Mostrar el registro sencillo del ítem
Systematic LREE enrichment of mantle harzburgites: The petrogenesis of San Carlos xenoliths revisited
dc.contributor.author | Tilhac, Romain | |
dc.date.accessioned | 2021-07-29T07:29:37Z | |
dc.date.available | 2021-07-29T07:29:37Z | |
dc.date.issued | 2021-04-30 | |
dc.identifier.citation | Romain Tilhac... [et al.]. Systematic LREE enrichment of mantle harzburgites: The petrogenesis of San Carlos xenoliths revisited, Lithos, Volumes 396–397, 2021, 106195, ISSN 0024-4937, [https://doi.org/10.1016/j.lithos.2021.106195] | es_ES |
dc.identifier.uri | http://hdl.handle.net/10481/69960 | |
dc.description | We are grateful to K. Itano for fruitful discussion of the ideas developed in this paper and K. Ozawa for support on the use of his opensystem melting model. The manuscript benefited from constructivecomments provided by Q. Xiong and three anonymous reviewers as well as from the editor X.-H. Li. This work was funded by a Japan Society for the Promotion of Science (JSPS) fellowship. | es_ES |
dc.description.abstract | The dichotomy between partial melting and metasomatism is a paradigm of mantle geochemistry since the pioneering work of Frey and Prinz (1978) on the occurrence of LREE-enriched harzburgites. However, the thermo-chemical implications of such two-stage scenarios are often poorly considered, and the latter fail to explain why trace-element enrichment and major-element depletion are often proportional.We here re-envisage the petrogenesis of the famous San Carlos peridotites based on new petrographic observations and detailed modal, major- and trace-element compositions. The lherzolites (and pyroxenites) are characterized by homogeneously fertile mineral chemistry and LREE-depleted patterns consistent with low degrees of partial melting of the lherzolitic protolith. Bulk compositions and mineral zoning suggest that opx-rich pyroxenites formed by pressure-solution creep during melt-present deformation, locally accompanied by magmatic segregations of cpx. The harzburgites are characterized by stronger mineral zoning with low-Mg# and Na-, Al- and Cr-rich cpx rims, and can be discriminated in a low-Jd and high-Jd cpx groups. The high-Jd group is interpreted as the result of local elemental redistribution in the presence of a low-degree hydrous melt, in good agreement with their wide range of LREE enrichment. In contrast, the MREE-to-HREE fractionation and increasing Cr# in spinel of the low-Jd group indicate that they experienced higher degrees of melting. Open-system melting simulations of trace-element fractionation during hydrous flux melting suggests that the high-Jd harzburgites are the result of low fluid influx producing poorly extracted melt, while higher influx led to higher melting degrees and efficient melt extraction in the low-Jd harzburgites; the lherzolites mostly remained below or near solidus during that process. The lithological and chemical heterogeneity of San Carlos mantle is thus compatible with a single-stage evolution, which is also supported by the striking consistency between Fe-Mg exchange and REE thermometric estimates (1057 and 1074 °C on average, respectively), indicating that harzburgites and lherzolites probably followed a similar P-T path and relatively little sub-solidus re-equilibration. These interpretations suggest that the development ofmelt extraction pathways promoted by reactive channeling instability is able to produce complex lithological heterogeneities during hydrous flux melting. This process provides a self-consistent explanation for the systematic enrichment of harzburgites observed in many mantle terranes and xenoliths worldwide. We argue that San Carlos is one of such examples where a ca 1.5-Ga continental lithosphere experienced localized flux melting and deformation during the tectonic reactivation of a Proterozoic subduction zone, providing new constraints on the mantle sources of volcanic activity in the Jemez Lineament. | es_ES |
dc.description.sponsorship | Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT) Japan Society for the Promotion of Science | es_ES |
dc.language.iso | eng | es_ES |
dc.publisher | Elsevier | es_ES |
dc.rights | Atribución 3.0 España | * |
dc.rights.uri | http://creativecommons.org/licenses/by/3.0/es/ | * |
dc.subject | Flux melting | es_ES |
dc.subject | Open-system melting model | es_ES |
dc.subject | Reactive channeling instability | es_ES |
dc.subject | Pressure-solution creep | es_ES |
dc.subject | Tectonic reactivation | es_ES |
dc.subject | Jemez Lineament | es_ES |
dc.title | Systematic LREE enrichment of mantle harzburgites: The petrogenesis of San Carlos xenoliths revisited | es_ES |
dc.type | info:eu-repo/semantics/article | es_ES |
dc.rights.accessRights | info:eu-repo/semantics/openAccess | es_ES |
dc.identifier.doi | 10.1016/j.lithos.2021.106195 | |
dc.type.hasVersion | info:eu-repo/semantics/publishedVersion | es_ES |