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1
Forest, Richard C. "Structures and metamorphism of Ptarmigan Creek area, Selwyn Range, B.C." Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63337.
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Krauss, Jason B. "High-pressure (HP), granulite-facies thrusting in a thick-skinned thrust system in the eastern Grenville Province, central Labrador /." Internet access available to MUN users only, 2002. http://collections.mun.ca/u?/theses,42716.
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Sturms, Jason M. "Surficial mapping and kinematic modeling of the St. Clair thrust fault, Monroe County, West Virginia." Morgantown, W. Va. : [West Virginia University Libraries], 2008. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=5597.
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Thesis (M.S.)--West Virginia University, 2008.Title from document title page. Document formatted into pages; contains vii, 84 p. : ill. (some col.), maps (some col.). Includes abstract. Includes bibliographical references (p. 75-78).
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Roberts, Gerald Patrick. "Deformation and diagenetic histories around foreland thrust faults." Thesis, Durham University, 1990. http://etheses.dur.ac.uk/6258/.
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This thesis is concerned with the relationship between deformation and fluid flow along thrust zones. The study was carried out in the Vercors, French Sub-Alpine Chains foreland thrust belt. Study of the thermal alteration of organic matter within the area suggests that prior to west-north-west directed thrusting within the Vercors basin in post middle Miocene times, the rocks now exposed at the surface had not been buried beneath a large thickness of foredeep sediments and remained within the diagenetic realm. Deeper buried levels within the stratigraphy passed into the hydrocarbon generation window prior to thrusting within the Vercors basin. The rocks presently exposed at the surface also remained in the diagenetic realm during and after the thrusting which suggests that thrust sheet loading did not significantly contribute to thermal alteration of organic matter. The structures of the thrust belt may have been possible structural traps for any hydrocarbons which underwent re-migration during the thrusting. The structures have been exhumed by erosion during isostatic uplift. The Rencurel Thrust and overlying Rencurel Thrust Sheet were selected for special study as they are of regional structural importance. The thrust emplaces Urgonian limestones onto Miocene molasse sediments at present erosion levels. The thrust sheet is internally deformed by thrusts and folds. Structural data indicate that the deformation within the thrust sheet and within the Rencurel Thrust Zone occurred during one kinematically linked phase of thrusting. The Rencurel Thrust Zone itself is around 100 metres thick. The higher part of the thrust zone is composed of an array of minor faults developed within the Urgonian. These fault zones are generally less than 10cm wide and are coated in fault gouge. This array of faults is underlain by a gouge zone along the thrust contact between the Urgonian and the Miocene which is several metres thick. The gouge zones were all formed during the action of diffusive mass transfer (DMT) and cataclasis as deformation mechanisms. The wall-rocks to the gouge zones are relatively undeformed by the action of cataclasis. Cataclasis is dilatant and produces fracture porosity which increases the permeability of the fault zones whilst DMT reduces the porosity and permeability of the fault zones due to cement precipitation and pressure dissolution. Cross- cutting relationships between the microstructures indicating the action of cataclasis and DMT, suggest that the porosity and permeability of the fault rocks changed in a complex manner during the incremental deformation. This has important implications for assessing syn-kinematic fluid migration through fault zones. The fault rocks exposed at the surface today are relatively impermeable compared to undeformed wall-rocks away from the fault zone which have permeabilities comparable to those found within hydrocarbon reservoirs. The thrust zone may have been a seal in the sub-surface after the cessation of thrusting but prior to uplift and erosion. Early distributed deformation produced an array of minor faults within the Urgonian. Cataclasis had ceased along these faults before later deformation became localised along the gouge zone which exists along the thrust contact between the Urgonian and the Miocene rocks. Early deformation was accompanied by the migration through fracture porosity of pore waters which were saturated with respect to calcite and had interacted with organic matter which was being thermally altered. This fluid flow system was not connected to fluid flow higher in the stratigraphy which resulted in the precipitation of ferroan calcite within fracture porosity in the Senonian limestones. Late deformation within the thrust zone was accompanied by the migration of hydrocarbons and pore waters saturated with respect to calcite and pyrite. All the pore waters involved in migration through the active thrust zone seem to have migrated up-dip. They migrated from levels in the stratigraphy where organic metamorphism and the maturation of hydrocarbons were occurring to levels in the deformed section which have always remained within the diagenetic realm. Ferroan calcite, pyrite and traces of hydrocarbons have not been found outside the gouge zone along the thrust contact between the Urgonian and Miocene. The fracturing which occurred to open this migration pathway did not re- fracture the inactive minor faults which were impermeable at this time. Fluid migration at this time was confined to beneath the zone of impermeable minor faults in the Urgonian and did not contribute to the diagenesis of the rocks above the thrust zone. Hydrocarbons could not have entered the hanging-wall anticline above the thrust zone from this migration pathway. The fracturing at this time did not produce connected fracture networks pervasively throughout the thrust zone which suggests that the deformation may not have released large amounts of energy in the form of seismic waves.
5
McClay, K. R. "Structural geology and tectonics /." Title page, contents and abstract only, 2000. http://web4.library.adelaide.edu.au/theses/09SD/09sdm126.pdf.
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Patthoff, D. Alex. "Structure and crustal balance of the Herald Arch and Hope Basin in the Chukchi Sea, Alaska." Morgantown, W. Va. : [West Virginia University Libraries], 2008. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=5888.
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Thesis (M.S.)--West Virginia University, 2008.Title from document title page. Document formatted into pages; contains vii, 106 p. : ill. (some col.), col. maps. Includes abstract. Includes bibliographical references (p. 100-103).
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Wigginton, Sarah S. "The Influence of Mechanical Stratigraphy on Thrust-Ramp Nucleation and Propagation of Thrust Faults." DigitalCommons@USU, 2018. https://digitalcommons.usu.edu/etd/7344.
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Our current understanding of thrust fault kinematics predicts that thrust faults nucleate on low angle, weak surfaces before they propagate upward and forms a higher angle ramp. While this classic kinematic and geometric model serves well in some settings, it does not fully consider the observations of footwall deformation beneath some thrust faults. We examine an alternative end-member model of thrust fault formation called “ramp-first” fault formation. This model hypothesizes that in mechanically layered rocks, thrust ramps nucleate in the structurally strong units, and that faults can propagate both upward and downward into weaker units forming folds at both fault tips. To explore this model, we integrate traditional structural geology field methods, two dimensional cross section reconstructions, and finite element modeling. Field data and retro-deformable cross sections suggest that thrust faults at the Ketobe Knob, in Utah nucleated in strong layers and propagated upward and downward creating folds in weak layers. These findings support the hypothesis that thrust faults and associated folds at the Ketobe Knob developed in accordance with the ramp-first kinematic model.We can apply this understanding of the mechanics behind thrust fault nucleation and propagation in mechanically layered stratigraphy to a wide range of geological disciplines like structural geology and tectonics, seismology, and petroleum geology. By incorporating our knowledge of lithology into fault models, geologists are more likely to correctly interpret structures with limited data sets.
