Decarbonation in the Ca-Mg-Fe carbonate system at mid-crustal pressure as a function of temperature and assimilation with arc magmas – Implications for long-term climate

Crustal CO2 contribution to subduction zone degassing recorded through calc-silicate xenoliths in arc lavas

“…Aureoles are thermally and chemically gradational, with proximal thermally-affected fully decarbonated and/or assimilated rocks, through metasomatic rocks, to distal marbles, therefore we use a conservative 50% decarbonation efficiency as an average for our aureole calculations. This is in line with a lack of olivine, periclase and other magnesian phases in the xenoliths, which implies the carbonate protolith at Merapi is highly likely to be limestone, which has a lower decarbonation efficiency than dolomite 55 .…”

“…Periods of global warming in the Earth’s past, such as the Cretaceous hothouse and the Paleocene-Eocene Thermal Maximum (PETM) have been discussed in the context of excess atmospheric carbon originating from either organic carbon release 53 , intense volcanism 54 and/or increased magma-crustal carbonate interaction at volcanic arcs 55 . Some periods of global warming in the Earth’s past, notably the PETM, are accompanied by negative δ 13 C excursions of several per mil in the rock record, which could be explained by either massive volcanism 54 and/or organic carbon release (permafrost and/or methane hydrates) 53 .…”

“…Δ 13 C CO2-calcite = 3.7 to 2.7‰ at 500–1000 °C 19 ), thus driving the δ 13 C of released CO 2 at volcanoes to relatively high values. A suggested increased volume of crustal carbonate CO 2 release during PETM 55 would therefore increase the δ 13 C composition of the global volcanic CO 2 output above typical mantle values (c.f. 2,56 ).…”

“…The size of the pre-eruptive magma reservoir below Merapi is poorly constrained, but is known to reside within the carbonate substrata 33,44 . Using the erupted volume from the 2010 paroxysmal eruption of 0.02 to 0.05 km 3 50 and an average intrusive:extrusive ratio of 5:1 55,62 , we assume an estimated reservoir size of 0.1 to 0.25 km 3 . Thermal and metasomatic aureoles can be extensive in size 63 , so we calculate a range of aureole thicknesses from 5 to 30% of the reservoir width.…”

Application and Comparison of Machine Learning Algorithms for Predicting Mass Loss of Cement Raw Materials due to Decarbonation Process

“…In reality, the chemical composition of raw materials, particle size distributions, temperature range throughout the duration of the decarbonation process are most important factors affecting mass loss due to decarbonation. The relation between the mass loss its influence factors is highly complex [5]. Unfortunately, when the problem is complex, it is difficult or even impossible to obtain exact relationship between target and its influence factors.…”