柴北缘侏罗纪煤显微组分与泥炭沉积速率
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摘要
为了揭示侏罗纪柴达木盆地北缘泥炭聚集特征,对高泉露天矿7号煤层进行了煤岩学和频谱分析研究。结果表明,7号煤层有机组分变化大,镜质组平均含量为49.9%,以基质镜质体(平均含量19.1%)和结构镜质体(平均含量12.1%)为主;惰质组平均含量为41.1%,以半丝质体(平均含量19.3%)和碎屑惰质体(平均含量12.3%)为主;类脂组平均含量为2.8%,以孢子体(平均含量2.5%)为主。频谱分析识别出7号煤层内0.68 m、1.00 m和1.82 m三个有效厚度周期,其周期比值与泥炭地发育时期的岁差和黄赤交角周期比值相近,认为煤层V/I变化受到米兰科维奇天文周期中岁差和斜率的影响。利用MTM多窗谱分析重建了3个厚度周期的频谱信号,计算出7号煤层沉积时间约为371 ka,泥炭沉积速率约为0.2 mm/a,由于聚煤期泥炭的侵蚀和氧化等原因,该速率低于全新世全球低海拔相近纬度带的泥炭最高聚集速率(0.5~1.6 mm/a)。
To reveal peat accumulation characteristics of Jurassic coal seams in northern Qaidam Basin,coal petrology of the main coal seams and spectral analysis of coal seam No. 7 in Gaoquan open-pit mine were investigated. Results show that the volume of organic macerals varies considerably(120 samples),the average content of vitrinine and inertinite are 49. 9% and 41. 1% respectively,the former mainly comprises collodetrinite( ave. 19. 1%) and telinite( ave. 12. 1%),and the later primarily comprises semifusinite( ave. 19. 3%) and inertodetrinite( ave. 12. 3%). Sporinite( ave. 2. 5%) is the major component of liptinite( ave. 2. 8%). Three effective thickness periods of 0. 68 m,1. 00 m and 1. 82 m in coal No. 7 were recognized through the spectrum analysis,and the ratio of them is similar to that of the peat development period precession and obliquity cycle. As a result,the variation of coal vitrinite and inertinite is affected by the precession and slop of Milankovitch astronomical cycle. The spectrum signal of three thickness periods were reconstructed by the Multi Taper Method( MTM),from which the total deposition time( approximately 371 ka) and the average peat sedimentation rate( ave. 0. 2 mm/a)of coal No. 7 was obtained. The peat sedimentation rate of coal No. 7 is lower than the highest rate( about 0. 5 ~ 1. 6 mm/a) of Holocene deposited in lower altitude area with similar latitude.
To reveal peat accumulation characteristics of Jurassic coal seams in northern Qaidam Basin,coal petrology of the main coal seams and spectral analysis of coal seam No. 7 in Gaoquan open-pit mine were investigated. Results show that the volume of organic macerals varies considerably(120 samples),the average content of vitrinine and inertinite are 49. 9% and 41. 1% respectively,the former mainly comprises collodetrinite( ave. 19. 1%) and telinite( ave. 12. 1%),and the later primarily comprises semifusinite( ave. 19. 3%) and inertodetrinite( ave. 12. 3%). Sporinite( ave. 2. 5%) is the major component of liptinite( ave. 2. 8%). Three effective thickness periods of 0. 68 m,1. 00 m and 1. 82 m in coal No. 7 were recognized through the spectrum analysis,and the ratio of them is similar to that of the peat development period precession and obliquity cycle. As a result,the variation of coal vitrinite and inertinite is affected by the precession and slop of Milankovitch astronomical cycle. The spectrum signal of three thickness periods were reconstructed by the Multi Taper Method( MTM),from which the total deposition time( approximately 371 ka) and the average peat sedimentation rate( ave. 0. 2 mm/a)of coal No. 7 was obtained. The peat sedimentation rate of coal No. 7 is lower than the highest rate( about 0. 5 ~ 1. 6 mm/a) of Holocene deposited in lower altitude area with similar latitude.
引文
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[18]秦勇,王文峰,李壮福,等.海侵作用影响下的高分辨煤相序列及其古泥炭沼泽发育模式:以山西北部安太堡上石炭统太原组11号煤层为例[J].地质学报,2008,82(2):234-246.Qin Yong,Wand Wenfeng,Li Zhuangfu,et al.High resolution coal facies sequence and peat paleo-bog pattern during the transgression[J].Acta Geological Sinica,2008,82(2):234-246.
[19]许福美,黄文辉,吴传始,等.顶峰山矿区39号煤层的煤岩学与煤相特征[J].煤炭学报,2010,35(4):623-628.Xu Fumei,Huang Wenhui,Wu Chuanshi,et al.Coal petrology and facies of coal seam No.39 from Dingfengshan mining district,Longyong coalfield,Fujian Province,China[J].Journal of China Coal Society,2010,35(4):623-628.
[20]Whelan R J.The ecology of fire[M].London:Cambridge University Press,1995.
[21]Berger A,Loutre M F,Laskar J.Stability of the astronomical frequencies over the earth’s history for paleoclimate studies[J].Science,1992,255:560-566.
[22]斯塔赫.斯塔赫煤岩学[M].杨起,译.北京:煤炭工业出版社,1990.
[23]Diessel C,Boyd R,Wadsworth J,et al.On balanced and unbalanced accommodation/peat accumulation ratios in the Cretaceous coals from Gates Formation,Western Canada,and their sequence-stratigraphic significance[J].International Journal of Coal Geology,2000,43:143-186.
[2]汤良杰,金之钧,张明利,等.柴达木盆地构造古地理分析[J].地学前缘,2000,7(4):421-429.Tang liangjie,Jin Zhijun,Zhang Mingli,et al.An analysis on tectonic paleogeography of the Qaidam Bsain,NW China[J].Earth Science Frontiers,2000,7(4):421-429.
