Stratigraphic Correlation of Seismo-Turbidites in Japan Trench using Paleomagnetic Secular Variation
Abstract
A thick turbidite unit associated with the 2011 Tohoku-oki earthquake, and two older thick turbidite units (TT2 and TT3), which are most likely to have been induced by great earthquakes similar to the 2011, were discovered in the Japan Trench floor. Dating those deposits is crucial to understand the recurrence of Tohoku-oki earthquake. Because the basins are located in the hadal zone, obtaining detailed stratigraphic ages is generally difficult. However, paleomagnetic secular variation has been proved to be useful approach to date slope sequences in the Japan Trench composed of frequent thinner turbidite sequences below CCD. We tested if the similar approach can work for thick turbidite sequences in the trench. Paleomagnetic and rock-magnetic analyses were carried out on the samples. We measured magnetizations of demagnetized NRM, and ARM. We found that MDF of ARM profiles in TT3 unit is characterized by an unique pattern. Contrary, a constant MDF in TT2 with high magnetic susceptibility spike in the base was recognized. Assuming that those magnetic signatures are stratigraphic ties, we compared the paleomagnetic secular variation patterns to a reference. Especially declination changes can be well correlated to that of the reference. We confirmed precise correlations of turbidite units in Japan Trench are possible, and the secular variation is available up to 4,000 years ago at least in the Trench basin.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMGP34A..03K
- Keywords:
-
- 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