The Study Of Jiafushaersu Granite In Western Junggar, Xinjiang

The author participated in regional geological survey and granitoids thematic study.On the basis of results of the item, the paper focus on petrology, petrography, magmasequence, isotopic age, geochemistry, tectonic setting and magma evolution of theJiafushaersu intrusion, and I reached the following conclusions:1. The Jiafushaersu intrusion is duplex plutons, which are composed of syenogranite,adamellite, biotite adamellite, porphyritic biotite one and porphyritic granodiorite.Moreover, including dioritic enclaves and microgranular acidic dykes.2. LA-ICP-MS zircon U-Pb dating reveal that the Jiafushaersu intrusion in WestJunggar, is formed303.8±5.1Ma, showing that is emplaced in the Late Carboniferous, thatis similar with the age of post-orogenic magma activity around the West Junggar area.Moreover, High-precision zircon U-Pb dating age, not only acquisition the reliable material,but also enrich the age of granite in the area, most important is taking stronge evdent forrebuilding tectonic framework and recovering magma evolution in West Junggar.3. Petrology and the rock geochemistry reseach indicated, the Jiafushaersu intrusionhave characteristics of high silicon, rich alkali, low aluminum, calcium and magnesium,high differentiation. In SiO₂-AR, A/NK-A/CNK and Na₂O-K₂O plots, the granite havemetaluminous-peraluminous alkali A-type granite features.4. Trace and rare earth element （REE） research indicated, the Jiafushaersu intrusionhave enrich in large ion lithophile elements （LILE, such as Rb and K）, and highfiled-strength elements （HFSE, such as Zr and Hf）, deplete in Eu, Ba, Sr, Nb,chondrite-normalized REE pattern is right-incline “V” type. This belonged to aluminumA-type granite.5. In combination with Sr, Nd, Pb and¹⁸O from this granite in previous work, thisstudy suggest that the intrusion derived from juvenile crust, including oceanic crust andisland arc components, which formed by fractional crystallization of granodioritic magmawhich were produced by partial melting of a depleted mantle which stay some time in thecrust.6. In tectonics environment diagram of Al₂O₃-SiO₂and Rb-Y+Nb, the Jiafushaersuintrusion formed in extension of post-collision setting, not anorogenic granite.