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Full-Text Articles in Physical Sciences and Mathematics

Evaluation Of Computational Methods Of Paleostress Analysis Using Fault-Striation Data, Steven Henry Schimmrich Jan 1991

Evaluation Of Computational Methods Of Paleostress Analysis Using Fault-Striation Data, Steven Henry Schimmrich

Geology Theses and Dissertations

Over the past 12 years, many different computational methods or variations of existing methods have been proposed for determining paleostress tensors from fault populations and their slip directions. These methods are all based upon well-known relationships between stress and shear and use iterative, non-linear mathematical algorithms which seek to minimize the angles between the calculated maximum shear stress direction and the observed movement directions on each fault plane in a population. The solution returned is the best-fit paleostress tensor for the population.
By taking the Coulomb failure criterion into account, several paleostress analysis programs have been able to use linear, …

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The Geology Of Taconic Thrust Sheets And Surrounding Carbonates Of The West Central Vermont Marble Belt, North Of Rutland, Vermont, Kay Bierbrauer Jan 1990

The Geology Of Taconic Thrust Sheets And Surrounding Carbonates Of The West Central Vermont Marble Belt, North Of Rutland, Vermont, Kay Bierbrauer

Geology Theses and Dissertations

The carbonates of the Vermont Valley and the overlying rocks of the Taconic sequence have been generally believed to lie on the east limb of a major unfaulted syncline (Middlebury Synclinorium). In this view a westward dipping, north-south trending basal Taconic overthrust must be exposed somewhere along the eastern margin of the Taconic Range.
In contrast, this study based on detailed mapping at the north end of the Taconic Allochthon suggests that a folded overthrust surface is only locally seen in fensters; more commonly the basal obduction surface of the Taconic Allochthon has been truncated by later cross-cutting thrust faults. …

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Petrology Of The Kula Volcanic Field, Western Turkey, Julie M. Dyer Jan 1987

Petrology Of The Kula Volcanic Field, Western Turkey, Julie M. Dyer

Geology Theses and Dissertations

The Kula volcanics are a small Pleistocene to Recent volcanic field located on the north shoulder of the Gediz graben, approximately 120 km east of Izmir. The field consists of a mixture of flows, small cones and pyroclastic deposits erupted during three periods of volcanic activity beginning about one million years ago. The volcanics range in composition from basanites to trachybasalts, commonly porphyritic with abundant clinopyroxene, olivine and amphibole phenocrysts. The lavas also host a wide variety of megacrysts, crustal xenoliths and hydrous mantle-derived nodules. These volcanics unconformably overlie Neogene lacustrine sedimentary rocks and the metamorphic basement rocks of the …

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Structural Analysis Across The Northeast Boundary Of The Taconic Allochthon, West-Central Vermont, Thomas E. Hoak Jan 1987

Structural Analysis Across The Northeast Boundary Of The Taconic Allochthon, West-Central Vermont, Thomas E. Hoak

Geology Theses and Dissertations

The Taconic Allochthon is an elongate belt of Cambro-Ordovician, argillaceous sediments with lesser occurrences of calcareous and siliceous lithologies. These lithologically distinctive strata lie tectonically juxtaposed over a coeval medial-Ordovician carbonate shelf sequence. This geometry resulted from an arc-continent collision in which a westward-migrating arc (Ammonoosuc Volcanics) collided with an eastern North America passive margin and the accumulated accretionary prism of the forearc region was thrust onto the passive continental margin.
The present thesis examined the structural sequence at the north end of the Allochthon and the continuity of this sequence into the adjacent Parautochthonous Shelf strata. Structurally, the study …

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Structural Investigations On Experimentally And Naturally Produced Slickensides, Thomas Michael Will Jan 1987

Structural Investigations On Experimentally And Naturally Produced Slickensides, Thomas Michael Will

