Metamorphic petrology and zircon geochronology of high-grade rocks from the central Mozambique Belt of Tanzania: crustal recycling of Archean and Palaeoproterozoic material during the Pan-African orogeny

H. Sommer, A. Kroner, C. Hauzenberger, S. Muhongo, Michael Wingate

    Research output: Contribution to journalArticle

    72 Citations (Scopus)

    Abstract

    New data on the metamorphic petrology and zircon geochronology of high-grade rocks in the central Mozambique Belt (MB) of Tanzania show that this part of the orogen consists of Archean and Palaeoproterozoic material that was structurally reworked during the Pan-African event. The metamorphic rocks are characterized by a clockwise P-T path, followed by strong decompression, and the time of peak granulite facies metamorphism is similar to other granulite terranes in Tanzania. The predominant rock types are mafic to intermediate granulites, migmatites, granitoid orthogneisses and kyanite/sillimanite-bearing metapelites. The meta-granitoid rocks are of calc-alkaline composition, range in age from late Archean to Neoproterozoic, and their protoliths were probably derived from magmatic arcs during collisional processes. Mafic to intermediate granulites consist of the mineral assemblage garnet-clinopyroxene-plagioclase-quartz-biotite-amphibole +/- K-feldspar +/- orthopyroxene +/- oxides. Metapelites are composed of garnet-biotite-plagioclase +/- K-feldspar +/- kyanite/sillimanite +/- oxides. Estimated values for peak granulite facies metamorphism are 12-13 kbar and 750-800degreesC. Pressures of 5-8 kbar and temperatures of 550-700degreesC characterize subsequent retrogression to amphibolite facies conditions. Evidence for a clockwise P-T path is provided by late growth of sillimanite after kyanite in metapelites. Zircon ages indicate that most of the central part of the MB in Tanzania consists of reworked ancient crust as shown by Archean (c. 2970-2500 Ma) and Palaeoproterozoic (c. 2124-1837 Ma) protolith ages. Metamorphic zircon from metapelites and granitoid orthogneisses yielded ages of c. 640 Ma which are considered to date peak regional granulite facies metamorphism during the Pan-African orogenic event. However, the available zircon ages for the entire MB in East Africa and Madagascar also document that peak metamorphic conditions were reached at different times in different places. Large parts of the MB in central Tanzania consist of Archean and Palaeoproterozoic material that was reworked during the Pan-African event and that may have been part of the Tanzania Craton and Usagaran domain farther to the west.
    Original languageEnglish
    Pages (from-to)915-934
    JournalJournal of Metamorphic Geology
    Volume21
    Issue number9
    DOIs
    Publication statusPublished - 2003

    Fingerprint

    crustal recycling
    Geochronology
    Petrology
    Pan African orogeny
    petrology
    geochronology
    metapelite
    Recycling
    Archean
    zircon
    Rocks
    kyanite
    sillimanite
    granulite facies
    granitoid
    Garnets
    metamorphism
    rock
    Oxides
    protolith

    Cite this

    @article{55e58f0174a94d02bd966c6c2dd2a2da,
    title = "Metamorphic petrology and zircon geochronology of high-grade rocks from the central Mozambique Belt of Tanzania: crustal recycling of Archean and Palaeoproterozoic material during the Pan-African orogeny",
    abstract = "New data on the metamorphic petrology and zircon geochronology of high-grade rocks in the central Mozambique Belt (MB) of Tanzania show that this part of the orogen consists of Archean and Palaeoproterozoic material that was structurally reworked during the Pan-African event. The metamorphic rocks are characterized by a clockwise P-T path, followed by strong decompression, and the time of peak granulite facies metamorphism is similar to other granulite terranes in Tanzania. The predominant rock types are mafic to intermediate granulites, migmatites, granitoid orthogneisses and kyanite/sillimanite-bearing metapelites. The meta-granitoid rocks are of calc-alkaline composition, range in age from late Archean to Neoproterozoic, and their protoliths were probably derived from magmatic arcs during collisional processes. Mafic to intermediate granulites consist of the mineral assemblage garnet-clinopyroxene-plagioclase-quartz-biotite-amphibole +/- K-feldspar +/- orthopyroxene +/- oxides. Metapelites are composed of garnet-biotite-plagioclase +/- K-feldspar +/- kyanite/sillimanite +/- oxides. Estimated values for peak granulite facies metamorphism are 12-13 kbar and 750-800degreesC. Pressures of 5-8 kbar and temperatures of 550-700degreesC characterize subsequent retrogression to amphibolite facies conditions. Evidence for a clockwise P-T path is provided by late growth of sillimanite after kyanite in metapelites. Zircon ages indicate that most of the central part of the MB in Tanzania consists of reworked ancient crust as shown by Archean (c. 2970-2500 Ma) and Palaeoproterozoic (c. 2124-1837 Ma) protolith ages. Metamorphic zircon from metapelites and granitoid orthogneisses yielded ages of c. 640 Ma which are considered to date peak regional granulite facies metamorphism during the Pan-African orogenic event. However, the available zircon ages for the entire MB in East Africa and Madagascar also document that peak metamorphic conditions were reached at different times in different places. Large parts of the MB in central Tanzania consist of Archean and Palaeoproterozoic material that was reworked during the Pan-African event and that may have been part of the Tanzania Craton and Usagaran domain farther to the west.",
    author = "H. Sommer and A. Kroner and C. Hauzenberger and S. Muhongo and Michael Wingate",
    year = "2003",
    doi = "10.1046/j.1525-1314.2003.00491.x",
    language = "English",
    volume = "21",
    pages = "915--934",
    journal = "Journal of Metamorphic Geology",
    issn = "0263-4929",
    publisher = "Wiley-Blackwell",
    number = "9",

    }

    TY - JOUR

    T1 - Metamorphic petrology and zircon geochronology of high-grade rocks from the central Mozambique Belt of Tanzania: crustal recycling of Archean and Palaeoproterozoic material during the Pan-African orogeny

    AU - Sommer, H.

