| Popis: |
A new criterion, geodynamic principles and processes, is incorporated with continental margin type, basin position on a plate, and crustal type to classify sedimentary basins. Within plate interiors, cratonic basins are formed by mechanical extension followed by thermal subsidence with a later flexural overprint. In passive margins, rift basins form by extension followed by thermal subsidence, and are oriented nearly parallel to margin edges. Aulacogens form similarly, but are oriented nearly at right angles to plate boundaries. Flexure basins are formed by load flexure along the plate edge. Sedimentary basins of active continental margins are part of a spectrum of compressive-collisional margins to compressive-extensional margins. Trench slope basins (on the trench wall) involve both a compressional and extensional history, whereas trench basins and forearc basins are compressional only. Intra-arc basins form by extension followed by thermal subsidence within magmatic arcs, and occur on continental crust, whereas backarc basins form by extension and rapid thermal subsidence involving oceanic crust. Thus the basins of a transect across a B-subduction zone and arc show a progressive change from compression to extension inboard from the trench floor. In transform margins, pull-apart basins and transpressional basins from by extension, thermal subsidence and translation. The distinction between the two basins is controlled by basin position on a transform margin associated with releasing bends (pull-apart basins) and restraining bends (transpressional basins). Collisional margins develop foreland basins inboard from the collision zones. A distinction is made between peripheral foreland basins caused by endloading and flexure along a plate edge, and retroarc foreland basins which are located inboard on the plate. Superposed (collage) basins form by compression on collisional plate boundary suture zones. Most basins, particularly older ones, show a history of multiple basin evolution and are named polyhistory basins. Successor basins are characterized by temporal succession of changing prototype basins. Resurgent basins show a temporal succession of repeated, identical prototype basins. To improve prediction of occurrence of commercial hydrocarbon and sedimentary-hosted ore deposits, it is recommended that the proposed geodynamic basin classification be combined with either organic (petroleum) or inorganic (metals) geochemical classification systems. Organic geochemical basin classification discriminates basin types using three criteria of organic maturation: charge factor, migration drainage factor and impedance factor. A similar maturation approach is developed for mineral deposits, and an inorganic geochemical classification is proposed herein recognizing three criteria of inorganic maturation: metal solubility factor, migration drainage factor, and environmental potential for mineral precipitation. Combining the geodynamic and geochemical maturation approach to basin classification should enhance commercial exploration and exploitation. |