Geology Theses and Dissertations

This work has involved an experimental approach and a study of naturally produced slickensides.
The experiments, carried out on a pyrophyllitic rock, have been performed in order to define some extrinsic parameters that control surface and microstructural features. Normal stress, speed (i.e. strain rate), and amount of slip and total displacement were related to measureable surface features, such as length, and spacing between the developing ridges and grooves. Special attention was paid to a newly recognized type of slickenside lineation (Means, 1986). This lineation produced experimentally cannot be explained in terms of the traditional asperity ploughing or dissolution/precipitation models. It …

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Sedimentology And Tectonic Significance Of The Nutzotin Mountains Sequence, Alaska, Jane Kozinski Jan 1985

Sedimentology And Tectonic Significance Of The Nutzotin Mountains Sequence, Alaska, Jane Kozinski

Geology Theses and Dissertations

The Nutzotin Mountains Sequence, a Mesozoic flysch sequence in the eastern Alaska Range, was studied along the southern border and in the central portions of the outcrop belt. Three lithologic associations are recognized in the Bonanza Creek section (southern margin) that together indicate a coarsening-upward trend, suggestive of a prograding fan system. These associations are (from bottom to top): 1) debris flow conglomerates overlain by 500 m of intercalated mudstone and base-missing turbiditic siltstone, and mass movement features such as slump folds and slump horizons, 2) 195 m of thicker, coarser turbidites intercalated with mudstones; turbidites are graded but lack …

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Tectonic Implications Of Late Tertiary Strata Exposed Along The Piankatank River, Eastern Virginia, Daniel Stephen Lane Oct 1984

Tectonic Implications Of Late Tertiary Strata Exposed Along The Piankatank River, Eastern Virginia, Daniel Stephen Lane

OES Theses and Dissertations

Biostratigraphic analysis of Late Miocene and Pliocene strata along the Piankatank River in eastern Virginia exposes a juxtaposition of the Eastover and Yorktown Formations. This structure is situated on a NE trending alignment of geological, geomorphic, and geophysical features which run from southern Virginia to northern Delaware. Tectonic jointing in isolated sandstone bodies and fracture controlled drainage patterns provide further evidence of post-middle Pliocene tectonism in the region. The lateral spacing of this structure from the Stafford and Brandywine fault zones and other linear features on the Coastal Plain strongly implies that a structural similarity exists between the Piankatank structure …

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The Influence Of Oceanic Transform Boundaries On The Generation And Evolution Of Oceanic Lithosphere, David G. Gallo Jan 1984

The Influence Of Oceanic Transform Boundaries On The Generation And Evolution Of Oceanic Lithosphere, David G. Gallo

Geology Theses and Dissertations

The first-order geologic and morphologic relationships at, along and proximal to ridge-transform-ridge plate boundaries are used to construct an empirical and speculative tectonic model. The geometry of a ridge-transform intersection necessitates the juxtaposition of relatively cold, thick lithosphere against the truncated end of an accreting plate boundary. The cold face of lithosphere cools the adjacent wedge of asthenosphere rising beneath the axis of accretion and restricts the amount of partial melting thus attenuating the amount of basaltic melt segregated from the asthenosphere per unit time. The manifestation of this cold edge effect is a thinner oceanic crust. At depth, upper …

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The Tectonic Evolution Of The Eastern Yukon Tanana Upland, Alaska, Grant W. Cushing Jan 1984

The Tectonic Evolution Of The Eastern Yukon Tanana Upland, Alaska, Grant W. Cushing

Geology Theses and Dissertations

Field, structural, and isotopic studies in the southeastern Eagle Quadrangle reveal a complex Mesozoic history involving major metamorphism, fold development, thrusting, and igneous intrusion. These events may be related to the accretion of a terrane, possibly Stikine, to the North American continental margin.
40Ar/39Ar incremental heating experiments on metamorphic minerals from amphibolite facies rocks reveal Late Triassic to Middle Jurassic plateau ages interpreted as the age of major metamorphism. Large scale northeast trending folds within these rocks formed after the major metamorphism and before the intrusion of an undeformed, unmetamorphosed cross-cutting dike in Middle Jurassic. These folds probably developed in …

