Rhyolite flow-dome

Figure 3.2 A zone of obsidian in a rhyolite flow-dome structure. (Redrawn with permission from Hughes and Smith, 1993 Figure 2A.)...

Abstract Nash creek is the largest Zn-Pb deposit in the Tobique-Chaleurs Zone, and contains indicated and inferred resources of 7.8 Mt grading 2.72% Zn, 0.55% Pb and 18.26 g/t Ag and 1.2 Mt grading 2.66% Zn, 0.52% Pb and 18 g/t Ag, respectively. The deposit is hosted by Early Devonian bimodal volcanic and minor interlayered sedimentary rocks that were deposited in a trans-pressional rift. The host rocks sequence includes the Archibald Settlement Formation (rhyolite flows domes and related rocks), and the Sunnyside Formation (mafic lava flows and interlayered volcaniclastic and sedimentary rocks). 

Tolfa-Manziana-Cerite 3.5 - Multicentre complex made of trachydacite to rhyolite lava flows, domes and pyroclastic flows. 

Ponza, Palma-rola, Zannone, La Botte 4.2 to 1 Ma - Lava flows, domes, breccias and hydrovol-canic products formed of Pliocene calc-alkaline rhyolites and Pleistocene peralkaline rhyolites and potassic trachytes. 

Complex (20 and 15 ka), sited north of Primordial Vulcano, is the remnant of a stratovolcano with a central caldera (Fossa Caldera), mainly formed by latitic, trachytic and rhyolitic lava flows, domes, and pyroclastic rocks. Fossa Caldera products were erupted between 15 and 8 ka by pyroclastic and effusive eruptions of shoshonitic intermediate to silicic magmas. Cono della Fossa is a 391 m high active edifice that rises at the center of the Fossa Caldera it was formed in the last 6000 years by several silicic pyroclastic eruptions and a few lava effusions. Vulcanello is a shield made of mafic potassic lavas showing a KS affinity, with central trachytic pyroclastic cones. Vulcanello was formed as a new island probably about one thousand years ago (magnetostratigrafic age by Tanguy, personal communication) sand accumulation in the isthmus area finally connected Vulcanello with the main island. 

Use of micro-XRF in the characterization of hydrothermal alteration application to the subaqueous felsic dome-flow complex of the Cap d Ours segment of the Glenwood rhyolite, Rouyn-Noranda, Quebec... 

In the JRS the Dalhousie Group is divided into five formations (Walker and McCutcheon 1995). Only the upper three Archibald Settlement, Sunnyside and Big Hole Brook formations (described below), are exposed in the vicinity of Nash Creek. The Archibald Settlement Formation is the lowermost of these and consists of massive flows and domes of orange to red, aphyric, commonly flow-layered rhyolite. Up section massive flows are interlayered with fine- to coarse-grained volcaniclastic rocks including heterolithic lapilli-tuff and agglomerate, as-well-as volumetrically minor feldspar-phyric rhyodacite. A U/Pb zircon age of 415.6 +/-0.4 Ma has been returned from rhyolite of... 

Panarea 150 kato 45 ka - Mostly submerged stratovolcano with a flat top at about 100-150 m below sea level, formed by domes and minor lava flows and pyroclastics with a dominant calc-alkaline dacite to rhyolite composition. Minor shoshonites. 

Pantelleria 320 to less than 10 ka - Stratovolcano with central nested calderas formed of peralkaline rhyolitic (pantellerites) and trachytic ignimbrites and lava domes, with minor weakly Na-alkaline basaltic lava flows and cinder cones. 

---