Petrotectonic Of Huangling Granite Batholith, Western Hubei

Huangling granite batholith ,along with Hannan and Liyuzai granite batholith,constructs a low-K granite belt in the northern periphery of Yangtze Platform.It was formed during the orogenetic process of "Qinling Ocean" subduction toward southern Yangtze Plate in the late Proterozoic(833Ma~770Ma).It is disintegrated into 4 suites, comprising 15 units, and the invading sequence successively is Sand-ouping quartz tonalite suites and Huanglingmiao trondjiemite-light-colored granodolerite suites of pre-plate collision, Dalaoling monzonite granite suites of post-plate collsion uplift, Xiaofeng quartz monzonite dior-itic porphyrite suites of late-orogenic and A-type granite of post- orogenic.Geochemistry characteristics shows that Huangling granite batholith belongs to calc-alkalic series I-type granite and A- ype granite association. Sandouping suites and Huanglingmiao suites are comagmatic evolution series. Nd and Sr Isotope geochemical data indicates that Huangling granite batholith had different source rock. Sandouping and Huanglingmiao suites were formed by magma of Late Archeozic Kongling" group. Daoling and Xiaofeng suits are probably derived from mafic or H-K calc-alkalic igenous rock slightly youger than the former. Study on mafic microgranular enclave and its host rock of Huangling granite batholith reveals that they were magma crystallized products .It is symbol of magma mixing.Sandouping and Huanglingmiao suites are syntectonic granitonic emplaced at the ductile domain about 16 km deep under the action of SN-strikingregional compression. Dalaoling and Xiaofeng suites are late-tectonic granitoids emplaced at the brittle domain formed during rapid uplift and stretche of the crust.Emplacement ages of Huangling granite batholith are between 833 and 770 Ma. And caused by the subduction occurred beneath northern Yangtze plate during late Proterozoic. Xiaofeng dyke and A-type granite make up of the indicative breaking-up events along the northern margin of Yangtze plate. The forming of Huangling granite batholith probably represents concretion of united block along Yangtze Platefrom in Neoproterozoic, stretching and rifting of the united block in 800Ma.