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熔积岩是岩浆与未固结的松软沉积物混合而生的一种特殊火山碎屑岩.它代表着岩浆活动与沉积作用的同期性,因此可以对岩浆喷发期内的沉积环境做出精确限定.在二叠纪塔里木大火成岩省西北缘印干-柯坪地区的早期喷发层序中首次发现熔积岩.其中,印干附近第二喷发期次层序中以淬冷开裂而形成的块状熔积岩为主,柯坪一带第二、第四喷发层序中则同时拥有块状熔积岩和流态熔积岩.上述熔积岩的宿主沉积物均为海相灰质,证明当时当地的岩浆喷发事件发生于陆表海相环境中.在距印干以东不远处的开派兹雷克剖面,同期层序中却只发育稳定的陆相溢流玄武岩而未见熔积岩,证明海陆环境在此发生了交互.在利用熔积岩确定三个剖面喷发环境的基础上,精确了塔里木大火成岩省西北缘喷发早期沉积环境的分布范围,及其随时间而发生变迁的详细过程.
Moltenite is a kind of special volcaniclastic rock mixed with unconsolidated soft sediment, which represents the synchronicity of magmatism and sedimentation, so it can make accurate sedimentary environment during magma eruption The first sedimentary rocks were found in the early eruption sequence of the Indo-Keping area in the northwestern margin of the Permian Tarim Large igneous province, in which the second eruption sequence near Indo-Gan was formed by quenching and cracking In the second and fourth eruption sequences of Keping, there are both massive and fluid-state sedimentary rocks, all of which host sediments are marine gray matter, At that time, the local magmatic eruption occurred in the terrestrial marine environment.At the Kai Peizi Lake section not far away from the east of the Yugoslavia, only stable continental over basalts developed in the same sequence without sedimentary rocks, proving The interaction between the sea and the land environment took place here.On the basis of using the sedimentary rocks to determine the eruption environment of the three sections, the distribution of sedimentary environment in the early eruption of the northwestern Tarim large igneous province and the detailed process of its change over time were precisely determined.