The Andes Mountains provide an ideal natural laboratory to analyze the relationship between the tectonic evolution of a subduction margin, retroarc shortening, basin morphology, and volcanic activity. Timing of initial shortening and foreland basin development in Argentina is diachronous along strike, with ages varying by 20-30 million years. The Neuquén Basin (32°S-40°S) of southern-central Argentina sits in a retroarc position and provides a geological record of sedimentation in variable tectonic settings from the Late Triassic to the early Cenozoic including: 1.) active extension and deposition in isolated rift basins in the Late Triassic-Early Jurassic; 2.) post-rift back-arc basin from Late Jurassic-Late Cretaceous; 3.) foreland basin from Late Cretaceous to Oligocene; and 4.) variable extension and contraction along-strike from Oligocene to present. The goal of this study is to determine the timing of the transition from post-rift thermal subsidence to foreland basin deposition in the northern Neuquén Basin and then assess volcanic activity and composition during various tectonic regimes. The Aconcagua and Malargüe areas (32°S and 35°S) are located in the northern segment of the Neuquén Basin and preserve Upper Jurassic to Miocene sedimentary rocks, which record the earliest phase of shortening at this latitude. This study presents new sedimentological and detrital zircon U-Pb data from the Jurassic to latest Cretaceous sedimentary strata to determine depositional environments, stratigraphic relations, provenance, and maximum depositional ages of these units and ultimately evaluate the role of tectonics on sedimentation in this segment of the Andes. The combination of provenance, basin, and subsidence analysis shows that the initiation of foreland basin deposition occurred at ~100 Ma with the deposition of the Huitrín Formation, which recorded an episode of erosion marking the passage of the flexural forebulge. This was followed by an increase in tectonic subsidence, along with the appearance of recycled sedimentary detritus, recorded in petrographic and detrital zircons analyses, as well development of an axial drainage pattern, consistent with deposition in the flexural forebulge between 95 and 80 Ma. By ca. 70 Ma the volcanic arc migrated eastward and was a primary local source for detritus. Growth structures recorded in latest Cretaceous units very near both the Aconcagua and Malargüe study areas imply 35-40 km and 80-125 km of foreland migration between 95 and 60 Ma in the Aconcagua and Malargüe areas, respectively. Strata ranging in age from Middle Jurassic to Neogene were analyzed to determine their detrital zircon U-Pb age spectra and Hf isotopic composition to determine the relationship between magmatic output rate, tectonic regime, and crustal evolution. When all detrital zircon data are combined, significant pulses in magmatic activity occur from 190-145 Ma, and at 128 Ma, 110 Ma, 69 Ma, 16 Ma, and 7 Ma. The duration of magmatic lulls increased markedly from 10-30 million years during back-arc deposition (190-100 Ma) to ~40-50 million years during foreland basin deposition (100-~30 Ma). The long duration of magmatic lulls during foreland basin deposition could be caused by flat-slab subduction events during the Late Cretaceous and Cenozoic or by long magmatic recharge events. There are three major shifts towards positive Hf isotopic values and all are associated with regional extension events whereas compression seems to lead to more evolved isotopic values.

The Copiapó region in northern Chile contains numerous intrusion- and volcanichosted IOCG vein systems. These veins share many features with larger IOCG systems in the region (e.g., Candelaria, Punta del Cobre), including abundant hydrothermal magnetite or hematite ± Cu, Au, REE, and other elements, and exhibit similar styles of mineralization including voluminous breccias, stockwork, and massive veins. The relatively simple geometries and small size of veins offer advantages for study of zoning and genesis in an IOCG system; and, they also provide an interesting counterpoint to classic epithermal Ag-Au veins. The vein systems exhibit systematic patterns in the alteration and mineralization zoning in both time and space. Deeper exposures are characterized by high-temperature styles of sodic and sodic(-calcic) alteration with Fe and Cu depleted vein fill assemblages. This passes upwards through a proximal zone of magnetite-dominated vein fill with sparse to absent copper, and into a magnetite-dominated, copper-bearing portion of the vein. Copper is best developed at intermediate to shallow levels in association with the hematite-dominated portions of the system. More distal, carbonate dominated facies with minor hematite and chalcopyrite are also present. Shallow levels of the vein system may be characterized by a low-sulfur style of advanced argillic alteration, that may be stratabound, in discordant breccia bodies, or structurally controlled on faults. The assemblages differ from other ore forming environments by their lack of sulfide and/or sulfate minerals, and the abundance of hypogene iron oxide phases (hematite and/or magnetite). Vein systems are dominated by brecciation events that record repeated, cyclic pulses of mineralizing fluids. Stable and radiogenic isotopic analyses, combined with fluid inclusion and mineral phase equilibria indicate the fluids were hypersaline brines (generally >40 wt% NaCl(eq)) over a temperature range of 200º-450ºC. The shallow formation, structural styles, repeated mineralization events, and size of the IOCG vein systems have many parallels to the classic precious-metal rich Ag-Au epithermal systems. Nonetheless, the two types of veins differ in their geochemistry, reflecting the large differences in fluid salinities, commonly <10 wt% NaCl(eq) in epithermal settings as compared to 15 to > 50 wt% NaCl(eq) in IOCG systems.

