Evaporite-karst problems and studies in the USA

USGS Publications Warehouse

Johnson, K.S.

2008-01-01

Evaporites, including rock salt (halite) and gypsum (or anhydrite), are the most soluble among common rocks; they dissolve readily to form the same types of karst features that commonly are found in limestones and dolomites. Evaporites are present in 32 of the 48 contiguous states in USA, and they underlie about 40% of the land area. Typical evaporite-karst features observed in outcrops include sinkholes, caves, disappearing streams, and springs, whereas other evidence of active evaporite karst includes surface-collapse structures and saline springs or saline plumes that result from salt dissolution. Many evaporites also contain evidence of paleokarst, such as dissolution breccias, breccia pipes, slumped beds, and collapse structures. All these natural karst phenomena can be sources of engineering or environmental problems. Dangerous sinkholes and caves can form rapidly in evaporite rocks, or pre-existing karst features can be reactivated and open up (collapse) under certain hydrologic conditions or when the land is put to new uses. Many karst features also propagate upward through overlying surficial deposits. Human activities also have caused development of evaporite karst, primarily in salt deposits. Boreholes (petroleum tests or solution-mining operations) or underground mines may enable unsaturated water to flow through or against salt deposits, either intentionally or accidentally, thus allowing development of small to large dissolution cavities. If the dissolution cavity is large enough and shallow enough, successive roof failures can cause land subsidence and/or catastrophic collapse. Evaporite karst, natural and human-induced, is far more prevalent than is commonly believed. ?? 2007 Springer-Verlag.

Secondary ferroan dolomite rhombs in oil reservoirs, Chadra Sands, Gialo field, Libya

DOE Office of Scientific and Technical Information (OSTI.GOV)

Al-Shaieb, Z.; Shelton, J.W.

1978-03-01

Oil-productive, Oligocene Chadra sands in Gialo field, Libya, at depths of 600 to 750 m contain small dolomite rhombs. The rhombs are present as single crystals on detrital grains and as nonmosaic aggregates in pore space. The dolomite is calcium-rich and contains up to 10% iron but not measurable sodium or strontium. Total dissolved solids of produced interstitial water from the Chadra sand range from about 4,500 to 10,000 ppM. Introduction of fresh (meteoric) water into the Chadra sands, which were deposited in shallow-marine (shelf) environment, was responsible for formation of the dolomite rhombs. Iron in the dolomite rhombs wasmore » derived from alteration of galuconite.« less

A new model for simulating spring discharge recession and estimating effective porosity of karst aquifers

NASA Astrophysics Data System (ADS)

Xu, Bin; Ye, Ming; Dong, Shuning; Dai, Zhenxue; Pei, Yongzhen

2018-07-01

Quantitative analysis of recession curves of karst spring hydrographs is a vital tool for understanding karst hydrology and inferring hydraulic properties of karst aquifers. This paper presents a new model for simulating karst spring recession curves. The new model has the following characteristics: (1) the model considers two separate but hydraulically connected reservoirs: matrix reservoir and conduit reservoir; (2) the model separates karst spring hydrograph recession into three stages: conduit-drainage stage, mixed-drainage stage (with both conduit drainage and matrix drainage), and matrix-drainage stage; and (3) in the mixed-drainage stage, the model uses multiple conduit layers to present different levels of conduit development. The new model outperforms the classical Mangin model and the recently developed Fiorillo model for simulating observed discharge at the Madison Blue Spring located in northern Florida. This is attributed to the latter two characteristics of the new model. Based on the new model, a method is developed for estimating effective porosity of the matrix and conduit reservoirs for the three drainage stages. The estimated porosity values are consistent with measured matrix porosity at the study site and with estimated conduit porosity reported in literature. The new model for simulating karst spring hydrograph recession is mathematically general, and can be applied to a wide range of karst spring hydrographs to understand groundwater flow in karst aquifers. The limitations of the model are discussed at the end of this paper.

Karst in evaporite rocks of the United States

USGS Publications Warehouse

Johnson, Kenneth S.

2002-01-01

Evaporites are the most soluble of common rocks; they are dissolved readily to form the same range of karst features that typically are found in limestones and dolomites. Evaporites, including gypsum (or anhydrite) and salt, are present in 32 of the 48 contiguous United States, and they underlie about 35-40% of the land area. Evaporite outcrops typically contain sinkholes, caves, disappearing streams, and springs. Other evidence of active karst in evaporites includes surface-collapse features and saline springs or saline plumes that result from dissolution of salt. Many evaporites, including some in the deeper subsurface, also contain evidence of paleokarst that is no longer active; this evidence includes dissolution breccias, breccia pipes, slumped beds, and collapse structures. Evaporites occur in 24 separate structural basins or geographic districts in the United States, and either local or extensive evaporite karst is known in almost all of these basins or districts. Human activities also have caused development of evaporite karst, primarily in salt deposits. Boreholes or underground mines may enable (either intentionally or inadvertently) unsaturated water to flow through or against salt deposits, thus allowing development of small to large dissolution cavities. If the dissolution cavity is large enough and shallow enough, successive roof failures can cause land subsidence or catastrophic collapse. Evaporite karst, both natural and human-induced, is far more prevalent than commonly believed.

[Summer Greenhouse Gases Exchange Flux Across Water-air Interface in Three Water Reservoirs Located in Different Geologic Setting in Guangxi, China].

PubMed

Li, Jian-hong; Pu, Jun-bing; Sun, Ping-an; Yuan, Dao-xian; Liu, Wen; Zhang, Tao; Mo, Xue

2015-11-01

Due to special hydrogeochemical characteristics of calcium-rich, alkaline and DIC-rich ( dissolved inorganic carbon) environment controlled by the weathering products from carbonate rock, the exchange characteristics, processes and controlling factors of greenhouse gas (CO2 and CH4) across water-air interface in karst water reservoir show obvious differences from those of non-karst water reservoir. Three water reservoirs (Dalongdong reservoir-karst reservoir, Wulixia reservoir--semi karst reservoir, Si'anjiang reservoir-non-karst reservoir) located in different geologic setting in Guangxi Zhuang Autonomous Region, China were chosen to reveal characteristics and controlling factors of greenhouse gas exchange flux across water-air interface. Two common approaches, floating chamber (FC) and thin boundary layer models (TBL), were employed to research and contrast greenhouse gas exchange flux across water-air interface from three reservoirs. The results showed that: (1) surface-layer water in reservoir area and discharging water under dam in Dalongdong water reservoir were the source of atmospheric CO2 and CH4. Surface-layer water in reservoir area in Wulixia water reservoir was the sink of atmospheric CO2 and the source of atmospheric CH4, while discharging water under dam was the source of atmospheric CO2 and CH4. Surface-layer water in Si'anjiang water reservoir was the sink of atmospheric CO2 and source of atmospheric CH4. (2) CO2 and CH4 effluxes in discharging water under dam were much more than those in surface-layer water in reservoir area regardless of karst reservoir or non karst reservoir. Accordingly, more attention should be paid to the CO2 and CH4 emission from discharging water under dam. (3) In the absence of submerged soil organic matters and plants, the difference of CH4 effluxes between karst groundwater-fed reservoir ( Dalongdong water reservoir) and non-karst area ( Wulixia water reservoir and Si'anjiang water reservoir) was less. However, CO2

Hydrogeology and quality of ground water in the Boone Formation and Cotter Dolomite in karst terrain of northwestern Boone County, Arkansas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leidy, V.A.; Morris, E.E.

1991-01-01

Shallow groundwater flow systems in karst terrain of northwestern Boone County, Arkansas, are particularly susceptible to contamination. The potential for groundwater contamination probably is greater in the northern one-half of the study area where there are more photolineaments and presumably subsurface fractures. Groundwater samples from 17 springs discharging from the Boone Formation and 17 wells completed in the Cotter Dolomite were analyzed to determine ambient groundwater quality and to document water quality variations. The chemical constituents in groundwater generally did not exceed US Environmental Protection Agency primary or secondary maximum contaminant levels. However, fecal coliform and fecal streptococcus bacteria weremore » detected in most springs and in three wells. One spring, located near an abandoned wood-treatment plant (a designated Superfund site), had maximum iron, manganese, lead, and pentachlorophenol concentration that exceeded US Environmental Protection Agency's primary or secondary maximum contamination levels for drinking water. Water samples collected from selected springs emerging from the Boone Formation exhibited an overall decrease in specific conductance and total alkalinity, calcium, magnesium, sodium, and chloride concentrations and an overall increase in nitrate, fecal coliform, and fecal streptococcus bacteria concentrations 3 to 8 hours after a rainstorm.« less

Dolomitization and over-dolomitization in the Vajont limestone (Dolomiti Bellunesi, Italy) controlled by Mesozoic normal faults: a microstructural and diagenesis study

NASA Astrophysics Data System (ADS)

Cortinovis, Silvia; Swennen, Rudy; Bistacchi, Andrea

2015-04-01

The Vajont Gorge (Dolomiti Bellunesi, Italy) provides spectacular outcrops of Jurassic limestones (Vajont Limestone Formation) in which Mesozoic faults and fracture corridors are continuously exposed. Some of these faults acted as conduits for Mg-enriched hydrothermal fluids resulting in structurally-controlled dolomitization of the limestone. The dolomitization resulted in several dolomite bodies (100-200 m thick and several hundreds of meters along fault strike) that are particularly interesting as reservoir analogues for hydrocarbon, CO2, or water-bearing systems. The dolomitization process occurred after deposition and compaction of the oolitic limestone (dolomitization post-dates a dissolution event that affected the internal parts of the oolites), but before the Alpine contractional deformation. In fact, the meso-structural data collected in the Vajont Gorge allowed the reconstruction of a 3D model showing that the circulation of the dolomitizing fluids into the limestone host rock, but also the late stage of porosity reduction (strong pore filling due to over-dolomitization) were controlled by normal faults and fracture corridors interpreted as Pre-Alpine (Jurassic or Cretaceous). Later on, the influence of Alpine (Tertiary) deformation have been very limited in the studied volume. For instance dolomite veins are sometimes overprinted by bed-inclined stylolites consistent with Alpine shortening axes, but no large Alpine fault is present in the studied outcrops. Cathodoluminescence microscopy allowed recognizing different growth stages saddle dolomite crystals, which point to varying precipitation conditions during three main stages of dolomitization. Dolomite and calcite crystal twinning suggests deformation under increasing temperature conditions, consistent with intracrystalline plasticity deformation mechanisms. The presence of cataclasites composed of hydrothermal dolostone clasts, in turn cemented by dolomite, or of dolomite veins and compaction

Characterization of Endolithic Culturable Microbial Communities in Carbonate Rocks from a Typical Karst Canyon in Guizhou (China).

PubMed

Tang, Yuan; Cheng, Jian-Zhong; Lian, Bin

2017-01-02

The endolithic environment is a ubiquitous habitat for microorganisms and a critical interface between biology and geology. In this study, a culture-based method and the phylogenetic analysis based on 16S rRNA and internal transcribed spacer (ITS) sequences were used to investigate the diversity of endolithic bacteria and fungi in two main types of carbonate rocks (namely dolomite and limestone) from Nanjiang Canyon in Guizhou karst area, China. The results of bacterial diversity indicated that all bacteria isolated from dolomite and limestone rocks were divided into 4 bacterial groups, including Proteobacteria, Actinobacteria, Firmicutes and Bacteroidetes. For these two kinds of rocks, Proteobacteria was the first dominant group, and Gammaproteobacteria occupied the greatest proportion which might be closely related to Pseudomonas in phylogeny to be the most dominant genera after isolation. Actinobacteria and Bacillus bacteria were also widespread in these two kinds of rock environments. There were only 9 and 8 strains of fungi isolated from dolomite and limestone respectively, which all belonged to Ascomycota. To the best of our knowledge, this is the first report on diversity of endolithic culturable bacteria and fungi in carbonate rocks in Guizhou karst region. These microorganisms may play an important and unprecedented role in the carbonate rock weathering during the long history of geological evolution.

Verification of the karst flow model under laboratory controlled conditions

NASA Astrophysics Data System (ADS)

Gotovac, Hrvoje; Andric, Ivo; Malenica, Luka; Srzic, Veljko

2016-04-01

Karst aquifers are very important groundwater resources around the world as well as in coastal part of Croatia. They consist of extremely complex structure defining by slow and laminar porous medium and small fissures and usually fast turbulent conduits/karst channels. Except simple lumped hydrological models that ignore high karst heterogeneity, full hydraulic (distributive) models have been developed exclusively by conventional finite element and finite volume elements considering complete karst heterogeneity structure that improves our understanding of complex processes in karst. Groundwater flow modeling in complex karst aquifers are faced by many difficulties such as a lack of heterogeneity knowledge (especially conduits), resolution of different spatial/temporal scales, connectivity between matrix and conduits, setting of appropriate boundary conditions and many others. Particular problem of karst flow modeling is verification of distributive models under real aquifer conditions due to lack of above-mentioned information. Therefore, we will show here possibility to verify karst flow models under the laboratory controlled conditions. Special 3-D karst flow model (5.6*2.6*2 m) consists of concrete construction, rainfall platform, 74 piezometers, 2 reservoirs and other supply equipment. Model is filled by fine sand (3-D porous matrix) and drainage plastic pipes (1-D conduits). This model enables knowledge of full heterogeneity structure including position of different sand layers as well as conduits location and geometry. Moreover, we know geometry of conduits perforation that enable analysis of interaction between matrix and conduits. In addition, pressure and precipitation distribution and discharge flow rates from both phases can be measured very accurately. These possibilities are not present in real sites what this model makes much more useful for karst flow modeling. Many experiments were performed under different controlled conditions such as different

Evaporite karst of northern lower Michigan

USGS Publications Warehouse

Black, T.J.

1997-01-01

Michigan has three main zones of evaporite karst: collapse breccia in Late Silurian deposits of the Mackinac Straits region; breccia, collapse sinks, and mega-block collapse in Middle Devonian deposits of Northern Lower Michigan, which overlaps the preceding area; and areas of soil swallows in sinks of Mississippian deposits between Turner and Alabaster in Arenac and Iosco counties, and near Grand Rapids in Kent County. The author has focused his study on evaporite karst of the Middle Devonian deposits. The Middle Devonian depos its are the Detroit River Group: a series consisting of limestone, dolomite, shale, salt, gypsum, and anhydrite. The group occurs from subcrop, near the surface, to nearly 1400 feet deep from the northern tip of the Southern Peninsula to the south edge of the "solution front" Glacial drift is from zero to 350 feet thick. Oil and gas exploration has encountered some significant lost-circulation zones throughout the area. Drilling without fluid returns, casing-seal failures, and lost holes are strong risks in some parts of the region. Lost fluid returns near the top of the group in nearby areas indicate some karst development shortly after deposition. Large and irregular lost-circulation zones, linear and patch trends of large sink holes, and 0.25 mile wide blocks of down-dropped land in the northern Lower Peninsula of Michigan were caused by surface- and ground-water movement along faults into the Detroit River Group. Glaciation has removed some evidence of the karst area at the surface. Sinkhole development, collapse valleys, and swallows developed since retreat of the glacier reveal an active solution front in the Detroit River Group.

