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Showing 1 to 20 of 23 for “"syenite"”.
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Petrology and geochemistry of syenite intrusions in the Eastern Province of Zambia
… nepholine-sodalite varieties.The ,Sinda syenite intrusions are oversaturated potassics which form a petrogenetically related N-S trending string of intrusions at the eastern margin of the Sinda batholith.The northernmost Lusandwa intrusion is a composite diapir covering some 70sq Km …
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Petrogenesis of the peralkaline granite (and associated syenite) dykes of the Straumsvola Complex, Western Dronning Maud Land, Antarctica
The Straumsvola nepheline syenite complex in Western Dronning Maud Land, Antarctica consists of an outer massive and inner layered nepheline syenite that is itself intruded by ijolite. The complex and its immediate country rock was intruded by numerous dykes. A small proportion of these dykes are …
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Petrogenesis of the Mesoproterozoic anorthosite, syenite and carbonatite suites of NW Namibia and their contribution to the metasomatic formation of the Swartbooisdrif sodalite deposits
… its south-eastern margin the KIC was invaded by syenite dykes (1,380-1,340 Ma) and younger carbonatites (1,140-1,120 Ma) along ENE and SE trending faults. Older ferrocarbonatite intrusions, the ‘carbonatitic breccia’, frequently contain wallrock fragments, whereas subordinate ferrocarbonatite …
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Petrology of the Gracefield pluton.
The Gracefield pluton is composed of two distinct syenite intrusions; both of which appear to have been intruded late in the Grenville tectonic and metamorphic history. They both exhibit a well developed concentric mineralogical zoning. They have shonkinitic cores which grade laterally into alkali …
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The geochemistry and geochronology of the barby formation in the sinclair area, Southern Namibia
… are described and dated. The coeval Spes Bona Syenite and the Tiras Granite are also described and dated. The rock types in the Barby Formation are rhyolites, basaltic trachyandesites, trachybasalts and trachydacites as well as volcanoclastic rocks. The rocks are largely undeformed and partly …
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The oxygen, carbon & hydrogen isotope geochemistry of the Phalaborwa Complex, South Africa
… and many smaller syenite plugs around the pipe. The complex is the oldest known carbonatite in southern Africa and the only one known to host economic copper deposits. There are no known detailed studies on multi-mineral oxygen and hydrogen isotopes or multi-rock …
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The Middle Fork Plutonic Complex: a plutonic association of coeval peralkaline and metaluminous magmas in the north-central Alaska Range
… the 125 km² complex is hedenbergite - fayalite syenite, ≃20% is peralkaline arfvedsonite - biotite alkali-feldspar granite (AF granite), and ≤20% is pyroxene - olivine - biotite gabbro. The rest is a mixed unit including clinopyroxene - biotite - amphibole diorite, and hornblende - biotite …
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Mineralogy and Geochemistry of Anorogenic Granitic Miarolitic Pegmatites Associated with the White Mountain Intrusive Suite, New Hampshire
… Platte (Simmons et al. 1987) and the Wausau Syenite Complex (Meyers et al. 1984).</p>
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Stratigraphy, igneous petrology and evolution of the Sinclair Group in southern South West Africa
… of the northwesterly elongated body of Spes Bona syenite was accompanied by intrusion of monzonitic and dioritic magma along fracture zones marginal to the syenite. The emplacement into high crustal levels of large volumes of the porphyritic/granophyric Nubib granite (1360±50 Ma) took place within …
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Characterization of Residual Mineral Content of Bauxite Stockpiles in Saline County, Arkansas: An XRD Analysis Approach
… and hosts extensive bauxite and nepheline syenite deposits. With the depletion of highgrade ore, renewed interest in bauxite stockpiles has focused on critical mineral potential. Previous X-ray Fluorescence studies have identified critical elements in significant concentrations, including …
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Petrogenesis of a migmatite, Penobscot County, Maine: ultrametamorphism or intrusion?
