柴北缘全吉地区晚震旦世冰川沉积特征及地质意义
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摘要
通过对柴达木盆地北缘全吉山、石灰沟等野外剖面详细的勘察及实测,对新元古代全吉群红铁沟组冰川沉积事件进行研究,分析冰成岩发育特征,揭示各类冰川沉积现象的形成机制,建立冰成岩沉积模式,探讨冰川事件对柴北缘地区地层划分与板块对比的重要意义。结果表明:柴达木盆地北缘全吉地区红铁沟组发育新元古代冰川沉积事件,冰成岩发育位置与正常潮坪沉积一致;该地层序列中保留了冰底碛、消融碛以及冰海沉积物等不同的沉积物类型;该套冰成岩厚度横向变化大,可能为与弧后扩张有关的盆地伸展阶段的斜坡相沉积;红铁沟组下伏黑土坡组顶、底各存在一个区域不整合面,柴北缘地区新元古代末期至少发育两期大规模构造运动,研究区各剖面中黑土坡组、红铁沟组及皱节山组不同程度的剥蚀是新元古代末期柴北缘洋盆向北俯冲造成的挤压-剥蚀以及弧后伸展导致的盆地再次沉降—接受沉积转换的直接体现;红铁沟组冰成岩为震旦纪全球性冰川事件——Gaskiers冰期的产物,可与华北南缘罗圈组及塔里木汉格尔乔克组冰成岩层对比,认为塔里木、柴达木等地块在晚震旦世亲华北。
Based on the detailed investigation of field profiles in Quanjishan and Shihuigou in the northern margin of Qaidam Basin, a study of glacial events in Hongtiegou Formation of Quanji group was presented. The characteristics of glacial diagenesis were analyzed, the formation mechanism of various glacial deposition phenomena was revealed, the glacial diagenetic sedimentary model was established, and the significance of glacial events for stratigraphic division and plate correlation in the north margin of Qaidam Basin was discussed. The results show that Hongtiegou Formation experienced Neoproterozoic glaciation in Quanji area in the northern margin of Qaidam Basin, and the location of glacial diagenesis was consistent with that of normal tidal flat deposits. Its stratigraphic sequence retains glacial ground moraine, ablation moraine and proglacial tidal deposit. The formation thickness is characterized by great horizontal variations, and this glacial deposit may be the product of slop which formed under the background of basin extension during back-arc spreading. Furthermore, two unconformities are recognized on top and underneath Heitupo Formation, which represent two tectonic movements during Neoproterozoic. Moreover, the denudation of the Heitupo Formation, Hongtiegou Formation and Zhoujieshan Formation in the profiles of the study area is the direct reflection of compression-denudation caused by the northward subduction of the oceanic basin in the northern margin of the Qaidam Basin in the late Neoproterozoic era and the re-subsidence caused by the back-arc basin extension. This glacial deposit of Hongtiegou Formation was the product of Gaskiers glaciation during the global glacial period in Sinian. It can make a contrast with Luoquan Formation in southern margin of North China and Hangerqiaok Formation glacial event in Tarim. It is believed that the Tarim and Qaidam blocks are related to the North China plate in the late Sinian.
Based on the detailed investigation of field profiles in Quanjishan and Shihuigou in the northern margin of Qaidam Basin, a study of glacial events in Hongtiegou Formation of Quanji group was presented. The characteristics of glacial diagenesis were analyzed, the formation mechanism of various glacial deposition phenomena was revealed, the glacial diagenetic sedimentary model was established, and the significance of glacial events for stratigraphic division and plate correlation in the north margin of Qaidam Basin was discussed. The results show that Hongtiegou Formation experienced Neoproterozoic glaciation in Quanji area in the northern margin of Qaidam Basin, and the location of glacial diagenesis was consistent with that of normal tidal flat deposits. Its stratigraphic sequence retains glacial ground moraine, ablation moraine and proglacial tidal deposit. The formation thickness is characterized by great horizontal variations, and this glacial deposit may be the product of slop which formed under the background of basin extension during back-arc spreading. Furthermore, two unconformities are recognized on top and underneath Heitupo Formation, which represent two tectonic movements during Neoproterozoic. Moreover, the denudation of the Heitupo Formation, Hongtiegou Formation and Zhoujieshan Formation in the profiles of the study area is the direct reflection of compression-denudation caused by the northward subduction of the oceanic basin in the northern margin of the Qaidam Basin in the late Neoproterozoic era and the re-subsidence caused by the back-arc basin extension. This glacial deposit of Hongtiegou Formation was the product of Gaskiers glaciation during the global glacial period in Sinian. It can make a contrast with Luoquan Formation in southern margin of North China and Hangerqiaok Formation glacial event in Tarim. It is believed that the Tarim and Qaidam blocks are related to the North China plate in the late Sinian.
