北京西山下苇甸地区青白口系长龙山组沉积相及层序地层研究
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摘要
北京西山下苇甸地区出露良好的青白口系长龙山组,笔者通过实测野外露头剖面以及岩石薄片镜下鉴定,对该组下部沉积相及层序地层进行研究,并对沉积环境演化进行分析。识别出长龙山组下部8种岩石类型有含砾砂岩、羽状交错层理砂岩、丘状交错层理砂岩、波状层理粉砂岩、脉状层理粉砂岩、透镜状层理粉砂岩、碳质泥岩以及水平层理泥岩;并识别出辫状河道、潮坪(潮道)、潮下浅水及潮下深水等沉积相类型,建立该区辫状河—滨岸潮坪沉积模式。进而通过识别长龙山组与其下伏地层之间的区域不整合面和下切谷河道充填砂砾岩底面确定层序界面。其中,初始海泛面以每个砂体之上覆盖的细粒沉积的底面为代表,最大海泛面以厚层碳质泥岩及水平层理泥岩的底面为代表。依据这些关键层序地层界面,将该区长龙山组下部划分为3个层序,每个层序内部进一步划分为低位体系域、海侵体系域以及高位体系域。综合分析表明,京西的长龙山组发育于由燕辽裂陷槽转为华北稳定克拉通的过渡期。
The Changlongshan Formation of Qingbaikouan is well exposed in the Xiaweidian area,West Mountain of Beijing.Based on the analysis of the lower part of Changlongshan Formation and the thin sections of the sandstones examined by the optical microscope,sedimentary facies,sequence stratigraphy,and environmental evolution of the Changlongshan Formation were determined.A total number of 8 rocktypes were identified,including gravelly sandstones,Herringbone cross-bedded sandstones,hummocky cross-bedded sandstones,wavy-laminated siltstones,flaser-laminated siltstones,lenticular-laminated siltstones,carbonaceous mudstones,and horizontal-bedded mudstones.Based on the lithofacies analyses,four main sedimentary facies were recognized,including braided channel,tidal flat(tidal channel),shallow subtidal,and deep subtidal facies,and a braided channel-shoreline tidal flat depositional model was proposed.The regional unconformity between the Changlongshan Formation and its underlying strata,and the bottom of glutenite filling the incised valley were identified as sequence boundaries.The initial flooding surfaces are characterized by basal fine-grained deposits overlying on the major incised valley filled sandstones,while the maximum flooding surfaces are typified by the bases of a thick succession of the carbonaceous mudstones and horizontal-laminated mudstones.Three sequences were recognized in the lower part of the Changlongshan Formation in the Xiaweidian area,with each further subdivided into LST,TST and HST by the initial flooding surface and maximum flooding surface.The comprehensive analyses indicate that the Changlongshan Formation in western Beijing was developed during a period characterized by the transition from the Yan-Liao rifted trough stage to the North China stable craton stage.
The Changlongshan Formation of Qingbaikouan is well exposed in the Xiaweidian area,West Mountain of Beijing.Based on the analysis of the lower part of Changlongshan Formation and the thin sections of the sandstones examined by the optical microscope,sedimentary facies,sequence stratigraphy,and environmental evolution of the Changlongshan Formation were determined.A total number of 8 rocktypes were identified,including gravelly sandstones,Herringbone cross-bedded sandstones,hummocky cross-bedded sandstones,wavy-laminated siltstones,flaser-laminated siltstones,lenticular-laminated siltstones,carbonaceous mudstones,and horizontal-bedded mudstones.Based on the lithofacies analyses,four main sedimentary facies were recognized,including braided channel,tidal flat(tidal channel),shallow subtidal,and deep subtidal facies,and a braided channel-shoreline tidal flat depositional model was proposed.The regional unconformity between the Changlongshan Formation and its underlying strata,and the bottom of glutenite filling the incised valley were identified as sequence boundaries.The initial flooding surfaces are characterized by basal fine-grained deposits overlying on the major incised valley filled sandstones,while the maximum flooding surfaces are typified by the bases of a thick succession of the carbonaceous mudstones and horizontal-laminated mudstones.Three sequences were recognized in the lower part of the Changlongshan Formation in the Xiaweidian area,with each further subdivided into LST,TST and HST by the initial flooding surface and maximum flooding surface.The comprehensive analyses indicate that the Changlongshan Formation in western Beijing was developed during a period characterized by the transition from the Yan-Liao rifted trough stage to the North China stable craton stage.
