tailieunhanh - Báo cáo " Method of sedimentary basin reconstruction and compilation of lithofacies - paleogeographic maps "

A secondary basin corresponds with a second order depositioual cycle, is limited by two erosional surfaces which are also the boundaries of a seismic sequence. In other words, a secondary basin is a component of an overall sedimentary basin. A secondary basin is formed at the same time with a tectonic phase where the tlu·ee most important factors are faulting, subsidence and uplifting. Basin-forming faults are usually normal faults and are called "syn-depositional fault". The reconstruction of a sedimentary basin, is rather complicated, but it is very necessary for basin ànalysis, facial analysis and compilation of· lithofacies-paleogeographic maps, as the dimensions and. | VNU Journal of Science Earth Sciences 25 2009 204-216 Method of sedimentary basin reconstruction and compilation of litho facies - paleogeographic maps Tran Nghi Hanoi University of Science VNƯ 334 Nguyen Trai Hanoi Vietnam Received 3 October 2009 Summary. A secondary basin corresponds with a second order depositional cycle is limited by two erosional surfaces which are also the boundaries of a seismic sequence. In other words a secondary basin is a component of an overall sedimentary basin. A secondary basin is formed at the same time with a tectonic phase where the three most important factors are faulting subsidence and uplifting. Basin-forming faults are usually normal faults and are called syn-depositional fault . The reconstruction of a sedimentary basn is rather complicated but it is very necessary for basin analysis facial analysis and compilation of lithofacies-paleogeographic maps as the dimensions and thickness of the present secondary basin are not the same as of the primitive basin. To get a true picture of the primitive basin one must carry out the following steps - Drawing the reconstructed geologic sections - Reconstructing the sediment thickness Ya where h is the primitive thickness h2 is the present thickness K is the shrinkage coefficient depending on the rock type Pl is the primitive common porosity p2 is the present common porosity - Reconstructing the integrated geologic-sedimentary sections Width of the basin L1 C. U- a ÍX ti rj i i l where c is a correction coefficient diagenetic stage catagenetic stage and metagenetic stage . Thickness of the basin Hi ch2 - Reconstructing the boundaries of the basin - Reconstructing the isopach map - Compiling the lithofacies-paleogeographic map. E-mail trannghi@ 204 T. Nghi ì VNU Journal of Science Earth Sciences 25 2009 204-216 205 Introduction So far sedimentologists usually draw lithofacies-paleogeographic maps with omission of a principled stage . the reconstruction .