Sequence Stratigraphy Of The Triassic And Its Tectonic Settings In Geotong Area, Yunnan Province

Gejiu area of yunnan province is located in located in the southern margin of the youjiang basin of south China block (or the nanpanjiang river basin, dianqiangui basin) of the southwest corner, and is famous for production of tin ore at home and abroad. Area is located in the south of yunnan gejiu, predecessors to the area of geological mapping and mineral exploration, but the stratigraphic sequence characteristics of the research is generally weak, so based on the sequence stratigraphy and orogen stratigraphy, lithofacies paleogeography, such as plate tectonics theory as the instruction, on the basis of predecessors’research, combining our main profile with regional tectonic background and establish an old district Triassic sequence stratigraphic framework, find out the sequence of sedimentary facies and sedimentary system characteristics, analysis of gejiu area Triassic nanpanjiang basin evolution The most workspace stratigraphic contact relationship clear, involved in the Triassic stratigraphic section includes three field profile with three former our profile, including lower xianmatang group (T1x) and jialinjiang group (T1j), middle gejiu group (T2g) and falang group (T2f), under the banan group (T3b) and huobachong group (T3h). It now consists of 3 second-order sequence, specific divided into 7 third-order sequences, composed of 2 Lowstand system tract (LST), the 6 Transgression system tract (TST) and the 7 Highstand system tract (HST), The most Sequence boundary are interface conversion surface facies and volcano events sedimentary, including neritic shelf depositional system, carbonate platform depositional system and shoreline sedimentary system. Combined with analysis of sedimentary environment and integration of Triassic strata of the phase of the previous research data, can be found in Youjiang basin is a product of the Indosinian movement, by the Paleo Tethys tectonic composite basin and circum Pacific tectonic evolution process, experience started by Shiru Ki in the late stage of intracontinental rift basin of passive margin rift basin, back arc rift basin, foreland basin stage filling die, filling the shallow water phase to continue to die and finally receive the terrigenous sediments.