Stratigraphy Commons^™

Stratigraphy, Depositional Environment And Structure Of The Taconic Allochthon, Central Washington County, New York, Louise D. Jacobi

Geology Theses and Dissertations

The Taconic Allochthon contains rocks of Cambrian (?), Cambrian and Ordovician age. It measures approximately 200 kilometers by 25 kilometers and is located in contiguous sections of New York, Vermont, Massachusetts, and Connecticut. The rocks are predominantly slates with lesser amounts of arenites, wackes, limestone, chert, and conglomerates. All have been subjected to chlorite or biotite grade metamorphism and two tectonic deformations. The study area in central Washington County, New York, contains most of the Taconic sequence, and because of both natural and man-made exposure it is more accessible than most other locations. A lithostratigraphic column has been identified which …

Long-Distance Turbidite Correlations In The Horseshoe Abyssal Plain, William H. Hoyt

Geology Theses and Dissertations

Few studies on modern abyssal plain turbidites have attempted to assess the lateral extent of individual units and few have therefore been able to provide any information on the evolution of turbidity deposits across long abyssal plain distances. In the 4755 m-deep Horseshoe Abyssal Plain, ten distinct lithologic units (six of these Iberian Peninsula-derived turbidites) were delineated in nine piston cores on the basis of stratigraphic position, thickness (range of 20 cm to greater than 500 cm), color, sediment type, sedimentary structures, x-ray mineralogy, and the ubiquitous presence of units in all abyssal plain and supplying canyon piston cores. In …

Structural Studies In The Northern Chester Dome Of East-Central Vermont, Bruce Wallace Nesbit

Geology Theses and Dissertations

Rocks in the Eastern Vermont Sequence are highly metamorphosed and are said to range in age from Precambrian to Siluro-Devonian. The sequence outcrops on Keyes Mountain, about 6km Northwest of Felchville, Vermont, and an area on this mountain about 2km square was mapped in great detail.
The dominant rock type found is quartzofeldspathic gneiss, but schistose gneiss, amphibolite, quartzite and schist also occur. Most of these rocks are layered but layering has been transposed in many places and much of it is probably secondary. Layering and schistosity both dip dominantly to the north at about 25º.
A number of mesoscopic …

A Study Of Some Petrologic And Structural Aspects Of The East Dover Ultramafic Bodies, South Central Vermont, Mark Allen Hoffman

Geology Theses and Dissertations

INTRODUCTION (pp.1-4)

Mineralogical, textural and chemical changes of ultramafic rocks in response to regional deformation and metamorphism are, at best, imperfectly known (Miyashiro, 1973, p. 30). In Vermont, which has an extremely prominent and well-exposed belt of ultramafics (fig. 1), investigation of these rocks has largely been directed toward such processes as serpentinization, steatitization, and the formation of metasomatic zones at the contacts with country rocks. With few exceptions, there is a lack of detailed descriptions of regional metamorphic textures, mineralogy, and structures developed in the Vermont ultramafic rocks. It is the main purpose of this thesis to describe the …

Petrology Of The Nemeiben Lake Ultramafic And Associated Nickel-Sulphide Deposits, Anantaramam Peddada

Geology Theses and Dissertations

The Nemeiben Lake ultramafic body is located in the center of Saskatchewan, Canada, within the Churchill Province of the Canadian Shield. The ultramafic rocks consist of serpentinites, partly serpentinized and uralitized pyroxenite, and unaltered pyroxenite. Associated sulphide mineralization is of disseminated, net texture, and fracture filling types. The ore minerals present are pyrrhotite, pentlandite, chalcopyrite, pyrite, marcasite, violarite, bravoite and native copper. The sulphides are considered to be initially of magmatic origin formed from a sulphide melt separated at a late stage during crystallization of the ultramafic rocks. Subsequent serpentinization has locally redistributed the ores.
Serpentinization in the Nemeiben Lake …