8
Lock, Jane. "Interpreting how low-temperature thermochronometric data in fold-and-thrust belts : an example from the Western Foothills, Taiwan /." Thesis, Connect to this title online; UW restricted, 2007. http://hdl.handle.net/1773/6698.
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Leonard, Richard. "Variable structural style, stratigraphy, total strain and metamorphism adjacent to the Purcell thrust, near Blackman Creek, B.C." Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63282.
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Tully, Justin Edward. "Structural interpretation of the Elk Range thrust system, Western Colorado, USA." Thesis, Montana State University, 2009. http://etd.lib.montana.edu/etd/2009/tully/TullyJ0509.pdf.
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The Elk Mountains of western Colorado expose Pennsylvanian-Permian strata that were deposited along the western margin of the Ancestral Central Colorado Trough. These rocks were displaced southwestward in Late Cretaceous-Early Paleogene time along the northeast-dipping Elk Range thrust system. The thrust system trends southeast from Redstone, CO to the Fossil Ridge wilderness and includes the en echelon Elk Range and Brush Creek thrust faults. This thrust system represents the deeply eroded up-plunge core of a major Laramide basement-cored fold in western Colorado, the Grand Hogback monocline. The emergence of the thrust system from the fold's core is well documented at all scales of geologic mapping over the northwest end of the system. This surface relationship is undemonstrated in previous structural interpretations, which invoke a mechanism of gravity sliding within the sedimentary package, induced by vertical basement uplift. To the southeast a critical portion of the system had remained unmapped in any contiguous detail. This critical area exposes the basement roots of the thrust system, as it merges with the reverse-faulted southwestern margin of the Laramide Sawatch Range basement arch. This thesis presents a new structural architecture for the Elk Range thrust system through: 1) new 1:24,000 scale mapping of the emergent root zone, 2) regional balanced cross-section analysis 3) demonstration of a genetic relationship with the Grand Hogback monocline, and 4) consideration of contemporary basement-involved foreland contraction models. The fault system is a basement-rooted, right-stepping, en echelon thrust front. The Elk Range thrust sheet is truncated by high-angle reverse faults to the east and the Brush Creek thrust becomes steeper and merges with reverse faults to the southeast. The western Sawatch front shows evidence for late-stage, north-south directed contraction. Thus, the Elk Range thrust system represents an inverted segment of the western Ancestral Colorado Trough. Structurally, it represents a transitional deformation regime between fold-shortening (Grand Hogback monocline) and high-angle reverse-faulting (Sawatch arch). Together, this tectonic continuum marks Colorado's westernmost Laramide deformation front against the Colorado Plateau. Younger deformation is observed and discussed with respect to the region's dynamic transition from Laramide contraction to Rio Grande rifting.
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Ward, Emily M. Geraghty. "Development of the Rocky Mountain foreland basin combined structural, mineralogical, and geochemical analysis of basin evolution, Rocky Mountain thrust front, northwest Montana /." CONNECT TO THIS TITLE ONLINE, 2007. http://etd.lib.umt.edu/theses/available/etd-09262007-094800/.
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Bennett, David George. "The role of fluids during retrograde metamorphism, associated with thrust zones in the Caledonides of North Norway." Thesis, University of Southampton, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293174.
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Miller, Martin Gregg. "Structural and kinematic evolution of the Badwater Turtleback, Death Valley, California /." Thesis, Connect to this title online; UW restricted, 1992. http://hdl.handle.net/1773/6716.
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Hansen, Ashley D. "Reservoir characterization and outcrop analogs to the Navajo sandstone in the Central Utah thrust belt exploration play /." Diss., CLICK HERE for online access, 2007. http://contentdm.lib.byu.edu/ETD/image/etd1919.pdf.
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Thigpen, James Ryan. "Vorticity of Flow, Deformation Temperatures, and Strain Symmetry of the Moine Thrust Zone, NW Scotland: Constraining the Kinematic and Thermal Evolution of a Collisional Orogenic System." Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/28228.
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Examination of deformation temperature, flow vorticity, and strain symmetry in the Loch Eriboll, Loch More, and Assynt regions of the Moine thrust zone (MTZ) in northwest Scotland allows quantitative kinematic and thermal characterization of a crustal-scale shear zone at the base of the Scandian (435-425 Ma) orogenic wedge. Quartz crystal fabrics, kinematic vorticity (Wm), and strain estimates from the ductile thrust sheets in this region are used to determine how pure and simple shear components of deformation are partitioned, and indicate that these processes may be thermally, structurally, and lithologically dependent. Vorticity analysis of samples collected along strike in the MTZ and overlying Moine nappe indicate that Scandian thrusting and deformation involved a considerable pure shear component. Integrated strain and vorticity estimates indicate that significant sub-vertical foliation normal shortening has occurred as nappe stacking progressed. Along strike Wm variation could not be directly correlated with changes in footwall structural architecture, lithology, deformation temperatures, or structural depth and are thus interpreted to reflect local variability driven by a complex interplay of these and possibly other factors. Quartz c- and a-axis fabrics indicate that deformation in the footwall of the Moine thrust involved plane strain to general flattening strain with only a minor rotational (non-coaxial) component. In contrast, deformation in the Moine nappe was strongly non-coaxial, as indicated by asymmetric single girdle c-axis fabrics. Quartz c-axis opening angles and microstructures suggest that deformation temperatures increase from north to south and from structurally lower to structurally higher levels in the footwall to the Moine thrust. Vertical ductile thinning must be accommodated by either volume loss or extrusion of material towards the synorogenic topographic surface. Extrusion towards the synorogenic topographic surface implies a causal link between upper and lower crustal processes, with significant implications for the kinematic, geometric, and kinetic (deformation rates) evolution of the Scandian orogenic wedge. New thermobarometric and deformation temperature estimates are combined with structural and kinematic investigations to characterize the thermal structure of the Moine, Ben Hope, and related nappes. At the leading edge of the Moine thrust, subhedral garnets with prograde compositional growth zoning yield peak temperatures (grt-bio) of 440-492 °C at 4.5-6.0 kbars from Creagan Meall Horn to northern Assynt. Three samples collected at similar structural positions along the leading edge of the Moine nappe yield deformation temperatures of 420-460 °C, as determined from quartz c-axis opening angles. At the structurally highest position in the Moine nappe, garnet prograde compositional zoning profiles are preserved and samples yields P-T estimates of 565-571 °C (grt-bio) and 4.5-5.1 kbar (GRAIL barometer, minimum pressure due to absence of Al2SiO5 phase). Quartz c-axis fabrics of samples collected at similar structural positions yield deformation temperature estimates of 490-565 °C. In the structurally higher Ben Hope nappe, two phases of prograde compositional growth zoning are preserved in garnet bearing amphibolite near Portvasgo. The later outer garnet rim records P-T conditions of 655-672 °C at 3.9-5.1 kbars. The inverted metamorphic sequence from the Moine to the Naver thrust is mostly intact and is interpreted to be Scandian (435-420 Ma) in age. It is likely that the formation of this inverted sequence is due to a combination of progressive accretion of successively lower grade thrust sheets onto the base of the Scandian wedge and heating of the Moine and Ben Hope nappes from above by the relatively higher temperature migmatites of the Naver thrust. Vertical ductile thinning, in conjunction with erosion and normal faulting, likely led to rapid exhumation of the Scandian nappe pile and in turn preserved the inverted metamorphic sequence.Ph. D.
