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1、安徽巢北早三叠世南陵湖灰岩中的灰涌构造及其成因意义迟元林 钟建华 周瑶琪 陈书平 王绍兰 朱光有 孙国忠 摘 要 安徽巢北早三叠世南陵湖组的灰岩中发育了一种非常特殊的构造,我们将其称为“灰涌”(limeblow),因为它们在形态、结构及成因上非常类似于由地震喷沙形成的砂涌(sandflow)。这种灰涌形态上呈蘑菇状或伞状,由涌道、涌盘及涌口三部分组成,但后者有时可以不发育。涌道呈直立圆柱状,高30~50cm,直径0.2~2cm,但常因灰泥的流动而“愈合”;涌道之上为涌盘,大部分呈铁饼形,直径在5~40cm,高1~8cm,多数在3~5cm。部分中心有一凹坑(涌
2、口),凹坑直径在1~3cm,深度一般不超过1cm。涌盘内部具有纹层结构,由黄褐色泥灰纹层和浅灰色泥晶灰岩纹层交互所形成的。研究表明,前者系沉积所形成,而后者系地震喷涌所形成。结合模拟实验推测灰涌的成因可能与地震有关。通过对1号灰涌层的研究发现,有的灰涌是由二十次左右(5个幕)地震形成的。 关键词 灰涌;地震;巢北 中图法分类号 P584ThelimeblowintheNanlinghulimestoneofearlyTriassicperiodinnorthChaohu,Anhui:ItsgenesisandsignificanceChiYuanlin(
3、ChangchunScienceandTechnologyUniversity,Changchun,130026)ZhongJianhuaZhouYaoqiChenShupingWangShaolanZhuGuangyouandSunGuozhong(ResourceandEnvironmentInstitute,ChinaUniversityofPetroleum,Dongying,257062) Abstract AkindofunusualsedimentarystructuredevelopedintheNanlinghulimestoneofear
4、lyTriassicperiodinnorthChaohu,Anhuiprovince,whichiscalledas“limeblow”,becauseitresemblesthesandblowinshape,structureandgenesis.Thesandblowwasformedbyearthquakes.ThelimeblowinnorthChaohuhastheappearancelikemushroomorumbralleandconsistsofthreeparts:blowchannel(duct),blowdishandblowmout
5、h,butthelatterdoesnotoftenemerge.Theblowchannelislikeacylinder,with30~50cmheightand0.2~2cmindiameter,nevertheless,theblowchanneloftenappearstobeclose.Overtheblowchannelthereisablowdish,mostofwhicharelikediscus,being5~40cmindiameterand1~8cminheight.Partsofblowdishhaveoneortwotothreebl
6、owmouthesintheircentersorneartheircenters.Theblowmouthisamong1~3cmindiametersandnotmorethanonecentimeterindepth.Theblowdishhaslaminaestructures,whichwasformedbyalternationofyellowishbrownargillaceouslimestonelaminaeandlightgreymicritelimestonelaminae.Basedonthestudies,theargillaceous
7、limestonelaminaeisthoughttobeformedbynormaldeposition,nevertheless,themicritelimestonelaminaebyeffusionformedbyearthquakes.Thestudyoflime-blow-layerⅠhassuggestedthatithadbeenformedbyabout20timesearthquakes(5earthquakeepisodes). Keywords Limeblow,Earthquake,Chaobei 地震导致沉积物流体化,同时形成异
8、常孔隙压力,使地下松散砂