Variations in paleotemperatures and paleoenvironmental proxies associated with OAE1a

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Author(s): Brassell, Simon C.
Author Affiliation(s): Primary:
Indiana University, Department of Geological Sciences, Bloomington, IN, United States
Volume Title: AGU 2011 fall meeting
Source: American Geophysical Union Fall Meeting, Vol.2011; American Geophysical Union 2011 fall meeting, San Francisco, CA, Dec. 5-9, 2011. Publisher: American Geophysical Union, Washington, DC, United States
Note: In English
Summary: Evidence from biomarker paleotemperature proxies of temporal variations in ocean temperatures during Cretaceous Oceanic Anoxic Events prompts evaluation of stratigraphic trends in molecular and isotopic compositions and in elemental abundances that may reflect biological responses to fluctuations in palaeoenvironmental conditions, especially levels of oxygenation. The major variations in biomarkers and other geochemical proxies for the organic-rich sediment sequence from Shatsky Rise (ODP Site 1207) that corresponds to OAE1a (early Aptian) and exhibits two cooler intervals based on TEX86 measurements include: (i) decreasing concentrations of 2-methylhopanes derived from cyanobacteria with increasing temperature, (ii) a correspondence of the lycopane index with Mo concentrations, which both reflect anoxic conditions that appear more prevalent during warmer intervals, and (iii) fluctuations in V concentrations that reflect temperature trends, and correspond closely with organic C contents, except where Corg >30%. These results suggest that changes in ocean temperatures during OAE exert an influence on surface ocean conditions that govern seasonal productivity and stratification, but remain independent from the primary controls on anoxia.
Year of Publication: 2011
Research Program: ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Bacteria; Biomarkers; Cretaceous; Cyanobacteria; Isotopes; Leg 198; Mesozoic; North Pacific; Northwest Pacific; OAE 1; ODP Site 1207; Ocean Drilling Program; Oceanic anoxic events; Pacific Ocean; Paleoenvironment; Paleotemperature; Shatsky Rise; West Pacific
Coordinates: N374700 N374800 E1624600 E1624500
Record ID: 2018028729
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