A geophysical investigation of the southern Jalisco block in the State of Colima, Mexico.

Abstract

Se reportan estudios de geología y de campos potenciales en el Estado de Colima, México, para estudiar la extensión neotectónica previamente interpretada a través del Graben de Colima. Nuestros estudios indican que la extensi6n tectónica al sur del Volcán de Colima es nula o muy pequeña y que los rasgos interpretados previamente como estructuras extensionales son rasgos erosionales relacionados con antiguas deformaciones o a cortes de barrancas producidos por la rápida sedintentaci6n del Volcán de Colima.doi: sin doi

Active rifting and crustal thinning along the Rivera-Cocos plate boundary as inferred from Mantle Bouguer gravity anomalies

“…The geometry and motion of the various lithospheric plates and blocks comprising western Mexico, both onshore and offshore, has recently received much attention (e.g., Mammerickx, 1984;Luhr et al, 1985;Bourgois etal., 1988;Allan et al, 1991;Bandy, 1992;Serpa et al, 1992;Bandy and Pardo, 1994;Bandy etal., 1995Bandy etal., , 1998aLonsdale, 1995;DeMets and Wilson, 1997;Suarez et al, 1999;Michaud et a[., 2000Michaud et a[., , 2001Bourgois aildMichaud, 2002). Of particular interest to the present study; is the current debate concerning the location and nature of the boundary between the Rivera and Cocos plates.…”

“…The data used in this study consists of (1) marine gravity data obtained from the National Geophysical Data Center (NGDC), Boulder Colorado, (2) previously published land gravity data (Skidmore, 1988;Serpa et al, 1992;Bandy et al, 1993), (3) previously unpublished land gravity data collected from 1992 to 1999, and (4) bathymetric data from Bandy (1992) and more recent marine data presently available from the NGDC. All of the land gravity data are referenced to the absolute gravity base station located at the Oceanographic Institute, Manzanillo, Mexico (location = l9°03'45.545"N, 104°18'08.800"W; elevation with respect to the WGS-77 ellipsoid= -11.15 m; absolute gravity = 978581.46 mGal) (Ness, 1984), and are reduced to complete Bouguer Anomaly values using the Mexico terrain correction data base of Aiken et al (1997).…”

Paleomagnetism of Plio-Quaternary basalts in the Jalisco block, western Mexico

“…Suarez (1993, 1995) located the top of the Wadati-Benioff zone at approximately 100 km depth under the Mascota and Talpa de Allende grabens; this depth is typical for magma generation by melting of subducting slabs. The second hypothesis proposes that they are due to rifting of the J alisco Block away from the North American plate; the rifting being caused by NW motion and NW -SE stretching of the Jalisco block relative to the North American plate (Luhr et al, 1985;Serpa et al, 1989;Righter and Carmichael, 1992;Wallace et al, 1992;Bandy, 1992;Maillol and Bandy, 1994b;Kostoglodov and Bandy, 1995). The third hypothesis also proposes that the extension is due to rifting of the Jalisco Block away from the North American plate; unlike the second proposal, however, this hypothesis proposes a SW motion of the Jalisco Block relative to the North American Plate Harrison, 1989, 1990;Rosas-Elguera et al, 1993;Ferrari et al, 1994).…”

“…It is disrupted by several NW-SE to NE-SW oriented grabens, including the Mascota and Talpa de Allende grabens, which contain both recent alkaline and calc-alkaline volcanic rocks (Luhr et al, 1989;Carmichael, 1990, 1991;Righter and Carmichael, 1992;Wallace et al, 1992). Rifting and associated volcanism has been attributed to rifting of the Jalisco block away from the North American plate; the rifting would involve a NW movement of and NW -SE stretching of the Jalisco block relative to the North American plate (Luhr et al, 1985;Nieto-Obreg6n, 1985;Serpa et al, 1989;Righter and Carmichael, 1992;Wallace et al, 1992;Bandy, 1992;Maillol and Bandy, 1994b;Kostoglodov and Bandy, 1995).…”