Tectonic background and hydrocarbon accumulation of carboniferous volcanic in Santanghu basin

The magmatic origin and evolvement of volcanic rock are controlled by its geodynamic background.Volcanic rock in different tectonic environment forms different geochemical characteristics.The study such as chemical constituents,trace element abundances and REE pattern of Carboniferous volcanics in Santanghu basin and analysis of tectonic evolvement show that the Carboniferous volcanics was formed in continental margin setting generally.Tectonic background has slightly difference in different stages,among them,volcanic rock of C2h is mainly on within-plate setting,and C2k is mainly on volcanic island arc setting.Mafic-intermediate volcanic rocks that formed in the setting are abundant in plagioclase and zeolite amygdale,which are apt to be weathering and leaching and form the high-quality reservoir,and weathered crust reservoir with lower generation and upper accumulation and inner formation volcanic reservoir with self generation and self accumulation formed in oil-source control range.