Upper Cretaceous Mass Transport Systems
Above the Wyandot Formation Chalk,
Offshore Nova Scotia
B.M. Smith, M.E. Deptuck, and K.L. Kendell
Abstract Interpretations from 18 contiguous 3-D seismic surveys, covering more
than 17,000 km2, show a wide variety of diagnostic geomorphic elements that
indicate mass wasting was an important process in shaping the top surface of the
Wyandot Formation, an Upper Cretaceous chalk unit deposited across wide areas
off the coast of Nova Scotia. These geomorphic elements include a series of clearly
defined ~80 m high head scarps extending more than 100 km across the margin,
multiple 20 to 80 m high side scarps defining up to 40 km long failure corridors,
and an irregular planform fabric above areas interpreted to correspond to bedding
plane detachments, variably modified by overlying deformed strata. The latter
morphology includes large >1 km wide slide blocks or erosional remnants. In addition,
multiple intervals of chaotic seismic facies are recognized directly above the top
Wyandot Formation seismic marker. These geomorphic features are attributed to a
complex history of slope failure originating from a series of shelf-perched delta
systems located 40 to 60 km landward from the paleo-continental slope break. These
deltas prograded over the Wyandot Formation in the Late Cretaceous through early
Paleogene. This study indicates that significant quantities of resedimented chalk
may have been deposited on the outer shelf and upper slope. Such deposits could
form important gas reservoirs, as demonstrated in the North Sea (e.g. Ekofisk
field). However, the degree to which overlying prodelta muds were mixed with
the Wyandot chalk during failure is unclear and likely has a direct bearing on the
reservoir potential of resedimented chalks off Nova Scotia.
Keywords Wyandot Formation • chalk • mass wasting • head scarp • transport
corridor • resedimented chalk
B.M. Smith (), M.E. Deptuck, and K.L. Kendell
Canada-Nova Scotia Offshore Petroleum Board, 1791 Barrington St,
Halifax, NS, Canada B2Y 4A2
e-mail: bmsmith@cnsopb.ns.ca
D.C. Mosher et al. (eds.), Submarine Mass Movements and Their Consequences,
Advances in Natural and Technological Hazards Research, Vol 28,
© Springer Science + Business Media B.V. 2010
619
620
1
B.M. Smith et al.
Introduction
Nova Scotia is located on the east coast of Canada with an offshore area of
approximately 400,000 km2 (Fig. 1). The Scotian margin developed after North
America rifted and separated from the African continent during the break-up of
Pangea. Red beds and evaporites were the dominant deposits during the Late
Triassic rift phase, whereas typical clastic progradational sequences with periods of
carbonate deposition dominated the drift phase (Wade and MacLean 1990). Near
the end of the Cretaceous, a period of generally high global sea level (Haq et al.
1987) resulted in the widespread deposition of chalks, marls and marine shales of
the Dawson Canyon and Wyandot formations, which blanketed shelf and slope
areas off Nova Scotia (MacIver 1972; Jansa and Wade 1975).
The Upper Cretaceous Wyandot Formation was deposited on a stable shallowwater, open marine continental shelf (Jansa and Wade 1975; Ings et al. 2005), with
several wells also encountering the formation in probable upper slope settings,
seaward of the paleo-continental shelf edge. Limestone of the Wyandot Formation
generally consists of coccolithic-foraminiferal chalks and lime mudstones that are
soft, fossiliferous, and argillaceous (Wade and MacLean 1990). They are commonly
interbedded with marls, calcareous shales and marine mudstones. On gamma ray
logs, the Wyandot Formation commonly passes up-section from a serrated to more
blocky response, interpreted to reflect a decrease in clay content towards its top
NS
NFLD
Halifax
N
USA
CANADA
200 km
Fig. 1 Location of the study area off Nova Scotia (NS), eastern Canada. NFLD = Newfoundland
Upper Cretaceous Mass Transport Systems
621
(Deptuck et al. 2003; Ings et al. 2005). Biostratigraphic age determinations indicate
that across the Scotian Shelf the Wyandot Formation was deposited in the Coniacian
to Maastrichtian (Wade and MacLean 1990) but in the study area, it is commonly
Campanian or older (Fensome et al. 2008). The Wyandot Formation ranges in
thickness from less than 50 m in the study area to greater than 250 m on the eastern
Scotian shelf. The wide variation in thickness has been attributed to a combination
of erosion and its proximity to prodeltaic shales associated with the influx of clastic
depositional systems (i.e. in areas far removed from clastic depositional systems,
like the eastern Scotian shelf, thicker intervals of chalk accumulated; MacRae et al.
