Marine Geology 217 (2005) 233 – 254
www.elsevier.com/locate/margeo
Sedimentary trace element constraints on the role of North Atlantic
Igneous Province volcanism in late Paleocene–early Eocene
environmental change
Deborah J. Thomasa,T, Timothy J. Bralowerb
a
Department of Oceanography, Texas A&M University, College Station, TX 77843-3146, United States
Department of Geosciences, Pennsylvania State University, University Park, PA 16802, United States
b
Accepted 2 March 2005
Abstract
A growing body of geologic evidence suggests that emplacement of the North Atlantic Igneous Province (NAIP) played a
major role in global warming during the early Paleogene as well as in the transient Paleocene–Eocene thermal maximum
(PETM) event. A ~5 million year record of major and trace element abundances spanning 56 to 51 Ma at Deep Sea Drilling
Project Sites 401 and 549 confirms that the majority of NAIP volcanism occurred as subaerial flows. Thus the trace element
records provide constraints on the nature and scope of the environmental impact of the NAIP during the late Paleocene–early
Eocene interval. Subaerial volcanism would have injected mantle CO2 directly into the atmosphere, resulting in a more
immediate increase in atmospheric greenhouse gas abundances than CO2 input through submarine volcanism. The lack of
significant hydrothermalism contradicts recently proposed mechanisms for thermally destabilizing methane hydrate reservoirs
during the PETM. Any connection between NAIP volcanism and PETM warming had to occur through the atmosphere.
D 2005 Elsevier B.V. All rights reserved.
Keywords: NAIP; trace elements; bulk sediment; PETM; DSDP Site 401; DSDP Site 549
1. Introduction
1.1. Geological and environmental consequences of
large igneous province volcanism
Large igneous provinces (LIPs) are constructed
during a focused outpouring of primarily basaltic
T Corresponding author.
E-mail address: dthomas@ocean.tamu.edu (D.J. Thomas).
0025-3227/$ - see front matter D 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.margeo.2005.02.009
lavas, both beneath the sea surface and on the
continents (e.g., Tarduno et al., 1991; Coffin and
Eldholm, 1994). The environmental impact of LIP
volcanism has received considerable attention, as the
timing of many prominent paleoclimatic and biotic
events coincided with LIP emplacement. The best
known examples include the Permian–Triassic extinction event which coincided with Siberian Trap
volcanism (Renne and Basu, 1991), the Triassic–
Jurassic extinctions which were contemporaneous
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D.J. Thomas, T.J. Bralower / Marine Geology 217 (2005) 233–254
with Central Atlantic Magmatic Province volcanism
(Marzoli et al., 1999), Cretaceous Oceanic Anoxic
Event 1a which overlapped with emplacement of the
Ontong Java and Manihiki Plateaus (e.g., Tarduno et
al., 1991; Larson, 1991; Larson and Erba, 1999), and
the Paleocene–Eocene transition which occurred
during North Atlantic Igneous Province (NAIP)
volcanism (Rea et al., 1990; Eldholm and Thomas,
1993; Jolley et al., 2002).
NAIP volcanism commenced during the early
Paleogene with the initiation of the Iceland plume
beneath Greenland (Tegner et al., 1998), and culminated in seafloor spreading between Greenland and
Norway. The NAIP consists of the volcanic sequences
found in the British Isles, eastern Canada (Baffin
Island), West Greenland, the East Greenland continental flood basalt sequences, the seaward-dipping
reflector sequences along the perimeter of the rifted
margins of South and East Greenland and the northwestern Europe counterparts, and the aseismic Greenland–Iceland–Faeroe Ridges (e.g., Saunders et al.,
1997 and references therein) (Fig. 1).
The majority of NAIP volcanism occurred in two
phases (Sinton and Duncan, 1998). The initial pulse
(~60–62 Ma) produced basalt along the southeastern
Greenland margin, and in western Greenland, Scotland and Northern Ireland, as well as regionally
distributed silicic ash falls (Knox and Morton, 1988;
Sinton and Duncan, 1998). The second phase began
~57–58 Ma (Sinton and Duncan, 1998) and generated
the upper series of the seaward-dipping reflector
sequences (SDRS) along the southeastern Greenland
margin, Rockall Plateau, and the Vbring Plateau, as
well as some of the younger lava series in the British
Fig. 1. Paleogeographic reconstruction of the late Paleocene (~55 Ma) showing the locations of DSDP Sites 401 and 549. Inset adapted from
Saunders et al. (1997) and main paleoreconstruction from the Ocean Drilling Stratigraphic Network (http://www.odsn.de).
D.J. Thomas, T.J. Bralower / Marine Geology 217 (2005) 233–254
Isles. Seafloor magnetism shows the presence of
Chron 24-age (52.4 to 55.9 Ma; Berggren et al.,
1995) crust in the Norwegian-Greenland Sea (Saunders et al., 1997 and references therein). Volcanism
that produced C24 age crust coincided with the
formation of the off-lapping SDRS. Several DSDP
and ODP drilling legs (38, 48, 81, 104, 152, and 163)
dedicated to investigation of the off-lapping volcanic
sequences found that much of the second pulse of
volcanism occurred subaerially or in shallow water
(e.g., Clift et al., 1995). This suggests that the oldest
portions of ocean floor in the Norwegian-Greenland
Sea formed subaerially followed by subsidence to
submarine depths after cooling.
Mantle outgassing of CO2 during NAIP emplacement has been implicated in the long-term warming
trend that began at ~59 Ma and peaked at ~51 Ma
(Rea et al., 1990; Zachos et al., 2001). During the
first major pulse of NAIP activity, a large volume
of rapidly and subaerially extruded flood basalts
(N 1.8 106 km3 in ~3 My) could have contributed
1020 g of CO2 to the ocean–atmosphere reservoirs
235
(Caldeira and Rampino, 1991; Eldholm and Thomas,
1993). This excess atmospheric CO2 may have led to
gradual, long-term early Paleogene warming (Fig. 2).
With a carbon isotopic composition of 6x, ~1020 g
of mantle CO2 from the NAIP also could have
contributed to the concomitant long-term decrease in
benthic foraminiferal d 13C values (e.g., Zachos et al.,
2001).
NAIP magmatic activity has also been invoked
as an explanation for the rapid and transient
Paleocene–Eocene thermal maximum (PETM) that
occurred in the midst of the long-term early
Paleogene warming trend. Eldholm and Thomas
(1993) explored the possibility that mantle CO2
outgassing associated with the NAIP may have
caused the rapid warming and the major decrease in
global d 13C values. However, they concluded that
the PETM warming and d 13C decrease were too
rapid to have been caused by the NAIP alone.
Jolley et al. (2002) speculated that NAIP magmatism warmed the oceans sufficiently to thermally
destabilize methane hydrate reservoirs in North
Fig. 2. The geochronologic framework for global climate records (d 18O and d 13C panels from Zachos et al., 2001) and the primary components
of NAIP volcanism (adapted from Sinton and Duncan, 1998). The PETM warming and carbon isotope excursions are indicated.
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D.J. Thomas, T.J. Bralower / Marine Geology 217 (2005) 233–254
Atlantic sediments. Establishing this direct relationship between NAIP volcanism and dissociation of
methane hydrates (Dickens et al., 1995, 1997) relies
on a questionable identification of the base of the
PETM carbon isotope excursion within the FaeroeShetland T40 lava series (Jolley et al., 2002). This
stratigraphic placement of the carbon isotope excursion implies that the PETM occurred ~5 My earlier
than dictated by the Berggren et al. (1995) timescale, a claim that was debated by a series of
comments (Aubry et al., 2003; Srivastava, 2003;
Thomas, 2003; Wei, 2003).
More recently, Svensen et al. (2004) cited seismic
reflection evidence that NAIP-age magma intrusions
into carbon rich sediments along the Norwegian
margin resulted in the production and release of
sufficient thermogenic methane to cause the PETM
warming and d 13C excursion. Arguments against this
new hypothesis focus on the poorly constrained
timing of the intrusions and formation of the hydrothermal bconduitsQ through which the newly produced methane would have reached the ocean–
atmosphere reservoir relative to the well constrained
timing of the PETM (Dickens, 2004). These debates
highlight the difficulty in establishing a causal
relationship between NAIP volcanism and environmental change during the PETM without precise
correlation of regional magmatic events to the global
chemostratigraphic framework.
Determining if a phase of intense submarine
volcanism occurred in the northeastern Atlantic
would contribute to our understanding of the
evolution of early Paleogene climate and oceanography and enable direct correlation of NAIP
volcanism to the stratigraphic record of climate
change. The short-term (millenial) climatic effects
of subaerial and submarine volcanism likely would
have been different, based on the efficiency of gas
transfer from the mantle to the atmosphere. Subaerial
volcanism would inject mantle gases directly into the
atmosphere, where they would contribute immediately to greenhouse gas inventories. However, the
short-term climatic effects of injecting mantle CO2
into subsurface waters would have been dampened
by carbonate system buffering (e.g., Coffin and
Eldholm, 1994). In addition, a phase of intense
submarine volcanism might have increased regional
productivity by seeding oceanic surface waters with
potentially biolimiting micronutrients (e.g., Vogt,
1989; Sinton and Duncan, 1997; Leckie et al.,
2002). Finally, tighter constraint on the volcanic
history of the NAIP is also crucial in elucidating the
onset of basin formation in, and deep-water sourcing
from, the northeastern Atlantic.