Sedimentary deposits have been broadly used to constrain past climate change and tectonic histories within mountain belts. This dissertation summarizes three studies that evaluate the effects of climate change and tectonics on sedimentary basin development. (1) The paleoslope estimation method, a method for calculating the threshold slope of a fluvial deposit, does not account for the stochastic variations in water depth in alluvial channels caused by climatic and autogenic processes. Therefore, we test the robustness of applying the paleoslope estimation method in a tectonic context. Based on our numerical modeling results, we conclude that if given sufficient time gravel can prograde long distances at regional slopes less than the minimum transport slope calculated with the paleoslope estimation method if water depth varies stochastically in time, and thus, caution should be exercised when evaluating regional slopes measured from the rock record in a tectonic context. (2) The role of crustal thickening, lithospheric removal, and climate change in driving surface uplift in the central Andes in southern Bolivia and changes in the creation of accommodation space and depositional facies in the adjacent foreland basin has been a topic of debate over the last decade. Our numerical modeling results show that gradual rise of the Eastern Cordillera above 2-3 km prior to 22 Ma leads to sufficient sediment accommodation for the Oligocene-Miocene foreland basin stratigraphy, and thus, the Eastern Cordillera gained the majority of its modern elevation prior to 10 Ma. Also, we conclude that major changes in grain size and depositional rates are primarily controlled by mountain-belt migration (i.e., climate change and lithospheric removal are secondary mechanisms). (3) Existing equations for predicting the long-term bedload sediment flux in alluvial channels include mean discharge as a controlling variable but do not explicitly include variations in discharge through time. We develop an analytic equation for the long-term bedload sediment flux that incorporates both the mean and coefficient of variation of discharge. Our results show that although increasing aridity leads to an increase in large discharges with respect to small discharges, long-term bedload sediment transport rates decrease for both gravel and sand-bed rivers with increasing aridity.

In the Basin and Range province of southwestern North America, Oligocene and Miocene normal faults are superimposed upon the Late Cretaceous-early Tertiary magmatic arc. This study examines tilted fault blocks containing dismembered pieces of porphyry systems, including pieces below and peripheral to ore bodies, that are exposed at the modern surface. Features in the magmatic-hydrothermal porphyry systems are used to place constraints on the style of extension in Arizona, and reconstructions of extension are used to examine the deep and peripheral portions of porphyry systems to provide a more complete understanding of porphyry systems as a whole. The Eagle Pass, Tea Cup, and Sheep Mountain porphyry systems of Arizona are examined in this study. In all the study areas, previous interpretations of the style of extension involved strongly listric normal faults. However, similar amounts of tilting observed in hanging wall and footwall rocks, as well as structure contour maps of fault planes, require that down dip curvature on faults was minimal (<1°/km. Instead, extension is shown here to have occurred as sets of nearly planar, "domino-style" normal faults were superimposed upon one another, including in the Pinaleño metamorphic core complex. Reconstructions of Tertiary extension reveal that sodic (-calcic) alteration is occurs 2-4 km peripheral to, and greisen alteration is found structurally below and overlapping with, potassic alteration. In addition, a preliminary reconstruction of extension across the Laramide magmatic arc reveals that the geometry, as revealed by known porphyry systems, is of similar scale to that of other magmatic arcs. These results help further the debate surrounding competing models of continental extension, and combine with previous work to provide a more complete understanding of the geometries of Arizona porphyry systems at the district and arc scale.

