The Central Asian Orogenic belt, which stretches across southern Mongolia and Northern China, is constructed of volcanic arcs and intervening basins that were generated by the consumption of the Paleo-Asian Ocean. This belt is of interest to the igneous petrology community because of the diversity of its magmatic components and their exhumation during final amalgamation of the northern part of the Asian continent. The age and nature of this structural amalgamation are both matters of significant controversy. R.C. Economos and colleagues investigated the Gobi-Tianshan Intrusive Complex, an igneous complex generated as part of this final closure, via U-Pb geochronology, isotope geochemistry, and detailed field mapping. Geochronology shows the complex to be Early Permian in age, and isotope geochemistry ties it to a far-reaching belt of isotopically unusual plutons with the same age and basic petrological characteristics. We argue that the Gobi-Tianshan Intrusive Complex and these similar plutons were generated in a subduction zone setting in which their isotopes were disrupted by the subduction of sedimentary material. Thus, the study area marks the final subduction in the Central Asian Orogenic Belt and was immediately post-dated by a major shift in tectonic regime.
Drainage and base-level adjustments during evolution of a late Pleistocene piggyback basin, Eastern Cordillera, Central Andes of northwestern Argentina
Gustavo Gonzlez Bonorino and Liliana del Valle Abascal, CONICET-CADIC, UTN-FRRG, B. Houssay 200, Ushuaia, CP9410, Argentina. Posted online 2 October 2012; http://dx.doi.org/10.1130/B30395.1.
Quaternary uplift of an orogenic barrier in the Andean foothills in NW Argentina, South America, partly obstructed eastward flowing streams and gave
|Contact: Kea Giles|
Geological Society of America