Browsing by Subject "Caves"
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Item Assessing the Impact of Groundwater Pollution from Marine Caves on Nearshore Seagrass Beds in Bermuda(2010-01-14) Cate, Jenipher R.This investigation characterized karstic and nearshore environments of Bermuda to describe 1) behavior and periodicity of cave springs; 2) submarine spring water quality; and 3) nearshore marine seagrass density. Caves can be conduits for groundwater pollution where terrestrial anthropogenic processes leach nutrient enriched water into marine caves springs that flow directly into coastal waters. Seagrass may serve as an environmental indicator due to its susceptibility to anthropogenic pollution. In 2007, environmental water monitoring devices were moored at the entrance of coastal cave springs throughout Bermuda to retrieve data on water quality, flow volume, velocity and direction. Nutrients (nitrate, phosphate, nitrite, and ammonium) and fecal bacteria (Enterococcus spp. and Escherichia coli) were measured in each cave. To qualify a link between terrestrial pollution and the nearshore environment, seagrass density within 100 m from cave entrances were measured. Bermuda caves were tidally influenced. Caves in Harrington Sound showed a delayed tidal flux with smaller ranges due to the restricted tidal inlet. Four caves exhibited a 1:1 in:out flow ratio. Caves with an imbalance flow ratio could be influenced by additional entrances, connection to an alternate water body, or cave geometry. Cave water was similar between caves. Environmental parameters and nutrients changed together, excluding seasonal variations in temperature (17.89 to 22.94 degrees C). Higher nutrients and fecal coliforms within caves indicated sewage may be leaching into the subsurface ground water system. Three seagrass species were evenly distributed within patchy meadows. Densities ranged from 0.91 to 4.5 (on a Braun-Blanket Scale). Higher mean densities in Harrington Sound, suggested the enclosed, protected nature of the sound allowed for reduced wave and current action. Syringodium filiforme decreased in density towards the ocean signifying a direct influence of cave water on seagrass beds. Tidal in and out-flux allowed for a constantly changing environment suitable for a mixture of seagrass species. Higher dissolved inorganic nutrient concentrations were associated with locations lacking seagrass. This study found 1) cave springs connected groundwater and nearshore seagrass ecosystems; and 2) components associated with terrestrial sewage pollution (DIN, HPO4=, and Enterococcus spp.) were higher within caves than nearshore waters.Item Clays and associated minerals in caves of the Guadalupe Mountains, New Mexico(Texas Tech University, 1998-05) Polyak, Victor JamesThe clay minerals occurring in caves of the Guadalupe Mountains of New Mexico include kaolinite, dickite, hydrated halloysite, illite, montmorillonite, trioctahedral smectite, and palygorskite. The minerals associated with these clays include alumimte, alunite, natroalunite, jarosite, calcite, dolomite, aragonite, huntite, gibbsite, nordstrandite, goethite, gypsum, hydrobasaluminite, metatyuyamunite, tyuyamunite, quartz, todorokite, and rancieite. The clay minerals found to be authigenic in the caves are hydrated halloysite, montmorillonite, trioctahedral smectite (probably saponite and stevensite), and palygorskite. Hydrated halloysite and alunite are by-products of the sulfuric acid-related speleogenesis that formed many of the larger caves; montmorillonite and illite were altered to hydrated halloysite and alunite. Montmorillonite was found to form in moistened floor and ledge sediments, but these occurrences are not common. Trioctahedral smectite forms in association with Mg-carbonates such as dolomite and huntite in crusts and moonmilks; evolution of the formation of these silicates follows the sequence of carbonate mineral formation. For instance, amorphous silica and poorly formed silicates precipitate with Mg-calcite and aragonite in stalagmites and crusts, while trioctahedral smectite forms in association with the Mg-carbonates. Palygorskite forms in smectite-rich sediments such as the brown laminated silts and green clays of Carlsbad Cavern. Dickite and illite are inherited in wall residues from the dissolution of the cavewall bedrock by condensate or carbon dioxide of the cave air, and/or by biochemical breakdown. Dickite and illite are not cave-authigenic. 40Ar/39Ar dating of alunite from these caves have yielded the formation age of five caves. The apparent ages ranged from 11.3 million years for Virgin Cave located at the higher elevations (2000 meters) to 3.9 million years for the Green Clay Room of Carlsbad Cavern at an elevation of 1090 meters. Alunite ages are strongly correlative with cave elevations. An apparent water table decline of approximately 1100 meters is shown to have occurred from 12 million years ago to the present.Item Laser-mapping and 3D reconstruction of the Lower Ordovician El Paso Group breccia collapse breccias, Franklin Mountains, Texas(2009-08) Bellian, Jerome Anthony, 1971-; Kerans, C. (Charles), 1954-The Lower Ordovician El Paso Group is a >400-m-thick carbonate succession exposed in the Franklin Mountains, El Paso, Texas. The El Paso Group contains multiple breccias related to collapsed-paleocave systems. These breccias have been documented as having formed during the top-Lower Ordovician Sauk depositional supersequence lowstand. Evidence presented in this study suggests that cave formation may have been as much as 350 million years younger and related to Laramide oblique right lateral compression. Regardless of the timing of formation, the breccias mapped in this study are of collapsed paleocave origin based on breccia clast organization and matrix content. Speleogenetic models are compared against observations of breccia distribution by direct field observations and mapping on sub-meter airborne light detection and ranging or lidar data. Point vectors were defined