Biogenic opal production in the Agulhas Current and its connection to aridification in South Africa during the mid-Pleistocene

Author(s): Ruiz Marin, Eduardo; Coenen, Jason; Scherer, Reed P.; Stansell, Nathan D.
Integrated Ocean Drilling Program, Expedition 361 Scientists, College Station, TX
Author Affiliation(s): Primary:
Northern Illinois University, Department of Geology and Environmental Geosciences, DeKalb, IL, United States
Volume Title: Geological Society of America, North-Central Section, 52nd annual meeting
Source: Abstracts with Programs - Geological Society of America, 50(4); Geological Society of America, North-Central Section, 52nd annual meeting, Ames, IA, April 16-17, 2018. Publisher: Geological Society of America (GSA), Boulder, CO, United States. ISSN: 0016-7592 CODEN: GAAPBC
Note: In English
Summary: We present a record of biogenic opal production near the Agulhas Current and Benguela upwelling region from IODP Site U1479, collected during Expedition 361. Records from ODP Leg 177, Sites 1090 and 1089, suggest arid climates in South Africa, as suggested by net productivity of diatoms at these sites. A change from obliquity to eccentricity cycles dominated the Mid-Pleistocene Transition (MPT) (800 kyr-1.07 Ma), which led to an increase in ice mass during glacial periods. Glacial and interglacial changes caused fluxes in biogenic silica transport in the Agulhas Current and the Benguela upwelling region. With the biogenic opal % we infer significant increases in nutrients to the site during the onset of the MPT. We are tracking opal % fluxes in U1479 from Marine Isotope Stage-18 (MIS-18) to MIS-21, around 800 kyr, to evaluate nutrient fluxes and production, and relate it to the distribution of Benguela upwelling events. Our current data include 29 intervals down core at a 10,000-year resolution showing fluxes in the biogenic silica during the MPT. Preliminary results indicate that during about 770-855 kyr there was an increase in biogenic silica production, similar to the observed event at ODP Sites 1090 and 1089. With improvements in the age model we hope to solidify this high production event of biogenic silica to better understand the timing in relation to Sites 1090 and 1089 and other Benguela upwelling studies.
Year of Publication: 2018
Research Program: IODP Integrated Ocean Drilling Program
IODP2 International Ocean Discovery Program
Key Words: 24 Surficial Geology, Quaternary Geology; Africa; Agulhas Current; Atlantic Ocean; Biogenic processes; Cape Basin; Cenozoic; Climate change; Expedition 361; Framework silicates; IODP Site U1479; International Ocean Discovery Program; Marine environment; Middle Pleistocene; Opal; Paleoclimatology; Paleoecology; Paleoenvironment; Pleistocene; Quaternary; Silica; Silica minerals; Silicates; South Africa; South Atlantic; Southeast Atlantic; Southern Africa
Coordinates: S350332 S350331 E0172405 E0172403
Record ID: 2018064987
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States