Lead and strontium isotopes are two powerful tracers that can be used to identify or constrain the provenance of a wide range of archaeological materials, but these two isotopic tracers have been rarely employed to infer the sources of artifacts in the southwestern USA. This dissertation contains four studies that demonstrate how these isotopic systems can address questions about the sources of three types of archaeological materials found in this region: turquoise, lead-based glaze-paints, and metals. The analysis of 116 samples of turquoise from 17 deposits in the southwestern USA reveals that lead and strontium isotopes are robust and sensitive tracers of turquoise at multiple scales. Isotopic variation among turquoise deposits correlates with broad regional differences in the geologic and tectonic setting of the rocks and mineral deposits which host turquoise mineralization. Many turquoise deposits also have unique isotopic signatures that will enable insights into ancient patterns of turquoise acquisition at regional and local levels. To show the utility of these tracers when applied to archaeological turquoise, I use lead and strontium isotopic measurements to establish that the Silver Bell Mountains are the likely source turquoise found at the Redtail site in the Tucson Basin, Arizona, USA. This dissertation also contains new, high-precision isotopic ratios of lead ores (galena and cerrusite) from four mining districts in New Mexico, including the Cerrillos Hills. All districts studied are possible sources of lead used by Pueblo IV communities to produce glaze paints. These new measurements, made by multiple-collector ICP-MS, define the isotopic composition of the ore deposits with greater precision and accuracy than achieved in previous studies, indicating an opportunity to improve interpretations about the provenance of lead in glaze paints. Lead isotopes are also found to be useful tools for identifying lead and copper metal associated with the 1540-1542 Vázquez de Coronado expedition. Lead shot and copper crossbow boltheads from two sites with archaeological evidence for the expedition's presence were determined to share similar or identical lead isotopic ratios. I propose this specific isotopic "fingerprint" can be used to identify other artifacts belonging to the expedition in the Southwest.

Geoscience attracts few African American and Hispanic/Latino students to the major and has historically not retained women at the same rate as men. Many factors have been proposed to explain these disparities but no quantitative study addressed geoscience diversity at the undergraduate level. To examine potential barriers to recruitment and retention, we interviewed geoscience majors from two large public universities in the U.S. and gathered 'critical incidents,' or life experiences that affected choice of a geoscience major. Critical incidents were classified by time period (when they occurred), grouped by outcome, sorted into categories, and compared by race/ethnicity and gender. Three manuscripts -- each involving different analyses of the critical incident dataset -- comprise this dissertation. Among many findings, our study showed that that white, Hispanic/Latino, and African American students reported different types of experiences affecting major choice while growing up. For instance, 81% of white students reported outdoor experiences (e.g., camping, hiking) as children, whereas Hispanics (33%) and African Americans (22%) reported significantly fewer outdoor experiences from the same time period. Men and women geoscience majors also reported differences. In one example, men (92%) reported at least one positive experience involving career and economics factors; far fewer women (50%) reported the same. Our results can inform recruiting and retention practices. Geoscience programs can provide field trips for all prospective majors, target on-campus advertising towards diverse student groups, meet with academic advisors of incoming freshmen to encourage African American and Hispanic students to enroll in introductory geology courses, and provide major and career information to parents of prospective majors. To better recruit and retain women, geoscience programs can emphasize other, non-economic factors when advertising the degree, promoting internships, and developing field and academic experiences.

This dissertation is focused on the design of the Open Data Repository's Data Publisher (ODR), a web-based central repository for scientific data, primarily focused on mineralogical properties, but also applicable to other data types, including for instance, morphological, textural and contextual images, chemical, biochemical, isotopic, and sequencing information. Using simple web-based tools, the goal of ODR is to lower the cost and training barrier so that any researcher can easily publish their data, ensure that it is archived for posterity, and comply with the mandates for data sharing. There are only a few databases in the mineralogical community, including RRUFF (http://rruff.info) for professionals, and mindat.org (http://www.mindat.org) for amateurs. These databases contain certain specific mineral information, but none, however, provide the ability to include, in the same platform, any of the many datatypes that characterize the properties of minerals. The ODR framework provides the flexibility required to include unforeseen data without the need for additional software programming. Once ODR is completed, the RRUFF database will be migrated into ODR and populated with additional data using other analytical techniques, such as Mössbauer data from Dr. Richard Morris and NVIR data from Dr. Ralf Milliken. The current ODR pilot studies are also described here, including 1) a database of the XRD analysis performed by the CheMin instrument on the Mars Science Laboratory rover Curiosity, 2) the NASA-AMES Astrobiology Habitable Environments Database (AHED), which aims to provide a central, high quality, long-term data repository for relevant astrobiology information, 3) the University of Arizona Mineral Museum (UAMM), with over 21,000 records of minerals and fossils from the museum collection, and 4) the Mineral Evolution Database (MED), that uses the ages of mineral species and their localities to correlate the diversification of mineral species through time with Earth's physical, chemical and biological processes. A good database design requires understanding the fundamentals of its content, so part of this thesis is also focused on developing my skills in mineral analysis and characterization, through the study of the crystal-chemistry of diverse minerals using X-ray diffraction, Raman spectroscopy and microprobe analysis, as principal techniques.

