准噶尔盆地陆西地区上石炭统上层序火山岩岩相研究

采用地质、地震资料，对准噶尔盆地陆西地区上石炭统进行了层序划分与对比，并对上石炭统上层序火山岩岩性、岩相进行了分析。研究认为，陆西地区上石炭统可分为上、下2个层序，上层序的顶、底界均为区域性不整合面，在地震剖面上具有上超/削蚀的反射终端类型。上层序的岩石类型主要有玄武岩、安山岩、沉凝灰岩、凝灰岩、火山角砾岩、英安岩等。火山岩岩相有火山通道相、爆发相、溢流相和火山沉积相。火山通道相主要根据地震剖面上的锥状体来识别；爆发相岩性主要为火山角砾岩与凝灰岩，电性特征为高电阻率、高速度，伽玛值变化大，但以低伽玛为主，具有变振幅、断续或杂乱反射特征；溢流相岩性主要为玄武岩、安山岩、英安岩等，电性特征为高电阻率、高速度，伽玛值变化大，具有中-强振幅、较连续反射特征；火山沉积相主要由正常火山碎屑岩、正常沉积岩、火山碎屑沉积岩等组成，电性特征表现为高伽玛、低电阻率、低速度，具有强振幅、高连续反射特征。爆发相主要分布于达巴松凸起-夏盐凸起西部和东部；火山沉积相主要分布于夏盐凸起中部、玛湖凹陷南部；其他地区则为溢流相分布区。

Lithofacies of Volcanic Rock at the Top of Upper Carboniferous Stratigraphy in Luxi Area of Junggar Basin

By geologic information and seismic data, we carry out the sequence division and correlation for the upper Carboniferous stratigraphy in the Luxi area of Junggar basin, and discuss the lithology and lithofacies volcanic rock at the top of the upper Carboniferous stratigraphy. The result suggests that the upper Carboniferous stratigraphy in the Luxi area could be divided into two sequences, such as upper sequence and lower sequence. The top and base boundaries of the upper sequence are regional unconformity, which is shown as the onlap/erosion reflection terminal type in the seismic profile. The rock types in the upper sequence are basalt, andesite, sedimentary tuff, tuff, volcanic breccia, dacite, etc. The volcanic facies included volcanic conduit, explosive, overflow, volcanogenic sedimentation. The volcanic conduit facies can be distinguished by cone reflection in the seismic profile. The lithological rocks in the explosive rock facies are volcanic breccia and tuff, with high electrical resistivity and high velocity, various gamma values but low gamma value, accompanied with variable amplitudes, interrupted continuous reflection or scrambled reflection signature. The lithological rocks in the overflow facies are basalt, andesite and dacite, with high electrical resistivity and high velocity, various gamma value, accompanied with moderate-strong amplitudes, continuouse reflection signature. The lithological rocks in volcanogenic sedimentation facies are composed of normal volcaniclastic rock, sedimentary rock and volcaniclastic sedimentary rock, with electrical property of high gamma, low electrical resistivity and low velocity, as well as high amplitude, high continuouse reflection signature. The explosive rock facies is greatly distributed in the Dabasong uplift and the western and eastern parts of the Xiayan uplift. The volcanogenic sedimentation facies is mainly distributed in the central Xiayan uplift, southern Mahu sag. The other regions show the overflow facies.