南海北部海相中生界发育的微体化石证据

MZ-1-1钻井首次在南海北部珠江口盆地揭示了中生界,获得了可确定地层时代和沉积环境的孢粉和放射虫化石。克拉梭粉(Classopollis)和桫椤孢(Cyathdites)含量占优势的化石组合被发现于井深2 187~2 388 m井段,表明其属于中侏罗世;1 725~1 887 m层段的硅质岩包含以Caneta hsui、Loopus primitivus、Dibolachras sp.cf.D.apletopora等为代表分子的晚侏罗世-早白垩世放射虫动物群。微体化石分析结果表明,南海北部珠江口盆地被首次揭露的前新生代地层中存在着海相的侏罗系和白垩系。中侏罗世克拉梭粉和桫椤孢孢粉组合反映的是热带-亚热带沿海地区植被,滨海沼泽环境发育。晚侏罗世-早白垩世南海北部的海洋沉积环境发生了海水由浅到深的重大变化,形成了深海环境。

MICROFOSSIL EVIDENCE FOR DEVELOPMENT OF MARINE MESOZOIC IN THE NORTH OF SOUTH CHINA SEA

Microfossils, including spores, pollen and radiolarian, were found in the Mesozoic which was first encountered in Well MZ-1-1 in the north of the South China Sea. The geological time of the spore and pollen assemblage dominated by Classopollis and Cyathdites is given as the middle Jurassic, which was recovered from the interval 2 187~2 388 m of Well MZ-1-1. The siliceous rocks occurring in the interval 1 725~1 887 m of this well contains late Jurassic to early Cretaceous radiolarian assemblages, mainly including Caneta hsui,Loopus primitivus,Dibolachras sp. cf. D. apletopora. The results of microfossil analysis have demonstrated the occurrence of marine Jurassic and Cretaceous in the north of the South China Sea. The spore and pollen assemblage dominated by Classopollis and Cyathdites reflects the tropical to subtropical coastal vegetation and coastal marshland that developed in the north of the South China Sea during the middle Jurassic. The deposition environment changed greatly and the deep water reigned in this region during the late Jurassic to early Cretaceous.