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Showing 1 to 20 of 29 for “"dacite"”.
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Thermal Modeling of Cooling Time of Submarine Dacite Lapilli Tuff: Brothers Volcano, Kermadec Arc
… to create a cooling curve model of a lapilli dacite clast from its initial eruption temperature to the Curie temperature of magnetite to compare to the acquisition of the paleomagnetic remanent vector to test modes of eruption style.</p> <p>The model was created using three initial …
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Petrology and geochemistry of the recent eruption history at Rabaul Caldera, Papua New Guinea : implications for magmatic processes and recurring volcanic activity
… side of Rabaul Caldera...Comparison with dacite magma compositions erupted in 1937-1943, 1878, and during the recent prehistoric era and the presence of plagioclase phenocrysts reflecting older basalt-dacite magma interaction events (i.e., anorthite cores overgrown with thick andesine …
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Petrology and geochemistry of the recent eruption history at Rabaul Caldera, Papua New Guinea : implications for magmatic processes and recurring volcanic activity
… side of Rabaul Caldera...Comparison with dacite magma compositions erupted in 1937-1943, 1878, and during the recent prehistoric era and the presence of plagioclase phenocrysts reflecting older basalt-dacite magma interaction events (i.e., anorthite cores overgrown with thick andesine …
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Evaluation of Failure Mechanics of the Malpais Landslide, Eureka County, Nevada
… Paleozoic basement rocks and underlie Miocene dacite flow units. The landslide, which originated at a local high point along the fault-controlled Malpais Rim, flowed north into Whirlwind Valley. It has a surface area of approximately 2.2 km2 and volume of approximately 0.032 km3. The landslide …
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The geology and geochemistry of a Robinson Creek gold ocurrence, north of Amisk Lake, Saskatchewan
… intermediate to felsic volcanic rocks (dacite to rhyolite), also belonging to the Amisk Group, are found stratigraphically above the mafic volcanics, and may represent former volcanic flows and related pyroclastic rocks. These rocks are intruded by two varieties of porphyritic dacite to …
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Stratigraphic and Geochemical Insights into Explosive Volcanism in Northwestern Nicaragua: Case Studies from the Momotombo-Monte Galán Volcanic System and Cosigüina Volcano
… caldera of Cosigüina volcano. Early erupted dacite pumice and later erupted andesite scoria was sampled at fine scale and a combination of multiple geochemical approaches were applied to characterize matrix glass, plagioclase phenocrysts, and melt inclusions. The textures of the sampled …
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Deciphering the Signature of Magma Mixing: Examples from the Castle Creek Eruptive Period, Mount St. Helens, Washington
… 1700 years B.P. The Castle Creek period erupted dacite, andesite and basalt within this short span of time. Andesite and dacite eruptions dominate the first approximately 700 years of the period, and all basaltic units were erupted in approximately the last 100 years of the period. This is the …
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Volcanic stratigraphy and lithochemistry of the lower Jurassic Hazelton group, host to the Eskay Creek precious and base metal volcanogenic deposit
… elastic sedimentary rocks; andesite - hiatus 1 - dacite - rhyolite - dacite - hiatus 2 (peak alteration and 21 Zone mineralization) -basalt. Volcanism occurred in an extensional basinal environment. Consistent mineralogy, calc-alkaline affinities and fractionation trends, suggest the intermediate …
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Documenting Magma Evolution of the Fossa delle Felci (Salina Island, South Tyrrhenian Sea) by Integrating In Situ Plagioclase Data with Quantitative Modeling
… Island, Italy) magmas, which span the basalt to dacite range (52-65 wt% SiO2). Integration of petrographic, whole rock, and in situ plagioclase data with quantitative magma chamber models suggests differentiation dominated by fractional crystallization and magma recharge/mixing in reservoirs …
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The Muddy Creek Formation: Depositional environment, provenance, and tectonic significance in the western Lake Mead area, Nevada and Arizona