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Hoehn, Jack R. "Low-Temperature Deformation of Mixed Siliciclastic & Carbonate Fault Rocks of the Copper Creek, Hunter Valley, and McConnell Thrusts." Oberlin College Honors Theses / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=oberlin1400002733.
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Goddard, James V. "Internal Deformation, Evolution, and Fluid Flow in Basement-Involved Thrust Faults, Northwestern Wyoming." DigitalCommons@USU, 1993. https://digitalcommons.usu.edu/etd/6697.
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An integrated field , microstructure, fracture statistic , geochemistry , and laboratory permeability study of the East Fork and White Rock fault zones , of similar age and tectonic regime but different structural level and hydrogeologic history , provides detailed information about the internal deformation and fluid flow processes in fault zones . The primary conclusions of this research are: 1) Fault zones can be separated into subzones of protolith, damaged zone , and gouge /cataclasite , based on physical morphology and permeability structure . At deep structural levels, gouge/cataclasite zones are more evolved (thicker with increased grain size reduction) due to strain localization , higher pressure and temperature, and fluid/rock interaction ; 2) Deformation mechanisms evolved from primarily brittle fracturing and faulting in the damaged zone to extreme, fluid-enhanced chemical breakdown and cataclasis which localized strain in the fault core. Deformation in the deep-level-fault core may be a combination of frictional and quasiplastic mechanisms, and is largely controlled by extremely fine-grained clays, zeolites , and other phyllosilicates that may have acted as a thermally pressurized, fluid-saturated lubricant; 3) Permeability in fault zones was temporally heterogeneous and anisotropic (permeability of damaged zone>protolith>gouge /cataclasite, permeability along fault> permeability across fault); 4) Volume loss was concentrated in the fault cores and was negligible at intermediate structural
levels and high at deep structural levels in the semi-brittle to brittle regime ; 5) Fluid flow and solute transport were concentrated upwards and subparallel to the fault in the damaged zone ; 6) Faults at both the local and regional scale acted as fluid flow conduit/barrier systems depending upon the evolutionary stage and interval in the seismic cycle ; 7) Fluid/rock volume ratios , fluid flux , and fluid/rock volume ratios over time ranged from ⋍ 103 to 104, 10-6 ms-1 to 10-9 ms-1, and 0.05 L/m3 rock•yr to 0.50 L/m3 rock•yr, respectively, suggesting that enormous quantities of fluids passed through the fault zones; 8) Box counting fractal analyses of fault zone fractures showed that fracture spatial and density distribution is scale-invariant at the separate scales of outcrop , hand-sample , and thin section, but self-affine from outcrop to thin-section scale; 9) Linear fractal analysis depicts clustering and density distribution as a function of orientation, and may be a quick, robust method of estimating two-dimensional fracture permeability; and 10) Fractal analysis of fractures is not a comprehensive statistical method, but can be used as another supplemental statistical parameter.
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Gong, Zhijun, and 龚志军. "Application of optical dating to late quaternary uplift and thrust activity in the northern piedmont of Tian Shan, China." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hdl.handle.net/10722/193394.
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Tian Shan is one of the most important orogenic belts in central Asia. It has been reactivated as a result of the Cenozoic India-Eurasia collision. Dating of the late Cenozoic tectonic deformation of Tian Shan and its piedmonts is important for understanding the mountain building as well as evaluating seismic hazards in the region. This study is focused on the applications of optical dating to the late Quaternary uplift and thrust activity along Manas River, in the northern piedmont of the Tian Shan, China.
The sediments on river terraces were dated with optical dating. The elevations were measured with the kinematic global position system (GPS). The results suggest that two phases can be identified according to the significantly different river incision rates. One phase was from ~20 ka to ~4.8 ka, with a much slower incision rate of ~ 2.2 ± 0.6 mm/yr. The other phase was from ~4.8 ka to present, with a faster incision rate of ~ 13.5 ± 0.6 mm/yr. The accelerated incision rate of Manas River was mainly attributed to the tectonic forces, suggesting that the tectonic uplift was significantly intensified since ~4.8 ka in the northern piedmont of Tian Shan.
The study region has suffered from multiple thrust activities during the late Quaternary, which led to the intensive deformations of the river terraces. By studying the deformed terraces, I evaluated the timing of the past thrust activities as well as the vertical slip rate of the thrust faults. The results demonstrated that the thrust activity intensified during the late Holocene, as manifested by the more frequent thrust activities and higher vertical slip rates.