1.2. Trace element abundance as a potential proxy for
intense submarine volcanism
Submarine volcanism can generate hydrothermal
plumes enriched in elements leached from cooling
basalts (Heath and Dymond, 1977; Edmond et al.,
1979; Dymond, 1981) and degassed from erupting
magmas (Vogt, 1989; Rubin, 1997). Advection of
the plume, followed by cooling and deposition,
imparts a hydrothermal component to pelagic deepsea sediments located downstream from the volcanic source. Episodes of plate tectonic reorganization, such as rifting or large igneous province
volcanism, may generate hydrothermal bmegaQ
plumes (Baker, 1994) that could enrich Fe, Mn,
and trace metal (e.g., Cr, V, Ni, Zn, Cu, Ba, among
others) contents in proximal sediments by ~10–
1000 times background values (Rubin, 1997). Such
enrichments may serve as a proxy for intensified
hydrothermal activity associated with submarine
large igneous province emplacement (Duncan et
al., 1997), and may enable determination of the
onset of submarine volcanism in the NorwegianGreenland Sea.
Several investigators used bulk sediment trace
element concentrations to determine the timing of
major episodes of submarine volcanism. Orth et al.
(1993) examined samples from 16 sections spanning
the Cenomanian–Turonian boundary (93.5 Ma) in
the U.S. Western Interior, and found significant trace
element enrichments concentrated in two spikes in
upper Cenomanian strata close in age to oceanic
anoxic event OAE2. These authors suggested that
intensified seafloor spreading and associated hydrothermal activity might have produced enhanced trace
element concentrations. The magnitude of the trace
element abundance anomaly decreased toward the
north in the U.S. Western Interior (Orth et al., 1993),
supporting a volcanic source to the south. In a
similar study, Duncan et al. (1997) found elevated
trace element abundances in the upper Barremian–
D.J. Thomas, T.J. Bralower / Marine Geology 217 (2005) 233–254
lower Aptian section of the Cismon core from
northern Italy that correlates in time with the major
pulse of Ontong Java Plateau and Manihiki Plateau
volcanism during the Early Cretaceous. Normalization of the elemental concentrations to Al revealed
enrichments of Sc, Mn, Co, Ni, Cu, Zn, Y, Zr, Ba,
Hf, Pb, and U of up to 100 times background values
in the stratigraphic horizons immediately below the
Selli black shale horizon (OAE1a).
A potential complication in interpreting trace
element anomalies in both of the above studies is
that the anomalies correspond to prominent changes in
sedimentary organic matter associated with two
OAEs. Enhanced accumulation of organic matter,
and the associated change in pore water redox
conditions, can generate bulk sedimentary normalized
trace element anomalies through scavenging and
bioconcentration (e.g., Brumsack, 1986), or remobilization within pore waters (e.g., Torres et al., 1996).
As a consequence, numerous studies have investigated the use of trace element ratios as proxies for
dysoxia/anoxia (e.g., Jones and Manning, 1994;
Martı́nez-Ruiz et al., 2003). Thus it is difficult to rule
out the possibility that the trace metal anomalies
recorded in the Cenomanian–Turonian boundary
(Orth et al., 1993) or upper Barremian–lower Aptian
sections reflect the redox and lithologic changes
associated with enhanced organic matter accumulation
during the OAEs.
An additional consideration is whether formation
of hydrothermal plumes was facilitated by the redox
conditions of the water column during the two
episodes of OAE black shale deposition. Under
oxic conditions, plumes are capable of advecting
hydrothermal particles tens to hundreds of kilometers after achieving neutral buoyancy (Klinkhammer and Hudson, 1986; Feely et al., 1992). The
factors that limit chemical/particulate transport via
hydrothermal plume advection are deposition of
hydrothermal and hydrothermally scavenged compounds and dilution of the plume by ambient seawater
(Cowen et al., 1990; Feely et al., 1992; Lilley et al.,
1995). Changes in seawater redox conditions could
alter rates of both particulate scavenging and
microbially mediated oxidation, thus affecting the
ultimate distance of hydrothermal plume influence.
Thus, oceanic anoxia may have been responsible for
the presumed hydrothermal delivery of trace ele-
237
ments to locations more than several thousand
kilometers from the volcanic source (e.g., Duncan
et al., 1997).
The upper Paleocene to lower early Eocene
sedimentary record of environmental change, including the PETM, does not contain any intervals of
significantly elevated organic carbon. Although deep
waters during the PETM were characterized by
diminished dissolved oxygen (e.g., Thomas and
Shackleton, 1996), sediments deposited in the North
Atlantic during the PETM do not indicate dysoxic/
anoxic conditions. Therefore interpretation of any
trace element anomaly will not be complicated by
redox changes of the magnitude that characterized
the lower and mid-Cretaceous sections previously
investigated.
Here we address the timing of NAIP volcanism
with respect to climate change during the late
Paleocene–early Eocene by attempting to determine
the onset of a proposed episode of submarine
volcanism in the northeastern Atlantic basins using
sedimentary trace element abundances. We generated
a stratigraphy of major and trace element abundances
at North Atlantic DSDP Sites 401 and 549, to
determine if hydrothermal contributions increased
during the late Paleocene–early Eocene. These sites
were located within a few hundred kilometers south of
the main NAIP volcanic centers and thus ideally
situated to record a southward-flowing hydrothermal
plume into the North Atlantic.
2. Samples and methods
2.1. Site selection
We selected DSDP Sites 401 (Bay of Biscay,
North Atlantic; paleodepth ~1900 m) and 549
(Goban Spur, North Atlantic; paleodepth ~2500 m)
for major and trace element analyses. DSDP Sites
401 and 549 are situated on crust that formed prior
to NAIP emplacement and contain expanded stratigraphic sections of the upper Paleocene to lower
Eocene, as well as a record of the PETM (e.g.,
Aubry et al., 1996; Pardo et al., 1997). As
previously mentioned, these sites were located
within a few hundred kilometers of portions of
the NAIP (Fig. 1). Proximity to the volcanism
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D.J. Thomas, T.J. Bralower / Marine Geology 217 (2005) 233–254
within the North Atlantic basins is an important
consideration because the trace elemental concentrations of the plume decrease with distance from
the volcanic source as scavenging and deposition
occur (e.g., Lyle et al., 1987; Duncan et al., 1997).
In addition, partial upper Paleocene–lower Eocene
carbon isotope stratigraphies already exist for these
sites (Stott et al., 1996; Pardo et al., 1997), enabling
direct placement of the elemental records in the
early Paleogene chronostratigraphic framework.
Upper Paleocene–lower Eocene sediments from
Sites 401 and 549 are ideally suited for use of the
hydrothermal plume trace element proxy. Neither
the PETM nor the longer late Paleocene–early
Eocene interval was characterized by an episode
of enhanced organic matter accumulation in pelagic
sediments. Upper Paleocene–lower Eocene sedimentary organic matter concentrations at Sites 401 and
549 are b 1% (Montadert et al., 1979; de
Graciansky et al., 1985), typical of pelagic sedimentary sections. Thus any occurrence of elevated
hydrothermal trace element/Al values can be interpreted unambiguously to reflect enhanced hydrothermal inputs.
2.2. Analyses
We analyzed 21 samples from 184.11 to 194.59
mbsf (51.45 to 54.18 Ma) at Site 401, and 72 samples
from 298.70 to 350.0 mbsf (52.53 to 56.09 Ma) at
Site 549. Major and trace elements were measured by
X-ray fluorescence (XRF) analysis at St. Mary’s
University, Halifax, Nova Scotia, yielding concentrations of the elements Si, Ti, Al, Fe, Mn, Mg, Ca,
Na, K, P, V, Cr, Zr, Ba, Ni, Zn, Ga, Sr, and Nb. Of
this suite of elements, only Fe, Mn, V, Cr, Ni, and Zn
are diagnostic of hydrothermal plumes (Rubin, 1997).
However, analysis of a broader array of elements is
important to characterize the source of elemental
deposition to the North Atlantic sediments. Analytical
precision is b 1% for major elements and, 5% for
trace elements. Calcium carbonate values of Site 549
samples were determined by carbon coulometry at
UNC-Chapel Hill. Reproducibility of CaCO3 analyses
is F 0.2% based on replicate analyses of calcite
standards.
Trace element concentrations were normalized to
Al to eliminate the effects of variations in terrigenous
sediment supply (Orians and Bruland, 1985). In
regions where surface water primary productivity is
high, Ti may be a more appropriate normalizing
element because biological scavenging can contribute
biogenic, bexcessQ Al to the sediments (Murray and
Leinen, 1993). However, sedimentary (lack of biogenic silica and low organic matter content) and biotic
(nannoplankton assemblages) indicators suggest that
Sites 401 and 549 were not affected by highly
productive surface waters during the late Paleocene–
early Eocene (Montadert et al., 1979; de Graciansky et
al., 1985; Tremolada and Bralower, 2004). Thus we
selected Al to correct for detrital contributions.
Normalized elemental abundances are compared to
calcium carbonate weight percentage to assess the
effects of changes in carbonate content on elemental
abundance. All data are available in the online data
repository.
