Developing a High-Resolution Paleointensity Assisted Chronology Through the Matuyama-Brunhes Transitional Interval (0.7 to 1.25 Ma) for the NE Pacific From IODP Expedition 341, Sites U1417 and U1418
Abstract
Our understanding of the geomagnetic field and its application as a stratigraphic dating method are fundamentally limited by a lack of high quality records from many regions of the globe. The NE Pacific is one such region, not only lacking in quality paleomagnetic records, but as a region that is difficult to date using traditional Quaternary marine sediment methods, that would greatly benefit from detailed magnetic stratigraphies. We present u-channel and shipboard paleomagnetic data focusing on Matuyama-Brunhes transitional interval ( 0.7 to 1.25 Ma) from two IODP Sites (U1417 and U1418) drilled during Expedition 341 (South Alaska). Progressive AF demagnetization of u-channel samples, constrained by hysteresis data in the 100 to 200 m (CCSF-a) interval of Site U1417 define a well resolved, low coercivity, magnetization consistent with geocentric axial dipole expectations that improves upon reliable shipboard directions and intensities. Although ultrahigh resolution (>1 m /kyr) Site U1418 could not be u-channeled through the 400 to 900 m (CSF-a) rotary cored interval, correlations between u-channel data at Site U1417 and shipboard data at Site U1418 are robust enough to allow transference of its substantially more complete oxygen isotopic record to Site U1417. Passing all criteria for reliability, normalized remanence at Site U1417 using both ARM acquisition and ARM demagnetization, provides a relative paleointensity proxy that can be correlated with well-dated paleointensity stacks. This comparison allows an initial paleointensity assisted chronology to be developed; facilitating evaluation of both regional climate records through the middle Pleistocene transition, and the paleo-geomagnetic record that preserves polarity transitions, excursions, intensity variations, and secular variation during both polarities.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFMGP51D..02S
- Keywords:
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- 1135 Correlative geochronology;
- GEOCHRONOLOGYDE: 1165 Sedimentary geochronology;
- GEOCHRONOLOGYDE: 1520 Magnetostratigraphy;
- GEOMAGNETISM AND PALEOMAGNETISMDE: 1535 Reversals: process;
- timescale;
- magnetostratigraphy;
- GEOMAGNETISM AND PALEOMAGNETISM