Geochemistry and δ11 B evolution of tourmaline from tourmalinite as a record of oceanic crust in the Tonian Ibaré ophiolite, southern Brasiliano Orogen

Arena, Karine; Hartmann, Léo Afrâneo; Lana, Cristiano; Queiroga, Gláucia Nascimento; Castro, Marco Paulo de

doi:10.1590/0001-3765202020180193

Cited by 8 publications

(4 citation statements)

References 62 publications

(29 reference statements)

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“…Chromite composition is compatible with lower amphibolite facies metamorphism. The tourmalinite is similar to rocks described by Hartmann et al (2019) and Arena et al (2019), because of assemblage with clinochlore and dravite composition. Metamorphic tourmaline is common in amphibolite facies rocks, although the mineral may form in the full range of metamorphic conditions, notably low and medium grade metamorphism (Henry and Dutrow 1996, Berryman et al 2016, Zheng et al 2019.…”

Section: Resultssupporting

confidence: 56%

“…This tripartite division organizes the stratigraphic relationship in the São Gabriel terrane. Additional ophiolites occur in the Porongos foldand-thrust belt both in southernmost Brazil and northeastern Uruguay -Capané (Arena et al 2019), Candiotinha (Xavier et al 2018), Arroio Grande (Ramos and Koester 2015), and Cerro La Tuna (Peel et al 2018).…”

Section: Geological Settingmentioning

confidence: 99%

“…The depletion of the residual ultramafic rocks (metaserpentinite) in most elements (e.g., Al, Ti, Ca, Na) and redeposition within and in host rock of serpentinite leads to the formation of metasomatic rocks, particularly blackwall (rodingite, chloritite). Chloritites are characteristic rocks (e.g., Barriga and Fyfe 1983, Dubińska et al 2004, Arena et al 2017, whereas massive and disseminated tourmaline derives from oceanic fumaroles (e.g., Arena et al 2019. Carbonation of serpentinite in the oceanic crust leads to generation of chromite-talc-magnesite granofels.…”

Section: Introductionmentioning

confidence: 99%

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Mineralogical evolution of the northern Bossoroca ophiolite, São Gabriel terrane

et al. 2020

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Mineralogical evolution of ophiolites is significant to understand paleo-oceanic crust and mantle requiring multi-proxy techniques to identify steps in the processes. We studied the Bossoroca ophiolite from the southern Brasiliano Orogen, a prime example of Tonian accretion to an oceanic island arc. Integration of field geology, aeromagnetometry, aerogamaspectrometry, electron microprobe analyses, and compositional maps of minerals led to the decoding of oceanic and continental processes. The ophiolite is highly magnetic and low-K and is positioned at the base of the superstructure. We studied amphibolite, tourmalinite, and chromite-talc-magnesite granofels from the ophiolite, Capivaras diorite from the Cambaí Complex infrastructure and one metavolcanoclastic rock from the Vacacaí Group superstructure. Honblende is zoned in all rock types. Low-Ti hornblende is compatible with medium-pressure metamorphism at 7 kbar. This M1 to M2 amphibolite facies resulted in the widespread association of olivine + talc in metaserpentinite. Dravite is similar to tourmaline from the Ibaré ophiolite. Andesine and oligoclase are dominant and albite minor. Cr-spinel in granofels recrystallized in greenschist facies; host rock originated by carbonatization of serpentinite formed in the oceanic crust along with chloritite and tourmalinite. Serpentinite rare earth elements (REE) suggest origin in depleted mantle peridotite. The ophiolite evolved in the Adamastor Ocean until incorporation into the island arc.

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Section: Resultssupporting

confidence: 56%

Section: Geological Settingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Mineralogical evolution of the northern Bossoroca ophiolite, São Gabriel terrane

et al. 2020

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“…These genetic processes influence the tourmaline composition and manifest in certain compositional trends. For example, tourmalinites associated with evaporites typically display the oxy-dravite-povondraite trend (Frimmel and Jiang 2001;Henry et al 2008;Bačík et al 2008), whereas regional metasomatic tourmalinites usually contain schorl-dravite with the Fe/(Fe + Mg) ratio resulting mostly from the geochemical properties of the host rock (Pesquera et al 1999;Bačík et al 2009;Houzar et al 2014;Yücel-Öztürk et al 2015;Arena et al 2020;Nabelek 2021). Tourmaline from contact-metasomatic tourmalinites associated with granitic intrusions is also in the schorl-dravite trend but usually shifted towards schorl and even foitite (Smith and Yardley 1996;Bosi et al 2018).…”

Section: Genetic Environment and Evolution Of Tourmalinitesmentioning

confidence: 99%

Crystal chemistry and evolution of tourmaline in tourmalinites from Zlatá Idka, Slovakia

Bačík¹,

Odzín²,

Uher³

et al. 2022

J. Geosci.

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Tourmalinites occur in early-Paleozoic metamorphic rocks of the Gemeric Unit near Zlatá Idka village, Western Carpathians, eastern Slovakia. Tourmaline compositions, analyzed with the electron microprobe, include a wide range of tourmaline species. Tourmaline in tourmalinites from Zlatá Idka is compositionally variable, with the dominant substitution Mg-Fe 2+ consistent with prevalent schorl-dravite compositions and their fluor-and oxy-dominant counterparts -fluorschorl, fluor-dravite, oxy-schorl and oxy-dravite. Portions of tourmaline are enriched in Ca in the form of the fluor-uvite and magnesio-lucchesiite components. A subset of the compositions has Ti > 0.25 atoms per formula unit (apfu) and corresponds to the hypothetical "magnesio-dutrowite", Mg-dominant analogue of dutrowite. In addition, some of the tourmalines are X-site vacant and classified as foitite. The crystal chemistry of tourmaline is complex and influenced by several exchange mechanisms, including Mg(Fe) -

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Oceanic crust and mantle evidence for the evolution of Tonian-Cryogenian ophiolites, southern Brasiliano Orogen

Werle

Hartmann

Queiroga

et al. 2020

Precambrian Research

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Geochemistry and δ11 B evolution of tourmaline from tourmalinite as a record of oceanic crust in the Tonian Ibaré ophiolite, southern Brasiliano Orogen

Cited by 8 publications

References 62 publications

Mineralogical evolution of the northern Bossoroca ophiolite, São Gabriel terrane

Mineralogical evolution of the northern Bossoroca ophiolite, São Gabriel terrane

Crystal chemistry and evolution of tourmaline in tourmalinites from Zlatá Idka, Slovakia

Oceanic crust and mantle evidence for the evolution of Tonian-Cryogenian ophiolites, southern Brasiliano Orogen

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