Internally consistent estimates of pressure and temperature; the staurolite problem

Pigage, Lee C.; Greenwood, H. J.

doi:10.2475/ajs.282.7.943

Cited by 127 publications

(89 citation statements)

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“…A temperature of 600-625 °C was calculated for migmatitic gneiss and 700-860 °C for migmatitic schist. Temperatures estimated using calibrations by Ferry and Spear (1978), Pigage and Greenwood (1982) and Hodges and Spear (1982) are higher than those from calibrations of Bhattacharya et al (1992) and Thompson (1976), while temperatures from the calibration of Indares and Martignole (1985) are systematically lower than the results from the other calibrations. The higher temperatures are an artifact of the high Ti content in biotite (Indares and Martignole 1985).…”

Section: P-t Conditions Of Pan-african Orogeny In Southeastern Nigericontrasting

confidence: 44%

P-T conditions of Pan-African orogeny in southeastern Nigeria

Ephraim¹,

Ekwueme²,

Moazzen³

et al. 2008

Central European Geology

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Different rock types from the area northeast of Obudu, southeastern Nigeria were investigated in order to place constraints on their metamorphic conditions. Detailed petrographic studies indicate four main rock groups in the studied area, namely migmatitic gneiss, migmatitic schist, granite gneiss and a minor amount of amphibolite, metagabbro and dolerite. The chemistry of minerals in these rocks is used to estimate metamorphic pressure and temperature (P-T) using appropriate geothermometers and geobarometers. The estimated temperature for migmatitic gneiss of the area is 600-625 °C and 600-650 °C for migmatitic schist; the pressure is ~ 8 kbar. For amphibolite the temperature is ~600-700 °C and pressure is 8-12 kbar. The estimated pressures and temperatures for the northeast Obudu rocks correspond to upper amphibolite to lower granulite facies metamorphism. The metamorphism occurred due to continent-continent collision during the Pan-African orogeny, most likely during the D1 deformational phase of the area. The recorded high pressures possibly resulted from crustal thickening in the area. P-T conditions for Pan-African orogeny in northeast Obudu area are in good agreement with P-T estimations for the Pan-African event in adjacent areas.

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Section: P-t Conditions Of Pan-african Orogeny In Southeastern Nigericontrasting

confidence: 44%

P-T conditions of Pan-African orogeny in southeastern Nigeria

Ephraim¹,

Ekwueme²,

Moazzen³

et al. 2008

Central European Geology

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“…Associated slates show a Mn-rich garnetbiotite assemblage. Analysis of the mineral chemistry using the equilibrium Mg/Fe 2 § exchange relationship between co-existing garnet and biotite has allowed application of the solid solution garnet-biotite geothermometer of Pigage and Greenwood (1982), modified after Ferry and Spear (1978). Temperatures in the order of 450 (+ 50)~ have been calculated (Primmer, 1984) for three mineral pairs within one sample.…”

Section: Northern Beltmentioning

confidence: 99%

A transition from diagenesis to greenschist facies within a major Variscan fold/thrust complex in SW England

Primmer

1985

Mineral. mag.

