Strain distribution across broad plate boundaries is inadequately understood. California's Mojave Desert has been adjacent to Tertiary convergent and transform plate margins and its general geology is fairly well known, making it an excellent location for crustal motion studies. Models for the Cenozoic history of the Mojave Desert predict crustal motions, but paleomagnetism is the primary method for quantifying such motions. The Barstow, California area has good exposure of appropriate rocks ranging from Oligocene-earliest Miocene to Pliocene in age. Standard paleomagnetic sampling and analysis of these volcanic units yielded primary paleomagnetic directions, which spatially and temporally constrain crustal motions in the Barstow area. Observed magnetic directions were compared with expected directions for cratonic North America allowing determination of crustal rotations and translations. Paleomagnetic directions from the Lane Mountain Quartz Latites and Jackhammer Formation suggest 55$\sp\circ$ to 75$\sp\circ$ of clockwise rotation of the Barstow area in earliest Miocene time which may be related to oroclinal bending of the southern Sierra Nevada batholith. These units may also record a geomagnetic reversal. Twenty-three degrees of counterclockwise rotation of the Pickhandle Formation coincides with early Miocene northeast-southwest extension and detachment faulting in the Mojave Desert. Other parts of the desert experienced variable senses and amounts of rotation concurrently. Drag along transfer zones or detachment surface geometry appear to have caused upper plate rotations in the extended terranes, while the lower plates remained unrotated. These results suggest that extension in the Mojave Desert is related to similarly oriented Miocene extension in adjacent areas. This study, like most paleomagnetic work in the western and central Mojave Desert, shows no evidence for post-18 Ma rotation, suggesting that post-10 Ma right-lateral faulting there has produced relatively little crustal deformation. The exception to this generalization is the northeast corner of the Mojave Desert which underwent about 28$\sp\circ$ of post-18 Ma clockwise rotation. This enigmatic and structurally different northeastern area has apparently experienced atypical post-middle Miocene activity. Paleomagnetic flattening data and structural constraints indicate that post-Oligocene north-south translation of crustal blocks in the Mojave Desert has been insignificant.

<p> The fluvial and deltaic Wilcox Group is a major target for hydrocarbon and coal exploration in northern and central Louisiana. However, the characterization and delineation of fluvial systems is a difficult task due to the variability and complexity of fluvial systems and their internal heterogeneities. </p><p> Seismic geomorphology is studied by recognizing paleogeographic features in seismic stratal slices, which are seismic images of paleo-depositional surfaces. Seismic attributes, which are extracted along seismic stratal slices, can reveal information that is not readily apparent in raw seismic data. The existence and distribution of fluvial channels are recognized by the channel geomorphology in seismic attributes displayed on stratal slices. The lithologies in the channels are indicated by those seismic attributes that are directly related to the physical properties of rocks. Selected attributes utilized herein include similarity, spectral decomposition, sweetness, relative acoustic impedance, root mean square (RMS) amplitude, and curvature. Co-rendering and Red/Green/Blue (RGB) display techniques are also included to better illuminate the channel geometry and lithology distribution. Hydrocarbons may exist in the channel sand-bodies, but are not explicitly identified herein. Future drilling plans for oil and gas exploration may benefit from the identification of the channels and the lithologies that fill them.</p>

<p> The purpose of this study was to identify the geologic signature of paleostorm events within the mid-continent region. This research aimed to create a better understanding of the long-term geologic history of major storms and to allow for better-informed projections regarding future return periods for such storms. The study locations were Cheyenne Bottoms Wildlife Refuge, Kansas and Canton Lake, Oklahoma. To determine the geologic signature of major storms, sediment cores were taken at both locations and sampled at high resolution (3 mm) intervals for grain size analysis using a Cilas laser particle size analyzer. Downcore chronology was determined through Pb-210, Cs-137 and C-14 dating methods. Using a recent known major storm occurrence at Canton Lake, the signature created by storms in the geologic record was identified. The resulting signature was then used to identify paleostorms in the longer-term record in the Cheyenne Bottoms core. The results were also used to determine storm/climate cycles in the long-term geologic record, and to calculate true return periods for major storms. A better understanding of true return periods and possible increases in frequency or intensity of large storms is essential in the effort to mitigate future damage to infrastructure and loss of human life</p>

