CAJ | 학술논문

羌塘中部果干加年山上三叠统望湖岭组作为龙木错-双湖-澜沧江板块缝合带闭合最重要的沉积学证据已被广泛认知，但是望湖岭组中流纹岩的岩石成因至今尚未得到很好的解释。全岩地球化学分析表明，该流纹岩高硅、富碱、富铝，属钙碱性过铝质流纹岩；富集轻稀土元素，轻重稀土元素分馏较强，LREE/HREE=6.39~7.72，具明显的Eu负异常，富集Rb、Th、U和K，亏损Ba、Ta、Nb、Sr，强烈亏损P和Ti，具有后碰撞火山岩的特点。综合区域地质资料，龙木错-双湖-澜沧江板块缝合带于晚三叠世碰撞拼合，初步认为该流纹岩可能是岩石圈碰撞加厚之后减压过程中岩浆活动的产物，形成于后碰撞环境的应力松弛阶段。
강당중부과간가년산상삼첩통망호령조작위룡목착-쌍호-란창강판괴봉합대폐합최중요적침적학증거이피엄범인지，단시망호령조중류문암적암석성인지금상미득도흔호적해석。전암지구화학분석표명，해류문암고규、부감、부려，속개감성과려질류문암；부집경희토원소，경중희토원소분류교강，LREE/HREE=6.39~7.72，구명현적Eu부이상，부집Rb、Th、U화K，우손Ba、Ta、Nb、Sr，강렬우손P화Ti，구유후팽당화산암적특점。종합구역지질자료，룡목착-쌍호-란창강판괴봉합대우만삼첩세팽당병합，초보인위해류문암가능시암석권팽당가후지후감압과정중암장활동적산물，형성우후팽당배경적응력송이계단。
It is extensively known that the Guoganjianianshan late Triassic Wanghuling Formation is the most important sedimentologic evidence of the closure of the Lungmu Co-Shuanghu-Lancang River plate suture zone;nevertheless, so far the petrogenesis of the rhyolite remains unclear. The bulk rock geochemical analysis indicates the characteristics of high silica, rich alkali and Al, suggesting calc-alkali peraluminous rhyolite. The rhyolite samples are rich in LREE, the fractionation between LREE and HREE is strong with LREE/HREE being 6.39-7.72, and there exists obvious Eu negative anomaly. In addition, the rhyolite samples are enriched in Rb, Th, U, K, depleted in Ba, Ta, Nb, Sr, and prominently depleted in P and Ti, demonstrating the characteristics of post-collision volcanic rocks. An integrated analysis of geological survey information reveals that the Lungmu Co-Shuanghu-Lancang River plate suture zone was closed in late Triassic. The authors preliminarily hold that the rhyolite resulted probably from magmatic activity in the process of decompression after the lithosphere collision, and was formed in the stress relaxation phase of the post-collision environment.