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Articles 151 - 165 of 165

Full-Text Articles in Physical Sciences and Mathematics

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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