陕西富平地区中奥陶统等深流沉积的特征及其地质意义.pdf

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1、第29卷第9期地质通报VO1．29．NO．92010年9月GE0LoGICALBULLETIN0FCHINASep．，2010陕西富平地区中奥陶统等深流沉积的特征及其地质意义屈红军，梅志超，李文厚，关利群，冯杨伟，范玉海QUHong-j1．11"1，MEIZhi—chao，LIWen—hou，GUANLi—qun，FENGYang—wei，FANYu—hai大陆动力学国家重点实验室／西北大学地质学系，陕西西安710069StateKeyLaboratoryofContinentMDynamics／DepartmentofGeology．NorthwestUniversity,710069．Sh

2、aonxi,China摘要：陕西富平赵老峪地区中奥陶统赵老峪组发育一套与深水碳酸盐岩重力流沉积、放射虫硅质岩、火山凝灰岩伴生的等深流沉积。根据岩性特征可以将该等深流沉积划分为砾屑等深积岩、砂屑等深积岩、粉屑等深积岩和灰泥等深积岩4种类型．识别出较完整的、由单一灰泥或粉屑或砂屑等深积岩叠置组成的4种等深积岩层序。等深流的流向从东北向西南方向。说明中奥陶世富平地区可能是秦岭北侧弧后盆地伸进浅水台地的一个北东向的深海前槽。富平赵老峪地区下奥陶统马家沟组和华北地块其他地区一样都发育浅水台地相碳酸盐岩，中奥陶统突变为深水斜坡一盆地边缘相的碳酸盐岩重力流及等深流沉积．而同期华北地块主体隆升为陆．反映了在扬

3、子板块向华北板块俯冲的背景下，秦岭北侧早古生代弧后盆地北测的陷落下沉作用。关键词：中奥陶统；赵老峪组；富平地区；等深积岩；弧后盆地中图分类号：P534．42；P512．2文献标志码：A文章编号：1671—2552(2010)09—1304—06QuHJ，MeiZC，LiWGuanLQ，FengYW，FanYH．ThecharacteristicsofMiddleOrdoviciancontourcurrentdepositsandgeologicalimplicationinFupingregion,ShaanxiProvince，China．GeologicalBulletinofChina

4、,2010,29(9)：1304--1309Abstract：InFupingZhaolaoyuregionofShaanxiProvince，MiddleOrdovicianZhaolaoyuFormationdevelopedasuiteofcontourites，whichwasassociatedwithdeepwatercarbonategravity—flow，radiolarianchertandvolcanictuf．Accordingtotheirlithologiccharac—teristics，thecontouritescanbeclassifiedintofourt

5、ypes，respectivelypsephiticcontourite，calcareniticcontourite，calcisiltiticcontourite，andcalcilutiticcontouriteFourtypesofcontouritesequenceswereidentifiedas，whicharecomposedbytheoverlyingofsub—inte-gratedsequence，singlecalcilutititesequencewithcalcisiltititeorcalcilutiticclot，singlecalcisiltiticconto

6、uritesequence，andsinglepsephiticcontouritesequence．ThecontourcurrentWasfromnortheasttosouthwest，whichsuggestedthatmiddleOrdovicianFupingregionmaybeanortheasternabyssalanteriortroughinMiddleOrdovicianepoch，developingfromarcrearbasinsonthenorthofQinlingfingeringintoshallowplateau．InfupJngZhaolaoyuIe§o

7、nLowOrdovicianMajiagonFormation．1ikeotherregionsofHuabeiblock，developedshallowplateaufaciescarbonate．ButinMiddleOrdovicianfacieschangedsuddenlyintodeepwaterslope—basinmarginfaciescarbonategravity—flow