2.3. Age model
We based the age model for Sites 401 and 549 on
published biostratigraphic data (Table 1) and the late
Paleocene–early Eocene orbital stratigraphy developed for ODP Site 690 (Röhl et al., 2000). Numeric
ages assigned to the biostratigraphic data defined
within a chronostratigraphic framework that placed
the P/E boundary at 55.5 Ma (Berggren et al., 1995;
Thomas and Shackleton, 1996; Bralower et al.,
1997) have not been revised to comply with the
new age for the Paleocene–Eocene boundary of 55.0
Ma (defined as the base of the CIE). We adjusted all
biostratigraphic datum ages to be 0.5 My younger in
Table 1
Stratigraphic depth (mbsf) of the biostratigraphic data and chemostratigraphic tie-points used to construct the age model
Datum
Age
Age
My
LO D. lodoensis
LO T. contortus (B)
CIE brecoveryQ
HO F. tympaniformis
CIE base
LO D. multiradiatus
52.80
53.93
55.28
55.33
–
56.20
52.30
53.43
54.78
54.83
55.0
55.70
a
b
c
Müller (1979).
Müller (1985).
Aubry et al. (1996).
0.5
Site 401
Site 549
189.48a
–
198.81
NA
202.72
217.5a
299.50b
335.16c
–
335.55c
339.68
352.30b
D.J. Thomas, T.J. Bralower / Marine Geology 217 (2005) 233–254
order to apply the new 55.0 Ma age for the base of
the CIE while incorporating existing late Paleocene–
early Eocene biostratigraphic data. Then we assigned
54.78 Ma to the asymptote of the carbon isotope
curve recovery based on the orbitally determined
220-ky duration of the entire event (Röhl et al.,
2000). We assumed linear sedimentation rates
between datum ages.
3. Results
3.1. Calcium carbonate abundance
Site 549 carbonate contents varied from 0 to ~74%
(Fig. 3). Four intervals of decreased carbonate content
occur in the section, with the most prominent (339.94
to 338.60 mbsf) associated with the PETM. At the
PETM (corresponding to the ~5x decrease in d 13C
values as shown in Fig. 3), carbonate values decrease
Fig. 3. Comparison of the d 13C (continuous gray line; Stott et al.,
1996) and CaCO3 records (discrete filled diamonds; this study) from
DSDP Site 549. The PETM d 13C excursion and carbonate decrease
occur at ~340 mbsf.
239
from ~60% to ~0%, then recover to ~43%. Other
minima at 321.79, 312.94, and 306.47 mbsf correspond to carbonate contents of 23%, 47%, and 38%,
respectively (Fig. 3).
3.2. Major element trends
3.2.1. Site 549
Ca, Si, Al, and Fe are the most abundant elements
in Site 549 sediments. The abundance of Ca varies
between ~0% and 30%, and the stratigraphic trend
follows the pattern of CaCO3 in the upper Paleocene–
lower Eocene section (Fig. 4). Greater than 99% of
sedimentary Ca is bound in CaCO 3 (with the
exception of one sample at 339.94 mbsf), suggesting
that weight percent Ca is a suitable proxy for CaCO3
in these sediments. The stratigraphic trends shown by
Al are opposite to those of CaCO3 (Fig. 4), with peaks
corresponding to carbonate minima. Aluminum contents vary between ~2% and 9%. Normalization of Ca
to Al preserves the stratigraphic trend in Ca content
and the relationship to the CaCO3 curve. Stratigraphic
trends in Si and Fe track the Al curve, with Si
abundances between 7% and 28%, and Fe varying
between ~1% and 6%.
The remaining elemental abundances were normalized to Al. A variety of patterns emerge from the
normalized major elemental trends (Fig. 5). Most
major elements demonstrate patterns similar to Mg
and Mn (Fig. 5) in which normalized abundances
show slight to pronounced minima corresponding to
CaCO3 minima. In contrast, K/Al (Fig. 5) and Fe/Al
ratios generally correlate negatively to Ca and
CaCO3.
Also shown in Fig. 5 are the ranges in element/Al
values for continental crust (Taylor and McLennan,
1995) and MORB (Li, 2000). Site 549 K/Al and Fe/Al
values fall within the range of element/Al values for
the continental crust, while Mg/Al and Mn/Al values
are typically at the low end of the continental crust
range or below crustal values. With the exception of
K/Al, major element/Al ratios in Fig. 5 lie below
typical MORB values.
3.2.2. Site 401
Ca, Si, Al, and Fe are the most abundant
elements in Site 401 sediments. The abundance of
Ca varies from ~20% to 34%, corresponding to
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D.J. Thomas, T.J. Bralower / Marine Geology 217 (2005) 233–254
Fig. 4. Records of CaCO3, Ca, and Al for Site 549. Panel A demonstrates the close correlation between CaCO3 weight percent and Ca weight
percent, indicating the suitability of Ca as proxy for carbonate content in the North Atlantic sediments analyzed in this study. Panel B indicates
the inverse relationship between CaCO3 and sedimentary Al, rendering Al suitable as a correction for detrital contributions to these sediments.
calculated CaCO3 percentages of 50% to 86%. A
decrease in Ca to 20% occurs at 52.42 Ma (189.93
mbsf). Stratigraphic trends in Si, Al, and Fe oppose
the Ca trend (Fig. 5, online data repository). Silica
varies from ~4% to 13%, Al abundances are
between ~1% and 5%, and Fe contents range from
0.7% and 2.3%.
The major elements Mg, K, Mn, and Fe (normalized to Al) are shown in Fig. 6. Minor (up to ~0.1)
variations in the element/Al ratios correlate positively
with Ca. Deviations from this relationship (not
illustrated in Fig. 5) occur in the Na/Al record at
51.22 Ma (185.42 mbsf) and at the base of the Ti/Al
record, from 53.49 to 53.66 Ma (193.95 to 194.59
mbsf) in which the element/Al ratios increase while
Ca abundance decreases.
Comparison of the Site 401 major element/Al
values with those of the average continental crust and
MORB indicates that Mg/Al values lie at the low end
of the range of continental crust values, and below
MORB values, while Mn/Al and Fe/Al values are
below both continental crust and MORB values. K/Al
values at Site 401 are higher than MORB and within
the upper limit of the range in continental crust values.
3.3. Minor element trends
3.3.1. Site 549
Much of the variation in normalized minor
element trends correlates to Ca (hence CaCO3)
fluctuations (Fig. 6). In particular, the normalized
concentrations of Sr, Zr, Nb, and Ba, and, to a lesser
extent, V, Zn, and Ga tend to vary directly with
CaCO 3 content, whereas Cr and Ni correlate
negatively with CaCO3. Notable peaks in element/
Al trends occur in the V/Al record at 52.91 Ma
(318.80 mbsf) and the Ba/Al record at 55.35 Ma
(346.0 mbsf). Prominent Cr and Ni peaks at 52.47
Ma (305.0 mbsf) (~30 and 120 times higher than
background, respectively) were not observed in the
D.J. Thomas, T.J. Bralower / Marine Geology 217 (2005) 233–254
241
Fig. 5. Plots of representative normalized major element ratios (Mg/Al, K/Al, Mn/Al, and Fe/Al) and Ca weight percent for Sites 401 and 549.
For each normalized element (element/Al), the left panel contains the Site 401 record and the right panel contains the Site 549 record. The blue
line along the element/Al axis represents the range of element/Al values of continental crust (Taylor and McLennan, 1995), and the yellow line
is the element/Al composition of a typical MORB (Li, 2000). (For interpretation of the references to colour in this figure legend, the reader is
referred to the web version of this article.)
stratigraphic intervals immediately above or below.
We believe these peaks probably resulted from
spurious analysis or contamination, and we excluded
them from figures.
Site 549 V/Al values lie within the range of
average continental crustal composition (Fig. 6) and
below that of typical MORB (except for the value of
34.03 at 54.9 Ma). Cr/Al and Ni/Al values fall within
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D.J. Thomas, T.J. Bralower / Marine Geology 217 (2005) 233–254
Fig. 6. Plots of representative normalized trace element ratios (V/Al, Cr/Al, Ni/Al, and Zn/Al) and Ca weight percent for Sites 401 and 549. For
each normalized element (element/Al), the left panel contains the Site 401 record and the right panel contains the Site 549 record. The blue line
along the element/Al axis represents the range of element/Al values of continental crust (Taylor and McLennan, 1995), and the yellow line is the
element/Al composition of a typical MORB (Li, 2000). (For interpretation of the references to colour in this figure legend, the reader is referred
to the web version of this article.)
the range of continental crust and are similar to that of
MORB (Fig. 6). Zn/Al values are generally higher
than both continental crust and MORB.
3.3.2. Site 401
Trends in most of the normalized minor element
ratios at Site 401 (V, Zn, Ga, Sr, Zr, Nb, and Ba)
correlate positively with changes in Ca (Fig. 6).
However, variations in Cr/Al and Ni/Al records
demonstrate a negative correlation to the Ca record.
Ni/Al also contains a peak at 52.52 Ma (190.3
mbsf) to a value of ~22, nearly a four-fold increase
in values recorded throughout the rest of the
record.