Both quartz and potassium feldspar can be as dosimeters for optical dating of sediments. However, quartz OSL is sometimes seriously impeded with problems such as very dim signals and insufficient bleaching problems. K-feldspar has attractive advantages over quartz, despite of problem of anomalous fading. K-feldspar was explored in this study, by investigating the relationship between the infrared stimulated luminescence (IRSL) and blue light stimulated luminescence (BLSL) signals. For IRSL and BLSL at 60 °C, it was suggested that most of the IRSL could be bleached by blue light (BL), while the BLSL could only be partially bleached by infrared (IR) stimulation. Besides, the fast and medium components of BLSL were mainly associated with the IRSL. If IR stimulation temperature was raised from 60 to 200 °C, at least two portions of the IRSL signals at 200 °C were observed. One portion could be bleached by BL at 60 °C and the other portion was hardly bleached by BL at 60 °C. Dating of K-feldspar from the various signals provided cross-checking for the reliability of quartz OSL for dating sedimentary samples.published_or_final_version
Earth Sciences
Doctoral
Doctor of Philosophy
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May, Bryce Derrick. "Comparative geomorphology of two active tectonic structures, near Oxford, North Canterbury." Thesis, University of Canterbury. Geological Sciences, 2004. http://hdl.handle.net/10092/1521.
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The North Canterbury tectonic setting involves the southward propagating margin of easterly strike-slip activity intersecting earlier thrust activity propagating east from the Alpine Fault. The resulting tectonics contain a variety of structures caused by the way these patterns overlap, creating complexities on the regional and individual feature scale. An unpublished map by Jongens et al. (1999) shows the Ashley-Loburn Fault System crossing the plains from the east connected with the Springfield Thrust Fault in the western margins, possibly the southern limit of the east-west trending strikeslip activity. Of note are two hill structures inferred to be affected by this fault system. View Hill to the west, is on the south side of this fault junction, and Starvation Hill further east, was shown lying on the north side of a left stepover restraining bend. During thrust uplift and simple tilting of the View Hill structure, at least two uplift events post date last Pleistocene aggradation accounting for variations in scarp morphology. Broad constraints on fault dip and the age of the displacement surface suggest that slip-rates are in the order of 0.5 mm/year. East from View Hill, the strike-slip fault was originally thought to curve northeast, around the southeast of Starvation Hill. But there is neither evidence of a scarp, nor other clear evidence of surface faulting at Starvation Hill, which poses the question of the extent to which folding may reflect both fault geometry and fault activity. Starvation Hill is a triangular shape, with a series of distinctive smooth, semi-planar surfaces, lapping across both sides of the hill at a range of elevations and gradients. These surfaces are thought to be remnants of old river channels, and are indicative of tilting and upwarping of the hill structure. 3D computer modelling of these surfaces, combined with studies of the cover sequence on the hill, resulted in inferences being drawn as to the location of hinge lines of a dual-hinged anticline and an overview of the tectonic history of the hill. This illustrates the potential to apply topographical and geomorphic studies to the evolution of geometrically complex structures Starvation Hill is interpreted to be the result of two fault-generated folds, one fault trending north, the other, more recent fault, trending east. These two faults are thought to be sequentially developed segments of the original fault zone inferred by Jongens et al. (1999) but with reinterpreted location and mechanism detail. The presence of two faults has resulted in overprinted differential uplift of the structure, which has been significantly degraded, especially in the southwest corner of the hill. The majority of the formation of the northerly trending structure of Starvation Hill is inferred to be pre-Otiran, with uplift of the later east trending structure continuing into the late Pleistocene and Holocene.
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Kendrick, Richard D. "Magnitude of Displacement and Styles of Deformation on the Paris and Laketown Thrust Faults, Northern Utah." DigitalCommons@USU, 1994. https://digitalcommons.usu.edu/etd/6783.
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Surface geology is combined with abundant industry seismic-reflection and drill-hole data in the central Bear River Range and Bear Lake Plateau to depict the forms and interactions of the Paris-Woodruff-Willard, Laketown-Meade-Home Canyon, and Crawford thrust faults. Displacement on the Paris thrust diminished to the south, and died out in splays where displacement was transferred to the Willard thrust. West of Woodruff, Utah, splays of the Laketown thrust deformed a complex footwall imbricate of the Willard thrust. To the east, a major northeast-striking Crawford thrust splay exhibits a change in slip vectors from east to southeast. Reorientation of these slip vectors is recorded by an imbricate stack of thrusts in the Willard thrust footwall to the west. The sharp bend in the surface trace of the Crawford normal fault southeast of Randolph, Utah, reflects the separation of the south-southeast-trending surface traces of the Crawford thrust and this northeast-trending splay.
Cross sections indicate that the Sheep Creek thrust, a major splay off the basal decollement at the base of the Crawford thrust sheet, accommodated displacement during the transition from thrusting on the western thrust system (Paris-Woodruff-Willard, and Laketown-Meade-Home Canyon) to the structurally lower eastern thrust system (Crawford, Absaroka, and younger thrusts). The Sheep Creek thrust trends northeast and folded the Laketown thrust in the central Bear River Range. Shortening in the northeast part of the study area was accommodated by the Home Canyon thrust along a detachment in the Jurassic Twin Creek Limestone. Several splays from this thrust extensively folded the footwall of the Meade thrust and rocks of the Bear Lake Plateau, and thereby formed a series of hanging-wall anticlines that have been extensively drilled for hydrocarbons.
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Watkins, Hannah E. "Characterising and predicting fracture patterns in a sandstone fold-and-thrust belt." Thesis, University of Aberdeen, 2015. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=227123.
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Fracture distribution in a fold and thrust belt is commonly thought to vary depending on structural position, strain, lithology and mechanical stratigraphy. The distribution, geometry, orientation, intensity, connectivity and fill of fractures in a reservoir are all important influences on fractured reservoir quality. The presence of fractures is particularly beneficial in reservoirs that contain little matrix porosity or permeability, for example tight sandstones. In these examples fractures provide essential secondary porosity and permeability that enhance reservoir production. To predict how reservoir quality may fluctuate spatially, it is important to understand how fracture attributes may vary, and what controls them. This research aims to investigate the influence of structural position on fracture attribute variations. Detailed fracture data collection is undertaken on folded sandstone outcrops. 2D forward modelling and 3D model restorations are used to predict strain distribution in the fold-and-thrust belt. Relationships between fracture attributes and predicted strain are determined. Discrete Fracture Network (DFN) modelling is then undertaken to predict fracture attribute variations. DFN modelling results are compared with field fracture data to determine how well fractured reservoir quality can be predicted. Field data suggests strain is a major controlling factor on fracture formation. Fractures become more organised and predictable as strain increases. For example in high strain forelimb regions, fracture intensity and connectivity are high, and fracture orientations are consistent. In lower strain regions, fracture attributes are much more variable and unpredictable. Fracture variations often do not correspond to strain fluctuations, and correlations can be seen between fracture intensity and lithology. Reservoir quality is likely to be much more variable in low strain regions than high strain regions. DFN modelling is also challenging because fracture attribute variations in low strain regions do not correspond to strain, and therefore cannot be predicted.
