Neogene Magnetostratigraphy, Relative Paleointensity, and High-Resolution Magnetic Record of IODP Site U1514 (Mentelle Basin, Australia)
Abstract
We present high-resolution paleomagnetic and rock magnetic results from the Neogene part of the APC-cored section (13 - 68 mbsf) of International Ocean Discovery Program (IODP) Site U1514 (33º 7.233'S; 113º 5.467'E, 3838 m water depth). This site was cored as part of the IODP Australia Cretaceous Climate and Tectonics Expedition to address (1) paleoceanographic, paleoclimatic, and tectonic questions about the evolution of the high-latitude southwestern margin of Australia and (2) to obtain a continuous Cenozoic sediment record in the Mentelle Basin. The upper 80-m of Site U1514 consist of a sequence of pale brown to pale yellow nannofossil ooze, foraminiferal ooze, and nannofossil ooze that is Pleistocene to Eocene in age and show cyclic sedimentary variations. Ages were obtained from magnetostratigraphy (Chrons C13r through C2r) with biostratigraphic controls. We collected rock magnetic and paleomagnetic measurements at 1-cm resolution on 55-m of U-channel samples (representing ~32 myr. including 3 hiatuses), with the goal of extracting a high-resolution magnetostratigraphy and records of paleoenvironmental variability and relative geomagnetic paleointensity. Stepwise demagnetization of the natural remanence (NRM) demonstrates the successful removal of a secondary, predominantly drill-string induced, magnetization and identification of a stable and strong primary magnetization carried by the sediment samples (average MAD calculated by principal component analysis: ~1.4º). Excellent behavior of the samples during alternating field demagnetization suggests magnetite as the main carrier of magnetic remanence. Relative paleointensity estimates were determined by normalizing the NRM by the ARM (slope method) and magnetic susceptibility. Time-frequency analyses of high-resolution concentration and grain-size dependent rock magnetic proxy data will be presented with the goal of identifying the driver of cyclic changes in the sedimentary section.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMGP51B0645R
- Keywords:
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- 1165 Sedimentary geochronology;
- GEOCHRONOLOGY;
- 1520 Magnetostratigraphy;
- GEOMAGNETISM AND PALEOMAGNETISM;
- 4910 Astronomical forcing;
- PALEOCEANOGRAPHY