2002; Fensome et al. 2008).
On seismic profiles, the top lithological boundary of the Wyandot Formation
generates a high amplitude positive seismic signature that separates denser and
faster velocity rocks below from less dense and lower velocity Upper Cretaceous
and Paleogene clastics above. This boundary is distinctive across most of the
Scotian shelf and the resulting seismic reflection is commonly used for determining
the phase of seismic volumes and for calibrating well synthetic ties.
In the Sable Island area, abrupt variations in the thickness of the Wyandot
Formation commonly coincide with an irregular reflection pattern on the top
Wyandot seismic marker (MacRae et al. 2002). Using predominantly 2D reflection
seismic profiles, previous workers interpreted the irregular top Wyandot surface as
erosion resulting from ocean current scouring or submarine karst (Wielens et al.
2002; MacRae et al. 2002; Deptuck et al. 2003). The patchwork of individual 3D
seismic programs used in this study, however, provides more constraints on the
origin of some irregularities on the top Wyandot Formation marker across large
areas of the Scotian shelf and slope. The objectives of this paper are to document
the geomorphology of the top Wyandot Formation seismic marker mapped from 3D
seismic data and to discuss additional processes, like mass wasting, that have
strongly influenced its appearance.
2
Study Area, Data, and Methods
The study area, highlighted in the center of Fig. 1, encompasses most of the “Sable
Subbasin”. With 67 hydrocarbon exploration wells, this subbasin is the most
densely explored area off Nova Scotia. About half of the study area lies on the
present-day continental shelf in water depths less than 200 m with the other half on
the continental slope in water depths up to 3,000 m.
The data set consists of 18 contiguous time-migrated 3-D seismic surveys,
covering an area >17,000 km2 above the present-day shelf and slope off Nova
Scotia. The seismic surveys were acquired by several different companies between
1998 and 2002. All surveys were adjusted to zero phase and bulk shifted in time to
provide a consistent data set, and the top of the Wyandot Formation was correlated
to seismic at 18 well locations using synthetic seismograms.
The strong positive reflection from the top of the Wyandot Formation was
mapped across the study area. The interpreted data was then gridded at spacing of
622
B.M. Smith et al.
side
scarp
E. WETZ
W. WETZ
e
Z
ET
West
Sable
E.W
fault
a
h
d
c
Z
ET
.W
W
scour
1
transport
corridor
b
4
f 2
Oligocene
canyon
Time ms
1000
3
g
i
velocity
pushdown
N
1 0 km
well locations
1 Eagle D-21
2 Onondaga E-84
3 Alma K-85
4 Cree E-35
2000
3000
Fig. 2 Sun-illuminated 3D seismic render of the top Wyandot marker (two-way time) showing
the wide variation in morphological features, including head scarps, side scarps, faults, canyons,
and sediment transport corridors. The inset shows the same map with the two main Wyandot
erosional zones highlighted in pink that are separated by the West Sable structural high (see text
for details). The lettered boxes locate detailed dip map images shown in Fig. 3
25 by 25 m and displayed in time using Geoviz 3D visualization software, as shown
in Fig. 2. In all figures, warm colors signify shorter two-way travel times (i.e.
shallower areas) and cool colors represent longer two-way travel times (i.e. deeper
areas). Dip magnitude maps, like the ones shown in Fig. 3, were generated using
Schlumberger IESX software, and were derived from the gridded seismic data.