    AU - Kroner, A.

    AU - Hauzenberger, C.

    AU - Muhongo, S.

    AU - Wingate, Michael

    PY - 2003

    Y1 - 2003

    N2 - New data on the metamorphic petrology and zircon geochronology of high-grade rocks in the central Mozambique Belt (MB) of Tanzania show that this part of the orogen consists of Archean and Palaeoproterozoic material that was structurally reworked during the Pan-African event. The metamorphic rocks are characterized by a clockwise P-T path, followed by strong decompression, and the time of peak granulite facies metamorphism is similar to other granulite terranes in Tanzania. The predominant rock types are mafic to intermediate granulites, migmatites, granitoid orthogneisses and kyanite/sillimanite-bearing metapelites. The meta-granitoid rocks are of calc-alkaline composition, range in age from late Archean to Neoproterozoic, and their protoliths were probably derived from magmatic arcs during collisional processes. Mafic to intermediate granulites consist of the mineral assemblage garnet-clinopyroxene-plagioclase-quartz-biotite-amphibole +/- K-feldspar +/- orthopyroxene +/- oxides. Metapelites are composed of garnet-biotite-plagioclase +/- K-feldspar +/- kyanite/sillimanite +/- oxides. Estimated values for peak granulite facies metamorphism are 12-13 kbar and 750-800degreesC. Pressures of 5-8 kbar and temperatures of 550-700degreesC characterize subsequent retrogression to amphibolite facies conditions. Evidence for a clockwise P-T path is provided by late growth of sillimanite after kyanite in metapelites. Zircon ages indicate that most of the central part of the MB in Tanzania consists of reworked ancient crust as shown by Archean (c. 2970-2500 Ma) and Palaeoproterozoic (c. 2124-1837 Ma) protolith ages. Metamorphic zircon from metapelites and granitoid orthogneisses yielded ages of c. 640 Ma which are considered to date peak regional granulite facies metamorphism during the Pan-African orogenic event. However, the available zircon ages for the entire MB in East Africa and Madagascar also document that peak metamorphic conditions were reached at different times in different places. Large parts of the MB in central Tanzania consist of Archean and Palaeoproterozoic material that was reworked during the Pan-African event and that may have been part of the Tanzania Craton and Usagaran domain farther to the west.

    AB - New data on the metamorphic petrology and zircon geochronology of high-grade rocks in the central Mozambique Belt (MB) of Tanzania show that this part of the orogen consists of Archean and Palaeoproterozoic material that was structurally reworked during the Pan-African event. The metamorphic rocks are characterized by a clockwise P-T path, followed by strong decompression, and the time of peak granulite facies metamorphism is similar to other granulite terranes in Tanzania. The predominant rock types are mafic to intermediate granulites, migmatites, granitoid orthogneisses and kyanite/sillimanite-bearing metapelites. The meta-granitoid rocks are of calc-alkaline composition, range in age from late Archean to Neoproterozoic, and their protoliths were probably derived from magmatic arcs during collisional processes. Mafic to intermediate granulites consist of the mineral assemblage garnet-clinopyroxene-plagioclase-quartz-biotite-amphibole +/- K-feldspar +/- orthopyroxene +/- oxides. Metapelites are composed of garnet-biotite-plagioclase +/- K-feldspar +/- kyanite/sillimanite +/- oxides. Estimated values for peak granulite facies metamorphism are 12-13 kbar and 750-800degreesC. Pressures of 5-8 kbar and temperatures of 550-700degreesC characterize subsequent retrogression to amphibolite facies conditions. Evidence for a clockwise P-T path is provided by late growth of sillimanite after kyanite in metapelites. Zircon ages indicate that most of the central part of the MB in Tanzania consists of reworked ancient crust as shown by Archean (c. 2970-2500 Ma) and Palaeoproterozoic (c. 2124-1837 Ma) protolith ages. Metamorphic zircon from metapelites and granitoid orthogneisses yielded ages of c. 640 Ma which are considered to date peak regional granulite facies metamorphism during the Pan-African orogenic event. However, the available zircon ages for the entire MB in East Africa and Madagascar also document that peak metamorphic conditions were reached at different times in different places. Large parts of the MB in central Tanzania consist of Archean and Palaeoproterozoic material that was reworked during the Pan-African event and that may have been part of the Tanzania Craton and Usagaran domain farther to the west.

    U2 - 10.1046/j.1525-1314.2003.00491.x

    DO - 10.1046/j.1525-1314.2003.00491.x

    M3 - Article

    VL - 21

    SP - 915

    EP - 934

    JO - Journal of Metamorphic Geology

    JF - Journal of Metamorphic Geology

    SN - 0263-4929

    IS - 9

    ER -