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DOI	10.1016/j.epsl.2021.116771
	Residence time of igneous garnet in Si-rich magmatic systems: Insights from diffusion modeling of major and trace elements
	Devoir A.; Bloch E.; Müntener O.
发表日期	2021
ISSN	0012821X
卷号	560
英文摘要	Although garnet is an important accessory phase in many granitic rocks, the petrogenetic history of such garnets is often debated. Explanations range from crystallization from (mostly) peraluminous melts to entrainment of peritectic or xenocrystic garnets originating from country rocks. Here we present a detailed microchemical study of a mid-crustal granodiorite from the Ivrea-Zone (N-Italy), which contains metapelitic enclaves and composite metamorphic-magmatic xeno-phenocryst garnet. Garnets from this locality exhibit high-phosphorus (∼800 ppm) metamorphic cores and multiple igneous overgrowth rims. The high-phosphorus cores appear to originate from granulite facies country-rock, while low-phosphorus rims indicate magmatic overgrowth in two main episodes. Zircon-bearing nanogranitoid inclusions are trapped along embayments between garnet cores and the first magmatic growth zones. Zirconium saturation thermometry indicates a temperature of 820 ± 5°C during the first magmatic overgrowth, and a temperature of 778 ± 10°C for the second overgrowth. The latter temperature agrees with garnet-biotite thermometry using the garnet rim composition, which yields a temperature of 773 ± 29 °C. In order to quantify the duration of the overgrowth episodes, we have numerically modeled Cr, Y, REEs and Hf trace element diffusion, as well as multicomponent major divalent cation diffusion within garnet using available experimental diffusion data and Cr diffusion data retrieved from natural garnets. All modeled diffusants conform to a single temperature-time path, in which the temperatures associated with the first and second magmatic overgrowths persisted for 5.4 and 6.3 kyr, respectively. Composite garnets in Si-rich magmatic systems have the potential to constrain magma transit rates in the continental crust. © 2021 The Author(s)
关键词	igneous garnet Ivrea-Verbano multi-element diffusion nanogranites residence time
英文关键词	Diffusion; Mica; Phosphorus; Thermometers; Trace elements; Zircon; Zircon deposits; Continental crusts; Diffusion model; Divalent cation; Element diffusion; Granulite facies; Magmatic systems; Major and trace elements; Multicomponents; Garnets; diffusion; garnet; granite; granodiorite; magma; metapelite; modeling; residence time; trace element; Italy; Ivrea-Verbano Zone
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/203071
作者单位	Institute of Earth Sciences, University of Lausanne, Geopolis, Lausanne, 1015, Switzerland
推荐引用方式 GB/T 7714	Devoir A.,Bloch E.,Müntener O.. Residence time of igneous garnet in Si-rich magmatic systems: Insights from diffusion modeling of major and trace elements[J],2021,560.
APA	Devoir A.,Bloch E.,&Müntener O..(2021).Residence time of igneous garnet in Si-rich magmatic systems: Insights from diffusion modeling of major and trace elements.Earth and Planetary Science Letters,560.
MLA	Devoir A.,et al."Residence time of igneous garnet in Si-rich magmatic systems: Insights from diffusion modeling of major and trace elements".Earth and Planetary Science Letters 560(2021).