Magnetostratigraphy, Rock Magnetism and Relative Paleointensity (RPI) Study of IODP Expedition 381, Corinth Rift.
Abstract
We have studied the magnetostratigraphy, rock magnetism, paleomagnetic properties and relative paleointensity (RPI) of Plio-Quaternary syn-rift sediments recovered during IODP Expedition 381 from the Gulf of Corinth (Greece). A total of 1415 cubic ( 8 cm3) specimens were collected throughout the 1.9 km of drilled sedimentary sequence at 0.75 m spacing from four holes (M0078A, M0078B, M0079A, and M0080A). Bulk magnetic susceptibility (k) and natural remanent magnetization (NRM) were measured before stepwise demagnetizing the samples using 13 alternating field (a.f.) steps up to 100 mT. Characteristic remanent magnetization (ChRM) components were isolated at 45-50 mT after having removed the secondary components of magnetization at 5-10 mT. The NRM intensity is characterized by a direct linear relationship with the magnetic susceptibility. Curie points (i.e., k-T) have indicated the presence of at least four predominant magnetic mineral phases, with temperatures of 320-400°C (greigite), 520 to 575°C (Ti-poor magnetite) and maghemite 6000C. The inclination of the ChRM components from the four holes show both positive and negative inclinations with values close to the expected inclination at the sampling locality (i.e., 58°N), which allowed us to build a preliminary magnetostratigraphy for the cored sediments. A number of intervals within the youngest syn-rift sediments are characterized by lower or higher inclinations, which might represent excursions and/or Subchrons of the geomagnetic field documented within the Brunhes and Matuyama Chrons. In order to test this hypothesis, we have imparted anhysteretic remanent magnetizations (ARM) and saturation isothermal remanent magnetizations (SIRM) to all the recovered specimens, and used the ratios between their intensity, the NRM and susceptibility to determine the relative paleointensity (RPI) and compare it to the geomagnetic instability time scale of Singer (2014).
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMGP43B0778H
- Keywords:
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- 1520 Magnetostratigraphy;
- GEOMAGNETISM AND PALEOMAGNETISMDE: 1527 Paleomagnetism applied to geologic processes;
- GEOMAGNETISM AND PALEOMAGNETISMDE: 1535 Reversals: process;
- timescale;
- magnetostratigraphy;
- GEOMAGNETISM AND PALEOMAGNETISMDE: 1540 Rock and mineral magnetism;
- GEOMAGNETISM AND PALEOMAGNETISM