Study on comprehensive planning of rocky desertification in karst area of Chongqing

NASA Astrophysics Data System (ADS)

Zang, Yajun

2017-11-01

Chongqing is a key area for comprehensive treatment of rocky desertification in karst areas of china. Strengthening the comprehensive management of karst rocky desertification area, for the maintenance of ecological safety of Three Gorges Reservoir area, expanding the karst rocky desertification area people survival and development space, and improving the regional ecological conditions, have important practical significance to the construction of ecological civilization and building a harmonious society. Based on the investigation, analysis and arrangement of the data in the rocky desertification area, the paper puts forward the corresponding measures and phased targets for the treatment of the Rocky Desertification in the karst areas of Chongqing.

Significant role of structural fractures in Ren-Qiu buried-block oil field, eastern China

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fei, Q.; Xie-Pei, W.

1983-03-01

Ren-qui oil field is in a buried block of Sinian (upper Proterozoic) rocks located in the Ji-zhong depression of the western Bohai Bay basin in eastern China. The main reservoir consists of Sinian dolomite rocks. It is a fault block with a large growth fault on the west side which trends north-northeast with throws of up to 1 km (0.6 mi) or more. The source rocks for the oil are Paleogene age and overlie the Sinian dolomite rocks. The structural fractures are the main factor forming the reservoir of the buried-block oil field. Three structural lines, trending northeast, north-northeast, andmore » northwest, form the regional netted fracture system. The north-northeast growth fault controlled the structural development of the buried block. The block was raised and eroded before the Tertiary sediments were deposited. In the Eocene Epoch, the Ji-zhong depression subsided, but the deposition, faulting, and related uplift of the block happened synchronously as the block was gradually submerged. At the same time, several horizontal and vertical karst zones were formed by the karst water along the netted structural fractures. The Eocene oil source rocks lapped onto the block and so the buried block, with many developed karst fractures, was surrounded by a great thickness of source rocks. As the growth fault developed, the height of the block was increased from 400 m (1300 ft) before the Oligocene to 1300 m (4250 ft) after. As the petroleum was generated, it migrated immediately into the karst fractures of the buried block along the growth fault. The karst-fractured block reservoir has an 800-m (2600-ft) high oil-bearing closure and good connections developed between the karst fractures.« less

Guidelines for sinkhole and subsidence rehabilitation based on generic geological models of a dolomite environment on the East Rand, South Africa

NASA Astrophysics Data System (ADS)

Kleinhans, Ilse; Van Rooy, J. Louis

2016-05-01

A sound understanding of the various factors influencing and associated with the formation of sinkholes or subsidences on dolomite land is essential for the selection of appropriate rehabilitation methods. The investigation and rehabilitation of numerous sinkholes and subsidences located on dolomite in the East Rand of South Africa, created an opportunity to develop a broad based understanding of different karst environments, their susceptibility to sinkhole and subsidence formation and best practice rehabilitation methods. This paper is based on the guidelines developed whereby the geological model of the sinkhole or subsidence is used to recommend an appropriate rehabilitation method. Nine typical geological models with recommended rehabilitation methods are presented in this paper.

Dolomitization and neomorphism of Mississippian (Visean) upper debolt formation, Blueberry field, northeastern British Columbia: Geologic, petrologic, and chemical evidence

DOE Office of Scientific and Technical Information (OSTI.GOV)

Durocher, S.; Al-Aasm, I.S.

1997-06-01

Petrographic, chemical, and isotopic studies of the Mississippian (Visean) upper Debolt Formation in the Blueberry field, British Columbia, Canada, reveal that dolomitization was the result of several diagenetic events and that neomorphic alteration of these dolomites significantly modified their original chemical signatures. These studies also demonstrate how tectonics play an important role in controlling and modifying reservoir dolomites in the area. Petrographic investigations have documented two early dolomite phases, (1) early matrix dolomite and (2) pervasive dolomite, and two later generations, (3) coarse cement and (4) pseudomorphic replacement of crinoids. Early matrix dolomite occurs as small (average 25 {mu}m) subhedralmore » to euhedral crystals that replace the matrix of carbonate mudstones, wackestones, and packstones. Petrographic evidence suggests that early matrix dolomite had a relatively early, precompaction origin, possibly from marine fluids. However, geochemical evidence indicates that later fluids have altered their original geochemical signatures. Pervasive dolomite, which forms the reservoir intercrystalline porosity, occurs with planar-s and planar-e textures. Planar-s crystals typically have a dirty appearance and exhibit homogeneous dull brown/red cathodoluminescence colors. Planar-e crystals may appear with a cloudy core and a clear rim, and under cathodoluminescence display an irregular dull brown/red core and a thin, bright red rim. Due to the spatial distribution pattern of pervasive dolomite with respect to the overlying unconformity surface, its paleogeographic distribution and close temporal relationship with meteoric diagenetic events, pervasive dolomite formed from a mixture of seawater and meteoric fluids. However, alteration of their primary chemistry by later fluids is indicated by their depleted {delta}{sup 18}O values and radiogenic {sup 87}Sr/{sup 86}Sr ratios.« less

Heterotrophic prokaryotic production in ultra-oligotrophic alpine karst aquifers and ecological implications

PubMed Central

Wilhartitz, Inés C.; Kirschner, Alexander K.T.; Stadler, Hermann; Herndl, Gerhard J.; Dietzel, Martin; Latal, Christine; Mach, Robert L.; Farnleitner, Andreas H.

2011-01-01

Spring waters from alpine karst aquifers are important drinking water resources. To investigate in situ prokaryotic heterotrophic production (HP) and its controlling factors, two alpine karst springs of contrasting hydrogeology but of nearby catchments were studied over two annual cycles. Heterotrophic production in spring water, as determined by [3H]leucine incorporation, was low but revealed strong seasonal variations ranging from 0.06 to 6.83 pmol C l−1 h−1 (DKAS1, dolomitic karst-spring) and from 0.50 to 75.6 pmol C l−1 h−1 (LKAS2, limestone karst-spring). Microautoradiography combined with catalyzed reporter deposition - fluorescence in situ hybridization (MAR-CARD-FISH) showed that only about 7 % of the picoplankton community took up [3H]leucine resulting in generation times of 3 to 684 days. Principal component analysis, applying hydrological, chemical and biological parameters demonstrated that planktonic heterotrophic production in LKAS2 was strongly governed by hydrogeographical components (e.g. discharge), whereas variations in DKAS1 are also strongly influenced by changes within the aquifer itself. Measurements in sediments recovered from LKAS2, DKAS1 and similar alpine karst aquifers (n=12) revealed an 106-fold higher heterotrophic production (average 19 μmol C dm−3 h−1) with significantly lower generation times as compared to the planktonic fraction, highlighting the metabolic potential of surface associated endokarst communities to add to self-purification processes. Estimates of microbially mediated CO2 in this compartment indicated a possible contribution to karstification. PMID:19490127

Caves, Carbonates and Climate: Karst Landscape Development through Environmental Forcing, Little Cayman Island

NASA Astrophysics Data System (ADS)

Hsia, S.; Ouellette, G., Jr.; Manfrino, C.

2016-12-01

The Cayman Islands are situated in the west-central Caribbean Sea, between Cuba and the Yucatan Peninsula. Little Cayman Island (LCI) is relatively underdeveloped and understudied in comparison to its sister islands, Grand Cayman and Cayman Brac, and hosts less than 200 permanent residents over a 30 square kilometer area. However, like its sister islands, LCI is a small carbonate platform derived from reef building during the Oligocene, Miocene, and Quaternary. The shared geologic history of the Cayman Islands along with minimal human disturbance makes LCI an ideal site to study an island karst landscape. Conduction of field surveys, stratigraphic and petrologic comparisons between primary lithologic formations, and compilation of a geospatial inventory of karst features and lithology of LCI using GIS revealed novel insights into landscape evolution on LCI. In addition to surface karst surveys, several caves on the island were mapped. Cave morphologies suggest that evolution of LCI karst features have been driven by both hydroclimate, as well as salt and freshwater mixing, modulated by sea level fluctuations. These findings are mirrored in the lithology of partially dolomitized Miocene carbonates, which contain paleo-karst fill features and reveal hydroclimate influence, as well as enhanced resistance to dissolution in the present day, ostensibly from submersion in Mg-rich sea waters prior to the Quaternary. These findings shed light on the complex relationship of climate, geology, and karst landscape development on this particular carbonate island. This information is critical in anticipating structural and hydrogeological integrity on LCI under future climate change scenarios and serves as an example of the interplay linking climate and geologic processes to karst landscape development on small carbonate islands.

Experimental observation and numerical simulation of permeability changes in dolomite at CO2 sequestration conditions

NASA Astrophysics Data System (ADS)

Tutolo, B. M.; Luhmann, A. J.; Kong, X.; Saar, M. O.; Seyfried, W. E.

2013-12-01

Injecting surface temperature CO2 into geothermally warm reservoirs for geologic storage or energy production may result in depressed temperature near the injection well and thermal gradients and mass transfer along flow paths leading away from the well. Thermal gradients are particularly important to consider in reservoirs containing carbonate minerals, which are more soluble at lower temperatures, as well as in CO2-based geothermal energy reservoirs where lowering heat exchanger rejection temperatures increases efficiency. Additionally, equilibrating a fluid with cation-donating silicates near a low-temperature injection well and transporting the fluid to higher temperature may enhance the kinetics of mineral precipitation in such a way as to overcome the activation energy required for mineral trapping of CO2. We have investigated this process by subjecting a dolomite core to a 650-hour temperature series experiment in which the fluid was saturated with CO2 at high pressure (110-126 bars) and 21°C. This fluid was recirculated through the dolomite core, increasing permeability from 10-16 to 10-15.2 m2. Subsequently, the core temperature was raised to 50° C, and permeability decreased to 10-16.2 m2 after 289 hours, due to thermally-driven CO2 exsolution. Increasing core temperature to 100°C for the final 145 hours of the experiment caused dolomite to precipitate, which, together with further CO2 exsolution, decreased permeability to 10-16.4 m2. Post-experiment x-ray computed tomography and scanning electron microscope imagery of the dolomite core reveals abundant matrix dissolution and enlargement of flow paths at low temperatures, and subsequent filling-in of the passages at elevated temperature by dolomite. To place this experiment within the broader context of geologic CO2 sequestration, we designed and utilized a reactive transport simulator that enables dynamic calculation of CO2 equilibrium constants and fugacity and activity coefficients by incorporating

Study on the influencing factors of natural energy development in carbonate reservoirs

NASA Astrophysics Data System (ADS)

Wang, Zhenjie

2018-06-01

In depletion mining, the crude oil is produced by using the edge water and bottom water of reservoirs as well as the reservoir itself and the elastic properties of reservoirs and irreducible water. Depletion mining has the following three advantages: (1) full use of natural energy; (2) can save investment; (3) stratum adaptability. Since depleted mining is mined at the cost of a substantial reduction in pressure, reservoir stress sensitivity is not so strong and natural energy development can be chosen when the saturation pressure is large. In the case of carbonate reservoirs, the cumulative oil production increases with the increase of permeability to karst caves. However, when the permeability of karst caves is more than 100 x 10-3µm-2, the final cumulative oil production changes little. (4) For the carbonate reservoir, as the fracture permeability increases, the cumulative oil production increases and the development time greatly decreases. However, when the permeability of the karst cave is greater than 1000 x 10-3µm-2, although the oil production rate is very large, but the final cumulative oil change is small. (5) For the carbonate reservoir, it can be seen from the calculation results that as the coupling coefficient increases, the oil production in the whole area increases, indicating that the coupling effect between the fracture and the karst cave will be better and the oil recovery will be improved

The Tonian Beck Spring Dolomite: Marine dolomitization in a shallow, anoxic sea

NASA Astrophysics Data System (ADS)

Shuster, Alice Mary; Wallace, Malcolm William; van Smeerdijk Hood, Ashleigh; Jiang, Ganqing

2018-06-01

The reason for the abundance of dolomite lithologies in Earth's early geological record compared to modern environments remains contentious. This study provides new insight into this Precambrian "dolomite problem" by revisiting one of the most controversial dolomite localities, the Beck Spring Dolomite, of Death Valley, USA. Consistent with some previous studies, petrographic evidence indicates that although the Beck Spring Dolomite now consists almost entirely of dolomite, it was originally precipitated largely as aragonite and high-Mg calcite. Depositional constituents (microbialites and ooids) were likely originally aragonitic, and early marine length-fast cements (now dolomite) are suggested to have precipitated as high-Mg calcite then replaced syntaxially by dolomite. Based on petrographic and geochemical evidence, we suggest that marine dolomitization was the dominant synsedimentary diagenetic process in the unit, and for the most part, involved syntaxial and mimetic replacement. Further, a length-slow fibrous dolomite generation was precipitated during the later stages of marine diagenesis as a primary marine dolomite cement. This is indicated by the length-slow crystallographic structure of the cement and from its preserved geochemical and cathodoluminescence growth zonation. This new evidence for Tonian marine dolomite precipitation reinforces the idea of Precambrian marine environmental conditions, including the chemical composition of seawater, promoting dolomite formation at this time. The trace metal geochemical composition of well-preserved marine components, especially dolomite marine cements, reveals information about redox conditions in this Tonian shallow seawater. In terms of rare earth element geochemistry, the Beck Spring Dolomite has no significant Ce anomaly, and a ubiquitous positive Eu anomaly, consistent with widespread oceanic anoxia during deposition. Furthermore, the relatively low levels of iron and chalcophile elements Co, Cu, Pb and

Dolomite-II: A new high pressure polymorph of CaMg(CO3)2

NASA Astrophysics Data System (ADS)

Santillan, J.; Williams, Q.; Knittle, E.

2002-12-01

We have measured the infrared spectra and x-ray diffraction of CaMg(CO3)2-dolomite to pressures of 50 GPa at 300 K. We observe both splittings and disappearances of x-ray diffraction peaks between 15 and 20 GPa, as well as new bands in the infrared spectrum of dolomite. The onset of the changes in both the x-ray and infrared data appears to be gradual, and thus kinetically impeded: this is consistent with previous shock results. The infrared and x-ray data are consistent with dolomite adopting a calcite-III-like structure. The net volume change associated with the transition based on a calcite-III monoclinic unit cell is ~4 percent. We calculate that the high pressure phase of dolomite has a volume virtually indistinguishable from that of magnesite plus aragonite. Similarly, an assemblage of the high pressure phase of dolomite and magnesium silicate perovskite has an essentially volume to a magnesite plus calcium silicate perovskite assemblage. Our results thus indicate that high-pressure polymorphism in dolomite could stabilize CaMg(CO3)2 in the deep mantle, and thus that high-pressure polymorphs of dolomite could represent the main reservoir for carbon storage within Earth's lower mantle.

