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库车河流域小提坎里克组火山岩主要为一套流纹岩建造,富碱(Na_2O+K_2O=6.89~8.46%)、高钾(K_2O/Na_2O=1.6~2.1)、铝含量12.83~14.78%(平均为14.18%),低钙(1.06~2.51%,平均为1.50%)、低镁(MgO=0.27~0.44%,平均为0.37%),Fe_2O_3~*=1.29%~2.68%(平均为2.17%)。其铝饱和指数A/CNK为0.98~1.15,为过铝质高钾钙碱性—钾玄质花岗岩类。流纹岩的轻稀土强烈富集,重稀土亏损,明显富集Rb、Th、U、K、Pb等大离子亲石元素,亏损Sr、Nb、Ta、P、Ti等元素,具明显的铕负异常(δEu为0.46~0.54)。主微量元素特征显示其壳源成因,原岩为变质杂砂岩,源区有石榴石、角闪石、斜长石的残留。对两个流纹岩样品中的锆石进行LA-ICP-MS U-Pb年龄测定,获得288.3 Ma和290.3 Ma的形成年龄,与西部温宿和拜城地区的小提坎里克组火山岩为同期火山活动产物。该套火山岩具有同碰撞过铝质S型花岗岩特征,结合区域上广泛分布的二叠纪后造山花岗岩,认为西南天山洋至少在早二叠世已经闭合。
The Kantianlike volcanic rocks in the Kuqa River Basin are mainly composed of rhyolite, which are rich in alkali (Na 2 O + K 2 O = 6.89-8.46%), high K (K 2 O / Na 2 O = 1.6-2.1) and Al 12.83-14.78 (Average 14.18%), low calcium (1.06-2.51%, average 1.50%), low magnesium (0.30-0.24%, average 0.37%) and Fe 2 O 3 ~ 1.29% -2.68% 2.17%). Its aluminum saturation index A / CNK is 0.98 ~ 1.15, which is a peraluminous high-K calc-alkaline-konite granite. The light rare earths of rhyolite are strongly enriched and heavy rare earths are depleted, which are obviously enriched in large ion lithophile elements such as Rb, Th, U, K, Pb and depleted in elements such as Sr, Nb, Ta, P and Ti with obvious europium Negative abnormalities (δEu 0.46 ~ 0.54). The characteristics of main trace elements show the origin of the crust, the original rocks are metamorphic miscellaneous sandstone, and the source area is the remains of garnet, amphibole and plagioclase. The zircon ages of the two rhyolite samples were determined by LA-ICP-MS and U-Pb dating to 288.3 Ma and 290.3 Ma, respectively. The volcanic rocks of the Wandikanlike Formation in the western Wensu and Baicheng areas were The same period volcanic activity product. This suite of volcanic rocks has the same collisional petrogenesis of S-type granites and is widely distributed in the area as a Permian post-orogenic granite. It is believed that the southwestern Tianshan Ocean was closed at least in the Early Permian.