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dc.contributor.authorCarter, Laura B.
Dasgupta, Rajdeep
dc.date.accessioned 2017-05-19T20:48:12Z
dc.date.available 2017-05-19T20:48:12Z
dc.date.issued 2016
dc.identifier.citation Carter, Laura B. and Dasgupta, Rajdeep. "Effect of melt composition on crustal carbonate assimilation: Implications for the transition from calcite consumption to skarnification and associated CO2 degassing." Geochemistry, Geophysics, Geosystems, 17, no. 10 (2016) Wiley: 3893-3916. https://doi.org/10.1002/2016GC006444.
dc.identifier.urihttps://hdl.handle.net/1911/94303
dc.description.abstract Skarns are residue of relatively low-temperature magma-induced decarbonation in the crust largely associated with silicic plutons. Mafic magmatic intrusions are also capable of releasing excess CO2 due to carbonate assimilation. However, the effect of mafic to silicic melt evolution on the decarbonation processes, in addition to temperature controls on carbonate-intrusive magmatic systems, particularly at continental arcs, remains unclear. In this study, experiments performed in a piston cylinder apparatus at midcrustal depth (0.5 GPa) at supersolidus temperatures (900–1200°C) document calcite interaction with andesite and dacite melts at equilibrium under closed-system conditions at calcite saturation in a 1:1 melt-calcite ratio by weight. With increasing silica content in the starting melt, at similar melt fractions and identical pressure, assimilation decreases drastically (≤65% andesite-calcite to ≤18% dacite-calcite). In conjunction, the CaO/SiO2 ratio in melts resulting from calcite assimilation in andesitic starting material is >1, but ≤0.3 in those formed from dacite-calcite interaction. With increasing silica-content in the starting melt skarn mineralogy, particularly wollastonite, increases in modal abundance while diopsidic clinopyroxene decreases slightly. More CO2 is released with andesite-calcite reaction (≤2.9 × 1011 g/y) than with more skarn-like dacite-calcite interaction (≤8.1 × 1010 g/y, at one volcano assuming respective calcite-free-superliquidus conditions and a magma flux of 1012 g/y). Our experimental results thus suggest that calcite assimilation in more mafic magmas may have first degassed a significant amount of crustal carbon before the melt evolves to more silicic compositions, producing skarn. Crustal decarbonation in long-lived magmatic systems may hence deliver significant albeit diminishing amounts of carbon to the atmosphere and contribute to long-term climate change.
dc.language.iso eng
dc.publisher Wiley
dc.rights Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
dc.title Effect of melt composition on crustal carbonate assimilation: Implications for the transition from calcite consumption to skarnification and associated CO2 degassing
dc.type Journal article
dc.citation.journalTitle Geochemistry, Geophysics, Geosystems
dc.citation.volumeNumber 17
dc.citation.issueNumber 10
dc.type.dcmi Text
dc.identifier.doihttps://doi.org/10.1002/2016GC006444
dc.type.publication publisher version
dc.citation.firstpage 3893
dc.citation.lastpage 3916


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