Detailed field and petrographic study of the Precambrian Rough Ridge Formation of the Packsaddle Schist documents a more complex tectonic history for the Llano Uplift than has previously been reported. The Rough Ridge Formation was affected by two metamorphic events and four phases of deformation. Mineral assemblages in pelitic and mafic lithologies are characteristic of the amphibolite facies, and the presence of cordierite in preference to almandine indicate low pressure during part of the metamorphism. Inclusions of staurolite in a Mn-rich garnet, coupled with the absence of staurolite elsewhere in the rock suggest that pressure may have ranged from medium to low during metamorphism. Textures indicate that post-tectonic recrystallization occurred as a consequence of either slow cooling or of reheating after dynamothermal events. The first phase of deformation (D1) was a complete transposition of original sedimentary layers, with a pervasive foliation (S1) forming parallel to the axial planes of isoclinal folds. D2 is characterized by small folds and a crenulation cleavage S2. D3 formed a crenulation cleavage S3. D4 formed the prominent folds in the area, with a pervasive axial planar cleavage S4. Isolated occurrences of a pre-S1 metamorphic foliation are evidence of still earlier deformation. In one pelitic unit, oriented inclusions show that garnet growth was post-D2, while cordierite growth was post-D4. Growth and recrystallization of micas, quartz and feldspar span all the deformations. The timing of deformation events is bracketed by the pre- to syn-tectonic intrusion of the 1167 +/- 15 m.y. old Red Mountain Gneiss, and the post-tectonic intrusion of a 1080 +/- 15 m.y. old melarhyolite dike. The results of this study demonstrate that rocks of the Llano Uplift have undergone a complex tectonic and metamorphic history similar to that seen in other Grenville Age rocks of North America. / text

This study investigates the downstream controls of alluvial sediment composition and river channel adjustment in the Llano River watershed, Central Texas, USA. The Llano River watershed is characterized by a highly variable, flood-prone flow regime and a complex lithology of Cretaceous carbonate rock, Paleozoic sedimentary rock, and Precambrian igneous and metamorphic rock. Sedimentary variables for this study include particle size, sorting, carbonate content, and magnetic susceptibility. Channel adjustment includes the planform dimension and cross-sectional dimensions of bankfull- and macro-channels. Nineteen sites along the Llano River and selected tributaries were visited to measure cross-sectional channel geometry and sample bed, bank, and overbank sediment. Laboratory analyses of sediment and hydraulic analyses of cross sections were accompanied by analyses of partial-duration flood frequency, flow resistance, hydrography, digital elevation models, and statistical correlation. Findings include: (1) channel-bed material reduces in size with downstream distance, despite increasing valley confinement and bedrock exposure; (2) the downstream decrease in particle size is more evident for channel-bar deposits than for low-flow-channel (thalweg) deposits; (3) an abrupt gravel-to-sand transition occurs about 20 kilometers downstream of the Paleozoic-Precambrian contact; (4) an abrupt coarse- to fine-gravel transition occurs between 75 and 90 kilometers downstream the North Llano and South Llano Rivers; (5) channel-bank material increases downstream, contrasting with decreases in bed material; (6) carbonate content and magnetic susceptibility of alluvial sediment are inversely related, with carbonate content peaking near Junction; (7) four general categories to classify reaches of the North Llano, South Llano, and Llano Rivers are based on hydrology, planform morphology, lithology, and valley confinement; (8) mean depth increasingly compensates for bankfull discharge in a downstream direction; (9) mean depth compensates more than width for macrochannels; and (10) the return periods for bankfull and macro-channels are about 1 to 2 years and greater than 10 years, respectively. The results of this study will contribute to fluvial geomorphic theory of downstream trends in sediment composition and channel adjustment; as well as inform applied efforts related to aquatic biology, flood hazards, infrastructure design, and riparian and water-resource management in the region. / text

Historical research reveals a repeating pattern of uplift, erosion, and deposition in the region of the Llano Uplift, central Texas. This report examines the topography of the pre-Cretaceous landscape. The data consist of points, in three dimensions, that are located on the erosional surface, as determined by three methods. Category I data lie upon the contact between Cretaceous strata and underlying Paleozoic sediments or Precambrian basement; Category II data are defined in the subsurface from well logs; and Category III data are topographic high points where the Cretaceous has eroded away, but the underlying unit has not eroded (an exhumed surface). Digital mapping procedures were used to create triangulated irregular networks, three dimensional scenery, and topographic profiles. The digitally reconstructed surface is compound, consisting of higher, older erosional surfaces, incised into by rejuvenated stream activity to create lower, younger surfaces. This valley/divide topography, which is regional in extent, could not have been visualized without modern GIS technology. / text