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Asim, Muhammad. "HYDROCHEMICAL CHARACTERIZATION AND NUMERICAL MODELING OF GROUNDWATER FLOW IN A PART OF THE HIMALAYAN FORELAND BASIN." Kent State University / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=kent1132262925.
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Camanni, Giovanni. "The structure of the south‐central Taiwan thrust belt." Doctoral thesis, Universitat de Barcelona, 2014. http://hdl.handle.net/10803/284852.
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The Taiwan thrust belt is generally thought to develop above a shallow, through-going basal detachment confined to within the sedimentary cover of the Eurasian continental margin. A number of data sets, however, such as surface geology, earthquake hypocentre, and seismic tomography data among others, suggest that crustal levels below the interpreted location of the detachment are also currently being involved in the deformation. In this thesis, new surface geology data were combined with several available geophysical data sets to find a model for the structure of the south-central part of the thrust belt that takes into account deformation taking place at depth. Results of this thesis indicate that beneath the internal Hsuehshan and Central ranges the structural development of the south-central Taiwan thrust belt is controlled by steeply dipping and deep-penetrating faults that are currently inverting pre-existing basement faults inherited from the Eurasian continental margin. Basement rocks are uplifted along these faults to form a basement culmination in the interior of the thrust belt. Beneath the more external Coastal Plain and Western Foothills, however, most of the deformation appears to be taking place near the basement-cover interface, which is acting as an extensive level of detachment and still preserves the extensional geometry inherited from the Eurasian margin.La estructura de la cordillera de Taiwán se considera constituida por un sistema de cabalgamientos y pliegues desarrollados sobre un despegue basal con suave inclinación, situado en la cobertera sedimentara de la margen continental Euroasiática. Una cantidad creciente de datos de sismicidad y de geología de superficie, sin embargo, indican la existencia de actividad generalizada de fracturas en la corteza media e inferior y sugieren que los niveles de la corteza por debajo de la ubicación del despegue basal también están actualmente involucrados en la deformación. En esta tesis, nuevos datos de geología de superficie se combinaron con varios conjuntos de datos geofísicos disponibles para encontrar un modelo para la estructura de la parte sur-central de la cordillera de Taiwán. Los resultados de este trabajo indican que debajo de la parte interna de la área de estudio el desarrollo estructural de la cordillera de Taiwán esta controlado por fallas mayores con alta inclinación, que penetran hasta partes profundas de la corteza, y que están reactivando fallas preexistentes heredadas de la margen continental Euroasiática. Rocas de basamento están elevadas a lo largo de estas fallas y forman una culminación por debajo de las partes internas de la cordillera. Por debajo de el Coastal Plain y de las Western Foothills en la parte externa de la área de estudio, sin embargo, la mayor parte de la deformación parece estar teniendo lugar cerca de la interfaz basamento-cobertera, que está actuando como un amplio nivel de despegue basal y aún conserva la geometría extensional heredada de la margen continental Euroasiática.
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Ho, Hoi-to Lucas, and 何海濤. "The Nielaxiongbo metamorphic core complex and its associated granites,in Southern Tibet." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2002. http://hub.hku.hk/bib/B30252052.
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Guerrero, Francisco Jesus. "Death Valley reconstruction new piercingpoints in the Panamint Mountains and Resting Springs Range /." To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2008. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.
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Beavogui, Massa. "Structural controls of gold mineralisation in Seguelen pit of Siguiri gold mine, Guinea." Thesis, Rhodes University, 2015. http://hdl.handle.net/10962/d1019879.
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The present study provides the results of detailed mapping and analysis of structures encountered in Seguelen pit of Siguiri gold mine, Guinea, where the Siguiri mine is geo-tectonically located in the Baoulé-Mossi domain of Man Shield in West African craton. The gold deposit is hosted in low-grade metamorphic sediments of turbidites sequences which form part of the Lower Proterozoic of Birimian Super group. Three rock formations of Balato, Fatoya and Kintinian underlay the overall pits. The Siguiri gold mine is characterized by the deep weathering profile, developed over the rocks reaching 200 m below the surface in some areas and often capped by the lateritic gravel or duricrust. The rock formations at Seguelen area are characterised by strong bedding monotonously dipping towards SW and trending NW-SE. The lithology of the host rocks has strong control on the disseminated mineralisation throughout the deposit. Two domains of rock formations are clearly distinguished at Seguelen: Fatoya Formation(Ffm) domain ; and Kintinian Formation (Kfm) domain. The two domains are separated by a contact zone of 1.7 m wide parallel to bedding and characterised by the presence of quartz fragments as well as thinly sheeted shale and black shale. This contact zone is identified as disconformity. The major tectonic deformation which has affected the region is known as D2 corresponding to the Eburnean orogeny. The major D2 related structures is the regional thrust striking N-S over an area of 12 km long and 3 km wide and within which corridors all Siguiri gold Mine open pits are located. In the N-S trending structures, there is east-northeast shortening and north-northwest extension. There is pervasive hydrothermal alteration (carbonatization and sideritization) and supergene alteration in the all pits. The hydrothermal alteration attests the intensity of hydrothermal fluid-flow over the host rocks. The hydrothermal fluids flowed along the fractures and within the wall rocks through bedding plans to form numerous auriferous quartz veins bearing disseminated sulphides through chemical reaction between fluids and wall rocks, which are remarkable at Seguelen pit. Three quartz vein sets are distinguished at Seguelen: NNE-SSW quartz vein set NE-SW quartz vein set NW-SE quartz vein set The NE-SW and NNE-SSW quartz veins are often lenticular and associated with the bulk mineralisation.
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Vasconcelos, Bruno Rodrigo. ""Deformação polifásica e metamorfismo do Grupo Cuiabá na região de Poconé (MT), cinturão de dobras e cavalgamentos Paraguai"." Universidade Federal de Mato Grosso, 2014. http://ri.ufmt.br/handle/1/590.
