Variations of calcareous nannofossils of cobalt-rich crusts and geological records at the Eocene-OIigocene transition in western Pacific seamounts  

作　　者：ZHANG HaiSheng HU Ji ZHAO Jun HAN ZhengBing YU PeiSong WU GuangHai LEI Ji Jiang LU Bing Irina A PULYAEVA 

机构地区：[1]Second Institute of Oceanography,State Oceanic Administration [2]Key Laboratory of Marine Ecosystem and Biogeochemistry,State Oceanic Administration [3]State Scientific Centre Yuzhmorgeologia

出　　处：《Science China Earth Sciences》2015年第5期784-794,共11页中国科学（地球科学英文版）

基　　金：supported by the National Natural Science Foundation of China(Grant Nos.41076072 and 40676025)

摘　　要：Two records of the crust laminae from the Marcus-Wake Seamounts and the Magellan Seamount were biostratigraphically studied. Based on biological imprints of the calcareous nannofossils, the geological ages of the two records were determined, with CM1D03 from the Marcus-Wake Seamounts being of late Paleocene to Pleistocene and CM3D06 from the Magellan Seamount of Late Cretaceous （more than 70.0 Ma）. There are the obvious temporal-spatial differences in the initial formation period and enrichment characteristics of the cobalt-rich crusts of the two seamount chains and differences in the combination and distribution of microfossils in the inner crust layers between the seamounts. These differences are due to the adaptabilities of oceanic species in different environments. Ecological research was carried out in terms of population size of the calcareous nannofossi｜s preserved in the crustal layers to discern the relation of the geological events at the Eocene-Oligocene （E/O） tran- sition. The results show the transitions and recombination of species in the biotic community during the E/O transition obvi- ously corresponded to 25 mm depth in the CM1D03 crust and 58 mm depth in the CM3D06 crust. The changes in biological species and the formation of particular ecological structures indicate the adaptive response of the paleo-biological community in the western Pacific Ocean to the global cold-climate events and the close correlation between the formation of the crust and the global climate change.Two records of the crust laminae from the Marcus-Wake Seamounts and the Magellan Seamount were biostratigraphically studied. Based on biological imprints of the calcareous nannofossils, the geological ages of the two records were determined, with CM1D03 from the Marcus-Wake Seamounts being of late Paleocene to Pleistocene and CM3D06 from the Magellan Seamount of Late Cretaceous(more than 70.0 Ma). There are the obvious temporal-spatial differences in the initial formation period and enrichment characteristics of the cobalt-rich crusts of the two seamount chains and differences in the combination and distribution of microfossils in the inner crust layers between the seamounts. These differences are due to the adaptabilities of oceanic species in different environments. Ecological research was carried out in terms of population size of the calcareous nannofossils preserved in the crustal layers to discern the relation of the geological events at the Eocene-Oligocene(E/O) transition. The results show the transitions and recombination of species in the biotic community during the E/O transition obviously corresponded to 25 mm depth in the CM1D03 crust and 58 mm depth in the CM3D06 crust. The changes in biological species and the formation of particular ecological structures indicate the adaptive response of the paleo-biological community in the western Pacific Ocean to the global cold-climate events and the close correlation between the formation of the crust and the global climate change.

关 键 词：Marcus-Wake Seamounts Magellan Seamount cobalt-rich crust NANNOFOSSIL E/O geological event 

分 类 号：Q914.2[天文地球—古生物学与地层学] P736.2[生物学—古生物学]