A new barometric technique measuring stored stress in quartz inclusions via laser Raman microspectrometry was employed in an attempt to elucidate the extent of highpressure (HP) metamorphism in the Llano Uplift of central Texas. Rare lithologies within the Llano Uplift contain mineralogical evidence of HP metamorphism (pressures from 1.4 to 2.4 GPa at temperatures from 650 to 775°C), but much of the uplift is composed of felsic gneisses lacking any HP signature; these felsic gneisses may never have transformed to HP assemblages, or they may have been thoroughly overprinted by later low-pressure events. Barometry via laser Raman microspectrometry computes entrapment pressure for a quartz inclusion in garnet from measurement of the displacements of its Raman peak positions from those of a quartz standard at atmospheric pressure. Quartz inclusions in garnets that grew in felsic gneisses under HP conditions should retain HP signatures, despite later overprinting. Application of the Raman microspectrometry technique should therefore allow barometry of previously uncharacterizable rocks. For two localities in the Llano Uplift, entrapment pressures from Raman barometry (0.6-0.7 GPa and 0.2-0.3 GPa) were substantially lower than pressures expected based on conventional barometers (1.4 GPa and 1.6-2.4 GPa). This absence of any HP signatures in the Llano rocks contrasts with more successful applications of the Raman technique by previous workers in high P/T blueschist-facies rocks. A key difference in the Llano rocks is that they reached peak temperatures at which intracrystalline diffusion in garnet, driven by compositional gradients produced during growth, had noticeable effects: complete homogenization of growth zoning had occurred in the locality that produced the greatest discrepancies between Raman and conventional pressures, and modest relaxation of zoning occurred in the locality with the smaller discrepancies. The failure of the Raman technique to recover pressures consistent with conventional barometry in the Llano Uplift is therefore attributed to relaxation of stress on the quartz inclusions as the result of intracrystalline diffusion within the garnet. This conclusion suggests that use of the Raman barometric technique must be restricted to rocks whose time-temperature histories produce only very limited intracrystalline diffusion in garnet, typically those rocks whose peak metamorphic temperatures fall at or below upper amphibolite-facies conditions. / text

The purpose of the author is to present a geological survey of the Backbone Ridge area in Burnet and Llano counties, Texas. During the summer of 1947 while enrolled in a geologic field course in McCullough County, it was noted that a new classification of the Cambrian and Ordovician formations In central Texas had been presented In the literature. It was noted at the same time that the Paleozoic rocks of the Llano uplift are more highly faulted than had been shown on previous geologic maps of the region. The writer concluded from field observations that the Backbone Ridge area was more complexly faulted then had been previously shown, and it was decided to test this conclusion by making a detailed geologic map of the area using the stratigraphic subdivisions recently established by Bridge, Barnes, and Cloud. A detailed study was made of these subdivisions and a large number of the type sections were visited. It was necessary to study the complete geologic history of the region in order that the events which involved the complex structural pattern and the present physiographic forms might be properly understood. The material contained in this report consists of data obtained from the literature and from field observations which were made in the area during the months of June and July of 1948. / text

Mitl Valdez's film Los confines (1987) is an adaptation of several works of fiction by the Mexican author Juan Rulfo. The director chose to adapt two short stories ("Talpa" and "¡Diles que no me maten!") and an episode from the author's first novel, Pedro Páramo. Valdez's intent was to "capturar el sentido" of the Jaliscan author or, in other words, to remain faithful to certain elements of his writing while adjusting them to the filmic medium. The musical score of Los confines is the method of appropriation that this study endeavors to investigate, since it shares common themes, metaphors, and imagery with the source texts. The musical language of Los confines not only communicates meaning within the film, but echoes elements of Rulfo's writing as well. Musical motifs in the score evoke concepts and symbols that form part of the writer's fictive universe and illustrate how Valdez finds "un equivalente en la expresión cinematográfica" for Rulfian material (qtd. in Pelayo).

We explore efficient parallel radix sort for the AMD Fusion Accelerated Processing Unit (APU). Two challenges arise: efficiently partitioning data between the CPU and GPU and the allocation of data in memory regions. Our coarse-grained implementation utilizes both the GPU and CPU by sharing data at the begining and end of the sort. Our fine-grained implementation utilizes the APU’s integrated memory system to share data throughout the sort. Both these implementations outperform the current state of the art GPU radix sort from NVIDIA. We therefore demonstrate that the CPU can be efficiently used to speed up radix sort on the APU. Our fine-grained implementation slightly outperforms our coarse-grained implementation. This demonstrates the benefit of the APU’s integrated architecture. This performance benefit is hindered by limitations in the APU’s architecture and programming model. We believe that the performance benefits will increase once these limitations are addressed in future generations of the APU.

