构造不整合的分布样式及其对地层圈闭的制约-以塔里木盆地中泥盆世末为例

Distribution patterns of the end of the Middle Devonian tectonic unconformity and their constrain on the development and distribution of favorable stratigraphic traps in the Tarim Basin

中泥盆世末构造不整合是塔里木盆地最重要的不整合之一,是早海西构造变动的产物。这一不整合在盆地内分布十分广泛,从隆起区向洼陷区表现为叠合不整合、高角度不整合、微角度不整合、平行不整合至整合。在塔北、塔中等地区对下伏地层削蚀强烈,不整合之后又伴随着晚泥盆世东河砂岩的沉积上超,形成多个削蚀不整合三角带和上超不整合三角带。不整合的分布和结构样式反映了构造运动的结果,同时对有利地层圈闭发育分布具有明显的制约作用,削蚀不整合三角带是寻找志留系岩性地层圈闭的有利区,上超不整合三角带是寻找泥盆系东河砂岩岩性地层圈闭的有利区。

As a result of the early Hercynian Movement, the latest Middle Devonian tectonic unconformity is one of the most important unconformities in Tarim basin. It is widely distributed in the basin, occurring in the forms of superimposed unconformity, high angle unconformity, parallel unconformity, and conformity from the uplifted area to the depression. The underlying strata in Tabei and Tazhong areas were eroded severely and were accom- panied by deposition and onlapping of the Donghe sandstone along the unconformity in Late Devonian, forming several erosional unconformity triangle zones and onlapping unconformity triangle zones. The distribution and structural styles of the unconformity are the results of tectonic movement and controls the distribution of the favorable stratigraphic traps. The erosional unconformity triangle zones are the potential areas for the Silurian lithologic traps, while the onlapping unconformity triangle zones are regarded as the favorable areas for the Devonian Donghe sandstone lithologic traps.