On the basis of the regulary vertical stacking patterns ofmeter-scale cyclic-sequences in the quest for a fundamental unit of stratigraphy and sedimentology, 25 third-order sedimentary sequences that could be furtherly grouped into 4 second-order tectonic sequences are discerned in Late Paleozoic of the Nanpanjiang Basin. According with the natures of stratigraphy and sedimentology as well as the meanings on tectonics, sequence boundaries might be divided into four types: tectonic unconformity that is similar to type I boundary defined by Vail et al., sedimentary unconformity that is similar to type Ⅱ boundary, drowned unconformity and their relative surfaces. There are two reef-building periods in Late Paleozoic of the Nanpanjiang Basin, which are correspond to developing periods of regional oil-generating strata constituted by basin facies shales, so the well congenital forming condition of oil and natural gas is established. In generally, the reservoir constituted by reef and grain beach limestones is formed in the rising process of third-order sea-level changes, and the dolomitic reservoir is generated in forced-regression process resulted from the falling period of third-order sea-level changes. Based on the study on sequence stratigraphy, three regionally potential association of oil-generating strata, reservoir and capping bed could be discerned in Late Paleozoic of the Nanpanjiang Basin: the lower association which Caladonian unconformity and Devonian reefs developed in isolated platform constitute its main prospecting targets; the middle association which its main prospecting target refers to dolomitic reservoir of Carboniferous Dapu Formation; the upper association which its main prospecting targets include the unconformity of Dongwu revolution as well as reef limestones and reef-top dolomites of Middle Permian Maokou Formation, and reef limestones of Late Permian Changxing Formation in isolated carbonate platform.%以米级旋回层序为基本工作单元，米级旋回层序在长周期三级层序中的有序叠加形式为基础，在南盘江盆地晚古生代地层中共识别出25个三级层序(沉积层序)；以构造不整合面为准，又可进一步归为4个二级层序(构造层序)。根据地层、沉积特征及构造地质涵义，把层序界面归纳为4种类型：构造不整合面、沉积不整合面、淹没不整合面以及它们的相关面，其中构造不整合面类似于类型Ⅰ界面，沉积不整合面类似于类型Ⅱ界面。晚古生代南盘江盆地存在两个明显的造礁期。于三级海平面上升阶段主要发育礁滩相灰岩构成的储层；而在与三级海平面下降相关的强迫型海退过程中则发育白云岩构成的储层。因此，可把南盘江盆地区域性的潜在生储盖组合拟定为3个：以孤立台地上泥盆系生物礁和加里东运动不整合面为主要勘探对象的下组合；以石炭系大埔组白云岩为主要勘探对象的中组合；以茅口组上部和长兴组生物礁及礁顶相白云岩、东吴运动不整合面为主要勘探对象的上组合。
展开▼