Dark colours indicate steeper dips and lighter colours indicate shallower dips.
3
Results – Variation in Top Chalk Morphology
Meticulous mapping of the complex seismic reflection defining the top of the
Wyandot Formation, combined with a fine 25 by 25 m gridding of the resulting
surface, reveals a wide range of geomorphic features that range from smooth and
Upper Cretaceous Mass Transport Systems
623
Fig. 3 Dip magnitude images showing the variation in planform geomorphology of the Wyandot
marker. Darker areas correspond to steeper dips. See Fig. 2 for location and text for discussion
relatively featureless, to bumpy with a highly complex planform and cross-sectional
appearance (e.g. Figs. 2–4). The top chalk morphologies in Figs. 3 and 4 are
strikingly similar to features documented in the Petrel Member on the Grand Banks
of Newfoundland, a Turonian chalk unit within the Dawson Canyon Formation
(see Fig. 2.5 of Deptuck 2003).
Some of the most obvious geomorphic features preserved on the top Wyandot
marker correspond to faults. Two varieties are apparent. The first are younger
offsets associated with long-lived deep-seated down-to-the-basin listric growth
faults (e.g. Fig. 3i) that form curved lineations with a dominant E-W or ENE-WSW
orientation. Fault offset of the top Wyandot marker is commonly <50 to 120 m on
the shelf, with >1 km of offset south of Fig. 2, where prominent salt withdrawal
deformed the slope as sedimentation was focused on the hanging wall of mini-basin
bounding faults. These faults are more numerous in areas interpreted to coincide
with the paleo-continental shelf-edge (near the light blue shading in Fig. 2), where
prominent growth took place in older stratigraphic intervals (below the top Wyandot
marker). Most of these faults sole out above overpressured shale or allochthonous
salt intervals. The second style of faulting corresponds to intra-formational or
polygonal faults (e.g. Fig. 3h; Dewhurst et al. 1999; see also Hansen et al. 2004)
that show offset is restricted to stratigraphic intervals immediately above and below
the top Wyandot marker. These faults are most apparent in areas with the thickest
in-situ chalk, for example near the Eagle D-21 well where the Wyandot Formation
is about 190 m thick (see Ings et al. 2005). Offset along these faults is typically less
than 30 m, forming a polygonal pattern of fault traces in plan view.
624
B.M. Smith et al.
~10 km
A
N
block
B
a
b
head scarp
Top Wyandot
block
Fig. 4 Rendered time-structure perspective map showing a closer-up view of the top Wyandot marker.
Seismic line AB crosses a head scarp associated with a slope failure that detached above a bedding
plane located near the base of the Wyandot Formation. Although the younger chaotic mass transport
deposit above the top Wyandot marker (yellow) could be associated with the same failure, it is
probably associated with a younger failure composed predominantly of prodelta muds. The profile
also crosses one of the isolated features interpreted as a slide block or an erosional remnant
A wide range of other geomorphic elements on the top Wyandot marker correspond
to erosional features. For example, the marker is truncated along the bases of deeply
incised canyons of various ages (e.g. Fig. 3g). Several sinuous to linear canyon thalwegs
are apparent in the western part of Fig. 2, but these are generally much younger
features (Eocene to Miocene) that only affect the top Wyandot marker in areas of
maximum incision depth. In some cases the slower velocity fill of younger canyons
generates ‘velocity pushdown’ artifacts on the top Wyandot surface (e.g. western part
of Fig. 2). Other erosional features, which form the primary focus of this paper, appear
to be associated with an unconformity directly above the Wyandot Formation.
They are probably associated with a top chalk unconformity identified by
Doeven (1983) and Fensome et al. (2008) in Onondaga E-84. Here, all of the
Campanian is absent, and lower Campanian or Santonian chalks are overlain directly
by Maastrichtian clastics.
