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Structural geology of the Hengshan-Wutai-Fuping mountain belt: implications for the tectonic evolution ofthe Trans-North China OrogenZhang, Jian, 張健 January 2007 (has links)
published_or_final_version / abstract / Earth Sciences / Doctoral / Doctor of Philosophy
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Some geomorphological problems of the Patsin Range and adjacent areas,north eastern Hong KongHo, Kee-hau, 何其豪 January 1971 (has links)
published_or_final_version / Geography and Geology / Master / Master of Arts
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Post-cretaceous structural geology near Del Norte Gap, Brewster County, Texas / Del Norte Gap, Brewster County, TexasEverett, John R. 18 July 2014 (has links)
The-west-dipping, north-northwest-trending Black Peak fault and associated monoclines which form the western flank of the Marathon dome, are well exposed near Del Norte Gap. Field mapping shows that the dip of the Black Peak fault increases downward from zero to 80 degrees. A northeast-trending right lateral fault cuts the hanging wall of the Black Peak fault at Del Norte Gap. The Black Peak fault has greater displacement south of the gap than north of the gap. Several north and northwest-trending normal faults cut the Cochran Mountains. The folding and faulting took place after the deposition of the upper Boquillas Limestone and before the deposition of Quaternary gravels. Vertical uplift of the Marathon dome during the Laramide orogeny produced the Black Peak fault and associated features. Normal faults later cut the area. The structural features near Del Norte Gap correspond well to previously described analytical and experimental configuration of features produced by differential vertical movement of basement blocks and previously described examples of vertical tectonics. / text
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Tectonostratigraphic history of the southern Foothills terrane.Newton, Maury Claiborne, III. January 1990 (has links)
As a tool in discriminating basic rocks from different tectonic settings, a type of diagram was developed that employs three ratios of trace elements. The diagram separates basic rocks formed in mid-ocean ridge, intra-plate, and volcanic arc settings. It can be used to differentiate basalts from marginal basin, forearc, and arc rift zone settings. A second application of this type of diagram, employing major elements, distinguishes tholeiitic, calcalkaline, and boninitic series volcanic rocks. The southern part of the Foothills terrane, western Sierra Nevada, California, is composed chiefly of Jurassic-Triassic(?) metavolcanic and metasedimentary rocks of lower greenschist grade. Major tectonism affecting the terrane, associated with the Late Jurassic-Early Cretaceous Nevadan orogeny, was sinistral transpression with shearing along the Bear Mountains and Melones fault zones. The line of slip in high shear strain regions is approximated by the modal stretching lineation, which is at a rake of approximately 45° SE to the general shear zone orientation, suggesting sub-equal components of strike slip and dip slip. The sense of shear from kinematic indicators is consistently east side to the northwest. The terrane hosts three types of syngenetic massive sulfide deposits: Cyprus-type Cu deposits, Kuroko-type Zn-Cu-Pb deposits, and Besshi-type Cu-Zn deposits. The Cyprus-type deposits lie at the top of a Triassic(?) tholeiitic - basalt sequence in the lower Penon Blanco Formation. The deposits are part of an ophiolitic sequence that appears to have formed in an open-ocean spreading center environment. Felsic lava facies host the Kuroko-type deposits at the top of the Middle to Late Jurassic upper Gopher Ridge Formation, a dominantly bimodal sequence of meta-rhyolitic lavas and tuffs and meta-basaltic lavas. The tectonic setting appears to have been an arc-rift zone that formed during the transition from arc volcanism forming the lower Gopher Ridge Formation to younger basinal sedimentation forming the Mariposa Formation. The Besshi-type deposits are sediment-hosted in the Late Jurassic Mariposa Formation. They appear to have formed in the median part of a long linear basin between rifted arc segments. The inferred tectonic setting of the sulfide deposits was an early back-arc or interarc basin, which may have been related to transtensional tectonics.
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Surface structure on the east flank of the Nemaha Anticline in northeast Pottawatomie County, KansasRatcliff, Gene A January 1957 (has links)
No description available.
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Reappraising the Numidian system (Miocene, southern Italy) deep-water sandstone fairways confined by tectonised substrateRomagna Pinter, Patricia January 2017 (has links)
No description available.
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The stratigraphy and sedimentology of the Upper Johannesburg and Turffontein Subgroups in the Southwestern portion of the Welkom GoldfieldBailey, Andrew Charles 06 June 2016 (has links)
Thesis (M.Sc.)--University of the Witwatersrand, Faculty of Science, 1991 / This study documents and interprets the stratigraphy and sedimentary environments of the upper Johannesburg and Turffontein Subgroups of the Witwatersrand Supergroup on St. Helena Gold Mine. These data are used to construct a tectono-stratigraphic framework and determine the general distribution of economic mineralization.
[Abbreviated abstract. Open document to view full version]
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Parental magmas of the Bushveld Complex, South AfricaCurl, Edward Alexander, 1972- January 2001 (has links)
Abstract not available
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P and S velocity structure beneath the Gulf of MaineSattel, Daniel 04 October 1990 (has links)
Seismic refraction data collected in 1985 by the USGS were used in
this study to derive the P and S velocity structure of the crust beneath the
Gulf of Maine. The data quality differs among instruments and is affected
by surficial lateral heterogeneities, a ringy source signature and
reverberations. Velocity models of the crust were computed by one-dimensional
raytracing and by wavefield continuation. Pg arrivals were
modeled using both techniques to derive the P velocity of the upper 5-15
km of the crust and give very similar results. Strong Sg arrivals were also
observed, and computed S amplitudes generated from P-S conversion for
different scenarios show that the observed S wave is generated at the
basement top. Two small sediment basins are indicated in the Central
Plutonic Zone and two faults are suggested in the Fault Zone and the
Central Plutonic Zone, respectively. Beneath the sediments the layering is
uniform with dips of less than 2° and a fairly laterally homogeneous
velocity structure, in spite of lateral variations in reflectivity. P and S
velocities increase from 5.3 and 2.8 km/s, respectively, at the basement to
6.4 and 3.7 km/s at 10 km depth. A laterally discontinuous low velocity
zone is indicated at 6-10 km depth which might be caused by laccolithic
granitic intrusions. However, magnetic and gravity data do not show
indications for felsic intrusions where the low velocity zones are observed.
