Stability and paragenesis of Fe-Ti oxide minerals and sphene in the basic schists of the Sanbagawa metamorphic belt in central Shikoku, Japan.

Itaya, Tetsumaru; Otsuki, Michio

doi:10.2465/ganko1941.73.359

Cited by 11 publications

(4 citation statements)

References 16 publications

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“…Hematite coexisting with ilmenite in specimen 2K has 30 ± 2 mole% ilmenite solid solution. This composition and the Fe-Ti ox jd e assemblages observed here are very similar to those of the high-grade zones of the Sanbagawa belt, as reported by Itaya and Otsuki (1978).…”

Section: Mineralogysupporting

confidence: 89%

Phase petrology of eclogitic rocks in the Fairbanks district, Alaska

Brown¹,

Forbes²

1986

Geological Society of America Memoirs

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The eclogitic terrane near Fairbanks, Alaska, consists of interlayered basic, calcmagnesian, quartzose, and pelitic schists, providing an opportunity to evaluate mineral parageneses in a diverse suite of high pressure metamorphic rocks. The terrane is interpreted to have equilibrated at 600 ± 25°C and 15 ± 2 kbars based on: 1) the jadeite content of omphacite coexisting with quartz + albite and 2) the pelitic assemblage garnet + chloritoid + staurolite + kyanite + quartz. The Ellis and Green (1979) calibration of Ko-Fe/Mg of garnet/pyroxene also gives a 600°C temperature for basic schists where ^Sa = -30. However, the application of this geothermometer to calc-magnesian schists, where Xgf ranges up to .47, gives temperatures that are much too high > (700°C). The KQ values show some scatter, but do not systematically vary with the jadeite content of pyroxene in the range from 8 to 45%, or with the grossularite content of garnet from 25 to 47%. Temperatures derived from biotite-garnet KQS with the calibration of Ferry and Spear (1978), are also approximately 600°C. At such temperatures, glaucophane in the Fairbanks eclogites exceeds the maximum stability limit defined by the experimental studies of Maresch (1977).Comparison of the phase relations and inferred P-T of formation of the Fairbanks rocks with those from other high pressure terranes leads to the derivation of pressuredependent equilibria that express the transition from amphibolites of the Sanbagawa belt to the substantially higher pressure kyanite eclogites of the Tauern Window. The Fairbanks eclogitic terrane is intermediate in this progression. REFERENCES CITEDAlbee, A. L., 1965, A petrogenetic grid for the Fe-Mg silicates of pelitic schists:

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Section: Mineralogysupporting

confidence: 89%

Phase petrology of eclogitic rocks in the Fairbanks district, Alaska

Brown¹,

Forbes²

1986

Geological Society of America Memoirs

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“…3). Rutile and ilmenite are common Ti-rich phases in the high-grade zone of the Sanbagawa belt including the albite-biotite zone (e.g., Itaya and Otsuki, 1978;Itaya and Banno, 1980). Additionally, ilmenite and rutile grains contain chlorite as inclusions (Fig.…”

Section: Resultsmentioning

confidence: 99%

Late Cretaceous CHIME monazite ages of Sanbagawa metamorphic rocks from Nushima, Southwest Japan

Suzuki

Enami

Maekawa

et al. 2018

Journal of Mineralogical and Petrological Sciences

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The Sanbagawa metamorphic rocks of epidote-amphibolite facies are extensively exposed in Nushima at the southern end of the Hyogo Prefecture, Japan. Chemical U-Th-total Pb isochron method (CHIME) ages were determined for monazite grains from the Sanbagawa metamorphic rocks. CHIME monazite ages are 92.3 ± 3.2 and 90.3 ± 4.7 Ma for two chlorite-rich rocks collected from the reaction zone between pelitic schists and serpentinites. The monazite grains occur as isolated phases or aggregates with rutile/ilmenite in chlorite-rich matrix, and thus the CHIME monazite ages are interpreted to represent recrystallization close to the peak stage of prograde epidote-amphibolite facies metamorphism. Considering the U-Pb zircon ages reported in literature, the main stage of Sanbagawa prograde metamorphism up to the epidote-amphibolite facies is estimated to have been at 80-92 Ma. Comparison of the age data between the Sanbagawa eclogite and epidote-amphibolite facies stages suggests the possibility that the formation of eclogite facies rocks at different depths and periods of the Sanbagawa subduction continued for more than 20-30 million years.

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“…The system Al,03-Fe0-Mg0-Ca0 with excess of hematite, quartz, albite, muscovite and fluid describes the phase relations of hematite-bearing basic schists. The fluid attending the Sanbagawa metamorphism is generally believed to have been predominantly H 2 0 (Emst, 1972;Itaya & Otsuki, 1978;Itaya & Banno, 1980). At a given PIT in a fourcomponent system, the composition of amphibole that coexists with two minerals, namely epidote and chlorite, has one degree of freedom.…”

Section: Graphic Representationmentioning

confidence: 99%

Prograde and retrograde metamorphism of hematitebearing basic schists in the Sanbagawa belt in central Shikoku

Otsuki

Banno

1990

Journal Metamorphic Geology

147

134

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The mineral assemblages of hematite-bearing basic schists in intermediate high-pressure metamorphism are temperature dependent. For assemblages with excess hematite. albite, muscovite and quartz, the paragenetic relations can be dealt with in terms of a fourcomponent system, without omitting or grouping major components.In the Sanbagawa belt in central Shikoku, the dominant amphibole in the hematite-bearing basic schists changes from winchite, via crossite and barroisite to hornblende. The stability of amphibole is described chemographically within a pseudoternary system with another excess phase, epidote. Many amphiboles are chemically heterogeneous owing to retrograde reactions which produced low-TIP amphibole around the prograde amphibole. The examination of amphibole zoning makes it possible to draw a retrograde P-T trajectory which passes on the lower pressure side of the prograde one.

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Stability and paragenesis of Fe-Ti oxide minerals and sphene in the basic schists of the Sanbagawa metamorphic belt in central Shikoku, Japan.

Cited by 11 publications

References 16 publications

Phase petrology of eclogitic rocks in the Fairbanks district, Alaska

Phase petrology of eclogitic rocks in the Fairbanks district, Alaska

Late Cretaceous CHIME monazite ages of Sanbagawa metamorphic rocks from Nushima, Southwest Japan

Prograde and retrograde metamorphism of hematitebearing basic schists in the Sanbagawa belt in central Shikoku

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