D.J. Thomas, T.J. Bralower / Marine Geology 217 (2005) 233–254
V/Al and Cr/Al values recorded at Site 401 lie
within the range of average continental crustal
composition and below that of typical MORB
(Fig. 6). The majority of Ni/Al values lies within
the range of continental crust and are lower than
MORB (Fig. 6). One exceptional value of 22.2 at 52.5
Ma is significantly higher than both MORB and
continental crust. Zn/Al values are generally higher
than both continental crust and MORB.
4. Discussion
4.1. Characterizing detrital and biogenic contributions to sediments investigated
Deep-sea sediments can be separated into four
genetic categories: biogenic, detrital (terrigenous),
hydrothermal, and hydrogenous (authigenic). The
relative contribution of any of these components is
dictated by a number of factors including climate,
ocean circulation, water depth, tectonics, weathering, runoff, and primary productivity. Stratigraphic
changes in the relative abundance of a given
sedimentary component may provide insight into
paleoenvironmental changes. However, it is often
difficult to attribute sediment compositional changes
to a single cause. For example, CaCO3 in deep-sea
sediments is primarily biogenic in origin, produced
by calcareous phytoplankton (i.e., nannoplankton)
and zooplankton (i.e., foraminifera) in surface
waters or by benthic organisms (benthic foraminifers, ostracods). Stratigraphic changes in the CaCO3
content, however, may reflect changes in the
production or dissolution of CaCO3, the supply of
other constituents that dilute the concentration of
CaCO3, or a combination of these factors. Similar
ambiguities accompany the interpretation of changes
in other sediment constituents.
Lithology exerts a first order control on sediment
chemistry; thus, in order to interpret elemental
chemistry as a proxy for submarine volcanic activity,
we first must characterize the nature of lithologic
variation. The dominant lithology in the upper
Paleocene–lower Eocene section at Sites 401 and
549 is nannofossil chalk with varying amounts of
terrigenous material (Montadert et al., 1979; de
Graciansky et al., 1985).
243
Although chalk is the overall dominant lithology
throughout the investigated section at Site 549,
CaCO3 content varies significantly (Fig. 3). Situated
at ~2500 m water depth during the late Paleocene–
early Eocene (Stott et al., 1996), Site 549 was
subject to intervals of dissolution which most likely
caused the CaCO3 minima. Carbonate decreases at
the shallower Site 401 are smaller (~1900 m
paleodepth; Montadert et al., 1979) but generally
correlate with those at Site 549. One notable
dissolution event lies at 189.93 mbsf at Site 401
corresponding to a decrease in carbonate from
~75% to ~49% (as estimated from Ca wt.%).
The vast majority of Ca in deep-sea sediments is
associated with CaCO3, thus Ca serves as a
carbonate proxy in most cases. Normalization of
Ca by Al does not change the stratigraphic pattern
of Ca abundance, indicating that the Ca in Site 549
sediments was derived primarily from CaCO3.
Preferential removal of a dominant component
results in an increase in the concentration of the
other constituents. This is particularly evident at
Site 549 where peaks in Al mirror minima in
CaCO3 (Fig. 4). This effect is also apparent in the
opposing trends of Ca versus Si, Al, and Fe at Site
401. Such peaks have no other paleoenvironmental
significance.
4.2. Assessing hydrothermal contributions to the
sediments investigated
Comparison of Al-normalized elemental trends
with the CaCO3 record enables characterization of
elemental fluctuations that are not attributable to
variations in biogenic or detrital fluxes. If normalized element and CaCO3 trends are similar, then the
dominant, non-detrital control is simply the occurrence of these elements in calcite. Such a pattern is
demonstrated by the opposing trends of CaCO3 and
Al (Fig. 4). However, variations in normalized
element trends that have no relationship to CaCO3
indicate a source other than biogenic or detrital
contributions.
Normalized major elemental abundances at Sites
401 and 549 tend to follow changes in CaCO3 (Fig.
5). Trends in normalized Na, Mg, P, Ti, and Mn
seem to be controlled by sediment accumulation
rate, as minima in the elemental ratios coincide with
244
D.J. Thomas, T.J. Bralower / Marine Geology 217 (2005) 233–254
diminished CaCO3 abundance. Two exceptions in
the group of major elements are K at Site 549 and
Fe at both sites. Minor increases in Site 549 K/Al
values coincide with CaCO3 minima (Fig. 5),
suggesting slight changes in clay mineralogy that
are not associated with the supply of detrital
material. Fe/Al fluctuations may also be attributable
to variations in clay mineralogy, but are unlikely
associated with enhanced hydrothermal activity. If
hydrothermal contributions increased, K/Al ratios
would be expected to decrease as Fe/Al ratios
increase (e.g., Heath and Dymond, 1977; Li, 2000).
In addition, a significant input of hydrothermal
elements would generate changes in the element/Al
ratio independent of any variation in the sediment
CaCO3 content.
Comparison of the range of sedimentary major
element/Al to that expected for bulk continental
crust (Taylor and McLennan, 1995) or typical basalt
(Li, 2000) composition also provides insight into
the source of normalized elemental variations (Fig.
5). In general, major element/Al ratios recorded are
closer to a continental crust composition than
MORB. This comparison combined with the overall
inverse relationship of K/Al and Fe/Al to CaCO3 is
strong evidence of a detrital source.
The abundances of trace elements normalized to
Al also demonstrate a relationship with CaCO3
abundance (Fig. 6). Such a relationship would be
expected for elements such as Sr, Zn, and Ba that
substitute directly into the calcite lattice based on
charge balance. However, most trace element accumulation at Site 549 was influenced primarily by
general biogenic sediment accumulation. Two minor
exceptions occur in the V/Al record at 318.80 mbsf
and in Ba/Al at 338.60 mbsf. While increased V and
Ba are associated with hydrothermal deposition
(e.g., Lilley et al., 1995), we argue that these peaks
were not caused by enhanced hydrothermal activity
because they are not accompanied by enrichments in
other hydrothermal elements. Instead these peaks
may reflect pore water redox anomalies (e.g., Jacobs
et al., 1987; Torres et al., 1996).
Normalized trace element abundances at Site
401 also follow biogenic sedimentation (Fig. 6).
The overall coherence of Zn/Al and Ca trends
suggests that much of the Zn content in Site 401
and 549 sediments may be bound in biogenic
carbonate. Cr/Al and Ni/Al ratios, however, tend to
oppose Ca abundance, suggesting that these elements reflect hydrogenous or possibly hydrothermal
contributions. However, the magnitude of Cr/Al or
Ni/Al fluctuations (~2 10 4) does not suggest a
significant hydrothermal contribution as would be
expected from the NAIP. Once again, the Cr/Al
and Ni/Al fluctuations are not accompanied by
changes in other elemental ratios that might
indicate hydrothermal inputs or scavenging (e.g.,
Fe, Mn).
4.3. Paleoenvironmental implications of the elemental
record
Hydrothermalism associated with seafloor spreading can generate a plume capable of traversing
hundreds (Klinkhammer and Hudson, 1986; Feely et
al., 1992) and potentially thousands of kilometers
(Duncan et al., 1997) from the source depending on
plume buoyancy. Sites 401 and 549 were located
within a few hundred kilometers of the southern
portions of the NAIP (southeastern Greenland
margin and British Tertiary igneous province), and
thus had the potential to record trace element
deposition from a hydrothermal plume if volcanism
was sufficiently intense.
Elemental data from the upper Paleocene and
lower Eocene sections at Sites 401 and 549,
together spanning ~5 My including the Paleocene/
Eocene boundary, do not indicate a significant
component of hydrothermal deposition. There are
two possible explanations for the lack of a hydrothermal trace element anomaly. Either submarine
volcanism during the NAIP was not sufficiently
intense to generate a plume, or submarine volcanism
produced a hydrothermal plume but Sites 401 and
549 were too far from the source to record
hydrothermal sedimentation. Both explanations suggest that the second phase of NAIP activity was not
accompanied by significant submarine volcanism.
The new data corroborate numerous field studies
(e.g., Saunders et al., 1997) that suggest the
majority of NAIP volcanism was subaerial or
intrusive, as opposed to submarine.
In addition, there is no evidence for a regional
increase in sea surface primary productivity in the
North Atlantic in upper Paleocene–lower Eocene
D.J. Thomas, T.J. Bralower / Marine Geology 217 (2005) 233–254
sediments (Montadert et al., 1979; de Graciansky et al.,
1985; Stott et al., 1996; Pardo et al., 1997; Tremolada
and Bralower, 2004). Hydrothermalism associated with
massive submarine volcanic provinces in the Cretaceous is believed to have bseededQ enhanced primary
productivity through supply of micronutrients such as
Fe (Vogt, 1989; Sinton and Duncan, 1997; Leckie et al.,
2002). This effect, combined with the potential for
reduced metals (from hydrothermal inputs) to consume
dissolved O2 from seawater during oxidation, may
have contributed to global anoxia during the Cretaceous OAEs. It is reasonable to expect that generation
of a hydrothermal plume during NAIP emplacement
would have had similar environmental impact, yet no
such evidence exists in the sedimentary record.