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Vários modelos deformacionais foram propostos para o Cinturão Paraguai diferindo principalmente quanto ao número de fases de deformação, sentido da vergência e estilo tectônico. Feições estruturais apresentadas neste trabalho indicam tectônica dominada por escamas de baixo ângulo de mergulho na fase inicial, seguida por duas fases deformacionais progressivas. A primeira fase de deformação (F1) é caracterizada por clivagem ardosiana (S1), com recristalização de minerais da fácies xisto verde, plano axial de dobras isoclinais recumbentes (D1) de direção NE associadas a zonas de falhamento reverso subhorizontais com movimentação de topo para SE. A segunda fase deformacional (F2) mostra vergência para NW, caracterizada por clivagem de crenulação (S2) plano axial de dobras abertas (D2) do acamamento e foliação S1, localmente associada a falhas reversas. A terceira fase de deformação é caracterizada por falhas e fraturas sub-verticais com direção NW mostrando movimentação sinistral, comumente preenchidas por veios de quartzo. O acervo de estruturas tectônicas e paragênese metamórfica descrita indicam que a deformação mais intensa, em nível crustal mais profundo, alcançou a fácies xisto verde durante F1. Acomodando expressivo encurtamento crustal por meio de dobras recumbente e zonas de cisalhamento de baixo ângulo com movimentação de topo para SE, em regime tectônico do tipo pelicular delgado. A fase F2 teve deformação menos intensa e se comportou de maneira rúptil-dúctil, acomodando discreto encurtamento por meio de dobras normais abertas e falhas inversas subverticais desenvolvidas em nível crustal mais raso, com vergência em direção ao Cráton Amazônico. A terceira fase deformacional (F3) foi menos intensa e acomodou encurtamento na forma de fraturas e falhas sinistrais subverticais, comumente preenchidas por veios de quartzo.
Several deformation models have been proposed for the Paraguay Belt, differing mainly in the number of deformation phases, sense of vergence and tectonic style. Structural features presented in this work indicate tectonic dominated by an initial phase of low dipping thrust sheets, followed by two progressive deformation phases. The first deformation phase (F1) is characterized by a slaty cleavage (S1), axial plane of isoclinal recumbent folds (D1) in the NE direction, with recrystallization of minerals from the greenschist facies, related to horizontal shear zones with top-to-the-SE sense of movement. The second stage shows a NW-vergence, characterized by crenulation cleavage, S0 and S1 axial planes of open folds, locally associated with reverse faults. The third deformation phase is characterized by subvertical faults and fractures in the NW direction showing sinistral movement, commonly filled by quartz veins. The collection of tectonic structures and metamorphic paragenesis described indicate that the most intense deformation, at deeper crustal level, reached the greenschist facies during F1. Accommodating significant crustal shortening through isoclinal recumbent folds and low-angle shear zones showing top-to-the SE sense of movement during a thin-skinned tectonic regime. The phase F2 showed more subtle deformation, with more competent rock types developing brittle behavior and less competent rock types developing ductile behavior, by accommodating slight shortening through normal open folds and subvertical reverse faults nucleated in shallower crustal level with vergence towards the Amazonian Craton. The third phase was less intense and shortening is accommodated in the form of fractures and subvertical sinistral faults, commonly filled by quartz veins.
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Dauch, Christian. "Decrochements et chevauchements dans une zone de plate-forme : l'exemple du massif de la gresigne (aquitaine nord-orientale)." Toulouse 3, 1988. http://www.theses.fr/1988TOU30081.
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Presentation d'un modele de zone de decrochements et de chevauchements dans l'avant-pays nord de la chaine des pyrenees, massif de gresigne. Les macrostructures definissent le cadre tectonique general, les microstructures indiquent l'existence de deux directions principales de racourcissement qui se superposent. La structure du massif de la gresigne est une structure ecaillee de type duplex. Le mecanisme de deformation resulte de l'effet de coin forme par les decrochements limites convergents
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Vuichard, Jean-Paul. "La marge austro-alpine durant la collision alpine : evolution tectonometamorphique de la zone sesia-lanzo." Rennes 1, 1988. http://www.theses.fr/1988REN10129.
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L'objectif de l'etude est de discuter la cinematique des etapes precoces de la collision (evenement eoalpin) dans les alpes occidentales et de definir l'histoire de l'epaississement dans la partie interne de l'arc alpin. L'unite choisie est la zone sesia-lanzo qui represente la partie distale de la marge apulienne. Apres une description des unites, l'evolution p-t-t des trois unites de la zone (gneiss minuti, seconde zone diorito-kinzigitique iidk, micaschistes eclogitiques) est etudiee. Deux deformations alpines majeures sont identifiees. On montre que la zone sesia-lanzo est le resultat de deux empilements. Enfin, un schema d'evolution tectonique est propose pour les alpes occidentales et la cinematique de collision est discutee
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BODIN, EUGENE JOELLE. "Le devonien inferieur et moyen des pyrenees ariegeoises et centrales : biostratigraphie, series heteropiques et mise en evidence de nappes hercyniennes precoces." Toulouse 3, 1987. http://www.theses.fr/1987TOU30211.
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L'etude biostratigraphique, a l'aide des conodontes, du devonien inferieur et moyen des pyrenees ariegeoises et centrales a permis de distinguer 3 domaines paleogeographiques allonges selon l'axe de la chaine pyreneenne. Ils se dfferencient egalement par leur lithologie. On met en evidence une tectonique tangentielle varisque qui amene les series du nord a chevaucher les series sud et ces dernieres a chevaucher le substratum. Ces nappes precoces a vergence du nord vers le sud, d'ampleur plurikilometrique, constituent un trait essentiel de l'orogenese varisque pyreneenne
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Ouazzani-Touhami, Mohamed. "Structures et recristallisations associees dans des zones de cisaillement : nappes de mascate (oman) et nappes de frederico s.l. (rif interne, maroc)." Université Louis Pasteur (Strasbourg) (1971-2008), 1986. http://www.theses.fr/1986STR13198.
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L'etude de la deformation et des recristallisations associees dans deux ensembles de nappes synmetamorphiques (mascate, oman; rif, maroc) a abouti a montrer que, dans les deux exemples, il apparait que les isogrades du metamorphisme sont perturbes par des chevauchements tardi- a post-metamorphiques, qui jouent un role important dans les dernieres phases de l'evolution thermique des piles tectoniques considerees. Les nappes de mascate (oman) representent un element tres interne, en fenetre, sous les nappes oceaniques chainees sur la plateforme arabe. En ce qui concerne les nappes de federico (rif, maroc), on montre que le plissement synmetamorphique est un pli isoclinal couche, et que l'empilement des unites semble s'etre fait du sud vers le nord, en sens contraire de celui du chevauchement tardif (miocene)
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Lemennicier, Yves. "Le complexe métamorphique du sud Karakorum dans le secteur du Chogo Lungma (Baltistan-Nord Pakistan) : étude structurale, métamorphique, géochimique et radiochronologique." Université Joseph Fourier (Grenoble), 1996. http://www.theses.fr/1996GRE10117.