… Muddy Creek Formation are composed of andesite, dacite, basalt, rhyolite, quartz monzonite, and granite. Paleocurrent data for the basal River Mountain conglomerate suggest that the transport direction was to the southeast, parallel to the regional strike of high-angle normal faults. The River …
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Controls of Melt Genesis and Evolution at Buldir Volcano in the Western Aleutian Island Arc
… or subducted basaltic source. Andesites and dacites from emergent volcanoes throughout the Aleutians often also have low abundances of middle and heavy rare-earth elements (REE's), but these characteristics are widely attributed to fractional crystallization and the removal of amphibole from …
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Experimental studies on the adsorption of SO2 on volcanic ashes
… Andesite: A=1644.28; B=0.29; C=-7.43; Dacite: A=2139.52; B=0.29; C=-9.32; Rhyolite: A=909.75; B=0.21; C=-4.48. The heats of adsorption Delta(Ha) for the synthetic glasses were inferred from the regression model: For rhyolite Delta (Ha) was approx. 7.6 kJ/mol, for dacite Delta (Ha) was …
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The geology and geochemistry of volcanic rocks in the Lava Mountains, California: Implications for Miocene development of the Garlock Fault
… 9-km diameter Western Lava Mountains volcano. Dacites with limited chemical variability reflect interaction of mantle derived basalt with both metabasalt and graywacke of the Mesozoic Rand Schist and Cretaceous "Atolia-type" granitoids. Geophysical data suggests a low angle contact between …
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Die Fragmentierung hochviskoser Magmen
… interest. The experiments were performed on Dacite samples form Mt. St. Helens (Washington, USA), Fugendake (Unzen volcano complex, Japan) and basaltic Andesites of the 1994 eruption of Merapi (Java, Indonesia). The experimental investigation, the methodological and technical development are …
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Major element and isotopic studies on the James Run/Port Deposit association, Maryland: tectonic analogues and Taconic deformation
… the meta-igneous rocks as a bimodal tholeiite-dacite/tonalite suite with trondhjemitic affinities and indicate that subsolidus alteration during dynamic metamorphism was minor. Comparison of these data with other tectonic environments suggests their generation by partial fusion of amphibolitic …
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WHY THE XWISTEN CROSSED THE RIVER: LITHIC TRANSPORT STRATEGIES ON THE CANADIAN PLATEAU
… as arrowstone, basalt, vitreous trachydacite, and/or dacite, provided the majority (often more than 75%) of many lithic assemblages in the Mid- Fraser region of south-western British Columbia. Most explanations for this have largely been insufficient for explaining the differential …
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WHY THE XWISTEN CROSSED THE RIVER: LITHIC TRANSPORT STRATEGIES ON THE CANADIAN PLATEAU
… as arrowstone, basalt, vitreous trachydacite, and/or dacite, provided the majority (often more than 75%) of many lithic assemblages in the Mid- Fraser region of south-western British Columbia. Most explanations for this have largely been insufficient for explaining the differential …
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Deciphering the Tectonics of the Caucasus from Post-Collisional Volcanism
… Caucasus, dominated by calc-alkaline basalt-dacite (48-72 wt% SiO<sub>2</sub>) compositions. High Mg# cores (>85) of olivines suggest significant fractionation has occurred. Trace element patterns show a distinctive supra-subduction setting, suggesting the fluid-enriched source remained in …
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Petrogenesis of Eocene-Oligocene magmatism of the Sulphur Springs Range, central Nevada: The role of magma mixing
… suite ranges compositionally through rhyolite, dacite, andesite and basaltic andesite but is less alkaline than the Bingham volcanic suite. However, the alkali content of the Sulphur Springs suite is similar to other Eocene igneous rocks along the Carlin Trend. The unusual geochemical signature …
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The Marcona - Mina Justa District, South-Central Perú: Implications for the Genesis and Definition of the Iron Oxide-Copper (-Gold) Ore Deposit Clan
… and intricate, amoeboid interfingering with dacite porphyry intrusions, interpreted as evidence for the commingling of hydrous Fe oxidic and silicic melts. An evolution from magnetite - biotite - calcic amphibole ± phlogopite assemblages, which are inferred to have crystallized from an …
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