No description available.

No description available.

Development of homes, roads, and commercial buildings in northern Utah has grown significantly during the last several decades. Construction has expanded from the valley floor to higher elevations of benches, foothills, and other elevated regions of the Wasatch Mountain Front. Construction in the higher elevation areas are a concern due to potential for landslides, both new and reactivated. Landslides have been identified in this region and are dated as Pleistocene to historical in age. A possible landslide of about 0.5 km2 on the south slope of Traverse Mountain has been mapped by the Utah Geological Survey in 2005. Its surface exhibits hummocky topography and is comprised of Oligocene-age volcanic ash, block and ash flow tuffs, and andesite lava. Landslides along the Wasatch Mountain Front are complex features usually characterized by dense vegetation and poor outcrop and require a combination geological and geophysical methods to study their thickness, slope, lateral extent, and style of emplacement. Our study incorporates trenching, boreholes, and LiDAR aerial imagery. Unique to the study of landslides is our use of seismic reflection with a vibroseis source over the mapped landslide deposit. The seismic parameters of source, station spacing, and processing method provide a coherent, albeit low-resolution, image of the upper 500 m of the subsurface beneath the landslide. A major reflector boundary in our seismic profiles has an apparent dip of 4° to the south, approximately parallel with the surface topography. Its elevation and seismic character are indicative of a contact between the Oligocene-age volcanic rocks on top of a portion of the Pennsylvanian-age Bingham Mine Formation, a mixed carbonate and siliciclastic sequence. The reflector defines an asymmetric graben-like structure bounded by a north-northwest-trending normal fault system. Analysis of trenches, boreholes and local geology reveals a faulted, chaotic body of block and ash flow tuffs, surrounded by andesite lavas. Using LiDAR and surface geological reconnaissance, a possible toe or margin of a landslide has been interpreted in the north-west portion of the study area. The combination weakened block and ash flow tuffs and abundant clay production from this unit contribute to the likelihood of a coalescence of landslides in this mapped landslide area. The integration of LiDAR, trenching, boreholes and reflection seismology provides the range and resolution of data needed to assess the complex geology of landslides.

The Late Cretaceous–early Paleogene is the most recent period of Earth history with a dynamic carbon cycle that experienced sustained global greenhouse warmth and can offer a valuable insight into our anthropogenically-warmer future world. Yet, knowledge of ambient climate conditions and evolution of the carbon cycle at this time, along with their relation to forcing mechanisms, are still poorly constrained. In this thesis, I examine marine sediments recovered from the South Atlantic Walvis Ridge (ODP Site 1262) and Indian Ocean Ninetyeast Ridge (IODP Site U1443 and ODP Site 758), to shed new light on the evolution of the climate and carbon cycle from the Late Maastrichtian through to the Early Eocene (~67.10–52.35 Ma). The overarching aims of this thesis are: 1) to identify the long-term trends and principle forcing mechanisms driving the climate and carbon cycle during this time period, through construction of 14.75 million-year-long, orbital-resolution (~1.5–4 kyr), stratigraphically complete, benthic stable carbon (δ13Cbenthic) and oxygen (δ18Obenthic) isotope records; 2) to investigate in more detail the climatic and carbon-cycle perturbations of the Early–Middle Paleocene (e.g., the Dan-C2 event, Latest Danian Event and the Danian/Selandian Transition Event) and place these in their proper (orbital) temporal context; 3) to investigate the Late Maastrichtian warming event and its relationship to the eruption of the Deccan Traps Large Igneous Province, as well as its role (if any) in the subsequent Cretaceous/Paleogene (K/Pg) mass extinction; 4) to provide the first orbital-resolution estimates of temperature and carbonate chemistry variability from the low latitude Indian Ocean spanning the Late Paleocene–Early Eocene, through analysis of trace element and stable isotope data from multiple foraminiferal species. Taken together, the results presented in this thesis provide a critical new insight into the dynamic evolution of the climate and carbon cycle during the greenhouse world of the early Paleogene, and shed light on the potential forcing mechanisms driving the climate and carbon cycle during this time.

No description available.

