CALIFORNIA STATE UNIVERSITY, NORTHRIDGE
THE GEOLOGY OF THE INNER BASIN MARGIN,
NEWPORT BEACH TO DANA POINT, ORANGE COUNTY, CALIFORNIA
A thesis submitted in partial satisfaction of the
requirements for the degree of Master of Science in
Geology
by
Stephen Charles Sterling
January, 1982
The Thesis of Stephen Charles Sterling is approved:
California State University, Northridge
ii
CONTENTS
Page
ABSTRACT
INTRODUCTION
1
General Statement
1
Geographic Setting
Bathymetric Setting
2
Previous Investigations
2
METHODS AND PROCEDURES
7
General Statement
7
Navigation
10
Velocity Analysis
10
Velocity Functions
11
Depth Migration
13
Ac know l edgemen ts
13
GEOLOGIC SETTING
15
REGIONAL STRATIGRAPHY
23
General Statement
23
Basement
23
Superjacent Rocks
26
Jurassic-Early Miocene
26
Middle to Late Miocene
27
Pliocene
32
Pleistocene
36
Holocene
37
SEISMIC STRATIGRAPHY
38
General Statement
38
iii
Page
Basement
38
r1i ocene
39
Pliocene
43
ONSHORE STRUCTURE
48
OFFSHORE STRUCTURE
52
General Statement
52
Faults
52
The Newport-Inglewood Fault Zone
52
Other Faults
58
Structural Highs and Lows
61
Correlation of Onshore-Offshore Geologic Features
63
NEOGENE EVOLUTION OF THE INNER BASIN MARGIN
67
General Statement
67
Pre-depositional Events
67
Neogene Events
69
Depositional History
69
Structural Evolution
73
SUMMARY AND CONCLUSIONS
75
REFERENCES
80
iv
LIST OF ILLUSTRATIONS
Page
Figure
l.
Location of study area
4
2.
Bathymetry of the inner basin margin
5
3.
Tracklines of common depth point seismic lines in the
study area
9
4.
Major structural blocks of the Los Angeles basin
17
5.
Location of geologic features referred to in text
19
6.
Composite sections showing regional correlation of units
24
7.
The major structurally high and low areas in the
basement surface
41
8.
Location of stratigraphic sequences that onlap or
downlap against the basement surface
47
9.
Structural provinces in the study area
54
10.
Earthquake epicenters, from 1933 to 1972, plotted
along the Newport-Inglewood structural zone
57
11.
Location of major faults displacing the basement
surface
60
12.
Apparent horizontal offset of geologic features along
the Newport-Inglewood structural zone
65
13.
Direction of sediment transport for upper Miocene
through lower Pliocene strata
72
Plates
Structure contour map on top of the basement schist
In pocket
II.
Structure contour map. on the top of the
Delmontian stage
In pocket
III.
Structure contour map on the top of the
Repettian stage
In pocket
I.
IV.
Structure contour map on top of an arbitrary reflector
In pocket
within the Plio-Pleistocene stratigraphic section
v
.,..
Plates
V.
VI.
Structure cross-sections: Oriented
perpendicular to the coastline
In pocket
Structure cross-sections:
to the coastline
In pocket
Oriented parallel
vi
ABSTRACT
THE GEOLOGY OF THE INNER BASIN MARGIN,
NEWPORT BEACH TO DANA POINT, ORANGE COUNTY, CALIFORNIA
by
Stephen Charles Sterling
Master of Science in Geology
Geological and geophysical data, which include common depth point
seismic profiles, velocity analysis displays, borehole and other
information, were used to study the structural evolution and Neogene
sedimentation of the inner basin margin between Newport Beach and Dana
Point.
Neogene time, as used in this study, includes the Miocene and
Pliocene epochs.
Using these data four seismic horizons were mapped in
the study area:
(1) top of the acoustic basement (top Catalina Schist);
(2) top of the Delmontian (?) benthic foraminiferal stage; (3) top of
the Repettian benthic foraminiferal stage; and (4) an arbitrary
reflector within the Plio-Pleistocene stratigraphic section.
Sedimentary rocks in the study area range from late Miocene to
Recent.
Late Miocene through Pliocene strata onlapped structurally
vii
high basement areas and downlapped structurally low basement areas to
the south-southeast.
The southerly direction of sediment transport
in the upper Miocene through Pliocene stratigraphic section from the
San Pedro Bay area to the study area suggests sediment was channeled
through the northwest-trending Wilmington graben.
were probably transported by density currents.
These sediments
In the study area,
strata accumulated on a basement surface in which structural highs
controlled or blocked sediment transport to the southeast.
South of Dana Point, sediment input from the northwest was blocked
by the basement high associated with the offshore San Joaquin ridge,
however, the strata in this area onlapped the basement ridge from the
north to northeast.
This north to northeast onlap involves strata
probably corresponding to the upper Miocene-lower Pliocene Capistrano
Formation.
Onlap to the offshore San Joaquin ridge from the north-
northwest continued through Pliocene time until Plio-Pleistocene strata
overlapped this structural high.
Major ridges, troughs, and numerous faults are present in the
surface of the basement Catalina Schist.
The relatively continuous
nature of these faults suggests that the area consists of a series of
north to northwest-trending fault blocks which move independently.
This is evidenced by differential displacement of the basement surface
along single fault traces.
Based primarily on basement structural
elements, the study area is divided into three structural provinces:
1.
Province I is located on the continental shelf and is
characterized by chaotic reflectors.
2.
Province II is the northwest portion of the area and is
characterized by north to northwest-trending faults and ridges in
viii
....
the basement surface.
3.
Province III is the southeast portion of the area and is
characterized by north to northeast-trending faults, ridges, and
troughs in the basement surface.
Faults in the study area are high angle normal.
Most of these
faults terminate within, or near the top of, the Repetto Formation.
A number of them have a thicker sedimentary section on their downthrown
side indicating that at least a portion of the displacement occurred
contemporaneously with sediment deposition.
The Newport-Inglewood structural zone extends offshore of Newport
Beach to southeast of Dana Point in a series of four right-stepping
en echelon fault segments.
Lateral offset along the Newport-
Inglewood zone, using assumed similar or related geologic features as
piercing points. has been right-lateral with an estimated horizontal
displacement of 4250 meters.
ix
I
INTRODUCTION
General Statement
The inner basin margin from Newport Beach to Dana Point is
located at the southernmost extent of the Los Angeles basin and forms
a portion of the northern flank of the San Diego trough.
Since Middle
Miocene time, this area has been the site of significant sedimentation
and tectonic activity.
No previous detailed investigations have been
completed in the study area.
The purpose of this investigation is,
then, to delineate structural and stratigraphic features and to
describe the geologic evolution of the area.
For this study, industry geophysical and geological data were
obtained including common depth point (COP) seismic profiles, post-plot
navigation sheets (shot point locations), velocity analyses, and
borehole information.
Both geological and geophysical interpretations
by the writer were limited to the use of the COP seismic profiles.
Offshore extrapolations of onshore geologic structures were hindered
due to the proximity of the offshore portion of the Newport-Inglewood
structural zone.
In the northern portion of the area interpretations
were aided by good borehole information.
Geographic Setting
The area of investigation is part of the southern California
Continental Borderland and encompasses nearly 360 square kilometers
{approximately 40 km x 9 km) along the inner basin margin, between
l
•
2
Newport Beach and Dana Point (Fig. 1).
Newport Beach is approximately
45 kilometers southeast of the city of Los Angeles along the southern
California coast.
Landward of the study area are the San Joaquin
Hills which define the eastern margin of the Los Angeles basin.
Directly offshore the ocean floor deepens into the northern end of
the San Diego trough.
The northernmost portion of the area overlies
the southern edge of the broad San Pedro shelf.
Bathymetric Setting
The southern California continental shelf typically is narrow.
The shelf southeast of the broad 25 kilometer wide San Pedro shelf
tapers to approximately 2 km in width and broadens to a width of
approximately 3.5 km near Dana Point (Fig. 2).
The edge of the
shelf generally is parallel to the coast, only diverging
significantly near the San Pedro-Newport submarine canyon area.
From
the shelf break, at approximately 100m below sea level, the
transition to a steep continental slope is abrupt.
Further offshore,
the continental slope rapidly grades into the basin apron and floor of
the San Diego trough.
Previous Investigations
A majority of previous investigations were concerned with
regional surveys of the entire California Continental Borderland.
Moore (1960, 1969) utilized seismic data with subbottom penetration to
evaluate geologic structures beneath the sea floor.
Western
Geophysical Company (1972) used common depth point seismic reflection
3
Figure 1.
Location of study area.
LOS
118° 00'
0-1
(~,
0
~k
~
SAN PEDRO
SHELF
',,
"',f,,,
,,
l{
'"-:,,..
'',
100m
SAN PEDRO
BASIN
-
33° 30'
":
0 km/
15
~·
SCALE 1:500,000
/
SAN CLEMENTE
~
ISLAND
';:)
L·---------~--~-----___.j
..j::>.
•
•
5
Figure 2.
Bathymetry of the inner basin margin
(from Vedder and others, 1976, sheet 3).
6
118° 00'
LOS
ANGELES
BASIN
'..:ll
-0 km
'
5
10
.J
SCALE 1:250,000
BATHYMETRIC CONTOUR
INTERVAL: 50 METERS
AREA
33° 30'
sao
7
and seismic refraction data to construct reflection-time structure
contour maps from Miocene rocks to the acoustic basement between
Palos Verdes and offshore of San Diego.
Ziony and others (1974)
reviewed published and unpublished data, supplemented by limited
field investigations, to study the recency of faulting along the
coastal portions of the Borderland.
Vedder and others (1974) used
subbottom seismic profiles, gravity and magnetic data, well and
shallow core information, published papers, and unpublished data to
describe the regional geologic framework of the Borderland.
North of the study area, in the Santa Monica and San Pedro
basins, Junger and Wagner (1977) used seismic reflection profiles and
bedrock samples to evaluate the geologic evolution of these areas.
Nardin and Henyey (1978) utilized seismic reflection profiles and
bedrock samples to study the late Pliocene through early Pleistocene
evolution of the Santa Monica and San Pedro shelves.
Rudat (1980)
assessed the Quaternary evolution of the San Pedro shelf using
reflection profiles and dart core data.
South of the Palos Verdes
Peninsula, Jahns and others (1971) described structural elements
along the continental shelf and Lee (1977) utilized seismic reflection
profiles in the Newport submarine canyon area to construct a tectonic
map and geologic cross sections.
METHODS AND PROCEDURES
General Statement
For this study, 340 kilometers of unmigrated time common depth
point (COP) seismic profiles were obtained from industry (Fig. 3).
8
Figure 3.
Tracklines of common depth point
seismic lines in the study area.
9
118° 00'
~
HUNTINGTON
BEACH
0 km
L
5
10
J
j
I
SCALE 1:250,000
LAGUNA
I
10
The profiles were collected on five separate surveys by four
geophysical service companies.
The surveys vary from 12 fold to 36
fold gathers (1200% to 3600% stack).
Four of the surveys used
airgun energy sources and a 100 Kj super sparker energy source was
used for one.
Borehole data were only available from the northern part of the
study area.
Using these data three reflectors corresponding to:
the
top of the acoustic basement (Catalina Schist), the top Delmontian (?)
and top Repettian benthic foraminiferal stages of Kleinpell (1938),
were correlated throughout the study area.
Navigation
Precision navigated
11
Shot point
11
location maps were furnished by
industry for all of the seismic tracklines.
Velocity Analysis
Velocity analysis, an integral part of seismic processing,
utilizes the variation of normal moveout with seismic record time to
determine velocity (Garotta and Michon, 1967; Telford and others,
1976).
In an ideal model of parallel horizontal layers, an RMS (root-
mean-square) velocity is determined to remove normal moveout and to
enhance primary reflectors (Sheriff, 1978).
RMS velocity may be
obtained from the equation:
Vrms 2=
v12t + v22t2 + V3 2t3 + ... + Vn 2tn
tl + t2 + t3 + ... tn
where:
Vl, V2, V3 ... Vn
are the interval velocities of the
11
respective horizontal layers, and
tl, t2, t3 ... tn
are the one-way travel times to their
respective horizontal layers (Dobrin,
1976).
During computer processing of an actual seismic line, a proper
stacking velocity is determined for enhancement of primary
reflectors.
This is accomplished by assuming a stacking velocity
and, then, normal moveout is examined for the offset of traces as a
function of time.
The degree of unison of all available traces to be
stacked is measured until the coherence of reflectors is a function
of stacking velocity and arrival time.
\~hen
this criteria for
reflector coherence is attained, the stacking velocity is considered
to ensure the proper amount of normal moveout removal to maximize the
stacking of primary events {Telford and others, 1976; Coffeen, 1978).
Stacking velocities, and RMS velocities, are determined from first
arrival times and are typically a few percent faster than
corresponding average velocities (Sheriff, 1973).
Velocity analyses
were completed at intervals of approximately one mile along each
seismic line.
Velocity Functions
Velocity analysis displays were digitized and individually
entered into a pre-written industry computer program designed to
calculate a least-squares-fit for linear increase of velocity with
depth.
