The Mexican Volcanic Belt structure and tectonics.

Abstract

The Mexican Volcanic Belt appears to be an ancient suture which was reopened in Middle Tertiary times. Its irregular zigzag course. with large volcanoes rising on its southern corners suggests that. the suture suffered major transcurrent displacements early in geologic history. The igneous activity of the belt -mostly andesitic lavas- may be derived from melting of the oceanic Cocos Plate upon suffering subduction in the Acapulco Trench. No connection exists between the Clarion Fracture Zone and the belt's large volcanoes, which only form an apparent east-west alignment. Probably the crustal weakness into which the East Pacific Rise entered upon rifting the Gulf of California originally formed, with the belt's suture, a single ancient zone of weakness.