Upper Cretaceous Mass Transport Systems
625
~20 km
D1
N
A
BA
D2
a
b
D2
D1
head scarp
Fig. 5 Three mapped surfaces D1, D2, and the top Wyandot marker (in dark blue). Location of
seismic section AB is denoted by the solid black line. The top Wyandot marker is overlain by two
younger progradational surfaces. The red mapped horizon (D2) defines the western map which is
cropped at the black dashed line in order to display the older clinoform surface to the east (D1)
defined by the top of the orange shading on the seismic section
In the westernmost part of Fig. 2, the top Wyandot marker is smooth and
continuous across elongated zones paralleling the orientation of prodelta clinoforms
that overlie the marker (e.g. Fig. 5). In Fig. 5, subtle truncation of the smooth
Wyandot marker is apparent below ‘delta 1’ (discussed later), and a much thinner
Wyandot Formation was encountered in wells in these areas (e.g. 30.8 m thick at
Cree E-35 and 11.5 m thick at Alma K-85). Such erosion has been attributed to
scouring by shallow ocean currents that flowed parallel to the strike orientation of
prodelta clinoforms (MacRae et al. 2002). Subtle 50 to 100 m wide slope-parallel
linear scours above the top Wyandot marker (Fig. 2) and above younger ‘prodelta
626
B.M. Smith et al.
clinoform’ markers (e.g. the D2 marker in Fig. 5), appear to corroborate this idea.
Deptuck (2003) documented similar erosional scours above prodelta clinoforms
and the Wyandot Formation on the Grand Banks of Newfoundland to the north, and
attributed them to erosion associated with the ancestral Gulf Stream. Such currents
promoted oversteepening of clinoform sets, preconditioning them for failure.
Some of the most striking erosional features in the study area appear to be
associated with slope failures that took place above the Wyandot Formation. Several
sharp vertical offsets in the top Wyandot marker elevation are seen in Fig. 4. Some
of these correspond to faults described earlier but others show no offset in underlying
stratigraphic layers. Despite their similar plan view appearance, they do not correspond
to faults. A seismic profile across the 27 km long NE oriented lineation in Figs. 3a
and 4 indicates that the downward step in the top Wyandot marker corresponds to
erosion of the upper parts of the Wyandot Formation. Erosion took place roughly
parallel to the base of the Wyandot Formation. The sharp downward step therefore
is interpreted as a head scarp associated with a mass failure that took place after the
Wyandot Formation was deposited. South of the head scarp, the failure detached
above a bedding plane located somewhere near the base of the Wyandot Formation,
perhaps in a mechanically weaker, more argillaceous interval. A slab of Wyandot
chalk, thus, appears to have detached and broke up as it was transported to the south.
A series of lineations also trend perpendicular to the orientation of normal faults
(Fig. 4). Like the interpreted head scarps, they show no offset in underlying seismic
markers, and are interpreted as side scarps oriented parallel to the direction of
sediment transport. Two such side scarps define a 5 km wide north–south oriented
‘failure corridor’ (Fig. 3b) that extends towards the paleo continental shelf edge.
The distance from the head scarp to its distal end is approximately 60 km. Several
north–south oriented linear scours are present on the floor of the failure corridor
(see Fig. 4). A more prominent side scarp is also present east of the failure corridor.
It is 37 km long, has a north–south orientation, and a somewhat irregular shape in
plan view. The side scarp sharply separates the more intact polygonally faulted
chalk to the east from highly complex ‘deformed’ top chalk surface to the west.