Our data conflict with previous findings of
increased Fe and Mn mass accumulation rates at Site
549 (Olivarez and Owen, 1989) that were interpreted as
evidence for enhanced hydrothermal activity in the
northeastern Atlantic. One explanation for this discrepancy is that the interpretation of Olivarez and Owen
(1989) was based on Fe and Mn enrichments in the
acetic acid-soluble carbonate fraction leached from Site
549 sediments (Andrianiazy and Renard, 1985). These
data reflect changes in the Fe and Mn content of
sedimentary carbonate that likely resulted from carbonate diagenesis rather than regional hydrothermal
inputs. Normalization of our bulk sediment Fe and
Mn data to Al reveals no such hydrothermal enrichment
at any point in the ~5 My interval sampled (Fig. 5).
The lack of evidence for increased hydrothermal
activity associated with the P/E boundary interval
(Figs. 5 and 6) argues against a direct role of NAIP
volcanism (e.g., direct heating of waters to thermally
destabilize proximal hydrate reservoirs) in the
PETM warming. However, NAIP volcanism likely
contributed significantly to late Paleocene–early
Eocene global change. Subaerial volcanism and its
associated CO2 outgassing would have affected
atmospheric greenhouse gas concentrations more
directly and immediately than submarine volcanism.
Thus NAIP volcanism may have contributed to late
Paleocene warming leading up to the PETM
(Thomas et al., 2002), as well as the long-term
warming that spanned the late Paleocene–early
Eocene interval.
Finally, the Site 401 and 549 records have
implications for the tectonic history of the North
245
Atlantic basins and the evolution of thermohaline
circulation patterns in the Atlantic. The trace element
records indicate that NAIP volcanism remained
subaerial until at least 50.6 Ma. This implies that
submarine basin formation in the Norwegian-Greenland seas had not advanced to the point of an open
marine connection to the rest of the Atlantic by 50.6
Ma. Thus the North Atlantic likely was not a site of
deep-water formation during the late Paleocene and
early Eocene.
5. Conclusions
We generated a ~5 million year record of major
and trace element abundances at DSDP Sites 401
and 549. Normalized elemental abundances at Sites
401 and 549 predominantly reflect biogenic and
detrital sedimentation, and do not indicate a hydrothermal contribution. In addition, we found no
evidence of enhanced hydrothermal element accumulation before or during the PETM. These data
reinforce observations that NAIP emplacement was
dominantly subaerial.
Our data help to constrain the potential role of
NAIP volcanism in late Paleocene–early Eocene
environmental change. Subaerial volcanism would
have injected mantle CO2 directly into the atmosphere, likely resulting in a more immediate increase in
atmospheric greenhouse gas inventories than CO2
input through submarine volcanism. In addition, the
lack of significant submarine volcanism rules out the
possibility that thermal dissociation of methane
hydrates during the Paleocene–Eocene thermal maximum was caused by magmatic warming of ocean
waters. The only plausible direct relationship between
NAIP volcanism and the PETM was through
increased concentrations of atmospheric CO2 and
consequent greenhouse warming.
Acknowledgments
This work was supported by NSF EAR 98-146054
(TJB). We thank David Slauenwhite at St. Mary’s
University for performing the XRF analyses. We also
thank Bob Duncan and an anonymous reviewer for
their helpful comments.
246
Appendix A. Site 549 CaCO3 and elemental data
Depth (mbsf)
Age (Ma)
12-4,
12-4,
13-1,
13-1,
13-1,
13-1,
13-1,
13-1,
13-2,
13-2,
13-2,
13-2,
13-2,
13-2,
13-2,
13-2,
13-2,
13-2,
13-3,
13-3,
13-3,
13-3,
13-3,
13-4,
13-4,
13-5,
13-6,
13-7,
14-1,
14-2,
14-3,
14-4,
14-5,
14-6,
14-7,
15-1,
15-2,
15-3,
15-4,
15-5,
298.7
298.99
303.23
303.48
303.72
303.99
304.19
304.41
304.6
304.7
304.8
304.9
305
305.1
305.3
305.51
305.7
305.9
306.07
306.31
306.47
306.68
307.01
307.62
308.01
309.18
310.7
312.18
312.94
314.48
316
317.47
318.8
320.32
321.79
322.5
323.94
325.5
326.97
328.49
52.275
52.284
52.418
52.426
52.434
52.442
52.449
52.456
52.462
52.465
52.468
52.471
52.474
52.477
52.484
52.490
52.496
52.503
52.508
52.516
52.521
52.528
52.538
52.557
52.570
52.607
52.655
52.702
52.726
52.775
52.823
52.869
52.912
52.960
53.006
53.029
53.074
53.124
53.170
53.219
70–72
99–101
23–25
48–49
72–75
99–101
119–122
141–143
10–12
20–22
30–32
40–42
50–51
60–62
80–82
101–103
120–122
140–142
7–9
31–33
47–48
68–70
101–103
12–14
51–52
49–50
51–52
49–50
44–45
48–49
50–51
47–48
45–46
47–48
44–45
50–51
44–45
50–51
47–48
49–50
CaCO3 (%)
60.33
62.08
38.08
69.17
72.83
73.67
62.67
46.58
67.17
68.58
72.25
68.17
54.17
22.58
46.5
42.83
41.17
42.92
40.58
Si (%)
Si/Al
Ti (%)
Al (%)
Fe (%)
Fe/Al
Mn (%)
Mn/Al
Mg (%)
Mg/Al
19.59
16.07
13.91
10.04
10.06
8.96
10.59
8.25
7.44
8.23
9.22
9.69
9.77
9.91
10.48
10.58
10.99
13.83
8.95
13.28
16.32
11.91
11.34
10.95
7.87
7.05
6.74
9.91
13.91
8.53
8.34
7.79
8.08
12.4
19.68
14.59
15.17
15.29
15.14
15.9
2.4
2.5
2.67
2.77
2.83
2.86
2.78
2.9
2.93
2.96
2.86
2.9
2.95
2.83
2.78
2.86
2.87
2.86
3.08
2.89
2.82
2.85
2.94
2.86
3.02
3.01
3.06
3.07
2.82
2.93
3.06
3.08
2.86
2.99
2.53
2.77
2.86
2.91
2.9
2.89
0.38
0.32
0.29
0.19
0.2
0.18
0.21
0.16
0.15
0.16
0.18
0.19
0.19
0.19
0.21
0.21
0.21
0.28
0.18
0.26
0.31
0.22
0.21
0.21
0.15
0.14
0.13
0.19
0.27
0.17
0.16
0.16
0.18
0.25
0.39
0.33
0.34
0.33
0.33
0.36
8.18
6.42
5.2
3.62
3.55
3.14
3.82
2.85
2.54
2.78
3.22
3.34
3.31
3.51
3.77
3.69
3.83
4.84
2.9
4.6
5.78
4.18
3.85
3.82
2.6
2.34
2.2
3.23
4.93
2.92
2.73
2.52
