DOI: 10.1016/j.epsl.2020.116549
论文题名: Thermobarometry of CO2-rich, silica-undersaturated melts constrains cratonic lithosphere thinning through time in areas of kimberlitic magmatism
作者: Sun C. ; Dasgupta R.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2020
卷: 550 语种: 英语
中文关键词: cratonic evolution
; deep carbon cycle
; geothermobarometry
; kimberlite
; lithosphere thickness
; silica-undersaturated melt
英文关键词: Alumina
; Aluminum oxide
; Carbon dioxide
; Olivine
; Silica
; Correction schemes
; Equilibration depths
; High temperature
; Lithosphere thinning
; Melt compositions
; Pressure dependent
; Temporal coupling
; Temporal variation
; Volcanic rocks
; barometry
; carbon dioxide
; craton
; crustal thinning
; experimental study
; kimberlite
; magmatism
; partial melting
; silicate melt
; temporal variation
; unsaturated medium
英文摘要: Cratonic lithosphere is believed to have been chemically buoyant and mechanically resistant to destruction over billions of years. Yet the absence of cratonic roots at some Archean terrains casts doubt on the craton stability and longevity on a global scale. As unique mantle-derived melts at ancient continents, silica-poor, kimberlitic melts are ideal tools to constrain the temporal variation of lithosphere thickness and the processes affecting the lithosphere root. However, no reliable thermobarometer exists to date for strongly silica-undersaturated, mantle-derived melts. Here we develop a new thermobarometer for silica-poor, CO2-rich melts using high-temperature, high-pressure experimental data. Our barometer is calibrated based on a new observation of pressure-dependent variation of Al2O3 in partial melts saturated with garnet and olivine, while our thermometer is calibrated based on the well-known olivine-melt Mg-exchange. For applications to natural magmas, we also establish a correction scheme to estimate their primary melt compositions. Applying this liquid-based thermobarometer to the estimated primary melt compositions for a global kimberlite dataset, we show that the equilibration depths between primary kimberlite melts and mantle peridotites indicate a decrease of up to ∼150 km in cratonic lithosphere thickness globally during the past ∼2 Gyr. Together with the temporal coupling between global kimberlite frequency and cold subduction flux since ∼2 Gyr ago, our results imply a causal link between lithosphere thinning and supply of CO2-rich melts enhanced by deep subduction of carbonated oceanic crusts. While hibernating at the lithosphere root, these melts chemically metasomatize and rheologically weaken the rigid lithosphere and consequently facilitate destruction through convective removal in the ambient mantle or thermo-magmatic erosion during mantle plume activities. © 2020 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165292
Appears in Collections: 气候变化与战略
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作者单位: Department of Earth, Environmental and Planetary Sciences, Rice University, 6100 Main Street, MS 126, Houston, TX 77005, United States
Recommended Citation:
Sun C.,Dasgupta R.. Thermobarometry of CO2-rich, silica-undersaturated melts constrains cratonic lithosphere thinning through time in areas of kimberlitic magmatism[J]. Earth and Planetary Science Letters,2020-01-01,550