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| Format: | Artículo científico |
| Language: | en |
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Universidad Nacional Autónoma de México
2006
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| Online Access: | https://www.redalyc.org/articulo.oa?id=57230205 |
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Table of Contents:
- Geophysical modeling of Valle de Banderas graben and its structural relation to Bahía de Banderas, Mexico Román Álvarez Vsevolod Yutsis Jorge A. Arzate Jesús Pacheco Héctor López Loera Ciencias de la Tierra Mexico gravity Jalisco Block magnetotellurics Valle de Banderas A gravimetric survey consisting of fi ve lines and 483 stations, as well as a magnetotelluric (MT)survey consisting of 17 observation sites, were made in the Valle de Banderas region for the determinationof the structural characteristics of the valley. Additionally, data from a previous aeromagnetic surveywere analyzed to correlate them with our geophysical measurements. The gravimetric and MT modelsconfi rm that the valley corresponds to a graben structure with slumped blocks that vary from ~2000 mdeep close to Bahía de Banderas to shallow burial depths (~100 m) toward the NE end of the valley. Faultsfl anking the valley, inferred from the gravity and magnetic models, trend toward offshore faults in Bahíade Banderas, indicating a structural connection between land and sea. From the MT measurements weconclude that a 2-D resistivity behavior is observed within the graben whereas outside of the graben thebehavior is 1-D, in spite of the rough topography of this region. Our gravimetric models also indicatethe occurrence of basin-like structures within the graben, coinciding with similar structures reportedoffshore in the Bahía de Banderas, suggesting that such structures may be typical erosional features ofthe graben. The aeromagnetic analysis correlates with the gravimetric and MT models, and suggeststhat the graben structure is an extensional zone on granitic crust; it also indicates that the extensionalzone continues to the NE, beyond the topographic limits of Valle de Banderas on land and towards Bahíade Banderas seawards. We propose that this region belongs to the same tectonic structure in spite ofan approximate change in orientation of 30° between the bay and the valley, and strengthen the ideathat this graben constitutes part of the NW limit of the Jalisco Block. A tectonic model for the region ispresented at various stages, from around 10075 Ma to the Present. We propose that initiation of theBahía de Banderas structure started at ~14 Ma along an E-W trend, and that at ~5 Ma the graben axiswas reoriented to a SW-NE direction, that induced the formation of Valle de Banderas. 2006 artículo científico 1026-8774 https://www.redalyc.org/articulo.oa?id=57230205 en http://www.redalyc.org/revista.oa?id=572 Revista Mexicana de Ciencias Geológicas application/pdf Universidad Nacional Autónoma de México Revista Mexicana de Ciencias Geológicas (México) Num.2 Vol.23