Imaging of karsts on buried carbonate platform in Central Luconia Province, Malaysia

NASA Astrophysics Data System (ADS)

Nur Fathiyah Jamaludin, Siti; Mubin, Mukhriz; Latiff, Abdul Halim Abdul

2017-10-01

Imaging of carbonate rocks in the subsurface through seismic method is always challenging due to its heterogeneity and fast velocity compared to the other rock types. Existence of karsts features on the carbonate rocks make it more complicated to interpret the reflectors. Utilization of modern interpretation software such as PETREL and GeoTeric® to image the karsts morphology make it possible to model the karst network within the buried carbonate platform used in this study. Using combination of different seismic attributes such as Variance, Conformance, Continuity, Amplitude, Frequency and Edge attributes, we are able to image the karsts features that are available in the proven gas-field in Central Luconia Province, Malaysia. The mentioned attributes are excellent in visualize and image the stratigraphic features based on the difference in their acoustic impedance as well as structural features, which include karst. 2D & 3D Karst Models were developed to give a better understanding on the characteristics of the identified karsts. From the models, it is found that the karsts are concentrated in the top part of the carbonate reservoir (epikarst) and the middle layer with some of them becomes extensive and create karst networks, either laterally or vertically. Most of the vertical network karst are related to the existence of faults that displaced all the horizons in the carbonate platform.

SWAT-based streamflow and embayment modeling of Karst-affected Chapel branch watershed, South Carolina

Treesearch

Devendra Amatya; M. Jha; A.E. Edwards; T.M. Williams; D.R. Hitchcock

2011-01-01

SWAT is a GIS-based basin-scale model widely used for the characterization of hydrology and water quality of large, complex watersheds; however, SWAT has not been fully tested in watersheds with karst geomorphology and downstream reservoir-like embayment. In this study, SWAT was applied to test its ability to predict monthly streamflow dynamics for a 1,555 ha karst...

Speleogenesis in Dinaric karst area

NASA Astrophysics Data System (ADS)

Garasic, Mladen; Garasic, Davor

2015-04-01

-European (Persian - Farsi) origin coming from the word "kar", "gar", khar" or "ghar" meaning a "rock" or today a "cave" too. After using the German name "Karst" for the plateau Kras (Slovenia) above Trieste (Italy), the international scientific term derives to designate "karst" and the whole science of karst phenomena, "karstology". In 1972 a Glossary of multilingual equivalents of karst terms was published by UNESCO and FAO. From 2005 Union Internationale de Speleologie (UIS) on internet have Caver's MultiLingual Dictionary with 24 languages till today. The geological history (and speleogenesis) of/in the Dinaric karst in Croatia can be divided into six periods , or according to the facies sedimentary features on six mega sequencies . From the older to the younger ones are: (1) younger Carboniferous - Permian older ( region of Lika , Ričica ), (2) older Permian - Middle Triassic ( Lika , Brusani , Paklenica , Knin polje, Vrlika ) , (3) younger Triassic (younger Noricum ) - Early Jurassic (older Toarcium ) (the so-called areas . Haupt dolomite ), (4) younger Toarcium - younger Cenomanian / Turonian older ( mountain Dinara, Istria , areas of Rudistic limestones), (5) older Turonian - the end of the Cretaceous ( Istria , Cres , Obrovac, Zrmanja river ), (6) Eocene (areas of foraminipheral limestones), (7) Oligocene - Miocene ( Drnis , Sinj , Imotski , Promina , Benkovac , southern Velebit Mt) and (8) Pliocene - Holocene (Velebit mountain ). The boundaries between megasequencies marked as important geological events such as interruptions due to sedimentation and uplift with geogological regresion with karst formation or deepening of depositional environments . The stages of karstification only through time and places where it is still visible today . - perm older - karstification upper Carboniferous and lower Permian limestone , Ričice and Rizvanuša ; Ladinian - younger - older Noricum - karstification Middle Triassic dyploporious limestones , on Orlic , mountains of Štirovača to

European and Middle-East ferroan hydrothermal dolomites: lessons learnt with respect to crustal dynamics, fluid circulations and rock-fluid interactions

NASA Astrophysics Data System (ADS)

Nader, Fadi Henri; Gasparrini, Marta; Bachaud, Pierre

2016-04-01

Classical case studies of hydrothermal dolostones, which are known worldwide to provide excellent reservoirs for ores and hydrocarbons, often illustrate the presence of iron-rich dolomite phases. The world-class hydrothermal dolostones from the Basque-Cantabrian Basin (Northern Spain) exemplify the initiation of high temperature dolomitization (at about 200°C), with significant amount of ferroan dolomite phases (including up to 2% FeO). These dolomites are believed to be responsible for the pervasive replacement of the original limestone rocks - they are followed by non-ferroan dolomite phases. The associated fluids are supposed to have interacted with basement rocks, and travelled from deep-seated sources along major fault pathways. The geochemical traits of such fluids are also typically similar to, and probably associated with, mineralization fluids (e.g. Pb-Zn, MVT). In the Middle East, several observed dolostones show, on the contrary, a later phase of ferroan dolomite cements which occlude the inter-crystalline porosity of earlier non-ferroan matrix dolomites. Dolomitization occurred under increasingly higher temperatures (from 50 to 100°C) during burial. Here, the origin of iron-rich fluids and conditions of precipitation of associated dolomites do not necessarily involve interactions with basement rocks, but rather a relative Fe-enrichment with further reducing settings. Based on previous research projects concerning a variety of dolostones from Europe and the Middle-East, this contribution presents observational, analytical and computational results focused on ferroan dolomites. Recent numerical geochemical modelling emphasized the physico-chemical pre-requisites for crystallizing ferroan rather than non-ferroan dolomites (and vice-versa), allowing better understanding of related diagenetic processes. Besides, important larger-scale information on the crustal fluid circulations are demonstrated to be intimately associated to the parent-fluids sources and

Water resources management in karst aquifers - concepts and modeling approaches

NASA Astrophysics Data System (ADS)

Sauter, M.; Schmidt, S.; Abusaada, M.; Reimann, T.; Liedl, R.; Kordilla, J.; Geyer, T.

2011-12-01

Water resources management schemes generally imply the availability of a spectrum of various sources of water with a variability of quantity and quality in space and time, and the availability and suitability of storage facilities to cover various demands of water consumers on quantity and quality. Aquifers are generally regarded as suitable reservoirs since large volumes of water can be stored in the subsurface, water is protected from contamination and evaporation and the underground passage assists in the removal of at least some groundwater contaminants. Favorable aquifer properties include high vertical hydraulic conductivities for infiltration, large storage coefficients and not too large hydraulic gradients / conductivities. The latter factors determine the degree of discharge, i.e. loss of groundwater. Considering the above criteria, fractured and karstified aquifers appear to not really fulfill the respective conditions for storage reservoirs. Although infiltration capacity is relatively high, due to low storativity and high hydraulic conductivities, the small quantity of water stored is rapidly discharged. However, for a number of specific conditions, even karst aquifers are suitable for groundwater management schemes. They can be subdivided into active and passive management strategies. Active management options include strategies such as overpumping, i.e. the depletion of the karst water resources below the spring outflow level, the construction of subsurface dams to prevent rapid discharge. Passive management options include the optimal use of the discharging groundwater under natural discharge conditions. System models that include the superposition of the effect of the different compartments soil zone, epikarst, vadose and phreatic zone assist in the optimal usage of the available groundwater resources, while taking into account the different water reservoirs. The elaboration and implementation of groundwater protection schemes employing well

Experimental observation of permeability changes in dolomite at CO2 sequestration conditions.

PubMed

Tutolo, Benjamin M; Luhmann, Andrew J; Kong, Xiang-Zhao; Saar, Martin O; Seyfried, William E

2014-02-18

Injection of cool CO2 into geothermally warm carbonate reservoirs for storage or geothermal energy production may lower near-well temperature and lead to mass transfer along flow paths leading away from the well. To investigate this process, a dolomite core was subjected to a 650 h, high pressure, CO2 saturated, flow-through experiment. Permeability increased from 10(-15.9) to 10(-15.2) m(2) over the initial 216 h at 21 °C, decreased to 10(-16.2) m(2) over 289 h at 50 °C, largely due to thermally driven CO2 exsolution, and reached a final value of 10(-16.4) m(2) after 145 h at 100 °C due to continued exsolution and the onset of dolomite precipitation. Theoretical calculations show that CO2 exsolution results in a maximum pore space CO2 saturation of 0.5, and steady state relative permeabilities of CO2 and water on the order of 0.0065 and 0.1, respectively. Post-experiment imagery reveals matrix dissolution at low temperatures, and subsequent filling-in of flow passages at elevated temperature. Geochemical calculations indicate that reservoir fluids subjected to a thermal gradient may exsolve and precipitate up to 200 cm(3) CO2 and 1.5 cm(3) dolomite per kg of water, respectively, resulting in substantial porosity and permeability redistribution.

Origin of dolostone reservoir rocks, Smackover Formation (Oxfordian), northeastern Gulf Coast, U. S. A

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prather, B.E.

Formation of regionally extensive dolostone reservoir rocks in the Smackover can be understood despite the possible effects of recrystallization. Geochemical and petrographic data suggest that dolomitization took place in (1) seawater-seepage, (2) reflux, (3) near-surface mixed-water, (4) shallow-burial mixed-water, and (5) deeper burial environments, which overlapped in time and space to form a platform-scale' dolostone body composed of a complex mixture of dolomites. Seawater-seepage and reflux dolomitization occurred in the near surface penecontemporaneously with deposition of the Smackover and overlying Haynesville Formations. Dolomitization by seawater seepage occurred within an oolite grainstone sill which separated an intraplatform salt basin from themore » open sea. Seawater flowed landward through the sill in response to evaporitic drawdown of brines in the isolated intraplatform basin. Isolation of the salt basin occurred during the Oxfordian when the shoreline retreated from the Conecuh embayment. Dolomite located at the top of the Smackover enriched in {sup 18}O suggests additional dolomitization by reflux of hypersaline brines. Reflux occurred as Buckner coastal sabkhas prograded over Smackover oolite grainstone shoreface deposits. Vugs lined with shallow-burial calcite and dolomite cements indicate flushing of the Smackover grainstone aquifer with fresh water. Freshwater intrusion probably occurred following sea level lowstands during the Late Jurassic and Early Cretaceous. Leaching in the proximal portion of the freshwater aquifer produced excellent limestone reservoir rocks in the updip Smackover. Dolomitization in the contemporaneous downdip mixed connate/freshwater zone formed dolostone reservoir rocks with depleted isotopic compositions consistent with a shallow-burial mixed-water origin.« less

[Hydrological characteristics of calcareous soil with contrasting architecture on dolomite slope of Northwest Guangxi].

PubMed

Zhang, Xing; Wang, Ke Lin; Fu, Zhi Yong; Chen, Hong Song; Zhang, Wei; Shi, Zhi Hua

2017-07-18

The traditional hydrology method, stable hydrogen and oxygen isotope technology, and rainfall simulation method were combined to investigate the hydrological function of small experimental plots (2 m×1.2 m) of contrasting architecture in Northwest Guangxi dolomite area. There were four typical catenary soils along the dolomite peak-cluster slope, which were the whole-sand, up-loam and down-sand, the whole loam, up-clay and down-sand soil types, respectively. All the experimental plots generated little amounts of overland runoff and had a high surface infiltration rate, ranging from 41 to 48 mm·h -1 , and the interflow and deep percolation were the dominant hydrological progress. The interflow was classified into interflow in soil clay A and C according to soil genetic layers. For interflow in soil clay A, matrix flow was generated from the whole-sand, up-loam and down-sand, up-clay and down-sand soil types, but preferential flow dominated in the whole-loam soil type. As for interflow in soil clay C, preferential flow dominated in the whole-loam, up-clay and down-sand, up-loam and down-sand soil types. The soils were shallow yet continuously distributed along the dolomite slope. The difference of hydrological characteristics in soil types with different architectures mainly existed in the runoff generation progress of each interface underground. It proved that the a 3-D perspective was needed to study the soil hydrological functions on dolomite slope of Northwest Guangxi, and a new way paying more attention on underground hydrological progress should be explored to fully reveal the near-surface hydrological processes on karst slope.

The use of karst geomorphology for planning, hazard avoidance and development in Great Britain

NASA Astrophysics Data System (ADS)

Cooper, Anthony H.; Farrant, Andrew R.; Price, Simon J.

2011-11-01

Within Great Britain five main types of karstic rocks - dolomite, limestone, chalk, gypsum and salt - are present. Each presents a different type and severity of karstic geohazard which are related to the rock solubility and geological setting. Typical karstic features associated with these rocks have been databased by the British Geological Survey (BGS) with records of sinkholes, cave entrances, stream sinks, resurgences and building damage; data for more than half of the country has been gathered. BGS has manipulated digital map data, for bedrock and superficial deposits, with digital elevation slope models, superficial deposit thickness models, the karst data and expertly interpreted areas, to generate a derived dataset assessing the likelihood of subsidence due to karst collapse. This dataset is informed and verified by the karst database and marketed as part of the BGS GeoSure suite. It is currently used by environmental regulators, the insurance and construction industries, and the BGS semi-automated enquiry system. The database and derived datasets can be further combined and manipulated using GIS to provide other datasets that deal with specific problems. Sustainable drainage systems, some of which use soak-aways into the ground, are being encouraged in Great Britain, but in karst areas they can cause ground stability problems. Similarly, open loop ground source heat or cooling pump systems may induce subsidence if installed in certain types of karstic environments such as in chalk with overlying sand deposits. Groundwater abstraction also has the potential to trigger subsidence in karst areas. GIS manipulation of the karst information is allowing Great Britain to be zoned into areas suitable, or unsuitable, for such uses; it has the potential to become part of a suite of planning management tools for local and National Government to assess the long term sustainable use of the ground.

Karst flash floods: an example from the Dinaric karst (Croatia)

NASA Astrophysics Data System (ADS)

Bonacci, O.; Ljubenkov, I.; Roje-Bonacci, T.

2006-03-01

Flash floods constitute one of the deadliest and costliest natural disasters worldwide. This paper explains the karst flash flood phenomenon, which represents a special kind of flash flood. As the majority of flash floods karst flash floods are caused by intensive short-term precipitation in an area whose surface rarely exceeds a few square kilometres. The characteristics of all flash floods are their short duration, small areal extent, high flood peaks and rapid flows, and heavy loss of life and property. Karst flash floods have specific characteristics due to special conditions for water circulation, which exist in karst terrains. During karst flash floods a sudden rise of groundwater levels occurs, which causes the appearance of numerous, unexpected, abundant and temporary karst springs. This paper presents in detail an example of a karst flash flood in the Marina bay (Dinaric karst region of Croatia), which occurred in December 2004.

Case History: Merging the Tools of DC Resistivity and Fracture Trace Analysis for Locating High Yield Domestic Water Wells in Karst Terrain, Shenandoah Valley, Virginia, USA

NASA Astrophysics Data System (ADS)

Frangos, W.; Eaton, L. S.

