Study On Sedimentary Environment And Tectonic Settingin Of Provenace In The Longshan Formation Of Jurassic In West Kunlun Of Gela

The Longshan Formation of Jurassic which Outcrop in ageledaban ditch in the westKunlun of Gela is the only marine of Jurassic stratigraphic record which is stored inthe south side of Maza-Cangxiwa tectonic melange belt, It is a good carrier of theJurassic sedimentary environment and tectonic evolution processes.the previousstudies on the sedimentary environment had briefly, but did not establish thesedimentary model, has not carried on research on provenance and tectonicbackground of the source area.study the sedimentary environment, material sourcesand tectonic background of Longshan formation in the south of Mazar-Kangxiwarsuture zone, Restoration of the structure and sedimentary evolution of the jurassic.Studies on petrology, sedimentology show Longsha n formation Mainly for thecarbonate rocks intercalated with clastic rocks, partially with gypsum and lenticulargravel stratum, through comprehensive research of sedimentary facies andsedimentary sequence revealed the Longshan formation of barrier island of tidal flatand lagoon, can further distinguish the mud flat, sand flat, mixed flat, limemud flat,dolomitic flat, tidal channel, lagoon and other sedimentary units, Study on thecharacteristics of sedimentary sequence display Longshan formation sedimentaryevolution can be divided into five series, Corresponding to different sea-levelchanges,From the south to the north, showing the distribution characteristics from seato land transition, indicating the source direction from north to east.Application of Dickson graphical method, the results show that the detrital materialderived from the recycled orogenic belt, with the collision suture and fold-thrust beltproperties. geochemical indicate the material sources were mainly from the passivecontinental margin, continental island arc, as active continental margin, with a mixtureof source characteristics.Comprehensive provenance tectonic background analysis results, combined withregional geological features, that the Jurassic Longshan formation source comes fromthe north of the Mazar-Kangxiwar suture zone,stratigraphic correlation suture zoneon both sides of the same time, shows that the area of Early-Middle Jurassic in upliftorogenic evolution stage, began a transformation from sea to land,sedime ntary fillingsequences developed in the foreland basin in the south is the sedimentary records of Gutisi ocean subduction orogeny and Qiangtang block and Tarim block collided.