Título:	Recycling process and proto-kimberlite melt metasomatism in the lithosphere-asthenosphere boundary beneath the Amazonian Craton recorded by garnet xenocrysts and mantle xenoliths from the Carolina kimberlite
Autor(es):	Gervasoni, Fernanda Jalowitzki, Tiago Luís Reis Rocha, Marcelo Peres Weska, Ricardo Kalikowski Rodrigues, Eduardo Novais Rodrigues, Rodrigo Antonio de Freitas Yannick Bussweiler Elisa Soares Rocha Barbosa Jasper Berndt Elton Luiz Dantas Valmir da Silva Souza Stephan Klemme
ORCID:	https://orcid.org/0000-0002-9533-4008 https://orcid.org/0000-0002-8107-7055
Afiliação do autor:	Universidade Federal de Pelotas, Centro de Engenharias Universidade Federal do Rio Grande do Sul, Programa de Pós-graduação em Geociências Universidade de Brasília, Instituto de Geociências, Programa de Pós-graduação em Geologia Universidade de Brasília, Instituto de Geociências, Programa de Pós-graduação em Geologia Universidade Federal do Mato Grosso, Faculdade de Geociências Universidade de Brasília, Instituto de Geociências, Programa de Pós-graduação em Geologia Universidade de Brasília, Instituto de Geociências, Programa de Pós-graduação em Geologia Universität zu Köln, Institut für Geologie und Mineralogie, Germany Faculdade de Ciências e Tecnologia, Universidade Federal de Goiás Universität Münster, Institut für Mineralogie, Münster, Germany Universidade de Brasília, Instituto de Geociências, Programa de Pós-graduação em Geologia Universidade de Brasília, Instituto de Geociências, Programa de Pós-graduação em Geologia Universität Münster, Institut für Mineralogie, Münster, Germany
Assunto:	Xenólitos mantélicos Craton amazônico Metassomatismo
Data de publicação:	2022
Editora:	Elsevier B. V.
Referência:	GERVASONI, Fernanda et al. Recycling process and proto-kimberlite melt metasomatism in the lithosphere-asthenosphere boundary beneath the Amazonian Craton recorded by garnet xenocrysts and mantle xenoliths from the Carolina kimberlite. Geoscience Frontiers, [S. l.], v. 13, n. 5, 101429, set. 2022. DOI: https://doi.org/10.1016/j.gsf.2022.101429. Disponível em: https://www.sciencedirect.com/science/article/pii/S1674987122000822?via%3Dihub. Acesso em: 27 set. 2024.
Abstract:	Here we present new data on the major and trace element compositions of silicate and oxide minerals from mantle xenoliths brought to the surface by the Carolina kimberlite, Pimenta Bueno Kimberlitic Field, which is located on the southwestern border of the Amazonian Craton. We also present Sr-Nd iso- topic data of garnet xenocrysts and whole-rocks from the Carolina kimberlite. Mantle xenoliths are mainly clinopyroxenites and garnetites. Some of the clinopyroxenites were classified as GPP–PP–PKP (garnet-phlogopite peridotite, phlogopite-peridotite, phlogopite-K-richterite peridotite) suites, and two clinopyroxenites (eclogites) and two garnetites are relicts of an ancient subducted slab. Temperature and pressure estimates yield 855–1102 °C and 3.6–7.0 GPa, respectively. Clinopyroxenes are enriched in light rare earth elements (LREE) (LaN/Yb N = 5–62; CeN/SmN = 1–3; where N = primitive mantle normal- ized values), they have high Ca/Al ratios (10–410), low to medium Ti/Eu ratios (742–2840), and low Zr/Hf ratios (13–26), which suggest they were formed by metasomatic reactions with CO 2-rich silicate melts. Phlogopite with high TiO 2 (>2.0 wt.%), Al 2O 3 (>12.0 wt.%), and FeOt (5.0–13.0 wt.%) resemble those found in the groundmass of kimberlites, lamproites and lamprophyres. Conversely, phlogopite with low TiO 2 (<1.0 wt.%) and lower Al2O 3 (<12.0 wt.%) are similar to those present in GPP-PP-PKP, and in MARID (mica-amphibole-rutile-ilmenite-diopside) and PIC (phlogopite-ilmenite-clinopyorxene) xenoliths. The GPP-PP-PKP suite of xenoliths, together with the clinopyroxene and phlogopite major and trace element signatures suggests that an intense proto-kimberlite melt metasomatism occurred in the deep cratonic lithosphere beneath the Amazonian Craton. The Sr-Nd isotopic ratios of pyrope xenocrysts (G3, G9 and G11) from the Carolina kimberlite are characterized by high 143 Nd/ 144 Nd (0.51287–0.51371) and eNd (+4.55 to +20.85) accompanied with enriched 87 Sr/86 Sr (0.70405–0.71098). These results suggest interac- tion with a proto-kimberlite melt compositionally similar with worldwide kimberlites. Based on Sr-Nd whole-rock compositions, the Carolina kimberlite has affinity with Group 1 kimberlites. The Sm-Nd iso- chron age calculated with selected eclogitic garnets yielded an age of 291.9 ± 5.4 Ma (2 r), which repre- sents the cooling age after the proto-kimberlite melt metasomatism. Therefore, we propose that the lithospheric mantle beneath the Amazonian Craton records the Paleozoic subduction with the attach- ment of an eclogitic slab into the cratonic mantle (garnetites and eclogites); with a later metasomatic event caused by proto-kimberlite melts shortly before the Carolina kimberlite erupted.
Unidade Acadêmica:	Instituto de Geociências (IG)
Programa de pós-graduação:	Programa de Pós-Graduação em Geologia
Licença:	This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
DOI:	https://doi.org/10.1016/j.gsf.2022.101429
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