Feature extraction of Milankovitch cycle in well logs and its sedimentological significance:a case study of Jiyang depression zone
Author(s): FU Wen-zhao, YU Ji-feng, YANG Feng-jie, LI Qing, LIU Hua, WANG Yu-lin, College of Geological Sciences and Engineering, Shandong University of Science and Technology, Shandong Provincial Key Laboratory of Depositional Mineralization &Sedimentary Minerals, Shengli Petroleum Administrative Bureau
Pages: 1025-1032
Year: 2013 Issue: 6
Journal: Journal of China University of Mining & Technology
Keyword: Jiyang depression; thickness of Milankovitch cyclothems; Early Paleozoic; Late Paleozoic; Mesozoic;
Abstract: Milankovitch cycle is the manifestation of Milankovitch effect in the stratigraphic record.Its time property is an effective means to divide and constrast the high-resolution strata.In order to reveal the differences of Milankovitch information preserved among different stratigraphic units,enrich stratigraphic theory,especially cyclostratigraphic theory,Milankovitch features were extracted by means of the Extreme Mode method of one-dimensional Continuous Wavelet Transform from related strata based on the GR well logging data of 38wells in Jiyang Depression Zone,and the thickness of the cyclothems recognized corresponding to the precession,obliquity and eccentricity was calculated respectively and their fluctuation was also analyzed.The results show that,in the study area,there widely exists Milankovitch information in several stratigraphic intervals.Among them,the thickness of the precession cyclothem varies in ranges of 3.4—17.1m,8.6—19.0mand 7—11min Early Paleozoic(∈-O),Late Paleozoic(C-P)and Cenozoic(E-N)correspondingly.And among them,13m,14m and 10mcycles are the principal ones;the thickness of the obliquity cyclothem,in the same way,7.2—27.8m,19.5—39.2m and 14—2 6m,with 27m,26m and 21mas principal cycles while eccentricities are 20.3—64.6m,37.2—75.1m and 40—60m,and 60m,74mand 51mbeing principal ones.The thickness of Milankovitch cyclothem in Mesozoic varies in ranges of 3.2—21.4m,6.2—42.8m and 15.4—108.6m,corresponding to precession,obliquity,and eccentricity respectively,with no obvious principal cycle.A conclusion can be drawn that the fluctuation of the thickness of Milankovitch cyclothem tends to strengthen with the aging of the geological intervals from Cenozoic(E-N),Late Paleozoic(C-P)to Early Paleozoic(∈-O),that is,the stability of Milankovitch cycle information preserved in the older strata is deteriorated more by the following geological events.The strongest fluctuation of the thickness of Milankovitch cyclothem in Mesozoic was probably resulted from the stronger sedimentary environment differentiation caused by the active tectonics.Furthermore,the accumulation rate was calculated and explained for different geological intervals in terms of the thickness of principal cyclethom.
Pages: 1025-1032
Year: 2013 Issue: 6
Journal: Journal of China University of Mining & Technology
Keyword: Jiyang depression; thickness of Milankovitch cyclothems; Early Paleozoic; Late Paleozoic; Mesozoic;
Abstract: Milankovitch cycle is the manifestation of Milankovitch effect in the stratigraphic record.Its time property is an effective means to divide and constrast the high-resolution strata.In order to reveal the differences of Milankovitch information preserved among different stratigraphic units,enrich stratigraphic theory,especially cyclostratigraphic theory,Milankovitch features were extracted by means of the Extreme Mode method of one-dimensional Continuous Wavelet Transform from related strata based on the GR well logging data of 38wells in Jiyang Depression Zone,and the thickness of the cyclothems recognized corresponding to the precession,obliquity and eccentricity was calculated respectively and their fluctuation was also analyzed.The results show that,in the study area,there widely exists Milankovitch information in several stratigraphic intervals.Among them,the thickness of the precession cyclothem varies in ranges of 3.4—17.1m,8.6—19.0mand 7—11min Early Paleozoic(∈-O),Late Paleozoic(C-P)and Cenozoic(E-N)correspondingly.And among them,13m,14m and 10mcycles are the principal ones;the thickness of the obliquity cyclothem,in the same way,7.2—27.8m,19.5—39.2m and 14—2 6m,with 27m,26m and 21mas principal cycles while eccentricities are 20.3—64.6m,37.2—75.1m and 40—60m,and 60m,74mand 51mbeing principal ones.The thickness of Milankovitch cyclothem in Mesozoic varies in ranges of 3.2—21.4m,6.2—42.8m and 15.4—108.6m,corresponding to precession,obliquity,and eccentricity respectively,with no obvious principal cycle.A conclusion can be drawn that the fluctuation of the thickness of Milankovitch cyclothem tends to strengthen with the aging of the geological intervals from Cenozoic(E-N),Late Paleozoic(C-P)to Early Paleozoic(∈-O),that is,the stability of Milankovitch cycle information preserved in the older strata is deteriorated more by the following geological events.The strongest fluctuation of the thickness of Milankovitch cyclothem in Mesozoic was probably resulted from the stronger sedimentary environment differentiation caused by the active tectonics.Furthermore,the accumulation rate was calculated and explained for different geological intervals in terms of the thickness of principal cyclethom.
Related Articles