引文
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[18] 陈世悦,孙娇鹏,刘文平,等.青海大煤沟新元古代冰碛岩的发现及地质意义[J].地层学杂志,2015,39(1):81-88.CHEN Shiyue,SUN Jiaopeng,LIU Wenping,et al.The discovery and geological significance of the Neoproterozoic moraine rocks in the Dali gully,Qinghai[J].Journal of Stratigraphy,2015,39(1):81-88.
[19] EYLES N.‘Zipper-rift’:a tectonic model for Neoproterozoic glaciations during the breakup of Rodinia after 750 Ma[J].Earth Science Reviews,2004,65(1):1-73.
[20] 青海地质矿产局,托素湖幅1:20万区域地质调查报告[R].青海:青海省地质局,1978:1-124.
[21] 青海地质矿产局,怀头他拉幅1:20万区域地质调查报告[R].青海:青海省地质局,1980:1-126.
[22] 彭善池.迎接寒武系全球年代地层的新划分——2004年版“国际地层表”述评[J].地层学杂志,2005,29(2):171-177.PENG Shanchi.Towards a new global subdivision of the cambrian system:a review of the 2004 edition of the international stratigraphic table[J].Journal of Stratigraphy,2005,29(2):171-177.
[23] 李燕平,麦克威廉斯M,谭承泽.柴达木地体震旦系全吉群的古地磁研究[J].新疆地质,1988(2):38-43.LI Yanping,MCWILLIAMS M,TAN Chengze.The paleomagnetic study of the quanji group (Sinian) of the Chaidam Terrane[J].Xinjiang Geology,1988(2):38-43.
[24] 许志琴,杨经绥,吴才来,等.柴达木北缘超高压变质带形成与折返的时限及机制[J].地质学报,2003,77(2):163-176.XU Zhiqin,YANG Jingsui,WU Cailai,et al.Timing and machanism of formation and exhumation of the Qaidam Ultra-pressure metamorphic belt[J].Acta Geologica Sinica,2003,77(2):163-176.
[25] 赵祥生,张录易,邹湘华,等.西北地区震旦纪冰碛层及其地层意义[M].天津:天津科学技术出版,1980:214-230.
[2] KIRSCHVINK J L.Late proterozoic low-latitude global glaciation:the snowball earth[M].Cambridge:Cambrian University Press,1992:51-52.
[3] HOFFMAN P F,KAUFMAN A J,HAlVERSON G P,et al.Neoproterozoic snowball earth[J].Science,1999,281(5381):1342-1346.
[4] CONDON D.U-Pb Ages from the Neoproterozoic Doushantuo Formation,China[J].Science,2005,308(5718):95-98.
[5] 张启锐,储雪蕾.南华系建系问题探讨[J].地层学杂志,2007,31(3):222-228.ZHANG Qirui,CHU Xuelei.Problems in defining the NanhuaPeriod[J].Journal of Stratigraphy,2007,31(3):222-228.
[6] 高振家.关于震旦纪冰成岩的几个问题讨论[J].新疆地质,1983(1):85-94.GAO Zhenjia.Discussion about some problems of glacigenic rocks of Simian,China[J].Xinjiang Geology,1983(1):85-94.
[7] 孙娇鹏,陈世悦,彭渊,等.柴达木东北部晚石炭世盆山格局研究[J].中国石油大学学报(自然科学版),2017,41(4):10-17.SUN Jiaopeng,CHEN Shiyue,PENG Yuan,et al.Late Carboniferous mountain-basin framework of Northeastern Qaidam area[J].Journal of China University of Petroleum(Edition of Natural Science),2017,41(4):10-17.