引文
北京市地质矿产局.1991.北京市区域地质志.北京:地质出版社.[Beijing Bureau of Geology and Mineral Resources.1991.Regional Geology of Beijing.Beijing:Geological Publishing House]
鲍亦刚,刘振锋,王世发.2001.北京西山百年地质研究.北京:地质出版社.[Bao Y G,Liu Z F,Wang S F.2001.A Century of Geological Research in Western Beijing.Beijing:Geological Publishing House]
陈小军,罗顺社,李家华.2011.宣龙坳陷青白口系长龙山组碎屑岩地球化学特征.中国地质,38(6):1477-1478.[Chen X J,Luo SS,Li J H.2011.Clastic rock geochemical features of Changlongshan Formation in Qingbaikou System within Xuanlong Depression.Geology in China,38(6):1477-1478]
黄学光.2006.燕山中、新元古代沉积盆地构造演化.地质调查与研究,29(4):264-269.[Huang X G.2006.Tectonic evolution of the Meso-Neoproterozoic sedimentary basin in Yanshan Range.Geological Survey and Research,29(4):264-269]
刘宝珺,曾允孚.1985.岩相古地理基础和工作方法.北京:地质出版社.[Liu B J,Zeng Y L.1985.The Lithofacies Palaeogeographic Basis and Working Methods.Beijing:Geological Publishing House]
刘庆余.1990.北京西山的地质研究及其地质实习基地的历史回顾.地球科学:中国地质大学学报,15(6):697-704.[Liu Q Y.1990.The history reminiscence of the geological study and the practice training base in western Beijing.Earth Science:Journal of China University of Geosciences,15(6):697-704]
乔秀夫.1976.青白口群地层学研究.地质科学,11(3):251-252.[Qiao X F.1976.The stratigraphy research of Qingbaikou System.Chinese Journal of Geology,11(3):251-252]
曲永强,潘建国,梁利东,杨祖峰,王海龙.2012.燕辽裂陷槽中元古界不整合面性质.沉积与特提斯地质,32(2):12-13.[Qu YQ,Pan J G,Liang L D,Yang Z F,Wang H L.2012.The attributes of the Mesoproterozoic unconformities in the Yanliao rift trough.Sedimentary Geology and Tethyan Geology,32(2):12-13]
王立峰,李文宣,罗均林,胡华斌.2000.河北省怀来新元古代长龙山组沉积相研究.世界地质,19(2):138-139.[Wang L F,Li WX,Luo J L,Hu H B.2000.The study on sedimentary facies of Changlongshan Formation of Neoproterozoic Era in Huailai,Hebei.Global Geology,19(2):138-139]
王鸿祯.1985.中国古地理图集.北京:地图出版社,6-7.[Wang HZ.1985.Atlas of the Paleogeography of China.Beijing:Cartographic Publishing House,6-7]
吴因业,张天舒,张志杰,崔化娟.2010.沉积体系域类型、特征及石油地质意义.古地理学报,12(1):69-81.[Wu Y Y,Zhang T S,Zhang Z J,Cui H J.2010.Types and characteristics of depositional systems tract and its petroleum geological significance.Journal of Palaeogeography(Chinese Edition),12(1):69-81]
周洪瑞,梅冥相,罗志清,邢矿.2006.燕山地区新元古界青白口系沉积层序与地层格架研究.地学前缘,13(6):280-290.[Zhou HR,Mei M X,Luo Z Q,Xing K.2006.Sedimentary sequence and stratigraphic framework of the Neoproterozoic Qingbaikou System in the Yanshan region.Earth Science Frontiers,13(6):280-290]
van Wagoner J C,Mitchum R M,Campion K M,Rahmanian V D.1990.Siliciclastic sequence stratigraphy in well logs,cores and outcrops:Concepts for high-resolution of time and facies.AAPG Methods in Exploration Sciences,(7):1-55.
