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《陕南奥陶系宝塔组灰岩网状裂缝成因.pdf》由会员上传分享,免费在线阅读,更多相关内容在行业资料-天天文库。
1、第37卷第4期地球科学~—中国地质大学学报VO1.37NO.42012年7月EarthScienceJournalofChinaUniversityofGeosciencesJuly20l2doi:10.3799/dqkx.2012.093陕南奥陶系宝塔组灰岩网状裂缝成因王安东,周瑶琪,仲岩磊,段竟,王子阳,张振凯1.中IN石油大学地球科学与技术学院,山东青岛2665552.中国石化胜利油田采油工艺研究院,山东东营257000摘要:为了研究奥陶系宝塔组灰岩网状裂缝的形成原因,利用古生物鉴定、野外露头对比及镜下薄片观察等方法
2、进行分析.古生物以头足类、三叶虫、介形类和棘皮类为主,偶见腕足类,未见藻类.裂缝延伸到生物化石时停止,贯穿地层顶底面但未穿透相邻地层,平面呈瘤状、龟裂纹和s曲线等,锯齿状缝合线切穿裂缝.镜下发现灰质基块内散布着泥质团块,泥质团块通过微裂隙互相连通或连通主裂缝,泥质内夹的灰质碎屑长轴沿裂缝展布,新鲜剖面灰质基块与泥质裂缝无明显界限.提出宝塔期扬子板块处于稳定克拉通沉积环境,网状裂缝是在较深水缓慢沉积的低能开阔台地环境下,由于化学分异作用灰质质点聚集、压实作用胶态粘土矿物脱水收缩、泥质随水排出时充填裂缝而形成的,为非构造成因裂
3、缝.关键词:宝塔组灰岩;网状裂缝;泥质含量;收缩裂缝;沉积学;构造.中图分类号:P588.2文章编号:1。。0—2383(2012)O4—0843-08收稿日期:2012-03—05CattsesofReticularCracksinOrdovicianBaotaFormationLimestoneinSouthernShaanxiWANGAn-dong,ZHOUYa~qi,ZHONGYan-lei,DUANJing,WANGZi—yang,ZHANGZhen-kai1.SchooloyGeosciences,ChinaU
4、niversityotPetroleum,Qingdao266555,China2.ShengliOilProductionResearchInstituteofSinoPec,Dongying257000,ChinaAbstract:ThroughPaleontologyappraisal,outcropcontrastandundermirrorsliceobservationmethods,thispaperanalyzesthecausesofreticularcracks,BaotaFormationlimest
5、one,Ordovician.Paleontologyismainlyofcephalopods(Sinoceraschinensis),trilobites,ostracodaandechinodermata(Metacrinus),occasionallyincludingBraehiopoda,noalga.Theformationisdi—videdintotWOunits:thelowerpurpleandtheupperceladon.Thecrack,stretchingfromthesurfaceandbo
6、ttomwithoutpenetratingtheadjacentformation,stopswhenextendedtOthebiologicalfossils.Thepatternsareofnodular,tortoiseshellandtheScurve,etc;dentatesuturelinescutthroughthecrack.Microscopicstudyshowsthatshalemassspreadsinthelimymatrices,withshalemassconnectedeachother
7、orconnectedtOthemaincrackbythemicrocrack,themacroaxisofthelimychippinginshaleexhibitedalongthecrack.Therearenoobviousboundariesbetweenlimymatricesandshalecrackinfreshprofile.ItiSconcludedthattheYangtzeplate,Baotaperiodwasinastablecratonsedimentaryenvironment,andre
8、ticularcracksformedduetOlimyparticlesbychemicaldifferentiationandclaymineralsyneresisincompressionswithshalefillingcrackswithno-flowperiodsinadeepwater(
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