There are currently no detailed directional PSV records from most of the Southern Hemisphere prior to the last 3000 years and only one detailed Holocene (last 12,000 years) paleointensity record from anywhere in the Southern Hemisphere. This critical data gap precludes developing spherical harmonic models for prehistoric time intervals to better understand dynamo sources in the Earth's deep interior or to even properly interpret PSV records in the Northern Hemisphere. ODP Leg 202 Sites 1233, 1234, 1235 and Site Survey cores adjacent to the southern Chilean margin provide an exceptional opportunity to address this data gap. In this project, the investigators intend to: (1) Recover four replicate directional PSV records spanning the Holocene from deep-sea sediment cores collected adjacent to the southern Chilean continental margin (35 degreesS-50 degreesS). (2) Recover at least two replicate paleointensity records from these same cores. (3) Carry out a careful rock magnetic study of all sediments (magnetic mineralogy, ARM, IRM, CHI, plus selected AMS and hysteresis measurements) to assess where environmental effects might be biasing the directional or paleointensity data. (4) Carry out a regional inter-comparison of all Holocene PSV records from this region to assess data quality and integrate them into an existing Holocene PSV database for future modeling studies. Results from this proposal will significantly aid development of spherical harmonic models of the Earth's Holocene field variability and provide a much better view of the overall space/time variability of the field. Such observations and models are required to properly assess the nature of dynamo processes acting within the Earth's core. Broader Impacts: This project will mentor at least one high school student, one undergraduate student and a paid graduate student. Final paleomagnetic datasets will be made available on the PI's website (http://earth.usc.edu/~slund) and forwarded as a contribution to other database initiatives.
