LATE PALEOZOIC TECTONICS ENVIRONMENT AND HYDROCARBON SIGNIFICANCE OF EAST QINLING-DABIE OROGENIC BELT AND ITS BOTH SIDES

On the basis of geochemical analysis for volcanic rocks from East Qinling-Dabie Orogenic Belt and its both sides: Zhuangke of Lüyang County and mid-Atlantic ridge can be classified as the same type of rocks characterized by low ratio of K₂O/SiO₂,high ratio of TiO₂/SiO₂,low value of ΣREE,with flat REE pattern and not enriched LREE,which are between the continental and the oceanic tholeiite.The rock characteristics from Sanchazi of Lüeyang County,Lianghe of Shiquan County and the Japanese island arc are high ratio of K₂O/SiO₂,low ratio of TiO₂/SiO₂,high value of ΣREE and richment of LREE,the REE distribution pattern showed steep right-dip.This paper considers that the environment of West Qinling Mountain(Mianlüe-Animaqing-Soto Lake-Mazha)is the Paleo-Tethys Ocean in the Late Paleozoic,the east area(passed by the Zhenba-Chengkou-Qingfeng-Xiangfan-Zhoujiawan-Guangji)is aulacogen sediments.The south side of Qinling-Dabie Orogenic Belt is mainly in the extended environment affected by Paleo-Tethys Ocean which main hydrocarbon source rocks are Permian carbonate,shale and coal,and enriched gas.While the north side is in a state of intracontinental depression accompanying the uplifting,and the Carboniferous-Permian coal-bearing strata are the main hydrocarbon source rocks,secondary hydrocarbon generation in Late Yanshanian-Himalayan has important significance for oil and gas accumulation.