Geological,Geochemical Characteristics of Hongshan Pluton:Constraint for Lower Crust of West Junggar,Xinjiang
Jiang Yun
Xiao Long
Zhou Pei
Wang Guocan
Abstract：The basement of Junggar basin has been disputed for years,the geochemical characteristics of the granites are indica-tive of the lower crust,our research shows that,the Hongshan alkali feldspar granites from the West Junggar region, Xingjiang,are characterized by high SiO 2 ,low Al2 O 3 ,high total alkali,metalumious,and LREE along with significant nega-tive Eu anomalies,enrichment of large ion lithophile elements (such as Th,Rb and K)and high field-strength elements (such as Zr and Hf),strong depletion of Sr,Ba,P and Ti,showing geochemical features reminiscent of A-type granites.It can fur-ther infer that it was formed in post-collisional extensional environment.Zircon U-Pb dating by SIMS and LA-ICP-MS yield ages of 31 5.7±2.4 Ma and 31 7.8±3.8 Ma,suggesting that the pluton was emplaced at early Late Carboniferous,which is con-temporary with the timing of the Late Paleozoic post-collisional magmatism in the region.Mineral thermometry implies that the pluton formed at a temperature from 680 to 860 ℃.On the other hand,zircon Lu-Hf and Sr-Nd isotopic features show a deple-ted mantle-like signature,suggesting that the magma was sourced from juvenile crust.
Keywords：A-type graniteLate Carboniferouspost-collisionlower crustHongshan plutonWest Junggargeochemistry
Publication Date：2015-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：19( 1129-1147 )