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Les aspects tectonometamorphiques et plutoniques du complexe metamorphique du karakorum (kmc) on ete etudies dans le secteur du chogo lungma (n. Pakistan). Quatre ensembles d'orthogneiss, repris dans l'evolution tectonometamorphique, ont ete identifies, certains presentant des similitudes avec des granitoides deja connus plus au nord : l'ensemble bukpun est un equivalent des plutons de subduction cretaces de type hunza ou ghamu bar ; l'ensemble basha d'origine crustale probable presente quelques similitudes avec le granite oligo-miocene du baltoro ; l'ensemble bolocho a des caracteres intermediaires entre des complexes subalcalins et alcalins (d'ages cretaces a paleogenes). Les caracteristiques du quatrieme (aralter) sont originales dans le karakorum. L'histoire tectonometamorphique du kmc inclut : (i) des plis isoclinaux n100e a vergence sud associes a une schistosite s1 plan axial et formes dans un regime en aplatissement dominant. Ils correspondent au pic de metamorphisme (620 - 730c pour 7,5 - 11 kbar) ; (ii) des domes allonges n100e a n140e qui reprennent et deforment s1. Ils sont associes a une evolution metamorphique principalement en decompression (7,5 a 4 kbar). Ces domes seraient issus d'une deformation heterogene avec extrusion - a composantes verticale et decrochante - le long du mkt. Ils sont contemporains de la mise en place du pluton syenitique d'hemasil, magma potassique probablement issu d'une source mantellique enrichie et ayant certainement subi une contamination crustale. Les donnees #4#0ar/#3#9ar permettent d'estimer un age de mise en place a 9 ma. Il apparait donc qu'une partie de l'evolution tectonometamorphique et magmatique du kmc est tres recente et probablement en relation avec l'activation des grands decrochements regionaux. Elle est a rapprocher de celle du haut himalaya du nanga parbat situe au sud-ouest.
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Van, Gool Jeroen Antonius Maria. "The Grenville front foreland fold-and-thrust belt in southwestern Labrador : mid-crustal structural and metamorphic configuration of a Proterozoic Orogenic thrust wedge /." 1992. http://collections.mun.ca/u?/theses,48444.
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Grenier, Robert. "The Appalachian fold and thrust belt, northwestern Newfoundland /." 1990. http://collections.mun.ca/u?/theses,108913.
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McClay, K. R. (Kenneth R. ). "Structural geology and tectonics / by Kenneth Ronald McClay." 2000. http://hdl.handle.net/2440/38528.
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Includes bibliographical references.1 v. (various pagings) :
Title page, contents and abstract only. The complete thesis in print form is available from the University Library.
Consists of 75 published papers on structural geology and tectonics grouped into 5 broad themes -- and ore deposits; analogue modelling; extensional tectonics; thrust tectonics; and, tectonics, all presented in chronological order within the group.
Thesis (D.Sc.)--University of Adelaide, Dept. of Geology and Geophysics, 2000
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Breen, Nancy Ann. "Three investigations of accretionary wedge deformation." 1987. http://catalog.hathitrust.org/api/volumes/oclc/16928889.html.
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Thesis (Ph. D.)--University of California, Santa Cruz, 1987.Typescript. "These papers describe faulting and folding observed on the seafloor using SeaMARC II side-scan sonar, seismic reflection, and 3.5 kHz data"--P. 1. Includes bibliographical references.
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Qayyum, Mazhar. "Crustal shortening and tectonic evolution of the Salt Range in Northwest Himalaya, Pakistan /." 1991. http://hdl.handle.net/1957/9504.
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Merguerian, Charles. "Stratigraphy, structural geology, and tectonic implications of the Shoo Fly Complex and the Calaveras-Shoo Fly thrust, Central Sierra Nevada, California." Thesis, 1985. https://doi.org/10.7916/d8-mdta-w378.
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Mylonitic rocks of the Shoo Fly Complex form a region of epidote-amphibolite grade quartzose and granitoid gneiss, subordinate schist and calcareous rocks, and rare amphibolite in the foothills of the Sierra Nevada range in central California. The Shoo Fly has endured a complicated Phanerozoic structural development involving seven superposed deformations at variable crustal depths. The first four of these (D1-D4) involved tight to isoclinal folding and shearing under medium grade metamorphic conditions. The last three (D5-D7) are marked by open folding and retrograde metamorphism of older fabric elements.
The Shoo Fly is in ductile fault contact with east-dipping argillite, chert, and marble of the Calaveras Complex. The Calaveras-Shoo Fly thrust formed during D3 and is a 1-2 km wide syn-metamorphic ductile shear zone. Recognition of D3 overprinting of older Dl+D2 fabrics along the thrust zone indicates that upper plate Shoo Fly rocks record an earlier and more complex structural history than the lower plate Calaveras rocks.
Paleozoic gneissic granitoids, an important lithologic component of the Shoo Fly, were intruded as a series of plutons ranging from calc-alkaline gabbro to granitoid (predominate) to syenite. They truncated the early S1 foliation in the Shoo Fly and were folded during regional D2 and D3 events when they were penetratively deformed into augen gneiss, blastomylonite, and ultramylonite.
The Sonora dike swarm occurs as an areally extensive (> 1500 km2) subvertical consanguineous suite of andesite, lamprophyre, and basalt dikes that trend east-west across the Calaveras and Shoo Fly Complexes. The metamorphic complexes form the basement to a middle Jurassic calc-alkaline plutonic arc (Jawbone granitoid sequence). A middle Jurassic K-Ar age on the dikes (157-159 m.y.) together with the data of this report indicate that they are petrogenetically related to the Jawbone granitoid sequence and that the dikes probably formed during subduction beneath a continental arc.
The dikes provide an important structural marker in the Shoo Fly and Calaveras Complexes. Intrusion of the dike swarm was sensitive to a structural anisotropy in the basement complexes. Since they intruded east-west along a spaced regional schistosity developed during folding of the Calaveras-Shoo Fly thrust, thrusting and subsequent folding were clearly pre-middle Jurassic events.
Available geochronologic data sets middle Ordovician to late Devonian intrusive ages for the gneissic granitoids, establishing a pre-late Devonian depositional age for the Shoo Fly. D1 and intrusion of the orthogneiss protoliths may have been precursors of the Late Devonian to Early Mississippian Antler orogeny or, alternatively, may have occurred significantly earlier than the Antler orogeny. Based on cross-cutting relations, D2 formed during the Antler orogeny, D3 and possibly D4 during the Sonoma orogeny, and D5 and D6 during the Nevadan orogeny.