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Geology Of The Fondo Negro Region, Dominican Republic, J. Calvin Cooper Jan 1983

Geology Of The Fondo Negro Region, Dominican Republic, J. Calvin Cooper

Geology Theses and Dissertations

Detailed geologic mapping of the Fondo Negro-Sierra de Martin Garcia region of the Southwestern Dominican Republic establishes that this area is part of a broad and diffuse Northern Caribbean plate boundary zone (PBZ). Faulting in the study area is predominantly left lateral strike-slip, with secondary compression (thrusting) causing both substantial, and rapid, uplift of the region. Folding associated with the wrench faulting affects rocks of all ages in the field area from Paleocene limestones to Quaternary alluvial fans.
New stratigraphic designations are proposed for mappable litho-units in the area, and these are correlated with Hispaniola stratigraphy in general based on …

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The Pre-Tertiary Geology And Mesozoic Tectonic Evolution Of Eastern China, Southeast Asia And Adjacent Regions, Michael P. Klimetz Jan 1983

The Pre-Tertiary Geology And Mesozoic Tectonic Evolution Of Eastern China, Southeast Asia And Adjacent Regions, Michael P. Klimetz

Geology Theses and Dissertations

Several orogenic belts transecting south-eastern Asia are the sites of former convergent plate margins although there have been varying interpretations of the collisional framework of individual continental blocks, styles of convergence at these zones and the timing of respective collisions. A comprehensive tectonic study of eastern China, Mongolia and the southern Soviet Far East indicates the collision of the South China Block with a combined North China-Northeast China Fold Zone Block in the late Triassic-early Jurassic, their collective suturing to Eurasia in the late Jurassic-early Cretaceous, followed by the Sikhote Alin-Japan Block in the mid to late Cretaceous. The evidence …

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Structure And Stratigraphy Of West Haven, Vermont, Christoph K. Steinhardt Jan 1983

Structure And Stratigraphy Of West Haven, Vermont, Christoph K. Steinhardt

Geology Theses and Dissertations

Mapping and structural investigations in an area bounded to to the west by by Grenvillian basement and to the east by allochthonous rocks emplaced during the medial Ordovician Taconic Orogeny led to division of the area into a Western Undeformed Zone and an Eastern Deformed Zone. The former consists of a thin, undeformed shelf sequence of upper Cambrian to lower Ordovician (Canadian) clastics and carbonates, which unconformably overlie Grenvillian basement and dip gently to the east.
The Eastern Deformed Zone consists of early to medial Ordovician carbonates folded about northnortheast trending axes with east to southeast dipping axial surfaces, overlain …

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Structure And Tectonics Of The Keban Metamorphics In The Northern Margin Of The Bitlis Suture Zone, Southeastern Turkey, Gültekin Savci Jan 1983

Structure And Tectonics Of The Keban Metamorphics In The Northern Margin Of The Bitlis Suture Zone, Southeastern Turkey, Gültekin Savci

Geology Theses and Dissertations

The study area near Keban consists of the allochthonous Keban division of the Keban-Malatya crystalline complex and the Yuksekova island-arc rocks of the Bitlis-Puturge Complex in the northern margin of the Bitlis Suture Zone. Detailed mapping shows that the Palaeozoic-Triassic Keban Metamorphics are composed of the following formations: (1) white, massive, karstic Kirklar Marble; (2) phyllitic psammite with calcschist interlayers Calik Formation; and (3) semi-crystallized gray Koyunatlayan Limestone. These formations define a tectonostratigraphy with the Kirklar Marble at the base and the Koyunatlayan Limestone at the top. The detailed lithological description of the Keban Metamorphic rock assemblages suggest that they …

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The Structural Geology Of The Tectonized Ultramafic Suite Of The Table Mountain Massif, Bay Of Islands Complex, Newfoundland, Robert Whitney Blake Jan 1982

The Structural Geology Of The Tectonized Ultramafic Suite Of The Table Mountain Massif, Bay Of Islands Complex, Newfoundland, Robert Whitney Blake

