The primary and secondary mafic silicates from the Amba Dongar carbonatitic-alkaline complex, Gujarat, India and the Strange Lake peralkaline granitic complex, Quebec-Labrador, Canada are the subject of this investigation of their origin, evolution and relationship to mineralization. Primary minerals are transformed by a variety of processes related to their crystallization history. The most important of these processes are: magma evolution, magma degassing and metasomatism. These processes are commonly associated with the evolution of peralkaline granitic and carbonatitic-alkaline complexes, and with the formation of associated mineral deposits (e.g., fluorite in the Amba Dongar complex; Zr-, REE- (rare-earth elements), Be-, Nb-and Y-rich deposit in the Strange Lake complex). Although all minerals in these complexes may be subject to these changes, the mafic silicates amphibole, pyroxene and mica are of particular interest, as they remain poorly studied and may comprise up to 10 vol.% of the rock. Moreover, they can contain significant quantities of high field-strength elements (HFSE), which may be mobilized following interaction with later fluids, and deposited as secondary minerals in the ore zone. / In the Amba Dongar complex, Na-metasomatism followed by K- (or Mg-) metasomatism resulted in the formation of fenites, with mobilization of HFSE, among other trace elements. Vermiculite was formed by a subsequent stage of hydrothermal alteration, which is also responsible for formation of the fluorite deposit. In the Strange Lake complex, enrichment of the primary arfvedsonitic amphibole in HFSE and REE is related to magmatic evolution, whereas later degassing released sufficient amounts of volatiles and Na that the amphibole became more potassic and aegirine crystallized. This amphibole acted as a sink for trace elements such as Li, HFSE and REE. These elements were remobilized during Na-metasomatism through replacement of amphibole by aegirine, and deposited as secondary, generally Ca-rich, minerals (e.g., winchitic amphibole and biopyriboles) during later, lower-temperature Ca-metasomatism. Primary mafic silicates in alkaline complexes can thus undergo metasomatic reactions that result in the mobilization of elements that contribute to formation of related ore deposits. These findings concerning the solid phases involved in both localities correlate very well with indications of mixing of two distinct fluid phases.

The meteorite impact that formed the 32-km-diameter Upper Pennsylvanian (285 +/- 23 Ma) West Clearwater structure, situated about 125 km east of the Hudson Bay arc, northern Quebec, formed a sheet of impact melt now exposed on a central ring of islands. At least seven marble enclaves have been mapped in the melt sheet; this report is based on observations made on samples from two of these enclaves. These blocks represent recrystallized remnants of a cover of Middle Ordovician limestone, now completely eroded in the area. While the impact melt was still above its solidus, the locally fossiliferous dolomite-bearing limestone recrystallized to granoblastic calcite + periclase marble. The silica content of the marble led to the formation of a sanidinite-facies assemblage of unusual nesosilicates such as spurrite, Ca5(SiO4)2(CO3), merwinite, Ca 3Mg(SiO4)2, and monticellite, CaMgSiO4. Aluminian srebrodolskite, Ca2(Fe3+,Al)2O 5, the Fe3+-dominant analogue of brownmillerite, Ca 2(Al,Fe3+)2O5, is found in material with a composition similar to "Portland cement clinker". At its type locality, srebrodolskite is attributed to the calcining of ankeritic carbonate. Phase equilibrium and stratigraphic data constrain peak conditions of metamorphism to at least, T ≈ 815º +/- 15ºC, P < 100 bar and X(CO2) > 0.1. Retrograde mineral assemblages indicate that X(CO2) < 0.1 was achieved shortly after peak metamorphism owing to influx of H2O. Portlandite, Ca(OH)2, is one of several species formed during late hydration of the assemblage upon cooling.

Apatite occurs as an accessory phase throughout the Sudbury Igneous Complex (SIC), Ontario, as well as in the overlying tuffaceous rocks of the Onaping Formation (OF). This investigation was designed to characterize the textural development and composition of apatite. Representative samples were taken from three traverses: the NW suite is the most pristine. Apatite is found primarily as a post-cumulus (or intergranular) phase, but becomes a cumulus mineral in the quartz gabbro. The apatite is F-rich; Cl and OH contents decrease from the base of the complex upward. Apatite in the OF has higher inferred levels of OH. In the SIC, Cl and OH decreased relative to F upon vapour saturation of the evolving melt. The concentrations of LREE, up to 2 wt% La$ rm sb2O sb3+Ce sb2O sb3+Nd sb2O sb3,$ are higher in apatite near the base of the complex. The chondrite-normalized REE patterns, and $ sp{87}$Sr/$ sp{86}$Sr ratios (0.707-0.708), are similar in apatite from each rock type of the Main Mass. The SIC evolved normally by fractional crystallization of a single batch of basic magma, which likely resulted from an impact-generated crustal melt. Apatite from the SW section and, to a lesser extent, the NE section, has significantly lower levels of Cl and LREE; the $ sp{87}$Sr/$ sp{86}$Sr ratio has also been reset (up to 0.739). Local recrystallization during metamorphism thus led to remobilization of these elements from apatite.

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1990. / Vita. Abstract. Includes bibliographical references. Also available via the Internet.

Proefschrift (D. Agr.)--Landbouwhoogeschool te Wageningen. / "Literatuur": p. 211-216.

Inaug.-diss.--Erlangen. / Lebenslauf. "Literaturübersicht": p. [5]-8.

Inaug.-Diss.--Leipzig. / Vita.

Thesis (M.A.)--University of Wisconsin--Madison, 1969. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Presented as Thesis (Ph. D.)--University of Wisconsin--Madison, 1924. / Reprinted from American journal of science, vol. XVI (Nov. 1928), p. 423-445. Includes bibliographical references.

Inaug.-diss.--Freiburg i. Br.