Tectonic Evolution And Prototype Basin Sedimentary Characteristics Of The Eastern Edge Of North America Since The Late Proterozoic

Under the instruction of plate tectonics theory and Sedimentary basin analysis method,on the basis of former researchers' achievements,this paper mainly focus on the evolution of North American,tectonic movement,prototype basin development and sedimentary characteristics of the eastern margin.This has important theoretical and practical significance for riching basin prototype and plate tectonics theory,and providing strategic basis for overseas oil and gas exploration and exploitation.Phanerozoic tectonic evolution of the North American can be summarized into three main stages:(1)From Precambrian to Ordovician,is the cracking phase of Pannotia.The North American plate separated from supercontinent,drafted counterclockwise,from south to north across the equator.(2)From Late Ordovician to Late Permian is the phase of assemblage of Pangea.The oceanic crust of Iapetus Ocean subducted under the eastern edge of North America,which then collided with Baltica,caused Taconic,Caledonian and Acadian orogeny.The reduction of Rheic Ocean,resulted the collision of North America,Africa and South America,formed the Allegheny,Marathon and Ouachita orogeny.(3)From Triassic to present days is the phase of breakup of Pangea.North American separated from Africa,South America and Europe.The Atlantic opened and expanded.Evolution of the eastern margin of North American prototype basin is also divided into three stages:(1)Cambrian-Ordovician,rift basins to passive margin basins stage.(2)Late Ordovician-Late Permian,passive margin basins developed into back-arc basins at the eastern edge of North America.Orogences formed as terranes and arcs collided with continent.Orogenic foreland basins developed in the extrusion environment.(3)In Triassic,difts developed at the eastern and southern edge of North America,as a result of extensional environment.Expansion of the oceanic crust makes rift basins subsided and developed into passive margin basins.Tectonic movement impact the evolution of basins,and then affect the sedimentary characteristics and control oil and gas prospects.The Michigan Basin subsided as a craton basin because Taconic orogeny,carbonates and reef reservoir was well-developed in Ordovician and Silurian.The Appalachian Basin,as a foreland basin,makes huge oil and gas production in clastic reservoir-cap portfolio in Upper Devonian and above strata.The Scotian Basin and The Deep Water Gulf of Mexico Basin at the eastern and souhtern margin of North America developed from rift basins to passive margin basins,deposited shallow marine carbonate and delta sandstone,mudstone in Jurassic,Cretaceous and Tertiary,which also make up favorable reservoir-cap portfolio.