A wide range of morphologies are preserved within failed areas defined by head
scarps and side scarps. The seismic profile in Fig. 4 crosses a 1 km wide and 2 km
long angular ‘block’ and a more irregular fabric above the bedding plane detachment (Fig. 3c). The seismic character of the block is identical to intact intervals of
chalk north of the head scarp, and this feature is interpreted as a slide block
composed of chalk left behind during slab break-up. Several additional blocks are
recognized to the east of the largest block (Fig. 4). It is also possible that some of
these features are erosional remnants of intact chalk, though this is not our
preferred interpretation. NE of the largest slide block, several positive relief
features are elongated parallel to the head scarp and may be comprised of a cluster
of rotated or folded slide blocks transported normal to a failure scarp located just
north of the 3D seismic coverage.
In addition to the angular slide blocks interpreted in Fig. 4, some morphologies
on the failed top chalk surface are of unknown origin. For example, a series of
Upper Cretaceous Mass Transport Systems
627
elongated morphological features are present in Fig. 3e. They are locally v-shaped
in cross section and could represent elongated scours. Alternately, they could also
represent a series of rotated blocks associated with shallower failures that locally
modified the top Wyandot marker. In addition, a cluster of sub-circular depressions
in Fig. 3f could correspond to areas of irregular chalk dissolution (associated with
submarine karst?) or could represent fluid escape structures.
3.1
Slope Failures Above the Wyandot Formation
Collectively, the head scarps, side scarps, and zones of irregular reflection character
define the boundaries of a large complex area of erosion and transport across
the top of the Wyandot Formation. The ‘Wyandot erosion and transport zone’
(WETZ for short) encompasses an area of about 1,700 km2 and can be subdivided
into two sub-areas (Eastern WETZ and Western WETZ) shown on the inset map
in Fig. 2.
The Western WETZ covers an area of 700 km2. This area is bound to the north
by a 27 km long and 80 m high head scarp, which continues beyond 3D seismic
coverage to the west. The western boundary of the Western WETZ is located within
this data gap as shown in Fig. 2.The eastern boundary of the Western WETZ is
defined by a structural high, trending south from the West Sable structure. There
appears to be less Wyandot erosion above this high and the overlying MTD thins.
No side scarp was identified along this eastern boundary, and instead the transition
to in situ chalk is more gradual.
The Eastern WETZ covers an area of 1,000 km2 and is more clearly defined on
seismic than the Western WETZ. The 80 m high head scarp shown in Fig. 3a
continues to the east beyond 3D seismic coverage, but can be traced further on 2D
seismic profiles. The head scarp merges into a prominent side scarp that sharply
separates the Eastern WETZ from an area of more intact, polygonally faulted chalk
to the east. This prominent side scarp forms the eastern boundary of the Eastern
WETZ. Its southern limit transitions gradually into a surface with less obvious
erosive character, except along the prominent failure corridor that indicates failed
material locally was transported to and probably beyond the paleo continental slope
break. The western extent of the head scarp merges into another side scarp forming
the western boundary of the Eastern WETZ. This boundary continues south along the
south-trending structural high characterized by thicker in-situ chalk (south of the
West Sable structure shown in Fig. 2) and eventually forms the western edge of
the failure corridor.
Areas where the top Wyandot chalk surface is highly complex are commonly
overlain by low amplitude chaotic mass transport deposits derived from mud-prone
prodelta clinoforms in overlying Upper Cretaceous and lowermost Paleogene
strata. As such, the complex fabric observed above the Wyandot Formation could
be closely associated with failures derived from variably oriented clinoforms.
628
3.2
B.M. Smith et al.
Relationship of Failures to Adjacent and Overlying
Prograding Clastic Systems
During and after deposition of the Wyandot Formation, Campanian(?) to
Maastrichtian clastics prograded from the west as a succession of delta lobes
(Fensome et al. 2008). At least two delta lobes, delta 1 and delta 2 (Fig. 5)
prograded from the northwest downlapping onto the chalks of the Wyandot
Formation or the chaotic deposits that overlie it. These appear to be ‘shelf-perched’
delta systems, and within the study area the seaward most offlap break at the delta
front stopped 40 to 60 km short of the paleo-continental slope break. Many of the mass
transport features recorded in the top Wyandot marker are believed to be associated
with failures that were triggered in slightly younger intervals corresponding to
these shelf-perched deltas.