Visualization of digital geographic data is often accomplished through custom symbology that is saved in a proprietary format called a layer file (.lyr). The sharing of free geographical information system (GIS) data can be limited as the symbology data is bound inthe .lyr file format. This makes it harder and more tedious to work with open software tools since it is not possible to convert or open the .lyr file in free and open GIS software and thus limits the distribution of free GIS data. The aim of this thesis is to increase the interoperability of .lyr data between proprietary and free and open GIS software. This was done by revers eengineering the .lyr file format to document the file structure and to distribute the knowledge and metadata gained from this project to the open source community. Reverse engineering the.lyr format provided a well needed metadata and documentation about the format which increases the interoperability and enable future work to continue to lessen the gap between open source and commercial software. This groundwork can therefore, enable a continued development of data interoperability between proprietary and free and open GIS software.

The two end-member concept of mantle plume-driven versus far field stress-driven continental rifting anticipates high volumes of magma emplaced close to the rift-initiating plume, whereas relatively low magmatic volumes are predicted at large distances from the plume where the rifting is thought to be driven by far field stresses. We test this concept at the Guinea Plateau, which represents the last area of separation between Africa and South America, by investigating for rift-related volumes of magmatism using borehole, 3D seismic, and gravity data to run structural 3D inversions in two different data areas. Despite our interpretation of igneous rocks spanning large areas of continental shelf covered by the available seismic surveys, the calculated volumes in the Guinea Plateau barely match the magmatic volumes of other magma-poor margins and thus endorse the aforementioned concept. While the volcanic units on the shelf seem to be characterized more dominantly by horizontally deposited extrusive volcanic flows distributed over larger areas, numerous paleo-seamounts pierce complexly deformed pre and syn-rift sedimentary units on the slope. As non-uniqueness is an omnipresent issue when using potential field data to model geologic features, our method faced some challenges in the areas exhibiting complicated geology. In this situation less rigid constraints were applied in the modeling process. The misfit issues were successfully addressed by filtering the frequency content of the gravity data according to the depth of the investigated geology. In this work, we classify and compare our volume estimates for rift-related magmatism between the Guinea Fracture Zone (FZ) and the Saint Paul's FZ while presenting the refinements applied to our modeling technique.

A presente pesquisa discute os trabalhos de campo da semana de recepção de calouros, no Instituto de Geociências da USP, em dois momentos. O primeiro entre os anos de 1978 e 1982 organizados pelos alunos do bacharelado em Geologia, integrantes do Centro Paulista de Estudos Geológicos CEPEGE. O segundo momento para os alunos do curso de Licenciatura em Geociências e Educação Ambiental LiGEA, entre os anos de 2005 a 2012. O principal objetivo deste trabalho é compreender como estas atividades contribuíram e continuam contribuindo com o processo de institucionalização da área de Pesquisa e Ensino em Geociências. Institucionalização é compreendida por nós não só como a criação de uma estrutura física, com normas, regulamentos, leis e estatuto, mas sim em um sentido mais amplo, incluindo, também, comportamentos que materializam valores em um determinado grupo social. Ao longo da pesquisa percebemos que estas atividades introdutórias, cada uma em seu contexto, estão impregnadas de valores e concepções metodológicas, pedagógicas e científicas. Para realizarmos a análise segundo estas dimensões, utilizamos diversas técnicas de coleta de dados como entrevistas, observação participante, anotações e pesquisa em arquivo documental. Assim, procuramos compreender a forma como estes trabalhos de campo foram organizados, utilizando um olhar multidimensional, compreendendo os contextos históricos e concepções educacionais, relacionando com discussões epistemológicas da área. A metodologia de análise de dados foi a Análise Textual Discursiva. Foi possível observar que os trabalhos de campo, tanto do CEPEGE, como da LiGEA, refletem aspectos pedagógicos, processuais de institucionalização e de formação científica, subjetiva e afetiva dos participantes. / This study discusses the field work for the week of receiption of freshmen at the Geosciences Institute of USP, on two occasions. The first between 1978 and 1982 organized by the students of the bachelor\'s degree in geology, members of the Central Geological Survey Paulista - CEPEGE. The second moment for the students of the Bachelor\'s Degree in Geosciences and Environmental Education - LiGEA, between the years 2005 to 2012. The main objective of this study is to understand how these activities contributed and still contribute to the process of institutionalization of the area of Research and Education in Geosciences. Institutionalization is understood by us as not only the creation of a physical structure, with rules, regulations, laws and statutes, but in a broader sense, including also behaviors that embody values in a particular social group. During the research we realized that these introductory activities, each in its context, are imbued with values and methodological conceptions, educational and scientific. To carry out the analysis along these dimensions we use various techniques of data collection such as interviews, participant observation, research notes and document archive. So we try to understand how this field works were organized, using a multidimensional look, understanding the historical contexts and educational concepts, epistemological discussions relating to the area. The methodology of data analysis was the Textual Discourse Analysis. It was observed that the field work, both CEPEGE as the LiGEA reflect pedagogical aspects, procedural institutionalization and scientific training, participants\' subjective and emotional.