This least-squares-fit is termed a velocity function.
relation is expressed by the equation:
The
12
(1 )
V(z)
where:
=
Vo + kz
V(z) = velocity at depth z below the datum plane
(instantaneous velocity).
Vo
= velocity at the horizontal datum plane.
k
= acceleration factor or velocity gradient.
z
= depth
(Dobrin, 1976; Telford, and others, 1976, Sheriff, 1973).
The assumption of a linear increase of velocity with depth is
more advantageous than a stepwise increase involving discrete layers.
Not only is it easier to handle mathematically, but is also a good
approximation of actual velocity functions in clastic basins
(Dobrin, 1976).
Using the calculated velocity functions, a time-depth
relationship was established (assuming that shot and receiver are
coincident and ray paths are vertical) by using the equation:
z
(2)
=
Vo/k (ekt/2- 1)
or
t = 2/k ln (1 + k/Vo z)
(3)
where:
t
=
two-way reflection time.
(other notation defined above).
The projection of the top basement Catalina Schist, top Delmontian
(?) and Repettian benthic foraminiferal stages onto unmigrated time
seismic profiles was accomplished by using the following procedure:
1.
Depths (z) of the top of the above formation and stage tops
were obtained from borehole data.
2.
Velocity at the horizontal datum plane (Vo) and the
acceleration factor (k) were calculated from the velocity analyses
adjacent to the boreholes by using the velocity function computer
..,.
13
program.
The program output is expressed by equation (1).
The
horizontal datum plane is water bottom and the given velocity (to be
used in calculations) of the water column is 4850 feet per second.
3.
The two-way reflection time to the formation and stage tops
was obtained by entering depth (z) and the calculated (Vo) and (k)
values into equation (3).
4.
Projection of the formation and stage tops onto the seismic
profiles was completed using ten different velocity analysis displays
adjacent to the boreholes to ensure proper location of the correlated
formation and stage tops on both strike and dip seismic profiles.
Depth Migration
Reflectors corresponding to the chosen formation and stage tops
were correlated within the study area.
The correlated tops from each
seismic profile were digitized and entered into a pre-written, two
dimensional depth migration industry computer program.
Velocity
functions, and their corresponding shot point locations, also were
entered.
Output from this program is individual plots of the seismic
profiles with the digitized tops migrated to their proper positions in
space and depth.
The migrated formation and stage tops on the output
plots were then checked for correlation misties at profile
intersections.
Acknowledgements
The writer would like to thank Dr. P. J. Fischer for suggesting
this project and for his guidance, Dr. H. Adams for critically
reading this manuscript and especially Dr. J. M. Evensen for the
14
critical reading of this manuscript and for his support and
encouragement.
The author is greatly indebted to Mr. W. J. Isaacs for his
consultation in the velocity research phase of this work.
The
computer assistance by Mr. R. J. Grabyan and Mr. L. J. Rothenberg and
the assistance in the determination of the correlated benthic
foraminiferal stage tops from borehole data by Mr. G. Blake is
appreciated.
The writer is grateful to E. Kutz and C. Hutchens for
typing, Mr. J. Donnelly for drafting, and Mr. M. C. Blundell for the
critical reading of this manuscript and for his support throughout
this project.
Above all, the author would like to thank Dottie Sterling for her
many hours of assistance, her patience and encouragement.
This project could not have been possible without the financial
support, computer use, and the release of proprietary data furnished
by Union Oil Company of California.
GEOLOGIC SETTING
The basement rocks of the Los Angeles basin have been divided
into a western blueschist facies complex and an eastern granitic
complex (Yerkes and others, 1965; Hill, 1971; Yeats, 1973).
The
basin contains a structural depression, parts of which have been sites
of discontinuous deposition since the Late Cretaceous with continuous
subsidence and predominantly marine deposition since middle Miocene
time (Yerkes and others, 1965).
Yerkes and others (1965) divided the Los Angeles basin into four
large structural blocks based on rocks of contrasting lithologies
(Fig. 4).
Contacts of adjoining blocks are flexures in basement rocks
or major fault zones.
The present study area is within the
southwestern block which extends from Santa Monica to Long Beach, and
southeastward into San Pedro Bay.
The basement rock is composed of
the western blueschist facies complex.
The sedimentary rocks of the
southwestern block are approximately 6250 meters thick and are
composed of chiefly marine sedimentary strata of middle Miocene to
recent age (Yerkes and others, 1965).
The Palos Verdes fault (Fig. 5) can be traced for more than 80
kilometers, extending offshore northwest and southeast of the Palos
Verdes Hills (Junger and Wagner, 1977).
Beneath the San Pedro shelf,
the fault is most commonly expressed by an abrupt dislocation between
folded strata and relatively undeformed layers, although locally it
appears as a wide fault zone (Nardin and Henyey, 1978).
Junger and
Wagner (1977) describe the southward continuation of the Palos Verdes
fault as the vertically distributed terminations of near-horizontal
15
16
Figure 4.
Major structural blocks of the Los Angeles
basin (from Yerkes and others, 1965).
17
NORTHWESTERN BLOCK
~
' '\
NORTHEASTERN BLOCK
,
' '\.
..
\...___./ LOS ANGELES
\
\
\
.\,
\
CENTRAL BLOCK
0 km
15
SCALE 1:500,000
'
' ' ~\:'.,~
~
' ,,
'o -.:,. ._
,/
BOUNDARY OF STRUCTURAL BLOCK
/
v
IS' ',:--'
.
'
'
J-v ' ' ,
'
<>J-
' '
'
'
-1-r-.
·r~
''-1
' ',
''
'
' '\
'
'/
...
/
')
/
18
Figure 5.
Location of geologic features referred to in
text. The offshore portion of the NewportInglewood structural zone is from this study.
All other features are from sources cited in.
LOS
118"
~
oo'
15
okrn
.<)
\)
I
,o
l
I
I
SCALE 1:500,000
'1(
0~
£.~
~<)
it-/
(1,
/1>
\
G')'
0
('lSI
./"<.
1>
/
(:>
SAN PEDRO
BASIN
-1~
'('"V
")>
',
&..0
(~
.>-
'
'
'
'
'
~~._,:a{)"''""'''It
~
',1/
&i-
' ',,v.
,y
1(.
Q
v1
(.IS'
1'
~
,,,,,,,,
'',,
\
,(:' \...
.....
'-0
j
.
20
beds of the Wilmington graben against the steeper dipping beds of the
Palos Verdes uplift.
To the south, the Palos Verdes fault extends to
the area adjacent to Lasuen Knoll.
Near San Pedro, this fault shows
late Pleistocene and possible Holocene tectonic deformation and
separations.
(Junger and Wagner, 1977; Nardin and Henyey, 1978).
The Wilmington anticline (Fig. 5) is another major fold,
approximately 30 kilometers in length, located eastward of the Palos
Verdes Hills (Junger and Wagner, 1977).
Its southeastern extent
underlies a portion of the northern San Pedro shelf.
The core of the
Wilmington anticline consists of Catalina Schist which is overlain by
as much as 3500 meters of Miocene and younger sediments.
This
northwest-trending anticline is complexly broken by northeast-trending
faults (Mayuga, 1970).
One of the major structural features in San Pedro Bay is the
Wilmington graben (Fig. 5).
The southwestern boundary of the graben
is the Palos Verdes fault zone and the northeastern boundary is a
discontinuous series of faults on trend with the onshore NewportInglewood fault zone.
Strata appear to be gently folded in the
Wilmington graben with a structural high appearing against the Palos
Verdes fault (Junger and Wagner, 1977).
The San Joaquin Hills, immediately landward of study area, form
a complexly faulted anticline, bordered by the Capistrano syncline to
the east (Fig. 5).
The stratigraphic sequence exposed contains
Paleocene through Holocene marine and nonmarine sedimentary rock,
locally cut by igneous intrusive rocks (Vedder, 1970).
The Newport-Inglewood fault zone is one of the dominant
structural elements in the Los Angeles basin.
This northwest-
21
southeast trending zone separates the southwestern and central
structural blocks of the Los Angeles basin.
The Newport-Inglewood
fault zone consists of cross-trending en-echelon anticlinal folds
and discontinuous faults (Yeats, 1973) characteristic of wrench-style
deformation (Harding, 1973).
Cumulative right-lateral strike-slip
displacement is approximately 3 kilometers (Yeats, 1973).
Several
workers continue this zone southward to the San Diego area (Emery,
1960; Barrows, 1974).
REGIONAL STRATIGRAPHY
General Statement
The relationship and distribution of lithologic units can be
grouped into two stratigraphic sections separated by the northwesttrending Newport-Inglewood fault zone.
To the southwest, Mesozoic
schist basement is overlain by a succession of marine and nonmarine
middle Miocene to Recent sedimentary rocks containing local igneous
intrusions.
Northeast of the Newport-Inglewood fault zone, Mesozoic
granitic basement underlies the Cretaceous to Recent succession of
marine and nonmarine sedimentary rocks and local intrusive igneous
rocks (Yerkes and others, 1965).
Figure 6 shows the regional
correlation of these rocks.
Basement
Basement rocks of the southern California Continental Borderland
consist of a western blueschist facies complex (Yerkes and others,
1965) and of metasedimentary rocks analogous to the Franciscan complex
of northern and central California (Crouch, 1981).
In the study area,
basement rocks are composed of Catalina Schist, which belong to the
western blueschist facies complex.
In middle Miocene time, an extensive Catalina Schist highland
west of, and subparallel to, the present coastline extended from
Santa Monica to Oceanside (Woodford and others, 1954; Yeats, 1973;
Stuart, 1979).
Exposures of Catalina Schist are present on the Palos
Verdes Hills uplift and on Santa Catalina Island (Woodford and
others, 1954).
Samples of Catalina Schist also have been obtained
from submarine dredge and core samples (Vedder and others, 1974) as
well as from clasts in the San Onofre Breccia (Stuart, 1976).
22
These
23
Figure 6.
Composite sections showing regional correlation
of units (from Yerkes and others, 1965;
Rudat. 1980).
My
California
I f."
Epoch
Verdes Uplift
San Jonquin Hills Area
'Nllmington Grnbcn
G~nthlc
U.P
Stnge
0
PLEISTOCENE!-
~~~~-_:~~'--~~
vn"t:E'-"~'~'"1'<
-- 'i-il'l-\-tJI~I-1>-~'<
f\~p-0\~~N..-·
"rPr:to FM
-.,._
REPETTO FM.
of.LMO~'~""N
5
T
u
0
N
0
z
w
~
I
w
z
MONTEREY SHALE
t..~Orlt-1\P..~'<
r~~~----
10
15
- -- --
t
.:f'() "'
<:i"
PUENTE FM.
MalBQO Mudstone
Valmonte Diatorn1te
Altamira Shale
0
N
1_J
:::>
\_\)lSI I>-~'<
;--.____
TOPANGA
SA~~-
- f>.tLI"Z.II>-~'<
---
ONOFRE-<::
BRECCIA
---
0
z
w
u
PUENTE FM.
<:(
u..
D
0
0
$:
20
30·-
60-
UPPER
90-
CRETACEOUS
CATALINA SCHIST
CATALINA SCHIST
CATALINA SCHIST
LOWER CRET
TO TRIASSIC
N
~
-~
"'
25
basement rocks typically consist of fine-grained chlorite-quartz
schist, chlorite-muscovite-albite-quartz schist, crossite-bearing
schist, chlorite-talc schist, quartz-chlorite-tremolite-lawsonite
schist, and meta-gabbro (Woodring and others, 1946; Yerkes and
others, 1965).
The Catalina Schist on the mainland has been correlated with the
type section that is exposed on Santa Catalina Island (Woodford, 1924).
Whole rock, blue amphibole, white mica, and hornblende potassium-argon
ages indicate that the schist on Santa Catalina Island was
metamorphosed 95 to 109 m.y.b.p. (Suppe and Armstrong, 1972).
Prior to
metamorphism, the protolith of the Catalina Schist consisted of mafic
volcanic rocks, conglomerate, graywacke, shale, and chert.
These are
similar in proportion to the unmetamorphosed portion of the Upper
Jurassic to Eocene Franciscan Formation of the Coast Range and are
considered to be equivalent to that formation (Woodford and others,
1954; Bailey and others, 1964).
In the Los Angeles basin, the basement rocks of the southwestern
block are composed of schist, which contrast sharply with the plutonic,
metasedimentary and volcanic Mesozoic basement rocks of the other
basinal blocks (Yerkes and others, 1965).
The basement rocks have been
divided into a western blueschist facies complex and an eastern granitic
complex (Woodford, 1925; Yerkes and others, 1965; Yeats, 1973), which
are separated by the Newport-Inglewood fault zone.
Tertiary rock units older than middle Miocene are not known to
occur in the southwestern block.
It is unknown whether the absence of
these rock units is the result of erosion or non-deposition.
Yerkes
and others (1965) suggested erosion because 4300 meters of Upper
26
Cretaceous to Oligocene rocks in the San Joaquin Hills probably
extended across the present Newport-Inglewood structural zone to the
southwestern block.
