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白垩纪放射虫化石种类繁多,目前全球的分带对比还较困难。藏南的白垩纪放射虫硅质岩广泛分布,各时期的放射虫化石均有报道,但有待进一步的古生物学和生物地层学研究。O’Dogherty(1994)建立了一个有价值的西地中海地区白垩纪中期的放射虫分带,但将藏南赛诺曼期冲堆组的一些放射虫化石属种的时代,归入阿普特期,导致一些错误的对比结果。本文将冲堆组一块灰岩标本(80-153)的23种化石示于图版Ⅰ,它们都是西地中海地区放射虫化石的共同种或相近种,据O’Dogherty(1994)提供的这些种的时代分布,表明冲堆组的放射虫化石组合宜与西地中海地区赛诺曼阶中下部的Spica亚带对比。
Cretaceous radioactive fossils a wide range of the current global zoning comparison is more difficult. Late Cretaceous radiolarian cherts in southern Tibet are widely distributed. Radiolarian fossils have been reported in all periods, but further palaeontology and bio-stratigraphic studies are needed. O’Dogherty (1994) established a valuable mid-Cretaceous zonation zonation in the western Mediterranean, but the era of some radonated fossil species from the South Sinanian heap stack was classified as Apt Period, leading to some erroneous comparison results. In this paper, 23 fossils of a limestone specimen (80-153) from the Reactor Formation are shown in Plate I, all of which are common or proximate species of radiolarian fossils in the western Mediterranean. According to O’Dogherty (1994) The age distribution indicates that the radiolarian fossil assemblage in the heap stack should be compared with the Spica subzone of the mid-lower Sinumannian in the western Mediterranean.