DOI: 10.1016/j.epsl.2020.116548
论文题名: TTG generation by fluid-fluxed crustal melting: Direct evidence from the Proterozoic Georgetown Inlier, NE Australia
作者: Pourteau A. ; Doucet L.S. ; Blereau E.R. ; Volante S. ; Johnson T.E. ; Collins W.J. ; Li Z.-X. ; Champion D.C.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2020
卷: 550 语种: 英语
中文关键词: amphibolite
; continental crust formation
; fluid-fluxed melting
; phase equilibrium and trace-element modelling
; Proterozoic
; TTG
英文关键词: Alkalinity
; Exploratory geochemistry
; Rare earths
; Tectonics
; Trace elements
; Chemical variability
; Continental crusts
; Field observations
; Geochemical signatures
; Heavy rare earth elements
; Lithospheric mantle
; Metamorphic evolution
; Phase equilibrium calculation
; Melting
; continental crust
; mafic rock
; metamorphism
; orogenic belt
; partial melting
; petrogenesis
; petrology
; Proterozoic
; tectonic setting
; Australia
; Georgetown [Queensland]
; Queensland
英文摘要: Across the Archaean to Proterozoic transition, the composition of newly-formed felsic continental crust changed from tonalite–trondhjemite–granodiorite (TTG) to calc-alkaline granitoid, possibly coinciding with the emergence of plate tectonics. Nevertheless, TTG suites were sporadically produced in Proterozoic and Phanerozoic orogenic belts, and such occurrences may provide petrological and tectonic insights into the formation of ancient continents. Here we demonstrate that the ca 1560 Ma Forest Home TTG plutonic suite in the Georgetown Inlier, NE Australia, was derived from partial melting of spatially-associated mafic rocks in a post-collisional setting. The studied TTG rocks have a ‘high-pressure’ geochemical signature, with elevated Sr, low heavy rare earth element and low high field strength element contents. Established petrogenetic models suggest they were derived by partial melting either of hydrated basaltic crust at >70 km depth or enriched lithospheric mantle, or by fractionation of lower-pressure mafic magmas. Using phase equilibrium calculations and trace-element modelling, we show that the geochemical signature of the Georgetown TTG likely resulted from fluid-fluxed crustal melting at relatively shallow depths (25–35 km), consistent with field observations and the inferred metamorphic evolution of the inlier. Our results suggest that the chemical variability of TTGs can reflect the variable availability of fluids rather than depth of melting, which has implications for tectonic processes responsible for the formation of early continental crust. © 2020 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165215
Appears in Collections: 气候变化与战略
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作者单位: Earth Dynamics Research Group, ARC Centre of Excellence for Core to Crust Fluid Systems (CCFS), The Institute for Geoscience Research (TIGeR), School of Earth and Planetary Sciences, Curtin University, GPO Box U1987WA 6845, Australia; The Institute for Geoscience Research (TIGeR), School of Earth and Planetary Sciences, Curtin University, GPO Box U1987WA 6845, Australia; Institut für Geologie, Mineralogie und Geophysik, Fakultät für Geowissenschaften, Ruhr-Universität Bochum, Universitätsstr. 150, Bochum, 44780, Germany; Geoscience Australia, Symonston, Canberra, ACT 2609, Australia
Recommended Citation:
Pourteau A.,Doucet L.S.,Blereau E.R.,et al. TTG generation by fluid-fluxed crustal melting: Direct evidence from the Proterozoic Georgetown Inlier, NE Australia[J]. Earth and Planetary Science Letters,2020-01-01,550