Finding of talc- and kyanite-bearing amphibolite from the Paleoproterozoic Usagaran Belt, Tanzania

Keiko Mori; Tatsuki Tsujimori; Nelson Boniface

doi:10.2465/jmps.180713

Finding of talc- and kyanite-bearing amphibolite from the Paleoproterozoic Usagaran Belt, Tanzania

Keiko Mori, Tatsuki Tsujimori, Nelson Boniface

CNEAS - Department of Basic Studies

Research output: Contribution to journal › Letter › peer-review

6 Citations (Scopus)

Abstract

We report a newly discovered assemblage of talc-kyanite in an amphibolite from the Isimani Suite of the Paleoproterozoic Usagaran Belt, central Tanzania. The amphibolite is characterized by the mineral assemblage of clinoamphibole, kyanite, talc with minor rutile, quartz, dolomite, and rare barite. The high Fe³⁺/(Fe³⁺ + Fe²⁺) ratio (0.48-0.80) of clinoamphibole and the presence of sulfate (barite) indicate a very-high oxidation state during metamorphism. P-T pseudosection modelling predicts that the studied talc- and kyanite-bearing amphibolites formed at high-pressure conditions (P > 1.0 GPa). Moreover, the modelling suggests formation of talc + kyanite + clinoamphibole at a highly oxidizing condition with CO₂ fluid. This talc-kyanite association provides an index of high-pressure metamorphism of the Usagaran Belt and marks the oldest record of the talc- kyanite association in regional metamorphism in the Earth's history.

Original language	English
Pages (from-to)	316-321
Number of pages	6
Journal	Journal of Mineralogical and Petrological Sciences
Volume	113
Issue number	6
DOIs	https://doi.org/10.2465/jmps.180713
Publication status	Published - 2018 Dec 1

Keywords

Amphibolite
High-pressure metamorphism
Kyanite
Talc
Tanzania
Usagaran Belt

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10.2465/jmps.180713

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@article{3e61d4f9ed114c1f9d1152cff1e36fcb,

title = "Finding of talc- and kyanite-bearing amphibolite from the Paleoproterozoic Usagaran Belt, Tanzania",

abstract = "We report a newly discovered assemblage of talc-kyanite in an amphibolite from the Isimani Suite of the Paleoproterozoic Usagaran Belt, central Tanzania. The amphibolite is characterized by the mineral assemblage of clinoamphibole, kyanite, talc with minor rutile, quartz, dolomite, and rare barite. The high Fe3+/(Fe3+ + Fe2+) ratio (0.48-0.80) of clinoamphibole and the presence of sulfate (barite) indicate a very-high oxidation state during metamorphism. P-T pseudosection modelling predicts that the studied talc- and kyanite-bearing amphibolites formed at high-pressure conditions (P > 1.0 GPa). Moreover, the modelling suggests formation of talc + kyanite + clinoamphibole at a highly oxidizing condition with CO2 fluid. This talc-kyanite association provides an index of high-pressure metamorphism of the Usagaran Belt and marks the oldest record of the talc- kyanite association in regional metamorphism in the Earth's history.",

keywords = "Amphibolite, High-pressure metamorphism, Kyanite, Talc, Tanzania, Usagaran Belt",

author = "Keiko Mori and Tatsuki Tsujimori and Nelson Boniface",

note = "Funding Information: This research was supported by the Center for Northeast Asian Studies, Tohoku University and the University of Dar es Salaam in part by grants from the MEXT/JSPS KAKENHI (JP16H01123 and JP18H01299) to T. Tsuji-mori. We thank Kazumasa Aoki and Rustam Orozbaev who have critically reviewed this manuscript and Takao Hirajima for constructive editorial evaluation. We extend our appreciation to Leander Franz for sharing the solid– solution model of yoderite. T. Tsujimori and N. Boniface thank R. Kinyaiya for driving us safely in a Toyota LandCruiser 70 in difficult but beautiful fields. Publisher Copyright: {\textcopyright} 2018 Japan Association of Mineralogical Sciences.",

year = "2018",

month = dec,

day = "1",

doi = "10.2465/jmps.180713",

language = "English",

volume = "113",

pages = "316--321",

journal = "Journal of Mineralogical and Petrological Sciences",

issn = "1345-6296",

publisher = "Tohoku University",

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TY - JOUR

T1 - Finding of talc- and kyanite-bearing amphibolite from the Paleoproterozoic Usagaran Belt, Tanzania

