气候变化领域集成服务门户(CCPortal): A tale of two domes: Neogene to recent volcanism and dynamic uplift of northeast Brazil and southwest Africa

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DOI	10.1016/j.epsl.2020.116464
	A tale of two domes: Neogene to recent volcanism and dynamic uplift of northeast Brazil and southwest Africa
	Klöcking M.; Hoggard M.J.; Rodríguez Tribaldos V.; Richards F.D.; Guimarães A.R.; Maclennan J.; White N.J.
发表日期	2020
ISSN	0012821X
卷号	547
英文摘要	Topographic domes that are distant from active plate boundaries are often characterised by rapid, youthful uplift, contemporaneous mafic volcanism, radial drainage patterns, and positive long-wavelength gravity anomalies. There is increasing evidence that they are underlain by anomalously low sub-plate seismic velocities. Despite their well-known geomorphological expression, the origin of these epeirogenic features remains enigmatic and is much debated. Here, we investigate potential mechanisms for rapid regional uplift by combining disparate observations from the Borborema and Angolan plateaux that straddle the Brazilian and southwest African margins, respectively. Oceanic residual depth measurements, drainage analysis, stratigraphic architecture, emergent marine terraces and basement denudation are used to constrain their regional uplift histories. In both cases, the bulk of topographic growth occurred within the last 30 Ma in the absence of significant tectonic deformation. We estimate present-day mantle temperature and lithospheric thickness from Neogene to recent volcanic trace element compositions and upper mantle shear wave velocities. Volcanic geochemistry in northeast Brazil is compatible with decompression melting of warm asthenosphere and potentially a minor contribution from metasomatised lithospheric mantle. In Angola, melting of metasomatised lithosphere is probably triggered by injection of small-degree asthenospheric-derived melts. We find no evidence for an asthenospheric thermal anomaly >50 °C above ambient beneath either region. Present-day lithospheric thickness is ∼100 km beneath Angola and could be as thin as 60 km in the Borborema Province. For Angola, thermobarometry on mantle xenocrysts from Cretaceous kimberlites is used to estimate palaeogeothermal gradients. Results indicate a pre-existing gradient in lithospheric thickness between the edge of the Congo craton and the centre of the Angolan dome at ∼120 Ma. This gradient likely steepened as a result of additional Neogene thinning by 30±10 km beneath the centre of the dome. We conclude that the mechanism for Neogene epeirogenic uplift of the Borborema and Angolan domes is the introduction of a small positive temperature anomaly into the asthenosphere that causes thermomechanical thinning of the overlying lithospheric mantle. © 2020 Elsevier B.V.
关键词	asthenospheric temperature dynamic topography intraplate magmatism landscape evolution lithospheric structure xenolith thermobarometry
英文关键词	Melting; Minerals; Shear flow; Shear waves; Stratigraphy; Trace elements; Volcanoes; Decompression melting; Lithospheric mantle; Lithospheric thickness; Metasomatised lithosphere; Shear wave velocity; Stratigraphic architecture; Tectonic deformations; Trace element composition; Domes; dome; lithospheric structure; Neogene; temperature anomaly; terrace; topography; uplift; volcanism; Angola; Borborema; Brazil; Congo Craton
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/202702
作者单位	Bullard Laboratories, Department of Earth Sciences, University of Cambridge, United Kingdom; Research School of Earth Sciences, The Australian National University, Acton, ACT, Australia; Lamont–Doherty Earth Observatory, Columbia University, New York, United States; Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA, United States; Lawrence Berkeley National Laboratory, Berkeley, CA, United States; Department of Earth Science and Engineering, Imperial College, London, United Kingdom; School of GeoSciences, University of Edinburgh, United Kingdom
推荐引用方式 GB/T 7714	Klöcking M.,Hoggard M.J.,Rodríguez Tribaldos V.,et al. A tale of two domes: Neogene to recent volcanism and dynamic uplift of northeast Brazil and southwest Africa[J],2020,547.
APA	Klöcking M..,Hoggard M.J..,Rodríguez Tribaldos V..,Richards F.D..,Guimarães A.R..,...&White N.J..(2020).A tale of two domes: Neogene to recent volcanism and dynamic uplift of northeast Brazil and southwest Africa.Earth and Planetary Science Letters,547.
MLA	Klöcking M.,et al."A tale of two domes: Neogene to recent volcanism and dynamic uplift of northeast Brazil and southwest Africa".Earth and Planetary Science Letters 547(2020).