[8] 杨超,陈清华,王冠民,等.柴达木地区晚古生代沉积构造演化[J].中国石油大学学报(自然科学版),2010,34(5):38-43,49.YANG Chao,CHEN Qinghua,WANG Guanmin,et al.Sedimentary and tectonic evolution of Qaidam areas in Late Paleozoic[J].Journal of China University of Petroleum(Edition of Natural Science),2010,34(5):38-43,49.
[9] 王云山.青海全吉山红铁沟冰碛层的确定[J].西北地质,1977(4):36-39,54,15.WANG Yunshan.Identify of moraine layer in Hongtiegou Quanji Mountain,Qinghai province[J].Northwestern Geology,1977(4):36-39,54,15.
[10] 王勋.柴达木盆地北缘全吉群年代格架与全吉地块前寒武纪构造属性[D].北京:中国地质大学(北京),2015.WANG Xun.Research on geochonological framework of the Quanji Group and Precambrian tectonic affinity of the Quanji massif,north Qaidam[D].Beijing:China University of Geosciences(Beijing),2015.
[11] 王惠初.柴达木盆地北缘早古生代碰撞造山及岩浆作用[D].北京:中国地质大学(北京),2006.WANG Huichu.Early Paleozoic collisional orogeny and magmatism on northern margin of the Qaidam basin[D].Beijing:China University of Geosciences(Beijing),2006.
[12] 青海省地质矿产局.青海省区域地质志[M].北京:地质出版社,1991:6-28.
[13] 孙崇仁.青海省岩石地层[M].武汉:中国地质大学出版社,1997:14-101.
[14] 王云山,庄庆兴,史从彦,等.柴达木盆地北缘的全吉群[M].天津:天津科学技术出版,1980:214-230.
[15] SCHOEMAN F R,THORNTON J A.Sedimentary environments and facies[J].Earth Science Reviews,1987,24(3):233-233.
[16] BOULTON G S,DEYNOUX M.Sedimentation in glacial environments and the identification of tills and tillites in ancient sedimentary sequences[J].Precambrian Research,1985,15(3):397-422.
[17] 李吉均.论冰川擦痕[J].冰川冻土,1982,4(1):29-34.LI Jijun.On glacial striation[J].Journal of Glaciology and Geocryology,1982,4(1):29-34.
[18] 陈世悦,孙娇鹏,刘文平,等.青海大煤沟新元古代冰碛岩的发现及地质意义[J].地层学杂志,2015,39(1):81-88.CHEN Shiyue,SUN Jiaopeng,LIU Wenping,et al.The discovery and geological significance of the Neoproterozoic moraine rocks in the Dali gully,Qinghai[J].Journal of Stratigraphy,2015,39(1):81-88.
[19] EYLES N.‘Zipper-rift’:a tectonic model for Neoproterozoic glaciations during the breakup of Rodinia after 750 Ma[J].Earth Science Reviews,2004,65(1):1-73.
[20] 青海地质矿产局,托素湖幅1:20万区域地质调查报告[R].青海:青海省地质局,1978:1-124.
[21] 青海地质矿产局,怀头他拉幅1:20万区域地质调查报告[R].青海:青海省地质局,1980:1-126.
[22] 彭善池.迎接寒武系全球年代地层的新划分——2004年版“国际地层表”述评[J].地层学杂志,2005,29(2):171-177.PENG Shanchi.Towards a new global subdivision of the cambrian system:a review of the 2004 edition of the international stratigraphic table[J].Journal of Stratigraphy,2005,29(2):171-177.
[23] 李燕平,麦克威廉斯M,谭承泽.柴达木地体震旦系全吉群的古地磁研究[J].新疆地质,1988(2):38-43.LI Yanping,MCWILLIAMS M,TAN Chengze.The paleomagnetic study of the quanji group (Sinian) of the Chaidam Terrane[J].Xinjiang Geology,1988(2):38-43.
[24] 许志琴,杨经绥,吴才来,等.柴达木北缘超高压变质带形成与折返的时限及机制[J].地质学报,2003,77(2):163-176.XU Zhiqin,YANG Jingsui,WU Cailai,et al.Timing and machanism of formation and exhumation of the Qaidam Ultra-pressure metamorphic belt[J].Acta Geologica Sinica,2003,77(2):163-176.
[25] 赵祥生,张录易,邹湘华,等.西北地区震旦纪冰碛层及其地层意义[M].天津:天津科学技术出版,1980:214-230.
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