DOI: 10.1016/j.epsl.2017.12.013
Scopus记录号: 2-s2.0-85038216094
论文题名: Geodynamics of kimberlites on a cooling Earth: Clues to plate tectonic evolution and deep volatile cycles
作者: Tappe S. ; Smart K. ; Torsvik T. ; Massuyeau M. ; de Wit M.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2018
卷: 484 起始页码: 1
结束页码: 14
语种: 英语
英文关键词: early Earth
; global change
; kimberlite origin
; secular mantle cooling
; supercontinent cycles
; terrestrial magmatism
Scopus关键词: Carbon dioxide
; Gallium
; Geodynamics
; Lithology
; Magnesium compounds
; Melting
; Minerals
; Silicates
; Tectonics
; Trace elements
; Early Earth
; Global change
; Kimberlite origin
; Magmatisms
; Supercontinents
; Volcanic rocks
; cooling
; geodynamics
; global change
; kimberlite
; magmatism
; mantle process
; plate tectonics
; secular variation
; supercontinent
; tectonic evolution
; volatilization
英文摘要: Kimberlite magmatism has occurred in cratonic regions on every continent. The global age distribution suggests that this form of mantle melting has been more prominent after 1.2 Ga, and notably between 250–50 Ma, than during early Earth history before 2 Ga (i.e., the Paleoproterozoic and Archean). Although preservation bias has been discussed as a possible reason for the skewed kimberlite age distribution, new treatment of an updated global database suggests that the apparent secular evolution of kimberlite and related CO2-rich ultramafic magmatism is genuine and probably coupled to lowering temperatures of Earth's upper mantle through time. Incipient melting near the CO2- and H2O-bearing peridotite solidus at >200 km depth (1100–1400 °C) is the petrologically most feasible process that can produce high-MgO carbonated silicate melts with enriched trace element concentrations akin to kimberlites. These conditions occur within the convecting asthenospheric mantle directly beneath thick continental lithosphere. In this transient upper mantle source region, variable CHO volatile mixtures control melting of peridotite in the absence of heat anomalies so that low-degree carbonated silicate melts may be permanently present at ambient mantle temperatures below 1400 °C. However, extraction of low-volume melts to Earth's surface requires tectonic triggers. Abrupt changes in the speed and direction of plate motions, such as typified by the dynamics of supercontinent cycles, can be effective in the creation of lithospheric pathways aiding kimberlite magma ascent. Provided that CO2- and H2O-fluxed deep cratonic keels, which formed parts of larger drifting tectonic plates, existed by 3 Ga or even before, kimberlite volcanism could have been frequent during the Archean. However, we argue that frequent kimberlite magmatism had to await establishment of an incipient melting regime beneath the maturing continents, which only became significant after secular mantle cooling to below 1400 °C during post-Archean times, probably sometime shortly after 2 Ga. At around this time kimberlites replace komatiites as the hallmark mantle-derived magmatic feature of continental shields worldwide. The remarkable Mesozoic–Cenozoic ‘kimberlite bloom’ between 250–50 Ma may represent the ideal circumstance under which the relatively cool and volatile-fluxed cratonic roots of the Pangea supercontinent underwent significant tectonic disturbance. This created more than 60% of world's known kimberlites in a combination of redox- and decompression-related low-degree partial melting. Less than 2% of world's known kimberlites formed after 50 Ma, and the tectonic settings of rare ‘young’ kimberlites from eastern Africa and western North America demonstrate that far-field stresses on cratonic lithosphere enforced by either continental rifting or cold subduction play a crucial role in enabling kimberlite magma transfer to Earth's surface. © 2017 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/110070
Appears in Collections: 影响、适应和脆弱性 气候变化事实与影响
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作者单位: Deep & Early Earth Processes (DEEP) Research Group, Department of Geology, University of Johannesburg, Auckland Park, 2006, South Africa; School of Geosciences, University of the Witwatersrand, Johannesburg, 2050, South Africa; Centre for Earth Evolution and Dynamics (CEED), University of Oslo, Oslo, 0316, Norway; Geological Survey of Norway, Trondheim, 7491, Norway; Department of Geology, University of Pretoria, Pretoria, 0002, South Africa
Recommended Citation:
Tappe S.,Smart K.,Torsvik T.,et al. Geodynamics of kimberlites on a cooling Earth: Clues to plate tectonic evolution and deep volatile cycles[J]. Earth and Planetary Science Letters,2018-01-01,484