Mitchum R M,van Wagoner J C.1991.High frequency sequences and their stacking patterns:Sequence stratigraphic evidence of high frequency eustatic cycles.Sedimentary Geology,70(2-4):131-160.
鲍亦刚,刘振锋,王世发.2001.北京西山百年地质研究.北京:地质出版社.[Bao Y G,Liu Z F,Wang S F.2001.A Century of Geological Research in Western Beijing.Beijing:Geological Publishing House]
陈小军,罗顺社,李家华.2011.宣龙坳陷青白口系长龙山组碎屑岩地球化学特征.中国地质,38(6):1477-1478.[Chen X J,Luo SS,Li J H.2011.Clastic rock geochemical features of Changlongshan Formation in Qingbaikou System within Xuanlong Depression.Geology in China,38(6):1477-1478]
黄学光.2006.燕山中、新元古代沉积盆地构造演化.地质调查与研究,29(4):264-269.[Huang X G.2006.Tectonic evolution of the Meso-Neoproterozoic sedimentary basin in Yanshan Range.Geological Survey and Research,29(4):264-269]
刘宝珺,曾允孚.1985.岩相古地理基础和工作方法.北京:地质出版社.[Liu B J,Zeng Y L.1985.The Lithofacies Palaeogeographic Basis and Working Methods.Beijing:Geological Publishing House]
刘庆余.1990.北京西山的地质研究及其地质实习基地的历史回顾.地球科学:中国地质大学学报,15(6):697-704.[Liu Q Y.1990.The history reminiscence of the geological study and the practice training base in western Beijing.Earth Science:Journal of China University of Geosciences,15(6):697-704]
乔秀夫.1976.青白口群地层学研究.地质科学,11(3):251-252.[Qiao X F.1976.The stratigraphy research of Qingbaikou System.Chinese Journal of Geology,11(3):251-252]
曲永强,潘建国,梁利东,杨祖峰,王海龙.2012.燕辽裂陷槽中元古界不整合面性质.沉积与特提斯地质,32(2):12-13.[Qu YQ,Pan J G,Liang L D,Yang Z F,Wang H L.2012.The attributes of the Mesoproterozoic unconformities in the Yanliao rift trough.Sedimentary Geology and Tethyan Geology,32(2):12-13]
王立峰,李文宣,罗均林,胡华斌.2000.河北省怀来新元古代长龙山组沉积相研究.世界地质,19(2):138-139.[Wang L F,Li WX,Luo J L,Hu H B.2000.The study on sedimentary facies of Changlongshan Formation of Neoproterozoic Era in Huailai,Hebei.Global Geology,19(2):138-139]
王鸿祯.1985.中国古地理图集.北京:地图出版社,6-7.[Wang HZ.1985.Atlas of the Paleogeography of China.Beijing:Cartographic Publishing House,6-7]
吴因业,张天舒,张志杰,崔化娟.2010.沉积体系域类型、特征及石油地质意义.古地理学报,12(1):69-81.[Wu Y Y,Zhang T S,Zhang Z J,Cui H J.2010.Types and characteristics of depositional systems tract and its petroleum geological significance.Journal of Palaeogeography(Chinese Edition),12(1):69-81]
周洪瑞,梅冥相,罗志清,邢矿.2006.燕山地区新元古界青白口系沉积层序与地层格架研究.地学前缘,13(6):280-290.[Zhou HR,Mei M X,Luo Z Q,Xing K.2006.Sedimentary sequence and stratigraphic framework of the Neoproterozoic Qingbaikou System in the Yanshan region.Earth Science Frontiers,13(6):280-290]
van Wagoner J C,Mitchum R M,Campion K M,Rahmanian V D.1990.Siliciclastic sequence stratigraphy in well logs,cores and outcrops:Concepts for high-resolution of time and facies.AAPG Methods in Exploration Sciences,(7):1-55.
Mitchum R M,van Wagoner J C.1991.High frequency sequences and their stacking patterns:Sequence stratigraphic evidence of high frequency eustatic cycles.Sedimentary Geology,70(2-4):131-160.