鄂尔多斯盆地奥陶系马家沟组中组合沉积微相特征及演化

The characteristic and evolution of sedimentary microfacies in the middle Ordovician assemblages in the Ordos Basin

鄂尔多斯盆地奥陶系中组合发育了一套较典型的白云岩储层,在钻井岩芯分析、薄片鉴定和室内微相等综合分析的基础上,对中组合的沉积微相类型、展布规律及其演化特征进行了研究,其结果表明:在中央古隆起东侧奥陶系中组合主要有开阔台地和局限台地2种沉积相,潮坪、泻湖、点滩、礁(滩)间4种亚相,其中潮坪包含潮上泥云坪、潮间灰云坪,潮下灰坪等9个微相类型,泻湖主要为膏盐微相,点滩主要为生屑灰岩微相,礁(滩)间主要为灰岩微相。在马五沉积时期在大的海退背景之下存在着马五5-马五6,马五7-马五8,马五9-马五10三个次一级的海进-海退过程,在此研究基础上我们提出中央古隆起-潮上云坪-潮间灰云坪-膏岩洼地(泻湖)的沉积相模式解释空间上的岩相组合。

A set of typical dolomite reservoir developed in the middle Ordovician assemblages in the Ordos Basin .The authors have done some researches on evolution characteristics and types of sedimentary microfacies ,which are based on core analysis ,identifying under the microscope and comprehensive analysis indoors .There are two kinds of sedimentary facies four intrafacies and several microfacies in the eastern margin of central paleo‐uplift in the middle Ordovician assemblages .During the deposition of the fifth Majiagou period under the background of marine regression there existed Ma55‐Ma56 ,Ma57‐Ma58 ,Ma59‐Ma510 three concussive transgression‐regression process .The authors established a mode of sedimentary facies on the basis of petrological combination .The sedimentary facies are as follows ：supratidal doloflat face ,intertidal limestone‐doloflat and gypsum rock depression （lagoon） .