Middle American geology and evolution

Abstract

Middle America involves many geographic elements, ranging from the intensely explored areas of southern N America, the Gulf of Mexico and northern S America to the dispersed and less well-understood complex of islands, basins and volcanic arcs in between. Many different models have been proposed to explain its evolution. They involve varying locations and movements of major blocks, such as Maya and Chortis, and several explanations for the opening of the Grenada and Yucatan supposed back-arc basins. A major debate concerns the origin and content of the Caribbean Plate. Did it form as oceanic crust in the Jurassic Pacific, where it thickened into an oceanic plateau before entering between N and S America, driving before it the “Great Arc of the Caribbean”, or did it form in-place, sharing a history of continental extension with the eastern seaboard of N America and the Gulf of Mexico? Regional NE and NW tectonic fabric, reflecting reactivation of ancient structures, argues for the latter (and denies major block rotations). Similarity with the Scotia and Banda areas, both formed by intra-continental extension, also supports this model. Crustal thicknesses, silicic rocks and ancient inherited zircons point to continental content. Thickening of section from mainland S America to many kilometres of distal (meta) sediments interbedded with lavas and volcanic rocks suggests continental extension with seaward-dipping wedges. Seismic data over the Caribbean oceanic plateau suggest extended continental fabric that carries rifts with salt diapirs, wedges of seaward-dipping reflections and thinned “oceanic” crust. Middle America will be best understood when all available data are integrated and discussed — the theme of this conference.

AAPG Datapages/Search and Discovery Article #90330©2018 AAPG Hedberg: Geology of Middle America – the Gulf of Mexico, Yucatan, Caribbean, Grenada and Tobago Basins and Their Margins “Integration of the geology of the area from the southern onshore of North America to the northern onshore of South America”, Siguenza, Guadalajara, Spain, July 2-5, 2018