TECTONOTHERMAL EVOLUTION OF ORDOS BASIN BY THERMOLUMINESCENCE, NW CHINA

更新时间:2023-08-14

【摘要】Ordos Basin is a remnant cratonic basin undergone multiple tectonothermal cyles, by the comprehensive study of thermoluminescence combined with vitrinite reflectance,magmatism, metamorphism and tectonosedimentation in the basin. Highly geothermal field,strong crustal movement existed in the basin during Archean to Paleoproterozoic. Since Mesoproterozoic, the tectonothermal nature has been relatively stable in Ordos Basin, associating with constant subsidence or uplift sometimes,while heat flow has still been high in the vicinityof the basin with strong activation of graben structural system because of the upwarding mantle creep flow. Two tectonothermal evolution stages and four developing periods can be recongnized in Ordos Basin,i. e. Pre-Mesoproterozoic stage consisting of Archean much higher geothermal geodome period and Paleoproterozoic higher-Reothermal geosyncline period,Mesoproterozolc to present stage including Mesoproterozoic to early Triassic low-geothermal geodepression period and late Triassic to present lowugeothermal uplift-subsidence period. The tectonothermal event at middle Triassic caused the uplift of the basin and the formation of the central paleodome,indicating that the basin entered its residual developing period of the platform. During the residual stable developing period of plat form,the creeping of the mantle increased and the heat flow changed to be high,accompanied by wide spreading eruption of basalt, such as that in Yimeng Uplift area,while the tectonic activity has been quite strong in the surrounding of the basin and the surrounding obviously overthrusted over the basin. Since Triassic, the basin has been gradually uplifted and its tectonism has migrated westward. The tectonothermal event may predicted the breakup of ordos Basin.

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