It also has been suggested that the Catalina
uplift may have occupied the western Los Angeles basin and shelf area
as early as Paleocene time (Reed and Hollister, 1936; Woodring and
others, 1946).
The Catalina uplift could have been covered with
Cretaceous sediments which were not eroded away until the end of
Miocene time, therefore delaying exposure of the Catalina Schist.
Yeats (1973), however, questioned whether pre-middle Miocene Strata
could be removed entirely by erosion with none of the Catalina Schist
having undergone erosion and subsequent deposition as sedimentary
rocks.
Yeats (1973) proposed that the Catalina Schist did not receive
sediment nor was subjected to erosion in pre-Miocene time.
The
depositional history and the age of rock units overlying basement
Catalina Schist in the study area are discussed in subsequent sections
of this paper.
Hill (1971) suggested that the Newport-Inglewood
structural zone represents a Mesozoic subduction zone that juxtaposes
basement rocks of contrasting lithologies .. This zone developed during
Cretaceous time and altered or subducted any pre-Tertiary rocks in the
southwestern block.
Superjacent Rocks
Exposures of Cretaceous through lower Miocene rocks are found in
two areas of the Los Angeles basin:
the Santa Monica Mountains and the
San Joaquin Hills-Santa Ana Mountains.
These rocks are not known to
occur within the southwestern block (Yerkes and others, 1965).
Jurassic - Early Miocene
In the Los Angeles basin, the lithologically varied Upper
Cretaceous rocks are chiefly marine.
Paleocene and Eocene rocks
27
comprise a marine and nonmarine section and the upper Eocene (?) to
lower Miocene rocks comprise a thick nonmarine red-bed section of
the Sespe Formation.
Sespe strata are overlain by, and interbedded
with, lower Miocene marine strata (Yerkes and others, 1965).
In the San Joaquin Hills, rocks of the Jurassic Bedford Canyon
Formation and of the lower Cretaceous Trabuco, Ladd, and Williams
Formations consist of sandstone, siltstone, and conglomerate beds.
The Paleocene Silverado Formation contains marine and nonmarine
coarse-to-medium-grained sandstone with conglomerate and claystone.
The Eocene Santiago Formation consists of marine and nonmarine
medium-to-coarse-grained sandstone with interbedded conglomerate,
fine-grained sandstone, and claystone beds.
Upper Eocene to lower
Miocene rocks unconformably overlie Eocene rocks and comprise the
Sespe and Vaqueros Formations.
These rocks are unconformably overlain
by the early Miocene Vaqueros Formation.
The Vaqueros Formation
consists of marine siltstone, arenaceous siltstone, and fine-tocoarse-grained siltstone (Vedder, 1970; Tan and Eddington, 1976).
Middle to Late Miocene
The sedimentary rocks of the southwestern block are approximately
6250 meters thick and are composed predominantly of marine sedimentary
strata of middle Miocene to recent age (Yerkes and others, 1965).
Marked differences in rates and amounts of subsidence have produced
pronounced lateral variations in thickness and lithology of these
rocks.
Contemporaneous faulting and folding, and local erosion, have
produced regional and local unconformities, disconformities and
stratigraphic discontinuities across faults (Yerkes and others, 1965).
28
In the Los Angeles basin, the middle Miocene rocks form a
varied succession of volcanic and marine sedimentary rocks.
In the
western portion of the basin middle Miocene strata unconformably
overlie the Catalina Schist basement (Yerkes and others, 1965).
In the Palos Verdes Hills middle Miocene strata lie on
Catalina Schist and are overlain by upper Miocene strata (Woodring
and others, 1946).
The Monterey Shale is the oldest middle Miocene
formation exposed on the Palos Verdes Hills.
Outcrops of Monterey Shale are present on the San Pedro shelf
(Crouch, 1954; Moore, 1954; Junger and Wagner, 1977; Nardin and
Henyey, 1978; Rudat, 1980).
Miocene rocks thought to belong to the
Monterey Formation have been dredged along the inner shelf offshore
of Palos Verdes and from the outer Los Angeles Harbor (Moore, 1954).
Rocks typical of the Monterey Shale (described as hard, porcelaneous,
laminated, rhythmically banded shale) were dredged from the westcentral area of the San Pedro shelf by Moore (1954).
Middle and upper Miocene siliceous shale and mudstone have been
sampled along the crest of the Palos Verdes uplift as well as along
its flank (San Pedro Escarpment).
Seafloor samples indicate that
the lithology of Miocene rocks differs in various parts of the area
(Junger and Wagner, 1977).
Upper Miocene strata of the Los Angeles basin form a widespread
section of very fine-to coarse-grained, marine sedimentary rocks and
local intrusive igneous rocks.
Upper Miocene sediments onlap the
western basement from the northeast (Yerkes and others, 1965).
In
the southeastern part of the Palos Verdes uplift, Miocene sediments
buttress against the basement and pinch out against Miocene volcanic
29
or basement rocks on the northeast side of the San Pedro basin (Junger
and Wagner, 1977).
This pattern of sedimentation indicates that the
subsidence of the Los Angeles basin in upper Miocene time began
southeast of the southwestern block and spread north and west (Yerkes
and others, 1965).
Woodring and others, (1946) reported that
subsidence and continuous deposition occurred in the Palos Verdes
Hills area until early Pliocene time.
The Wilmington oil field contains a thin middle Niocene section
and a thick upper Miocene section (Mayuga, 1970).
A majority of the
strata belong to the upper Miocene Puente Formation, with a thin
underlying section of the middle Miocene Topanga Group present.
The
Topanga Group along the crest of the Wilmington anticline consists of
alternating layers of coarse-grained, poorly sorted sandstone and
distinctly stratified shale (Mayuga, 1970).
The upper Miocene Puente
Formation consists of poorly sorted, fine- to coarse-grained
sandstones interbedded with claystone, siltstone, shale and a few hard
sandstone members (Mayuga, 1970).
A majority of the oil sands in the
Puente Formation, as well as portions of the Repetto Formation, show a
southwest direction of transport (Truex, 1974).
Along Newport Beach, the upper Miocene section has been
correlated with the lower Mohnian Puente Formation (Hunter and Allen,
1956; Ingram, 1968).
The Puente Formation generally is a fine to
silty arkosic san.d with an upper massive, silty brownish-gray shale
containing thin silt seams, sand, and hard chert lenses (Hunter and
Allen, 1956; Ingram, 1968).
Overlying the shale sequence is a
characteristic bentonitic marker bed, the top of which marks an
30
unconformity between the late Mohnian and Delmontian (?) stages
(Hazenbush and Allen, 1958; Ingram, 1968).
The validity of the benthic foraminiferal Delmontian stage is
questionable.
Pierce (1972) suggests that the Delmontian stage may be
a facies of the Mohnian stage as evidenced by the finding of
characteristic Delmontian fossils in rocks of the Mohnian stage as
well as the finding of Mohnian fossils in rocks of the Delmontian
stage.
Furthermore, the Delmontian stage may transgress the Miocene-
Pliocene boundary within the upper portion of the Monterey Formation
(Berggren and Van Couvering, 1974; Boellstroff and Steineck, 1975).
Surface investigations have shown the middle to upper Miocene
and upper Miocene to lower Pliocene rocks along Newport Bay belong to
the Monterey and Capistrano Formations, respectively (Vedder and
others, 1957; Vedder, 1970; Ingle, 1972).
Outcrops of the Monterey
Formation consist of silty and diatomaceous shales, clay and cherty
shale, limestone lenses, and turbidite sand.
Comparison of the middle
to upper Miocene Monterey and the upper Miocene Puente Formations
indicate that the Puente Formation generally is composed of coarsergrained material (Woodford and others, 1946; Woodring and others, 1946;
Hunter and Allen, 1956; Ingram, 1968).
The Capistrano Formation
conformably overlies the Monterey Formation and consists of
siltstone, channel deposits, and interbedded white diatomaceous shale
(Ingle, 1972).
In the San Joaquin Hills, the stratigraphically lowest formation
of middle Miocene age is the Topanga Group.
Contact with the
underlying Vaqueros Formation generally is gradational.
31
The middle Miocene marine and nonmarine San Onofre Breccia
unconformably overlies the Topanga Group in the San Joaquin Hills.
The upper portion is locally intertongued with Monterey Shale (Vedder,
1970).
Stuart (1975, 1979) and Vedder (1971) have indicated that the
San Onofre Breccia in the type region most likely is restricted to the
upper Relizian and lower Luisian stages.
Locally, the San Onofre
Breccia contains sandstone, siltstone, and conglomerate, but
dominantly consists of a distinctive coarse clastic unit composed
chiefly of Catalina Schist detritus (Tan and Edgington, 1976).
This
unit is very lenticular and may be as thick as 900 meters near South
Laguna.
The San Onofre Breccia thins northward (Vedder, 1970;
Stuart, 1979) to the point where no San Onofre Breccia is found in the
Los Angeles basin north and west of Sunset Beach (Yeats, 1973).
Vedder
(1970) concludes that the bulk of the San Onofre Breccia was derived
from exposures of Catalina Schist to the south and west near the
present trace of the Newport-Inglewood structural zone.
According to
Junger (1974), the primary source terrane was a ridge, presently
buried, that extended for about 30 kilometers south\vard from a point
about 9 kilometers offshore of Laguna Beach.
The San Onofre Breccia formed as a series of clastic wedges
derived from uplifted Mesozoic metamorphic rocks.
These clastic
wedges were deposited as alluvial fan, fan-delta, and shallow marine
deposits.
The most complete sequences of alluvial fan and fan-delta
deposits are exposed between Oceanside and Laguna Beach (Stuart, 1979).
Overlying the San Onofre Breccia in the San Joaquin Hills is the
Monterey Shale.
The contact with the underlying San Onofre Breccia
is locally gradational, but generally is unconformable (Vedder, 1970).
32
The upper Miocene to lower Pliocene rocks of the San Joaquin
Hills belong to the Capistrano Formation which is composed
predominantly of mudstone and the prominently sandstone Oso member.
The Capistrano Formation unconformably overlies older rocks in the
western portion of the Capistrano syncline but elsewhere it is
gradational with the Monterey Shale.
Igneous dikes, sills, and flows of Miocene age (probably limited
to the last half of the epoch) disrupt the sedimentary section in the
area west of Laguna Canyon in the San Joaquin Hills (Vedder, 1970).
In the Capistrano Embayment, the Monterey Formation has nearly a
uniform thickness and lithology and is conformably overlain by the
Capistrano Formation.
These two formations are differentiated by the
change of the thin bedded Monterey shale to the indistinctly bedded
siltstone and fine-grained biotite-rich sandstone of the Capistrano
Formation (Ehlig, 1979).
On the west side of the embayment, the
lower part of the Capistrano Formation contains sediments derived
from the erosion of strata exposed in the San Joaquin Hills.
This
formation was deposited at bathyal depths (Ehlig, 1979).
Pliocene
In the central portion of the Los Angeles basin, sedimentation
continued uninterrupted through late Miocene into Pliocene time.
This contrasts with the periphery of the basin where uplift at the
beginning of Pliocene time resulted in local unconformities (Yerkes
and others, 1965).
The Pliocene rocks comprise a repetitive succession of
alternating fine to coarse clastic marine strata, which range in
33
thickness from 3000 to 4300 meters (Woodford and others, 1954;
Yerkes and others, 1965).
Pliocene rocks of the southwestern block of the Los Angeles basin
have been assigned to the Repetto and Pico Formations.
The Repetto
Formation is not a formalized name, but is used to remain consistent
with existing literature and the use of Pico Formation is actually
restricted to areas outside the Los Angeles basin (Wissler, 1943;
Woodring and others, 1946; Yerkes and others, 1965; Junger and
vJagner, 1977).
The Repetto Formation on the Palos Verdes Hills is represented by
soft, massive, glauconitic siltstone containing Catalina Schist
detritus apparently derived from the south or west.
A majority of the
sediment, however, was derived from the north (Woodring and others,
1946).
The Repetto Formation in the Los Angeles basin and accumulated in
seas as deep as 1829 meters (Woodring and others, 1946; Ingle, 1967).
Strata of the lower Pliocene Repetto Formation have been reported
on the north slope of the San Pedro basin by Emery and Shepard {1945),
Moore (1954), and Jennings (1962).
Pliocene rocks occur locally along
ridges and slopes of San Pedro Basin but are covered by younger
sediments in the basin proper (Junger and Wagner, 1977).
Junger and
Wagner (1977) established a relation of the Offshore Pliocene
stratigraphic sequence to the underlying and overlying stratigraphic
sequences by correlation of unconformities observed in the offshore
basins with those described in the literature.
Seismic profiles show
a thin layer of sediment forming a dip slope and lying unconformably
on an erosional surface of folded upper Miocene strata.
Moore (1954)
34
described rocks of the Repetto Formation obtained from dredge hauls on
the northern San Pedro shelf as massive, angular, olive-colored soft
siltstone containing hard sandstone and mudstone concretions.
Rudat
(1980) recognized a seismic unit characterized by a lack of distinct
bedding reflectors in the vicinity of the San Pedro Sea Valley and the
San Gabriel Submarine Canyon suggesting the massive lithology of the
Repetto Siltstone.
