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Multistage Extension and Age Dating of the Xiaoqinling Metamorphic Core Complex, Central China
Author(s) -
Jinjiang ZHANG,
Yadong ZHENG
Publication year - 1999
Publication title -
acta geologica sinica ‐ english edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.444
H-Index - 61
eISSN - 1755-6724
pISSN - 1000-9515
DOI - 10.1111/j.1755-6724.1999.tb00821.x
Subject(s) - metamorphic core complex , extensional definition , geology , seismology , metamorphic rock , normal fault , detachment fault , echelon formation , extension (predicate logic) , shear zone , shear (geology) , fault (geology) , china , core (optical fiber) , geochemistry , petrology , archaeology , geography , tectonics , computer science , programming language , materials science , composite material
There are two extensional systems in the Xiaoqinling metamorphic core complex (XMCC). One is the detachment fault system developed along the peripheries of the XMCC, which extended in an ESE‐WNW direction and whose upper plate moved towards the WNW. The other extensional system includes the retrograde shear zones and normal faults developed within the XMCC, which represent the collapse of the XMCC. Ar‐Ar and K‐Ar dating shows that the extension of the detachment fault system continued from 135 to 123 Ma, i.e. in the late stage of its evolution at about 127 Ma. The collapse represented by the extensional system within the XMCC was operative during 120–106 Ma, and its main activity occurred about 116 Ma ago. These suggest that the XMCC experienced two extensional stages in its evolution, i.e., the syn‐orogenic regional extension and post‐orogenic collapse extension.