陕西富平地区中奥陶统等深流沉积的特征及其地质意义  

The characteristics of Middle Ordovician contour current deposits and geological implication in Fuping region,Shaanxi Province,China

作　　者：屈红军[1] 梅志超[1] 李文厚[1] 关利群[1] 冯杨伟[1] 范玉海[1] 

机构地区：[1]大陆动力学国家重点实验室/西北大学地质学系,陕西西安710069

出　　处：《地质通报》2010年第9期1304-1309,共6页Geological Bulletin of China

基　　金：国家科技重大专项课题(编号:2008ZX05025-006)资助

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-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。In Fuping Zhaolaoyu region of Shaanxi Province,Middle Ordovician Zhaolaoyu Formation developed a suite of contourites,which was associated with deep water carbonate gravity-flow,radiolarian chert and volcanic tuff.According to their lithologic characteristics,the contourites can be classified into four types,respectively psephitic contourite,calcarenitic contourite,calcisiltitic contourite,and calcilutitic contourite.Four types of contourite sequences were identified as,which are composed by the overlying of sub-integrated sequence,single calcilutitite sequence with calcisiltitite or calcilutitic clot,single calcisiltitic contourite sequence,and single psephitic contourite sequence.The contour current was from northeast to southwest,which suggested that middle Ordovician Fuping region may be a northeastern abyssal anterior trough in Middle Ordovician epoch,developing from arc rear basins on the north of Qinling fingering into shallow plateau.In Fuping Zhaolaoyu region,Low Ordovician Majiagou Formation,like other regions of Huabei block,developed shallow plateau facies carbonate.But in Middle Ordovician facies changed suddenly into deep water slopebasin margin facies carbonate gravity-flow and contourite,meanwhile Huabei block uplifted and became landmass,which indicated that the northern part of Eopaleozoic arc rear basins on the north of Qinling were sinking on the background of Yangtze block underthrusting toward Huabei block.

关 键 词：中奥陶统 赵老峪组 富平地区 等深积岩 弧后盆地 

分 类 号：P534.42[天文地球—古生物学与地层学] P512.2[天文地球—地质学]