Quaternary climate change as revealed by calcium carbonate fluctuations in western Equatorial Atlantic sediments

Damuth, John E.

doi:10.1016/0011-7471(75)90078-9

Cited by 32 publications

(54 citation statements)

References 35 publications

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“…in the carbonate curve follow closely variations in the oxygen isotope curve (Prell and Hays, 1977;McIntyre et al, 1972;Damuth, 1975b;Laine, 1977).…”

Section: Previous Investigators Have Established That Variationsmentioning

confidence: 76%

Studies of deep-sea sedimentary microtopography in the North Atlantic Ocean

Flood¹

1978

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partial fulfillment of the requirements for the degree of Doctor of Philosophy.. ABSTRACTMany of the small-scale topographic features (dimensions of centimeters to kilometers) found on the Blake-Bahama Outer Ridge (western North Atlantic, water depth greater than 4000 m) and in the Rockall Trough (northeastern North Atlantic, water depth greater than 2000 m) have been formed as bed forms of deep currents. These bed forms, all developed in cohesive sediments, include current ripples (spacings of tens of centimeters, formed transverse to the flow), longitudinal triangular ripples (spacings of meters, formed in sandy muds and parallel to the flow), furrows (spacings of tens to 100's of meters, formed parallel to the flow and presently either erosional or depositional), and regular sediment waves (spacings of a few kilometers, now found oblique to the flow and migrating either upstream or downstream).The local distribution of any given bed form is influenced by the presence of larger features. Bed forms are often found in zones which strike parallel to the regional contours.Debris flows, affecting areas of 1000's to 10,000's of square kilometers, are also present in these areas. A debris flow studied in the Rockall Trough is erosional at its shallowest depths and depositional at greater depths. Gravitational flows strike perpendicular to the contours. Pockmarks (tens of meters in diameter, marking fluid seeps) are also found on the Blake-Bahama Outer Ridge.The larger topographic features (greater than several meters) with steep slopes (greater than about 200) can be observed on surface echo-sounding profiles either as fields of regular hyperbolic echoes (e.g., echoes from regularly spaced furrows), fields of irregularly spaced, dissimilar hyperbolae (e.g., echoes from blocks, ridges, and folds in debris flows), or as regular features whose structfre is often obscured by side echoes (e.g., echoes fro .sediment waves).Although nearbottom investigations are required to describe the features, the nature of the sea floor can often be inferred from the character of the echo-sounding profile. Similar echo-sounding records in different areas of the ocean indicate the presence of similar sea-floor features.The morphology of the bed forms studied and the current and temperature structure of the overlying water column lead to conclusions about bed form origin and present-day interactions with deep currents.Furrows form as erosional bed forms during high-velocity (>20? cm/sec) current events by large, helical secondary circulations in the bottom boundary layer. Once formed, furrows may develop into depositional features, or they may continue as erosional ones, depending on the local currents and the sediment supply.Large, regular sediment waves may be formed at current speeds of 5 to 10 cm/sec by lee waves generated by topographic irregularities on the sea floor, such as submarine canyons, or by instabilities in the flow of deep, contour-following currents. Sediment waves develop where there is an abundant supply of sediment an...

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“…in the carbonate curve follow closely variations in the oxygen isotope curve (Prell and Hays, 1977;McIntyre et al, 1972;Damuth, 1975b;Laine, 1977).…”

Section: Previous Investigators Have Established That Variationsmentioning

confidence: 76%

Studies of deep-sea sedimentary microtopography in the North Atlantic Ocean

Flood¹

1978

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“…However, several glacial stages (22−24, 16, 12, 10, 8, and 4) show high carbonate and sand contents. Such records are not consistent with either those from pelagic sections of the equatorial Atlantic (Damuth, 1975;Jansen et al, 1984;Verardo and McIntyre, 1994), or with the values of the last interglacial-glacial change of Hole 959C. Bulk calcium carbonate mass accumulation rates closely follow bulk mass accumulation (Fig.…”

Section: Long-term Trends Carbonate and Coarse-fraction Analysismentioning

confidence: 72%

“…In various previous studies (Berger and Winterer, 1976;Damuth, 1975;Hays et al, 1976;Morley, 1977;Morley and Hays, 1981), variations in biogenically produced CaCO 3 were used to reconstruct the oceanographic conditions in the South Atlantic (and in other oceans) in conjunction with oxygen isotope stratigraphic 14 C dates and foraminifer biostratigraphy. At 18 ka, the calcite-compensation depth in (Shipboard Scientific Party, 1996).…”

Section: Gradual Trends Of Sedimentation Over the Last 125 Ky (Intementioning

confidence: 99%

“…Various studies of eastern equatorial Atlantic sediments (Sarnthein et al, 1981;Jansen et al, 1984;Pokras and Molfino, 1986;Jansen and Van der Gaast, 1988;Tiedemann et al, 1989;Bonifay and Giresse, 1992) showed the onset of enhanced trade winds via an onset of coastal upwelling activities during the glaciation period. Low sea level largely occurred during the last glaciation with prominent minima between 12 and 24 ka and between 61 and 74 ka (Damuth, 1975). The diffractometric ratio of quartz to kaolinite was measured for each bulk sample and plotted against depth; the values are slightly uneven, but the highest are observed in the interglacial episode of Stage 5.…”