This seismic unit is not deformed and rests
unconformably on folded Neogene rocks.
Junger and Wagner (1977)
propose that the undeformed unit is the earliest post-Miocene strata
in the San Pedro basin deposited prior to the steepening of the basin
flanks.·· Hov.Jever, Nardin and Henyey (1978) show deformed Repetti an
strata beneath the outer shelf in San Pedro Bay.
In San Pedro basin, sediments .buttress against Miocene rocks on
the basin flanks and the deeper sediments show growth structure
caused by contemporaneous sedimentation and subsidence (Junger and
Wagner, 1977).
Other buttress unconformities associated with
accelerated subsidence have been recognized by Junger and Wagner
(1977).
These are the unconformity at the top of the Repetto onshore
and an intra-Repetto unconformity correlated with the HuntingtonSunset Beach coastal area.
Late Pliocene basin sediments (the Pico
Formation) buttress against the basin flank, indicating that strata
higher on the flank have been uplifted prior to the deposition of the
late Pliocene sediments (Junger and Wagner, 1977).
In the Wilmington oil field Pliocene strata (representing both
the Repetto and Pica Formations) conformably overlie the upper Miocene
Puente Formation (Mayuga, 1970).
The Repetto shale beds are soft and
poorly indurated, brown to greenish gray, and grade to very micaceous
35
siltstone toward the upper part of the formation.
The Pico
Formation unconformably overlies the Repetto Formation and consists of
a series of sand and siltstone strata, with some claystone and hard
shale beds (Mayuga, 1970).
Faults in the offshore portion of the
oilfield do not appear to extend above the Repetto Formation (Junger
and Wagner, 1977).
Allen and Hazenbush (1957) reported unconformities at the top of
the Miocene Puente Formation and within and at the top of the Repetto
Formation in the Sunset Beach oil field.
A majority of the faults
terminate at the Miocene-Pliocene unconformity or at the unconformity
within the Repetto.
In the Huntington Beach oil field, Hazenbush and
Allen (1958) place erosional unconformities between the Miocene Puente
Formation and the lower Pliocene Repetto Formation, between the
Pliocene Repetto and Pica Formations, and within the Pico Formation.
A majority of the faults in this oil field terminate within the
Repetto Formation.
Lee (1977) mapped seismic reflectors offshore of Newport Beach
and the seismic profiles show an apparent northward dip and a
southwestward thinning of strata towards a basement high.
contact between the basement and
~1i ocene
The
reflectors, and between the
Miocene and Pliocene reflectors show an angular relationship,
indicating an angular unconformity exists between the
corresponding strata.
The fine-grained clastic rocks of early to late Pliocene age near
Newport Bay have been assigned to the Fernando Formation.
This
formation is faulted against, or rests unconformably on, the
Capistrano Formation (Vedder, 1970).
36
Marine and nonmarine sedimentary rocks of late Pliocene age which
unconformably overlie the Monterey Shale and Capistrano Formation in
the central part of the Capistrano syncline are assigned to the
Niguel Formation.
Pleistocene
During early Pleistocene time subsidence occurred in the
southwestern block of the Los Angeles basin and as much as 305 meters
of coarse marine sediments were deposited.
At the end of early
Pleistocene time a majority of the southwestern block was only
slightly submerged and a series of shoals may have existed along the
Newport-Inglewood structural zone (Yerkes and others, 1965).
The Lower Pleistocene rocks of the Los Angeles basin comprise a
succession of marine silt, sand, and gravel.
Exposures occur in the
southwestern block, in several of the low hills and mesas along the
Newport-Inglewood structural zone, and in portions of the central
block (Yerkes and others, 1965).
Upper Pleistocene deposits consist of marine terraces, nonmarine
terrace cover, nonmarine fluvial and lagoonal deposits, and probable
stabilized dune deposits.
These deposits are widely exposed in the
Los Angeles basin (Yerkes and others, 1965).
In the Palos Verdes Hills, lower Pleistocene deposits have been
assigned to the San Pedro Formation and unconformably overlay the
Monterey Shale or, less cowmonly, the Repetto Formation (Woodring
and others, 1946).
Upper Pleistocene marine sand and gravels that occur as terrace
deposits on the Palos Verdes Hills belong to the Palos Verdes Sand
(Woodring and others, 1946).
37
Junger and Wagner (1977) suggest that the base of the cross
bedding in the uppermost part of the stratigraphic sequence in San
Pedro Bay is the base of the Pleistocene.
These offshore crossbedded
deposits extend to the shelf edges where foreset beds continue into
the basins as slope deposits.
Rudat (1980) mapped several middle to
late Pleistocene units in the Wilmington Graben which are believed
to be correlative with the Palos Verdes Sand.
In the San Joaquin Hills area, limited exposures of early
Pleistocene sandstone, conglomerate, and siltstone beds belong to the
San Pedro Formation.
Late Pleistocene rocks include marine and
nonmarine terrace deposits (Vedder, 1970).
Holocene
Holocene deposits in the onshore region include alluvial and
modern stream deposits, sediments on flood plains, beaches,
embayments, and dunes (Yerkes and others, 1965;
Vedder~
1970).
Offshore Holocene deposits have been described by Rudat (1980).
SEISMIC STRATIGRAPHY
General Statement
Good borehole data was obtained in the area offshore of Newport
Beach to aid in the correlation of offshore stratigraphic sequences
within the study area.
Correlations of post-basement strata are based
on Kleinpell •s (1938) benthic foraminiferal stages (borehole data
references only benthic foraminiferal stages).
It is apparent that
provincial benthic foraminiferal stages can be time-transgressive as
well as affected by tectonically or climatically induced environmental
changes (Ingle, 1967; Bandy, 1972).
However, the use of benthic
foraminiferal stages for local correlations in the study area probably
is valid because the paleobathymetry of the upper Miocene and lower
Pliocene depositional environments appears to be uniformly deep water.
Basement
The basement rocks in the northern extent of the study area are
known to be composed of Catalina Schist (from borehole data) and
therefore belong to the western blueschist facies complex of the
southern California Continental Borderland.
The high-continuity and
high-amplitude doublet reflector (Sheriff, 1973; Sangree and Widmier,
1977; 1979) corresponding to this basement surface is correlated
approximately 33 kilometers to the south.
The distinctive seismic
signature of this reflector is consistent throughout the area.
Below
the top of the basement, reflectors are chaotic, indicating a near
total reflection of energy from the basement surface.
38
39
The basement surface, as shown by Plate I, is cut by numerous
faults with varying magnitudes of vertical displacements.
This surface
ranges from 1000 to 3150 meters below sea level with the major
structurally high area located 4.3 kilometers southwest of Dana Point
(named the offshore San Joaquin anticline by Western Geophysical
Company (1972) but will be referred to as the offshore San Joaquin
ridge) and a structurally low area (the offshore south Newport trough)
located 7.3 kilometers south of Newport Harbor (Fig. 7).
The
basement reflector corresponds to the acoustic basement (Horizon C)
mapped by
~Jestern
Geophysical Company (1972).
The contoured
unmigrated time values utilized by Western Geophysical Company (1972)
in the area offshore of Dana Point are equivalent to the unmigrated
time values digitized from seismic profiles by the writer.
~1i ocene
The lowest correlated reflector above the basement surface in the
study area corresponds to the top of the Delmontian (?) benthic
foraminiferal stage (Plate II).
This reflector shows an angular
relationship with underlying reflectors in the area offshore of
Newport Beach, and is considered to be equivalent to the MiocenePliocene unconformity recognized onshore.
Lee (1977) also reported
this angular relationship as the unconformable contact between
Miocene and Pliocene strata.
The middle Miocene San Onofre Breccia was not encountered by the
boreholes offshore of Newport Beach.
It is probable, however, that
this formation is present in the study area.
Seismic profiles east of
40
Figure 7.
The major structurally high and low
areas in the basement surface.
41
H
1
0
km
SCALE
5
10
1:250,000
OFFSHORE
SOUTH
NEWPORT
RIDGE
30'
OFFSHORE
SAN
JOAQUIN
RIDGE
42
the offshore San Joaquin ridge show a high-amplitude reflector which
may be the top of this formation.
Hunter and Allen (1956), Hazenbush and Allen (1958), and Ingram
(1968) stated that the upper Miocene section along Newport Beach is
correlative with the Puente Formation.
However, Lee (1977) reported
that borehole data offshore of the Santa Ana River and southwest of
the Newport-Inglewood structural zone indicate the upper Miocene
strata belong to the
~1onterey
Formation.
Core descriptions from Lee
(1977) indicate a fine-grained lithology, mostly shale, not typical of
the onshore section.
Throughout the study area pre-Pliocene reflectors
are characteristically discontinuous (hummocky clinoforms?) (Mitchum
and others, 1977).
This suggests that the upper Miocene strata in the
study area belong to the Puente Formation because the well bedded
character of the upper Miocene Monterey Shale should appear as
continuous to semi-continuous, parallel to subparallel reflectors.
To
clarify the question of the proper formation to assign the upper
Miocene strata, additional borehole data is necessary.
In addition, a
facies transition from the Monterey Formation to the coarser Puente
Formation also may occur southward from the San Pedro shelf area.
Upper Miocene sediments filled the structurally low areas in the
basement surface from the north to northwest.
This south to
southeast direction of sediment transport is shown by the onlapping
sequences of strata against the north flank of the offshore south
Newport ridge and the west flank of the offshore San Joaquin ridge.
Additional evidence for this transport direction is the downlapping
sequ~nces
of strata observed on the south flank of the offshore south
Newport ridge and in the offshore south Newport trough.
Strata of
43
undetermined age onlap the east flank of the offshore San Joaquin ridge
from the north to northeast.
Truncation of upper Miocene strata occurs
along the northeast-trending offshore south Newport fault located
approximately 9.2 kilometers south of Newport Harbor.
The thickness of upper Miocene strata varies from less than 50
meters to greater than 1000 meters (vertical isochore values, not true
thickness).
Major changes in thickness are controlled by the basement
surface (i.e. greatest thickness on down dropped blocks).
An
exception to this is in the offshore south Newport trough where strata
thin due to downlap prior to truncation against the offshore south
Newport fault.
Upper
r~iocene
strata commonly are cut by faults (Plates II, V, VI).
The faults predominantly are high angle normal and originate in
basement rock.
Subsidence of a number of basement fault blocks is
contemporaneous with sediment deposition as evidenced by faults with
thicker sedimentary sections on their downthrown side.
Pliocene
The reflector correlated within the Pliocene stratigraphic
section is the top of the Repettian benthic foraminiferal stage
(Plate III).
This reflector is characteristically high-continuity and
variable-amplitude and is relatively undisturbed, except by the
offshore south Newport fault where it is displaced vertically
approximately 200 meters.
The sequence of reflectors below the top of the Repettian stage
characteristically are parallel to subparallel, high-continuity with
44
generally high amplitude.
The outstanding feature of these reflectors
is their marked parallelism.
Offshore of Newport Beach, Repettian strata unconformably overlie
steeper dipping upper Miocene Delmontian strata.
To the southeast,
the Repettian strata appear to parallel the underlying upper Miocene
strata.
In the vicinity of the offshore south Newport trough, the
Repettian strata onlap the more gentle dipping upper Miocene strata
from the northwest.
The onlapping nature of the Repettian strata
continues to the southeast against the basement surface of the
offshore San Joaquin ridge.
The inability to recognize the angular
unconformity between Miocene and Pliocene strata in certain areas
may be the result of the limited resolution of the seismic profiles or
the contact actually may be locally conformable to disconformable.
The Repetto Formation gradually thickens to a maximum of
approximately 850 meters in the offshore south Newport trough.
To the
southeast, Repettian strata onlap the offshore San Joaquin ridge
and eventually thin to a zero thickness (the zero edge is located
approximately 6 kilometers offshore of Laguna Beach and generally
trends north-south).
Varying stratigraphic thicknesses across some
faults indicate displacement occurred contemporaneously with
deposition.
A majority of the faults, which are continuations of
those originating in basement rock, terminate within or at the top of
the Repetto Formation.
Reflectors within the middle to upper Pliocene strata belong to
the Pico Formation.
Reflectors are variable-continuity, variable-
amplitude, parallel to subparallel and are subparallel to the
reflectors associated with the underlying Repetto Formation.
Strata of
45
the Pica Formation dip to the southeast toward the offshore south
Newport trough and onlap the basement surface of the offshore San
Joaquin ridge from the north to northwest.
Onlap of this basement
surface by the post-Repettian strata continues to the southeast until
the strata completely overlap this basement high.
Plate IV shows the
structure along the top of an arbitrary reflector within the upper
Pliocene to Pleistocene stratigraphic section that overlaps the
offshore San Joaquin ridge.
Thickness of the post-Repettian strata
ranges from approximately 500 to 1600 meters.
In summary, the major basement structural highs impaired or blocked
sediment transport during the deposition of the overlying strata.
Upper Miocene through Pliocene strata buttress (onlap) against the
flanks of these structural highs, predominantly from the north to
northwest, and locally, upper Miocene strata drape off (down1ap) the
basement surface to the southwest.
