| | Journal (article/letter/editorial) | Geology and Mineralogy, University of Queensland, St. Lucia, Queensland, 4o67 SUMMARY. Spherulitic devitrification...consist of cryptocrystalline intergrowths of c~-cristobalite and alkali feldspar (calcicanorthoclase), with...studied from a suite of samples from the Aratiatia rhyolite. The most significant effect is the progressive...glasses. A systematic study of one rhyolite extrusion, the Aratiatia rhyolite, was undertaken to study in detail...show the spherulites to be composed mainly of ~-cristobalite and alkali feldspar (in cryptocrystalline intergrowths) | | | Report (volume) | visible. These hills consist of Sarmatian rhyolite domes and rhyolite tuff on their lower elevations. 35.5...small Diszndok6 Hill is built up from Sarmatian rhyolite. From here follow the road back to Mad. 48.5...this rhyolitic tuff and the higher elevations by rhyolite. To the left (north) the hills are built up by...cone is Sator Hill which consists of Sarmatian rhyolite. From here the road turns north and follows the...from the road. The castle was erected on a welded rhyolite tuff unit of Sarmatian age. siliceous Propylitic | | | Book | GRANITE 3 In partly crystalline varieties of rhyolite, spheroidal forms may originate which are generally...(1953) write: . There are ·all gradations between rhyolite, a rock of magmatic origin, and granite, and one...border zones of granites. Aureoles and Satellitic Dykes of Batlzoliths In the vicinity of granite massifs...long after the batholith crystallized. Moreover, dykes of lamprophyres occur, which are another facies...differentiation; dark rocks rich in mica flakes and amphibole. Dykes of granite porphyry (microgranites, microdiorites) | | | Book | resultant excess silica crystallizes out as cristobalite. Tsuzuki and Nagasawa (1969) carried out detailed...various volcanic rocks such as basalt, andesite, rhyolite and related pyroclastic rocks such as tuffs and...breccias, were formed. These volcanic rocks occur as dykes, sheets and flows. Virtually all of the rocks have...distributed in an irregular and funnel-shaped form in rhyolite and its pyroclastics. Those metallic ore deposits...comprise hydrothermally altered rocks derived from rhyolite, lithoidite, perlite or other parent rocks. Recently | | | Report (volume) | flows while granites occurring as plutons, ring dykes, bosses and plugs form the second phase. The third...represented by mafic and felsic dykes. The terrestrial basalt-rhyolite/trachyte volcanism of Malani is.................... . Granitoids and gneisses .Dykes . .............................................................................. Peralkaline rhyolite . . ........................................................................ Peraluminous rhyolite . ............. ........ . ............. | | | Report (volume) | features of the province is the presence of giant dykes, up to 800 metres wide. These are dominantly basic...magma generated in the wider portions of these dykes migrated upwards and may ultimately have accumulated...Ilimaussaq intrusion, Larsen & Serensen). The giant dykes, therefore, play a crucial role in understanding...trachyte and, with extreme fractionation, alkali rhyolite. The production of peralkaline acid rocks by crystal...features of the province is the presence of giant dykes, up to 800 metres wide. These are dominantly basic | | | Book | Alaskan zoned intrusions Mafic lavas Sill complexes Dykes Pegmatites MAGMATIC-HYDROTHERMAL – – – – – –...amorphous silica as opal-A, which later changes to cristobalite and finally quartz. Siliceous sinters may take...silica, cristobalite, hematite and various Na-K-V-Zn-Cu-S phases; (2) 450–5508C Au, cristobalite, hematite...chalcopyrite; (3) 6008C Au, amorphous silica, cristobalite, hematite, tenorite, WO3, barite, anglesite...and various K-Cu-Pb-V-Cl-S phases; (4) 6808C cristobalite, tridymite, hematite, rutile, plattnerite (PbO2) | | | Book | occurrences, usually volcanic fields or swarms of dykes or diatremes. Some of these are indicated on the...complex and Lake Tortue 103 Northwestern Quebec dykes 1 04 Cabonga Reservoir 1 05 Ba katong Reser-voi...syenitic, but in some places dioritic. It is cut by dykes up to 1.5 m thick including peralkaline types. Most...biotite, sphene and opaq ues. The greater number of dykes are perthite phyric syenites usually with some...suite consists of five agglomerate vents, about 75 dykes and sm all plugs, as well as several sills, within | | | Report (Issue volume) | Magnet ARGS WilSOn Ee Rk, Sein A es ed See ee eee Saint George gold deposit, Mount Magnet REBORN GPLATAVOOL...the lower crust to generate the large volumes of rhyolite and dacite ash and lava flows preserved in the...setting of South Australia. Extensive swarms of mafic dykes and gabbroic complexes were emplaced in the Gawler...to 1050 Myr. However, in addition to the mafic dykes and gabbroic complexes, there was a major phase...manifest again at about 1100 Myr by NW trending mafic dykes, and during the early Adelaidean by formation of | | | Book (volume) | extensive extrusions of trachyte, andesite and rhyolite appear in some areas to be connected with small...