Abstract:

The Early Proterozoic volcanic rocks of the Liaodong area are the important part of composition of Lower Proterozoic Liaohe Group. They are composed of two suites of the acid and basic volcanic rocks. It is suggested that the former should have been formed during the early-tensile depressing stage of the Liaohe rift development, which belongs to the melted crustal magma; the latter should have been formed during the mid-late intensive depressing stage of the Liaohe rift, which belongs to mantle-derived magma. This paper deals mainly with the characteristics of the petrology, mineralogy, petrochemistry and geochemistry for the basic volcanics. The above result has indicated that these volcanic rocks are mainly a suite of eruptive pillow basic lava from the sea-floor, which have the characteristics of the continental and oceanic tholeiites and belong to the evolutionary products of the Liaohe rift from continental crust to oceanic crust. It is thought that the dynamic background of the formation for volcanic rocks is closely related to the occurrence of the hot-mantle convection and the translational activity of the right-lateral shear of the Tan-Lu fault zone during the Early Proterozoic Era.

Key words: the Liaohe Group, basic volcanic rock, dynamic background, Early Proterozoic, the Liaodong area