2004-05-01

, suggesting underground voids. This knowledge could serve as a future guide for both well placement and for site evaluation of the potential for sinkhole occurrence. The second site is located 5 km due south of the Barth Farm. A potential residential and farm operations site was being evaluated for construction based on the availability of adequate water yield. Previous attempts of drilling on a contiguous property resulted in a fruitless 800 ft dry hole. The site is mapped as folded sedimentary rock (limestone, dolomite, shale), but outcrops are masked by ~25 m thick alluvial deposits of quartzite gravel and sand. The presence of numerous sinkholes and ponds suggests karst terrain. Fracture trace analysis was initially conducted to identify zones that may contain water-bearing conduits. A dipole-dipole DC resistivity survey followed in areas specifically delineated by the fracture trace analysis. The results lead to two strong wells, one producing 60-100 gpm at 286 ft deep, and the second well 40 gpm at 395 ft. Based on the previous drilling difficulty in this terrain, the complementary tools of high-resolution resistivity and fracture trace analysis are effective in locating high-yield water wells in karst environments. In the first case, the shallow aquifer was detected directly by the resistivity and indirectly by photo interpretation; in the second, both methods provided indirect evidence. The combined use of near-surface indications of underlying karst reservoirs is recommended for future exploration work.

Hochauflösendes Monitoring von Karst-Grundwasserressourcen beiderseits des Jordangrabens - Konzepte und Anwendungsbeispiele

NASA Astrophysics Data System (ADS)

Schmidt, Sebastian; Grimmeisen, Felix; Ries, Fabian; Goldscheider, Nico; Sauter, Martin

2018-03-01

In the semi-arid eastern Mediterranean water supply is highly dependent on karst aquifers. The region is characterized by multi-year dry and wet cycles combined with high hydrological dynamics, especially during intense precipitation events. The investigated karst regions in the West Bank and Jordan are experiencing strong urbanization within the groundwater catchments and hence a rising impact on water quality. Therefore, high resolution monitoring data are required for the assessment of available water resources and the hydrogeological characterization of the karst systems. These measurements are focused on the (natural) meteorological input signals and the system output signals at the karst springs. Also soil moisture and ephemeral runoff dynamics are investigated. The monitoring data enable (1) hydrogeological characterization of the aquifers, (2) estimation of groundwater recharge via soil water balance and reservoir models, and (3) assessment of contamination dynamics in groundwater (e. g. nitrate and E. coli concentrations), allowing an optimized raw water management. Several examples illustrate the importance of high-resolution hydrological monitoring data.

Karst development and speleogenesis, Isla de Mona, Puerto Rico

USGS Publications Warehouse

Frank, E.F.; Mylroie, J.; Troester, J.; Alexander, E.C.; Carew, J.L.

1998-01-01

Isla de Mona consists of a raised table-top Miocene-Pliocene reef platform bounded on three sides by vertical cliffs, up to 80 m high. Hundreds of caves ring the periphery of the island and are preferentially developed in, but not limited to, the Lirio Limestone/Isla de Mona Dolomite contact. These flank margin caves originally formed at sea level and are now exposed at various levels by tectonic uplift of the island (Franbk 1983; Mylroie et al. 1995b). Wall cusps, a characteristic feature of flank margin caves, are ubiquitois features. Comparisons among similar caves formed in the Bahamas and Isla de Mona reveal the same overall morphology throughout the entire range of sizes and complexities. The coincidence of the primary cave development zone with the Lirio Limestone/Isla de Mona Dolomite contact may result from syngenetic speleogenesis and dolomitization rather than preferential dissolution along a lithologic boundary. Tectonic uplift and glacioeustatic sea level fluctuations produced caves at a variety of elevations. Speleothem dissolution took place in many caves under phreatic conditions, evidence these caves were flooded after an initial period of subaerial exposure and speleothem growth. Several features around the perimeter of the island are interpreted to be caves whose roofs were removed by surficial denudation processes. Several large closed depressions and dense pit cave fields are further evidence of surficial karst features. The cliff retreat around the island perimeter since the speleogenesis of the major cave systems is small based upon the distribution of the remnant cave sections.

U.S. Geological Survey Karst Interest Group Proceedings, Bowling Green, Kentucky, May 27-29, 2008

USGS Publications Warehouse

Kuniansky, Eve L.

2008-01-01

*INTRODUCTION AND ACKNOWLEDGMENTS* Karst aquifer systems are present throughout parts of the United States and some of its territories. The complex depositional environments that form carbonate rocks combined with post-depositional tectonic events and the diverse climatic regimes under which these rocks were formed result in unique hydrologic systems. The dissolution of calcium carbonate and the subsequent development of distinct and beautiful landscapes, caverns, and springs have resulted in some karst areas of the United States being designated as national or state parks and commercial caverns. Karst aquifers and landscapes that form in tropical areas, such as the north coast of Puerto Rico, differ greatly from karst areas in more arid climates, such as central Texas or western South Dakota. Many of these public and private lands contain unique flora and fauna associated with the hydrologic systems in these karst areas. As a result, multiple Federal, State, and local agencies have an interest in the study of karst terrains. Carbonate sediments and rocks (limestone and dolomite) are composed of greater than 50 percent carbonate minerals and the predominant carbonate mineral is calcium carbonate or limestone (CaCO3). Unlike terrigenous clastic sedimentation, the depositional processes that produce carbonate rocks are complex, involving both biological and physical processes. These depositional processes impact greatly the development of permeability of the sediments. Carbonate minerals readily dissolve or precipitate depending on the chemistry of the water flowing through the rock, thus the study of both marine and meteoric diagenesis of carbonate sediments is multidisciplinary. Even with a better understanding of the depositional environment and subsequent diagenesis, the dual porosity nature of karst aquifers presents challenges to scientists attempting to study ground-water flow and contaminant transport. Many of the major springs and aquifers in the United

Evaluating susceptibility of karst dolines (sinkholes) for collapse in Sango, Tennessee, USA.

PubMed

Siska, Peter P; Goovaerts, Pierre; Hung, I-K

2016-08-01

Dolines or sinkholes are earth depressions that develop in soluble rocks complexes such as limestone, dolomite, gypsum, anhydrite, and halite; dolines appear in a variety of shapes from nearly circular to complex structures with highly curved perimeters. The occurrence of dolines in the studied karst area is not random; they are the results of geomorphic, hydrologic, and chemical processes that have caused partial subsidence, even the total collapse of the land surface when voids and caves are present in the bedrock and the regolith arch overbridging these voids is unstable. In the study area, the majority of collapses occur in the regolith (bedrock cover) that bridges voids in the bedrock. Because these collapsing dolines may result in property damage and even cause the loss of lives, there is a need to develop methods for evaluating karst hazards. These methods can then be used by planners and practitioners for urban and economic development, especially in regions with a growing population. The purpose of this project is threefold: 1) to develop a karst feature database, 2) to investigate critical indicators associated with doline collapse, and 3) to develop a doline susceptibility model for potential doline collapse based on external morphometric data. The study has revealed the presence of short range spatial dependence in the distribution of the dolines' morphometric parameters such as circularity, the geographic orientation of the main doline axes, and the length-to-width doline ratios; therefore, geostatistics can be used to spatially evaluate the susceptibility of the karst area for doline collapse. The partial susceptibility estimates were combined into a final probability map enabling the identification of areas where, until now, undetected dolines may cause significant hazards.

Evidence of Multi-Component Ion Exchange in Dolomite Formation during Low Salinity Waterflooding

NASA Astrophysics Data System (ADS)

Srisuriyachai, Falan; Meekangwal, Suthida

2017-12-01

Low salinity waterflooding is a technique performed in many oil reservoirs around the globe. The technique is simply implemented by injecting water with very low ionic activity compared to formation water into an injection well. The injected water will increase reservoir pressure that is compulsory to drive oil moving toward production well. More than just maintaining reservoir pressure as obtained from conventional waterflooding, low salinity water creates shifting of surface condition, resulting in additional amount of liberated oil. Nevertheless, exact oil recovery mechanisms are still discussed. Among these proposed mechanisms, Multi-component Ion Exchange (MIE) together with wettability alteration is believed to be a major mechanism leading to higher oil recovery compared to conventional waterflooding. In this study, detection of calcium and magnesium ions which are Potential Determining Ions (PDI) for carbonate reservoirs are detected during the coreflood experiment. Dolomite rock sample is used to represent carbonate formation and detection of previously mentioned ions is performed by complexometric titration of the effluents. From the study, it is observed that during conventional waterflooding and low salinity waterflooding at low temperature of 30 degrees Celsius, calcium and magnesium ions in the produced water is increased compared to the amount of these ions in the injected water. This incremental of ions can be explained by the dissolution of calcium and magnesium from dolomite which is chemically composed of calcium magnesium carbonate. At this temperature, the portion of calcium ion is always less than magnesium ion even though the amount of calcium ion is higher than magnesium ion in injected water. However, at higher temperatures which are 50 and 70 degrees Celsius, ratio of calcium and magnesium ions in injected and produced water is reversed. Disappearance of magnesium ion in the effluent is more obvious especially at 70 degrees Celsius and by

Ferroan dolomites in Miocene sediments of the Xisha Islands and their genetic model

NASA Astrophysics Data System (ADS)

Xu, Hong; Zhang, Weiwei; Wei, Kai; He, Qingkun; Jiang, Yunshui; Xu, Tingting; Jiang, Xuejun; Yan, Guijing; Song, Hongying; Wang, Jianghai

2018-01-01

Carbonate rocks are important reservoirs for global petroleum exploration. The largest oilfield in the South China Sea, Liuhua 11-1, is distributed in the massive carbonate reef area of the Zhujiang (Pearl) River Mouth Basin. Previous studies showed that one 802.17-m-long core from well Xichen-1 in the South China Sea mainly consisted of white and light gray-white organic reefs. Recently, a Miocene whole core (161.9 m long) of well Xiyong-2, near well Xichen-1, was found to contain six layers of yellowish brown, light yellowish gray, iron black, or light yellowish gray-white organic reefs. Scanning electron microscope images of these layers reveal a typical ferroan dolomite rich in Fe (up to 29%), with the high concentrations of Mn, Cu, W, Zn, Cr, Ni, and Co. Systematic X-ray powder diffraction analysis yields a 1.9-6.1 match in phase ratio with ankerite, 5.4-26.9 with dolomite, and zero with calcite, which indicate that the samples can be classified as ferroan dolomite. The iron and heavy metals are inferred to be originated from multiple volcanic eruptions of Gaojianshi Island in the Dongdao Atoll during the middle-late Miocene. These elements were dissolved in seawater, likely as a sol, and carried to Yongxing Island in the Xuande Atoll by sea currents and tides enhanced by prevailing winds, and deposited as a part of the sedimentation process in the study area. The ferroan dolomite has Sr content of (125-285)×10-6, which is lower than the accepted Sr boundary value of dolomite. This finding suggests that dolomitization occurred during large-scale global glacial regression in the late Miocene. The isolated Xisha carbonate platform, exposed to air, underwent freshwater leaching and dolomitization induced by mixed water, and caused the extensive Fe-Mg exchange along the organic reef profile to form ankerite and ferroan dolomite. These results may help to understand paleoceanographic environmental changes in the South China Sea during the Miocene.

Spontaneous transition of replacive to displacive growth of dolomite in burial dolomitization, and of serpentine in serpentinization

NASA Astrophysics Data System (ADS)

Merino, E.; Canals, A.

2011-12-01

Burial dolostones consist of huge volumes of dolomite that has replaced limestone volume for volume, with patches < 10 meters across of thin, equidistant "zebra" veins that are displacive. Characteristically, the contact between the two dolomite types is, under the microscope, seamless. This has long puzzled carbonate petrologists, who have mistaken the displacive dolomite veins for "void-filling cements" and therefore expect a sharp contact between the two dolomite types. The replacive dolomite forms not by dissolution-precipitation as usually assumed, but by dolomite-growth-driven pressure solution of the host calcite -- if the host is sufficiently viscous, or rigid. The local stress induced by the dolomite growth self-adjusts automatically so as to force the rates of dolomite growth and calcite pressure-solution to be mutually equal at each moment of the replacement. That is why replacement is always isovolumetric. But the dolomite-for-calcite replacement is self-accelerating via Ca2+ (each replacement increment releases Ca2+, which increases the activity product for dolomite and thus the rate of the next replacement increment, and so on), and crystalline carbonates are non-newtonian solids of the softening kind (as shown experimentally, Heard & Raleigh 1972). Thus, when the dolomite-for-calcite replacement becomes fast enough to reduce the local rock viscosity sufficiently, and if aqueous Mg2+ has not run out by then, the replacive growth will inevitably, and seamlessly, transition to displacive growth. This is when incipient zebra veins start to form. Each vein interacts with its neighbors via the induced stress they exert on each other, which leads to a "weeding" feedback that pressure dissolves some veins (the ones that find themselves too close to their neighbors), leaving the surviving ones more equidistant than before. Dolomitic zebra veins, or "rhythmites", are a good example of syntaxial veins. The same process and feedbacks, via Mg2+ instead of via Ca2

Soil nutrients and stoichiometric ratios as affected by land use and lithology at county scale in a karst area, southwest China.

PubMed

Wang, Miaomiao; Chen, Hongsong; Zhang, Wei; Wang, Kelin

2018-04-01

Soil carbon (C), nitrogen (N), and phosphorus (P) are the main soil nutrients required for plant development and their stoichiometric ratios are important indicators of ecosystem functions. However, there have been few studies on the effects of land use and lithology on soil nutrients and stoichiometric ratios, especially in karst areas with extremely fragile geology and intensive human disturbance. To evaluate the synergistic effect of land use and lithology, soil samples at depth of 0-15cm were collected from five land-use types (arable land, plantation forest, grassland, shrubland, and secondary forest) over three lithologies (karst dolomite and limestone and non-karst clasolite) in a typical karst area in southwest China. For natural succession, grassland, shrubland, and secondary forest corresponded to the early, middle, and late successional stage after agricultural abandonment, while from arable land to plantation forest can be treated as a manual reversion after agricultural abandonment. The results showed that, in dolomite, soil organic C (SOC) and total N (TN) increased continuously with natural succession and increased in plantation forest compared to arable land. Total P (TP) continued to decrease from arable land to grassland and then to shrubland. In limestone, SOC and TN did not follow the same pattern because SOC and TN were slightly higher in grassland than shrubland, while TN was slightly lower in plantation forest compared to arable land. TP was remarkably higher in arable land than the other land-use types. For clasolite, SOC was highest in grassland, while TN was not significantly different among land-use types. Compared to arable land, TP was lower in other types of land use. These soil nutrient characteristics led to various stoichiometric ratios under the five land-use types over different lithologies. Therefore, ecological restoration projects based on land use conversion should consider differences in regional lithology and human

Microbial diversity and impact on carbonate geochemistry across a changing geochemical gradient in a karst aquifer.

