Basic Types and Structural Characteristics of Uplifts: An Overview of Sedimentary Basins in China

Abstract

Abstract:The uplift is a positive structural unit of the crust It is an important window for continental dynamics owing to its abundant structural phenomena, such as fault, fold, unconformity and denudation of strata. Meanwhile, it is the very place to store important minerals like oil, natural gas, coal and uranium. Giant and large‐scale oil and gas fields in China, such as the Daqing Oilfield, Lunnan‐Tahe Oilfield, Penglai 19–3 Oilfield, Puguang Gas Field and Jingbian Gas Field, are developed mainly on uplifts. Therefore, it is the main target both for oil and gas exploration and for geological study. The uplift can be either a basement uplift, or one developed only in the sedimentary cover. Extension, compression and wrench or their combined forces may give rise to uplifts. The development process of uplifting, such as formation, development, dwindling and destruction, can be taken as the uplifting cycle. The uplifts on the giant Precambrian cratons are large in scale with less extensive structural deformation. The uplifts on the medium‐ and small‐sized cratons or neo‐cratons are formed in various shapes with strong structural deformation and complicated geological structure. Owing to changes in the geodynamic environment, uplift experiences a multi‐stage or multi‐cycle development process. Its geological structure is characterized in superposition of multi‐structural layers. Based on the basement properties, mechanical stratigraphy and development sequence, uplifts can be divided into three basic types — the succession, superposition and destruction ones. The succession type is subdivided into the maintaining type and the lasting type. The superposition type can be subdivided into the composite anticlinal type, the buried‐hill draped type, the faulted uplift type and the migration type according to the different scales and superimposed styles of uplifts in different cycles. The destruction type is subdivided into the tilting type and the negative inverted type. The development history of uplifts and their controlling effects on sedimentation and fluids are quite different from one another, although the uplifts with different structural types store important minerals. Uplifts and their slopes are the main areas for oil and gas accumulation. They usually become the composite oil and gas accumulation zones (belts) with multiple productive formations and various types of oil and gas reservoirs.