DOI: 10.1016/j.palaeo.2014.10.011
论文题名: Palaeoenvironmental turnover across the Cenomanian-Turonian transition in Oued Bahloul, Tunisia: Foraminifera and geochemical proxies
作者: Reolid M. ; Sánchez-Quiñónez C.A. ; Alegret L. ; Molina E.
刊名: Palaeogeography, Palaeoclimatology, Palaeoecology
ISSN: 0031-0182
出版年: 2015
卷: 417 起始页码: 491
结束页码: 510
语种: 英语
英文关键词: Cretaceous
; Ecostratigraphy
; Foraminifera
; OAE2
; Redox conditions
; Trophic conditions
英文摘要: The integrated analysis of foraminiferal assemblages, geochemical proxies, and stable isotopes in the Oued Bahloul section (Tunisia) allowed us to reconstruct the environmental turnover across the Cenomanian-Turonian boundary. An increase in palaeoproductivity proxies (P/Ti, U/Al, Sr/Al) and in δ13C values, and a decrease in foraminiferal diversity and δ18O values mark the beginning of the Oceanic Anoxic Event 2 (OAE2) at the Rotalipora cushmani and Whiteinella archaeocretacea biozones boundary. Eutrophic conditions at the seafloor and in the water column are evidenced by high proportions of buliminids and the replacement of planktic oligotrophic specialist Rotalipora by eutrophic opportunist Hedbergella. The enrichment in organic matter and redox sensitive elements, together with the abundance of low-oxygen tolerant benthic foraminifera, indicate dysoxic conditions in the deep-water column and at the seafloor (higher Uaut than Moaut). Among planktic foraminifera, deep- and intermediate-dwellers disappear (Rotalipora and Globigerinelloides), and surface-dwellers proliferate (Hedbergella). The persistency of the poorly oxygenated conditions during the W. archaeocretacea Biozone locally produced euxinic conditions where MoEF and Moaut reach high values, diversity presents minimum values, and benthic foraminifera temporarily disappear. The maximum percentage of heterohelicids indicates a stratified water column with a well-developed oxygen minimum zone. Improved oxygen conditions returned in the upper part of the W. archaeocretacea Biozone and Helvetoglobotruncana helvetica Biozone, with a slow recovery of foraminiferal assemblages, decrease in eutrophic genera (Heterohelix) and increase in mesotrophic genera (Whiteinella). A gradual increase in δ18O values suggests decreased temperatures in surface waters. The OAE2 has been attributed to global temperature changes and palaeoceanographic reorganization. The poor mixing of surface and deep waters and enhanced primary productivity related to global warming - associated with increasing continental weathering and nutrient runoff - may have favored the eutrophication of the ocean and the expansion of the oxygen minimum zone. © 2014 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/69120
Appears in Collections: 过去全球变化的重建
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作者单位: Departamento de Geología, Universidad de Jaén, Campus Las Lagunillas sn, Jaén, Spain; Departamento de Geociencias, Universidad Nacional de Colombia, Carrera 30, N 45-03, Bogotá, Colombia; Departamento de Ciencias de la Tierra e IUCA, Universidad de Zaragoza, Pedro Cerbuna 12, Zaragoza, Spain
Recommended Citation:
Reolid M.,Sánchez-Quiñónez C.A.,Alegret L.,et al. Palaeoenvironmental turnover across the Cenomanian-Turonian transition in Oued Bahloul, Tunisia: Foraminifera and geochemical proxies[J]. Palaeogeography, Palaeoclimatology, Palaeoecology,2015-01-01,417