Velocity differences among some instruments suggest anisotropy in the
upper 6 km of the crust, as observed in onshore Maine. These instruments
indicate velocities parallel to the structural grain of the Appalachians of
6.1-6.4 km/s and velocities transverse to the grain of 5.8-6.1 km/s in the
depth range 2-6 km. Cashes Ledge granite, a site of an intense magnetic
high, has a reduced velocity compared to surrounding rocks and might
extend to at least 10 km depth. Poisson's ratio for the upper crust ranges
from 0.23-0.26.
To derive the velocity structure of the middle and lower crust, wide-angle
reflections interpreted to be PmP and SmS were modeled by one-dimensional
raytracing. In addition synthetic seismograms were computed
using the WKBJ method to constrain possible middle and lower crust
velocity models by their PmP and SmS amplitudes. Recorded PmP and
SmS wide-angle reflections have quite different amplitudes and travel-times
among instruments suggesting a heterogeneous lower crust. The crust
below 10 km depth has an average P velocity of 6.5-6.8 km/s and an
average S velocity of 3.7-3.9 km/s. Most instruments indicate a Poisson's
ratio of around 0.25 between 10 km depth and Moho and one instrument
suggests a Poisson's ratio of 0.28. Hence, the middle and/or lower crust
under the Gulf of Maine is heterogeneous and represents average crust
modified by mafic intrusions, probably during Mesozoic extension. Moho
depth is indicated between 30 and 37 km depth. Wide-angle reflections
coming from 28 km depth as indicated by two instruments are interpreted
to come from the top of a lower crustal intrusion. This interpretation is
supported by an observed mismatch between the models giving a thickness
of 28 km and the reflection data.
Although it represents a different geological terrane, the velocity and
thickness of the crust beneath the central Gulf of Maine is very similar that
onshore Maine. / Graduation date: 1991
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Subsurface structural evolution along the northern Whittier fault zone of the eastern Los Angeles basin, Southern CaliforniaHerzog, David W. 26 January 1998 (has links)
The Whittier fault forms the central part of a fault system extending
from the East Montebello fault at Whittier Narrows to the Elsinore fault,
which is traced as far as the Mexican border. The Whittier fault forms a
restraining bend in this fault system, resulting in uplift of the Puente Hills.
The northwestern part of the Whittier fault in the Whittier oil field in the
eastern Los Angeles basin strikes approximately N65��W and dips 70-75��
northeast. The fault is near the range front of the Puente Hills northwest of
Turnbull Canyon, and within the Puente Hills to the southeast.
The central reach of the Whittier fault had normal separation in the
Relizian and Luisian stages of the middle Miocene. From the Mohnian
through Repettian stages of the late Miocene and early Pliocene, little, if any,
offset occurred until the initiation of reverse offset in the Venturian stage of
the late Pliocene. A component of right-lateral strike-slip may have been
added near the end of the Pliocene, coinciding with the formation of the
Elsinore fault. The Workman Hill and Whittier Heights faults may have
formed in the late Pliocene to early Pleistocene, coinciding with the possible
initiation of strike-slip on the Whittier fault. The present sense of slip on the
Whittier fault southeast of the study area is nearly pure right-lateral strike-slip,
with a slip rate of 2-3 mm/yr. The northwestern part of the Whittier
fault has a component of reverse slip of approximately 1 mm/yr. The
amount of strike-slip on this part of the fault was not determined by this
study.
The Rideout Heights, 304, and 184 low-amplitude anticlines formed in
the Whittier oil field area in the late Miocene and early Pliocene. The
Rideout Heights anticline is a southwest-verging fault-propagation fold
trending northwesterly from the mouth of Turnbull Canyon through the
Rideout Heights area. Strata are overturned in the southwest limb of the
fold, and normally dipping in the northeast limb; the fold has been cut along
its hinge by the Whittier fault.
The 304 and 184 anticlines are north-verging and appear to be beddingplane
shear folds in the northeast limb of the La Habra syncline. Recent
strike-slip on the Whittier fault may have reactivated the 184 anticline,
causing uplift of the footwall block south of Turnbull Canyon. North of
Turnbull Canyon, the Whittier fault is at the range front with no evidence of
Quaternary footwall uplift. The 304 anticline could be a fault-propagation
fold from a previously-unknown southwest dipping blind reverse fault south
of the Whittier fault; uplift on this fold could also be the cause of footwall
uplift south of Turnbull Canyon.
Active fault traces, possibly strike-slip, are on or near the Whittier fault
south of Turnbull Canyon, but to the north, recent offsets appear to be
northeast of the Whittier fault in the Puente Hills. These offsets may
represent an attempt of the Whittier fault to straighten itself by bypassing the
restraining bend at Turnbull Canyon. so, this movement is too recent to
offset conglomerate beds more than a few tens of meters. / Graduation date: 1998
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