On1ap of strata against the
eastern flank of the offshore San Joaquin ridge from the north to
northeast is observed on seismic profiles as well.
The areas of
onlapping and downlapping stratigraphic sequences are shown in Fig. 8.
46
Figure 8.
Location of stratigraphic sequences that
onlap or downlap against the basement
surface.
47
118°00'
0
km
5
SCALE
10
1:250,000
DIRECTION OF
ONLAP/DOWNLAP
33°
PT.
ON LAP
30'
ONSHORE STRUCTURE
The structural grain of the southern California Continental
Borderland and the Peninsular Ranges is characterized by northwestsoutheast-trending folds and faults (Emery, 1960; Moore, 1969; Vedder,
and others, 1974; Junger, 1976).
These northwest-southeast-trending
features are bordered or truncated on the north by the east-west
structural grain of the Transverse Ranges.
The major structural element in the study area is the offshore
extension of the northwest-southeast-trending Newport-Inglewood
structural zone.
In the Los Angeles basin, the Newport-Inglewood
structural zone is characterized by a belt of northwest-southeasttrending, en echelon faults and subparallel west-northwest-trending
folds which extend from Beverly Hills to Newport Beach.
Reed and
Hollister (1936) summarize early investigations and suggest that the
en echelon structural character indicates that a basement or master
fault exists along which dextral shearing stresses are operative.
Basement contrasts on either side of the zone tend to support the
master fault hypothesis.
The NevJport-Inglevmod structural zone is
considered by most workers to be a major tectonic boundary separating
Catalina Schist (western blueschist facies complex) from predominantly
granitic basement (eastern granitic complex) (Yerkes and others, 1965;
Hill, 1971).
The placement of contrasting basement lithologies along
this zone occurred between Late Cretaceous and middle Miocene time
(Yerkes and others, 1965).
The Newport-Inglewood structural zone separates the Los Angeles
basin's southwestern and central structural blocks.
48
To the northwest,
49
the zone is terminated against, or merges with, the east-northeasttrending Santa Monica fault zone.
At its southeast end, the zone
trends offshore of the San Joaquin Hills (Yerkes and others, 1965).
This structural trend is a zone of complex faulting and related folding.
It contains west-trending reverse faults, north-trending normal faults,
northwest-trending right-lateral en echelon strike-slip faults, and
right-handed en echelon anticlinal folds (Yeats, 1973; Harding, 1973).
The development of the structural style of the Newport-Inglewood
structural zone has been attributed to strike-slip deformation
(Barrows, 1974).
Early investigators (Eaton, 1923; Ferguson and Willis,
1924) noted that lateral movement was responsible for the formation of
the en echelon anticlinal structures.
Moody and Hill (1956) recognized
that various faults associated with the structural zone are not a part
of a single clear-cut faul,t trace, but
in a narrow zone.
rather~
they are parallel faults
Harding (1973) stated that the "parallel faults" in
different parts of the Newport-Inglewood structural zone demonstrate
different directions, magnitudes, and histories of displacement.
He
attributed the structural trends to wrenching and used the NewportInglewood structural zone as an example of a wrench zone of small
displacement analogous to experimentally produced structural patterns
produced in model studies by Wilcox and others (1973)
The amount of right lateral displacement along the NewportInglewood structural zone is controversial.
The anticlines associated
with Dominguez Hill, Baldwin Hills, and Signal Hill have displacement,
as measured across fold axes or on flank bulges, that range from 750
to 1980 meters (Harding, 1973).
meters of dextral offset.
Wright and others (1973) suggest 1220
Large scale right lateral separation of as
50
much as 3000 meters also has been suggested (Yerkes and others, 1965;
Hill, 1971; Yeats, 1973).
much as 1220 meters.
Vertical separation of basement rock is as
This displacement progressively decreases in
younger strata (Yerkes and others, 1965).
A northwest-southeast compression and the propagation of basement
anisotropies into overlying strata along the present trace of the
Newport-Inglewood structural zone began at the end of Miocene time.
However, localization of shear strain and deformation along the zone
began during the initiation of the Pasadenan orogeny in late Pliocene
time (Yeats, 1973).
An offshore continuation of the Newport-Inglewood structural zone
has been shown by many authors (Tabor, 1920; Eaton, 1933; Emory, 1960;
Yerkes and others, 1965; Morton, 1973; Jennings, 1975; Rodgers, 1979).
Hill (1971) suggested that the
~ctive
fault zone does not extend south
of Newport Beach, rather, a much older Cretaceous fault zone extends
south to Baja California.
On the basis of seismic reflection profiles
and active seismicity, others have suggested the (active?) fault zone
extends south to San Onofre (Western Geophysical Company, 1972;
Fischer and others, 1979; Tieken, in prep.).
Some writers continue
this zone south to the San Diego area (Emery, 1960; Barrows, 1974)
whereas others suggest a connection between the Newport-Inglewood fault
zone and the Rose Canyon fault in San Diego (Corey, 1954; Moore, 1972;
Kennedy, 1975; Moore and Kennedy, 1975; Greene and others, 1979).
A major onshore structural feature adjacent to the study area is
the complexly faulted anticline of the central San Joaquin Hills.
The
anticlinal structure is defined by the regional bedding dips of the
Topanga Formation (Tan and Edgington, 1976).
The dominant structural
51
control is faulting, not folding, since homoclinally dipping beds
generally are present in fault blocks.
The exception is the Monterey
Shale where folding is apparent (Tan and Edgington, 1976).
The San Joaquin Hills are transected by numerous northwesttrending faults including the Pelican Hill, Shady Canyon, and the
Laguna Canyon fault.
Also present are north and east-trending faults
(the northern portion of the Laguna Canyon fault and the Temple Hill
fault) (Tan and Edgington, 1976).
The Pelican Hill fault zone extends from Newport Bay to northwest
Laguna Beach.
This fault displays vertical and inferred lateral
movements that were recurrent in Miocene and Pliocene time (Vedder,
1970).
Furthermore, higher-level Pleistocene marine terraces are
displaced by this fault zone indicating that it moved during Late
Quaternary time (Tan and Edgington, 1976).
The greatest vertical
stratigraphic separation along the fault is 760 meters (Tan and
Edgington, 1976).
Southeast of the San Joaquin Hills is the Capistrano Embayment.
This embayment is a flat-bottomed trough, which is bounded by the
Peninsular Ranges on the east and the San Joaquin Hills on the west and
extends from the coast near San Juan Capistrano to the Santa Ana
Mountains (Ehlig, 1979).
The trough was formed by down-warping along
the east side of the San Joaquin Hills and downward displacement along
the west side of the Cristianitos fault.
The trough began to form
approximately 10 m.y. ago and was a depocenter for the upper Miocene
to lower Pliocene Capistrano Formation (Ehlig, 1979).
OFFSHORE STRUCTURE
General Statement
The study area is divided into three structural provinces based
primarily on basement structural elements (Fig. 9):
1.
Province I is located on the continental shelf landward of
the seaward margin of the Newport-Inglewood structural zone, and is
characterized by chaotic reflectors (because of which the basement
rock type cannot be determined).
2.
Province II is the northwest portion of the area and is
characterized by north to northwest-trending faults and ridges in the
basement surface.
3.
Province III is the southeast portion of the area and is
characterized by north to northeast-trending faults, ridges, and
troughs in the basement surface.
Faults
The Newport Inglewood Fault Zone
The major fault in the study area is the Newport-Inglewood fault
zone (Fig. 9).
This tectonically active structural zone has a maximum
width of approximately 5 kilometers in the region extending from
Huntington Beach to Newport Beach (Morton, 1973).
Numerous faults show
surface to near-surface displacements and the Long Beach earthquake of
1933 is generally attributed to movement of this fault zone.
According
to Harding (1973), the structural style of the zone is the result of
wrench-style deformation.
52
53
Figure 9.
Structural provinces in the study area.
54
118~
00'
k m
0
SCALE
NEWPORT
X
;<
\
5
1:250,000
RIDGE
TROUGH
FAULT
10
'
55
The Newport-Inglewood structural zone was mapped by the writer
offshore of Newport Harbor and found to continue southeastward past
Dana Point (Plate I).
Lee (1977) mapped offshore fault splays within
this zone from Huntington Beach to the Newport Beach River.
Within
the study area the Newport-Inglewood structural zone is characterized
by chaotic reflectors (discontinuous and discordant) which are the
result of severely deformed rock units.
reflectors across the zone was made.
No attempt to correlate
The maximum mappable width of the
offshore continuation of the zone is 3 kilometers, however, the seismic
coverage was insufficient to delineate the landward margin of this zone.
The uppermost reflectors in the Plio-Pleistocene sequence appear
to be disrupted within the offshore portion of the Newport-Inglewood
structural zone.
Fischer and others (1979) utilized 3.5 kHz high
resolution profiles to show late Pleistocene, Holocene, and sea floor
displacement in this offshore portion.
Seismicity studies show
activity along the zone (Henyey and Teng, 1976) (Fig. 10).
Four right-stepping, en echelon segments form the seaward margin
of the Newport-Inglewood structural zone (Plate I).
The right-stepping,
en echelon character is consistent with the onshore right-handed, en
echelon structural pattern of anticlinal culminations and strike-slip
faults (Harding, 1973).
This seaward margin was mapped at the
basement surface, where the basement reflector was disrupted beyond
recognition.
Overlying reflectors become chaotic at approximately the
same location as the basement reflector suggesting a near vertical
attitude of the zone.
This southern boundary of the zone is defined
as the change from chaotic reflectors (Characteristic of the internal
zone) to the high-continuity reflectors to the southwest.
The
56
Figure 10.
Earthquake epicenters, from 1933 to 1972, plotted
along the Newport-Inglewood structural zone
(from Henyey and Teng, 1976).
••• •, .~l>e•
O0
LOS
118°
t{
00'
ANGELES
.• •';_ ::•
•
0 O •
..OBASIN
Okm
SCALE 1:500,000
•
\
..~!'\ ~ •": ••
~--(!).
~-. ~o
j·o
•
@I
•
".
0
" ""'
o$
ti\~
EARTHQUAKE
EPICENTER
NEWPORTINGLEWOOD
FAULT
e8 .,.. ..<~o
(•~A··
......
''9
SAN PEDRO
BASIN
15
''
.',
.
\'<~,
.....,
IS'
'
....
... ,
'
)-(/,
'
.... ,
'0;...
',
-1-s:-<'
',
"
',,
-1
'
', './
'
/
)
f
U1
-....j
.,
58
northernmost offshore segment extends to within 2.5 kilometers of
Newport Beach and the southernmost segment is approximately 3.8
kilometers offshore of Dana Point (Plate I).
Other Faults
Most other faults in the study area are high angle normal with
varying magnitudes of vertical displacement.
Evidence of strike-slip
displacement could not be determined on any faults in the study area.
Faults originate in basement rock and terminate at various levels in
the overlying sedimentary section.
Few faults extend through the top
of the Repetto Formation and those that do have relatively small
displacements.
An exception is the offshore south Newport fault which
displaces the top Repettian reflector more than 200 meters.
Three faults in the study area vertically displace the top
basement reflector more than 200 meters.
Two of the faults are in
Province II and trend north to northwest (the offshore Newport Mesa
fault and the offshore Newport Harbor fault) (Fig. 11).
The offshore
Newport Mesa fault has a maximum displacement of 200 meters and the
offshore Newport Harbor fault has a maximum displacement of 600 meters
at its southern-most extent.
The third fault is the offshore south
Newport fault in Province III, which trends north to northeast.
A
maximum displacement of 900 meters was mapped along this fault (Plate I).
This fault displaces the top Repetto reflector approximately 200 meters,
and bifracates with decreasing throw to the south.
Typically, faults within the study area show differential
displacement of the basement surface along their length, which is due
to numerous intersections with other faults.
These fault intersections
59
Figure 11.
Location of major faults
displacing the basement surface.
60
118"
00'
0
km
SCALE
5
10
1:250,000
NEWPORJ
BEACH
"
Q
~'
NEWPORT
MESA
)
~
~cs
FAULT
FAULT
\
33°
'
30'
61
give Province II and the northwest portion of Province III the
appearance of consisting of a series of
11
basement-rooted 11 fault blocks,
each moving independently (Plate I).
In the area of investigation, numerous faults show a greater
thickness of sedimentary section on their downthrown side (Plates V
and VI).
This suggests that at least part of the vertical
displacement along the faults was contemporaneous with sediment
deposition.
Faults vary in trend direction and lateral continuity.
Faults in
Province II generally are more continuous and have a predominantly
northwest trend.
Faults in Province III generally are discontinuous
and have a predominantly northeast trend.
Structural Highs and Lows
The structural trends in the study area primarily are developed
in basement rock.
These trends, and the major structural relief of the
basement surface, were developed prior to upper Miocene time.
This is
evidenced by the onlapping and downlapping sequences of upper Miocene
strata against the basement surface.
Apparent large scale folding of
upper Miocene to Pliocene strata is due to the draping of strata over
the basement highs and to post-depositional faulting.
The major trend axes are located on Fig. 7.
The largest high is
the north-south trending offshore San Joaquin ridge in Province III.
