干旱区生态环境知识资源中心(Arid): Erosion rates and weathering timescales in the eastern Great Escarpment, South Africa

Arid

DOI	10.1016/j.chemgeo.2021.120368
	Erosion rates and weathering timescales in the eastern Great Escarpment, South Africa
	Makhubela, Tebogo, V; Kramers, Jan D.; Konyana, Sibusiso M.; van Niekerk, Herman S.; Winkler, Stephan R.
通讯作者	Makhubela, TV (corresponding author), Univ Johannesburg, Dept Geol, Johannesburg, South Africa.
来源期刊	CHEMICAL GEOLOGY
ISSN	0009-2541
EISSN	1872-6836
出版年	2021
卷号	580
英文摘要	The eastern escarpment in South Africa has a combination of geology and climate that is unique in the entire Great Escarpment. Yet, no studies have been undertaken before to quantify the landscape changes at this locality. In this study, we assess the denudation history of the eastern escarpment using cosmogenic beryllium-10 (Be-10) on quartz from rock outcrops and river sediments, and carry out uranium-thorium-helium ((U,Th)-He) and argon-argon (Ar-40/Ar-39) dating of Fe-oxides and Mn-oxides, respectively, in the soils. The erosion rates obtained on the eastern escarpment vary from 1.8 m/Ma to 24 m/Ma and are similar in range to values from the entire Great Escarpment. We found that the catchment-averaged erosion rates of the gentle catchments above the eastern escarpment are lower, whereas those from steep catchments draining the escarpment edge are higher. We also determined that the catchment-average erosion rates of the eastern escarpment are similar to those of the western escarpment in Namibia, lower than those of the Drakensberg Escarpment and lower than those of the Lowveld adjacent to it. The Ar-40/Ar-39 dating of cryptomelane-bearing Mn nodules yield Palaeoproterozoic ages unrelated to the pedogenic processes, and might indicate that these nodules are not pedogenic, but inherited from weathered bedrock. The (U,Th)-He ages of goethite concretions range from 0.85 Ma to 1.05 Ma and they date the last period of intensive chemical weathering on the eastern escarpment, which coincides with the Mid Pleistocene Transition from humid to more arid conditions on the southern African subcontinent. Given the low erosion rates above the escarpment, an area that experiences intensive chemical weathering, and the high erosion rates down the escarpment we conclude that at the eastern escarpment, pediplanation is a more important driver of denudation than peneplanation.
英文关键词	Great Escarpment Southern Africa landscape Cosmogenic nuclides (U-Th)-He dating Fe-Mn-oxides Ar-40/Ar-39 dating
类型	Article
语种	英语
收录类别	SCI-E
WOS记录号	WOS:000689272600001
WOS关键词	APATITE FISSION-TRACK ; ANCIENT GNEISS COMPLEX ; LANDSCAPE EVOLUTION ; K-AR ; AR-40/AR-39 GEOCHRONOLOGY ; FERROMANGANESE DEPOSITS ; COSMOGENIC NUCLIDES ; SURFACE EROSION ; SOIL PRODUCTION ; LAND SURFACES
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/2XILL650/368305
作者单位	[Makhubela, Tebogo, V; Kramers, Jan D.; Konyana, Sibusiso M.; van Niekerk, Herman S.] Univ Johannesburg, Dept Geol, Johannesburg, South Africa; [Winkler, Stephan R.] NRF iThemba Labs Gauteng, ZA-2050 Johannesburg, South Africa
推荐引用方式 GB/T 7714	Makhubela, Tebogo, V,Kramers, Jan D.,Konyana, Sibusiso M.,et al. Erosion rates and weathering timescales in the eastern Great Escarpment, South Africa[J],2021,580.
APA	Makhubela, Tebogo, V,Kramers, Jan D.,Konyana, Sibusiso M.,van Niekerk, Herman S.,&Winkler, Stephan R..(2021).Erosion rates and weathering timescales in the eastern Great Escarpment, South Africa.CHEMICAL GEOLOGY,580.
MLA	Makhubela, Tebogo, V,et al."Erosion rates and weathering timescales in the eastern Great Escarpment, South Africa".CHEMICAL GEOLOGY 580(2021).