At Farinole, Corsica, birefringent garnet is associated with glaucophane, zoisite, relict omphacite, rutile, ilmenite, titanite and retrograde chlorite. The blueschist blocks give phengite K-Ar ages of around 320 Ma (Tsujimori and Itaya, submitted). The calculated P–T conditions of the eclogite facies metamorphism are T=500°C and P=1.56–2.35 GPa (Li et al., 2006a), or 482–625°C, 2–2.5 GPa (Zhang … The mineral assemblage of the host rock includes garnet porphyroblasts and a matrix that mainly consists of glaucophane, barroisitic hornblende, omphacite and epidote, as well as phengite and rutile as minor phases. Petrology and Occurrence of Eclogite and Glaucophane-bearing Rocks Around Khamti-Natmaw Jade Mine Area, Sagaing Region ... omphacite and pyrope garnet porphyroblasts with minor amphiboles (glaucophane), greenish micas and epidote in eclogite and glaucophane, garnet, hornblende and actinolite in amphibolite respectively. The assemblage 2. represents the common alkali amphibole bearing basic rock, or glaucophane schist. canic rocks and omphacite-bearing blueschists. The massive glaucophane-bearing metagabbros without omphacite are predominantely made up of sodic and calcic amphiboles, epidote, albite and chlorite. The variations in mineral assemblages are interpreted to depend upon local changes in the bulk chemical compo-sition. Kyanite–paragonite–garnet–glaucophane schist. In addition, various amounts of biotite, titanite, magnetite, ilmenite and traces of white mica occur. (a) Glaucophane‐bearing quartzite (quartz‐rich layers are above and below field of view) showing interaction of glaucophane with quartz veins at a high angle to compositional layering (plane light). I.—Glaucophane-schist, Eclogite, and Associated Rocks from Knockormal in the Girvan-Ballantrae Complex, South Ayrshire - Volume 64 Issue 1 Amphibole-bearing rocks with a lineated fabric belong to this group. Though the garnets are most typi-cally associated with glaucophane they occur in a few places in rocks consisting largely of actinolite or of omphacite. In the eclogite, three different metamorphic stages (stages I to III) are defined on the basis of microstructures and mineral zoning. Eclogite and garnet glaucophane schist have MORB-like bulk compositions (major and trace), but garnet glaucophane schist is free from omphacite, reflecting a higher Mg/(Mg+Fe) ratio bulk-rock composition. Two types of garnet–phengite–quartz veins cross-cut the host rock. Some schists contain no platy minerals like sheet silicates or graphite, but in this case these rocks have to display a linear fabric (elongated minerals in sub-parallel orientation). Aosta valley, Western Alps. (b) Omphacite + glaucophane + phengite + lawsonite + garnet‐bearing quartzite (plane light). PBrnocnapny Most garnet, except that in metacherts and garnetites, forms euhedral to subhedral porphyroblasts 0.5 to 2.0 mm in diameter. Smith, James Perrin (1906), The paragenesis of the minerals in the glaucophane-bearing rocks of California: American Philosophical Society Proceedings: 45: 213; Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 239. The barroisite–bearing eclogites contain two types of euhedral garnet: coarse– (1–1.5 mm) and fine– grained (<0.5 mm). Thus, the garnet + omphacite equilibrium assemblages are not relict from a pre-glaucophane schist metamorphism, but represent the peak of dry, prograde metamorphism in the metabasic rocks of Groix. Eclogite and garnet glaucophane schist have MORB-like bulk compositions (major and trace), but garnet glaucophane schist is free from omphacite, reflecting a higher Mg/(Mg+Fe) ratio bulk-rock composition. The eclogitic jadeite–garnet glaucophane schists occur as lenticular or sheet‐like bodies in the pelitic schist matrix, with the peak mineral assemblage of garnet + glaucophane + jadeite + phengite + quartz. Foliation surface of eclogitic metabasic schist with garnet, omphacite, clinozoisite and needles of dark glaucophane. Pseudomorphed lawsonite‐, garnet‐, and glaucophane‐bearing schists exposed at the highest structural levels of Tinos (Kionnia and Pyrgos Subunits) reached ~22–26 kbar and 490–520°C under water‐saturated conditions, whereas pseudomorphed lawsonite‐ and aegirine‐omphacite bearing eclogite reached ~20–23 kbar and 530–570°C. Apatite, zircon and titanite are present as accessory mineral phases. 345 Ma as the best approximation for the timing of peak metamorphic conditions. Omphacite is thought to have crystallized in water- deficient assemblages after the breakdown of lawsonite and the beginning of garnet growth. ted schist, garnet-glaucophane schist, metagabbro, meta-diabase, albitite, omphacite rock, jadeitite, stilpnomelane schist, pelitic schist, and actinolite-tremolite rocks (Saka-moto, 1997a). 