Figure 5 illustrates the aerial relationship between the younger deltas and the
mass wasting features expressed on the top Wyandot marker. The top of each delta
lobe has been mapped and are denoted by the orange (D1) and the red (D2)
horizons on seismic section AB (Fig. 5). Delta 1 aggraded to a height of approximately 300 m prior to failure of mud rich clinoforms and to some extent sandier
delta top-sets. The resulting mass transport deposit (MTD) is shaded in yellow on
the seismic section. The MTD overlies the head scarp on the top Wyandot marker
associated with the Western WETZ. It is unclear whether this mass transport
system exploited a plane of weakness within the Wyandot Formation and eroded
the upper portion of the chalks creating the scarp or whether this mass transport
deposit is a later feature that simply draped a pre-existing scarp above the top
Wyandot surface. The similarity in orientation of the two head scarps may imply
that the southern scarp formed during an initial prodelta failure, with retrogradation producing the head scarp that truncates the seaward edge of Delta 1. If the
erosion above the Wyandot Formation is a result of prodelta failure, then the
resulting MTD should consist of a mixture of Wyandot carbonates and delta front
to prodelta sediments. A series of younger clinoforms can also be seen downlapping onto this MTD and many additional failures appear to have been initiated as
clastic systems continued to prograde. These failure deposits commonly merge
with and erode into older MTDs, resulting in complicated stratigraphy in the
central area of the WETZ.
A second failure scarp is evident on the younger D2 surface to the west. This
younger approximately 10 km wide failure was initiated after the Wyandot surface was buried by a combination of clinoform bottom-sets and chaotic deposits
associated with earlier slope failures. Therefore the Wyandot surface in this location
was protected by a thicker clastic cover and was less affected by the failed delta
front at the D2 surface. A secondary scarp is also evident south of the failure scarp,
and may record the position of the initial failure, with retrogradational failure defining
the ultimate head scarp location.
Upper Cretaceous Mass Transport Systems
3.3
629
Potential Triggering Mechanisms
Numerous triggering mechanisms for these failures are possible. Norris et al.
(2000) suggested that the 65 Ma Chicxulub bolide impact at the K/T boundary was
responsible for slope instability and mass failure of chalks across extensive areas
of the western North Atlantic. However, the presence of Maastrichtian age clastic
deposits associated with prodelta clinoforms above the unconformity (Doeven
1983; Fensome et al. 2008) indicates erosion above the Wyandot Formation in the
study area predates the K/T bolide impact. In addition, erosion above the Wyandot
Formation is diachronous, and hence is unlikely to be associated with any single
event. It is possible that oversteepening of the prodelta clinoforms, which are
locally steeper than 5°, could have preconditioned them for failure. The steep
gradient of these clinoforms may be associated with the passage of ocean currents
that locally undercut clinoform bottom-sets, as observed in the Jeanne d’Arc Basin
to the north (where time-equivalent clinoforms are as steep as 9°; see Figure 4.11
of Deptuck 2003). Ground shaking by earthquakes or short-term drops in eustatic
sea level, could equally have initiated these failures.
4
Conclusions
1. Interpretations from 18 contiguous 3-D surveys, covering more than 17,000 km2,
show a wide variety of geomorphic elements that indicate mass wasting was an
important process in shaping the top surface of the Wyandot Formation.
2. Head scarps, side scarps, bedding plane detachments, slide blocks or erosional
remnants, scours and chaotic mass transport deposits are all recognized along
or above the top Wyandot marker. They record a complex history of Late
Cretaceous slope failure above the Wyandot chalk.
3. Athough most chaotic MTDs come to rest on the relatively flat-lying shelf, at
least one transport corridor reached the paleo continental slope break, indicating
that some resedimented chalks may have been transported into deeper water
where the slope morphology is complex.
