Accommodation space and Milankovitch orbit cycle sequence of the Paleogene stratigraphic frames in Lunpola basin based on the spectrum snalysis of the logging curve
Author(s): YIN Qing, YI Hai-sheng, XIA Guo-qing, LI Hong-wei, YAO Lei, Institute of Sedimentary Geology, Chengdu University of Technology, State Key Laboratory of Oil/Gas Reservoir Geology and Exploitation
Pages: 1288-1297
Year: 2015 Issue: 3
Journal: Progress in Geophysics
Keyword: Lunpola basin; Milankovitch cycles; spectral analysis; Fischer plots; astronomical time scale; accommodation;
Abstract: Lunpola basin is the best petroliferous basin in the world with average elevation of about 4600 meters in central Tibet Plateau,however,the paleogene stratigraphic frames in the Lunpola basin is rarely discussed.Natural gamma data of the well Xilun 2of the Lunpola Basin which possess clearly top and bottom and continuous layers have been analyzed by spectral analysis,filter analysis and Fischer plots.A highresolution astronomical timescale of each formation is established,the sequence stratigraphy of high-frequency cycles in the Niubao and Dingqinghu Formations is divided,the curve of accommodation and the high-frequency sedimentary cycle Superposition type is identified. The results revealed the production of lacustrine depositional cycles in Lunpola Basin was controlled by the Milankovitch cycles.The Dingqinghu Formation is divided into 37fourth-order sequence units and120fifth-order sequence units using eccentricity cycle curve,and the sedimentary rate is 4.75cm/ka during 14.985 Ma.The Niubao Formation is divided into 46fourth-order sequence units and 142 fifth-order sequence units using eccentricity cycle curve,and the sedimentary rate is 7.71cm/ka during 18.63 Ma.By using Fischer plots,the result indicates that both the Dingqinghu and Niubao Formations represent two long cycles of accommodation changes, which from rapidly rising-rapidly falling to slowly rising-slowly falling.The Dingqinghu Formationcan be divided into 2second-order sequence units,6third-order sequence units,37fourth-order sequence units,120fifth-order sequence units and 270sixth-order sequence units;the Niubao Formation can be divided into 2second-order sequence units,8third-order sequence units,46fourth-order sequence units,142fifth-order sequence units and 489sixth-order sequence units.The investigation provides a new effective approach to build the correlating framework of high-resolution sequence in the Lunpola basin.
Pages: 1288-1297
Year: 2015 Issue: 3
Journal: Progress in Geophysics
Keyword: Lunpola basin; Milankovitch cycles; spectral analysis; Fischer plots; astronomical time scale; accommodation;
Abstract: Lunpola basin is the best petroliferous basin in the world with average elevation of about 4600 meters in central Tibet Plateau,however,the paleogene stratigraphic frames in the Lunpola basin is rarely discussed.Natural gamma data of the well Xilun 2of the Lunpola Basin which possess clearly top and bottom and continuous layers have been analyzed by spectral analysis,filter analysis and Fischer plots.A highresolution astronomical timescale of each formation is established,the sequence stratigraphy of high-frequency cycles in the Niubao and Dingqinghu Formations is divided,the curve of accommodation and the high-frequency sedimentary cycle Superposition type is identified. The results revealed the production of lacustrine depositional cycles in Lunpola Basin was controlled by the Milankovitch cycles.The Dingqinghu Formation is divided into 37fourth-order sequence units and120fifth-order sequence units using eccentricity cycle curve,and the sedimentary rate is 4.75cm/ka during 14.985 Ma.The Niubao Formation is divided into 46fourth-order sequence units and 142 fifth-order sequence units using eccentricity cycle curve,and the sedimentary rate is 7.71cm/ka during 18.63 Ma.By using Fischer plots,the result indicates that both the Dingqinghu and Niubao Formations represent two long cycles of accommodation changes, which from rapidly rising-rapidly falling to slowly rising-slowly falling.The Dingqinghu Formationcan be divided into 2second-order sequence units,6third-order sequence units,37fourth-order sequence units,120fifth-order sequence units and 270sixth-order sequence units;the Niubao Formation can be divided into 2second-order sequence units,8third-order sequence units,46fourth-order sequence units,142fifth-order sequence units and 489sixth-order sequence units.The investigation provides a new effective approach to build the correlating framework of high-resolution sequence in the Lunpola basin.
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