塔里木盆地二叠系划分对比与火山岩分布

根据全盆地钻井与露头剖面对比和地震剖面追踪解释,探讨了塔里木盆地覆盖区二叠系岩石地层的划分对比。二叠系自下而上由一个自然伽玛曲线加积段、三个自然伽玛曲线退积段组成,加积段为南闸组、退积段分别为库普库兹曼组、开派雷兹克组和沙井子组。南闸组是塔里木盆地最后一次海侵形成的滨浅海灰岩泥岩薄互层为主的沉积。库普库兹曼组和开派雷兹克组是两个基性火山岩-酸性火山岩的旋回或基性火山岩-砂泥岩的旋回。沙井子组是一个与区域构造运动有关的冲积扇、辫状河-曲流河沉积的异旋回。二叠系火山岩在和田河、塔中西部和顺托果勒地区厚度较大,库普库兹曼组火山岩一般0~60m,开派雷兹克组火山岩一般0~200m,局部可超过400m。与库普库兹满组火山岩相比,开派雷兹克组火山岩分布范围由塔西南朝塔东北方向有所迁移。中西部的库普库兹曼组火山岩可能喷发于水下。火山通道多沿着古隆起上的断背斜、断鼻构造分布。火山岩可形成油气藏遮挡,或本身形成储层,但火山活动改造或不同程度地破坏了早期已有油气藏。

Permian division and correlation and distribution of volcanic rocks of Tarim basin

Based on the basin-wide analysis of well, outcrops and tracing of seismic data, the underground Permian petrologic stratigraphy is re-divided and correlated throughout the Tarim Basin. Permian System upward consists of one aggradation interval and three retrogradation intervals of natural gamma ray logs. The aggradation interval belongs to Nanzha Formation, and the other three intervals belong to respectively Kupkuciman Formation, Kaipeleicike Formation and Shajingzi Formation. Nanzha Formation is dominated by rocks of brown gray shales interbedded with thin limestones that represent littoral to neritic deposits during the last transgression in Tarim basin. Kupkuciman and Kaipeleicike Formations are two cycles from basic to acidic volcanic rocks or from basic volcanic to terrestrial clastic rocks. Shajingzi Formation is an allocycle from alluvial fan to branded channel to meandering fluvial deposition resulted from a tectonic movement. The Permian volcanic rocks are thicker over the areas from Hetian River to Tazhong to Shuntuoguole. The volcanic rocks are atypically 0~60m in Kupkuciman Formation, and 0~200m or locally over 400m in Kaipeleicike Formation. The volcanic rocks of Kaipeleicike Formation are accumulated further northeast compared to that of Kupkuciman Formation. Over the middle to west region of Tarim basin, part of Kupkuciman volcanic rocks might have formed underwater. Volcanic passage and craters seen on seismic sections are distributed extensively on the anticlines or fault nose structures in uplifted region and rarely seen in depression area. Volcanic rocks can serve as cap or shelter rocks of a pool, or be reworked to be one kind of reservoir rocks, but mostly the volcanic activity might have affected or to some extent destroyed the earlier formed oil-gas pools.