Geology Theses and Dissertations

Table Mountain is the northernmost massif in the Bay of Islands Ophiolite. It represents a continuous, approximately 7 kilometer thick, section of residual harzburgite tectonites capped by a nearly flat-lying assemblage of deformed and undeformed cumulate rocks. The notable mesoscopic structural features of the massif include a zone of penetrative deformation extending upsection from the tectonized harzburgites approximately 500 meters into the dunites and basal cumulates. The orientation of the foliation and associated lineations as well as the inferred shear sense within the zone is consistent with that affecting the harzburgites. Highly deformed dunite lenses which range in thickness up …

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Structure Of The Northern Margin Of The Bitlis Suture Zone Near Sivrice, Southeastern Turkey, Mark R. Hempton Jan 1982

Structure Of The Northern Margin Of The Bitlis Suture Zone Near Sivrice, Southeastern Turkey, Mark R. Hempton

Geology Theses and Dissertations

Detailed mapping near Sivrice shows that the northern margin of the Bitlis Suture zone consists of three major tectonostratigraphic units outcropping as distinct north-dipping thrust slices. From south to north these are: (1) the Pütürge Complex; (2) the Maden Complex; and (3) the Elazig Complex.
The pre-Eocene Pütürge Complex consists of 80% metapelite, 15% metaquartzite, and 5% recrystallized limestone. These rocks represent a continental margin sequence that has been metamorphosed to the lower greenschist facies. There are three generations of structural elements: (1) a transposition foliation and macroscopic isoclinal folds, (2) a crenulation cleavage and mesoscopic folds, and (3) kink …

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Permo-Triassic Reconstruction Of Western Pangea And The Evolution Of The Gulf Of Mexico-Caribbean Region, James Lawrence Pindell Jan 1981

Permo-Triassic Reconstruction Of Western Pangea And The Evolution Of The Gulf Of Mexico-Caribbean Region, James Lawrence Pindell

Geology Theses and Dissertations

A Permo-Triassic reconstruction of western Pangea (North America, South America, Africa) is proposed that is characterized by: 1) definition of the North Atlantic fit by matching of marginal offsets (fracture zones) along the opposing margins, 2) a South Atlantic fit that is tighter than the Bullard fit and that is achieved by treating Africa as two plates astride the Benue Trough and related structures during the Cretaceous, 3) complete closure of the Proto-Atlantic Ocean between North and South America, accomplished by placing the Yucatan block between the Ouachita Mountains and Venezuela, 4) a proposed Hercynian suture zone that separates zones …

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Structural Studies Of The Ordovician Flysch And Melange In Albany County, New York, Frederick W. Vollmer Jan 1981

Structural Studies Of The Ordovician Flysch And Melange In Albany County, New York, Frederick W. Vollmer

Geology Theses and Dissertations

The middle Ordovician rocks of the Albany 15 minute quadrangle comprise interbedded graywacke and shale, and in the east, coarse cobble or olistostromic deposits. The detrital composition, westward fining and regional westward transgression of these deposits indicate that these were sediments shed off the westward thrusting Taconic Allochthon. Primary sedimentary structures show that these rocks were deposited by turbidity currents flowing into a longitudinal trough, probably formed in response to increased load during overthrusting. Although strongly dependent on lithology, deformation intensity generally increases from west to east; from essentially undeformed bedded flysch through asymmetrically folded and thrust beds to highly …

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Complex Structure And Stratigraphy Of Lower Slices Of The Taconic Allochthon Near Middle Granville, New York, David B. Rowley Jan 1980

Complex Structure And Stratigraphy Of Lower Slices Of The Taconic Allochthon Near Middle Granville, New York, David B. Rowley

