Sedimentary Response To Tectonic Evolution Of The Central Guizhou Uplift And Its Adjacent Areas

The oil and gas exploration takes an increasingly role in China’s economic development, marine carbonate rocks has a great potential for exploration, the Central Guizhou Uplift and its adjacent areas are the important succeed battlefield that southern China exploration goes out of the Sichuan Basin. Predecessors have done certain research in this area, but there are some deficiencies in the comparison of sequence stratigraphy, lithofacies paleogeography, structural analysis, and petroleum geology.This paper taked Central Guizhou Uplift and its adjacent areas Ordovician, Silurian as the main research object, also the late Paleozoic strata was involved, and conducts a comprehensive study of the sequence stratigraphy, depositional systems, lithofacies palaeogeography, fault structure and tectonic evolution. The detailed study of sequence stratigraphy was carried out with outcrop and drill logging data,10three-order sequence boundaries were identified in the Ordovician, and divided them into9three-order sequences, of these interfaces, OSB1, OSB3,OSB4, OSB5and OSB9are type Ⅰ sequence boundary, and other sequence boundaries are type Ⅱ sequence boundary.5three-order sequence boundaries were identified in Silurian, and divided them into4three-order sequences, of which SSB1, SSB2, SSB3, SSB4and SSB5are type Ⅰ sequence boundary. Based on the sequence stratigraphic classification and analysis of seismic facies, the formation time of Central Guizhou Uplift was studied, and found that the Central Guizhou Uplift formation was not done overnight but by repeated times, the earliest time was the Ordovician Tongzi Period, it was underwater uplift stage, it first exposure of the water until the early Meitan Formation, then it was flooded by seawater, and rose out of the water again in the late Meitan Formation. The Central Guizhou Uplift was finally lifted into land until the late Wufeng Formation.By studying the the spatial distribution characteristics and kinematic characteristics of the fault zone, the controlling action of the four boundary faults in Central Guizhou Uplift and its adjacent for facies and deposition was analyzed. Zunyi Fracture had no controlling action on the deposition of both sides, and no affect on the formation, evolution and deposition of the Central Guizhou Uplift. Yadu-Ziyun Fracture started its activities during the Duyun Movement period, leading to the disintegration of the Dianqiangui Ancient Land, and played a significant controlling role in the deposition of the Central Guizhou Uplift. Hezhang-Zunyi Fracture had controlling action on the sedimentary facies and paleontology of both sides in fault zone in Ordovician, and the controlling role was more significant in Silurian. Zhenyuan-Guiyang Fracture played a significant controlling role in the deposition of both sides in fault zone during the Duyun Movement period. During the Guangxi Movement period, the fracture essentially controlled the sedimentary boundary of the Silurian in the southern edge of Central Guizhou Uplift.With a large number of outcrop section, drilling logging data and seismic data,4kinds of sedimentary system-coastal deposition system, shelf sedimentary system, carbonate platform sedimentary system, slope-basin sedimentary system were identified in the Central Guizhou Uplift and its Adjacent Areas, and each sedimentary system was further subdivided. Provenance analysis was conducted by Dickinson triangular cast point diagram method while supplemented by heavy minerals, it was found that the provenance of Northern Guizhou Slope, Wuling Depression, Southern Guizhou Depression was from Niushoushan Ancient Land, also the provenance of the Southern Guizhou Depression was affected by Xuefeng Uplift in the southeast. High quality seismic facies were selected to study the seismic facies of southern Guizhou depression, four kinds of seismic facies were identified in Ordovician, and three kinds of seismic facies were identified in Silurian. Based on division and correlation of the sequence, depositional systems, and sedimentary connected well correlation, seismic facies study, taking outcrop sequence stratigraphy as the guidline, combining with drilling and seismic data, and taking the three system tracts as time unit, the lithofacies paleogeographic map of Ordovician and Silurian in Central Guizhou Uplift and its adjacent areas was established. The Central Guizhou Region experienced the shallowing of OSQ3TST period, it was exposured of the water surface for the first time during the OSQ3HST period, during the OSQ4HST period the Central Guizhou Uplift was exposured of the water surface again, the geographical pattern evolved into the southern high northern low situation from the situation that the north west was high and south east was low during the OSQ8HST period. When it came to the OSQ9TST period, the Central Guizhou Uplift was completely uplifted into land, and it fused with Southern Guizhou and formed into Dianqiangui ancient land. During SSQ2TST period, the sea water was intrused, which led to the redisintegration of Dianqiangui ancient land.Yunan Movement was the start of the formation of the Central Guizhou Uplift, the collision of Yunkai Block and Qiangui-Beiyue Block caused the water of Xifeng-Zhijin was relatively shallow, the Ordovician Tongzi Period was a set of domolite deposition, it was the underwater uplift stage. Duyun Movement caused the study area to further uplift, the Central Guizhou Region was basically out of the water, becoming onshore uplift and connected the Diandong ancinet land which was the invasion by western. In the period of Late Ordovician, Duyun Movement further strengthened, and ultimately made the Central Guizhou, Qiannan rising into land, the deposition of Late Ordovician and Early Silurian was omission. The Central Guizhou Uplift was inheritance strengthened by Guangxi Movement, the scope of Central Guizhou Uplift further expanded, the Central Guizhou, Qiannan overall continued to uplift, its upper miss Upper Silurian-Lower Devonian, and even part of the Carboniferous Datang Group and the Ordovician Meitan Group directly contact.The characteristics of source-reservoir-cap, the reservoir forming and damage and the geological reserves of Majiang ancient reservoir, Weng’an ancient reservoir in Central Guizhou Uplift and its adjacent areas were analyzed. It was found that the development of hydrocarbon source rocks has a multi-storey department, the Cambrian Niutitang Formation, Silurian Longmaxi Formation were main hydrocarbon source rocks, while the Sinian Doushantuo Formation mudstone, the middle Devonian shale and marl, Carboniferous shale, Permian mudstone, limestone and coal measures were minor hydrocarbon source rocks. The reservoirs were mainly Upper Sinian Dengying Formation, the sandstone at the top of the Lower Cambrian Mingxinsi Formation, the carbonates in Lower Ordovician, the sandstone in Silurian. It was found that the Central Guizhou Uplift and its adjacent areas had3sets of regional seal and2sets of local seal. The3sets of regional seal were the Lower Cambrian Niutitang-Jindingshan Formation, the Jindingshan-Qingxudong Formation and the upper of the middle-lower Silurian. The2sets of local seal were Cambrian Marketing gypsum rock of Central Guizhou Uplift and Northern Guizhou Slope, the Middle Ordovician mudstone class remained in Guiding-Sandu-Huangping in southern Guizhou. The Central Guizhou Uplift and its adjacent areas mainly had3sets of reservoir combination. Favorable oil and gas exploration area in the Central Guizhou Uplift and its adjacent areas was selected, and the Anshun depression is the best blocks in hydrocarbon preservation conditions.