摘要
目前,大陆架科学钻探CSDP-2井是南黄海盆地中部隆起上的唯一深钻,是揭示南黄海中—古生界海相地层时代,恢复其沉积环境和构造运动的基准井。本文针对该井开展岩心描述并进行薄片观察,结合测井数据、古生物化石等资料,将志留系—石炭系划分为下志留统高家边组、侯家塘组、坟头组,上泥盆统五通组,下石炭统高骊山组、和州组,上石炭统黄龙组、船山组。其中,志留系沉积了一套浅海陆棚相的细碎屑岩,沉积物以浅海—滨海相砂泥岩为主;泥盆系五通组同样为碎屑岩沉积,稳定的石英砂岩和紫红色泥岩并存,下部为潮坪相,上部则为三角洲相;而石炭系发育台坪、泻湖、颗粒滩等碳酸盐岩台地亚相,岩性以生屑灰岩和泥晶灰岩为主。区域地层对比表明,南黄海盆地中—古生界海相地层是下扬子区由陆域向海域的延伸,其志留系—石炭系岩性序列与下扬子陆域基本一致。
The Well CSDP-2of continental shelf drilling program is the only deep well in the central uplift of South Yellow Sea at present,so it has reference value for revealing the Mesozoic-Paleozoic marine stratigraphic epoch and restoring the depositional environment and tectonic movement.Based on the core description and thin-section examination of the rocks,combined with logs and fossils,the Silurian-Carboniferous strata are divided into Lower Silurian Gaojiabian,Houjiatang-and Fentou Formations;Upper Devonian Wutong Formation;Lower Carboniferous Gaolishan-and Hezhou Formations;Upper Carboniferous Huanglong and Chuanshan Formations.Among them,a set of shallow-sea shelf facies with fine clastic rocks were deposited in Silurian.The Devonian Wutong is characterized by the coexistence of stable quartz sandstone and purple red mudstone,with lower tidal flat facies and upper delta facies.Carboniferous is dominated by bioclastic limestone and muddy limestone,mainly developed in platform,lagoon and grain-beach subfacies of carbonate platform.The regional stratigraphic correlation shows that the lithologic sequence of Silurian-Carboniferous is basically consistent with that of the Lower Yangtze land area,indicating that the Mesozoic-Paleozoic marine strata in the South Yellow Sea basin were the extension of the Lower Yangtze platform from land to sea.