Section: Gradual Trends Of Sedimentation Over the Last 125 Ky (Intementioning

confidence: 99%

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Indicators of climate and sediment-source variations at Site 959: implications for the reconstruction of paleoenvironments in the Gulf of Guinea through Pleistocene times

Giresse¹,

Gadel²,

Serve³

et al. 1998

Proceedings of the Ocean Drilling Program, 159 Scientific Results

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Leg 159 Ocean Drilling Project Site 959 (in 2100 m water depth and ~120 km off the west African coast) is located on a small plateau that extends on the northern flank of the Côte d'Ivoire-Ghana Marginal Ridge. Because of its topographic position, this site was largely isolated from mass gravitational or turbidity flows coming from the continental shelf and slope. This very steep transform margin, on the other hand, has probably established interference of bottom-water circulation. The Hole 959C depth corresponds roughly to the interface between North Atlantic Deep Water and South Atlantic Intermediate Water. The very moderate linear sedimentation rates (~1−2 cm/k.y.) are relatively constant throughout the Pleistocene interval. This pronounced low sedimentation rate most likely reflects the persistent activity of deep-water circulation. Based on the oxygen isotopic record, two stratigraphic gaps are reported between 1.6 and 0.99 Ma and between 0.20 and 0.12 Ma, and are attributed to enhanced bottom-water circulation. This water circulation implies that significant changes in winnowing activity occurred in this site during the last 1 m.y. Detailed microstructural analysis indicates a number of laminae 1 mm to 1 cm thick with increased concentration of foraminifers resulting from the recurrent winnowing process (contourite). Many more glauconitic infillings of foraminifers were observed ~1−0.9 Ma, just after the major hiatus. Assuming that the superficial redistribution of the sediment was favorable to longer contact with seawater and to mineralization, the green grain concentration supports the indication of an uneven beginning of sedimentation after the hiatus.The carbonate average concentrations tend to increase from ~20%−30% in the lower part of the section to ~35%−40% in the upper part. Organic carbon increases ~0.7%−0.8% in the lower part to 1%−1.1% in the upper part. However, accumulation rates for carbonate and organic carbon closely follow bulk accumulation rate records that correspond to an average of the bottom-current winnowing intensity. Consequently, cyclic variations in relative abundances of carbonate and noncarbonate components do not appear to correspond clearly or closely to glacial/interglacial cycles. The older section (before 1.5 Ma) shows some evidence of maxima in productivity of calcareous foraminifers during interglacial cycles. Conversely, maxima of organic carbon are connected to glacials and may be enhanced by local upwelling. Both of these indicators have been used in the same way to identify the steps of the last 125 k.y. Such cyclic variations are similar to those of neighboring sites on the slope of the eastern equatorial Atlantic, but from ~1 to ~0.2 Ma, the highest variabilities are recorded and attributed to enhanced sediment redistribution. In the same section, the highest variation ranges of major components prevailed at the time when the climatic change had the maximum effect. It is difficult to assess, therefore, if eustatic and climatic cycles or stronger current in...

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“…During the interglacials poor preservation of planktonic foraminifera coincides with low CaCO 3 percent. Luz and Shackleton (1975) (Gardner, 1975;Damuth, 1975;B6 et al, 1976;Thunnell, 1976). Several authors, however, claimed that CaCO 3 cycles in the Atlantic are not caused by dissolution (e.g.…”

Section: Evidence For Caco3 Cycles Representing Dissolution Cyclesmentioning

confidence: 99%

The Influence of differential production and dissolution on the stable isotope composition of planktonic foraminifera

Erez¹

1978

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Planktonic foraminifera from plankton tows, sediment traps and sediments from the central North Atlantic were studied in order to understand how they acquire their oxygen and carbon isotope compositions. Shallow dwelling planktonic foraminifera (mostly spinose species), collected in plankton tows in the photic zone, show light isotopic compositions possibly in slight negative deviation from oxygen isotopic equilibrium.Radioactive tracer experiments using 14C and 4 5 Ca were conducted on shallow dwelling benthonic foraminifera and hermatypic corals. They show that photosynthesis of symbiotic algae within these organisms increases the amount of metabolic C02 incorporated into the skeleton which consequently becomes isotopically lighter. Because shallow dwelling planktonic foraminifera contain symbiotic algae it is suggested that their light isotopic compositions are also caused by photosynthetically enhanced incorporation of metabolic C02 in the skeleton. ACKNOWLEDGEMENTSIt is my pleasure to acknowledge the individuals and institutions who supported the work which led to this thesis.

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Quaternary climate change as revealed by calcium carbonate fluctuations in western Equatorial Atlantic sediments

Cited by 32 publications

References 35 publications

Studies of deep-sea sedimentary microtopography in the North Atlantic Ocean

Studies of deep-sea sedimentary microtopography in the North Atlantic Ocean

Indicators of climate and sediment-source variations at Site 959: implications for the reconstruction of paleoenvironments in the Gulf of Guinea through Pleistocene times

The Influence of differential production and dissolution on the stable isotope composition of planktonic foraminifera

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