Full Vector Studies of the Last 10 Thousand Years Derived From The East Maui Volcano Hawaii

We have determined the paleointensity of nine lavas flows that recorded the last 10 kyrs of geomagnetic field behavior from the youngest and largest of the two edifices of the island of Maui (i.e. Hana Volcanics, East Maui) with the multispecimen parallel differential pTRM method [Dekkers and Böhnel, EPSL, 248, 508-517, 2006]. The flows are characterized by irreversible Curie curves indicating two kinds of magnetic carriers: one almost pure magnetite and the second one Ti-rich magnetite with possible traces of titanomaghemite. The coercivity of remanence (Hcr) suggests that low-coercivity grains carry the NRM. Magnetic minerals from all of these flows are scattered within the PSD range with the exception of site HKAM (age 4.07±+0.09 ka) that lies in the SD range. The multispecimen method involves giving a laboratory pTRM to pristine specimens in different field strengths parallel to the original TRM; note that all pTRMs are given within the same range. From an existing sample collection for paleosecular variation studies [Herrero-Bervera and Valet, PEPI, 161, 267-280, 2007] we processed samples from 9 flows for paleointensity determinations ranging in age from 0.830.06 ka to 8.19±0.06 ka. pTRMs were given by in-field heating and cooling from 175 and to 260°C to avoid alteration. Low-field susceptibility variation appeared to be less than 10%, and sample sets from a few flows were heated to two different temperatures to check for consistency of results. All flows yielded good quality data. The paleointensity values increase to ~46 microTesla at ~ 2.2 ka and drop to ~22 microTesla at ~3.5 ka. At ~8.2 ka, ~39 microTesla is obtained, i.e. slightly higher than the present-day value (36 microTesla). Our paleointensity results (at least 7 flows) correlate well with the absolute paleointensity global determinations. The influence of a recently proposed domain-state correction [Fabian and Leonhardt, 2010, EPSL] on the paleointensity values will be investigated and shown.