Open Access. Powered by Scholars. Published by Universities.®
Physical Sciences and Mathematics Commons™
Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 10 of 10
Full-Text Articles in Physical Sciences and Mathematics
Source Of Meta-Igneous Blocks And Structure Of The Colebrooke Schist In The Snowcamp Peak Area, Pickett Peak Terrane, Southwestern Oregon, Jennifer Katrib
Source Of Meta-Igneous Blocks And Structure Of The Colebrooke Schist In The Snowcamp Peak Area, Pickett Peak Terrane, Southwestern Oregon, Jennifer Katrib
Geology Theses and Dissertations
The Colebrooke Schist of the Pickett Peak terrane, southwestern Oregon, is the easternmost, structurally highest unit of the Late Mesozoic-Cenozoic Franciscan Accretionary Complex. The Colebrooke Schist consists of mostly transitional greenschist-blueschist-facies meta-sedimentary rocks with common blocks of meta-volcanics and serpentinites, rare talc-schists and meta-plutonic rocks. The Colebrooke Schist meta-volcanic blocks are greenstones, in many cases with visible relict pillow structures and relict igneous textures.
Fifteen meta-volcanic samples and one meta-plutonic sample were analyzed by XRF and ICP-MS and were plotted with analyses from Plake (1989) and Coleman (1972). The Colebrooke Schist meta-volcanic rocks plot in mid-ocean ridge basalt (MORB), island …
Slickenside Petrography: Slip-Sense Indicators And Classification, Young-Joon Lee
Slickenside Petrography: Slip-Sense Indicators And Classification, Young-Joon Lee
Geology Theses and Dissertations
Petrographic study has been carried out on slickenside thin sections, to find out reliable microstructures for determining the slip-sense of faults, and to classify slickensides morphologically. Thin sections are made cut parallel to the striation and perpendicular to the slip plane. Many useful slip-sense indicators are found in thin section even though such indicators may be absent in hand specimens. They are (1) off-set or bending of once-continuous bodies such as veins, layers, grains or twin lamellae, (2) crystal fibers growing nearly parallel to the slip direction, (3) extensional fractures aligned oblique to the slip plane, (4) S-C geometries in …
Geology Of The Northern Baie Verte Peninsula, Newfoundland, Canada, Pamela J. Stella
Geology Of The Northern Baie Verte Peninsula, Newfoundland, Canada, Pamela J. Stella
Geology Theses and Dissertations
On the eastern portion of the Burlington Peninsula of northwest central Newfoundland, Canada, there are two different age groups of volcanic and volcaniclastic rocks. There have been arguments in the past as to whether or not these two groups are actually only one group (Cape St. John Group) but with progressive intensity of deformation and metamorphism from south to north. Other workers have divided the rocks into two distinct groups, the Grand Cove Group and the Cape St. John Group based on their differences in deformation style and metamorphic grade. This study ignored previous divisions of the rocks into one …
Stratigraphy And Structure Of The Ganson Hill Area: Northern Taconic Allochthon, Michelle Aparisi
Stratigraphy And Structure Of The Ganson Hill Area: Northern Taconic Allochthon, Michelle Aparisi
Geology Theses and Dissertations
The Ganson Hill study area is located in the Giddings Brook Slice of the Taconic Allochthon. It contains rocks of Cambrian(?), Cambrian and Ordovician age. The predominant rock type is slate with subordinate lithologies including quartzite, limestone, micrite, arenite and graywacke. The lithostratigraphy identified in the Ganson Hill area extends from the basal Bomoseen wacke to the Poultney slate. A more precisely defined lithostratigraphy is derived from the study area by the occurrence and recognition of the Middle Granville Slate Formation and the documentation of a second Cambrian black/green boundary. Previous workers have included this formation in different places, in …
A Numerical Approach For Determining The Variable Ascent Velocity Of A Granitoid Diapir, Keith I. Mahon
A Numerical Approach For Determining The Variable Ascent Velocity Of A Granitoid Diapir, Keith I. Mahon
Geology Theses and Dissertations
A mathematical model for granitoid diapirism has been developed that accounts for the time dependent thermal and rheological conditions encountered by the intruding body. This model is derived by the simultaneous solution of the partial differential equations of energy, continuity, and momentum utilizing scaling analysis. The underlying assumption is that deformation of the surrounding country rock is confined to a relatively thin layer with a temperature dependent Newtonian viscosity. When the country rock is modeled as a power-law fluid, the effective viscosity is dependent upon temperature and shear strain rate.
This model allows for realistic temperature gradients within the crust …
Structural Analysis Of Deformed Carboniferous Strata, Mispec Beach, Southern New Brunswick, Lauren Magin Bradley
Structural Analysis Of Deformed Carboniferous Strata, Mispec Beach, Southern New Brunswick, Lauren Magin Bradley
Geology Theses and Dissertations
Mispec Beach, New Brunswick is a coastal exposure of deformed Carboniferous sedimentary rocks. Late Paleozoic deformation in the region is thought to have occured in a restraining bend in the Cobiquid - Chedabucto fault.