The crest of this high is 1000 meters below sea level and the west
flank dips to a depth of greater than 3000 meters below sea level.
The
offshore San Joaquin ridge was formed primarily by plastic deformation
62
and faulting of the Catalina Schist prior to sediment deposition, by
being a remnant high area on an erosion surface, or by a combination of
Vertical fault displacement has also contributed to the overall
both.
relief of this ridge.
The offshore south Newport ridge is a northwest-trending high
in Province II with a relief of approximately 1000 meters on the
basement surface.
The origin of this ridge was due to faulting rather
than by plastic deformation or differential erosion.
Faults on the
northeast flank have downdropped blocks to the northeast and faults on
the southwest flank have downdropped blocks to the southwest.
The
offshore Newport Mesa and offshore Newport Harbor faults are primarily
responsible for control of the relief of the offshore south Newport
ridge.
Both the offshore San Joaquin and the offshore south Newport
ridges are buttressed by upper Miocene strata indicating growth prior
to deposition.
Syndepositional faults indicate continued relative
growth of structural relief of these highs through time.
Folds within the sedimentary section are relatively minor.
The
offshore south Newport ridge extends into the sedimentary section with
a relief of approximately 300 meters in the top Delmontian (?) strata.
This appears to be the result of post-depositional faulting and the
draping of strata over the basement structural highs (supratenuous
fo 1ding).
The offshore south Newport trough and the offshore San
Joaquin ridge have no expression in the sedimentary section.
63
Correlation of Onshore-Offshore Geologic Features
Correlation of reflectors across the offshore continuation of the
Newport-Inglewood structural zone is difficult.
Therefore the
estimation of lateral offset along the zone is based upon assumptions.
If it is assumed that the counterpart of the anticlinal structure
of the San Joaquin Hills is the offshore San Joaquin ridge, then the
lateral offset along the Newport-Inglewood structural zone is
approximately 4250 meters since late Miocene time.
This estimate is
based upon the projection of the onshore anticlinal trend to the
seaward margin of the zone (Fig. 12).
The assumption of the
equivalence of the positive structures is supported by their middle
to late Miocene time of inception.
The offshore San Joaquin ridge
formed prior to upper Miocene deposition as indicated by the
buttressing of the upper Miocene strata.
The anticlinal structure
associated with the San Joaquin Hills formed in response to Miocene
faulting (Vedder, 1970; Tan and Edgington, 1976).
The San Onofre Breccia was deposited as clastic wedges derived
from western schist basement highs (Stuart, 1979).
It should follow
that the thickest deposits are adjacent to these basement source highs.
The offshore San Joaquin ridge may have been the source terrain for the
thickest package of San Onofre Breccia exposed on the San Joaquin Hills
(Junger, 1974) and because this thick package is on trend with the axis
of the offshore San Joaquin ridge (Fig. 12), a minimum of offset along
the Newport-Inglewood structural zone is implied.
Stuart (1979)
reports that the Newport-Inglewood fault zone extends along the easter·n
boundary of the offshore San Joaquin ridge where evidence supports an
64
Figure 12.
Apparent horizontal offset of geologic features
along the Newport-Inglewood structural zone.
65
00'
0
km
10
5
1:2 50. 000
PELICAN
HILL
FAULT
Thickest package
of San Onofre
Breccia exposed
SAN
JOAQUJN
'
HILLS
ANTICLINE
~
3 3
OFFSHORE
SAN
JOAQUIN
RIDGE
°
30'
66
essentially fixed position of the ridge relative to San Onofre
Breccia deposits.
Lateral offset may also be estimated by assuming the onshore
Pelican Hill and the offshore south Newport faults were once a
continuous zone.
The amount of estimated offset varies according to
the azimuth of the line used to project the Pelican Hill fault to the
seaward margin of the Newport-Inglewood structural zone.
If the line
of projection parallels the onshore fault trend, then the offset is
approximately 7300 meters.
If the line of projection is perpendicular
to the seaward margin of the Newport-Inglewood structural zone, then
the offset is approximately 4250 meters (Fig. 12).
The assumption that
these faults are the offset segments of a formerly continuous fault
is based upon the following:
(1) both faults have a northwest
downdropped block (Vedder and others, 1957); (2) movement along both
faults was recurrent in Miocene and Pliocene time (Vedder, 1970); and
(3) the greatest stratigraphic separation on these faults is similar
(Pelican Hill fault, 760 meters (Tan and Edgington, 1976) and offshore
south Newport fault, 900 meters).
It should be noted that the offset of 4250 meters is the same for
the Pelican Hill-offshore south Newport fault and the San Joaquin Hills
anticline-offshore San Joaquin ridge estimates.
NEOGENE EVOLUTION OF THE INNER BASIN MARGIN
General Statement
The present configuration of the inner basin margin can be
attributed primarily to the deformation of basement rock and
subsequent Neogene sedimentation.
depocenter until Mohnian time.
The study area did not become a
The area developed in conjunction with
major tectonic events associated with the deformation of the
California Continental Borderland.
Pre-Depositional Events
The positioning of contrasting basement rock complexes (western
blueschist facies complex and the eastern granitic complex) is thought
to have occurred between Late Cretaceous and middle Miocene time (Yerkes
and others, 1965).
This basement contact is believed to be the Newport-
Inglewood structural zone and is thought to mark the location of the
southern California subduction zone, which was active during Cretaceous
time.
This subduction zone extended both northwest across the
Transverse Ranges, delineated by the Sur Nacimiento fault zone, and
southeast along Baja California (Hill, 1971).
Atwater (1970) and subsequent workers (Yeats, 1973; Blake and
others, 1978) attribute the origin of the Neogene borderland basins to
the impingement of a spreading ridge system against western North
America and to subsequent interactions.
Extensionists (Yeats and
others, 1974) suggest that early middle Miocene east-west extension
occurred in the southern California Continental Borderland as a result
of the intersection of the East Pacific Rise and the North American
67
68
plate.
Proponents of oblique extension (Howell and others, 1974) cite
strike-slip movement as the main cause of basin inception.
Recent work
suggests the relative change in motion between the North American plate
and Pacific plate to a more westerly direction about 10 m.y.b.p.
produced the component of extension required to form the Neogene basins
(Blake and others, 1978).
Nardin and Henyey (1978) propose that a
subsequent divergence between plate motions and the orientation of the
tectonically soft boundary between the North American and Pacific
plates occurred between 12 and 3 m.y.b.p. creating a degree of
convergence along the existing strike-slip faults.
This produced a
change in deformational style from crustal dilation, regional block
faulting and basin formation to narrow zones of folding and post-Miocene
discontinuous faulting.
(Nardin and Henyey, 1978; Junger, 1976).
These tectonic events, or combination of events. resulted in the
inception of the Los Angeles basin in middle Miocene time, as evidenced
by a thick sedimentary section of upper Miocene to Pliocene rocks
(Yerkes and others, 1965).
In middle Miocene time, a fairly continuous basement schist-ridge
system extended from Santa Monica to Oceanside (Stuart, 1979).
The
San Onofre Breccia was derived from this schist ridge and deposited in
a structural 1ov1 between the ridge to the west and the San Joaquin
Hills uplift to the east (Stuart, 1979) .
The offshore San Joaquin
ridge was the main source for the thickest exposed section of San
Onofre Breccia in the San Joaquin Hi 11 s according to Junger (197 4) and
Stuart (1979).
The schist-ridge system subsided at the end of middle
Miocene time and deposition of the San Onofre Breccia ceased.
At this
time, the basement surface in the study area attained its present
r
69
ridge and trough configuration with high angle normal faults.
This
ridge and trough configuration may be attributed to differential
erosion of the basement rock surface in middle Miocene time,
plastic deformation and faulting of the schist creating highs and
lows, or a combination of both.
Neogene Events
Depositional History
Upper Miocene deposition in the study area was contemporaneous
with the principal phase of subsidence in the Los Angeles basin
(Yerkes and others, 1965).
During this time, sediments were derived
from north to northwest of the area, as evidenced by the south to
southeast onlapping and downlapping sequences of strata onto the
basement surface.
In the southeastern part of the Palos Verdes
uplift, Miocene sediments buttress against the basement rock
indicating deposition by turbidity currents rather than hemipelagic
sedimentation which would have formed blanket-like deposits on the
basin floor and flanks (Junger and Wagner, 1977).
Truex (1974)
reports a southwest direction of sediment transport during the
deposition of the upper Miocene Puente and the lower Pliocene Repetto
Formations in the Wilmington area.
In the central part of the Los Angeles basin sedimentation was
continuous from late Miocene into Pliocene time and was contemporaneous
with continued basin subsidence (Yerkes and others. 1965).
Conrey
(1967) described the deposition of the lower Pliocene strata of the Los
Angeles basin as resulting from turbidity currents entering the
70
Whittier Narrows (Montebello) spreading coarse sediment over the
entire basin floor.
Truex (1974) suggested that the early Pliocene
(Repettian) sands in the Wilmington oil field represent turbidite
sequences.
In the study area, sedimentation was probably continuous from
late Miocene through Pliocene time.
The consistent south to southeast
onlap and downlap of strata indicates a consistent direction of
sediment transport.
The upper Miocene through Pliocene sediment
transport was controlled and blocked by the basement structural highs.
As proposed for the areas to the north, sediments were probably
transported by density currents into the study area.
The Palos Verdes uplift may have blocked sediment transport to the
southwest towards the deeper basin, restricting sediment transport to
the northwest-southeast-trending Wilmington graben (Fig. 13).
Sediment from the San Pedro bay and Wilmington areas would have
been transported into the study area and eventually diverted into the
deeper basin along the western flank of the offshore San Joaquin ridge.
To the southeast, the Capistrano Embayment originated 10 m.y. ago
and formed a marine basin of sedimentation for the upper Miocene to
lower Pliocene Capistrano Formation (Ehlig, 1979).
Capistrano
sediments infilled this structural trough at approximately the same
rate as the trough subsided.
Numerous south to southwest-trending
backfilled submarine channels exposed within the Capistrano Formation
suggest that excess sediments were frequently carried by turbidity
currents into a deeper offshore basin (Ehlig, 1979).
Offshore of the
Capistrano Embayment, reflectors onlap the east flank of the offshore
San Joaquin ridge.
71
Figure 13.
Direction of sediment transport for upper
Miocene through lower Pliocene strata.
LOS
11s•
J(
oo'
ANGELES
Ok m
BASIN
15
SCALE 1:500,000
WILMINGTON
'\
Direction
sediment
of
transport
\
J
SAN PEDRO
33° 30'
BASIN
\4
"
""-..J
N
'i .
.,
73
Deposition in the study area continued through Pliocene time as
strata overlapped the offshore San Joaquin ridge from the north to
northwest (age of the strata immediately overlying the basement
surface could not be determined).
As sediments overlapped this high
from the north to northwest, the area east of the ridge no longer
received sediment exclusively from the Capistrano Embayment area.
In the Wilmington graben cross-bedded sequences indicate a
continued southwesterly direction of transport in Quaternary time
(Junger and Wagner, 1977).
The Quaternary sediment filled the
Wilmington graben from the present coastline toward the Palos Verdes
uplift.
A large portion of these sediments were transported
southeastward into the Gulf of Catalina (Junger and Wagner, 1977).
Structural Evolution
Growth of the Wilmington anticline was initiated in late Miocene
time and continued through the lower Pliocene (Truex, 1974).
Similar
late Miocene uplift occurred in the San Pedro basin as evidenced by
the thin or absent Miocene sediments from the central and
southwestern parts of the basin (Junger and Wagner, 1977).
In
addition, strata buttress against the Miocene rocks on the basin
flanks and the deeper sediments sho'.'J growth structure caused by
contemporaneous sedimentation and subsidence of the central parts of
the basin (Junger and Wagner, 1977).
Concurrently, the flanks of the
San Pedro basin rose primarily by folding.
Late Pliocene subsidence
of the basin was caused by steepening of the flanks with a majority of
faults terminating at the top of the Repetto Formation (Junger and
Wagner, 1977).
In the study area, late Miocene to early Pliocene
74
tectonics are present.
Late Miocene to early Pliocene faulting may be the result of
continued subsidence of the structurally low areas, structural uplift
of the positive areas, or a combination of both.
Unconformities
within the sedimentary section are associated with the highs, suggesting
that widespread uplift within the area did not occur.
Faults in the
study area typically terminate within or near the top of the Repetto
Formation.
However, post-Repettian uplifts are present.
The origin and
uplift of en echelon anticlinoria beneath the Santa Monica and San
Pedro shelves can be interpreted to be the products of convergent
dextral shear along the Palos Verdes fault during late Pliocene and
Pleistocene time (Nardin and Henyey, 1978).
The emergence and
formation of the modern Wilmington anticline began during the early
part of the upper Pliocene (Mayuga, 1970).
Woodring and others (1946) considered the absence of upper
Pliocene strata north of the Palos Verdes Hills as indicative that this
was the period of strongest deformation in the Palos Verdes Hills.
Post-Repettian tectonics are present in the study area (i.e. the
top of the Repetto Formation is downdropped over 200 meters along the
northwest side of the offshore south Newport fault).
