Paleomagnetic and rock-magnetic survey of Brunhes lava flows from Tancitaro volcano, Mexico
This study presents paleomagnetic results from Tancitaro volcanism in the Michoacan Guanajuato Volcanic Field, western Mexico, as a contribution to the time averaged field global database. Detailed paleomagnetic and rock–magnetic studies were carried out on eleven independent lava flows; 120 oriente...
| Autores: | , , , , , , , , |
|---|---|
| Tipo de documento: | artigo |
| Estado: | Versão publicada |
| Data de publicação: | 2009 |
| País: | México |
| Recursos: | UNIVERSIDAD NACIONAL AUTÓNOMA DE MÉXICO |
| Repositório: | Geofísica Internacional |
| Idioma: | espanhol inglês |
| OAI Identifier: | oai:revistagi.geofisica.unam.mx:article/307 |
| Acesso em linha: | http://revistagi.geofisica.unam.mx/index.php/RGI/article/view/307 |
| Access Level: | Acceso aberto |
| Palavra-chave: | Paleosecular variation time averaged field Brunhes chron Trans–Mexican Volcanic Belt Paleomagnetismo variación paleosecular promedio de tiempo de campo epoca Brunhes Cinturón Volcánico Trans–Mexicano |
| Resumo: | This study presents paleomagnetic results from Tancitaro volcanism in the Michoacan Guanajuato Volcanic Field, western Mexico, as a contribution to the time averaged field global database. Detailed paleomagnetic and rock–magnetic studies were carried out on eleven independent lava flows; 120 oriented, standard paleomagnetic cores were collected from Tancitaro volcano and surrounding areas. All sites were dated by means of 40Ar–39Ar (Ownby et al., 2007) as originating from 793 ka to present. Rock–magnetic experiments included continuous susceptibility and hysteresis measurements. Remanence is carried mostly by Ti–poor titanomagnetite of pseudo–single–domain magnetic structure. Eight out of eleven flows yield normal magnetic polarities while three sites yielded inconsistent paleodirections most probably due to lightning. Mean paleodirection from eight flows is Inc=39.5°, Dec=356.4°, k=29, αc95=9.1° which corresponds to a pole position with Plat=84.4°, Plong=219.9°, K=33 and A95=8.5°, practically undistinguishable from expected Plio–Quaternary paleodirections, for the North American Craton. Paleosecular variation is compatible with other studies at the same latitude bands and with recent statistical models. The mean inclination falls within the uncertainties of the Geomagnetic Axial Dipole plus 5% quadrupolar contributions. |
|---|