The Lost South Gobi Microcontinent: Protolith Studies of Metamorphic Tectonites and Implications for the Evolution of Continental Crust in Southeastern Mongolia
Open Access
- 21 August 2013
- journal article
- research article
- Published by MDPI AG in Geosciences
- Vol. 3 (3), 543-584
- https://doi.org/10.3390/geosciences3030543
Abstract
The Central Asian Orogenic Belt, or Altaids, is an amalgamation of volcanic arcs and microcontinent blocks that records a complex late Precambrian–Mesozoic accretionary history. Although microcontinents cored by Precambrian basement are proposed to play an integral role in the accretion process, a lack of isotopic data hampers volume estimates of newly produced arc-derived versus old-cratonic crust in southeastern Mongolia. This study investigates metamorphic tectonites in southern Mongolia that have been mapped as Precambrian in age, largely on the basis of their high metamorphic grade and high strain. Here we present results from microstructural analyses and U-Pb zircon geochronology on samples from Tavan Har (44.05° N, 109.55° E) and the Yagan-Onch Hayrhan metamorphic core complex (41.89° N, 104.24° E). Our results show no compelling evidence for Precambrian basement in southeastern Mongolia. Rather, the protoliths to all tectonites examined are Paleozoic–Mesozoic age rocks, formed during Devonian–Carboniferous arc magmatism and subsequent Permian–Triassic orogenesis during collision of the South Mongolia arc with the northern margin of China. These results yield important insights into the Paleozoic accretionary history of southern Mongolia, including the genesis of metamorphic and igneous basement during the Paleozoic, as well as implications for subsequent intracontinental reactivation.Keywords
This publication has 63 references indexed in Scilit:
- Precambrian crystalline basement in southern Mongolia as revealed by SHRIMP zircon datingInternational Journal of Earth Sciences, 2008
- Tectonic models for accretion of the Central Asian Orogenic BeltJournal of the Geological Society, 2007
- Geochemical signature of Paleozoic accretionary complexes of the Central Asian Orogenic Belt in South Mongolia: Constraints on arc environments and crustal growthChemical Geology, 2006
- Accretion leading to collision and the Permian Solonker suture, Inner Mongolia, China: Termination of the central Asian orogenic beltTectonics, 2003
- A new terrane subdivision for Mongolia: implications for the Phanerozoic crustal growth of Central AsiaJournal of Asian Earth Sciences, 2002
- Geochronological evidence for existence of South Mongolian microcontinent—A zircon U-Pb age of grantoid gneisses from the Yagan-Onch Hayrhan metamorphic core complexChinese Science Bulletin, 2001
- Age of Palaeozoic granites and metamorphism in the Tuvino-Mongolian Massif of the Central Asian Mobile Belt: loss of a Precambrian microcontinentPrecambrian Research, 2001
- Geologic Evolution of the Himalayan-Tibetan OrogenAnnual Review of Earth and Planetary Sciences, 2000
- Evolution of the Altaid tectonic collage and Palaeozoic crustal growth in EurasiaNature, 1993
- Formation and evolution of strike‐slip faults, rifts, and basins during the India‐Asia Collision: An experimental approachJournal of Geophysical Research, 1988