Reactive Infiltration of MORB-Eclogite-Derived Carbonated Silicate Melt into Fertile Peridotite at 3GPa and Genesis of Alkalic Magmas
| dc.citation.firstpage | 1 | en_US |
| dc.citation.journalTitle | Journal of Petrology Advance Access | en_US |
| dc.citation.lastpage | 34 | en_US |
| dc.contributor.author | Mallik, Ananya | en_US |
| dc.contributor.author | Dasgupta, Rajdeep | en_US |
| dc.date.accessioned | 2013-09-25T17:48:52Z | en_US |
| dc.date.available | 2013-09-25T17:48:52Z | en_US |
| dc.date.issued | 2013 | en_US |
| dc.description.abstract | We performed experiments between two different carbonated eclogite-derived melts and lherzolite at 1375°C and 3 GPa by varying the reacting melt fraction from 8 to 50 wt %. The two starting melt compositions were (1) alkalic basalt with 11·7 wt % dissolved CO2 (ABC), (2) basaltic andesite with 2·6 wt % dissolved CO2 (BAC). The starting melts were mixed homogeneously with peridotite to simulate porous reactive infiltration of melt in the Earth’s mantle. All the experiments produced an assemblage of melt + orthopyroxene + clinopyroxene + garnet ± olivine; olivine was absent for a reacting melt fraction of 50 wt % for ABC and 40 wt % for BAC. Basanitic ABC evolved to melilitites (on a CO2-free basis, SiO2 ∼27–39 wt %, TiO2 ∼2·8–6·3 wt %, Al2O3 ∼4·1–9·1 wt %, FeO* ∼11–16 wt %, MgO ∼17–21 wt %, CaO ∼13–21 wt %, Na2O ∼4–7 wt %, CO2 ∼10–25 wt %) upon melt–rock reaction and the degree of alkalinity of the reacted melts is positively correlated with melt–rock ratio. On the other hand, reacted melts derived from BAC (on a CO2-free basis SiO2 ∼42–53 wt %, TiO2 ∼6·4–8·7 wt %, Al2O3 ∼10·5–12·3 wt %, FeO* ∼6·5–10·5 wt %, MgO ∼7·9–15·4 wt %, CaO ∼7·3–10·3 wt %, Na2O ∼3·4–4 wt %, CO2 ∼6·2–11·7 wt %) increase in alkalinity with decreasing melt–rock ratio. We demonstrate that owing to the presence of only 0·65 wt % of CO2 in the bulk melt–rock mixture (corresponding to 25 wt % BAC + lherzolite mixture), nephelinitic-basanite melts can be generated by partial reactive crystallization of basaltic andesite as opposed to basanites produced in volatile-free conditions. Post 20% olivine fractionation, the reacted melts derived from ABC at low to intermediate melt–rock ratios match with 20–40% of the population of natural nephelinites and melilitites in terms of SiO2 and CaO/Al2O3, 60–80% in terms of TiO2, Al2O3 and FeO, and <20% in terms of CaO and Na2O. The reacted melts from BAC, at intermediate melt–rock ratios, are excellent matches for some of the Mg-rich (MgO >15 wt %) natural nephelinites in terms of SiO2, Al2O3, FeO*, CaO, Na2O and CaO/Al2O3. Not only can these reacted melts erupt by themselves, they can also act as metasomatizing agents in the Earth’s mantle. Our study suggests that a combination of subducted, silica-saturated crust–peridotite interaction and the presence of CO2 in the mantle source region are sufficient to produce a large range of primitive alkalic basalts. Also, mantle potential temperatures of 1330–1350°C appear sufficient to produce high-MgO, primitive basanite–nephelinite if carbonated eclogite melt and peridotite interaction is taken into account. | en_US |
| dc.embargo.terms | none | en_US |
| dc.identifier.citation | Mallik, Ananya and Dasgupta, Rajdeep. "Reactive Infiltration of MORB-Eclogite-Derived Carbonated Silicate Melt into Fertile Peridotite at 3GPa and Genesis of Alkalic Magmas." <i>Journal of Petrology Advance Access,</i> (2013) Oxford University Press: 1-34. http://dx.doi.org/10.1093/petrology/egt047. | en_US |
| dc.identifier.doi | http://dx.doi.org/10.1093/petrology/egt047 | en_US |
| dc.identifier.uri | https://hdl.handle.net/1911/72115 | en_US |
| dc.language.iso | eng | en_US |
| dc.publisher | Oxford University Press | en_US |
| 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. | en_US |
| dc.subject.keyword | alkalic basalts | en_US |
| dc.subject.keyword | carbonated silicate melt | en_US |
| dc.subject.keyword | MORB-eclogite | en_US |
| dc.subject.keyword | peridotite | en_US |
| dc.subject.keyword | reactive infiltration | en_US |
| dc.title | Reactive Infiltration of MORB-Eclogite-Derived Carbonated Silicate Melt into Fertile Peridotite at 3GPa and Genesis of Alkalic Magmas | en_US |
| dc.type | Journal article | en_US |
| dc.type.dcmi | Text | en_US |
| dc.type.publication | publisher version | en_US |