塔里木东河塘二叠纪破火山口的三维地震解释与形成机制研究  

Three-d Seismic Interpretation and Formation Mechanism of Permian Calderasin the Donghetang Area of the Tarim Basin,Xinjiang,China

作　　者：李晓敏[1] 田伟[1] 弓明月 王磊[1] 刘平平 何衍鑫 LI Xiao-min;TIAN Wei;GONG Ming-yue;WANG Lei;LIU Ping-ping;HE Yan-xin(School of Earth and Space Sciences,Peking University,Bejing 100871,China;Petroleum Exploration and Production Research Institute,SINOPEC,Beijing 100083,China)

机构地区：[1]北京大学地球与空间科学学院,北京100871 [2]中石化勘探开发研究院,北京100083

出　　处：《矿物岩石地球化学通报》2022年第4期747-758,I0002,I0003,共14页Bulletin of Mineralogy, Petrology and Geochemistry

基　　金：国家自然科学基金资助项目(41702360);科技部重点研发计划课题(2019YFA0708503)。

摘　　要：破火山口在地球和类地行星的裂谷火山系统中广泛分布,然而其成因一直存在争议。有学者认为破火山口及其裂堑系统是板块构造运动的产物;而一些火山学家根据对地球上活动火山的观察,提出破火山口裂堑系统是火山动力学过程的产物。塔里木盆地东河塘工区发育近圆形和拉长状两类破火山口。拉长状破火山口沿二叠纪火山通道顶部的裂堑分布。通过对三维地震剖面的详细解释,确定破火山口裂堑的形成与超过100 km^(3)的热火山碎屑流的喷发具有同时性。根据火山通道的不规则外形、发育碳酸盐围岩捕掳体和缺乏强制褶皱的特征,确定破火山口裂堑塌陷是由于富CO_(2)岩浆通道在喷发释气过程中体积收缩形成。本研究为行星破火山口裂堑系统的成因提出一个新的模型,即岩浆-富挥发分围岩(如本实例中的碳酸盐岩)相互作用与火山通道释气回缩的共同作用。本研究成果对研究火山活动对行星大气圈演化的影响具有重要意义。Calderas are widely distributed in rift volcanic systems of the Earth and terrestrial planets,but their origin has been disputed.Some authors believe that calderas as well as the related rifts are products of plate tectonic movement;while some volcanologists proposed that the calderas and rifts were formed by the volcanic dynamic process based on the field observation of active volcanoes on the Earth.Two types of calderas,rounded and elongated ones,occurred in the Donghetang exploration area of the Tarim Basin.The elongated calderas are distributed along rifts on top of the Permian volcanic channel system.Based on the detailed 3-D seismic interpretation,we have confirmed that the formation of rifts of the elongated calderas had occurred simultaneously with the eruption of hot pyroclastic flows over 100 km^(3).We have proposed that the collapse of the elongated calderas rifts was caused by the volume contraction of the CO_(2)-rich magma channel during the process of gas release and magma eruption,based on characteristics of the irregular shape of magma channel,the extensively distributed xenoliths of carbonate wallrocks and the absence of forced folds above the sills.A new model for the genesis of the planetary caldera rift system,namely,the interaction between magma and volatile-rich wallrocks(e.g.,carbonate rocks in this case)and the retraction of gas released from volcanic channels,has been proposed in this study.It is of great significance to study the influence of volcanic activities on the evolution of terrestrial planetary atmospheres.

关 键 词：破火山口 裂堑 碳酸盐岩 同化作用 释气 三维地震 塔里木 东河塘 

分 类 号：P511.3[天文地球—地质学]