Geology Theses and Dissertations

The Precambrian (?) to medial Ordovician rocks of the Taconic Allochthon are characterized by argillaceous and arenaceous sediments with lesser associated carbonates, carbonate breccias, and cherts of predominantly deep-water aspect. These allochthonous rocks tectonically overlie an autochthonous to parautochthonous coeval sequence of dominantly shallow marine clastics and carbonates of the Champlain and Vermont Valley sequences. Facies, thickness, sedimentologic, and paleontologic considerations suggest that these coeval sequences represent a carbonate shelf continental rise pair of the east-facing early Paleozoic Atlantic-type margin of North America. This margin formed by the opening of an ocean in latest Precambrian time. The stratigraphy of the …

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Theoretical And Computer Assisted Studies In Tectonics, Structural Geology And Isotope Dating, Richard Leigh Thiessen Jan 1980

Theoretical And Computer Assisted Studies In Tectonics, Structural Geology And Isotope Dating, Richard Leigh Thiessen

Geology Theses and Dissertations

Several problems in the fields of tectonics, structural geology and isotopic dating were examined and simplified using computer programs. These problems include the theory of refolding, refold applications to three mining areas, hotspots and their relationship to mantle convection systems and ionium dating of volcanic rocks. In the first study, it was shown that current refold classification schemes are inadequate and so modifications were suggested. Various other aspects of multiple generations of interfering folds were also examined. The ideas of refold theory were then applied to three mining areas, the Chisel Lake Ore Body of Manitoba, the Galena-Roubaix District of …

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The Geology Of The Northern Part Of North Arm Massif, Bay Of Islands Ophiolite Complex, Newfoundland: With Application To Upper Oceanic Crust Lithology, Structure, And Genesis, Eric J. Rosencrantz Jan 1980

The Geology Of The Northern Part Of North Arm Massif, Bay Of Islands Ophiolite Complex, Newfoundland: With Application To Upper Oceanic Crust Lithology, Structure, And Genesis, Eric J. Rosencrantz

Geology Theses and Dissertations

Detailed mapping (1:15,800) of the northern half of North Arm Massif shows the area to be underlain with a complete, although thin, ophiolite assemblage consisting, from top to base, of basalts, sheeted diabase dikes, isotropic and layered gabbroic rocks, layered ultramafic rocks and harzburgite tectonite. The assemblage represents a preserved piece of Cambrian oceanic crust analogous to present-day oceanic crust. Sheeted dikes and isotropic gabbros comprise the majority of the rocks exposed, with this sequence at present flat-lying to gently warped into open, upright but nonsystematic folds. Basalts occupy a shallow discontinuous N-S trending trough within the west-central part of …

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The Geology Of The Southern Part Of The North Arm Mountain Massif, Bay Of Islands Ophiolite Complex, Western Newfoundland With Application To Ophiolite Obduction And The Genesis Of The Plutonic Portions Of Oceanic Crust And Upper Mantle, John F. Casey Jan 1980

The Geology Of The Southern Part Of The North Arm Mountain Massif, Bay Of Islands Ophiolite Complex, Western Newfoundland With Application To Ophiolite Obduction And The Genesis Of The Plutonic Portions Of Oceanic Crust And Upper Mantle, John F. Casey

Geology Theses and Dissertations

The Bay of Islands Ophiolite Complex forms a discontinuous belt of highly allochthonous mafic and ultramafic massifs in southwestern Newfoundland. The North Arm Mountain Massif contains the only significant exposures of sedimentary rocks overlying the ophiolite and also contains the most extensive exposures of plutonic rocks in the Bay of Islands Complex. Mapping has shown that sedimentary rocks, here named the Crabb Brook Group, rest with a pronounced erosional unconformity on ophiolitic rocks. Lithologic,paleontologic, facies, structural, and tectonic relationships indicate that this Group was deposited on the back of the ophiolite allochthon as it was being obducted onto the early …

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Saratoga: The Bubbles Of Reputation And Their Implications For An Embryonic Rift System In The Upper Hudson River Valley, James R. Young Jan 1980

Saratoga: The Bubbles Of Reputation And Their Implications For An Embryonic Rift System In The Upper Hudson River Valley, James R. Young

