Results 141 to 150 of about 343 (178)

Geochemistry of the Archaean Metavolcanic Rocks of Kolar and Hutti Gold Fields, Karnataka, India

Journal Geological Society of India, 1979
Abstract Geochemical data on Archaean goldfields metavolcanics (2.7 b. yrs) have been plotted on major and minor element discriminant diagrams to define the magma type and to formulate the tectonic environment model for the origin of these ancient volcanic rocks.
Iyer, GVA, Vasudev, VN
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Petrology of Metavolcanic Rocks in the Bishop Corners – Donaldson Area, Grenville Province, Ontario

Canadian Journal of Earth Sciences, 1973
A calc-alkalic suite, with an apparent thickness of 7 km, varies from alkali basalt and tholeiite composition in the lowest part exposed, through andesite flows and pyroclastic rocks, to rhyodacite pyroclastics at the top. Sixty-two chemical analyses demonstrate a single volcanic cycle.
K. Sethuraman, John M. Moore Jr.
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Metavolcanic rocks and their origin, Southern Adirondack mountains, New York

Bulletin Volcanologique, 1970
One of the problems associated with massif-type anorthosite in high grade metamorphic terranes is the absence of anorthositic extrusives. However, if anorthosite formed by crystal segregation, volcanic equivalents of the final fluid differentiate might occur.
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Geochemical variations within metavolcanic rocks of the Dalradian Farragon Beds and adjacent formations

Scottish Journal of Geology, 1993
Synopsis A detailed petrological and geochemical study of metavolcanic schists of the Dalradian Argyll Group of the southern Highlands of Scotland reveals the activity of five main centres of volcanicity. Volcanic activity started with the localized eruption of low HFSE tholeiites comprising the Laoigh Metabasites during the deposition of the
S. Goodman, J. A. Winchester
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The geochemistry of possible metavolcanic rocks and their relationship to mineralization at Montauban-Les-Mines, Quebec

Canadian Journal of Earth Sciences, 1977
Base metal and gold ores in thin calc-silicate and cordierite gneiss units at Montauban-Les-Mines have historically been described as pyrometasomatic deposits related to granitic intrusions. They are stratigraphically overlain by quartzo–feldspathic gneiss and amphibolite, the uppermost amphibolite unit being a pillowed metabasalt.Chemical analysis ...
Karen Stamatelopoulou-Seymour, Wallace H. MacLean   +1 more
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Steep tilting of metavolcanic rocks by multiple mechanisms, central Sierra Nevada, California

Geological Society of America Bulletin, 2000
For ∼200 km along the eastern Sierra Nevada continental magmatic arc, Mesozoic metavolcanogenic rocks dip steeply to the southwest (∼80°), a feature that must reflect fundamental processes in magmatic-arc construction. Although tight folds can account for such steep bedding tilts, folds in the metavolcanogenic sections are sparse and small scale.
Tobisch, Othmar T., Fiske, Richard S., Saleeby, Jason B., Holt, Elizabeth, Sorensen, Sorena S.   +4 more
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Petrography and Geochemistry of the North of Ilgin (Konya) Metavolcanic Rocks

In this study, investigated the geology, mineralogy, petrography and geochemistry of metavolcanic rocks in northern Ilgın (Konya). There are two Paleozoic and Mesozoic metamorphic rock groups in the study area. Alluvium and Neogene sediments are unconformably layered over these rocks.
Oral Sarıkaya, Şenel Özdamar
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U-Pb and Th-Pb whole-rock isochrons from metavolcanic rocks of the Carolina slate belt

Geological Society of America Bulletin, 1987
Felsic volcaniclastic rocks and massive pyrite of a part of the Carolina slate belt in South Carolina referred to as the “Haile-Brewer block” seem to have remained closed systems with respect to U, Th, and Pb since ∼465 Ma. U-Pb and Th-Pb whole-rock isochrons indicate ages of 466 ± 40 (2σ) and 462 + 53 Ma, respectively. The Pb-Pb secondary isochron age
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Nature of the Angular Unconformity between the Paleozoic Metasedimentary Rocks and the Mesozoic Metavolcanic Rocks in the Eastern Sierra Nevada, California

Geological Society of America Bulletin, 1974
Two major wall-rock sequences, the Paleozoic metasedimentary rocks and the Mesozoic metavolcanic rocks, in the eastern Sierra Nevada, California, are separated by an angular unconformity rather than by a fault as has been proposed by other investigators.
CHARLES A. BROOK, WARREN J. NOKLEBERG, RONALD W. KISTLER   +2 more
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Geochemistry and Petrology of Metavolcanic Rocks of the Early Proterozoic Mazaruni Greenstone Belt, Northern Guyana

Geological Society, London, Special Publications, 1987
Summary The dominantly metavolcanic Issineru Formation (IF) forms the lower 5–7 km of the stratotype for the early Proterozoic Mazaruni greenstone belt, N Guyana. Basalts and gabbros comprise the lower part of the section. The upper half includes some basalts, but is predominantly intermediate and felsic rocks.
R. Renner, A. K. Gibbs
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