Indexed on: 02 Aug '12Published on: 02 Aug '12Published in: Journal of Earth Science
The structural framework and evolution processes of the giant superimposed Tarim basin in Paleozoic Era are controlled by three main factors: (1) features and structures of the basin basement; (2) deep mantle dynamics process (such as the Sinian rifting and the Permian plume-related magmatic activities); (3) the powerful regional compressional or compresso-shear stress regime generated by the orogenic movement from surrounding regions. The latter of which occurring in multiple episodes is the most important factor for the Paleozoic Tarim basin evolution. Under the above tectonic background, the underlying lithosphere of the Tarim basin had been flexed, and then the upper crust was folded. The paleo-uplifts (e.g., Tabei (塔北) and Tazhong (塔中)) and depressions occurred in both of the flexural and folding processes, which are different with the models of foreland basin in stable and large cratons in the world. During the early evolution stage in Cambrian-Early Ordovician, low-relief paleo-uplifts, and open carbonate platforms formed in center area, while during the Late Ordovician compressional tectonic regime, the belted uplifts and restricted platforms formed in the contemporaneous folding processes. Denudated stages occurred during the strong tectonic events marked by the unconformities and karstified weathered crusts formed on platforms. All the discovered giant-middle oilfields are closely related to the paleo-uplift and karstified crust evolution. There are two main types of oil reservoir: paleo-karst type and reef-bank type on the carbonate platform in paleo-uplift areas. In Permian, plume-related massive magmatic activities led to geo-temperature increase and the regional uplifting in this basin, ending the marine deposit filling sequences and starting the formation of terrestrial deposits-dominated sequences. With abundant supply from giant hydrocarbon generation depressions, the most important oil fields formed in Tabei and Tazhong areas. To reveal the multi-stage evolution processes and the structural framework of the paleo-uplifts may be helpful for the prediction of new hydrocarbon domains. The integrated study on coupling relationship between the basin and surrounding orogens can provide an important approach for the superimposed basin dynamic research.