HR: 08:18h
AN: GP51A-02    [Abstracts]
TI: An Improved Hawaiian Secular Variation Curve for the Last 25 ka
AU: * Pressling, N J
EM: earnjp@earth.leeds.ac.uk
AF: University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, United Kingdom
AB: The Big Island of Hawaii has been the subject of numerous palaeomagnetic studies. The surface lava flows from the Kilauea, Mauna Loa and Hualalai volcanoes are abundant and accessible, resulting in 77 published absolute palaeointensity determinations for the time period 0--25 kyrs. These palaeointensity estimates are well constrained in time due to an extensive ¹⁴C dating program carried out by the US Geological Survey. 15 of the surface flows have been re-dated using accelerator mass spectrometry (AMS) and the implications of the revised ¹⁴C ages will be presented. In addition to the outcrop data, borehole data from the Hawaii Scientific Drilling Project (HSDP) core, Scientific Observation Hole 1 (SOH1) drill core and Scientific Observation Hole 4 (SOH4) drill core add a further 252 palaeointensity values to the database. Lake sediment data is also available for this period from Lake Waiau, located near the summit of Mauna Kea. Combining all the Hawaiian data and using the cubic-B spline method of curve fitting, a smooth, weighted curve has been obtained for each of the palaeomagnetic components. The trends seen in the improved secular variation curve for Hawaii will be discussed and compared to the trends seen in the global datasets PINT2003, SINT-800 and NAPIS-75, as well as global ¹⁰Be isotope data and archaeomagnetic data. The fit of the CALS7K.2 global model to the data will also be discussed.
DE: 1521 Paleointensity
DE: 1522 Paleomagnetic secular variation
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2007 Joint Assembly