Physical Sciences and Mathematics Commons^™

A Geochemical Study Of The Sudbury Breccia, Kevin M. Prochaska

Masters Theses

The origin of the Sudbury Breccia surrounding the Sudbury Basin of Ontario, Canada has long been debated. The breccia has been described both as an igneous injection and as an abraded country rock formed by attrition in place.

A geochemical analysis of selected elements in matrix and clast samples from the breccia revealed distinct differences between the two sample groups. Matrix samples were lower in silicon and higher in heavy elements than the clasts. Matrix and clasts were comparable in light elements.

The results of the analysis favor an igneous process. Petrographic observations and structural evidence support this idea. The …

Some Chemical And Mineralogical Aspects Of Plutonic Rocks From The North Arm Mountain Massif, Bay Of Islands Ophiolite, Newfoundland, Jerry W. Sullivan

Geology Theses and Dissertations

Whole-rock major and trace element compositions of one basalt, one diabase, and 21 rocks from the magmatic-plutonic units of the North Arm Mountain massif, Bay of Islands ophiolite, Newfoundland, were determined. Mineral compositions of a subset of the plutonic rocks were also determined.
The major and trace element compositions of the basalt and diabase are similar to abyssal tholeiites, and this is consistent with the REE data of Malpas (1978) and Suen, et. al. (1979) that suggest the lavas and dikes formed from a depleted or slightly enriched abyssal tholeiitic magma. The alkaline nature of the magma proposed by several …

A Geochemical Study Of The Rhododendron And Dalles Formations In The Area Of Mount Hood, Oregon, Marshall W. Gannett

Dissertations and Theses

The Miocene Rhododendron and Dalles Formations in the Mount Hood area are accumulations of chiefly pyroclastic andesitic material, largely confined to the Dalles-Mount Hood syncline. These very similar units are geographically separated by overlying andesites including the present Mount Hood cone, and past workers (Hodge 1938, Wise 1969) have suspected that they may share a common source. Prior to this study, few geochemical data were available for the Rhododendron and the Dalles Formations, compared to the well studied Columbia River basalts underlying them and the overlying Pliocene andesites. This geochemical study was designed to investigate certain aspects of the Rhododendron …

A Stratigraphic And Geochemical Investigation Of Ferruginous Bauxite Deposits In The Salem Hills, Marion County, Oregon, Charles William Hoffman

Dissertations and Theses

Pacific Northwest ferruginous bauxite deposits have formed in four main areas of northwestern Oregon and southwestern Washington by laterization of flows of the Columbia River Basalt Group (CRBG). The deposits, averaging 36.3% Al₂O₃ , 31.8% Fe₂O₃ , and 5.9% Sio₂, generally occur near the surface of hilltops in gently rolling areas. Two very different views have been advanced regarding the setting in which the deposits have formed. The first hypothesis calls for a blanket-type laterization by erosion of much of the original deposit upon uplift and dissection of the area.