The late Triassic-early Jurassic active continental margin of western north America in northeastern Mexico

Abstract

Exposures of Triassic-Jurassic volcanic sequences in northeastern Mexico suggest that they developed along an active continental margin. Other sequences in support of such a tectonic environment are exposed in Durango, Zacatecas, San Luis Potosi, Nuevo Leon and Tamaulipas, where siliciclastic flysch sediments to the west and an older metamorphic continental block to the east underlie the volcanics. It is proposed that these Triassic to Jurassic volcanic rocks and associated redbeds from middle to northeastern Mexico are genetically related to a Jurassic active continental margin. The red beds of easternmost Mexico are either associated with rifting related to the break-up of Pangea, or preferably to a back-arc basin and to the younger transgressive Callovian to Oxfordian sequence, beginning with redbeds and associated to the basin evolution of the Gulf of Mexico and an eastern passive continental margin.