The localization
of right-lateral shear along the Newport-Inglewood structural zone
during late Pliocene time (Yeats, 1973) could be neither
substantiated or disproved.
SUMMARY AND CONCLUSIONS
Seismic stratigraphic analysis demonstrates that the Neogene
structural evolution and depositional history of the study area was
relatively uniform.
The area developed in conjunction with pre-upper
Miocene tectonic events associated with the deformation of the
California Continental Borderland.
The basement surface in the study area ranges in depth from 1000
to 3150 meters bel ov1 sea 1evel.
Basement rocks are schist and be 1ong
to the western blueschist facies complex characteristic of the
California Continental Borderland.
Based primarily on basement
structural elements, the area is divided into three structural
provinces:
(1) Province I is the continental shelf area, (2) Province
II is the northwest portion of the area, and (3) Province III is the
southeast portion of the area.
During middle Miocene time, a schist ridge existed west of the
present coastline and shed detritus (the San Onofre Breccia) toward
the San Joaquin Hills area (Stuart, 1979).
The exposure of this schist
high resulted in differing sedimentary sections present in the San
Joaquin Hills and the study area.
The San Joaquin Hills area contains
thousands of meters of late Cretaceous to Paleogene sediments whereas
the study area contains no pre-Neogene rocks.
Miocene San Onofre Breccia in the
st~dy
The presence of middle
area is probable, however, the
majority of sediment deposition occurred only after subsidence of the
ridge at the end of middle Miocene time.
The source for the thickest
sedimentary package of middle Miocene San Onofre Breccia exposed in
the San Joaquin Hills may be the offshore San Joaquin ridge (Junger,
75
76
1974; Stuart, 1979).
With the subsidence of the schist ridge, the
present configuration of ridges and troughs in the basement surface
was established.
This basement configuration may be attributed to
pre-Neogene plastic deformation and faulting of the schist,
differential erosion of the basement surface during middle Miocene
time, a combination of both, or an original discontinuous schist ridge.
Upper Miocene sedimentary rocks, probably belonging to the Puente
Formation, are downlapped on basement structural lows and onlapped on
basement structural highs from the north to northwest.
Indications are
that from the San Pedro Bay area to the west flank of the offshore San
Joaquin ridge the apparent mode of deposition was by turbidity currents
with a southerly transport direction.
During Pliocene time the depositional patterns established during
late Miocene time continued.
The lower Pliocene Repetto Formation
onlapped the offshore San Joaquin ridge from the north to northwest
until this unit thinned to a zero thickness.
Sediments in the study area accumulated on a basement surface
whose configuration was established prior to late Miocene time.
Upper
Miocene through lower Pliocene sediments were derived from north to
northwest of the offshore Newport Beach area and their transport to the
southeast was controlled or blocked by basement highs.
This
depositional pattern continued until Plio-Pleistocene strata overlapped
the offshore San Joaquin ridge from the north to northwest.
The
consistent southerly direction of sediment transport during late
Miocene through Pliocene time may indicate that sediments were
channeled down the northwest-trending Wilmington graben.
The
77
southwest border of the Wilmington graben (the Palos Verdes uplift) was
uplifted along the Palos Verdes fault.
The time of inception of the
Palos Verdes fault probably was 10 to 15 m.y.b.p. at which time it
blocked sediment transport to the deeper basin (Blake and others, 1978).
Sediments, instead, were deflected to the southeast, eventually to be
diverted seaward along the west flank of the offshore San Joaquin
ridge.
South of Dana Point, strata probably belonging to the upper
Miocene to lower Pliocene Capistrano Formation onlapped the east flank
of the offshore San Joaquin ridge from the north to northeast.
Onlap
occurred while sediment transported into the Capistrano Embayment was
being shed offshore in a southerly direction (Ehlig, 1979).
This
offshore area received additional sediment from the northwest when
sediment transported offshore of the Newport Beach area overlapped the
offshore San Joaquin ridge.
Unconformities within the sedimentary section reported in the San
Pedro Bay area and in onshore oil fields are, for the most part, not
observed in the study area.
The unconformity between the Miocene and
Pliocene strata is present offshore from Newport Beach to an area south
of the Newport syncline.
It can be recognized only where the
divergent angular relationship between the strata is great enough to
be resolved by the seismic data.
Other unconformities were not mapped
because the seismic data probably lacks the detailed resolution
necessary for their recognition.
Syndepositional faulting occurred during the upper Miocene and
resulted in a relative subsidence of the structurally low areas.
78
Furthermore, faults with thicker sections of Repettian strata on their
downthrown blocks indicate that this faulting continued through
Repettian time.
A majority of faults terminate within, or at the top
of, the Repetto Formation.
This suggests a slowing of relative
subsidence during the lower Pliocene.
The upper Pliocene sedimentary
section is relatively undisturbed except along the offshore south
Newport fault where the base of the upper Pliocene is displaced
vertically approximately 200 meters.
The Newport-Inglewood structural zone extends offshore of Newport
Beach to southeast of Dana Point in a series of four right-stepping
en echelon fault segments.
Lateral offset along the Newport-Inglewood
structural zone, using assumed similar or related geologic features
as piercing points, has been right-lateral with an estimated
horizontal displacement of 4250 meters.
The late Pliocene time of
inception of the Newport-Inglewood structural zone as suggested by
Yeats (1973) could be neither substantiated or disproved as reflectors
within the zone are chaotic and no attempt to correlate formation tops
or reflectors through the zone was made.
Recent work by Fischer and
others (1979) and Tieken (in prep.) suggests the offshore extent of
the zone has been active in Holocene time.
Faults in the area are high angle normal.
The attitude and
sense of displacement of these faults suggests that a tensional
regime was active from late Miocene through at least lower Pliocene
time.
The northern portion of the area probably underwent subsidence
during late Miocene through lower Pliocene time similar to that which
occurred in the nearby Los Angeles basin.
This portion of the study
area may have originated as an irregular pull-apart basin during
79
middle Miocene.time.
Los Angeles basin.
Crowell (1974) suggested a similar origin for the
The relatively continuous nature of these faults
suggests that the area consists of a series of
blocks which move independently.
11
basement rooted 11 fault
This is evidenced by differential
vertical displacement of correlated reflectors along single fault traces.
The major tectonic events of the California Continental Borderland
are reflected in the geologic evolution of the study area.
Subsidence
of the western schist ridge and establishment of the basement
configuration subsequent to the North American and Pacific plate
interactions and prior to late Miocene sedimentation occurred in the
area.
The transition to a regime of convergent dextral shear is
evident by the presence of the Newport-Inglewood structural zone.
The
noted northwest-trending structures of the Borderland are present,
primarily in the northwest portion of the area.
The study area may be
an extension of the nearby Los Angeles basin as evidenced by similar
depositional patterns and the timinq of tectonic subsidence.
80
REFERENCES CITED
Allen, D. R., and Hazenbush, G. C., 1957, Sunset Beach oil field:
California Division of Oil and Gas, California Oil Fields Summary of Operations, v. 43, no. 2, p. 47-50.
Atwater, T. M., 1970, Implication of plate tectonics for the Cenozoic
tectonic evolution of western North America: Geological Society
of America Bulletin, v. 81, no. 12, p. 3513-3536.
Bailey, E. H., Irwin, W. P., and Jones, D. L., 1964, Franciscan and
related rocks, and their significance in the geology of western
California: California Division of Mines and Geology Bulletin
183, 177 p.
Bandy, 0. L., 1972, Late Paleogene-Neogene planktonic biostratigraphy
and some geologic implications, California, in Stinemeyer, E. H.,
ed., Proceedings of the Pacific Coast Miocene-Biostratigraphic
Symposium: Society of Economic Paleontologists and Mineralogists,
Pacific Section, p. 37-51.
Barrows, Allan G., 1974, A review of the geology and earthquake
history of the Newport-Inglewood structural zone, southern
California: California Division of Mines and Geology Special
Report 114.
Berggren, W. A., and Van Couvering, J. A., 1974, The Late Neogene:
New York, Elsevier, 216 p.
Blake, ~·1. C., Jr., Campbell, R. H., Dibblee, T. W., Jr., Howell, D. G.,
Nilsen, T. H., Normark, W. R., Vedder, J. C., and Silver, E. A.,
1978, Neogene basin formation in relation to plate-tectonic
evolution of San Andreas system, California: American
Association of Petroleum Geologists Bulletin, v. 62, no. 3,
p. 344-372.
Boellstorff, J. D., and Steineck, P. L., 1975, The stratigraphic
significance of fission-track ages on volcanic ashes in the
marine late Cenozoic of southern California: Earth and
Planetary Science Letters, v. 27, p. 143-154.
Coffeen, J. A., 1978, Seismic Exploration Fundamentals:
Petroleum Publishing, 277 p.
Tulsa,
Conrey, B. L., 1967, Early Pliocene sedimentary history of the Los
Angeles basin, California: California Division of Mines and
Geology, Special Report 93, 63 p.
Corey, W. H., 1954, Tertiary basins of southern California, in Jahns,
R. H., ed., Geology of southern California: California Division
of Mines Bulletin 170, part 8, chapter 3, p. 73-83.
81
Crouch, J. K., 1981, Northwest margin of California continental
borderland: marine geology and tectonic evolution: American
Association of Petroleum Geologists Bulletin, v. 65, no. 2,
p. 191-218.
Crouch, R. W., 1954, Paleontology and paleoecology of the San Pedro
shelf and vicinity: Journal of Sedimentary Petrology, v. 24,
no. 3, p. 182-190.
Crowell, J. C., 1974, Origin of late Cenozoic basins in southern
California, in Dickinson, W. R., ed., Tectonics and sedimentation:
Society of Economic Paleontologists and Mineralogists Special
Publication 22, p. 190-204.
Dobrin, M. D., 1976, Introduction to Geophysical Prospecting, 3rd ed.:
McGraw-Hill, 650 p.
Eaton, J. E., 1923, Structure of the Los Angeles basin and environs
(California): Oil Age, v. 20, no. 6, p. 8-9, 52.
Eaton, R. E., 1933, Long Beach, California, earthquake of March 10,
1933: American Association of Petroleum Geologists Bulletin,
v. 17, p. 732-738.
Ehlig, P., 1979, The late Cenozoic evolution of the Capistrano
embayment in Fife, D. L., ed., Geologic Guide of San Onofre
Nuclear Generating Station and Adjacent Regions of Southern
California: American Association of Petroleum Geologists,
Society of Economic Paleontologists and Mineralogists, Society of
Exploration Geophysicists, Pacific Sections, p. A38-A46.
Emery, K. 0., 1960, The Sea off Southern California, a modern habitat
of petroleum: New York, John Wiley and Sons, Inc., 366 p.
Emery, K. 0., and Shepard, F. P., 1945, Lithology of the sea floor off
Southern California: Geological Society of America Bulletin,
v. 56, p. 431-478.
Ferguson, R. N., and l~illis, C. G., 1924, Dynamics of oil-field
structure in Southern California: American Association of
Petroleum Geologists Bulletin, v. 8, no. 5, p. 576-583.
Fischer, P. J., Rudat, J., and Tieken, E., 1979, Recognition of active
(Holocene) faulting, southern California borderland: Geological
Society of America Abstracts with Programs, v. ll, no. 3, p. 78.
Garotta, R., and Michon, D., 1967, Continuous analysis of the velocity
function and of normal moveout correction: Geophysical
Prospecting 15, p. 584-597.
82
Greene, H. G., Bailey, K. A., Clarke, S. H., Ziony, J. I., and
Kennedy, M. P., 1979, Implications of fault patterns of the inner
California continental borderland between San Pedro and San Diego
in Abbott, P. L., and Elliott, W. J., eds., Earthquakes and
other perils, San Diego Region: Geological Society of America
Field Trip Guidebook, p. 21-27.
Harding, T. P., 1973, Newport-Inglewood trend, California- an
example of wrenching style of deformation: American Association
of Petroleum Geologists Bulletin, v. 57, no. 1, p. 97-116.
Hazenbush, G. C., and Allen, D. R., 1958, Huntington Beach oil field:
California Division of Oil and Gas, California Oil Fields Summary of Operations, v. 44, no. l, p. 13-25.
Henyey, T. L., and Teng, T. L., 1976, Oil and tar seep studies on the
shelves off southern California: Los Angeles, University of
Southern California Geophysical Laboratory Technical Report
75-4, no. 3, 13 p.
Hill, M. L., 1971, Newport-Inglewood zone and Mesozoic subduction,
California: Geological Society of America Bulletin, v. 82,
no. 10, p. 2957-2962.
Howe11, D. G., Stuart, C. J., Platt, J.P., and Hil1, D. J., 1974,
Possible strike-slip faulting in the southern California
borderland: Geology, v. 2, no. 2, p. 93-98.
Hunter, A. L., and Allen, D. R., 1956, Recent developments in West
Newport oil field: California Division of Oil and Gas, Summary
of Operations, v. 42, no. 2, p. 10-18.
Ingle, J. C., Jr., 1967, Foraminiferal biofacies variations and the
Miocene-Pliocene boundary in southern California: Bulletin of
American Paleontology, v. 52, no. 236, p. 217-394.
