A triple junction in the Gulf of Mexico: Implications for deep petroleum exploration

Abstract

Mesozoic redbed and salt sequences have recently been dated using a palynostratigraphical method developed at the Mexican Petroleum Institute (IMP) since 1975. They represent the early Mesozoic marine transgression which formed the petroleum systems. The information from 1969 to 1993 for the Rhaeto-Liassic redbed Los San Pedros Allogroup and Huayacocotla Group (Huayacocotla-El Alamar Basin), Middle Jurassic La Joya Formation (Chihuahua Sabinas Sub-basin), Middle Jurassic Rosario and Cahuasas formations (Tampico-Misantla Sub-basin) and Middle Jurassic Todos Santos Formation (Veracruz and Southeastern sub-basins) and Middle Jurassic salt units (Southeastern sub-basins) and the caprock of the Challenger Knoll, drilled in the Gulf of Mexico, are reviewed. After these data an unconformity between the igneous-metamorphic basement and the Middle Jurassic redbeds in some sub-basins of the Gulf of Mexico, and between the Liassic sedimentary rocks and the Middle Jurassic redbeds in the Huayacocotla-El Alamar, Tlaxiaco and Huamuxtitlán basins is proposed. The Triple Junction Model includes three different periods: (1) the formation of one or two Rhaeto-Early Liassic wrench or shear basins (Huayacocotla-El Alamar); (2 formation of the Tampico-Misantla Sub-basin during Late Liassic, and (3 , the origin of the Gulf of Mexico Basin and the Chihuahua-Sabinas, Veracruz and Southeastern sub-basins during the Early Middle Jurassic. A triple junction system allowed the northwestward displacement of the Texas-Louisiana Block and the western region of Mexico away from the stable Chiapas-Yucatán Block along the Vancouver-Bahamas and Texas-Sabinas alignments and the Pico de Orizaba-Laguna Inferior Megashear. From geochemical data oil and gas-producing provinces are predicted in continuation of the Chihuahua-Sabinas, Tampico-Misantla and southeastern sub-basins.