苏北盆地阜宁组钙质超微化石由来初探

A PRELIMINARY STUDY ON THE ORIGIN OF CALCAREOUS NANNOFOSSILS DISCOVERED IN THE FUNING FORMATION FROM THE NORTHERN JIANGSU BASIN

对苏北盆地 4个钻孔 3 0 0余块岩心样品进行了分析 ,在阜宁组的 8块样品中发现了钙质超微化石 ,计 3属 1种及 3个比较种。化石属种单调 ,保存较差 ,受到严重的溶蚀或增生。结合这些种类的分布时代和产出层位 ,很难排除苏北盆地阜宁组钙质超微化石再沉积的属性。

Calcareous nannofossils discovered in the Funing Formation from the Northern Jiangsu Basin are first reported in this paper. More than 300 core samples from 4 drilling holes are analysed, and calcareous nannofossils are discovered only in 8 core samples. Besides calcareous dinoflagellates Thoracosphaera cf. operculata, they include, 1 species and 3 conformis species from 3 genera, they namely, Quadrum gartneri, Polycostella cf. senaria, Hexalithus cf. hexalithus, and Hexalithus cf. magharensis. These fossils are rare in both number of genera and number of species. They are poor preserved, some of them are severely corroded or have overgrowth of calcite. The origin of these fossils and their distribution features in various tectonic depressions are studied. That those calcareous nannofossils are all reworked is judged by their preservation conditions, their geological times and the strata where they are discovered.