Absolute paleointensity determinations on late Miocene and Pliocene volcanic rocks from south- eastern Spain

HR: 0800h
AN: GP41E-02 [Abstracts]
TI: Absolute paleointensity determinations on late Miocene and Pliocene volcanic rocks from south-eastern Spain
AU: * Calvo, M
EM: mcalvo@ubu.es
AF: Universidad de Burgos Departamento de Física, Av. Cantabria, s/n, Burgos, 09006, Spain
AU: Gogochaichvili, A
EM: avto@geofisica.unam.mx
AF: Laboratorio de Magnetismo Natural, Instituto de Geofisica, UNAM, Tzintzuntzan 310, Morelia, 58098, Mexico
AB: Rock magnetic and paleointensity investigations have been carried out on late Miocene and Pliocene volcanic rocks from the eastern Betic region, in the south-eastern part of the Iberian Peninsula. Neogene volcanism in that region is related to fault activity and basin formation, and from a petrological point of view, four types of volcanic rocks can be distinguished: a) calc-alkaline volcanics (K/Ar ages between 15 and 8 M.y.), b) potassic calc- alakaline volcanics (K/Ar ages between 8.3 and 6.6 M.y.), c) lamproitic volcanic rocks (K/Ar ages between 8.6 and 5.7 M.y.) and d) basaltic alkaline volcanics (K/Ar ages between 2.8 and 2.7 M.y.). Besides paleomagnetic analysis, rock-magnetic studies, including thermomagnetic curves (magnetization and susceptibility versus temperature), measurement of hysteresis parameters, IRM acquisition and demagnetisation, VRM acquisition experiments as well as ore-microscopic analysis were performed in order to obtain information about the carriers and the stability of remanence. The main carrier of characteristic remanence is low-Ti titanomagnetite, although calk alkaline and lamproitic volcanics also show the presence of titanohematite, which appears related to the same paleomagnetic component. Paleointensity determinations were performed with the Thellier and Thellier (1959) stepwise double-heating method as modified by Coe (1967) on samples from 16 sites, all four types of volcanic rocks being represented in the experiment. The study is still in progress.
DE: 1521 Paleointensity
DE: 1540 Rock and mineral magnetism
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2007 Joint Assembly