2.82
4.15
7.77
5.26
5.3
5.25
5.23
5.5
4.88
4.08
3.04
2.29
2.19
1.9
2.32
1.76
1.31
1.5
1.88
2.02
1.96
2.02
2.34
2.23
2.11
2.83
1.78
2.79
3.5
2.66
2.19
2.33
1.55
1.38
1.2
2.01
3.09
1.83
1.59
1.43
1.04
2.68
4.93
2.08
2.75
3.06
3.04
2.93
0.6
0.64
0.58
0.63
0.62
0.6
0.61
0.62
0.52
0.54
0.58
0.6
0.59
0.58
0.62
0.6
0.55
0.58
0.61
0.61
0.61
0.64
0.57
0.61
0.6
0.59
0.54
0.62
0.63
0.63
0.58
0.57
0.37
0.65
0.63
0.39
0.52
0.58
0.58
0.53
0.08
0.08
0.11
0.17
0.16
0.17
0.14
0.17
0.19
0.18
0.16
0.15
0.16
0.15
0.13
0.13
0.13
0.1
0.15
0.09
0.08
0.11
0.12
0.12
0.15
0.15
0.13
0.1
0.07
0.11
0.17
0.16
0.22
0.1
0.05
0.12
0.12
0.13
0.12
0.1
0.01
0.01
0.02
0.05
0.04
0.05
0.04
0.06
0.07
0.06
0.05
0.04
0.05
0.04
0.04
0.04
0.04
0.02
0.05
0.02
0.01
0.03
0.03
0.03
0.06
0.06
0.06
0.03
0.01
0.04
0.06
0.06
0.08
0.02
0.01
0.02
0.02
0.02
0.02
0.02
0.98
0.89
0.75
0.66
0.6
0.57
0.61
0.53
0.51
0.52
0.57
0.62
0.61
0.63
0.63
0.63
0.65
0.71
0.55
0.68
0.86
0.71
0.63
0.62
0.53
0.49
0.46
0.54
0.77
0.54
0.59
0.54
0.53
0.73
1.03
0.77
0.81
0.81
0.81
0.81
0.12
0.14
0.14
0.18
0.17
0.18
0.16
0.19
0.2
0.19
0.18
0.18
0.18
0.18
0.17
0.17
0.17
0.15
0.19
0.15
0.15
0.17
0.16
0.16
0.2
0.21
0.21
0.17
0.16
0.19
0.22
0.21
0.19
0.18
0.13
0.15
0.15
0.16
0.16
0.15
D.J. Thomas, T.J. Bralower / Marine Geology 217 (2005) 233–254
Sample
64–65
51–52
22–23
102–103
43–44
73–74
138–139
14–15
78–79
67–69
97–99
37–39
51–53
70–72
94–96
116–118
141–143
2–4
9–11
22–24
28–30
44–46
50–52
64–66
93–95
51–52
50–51
50–51
49–50
47–48
50–51
45–46
330.14
331.51
331.73
332.51
333.43
333.73
334.38
334.64
335.28
336.67
336.98
337.88
338.02
338.21
338.45
338.6
338.85
339.03
339.1
339.23
339.29
339.45
339.51
339.65
339.94
341.53
343
344.5
346
347.47
349
350
53.271
53.314
53.321
53.346
53.375
53.385
53.405
53.413
53.859
54.876
54.889
54.926
54.932
54.940
54.949
54.956
54.966
54.973
54.976
54.982
54.984
54.991
54.993
54.999
55.014
55.103
55.184
55.267
55.351
55.432
55.517
55.572
45.17
46.83
50.08
47.08
44.75
49.25
45.75
46.5
41.42
49
54.08
44.17
39.75
36.42
22.83
32.33
7.92
2.5
0.51
0.64
0.71
0.73
0.82
18.08
16.33
56.75
51.58
57.42
55.5
43.92
37.75
46.42
14.49
14.04
13.41
14.17
14.63
13.72
14.7
14.51
15.27
13.51
11.67
14.93
16.43
17.33
20.54
17.8
24.42
25.68
26.09
25.96
26.94
26.64
26.78
22.2
17.06
11.39
13.53
11.72
12.94
16.51
17.47
15.19
2.92
2.82
2.89
2.85
2.88
2.88
2.9
2.89
2.9
2.94
2.96
3.16
3.17
3.18
2.97
3.07
2.96
2.84
2.85
2.91
3.23
3.03
3.03
3.19
3.24
3.34
3.94
3.93
5.51
5.72
4.52
5.69
0.31
0.31
0.3
0.32
0.32
0.31
0.33
0.32
0.45
0.27
0.22
0.28
0.29
0.31
0.35
0.29
0.4
0.44
0.45
0.44
0.45
0.48
0.48
0.38
0.35
0.16
0.14
0.13
0.09
0.12
0.19
0.11
4.96
4.99
4.65
4.97
5.07
4.76
5.08
5.03
5.27
4.59
3.94
4.73
5.19
5.44
6.92
5.81
8.26
9.03
9.17
8.91
8.34
8.78
8.83
6.95
5.26
3.41
3.43
2.98
2.35
2.88
3.87
2.67
3.19
2.71
2.64
2.53
2.74
2.58
2.78
2.8
2.62
3.05
2.36
3.06
3.18
3.19
3.97
3.41
4.83
5.59
5.62
5.53
5.19
4.72
4.76
3.76
3.27
2.24
2.4
2.07
1.71
2.18
2.88
1.89
0.64
0.54
0.57
0.51
0.54
0.54
0.55
0.56
0.5
0.66
0.6
0.65
0.61
0.59
0.57
0.59
0.59
0.62
0.61
0.62
0.62
0.54
0.54
0.54
0.62
0.66
0.7
0.69
0.73
0.76
0.74
0.71
0.13
0.14
0.14
0.14
0.13
0.15
0.14
0.15
0.11
0.13
0.15
0.12
0.09
0.08
0.09
0.11
0.05
0.06
0.07
0.08
0.09
0.03
0.03
0.05
0.08
0.14
0.13
0.17
0.18
0.16
0.17
0.18
0.03
0.03
0.03
0.03
0.03
0.03
0.03
0.03
0.02
0.03
0.04
0.02
0.02
0.01
0.01
0.02
0.01
0.01
0.01
0.01
0.01
0
0
0.01
0.02
0.04
0.04
0.06
0.08
0.06
0.04
0.07
0.77
0.74
0.72
0.74
0.75
0.72
0.77
0.75
0.92
0.83
0.74
0.86
0.92
0.93
1.05
0.84
1.22
1.42
1.44
1.44
1.36
1.42
1.45
1.31
1.07
0.81
0.93
0.85
0.55
0.61
0.83
0.56
0.16
0.15
0.16
0.15
0.15
0.15
0.15
0.15
0.18
0.18
0.19
0.18
0.18
0.17
0.15
0.15
0.15
0.16
0.16
0.16
0.16
0.16
0.16
0.19
0.2
0.24
0.27
0.28
0.24
0.21
0.21
0.21
Sample
Depth (mbsf)
Age (Ma)
Ca (%)
Ca/Al
Na (%)
Na/Al
K (%)
K/Al
P (%)
P/Al
12-4,
12-4,
13-1,
13-1,
13-1,
13-1,
13-1,
13-1,
13-2,
13-2,
298.7
298.99
303.23
303.48
303.72
303.99
304.19
304.41
304.6
304.7
52.275
52.284
52.418
52.426
52.434
52.442
52.449
52.456
52.462
52.465
8.17
13.49
17.4
24.15
23.69
25.46
22.76
26.29
27.77
26.71
1
2.1
3.35
6.67
6.67
8.11
5.97
9.23
10.96
9.61
0.82
0.79
0.76
0.64
0.61
0.53
0.65
0.58
0.44
0.51
0.1
0.12
0.15
0.18
0.17
0.17
0.17
0.2
0.17
0.18
2.08
1.52
1.28
0.83
0.9
0.75
0.96
0.7
0.57
0.67
0.25
0.24
0.25
0.23
0.25
0.24
0.25
0.24
0.23
0.24
0.07
0.05
0.04
0.05
0.05
0.05
0.05
0.05
0.05
0.05
0.01
0.01
0.01
0.01
0.01
0.02
0.01
0.02
0.02
0.02
70–72
99–101
23–25
48–49
72–75
99–101
119–122
141–143
10–12
20–22
247
(continued on next page)
D.J. Thomas, T.J. Bralower / Marine Geology 217 (2005) 233–254
15-6,
15-7,
16-1,
16-1,
16-2,
16-2,
16-2,
16-3,
16-3,
16-4,
16-4,
16-5,
16-5,
16-5,
16-5,
16-5,
16-5,
16-6,
16-6,
16-6,
16-6,
16-6,
16-6,
16-6,
16-6,
17-1,
17-2,
17-3,
17-4,
17-5,
17-6,
17-7,
248
Appendix A (continued)
Depth (mbsf)
Age (Ma)
Ca (%)
Ca/Al
Na (%)
Na/Al
K (%)
K/Al
P (%)
P/Al
13-2,
13-2,
13-2,
13-2,
13-2,
13-2,
13-2,
13-2,
13-3,
13-3,
13-3,
13-3,
13-3,
13-4,
13-4,
13-5,
13-6,
13-7,
14-1,
14-2,
14-3,
14-4,
14-5,
14-6,
14-7,
15-1,
15-2,
15-3,
15-4,
15-5,
15-6,
15-7,
16-1,
16-1,
16-2,
16-2,
16-2,
16-3,
16-3,
16-4,
16-4,
16-5,
304.8
304.9
305
305.1
305.3
305.51
305.7
305.9
306.07
306.31
306.47
306.68
307.01
307.62
308.01
309.18
310.7
312.18
312.94
314.48
316
317.47
318.8
320.32
321.79
322.5
323.94
325.5
326.97
328.49
330.14
331.51
331.73
332.51
333.43
333.73
334.38
334.64
335.28
336.67
336.98
337.88
52.468
52.471
52.474
52.477
52.484
52.490
52.496
52.503
52.508
52.516
52.521
52.528
52.538
52.557
52.570
52.607
52.655
52.702
52.726
52.775
52.823
52.869
52.912
52.960
53.006
53.029
53.074
53.124
53.170
53.219