for every point within study area to highlight subtle changes in outcrop erosional profile for mapping geological features directly on the lidar point cloud. In addition, spectral data from airborne photography and hyperspectral image analysis were used assist in geological contact definition. A digital outcrop model was constructed from 3D geologic mapping results from which spatial statistic were extracted and used to reconstruct collapsed paleocave breccia bodies. The resultant breccia geometries were compared against laser-scanned modern cave dimensions, from Devil's Sinkhole, Rocksprings, Texas, and used in analysis of conceptual models for cave formation. The breccias of the southern Franklin Mountains follow linear trends that closely match Riedel shear fracture patterns predicted from right-lateral oblique compression. Stress orientations that match right-lateral oblique compression in the Phanerozoic of the El Paso region are related to the Laramide orogeny. The relationship of observed structures and the orientation of collapse breccias may indicate that southern Franklin Mountain breccia bodies are the result of a solution-enhanced tectonic karst system.Item The modern assessment of climate, calcite growth, and the geochemistry of cave drip waters as a precursor to paleoclimate study(2011-08) Casteel, Richard Cain; Banner, Jay L.; Sharp, Jr., John M.; Quinn, Terrence M.The overall goal of this study is to determine the resolution and type of proxy that any one drip site can provide for the determination of past climate. The study examines surface conditions (effective rainfall, temperature, PDSI), cave characteristics (cave geometry, cave air CO2, location), drip site characteristics (drip rate, drip rate response to rainfall), and drip water characteristics (pH, trace element ratios, alkalinity, temperature). The study encompasses two distinctly different caves, Inner Space Cavern (Chapter 2) and Westcave (Chapter 3). A goal of Chapter 2 is to identify drip sites where there is an intra-annual climate signal, which can assist with high resolution paleo-drought reconstructions when extended to speleothem studies. To be considered an intra-annual climate sensitive drip site, a site should display statistically significant correlations between (1) effective rainfall and drip rate; (2) effective rainfall and Mg/Ca; (3) drip rate and Mg/Ca; (4) Palmer Drought Severity Index (PDSI) and drip rate; and (5) PDSI and Mg/Ca. These relationships can be explained by the extent to which water flux in the karst overburden influences flow path characteristics, water residence time, and water-rock interactions. The data in Chapter 3 will indicate that (1) variations in trace element/Ca values in cave drip waters are temperature dependent and vary on a seasonal time scale, (2) the standardization of trace element/Ca values allows for between drip site comparisons, (3) the standardization of trace element/Ca values can add statistical power to statistical analyses by increasing the sample size, (4) calcite growth rates follow a seasonal pattern based on variations in surface temperature, (5) a regional drought indicator provides correlation with trace element/Ca values at some drip sites and this relationship is most likely dependent upon temperature.Item The Use of Stable and Radiocarbon Isotopes as a Method for Delineating Sources of Organic Matter in Anchialine Systems(2013-05-08) Neisch, Julie ASubmerged caves, locally referred to as cenotes, can be found throughout the Yucatan Peninsula of Mexico. These nutrient poor, aphotic ?underground estuaries? lack photosynthetic primary productivity, but are often found underlying high primary productivity areas such as mangroves and tropical forests. Adjacent ecosystems contribute organic carbon to the cave systems via percolation, where it is then utilized by the obligate, cave-dwelling fish and invertebrates. Another potential pathway through which organic carbon can enter the cave food web is through chemosynthesis. Chemoautotrophic sulfur-oxidizing or nitrifying bacteria have been found in the hydrogen sulfide layer or in the sediments of some anchialine caves. Our study utilizes 13C/12C and 15N/14N stable isotopes as well as 14C radiocarbon dating to determine and compare the sources of organic matter entering a coastal anchialine cave (Cenote Aak Kimin) versus an inland cave (Cenote Maya Blue) in the Yucatan Peninsula. Stable isotopes have long been employed in tropic investigations. This study, however, is the first to utilize radiocarbon isotopes in anchialine caves. The use of both stable and radiocarbon isotopes as source indicators provides greater discrimination in systems that contain numerous carbon sources or indistinct trophic levels, particularly to distinguish between chemoautotrophic versus photosynthetically derived carbon. Results indicate that chemosynthetically derived organic carbon contributes substantially to the diet of some crustaceans, such as the stygobitic shrimp Typhlatya, while other species remain dependent on detrital inputs. Depleted ?13C values and aged radiocarbon values (as low as -47.51? and 1840 yrs. for Typhlatya spp.) in comparison to particulate and sediment ?13C values (lowest -32.07? and -28.43?, respectively). A comparison of isotopic values between Cenote Aak Kimin and Cenote Maya Blue suggests that the trophic web of the coastal cave incorporates more photosynthetic or detrital carbon, while the inland cave, with more depleted 13C and 14C values, relies more heavily on chemoautotrophic carbon. Within both systems, however, distinct photosynthetic and chemoautotrophic levels were identified. Water quality parameters, especially dissolved oxygen and pH, support the hypothesis of bacterial activity at the halocline. Anchialine systems in the Yucatan Peninsula are threatened due to increases in tourism, development, and pollution. Quantifying and qualifying the inputs of organic carbon is vital for the management and conservation of the area?s freshwater resources.