西太平洋海山富钴结壳分子化石和超微化石记录:年代划分和古生态环境演变  

MOLECULAR FOSSIL AND NANNOFOSSIL RECORDS IN A Co-RICH CRUST OF WEST PACIFIC SEAMOUNTS:IMPLICATION FOR STRATIGRAPHIC DIVISION AND PALEOECOLOGY AND PALEOENVIRONMENT

作　　者：赵军[1] 张海生[1] 于培松[1] 武光海[1] 卢冰[1] Pulyaeva I A 

机构地区：[1]国家海洋局海洋生态系统与生物地球化学重点实验室,国家海洋局第二海洋研究所 [2]State Scientific Centre Yuzhmorgeologia,Gelendzhik 353461,Russia

出　　处：《海洋地质与第四纪地质》2014年第2期95-103,共9页Marine Geology & Quaternary Geology

基　　金：国家自然科学基金项目(41076072;40676061;40676025)

摘　　要：分析了西太平洋海山CM1D03富钴结壳中超微化石生物地层学记录,结合钙质微浮游生物印痕,对结壳进行了地质年代的划分,其年代为晚古新世—早始新世(54~51Ma)、中始新世(45~40Ma)、中新世—上新世(22~2.4Ma)、上新世—更新世(3.6~1.2Ma)。利用气相色谱、气相色谱-质谱联用检测了结壳中的正构烷烃、类异戊二烯、甾烷等分子化石,探讨结壳生长过程中的生源构成、沉积环境以及古生态演替特征。结果表明,结壳中氯仿沥青"A"/有机碳(TOC)比值为10.51%~21.74%,具有明显的烃类运移特征。正构烷烃的轻/重烃比值(ΣC-23/ΣC+24)为0.74~1.47,碳优势指数(CPI)为0.80~1.45,碳稳定同位素(δ13 C)为-24.00‰^-25.48‰,指示有机质主要来源于海洋表层水体的浮游植物。研究还表明,有机质物源,C27、C28、C29甾烷的丰度变化,TOC保存及δ13 C等均与结壳生长所处海洋环境、全球气候和南极底流的结构变化有关。Calcareous nannofossils in CM1D03 Co-rich crust of west Pacific Seamounts were analyzed to esi- mate the stratigraphic ages. The results showed that the lower layer was formed in the late Paleocene-early Eocene （54-51 Ma）, whereas the porous middle layer was formed in the middle Eocene （45-40 Ma） and the upper layer was in the Miocene-Plioeene （22-2.4 Ma） and the Pliocene-Pleistocene （3.6-1.2 Ma）. The molecular fossils, including chloroform bitumen ＂A＂, n-alkanes, isoprenoids, steranes, in the Co-rich crust were measured using gas chromatography and gas chromatography - mass spectrum. The source com- position, depositional environment and palaeoecological community succession in the Co-rich crust during its growth have been discussed by analyzing the characteristics of these fine molecules （C2r, C28, and C29 steranes） and their molecular indices （∑C23/∑C＋, CPI and Pr/Ph） with consideration of the variation in organic carbon （TOC） content and its stable isotope compositions （313C） records. The results showed that chloroform bitumen ＂A＂/TOC （＂A＂/C） ratio was 10.51% -21.74%, Showing significant hydrocarbon transport pattern. The ratio of ∑C23/∑C24＋ for n-alkanes was 0. 7441.47,the CPI was 0. 80-1.45, and the value of 313C was --24.00%--25.48%0, indicating that organic matter in the Co-rich crust mainly ori- gined from phytoplankton. The results also indicated that the source of organic matter, C27, C2a, and C29 steranes distribution variation, TOC preservation and δ13C were related to changes in marine environment, global climate and Antarctic Bottom Water during the formation of Co-rich crust.

关 键 词：富钴结壳 超微化石 分子化石 古生态环境演化 西太平洋海山 

分 类 号：P736.4[天文地球—海洋地质]