Academic Journals Database
Disseminating quality controlled scientific knowledge

The Lost South Gobi Microcontinent: Protolith Studies of Metamorphic Tectonites and Implications for the Evolution of Continental Crust in Southeastern Mongolia

ADD TO MY LIST
 
Author(s): Joshua P. Taylor | Laura E. Webb | Cari L. Johnson | Matthew J. Heumann

Journal: Geosciences MDPI
ISSN 2076-3263

Volume: 3;
Issue: 3;
Start page: 543;
Date: 2013;
Original page

Keywords: East Gobi Fault Zone | Central Asian Orogenic Belt | South Gobi Microcontinent | Yagan-Onch Hayrhan | Mongolia | Paleozoic | Mesozoic | tectonics | U-Pb geochronology

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.

Tango Jona
Tangokurs Rapperswil-Jona

     Affiliate Program