Geology Theses and Dissertations

Carbonated, alkaline, saline waters occur over a wide area in the upper Hudson River Valley approaching 1,000 square miles. Through the sampling (spring and fall) of 39 locations, half of which were hitherto unsampled, the waters are shown to be a complexly mixed system with at least five major components.
They are:
1) a gaseous phase consisting primarily of CO2;
2) a fluid (containing the dissolved CO2) possibly analogous to a metamorphic brine whose major chemistry is HCO3>Na>Cl;
3) formational waters of variably low salinities which may be the end products of progressive dilution of Paleozoic connate brines …

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Geometry And Kinematics Of Continental Deformation In Zones Of Collision: Examples From Central Europe And Eastern Mediterranean, Ali Mehmet Celâl Sengör Jan 1979

Geometry And Kinematics Of Continental Deformation In Zones Of Collision: Examples From Central Europe And Eastern Mediterranean, Ali Mehmet Celâl Sengör

Geology Theses and Dissertations

Consideration of world-wide epicenter distribution has shown that deformation in continental lithosphere is not narrowly confined to well-defined plate boundaries but is present in wide, diffuse plate boundary zones. Early studies on the seismicity of the peri-Mediterranean area resulted in the division of the lithosphere in that region into a number of small plates, or microplates. Later studies in central Asia, which integrated seismicity with Quaternary geology, indicated, however, that a continuum approach may be more realistic to describe continental tectonics. This study concentrates on geometry and timing of continental deformation that resulted from continental collision in Central Europe and …

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Geology Of The Lucea Inlier, Western Jamaica, Jack Grippi Jan 1978

Geology Of The Lucea Inlier, Western Jamaica, Jack Grippi

Geology Theses and Dissertations

The Lucea Inlier exposes a Santonian to Campanian 4 km + thick sequence of shale-siltstone, resedimented volcaniclastics, lenses of shallow-water limestone, micritic limestone, pebbly mudstone and sandy pebble to boulder conglomerate. Clastics were deposited by a variety of gravity flow mechanisms. Petrographically sandstones are lithic or feldspathic arenites and contain only very small amounts of detrital quartz. Structurally the inlier is characterized by simple, open, east-west trending folds. A spaced, vertical axial-planar cleavage is developed in shales and fine siltstones. Two major east-west trending left-lateral fault zones, the Fat Hog Quarter and Maryland faults, cut the inlier into three blocks, …

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Geology Of The Northern Lewis Hills, Western Newfoundland, Jeffrey Alan Karson Jan 1977

Geology Of The Northern Lewis Hills, Western Newfoundland, Jeffrey Alan Karson

Geology Theses and Dissertations

The Lewis Hills is the southernmost of the four Bay of Islands Ophiolite Complex massifs. These massifs are considered to be the dissected remnants of a once nearly continuous thrust slice of oceanic crust and upper mantle of Early Ordovician age. The Lewis Hills Massif may be divided into three north south trending zones. The eastern zone (Bay of Islands Complex) is composed of variably deformed and recrystallized gabbro, troctolite, wehrlite and dunite cumulates and harzburgite tectonites. The western zone (Little Port Assemblage) consists of greenschist facies metagabbros, diabase dikes and minor quartz-diorite bodies. The central zone (Mount Barren Assemblage) …

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Petrology Of The Oceanographer Fracture Zone (35ºn35ºw), Tsugio Shibata Jan 1976

Petrology Of The Oceanographer Fracture Zone (35ºn35ºw), Tsugio Shibata

Geology Theses and Dissertations

During a geological and geophysical survey of the Oceanographer Fracture Zone (35°N, 35°W), seventeen dredge hauls containing a variety of rocks were obtained. Petrographic study shows that these rock samples can be classified into six main rock types: fresh basalt, weathered basalt, metabasalt, gabbro, metagabbro, and serpentinite. Most of the dredge hauls were positioned on the steep, southern wall of the fracture zone, and an inference from the dredging results suggests that basalt is the most abundant rock type which outcrops at the junction between the rift valley and the fracture zone; however, as we move away from the junction, …

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