Ingle, J. C., Jr., 1972, Biostratigraphy and paleoecology of early
Pleistocene benthonic and planktonic foraminifera, San Joaquin
Hills - Newport Bay, Orange County, California, in Stinemeyer,
E. H., ed., Proceedi nas of the Pacific Coast Miocene
Biostratigraphic Symposium: Society of Economic Paleontologists
and Mineralogists, Pacific Section, p. 255-283.
Ingram, W. L., 1968, Newport oil field: California Division of Oil
and Gas, California Oil Fields - Summary of Operations, v. 54,
no. 2, part 2, p. 39-45.
Jahns, R. H., Hill, M. L., Le Coule, J., Moore, D. C., Scott, R. F.,
Smith, S. W., 1971, Geoloqic structure of the continental shelf:
Regional relationships and influence on seismicity: A report
submitted to the Southern California Edison Company.
83
Jennings, C. W., 1962, Geological Map of California, Long Beach Sheet:
California Division of Mines and Geology Map.
Jennings, C. W., 1975, Fault map of California with locations of
volcanos, thermal springs, and thermal wells: California Division
of Mines and Geology Geologic Data Map Number 1.
Junger, Arne, 1974, Source of the San Onofre Breccia (California):
Geological Society of America Abstracts with Programs, v. 6,
no. 3, p. 199-200.
Junger, Arne, 1976, Tectonics of the southern California borderland,
in Howell, D. G., ed., Aspects of the geologic history of the
California continental borderland: American Association of
Petroleum Geologists, Pacific Section, Misc. Publication 24,
p. 486-498.
Junger, Arne and Wagner, H. C., 1977, Geology of the Santa Monica and
San Pedro Basins, California continental borderland: U.S.
Geological Survey Report MF-820.
Kennedy, M. P., 1975, Geology of the San Diego metropolitan area,
California, western San Diego metropolitan area: California
Division of Mines and Geology Bulletin 200A.
Kleinpell, R. M., 1938, Miocene Stratigraphy of California:
Association of Petroleum Geologists, Tulsa, 450 p.
American
Lee, Calvin Fang, 1977, Reflection profiling and trace metal
geochemistry of the Newport submarine canyon region, Ne\'tport
Beach, California: California State University at Los Angeles,
M. S. thesis, 258 p.
Mayuga, f~. N., 1970, Geology and development of California's giantvJilmington oil field, in Ha1bouty, M. T., ed., Geology of
Giant Petroleum Fields: American Association of Petroleum
Geologists Memoir 14, p. 158-184.
Mitchum, R. M., Jr., Vail, P. R., and Sangree, J. B., 1977,
Stratigraphic interpretation of seismic reflection patterns in
depositional sequences in Payton, C. E., Seismic stratigraphyapplications to hydrocarbon exploration: American Association of
Petroleum Geologists, Memoir 26, p. 117-134.
Moody, J. D., and Hill, M. J., 1956, Wrench fault tectonics:
Geological Society of Amer~ica Bulletin, v. 67, no. 9,
p. 1207-1246.
Moore, D. G., 1954, Submarine geology of the San Pedro shelf
(California): Journal of Sedimentary Petrology, v. 24, no. 3,
p. 162-iSl.
84
Moore, D. G., 1960, Acoustic-reflection studies of the continental
shelf and slope off southern California: Geological Society of
America Bulletin, v. 71, no. 8, p. 1121-1136.
Moore, D. G., 1969, Reflection profiling studies of the California
continental borderland-structure and Quaternary turbidite basins:
Geological Society of America Special Paper 107, 142 p.
Moore, G. W., 1972, Offshore extension of the Rose Canyon fault, San
Diego, California: U.S. Geological Survey Professional Paper
800-C, p. Cll3-Cll6.
Moore, G. W., and Kennedy, M. P., 1975, Quaternary faults at San
Diego Bay, California: U.S. Geological Survey Journal of
Research, v. 3, no. 5, p. 589-595.
Morton, P. K., 1973, Fault activity and earthquake map of Orange
County, California, in Gee-environmental maps of Orange County,
California: California Division of Mines and Geology
Preliminary Report 15.
Morton, P. K., Edgington, W. J., and Fife, D. L., 1974, Geology and
engineering geologic aspects of the San Juan Capistrano
quadrangle, Orange County, California: California Division of
Mines and Geology, Special Report 112, 64 p.
Nardin, T. R., and Henyey, T. L., 1978, Pliocene-Pleistocene
diastrophism of Santa Monica and San Pedro shelves, California
continental borderland: American Association of Petroleum
Geologists Bulletin, v. 62, no. 2, p. 247-272.
Pierce, R. L., 1972, Re-evaluation of the late Miocene biostratigraphy
of California-Summary of evidence, in Stinemeyer, E. H., ed.,
Proceedings of the Pacific Coast Miocene Biostratigraphic
Symposium: Society of Economic Paleontologists and
Mineralogists, Pacific Section, p. 334-340.
Reed, R. D., and Hollister, J. S., 1936, Structural evolution of
southern California: Tulsa, American Association of Petroleum
Geologists, 157 p.
Rodgers, D. A., 1979, Vertical deformation, stress accumulation, and
secondary faulting in the vicinity of the Transverse ranges of
southern California: California Division of Mines and Geology
Bulletin 203, 74 p.
Rudat, J., 1980, Quaternary evolution of the San Pedro shelf, Los
Angeles and Orange Counties, California: California State
University, Northridge, M. S. Thesis.
85
Sangree, J. B., and Widmier, J. M., 1977, Seismic interpretation of
clastic depositional facies in Payton, E. D., ed., Seismic
stratigraphy applications tolhydrocarbon exploration: American
Association of Petroleum Geologists, Memoir 26, p. 165-184.
Sangree, J. B., and Widmier, J. M., 1979, Interpretation of
depositional facies from seismic data: Geophysics, v. 44,
no. 2, p. 131-160.
Sheriff, R. E., 1973, Encyclopedic Dictionary of Exploration
Geophysics: Tulsa, Society of Exploration Geophysicists, 266 p.
Sheriff, R. E., 1978, A First Course in Geophysical Exploration and
Interpretation: Boston, International Human Resources
Development Corporation, 313 p.
Stuart, C. J., 1975, The stratigraphy, sedimentology, and tectonic
implications of the San Onofre Breccia, southern California:
University of California, Santa Barbara, Ph.D. dissertation.
Stuart, C. J., 1976, Source terrane of the San Onofre brecciapreliminary notes, in Howell, D. G., ed., Aspects of the
geologic history of-rhe California continental borderland:
American Association of Petroleum Geologists~ Pacific Section,
Misc. Publication 24, p. 309-325.
Stuart, D. J., 1979, Middle Miocene paleogeography of coastal southern
California and the California borderland- evidence from schistbearing sedimentary rocks in Armentrout, J. M., Cole, M. R., and
TerBest, H., Jr., eds., Cenozoic paleogeography of the western
United States: Society of Economic Paleontologists and
Mineralogists, Pacific Section, Pacific Coast Paleogeography
Symposium 3, p. 29-44.
Suppe, J., and Armstrong, R. L., 1972, Potassium-Argon dating of
Franciscan metamorphic rocks: American Journal of Science,
v. 272, p. 217-233.
Taber, S., 1920, The Inglewood earthquake in southern California,
June 21, 1920: Seismological Society of America Bulletin,
v. 10, no. 3, p. 129-145.
Tan, S. S., Edgington, W. J., 1976, Geology and engineering geologic
aspects of the Laguna Beach quadrangle, Orange County,
California: California Division of Mines and Geology Special
Report 126, 32 p.
Telford, W. M., Geldart, L. P., Sheriff, R. E., and Keys, D. A.,
1976, Applied Geophysics: New York, Cambridge University Press
860 p.
86
Tieken, E., in prep., Geology of the inner basin margin, Orange and
San Diego Counties, California: California State University
Northridge, M. S. Thesis.
Truex, S. N., 1974, Structural evolution of Wilmington, California,
anticline: American Association of Petroleum Geologists
Bulletin, v. 58, no. 12, p. 2398-2410.
Truex, J. N., 1978, Pliocene-Pleistocene diastrophism of Santa Monica
and San Pedro shelves, California continental borderland:
discussion: American Association of Petroleum Geologists
Bulletin, v. 62, no. 12, p. 2492-2495.
Vedder, J. G., 1970, Summary of Geology of the San Joaquin Hills,~
Geologic guidebook, southeastern rim of the Los Angeles basin,
Orange County, California, Newport Lagoon - San Joaquin Hills,
Santa Ana Mountains: American Association of Petroleum
Geologists, Society of Economic Paleontologists and
Mineralogists, and Society of Exploration Geophysicists,
Pacific Sections, p. 15-19.
Vedder, J. G., 1971, The San Onofre Breccia in the San Joaquin Hills,
in Bergren, F. W., ed., Geologic guidebook, Newport Lagoon to
San Clemente, Orange County, California: Society of Economic
Paleontologists and Mineralogists, Pacific Section, p. 11-21.
Vedder, J. G., 1972, Review of stratigraphic names and megafaunal
correlation of Pliocene rocks along the southeast margin of the
Los Angeles basin, California, in Stinemeyer, E. H., ed.,
Proceedings of the Pacific Coas~~iocene Biostratigraphic
Symposium: Society of Economic Paleontologists and Mineralogists,
Pacific Section, p. 158-172.
Vedder, J. G., Yerkes, R. F., and Schoellhamer, J. E., 1957, Geologic
map of the San Joaquin Hills-San Juan Capistrano area, Orange
County, California: U.S. Geological Survey Oil and Gas
Map OM-193.
Vedder, J. G., Beyer, L. A., Junger, A., Moore, G. W., Roberts, A. E.,
Taylor, J. C., and Wagner, H. C., 1974, Preliminary report on
the continental borderland of southern California: U.S.
Geological Survey Misc. Field Studies Maps ~1F-624, 34 p., 9
sheets.
Vedder, J. G., Taylor, J. C., Arnal, R. E., and Bukry, D., 1976,
fvlap showing location of selected pre-Quaternary rock samples
from the California continental borderland: U.S. Geological
Survey Misc. Field studies Map MF-737, 3 sheets.
Western Geophysical Company, 1972, Final seismic interpretation, San
Onofre offshore investigations: Report submitted to Southern
California Edison and San Diego Gas and Electric Company.
87
Wilcox, R. E., Harding, T. P., and Seely, D. R., 1973, Basic wrench
tectonics: American Association of Petroleum Geologists
Bulletin, v. 57, no. 1, p. 74-96.
Wissler, S. G., 1943, Stratigraphic formations (relations) of the
producing zones of the Los Angeles basin oil fields: in
Geologic formations and economic development of the air-and gas
fields of California: California Division of Mines and Geology
Bulletin 118, part 2, chapter 7, p. 209-234.
Woodford, A. 0., 1924, The Catalina metamorphic facies of the
Franciscan series: California University of Geological Science,
v. 15, no. 3, p. 49-68.
Woodford, A. 0., 1925, The San Onofre breccia - its nature and origin:
California University Publications Geological Science, v. 15,
no. 7, p. 159-280.
Woodford, A. 0., Moran, T. G., and Shelton, J. S., 1946, Miocene
conglomerates of Puente and San Jose Hills, California:
American Association of Petroleum Geologists Bulletin, v. 30,
no. 4, p. 514-560.
Woodford, A. 0., Schoellhamer, J. E., Vedder, J. G., and Yerkes, R. F.,
1954, Geology of the Los Angeles basin (California), liLJahns,
R. H., ed., Geology of southern California: California Division
of Mines Bulletin 170, part 5, chapter 2, p. 65-81.
Woodring, W. P., Bramlette, M. N., and Kew, W. S. W., 1946, Geology
and paleontology of the Palos Verdes Hills, California: U.S.
Geological Survey Professional Paper 207, 145 p.
Wright, T. L., Parker, E. S., and Erickson, R. C., 1973,
Stratigraphic evidence for timing and nature of late cenozoic
deformation in Los Angeles region, California: American
Association of Petroleum Geologists Abstracts, v. 57, p. 813.
Yeats, R. S., 1968, Southern California structure, sea-floor
spreading, and history of the Pacific basin: Geological Society
of America Bulletin, v. 70, no. 12, p. 1693-1702.
Yeats, R. S., 1973, Ne\'lport-Inglewood fault zone, Los Angeles basin,
California: American Association of Petroleum Geologists
Bulletin, v. 57, no. l, p. 117-135.
Yeats, R. S., Cole, r~. R., Merschat, vJ. R., and Parrsley, R. M.,
1974, Poway fan and submarine cone and rifting of the inner
southern California borderland: Geological Society of America
Bulletin, v. 85, no. 2, p. 293-302.
88
Yerkes, R. F., McCulloh, T. H., Schoellhamer, J. E., and Vedder,
J. G., 1965, Geology of the Los Angeles basin, California -An
introduction: U.S. Geological Survey Professional Paper 420-A,
57 p.
Ziony, J. I., Wentworth, D. M., Buchanan, J. M., and Wagner, H. C.,
1974, Preliminary map showing recency of faulting in coastal
southern California: U.S. Geological Survey Misc. Geological
Map 585.