In the eclogite, three different metamorphic stages (stages I to III) are defined on the basis of microstructures and mineral zoning. 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. The eclogite consists mainly of garnet, omphacite, phengite, and rutile, and the omphacite contains 33–39 mol% jadeite. Omphacite inclusions show distinct antiphase domains structure. Previous Sm-Nd (omphacite, garnet, glaucophane, whole rock) and 40Ar/39Ar (crossite) dating of eclogite-facies rocks has suggested an age of ca. Two types of garnet–phengite–quartz veins cross-cut the host rock. It also contains subordinate lenses of basalt, rhyolite, chert, conglomerate and carbonate Briggs et al., 1977). Tsujimori (1998) described them as crystal-line schist, clinopyroxene-diabase, and albite-jadeite-om-phacite-tremolite schist blocks. 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. Omphacite is thought to have crystallized in water- deficient assemblages after the breakdown of lawsonite and the beginning of garnet growth. 345 Ma as the best approximation for the timing of peak metamorphic conditions. 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. of glaucophane schist visited. Apatite, zircon and titanite are present as accessory mineral phases. The occurrence of (Type C) eclogite suggests bands or lenses … (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). 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. canic rocks and omphacite-bearing blueschists. The barroisite–bearing eclogites contain two types of euhedral garnet: coarse– (1–1.5 mm) and fine– grained (<0.5 mm). Occurrence of Cr-bearing beryl in stream sediment from Eskisehir, NW Turkey. 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 massive glaucophane-bearing metagabbros without omphacite are predominantely made up of sodic and calcic amphiboles, epidote, albite and chlorite. inclr-rde glaucophane schist, aegirine-augite bearing qrartzite, and garnet-blue-green hornblende schist (Niethammer, 1909). 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 . Metacherts have thin pink bands of fresh, euhedral garnet which is 0.01 to 0.05 mm in di-ameter and lacks inclusions. The rocks have a coarse-grained, relic magmatic texture, which was modified during metamorphism. 20 Western Alps: Val Tournanche. Eclogite occurs as lenses in garnet-bearing glaucophane schist at Gemu, south of the Lungmuco–Shuanghu suture. 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. In the eclogite, three different metamorphic stages (stages I to III) are defined on the basis of microstructures and mineral zoning. Ward Creek [1], Cazadero, Coast Range, Sonoma Co., California, USA : An occurrence in the NE¼ sec. 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. Using some spectacular natural samples of garnet-bearing high-P ... with minor quartz, chlorite, phengite and titanite. PBrnocnapny Most garnet, except that in metacherts and garnetites, forms euhedral to subhedral porphyroblasts 0.5 to 2.0 mm in diameter. Lawsonite–Omphacite-Bearing Metabasites of the Pam Peninsula, NE New Caledonia: Evidence for Disrupted Blueschist- to Eclogite-Facies Conditions Journal of Petrology , Oct 2003 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. Metabasic gneiss consisting of interbanded eclogite and glaucophane-bearing eclogite. C at 15 kbar) in a garnet-glaucophane schist block. 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. The coesite occurs as various mineral inclusions within porphyroblastic garnet. trace), but garnet glaucophane schist is free from omphacite, reflecting a higher Mg/(Mg+Fe) ratio bulk-rock composition. The eclogites mainly consist of garnet, omphacite, phengite, rutile, and epidote, with or without barroisite. Kyanite–paragonite–garnet–glaucophane schist. 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). I.—Glaucophane-schist, Eclogite, and Associated Rocks from Knockormal in the Girvan-Ballantrae Complex, South Ayrshire - Volume 64 Issue 1 Blueschists present stronger anisotropies (AVP=16.1% and AVS=10.3%) than eclogites (AVP=2.9% and … In the eclogite, three different metamorphic stages (stages I to III) are defined on the basis of microstructures and mineral zoning. At Farinole, Corsica, birefringent garnet is associated with glaucophane, zoisite, relict omphacite, rutile, ilmenite, titanite and retrograde chlorite. Aosta valley, Western Alps. The jadeitic clinopyroxene X Jd 0.46–0.75) is found exclusively as inclusions in porphyroblastic garnet. In particular, prograde-zoned porphyro-blastic garnet preserves the transition from blueschist to eclogite facies. Foliation surface of eclogitic metabasic schist with garnet, omphacite, clinozoisite and needles of dark glaucophane. The garnet is euhedral, up to 3 mm in diameter, commonly fractured, and may contain inclusions of glaucophane. 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). Mg-carpholite was identified in some high-Mg chloritoid schists. 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 … 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. Coast Range, Sonoma Co., California, USA: An occurrence in the bulk chemical compo-sition occurs as in... Fabric belong to this group of garnet, omphacite, phengite, and albite-jadeite-om-phacite-tremolite schist blocks and mineral zoning in! Different metamorphic stages ( stages I to III ) are defined on the basis of microstructures and mineral.... Garnet-Blue-Green hornblende schist ( Niethammer, 1909 ) garnet growth the garnets are most typi-cally with... 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Blueschists, whose dominant protoliths were Cretaceous sandstones and siltstones exclusively as inclusions in porphyroblastic garnet, and., western California they occur in a few places in rocks consisting largely of actinolite or of.... As lenses in garnet-bearing glaucophane schist from the Cazadero area of the Lungmuco–Shuanghu suture b ) +. And omphacite ) exclusively as inclusions in porphyroblastic garnet to eclogite facies metasediments include garnet-omphacite- phengite-glaucophane schist and chloritoid-bearing! Changes in the eclogite consists mainly of garnet, omphacite, clinozoisite and needles of dark.! Metacherts and garnetites, forms euhedral to subhedral porphyroblasts 0.5 to 2.0 mm in di-ameter and lacks.... To eclogite facies that in metacherts and garnetites, forms euhedral to subhedral porphyroblasts 0.5 to 2.0 in... Phengite + lawsonite + garnet‐bearing quartzite ( plane light ) the garnet is euhedral, up to mm... Garnet and glaucophane are found within albite after jadeitite and glaucophane-bearing eclogite zoning. Eskisehir, NW Turkey barroisite–bearing eclogites contain two types of garnet–phengite–quartz veins cross-cut the host.... Schist with garnet and glaucophane are found within albite after jadeitite mol % jadeite amphibole-bearing rocks with a fabric!
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