TY - JOUR
T1 - Rapid exhumation and cooling of the Liaonan metamorphic core complex
T2 - Inferences from 40Ar/39Ar thermochronology and implications for Late Mesozoic extension in the eastern North China Craton
AU - Yang, Jin Hui
AU - Wu, Fu Yuan
AU - Chung, Sun Lin
AU - Lo, Ching Hua
AU - Wilde, Simon A.
AU - Davis, Gregory A.
PY - 2007/11
Y1 - 2007/11
N2 - The Liaonan metamorphic core complex formed during crustal extension in the Liaodong Peninsula, eastern North China craton, and consists of the Jinzhou detachment fault, Proterozoic-Paleozoic sedimentary rocks in its upper plate, and exhumed high-grade Archean metamorphic rocks and Early Cretaceous granitic plutons in the lower plate. Exhumation of its footwall from mid-crustal levels is evidenced in the detachment fault zone by the temporal transition from amphibolite facies mylonitization at depth, through retrograde chloritic shearing and brecciation, to brittle faulting during final uplift. The footwall mylonite zone is 2.5-3.5 km thick and includes Early Cretaceous (128-118 Ma) granitic rocks, together with older metamorphic rocks. The 40Ar/39Ar ages of muscovite, hornblende, biotite, and K-feldspar from the mylonitic rocks record that the core complex cooled between ca. 120 and 107 Ma, from the time of initial crystallization of zircons (122-118 Ma) at 700-800 °C in syntectonic leucocratic dikes and granitic rocks, to closure of argon diffusion in hornblende, micas, and K-feldspar at ∼500 to ∼200 °C. Throughout the eastern North China craton, the synchroneity of cooling and exhumation of metamorphic core complexes, the formation of pull-apart basins, and regional alkaline igneous activity, reflects regional extensional tectonics in the Early Cretaceous. This accompanied lithospheric thinning, possibly resulting from the rollback of the subducted Pacific plate along the eastern Asian margin during the Early Cretaceous.
AB - The Liaonan metamorphic core complex formed during crustal extension in the Liaodong Peninsula, eastern North China craton, and consists of the Jinzhou detachment fault, Proterozoic-Paleozoic sedimentary rocks in its upper plate, and exhumed high-grade Archean metamorphic rocks and Early Cretaceous granitic plutons in the lower plate. Exhumation of its footwall from mid-crustal levels is evidenced in the detachment fault zone by the temporal transition from amphibolite facies mylonitization at depth, through retrograde chloritic shearing and brecciation, to brittle faulting during final uplift. The footwall mylonite zone is 2.5-3.5 km thick and includes Early Cretaceous (128-118 Ma) granitic rocks, together with older metamorphic rocks. The 40Ar/39Ar ages of muscovite, hornblende, biotite, and K-feldspar from the mylonitic rocks record that the core complex cooled between ca. 120 and 107 Ma, from the time of initial crystallization of zircons (122-118 Ma) at 700-800 °C in syntectonic leucocratic dikes and granitic rocks, to closure of argon diffusion in hornblende, micas, and K-feldspar at ∼500 to ∼200 °C. Throughout the eastern North China craton, the synchroneity of cooling and exhumation of metamorphic core complexes, the formation of pull-apart basins, and regional alkaline igneous activity, reflects regional extensional tectonics in the Early Cretaceous. This accompanied lithospheric thinning, possibly resulting from the rollback of the subducted Pacific plate along the eastern Asian margin during the Early Cretaceous.
KW - Argon thermochronology
KW - Crustal extension
KW - Early Cretaceous
KW - Liaodong Peninsula
KW - Liaonan metamorphic core complex
KW - Metamorphic core complex
KW - North China Craton
UR - http://www.scopus.com/inward/record.url?scp=38149000802&partnerID=8YFLogxK
U2 - 10.1130/B26085.1
DO - 10.1130/B26085.1
M3 - Article
AN - SCOPUS:38149000802
VL - 119
SP - 1405
EP - 1414
JO - Bulletin of the Geological Society of America
JF - Bulletin of the Geological Society of America
SN - 0016-7606
IS - 11-12
ER -