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  

作　　者：Fernanda Gervasoni Tiago Jalowitzki Marcelo Peres Rocha Ricardo Kalikowski Weska Eduardo Novais-Rodrigues Rodrigo Antonio de Freitas Rodrigues Yannick Bussweiler Elisa Soares Rocha Barbosa Jasper Berndt Elton Luiz Dantas Valmir da Silva Souza Stephan Klemme 

机构地区：[1]Centro de Engenharias,Universidade Federal de Pelotas(UFPel),Pelotas,Brazil [2]Programa de Pós-graduação em Geociências,Universidade Federal do Rio Grande do Sul,Porto Alegre,Brazil [3]Programa de Pós-graduação em Geologia,Instituto de Geociências,Universidade de Brasília(UnB),Brasília,Brazil [4]Faculdade de Geociências,Universidade Federal do Mato Grosso(UFMT),Cuiabá,Brazil [5]Institut für Geologie und Mineralogie,Universität zu Köln,Germany [6]Faculdade de Ciências e Tecnologia,Universidade Federal de Goiás(UFG),Aparecida de Goiânia,Brazil [7]Institut für Mineralogie,Universität Münster,Münster,Germany

出　　处：《Geoscience Frontiers》2022年第5期89-105,共17页地学前缘（英文版）

基　　金：supported by FAPDF(Call03/2018;Process n°23568.93.50253.24052018);Serrapilheira Institute(Serra-1709-18152)。

摘　　要：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 isotopic 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℃ and 3.6–7.0 GPa,respectively.Clinopyroxenes are enriched in light rare earth elements(LREE)(La_(N)/Yb_(N)=5–62;Ce_(N)/Sm_(N)=1–3;where N=primitive mantle normalized 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_(2)O_(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 Al_(2)O_(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 interaction with a proto-kim

关 键 词：Carolina kimberlite K-rich mantle xenoliths Ancient subducted slab Proto-kimberlite melt metasomatism 

分 类 号：P542.5[天文地球—构造地质学]