This proposal seeks to develop a paleomagnetic chronology for sites 1395 and 1396 using cores drilled offshore of Monserrat during IODP exp. 340. The cores are hemipelagic sediments intercalated with tephra/ash and turbidites. The cores provide a continuous record of sedimentation and volcanic activity, 1.1 MY for site 1395 (9 cm/kyear), 4.5 MY for site 1396 (3 cm/kyear). Records are superior to extant terrestrial and marine records. Both cores record magnetic reversals; 4 in 1395 and 17 in 1396. The U-channel samples for the study are in hand, stored at 4oC at Oregon St. The magnetic properties of core (pseudo-single domain ferromagnetic grains) are ?ideal? for recording magnetic field behavior and paleointensity. Proposed work includes: 1.Develop a detailed magnetochronology. Deconvolute measurements, make high precision measurements, do high resolution RPI at reversal intervals. Chronology will be correlated with O isotope and Ar-Ar work on the same cores. 2.Environmental and stratigraphic work. Use the differing magnetic properties of volcanic and hemipelagic sediments to identify and log tephra layers. Tephrochronology. Attempt to identify sources of tephra, e.g. different island volcanos have different lava compositions and magnetic properties. Relate magnetitc properties to grain size, weathering history etc. 3.Other. Will look for Saharan dust. Length of record provides opportunity to examine behavior of geomagnetic field. The work will be accomplished by creation of a composite spliced record of 1395 and 1396 to aid in sample selection for U-channel work,. The samples will be progressively demagnetized and NRM measured at the cm scale. MS, ARM, and IRM will be used to identify magnetic minerals. This information will be used to develop a proxy for RPI. Selected samples will be disaggregated to determine particle size properties of the magnetic minerals and relate this to the environmental record.
BROADER IMPACTS: This project will directly support a postdoctoral research associate at OSU and an undergraduate student who will be trained in measurement, data processing and interpretation of paleomagnetic data. The complete data set will be made available to the research community through the MAGIC database.
