塔里木东北缘库鲁克塔格地块西段新元古代花岗闪长岩成因及其地质意义

The Kuruktag Block is located on the northeastern margin of the Tarim Craton, where a large number of Neoproterozoic magmatic rocks are developed. To further clarify the genesis of these magmatic rocks and explore the regional geological evolution process, this paper conducts petrographic, chronological and geochemical studies on the Kauliulke granodiorite in the western part of the Kuruktag Block. The results show that the granodiorite was formed in the early Neoproterozoic (823 - 810 Ma) and belongs to the metaluminous - peraluminous I - type granitoids. It exhibits petro - geochemical characteristics of high silicon, sodium and aluminum, and low calcium, iron and potassium. Its Sr content is high (1690×10⁻⁶ - 2060×10⁻⁶), Y content is low (7.5×10⁻⁶ - 13.1×10⁻⁶), and the values of Sr/Y (140.84 - 274.67) and Laₙ/Ybₙ (1.98 - 65.23) are relatively high, similar to adakitic rocks. The rocks are enriched in LREE and LILE, depleted in HREE and HFSE, and have a weak positive Eu anomaly (δEu is 1.02 - 1.20). The zircon saturation temperature (t_Zr) is 747 - 762 °C (with an average of 755 °C). Based on comprehensive regional geological data, this paper infers that the granodiorite may have formed in a subduction - related continental arc environment and is the product of partial melting of the thickened lower crust with the participation of fluids.

库鲁克塔格地块位于塔里木克拉通东北缘,其中发育有大量新元古代岩浆岩,为进一步明确这些岩浆岩的成因,探讨区域地质演化过程,本文对库鲁克塔格地块西段的卡乌留克花岗闪长岩进行了岩相学、年代学及地球化学研究。结果表明,花岗闪长岩形成于新元古代早期(823~ 810 Ma),为准铝质-过铝质Ⅰ型花岗岩类;显示高硅、钠、铝,低钙、铁、钾的岩石地球化学特征;其Sr高(1690×10~(-6) ~ 2060×10~(-6)) 、Y低(7.5×10~(-6) ~ 13.1×10~(-6)),Sr/Y(140.84~ 274.67)及La_N/Yb_N(1.98~ 65.23)值较高,与埃达克质岩石类似;岩石富集LREE、LILE,亏损HREE、HFSE,具有弱的Eu正异常(δEu为1.02 ~ 1.20);锆石饱和温度(t_(Zr))为747~ 762 ℃(平均755 ℃) 。综合区域地质资料,本文推断该花岗闪长岩可能形成于与俯冲有关的大陆弧环境,是流体参与下加厚下地壳部分熔融的产物。