Sedimentary Environment And Basin Study In Triassic Of Luohuo Sichuan Province

Luhuo the eastern edge lies in the Qinghai-Tibet Plateau,located in Longmenshan -Jinping Shah tectonic belt west,combined with south Ani Ma Qing,Ganzi-north of Litang combined with the triangle,Xianshuihe fault Tilt through the Southwest of the work area;The study area in the Mesoproterozoic—Neoproterozoic Era,Through the formation of the basement,the mainland edge of the deposition hyperplasia,in particular the Late Permian after cracking-closure-the collision-uplifting lengthy and complicated process of evolution.It's evolution not only was Controlled by the Ganzi-Litang combination of belt and the north combined with the A ni Ma Qing formation and evolution,At the same time be restricted by the Longmenshan-Jin Pingshan structural zone and The Luhuo-Daofu structural zone evolution Constraints., whom east of the work area.In the Middle of the Permian period,the crust began rift,On the regional formed on the San dao-qiao formation Slumping Deposition conglomerate,and the underlying strata of cracking unconformity marks the formation of the rift basin age Threshold. With the continuing role of the Rift Valley,has formed marine rift sedimentary rocks of Da shi-bao formation.From bottom to top,sedimentary environment became deep, appear as a transgression sedimentary sequence.One the region,the San dao-qiao formation Slumping Deposition conglomerate and marine rift sedimentary rocks of Da shi-bao formation for the rift basin development provides an important basis.During this period,Luhuo-Daofu area may also rift.Under the control of this Ancient tectonic framework and Ancient geographical outlook,The beginning of the Triassic stratum of sedimentary;Late Permian-Early Triassic,the study area one-third of the initial pattern formed, The two sides of the Jinchuan stratigraphic microprovince and Yajiang stratigraphic microprovince began to passive margin flysch basin evolution and the Central of the study area- Luhuo- Daofu stratigraphic microprovince of the Rift Valley Stretching further To develop in the direction of the initial ocean basin.At this piont,The research area mainly grows the inferior deep sea-deep sea sand-mudstone facies in Bo ci-gou Formation,for the rift basin develops the mid and late stage,the water body formed by deepening;reflects the period for Rift Valley-the deep sea Sedimentary basin in nature.From the Mid of the Triassic La-ding period to Late Triassic Ka-ni period,The Ru nian-ge rock group,in Luhuo-Daofu belt,Start to deposition,Marked the formal formation of the one-third pattern of sedimentary basins in the study area.Northwest side of the Jinchuan stratigraphic microprovince for passive margin basin;south east of the Yajiang stratigraphic microprovince for deep-sea basin,and Luhuo-Daofu District is the initial ocean basin;Passive continental margin Basin of The Jinchuan stratigraphic microprovince, Main growth Contour current facies and turbidity sand-mudstone facies;Contour current facies Main growth in Zha ga-shan formation;turbidite fan phase can be broken down into the up-turbidite fan,Mid-turbidite fan And the down-turbidity fan; up-turbidity fan in the major development in the Za gu-nao Formation;Mid-turbidite fan in the main program developed in the Zhu wo Formation;and down-turbidite fan in the main program developed in the Xin du-qiao Formation;At this point,the Jinchuan stratigraphic microprovince was inferior deep sea-deep-sea facies and the slopes of the deep sea-deep-sea basin facies Combination.At the same time,even tablets sequence can be seen graded bedding,parallel bedding and ripple bedding,which represent typical storm deposits.His deposition phase sequence from the bottom to top:the slope -deep-sea basin facies→slopes facies→Inferior deep sea facies;the phase sequence reflect the Jinchuan stratigraphic microprovince in the Triassic period of the Mesozoic tectonic evolution pattern and sedimentary environment;Mid-Late Triassic,Although the Rift Valley Still further expansion,The stratigraphic microprovince is the margin for the performance of the properties;And formed a formation to Za gu-nao,zhu wo formation,Xin du-qiao formation as the representative of the slopes-deep-sea basin turbidite fan and contour current deposits of Zha ga-shan formation.Yajiang microprovince in addition to growth turbidity deposition facies and contour current facies,also growth inferior deep-sea basin-the slope of the flysch facies, shallow continental shelf facies.This microprovince turbidites Deposition similar phase and Jinchuan microprovince,mainly growthed in the Za gu-nao formation and Zhu wo formation,Inferior deep-sea basin-the slope of the flysch facies mainly growthed in Liang he-kou formation and contour current facies growth in xin du-qiao formation and shallow continental shelf facies mainly growth in Yajiang formation; Deposition of the combination of the region was the deep-sea phase,the inferio deep-sea basin-and the shallow continental shelf facies,Facies sequence from the bottom:deep-sea facies→inferio deep-sea facies→shallow continental shelf facies, the facies sequence to reflect the Yajiang microprovince in the Late Triassic Ka-ni period consistent with the Jinchuan microprovince,as well as The passive margin sea, only deep-water more than Jinchuan;Late Triassic Nuo li period,with the closure of the Rift Valley,and local groups in the Xikang orogenic activities,Basin properties becames to the residue-shrinking Basin,continue to accept deposits;at a time,when the Jinchuan microprovince have started a orogeny,into the land.Luhuo-daofu microprovince between the Yajiang microprovince and Jinchuan microprovince mainly growth deep ocean basins facies and shallow continental shelf facies.The ocean basin formed after the Rift Valley stretching to oceanic crust, Growthed in the stratum of the deposition-hybrid structure(such as in the Ru nian-ge rock group),the initial formation of ocean basins,and shallow continental shelf facies deposited after the closure of the Rift Valley,growth in Liang he-kou formation,a residue-shrinking Basin.With its deposition of the combination of deep-sea facies and shallow continental shelf facies.Deposition facies sequence from the bottom:the deep-sea facies→shallow water facies,which reflects this process that the microprovince through the Rift Valley further tension in Late Permian Period,thus forming the initial ocean basin,and along with the Rift Valley with the closure of shallow sea water and sediments the material of the shallow water facies.At the same time,reflects the process,which the tectonic evolution stage also chaged from extension to squeeze.Observation from the entire of the work area,each microprovince is not isolated, they belong to the Ba yan-kala Ocean,but the specific environment of small difference, in their sources of supply,Deposition facies and deposition facies sequence,process of the structural evolution,and other aspects of A certain similarity and comparability.