PubMed

Gray, Cassie J; Engel, Annette S

2013-02-01

Although microbes are known to influence karst (carbonate) aquifer ecosystem-level processes, comparatively little information is available regarding the diversity of microbial activities that could influence water quality and geological modification. To assess microbial diversity in the context of aquifer geochemistry, we coupled 16S rRNA Sanger sequencing and 454 tag pyrosequencing to in situ microcosm experiments from wells that cross the transition from fresh to saline and sulfidic water in the Edwards Aquifer of central Texas, one of the largest karst aquifers in the United States. The distribution of microbial groups across the transition zone correlated with dissolved oxygen and sulfide concentration, and significant variations in community composition were explained by local carbonate geochemistry, specifically calcium concentration and alkalinity. The waters were supersaturated with respect to prevalent aquifer minerals, calcite and dolomite, but in situ microcosm experiments containing these minerals revealed significant mass loss from dissolution when colonized by microbes. Despite differences in cell density on the experimental surfaces, carbonate loss was greater from freshwater wells than saline, sulfidic wells. However, as cell density increased, which was correlated to and controlled by local geochemistry, dissolution rates decreased. Surface colonization by metabolically active cells promotes dissolution by creating local disequilibria between bulk aquifer fluids and mineral surfaces, but this also controls rates of karst aquifer modification. These results expand our understanding of microbial diversity in karst aquifers and emphasize the importance of evaluating active microbial processes that could affect carbonate weathering in the subsurface.

Microbial diversity and impact on carbonate geochemistry across a changing geochemical gradient in a karst aquifer

PubMed Central

Gray, Cassie J; Engel, Annette S

2013-01-01

Although microbes are known to influence karst (carbonate) aquifer ecosystem-level processes, comparatively little information is available regarding the diversity of microbial activities that could influence water quality and geological modification. To assess microbial diversity in the context of aquifer geochemistry, we coupled 16S rRNA Sanger sequencing and 454 tag pyrosequencing to in situ microcosm experiments from wells that cross the transition from fresh to saline and sulfidic water in the Edwards Aquifer of central Texas, one of the largest karst aquifers in the United States. The distribution of microbial groups across the transition zone correlated with dissolved oxygen and sulfide concentration, and significant variations in community composition were explained by local carbonate geochemistry, specifically calcium concentration and alkalinity. The waters were supersaturated with respect to prevalent aquifer minerals, calcite and dolomite, but in situ microcosm experiments containing these minerals revealed significant mass loss from dissolution when colonized by microbes. Despite differences in cell density on the experimental surfaces, carbonate loss was greater from freshwater wells than saline, sulfidic wells. However, as cell density increased, which was correlated to and controlled by local geochemistry, dissolution rates decreased. Surface colonization by metabolically active cells promotes dissolution by creating local disequilibria between bulk aquifer fluids and mineral surfaces, but this also controls rates of karst aquifer modification. These results expand our understanding of microbial diversity in karst aquifers and emphasize the importance of evaluating active microbial processes that could affect carbonate weathering in the subsurface. PMID:23151637

Hydrological response of karst systems to large-scale climate variability for different catchments of the French karst observatory network INSU/CNRS SNO KARST

NASA Astrophysics Data System (ADS)

Massei, Nicolas; Labat, David; Jourde, Hervé; Lecoq, Nicolas; Mazzilli, Naomi

2017-04-01

The french karst observatory network SNO KARST is a national initiative from the National Institute for Earth Sciences and Astronomy (INSU) of the National Center for Scientific Research (CNRS). It is also part of the new french research infrastructure for the observation of the critical zone OZCAR. SNO KARST is composed by several karst sites distributed over conterminous France which are located in different physiographic and climatic contexts (Mediterranean, Pyrenean, Jura mountain, western and northwestern shore near the Atlantic or the English Channel). This allows the scientific community to develop advanced research and experiments dedicated to improve understanding of the hydrological functioning of karst catchments. Here we used several sites of SNO KARST in order to assess the hydrological response of karst catchments to long-term variation of large-scale atmospheric circulation. Using NCEP reanalysis products and karst discharge, we analyzed the links between large-scale circulation and karst water resources variability. As karst hydrosystems are highly heterogeneous media, they behave differently across different time-scales : we explore the large-scale/local-scale relationships according to time-scales using a wavelet multiresolution approach of both karst hydrological variables and large-scale climate fields such as sea level pressure (SLP). The different wavelet components of karst discharge in response to the corresponding wavelet component of climate fields are either 1) compared to physico-chemical/geochemical responses at karst springs, or 2) interpreted in terms of hydrological functioning by comparing discharge wavelet components to internal components obtained from precipitation/discharge models using the KARSTMOD conceptual modeling platform of SNO KARST.

Evaluating susceptibility of karst dolines (sinkholes) for collapse in Sango, Tennessee, USA

PubMed Central

Siska, Peter P.; Goovaerts, Pierre; Hung, I-K

2016-01-01

Dolines or sinkholes are earth depressions that develop in soluble rocks complexes such as limestone, dolomite, gypsum, anhydrite, and halite; dolines appear in a variety of shapes from nearly circular to complex structures with highly curved perimeters. The occurrence of dolines in the studied karst area is not random; they are the results of geomorphic, hydrologic, and chemical processes that have caused partial subsidence, even the total collapse of the land surface when voids and caves are present in the bedrock and the regolith arch overbridging these voids is unstable. In the study area, the majority of collapses occur in the regolith (bedrock cover) that bridges voids in the bedrock. Because these collapsing dolines may result in property damage and even cause the loss of lives, there is a need to develop methods for evaluating karst hazards. These methods can then be used by planners and practitioners for urban and economic development, especially in regions with a growing population. The purpose of this project is threefold: 1) to develop a karst feature database, 2) to investigate critical indicators associated with doline collapse, and 3) to develop a doline susceptibility model for potential doline collapse based on external morphometric data. The study has revealed the presence of short range spatial dependence in the distribution of the dolines’ morphometric parameters such as circularity, the geographic orientation of the main doline axes, and the length-to-width doline ratios; therefore, geostatistics can be used to spatially evaluate the susceptibility of the karst area for doline collapse. The partial susceptibility estimates were combined into a final probability map enabling the identification of areas where, until now, undetected dolines may cause significant hazards. PMID:27616807

Agriculture and Karst in Kentucky

USDA-ARS?s Scientific Manuscript database

This publication describes the unique hydrologic and environmental issues found in karst environments. The publication describes karst landscapes, the importance of karst, different types of karst features, and how water moves through karst landscapes. The publication includes details on methods for...

A urolith of biogenic dolomite - another clue in the dolomite mystery

NASA Astrophysics Data System (ADS)

Mansfield, Charles F.

1980-06-01

A male Dalmatian, Canis familiaris, produced uroliths of almost pure dolomite, 3-8 mm across, in his urinary bladder in less than 8 months at 38°C and about 1 atm. The X-ray diffractogram identified the predominant mineral as dolomite, and the sharp (01.5) peak showed it is ordered dolomite, not the disordered form, protodolomite. Geochemically and biologically plausible causes include (1) renal, respiratory, or metabolic alkalosis, (2) infection by urease-producing (urea-splitting) fungi or bacteria and (3) infection by uric acid-fermenting bacteria. Hematological, bacteriological, urological and geochemical considerations most strongly implicate infection by either anaerobic, urease-producing bacteria or anaerobic, uric acid-fermenting bacteria. The physical and chemical conditions of this urinary system more closely approximate modern and inferred ancient carbonate depositional settings than most previous laboratory experiments, especially in terms of temperature, pressure, total salinity and, possibly, biota. The presence of urease-producing and/or uric acid-fermenting bacteria in urea- and/or acid-containing sediment, such as fecal pellets and algal mats, could promote formation of authigenic dolomite or other carbonates.

Reaction kinetics of dolomite rim growth

NASA Astrophysics Data System (ADS)

Helpa, V.; Rybacki, E.; Abart, R.; Morales, L. F. G.; Rhede, D.; Jeřábek, P.; Dresen, G.

2014-04-01

Reaction rims of dolomite (CaMg[CO3]2) were produced by solid-state reactions at the contacts of oriented calcite (CaCO3) and magnesite (MgCO3) single crystals at 400 MPa pressure, 750-850 °C temperature, and 3-146 h annealing time to determine the reaction kinetics. The dolomite reaction rims show two different microstructural domains. Elongated palisades of dolomite grew perpendicular into the MgCO3 interface with length ranging from about 6 to 41 µm. At the same time, a 5-71 µm wide rim of equiaxed granular dolomite grew at the contact with CaCO3. Platinum markers showed that the original interface is located at the boundary between the granular and palisade-forming dolomite. In addition to dolomite, a 12-80 µm thick magnesio-calcite layer formed between the dolomite reaction rims and the calcite single crystals. All reaction products show at least an axiotactic crystallographic relationship with respect to calcite reactant, while full topotaxy to calcite prevails within the granular dolomite and magnesio-calcite. Dolomite grains frequently exhibit growth twins characterized by a rotation of 180° around one of the equivalent axis. From mass balance considerations, it is inferred that the reaction rim of dolomite grew by counter diffusion of MgO and CaO. Assuming an Arrhenius-type temperature dependence, activation energies for diffusion of CaO and MgO are E a (CaO) = 192 ± 54 kJ/mol and E a (MgO) = 198 ± 44 kJ/mol, respectively.

Microbial precipitation of dolomite in methanogenic groundwater

USGS Publications Warehouse

Roberts, Jennifer A.; Bennett, Philip C.; Gonzalez, Luis A.; Macpherson, G.L.; Milliken, Kitty L.

2004-01-01

We report low-temperature microbial precipitation of dolomite in dilute natural waters from both field and laboratory experiments. In a freshwater aquifer, microorganisms colonize basalt and nucleate nonstoichiometric dolomite on cell walls. In the laboratory, ordered dolomite formed at near-equilibrium conditions from groundwater with molar Mg:Ca ratios of <1; dolomite was absent in sterile experiments. Geochemical and microbiological data suggest that methanogens are the dominant metabolic guild in this system and are integral to dolomite precipitation. We hypothesize that the attached microbial consortium reacts with the basalt surface, releasing Mg and Ca into solution, which drives dolomite precipitation via nucleation on the cell wall. These findings provide insight into the long-standing dolomite problem and suggest a fundamental role for microbial processes in the formation of dolomite across a wide range of environmental conditions.

A new species of karst forest Bent-toed Gecko (genus Cyrtodactylus Gray) not yet threatened by foreign cement companies and a summary of Peninsular Malaysia's endemic karst forest herpetofauna and the need for its conservation.

PubMed

Grismer, L Lee; Wood, P L Jr; Anuar, Shahrul; Davis, H R; Cobos, A J; Murdoch, M L

2016-01-04

A new species of Bent-toed Gecko, Cyrtodactylus gunungsenyumensis sp. nov. of the sworderi complex, is described from Hutan Lipur Gunung Senyum, Pahang, Peninsular Malaysia and is differentiated from all other species in the sworderi complex by having a unique combination of characters including a maximum SVL of 74.7 mm; low, rounded, weakly keeled, body tubercles; 34-40 paravertebral tubercles; weak ventrolateral body fold lacking tubercles; 38-41 ventral scales; an abrupt transition between the posterior and ventral femoral scales; 20-23 subdigital lamellae on the fourth toe; enlarged femoral scales; no femoral or precloacal pores; no precloacal groove; wide caudal bands; and an evenly banded dorsal pattern. Cyrtodactylus gunungsenyumensis sp. nov. is a scansorial, karst forest-adapted specialist endemic to the karst ecosystem surrounding Gunung Senyum and occurs on the vertical walls of the limestone towers as well as the branches, trunks, and leaves of the vegetation in the associated karst forest. Cyrtodactylus gunungsenyumensis sp. nov. is the seventh species of karst forest-adapted Cyrtodactylus and the sixteenth endemic species of karst ecosystem reptile discovered in Peninsular Malaysia in the last seven years from only 12 different karst forests. This is a clear indication that many species remain to be discovered in the approximately 558 isolated karst ecosystems in Peninsular Malaysia not yet surveyed. These data continue to underscore the importance of karst ecosystems as reservoirs of biodiversity and microendemism and that they constitute an important component of Peninsular Malaysia's natural heritage and should be protected from the quarrying interests of foreign industrial companies.

Drilling the Mediterranean Messinian Evaporites to Answer Key Questions Related to Massive Microbial Dolomite Formation under Hypersaline Alkaline Conditions

NASA Astrophysics Data System (ADS)

McKenzie, Judith A.; Bontognali, Tomaso R. R.; Vasconcelos, Crisogono

2014-05-01

dolomite precipitation has been studied extensively in rare modern environments, such as the arid coastal sabkhas of Abu Dhabi, UAE and the hypersaline coastal lagoons in Brazil. However, extrapolation of these studies of relatively limited aerial extent to interpret larger-scale, ancient dolomite formation of putative evaporitic origin remains elusive. Such ancient micritic dolomite formations with associated micro-porosity represent extremely valuable hydrocarbon reservoirs. Therefore, a comprehensive investigation of a relatively recent micritic dolomite deposit that has not experienced extensive burial depths and diagenesis is essential to extend our understanding of these important reservoir systems. Based on the limited data obtained during drilling at DSDP Site 374: Messina Abyssal Plain, the dolomitic mudstones of the uppermost Messinian evaporite complex represent an ideal candidate for such an extensive study in a "natural laboratory". Thus, to increase our understanding of the biogeochemical processes associated with ancient massive dolomite formation, we propose to document the scientific objectives to support a major new drilling campaign to study the sub-seafloor Messinian evaporite complex in the deep Mediterranean basins, using greatly enhanced drilling technology that is currently available within the new International Ocean Discovery Program (IODP). Hsü, K., Montadert, L. et al., 1978. Initial Reports of the Deep Sea Drilling Project, Volume 42, Part 1: Washington (U.S. Government Printing Office).

Early dolomitization in the Lower Cretaceous shallow-water carbonates of Southern Apennines (Italy): Clues about palaeoclimatic fluctuations in western Tethys

NASA Astrophysics Data System (ADS)

Vinci, Francesco; Iannace, Alessandro; Parente, Mariano; Pirmez, Carlos; Torrieri, Stefano; Giorgioni, Maurizio

2017-12-01

diagenetic dolomite may be used as proxy to define the climatic fluctuations that have influenced the sedimentary dynamics in the Early Cretaceous. Moreover, considering that a comparable early dolomite distribution is present also in the Dinaric Platform, we suggest that a regional scale climate control acted on early dolomite formation and distribution. Refining the knowledge of such a key control may have a significative impact on hydrocarbon reservoir characterization and exploration in the Periadriatic area.

Comparing and refining karst disturbance index methods through application in an island karst setting

NASA Astrophysics Data System (ADS)

Porter, Brandon L.; North, Leslie A.; Polk, Jason S.