(1968), produced a widespread swarm of porphyrite dykes which were responsible for a widely disseminated...eastern flank of the granite which is cut by andesite dykes, considerable concentrations of molybdenite were...Nagyborzsony is confined to propylitized NNE trending dykes of pyroxene andesite and biotite—hornblende dacite...volcanic complex consists of andesite, dacite and rhyolite. It does not exceed 1km in thickness along the | | | Journal (volume) | decomposition products: hercynite, fayalite, cristobalite, Fecordierite and metallic α-iron. Metallic...volcanic rock with intermediate composition between rhyolite and dacite) and clays, effective in the retention...(low broad diffuse halo with a peak at 4.10 Å), cristobalite (clearly defined peak with a value of interplanar...mineral formation, solid-phase reaction of β-cristobalite formation begin after 1000 ºC. 2) Diagnostic...should be considered as alternating layers of α - cristobalite and tridymite with a deterministic quantitative | | | Report (issue) | a constituent of partly - spherulitic rh yolite dykes that are associated with the Glundebery balholith...quartz form the core zones of the Moose pegma tite dykes located immediate l y north of Hearne Ch anne l...H/11 Analcime and natrolite have been found in dykes cutting Trenton limestone near Montreal, Hochelaga...21 G/l Azurite is found on Frenchman Creek in Saint John County (W. L. Goodwin, 1 938 : Geology and...). -63- AZU 21 H/4 At Beveridge County in Saint John County, in a shear zone {F.J . Alcock , 1938: | | | Book | FLOOR-DISSEMINATED TYPE \ QUARTZ-SERICITE VEINS \ 1 ASSOCIATED DYKES Fig. 2 . 3 . DISSEMINATED IN LATE DIFFERENTIATES...essentially sheet-like intrusions with feeder dykes. The style of mineralisation is distinctive and... Disseminated cassiterite in small late stage "dykes" of fine grained granite/aplite. Wolframite is occasionally...consists essentially of a volcanic suite (andesite, rhyolite, dacite, basalt) with an associated forechain...Many centres are associated with small intrusives dykes of fine grained granite/aplite. (Fig. 2.4). A second | | | Book | footwall of gently dipping feldspar porphyry dykes and the dykes were therefore regarded as having an important...400 m. It is now apparent that the ore bodies and dykes have a more casual relationship and were probably...dominated successively by pillow lavas, sheeted dykes and gabbros. The base of the oceanic crust is defined...foliation of the harzburgite represent the sites of dykes which have acted as channelways to the overlying...and convective circulation within bulges in the dykes which encourage the mixing of chromite grains and | | | Journal (issue) | Volborthite, Annabergite, Hummerite-like*, Alpha-cristobalite, Sulvanite(?), Nontronite, Montroseite(?), Covelline...fine exposure of Precambrian Schist cut by rhyolite dykes could be seen, where the present working mine... and Harvey, C.O. 1950. The riebeckite-bearing dykes of Shetland. Mineralog.Mag., 29, 359-373. 51. Phillips | | | Book | overall have a north-east-south-west strike, rhyolite domes, while the central block of felsic to mafic...(James Cove) at 60673:3 Ma, while an intrusive rhyolite dyke cutting these volcanics gave a date of 585... 705), but U-Th—Pb analyses of zircons from a rhyolite provided a date of 602 +3 Ma. If the dates of...Can., 216, 1-65. Alcock, F. J. (1938). Geology of Saint John region, New Brunswick. Mem. geol. peninsula...reconsideration of some geological relations near Saint John, New Brunswick. Geol. Surv. Pap. Can., 84-1A | | | Book | lavas and subaqueous pyroclastics, intruded by rhyolite domes, while the central block of felsic to mafic...(James Cove) at 606*3-3 Ma, while an intrusive rhyolite dyke cutting these volcanics gave a date of 585...705), but U-Th-Pb analyses of zircons from a rhyolite provided a date of 602 +3 Ma. If the dates of...Can., 216, 1-65. Alcock, F. J. (1938). Geology of Saint John region, New Brunswick. Mem. geol. Surv. Avalon...reconsideration of some geological relations near Saint John, New Brunswick. Geol. Surv. Pap. Can., 84-1A | | | Book (edition) | (1949) Pleistocene glacial cycles interpretation) Saint-Marc, P., F. Paltrinieri & B. Situmorang (1977)-...Rb/Sr ratios in volcanic rocks and cordierite in rhyolite at Tanjong Illipoi (Wetar) indicate of strong...islands of Banda Arc because of abundant light grey rhyolite and dacite. This extinct, eroded and uplifted...leucite basanite and leucite tephrite eruptives and dykes from Batu Tara volcano (50 km N of Lembata (Lomblen)...suggest mantle origin. High ratio in Lake Toba rhyolite implies crustal origin) Whitford, D.J., W. Compston |
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