Extreme climatic conditions recorded in Santa Barbara Basin laminated sediments: the 1835–1840Macoma event

Schimmelmann, Arndt; Lange, Carina B.; Berger, Wolfgang; Simon, Antoine; Burke, Susan; Dunbar, Robert B.

doi:10.1016/0025-3227(92)90134-4

Cited by 54 publications

(35 citation statements)

References 39 publications

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“…This overall rate of decrease is thought to be a minimum value as the near-surface sample was "soupy" and particularly difficult to sample. A layer of intact pelecypods at 0.25 mbsf was believed to reflect the "Macoma oxygenation event" (Schimmelmann et al, 1992) indicating that APC coring had washed away approximately the top 30 cm of sediment (Kennett, Baldauf, et al, 1994). The near-surface total count is therefore probably an underestimate.…”

Section: Resultsmentioning

confidence: 99%

“…The presence of a sediment that is fully anaerobic to the surface is unusual (Soutar and Gill, 1977), and the lack of bioturbation will result in deposited organic carbon encountering only strictly anaerobic processes at the sediment surface before being incorporated into laminae. A considerable amount of work has been published on SBB sediments, although this has principally focussed on sediment geochemistry and cores of less than 75 cm (Soutar and Crill, 1977;Lange et al, 1987;Reimers et al, 1990;Bernhard and Reimers, 1991;Grant, 1991;Schimmelmann and Tegner, 1991;Schmidt and Reimers, 1991;Kennedy and Brassell, 1992;Schimmelmann et al, 1992). Other investigators have obtained samples up to 9 mbsf using piston and gravity cores for the purpose of determining sedimentary structures and marker layers (Thornton, 1986;Schimmelmann et al, 1990), sulfur chemistry (Schimmelmann and Kastner, 1993), and bacterial methanogenesis and methane oxidation rates Doose and Kaplan, 1981).…”

Section: Introductionmentioning

confidence: 99%

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Bacterial Profiles in Deep Sediments of the Santa Barbara Basin, Site 893

Cragg¹,

Parkes²,

Fry³

et al. 1995

Proceedings of the Ocean Drilling Program

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Bacterial depth profiles were obtained from high-organic-load sediments (water depth 538 m) to a depth of 68.28 m below seafloor. Using the Acridine Orange Direct Count (AODC) technique, near-surface bacterial populations were 1.27 × 10 9 cells/ cm 3 . Numbers of bacteria decreased rapidly to 4.77 × 10 6 cells/cm 3 at 12 mbsf and then more slowly to 2.51 × 10 6 cells/cm 3 at 68.28 mbsf (505-fold decrease). Dividing cells represented approximately 10% of the total count but decreased at a greater rate (850-fold). There was an abrupt change in the rate of total bacterial population decrease at approximately 13 mbsf. Bacterial numbers were strongly correlated (P « 0.002) with total organic carbon. Near-surface concentrations of organic carbon rapidly decreased from approximately 3.6% to 2.0% at 13 mbsf, and thereafter remained at 1.5%-2.0% to the base of the core at 68.28 mbsf, indicating a high level of recalcitrance. The changes in the rate of bacterial population decrease with depth may be a response to increasingly recalcitrant organic carbon. High levels of methane (4100 µmol/L) were found at 9.0 mbsf, although the maximum concentration present in the sediment at this site may be in an unsampled horizon above this depth. At greater depth, methane concentrations were still high (>IOOO µmol/L), and although this area has many seeps of oil and gas, the C|/C 2+ ratios indicate a biogenic rather than a fhermogenic source.This work represents the first detailed microbiological analysis of deep sediment layers from the Santa Barbara Basin.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Bacterial Profiles in Deep Sediments of the Santa Barbara Basin, Site 893

Cragg¹,

Parkes²,

Fry³

et al. 1995

Proceedings of the Ocean Drilling Program

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“…Together with the abundant flux of organic material from the highly productive surface waters, this leads to the accumulation of anoxic muds at the seafloor. These sediments are characterized by distinctly enriched organic-carbon contents and the preservation of annual light/ dark laminations (varves) caused by seasonal variations in the biogenic and terrigenous sediment, growth of bacterial mats, and/or bottom-water oxygenation (e.g., Soutar and Crill, 1977;Lange et al, 1987Lange et al, , 1990Reimers et al, 1990;Baumgartner et al, 1991;Schimmelmann et al, 1992). The high surface-water productivity is mainly controlled by the California Current System (CCS), which itself is triggered by ocean-atmosphere interactions over broad areas of the Pacific Ocean.…”

Section: Modern Setting In the Santa Barbara Basinmentioning

confidence: 99%

A 160,000-Year High-Resolution Record of Quantity and Composition of Organic Carbon in the Santa Barbara Basin (Site 893)

Stein¹,

Rack²

1995

Proceedings of the Ocean Drilling Program

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To identify the factors controlling the organic-carbon accumulation in the Santa Barbara Basin and their relationship to the (global) climatic history through the last 160,000 years, total organic carbon (TOC), Rock-Eval parameters, and C/N ratios were determined on 990 samples from Hole 893A. For a selected set of samples, n-alkanes and pristane/phytane ratios were also determined. In the major lithologies, TOC values vary between 1% and 4%, with the higher values more typical for the interglacials and the lower values more typical for the glacials. The source of the organic matter is a mixed marine/terrigenous type, with a higher marine proportion during interglacials. Gray flood/turbidity deposits and sandy turbidites are characterized by significantly lower TOC values of 0.9%-1.8% and 0.1%-0.3%, respectively, with a clear terrigenous origin.During the Holocene, increased surface-water productivity and the inflow of oxygen-depleted waters from the East Pacific probably resulted in anoxic bottom water and, thus, in the preservation of varved-like laminations and large amounts of marine organic carbon. During the warm interstadials 5e and 5a, surface-water productivity and, thus, marine organic carbon flux also increased; anoxic bottom water conditions, however, were not reached throughout, as indicated by the dominance of massive non-laminated sediments. Furthermore, distinct higher-frequency variations of a few thousands of years are present in Stages 1, 5a, and 5c. During glacial Stages 6 and 4 to 2 and cold interstadials 5d and 5b, surface-water productivity was reduced and the bottom-water conditions in the Santa Barbara Basin were more oxygenated. At those times of lowered sea level, also the supply of terrigenous organic matter was probably increased.

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“…Although the accuracy of these tsunami reports, and even the existence of a tsunami, have been questioned, most researchers concede that a tsunami of some size probably did occur (e.g., Lander et al, 1993;Marine Advisors, 1965;Sylvester, 1978;McCulloch, 1985). Subsequent identification of a large underwater slide (Yerkes et al, 1981) along the north slope of the western Santa Barbara Channel, and its dating to within the time of the earthquake (1811ti yr) (Schimmelmann et al, 1992) strongly indicates that a subsea slide triggered by the earthquake was the likely source of this tsunami.…”

Section: Historical Tsunamis Within the Santa Barbara Channelmentioning

confidence: 99%