The geology, petrology and geochemistry of Catface porphyry Cu (Mo-Au) deposit, located on the west coast of Vancouver Island are examined in detail. Detailed core logging and sampling was carried out to characterize the geometry and identity of different intrusive phases and alteration styles prevalent during the emplacement and formation of the deposit, as well as their geochemical affinity. Early- and late-stage potassic alteration is identified, as well as main-stage sodic-calcic and calcic-sodic alteration. Four distinct Paleogene intrusive phases vary from quartz diorite to granodiorite in composition. The rocks are broadly calc-alkaline, weakly peraluminous to moderately metaluminous, and have typical arc geochemical affinity. The timing of emplacement and mineralization is constrained by U-Pb and Re-Os geochronology at 40.4-41.4 Ma and 40.9 ±0.2 Ma, respectively. All four Paleogene Catface intrusive phases were emplaced close in time with a direct temporal correlation to mineralization. The chalcopyrite- and pyrite-bearing miarolitic cavities in the Halo Porphyry intrusive, combined with U-Pb and Re-Os dates suggest this intrusive phase is the most likely source of mineralizing fluids. The intrusions were emplaced at depths of less four kilometers in the crust, as evidenced by the presence of miarolitic cavities and confirmed through amphibole-plagioclase thermobarometry, which record conditions of 615–700 °C and <200 MPa. The lack of primary anhydrite and hematite, and the presence of pyrrhotite in the ore system indicate a reduced magmatic-hydrothermal event. The SO3 contents in apatites are <450 ppm, indicative of a degassed and/or sulphate-free (reduced) magma. The assemblage K-feldspar-quartz-biotite-ilmenite yields oxygen fugacities (fO2) which are 0.5 to 3.0 log units below the quartz-fayalite-magnetite (QFM) buffer at an assumed pressure of 300 MPa; orders of magnitude more reduced than typical porphyry deposits. Parental magmas to the Catface deposit were either derived from intrinsically-reduced mantle, or more typical oxidized arc magma that was subsequently reduced during ascent and emplacement. Further isotopic work is required to determine which process contributed to the reduction of these magmas in an arc setting. Nevertheless, recognition of reduced porphyry-related magmatism on west-central Vancouver Island is of similar age to that of North Fork (~36.8-38.9 Ma) deposit in Washington suggesting a consanguinity of reduced magmatism with the Paleogene Cascade arc. / Graduate

The thesis presents observations on the CO2 concentration and carbon isotopes in air CO2 (δ13C) to constrain the inter-annual variability of carbon inventory over the Southern Ocean between the years 2011-2013. Based on the observation, the region of CO2 venting was identified over the Southern Ocean. Further, isotopic characterization allowed inferring about the possible sources of CO2 degassing and contribution from the dissolved inorganic carbon (DIC) that exsolved to generate CO2. It is concluded that the origin CO2 is mainly from the degassing of CO2 available from the dissociation of DIC or organic degradation. Live Foraminiferal samples of Globigerina bulloides from towing were captured, separated and analysed for δ18O and δ13C from various locations across the Southern Ocean between 10°N−60°S. A large similarities in the estimated values (deduced from simultaneous composition of ocean water 18O, δ13C in DIC and temperature i.e. SST under equilibrium condition) and measured δ18O and δ13C values were observed until 40°S from the equator, and hence it was concluded that the calcification depth of G. bulloides is confined to a depth of ~75-200m till 40°S latitude. However, further south (>40oS) disequilibrium from the estimates was detected. A number of possible reasons were cited for the observed disequilibrium such as (1) Deeper depth habitat (2) Partial dissolution (3) Non-equilibrium calcification (4) Oceanic Suess Effect and (5) Genetic Variability. A box model of isotopic mass balance was presented in this study to explain the pattern of enrichment in the 13C values of sea water DIC with latitude (up to about 43°S). The model shows that a steady state of the carbon isotope ratio of water is achieved in a relatively short time of ~5000 days. Rainwater isotope in the open marine condition across the latitudinal transects over Southern Ocean marking zone of precipitation and evaporation is another element of this thesis. A variation with excess lighter isotopes in rainwater was observed in high latitude rain in this study. Observed isotopic depletion is attributed to rainout process over the ocean. The average rainout fraction over the Southern Ocean in the region of zone of precipitation is ~44%, while it drops to ~25% in the zone of evaporation. Second part of the thesis presents a novel method of isotope thermometry which is called “clumped isotope (13C18O16O16O-2 in the calcite structure) thermometry”. A revision in the thermometry equation relating 47 vs T in synthetic carbonates precipitates and otoliths was proposed. The revised calibration was used on fish otoliths from the modern and past environment to estimate the temperatures. Together with the clumped isotope, conventional stable isotopes in the shell carbonates were measured to effectively reconstruct the seasonal fresh water fraction at seasonal time scales.

