气候变化领域集成服务门户(CCPortal): Reconstructing East African monsoon variability from grain-size distributions: End-member modeling and source attribution of diatom-rich sediments from Lake Chala

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DOI	10.1016/j.quascirev.2020.106574
	Reconstructing East African monsoon variability from grain-size distributions: End-member modeling and source attribution of diatom-rich sediments from Lake Chala
	Meyer I.; Van Daele M.; Tanghe N.; De Batist M.; Verschuren D.
发表日期	2020
ISSN	0277-3791
卷号	247
英文摘要	Grain-size analysis and end-member modeling of the clastic fraction of the 25-kyr sediment sequence from Lake Chala, a meromictic crater lake on the lower east slope of Mt. Kilimanjaro, reveal crucial aspects of climate-driven environmental change in equatorial East Africa since the Last Glacial Maximum. The finely laminated sediments of Lake Chala contain only up to 40% of clastic components, the rest are mainly diatom frustules and amorphous organic matter. Measured grain-size distributions were split into six statistically meaningful end members, of which four could be linked to a distinct source and transport mechanism of clastic mineral input: fine aeolian dust from distal sources (EM1), fine catchment runoff (EM2), coarser aeolian dust from proximal sources (EM5) and coarse erosive material from the upper crater slopes (EM6). The two other end members (EM3 and EM4) represented frustules of the two most common diatom taxa in Lake Chala, Afrocymbella barkeri and Nitzschia fabiennejansseniana, which had (partly) survived sample pre-treatment. Temporal variation in normalized abundance of the two dust-derived end members are valuable proxies for past changes in monsoon circulation over equatorial East Africa. During Northern Hemisphere cold periods (e.g., Last Glacial Maximum and Younger Dryas) the Inter-Tropical Convergence Zone shifted southward, enhancing northeasterly monsoon winds in the Lake Chala area and increasing advection of fine dust from the dry Horn of Africa region. Simultaneously, more modest continental heating reduced the prevalence of small-scale atmospheric turbulence, and thus the occurrence of dust devils, resulting in reduced influx of coarse dust from drylands nearby. Conversely, abrupt intensification of the southeasterly monsoon at the onset of the Holocene is recorded by an abrupt increase in the amount of coarse dust delivered to Lake Chala. Temporal variation in the end members representing catchment run-off (EM2) and erosion (EM6) mainly reflect changes in lacustrine sedimentation dynamics associated with major lake-level fluctuation, as evidenced by other paleoenvironmental proxies. Overall this study shows that subdivision of the clastic fraction of lacustrine sediments into statistically robust grain-size end members can provide multiple independent and quantitative proxies which help constrain reconstructions of a region's multi-faceted climate history. © 2020 The Authors
英文关键词	Clastic sediment; Equatorial Africa; Holocene; Paleoclimatology; Paleolimnology; Sediment provenance
语种	英语
scopus关键词	Atmospheric thermodynamics; Atmospheric turbulence; Catchments; Climate change; Dust; Glacial geology; Grain size and shape; Lakes; Runoff; Size distribution; Amorphous organic matters; Grain size distribution; Intertropical convergence zone; Lacustrine sedimentations; Lacustrine sediments; Lake level fluctuations; Northern Hemispheres; Small-scale atmospheric turbulence; Sediments; crater lake; diatom; environmental change; eolian deposit; grain size; lacustrine deposit; Last Glacial Maximum; paleoenvironment; proxy climate record; sedimentation; Bourgogne-Franche-Comte; France; Horn of Africa; Jura [Bourgogne-Franche-Comte]; Kilimanjaro [Kilimanjaro (RGA)]; Kilimanjaro [Tanzania]; Lake Chalain; Tanzania; Bacillariophyta; Nitzschia
来源期刊	Quaternary Science Reviews
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/151304
作者单位	Renard Centre of Marine Geology (RCMG), Department of Geology, Ghent University, Krijgslaan 281 S8, Gent, B-9000, Belgium; Limnology Unit, Department of Biology, Ghent University, Ledeganckstraat 35, Gent, B-9000, Belgium
推荐引用方式 GB/T 7714	Meyer I.,Van Daele M.,Tanghe N.,et al. Reconstructing East African monsoon variability from grain-size distributions: End-member modeling and source attribution of diatom-rich sediments from Lake Chala[J],2020,247.
APA	Meyer I.,Van Daele M.,Tanghe N.,De Batist M.,&Verschuren D..(2020).Reconstructing East African monsoon variability from grain-size distributions: End-member modeling and source attribution of diatom-rich sediments from Lake Chala.Quaternary Science Reviews,247.
MLA	Meyer I.,et al."Reconstructing East African monsoon variability from grain-size distributions: End-member modeling and source attribution of diatom-rich sediments from Lake Chala".Quaternary Science Reviews 247(2020).