甘肃合作早三叠世钙质超微化石的发现

Discovery of Early Triassic Calcareous Nannofossils in Hezuo Area, Gansu

在甘肃合作地区早三叠世地层中发现了钙质超微化石,共3属3种,本文描述了2个新属3个新种。它们位于斜坡脚—盆地的深海沉积环境中,与早三叠世早期双壳类Claraia共生,其下部有具早三叠世面貌的孢粉组合,经能谱成分分析,这些化石为钙质。这些钙质超微化石的发现使钙质超微化石的时代分布的可靠记录延至早三叠世,为今后中生代地层的划分对比及钙质超微化石的演化研究提供了较好的资料。文中依据所发现的钙质超微化石对沉积环境进行了初步分析,为该区地质研究提供了证据。

Three Early Triassic calcareous nannofossil species of 3 genera were discovered in Hezuo Area, Gansu Province, of which 3 new species and 3 new genera are described here.The fossils were found in the deep-sea slope base-basin environment together with Early Triassic bivalve claraia. The underlying beds yield an Early Triassic palynomorph assemblage. Calcareous composition of these nannofossils are detected by energy spectrum analysis. discovery of these fossils extends the stratigraphic record of calcareous nannofossils (sensu stricto) back to Early Triassic, and provides potential for future subdivision and correlation of Early Mesozoic strata as well as the evolutionary history of nannofossils. This paper also makes a preliminary analysis of the depositienal environment of nannofossil bearing strata.