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

Abstract

El graben El Gordo yace dentro de la litosfera oceanica al oeste de la Trinchera Meso-Americana a 18.15°N, 104.7°W. Se ha propuesto a este graben como una marca del hundimiento aJ suroeste de una zoua activa de extension ubicada entre las placas de Rivera y Cocos. Los resultados de un an:ilisis de las anomalfas de gravedad de Manto-Bouguer en el area de graben El Gordo. yen el area ubicada entre el graben y la Dorsal del Pacifico Este, son consistentes con esta propuesta, asi como tambien con Ia propuesta de que la zona de extension se puede estar propaganda hacia Ia Dorsal del Pacifico Este. Especificamente: (1) Una disminucion prominente en los valores de la Anomalfa de Manto-Bouguer ocurre en el area del graben El Gordo, estando Iadisminucion maxima sobre el complejo volcani co El Gordo, ubicado en el centro del graben. Esta disminucion es modelada comoel resultado de una intrusion de magma dentro de Ia corteza oceanica del graben centrada bajo cl complejo volcanico El Gordo.Este modelo es respaldado por un flujo de calor en superficie alto en el area de este complejo. (2) Se observa un alto gravimetricode la anomalfa de A ire Libre NE-SW que se extiende desde el graben El Gordo hasta la Dorsal del Pacffico Este. Sin embargo, solola parte oeste de esta anomalfa es observada en el mapa de Anomalia de Manto-Bouguer. El modclado de los valores de la Anomalia de Manto-Bouguer indica que esta anomalfa puede deberse a un adelgazamiento de Ia corteza en esta region. Sin embargo, a diferencia del area del graben El Gordo, los datos gravimetricos y batimetricos son escasos en esta area, por lo que este resultado es preliminar.doi: sin doi

Morphology and magnetic survey of the Rivera-Cocos plate boundary of Colima, Mexico

“…Many previous studies have used the seafloor morphology and the seafloor spreading magnetic lineation data to try to resolve the kinematics and deformational history of this area. Some of these studies were of a regional focus (e.g., Mammerickx and Klitgord, 1982; Klitgord and Mammerickx, 1982;Atwater, 1989); whereas others were focused more directly on various aspects of the kinematics of the Rivera Plate (e.g., Eissler and McNally, 1984;DeMets and Stein, 1990;Bandy, 1992;Bandy and Pardo, 1994;DeMets and Wilson, 1997;Bandy et al, 1997Bandy et al, , 1998DeMets and Traylen, 2000;Jaramillo and Suárez, 2011) or on the complexities of the various boundaries of the Rivera Plate (e.g., Bourgois et al, 1988;Bandy et al, , 2005Kostoglodov and Bandy, 1995;Pardo and Suárez, 1995;Lonsdale, 1995;Michaud et al, 1997Michaud et al, , 2000Michaud et al, , 2001Serrato-Díaz et al, 2004). Although all of these studies have made significant contributions to understanding the tectonics of the Rivera plate, they have yet to provide a clear understanding of either the recent evolution of the northernmost segment of the EPR-PCS, or the nature of the Rivera-Cocos plate boundary.…”

“…A variant on this proposal is that of DeMets and Wilson (1997) who proposed that the boundary is a difuse zone of left lateral, NNE-SSW oriented shearing. The second group (Bandy, 1992;Kostoglodov and Bandy, 1995;Bandy et al, 1995Bandy et al, , 1998Serrato-Díaz et al, 2004) proposes that El Gordo Graben is the tip of a rift between the Rivera and Cocos plates and that this rift is currently propagating SW towards the EPR, resulting in a situation that is analogous to the present day Galapogos triple junction (Lonsdale, 1988). The divergence between the Rivera and Cocos plates is proposed by Bandy (1992) to be the result of the ridge-trench collision off the southern tip of Baja California at about 8 Ma (Lonsdale, 1991) and subsequent pivoting of the Rivera plate away from the rest of the Cocos Plate, a proposal that is consistent with the results of recent seismic studies (Yang, et al, 2009;León Soto et al, 2009).…”

Analysis of the Current Dynamic of the Jalisco Block, Mexico through GNSS Observations

“…The JB is mainly influenced by the oblique subduction of the Rivera plate in the western part; likewise, it is delimited by two continental deformation zones. To the east is the Colima rift (CR), trending N-S [7], which is a tectonic structure with purely extensional deformation [8] that has been considered by some as researchers as the eastern limit of the JB [9], whereas in the north is the Tepic-Zacoalco (TZR) rift [10], which runs NW-SE [11].…”