FRINK Linked Data Fragments server

Matches in SemOpenAlex for { <https://semopenalex.org/work/W1981682366> ?p ?o ?g. }

• W1981682366 endingPage "214" @default.
• W1981682366 startingPage "173" @default.
• W1981682366 abstract "This paper presents and discusses the isotopic data from the hydrothermal studies of the Poços de Caldas Natural Analogue Project. The purpose of these studies was to elucidate the mass transport of relevant elements and isotopes associated with hydrothermal mineralization and alteration at the Osamu Utsumi uranium mine, as applicable to high-temperature radwaste isolation (particularly in the U.S. nuclear waste program). Research efforts were focused on studying the thermal, chemical and hydrologic nature of the palaeohydrothermal regime associated with a breccia pipe at the Osamu Utsumi mine, and related to the geochemical, geochronological and petrological characterization studies of unaltered regional nepheline syenite and phonolite. The regional rocks studies have a vertically elongated δD, δ18O pattern, which possibly indicates meteoric water/rock interaction. Regression of RbSr whole-rock isotopic data for the regional nepheline syenite and phonolite samples did not produce isochrons. An internal, mineral-separate isochron regression from a nepheline syenite sample, considered representative of unaltered nepheline syenite of the Poços de Caldas plateau, yields an age of 78 Ma, and an initial 87S86Sr ratio of approximately 0.7051. The initial 87Sr86Sr ratios of the regional nepheline syenites are possibly indicative of a mantle source for the alkaline magmatism, with some incorporation of old, high Rb/Sr crustal material. The greater-than-mantle values of δ18O, if not due solely to surficial processes, also appear to require some assimilation of crustal material. SmNd isotopic data for the regional rocks do not define any isochrons, although the nepheline syenite samples conform very well to a calculated reference isochron for 78 Ma and a fixed initial 143Nd/144Nd of 0.512359. The regional phonolite samples lie markedly off this isochron. This is probably due to the phonolite samples having different initial 143Nd/144Nd values. All regional samples lie within the “Mantle Array” trend. Their location within ϵNd–ϵSr space indicates as asthenospheric Mid Ocean Ridge Basalt (MORB)-type source magma also contaminated by continental igneous and metamorphic rocks (e.g. the Precambrian gneiss surrounding the Poços de Caldas plateau). The rocks studied at the Osamu Utsumi mine from the F4 drillcore have experienced varying degrees of hydrothermal mineralization and metasomatism, and deep weathering. The hydrothermally altered rocks have a quite pronounced δD shift, with only a slight δ18O shift. The δD-δ18O trend of the hydrothermally altered F4 samples most likely reflects the variability of temperature, hydrologic flow, mineralogical alteration and, therefore, water/rock interaction and isotopic exchange in the palaeohydrothermal regime. Regression of RbSr whole-rock isotopic data for subsamples from a nepheline syenite xenolith sample yields an age of 76 Ma and an initial 87Sr86Sr ratio of approximately 0.7053. Due to the marked hydrothermal alteration and metasomatism of this sample, the RbSr isotopic system is interpreted as being re-equilibrated and thus the regressed age is the age of the hydrothermal event. Using a (87Sr86Sr)1 versus 1/Sr mixing diagram, distinct trends are seen for hydrothermal alteration, mineralization and weathering. Again, the F4 nepheline syenite samples do not define an SmNd isochron, but conform very well to a calculated model isochron for 78 Ma and an initial 143Nd/144Nd of 0.512365. The SmNd isotopic data also exhibit a possible disturbance by the hydrothermal, metasomatic alteration. A lamproite dyke which crosscuts the hydrothermal alteration in the Osamu Utsumi mine gives an age of 76 Ma, which is essentially the same as the RbSr age of the hydrothermally altered nepheline syenite subsamples." @default.
• W1981682366 created "2016-06-24" @default.
• W1981682366 creator A5042394676 @default.
• W1981682366 date "1992-11-01" @default.
• W1981682366 modified "2023-10-05" @default.
• W1981682366 title "Isotopic geochemical characterization of selected nepheline syenites and phonolites from the Poços de Caldas alkaline complex, Minas Gerais, Brazil" @default.
• W1981682366 cites W1579931904 @default.
• W1981682366 cites W1979152102 @default.