The Pennsylvanian Marble Falls Formation in the Llano Uplift region of the southern Fort Worth Basin (Central Texas) is a Morrowan-Atokan mixed carbonate-siliciclastic unit whose deposition was influenced by icehouse glacioeustatic sea-level fluctuations and foreland basin tectonics. Previous interpretations of the Marble Falls Formation focused on outcrop data at the fringes of the Llano Uplift. This study uses a series of 21 cores to create a facies architectural model, depositional environmental interpretation, and regional sequence stratigraphic framework. On the basis of core data, the study area is interpreted to have been deposited in a ramp setting with a shallower water upper ramp area to the south and a deeper water basin setting to the north. Analysis of cores and thin sections identified 14 inner ramp to basin facies. Dominant facies are: (1) burrowed sponge spicule packstone, (2) algal grain-dominated packstone to grainstone, (3) skeletal foraminiferal wackestone, and (4) argillaceous mudstone to clay shale. Facies stacking patterns were correlated and combined with chemostratigraphic data to improve interpretations of the unit’s depositional history and form an integrated regional model. The Marble Falls section was deposited during Pennsylvanian icehouse times in a part of the Fort Worth Basin with active horst and graben structures developing in response to the Ouachita Orogeny. The resulting depositional cycles reflect high-frequency sea-level fluctuations and are divided into 3 sequences. Sequence 1 represents aggradational ramp deposition truncated by a major glacioeustatic sea-level fall near the Morrowan-Atokan boundary (SB1). This fall shifted accommodation basinward and previously distal areas were sites of carbonate HST in Sequence 2 deposition following a short TST phase. Sequence 3 represents the final phase of carbonate accumulation that was diachronously drowned by Smithwick siliciclastics enhanced by horst and graben faulting. These findings contribute to our understanding of the depositional response to glacioeustatic sea-level changes during the Pennsylvanian and can also form the basis for constructing a sedimentological and facies analog for Morrowan to Atokan shallow- to deepwater carbonates in the Permian Basin and the northern Fort Worth Basin. / text

Deformation and partial melting have long been recognized to occur together, but differentiating which actually occurred first has remained enigmatic. Prevailing theories suggest that partial melting typically occurs first, and deformation is localized into melt-rich areas because they are rheologically weak. However, evidence from three different areas, suggests the role of strain has been underestimated in localizing partial melting. The Wet Mountains of central Colorado provide evidence for synchronous partial melting and deformation, with each process enhancing the other. Throughout the Wet Mountains, deformation is concentrated in areas where melt producing reactions occurred, and melt appears to be localized along deformation-related features. Melt microstructures present within the Wet Mountains correlate well with crustal-scale plutons and magmatic bodies and provide a proxy for crustal-scale melt flow. Granitic gneisses from the Llano Uplift, central Texas, provide evidence for partial melting occurring within small-scale shear zones and surrounding country rocks, synchronously. In the field, shear zones appear to contain former melt, whereas the country rock does not provide macroscopic evidence for partial melting. However, detailed microstructural investigation of shear zones and country rocks indicates the same density of melt microstructures, in both rock types. Melt microstructures are important for understanding the full melting history of a rock and without detailed structural and petrographic analysis, erroneous conclusions may be reached. Granulite-facies migmatites of the Albany-Fraser Orogen, southwestern Australia, have undergone partial melting, synchronous with three phases of bidirectional extension. Four major groups of leucosomes, including: foliation-parallel, cross-cutting, boudin neck and jumbled channelway leucosomes and late pegmatites were analyzed via whole-rock geochemistry, and there is evidence for fluid-saturated and -undersaturated biotite- and amphibole-dehydration melting. Migmatites from these three locations contain pseudomorphs of melt along subgrain and grain boundaries, areas of high dislocation density, in quartz and plagioclase. For these rocks that involve multicomponent systems, the primary cause for preferential melting in high strain locations is enhanced diffusion rates along the subgrain boundary because of pipe diffusion or water associated with dislocations. / text

Supervisors: Luis Urrieta and Noah De Lissovoy This qualitative and sociohistorical study examines the lives and experiences of Chicana/o educators in Texas and the ideological and political discourses of equity and social justice that they draw from to shape their practice in three educational sites: the Llano Grande Center (LGC), Red Salmon Arts/Resistencia Bookstore (RSA), and the Advanced Seminar in Chicana/o Research (ASCR). I document their work based on the oral narratives of fifteen educators, site document analysis, and ethnographic work I conducted as observant participant associated with these organizations. This project extends recent scholarship that links critical pedagogy, social and cultural theories of identity formation and new social movement scholarship to understand the multiple cultural, social and political dimensions of activist education. My principal findings indicate new senses of individual and collective identity practice, reframed critical and culturally relevant pedagogies, and a reconceptualization of indigenous discourse and practice. These findings have important implications for activists, educators and researchers by rearticulating scholar activist work in new more emancipatory ways that considers place-based models of critical and cultural relevant teaching and learning and more radically democratic research practices. / text