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Cook, Jennie E. "Development of a dilatant damage zone along a thrust relay in a low-porosity quartz arenite." 2005. http://etd.utk.edu/2005/CookJennie.pdf.
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McLaren, Sandra N. (Sandra Noeline). "Long-term consequences of the redistribution of heat producing elements within the continental crust: Australian examples / Sandra N. McLaren." 2001. http://hdl.handle.net/2440/19839.
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Includes copies of articles co-authored by author during the preparation of this thesis in back pocket.Includes bibliographical references (leaves 113-124).
viii, 172 leaves : ill. (some col.), maps ; 30 cm.
Title page, contents and abstract only. The complete thesis in print form is available from the University Library.
Focuses on the impact of change in the distribution of heat producing elements on lithospheric thermal regimes and on temperature dependent processes such as metamorphism, magmatism and deformation, with application to Proteozoic Australia (Mount Isa and Mount Painter inliers).
Thesis (Ph.D.)--Adelaide University, Dept. of Geology and Geophysics, 2001
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Coley, Katharine Lancaster 1956. "Structural evolution of the Warwick Hills, Marathon Basin, West Texas." 1987. http://hdl.handle.net/2152/10915.
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A detailed structural analysis was conducted of the Warwick Hills at the northeast tip of the doubly-plunging Dagger Flat anticlinorium, Marathon Basin, west Texas. Field work delineated a folded duplex structure composed of three horses. Thrust transport was towards the northwest and resulted in a hinterland-dipping duplex. Initial thrusting In the Warwick Hills shortened the area by 2.2:1 (54%). Post-thrusting, the duplex underwent nearly isoclinal folding creating two anticlines and a syncline, second-order folds to the Dagger Flat anticlinoium. Folding combined with thrusting brought the total shortening of the rock package to 6.5:1 (85%). Earlier estimates gave a shortening for the Warwick Hills of 3:1. Finally, the folded duplex was extended by oblique tear faulting that offset the folded thrusts accommodating extension of the major folds in a northeast direction. These tear faults occurred post-plunging of the folds and were the last deformational movements that affected the Warwick Hills. The Ordovician Maravillas and Devonian Caballos Formations acted in the Warwick Hills as a structurally competent couplet. Addition or subtraction of this couplet, or units in this couplet, controlled the location of the major and minor thrusts, the style and shape of folds, and the location of the fold hinges. Bounding the couplet are incompetent shales of the Ordovician Woods Hollow and the Mississippian Tesnus Formations. Thrusts in the Warwick Hills duplex have a basal décollement in the Woods Hollow shale and ramp up through the Maravillas/Caballos couplet with an upper décollement in the Tesnus shale. The entire duplex was primarily folded by flexural slip (i.e. concentric folds) as evidenced by slickensides oriented parallel to bedding and perpendicular to fold axes, the constant thickness of the competent layers and the change in fold shape with depth. Fold wavelength, as determined from the couplet in the lowest thrust sheet, averages ~1,300 m and the average fold axis for the Warwick Hills, as determined stereographically, plunges ~54° N90°E. Shale in the Woods Hollow and Tesnus Formations bounding the couplet, flowed passively during folding into the cavities that were created by the bending of the more competent units. Lower and upper boundaries of disharmonic folding developed in the Woods Hollow and Tesnus Formations respectively. Unique to this area when compared to the rest of the anticlinorium are the presence of tightly folded thrusts and steep east-trending fold axes. The anticlinorium plunges in the Warwick Hills because it drapes off a down-to-the-northeast basement fault. Folds were "dragged" or diverted to the east during thrusting of the duplex over this transversely-oriented paleotopographic fault scarp, or were diverted subsequent to thrusting of the duplex by strike-slip movements at depth along the basement fault.text
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Coetzee, Dirk Stephanus. "Syn-tectonic quartz vein formation in relationship to metamorphism, fluid inclusions and thrust tectonism on the northern margin of the Witwatersrand Basin." Thesis, 2014. http://hdl.handle.net/10210/10899.
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D.Phil. (Geology)A specific geological event has been characterized with the aid of an integrated metamorphic and fluid inclusion study of data obtained from syn-tectonic vein-quartz associated with thrusting and bedding-parallel shear along the northern margin of the Witwatersrand Basin. The vein-quartz associated with this event occurs as boudin-shaped bodies with their long and intermediate axes orientated within the foliation-, bedding- or fault-planes. The length of the quartz lenses which are spatially confined to shear zones often exceeds the thickness of the shear zones. These phenomena and the fact that quartz-fibres are orientated parallel to and not at right angles to the foliation confirms the syn-tectonic nature of the quartz veins. Heterogeneous P-T condition is indicative of imbrication, i.e. crustal thickening which is also substantiated by the random growth of pyrophylite and kyanite in shear zone assemblages, indicating that metamorphism outlasted deformation. Metamorphic studies of aluminous schists and vein-quartz with pyrophylliteand pyrophyllite - kyanite selvages established the development of two critical mineral assemblages: 1 Kaolinite + 2 Quartz = 1 Pyrophyllite + 1 H20 ... (1) and at higher P-T conditions 1 Pyrophyllite = 1 Kyanite + 3 Quartz + 1 H20 ... (2). The schists and quartz vein assemblages are quartz-oversaturated in contrast to the study material of Wallmach and Meyer (1990) which is quartz-undersaturated. Peak metamorphic conditions, therefore, are closely constrained by the position of the reaction curve (2) in P-T space, as is also substantiated by the presence of coexisting kyanite and pyrophyllite which are closely associated with syn-tectonic vein-quartz at the Florida Lake, Monarch Shaft and Krugersdorp localities. The nature of and circumstances under which the equilibrium aSsemblage pyrophyllite + kyanite + quartz has formed support an univariant situation, i.e. this assemblage can only coexist along the pyrophyllite kyanite isograd. The mineral assemblages that equilibrated during peak metamorphism are still present in the rocks of the shear zones, and show only incipient rehydration. The quartz-oversaturated nature of the rocks in the shear zones and the fact that kyanite formation is ascribed to reaction (2), cannot explain the abundance of quartz veins. Accordingly it is concluded that there must have been an external source from which Si02 was imported into shear zone to give rise to the formation of the large quantities of vein-quartz.