The Preliminary Study Of Volcanics In Wushitala,Heshuo Country,Sinkiang,China

Study area is located in the south eastern Tianshan, volcanic rocks can be divided intotwo part according to the volcanic formation of volcanic rock era, named the late Silurianvolcanic rocks and Devonian volcanic rocks. Both sets of volcanic rocks formed in differenttectonic environments, with different combinations of rocks and geochemical characteristics.Based on previous studies and detailed geological survey of the field of volcanic rocks of thestudy area were merged and divided, and through the study of two volcanic rocks, mineralogycharacteristics, geochemical characteristics and other aspects discussed its causes, sourcecharacteristics and tectonic environment and other issues.Silurian volcanic located in the eastern melange belt of Baitutang, The main lithologiesis metamorphosed basalt. Its characterized with rich MgO, poor K2O and Na2O. according totheir characteristics can be divided into three categories, the first two categories from thedepleted mantle, as MORB-type rocks; latter category performance-both N-MORB-type andE-MORB-type rock characteristics. According to the existing northern edge of the southernTianshan ophiolite data we suggest that, According to the northern margin of the SouthTianshan ophiolite existing research data we suggest that: the South Tianshan ocean hasstarted northward subduction at least from the late Silurian. Combined with regional tectonicevolution, the emergence of the Late Carboniferous-Early Permian granite cut melange beltwithout any obvious distortion, we suggest that the tectonic melange formed in the EarlyCarboniferous late-late Carboniferous medium term.Late Devonian volcanic rock located in the southeast corner of Baitutang, in Pochengzigroup (D3p) first rock section and the second rock section. mainly lithology is dacite, mostlybelonging to K calc-alkaline volcanic rocks, a small part belonging to potassium calc-alkalinevolcanic rocks. High Al2O3content and large range of variation K2O content. LREEenrichment, HREE enrichment of LILE, loss HFSE, obviously loss Nb, Ta, its geochemicalcharacteristics similar to island arc volcanic rocks, and tectonic environment of theAndean-type continental edge of the arc. Crustal evolution of the southern Tianshan combinethe study area and the early Early Carboniferous sedimentary Gancaohu group (C1g)deposition, paleontological features, that in the Late Devonian, south eastern Tianshan region into the residual basin evolution stage, there has residual basin exist between the plate of northErie and southern Tianshan Tarim Plate basin, accompanied by volcanic activity formed thelate Devonian volcanic rocks.