<p> Faults are an important element of reservoir characterization because they have the potential to compartmentalize a reservoir and create associated fractures that can profoundly influence fluid flow in the reservoir. This investigation describes details of the fault regime in a portion of the Wattenberg Field, Colorado. For the purposes of this study, seismic-scale faults are interpreted as horizons with displacements. Seismic-scale fractures are interpreted as linear amplitude discontinuities. Borehole image log scale faults show displacement. Borehole image log scale fractures do not show displacement. Both borehole image log scale faults and fractures are interpreted as seismic-scale fractures. </p><p> Faults were discovered by interpreting inflection points in cumulative dip plots and azimuth walkout plots derived from a borehole image log in a vertical well. On the image log fractures are consistently found in both the Niobrara chalk and marl benches. The individual benches are not resolvable at the scale of the seismic data, but evidence that faults are present in both the chalks and marls lends credence to the potential that seismic data may be able to predict fracture zones either directly or indirectly. </p><p> The hypothesis is tested on a 50 square mile 3D seismic survey. Generally, faults present in the Niobrara Formation in the survey are planar, normal faults that range up to two miles in length. Over 150 faults were picked. Rose diagrams illustrate a predominant strike direction of N 20 E. A predictive fracture volume was generated utilizing CGG&rsquo;s proprietary software: InsightEarth&trade;. The algorithm generates this volume statistically based on fault geometry. Each seismic-scale fault indicates a high potential for fracture swarms in the nearby vicinity. Fracture prediction can assist future exploration and development in the Niobrara resource play.</p>

<p> Peatlands act as carbon sinks while representing major sources of biogenic gases such as methane (CH4) and carbon dioxide (CO2), two potent greenhouse gases. Gas production and release in these peats soils are also influenced by overall warm temperatures and water table fluctuations due to the naturally shallow water table in the Florida Everglades. Releases of biogenic gases from Florida Everglades peat soils are not well understood and the temporal distribution and dynamics are uncertain. The general objective of this work was geared towards a methodological approach which aimed to examine the feasibility of capacitance moisture probes to investigate biogenic gas dynamics in various Florida Everglades peat soils at high temporal resolution. This work has implications for establishing capacitance moisture probes as a method to monitor gas dynamics in peat soils at high temporal resolution and better understanding patterns of gas build-up and release from peat soils in the Everglades. </p>

<p> The Hueco and Mesilla Bolsons are part of the intramountain basins of the Rio Grande Rift system. These bolsons are the primary source of groundwater for the El Paso-Ciudad Juarez metropolitan area and contain faults that show evidence of repeated earthquakes during the Quaternary. The region is also associated with has low-level (M&lt;4) seismicity. The collection and analysis of precision gravity data, coupled with information from water wells, multichannel analysis of surface waves (MASW) studies and previously published seismic reflection lines, have been used to examine the structure and faulting within these bolson. This study reveals that the Hueco and Mesilla Bolsons are very different structurally. The southern Mesilla Bolson contains about 500 m of sediment. Faults are difficult to trace and have less than 50-100 m of displacement across them. The southernmost bolson contains numerous Tertiary intrusions and the thickness of Cretaceous bedrock appears to decrease from south to north, possibly delineating the edge of Laramide age deformation within the bolson. The northern Hueco Bolson contains 1800 to 2500 m of basin fill. Displacement along the East Franklin Mountains fault (EFMF), a fault with evidence for repeated earthquakes within the past 64,000 years, is about 1500 m, and displacement on intrabasin faults is 200-300 m. Several intrabasin faults appear to control the saline to freshwater contact within the bolson. The EFMF may extend over 30 km south of the end of its mapped trace at the end of the Franklin Mountains and a number of intrabasin faults also extend south into the urbanized regions of the study area. The EFMF and other basin structures appear to be offset or disrupted at the speculated edge of Laramide deformation that lies beneath the bolson. Horizontal Gradient Methods (HGM) were applied to the gravity data and were successful for tracing faults and older Laramide features within the Hueco Bolson beneath the urbanized regions of the cities. HGM were not as successful at tracing faults within the Mesilla Bolson, however they were helpful for tracing the subsurface extent of igneous intrusions including the Mt. Cristo Rey, River, Three Sisters, and the Westerner outcrops. Some of these features appear linked at depth by a series of dikes and faults. MASW data were used to determine the average shear wave velocity in the upper 30m (Vs 30) at &sim;70 sites within the Hueco Bolson. These observations were combined with similar data collected previously in Juarez to produce regional velocity and site classification maps. The results show low velocities are found close to the river within fluvial deposits with higher velocities close to the Franklin Mountains where bedrock is close to the surface and higher velocities in upland regions of northeast El Paso were soils appear to be more highly cemented. These data will be used in conjunction with information on bolson geometries to model the expected effects of strong ground motion from earthquakes in the El Paso-Ciudad Juarez region.</p>

