根据古郯庐断裂两侧地块分布特征,渤海及周边地区早古生代具有南北高、中间低的古地理格局,以清水碳酸盐沉积为主.基于钻井岩心、薄片及露头观察,总结了典型沉积相标志,认为区内发育近岸潮坪相、局限台地相和开阔台地相等3类沉积相,台内洼地、灰泥丘、台内滩、潟湖、台坪等5类沉积亚相,以及9类沉积微相.在寒武系和奥陶系沉积相划分与精细对比的基础上,刻画了渤海及周边地区早古生代4个典型沉积时期的岩相古地理:受二级海平面升降、构造沉降和古地形的影响,早寒武世靠近(水下)古隆起区发育近岸潮坪相,中部局限台地—开阔台地发育;中寒武世厚层鲕粒滩广泛发育;晚寒武世—早奥陶世广泛发育局限台地白云岩坪、石灰岩坪;中奥陶世广泛发育开阔台地相台内洼地泥晶灰岩沉积.

According to the strata of the blocks on both sides of the ancient Tanlu fault, it is concluded that the Bohai Sea and its surrounding areas has a high-north, high-south, and low-middle paleotopography pattern in the Early Paleozoic, where clear-water carbonate mainly deposited. Based on the observation of drilling cores, thin sections and outcrops, typical sedimentary facies indicators are summarized. It is considered that there are three types of sedimentary facies in the area, i.e. nearshore tidal flat facies, limited platform facies and open platform facies, five types of sedimentary subfacies such as intra-platform depression, micrite mound, intra-platform shoal, lagoon, and platform flat, and nine types of sedimentary microfacies. Based on the identification and fine correlation of sedimentary facies of Cambrian and Ordovician, the lithofacies palaeogeography of four typical periods in the Bohai Sea and its surrounding areas is reconstructed. Controlled by sea level rise and fall, tectonic subsidence, and paleotopography, coastal tidal flats developed along paleouplifts and platforms developed widely in Lower Cambrian, oolitic shoals with large thickness developed in Middle Cambrian, dolomite and lime flats developed from Upper Cambrian to Lower Ordovician, and micrite limestone mainly developed in intra-platform depressions of open platform in Middle Ordovician. The results would be helpful to the study of hydrocarbon genesis and reservoir formation in the Lower Paleozoic, which is a favorable target layer for large or medium gas fields.