Tectonic Dynamothermal Transition Of The Meso-Cenozoic And Its Constraints On Coupled Metallogeneses In The Northeast Ordos Basin

Northeastern Ordos basin (NOB) experienced obviously differential uplift in Meso-Cenozic, and co-exist enrichment of multi-energy resources of oil-gas, sandstone-type uranium and coal deposits, etc. Recently, there has been an outstanding issue on the space-time scale of the tectonic dynamothermal transition and its effects on coupling mineralization and oil-gas accumulation in NOB. Based on the study of regional geological structure and thermochronology, this paper systematically establishes chronology sequence of tectonic events in Meso-Cenozic and the characteristics of tectonic dynamothermal transition in different part of NOB, then analysis the relationship between the tectonic dynamothermal transition and coupling mineralization and oil-gas accumulation. The main conclusions are as follows.By means of field geological survey of structural section and geophysical data, this paper reveals the edge fault system in NOB. The result shows that Lishi strike-slip fault belt is composed of Lishi fracture and Wubu-Fugu fracture which is the significant boundary of eastern Ordos. Shihalagou-Machanghao reverse fault which belongs to Yinshan-Daqingshan piedmont fault made the boundary of northern Ordos.Based on the fission track analysis and isotope chronology, established the peak age of tectonic chronology sequence in Meso-Cenozoic of NOB. The results show:the main tectonic heat event of the study aera occurred in 135Ma± in Yanshanian cycle, The differential uplift and denude occurred in 65Ma± and 20Ma± since the Late Yanshanian movement, the latter makes up for the missing geochronology records about 100Ma since Late Cretaceous.By the study on thermal-chronological dating, it clears the timing relationships about difference uplift in different structural units of NOB since Late Mesozoic difference. The results show that the uplift in the north was earlier(118-103Ma) than south(44-32Ma) and the east(79-32Ma) edge uplifted earlier than the inner-basin(18-17Ma). What's more, eastern Ordos basin area mainly experienced two stages tectonic events of roughly 78-66Ma and 62-32Ma in Cenozoic, and the tectonic uplift main occurred in 18-17Ma in depression area of ordos.Studies on the relationship between the tectonic dynamothermal transition mineralization and coupling mineralization show that tectonothermal event in middle stage of Yanshanian cycle(peak age is 135Ma±) which is coupling warming events of sedimentary buried and magmatic activity, make the main hydrocarbon source rock of Paleozoic to large-scale generate hydrocarbon and Jurassic sandstone-type uranium ore deposits. Differential uplifting event of late Yanshanian to early Himalayan period, especially two differential uplift events with the peak age of 65Ma± and 20Ma± when yield primary hydrocarbon accumulations to adjust and dissipate, coal and sandstone-type uranium deposits.