%0 Journal Article %T Paleomagnetism of Ar-Ar dated lava flows from the Ceboruco-San Pedro volcanic field (western Mexico): Evidence for the Matuyama-Brunhes transition precursor and a fully reversed geomagnetic event in the Brunhes chron %+ École normale supérieure - Paris (ENS-PSL) %+ Institut de Physique du Globe de Paris (IPGP) %A Petronille, Marie %A Goguitchaichvili, Avto %A Henry, Bernard %A Alva-Valdivia, Luis M. %A Rosas-Elguera, José %A Urrutia-Fucugauchi, Jaime %A Rodriguez Cejá, Maria %A Calvo-Rathert, Manuel %< avec comité de lecture %@ 2169-9313 %J Journal of Geophysical Research : Solid Earth %I American Geophysical Union %V 110 %P pp. 655-675. %8 2005 %D 2005 %Z 2005JGRB..110.8101P %R 10.1029/2004JB003321 %Z Sciences of the Universe [physics]Journal articles %X We report a detailed paleomagnetic and rock magnetic study of 17 independent lava flows belonging to the Trans-Mexican Volcanic Belt; 175 oriented samples were collected in the Ceboruco-San Pedro volcanic field. These sites were previously dated by means of a state-of-the-art 40Ar-39Ar geochronological method and span from 819 to 2 ka. Rock magnetic experiments, which included continuous susceptibility and hysteresis measurements, point to simple magnetic mineralogy. In most cases, the remanence is carried by Ti-poor titanomagnetite of pseudosingle-domain magnetic structure. Fourteen flows give normal magnetic polarities, while two are reversely magnetized; only one cooling unit yields intermediate paleodirections. The paleodirections of the flow dated at 819 ± 25 ka correspond to a VGP latitude of 18°N. This anomalous field behavior apparently recorded prior to the Matuyama-Brunhes (M-B) reversal may coincide with the transitionally magnetized lavas on La Palma, Canary Islands (40Ar-39Ar age of 822.2 ± 8.7 ka), and with an event featured in several marine sediment records. Thus this geomagnetic event, defined as M-B precursor, is probably global in extent. Two independent lava flows, dated at 623 ± 91 and 614 ± 16 ka, yield reverse paleodirections. Age uncertainties make it difficult to claim the discovery of a new geomagnetic event. It is possible that these lavas erupted during the worldwide observable Big Lost event (40Ar-39Ar age of 580.2 ± 7.8 ka), which has probably been longer and more complex than it is generally believed for geomagnetic excursions. %G English %2 https://insu.hal.science/insu-03601112/document %2 https://insu.hal.science/insu-03601112/file/Journal%20of%20Geophysical%20Research%20Solid%20Earth%20-%202005%20-%20Petronille%20-%20Paleomagnetism%20of%20Ar%25u2010Ar%20dated%20lava%20flows%20from%20the.pdf %L insu-03601112 %U https://insu.hal.science/insu-03601112 %~ INSU %~ UNIV-PARIS7 %~ ENS-PARIS %~ AFRIQ %~ CNRS %~ IPGP %~ RIGL %~ PSL %~ SORBONNE-UNIVERSITE %~ UNIV-PARIS %~ ENS-PSL %~ SU-TI %~ ALLIANCE-SU