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The Dabie UHP unit, Central China: a Cretaceous extensional allochthon superposed on a Triassic orogen
Author(s) -
Hong Wang,
Franz Neubauer,
Genser,
Kan Yang
Publication year - 1998
Publication title -
terra nova
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.353
H-Index - 89
eISSN - 1365-3121
pISSN - 0954-4879
DOI - 10.1046/j.1365-3121.1998.00200.x
Subject(s) - geology , allochthon , cretaceous , metamorphic rock , shear zone , tectonics , petrology , nappe , shearing (physics) , metamorphic core complex , shear (geology) , extensional definition , extensional tectonics , seismology , geochemistry , paleontology , geotechnical engineering
Petrological, geochronological and structural data show that the eastern Dabie metamorphic complex resulted from two orogenic stages. Precursor rocks of the ultrahigh‐pressure (UHP) and high‐pressure (HP) units in the present hanging wall tectonic position were buried, penetratively deformed and subsequently exhumed by distributed, ESE‐directed shearing during Triassic time. In contrast, rocks of the Dabie orthogneiss domes, now in a footwall tectonic position, were penetratively deformed during temperature‐dominated, Early Cretaceous tectonic events, that are likely related to magmatic underplating. The Dabie orthogneiss domes and the UHP/HP units were juxtaposed during Early Cretaceous exhumation of Dabie orthogneiss domes by the formation of an ESE‐directed low‐angle ductile normal shear zone. Consequently, the UHP/HP units now represent an extensional allochthon in the hanging wall of the younger normal shear zone. The Cretaceous extensional structures are limited by boundary strike‐slip faults. Consistent with the South China regional tectonic framework, ESE‐directed lateral extrusion is considered to be the driving mechanism for extension and the present‐day structure of the Dabie metamorphic complex.