Now showing items 11-20 of 192
Si-Al ordering in nephelines
(Springer-Verlag, 1971-06)
Different degrees of Si-Al ordering are demonstrated to exist in nepheline on the basis of five crystal structure refinements on specimens with different geologic origins and laboratory treatments. Disorder increases in ...
The hydrothermal component in ferromanganese nodules from the southeast Pacific Ocean
(Elsevier, 1989-06)
Statistical analyses of geochemical data from ferromanganese nodule samples representing a broad area of the southeast Pacific Ocean indicate nodule compositions are controlled by four factors: (1) suboxic diagenesis; (2) ...
Sr/Mg ratios of modern marine calcite: Empirical indicators of ocean chemistry and precipitation rate
(Elsevier, 1992-05)
Holocene biotic and abiotic marine calcite have a similar range of Mg contents (0 to 22 and 4 to 21 mol% MgCO3, respectively), yet biotic calcite has Sr2+ concentrations that are consistently 1250 ppm higher than those of ...
Igneous pyroxenes from metamorphosed anorthosite massifs
(Springer-Verlag, 1978-02)
Anorthosites, mangerites and charnockites from metamorphosed anorthosite massifs (the Adirondacks and elsewhere) commonly contain coarsely exsolved pyroxenes with substantial amounts of exsolved orthopyroxene (in clinopyroxene) ...
Genesis and solvus relations of submicroscopically intergrown paragonite and phengite in a blueschist from northern California
(Springer-Verlag, 1991-01)
Electron microbeam techniques have been used to examine submicroscopically intergrown paragonite, phengite and chlorite from the South Fork Mountain Schist of the Franciscan Terrane of northern California, which was subjected ...
Origin and chemical evolution of formation waters from Silurian-Devonian strata in the Illinois basin, USA
(Elsevier, 1991-01)
A suite of formation-water samples from Silurian-Devonian reservoirs in the Illinois basin has been analyzed for major, minor and trace element concentrations and for H, O and Sr isotopic compositions in order to interpret ...
Gold deposition by sulfidation of ferrous Fe in the lacustrine sediments of the Pueblo Viejo district (Dominican Republic): The effect of Fe-C-S diagenesis on later hydrothermal mineralization in a Maar-Diatreme complex
(Elsevier, 1992-09-10)
The Pueblo Viejo district, located in the Cordillera Central of the Dominican Republic, contains large Au-Ag deposits associated with acid-sulfate alteration within spilites, conglomerates and carbonaceous sedimentary rocks ...
Oxidation states of the upper mantle recorded by megacryst ilmenite in kimberlite and type A and B spinel lherzolites
(Springer-Verlag, 1984-01)
The intrinsic oxygen fugacities of homogeneous, inclusion-free, megacryst ilmenites from the Frank Smith, Excelsior, Sekameng and Mukorob kimberlite pipes in southern Africa, and the alnöitic breccia in the Solomon Islands ...