LATE QUATERNARY δ13C RESULTS FROM ODP LEG 165 SITE 1002C, CARIACO BASIN, VENEZUELA

One latest threat to modern ocean ecosystems is ocean freshening, where increases in intensity and frequency of climatic patterns lead to more persistent freshwater lenses, thus driving biological and chemical shifts via ocean stratification. The prevalence of the Intertropical Convergence Zone (ITCZ) in the Cariaco Basin, Venezuela, dates to at least 14 ka. The ITCZ, a semi-permanent regional low-pressure belt, provides the area with increased riverine input and upwelling, contributing to periods of ocean freshening and productivity. The ITCZ’s influence on the Cariaco Basin sediments makes the basin ideal for this study. The Cariaco Basin (northern continental shelf of Venezuela) is a well-known semi-enclosed basin and has been extensively studied using various proxies. Although there have been numerous studies on these proxies, few studies have focused on inorganic carbon isotopes (δ¹³C). Tests of Orbulina universa, a mixed-layer planktonic foraminifera, were collected from Late Quaternary (Marine Isotope Stages 1-9) Ocean Drilling Program (ODP) Site 1002C to establish a record of productivity and signals of localized ocean freshening. Here, we provide one of the first δ¹³C records at Site 1002C, combining a second higher resolution phase spanning Marine Isotope Stages (MIS) 2–8, with the first phase’s exploratory δ¹³C record spanning MIS 1-9. δ¹³C values range from 0.67 ‰ to 3.06 ‰. The productivity record presented here is concomitant with signals of localized ocean freshening, likely due to the position of the ITCZ and associated trade winds leading to the wet and dry conditions identified in the basin’s sedimentary record.