2016-12-01

The interconnected nature of surface and subsurface karst environments allows easy disturbance to their aquifers and specialized ecosystems from anthropogenic impacts. The karst disturbance index is a holistic tool used to measure disturbance to karst environments and has been applied and refined through studies in Florida and Italy, among others. Through these applications, the karst disturbance index has evolved into two commonly used methods of application; yet, the karst disturbance index is still susceptible to evaluation and modification for application in other areas around the world. The geographically isolated and highly vulnerable municipality of Arecibo, Puerto Rico's karst area provides an opportunity to test the usefulness and validity of the karst disturbance index in an island setting and to compare and further refine the application of the original and modified methods. This study found the both methods of karst disturbance index application resulted in high disturbance scores (Original Method 0.54 and Modified Method 0.69, respectively) and uncovered multiple considerations for the improvement of the karst disturbance index. An evaluation of multiple methods together in an island setting also resulted in the need for adding additional indicators, including Mogote Removal and Coastal Karst. Collectively, the results provide a holistic approach to using the karst disturbance index in an island karst setting and suggest a modified method by which scaling and weighting may compensate for the difference between the original and modified method scores and allow interested stakeholders to evaluate disturbance regardless of his or her level of expertise.

Hydrothermal dolomitization of the Bekhme formation (Upper Cretaceous), Zagros Basin, Kurdistan Region of Iraq: Record of oil migration and degradation

NASA Astrophysics Data System (ADS)

Mansurbeg, Howri; Morad, Daniel; Othman, Rushdy; Morad, Sadoon; Ceriani, Andrea; Al-Aasm, Ihsan; Kolo, Kamal; Spirov, Pavel; Proust, Jean Noel; Preat, Alain; Koyi, Hemin

2016-07-01

The common presence of oil seepages in dolostones is widespread in Cretaceous carbonate successions of the Kurdistan Region of Iraq. This integrated field, petrographic, chemical, stable C, O and Sr isotopes, and fluid inclusion study aims to link dolomitization to the origin and geochemical evolution of fluids and oil migration in the Upper Cretaceous Bekhme carbonates. Flux of hot basinal (hydrothermal) brines, which is suggested to have occurred during the Zagros Orogeny, resulted in dolomitization and cementation of vugs and fractures by coarse-crystalline saddle dolomite, equant calcite and anhydrite. The saddle dolomite and host dolostones have similar stable isotopic composition and formed prior to oil migration from hot (81-115 °C) basinal NaCl-MgCl2-H2O brines with salinities of 18-22 wt.% NaCl eq. The equant calcite cement, which surrounds and hence postdates saddle dolomite, has precipitated during oil migration from cooler (60-110 °C) NaCl-CaCl2-H2O brines (14-18 wt.% NaCl eq). The yellowish fluorescence color of oil inclusions in the equant calcite indicates that the oil had API gravity of 15-25° composition, which is lighter than present-day oil in the reservoirs (API of 10-17°). This difference in oil composition is attributed to oil degradation by the flux of meteoric water, which is evidenced by the low δ13C values (- 8.5‰ to - 3.9‰ VPDB) as well as by nil salinity and low temperature in fluid inclusions of late columnar calcite cement. This study demonstrates that linking fluid flux history and related diagenesis to the tectonic evolution of the basin provides important clues to the timing of oil migration, degradation and reservoir evolution.

Chemical composition and strength of dolomite geopolymer composites

NASA Astrophysics Data System (ADS)

Aizat, E. A.; Al Bakri, A. M. M.; Liew, Y. M.; Heah, C. Y.

2017-09-01

The chemical composition of dolomite and the compressive strength of dolomite geopolymer composites were studied. The both composites prepared with mechanical mixer manufactured by with rotor speed of 350 rpm and curing in the oven for 24 hours at 80˚C. XRF analysis showThe dolomite raw materials contain fewer amounts of Si and Al but high Ca in its composition. Dolomite geopolymer composites with 20M of NaOH shows greater and optimum compressive strength compared to dolomite geopolymer with other NaOH molarity. This indicated better interaction of dolomite raw material and alkaline activator need high molarity of NaOH in order to increase the reactivity of dolomite.

Model for dolomite formation in northwest Florida

USGS Publications Warehouse

Cooper, C.R.; Tindall, J.A.

1994-01-01

Petrographic methods are used to examine the nature of the Floridan post-Oligocene unconformity and diagenetic responses in the associated carbonate units. The study addresses the depositional environment and the character of sediments associated with the unconformity, types and timing of diagenetic changes, and mode of dolomitization for the Suwannee Limestone dolomites and basal Hawthorn Group dolosilts. The purpose of the study is to determine if the original texture of geologic materials is preserved more frequently in rocks deposited in a supratidal environment in the uppermost Floridan carbonates, to examine possible sources of magnesium for the dolomitization that has occurred in the Floridan aquifer, and to determine the chemical environment of dolomite formation. On the basis of lithology, the tri-county study area can be divided into two regions; one in which the uppermost Floridan carbonate is calcareous or locally silicified, and one in which the aquifer system is capped with dolomite. Lateral interfingering between the two regions is apparent, and it is inferred that the boundary between the limestone and dolomite represents a geochemical boundary between a mixed marine and freshwater environment and a subaerially exposed freshwater environment. Where dolomite has replaced the uppermost Suwannee Limestone, the dolomite is overlain by a thin unit of dolosilt. The predominant source of magnesium for the dolomitization that occurred in the study area is probably seawater. ?? 1994.

Recent Trends in Karst Geomorphology.

ERIC Educational Resources Information Center

Palmer, Arthur N.

1984-01-01

Recent trends related to the karst processes and the evolution of karst landscapes are discussed. The hydrochemical processes responsible for the origin of karst are expanded on to illustrate the present scope of karst studies. These geomorphological studies are combined with concepts and techniques from hydraulics, chemistry, and mathematics. (JN)

Contamination risk and drinking water protection for a large-scale managed aquifer recharge site in a semi-arid karst region, Jordan

NASA Astrophysics Data System (ADS)

Xanke, Julian; Liesch, Tanja; Goeppert, Nadine; Klinger, Jochen; Gassen, Niklas; Goldscheider, Nico

2017-09-01

Karst aquifers in semi-arid regions are particularly threatened by surface contamination, especially during winter seasons when extremely variable rainfall of high intensities prevails. An additional challenge is posed when managed recharge of storm water is applied, since karst aquifers display a high spatial variability of hydraulic properties. In these cases, adapted protection concepts are required to address the interaction of surface water and groundwater. In this study a combined protection approach for the surface catchment of the managed aquifer recharge site at the Wala reservoir in Jordan and the downstream Hidan wellfield, which are both subject to frequent bacteriological contamination, is developed. The variability of groundwater quality was evaluated by correlating contamination events to rainfall, and to recharge from the reservoir. Both trigger increased wadi flow downstream of the reservoir by surface runoff generation and groundwater seepage, respectively. A tracer test verified the major pathway of the surface flow into the underground by infiltrating from pools along Wadi Wala. An intrinsic karst vulnerability and risk map was adapted to the regional characteristics and developed to account for the catchment separation by the Wala Dam and the interaction of surface water and groundwater. Implementation of the proposed protection zones for the wellfield and the reservoir is highly recommended, since the results suggest an extreme contamination risk resulting from livestock farming, arable agriculture and human occupation along the wadi. The applied methods can be transferred to other managed aquifer recharge sites in similar karstic environments of semi-arid regions.

Type, origin, and reservoir characteristics of dolostones of the Ordovician Majiagou Group, Ordos, North China Platform

NASA Astrophysics Data System (ADS)

Feng Zengzhao; Zhang Yongsheng; Jin Zhenkui

1998-06-01

sea water. Type IV dolostones consist of coarse-silt-sized to fine-sand-sized dolomite crystals. In such dolostones, stylolites are cut by dolomite crystals. Fluid inclusions are present, and the homogenization temperature commonly ranges from 104°C to 203°C. The ordering of dolomites averages 0.85, and molar concentration of CaCO 3 averages 50.65%. δ13C averages 0.6‰, δ18O averages -7.4‰, and δCe averages 1.16. Such dolostones resulted from deep burial dolomitization. In the Ordos area, type I and II dolostones modified by palaeokarstification are the major gas reservoir rocks of the Ordos Gas Field at present. Type IV dolostones show good reservoir characteristics and may also be potential reservoir rocks.

A mathematical model for simulating spring discharge and estimating sinkhole porosity in a karst watershed

NASA Astrophysics Data System (ADS)

Li, Guangquan; Field, Malcolm S.

2014-03-01

Documenting and understanding water balances in a karst watershed in which groundwater and surface water resources are strongly interconnected are important aspects for managing regional water resources. Assessing water balances in karst watersheds can be difficult, however, because karst watersheds are so very strongly affected by groundwater flows through solution conduits that are often connected to one or more sinkholes. In this paper we develop a mathematical model to approximate sinkhole porosity from discharge at a downstream spring. The model represents a combination of a traditional linear reservoir model with turbulent hydrodynamics in the solution conduit connecting the downstream spring with the upstream sinkhole, which allows for the simulation of spring discharges and estimation of sinkhole porosity. Noting that spring discharge is an integral of all aspects of water storage and flow, it is mainly dependent on the behavior of the karst aquifer as a whole and can be adequately simulated using the analytical model described in this paper. The model is advantageous in that it obviates the need for a sophisticated numerical model that is much more costly to calibrate and operate. The model is demonstrated using the St. Marks River Watershed in northwestern Florida.

Karst map of Puerto Rico

USGS Publications Warehouse

Alemán González, Wilma B.

2010-01-01

This map is a digital compilation, combining the mapping of earlier geologists. Their work, cited on the map, contains more detailed descriptions of karst areas and landforms in Puerto Rico. This map is the basis for the Puerto Rico part of a new national karst map currently being compiled by the U.S. Geological Survey. In addition, this product is a standalone, citable source of digital karst data for Puerto Rico. Nearly 25 percent of the United States is underlain by karst terrain, and a large part of that area is undergoing urban and industrial development. Accurate delineations of karstic rocks are needed at scales suitable for national, State, and local maps. The data on this map contribute to a better understanding of subsidence hazards, groundwater contamination potential, and cave resources as well as serve as a guide to topical research on karst. Because the karst data were digitized from maps having a different scale and projection from those on the base map used for this publication, some karst features may not coincide perfectly with physiographic features portrayed on the base map.

The influence of solution composition and grain boundaries on the replacement of calcite by dolomite

NASA Astrophysics Data System (ADS)

Moraila Martinez, Teresita de Jesus; Putnis, Christine V.; Putnis, Andrew

2016-04-01

Dolomite formation is a mineral replacement reaction that affects extensive rock volumes and comprises a large fraction of oil and gas reservoirs [1,2]. The most accepted hypothesis is the 'dolomitization' of limestone by Mg-rich fluids [3]. The objective of this research is to study the replacement mechanism of calcite by dolomite, the role of grain boundaries, highlighted by Etschmann et al. (2014), and the possible influence of solutions in dolomite formation under the presence of ions that are normally in crustal aqueous fluids. To accomplish this purpose, we performed hydrothermal experiments using Carrara marble cubes of ~1.5 mm size and 7-9 mg weight as starting material, reacted with 1M (Mg,Ca)Cl2 aqueous solutions, with Mg/Ca ratios of 3 and 5 at 200°C, for different reaction times. Additional experiments were performed adding 1mM of Na2SO4, NaCl or NaF to the previous solutions. After the reaction, the product phases were identified using Raman spectroscopy, X-Ray powder diffraction (XRD), electron microprobe analysis (EMPA), and the textural evolution was studied by scanning electron microscopy (SEM). Samples reacted with aqueous solutions resulted in the replacements of the calcite rock into magnesite and dolomite. The amount and type of reaction strongly depends on the Mg/Ca ratio. Samples reacted with a Mg/Ca ratio of 5 resulted in an almost complete replacement reaction and more favorable for magnesite formation than for dolomite. When the Mg/Ca ratio was 3 dolomite formed but the replacement was located in the core of the sample. We show that grain boundaries are very important for the infiltration of solution and the progress of a replacement reaction, acting as fluid pathways. Solution composition controls the nature of the replacement product. Acknowledgment: This work is funded within a Marie Curie EU Initial Training Network- CO2-React. 1. Etschmann B., Brugger J., Pearce M.A., Ta C., Brautigan D., Jung M., Pring A. (2014). Grain boundaries as

Karst geomorphology and hydrology at the Campania - Basilicata border (southern Apennines of Italy)

NASA Astrophysics Data System (ADS)

Farfan Gonzalez, H.; Parise, M.

2009-04-01

This paper describes the main karst geomorphological and hydrological features of the area at the boundary between the Campania and Basilicata regions, in the southern Apennines of Italy. Even not far from the most important karst area of southern Italy (the Alburni Massif, hosting hundreds of caves, with very complex subterranean systems that have been extensively explored in the last 50 years), this sector has never been object of detailed karstic studies. Geologically, it shows a carbonate bedrock consisting of Cretaceous limestones and dolomites, in tectonic contact with terrigenous deposits of Miocene age. The territory is an active seismogenic zone, as testified by the November 23, 1980, earthquake that hit this part of southern Italy with a 6.8 magnitude, causing over 2,700 victims and destroying several small towns in the two regions. In 2007, within the framework of joint projects between the Italian Speleological Society (SSI) and the Cuban Speleological Society (SEC), a scientific and speleological expedition was carried out in a sector of this area. The efforts produced during the expedition, and in the preceeding phases as well, resulted in discovery, survey and documentation of 62 caves, and in supporting the progresses of the exploration activities in the main karst system in the area, a complex of two caves that reach a maximum depth of 123 meters and an overall length of 1,8 km. At the surface, a variety of karst landforms is recognizable. The main carbonate ridges show several orders of palaeosurfaces, located at different heights above sea level. Bounded by fault lines or fault line scarps, they present variable extension, the highest surfaces showing a much better continuity. On the Campanian side, several sinkholes are also present, some of which opened in the aftermath of the 1980 earthquake. The same event caused in Basilicata the formation of several caves of structural origin, controlled in their development by tectonics and extremely

Effect of Niagara power project on ground-water flow in the upper part of the Lockport Dolomite, Niagara Falls area, New York

USGS Publications Warehouse

Miller, Todd S.; Kappel, W.M.

