Research On The Uplift And Denudation Process Since The Late Cretaceous In Huanan Area,East Of Heilongjiang Province,China

Huanan uplift is located in the east of Heilongjiang Province,between the Yishu Fault and the Dunmi fault,at the front edge of the subduction of the Pacific plate towards the Eurasian plate,which is affected by the movement of the northern part of the Tanlu fault zone and the Pacific plate.The uplift of Huanan uplift is in response to the subduction of the Pacific plate,which directly led to the destruction of the Dashanjiang basin,forming the Mesozoic-Cenozoic basin group widely distributed in the east of Heilongjiang Province.Therefore,Huanan uplift is one of the best locations to study the subduction of the Pacific plate.In this paper,the uplift and exhumation process of Huanan uplift is comprehensively analyzed by means of structural geomorphology analysis,apatite fission track dating and thermal evolution history simulation.Based on fission track dating and apatite thermal history simulation,it is found that there are two stages of uplift and one stage of subsidence in Huanan uplift since the late Cretaceous.Uplift from the Late Cretaceous to the mid-Eocene,of which 75~60 Ma was a period of rapid uplift;From mid-Eocene to mid-Miocene subsidence,23.5~15Ma is the period of rapid subsidence;Uplift from the middle Miocene to the present,of which a rapid uplift period has occurred since 5Ma.Based on digital elevation model(DEM),this paper uses ArcGIS to extract four geomorphic indexes: slope,relief,HI and geomorphic information entropy.Combined with the trend of landform elevation,it is recognized that the landform of Huanan uplift is the result of the Quaternary right-hand transformation after the left-hand uplift and denudation since 15 Ma.The landform is generally in the old age,but there are differences in space.The evolution of the three local drainage basins in Huanan uplift area is in the middle age,among which the south area of Shuangyashan is the largest,the north area of Qitaihe river is the second,and the west area of Baoqing is relatively small.Combined with the research results of geomorphology and thermochronology,there are temporal and spatial differences in exhumation and burial in the middle period of Late Cretaceous Miocene in Huanan uplift area.The uplift in the middle period of Late Cretaceous Miocene migrated from east to west,and the subsidence in the middle period of Eocene Miocene expanded from east to West.The uplift since Miocene has little overall difference.Combined with the regional tectonic background,the dynamic mechanism of rapid uplift in the Huanan uplift area was combed out,and it was concluded that the uplift during the period of 75~40Ma May be caused by the continental collision between the Eurasian plate and the subduction of the Indian plate to the north.The subsidence process during 40~23.5Ma may be caused by the dextral strike slip of the Tanlu fault zone and the movement of the Pacific plate.The subsidence process during 23.5~15 Ma May be caused by the sinistral strike slip of the Tanlu fault zone.The uplift to date of 15 Ma May have been caused by the accelerated movement of the Pacific plate and the westward thrust generated by the strong expansion of the trough.