The Gulf of Cádiz contourite laboratory; variability in sediment composition over the past 200 ky

Author(s): O'Brien, Sean P.; Krissek, Lawrence
Author Affiliation(s): Primary:
Ohio State University, School of Earth Sciences, Columbus, OH, United States
Volume Title: Geological Society of America, 2014 annual meeting & exposition
Source: Abstracts with Programs - Geological Society of America, 46(6), p.344; Geological Society of America, 2014 annual meeting & exposition, Vancouver, BC, Canada, Oct. 19-22, 2014. Publisher: Geological Society of America (GSA), Boulder, CO, United States. ISSN: 0016-7592 CODEN: GAAPBC
Note: In English
Summary: Integrated Ocean Drilling Program Expedition 339 drilled contourite deposits in the Gulf of Cadiz and West Iberian margin. These recovered sedimentary successions provide key data for examining the development of the Mediterranean Outflow Water and the subsequent evolution of a complex contourite depositional system. In this study, we investigate MOW variability using mineralogy as a proxy. The major terrigenous mineral phases at Sites U1387 and U1389 were identified to define sediment composition and interpret its provenance. Temporal changes in sediment composition are analyzed over the last glacial/interglacial cycle, in order to identify changes in sediment provenance, continental weathering regimes, and/or dispersal patterns. The shipboard age model was used to assign sediment ages (a constant sedimentation rate of 25 cm/ky for Site U1387 and 40 cm/ky for Site U1389). The samples investigated range from Recent to 200 ka, with a sampling interval of ∼4 ky. Randomly mounted pressed powder samples were examined using x-ray diffractometry to identify bulk mineralogy. Semiquantitative mineral abundances in each sample are estimated by comparing the ratio of a mineral's selected peak area to that of the 4.26 Å quartz peak. These values are compared with respect to Marine Isotope Stages. Preliminary results show that the primary mineral phases include: quartz, calcite, dolomite, aragonite, feldspar, and a variety of clay minerals. This composition is consistent with adjacent onshore lithologies, and is also consistent with shipboard XRD results. No strong link between mineral phases and glacial/interglacial phases is detected. Average ratio values are generally higher during interglacial cycles.
Year of Publication: 2014
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 24 Surficial Geology, Quaternary Geology; Atlantic Ocean; Cenozoic; Clastic sediments; Contourite; Expedition 339; Gulf of Cadiz; IODP Site U1387; IODP Site U1389; Integrated Ocean Drilling Program; Marine environment; Marine sediments; Mineral composition; North Atlantic; Paleoenvironment; Pleistocene; Quaternary; Sediments; Upper Pleistocene; X-ray diffraction data
Coordinates: N364819 N364820 W0074308 W0074308
N362530 N362531 W0071641 W0071641
Record ID: 2015029337
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States