… the Parks Pond Pluton (mafic granite to quartz syenite) on the northeast. The Parks Pond crystallized at >1000°C. The leucosomes are I-type (metaluminous, hornblendebearing inclusions, primary titanite, allanite, hornblende, and apatite included in biotite or hornblende), or S-type (tourmaline …
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Temperature-dependent thermal transport properties of major Archean rock types and implications for the thermal evolution of Archean terranes
… banded iron formation to [about]0.8 mm2/s for syenite. D for all samples decreases with increasing T, and the range of D for the suite narrows to [about]0.45 and 0.70 mm2/s for granodiorite and tholeiite basalt respectively by ~1000K. We applied these results to endmember numerical models of …
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Sub-surface geology, petrochemistry and hydrothermal alteration of Wells MW-03, MW-09 and MW-20 from Menengai geothermal field, Kenya
… pyroclastics, tuffs, basalts and intrusives (syenite) were observed. Based on Al2O3 concentration and total K2O + Na2O, the analysed rocks are metaluminous compared to the neighbouring wells MW-04, MW-06 and MW-07. The geochemical evolution of Menengai rocks seems to be mainly controlled by …
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Structural setting and petrogenesis of Silurian granites in the Caledonides of northern Scotland
… complementary higher ENd(i) and lower 8180. Syenite-dominated complexes evolved by assimilation fractional crystallization (AFC) involving depleted granulite-facies basement whereas the granites assimilated Moine metasediment. Combining available age data with the observed isotope systematics …
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Tectono-hydrothermal evolution of the Neoarchean Abitibi greenstone belt, Canada
… pyroclastic surge and fallout deposits, and syenite intrusions within the Timiskaming assemblage. The clastic facies contain evidence for high rates of deposition and paleoseismic activity. The detrital material appears to be of varied provenance and may not only be derived from local …
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Petrography and Field Mapping of Eocene Intrusions and Adjacent Breccia Zones at the Scraper Springs Prospect, Elko County, Nevada
… alteration. A separately-mapped unit of quartz syenite is also documented, revealing potassic alteration haloes around its margins. Petrography indicates this type of potassic alteration is overprinted by propylitic and ultimately sericitic events. Advanced argillic alteration in the breccia …
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Geology of the western portion of the Dogtooth pluton, Lake of the Woods region, southwestern Ontario
… being quartz monzonite, granite, monzonite, and syenite. The average composition of the rocks sampled is 28.4 volume percent quartz, 46.9 percent plagioclase, and 19.7 percent alkali feldspar, which falls very close to the ternary eutectic for the KA1Si 308 –Na ALSi 308 –SI02 system. The rocks …
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Geological and geochemical aspects of the Loch Loyal Alkaline Complex, Sutherland
… parameters applicable to the Loch Loyal syenites and to relate these both to processes operating there and to the broader problems of alkaline rock genesis. Whole rock and trace element contents have been determined for the Loyal syenites and compared with other alkaline intrusions in …
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Geochemical and isotopic constraints on the source regions of phanerozoic carbonatites and associated alkaline rocks from the Zandkopsdrift complex of Namaqualand, South Africa, and the Marinkas Quellen, and Dicker Willem complexes in Namibia
… alkaline lamrophyre at Zandkopsdrift, nepheline syenite and trachyte at Marinkas Quellen, and ijolite and trachyte at Dicker Willem. At both Marinkas Quellen and Dicker Willem, the trachytes appear to be derived primarily from fenitised country rock. The major and trace element characteristics, …
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Petrogenesis of Mesoarchean high-K rocks in the Kaapvaal Craton: Investigating the Boesmanskop Alkaline Complex and Salisbury Kop batholith
… the BAC rocks. The BAC includes coarse-grained syenite, quartz monzonite and leucogranite. Some syenites display porphyritic textures that indicate K-feldspar phenocryst accumulation, with clinopyroxene and Ca-amphibole as intercumulus phases. Field observations indicate that the BAC magmas were …
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