Study Of Trassic Cyclic Stratigraphy In Tarim Basin And Reseach On Recovery Of Erosion Thickness By Sedimentation Rate

This dissertation focused on the Triassic strata in Tarim Basin, set up the Triassicsequence stratigraphic framework by using well-log and seismic data technology.Under the guidance of absolute geologic time, based on the sequence stratigraphicframework, using GR data filtering to analysis the stratigraphic cyclicity. Meanwhile,with the sedimentation rate which from astronomical tuning, the erosion thickness ofthe Triassic Akekule formation and Halahatang formation were regained.Based on the drilling and well-logging data, combine the seismic data to carryout the three-level sequence boundary recognition. The Triassic strata was dividedinto four three-level sequence, among them, T-SQ1represents for the Ketuerformation and the Akekule formation is correspond to T-SQ2and T-SQ3, theHalahatang formation is stand for T-SQ4.On the basis of predecessors’ achievements, study on the time stamp such assedimentary record in sedimentary basins, with sporopollen and fossils contrastedwith geological time scale, confirm the Triassic tectonic activity stage in Tarim Basinand find the deposition time relationship. Ketuer formation deposition time is252.17Ma-247.20Ma, Akekule formation is245.00Ma-228.00Ma, and Halahatangformation is228.00Ma-199.6Ma.Using GR data filtering, the well cycle characteristic in the profile was studied.The results indicate that the cycle development in the Triassic different structuralblocks were diversity. From northern depression head to south, the cycle quantityincreased gradually, and it was the least in the middle area of Tarim Basin. There aresimilar cycle features in the blocks, with good corresponding relationship.Finally, on the basis of the cycle which got from the GR filtering, with the targetcurve of astronomical periodic solutions for astronomical tuning, set up theastronomical tuning geological time scale, calculate the time for each geologicalprocess, and finally get the deposition rate for each cycle on well. Using thedeposition rate and the erosion thickness from cycle sequence framework, the studyindicates that the erosion thickness in Northern area is small, increases when come tothe middle part, and the erosion thickness is the biggest in the southwest part. Halahatang formation was denudated.