新疆库地北喀拉斯坦代里牙一带中元古代石英闪长岩年代学、地球化学特征及地质意义

Chronology,Geochemical Characteristics and Geological Significance of Middle Proterozoic Quartz Diorite in the Kalasitandaliya Area of Northern Kudi,Xinjiang

在库地北喀拉斯坦代里牙一带构造混杂岩中厘定出中元古代石英闪长岩,对其开展地质学、岩石学、岩石地球化学和同位素年代学研究。石英闪长岩SiO_(2)含量54.55%~55.84%,MgO含量5.42%~5.65%,Ti_(2)O含量1.15%~1.57%,Mg~#为57~58,里特曼指数σ为1.57~1.80,属高钾钙碱性系列。稀土元素总量∑REE为150.5×10^(-6)~183.68×10^(-6);(La/Yb)N为1.98~2.27,(La/Sm)N为1.39~2.08,(Gd/Yb)N为1.00~1.01,δEu=1.03~1.11。石英闪长岩锆石U-Pb年龄为(1130.3±5.6)Ma。西昆仑库地北喀拉斯坦代里牙一带石英闪长岩形成时代为中元古代晚期,属赞岐类高镁闪长岩,由地幔橄榄岩与消减洋片反应形成,形成于大陆岛弧环境,是Rodinia超大陆聚合过程洋壳向塔里木板块俯冲消减的地质记录。

Previous scholars have insufficient understanding of the pre Cambrian magmatic activity and tectonic evolution in the northern margin of the West Kunlun Mountains,resulting in significant differences.The author identified the Middle Proterozoic quartz diorite in the tectonic melange of the Kalastandailiya area in Kudi,and conducted geological,petrological,geochemical,and isotopic dating studies on it.The SiO_(2)content of quartz diorite ranges from 54.55%to 55.84%,MgO ranges from 5.42%to 5.65%,Ti_(2)O content ranges from 1.15%to 1.57%,Mg#ranges from 57%to 58%,and the Rittmann indexσranges from 1.57 to 1.80,belonging to the high potassium calcium alkaline series.The total amount of rare earth elements∑REE ranges from 150.5 to 183.68×10^(-6);(La/Yb)N ranges from 1.98 to 2.27,(La/Sm)N ranges from 1.39 to 2.08,and(Gd/Yb)N ranges from 1.00 to 1.01,δEu ranges from1.03 to 1.11.The U-Pb age of zircon obtained from quartz diorite is 1130.3±5.6 Ma.The formation of quartz diorite in the northern Kalastandailiya area of Kudi in the western Kunlun Mountains dates back to the late Mesoproterozoic era,belonging to the Zanqi type high magnesium diorite.It was formed by the reaction of mantle peridotite and subducted ocean sheets,and was formed in continental island arc environment.It is the geological record of the subduction and subduction of oceanic crust towards the Tarim block during the Rodinia supercontinent aggregation process.