Depositional-tectonic Evolution And Pennsylvanian Paleogeography Of Great Permian Basin, North America Plate

The Permian Basin of west Texas and Southeastern New Mexico is one of the major petroleum producing regions of the United States. The Permian Basin extends beneath an area approximately 250 miles(400 km) wide and 300 miles(480 km) long. The Permian Basin has been characterized as a large structural depression formed as a result of downwarp in the Precambrian basement surface located at the southern margin of the North American craton. The basin was filled with Paleozoic carbonate rock.From middle Ordovician to Silurian Period,this area was a broad and steady Carbonate platform with shallow-water. The south area of North America plate was collided with northern of south America plate during Early Carboniferous period(Mississippian),as a result,the original basin become a alluvial plain,and filled with mixed sandstone and mudstone. From late carboniferous to early Permian,the basin became structural differentiation. During Pennsylvanian period,the original basin formed the embryo structural framework as basin-platform-shelf. Broadly,carbonate deposition dominates in the shelf and Platform,whereas,The basin was filled with classic deposition. At the end of the Permian period,Pangea became break up,resulting a decline of sea level, ocean circulation is limited, began to deposit evaporate.,and formed carbonate reef in the Delaware basin,Margin of Midland basin and central Basin Platform.After Permian,the basin is a rise period and suffered from erosion. During Mesozoic,Permian Basin is a Sustained Platform Stage.Laramide deformation and later tectonic movement only effected on the western of the basin, and formed the structural framework as high western and low eastern.Thus,Tectonic evolution stage can be divided into passive continental margin stage,collision stage, Permian basin phase,stability basin,laramide, volcanism and basin- mountain stage.During Pennsylvanian period, Permian basin is a intracraton open-marine basin. It is mainly deposited clasolite and delta sedimentary in offshore. whereas in the far away of basin, mainly deposited thick carbonate and mudstone.Thus, shallow-water shelf was filled with carbonate rock,in the deep-water basin mainly distributed mudstone.Permian basin is a multigroup basin with 4 petroleum system at least,From Pre-Cambrian crystalline basement to cretaceous, it contains oil and gas in different degree.But Permian petroleum geological reserves is the largest,it account for 67% of total reserves.Gas was mainly saved in Lower Ordovian,the distribution of vertical of oil and gas resources is unequal.