DOI: 10.1016/j.quascirev.2014.11.014
Scopus记录号: 2-s2.0-84919940731
论文题名: Marine productivity leads organic matter preservation in sapropel S1: Palynological evidence from a core east of the Nile River outflow
作者: van Helmond N.A.G.M. ; Hennekam R. ; Donders T.H. ; Bunnik F.P.M. ; de Lange G.J. ; Brinkhuis H. ; Sangiorgi F.
刊名: Quaternary Science Reviews
ISSN: 2773791
出版年: 2015
卷: 108 起始页码: 130
结束页码: 138
语种: 英语
英文关键词: Dinocysts
; Eastern Mediterranean
; Holocene
; Nile discharge
; Pollen and spores
; Preservation
; Productivity
; Sapropel S1
Scopus关键词: accumulation rate
; biogenic deposit
; decomposition
; dinoflagellate cyst
; nutrient enrichment
; organic matter
; outflow
; palynology
; palynomorph
; pollen
; preservation
; spore
; stratification
; water column
; Nile [Uganda]
; Uganda
英文摘要: The formation of Eastern Mediterranean organic matter rich deposits known as sapropels is the results of two mechanisms: (enhanced) marine productivity and preservation of organic material at depth. However, their relative contribution and their leads and lags with respect to each other remainelusive. Here, we address these questions by studying sediments deposited prior to, during, and after the most recent sapropel (S1, ~10-6 calibrated ka before present, BP) with an integrated marine and terrestrial palynological approach, combined with existing and newly generated geochemical data. The studied core was retrieved from an area under strong influence of the Nile outflow and has high average sediment accumulation rates allowing a high temporal resolution (of several decades to centuries).Marine productivity, as reconstructed with total dinocyst accumulation rates (ARs) and biogenic CaCO3 content, starts to increase ~1ka prior to sapropel formation. A shift in the dinocyst taxa contributing to the productivity signal at sapropel onset indicates the rapid development of (seasonal) water column stratification. Pollen and spore ARs also increase prior to sapropel onset, but a few centuries after the increase in marine productivity. Hence, the first shift to a high marine productivity system before sapropel deposition may have been mostly favoured by the injection of nutrients via shoaling of the nutricline with a minor contribution of nutrients from land via river input and flooding of the shelves. Pollen assemblages indicate a gradual change across the sapropel onset from a savanna-like, through coastal marsh expansion, toward an open woodland assemblage, which is consistent with enhanced Nile influence and delta development. At sapropel onset a marked shift in pollen ARs could suggest increased preservation under anoxia. However, major shifts in pollen assemblages and signs of selective- or partial decomposition of terrestrial palynomorphs are absent. We therefore suggest that the high pollen ARs largely result from an increased influx of pollen by enhanced Nile discharge and extension of the freshwater plume. Three centuries after the sapropel onset, dinocyst ARs and CaCO3 content indicate that marine productivity starts to decrease, while sapropel deposition continued. Organic carbon content decreased only later and less dramatically. This may be explained by a shift in the dominance of the organisms contributing to marine productivity, to an enhanced preservation of organic matter, or a combination of both. © 2014 Elsevier Ltd. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/60050
Appears in Collections: 过去全球变化的重建
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作者单位: Marine Palynology and Paleoceanography, Laboratory of Palaeobotany and Palynology, Department of Earth Sciences, Faculty of Geosciences, Utrecht University, Budapestlaan 4, CD Utrecht, Netherlands; Department of Earth Sciences, Faculty of Geosciences, Utrecht University, Budapestlaan 4, CD Utrecht, Netherlands; Department of Physical Geography, Faculty of Geosciences, Utrecht University, Budapestlaan 4, CD Utrecht, Netherlands; TNO-Energy-Petroleum Geosciences, Princetonlaan 6, CB Utrecht, Netherlands; NIOZ Royal Netherlands Institute for Sea Research, PO Box 59, AB Den Burg, Texel, Netherlands
Recommended Citation:
van Helmond N.A.G.M.,Hennekam R.,Donders T.H.,et al. Marine productivity leads organic matter preservation in sapropel S1: Palynological evidence from a core east of the Nile River outflow[J]. Quaternary Science Reviews,2015-01-01,108