Petrogenesis Mineralization and Tectonic Implications of Paleoproterozoic Potassic-Ultrapotassic Magmatic Rocks in Western Yunnan
The Paleoproterozoic potassic-ultrapotassic magmatic rocks are widely developed in western Yunnan,forming an alkali-rich magmatic rock belt along the Jinshajiang-Ailaoshan fracture zone.Due to the lack of systematic research on these potassic-ultrapotassic magmatic rocks,there are still many debates on the petrogenesis and their relationship with mineralization.In this paper,through the collection of published whole-rock major and trace element,Sr-Nd isotope,zircon Hf isotope and geochronology data of the whole rock in the alkali-rich magmatic belt,the rock belt is divided into three parts,namely,south,central and north rock belts according to the tectonic position.Through systematic comparative analysis,it is concluded that the diagenetic age of Paleoproterozoic potassic-ultrapotassic rock formation in western Yunnan is basically the same,with a peak value of 35 Ma,which is the product of the same period of tectonic thermal events.The basic-ultramafic and intermediate-acid rocks have different genesis.The former enriched in LILEs,deficit HFSEs,high(87Sr/86Sr)i,and low εNd(t)values,probably originating from a slab-accounted enriched lithospheric mantle.The latter may be the product of crust-mantle mixing due to its higher SiO2 content.The formation of both is related to the shear slip and tensile action of the Jinshajiang-Ailaoshan fault,which is the product of partial melting of the lithosphere at different depths under the same tectonic thermal event.The potassic-ultrapotassic rocks of the southern and central rock belts are closely related to porphyry Au-(Cu-Mo)deposits.The magmatic formation process may provide favorable conditions for mineralization with high oxygen fugacity and water content,as well as ore-forming materials and ore-forming fluids.
western Yunnanpotassic-ultrapotassic magmatic rockspetrogenesismineralizationJunior lower crustCenozoic
NETL
NSTL
万方数据
维普
