Geochemistry and isotopes at DSDP Leg 80 Holes, supplement to: Cunningham, Robert; Kroopnick, Peter M (1985): Inorganic and isotopic geochemistry of sediments from Sites 549 to 551, northeastern North Atlantic. In: De Graciansky, PC; Poag, CW; et al. (eds.), Initial Reports of the Deep Sea Drilling Project, Washington (U.S. Gov. Printing Office), 80, 1073-1079

• Main Authors: Cunningham, Robert, Kroopnick, Peter M
• Format: Article in Journal/Newspaper
• Language: English
• Published: PANGAEA - Data Publisher for Earth & Environmental Science 1985
• Subjects: Deep Sea Drilling Project DSDP; North Atlantic
• Online Access: https://dx.doi.org/10.1594/pangaea.808145; https://doi.pangaea.de/10.1594/PANGAEA.808145

Thirty-eight samples from DSDP Sites 549 to 551 were analyzed for major and minor components and trace element abundances. Multivariate statistical analysis of geochemical data groups the samples into two major classes: an organic-carbon- rich group (> 1% TOC) containing high levels of marine organic matter and certain trace elements (Cu, Zn, V, Ni, Co, Ba, and Cr) and an organic-carbon-lean group depleted in these components. The greatest organic and trace metal enrichments occur in the uppermost Albian to Turanian sections of Sites 549 to 551. Carbon-isotopic values of bulk carbonate for the middle Cenomanian section of Site 550 (2.35 to 2.70 per mil) and the upper Cenomanian-Turonian sections of Sites 549 (3.35 to 4.47 per mil) and 551 (3.13 to 3.72 per mil) are similar to coeval values reported elsewhere in the region. The relatively heavy d13C values from Sites 549 and 551 indicate that this interval was deposited during the global "oceanic anoxic event" that occurred at the Cenomanian/Turonian boundary. Variation in the d18O of bulk carbonate for Section 550B-18-1 of middle Cenomanian age suggests that paleosalinity and/or paleotemperature variations may have occurred concurrently with periodic anoxia at this site. Climatically controlled increases in surface-water runoff may have caused surface waters to periodically freshen, resulting in stable salinity stratification