Thesis (B.Sc.(Hons))--University of Adelaide, Department of Economic Geology,1974.

Thesis (Ph. D.)--Lehigh University, 2006. / Includes vita. Includes bibliographical references (leaves 110-116).

Thesis (M.S. - Hydrology)--University of Arizona, 1983. / Includes bibliographical references (leaves 137-140).

Thesis (M.S.)--Pennsylvania State University, 1960. / Includes bibliographical references (leaves 86-91).

Thesis (Ph. D.)--Johns Hopkins University, 1913. / Biography. Reprinted from vol. 1 of Upper Cretaceous, pub. by the Maryland geological survey.

No description available.

Thesis (M.S.)--Baylor University, 2007. / Includes bibliographical references (p. 95-98).

Thesis (M.S.)--University of Missouri-Columbia, 2008. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed July 14, 2009). Includes bibliographical references.

The lavas and pyroclastics of Ascension Island contain a suite of coarse grained igneous blocks which range in composition from olivine-gabbro to peralkaline-granite paralleling, but extending beyond the compositional range of the volcanics. The lavas range from alkali-basalt through hawaiite, trachybasalt, trachyandesite and trachyte to comendite. True basalt is relatively rare and there is a scarcity of analyses with 57 < Si02 < 63 wt %. No high pressure mineral assemblages and hence no possible mantle fragments have been found. Petrographic and isotopic data suggest that a suite of gabbros from Dark Slope Crater crystallised from a magma derived from a MORB-like source. The remaining blocks and all the lavas evolved from magmas derived from a less depleted source. The chemical variation seen in the lavas and blocks is best explained by crystal fractionation mechanisms in a relatively shallow magma chamber. The gabbroic blocks exhibit cumulus textures suggesting that they formed by accumulation of settling crystals. The intermediate to acid blocks compare much more closely in composition with the evolved lavas and are probably their slowly cooled equivalents. There is petrographic evidence that partial melting of intermediate coarse grained material gave rise to melts of granitic composition but these are not chemically equivalent to the acid lavas and blocks. A pegmatoid body crystallised in situ and closed system crystal fractionation alone resulted in a very similar sequence of mineral assemblages to the blocks and lavas and a peralkaline final liquid. High 87 S4/ 86 Sr ratios in the evolved lavas and blocks are attributable to contamination by a small quantity of highly radiogenic oceanic sediment. Comparison with other oceanic volcanoes suggests that these differentiation processes are much less important in determining the evolutionary path of the magma than its apparent starting composition.

This thesis attempts to unravel the complex thermal and structural history of part of the High Himalayan Slab in NW India and combines reconnaissance-style field structural mapping of an area covering ~10,000 km² with petrography, microstructural analysis, thermobarometry and geochronology techniques. The results of this work show that the oldest protoliths of the High Himalayan Slab are at least Cambrian in age and that they may have experienced a major pre-Himalayan metamorphism at c.500 Ma. The youngest protoliths are Mesozoic in age (the Tandi Group) and demonstrate that the High Himalayan Slab represents the metamorphosed equivalents of the Tibetan Sedimentary Series. Metamorphism was achieved via substantial crustal shortening and thickening following the India-Asia collision at 50-54 Ma ago. Phase relationships demonstrate that metamorphism was a regional Barrovian-type event associated with the growth of biotite-, garnet-, staurolite-, kyanite- and sillimanite-bearing assemblages in metapelites. Quantitative thermobarometry demonstrates that near-peak conditions of c.6-8 kbar and 550-650°C were attained in the deepest exposed levels. Growth of metamorphic assemblages was underway by at least 30 Ma, as indicated by U-Pb ages of metamorphic monazites. Exhumation of the High Himalayan Slab was achieved through a combination of extensional unroofing along major detachments (namely the Zanskar Shear Zone), thermal doming, thrusting along the Main Central Thrust and surface erosion. Exhumation is closely associated with the growth of sillimanite- and cordierite-bearing assemblages in pelites and the generation and emplacement of crustal melt leucogranites in the upper parts of the slab. U-Pb dating of accessory phases from one of the crustal melt leucogranites (the Gumburanjon leucogranite) constrains its crystallisation and emplacement age at c.21-22 Ma. This is only slightly older than its ⁴⁰Ar/³⁹Ar muscovite and biotite cooling ages of c.20-21 Ma, which is attributed to the emplacement of the Gumburanjon leucogranite into the immediate footwall of the ZSZ. Field and geochronological data therefore support a strong temporal and spatial relationship between upper crustal melting and extension in a convergent orogen.