53.271
53.314
53.321
53.346
53.375
53.385
53.405
53.413
53.859
54.876
54.889
54.926
24.89
24.04
24.94
23.67
22.61
23.18
22.86
18.26
25.9
19.14
15.34
20.93
22.18
22.68
27.75
28.42
29.25
25.1
18.62
26.68
27.14
28.2
27.47
21.46
9.18
19.07
17.14
17.42
17.28
16.59
17.9
18.94
19.77
18.9
18.14
19.74
18.12
18.16
17.12
19.46
21.99
17.46
7.72
7.19
7.54
6.75
5.99
6.27
5.97
3.77
8.93
4.16
2.65
5.01
5.76
5.94
10.66
12.12
13.29
7.77
3.78
9.15
9.94
11.17
9.74
5.17
1.18
3.62
3.24
3.32
3.3
3.01
3.61
3.8
4.25
3.8
3.58
4.15
3.57
3.61
3.25
4.24
5.58
3.69
0.56
0.62
0.62
0.64
0.68
0.59
0.61
0.78
0.45
0.75
0.89
0.72
0.65
0.65
0.52
0.51
0.45
0.65
0.79
0.55
0.5
0.47
0.47
0.66
0.88
0.7
0.68
0.72
0.7
0.68
0.64
0.62
0.65
0.6
0.67
0.59
0.64
0.68
0.74
0.66
0.64
0.73
0.17
0.18
0.19
0.18
0.18
0.16
0.16
0.16
0.16
0.16
0.15
0.17
0.17
0.17
0.2
0.22
0.2
0.2
0.16
0.19
0.18
0.19
0.17
0.16
0.11
0.13
0.13
0.14
0.13
0.12
0.13
0.12
0.14
0.12
0.13
0.12
0.13
0.13
0.14
0.14
0.16
0.16
0.8
0.79
0.82
0.83
1.02
0.91
0.96
1.27
0.69
1.26
1.53
1.05
1.04
1
0.63
0.56
0.56
0.92
1.3
0.71
0.6
0.58
0.65
1.03
1.89
1.31
1.31
1.33
1.3
1.35
1.29
1.23
1.17
1.26
1.3
1.21
1.3
1.3
1.34
1.34
1.16
1.51
0.25
0.24
0.25
0.24
0.27
0.25
0.25
0.26
0.24
0.27
0.26
0.25
0.27
0.26
0.24
0.24
0.26
0.29
0.26
0.24
0.22
0.23
0.23
0.25
0.24
0.25
0.25
0.25
0.25
0.25
0.26
0.25
0.25
0.25
0.26
0.25
0.26
0.26
0.25
0.29
0.29
0.32
0.05
0.05
0.06
0.05
0.05
0.05
0.05
0.05
0.05
0.06
0.05
0.05
0.05
0.05
0.06
0.04
0.04
0.04
0.04
0.04
0.05
0.05
0.04
0.04
0.04
0.05
0.04
0.04
0.05
0.04
0.04
0.04
0.04
0.04
0.04
0.04
0.04
0.04
0.06
0.06
0.06
0.06
0.02
0.02
0.02
0.01
0.01
0.01
0.01
0.01
0.02
0.01
0.01
0.01
0.01
0.01
0.02
0.02
0.02
0.01
0.01
0.01
0.02
0.02
0.02
0.01
0.01
0.01
0.01
0.01
0.01
0.01
0.01
0.01
0.01
0.01
0.01
0.01
0.01
0.01
0.01
0.01
0.01
0.01
30–32
40–42
50–51
60–62
80–82
101–103
120–122
140–142
7–9
31–33
47–48
68–70
101–103
12–14
51–52
49–50
51–52
49–50
44–45
48–49
50–51
47–48
45–46
47–48
44–45
50–51
44–45
50–51
47–48
49–50
64–65
51–52
22–23
102–103
43–44
73–74
138–139
14–15
78–79
67–69
97–99
37–39
D.J. Thomas, T.J. Bralower / Marine Geology 217 (2005) 233–254
Sample
51–53
70–72
94–96
116–118
141–143
2–4
9–11
22–24
28–30
44–46
50–52
64–66
93–95
51–52
50–51
50–51
49–50
47–48
50–51
45–46
338.02
338.21
338.45
338.6
338.85
339.03
339.1
339.23
339.29
339.45
339.51
339.65
339.94
341.53
343
344.5
346
347.47
349
350
54.932
54.940
54.949
54.956
54.966
54.973
54.976
54.982
54.984
54.991
54.993
54.999
55.014
55.103
55.184
55.267
55.351
55.432
55.517
55.572
15.72
14.5
9.12
13.05
3.34
1.32
0.51
0.49
0.54
0.48
0.5
7.72
14.55
22.46
20.77
22.93
21.81
17.48
14.83
19.03
3.03
2.67
1.32
2.25
0.4
0.15
0.06
0.06
0.07
0.05
0.06
1.11
2.77
6.58
6.05
7.68
9.28
6.06
3.83
7.13
0.85
0.85
0.96
0.93
1.1
1.06
1.16
1.11
1.22
1.11
1.08
1.06
0.88
0.62
0.73
0.71
1.13
1.51
1.36
1.46
0.16
0.16
0.14
0.16
0.13
0.12
0.13
0.12
0.15
0.13
0.12
0.15
0.17
0.18
0.21
0.24
0.48
0.52
0.35
0.55
1.69
1.81
2.41
2.19
2.97
3.03
3.11
3.04
2.96
2.85
2.82
2.21
1.57
0.75
0.57
0.46
0.51
0.66
0.76
0.59
0.33
0.33
0.35
0.38
0.36
0.34
0.34
0.34
0.36
0.32
0.32
0.32
0.3
0.22
0.17
0.16
0.22
0.23
0.2
0.22
0.05
0.05
0.07
0.07
0.07
0.08
0.08
0.07
0.08
0.05
0.05
0.07
0.07
0.06
0.06
0.06
0.04
0.06
0.08
0.06
0.01
0.01
0.01
0.01
0.01
0.01
0.01
0.01
0.01
0.01
0.01
0.01
0.01
0.02
0.02
0.02
0.02
0.02
0.02
0.02
Sample
Depth (mbsf)
Age (Ma)
V (ppm)
V/Al
Cr (ppm)
Cr/Al
Zr (ppm)
Zr/Al
Ba (ppm)
Ba/Al
Ni (ppm)
Ni/Al
12-4,
12-4,
13-1,
13-1,
13-1,
13-1,
13-1,
13-1,
13-2,
13-2,
13-2,
13-2,
13-2,
13-2,
13-2,
13-2,
13-2,
298.7
298.99
303.23
303.48
303.72
303.99
304.19
304.41
304.6
304.7
304.8
304.9
305
305.1
305.3
305.51
305.7
52.275
52.284
52.418
52.426
52.434
52.442
52.449
52.456
52.462
52.465
52.468
52.471
52.474
52.477
52.484
52.490
52.496
108
93
82
63
62
53
64
59
64
66
61
66
65
62
66
70
70
13.21
14.49
15.76
17.4
17.46
16.89
16.77
20.72
25.25
23.75
18.93
19.73
19.65
17.67
17.49
18.95
18.29
74
57
47
45
33
42
33
24
22
27
28
31
931
31
33
36
36
9.05
8.88
9.03
12.43
9.29
13.38
8.65
8.43
8.68
9.72
8.69
9.27
281.45
8.83
8.75
9.75
9.41
119
113
111
94
98
94
100
92
89
92
94
95
95
91
97
101
101
14.55
17.6
21.34
25.97
27.6
29.95
26.21
32.31
35.11
33.11
29.16
28.4
28.72
25.93
25.71
27.34
26.39
2035
1457
1131
1038
885
1103
967
891
1095
1164
982
1014
1123
1231
1008
1299
1360
248.87
226.95
217.39
286.73
249.21
351.45
253.41
312.92
431.93
418.92
304.67
303.15
339.5
350.82
267.12
351.64
355.42
107
57
45
56
29
29
29
22
17
22
26
28
3387
29
31
33
32
13.09
8.88
8.65
15.47
8.17
9.24
7.6
7.73
6.71
7.92
8.07
8.37
1023.94
8.26
8.22
8.93
8.36
70–72
99–101
23–25
48–49
72–75
99–101
119–122
141–143
10–12
20–22
30–32
40–42
50–51
60–62
80–82
101–103
120–122
D.J. Thomas, T.J. Bralower / Marine Geology 217 (2005) 233–254
16-5,
16-5,
16-5,
16-5,
16-5,
16-6,
16-6,
16-6,
16-6,
16-6,
16-6,
16-6,
16-6,
17-1,
17-2,
17-3,
17-4,
17-5,
17-6,
17-7,
249
250
D.J. Thomas, T.J. Bralower / Marine Geology 217 (2005) 233–254
Appendix B. Site 401 elemental data
Sample
Depth
(mbsf)
Age
(Ma)
Si
(%)
Si/Al
Ti
(%)
Al
(%)
Fe
(%)
Fe/Al
Mn
(%)
Mn/Al
Mg
(%)
Mg/Al
12-4,
12-4,
12-4,
12-4,
12-5,
12-5,
12-5,
13-1,
13-1,
13-1,
13-1,
13-1,
13-1,
13-1,
13-2,
13-2,
13-2,
13-3,
13-3,
13-4,
13-4,
184.11
184.56
185.07
185.42
185.86
185.99
186.57
189.09
189.31
189.49
189.7
189.93
190.11
190.3
190.91
191.53
191.76
192.48
193.04
193.95
194.59
50.87
50.99
51.13
51.22
51.34
51.37
51.53
52.20
52.25
52.30
52.36
52.42
52.47
52.52
52.68
52.84
52.91
53.10
53.25
53.49
53.66
7.57
7.56
8.25
7.58
7.59
6.87
9.17
6.46
7.93
7.52
7.55
12.52
9.4
5.79
5.42
5.14
4.08
6.11
3.63
9.05
8.45
3.22
3.34
3.21
3.17
3.19
3.16
3.2
3.26
3.2
3.21
