The Research On Tectonic Characters And Cenozoic Uplift In Ruoergai Middle Block

The research of Ruoergai middle block (hereinafter with RMB) is subjected to the widespread value in recent years. It has important of academic and application value for researching tectonic history between different blocks in our country and analyzing petroleum exploration in foreland basin.This article has taken a system study on the tectonic characters and Cenozoic uplift in RMB by field observation, indoor cross section making. This article has based on massive sample testing and data collecting, taken quaternary geology, structure geology, lithology and basin analysis as the guardline and applied fission-track analysis. We have analyzed the regional stratum, upbuild tectonic pattern, analyzed the regional tectonic evolutionary process in RMB.Research shows that there are two third level tectonic cells in research area, what are Tangke bulge and Aba-Hongyuan depression; and there are three main fracture belts, what are Maqu-Lueyang fracture belt, Heishui fracture belt and Minjiang fracture belt.Triassic stratum is widely distributed in RMB,mainly is middle-upper Triassic's fragmentary rock. In the area, the fold shape is comparatively broad-tempered, the fracture belts don't developed, and stratum continuity is good. The area is destroyed very little by tectonic movement. The fold cambers in plane which protrudes to the south.Regional tectonic pattern show bigger hiberarchy, which mainly is composed of roof -slippage-fault-fold. The tectonic pattern of shallow hiberarchy which includes middle-upper Triassic's fragmentary rock is fault-propagation and low-angle faults fracture, its roof rock is mainly pelyte. The tectonic pattern of midding-deep hiberarchy which includes upper Paleozoic's carbonatite is possibly thrust and broad-tempered fold. According to stratum and tectonic characters, judging from the time of tectonic movement and anamorphic characters, the fold in the area happened mainly in Indo-Chinese epoch.RMB lies in the eastern edge of the Qinghai-Tibet Plateau and western of Sichuan, Its uplift mostly start from the Indo-Chinese movement of Mesozoic. During the Indo-Chinese movement, the area has mainly experienced decollement; The tectonic event of Himalayanmovement made the area happen strong uplift. From Neopaleozoic-Permian to now, there are five times uplift in the area; From Cenozoic to now the area uplift rate is gradually increasing. Through the analyse of sedimentary combinatorial types and characters of basin tectonic evolution , the contrast between the area and old Sichuan basin, from the non-seismic exploration results show that RMB has the condition for oil and gas storage, and it is the advantageous oil and gas explorating zone in Songpan– Aba.