La séquence sédimentaire du Dur At-Talah, située dans la partie sud du bassin de Syrte au centre de la Libye, est composée de 150 m d'épaisseur de roches principalement siliciclastiques (grès, siltites et argiles). L'importance de cette séquence est liée en partie à l'importance du bassin de Sirt qui est un des plus grands réservoirs d'hydrocarbures de Libye. La séquence est également un des plus important site de fossiles de vertébrés de l’Eocène supérieur, l'âge de la séquence. Les études antérieures, bien que très limitées par rapport à l'importance de cette zone, se sont concentrées principalement sur le contenu paléontologique de la séquence. L’étude sédimentologique n’avait été jusqu’à ce jour que très peu abordée. Cette thèse est un travail basé sur l’examen des affleurements et où l'accent est mis sur les structures sédimentaires et biogéniques (traces fossiles), visant à définir et à interpréter les faciès sédimentaires qui ont construit la séquence du Dur At Talah. L’ étude de la séquence a conduit à diviser la totalité de l’affleurement en trois intervalles génétiquement liés. Le plus ancien que nous avons appelé la « New Idam Unit » (environ 80 m d’épaisseur), est composé de grès très fins, de siltites et d’argiles. Cette unité (New Idam Unit) est recouverte en discordance par la « Sarir Unit » (environ 50 m d’épaisseur), composée de grès fins à moyens à faisceaux de litages entrecroisées dans sa partie inférieure (environ 25-30 m d’épaisseur) et de grès grossiers à microconglomératiques dans sa partie supérieure (environ 20-30 m d’épaisseur). La « Sarir Unit » est ainsi divisée en « Sarir inférieur » et « Sarir supérieur ». La « New Idam Unit » présente des dépôts qui sont attribués à un milieu main estuarien. La série débute par des dépôts d’environ 35 m d’épaisseur typiques d’un estuaire externe. Les 45 mètres qui lui font suite passent progressivement à des dépôts tidaux caractéristiques d’un estuaire interne. La Surface d'inondation maximale se situe entre les deux intervalles. Au-dessus de cette surface les indicateurs fluviaux augmentent et les indicateurs de marées diminuent progressivement, offrant ainsi un indice pour la migration de la rive de rivage vers le bassin (vers le Nord). La sous-unité du Sarir inférieur qui avait été interprétée avant ce travail comme dépôts fluviatiles, préserve pourtant des structures sédimentaires multi-échelles qui sont le résultat incontestable de processus de marée. Ceci est particulièrement évident dans la partie inférieure de l’unité « Sarir inférieur » (la Lower Lower Sarir Unit ; LLS). Dans la partie supérieure de l’unité Sarir inférieur (Upper Lower Sarir; ULS), les indicateurs de dynamique fluviale dominent largement sur ceux de la marée. Le Sarir inférieur est donc interprété comme un système deltaique mis en place lors d’une régression normale. Cette fois-ci, la surface maximale d'inondation se situe entre le LLS et ULS. Le « Upper Lower Sarir » (ULS) se terminée par une discordance subaérienne, avec de nombreuses traces d’émersion conservées au sommet de l'ULS. Celles-ci sont recoupées par le « Upper Sarir » qui montre des marqueurs fiables d'environnement de dépôt strictement fluvials. Les dépôts du « Upper Sarir » enregistre la séquence de bas niveau marin. Cette étude fournit des informations précieuses concernant le dépôt des séquences dans le bassin de Syrte au cours de la fin de l'Éocène. Elle fournit également une étude originale sur la dynamique tidale dans des milieux marins margino-littoraux. / Dur At Talah sedimentary sequence, located at the southern side of the Sirt Basin in central Libya, is composed of 150 m thick of mainly siliciclastic rocks. The importance of this sequence is linked to the importance of the Sirt Basin as one of large hydrocarbon reservoirs in Libya. The sequence is also an excellent site for vertebrate fossils of Late Eocene, the age of the sequence. Previous studies, though very limited compared to the importance of this area, are focused on its paleontological content. Sedimentology received only scant attention before this project. This thesis is an outcrop based study in which the focus is given to the sedimentary and biogenic (trace fossils) structures, aiming at defining and interpreting depositional facies which building up the sequence. The study is mainly based on field data which are analyzed on the light of related published literature and on the comparison with modern sedimentary environments. Results of facies analysis have led to splitting the entire sequence into three genetically related intervals. The oldest, we called the New Idam Unit (around 80m), is composed of very fine sandstones to mudstones. New Idam Unit is unconformably overlain by the Sarir Unit (around 50m), composed of medium grained cross bedded sandstones (the lower 25-30 m) changes up to very coarse and microconglomeratic sandstone (the upper 20-30 m). Thus, the Sarir Unit is split into the lower Sarir Subunit and upper Sarir subunit. The New Idam Unit presents both classical and unusual sedimentary and biogenic indicators that attribute this unit to estuarine depositional environment. It starts with outer estuarine (the lower 35 m) and ends up with inner estuarine (the upper 45 m). Maximum flooding surface is located in between. Above this surface the fluvial indicators increase and tidal indicators decrease, thus providing clue for basinward (North) migration of the shoreline. The lower Sarir subunit which was previously interpreted as fluvial deposits, preserves multi-scale sedimentary structures that undoubtedly belong to tidal processes. This is especially evidenced at the lower part of the lower Sarir Subunit (LLS). Fluvial indications over dominates the tidal ones in the upper part of the lower Sarir (ULS). Due to this configuration the whole lower Sarir subunit is interpreted as shallow marine, deltaic, depositional system, occurred during sea level ¨normal¨ regression. This time, maximum flooding surface is located between the LLS and ULS. The lower Sarir subunit is terminated by subaerial unconformity, with evidences of subaerial exposure preserved at the top of the ULS. These are intruded by the upper Sarir subunit which presents clear evidences of strictly fluvial environment of deposition. The deposits of the upper Sarir subunit record the low stand system tract part of the Dur At Talah sequence. In addition to the outlined results, the sequential pattern of the depositional events is suggested for the entire sequence of Dur At Talah. This study provides a valuable information regarding the depositional and sequential aspects of the Sirt Basin during the late Eocene, it also provide an unique case study for the better understanding of the shallow marine tidal deposits.