AU - Mori, Keiko

AU - Tsujimori, Tatsuki

AU - Boniface, Nelson

N1 - Funding Information: This research was supported by the Center for Northeast Asian Studies, Tohoku University and the University of Dar es Salaam in part by grants from the MEXT/JSPS KAKENHI (JP16H01123 and JP18H01299) to T. Tsuji-mori. We thank Kazumasa Aoki and Rustam Orozbaev who have critically reviewed this manuscript and Takao Hirajima for constructive editorial evaluation. We extend our appreciation to Leander Franz for sharing the solid– solution model of yoderite. T. Tsujimori and N. Boniface thank R. Kinyaiya for driving us safely in a Toyota LandCruiser 70 in difficult but beautiful fields. Publisher Copyright: © 2018 Japan Association of Mineralogical Sciences.

PY - 2018/12/1

Y1 - 2018/12/1

N2 - We report a newly discovered assemblage of talc-kyanite in an amphibolite from the Isimani Suite of the Paleoproterozoic Usagaran Belt, central Tanzania. The amphibolite is characterized by the mineral assemblage of clinoamphibole, kyanite, talc with minor rutile, quartz, dolomite, and rare barite. The high Fe3+/(Fe3+ + Fe2+) ratio (0.48-0.80) of clinoamphibole and the presence of sulfate (barite) indicate a very-high oxidation state during metamorphism. P-T pseudosection modelling predicts that the studied talc- and kyanite-bearing amphibolites formed at high-pressure conditions (P > 1.0 GPa). Moreover, the modelling suggests formation of talc + kyanite + clinoamphibole at a highly oxidizing condition with CO2 fluid. This talc-kyanite association provides an index of high-pressure metamorphism of the Usagaran Belt and marks the oldest record of the talc- kyanite association in regional metamorphism in the Earth's history.

AB - We report a newly discovered assemblage of talc-kyanite in an amphibolite from the Isimani Suite of the Paleoproterozoic Usagaran Belt, central Tanzania. The amphibolite is characterized by the mineral assemblage of clinoamphibole, kyanite, talc with minor rutile, quartz, dolomite, and rare barite. The high Fe3+/(Fe3+ + Fe2+) ratio (0.48-0.80) of clinoamphibole and the presence of sulfate (barite) indicate a very-high oxidation state during metamorphism. P-T pseudosection modelling predicts that the studied talc- and kyanite-bearing amphibolites formed at high-pressure conditions (P > 1.0 GPa). Moreover, the modelling suggests formation of talc + kyanite + clinoamphibole at a highly oxidizing condition with CO2 fluid. This talc-kyanite association provides an index of high-pressure metamorphism of the Usagaran Belt and marks the oldest record of the talc- kyanite association in regional metamorphism in the Earth's history.

KW - Amphibolite

KW - High-pressure metamorphism

KW - Kyanite

KW - Talc

KW - Tanzania

KW - Usagaran Belt

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U2 - 10.2465/jmps.180713

DO - 10.2465/jmps.180713

M3 - Letter

AN - SCOPUS:85059264444

SN - 1345-6296

VL - 113

SP - 316

EP - 321

JO - Journal of Mineralogical and Petrological Sciences

JF - Journal of Mineralogical and Petrological Sciences

IS - 6

ER -

Finding of talc- and kyanite-bearing amphibolite from the Paleoproterozoic Usagaran Belt, Tanzania

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Keywords

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