Middle Miocene Chiapas fold and thrust belt of Mexico: a result of collision of the Tehuantepec Transform/Ridge with the Middle America Trench
Published:January 01, 2009
J. J. Mandujano-Velazquez, J. Duncan Keppie, 2009. "Middle Miocene Chiapas fold and thrust belt of Mexico: a result of collision of the Tehuantepec Transform/Ridge with the Middle America Trench", Ancient Orogens and Modern Analogues, J. B. Murphy, J. D. Keppie, A. J. Hynes
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The Middle Miocene, thin-skinned, Chiapas fold-and-thrust belt (Gulf of Mexico–southeastern Mexico–Belize) consists of WNW-trending folds and thrusts, and East–West sinistral transcurrent faults resulting from N60°E shortening. Balanced cross-sections indicate that shortening varies from 48% (SW) to c. 8% (NE) with a total shortening of 106 km, and that thrusts merge into a basal décollement in the Callovian salt horizon. The Middle Miocene age of the deformation is synchronous with collision of the Tehuantepec Transform/Ridge with the Middle America Trench off Chiapas. The presently exposed Tehuantepec Transform/Ridge varies from a transform fault across which the age of the oceanic crust changes producing a step (down to the east) to a ridge resulting from compression following a change in plate motion and a series of seamounts. On the other hand, the earthquake data show that the part of the Tehuantepec Transform/Ridge subducted during the past 5 Ma is a step with no accompanying ridge. Whereas collision of a ridge segment with the trench is inferred to be responsible for the 13–11 Ma deformation in the upper plate, its termination at 11 Ma suggests an along-strike transition to a step. Collision of the Tehuantepec Transform/Ridge also appears to have terminated arc magmatism along the Pacific coast of Chiapas. The similarity between the petroleum-producing, Cantarell structure in the Sonda de Campeche and the buried foldbelt in the Sierra de Chiapas suggests there is considerable further hydrocarbon potential.
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Ancient Orogens and Modern Analogues
Plate tectonics provide a unifying conceptual framework for the understanding of Phanerozoic orogens. More controversially, recent syntheses apply these principles as far back as the Early Archaean. Many ancient orogens are, however, poorly preserved and the processes responsible for them are not well understood. The effects of processes such as delamination, subduction of oceanic and aseismic ridges, overriding of plumes and subduction erosion are rarely identified in ancient orogens, although they have a profound effect on Cenozoic orogens. However, deeply eroded ancient orogens provide insights into the hidden roots of modern orogens. Recent advances in analytical techniques, as well as in fields such as geodynamics, have provided fresh insights into ancient orogenic belts, so that realistic modern analogies can now be applied. This Special Publication offers up-to-date reviews and models for some of the most important orogenic belts developed over the past 2.5 billion years of Earth history.