陕南奥陶系宝塔组灰岩网状裂缝成因.pdf

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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(