3.34
2.66
2.96
3.39
3.22
3.17
3.22
3.14
3.39
3.42
3.42
0.13
0.12
0.13
0.13
0.13
0.12
0.16
0.11
0.14
0.13
0.12
0.22
0.16
0.09
0.09
0.09
0.07
0.1
0.06
0.2
0.21
2.35
2.27
2.57
2.39
2.38
2.18
2.86
1.98
2.48
2.34
2.26
4.71
3.18
1.71
1.68
1.62
1.26
1.95
1.07
2.65
2.47
1.31
1.24
1.33
1.29
1.29
1.18
1.52
1.11
1.31
1.23
1.17
2.32
1.59
0.86
0.81
0.8
0.66
0.94
0.55
1.53
1.5
0.21
0.21
0.19
0.2
0.2
0.2
0.2
0.21
0.2
0.2
0.19
0.19
0.19
0.19
0.18
0.19
0.2
0.18
0.19
0.22
0.23
0.09
0.09
0.08
0.08
0.09
0.09
0.08
0.09
0.07
0.07
0.07
0.07
0.07
0.07
0.07
0.07
0.07
0.06
0.07
0.08
0.09
0.04
0.04
0.03
0.03
0.04
0.04
0.03
0.04
0.03
0.03
0.03
0.01
0.02
0.04
0.04
0.04
0.05
0.03
0.07
0.03
0.04
0.42
0.39
0.43
0.44
0.46
0.41
0.49
0.39
0.45
0.44
0.4
0.68
0.51
0.34
0.33
0.31
0.29
0.35
0.25
0.49
0.46
0.18
0.17
0.17
0.18
0.19
0.19
0.17
0.19
0.18
0.19
0.18
0.14
0.16
0.2
0.19
0.19
0.23
0.18
0.23
0.19
0.19
1113
5658
107109
142144
3638
4951
107109
911
3134
4951
7072
9395
111113
130132
4143
103105
126128
4850
104106
4547
109111
Sample
Depth
(mbsf)
Age
(Ma)
Ca
(%)
Ca/Al
Na
(%)
Na/Al
K
(%)
K/Al
P
(%)
P/Al
12-4,
12-4,
12-4,
12-4,
12-5,
12-5,
12-5,
13-1,
13-1,
13-1,
13-1,
13-1,
13-1,
13-1,
13-2,
13-2,
13-2,
13-3,
13-3,
13-4,
13-4,
184.11
184.56
185.07
185.42
185.86
185.99
186.57
189.09
189.31
189.49
189.7
189.93
190.11
190.3
190.91
191.53
191.76
192.48
193.04
193.95
194.59
50.87
50.99
51.13
51.22
51.34
51.37
51.53
52.20
52.25
52.30
52.36
52.42
52.47
52.52
52.68
52.84
52.91
53.10
53.25
53.49
53.66
27.62
27.86
26.88
27.23
27.62
28.55
25.34
29.33
27.79
27.6
28.09
19.51
24.79
30.54
30.95
31.28
32.75
30.1
33.58
25.85
27.07
11.76
12.3
10.47
11.38
11.6
13.13
8.85
14.82
11.22
11.77
12.43
4.15
7.81
17.86
18.39
19.31
25.89
15.46
31.41
9.77
10.98
0.59
0.59
0.61
0.79
0.59
0.5
0.69
0.52
0.59
0.58
0.52
0.82
0.64
0.41
0.42
0.4
0.35
0.46
0.25
0.51
0.43
0.25
0.26
0.24
0.33
0.25
0.23
0.24
0.26
0.24
0.25
0.23
0.17
0.2
0.24
0.25
0.25
0.28
0.24
0.24
0.19
0.17
0.88
0.88
0.98
0.9
0.86
0.79
1.05
0.71
0.9
0.82
0.86
1.42
1.05
0.66
0.59
0.55
0.45
0.63
0.39
0.81
0.79
0.37
0.39
0.38
0.37
0.36
0.36
0.37
0.36
0.37
0.35
0.38
0.3
0.33
0.38
0.35
0.34
0.35
0.32
0.36
0.3
0.32
0.04
0.04
0.03
0.04
0.04
0.03
0.04
0.04
0.04
0.04
0.04
0.04
0.04
0.04
0.04
0.04
0.04
0.04
0.03
0.04
0.04
0.02
0.02
0.01
0.02
0.02
0.01
0.01
0.02
0.02
0.02
0.02
0.01
0.01
0.02
0.02
0.02
0.03
0.02
0.03
0.01
0.02
1113
5658
107109
142144
3638
4951
107109
911
3134
4951
7072
9395
111113
130132
4143
103105
126128
4850
104106
4547
109111
Sample
Depth
(mbsf)
Age
(Ma)
V
(ppm)
V/Al
Cr
(ppm)
Cr/Al
Zr
(ppm)
Zr/Al
Ba
(ppm)
Ba/Al
Ni
(ppm)
Ni/Al
12-4, 1113
12-4, 5658
12-4, 107109
184.11
184.56
185.07
50.87
50.99
51.13
48
42
46
20.43
18.54
17.92
16
17
12
6.81
7.5
4.67
77
82
79
32.77
36.2
30.78
647
823
727
275.33
363.32
283.22
11
10
14
4.68
4.41
5.45
D.J. Thomas, T.J. Bralower / Marine Geology 217 (2005) 233–254
251
Appendix B (continued)
Sample
Depth
(mbsf)
Age
(Ma)
V
(ppm)
V/Al
Cr
(ppm)
Cr/Al
Zr
(ppm)
Zr/Al
Ba
(ppm)
Ba/Al
Ni
(ppm)
Ni/Al
12-4,
12-5,
12-5,
12-5,
13-1,
13-1,
13-1,
13-1,
13-1,
13-1,
13-1,
13-2,
13-2,
13-2,
13-3,
13-3,
13-4,
13-4,
185.42
185.86
185.99
186.57
189.09
189.31
189.49
189.7
189.93
190.11
190.3
190.91
191.53
191.76
192.48
193.04
193.95
194.59
51.22
51.34
51.37
51.53
52.20
52.25
52.30
52.36
52.42
52.47
52.52
52.68
52.84
52.91
53.10
53.25
53.49
53.66
45
42
42
53
40
48
42
44
64
50
34
34
32
29
36
26
52
56
18.81
17.63
19.31
18.51
20.21
19.38
17.91
19.47
13.6
15.75
19.89
20.2
19.76
22.93
18.48
24.32
19.65
22.71
13
15
7
18
8
14
9
13
30
20
12
7
4
7
14
3
25
24
5.43
6.3
3.22
6.29
4.04
5.65
3.84
5.75
6.38
6.3
7.02
4.16
2.47
5.53
7.19
2.81
9.45
9.73
80
73
73
86
74
86
82
80
98
89
77
75
75
70
82
67
92
91
33.44
30.65
33.56
30.04
37.39
34.72
34.97
35.4
20.83
28.03
45.04
44.56
46.31
55.34
42.1
62.67
34.77
36.9
733
622
605
683
568
649
769
714
1365
748
862
719
648
710
660
563
614
634
306.41
261.17
278.13
238.54
286.96
262.02
327.99
315.94
290.11
235.55
504.25
427.21
400.12
561.31
338.87
526.62
232.03
257.06
13
16
11
26
14
15
11
11
37
24
38
6
7
3
9
2
25
18
5.43
6.72
5.06
9.08
7.07
6.06
4.69
4.87
7.86
7.56
22.23
3.57
4.32
2.37
4.62
1.87
9.45
7.3
142144
3638
4951
107109
911
3134
4951
7072
9395
111113
130132
4143
103105
126128
4850
104106
4547
109111
Sample
Depth
(mbsf)
Age
(Ma)
Zn
(ppm)
Zn/Al
Ga
(ppm)
Ga/Al
Sr
(ppm)
Sr/Al
Nb
(ppm)
Nb/Al
12-4,
12-4,
12-4,
12-4,
12-5,
12-5,
12-5,
13-1,
13-1,
13-1,
13-1,
13-1,
13-1,
13-1,
13-2,
13-2,
13-2,
13-3,
13-3,
13-4,
13-4,
184.11
184.56
185.07
185.42
185.86
185.99
186.57
189.09
189.31
189.49
189.7
189.93
190.11
190.3
190.91
191.53
191.76
192.48
193.04
193.95
194.59
50.87
50.99
51.13
51.22
51.34
51.37
51.53
52.20
52.25
52.30
52.36
52.42
52.47
52.52
52.68
52.84
52.91
53.10
53.25
53.49
53.66
34
34
35
35
36
33
44
31
38
34
31
59
43
25
24
24
24
27
22
40
40
14.47
15.01
13.64
14.63
15.12
15.17
15.37
15.66
15.34
14.5
13.72
12.54
13.54
14.62
14.26
14.82
18.97
13.86
20.58
15.12
16.22
5
3
3
3
3
3
5
3
3
3
3
9
3
3
3
3
3
3
3
3
3
2.13
1.32
1.17
1.25
1.26
1.38
1.75
1.52
1.21
1.28
1.33
1.91
0.94
1.75
1.78
1.85
2.37
1.54
2.81
1.13
1.22
624
693
670
695
611
636
639
624
652
622
634
615
651
719
715
748
730
744
700
560
577
265.55
305.93
261.02
290.53
256.55
292.38
223.17
315.25
263.23
265.29
280.54
130.71
205.01
420.6
424.83
461.87
577.12
382
654.76
211.62
233.95
8
7
8
6
7
7
8
7
9
8
8
10
10
6
7
6
7
7
5
10
8
3.4
3.09
3.12
2.51
2.94
3.22
2.79
3.54
3.63
3.41
3.54
2.13
3.15
3.51
4.16
3.7
5.53
3.59
4.68
3.78
3.24
1113
5658
107109
142144
3638
4951
107109
911
3134
4951
7072
9395
111113
130132
4143
103105
126128
4850
104106
4547
109111
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