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鄂尔多斯盆地南部下奥陶统马家沟组沉积特征

作    者:辛勇光,周进高,邓红婴
单    位:中国石油杭州地质研究院
基金项目:
摘    要:
依据鄂尔多斯盆地南部早奥陶世古构造、古地理、古水动力以及古气候背景, 结合单井、野外露头沉积相分析等认为,秦岭海槽和中央古隆起的存在和演化控制盆地南部马家沟组沉积特征及演化。(1)平面上根据中央古隆起的障壁作用将其分为两大沉积区,西南区和东北区。西南区发育盆地—斜坡—台地边缘相,东北区为障壁潟湖沉积环境;(2)东北区马家沟组由“三云三灰”六段组成,马一、马三、马五段为白云岩、石膏和石盐组成的蒸发岩系,马二、马四、马六段为石灰岩夹白云岩的碳酸盐岩序列,在纵向上构成蒸发岩与碳酸盐岩间互的旋回性沉积。在此基础上进一步建立了马家沟组障壁潟湖沉积模式,该模式具有两个主要特征院(1)中央古隆起作为障壁控制秦岭海与潟湖之间的海水沟通;(2)依据海平面升降旋回将该模式动态地分为三个阶段,即与海侵期相对应的以石灰岩沉积为主的障壁潟湖沉积阶段(阶段Ⅰ)、与海退期相对应的以石灰岩夹蒸发岩沉积为主的障壁咸化潟湖沉积阶段(阶段Ⅱ)和与低海平面期对应的以膏盐岩沉积 为主的障壁膏盐湖沉积阶段(阶段Ⅲ)。
关键词:鄂尔多斯盆地;马家沟组;秦岭海槽;中央古隆起;沉积特征;沉积模式

Sedimentary Features of Lower Ordovician Majiagou Formation in the Southern Part of Ordos Basin

Author's Name: Xin Yongguang,Zhou Jingao,Deng Hongyin
Institution: PetroChina Hangzhou Institute of Geology
Abstract:
Based on predecessor's researches of paleostructures,paleogeography, paleohydrodynamics and paleoclimate as well as the sedimentary facies of single wells and outcrops, authors discovered that Qinling Trough and the Central Uplift controlled the sedimentary features and evolution in the southern part of Ordos Basin during Early Ordovician period.The southern part of Ordos Basin is divided into two main sedimentary areas, the south western and the northeastern areas, owing to the barrier role of the Central Uplift. A basin,a slope and a platform margin developed in the southwestern and a lagoon in the northeastern. Lower Ordovician Majiagou Formation is composed of six members (abbreviated as Ma1 to Ma6), in which Ma1, Ma3 and Ma5 are evaporite including dolomite, anhydrite and halite and Ma2, Ma4, and Ma6 are limestone with dolomite. A new model, the Majiagou barrier-lagoon sedimentary model, is further put forward in order to interpret the sedimentary features of Majiagou Formation. This model includes two main characters. the one is that the Central Uplift plays an extreme role in the exchange of seawater between the lagoon and Qinling sea as a barrier; and the other is that the model is divided into three dynamical phases on the basis of an integrated cycle: the limestone in wide Barrier-lagoon during trans gression to high sea level (phaseⅠ), the mixed limestone/evaporite succession in concentrated lagoon during regression (phaseⅡ), and the anhydrite and halite in barrier lagoon during low sea level( phaseⅢ).
Keywords: Ordos Basin; Ordovician; Qinling Trough; Central Uplift; Sedimentary features; Sedimentary model
投稿时间:2010-03-02  
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