4. Erosional features associated with failures above the Wyandot Formation
appear to be closely tied to prodelta slope failures shed from overlying shelf
perched deltas. This close association could mean that resedimented chalks are
heavily mixed with prodelta shales, making them less desirable reservoir
targets.
Acknowledgments We wish to thank Andrew MacRae for his detailed review of our paper and
his generous contribution of ideas about Upper Cretaceous depositional systems on the Scotian
Margin. A review from Grant Wach also helped sharpen our ideas.
630
B.M. Smith et al.
References
Deptuck ME (2003) Post-rift geology of the Jeanne d’Arc Basin, with a focus on early paleogene
submarine fans and insights from modern deep-water systems. Unpublished Ph.D. thesis,
Dalhousie University, Halifax, Nova Scotia, Canada, 369 p.
Deptuck ME, MacRae RA, Shimeld JW, Williams GL, Fensome RA (2003) Revised upper cretaceous
and lower paleogene lithostratigraphy and depositional history of the Jeanne d’Arc Basin,
offshore Newfoundland, Canada. Am Assoc Pet Geol Bull 87:1459–1483.
Dewhurst DN, Cartwright JA, Lonergan L (1999) The development of polygonal fault systems by
syneresis of colloidal sediments. Mar Pet Geol 16:793–810.
Doeven PH (1983) Cretaceous nannofossil stratigraphy and paleoecology of the Canadian Atlantic
margin, Geological Survey of Canada, Bulletin 356:1–57.
Fensome RA, Crux JA, Gard IG, MacRae RA, Williams G, Thomas F, Fiorini F, Wach G (2008)
The last 100 million years on the Scotian Margin, offshore eastern Canada: An event-stratigraphic scheme emphasizing biostratigraphic data. Atl Geol 44:93–126.
Hansen DM, Shimeld JW, Williamson MA, Lykke-Anderson H (2004) Development of a major
polygonal fault system in Upper Cretaceous chalk and Cenozoic mudrocks of the Sable
Subbasin, Canadian Atlantic Margin. Mar Pet Geol 21:1205–1219.
Haq BU, Hardenbol J, Vail PR (1987) Chronology of fluctuating sea level since the Triassic.
Science 235:1156–1167.
Ings SJ, MacRae RA, Shimeld JW, Pe-Piper G (2005) Diagenesis and porosity reduction in the
Late Cretaceous Wyandot Formation, Offshore Nova Scotia: A comparison with Norwegian
North Sea Chalks. Bull Can Soc Pet Geol 53:237–249.
Jansa LF, Wade JA (1975) Geology of the continental margin off Nova Scotia and Newfoundland.
In: van der Linden WJM and Wade JA (eds.), Offshore Geology of Eastern Canada, Geol Surv
Can Pap 74–30:51–105.
MacIver NL (1972) Cenozoic and mesozoic stratigraphy of the Nova Scotia shelf. Can J Earth Sci
9:54–70.
MacRae RA, Shimeld JW, Fensome RA (2002) Cryptic erosion on the Upper Cretaceous Wyandot
Formation, Sable Island area, Scotian shelf. Atlantic Geoscience Society colloquium and
general meeting program and abstracts. Atl Geol 38:93.
Norris RD, Firth J, Blusztajn JS, Ravizza G (2000) Mass failure of the North Atlantic margin
triggered by the Cretaceous – Paleogene bolide impact. Geology 28:1119–1122.
Wade JA, MacLean BC (1990) The geology of the southeastern margin of Canada, Chapter 5, In:
Keen MJ and Williams GL (eds.), Geology of the Continental Margin of Eastern Canada, Geol
Surv Can, Geol Can No 2 167–238.
Wielens HJBW, MacRae RA, Shimeld J (2002) Geochemistry and sequence stratigraphy of
regional upper cretaceous limestone units, offshore eastern Canada. Org Geochem 33:1559–1569.