河北宽城地区洪水庄组岩石特征及沉积环境

Petrology and sedimentary environments of the Hongshuizhuang Formation in the Kuancheng region, Hebei

关键词:  洪水庄组  蓟县系  岩石特征  沉积环境  河北宽城

Key words:  Hongshuizhuang Formation  Jixianian  petrological feature  sedimentary environment  Kuancheng in Hebei

摘要:

河北宽城地区蓟县系洪水庄组主要为一套碳酸盐岩潮坪相沉积,厚度101.66m,下部由灰黑色页岩与中层-薄层状泥质白云岩互层组成,向上泥质白云岩不发育,以灰黑色页岩为主,含黄铁矿结核;上部由含粉砂泥质页状白云岩与含砂白云岩及含锰泥晶白云岩组成。该套地层岩石类型主要为白云岩和页岩,白云岩可进一步划分为硅质白云岩、(含粉砂)泥质(砂质)白云岩、(含锰)泥晶白云岩,页岩则由硅质页岩和暗色页岩组成。根据岩石学特征及沉积构造等相标志,将研究区洪水庄组划分为潮上带、潮间带(上、下)和潮下带(上、下)3种沉积环境。洪水庄组有机质富集,以大量藻类体和腐泥质碎屑为主,为很好的烃源岩,与上覆蓟县系铁岭组、青白口系下马岭组构成有利的生储盖配置,具有良好的油气勘探潜力。

Abstract:

The carbonate tidal-flat deposits in the Jixianian Hongshuizhuang Formation in the Kuancheng region, Hebei are made up of dominant grayish black shales with pyrite nodules and medium-to thin-bedded muddy dolostones in the lower part, and the silt-bearing muddy laminated dolostones, sand-bearing dolostones and manganese-bearing micritic dolostones in the upper part of the measured section in this study. This succession of strata consists dominantly of dolostones and shales. The former may be subdivided into siliceous dolostones,(siltbearing) muddy (sandy) dolostones, and (manganese-bearing) micritic dolostones while the latter comprise siliceous shales and dark shales. Three types of sedimentary environments are identified, including supratidal, intertidal (upper and lower) and subtidal (upper and lower) zones on the basis of petrological features and sedimentary structures. The Hongshuizhuang Formation oppears as organic matler-rich (algae and sapropelic fragments) excellent source rocks, and constitutes the favourable source-reservoir-seal disposition together with the overlying Jixianian Tieling Formation and Qingbaikouan Xiamaling Formation, which must be considered highly prospective for the petroleum exploration.