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本松错花岗岩岩基位于龙木错-双湖缝合带内,是多期中酸性岩浆侵入的产物.通过对花岗岩岩基中的花岗质片麻岩LA-ICP-MS锆石U-Pb定年,获得206Pb/238U加权平均年龄分别为496.2±3.9,497.1±3.0 Ma,该年龄值是迄今在羌塘盆地发现最古老、最可靠的岩浆岩年代学记录,为解决该地区关键地质问题提供了新的线索.获得花岗质片麻岩的锆石Hf(t)均为负值(均值,2.9,4.1),暗示花岗质片麻岩为壳源成因,两阶段模式年龄均值为1648和1723 Ma,花岗质片麻岩是原特提斯洋向冈瓦纳大陆边缘俯冲而引起古老地壳物质部分熔融的产物,是冈瓦纳大陆拼合之后在冈瓦纳大陆的边缘发生的安第斯型造山作用,而不属于冈瓦纳超大陆汇聚过程中发生的陆-陆碰撞形成的泛非造山带.说明冈瓦纳大陆北缘的岩浆弧向北至少延伸到了龙木错-双湖缝合带以南地区,龙木错-双湖缝合带为冈瓦纳大陆的北界.
According to the LA-ICP-MS zircon U-Pb dating of granitic gneiss in granite basement, the Benshen fault granite is located in Longmucuo-Shuanghu suture zone, , And the weighted average 206Pb / 238U ages were 496.2 ± 3.9 and 497.1 ± 3.0 Ma, respectively. This age value is the oldest and most reliable magmatic rock chronological record so far found in the Qiangtang basin, providing a solution to the key geological problems in this area New clues. The zircon Hf (t) obtained from granitic gneiss has a negative value (mean, 2.9, 4.1) suggesting that granitic gneiss is the causality of the crust, with an average of 1648 for the two-stage model 1723 Ma, the granitic gneiss is a product of subduction of the ancient crustal material by subduction of the former Tethys to the margins of the Gondwanaland, an Andean formation at the margins of the Gondwanaland after the Gondwana consolidation Orogeny rather than the Pan-African orogenic belt formed by land-continent collisions during the convergence of the Gondwanaland supercontinent, suggesting that the magmatic arc to the north of the Gondwanaland extends northwards at least to the Longmucuo-Shuanghu suture In the south, Longmucuo-Shuanghu suture zone is the northern boundary of the Gondwanaland.