• W1981682366 cites W2002834833 @default.
• W1981682366 cites W2016709163 @default.
• W1981682366 cites W2018006495 @default.
• W1981682366 cites W2027429612 @default.
• W1981682366 cites W2034203033 @default.
• W1981682366 cites W2043754460 @default.
• W1981682366 cites W2053342234 @default.
• W1981682366 cites W2064462016 @default.
• W1981682366 cites W2066044497 @default.
• W1981682366 cites W2066664533 @default.
• W1981682366 cites W2068202901 @default.
• W1981682366 cites W2069158051 @default.
• W1981682366 cites W2072191315 @default.
• W1981682366 cites W2084241674 @default.
• W1981682366 cites W2086637515 @default.
• W1981682366 cites W2094709181 @default.
• W1981682366 cites W2097328061 @default.
• W1981682366 cites W2101934152 @default.
• W1981682366 cites W2145604970 @default.
• W1981682366 doi "https://doi.org/10.1016/0375-6742(92)90125-r" @default.
• W1981682366 hasPublicationYear "1992" @default.
• W1981682366 type Work @default.
• W1981682366 sameAs 1981682366 @default.
• W1981682366 citedByCount "24" @default.
• W1981682366 countsByYear W19816823662015 @default.
• W1981682366 countsByYear W19816823662016 @default.
• W1981682366 countsByYear W19816823662017 @default.
• W1981682366 countsByYear W19816823662018 @default.
• W1981682366 countsByYear W19816823662020 @default.
• W1981682366 countsByYear W19816823662021 @default.
• W1981682366 countsByYear W19816823662022 @default.
• W1981682366 countsByYear W19816823662023 @default.
• W1981682366 crossrefType "journal-article" @default.
• W1981682366 hasAuthorship W1981682366A5042394676 @default.
• W1981682366 hasConcept C127313418 @default.
• W1981682366 hasConcept C156622251 @default.
• W1981682366 hasConcept C165205528 @default.
• W1981682366 hasConcept C17409809 @default.
• W1981682366 hasConcept C2779289598 @default.
• W1981682366 hasConcept C2910463356 @default.
• W1981682366 hasConcept C46381822 @default.
• W1981682366 hasConcept C487381 @default.
• W1981682366 hasConcept C57016615 @default.
• W1981682366 hasConcept C62074269 @default.
• W1981682366 hasConcept C67236022 @default.
• W1981682366 hasConceptScore W1981682366C127313418 @default.
• W1981682366 hasConceptScore W1981682366C156622251 @default.
• W1981682366 hasConceptScore W1981682366C165205528 @default.
• W1981682366 hasConceptScore W1981682366C17409809 @default.
• W1981682366 hasConceptScore W1981682366C2779289598 @default.
• W1981682366 hasConceptScore W1981682366C2910463356 @default.
• W1981682366 hasConceptScore W1981682366C46381822 @default.
• W1981682366 hasConceptScore W1981682366C487381 @default.
• W1981682366 hasConceptScore W1981682366C57016615 @default.
• W1981682366 hasConceptScore W1981682366C62074269 @default.
• W1981682366 hasConceptScore W1981682366C67236022 @default.
• W1981682366 hasIssue "1-3" @default.
• W1981682366 hasLocation W19816823661 @default.
• W1981682366 hasOpenAccess W1981682366 @default.
• W1981682366 hasPrimaryLocation W19816823661 @default.
• W1981682366 hasRelatedWork W1981682366 @default.
• W1981682366 hasRelatedWork W1985187585 @default.
• W1981682366 hasRelatedWork W1992756363 @default.
• W1981682366 hasRelatedWork W1996261707 @default.
• W1981682366 hasRelatedWork W2027487349 @default.
• W1981682366 hasRelatedWork W2033061823 @default.
• W1981682366 hasRelatedWork W2061632498 @default.
• W1981682366 hasRelatedWork W2061977424 @default.
• W1981682366 hasRelatedWork W3020920179 @default.
• W1981682366 hasRelatedWork W3165284211 @default.
• W1981682366 hasVolume "45" @default.
• W1981682366 isParatext "false" @default.
• W1981682366 isRetracted "false" @default.
• W1981682366 magId "1981682366" @default.
• W1981682366 workType "article" @default.