Within this exposure, two main generations of deformation are recognized. The first deformation is associated with slaty cleavage development, pebble elongation, and the formation of quartz veins. The second generation structure is a moderately developed crenulation cleavage. The diversity of structures present at this outcrop allows for a qualitative determination of the principal axes of stress and strain associated with the first generation structures.
Some Aspects Of Deformation Fabrics Along The Highland/Lowland Boundary, Northwest Adirondacks, New York State, Peter C. Hall
Some Aspects Of Deformation Fabrics Along The Highland/Lowland Boundary, Northwest Adirondacks, New York State, Peter C. Hall
Geology Theses and Dissertations
The Geology of the Whippoorwill Corners Area, NW Adirondacks, NYS
In the northwestern Adirondack Mountains of New York State lies a 110 km long, 0-5 km wide topographic and lithologic boundary which divides the Adirondack Highlands from the Northwest Lowlands. Structurally this boundary is apparently a highly strained zone of intensely foliated and lineated rocks. Within the zone mineral grains are highly recrystallized and of fine grain size with respect to rocks outside the zone, quartz becomes undulose, and mineral assemblages frequently exhibit retrograde characteristics. Despite the apparent high strain no demonstrable offset may be seen across the zone. Furthermore, …
Structural Analysis Of An Area Near Middlebury, Vermont, Paul A. Washington
Structural Analysis Of An Area Near Middlebury, Vermont, Paul A. Washington
Geology Theses and Dissertations
Detailed mapping of an area near Middlebury, Vermont, reveals a multiple deformational scheme quite different from that previously proposed. The published stratigraphy of the middle Ordovician limestones, on which earlier structural theories are based; was found to be inaccurate, so a new system has been defined. An unreported early generation of cleavage has been discovered which indicates the existence of a decollement zone in the upper Bascom formation. The second generation of cleavage and its associated folding were well defined by earlier workers, but this study shows that it is also a thin-skinned event.
The last deformation, as exhibited by …
Geology Of The Mafic/Ultramafic Transition, Table Mountain, Western Newfoundland, Suzanne O'Connell
Geology Of The Mafic/Ultramafic Transition, Table Mountain, Western Newfoundland, Suzanne O'Connell
Geology Theses and Dissertations
A thin (<200 m.) mafic suite and well developed mafic/ultramafic transition zone are exposed above a flat lying peridotite contact on northwestern Table Mountain. The igneous layering and sedimentary features indicate mineral deposition under conditions which promoted adcumulate growth, were capable of minor transport, and were subjected to at least minor tectonic activity during consolidation. Feldspathic,. mafic, and ultramafic dikes and veins cross-cut the layering. Microscopic futures indicate deformation at elevated temperature and/or low strain rates. Deformation is best developed within the transition zone, but cataclastic zones are most common in the hornblende gabbros. Orientations of layering, foliation, and lineation indicate a variable mafic/ultramafic transition and macroscopic folding. Geometric analysis indicates three distinct fold axis orientations: an east-west horizontal fold axis, a northeast trending modestly plunging axis, and a vertical though poorly defined axis. Such features demonstrate that an apparently simple contact relationship may be extremely complex. This has important implications for ocean floor accretion. The relatively simple ocean floor seismic stratigraphy masks very complex petrological and structural processes. Such processes may involve deposition in an actively convecting magma chamber with a differentially subsiding wedge (Dewey and Kidd, 1977), in which folding occurs in response to the steepening angle between the cumulate banding and the base of the magma chamber. The instability is enhanced by the different accumulation rates and densities of the minerals involved. The lineation may originally be a sedimentary feature indicative of transport direction from the convection cell, and perpendicular to the compressive stress which produced. the folding. The different orientations of lineations and fold axes could be produced by rotation of the ocean crustal blocks during lateral transport along the ocean floor and/or obduction. Further detailed study of ophiolite complexes will continue to shed light upon the nature and development of oceanic crust.
Geology Of The Badger Bay-Seal Bay Area, North-Central Newfoundland, K. Douglas Nelson
Geology Of The Badger Bay-Seal Bay Area, North-Central Newfoundland, K. Douglas Nelson
Geology Theses and Dissertations
Coastline in the Badger Bay-Seal Bay area of north-central Newfoundland exposes the thickest and least disrupted section of Ordovician rocks in Newfoundland's Central Volcanic Belt. The following conformable stratigraphic sequence is observed: 1) >5 km. of variegated mafic and silicic submarine volcanics and volcaniclastics of lower Ordovician age; 2) a thin (<.5 km.) sequence consisting of thin bedded red and green argillites, manganiferous cherts, bioturbated cherts and black sulferous graptolite-bearing argillites of Caradocian age; 3) >1.2 km. of quartz-rich sandstones of upper Ordovician age. Correlative sequences occur to the east in the Fortune Harbour Peninsula area and on New World Island. Together they record Early Ordovician island arc volcanism, Medial Ordovician cessation of volcanism and subsidence, and Medial through Late Ordovician uplift and …