西太平洋富钴结壳中钙质超微化石和分子化石研究

Calcareous nannofossil stratigraphy and molecular fossils in the Co-rich ferromanganese crust from the Western Pacific

本文对西太平洋麦哲伦海山CM3D06富钴结壳进行了钙质超微化石生物地层学研究,发现结壳中有代表白垩纪(晚期)、古新世(晚期)、始新世(早、中、晚期)、中新世(中期)、上新世(晚期)和更新世等各时代的标准钙质超微化石,表明结壳的形成始于白垩纪(晚期);在富钴结壳中检出正构烷烃、类异戊二烯烃、甾烷类等众多分子化石,分子化石组合特征指数、主峰碳、ΣC-23/C+24、CPI、Pr/Ph、Pr/nC17、Ph/nC18和nC31/nC17显示有机质生物母源主要为海洋浮游植物、浮游动物和底栖非光合作用的菌类,而甾烷类的C29、C28和C27含量分布的变化则说明生物种群具有快速演变的特征。此外,还探讨了CM3D06结壳中Pr/Ph和有机碳同位素组成变化与结壳生长过程中的海洋环境演化的关联程度。

Calcareous nannofossils biostratigraphy was studied on a sample of Co-rich ferromanganese crust,CM3D06,from the Magellanseamounts in the Western Pacific.The occurrences of classic calcareous nannofossils,which can typically represent the eras from the late Cretaceous to the Pleistocene,indicate that the crust has started forming in the Late Cretaceous.A suit of molecular fossils,including n-alkane,isoprenoid hydrocarbon and sterane,were detected in the Co-rich ferromanganese crust.Features of the molecular characteristics index,MH,ΣC23^-/C24^＋、CPI、Pr/Ph、Pr/nC17、Ph/nC18和 nC31/nC17 suggest the organic source in the crust mainly from marine phytoplankton、zooplankton and benthic non-photosynthetic fungus.The proportion patterns of C29、C28and C27 of the sterol component show the rapid evolution of the organism population.The relationship between the growing of the crust and the changes in the oceanic environment was also addressed through the organic carbon isotope and Pr/Ph analyses on each layer of the crust.