气候变化领域集成服务门户(CCPortal): Weathering dynamics of Large Igneous Provinces (LIPs): A case study from the Lesotho Highlands

CCPortal

DOI	10.1016/j.epsl.2019.115871
	Weathering dynamics of Large Igneous Provinces (LIPs): A case study from the Lesotho Highlands
	Chen Y.; Hedding D.W.; Li X.; Greyling A.C.; Li G.
发表日期	2020
ISSN	0012821X
卷号	530
英文摘要	Basaltic terrains contribute a significant component to the global silicate weathering flux despite their limited areal coverage. A strong correlation between chemical weathering flux and climatic factors such as temperature in volcanically inactive basaltic fields implies that weathering of basalt might have played an important role in maintaining the habitability of the Earth and the balance of the geological carbon cycle. However, the low erosion rate of flood basalt provinces on tectonically quiescent cratons, where the clear climate dependence of weathering rate has been observed, implies a ‘supply-limited’ weathering regime so that weathering fluxes are expected to be controlled by physical erosion rather than climate. This work tests the weathering dynamics of flood basalts by investigating the weathering flux of the Karoo LIP on the Lesotho Highlands where an extremely low rate of denudation has been recorded through terrestrial cosmogenic nuclide dating and sediment flux. Stream chemistry of the rivers from the Lesotho Highlands shows typical characteristics of basalt weathering with Ca and Mg as the dominant cations and HCO3 − as the dominant anion. Strong spatial and seasonal variability of solute concentration, possibly linked to a dilution effect, is observed. However, the giant Katse Reservoir of the Lesotho Highlands Water Project (LHWP) effectively averages the spatial and seasonal variability of the solute concentration. The average solution concentration and long-term runoff of the Katse Reservoir give an average atmospheric CO2 consumption rate of 0.26 ± 0.02 × 106 mol/km2/yr (mean ± standard deviation). The chemical weathering flux requires complete alteration of primary silicates and, therefore, a ‘supply-limited’ weathering regime is suggested given the low denudation rate. Nevertheless, the chemical weathering rate of the Lesotho Highlands, as well as other low-eroding basaltic plateaus, is still consistent with the global correlation between temperature and the rate of basalt weathering. A production-limited denudation rate, modulated by temperature, is suggested to reconcile the paradox between the observed temperature dependence of chemical weathering rates and ‘supply-limited’ weathering regimes. © 2019 Elsevier B.V.
关键词	critical zone landscape evolution regolith soil water-rock reaction
英文关键词	Basalt; Erosion; Floods; Geochemistry; Reservoirs (water); Silicates; Soils; Temperature distribution; Critical zones; Landscape evolutions; Large Igneous Provinces (LIPs); Lesotho Highlands Water Project; regolith; Temperature dependence; Terrestrial cosmogenic nuclides; Water-rock reactions; Weathering; chemical weathering; erosion rate; flood basalt; igneous geochemistry; landscape evolution; large igneous province; radiocarbon dating; regolith; water-rock interaction; Karoo; Lesotho; South Africa
语种	英语
来源期刊	Earth and Planetary Science Letters
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/202541
作者单位	MOE Key Laboratory of Surficial Geochemistry, Department of Earth and Planetary Sciences, Nanjing University, Nanjing, 210023, China; Department of Geography, University of South Africa, Pioneer Avenue, Florida, 1710, South Africa; SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, 710061, China
推荐引用方式 GB/T 7714	Chen Y.,Hedding D.W.,Li X.,et al. Weathering dynamics of Large Igneous Provinces (LIPs): A case study from the Lesotho Highlands[J],2020,530.
APA	Chen Y.,Hedding D.W.,Li X.,Greyling A.C.,&Li G..(2020).Weathering dynamics of Large Igneous Provinces (LIPs): A case study from the Lesotho Highlands.Earth and Planetary Science Letters,530.
MLA	Chen Y.,et al."Weathering dynamics of Large Igneous Provinces (LIPs): A case study from the Lesotho Highlands".Earth and Planetary Science Letters 530(2020).