1987-01-01

The Niagara River Power Project near Niagara Falls, N.Y., has created recharge and discharge areas that have modified the direction of groundwater flow east and northeast of the falls. Before construction of the power project in 1962, the configuration of the potentiometric surface in the upper part of the Silurian Lockport Dolomite generally paralleled the buried upper surface of the bedrock. Ground water in the central and east parts of the city of Niagara Falls flowed south and southwestward toward the upper Niagara River (above the falls), and ground water in the western part flowed westward into Niagara River gorge. The power project consists of two hydroelectric powerplants separated by a forebay canal that receives water from the upper Niagara River through two 4-mi-long, parallel, buried conduits. During periods of nonpeak power demand, some water in the forebay canal is pumped to a storage reservoir for later release to generate electricity during peak-demand periods. Since the power project began operation in 1962, groundwater within 0.5 mi of the buried conduits has seeped into the drain system that surrounds the conduits, then flows both south from the forebay canal and north from the Niagara River toward the Falls Street tunnel--a former sewer that crosses the conduits 0.65 mi north of the upper Niagara River. Approximately 6 million gallons of ground water a day leaks into the Falls Street tunnel, which carries it 2.3 mi westward to the Niagara River gorge below the falls. Daily water-level fluctuations in the forebay canal affect water levels in the drain system that surrounds the conduits, and this , in turn, affects the potentiometric surface in the Lockport Dolomite within 0.5 mi of the conduits. The drains transmit changes in pressure head near the forebay canal southward at least as far as the Falls Street tunnel area and possibly to the upper Niagara River. Some water in the pumped-storage reservoir recharges ground water in the Lockport

Construction on dolomite in south Africa

NASA Astrophysics Data System (ADS)

Wagener, Fritz Von M.; Day, Peter W.

1986-03-01

Damage to structures and loss of life have been more severe on dolomite than on any other geological formation in southern Africa. The subsidence that occurs on dolomitic terrain following development or during dewatering has given dolomite a notorious reputation and engineers and geologists became reluctant to recommend development on the material. This has led to the pioneering of founding methods for a wide variety of structures aimed at reducing the risk of severity of damage due to subsidence settlement Structures successfully founded on dolomitic terrane include residential and industrial buildings, gold mine reduction works and shaft structures, tailings dams, water retaining structures, and road and rail links. In this article, various methods of construction, some ot which were developed by the authors, are presented. It commences with a classification of a dolomite site in terms of overburden thickness followed by a discussion of the relevant construction methods The methods include mattresses of compacted soil supported by pinnacles or “floating” in residuum, deep foundations such as caissons, the use of specialized piling techniques, and soil improvement by dynamic consolidation

Multiple episodes of dolomitization and dolomite recrystallization during shallow burial in Upper Jurassic shelf carbonates: eastern Swabian Alb, southern Germany

NASA Astrophysics Data System (ADS)

Reinhold, C.

1998-10-01

The Upper Jurassic of the eastern Swabian Alb is composed of oolitic platform sands with associated microbe-siliceous sponge mounds at the platform margins. They are surrounded by argillaceous or calcareous mudstones and marl-limestone alternations, deposited in adjacent marl basins. Partial to complete dolomitization is predominantly confined to the mound facies. Six types of dolomite, as well as one type of ankerite, document a complex diagenetic history during shallow burial with multiple episodes of dolomite formation and recrystallization. The earliest massive matrix dolomitization is Ca-rich, has slightly depleted oxygen isotope values relative to Late Jurassic seawater, and carbon isotopic values in equilibrium with Late Jurassic seawater. This initial massive matrix dolomitization occurred during latest Jurassic to earliest Cretaceous and is related to pressure dissolution during very shallow burial at temperatures of at least 50°C. Hydrologic conditions and mass-balance calculations indicate that burial compaction provided sufficient fluids for dolomitization. Mg is derived from negligibly modified seawater, that was expelled from the adjacent off-reef strata into the mound facies. Position of the mounds along the platform margins controlled the distribution of the shallow-burial dolomite. Covariant trends between textural modification, increasing stoichiometry, partial changes in trace element content (Mn, Fe, Sr) and depletion in stable isotopes as well as distinctive CL pattern illustrate two recrystallization phases of the precursor matrix dolomite during further burial at elevated temperatures. Strong Sr enrichment of the second phase of recrystallized dolomite is ascribed to Sr-rich meteoric waters descending from overlying aragonite-bearing reef limestones or evaporite-bearing peritidal carbonates. Late-stage coarsely crystalline dolomite cements occur as vug and fracture fillings and formed during burial. Ankerite, associated with sulphide and

Fluid-flow, diagenesis and generation of secondary porosity-permeability in the Cretaceous Jandaira Formation, Brazil - an analogue of karstified carbonate reservoirs

NASA Astrophysics Data System (ADS)

Bezerra, F. H.; Cazarin, C. L.; Srivastava, N. K.

2017-12-01

This study investigates the diagenetic processes that generated secondary porosity-permeability in carbonates. Our study area is the Jandaira Formation, a post-rift unit, 50-700 m thick, which occurs over an area of 70 x 260 km in the Potiguar Basin, Equatorial margin of Brazil. The Jandaira Formation formed in the Turonian-Campanian and is the major exposed Cretaceous carbonate platform in the eastern continental margin of South America. Little folding and nearly flat-lying layers characterize this unit. We used a multidisciplinary approach, which included drone imagery, petrographic, petrophysical, petrological, and structural studies. Our results indicate that several levels of dissolution occurred in mudstone, grainstone, and wackestone facies along faults, fractures, and bedding planes. Fracture and faults provided vertical leaching pathways and sedimentary bedding provided horizontal pathways of increased secondary porosity and permeability. Dissolution resulted in a multi-scale karst system that could reach voids 5 m wide and 1 km long. Dissolution mostly affect the dolomitized sedimentary facies in the form of vugular, moldic, interparticular, and intercrystalline porosity. It also generated a new modified facies that we defined as karstified facies. Dissolution increased permeability in carbonate rocks from primary values of 0.0-0.94 mD to as much as 1370.11 mD. Micritization, lixiviation of evaporites, meteoric water infiltration and dolomitization during late diagenesis could have triggered dissolution processes. The Jandaira Formation serves as an analog of fractured and karstified carbonate reservoirs, where faults, joints, and bedding acted as pathways of high permeability.

Negative grouting consequences on karst environment

NASA Astrophysics Data System (ADS)

Bonacci, O.; Roje-Bonacci, T.; Gottstein, S.

2009-04-01

Grouting is a procedure by means of which grout is injected into different kinds of karst spaces (cracks, fissures, conduits and caves). It has a wide application in modern civil engineering, especially in karst terrains. It started nearly 200 years ago. In most cases the ingredients for the preparation of mortars and grouting suspensions are: cement, bentonite, clay and fillers, additives for stability and water. In practice the composition of grouting suspension is not standardized. A suspension injected under pressure will circulate in the karst spaces like a more or less viscous fluid until some of the larger suspended particles are blocked where the karst voids get narrower than the size of injected grains. The injection of materials into karst groundwater, i.e. the construction of grouting curtains, definitely could be the cause of unpredictable negative consequences on karst groundwater environments. The building of dams in karst areas always go along the construction of grouting curtains. During the construction of most dams in karst all over the world millions tons of injection mass have been injected in karst underground. It may impact water quantity in vadose zone and in karstic aquifer causing water table lowering and spring desiccation. In such cases the negative impact on local karst environment could be very dangerous. Physically as well as chemically this mass voraciously and quickly destroyed underground habitats and killed an enormous number of endangered and endemic species. Very often this is extremely expensive procedure and in many cases not very successful from the engineering point of view. From the ecological point of view it could causes catastrophic consequences. The greatest problem is that until now neither engineers nor ecologists took care of these great and massive negative influences on underground karst environments. In this paper few examples of different consequences of grouting on the hydrogeological as well as ecological regime

Cyclic, Early Diagenetic Dolomite Formation in Alkaline Lake Van

NASA Astrophysics Data System (ADS)

McCormack, J.; Bontognali, T. R. R.; Immenhauser, A.; Kwiecien, O.

2017-12-01

Modern dolomite-forming environments are commonly constrained to evaporitic marine or marginal marine settings such as lagoons and sabkhas. Beside microbial mediation, high temperatures and Mg2+ concentrations in solution are factors considered important in aiding dolomite formation. Accordingly, previous studies associate the presence of dolomite within deep sediments of alkaline Lake Van (Turkey) with periods of enhanced evaporation, low lake levels and high Mg/Ca ratio. We systematically studied dolomite within the sedimentary record of Lake Van by means of XRD, SEM and stable isotope (δ18O and δ13C) mass spectrometry. First, we considered the origin of the dolomite; next, we focused on the wider implication of its presence. SEM imaging documents large dolomite crystals interwoven with clay minerals and individual crystals with different crystallographic orientations grown together, indicating space-limited growth within the sediment. According to recent climatic reconstructions for the same sequence (ICDP PALEOVAN project), the water depth of the coring site - today at 350 m - unlikely fell below 200 m. Consequently, dolomite formed below a thick water column at constantly low temperatures (supported by heavy δ18O signature). Within this environment, variations in Mg/Ca ratio, pH and alkalinity, which are constantly high, have no effect on the episodic nature of dolomite precipitation. These observations call for a re-evaluation of the palaeoenvironments often invoked to interpret intervals rich in dolomite within ancient sedimentary sequences (e.g., periods of enhanced aridity and evaporation). Further, and in contrast to previous interpretations, our dolomite concentration data backed up by ICDP PALEOVAN reconstructions suggest that intervals rich in dolomite coincide with periods of high lake level and increased humidity. High dolomite concentrations (20 - 85 % relative carbonate content) occur cyclically within the last glacial period and coincide with

Geochemistry and origin of regional dolomites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hanson, G.N.; Meyers, W.J.

1992-01-01

This grant supports research on the origins and geochemical aspects of regional dolomites. Eight graduate students are involved in research on dolomite allowing a diverse range of studies. This report outlines their work in the field. (JL)

Experimentally determined biomediated Sr partition coefficient for dolomite: Significance and implication for natural dolomite

NASA Astrophysics Data System (ADS)

Sánchez-Román, Mónica; McKenzie, Judith A.; de Luca Rebello Wagener, Angela; Romanek, Christopher S.; Sánchez-Navas, Antonio; Vasconcelos, Crisógono

2011-02-01

Two strains of moderately halophilic bacteria were grown in aerobic culture experiments containing gel medium to determine the Sr partition coefficient between dolomite and the medium from which it precipitates at 15 to 45 °C. The results demonstrate that Sr incorporation in dolomite does occur not by the substitution of Ca, but rather by Mg. They also suggest that Sr partitioning between the culture medium and the minerals is better described by the Nernst equation ( DSrdol = Sr dol/Sr bmi), instead of the Henderson and Kracek equation ( DSrdol = (Sr/Ca) dol/(Sr/Ca) solution. The maximum value for DSrdol occurs at 15 °C in cultures with and without sulfate, while the minimum values occur at 35 °C, where the bacteria exhibit optimal growth. For experiments at 25, 35 and 45 °C, we observed that DSrdol values are greater in cultures with sulfate than in cultures without sulfate, whereas DSrdol values are smaller in cultures with sulfate than in cultures without sulfate at 15 °C. Together, our observations suggest that DSrdol is apparently related to microbial activity, temperature and sulfate concentration, regardless of the convention used to assess the DSrdol. These results have implications for the interpretation of depositional environments of ancient dolomite. The results of our culture experiments show that higher Sr concentrations in ancient dolomite could reflect microbial mediated primary precipitation. In contrast, previous interpretations concluded that high Sr concentrations in ancient dolomites are an indication of secondary replacement of aragonite, which incorporates high Sr concentrations in its crystal lattice, reflecting a diagenetic process.

The effects of dolomitization on petrophysical properties and fracture distribution within rift-related carbonates (Hammam Faraun Fault Block, Suez Rift, Egypt)

NASA Astrophysics Data System (ADS)

Korneva, I.; Bastesen, E.; Corlett, H.; Eker, A.; Hirani, J.; Hollis, C.; Gawthorpe, R. L.; Rotevatn, A.; Taylor, R.

2018-03-01

Petrographic and petrophysical data from different limestone lithofacies (skeletal packstones, matrix-supported conglomerates and foraminiferal grainstones) and their dolomitized equivalents within a slope carbonate succession (Eocene Thebes Formation) of Hammam Faraun Fault Block (Suez Rift, Egypt) have been analyzed in order to link fracture distribution with mechanical and textural properties of these rocks. Two phases of dolomitization resulted in facies-selective stratabound dolostones extending up to two and a half kilometers from the Hammam Faraun Fault, and massive dolostones in the vicinity of the fault (100 metres). Stratabound dolostones are characterized by up to 8 times lower porosity and 6 times higher frequency of fractures compared to the host limestones. Precursor lithofacies type has no significant effect on fracture frequency in the stratabound dolostones. At a distance of 100 metres from the fault, massive dolostones are present which have 0.5 times porosity of precursor limestones, and lithofacies type exerts a stronger control on fracture frequency than the presence of dolomitization (undolomitized vs. dolomitized). Massive dolomitization corresponds to increased fracture intensity in conglomerates and grainstones but decreased fracture intensity in packstones. This corresponds to a decrease of grain/crystal size in conglomerates and grainstones and its increase in packstones after massive dolomitization. Since fractures may contribute significantly to the flow properties of a carbonate rock, the work presented herein has significant applicability to hydrocarbon exploration and production from limestone and dolostone reservoirs, particularly where matrix porosities are low.

Chemistry and Environments of Dolomitization —A Reappraisal

NASA Astrophysics Data System (ADS)

Machel, Hans-G.; Mountjoy, Eric W.

1986-05-01

Dolomitization of calcium carbonate can best be expressed by mass transfer reactions that allow for volume gain, preservation, or loss during the replacement process. Experimental data, as well as textures and porosities of natural dolomites, indicate that these reactions must include CO 32- and/or HCO 3- supplied by the solution to the reaction site. Since dolomite formation is thermodynamically favoured in solutions of (a) low Ca 2+/Mg 2+ ratios, (b) low Ca 2+/CO 32- (or Ca 2+/HCO 3-) ratios, and (c) high temperatures, the thermodynamic stability for the system calcite-dolomite-water is best represented in a diagram with these three parameters as axes. Kinetic considerations favour dolomitization under the same conditions, and additionally at low as well as at high salinities. If thermodynamic and kinetic considerations are combined, the following conditions and environments are considered chemically conducive to dolomitization: (1) environments of any salinity above thermodynamic and kinetic saturation with respect to dolomite (i.e. freshwater/seawater mixing zones, normal saline to hypersaline subtidal environments, hypersaline supratidal environments, schizohaline environments); (2) alkaline environments (i.e. those under the influence of bacterial reduction and/or fermentation processes, or with high input of alkaline continental groundwaters); and (3) many environments with temperatures greater than about 50°C (subsurface and hydrothermal environments). Whether or not massive, replacive dolostones are formed in these environments depends on a sufficient supply of magnesium, and thus on hydrologic parameters. Most massive dolostones, particularly those consisting of shallowing-upward cycles and capped by regional unconformities, have been interpreted to be formed according to either the freshwater/seawater mixing model or the sabkha with reflux model. However, close examination of natural mixing zones and exposed evaporitic environments reveals that the

First description of Phanerozoic radiaxial fibrous dolomite

NASA Astrophysics Data System (ADS)

Richter, D. K.; Heinrich, F.; Geske, A.; Neuser, R. D.; Gies, H.; Immenhauser, A.