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ABSTRACT. The north coast of Cornwall, from Bude to Newquay, provides a continuous section through a major Variscan fold/thrust complex. Illite crystallinity studies have revealed a transition from diagenesis in the north to greenschist facies metamorphism in the south in the Upper Palaeozoic succession. More detailed studies of mineral assemblages in both metabasites and pelitic rocks support the regional pattern of metamorphism indicated by illite crystallinity, and show that locally in the Tintagel district, the grade of metamorphism may have reached middle to upper greenschist facies. An attempt to correlate the above data with temperatures (108-985~ derived from O-isotope geothermometers is made. Interpretation of the metamorphic data presented helps to emphasize the tectonic importance of the major structures seen in the fold/thrust complex. KEVWORDS: diagenesis, greenschist facies, illite, Variscan, Cornwall, England.THE geology of south-west England is dominated by a largely clastic sequence of Upper Palaeozoic sediments that has suffered a polyphase deforrnational history as a result of Variscan orogenic activity. In this context a study of the extent to which these sediments have been altered by burial and tectonism may help elucidate the complex pattern of structures in south-west England.The coastal section between Newquay and Bude ( fig. 1) has been chosen to demonstrate the degree of low-temperature alteration as it displays a continuous section through a major Variscan fold/ thrust complex. Here the rocks show both the greatest range in age (Lower Devonian to Upper Carboniferous) and variability in structural style. Brazier et aL (1979) Copyright the Mineralogical SocietyDevonian and Lower Carboniferous rocks in the Tintagel area and lower grades, anchizone to diagenetic zone for Upper Carboniferous rocks to the north. Descriptions of greenscbist facies mineral assemblages in the Tintagel area (Robinson and Read, 1981) support earlier observations (Tilley, 1925;Phillips, 1928) and confirm that the highest grade metamorphic effects occurred in that area. A more detailed study using similar techniques is made here and isotopic geothermometers are also used to provide more detailed information which is interpreted in the light of recent structural and tectonic syntheses.Layer silicate mineralogy and crystallinity determinations. XRD analysis of 122 samples shows that throughout the Devonian slates the < 2/tm~phyllo-silicate assemblage is dominated by a 10 A illite/ muscovite phase and chlorite with minor occurrences of pyrophyllite ( fig. 2). Chlorite-free assemblages are found in black, Lower Carboniferous slates, but the greatest variety of assemblage is found in the Upper Carboniferous, Crackington and Bude Formations. The uniformity in mineralogy throughout rocks of Devonian age suggests that there is a low-temperature metamorphic influence, with rocks in the illite-chlorite zone of Velde (1977), and indicating that temperatures must have exceeded 200~ This contrasts sharply with the very rapi...

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“…Pyrope contents of garnet porphyroblast in the pelitic gneiss increase from core to rim (Fig. 2D) Ferry and Spear (1978); TPL83, Perchuk and Lavrent'eva (1983); TPG82, Pigage and Greenwood (1982); PNH81, Newton and Haselton (1981): PP85, Perchuk et al (1985); THB94, Holland and Blundy (1994). (Table 1).…”

Section: P-t Conditionsmentioning

confidence: 97%

“…We used the chemical data of the rim part of the garnet porphyroblast and those of the core part of other minerals. Applicable geothermometers are garnet -biotite (Ferry and Spear, 1978;Pigage and Greenwood, 1982;Perchuk and Lavrent'eva, 1983) and amphibole -plagioclase (Holland and Blundy, 1994). Pressure was estimated by garnetsillimanite -plagioclase -quartz geobarometer proposed by Newton and Haselton (1981) and Perchuk et al, (1985).…”

Section: P-t Conditionsmentioning

confidence: 99%

Amphibolite-facies metamorphic rocks of the Mt. Tenzan area, northern Kyushu, Southwest Japan: Correlation with the Higo metamorphic rocks

Yamada

Owada

Osanai

2008

Journal of Mineralogical and Petrological Sciences

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The metamorphic rocks exposed in the Sefuri and Tenzan areas, northwestern Kyushu, are composed mainly of mafic rocks with trace amounts of pelitic, ultramafic and calc -silicate rocks and crystalline limestone occurring as lenses or blocks. These rocks underwent regional metamorphism prior to the Cretaceous intrusive rocks. The metamorphic rocks in the Tenzan area, south of the Sefuri area, underwent amphibolite -facies metamorphism and estimated metamorphic P -T conditions of these rocks reach up to 700 °C and 4.0 kbar. On the other hand, the metamorphic conditions in the Sefuri area have been reported to be up to 850 °C and 5.5 kbar. The metamorphic P -T -t path of northwestern Kyushu is interpreted as a clockwise trajectory. These P -T conditions and lithological features suggest that the metamorphic rocks of northwestern Kyushu can be correlated with those of the Higo metamorphic terrane, which is thought to be a candidate of the eastern extension of collision zone between the North China and the South China cratons during Late Permian to the Triassic periods.

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Internally consistent estimates of pressure and temperature; the staurolite problem

Cited by 127 publications

References 0 publications

P-T conditions of Pan-African orogeny in southeastern Nigeria

P-T conditions of Pan-African orogeny in southeastern Nigeria

A transition from diagenesis to greenschist facies within a major Variscan fold/thrust complex in SW England

Amphibolite-facies metamorphic rocks of the Mt. Tenzan area, northern Kyushu, Southwest Japan: Correlation with the Higo metamorphic rocks

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