Pan-African high pressure isobaric cooling: evidence from the mineralogy and thermobarometry of the granulite-facies rocks from the Uluguru Mountains, eastern Tanzania

Muhongo, S.; Tuisku, Pekka

doi:10.1016/s0899-5362(97)00012-2

Cited by 20 publications

(11 citation statements)

References 34 publications

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“…The analytical procedure is described in Muhongo and Tuisku (1996). A few hundred mineral analysis were performed with wide area coverage of the LGB.…”

Section: Methodsmentioning

confidence: 99%

Evolution of migmatitic granulite complexes: Implications from Lapland Granulite Belt, Part I: Metamorphic geology

Tuisku¹,

Mikkola²,

Huhma³

2006

Bull Geol Soc Finland

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The Palaeoproterozoic Lapland granulite belt was juxtaposed between Archaean and Proterozoic terrains in the NE part of the Fennoscandian Shield concurrently with the accretion of Svecofennian arc complexes at ~1.9 Ga. The belt consists mainly of aluminous migmatitic metagreywackes. Abundant noritic to enderbitic magmas were intruded concordantly into the metasediments and were probably an important heat source for metamorphism, which took place during the crystallization of the magmas. This is supported by structural and contact relations of metasediments and igneous rocks, and by the lack progressive metamorphic reaction textures in the igneous rock series. The peak of metamorphism took place above the dehydration melting temperature of the biotite-sillimanite-plagioclase-quartz assemblage at 750−850°C and 5−8.5 kbar which lead to formation of a restitic palaeosome and peraluminous granitic melt in metapelites. Subsequently, the rocks were decompressed and cooled below the wet melting temperature of pelitic rocks (650°C) under the stability fi eld of andalusite coexisting with potassium feldspar (2−3 kbar). Cooling was accompanied by the crystallization of the neosomes, often carrying aluminium-rich phases. Postmetamorphic duplexing of the LGB is clearly seen in the distribution of calculated PT conditions.

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“…The analytical procedure is described in Muhongo and Tuisku (1996). A few hundred mineral analysis were performed with wide area coverage of the LGB.…”

Section: Methodsmentioning

confidence: 99%

Evolution of migmatitic granulite complexes: Implications from Lapland Granulite Belt, Part I: Metamorphic geology

Tuisku¹,

Mikkola²,

Huhma³

2006

Bull Geol Soc Finland

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“…The timing of the metamorphic event in high-grade rocks in the ''Eastern Granulites" is also well known through radiometric dating undertaken by Spooner et al (1970), Lenoir (1994), Krö ner et al (2003), Maboko and Nakamura (1995, 2000, Muhongo et al (1987Muhongo et al ( , 2001 and Tenczer et al (2006). Geothermobarometric calculations and mineral textures show evidence for an IBC (Coolen, 1980;Muhongo and Tuisku, 1996;Appel et al, 1998;Muhongo, 1999).…”

Section: Geological Setting and Previous Petrological Studiesmentioning

confidence: 96%

Isothermal decompression history in the “Western Granulite” terrain, central Tanzania: Evidence from reaction textures and trapped fluids in metapelites

Sommer

Hauzenberger

Kröner

et al. 2008

Journal of African Earth Sciences

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“…Close to the eastern margin of the Tanzanian craton, Neoproterozoic metamorphism of high pressure granulite facies was reported (Muhongo and Tuisku, 1996;Appel et al, 1998;Möller et al, 2000;Cutten et al, 2006;Sommer et al, 2008). Thermobarometric results and isotopic dating revealed anticlockwise P-T-t paths, where conditions of peak metamorphism give a pressure range between 0.9 and 1.2 GPa at 800°C.…”

Section: Eclogites and Granulitesmentioning

confidence: 97%

“…Jaupart and Mareschal, 1999). A: P-T-t path (dotted curve) for eclogites from the Usagaran and Ubende belts (Möller et al,1995;Collins et al, 2004); B: P-T-t path for granulites from the western Mozambique belt (Cutten et al, 2006); C: P-T-t path (dashed curve) for granulites from the eastern Mozambique belt (Appel et al,1998); D: P-T-t path for metapelites from eastern Mozambique belt (Sommer et al, 2008); E: Ultramafic granulites from Uluguru mountains, eastern Tanzania (Muhongo and Tuisku, 1996); F: Metagabbros from the Ubendian belt, south-western Tanzania (Muhongo et al, 2002); G: Ruby-bearing rocks from Southwest Madagascar (Mercier et al, 1999b); H: Ruby-bearing rocks from SE Kenya (Mercier et al, 1999a). I: Stability of Crn+Qtz (Shaw and Arima, 1998;Schenk et al, 2004) and of Crn+Grt+Cpx in ruby-bearing rocks of Madagascar (Rakotondrazafy et al, 2006); J and K: ultrahigh temperature metamorphism at southern and northern edges of Tanzanian craton (Sandiford et al, 1987;Schenk et al, 2004).…”

Section: Accepted M Manuscriptmentioning

confidence: 99%

Plume-induced dynamic instabilities near cratonic blocks: Implications for P–T–t paths and metallogeny

Guillou-Frottier

Burov

Cloetingh

et al. 2012

Global and Planetary Change

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et al.. Plume-induced dynamic instabilities near cratonic blocks: implications for P-Tt paths and metallogeny. Global and Planetary Change, Elsevier, 2012, 90-91, pp.37-50. 10.1016/j.gloplacha.2011 ÔØ Å ÒÙ× Ö ÔØ Plume-induced dynamic instabilities near cratonic blocks: Implications for P-T-t paths and metallogeny This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT2 AbstractPlume head -lithosphere interactions around cratonic blocks result in thermo-mechanical disturbances that lead to heating and burial phases of crustal rocks. We present results from numerical models of plume head -cratonic blocks interactions where a free upper surface condition and realistic rheologies are accounted for. These models include distinct cratonic blocks embedded within a continental lithosphere and separated by several hundreds of kilometres. Surface topography, thermal field and effective viscosity values are tracked for 20Myr of interactions. The modelled dynamic interaction of a plume head around cratonic blocks results in two main types of instabilities, each of them resulting in a distinct P-T-t path.The "slab-like" instability, focused on cratonic edges when plume head is away from the craton centre, shows a near-isothermal burial phase, while the "drip-like" instability occurring above plume head material results in a near-isobaric heating phase. Consequently, both clockwise and counterclockwise P-T-t paths can be expected around cratons, as actually observed around the Tanzanian craton and other cratonic areas. Metallogenic data from gemstone-bearing rocks in south-east Africa and data from ultrahigh temperature and ultrahigh pressure metamorphism are compatible with our model. It appears that vertical mantle dynamics around cratons may also explain thermobarometric signatures that are often attributed to horizontal tectonics.

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Pan-African high pressure isobaric cooling: evidence from the mineralogy and thermobarometry of the granulite-facies rocks from the Uluguru Mountains, eastern Tanzania

Cited by 20 publications

References 34 publications

Evolution of migmatitic granulite complexes: Implications from Lapland Granulite Belt, Part I: Metamorphic geology

Evolution of migmatitic granulite complexes: Implications from Lapland Granulite Belt, Part I: Metamorphic geology

Isothermal decompression history in the “Western Granulite” terrain, central Tanzania: Evidence from reaction textures and trapped fluids in metapelites

Plume-induced dynamic instabilities near cratonic blocks: Implications for P–T–t paths and metallogeny

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