<p> Cryoconite holes are vertical columns of meltwater within the shallow subsurface of glaciers. In the McMurdo Dry Valleys (MDV) of Antarctica cryoconite holes are a source of meltwater and harbor microbial communities in an otherwise arid environment with low biologic activity. The holes form as sediments on the ice surface, which are darker than the surrounding ice, are preferentially heated by solar radiation. The warm sediments melt the underlying ice and migrate downwards. An ice lid forms, isolating them from the below-freezing atmosphere enabling them to remain thawed. In this study, field observations, laboratory experiments, and numerical modeling are used to characterize the fundamental variables controlling cryoconite hole development. </p><p> Field and laboratory results show that solar radiation drives cryoconite hole melting by controlling the energy available to the cryoconite and to warm the surrounding ice. Holes deepen further in warmer ice. Laboratory results show that at temperatures of &ndash;10 &deg;C at least 405 (W m^&ndash;2) are needed to warm the cryoconite sufficiently to melt surrounding ice. Numerical modeling shows that increased radiation flux into the subsurface and warmer air temperatures cause cryoconite to descend deeper and the meltwater-filled holes to enlarge, while increased surface ablation decreases their average depth. Cryoconite holes thaw sooner and refreeze later when the optical properties of the ice facilitate greater radiation transmission. Cryoconite warms the ice significantly more than ice without cryoconite. Within the melt-filled hole, the heat capacity of the water keeps the surrounding ice warm for several weeks after the cryoconite-free ice has cooled. The cryoconite itself is last to completely freeze.</p><p>

<p> Located in LaSalle Parish, Louisiana, the area of interest for this study encompasses portions of the Tullos-Urania and Olla oil fields, with their hydrocarbon accumulation stemming from the Wilcox Group. The overall objective of this study is threefold; first, generate structure maps of the strata within this area of investigation and identify the productive formations. Second, utilize seismic modeling from local wells defining the most accurate resistivity-to-sonic transform. The last goal is to generate an accurate seismic-to-well tie employing the most accurate sonic log generated at the wells bounding the high-resolution shallow imaging seismic data. This study must use resistivity data to model sonic logs for the bounding wells which have no sonic logs available. The modeled sonic logs are then used to create time- depth relationships between the acquired seismic data and the wells bounding the seismic line. To use resistivity logs to model a sonic log, this study will compare three equations (Faust, 1953; Kim, 1964; Smiths, 1968) to determine their relative accuracies for a one-step resistivity-to-sonic transform. Accuracy is measured by the absolute average deviation of the modelled sonic data from the measured sonic data from wells within the study area, but distant from the seismic line, which have recorded sonic logs. The results of this study indicate that the one-step resistivity-to- sonic equation proposed by Faust (1953) generates the least amount of error when applied to the short resistivity curve. Throughout the modeled logs, the Faust (1953) equation generates an absolute average deviation of 6.0% for the short resistivity curves while Kim&rsquo;s (1964) and Smiths (1968) equations produce 9.7% and 12.8% absolute average deviation. By understanding the variability of these models, future studies can ascertain the best fit model for further investigation of shallow hydrocarbon bearing formations within, or similar to, the Paleocene-Eocene aged strata in Central Louisiana.</p><p>

