DOI: 10.1016/j.epsl.2020.116464
论文题名: A tale of two domes: Neogene to recent volcanism and dynamic uplift of northeast Brazil and southwest Africa
作者: Klöcking M. ; Hoggard M.J. ; Rodríguez Tribaldos V. ; Richards F.D. ; Guimarães A.R. ; Maclennan J. ; White N.J.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2020
卷: 547 语种: 英语
中文关键词: 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
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. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165080
Appears in Collections: 气候变化与战略
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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
Recommended Citation:
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]. Earth and Planetary Science Letters,2020-01-01,547