Occurrence, age, and implications of the Yagan-Onch Hayrhan metamorphic core complex, southern Mongolia

Mylonitic rocks associated with the south-dipping detachment fault of the Yagan-Onch Hayrhan metamorphic core complex in southernmost Mongolia indicate subhorizontal south-southeast-directed extension in the Early Cretaceous; synkinematic biotites give 40Ar/39Ar ages of 129 to 126 Ma. The Yagan-Onch...

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Bibliographic Details
Published in:Geology (Boulder) 1999-02, Vol.27 (2), p.143-146
Main Authors: Webb, L E, Graham, S A, Johnson, C L, Badarch, G, Hendrix, M S
Format: Article
Language:English
Online Access:Get full text
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Summary:Mylonitic rocks associated with the south-dipping detachment fault of the Yagan-Onch Hayrhan metamorphic core complex in southernmost Mongolia indicate subhorizontal south-southeast-directed extension in the Early Cretaceous; synkinematic biotites give 40Ar/39Ar ages of 129 to 126 Ma. The Yagan-Onch Hayrhan core complex demonstrates that late Mesozoic localized high-strain extension, recently recognized in other parts of eastern Asia, also occurred in Mongolia. The presence of Mesozoic metamorphism at Onch Hayrhan, previously presumed to be Precambrian, brings into question the existence of the South Gobi microcontinent.
ISSN:0091-7613
DOI:10.1130/0091-7613(1999)0272.3.CO;2