The Paleocene-Eocene Thermal Maximum (PETM) (55 million years ago) stands as the largest in a series of extreme warming (hyperthermal) climatic events, which are analogous to the modern day increase in greenhouse gas concentrations. Orbitally triggered (Lourens et al., 2005, Galeotti et al., 2010), the PETM is marked by a large (-3‰) carbon isotope excursion (CIE). Hypothesized to be methane driven, Zeebe et al., (2009) noted that a methane based release would only account for 3.5°C of warming. An isotopically heavier carbon, such as that of soil and C3 plants, has the potential to account for the warming and CIE (Zachos et al., 2005). During the early Eocene, high latitude surface temperatures created favorable conditions for the sequestration of terrestrial carbon. A large untapped terrestrial carbon reservoir, such as that within permafrost regions, contains the potential, if degraded, to account for the CIE as well as the global temperature increase observed during the PETM. Using an fully integrated climate model (GENESIS) with fully coupled vegetation model (BIOME4), we show that adequate conditions for permafrost growth and terrestrial carbon sequestration did exist during the lead up to the PETM. By calculating the flux of net primary production (NPP) and soil respiration (Rs), we demonstrate that the biodegradation of permafrost-based carbon reservoirs had the potential to drive the PETM. Furthermore, we show that the natural planetary response to unbalanced carbon reservoirs resulted in the terrestrial sequestration of atmospheric carbon via permafrost regeneration, yielding a vulnerable carbon reservoir for the subsequent hyperthermal.

The Simpson Mountains have long been of economic interest and have renewed interest in their potential value. Field mapping of the project area redefined structural relationships between stratigraphic units. Geometric and kinematic analysis of structures in the Simpson Mountains show the range is deformed by the three most recent tectonic events: the Sevier Orogeny, the Laramide Orogeny, and Basin and Range Extension. Laramide structures define the range with a significant E-W normal fault and an E-W thrust fault, which are both likely related to Eocene-age igneous intrusions. Principal component analysis (PCA) of regional quartzite X-ray Fluorescence (XRF) data resulted in distinctive populations between the Eureka Quartzite and the Mutual and Prospect Mountain Quartzites. The PCA was paired with petrographic analysis of regional quartzites where samples were diagnostically classified to help validate the PCA results. XRF analysis of volcanic rocks show volcanic arc origin. 40Ar/39Ar dating of the volcanic rocks associated with the intrusions yield new ages of 34.09±0.10 to 37.05±0.06 Ma and 19.11±0.02 to 19.18±0.03. Lithostratigraphy of the map area was validated by identification of fossil samples. The Eocene intrusions are likely sources of mineralization in the range along older Sevier structures.