[3]黄曼,邵龙义,鲁静,等.柴北缘老高泉地区侏罗纪含煤岩系层序地层特征[J].煤炭学报,2007,32(5):485-489.Huang Man,Shao Longyi,Lu Jing,et al.The sequence stratigraphy of the Middle Jurassic coal measures in the Laogaoquan region of the Northern Qaidam basin[J].Journal of China Coal Society,2007,32(5):485-489.
[4]鲁静,邵龙义,刘天绩,等.柴北缘鱼卡地区侏罗纪煤系层序地层与聚煤作用[J].煤田地质与勘探,2007,35(1):1-6.Lu Jing,Shao Longyi,Liu Tianji,et al.A sequence stratigraphy analysis of the Jurassic coal measures in Yuqia region of Northern Qaidam basin[J].Coal Geology&Exploration,2007,35(1):1-6.
[5]鲁静,邵龙义,鞠崎,等.柴北缘大煤沟矿区侏罗纪煤系层序地层及其煤岩变化特征[J].煤田地质与勘探,2009,37(4):9-14.Lu Jing,Shao Longyi,Ju Qi,et al.Coal petrography variation in the sequence stratigraphic frame of the Jurassic coal measures of Dameigou mine area in Northern Qaidam basin[J].Coal Geology&Exploration,2009,37(4):9-14.
[6]袁学旭,郭英海,赵志刚,等.以米氏旋回为标尺进行测井层序划分对比:以东海西湖凹陷古近-新近系地层为例[J].中国矿业大学学报,2013,42(5):766-773.Yuan Xuexu,Guo Yinghai,Zhao Zhigang,et al.Comparison of well log sequence stratigraphic classification and correlation using Milankovitch cycles:Paleogene Neogene strata of Xihu sag in East China Sea[J].Journal of China University of Mining&Technology,2013,42(5):766-773.
[7]付文钊,余继峰,杨锋杰,等.测井记录中米氏旋回信息提取及其沉积学意义——以济阳坳陷区为例[J].中国矿业大学学报,2013,42(6):1025-1032.Fu Wenzhao,Yu Jifeng,Yang Fengjie,et al.Feature extraction of Milankovitch cycle in well logs and its sedimentological significance:a case study of Jiyang depression zone[J].Journal of China University of Mining&Technology,2013,42(6):1025-1032.
[8]Large J D,Jones F T,Briggs J,et al.Orbital tuning and correlation of 1.7 m.y.of continuous carbon storage in an early Miocene peatland[J].Geology,2004,32:873-876.
[9]Wang Hao,Shao Longyi,Large J D,et al.Constraints on carbon accumulation rate and net primary production in Lopinggian(Late Permian)tropical peatland in SW China[J].Palaeogeography,Palaeoclimatology,Palaeoecology,2011,300:152-157.
[10]刘桂侠,杨永泰.柴达木盆地北部基底岩性对上部地层构造演化及储集条件的影响[J].天然气工业,2003,23(2):40-43.Liu Guixia,Yang Yongtai.Influence of basement lithology on the structural evolution and reservoir conditions of overlying strata in the Northern Qaidam basin[J].Natural Gas Industry,2003,23(2):40-43.
[11]张泓.中国西北侏罗纪含煤地层与聚煤规律[M].北京:地质出版社,1998.
[12]Ghil M,Allen M R,Dettinger M D,et al.Advanced spectral methods for climatic time series[J].Reviews of Geophysics,2002,40:1-41.
[13]Bourg D M.Excell scientific and engineering cookbook[M].Sebastopol,USA.O’Reilly Media,Inc.,2006.
[14]韩德馨.中国煤岩学[M].徐州:中国矿业大学出版社,1996.
[15]中国煤田地质总局.中国煤岩学图鉴[M].徐州:中国矿业大学出版社,1996.
[16]Scott A C,Glasspool I J.Observations and experiments on the origin and formation of inertinite group macerals[J].International Journal of Coal Geology,2007,70:53-66.
[17]Diessel F K C.The stratigraphic distribution of inertinite[J].International Journal of Coal Geology,2010,81:251-268.
[18]秦勇,王文峰,李壮福,等.海侵作用影响下的高分辨煤相序列及其古泥炭沼泽发育模式:以山西北部安太堡上石炭统太原组11号煤层为例[J].地质学报,2008,82(2):234-246.Qin Yong,Wand Wenfeng,Li Zhuangfu,et al.High resolution coal facies sequence and peat paleo-bog pattern during the transgression[J].Acta Geological Sinica,2008,82(2):234-246.
[19]许福美,黄文辉,吴传始,等.顶峰山矿区39号煤层的煤岩学与煤相特征[J].煤炭学报,2010,35(4):623-628.Xu Fumei,Huang Wenhui,Wu Chuanshi,et al.Coal petrology and facies of coal seam No.39 from Dingfengshan mining district,Longyong coalfield,Fujian Province,China[J].Journal of China Coal Society,2010,35(4):623-628.
[20]Whelan R J.The ecology of fire[M].London:Cambridge University Press,1995.
[21]Berger A,Loutre M F,Laskar J.Stability of the astronomical frequencies over the earth’s history for paleoclimate studies[J].Science,1992,255:560-566.
[22]斯塔赫.斯塔赫煤岩学[M].杨起,译.北京:煤炭工业出版社,1990.
[23]Diessel C,Boyd R,Wadsworth J,et al.On balanced and unbalanced accommodation/peat accumulation ratios in the Cretaceous coals from Gates Formation,Western Canada,and their sequence-stratigraphic significance[J].International Journal of Coal Geology,2000,43:143-186.