浙西早寒武系大陈岭组地震液化脉电子探针分析研究
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摘要
针对地震液化脉体与臼齿构造在宏观上不易辨认的问题,利用电子探针技术对脉体和含脉体围岩做了定性和定量研究,液化脉中Si、K、Al、Mg明显高于含脉体围岩,而Ca、Sc则表现为含脉体围岩高于脉体;在地震突发振动力作用下,富水软沉积层液化泄水,塑性碳酸盐沉积物随水部分流失,使得单位面积内碳酸盐沉积含量低于围岩,Ca、Sc具有相似的化学性质,表现为脉体中Ca、Sc含量偏高;因脉体中易溶物质流失,使得难溶的Si质和炭质相对含量变大。对脉体和含脉体围岩纹层中的方解石定量研究显示,两者方解石的各元素含量几乎相同,表现出明显的同源性,表明脉体是层内物质。结果显示,地震液化脉与臼齿构造在微观特征明显不同,为事件地层的鉴别提供了新的思路。
Aiming at the difficulty in recognition of seismic liquefied veins and molar-tooth structure,qualitative and quantitative research were carried out on veins and vein-bearing carbonate rocks using electron microprobe techniques. The results show that: 1 the value of Si、 K、 Al、 Mg of the veins is significantly higher than that of the vein-bearing carbonate rocks,while the value of Ca and Sc is more abundant in the vein-bearing carbonate rocks. Ca and Sc have similar chemical properties,which are likely to be dissolved in water during the erosion process of carbonate rocks. That may be the result of water escape process. The loss of the soluble substances of veins leads to the relative increase of the insoluble Si and carbonaceous substances; 2 The quantitative research on the calcite of the veins and the vein-bearing carbonate rocks shows that the element component of the both is almost equal,which suggests obvious homology. So the veins should be the material within the stratal beds. In addition,the analysis result is evidently different from the previous study of molar-tooth structures. The veins from carbonate rocks of Dachenling Formation have the unique petrological,structural and geochemical features,so they should be interpreted to be seismic liquefied veins.
Aiming at the difficulty in recognition of seismic liquefied veins and molar-tooth structure,qualitative and quantitative research were carried out on veins and vein-bearing carbonate rocks using electron microprobe techniques. The results show that: 1 the value of Si、 K、 Al、 Mg of the veins is significantly higher than that of the vein-bearing carbonate rocks,while the value of Ca and Sc is more abundant in the vein-bearing carbonate rocks. Ca and Sc have similar chemical properties,which are likely to be dissolved in water during the erosion process of carbonate rocks. That may be the result of water escape process. The loss of the soluble substances of veins leads to the relative increase of the insoluble Si and carbonaceous substances; 2 The quantitative research on the calcite of the veins and the vein-bearing carbonate rocks shows that the element component of the both is almost equal,which suggests obvious homology. So the veins should be the material within the stratal beds. In addition,the analysis result is evidently different from the previous study of molar-tooth structures. The veins from carbonate rocks of Dachenling Formation have the unique petrological,structural and geochemical features,so they should be interpreted to be seismic liquefied veins.
引文
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[11]严兆彬,郭福生,彭花明,等.浙西寒武系大陈岭组震积岩的发现及其初步研究[J].地质学报,2005,79(6):730-736.
[12]Z B Yan,F S Guo,L J Liu.Study on C and O isotopic characteristics from Liquefied Vein Caused by Earthquake of Cambrian Dachenling Formation in the West of Zhejiang Province[C]//2012 International Conference on Earth Science and Remote Sensing,2012,156-160.
[13]F S Guo,Z B YAN,L Q Chen.Early Cambrian Seismic E-vents and Their Tectonic Significance in Western Zhejiang[J].Advancel Materials Research,2012(524-527):42-48.
[14]刘礼洁,郭福生,严兆彬.浙江桐村寒武系大陈岭组地震驱动的软沉积变形构造及地质意义[J].沉积学报,2012,30(5):795-805.
[15]旷红伟,金广春,刘燕学,等.从地球化学角度看微亮晶臼齿碳酸盐岩形成的环境条件---以吉辽地区新元古代微亮晶碳酸盐岩为例[J].天然气地球科学,2004,15(2):150-155.
[2]Helen E J,Frank R E.An ancient seismite response to Taconian far-field forces:The Cane Run Bed,Upper Ordovician(Trenton)Lexington Limestone,central Kentucky(USA)[J].Journal of Geodynamics,2004,37:487-511.
[3]汪胜国,钟建华,杨玉芳.松辽盆地古龙凹陷姚家组震积岩研究[J].新疆石油地质,2013,34(3):291-295.
[4]Pope B.M.,Pavlis G.L.,Rudman A.J.,et al.Distribution and magnitude of earthquakes recorded by the Wabash Valley seismic network[J].Transactions,American Geophysical Union,1997.46:455.
[5]Owen G.,Moretti M.,Alfaro P,et al.Recognising triggers for soft sediment deformation:Current understanding and future directions[J].Sedimentary Geology,2011.235(3-4):133-342.
[6]Su D H,Qiao X F,Sun A P,et al.Large eathquake-triggered liquefaction mounds and a carbonate sand volcano in The Mesoproterozoic Wumishan Formation,Beijing,North China[J].Geol.J.(2013)DOI:10.1002/gj.2501.
[7]乔秀夫,宋天锐,李海兵.是地震液化泄水成因,不是渗流管构造[J].科学通报,2002,47(14):1118-1120.
[8]孟祥化,葛铭,蔡国印,等.下寒武统大林子组溶解蒸发岩系旋回层序及渗流构造成因[J].科学通报,2002,47(14):1113-1117.
[9]C E Mitchell,X Chen,M S M Bergstr,et al.Definition of a global boundary stratotype for the Darriwilian Stage of the Ordovician System[J].Episodes,1997,v.20,158-166
[10]S C Peng,L E Babcok,J X Zuo,et al.Global Standard Stratotype-Section and Point(GSSP)for the Base of the Jiangshanian Stage(Cambrian:Furongian)at Duibian,Jiangshan,Zhejiang,Southeast China[J].Episodes,2012,35(4):462-477.
[11]严兆彬,郭福生,彭花明,等.浙西寒武系大陈岭组震积岩的发现及其初步研究[J].地质学报,2005,79(6):730-736.
[12]Z B Yan,F S Guo,L J Liu.Study on C and O isotopic characteristics from Liquefied Vein Caused by Earthquake of Cambrian Dachenling Formation in the West of Zhejiang Province[C]//2012 International Conference on Earth Science and Remote Sensing,2012,156-160.
[13]F S Guo,Z B YAN,L Q Chen.Early Cambrian Seismic E-vents and Their Tectonic Significance in Western Zhejiang[J].Advancel Materials Research,2012(524-527):42-48.
[14]刘礼洁,郭福生,严兆彬.浙江桐村寒武系大陈岭组地震驱动的软沉积变形构造及地质意义[J].沉积学报,2012,30(5):795-805.
[15]旷红伟,金广春,刘燕学,等.从地球化学角度看微亮晶臼齿碳酸盐岩形成的环境条件---以吉辽地区新元古代微亮晶碳酸盐岩为例[J].天然气地球科学,2004,15(2):150-155.