The Structural Features And Tectonic Evolution Of Dayangshu Basin, NE China

This article depends on the project "The Structural Characteristic, Tectonic Evolution and Basin-forming Dynamics surround Daqing Exploring Region Basins"of China University of Geosciences State Key Laboratory of Geological Processes and Mineral Resources, which is an important tackle key problem project of the labroratory. Dayangshu Basin is one of the basins surround the Daqing exploration area. It locates in the east part of Inner Mongolia and is closely adjacent to Songliao Basin at the southeast. Based on the field geology, geophysical exploration and drilling data, the author used many analysis techniques, such as structure geology, stratigraphy and basin analysis to research the structure modality, distribution features of volcanic rocks and the structure evolution of the primary basin. The main research results are as follows:1. From base to top, the strata of Dayangshu basin are Longjiang formation, Jiufengshan formation, Ganhe formation,which belong to the lower Cretaceous . And Nenjiang formation, and Gushanzhen formation, which belong to the upper Cretaceous. Top of Longjiang formation is medium-acid lava and volcanic clastic rock.Base of it is medium lava with clastic rock beds and thin beds of acid lava. The main rock assembly of the lower part of Jiufengshan formation is medium-felsic lava and volcanic clastic rock, the minor assembly is volcanic sedimentary rock and subvolcanic rock. The upper part of Jiufengshan formation is made of medium-mafic lava, volcanic clastic rock and interbeds of conglomerate, sandstone, mudstone and coal beds. Ganhe formation is mainly made of medium-mafic lava, vocanic sedimentary rock and with clastic sedimentary rock. Gushanzhen formation is made of medium calc-alkalic lava and volcanic clastic rock.2.The Daxing'anling faults belt, which is at the west boundary of Dayangshu basin, affected the evolution and formation of the basin deeply. The deep fault controlled the boundary of the basin, and formed a series of NE oriented normal faults, which fell to the deep depression part of the basin as steps and formed structure configuration that is gentle at west and steep at east, deep at south, shallow at north and rise alternated with depression.3. Daxinganling faults belt controlled the volcanic activity obviously. Activities near the belt are strong, while the ones far away form it changed to be weak gradually. The evolution rules are strong activity changed to weak ones and then changed to strong ones vertically. The early Cretaceous volcanic eruption belt is basically the same with the orientation of the deep fault in the region. All the volcanic facis are controlled by the deep fault ,paleo-topography and volcanic framework .The eruption material became thinner in grade from the volcanic head to the far area.4. The lithofacies of Longjiang formation , Jiufengshan formation , Ganhe formation and Gushanzhen formation are volcanic effluence facies, volcanic explosive facies, volcanic avalanche-deposit facies, volcanic fallout facies, pyroclastic flow facies, volcanic eruption-sedimentary facies, volcanic neck facies, intrusion facies and subvolcanic rock...