闽西南华安正长花岗岩同位素测年及地球化学特征

Isotope Dating and Geochemical Features of the Huaan Syengranite in the Fujian Southwestern

闽西南华安正长花岗岩通过1∶5万永福镇、华安县、高安圩、新圩、利水5幅区域地质调查,运用LA-ICP-MS锆石U-Pb测年,取得岩体西南端锆石U-Pb年龄为(143.97±0.45)Ma(MSWD为0.87)和(145.21±0.52)Ma(MSWD为0.34),东北端锆石U-Pb年龄为(140.8±2.6)Ma(MSWD为2.1),显示了华安正长花岗岩侵入年代为晚侏罗世。地球化学特征显示华安正长花岗岩岩浆源来自大陆地壳,形成于同碰撞环境,属铝过饱和S型花岗岩。

Huaan Syengranite is located in Southwestern Fujian,Theare is nobody research on the magmatism and the forming age of granite.The LA-ICP-MS U-Pb dating of the zircons from the Mesozoic Syengranite are carried out.The results show that the U-Pb dating of the tow porphyritic medium grain granite in the south-west of Granite is（143.97±0.45） Ma（MSWD=0.87）and（145.21±0.52）Ma（MSWD=0.34）respectively.The U-Pb dating of the porphyritic medium granite in the south-east of Granite is（140.8±2.6）Ma（MSWD=2.1）.Moreover,the data of petrochemistry show that Syengranite own high silicon,high alkali（K〉Na）,high Rb/Sr and Rb/Nb value,with low magnesium,low nickl and chromium value.The REE distribution patterns of the Syengranite appear as rightly-oblique and Eu strong losses.It is suggest that the Syengranite were formed in the collision-extrusion tectonic environment and were of strong magmatic differentiation and high magma acidity,It is belong to aluminum supersaturation S-type granites.