<p> The upper Wilcox group in the Tullos-Urania oilfield has not been imaged with enough resolution for interpretation. Prior seismic data collected in the area was designed for formations much deeper than the Wilcox Group. The purpose of this investigation was to produce an image of the subsurface and identify formations of interest for production of oil and gas by applying different processing methods. With an optimal processing workflow and use of limited well logs, an interpretation of the data was provided to the oil company. </p><p> The advantage of using an accelerated weight-drop source is the shallow horizons, ranging from 1,500 to 3,000 feet in-depth, become distinct with higher resolution. The acquisition achieved a dominant frequency averaging around 45&ndash;65 Hz compared to a nearby pre-existing 3D survey volume with a dominant frequency range of 15&ndash;35 Hz. Refracted waves dominated the unprocessed shot records from this data. Consequently, the field records had a significantly low signal-noise ratio. Therefore, the most critical processing steps focused on signal processing and velocity analysis. Without enough ground roll and noise suppression, the velocity analysis would not have been coherent. Some obstacles faced with processing the data included a sparse horizontal sampling and a lack of velocity logs along the seismic line. </p><p> The results of this study included a set of stacked lines, velocity models, and an optimal processing workflow for future high-frequency shallow seismic exploration surveys in the vicinity of LaSalle, LA. These results have concluded seismic surveying with an accelerated weight-drop source is a cost-effective method to produce a high- resolution cross-section of the high and low-velocity sand and shale channels of the fluvial Wilcox strata of Northern Louisiana. Further research should look to build on these results and gather a 3D survey to image the structure of the Tullos-Urania oilfield and identify hydrocarbons-in-place. </p><p>

<p> This work investigates the lithospheric structure beneath the Mesozoic (~140 &ndash; ~110 Ma) Chilwa Alkaline Province (CAP) in southern Malawi and northeastern Mozambique using aeromagnetic and satellite gravity data (the World Gravity Model 2012 (WGM 2012). The CAP is a granite, syenite, nepheline syenite, and basanite province with minor intrusions of carbonatite bodies. It intrudes the Precambrian terranes of the Southern Irumide belt and the Unango complex. It is located on the northeastern margin of the Mesozoic Shire graben and on the southeastern edge of the Cenozoic Malawi rift, which is considered the southernmost segment of the Western Branch of the East African Rift System (EARS). Some of the CAP&rsquo;s intrusive bodies are clearly offset by the border normal faults of the Malawi rift. Previous petrographic, geochemical and isotopic studies have suggested that the CAP is underlain by a thinned sub-continental lithospheric mantle (SCLM) possibly due to the Mesozoic Karoo rifting event. Hence, mantle magmatic source has been favored as an origin for the CAP. However, melting of a thickened continental crust cannot be ruled out for the origin of the CAP as has been suggested for several other alkaline intrusions. In this study: (1) Edge enhancement of the aeromagnetic data showed the CAP to be defined by circular and overlapping magnetic anomalies typical of hypabyssal nested igneous ring complexes. (2) Three-dimensional (3D) Voxi modeling and magnetic susceptibility analysis of the aeromagnetic data covering selected CAP&rsquo;s intrusive bodies showed that these were emplaced at an average depth of ~ 4 km. (3) Upward continuation of the WGM 2012 Bouguer gravity anomalies suggested that the CAP was sourced from possibly deeper magma chambers now preserved as broad batholiths at ~4 km to~6 km depth. (4) Two-dimensional (2D) radially-averaged power spectral analysis of the WGM 2012 Bouguer gravity anomalies showed that the CAP is underlain by a thick crust (possibly due to mafic magmatic under-platting) where the Moho can be as deep as ~45 km. It also showed that the CAP is underlain by a relatively thin SCLM (possibly due to Mesozoic Karoo rift-related lithospheric stretching) where the asthenosphere-lithosphere boundary (LAB) can be as shallow as ~110 km. This work suggests that thinning of the SCLM might have allowed for the ascendance and decompression melting of the asthenosphere but also provided heat source (through mafic magmatic under-platting) to partially melt the lower crust to form the CAP from a mixed magma source and through caldera collapse mechanism. This model can be tested by additional geochemical and isotopic studies. This work highlights the importance of potential field data for imaging complex continental lithospheric structure. Understanding the lithospheric structure beneath the CAP is helpful in guiding future mineral exploration efforts because igneous ring complexes are important sites for the formation of economic mineralization zones.</p><p>