DOI: 10.1016/j.palaeo.2014.04.009
论文题名: How environmental magnetism can enhance the interpretational value of grain-size analysis: A time-slice study on sediment export to the NW African margin in Heinrich Stadial 1 and Mid Holocene
作者: Razik S. ; Dekkers M.J. ; von Dobeneck T.
刊名: Palaeogeography, Palaeoclimatology, Palaeoecology
ISSN: 0031-0182
出版年: 2014
卷: 406 起始页码: 33
结束页码: 48
语种: 英语
英文关键词: Aeolian sediment transport
; Environmental magnetism
; Grain-size analysis
; Northwest Africa
; Provenance
; Senegal River
英文摘要: Sediment dynamics in limnic, fluvial and marine environments can be assessed by granulometric and rock-magnetic methodologies. While classical grain-size analysis by sieving or settling mainly bears information on composition and transport, the magnetic mineral assemblages reflect to a larger extent the petrology and weathering conditions in the sediment source areas. Here, we combine both methods to investigate Late Quaternary marine sediments from five cores along a transect across the continental slope off Senegal. This region near the modern summer Intertropical Convergence Zone is particularly sensitive to climate change and receives sediments from several aeolian, fluvial and marine sources. From each of the investigated five GeoB sediment cores (494-2956. m water depth) two time slices were processed which represent contrasting climatic conditions: the arid Heinrich Stadial 1 (~. 15 kyr BP) and the humid Mid Holocene (~. 6 kyr BP). Each sediment sample was split into 16 grain-size fractions ranging from 1.6 to 500. μm. Concentration and grain-size indicative magnetic parameters (susceptibility, SIRM, HIRM, ARM and ARM/IRM) were determined at room temperature for each of these fractions. The joint consideration of whole sediment and magnetic mineral grain-size distributions allows to address several important issues: (i) distinction of two aeolian sediment fractions, one carried by the north-easterly trade winds (40-63. μm) and the other by the overlying easterly Harmattan wind (10-20. μm) as well as a fluvial fraction assigned to the Senegal River (<. 10. μm); (ii) identification of three terrigenous sediment source areas: southern Sahara and Sahel dust (low fine-grained magnetite amounts and a comparatively high haematite content), dust from Senegalese coastal dunes (intermediate fine-grained magnetite and haematite contents) and soils from the upper reaches of the Senegal River (high fine-grained magnetite content); (iii) detection of partial diagenetic dissolution of fine magnetite particles as a function of organic input and shore distance; (iv) analysis of magnetic properties of marine carbonates dominating the grain-size fractions 63-500. μm. © 2014 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/69315
Appears in Collections: 过去全球变化的重建
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作者单位: Department of Geosciences, University of Bremen, Klagenfurter Straße, 28359 Bremen, Germany; Department of Earth Sciences, Utrecht University, Budapestlaan 17, 3584 CD Utrecht, Netherlands; MARUM - Center for Marine Environmental Sciences, University of Bremen, Leobener Straße, D-28359 Bremen, Germany
Recommended Citation:
Razik S.,Dekkers M.J.,von Dobeneck T.. How environmental magnetism can enhance the interpretational value of grain-size analysis: A time-slice study on sediment export to the NW African margin in Heinrich Stadial 1 and Mid Holocene[J]. Palaeogeography, Palaeoclimatology, Palaeoecology,2014-01-01,406