Palaeozoic palaeogeography of Mexico: constraints from detrital zircon age data
Published:January 01, 2009
R. Damian Nance, J. Duncan Keppie, Brent V. Miller, J. Brendan Murphy, Jaroslav Dostal, 2009. "Palaeozoic palaeogeography of Mexico: constraints from detrital zircon age data", Ancient Orogens and Modern Analogues, J. B. Murphy, J. D. Keppie, A. J. Hynes
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Detrital zircon age populations from Palaeozoic sedimentary and metasedimentary rocks in Mexico support palinspastic linkages to the northwestern margin of Gondwana (Amazonia) during the late Proterozoic–Palaeozoic. Age data from: (1) the latest Cambrian-Pennsylvanian cover of the c. 1 Ga Oaxacan Complex of southern Mexico; (2) the ?Cambro-Ordovician to Triassic Acatlán Complex of southern Mexico's Mixteca terrane; and (3) the ?Silurian Granjeno Schist of northeastern Mexico's Sierra Madre terrane, collectively suggest Precambrian provenances in: (1) the c. 500–650 Ma Brasiliano orogens and c. 600–950 Ma Goias magmatic arc of South America, the Pan-African Maya terrane of the Yucatan Peninsula, and/or the c. 550–600 Ma basement that potentially underlies parts of the Acatlán Complex; (2) the Oaxaquia terrane or other c. 1 Ga basement complexes of the northern Andes; and (3) c. 1.4–3.0 Ga cratonic provinces that most closely match those of Amazonia. Exhumation within the Acatlán Complex of c. 440–480 Ma granitoids prior to the Late Devonian–early Mississippian, and c. 290 Ma granitoids in the early Permian, likely provided additional sources in the Palaeozoic. The detrital age data support the broad correlation of Palaeozoic strata in the Mixteca and Sierra Madre terranes, and suggest that, rather than representing vestiges of Iapetus or earlier oceanic tracts as has previously been proposed, both were deposited along the southern, Gondwanan (Oaxaquia) margin of the Rheic Ocean and were accreted to Laurentia during the assembly of Pangaea in the late Palaeozoic.
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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.