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西昆仑北缘库斯拉甫一带侵入前寒武纪结晶基底(Ch)的中元古代两期岩体,早期以喀特列克岩体为代表,年龄为1 567 Ma,晚期以阿孜巴勒迪尔岩体为代表,年龄为1 423 Ma。早期岩体(δoPt)具有贫硅、高钙、中碱和准铝质等特征;岩性主要为钙碱性石英闪长岩,岩石稀土总量为168.4×10~(-6)～374.38×10~(-6)、轻重稀土比值为9.3～18.23,中等负铕异常(8Eu=0.53～0.82)。晚期岩体(ηγPt)具有富硅、高碱、富钾、强过铝质和全铁含量高等特征;岩性主要为碱性二长花岗岩,岩石具高的104*Ga/Al比值(3.01～3.5),很高的REE含量(375.68×10-6～1 075.46×10~(-6)),高LREE/HREE(7.07～16.87)和高(LaN/YbN)(8.32～25.2)及强烈负Eu异常(δEu=0.25～0.31)。通过对两期岩体(δoPt和ηγPt)同位素年龄、矿物学、岩石化学、微量元素及稀土元素等特征系统地研究,认为西昆仑北缘在中元古代发生两次明显的岩浆—构造事件,早期事件(δoPt的侵位)与兴地运动(I幕)有关;晚期事件(ηγPt的侵位)在时间及区域上与兴地运动(Ⅱ幕)比较吻合;早期岩浆(δoPt)可能存在部分幔源物质的加入,显示I型花岗岩的特征,可能属于造山期后花岗岩类;晚期岩浆(ηγPt)可能经历过下地壳的部分熔融或较高程度的分异演化过程,属于A2型花岗岩的范畴。两期岩浆活动可能为古塔里木板块的固结—裂解提供了新的证据及裂解模式的补充。
The Mesoproterozoic stage two intrusions intruded into the Precambrian crystalline basement (Ch) in the area of Kuslafu on the northern margin of Western Kunlun, was represented by the Early Cretaceous, with an age of 1 567 Ma. In the late stage, Ledier rock mass, represented by the age of 1 423 Ma. Early rock mass (δoPt) is characterized by poor silicon, high calcium, moderate alkali and quasi-aluminum. The lithology is mainly calc-alkaline quartz diorite with the total amount of rare earths ranging from 168.4 × 10 -6 to 374.38 × 10 ~ (-6), the ratio of light to heavy rare earth is 9.3 ~ 18.23, and moderately negative Eu anomaly (8Eu = 0.53 ~ 0.82). The late stage rock mass (ηγPt) is rich in silicon, high alkali, potassium, strong permanganate and high total iron content. The lithology is mainly alkaline monzogranite with a high 104 * Ga / Al ratio (3.01 ~ 3.5), high REE (375.68 × 10-6 ~ 1075.46 × 10 -6), high LREE / HREE (7.07-16.87) and high (LaN / YbN) (8.32-25.2) Eu anomaly (δEu = 0.25 ~ 0.31). By systematically studying the δθPt and ηγPt isotopic ages, mineralogical, petrochemical, trace elements and rare earth elements in the two phases of rock masses, it is considered that there are two obvious magmatism-tectonism events in the northern margin of West Kunlun during the Mesoproterozoic, The early events (emplacement of δoPt) are related to Xing-I movement (I-curtain); late events (invasion of ηγPt) coincide with Hing-earth movement in time and area (II); there may be part of early magma (δoPt) The addition of mantle-derived materials indicates that the type I granites may belong to post-orogeny granitoids. The late magma (ηγPt) may have undergone partial crustal melting or high-level differential evolution and belong to the category A2 granite . The two magmatic activities may provide new evidence for the consolidation and cracking of the ancient Tarim plate and complement the cracking mode.