Knowledge Resource Center for Ecological Environment in Arid Area
DOI | 10.1029/2012GC004146 |
Signatures and significance of aeolian, fluvial, bacterial and diagenetic magnetic mineral fractions in Late Quaternary marine sediments off Gambia, NW Africa | |
Just, Janna1,2; Dekkers, Mark J.3; von Dobeneck, Tilo1,2; van Hoesel, Annelies; Bickert, Torsten1,2 | |
通讯作者 | Just, Janna |
来源期刊 | GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS |
ISSN | 1525-2027 |
出版年 | 2012 |
卷号 | 13 |
英文摘要 | Two gravity cores retrieved off NW Africa at the border of arid and subtropical environments (GeoB 13602-1 and GeoB 13601-4) were analyzed to extract records of Late Quaternary climate change and sediment export. We apply end-member (EM) unmixing to 350 acquisition curves of isothermal remanent magnetization (IRM). Our approach enables to discriminate rock magnetic signatures of aeolian and fluvial material, to determine biomineralization and reductive diagenesis. Based on the occurrence of pedogenically formed magnetic minerals in the fluvial and aeolian EMs, we can infer that goethite formed in favor to hematite in more humid climate zones. The diagenetic EM dominates in the lower parts of the cores and within a thin near-surface layer probably representing the modern Fe2+/Fe3+ redox boundary. Up to 60% of the IRM signal is allocated to a biogenic EM underlining the importance of bacterial magnetite even in siliciclastic sediments. Magnetosomes are found well preserved over most of the record, indicating suboxic conditions. Temporal variations of the aeolian and fluvial EMs appear to faithfully reproduce and support trends of dry and humid conditions on the continent. The proportion of aeolian to fluvial material was dramatically higher during Heinrich Stadials, especially during Heinrich Stadial 1. Dust export from the Arabian-Asian corridor appears to vary contemporaneous to increased dust fluxes at the continental margin of NW Africa emphasizing that meltwater discharge in the North Atlantic had an enormous impact on atmospheric dynamics. |
英文关键词 | IRM end-member modeling NW Africa environmental magnetism magnetotactic bacteria paleoclimate terrigenous input |
类型 | Article |
语种 | 英语 |
国家 | Germany ; Netherlands |
收录类别 | SCI-E |
WOS记录号 | WOS:000309417300001 |
WOS关键词 | DEEP-SEA SEDIMENTS ; ISOTHERMAL REMANENT MAGNETIZATION ; ACQUISITION CURVES ; SOUTH-ATLANTIC ; CHINESE LOESS ; GRAIN-SIZE ; EQUATORIAL ATLANTIC ; BIOGENIC MAGNETITE ; TROPICAL ATLANTIC ; VERWEY TRANSITION |
WOS类目 | Geochemistry & Geophysics |
WOS研究方向 | Geochemistry & Geophysics |
资源类型 | 期刊论文 |
条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/172488 |
作者单位 | 1.Univ Bremen, MARUM Ctr Marine & Environm Sci, DE-28334 Bremen, Germany; 2.Univ Bremen, Fac Geosci, DE-28334 Bremen, Germany; 3.Univ Utrecht, Fac Geosci, Dept Earth Sci, Paleomagnet Lab Ft Hoofddijk, NL-3584 CD Utrecht, Netherlands |
推荐引用方式 GB/T 7714 | Just, Janna,Dekkers, Mark J.,von Dobeneck, Tilo,et al. Signatures and significance of aeolian, fluvial, bacterial and diagenetic magnetic mineral fractions in Late Quaternary marine sediments off Gambia, NW Africa[J],2012,13. |
APA | Just, Janna,Dekkers, Mark J.,von Dobeneck, Tilo,van Hoesel, Annelies,&Bickert, Torsten.(2012).Signatures and significance of aeolian, fluvial, bacterial and diagenetic magnetic mineral fractions in Late Quaternary marine sediments off Gambia, NW Africa.GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS,13. |
MLA | Just, Janna,et al."Signatures and significance of aeolian, fluvial, bacterial and diagenetic magnetic mineral fractions in Late Quaternary marine sediments off Gambia, NW Africa".GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS 13(2012). |
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