北非地区Ghadames盆地早古生代岩相古地理演化特征OACSTPCD

The Ghadames Basin has become one of the significant basins for overseas exploration and project investment in China.Accurate understanding of the early Paleozoic sedimentary system and lithofacies palaeogeographic characteristics is the basis for further exploration and the key to establish the early tectonic-sedimentary evolution history of the basin.Based on the comprehensive analysis of core,seismic and logging data in Ghadames Basin,combined with the restoration of palaeogeomorphology,the sedimentary system and lithofacies palaeogeographic characteristics are discussed.The results show four types of depositional sys-tems in the early Paleozoic of Ghadames Basin:alluvial fan,braided river,braided river delta and shallow marine.In the early and middle Cambrian,the Avalon terrane drifted toward the Baltic plate,the Proto-Te-thys Ocean initially expanded,and the active continental margin was formed.During this period,the whole basin was dominated by continental deposits.During the Cambrian-Ordovician,the platform uplift and de-pression pattern was initially formed owing to the Caledonian movement.Large-scale denudation occurred in the western and northern parts of the Ghadames Basin,and large-scale glacier deposits were developed to form glacial moraine reservoirs.In the Early and Middle Silurian,the Palaeo-Tethys Ocean continued to ex-pand,the sea level rose,and a extensive transgression occurred in the northern part.Shallow marine sedi-mentary environment predominated in the area during this time,and hot shale and mudstone were widely de-veloped which are important source rocks and cap rocks in the region.In the Devonian period,the Hercy-nian movement uplifted the region as a whole,and the sea area in the basin was reduced and replaced main-ly by continental sediments.On this basis,the establishment of the marine-continental transition sedimentary model under the early Paleozoic Tethys Ocean evolution background in the Ghadames Basin is established,which can provide a reference for the next exploration work in the study area.