21 Western Alps: Val Tournanche Eclogite facies. Ward Creek [1], Cazadero, Coast Range, Sonoma Co., California, USA : An occurrence in the NE¼ sec. Tsujimori (1995 b) reported a chromian omphacite-bearing tremolite schist of peridotite origin, suggesting that a part of the Oeyama ophiolite has experienced a high-P ÿ T metamorphism with the Sangun-Renge metamorphic rocks. In zone IIb, when basic rocks are schistose with conspicuous compositional band ing, alkali amphibole occurs not only around augite but also as individual grains in wholly recystallized layers. Occurrence of Cr-bearing beryl in stream sediment from Eskisehir, NW Turkey. The garnet glaucophane omphacite assemblage was reported in quartzfree hornblende eclogites from the Iratsu mass (Enami, Iwata & Banno, 1979), but glaucophane clearly postdated the development of garnet + omphacite. Omphacite inclusions show distinct antiphase domains structure. Glaucophane-bearing pelitic schist occurs as a string of elongated knockers adjacent to eclogite knockers exposed in a road cut along the highway between Puerto Cabello and Valencia . Blueschists present stronger anisotropies (AVP=16.1% and AVS=10.3%) than eclogites (AVP=2.9% and … Blueschist (glaucophane schist with garnet and omphacite). Metacherts have thin pink bands of fresh, euhedral garnet which is 0.01 to 0.05 mm in di-ameter and lacks inclusions. In the eclogite, three different metamorphic stages (stages I to III) are defined on the basis of microstructures and mineral zoning. Metabasic gneiss consisting of interbanded eclogite and glaucophane-bearing eclogite. The experiments demonstrated that the H 2O–CO2 fluid with dissolved major components released from the glaucophane schist can produce mineral assemblages of different chemical compositions in mantle materials: Na-bearing in websterite and K-bearing in harzburgite. New growth of secondary grossular-rich euhedral garnet and glaucophane are found within albite after jadeitite. Mg-carpholite was identified in some high-Mg chloritoid schists. In the latter case, it usually occurs in quartz-albite layers and is rare in epidote-chlorite ones. In-situ SIMS trace- element analyses in 20-30 micron steps revealed (1) sharp peaks of HREE (excepting Dy), Li and Y, and (2) "M"-shape shoulder spikes of Dy, Hf, and Er at the mantle. In the eclogite, three different metamorphic stages (stages I to III) are defined on the basis of microstructures and mineral zoning. It also contains subordinate lenses of basalt, rhyolite, chert, conglomerate and carbonate Briggs et al., 1977). Using some spectacular natural samples of garnet-bearing high-P ... with minor quartz, chlorite, phengite and titanite. The rocks have a coarse-grained, relic magmatic texture, which was modified during metamorphism. Omphacite is thought to have crystallized in water- deficient assemblages after the breakdown of lawsonite and the beginning of garnet growth. The coesite-bearing schist consists mainly of garnet, Na-Ca amphibole, quartz, white mica and albite; the coesite-bearing eclogite is mainly composed of omphacite, garnet, glaucophane and zoisite. trace), but garnet glaucophane schist is free from omphacite, reflecting a higher Mg/(Mg+Fe) ratio bulk-rock composition. Previous Sm-Nd (omphacite, garnet, glaucophane, whole rock) and 40Ar/39Ar (crossite) dating of eclogite-facies rocks has suggested an age of ca. glaucophane schist from the Cazadero area of the Fran- ciscan Formation, near Ward Creek, western California. Both rock types are hosted by calcareous pelitic schists. It consists of a range of lawsonite- to epidote–omphacite-bearing blueschists, whose dominant protoliths were Cretaceous sandstones and siltstones. 20 Western Alps: Val Tournanche. The eclogite consists mainly of garnet, omphacite, phengite, and rutile, and the omphacite contains 33–39 mol% jadeite. Eclogite occurs as lenses in garnet-bearing glaucophane schist at Gemu, south of the Lungmuco–Shuanghu suture. inclr-rde glaucophane schist, aegirine-augite bearing qrartzite, and garnet-blue-green hornblende schist (Niethammer, 1909). In particular, prograde-zoned porphyro-blastic garnet preserves the transition from blueschist to eclogite facies. Eclogite facies metasediments include garnet-omphacite- phengite-glaucophane schist and various chloritoid-bearing schists. The jadeitic clinopyroxene X Jd 0.46–0.75) is found exclusively as inclusions in porphyroblastic garnet. Related to glaucophane: Omphacite, Riebeckite, ... Beryl is accompanied by garnet, glaucophane, quartz, epidote, muscovite and chlorite in the stream sediments. The occurrence of (Type C) eclogite suggests bands or lenses … of glaucophane schist visited. C at 15 kbar) in a garnet-glaucophane schist block. The garnet is euhedral, up to 3 mm in diameter, commonly fractured, and may contain inclusions of glaucophane. Seismic properties of glaucophane-bearing blueschist and eclogite are calculated by combining measured LPO and the single-crystal elastic moduli of glaucophane with the other main mineral constituents of the rock: mostly epidote for blueschist, and omphacite and garnet for eclogite. The eclogites mainly consist of garnet, omphacite, phengite, rutile, and epidote, with or without barroisite. San Mateo Co. Redwood City It was doubt-less this fact that led several early writersr to refer some of these rocks as eclogites or glaucophane-eclogites. The coesite occurs as various mineral inclusions within porphyroblastic garnet. 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