| The tempestite sedimentary characters are widely apperared in Early Triassic of Northwestern Sichuan area,The breccia limestones,flat-pebble conglomerates,ostracum limestone,hummocky cross-bedding are vermiculately tempestite.Based upon the large amount geological evidence and simulation experiments,on Shangsi,Guangyuan and situated in Dagouli Qingchuan,researchers described the typical Early Triassic main section in Griesbachian area of Early Triassic first member of Feixianguan formation located were observed,described and sampled in detail.The lithological characters and sedimentary structures of the two sections were researched and such measurements as carbon-oxygen isotope,etc.were carried.The following conclusions were drawn:(1)Breccia limestones,flat-pebble conglomerates,ostracum limestones were most developed and the vermiculate limestones,subtidal wrinkle structures and carbonate seafloor fans were locally found in Nothwestern Sichuan area.(2)The flat-pebble conglomerates in First Feixianguan formation is different from the second one on the aspects of sedimentary environments(backgrounds),the same with the microorganism.One is the Autochthonous storm deposit,and another is Far source storm deposits.(3)False mud cracks were observed in Dagouli,Qingchuan,on which presents a dramatic rapid of the weathering rate.At the same time,it has grown into a essential reason expediting the shallow sea system indirectly.With the combination of characters from Sedimentology and Paleobiology,researchers take the wide important consideration on analysing the meaning of geology.After the P-T boundary event,the whole climate in Early Trassic is abnormal,on which showing certain evolution rule of paleoclimate.To sum up in conclusion,the stom acts are connected with large scale gravel-sized grain sedimentation.The corresponding reasons may greenhouse effect,global warming,transformation of paleo-ocean conditions,prevailing monsoon and paleogeography location. |
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