Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 16 of 16 for “"Amphiboles"”.
-
A thermo-chemical analysis of some amphiboles
Thesis. (Ph.D.) Massachusetts Institute of Technology. Dept. of Geology, 1951.
-
Chemical controls on tetrahedral site occupancy in amphiboles
Thesis (M.S.)--Michigan State University. Dept. of Geology, 1971
-
Relationships between crystal structure, bonding and thermal stability of amphiboles
… in structure and chemical composition of the amphiboles and the wide range of their occurrence suggest that the amphiboles are potential index minerals for the physical conditions of their formation. Hydrothermal stability studies of several amphibole endmembers have demonstrated that the …
-
Iron-magnesium amphiboles: synthesis and stability with respect to temperature, pressure, oxygen fugacity, and sulfur frugacity
… to synthesize and investigate phase relations of amphiboles on the join Mg₇Si₈O₂₂(OH)₂-Fe₇Si₈O₂₂(OH)₂. Synthesized amphiboles from Mg₆Fe₁Si₈O₂₂(OH)₂ to Mg₁Fe₆Si₈O₂₂(OH)₂ are optically orthorhombic. Variation of unit cell parameters with composition suggests that they are members of a single, …
-
Sodium metasomatism and magnesio-riebeckite mineralization in the Wilson Ridge pluton
… that granitoid rocks containing hydrothermal amphiboles have lower delta18O values (+3.68‰ to +6.97‰) than unaltered granitoid rocks (delta 18O values +6.04‰ to +9.23‰).
-
Experimental studies of melting and crystallization processes in planetary interiors
… from the Mt. Shasta region, and apply it to amphiboles in these enclaves. Evidence for pre-eruptive H2O contents of up to 14 wt% is presented, and bulk chemical analyses of the inclusions are used to show that extensive magma mixing has occurred at all crustal depths up to 35km beneath Mt. …
-
Experimental studies of melting and crystallization processes in planetary interiors
… from the Mt. Shasta region, and apply it to amphiboles in these enclaves. Evidence for pre-eruptive H₂O contents of up to 14 wt% is presented, and bulk chemical analyses of the inclusions are used to show that extensive magma mixing has occurred at all crustal depths up to 35 km beneath Mt. …
-
Mafic magmatism in the Eastern Cordillera and Putumayo Basin, Colombia : causes and consequences
… minerals of the intrusions (clinopyroxenes and amphiboles) reflect the same dual character that has been found in the bulk-rock analyses. Despite the observed alteration of the rocks, the mineral composition shows evidences for an enriched and a relative depleted magma source. Even the …
-
Geochemistry, stable isotopes and fluid inclusion studies of the Otjikoto gold deposit, Central Namibia
… samples. Analysis of the microprobe data on the amphiboles shows that the analysed grains are made up of anthophyllites. Microprobe data of the chlorites showed that the majority of the chlorites are made up of ripidolites. Temperatures of chlorite formation were calculated to be in the range of …
-
The geology of the Khayyam and Stumble-On deposits, Prince of Wales Island, Alaska
… with compositions ranging from An₁₉ to An₃₁, and amphiboles that plot in the compositional fields of calcic ferro-and magnesio-hornblendes. These mineral compositions indicate metamorphism to the lower amphibolite facies. The Khayyam deposit was mined from 1901 to 1907, when approximately 250,000 …
-
Geology of the Piney River-Roseland titanium area, Nelson and Amherst counties, Virginia
… by the development of chlorite, biotite, and amphiboles from mafic minerals in the wall rock, and by saussuritization of the feldspars. Evidence indicates that most or all of the deposits formed by replacement of the wall rock. Titanium, fluorine, phosphorus, water and minor carbon dioxide …
-
Documenting multiple metasomatic events within the Finero phlogopite peridotite using chlorine isotopes, Ivrea zone, Italy
… between samples. Three distinct populations of amphiboles are defined on the basis of Na, K, Al, and Cr concentrations. Group 1 samples show a weak correlation in Cl vs. Na concentrations in amphibole, with an R² value of 0.414. Large variations in chlorine and hydrogen isotopic values occur …
-
The metamorphic sheet and underlying volcanic rocks beneath the Semail ophiolite in the northern Oman mountains of Arabia
… the Hawasina Complex. Low glaucophane content of amphiboles and low jadeite content of clinopyroxenes suggest relatively low pressures of crystallisation. The distribution coefficient K<sub>D</sub> for coexisting garnet and clinopyroxene suggests a temperature range of 670<sup>o</sup> to …
-
Petrogenesis of the Mesoproterozoic anorthosite, syenite and carbonatite suites of NW Namibia and their contribution to the metasomatic formation of the Swartbooisdrif sodalite deposits
… were produced. Thermobarometry studies on amphiboles yield temperatures of 985-950°C whereas the chemical composition of coronitic garnet and orthopyroxene indicate a subsolidus re-equilibration of the KIC at conditions of 760 ± 100°C and 7.3 ± 1 kbar. In the syenites Kfs, Pl, Hbl and/or …
-
The Porgera gold deposit, Papua New Guinea : geology, geochemistry and geochronology
… ratios in whole-rock samples, pyroxenes and amphiboles, and the presence of primary chromite/magnetite microphenocrysts indicate that the magma crystallized under conditions of high fo2. Least-evolved samples are characterized by low Ba/La (8 to 10), La/Nb (0.6 to 0.7) and Sr/Nd (~25) ratios, …
-
The Porgera gold deposit, Papua New Guinea : geology, geochemistry and geochronology
… ratios in whole-rock samples, pyroxenes and amphiboles, and the presence of primary chromite/magnetite microphenocrysts indicate that the magma crystallized under conditions of high fo2. Least-evolved samples are characterized by low Ba/La (8 to 10), La/Nb (0.6 to 0.7) and Sr/Nd (~25) ratios, …