Tectonic Evolution Of Western North America And The Control Effect On Basins

The western North America records a complex Phanerozoic history,which mainly includes several subduction-related orogenies with associated sedimentary basins.This paper focus on the west of North American,by studying its tectonic evolution and the relationship with the adjacent plates,as well as the development and sedimentation of its typical basins,then summarize the tectonic evolution of western North America and developmental characteristics of its basins,in order to study the effect whith tectonic controls on Basin and provide strategic basis to China for exploring and exploiting oil and gas overseas.The history of western North America including the following phases:(1)Latest Proterozoic rifting of Rodinia to form the early Paleozoic intraplate margin,along which accumulated the Cordilleran miogeocline;(2)Devonian—Pennsylvanian Antler orogeny is the first orogeny in western North America;(3)Permian-Triassic Sonoma orogeny is the beginning of cordillera subduction pattern;(4)Late Jurassic Nevadan orogeny in the context of north-to-south suturing of diverse island arcs and related terranes to western North and South America;(5)Latest Jurassic-Late Cretaceous arc-trench system(including forearc basins),with major retroarc shortening and flexural loading to form the Cordilleran retroforeland basin during the Late Cretaceous Sevier orogeny;(6)Latest Cretaceous-Eocene Laramide orogeny,involving shortening of continental basement far inland,as rapid convergence and possible subduction of buoyant crust resulted in flat-slab subduction;(7)Sudden slowing of convergence between North America and the Farallon plate,and consequent collapse of the subducting slab resulted to San Andreas transform boundary.Its related basin types also exhibit certain rules,namely the Cambrian-Silurian mainly passive margin basin,but later under the influence of subduction and collision converted to trench-arc-basin system and foreland basin,then the strike slip basin appeared when the San Andreas Fault formed.In order to have a better understanding of the western North America,the paper chose to focus on two basins,the San Juan Basin was a passive margin basin from Cambrian to Carboniferous and then turn to foreland basin,The Cook Inlet basin evolved from a back-arc basin setting during Mesozoic time to a fore-arc basin in the Cenozoic,these too basins well documented the western North America orogenies and arc-continent collision process.This thesis emphasizes on the basic overview,stratigraphic features,tectonic evolution,the prototype basin and paleogeographic evolution of these two basins,aims to help us study how the tectonic of western North America control basin types and sedimentation.