干旱区生态环境知识资源中心(Arid): Significantly enhanced mid Holocene fluvial activity in a globally important, arid-zone wetland: The Okavango Delta, Botswana

Arid

DOI	10.1002/esp.5289
	Significantly enhanced mid Holocene fluvial activity in a globally important, arid-zone wetland: The Okavango Delta, Botswana
	Tooth, Stephen; McCarthy, Terence S.; Duller, Geoff A. T.; Assine, Mario L.; Wolski, Piotr; Coetzee, Grace
通讯作者	Tooth, S (corresponding author)，Aberystwyth Univ, Dept Geog & Earth Sci, Earth Surface Proc Res Grp, Aberystwyth SY23 3DB, Dyfed, Wales.
来源期刊	EARTH SURFACE PROCESSES AND LANDFORMS
ISSN	0197-9337
EISSN	1096-9837
出版年	2022-01
英文摘要	Information on past dryland environments is commonly derived from geomorphological landforms and sediments ('geoproxies'). The Okavango Delta in the middle Kalahari, Botswana, has been subject to a long history of arid-humid transitions but its potentially rich archive of fluvial geoproxies is largely untapped. Previous palaeoenvironmental studies in the Delta region have focused mainly on aeolian dunes, lacustrine beach ridges, and rare pollen sequences in surrounding locations, and the Delta's channel dynamics have remained poorly constrained, both chronologically and in quantitative palaeohydrological terms. Focusing on the Delta's Xugana region, we present the first optically stimulated luminescence ages for palaeochannel fills and scroll bars, revealing significantly enhanced fluvial activity in the similar to 7-4 ka interval. Along 120-150 m-wide, sand-bed, sinuous palaeochannels, lateral migration and bend cutoffs were driven by palaeodischarges up to similar to 350-450 m(3) s(-1), at least nine times those of the present-day channels. These palaeochannels represent the last major phase of meander activity in the middle and lower Delta. The palaeodischarges imply significantly higher rainfall over the catchment in the mid Holocene, possibly resulting from a southwards shift of the African tropical rainbelt. Over the last few thousand years, diminished fluvial activity in the Xugana region has continued; <20 m-wide channels with discharges typically <40 m(3) s(-1) have been more laterally stable, albeit subject to local avulsions. These findings provide the 'missing link' between evidence for past intervals of enhanced rainfall in the Delta's tributary catchments in the northwest and west and the filling of large lacustrine basins to the southeast and east. The findings contribute to improved understanding of changing Kalahari hydroclimates and support growing evidence indicating that the mid to late Holocene was a time of significant fluvial transformation across many of the world's drylands.
英文关键词	Holocene climate Kalahari luminescence dating Okavango Delta palaeodischarge scroll bar
类型	Article ; Early Access
语种	英语
收录类别	SCI-E
WOS记录号	WOS:000739613900001
WOS关键词	PALAEO-ENVIRONMENTAL CHANGE ; CENTRAL SOUTHERN AFRICA ; LATE QUATERNARY ; LAKE NGAMI ; KALAHARI DESERT ; CLIMATE-CHANGE ; MEGA-LAKE ; LUMINESCENCE ; RIVER ; DYNAMICS
WOS类目	Geography, Physical ; Geosciences, Multidisciplinary
WOS研究方向	Physical Geography ; Geology
资源类型	期刊论文
条目标识符	http://119.78.100.177/qdio/handle/2XILL650/377178
作者单位	[Tooth, Stephen; Duller, Geoff A. T.] Aberystwyth Univ, Dept Geog & Earth Sci, Aberystwyth, Dyfed, Wales; [Tooth, Stephen; McCarthy, Terence S.; Coetzee, Grace] Univ Witwatersrand, Sch Geosci, Johannesburg, South Africa; [Assine, Mario L.] Sao Paulo State Univ, Dept Geol, Sao Paulo, Brazil; [Wolski, Piotr] Univ Cape Town, Climate Syst Anal Grp, Rondebosch, South Africa
推荐引用方式 GB/T 7714	Tooth, Stephen,McCarthy, Terence S.,Duller, Geoff A. T.,et al. Significantly enhanced mid Holocene fluvial activity in a globally important, arid-zone wetland: The Okavango Delta, Botswana[J],2022.
APA	Tooth, Stephen,McCarthy, Terence S.,Duller, Geoff A. T.,Assine, Mario L.,Wolski, Piotr,&Coetzee, Grace.(2022).Significantly enhanced mid Holocene fluvial activity in a globally important, arid-zone wetland: The Okavango Delta, Botswana.EARTH SURFACE PROCESSES AND LANDFORMS.
MLA	Tooth, Stephen,et al."Significantly enhanced mid Holocene fluvial activity in a globally important, arid-zone wetland: The Okavango Delta, Botswana".EARTH SURFACE PROCESSES AND LANDFORMS (2022).