2014-05-01

The petrographic analysis and crystallographic analysis of concretionary carbonate cements ("coal balls") from Carboniferous paralic swamp deposits reveal the presence of (length fast) radiaxial fibrous dolomite (RFD), a fabric not previously reported from the Phanerozoic. This finding is of significance as earlier reports of Phanerozoic radiaxial fibrous carbonates are exclusively of calcite mineralogy. Dolomite concretions described here formed beneath marine transgressive intervals within palustrine coal seams. This is of significance as seawater was arguably the main source of Mg2 + ions for dolomite formation. Here, data from optical microscopy, cathodoluminescence, electron backscattered diffraction, X-ray diffraction and geochemical analyses are presented to characterize three paragenetic dolomite phases and one calcite phase in these concretions. The main focus is on the earliest diagenetic, non-stoichiometric (degree of order: 0.41-0.46) phase I, characterized by botryoidal dolomite constructed of fibres up to 110 μm wide with a systematic undulatory extinction and converging crystal axes. Petrographic and crystallographic evidence clearly qualifies phase I dolomite as radiaxial fibrous. Conversely, fascicular optical fabrics were not found. Carbon-isotope ratios (δ13C) are depleted (between - 11.8 and - 22.1‰) as expected for carbonate precipitation from marine pore-fluids in organic-matter-rich, paralic sediment. Oxygen isotope (δ18O) ratios range between - 1.3 and - 6.0‰. The earliest diagenetic nature of these cements is documented by the presence of ubiquitous, non-compacted fossil plant remains encased in phase I dolomite as well as by the complex zoned luminescence patterns in the crystals and is supported by crystallographic and thermodynamic considerations. It is argued that organic matter, and specifically carboxyl groups, reduced thermodynamic barriers for dolomite formation and facilitated Mg/CaCO3 precipitation. The data shown here

Dolomite III: A new candidate lower mantle carbonate

NASA Astrophysics Data System (ADS)

Mao, Zhu; Armentrout, Matt; Rainey, Emma; Manning, Craig E.; Dera, Przemyslaw; Prakapenka, Vitali B.; Kavner, Abby

2011-11-01

Dolomite is a major constituent of subducted carbonates; therefore evaluation of its phase stability and equation of state at high pressures and temperatures is important for understanding the deep Earth carbon cycle. X-ray diffraction experiments in the diamond anvil cell show that Ca0.988Mg0.918Fe0.078Mn0.016(CO3)2 dolomite transforms to dolomite-II at ∼17 GPa and 300 K and then upon laser-heating transforms to a new monoclinic phase (dolomite-III), that is observed between 36 and 83 GPa. Both high-pressure polymorphs are stable up to 1500 K, indicating that addition of minor Fe stabilizes dolomite to Earth's deep-mantle conditions.

Database Dictionary for Ethiopian National Ground-Water Database (ENGDA) Data Fields

DTIC Science & Technology

2007-01-01

Coarse Sand Fine Sand Fine-Grained Sandstone Fractured Igneous and Metamorphic Rock Gravel Karst Limestone, Dolomite Medium Sand Medium-Grained...Coarse Sand; Fine Sand; Fine-Grained Sandstone; Fractured Igneous and Metamorphic Rock; Gravel; Karst Limestone/ Dolomite ; Medium Sand; Medium...aquifer lithology (rock type; Babcock and other, 2004). - 20 - Data Type: List, 1-character code C Consolidated porous sedimentary I Fractured

Geothermal prospection in the Greater Geneva Basin (Switzerland and France). Impact of diagenesis on reservoir properties of the Upper Jurassic carbonate sediments

NASA Astrophysics Data System (ADS)

Makhloufi, Yasin; Rusillon, Elme; Brentini, Maud; Clerc, Nicolas; Meyer, Michel; Samankassou, Elias

2017-04-01

Diagenesis of carbonate rocks is known to affect the petrophysical properties (porosity, permeability) of the host rock. Assessing the diagenetic history of the rock is thus essential when evaluating any reservoir exploitation project. The Canton of Geneva (Switzerland) is currently exploring the opportunities for geothermal energy exploitation in the Great Geneva Basin (GGB) sub-surface. In this context, a structural analysis of the basin (Clerc et al., 2016) associated with reservoir appraisal (Brentini et al., 2017) and rock-typing of reservoir bodies of potential interest were conducted (Rusillon et al., 2017). Other geothermal exploitation projects elsewhere (e.g. Bavaria, south Germany, Paris Basin, France) showed that dolomitized carbonate rocks have good reservoir properties and are suitable for geothermal energy production. The objectives of this work are to (1) describe and characterize the dolomitized bodies in the GGB and especially their diagenetic history and (2) quantify the reservoir properties of those bodies (porosity, permeability). Currently, our study focuses on the Upper Jurassic sedimentary bodies of the GGB. Field and well data show that the dolomitization is not ubiquitous in the GGB. Results from the petrographical analyses of the Kimmeridgian cores (Humilly-2) and of field analogues (Jura, Saleve and Vuache mountains) display complex diagenetic histories, dependent of the study sites. The paragenesis exhibits several stages of interparticular calcite cementation as well as different stages of dolomitization and/or dedolomitization. Those processes seem to follow constrained path of fluid migrations through burial, faulting or exhumation during the basin's history. These complex diagenetic histories affected the petrophysical and microstructural properties via porogenesis (conservation of initial porosity, moldic porosity) and/or poronecrosis events. The best reservoir properties appear to be recorded in patch reef and peri

The trade-off between safety and efficiency in hydraulic architecture in 31 woody species in a karst area.

PubMed

Fan, Da-Yong; Jie, Sheng-Lin; Liu, Chang-Cheng; Zhang, Xiang-Ying; Xu, Xin-Wu; Zhang, Shou-Ren; Xie, Zong-Qiang

2011-08-01

Karst topography is a special landscape shaped by the dissolution of one or more layers of soluble bedrock, usually carbonate rock such as limestone or dolomite. Due to subterranean drainage, overland flow, extraction of water by plants and evapotranspiration, there may be very limited surface water. The hydraulic architecture that plants use to adapt to karst topography is very interesting, but few systematic reports exist. The karst area in southwestern China is unique when compared with other karst areas at similar latitudes, because of its abundant precipitation, with rainfall concentrated in the growing season. In theory, resistance to water-stress-induced cavitation via air seeding should be accompanied by decreased pore hydraulic conductivity and stem hydraulic conductivity. However, evidence for such trade-offs across species is ambiguous. We measured the hydraulic structure and foliar stable carbon isotope ratios of 31 karst woody plants at three locations in Guizhou Province, China, to evaluate the functional coordination between resistance to cavitation and specific conductivity. We also applied phylogenetically independent contrast (PIC) analysis in situations where the inter-species correlations of functional traits may be biased on the potential similarity of closely related species. The average xylem tension measurement, at which 50% of hydraulic conductivity of the plants was lost (Ψ(50)), was only -1.27 MPa. Stem Ψ(50) was positively associated with specific conductance (K(s)) (P < 0.05) and leaf specific conductance (K(l)) (P < 0.05). However, the PIC correlation for both relationships was not statistically significant. δ(13)C was positively related to K(l) in both the traditional cross-species correlation analysis and the corresponding PIC correlations (P < 0.05). The Huber value (sapwood area:leaf area ratio) was negatively correlated with K(s) in both the traditional cross-species correlation and the corresponding PIC

Stable sulfur and oxygen isotopes as geochemical tracers of sulfate in karst waters

NASA Astrophysics Data System (ADS)

Sun, Jing; Kobayashi, Tatsuaki; Strosnider, William H. J.; Wu, Pan

2017-08-01

Karst water resources, which are extremely sensitive to mining activities, are critical for the support of human societies and ecological systems in many regions worldwide. In order to determine the sources and fate of dissolved sulfate in low-pH karst waters, hydrochemical variations of karst waters with and without acid mine drainage (AMD) impacts were investigated along with stable isotope dynamics. As expected, hydrochemical characteristics and isotopic compositions of the AMD and AMD-downstream water (ADW) were dramatically different from that of the non-AMD-impacted water (NAW). The sources of sulfur isotopes in sulfate were predominantly pyrite oxidation for the AMD and ADW, and atmospheric deposition for the NAW. Based on the general isotope-balance model, the relative proportions of sulfate oxygen derived from water and air were calculated. The mean proportion of sulfate oxygen derived from water in ADW was roughly double that of AMD. This suggests that the sulfate associated with AMD is predominantly influenced by aerobic pyrite oxidation, while that of ADW is likely affected by the dissolution of pyrite under anaerobic conditions in reservoir sediment. This observation was coincident with the noted variations of hydrochemical characteristics and was supported by principal component analysis. These results provide a better understanding of how stable isotopes of sulfate and water can be used to track mining contamination in karst aquifers, which could benefit remediation planning for these distinctive systems.

Quantifying the magnitude and spatiotemporal variation of aquatic CO2 fluxes in a sub-tropical karst catchment, Southwest China

NASA Astrophysics Data System (ADS)

Ding, Hu; Waldron, Susan; Newton, Jason; Garnett, Mark H.

2017-04-01

The role played by rivers in regional and global C budgets is receiving increasing attention. A large portion of the carbon transported via inland waters is returned to the atmosphere by carbon dioxide evasion from rivers and lakes. Karst landscapes represent an important C store on land, and are also considered to play an important role in climate regulation by consuming atmospheric CO2 during chemical weathering. However, we cannot be certain how effective this sink is if we do not know how efficiently the rivers draining karst landscapes remobilise weathered C to the atmosphere as CO2. pCO2 in karst waters is generally greater than atmospheric equilibrium, indicating that there can be a net CO2 efflux to the atmosphere. However, measurement confirming this and quantifying flux rates has been rarely conducted. Using a floating chamber method, in 2016 we directly measured CO2 fluxes from spatially distributed freshwaters (springs, sinkholes, streams and reservoirs/ponds) in the Houzhai Catchment, a karst region in SW China. Fluxes ranged from -0.5 to +267.4 μmol CO2 m-2s-1, and most sites showed seasonal variations with higher CO2 efflux rates in the wet (April - September) than dry season (October - March). There was a significant positive relationship between CO2 efflux and flow velocity, indicating that hydraulic controls on CO2 efflux from flowing water are important, while for water with little movement (sinkholes and reservoirs/ponds), pCO2 appears a more important control on efflux rates. Conditions similar to this study area may exist in many sub-tropical rivers that drain karst landscapes in South China. These waters are rich in DIC which can be an order of magnitude greater than some non-karst catchments. The large DIC pool has the potential to be a considerable source of free CO2 to the atmosphere. Considering that carbonate lithology covers a significant part of the Earth's surface, CO2 evasion in fluvial water from these regions is expected to

A LEXICON OF CAVE AND KARST TERMINOLOGY WITH SPECIAL REFERENCE TO ENVIRONMENTAL KARST HYDROLOGY (2002 EDITION)

EPA Science Inventory

Several attempts to classify karst terminology in an organized manner have been attempted in the past. The last few glossaries of karst terminology were organized in the late 1960s and published in the early 1970s. Since that time, many new terms related to karst in general hav...

A Raman spectroscopic comparison of calcite and dolomite

NASA Astrophysics Data System (ADS)

Sun, Junmin; Wu, Zeguang; Cheng, Hongfei; Zhang, Zhanjun; Frost, Ray L.

2014-01-01

Raman spectroscopy was used to characterize and differentiate the two minerals calcite and dolomite and the bands related to the mineral structure. The (CO3)2- group is characterized by four prominent Raman vibrational modes: (a) the symmetric stretching, (b) the asymmetric deformation, (c) asymmetric stretching and (d) symmetric deformation. These vibrational modes of the calcite and dolomite were observed at 1440, 1088, 715 and 278 cm-1. The significant differences between the minerals calcite and dolomite are observed by Raman spectroscopy. Calcite shows the typical bands observed at 1361, 1047, 715 and 157 cm-1, and the special bands at 1393, 1098, 1069, 1019, 299, 258 and 176 cm-1 for dolomite are observed. The difference is explained on the basis of the structure variation of the two minerals. Calcite has a trigonal structure with two molecules per unit cell, and dolomite has a hexagonal structure. This is more likely to cause the splitting and distorting of the carbonate groups. Another cause for the difference is the cation substituting for Mg in the dolomite mineral.

Geothermal convection: a mechanism for dolomitization at Enewetak Atoll?

USGS Publications Warehouse

Wilson, A.M.; Sanford, W.; Whitaker, F.; Smart, P.

2000-01-01

Geothermal convection in carbonate platforms could drive massive dolomitization by supplying mass transport of magnesium over long periods and at temperatures high enough to overcome kinetic limitations. Reactive-transport simulations based on Enewetak Atoll show dolomitization in a thin band at a permeability contrast near the base of the platform, which is consistent with field observations of dolomitized Eocene deposits. Dolomitization is predicted at approximately 6% per My at temperatures of 45–60°C, and complete dolomitization could be accomplished in ∼16 My. Calcium enrichment of pore fluids and upward transport of these fluids is established early, prior to 30 ky.

First-principles calculations of high-pressure iron-bearing monoclinic dolomite and single-cation carbonates with internally-consistent Hubbard U

NASA Astrophysics Data System (ADS)

Solomatova, N. V.; Asimow, P. D.

2017-12-01

It has been proposed that iron has a significant effect on the relative stability of carbonate phases at high pressures, possibly even stabilizing double-cation carbonates (e.g., dolomite) with respect to single-cation carbonates (e.g., magnesite, aragonite and siderite). X-ray diffraction experiments have shown that dolomite transforms at 35 GPa to a high-pressure polymorph that is stable to decomposition; however, there has been disagreement on the structure of the high-pressure phase [1,2]. Ab initio calculations interfaced with an evolutionary structure prediction algorithm demonstrated that a C2/c polymorph of pure CaMg(CO3)2 dolomite is more stable than previously reported structures [3]. In this study, we calculate the relative enthalpies up to 80 GPa for a set of carbonate phases including Fe-bearing solutions and endmembers, using the generalized gradient approximation and a Hubbard U parameter calculated through linear response theory to accurately characterize the electronic structure of Fe. When calculated with a constant U of 4 eV, the spin transition pressure of (Mg,Fe)CO3 agrees well with experiments, whereas an internally-consistent U overestimates the spin transition pressure by 50 GPa. However, whether we use constant or internally-consistent U values, a higher iron concentration increases the stability field of dolomite C2/c with respect to single-cation carbonate assemblages, but iron-free dolomite is not stable with respect to single-cation carbonates at any pressure. Thus, high-pressure polymorphs of Fe-bearing dolomite could in fact represent an important reservoir for carbon storage within oxidized sections of Earth's mantle. [1] Mao, Z. et al. (2011) Geophysical Research Letters, 38. [2] Merlini, M. et al. (2012) Proceedings of the National Academy of Sciences, 109, 13509-13514. [3] Solomatova, N. V. and Asimow, P. D. (2017) American Mineralogist, 102, 210-215.

A Raman spectroscopic comparison of calcite and dolomite.

PubMed

Sun, Junmin; Wu, Zeguang; Cheng, Hongfei; Zhang, Zhanjun; Frost, Ray L

2014-01-03

Raman spectroscopy was used to characterize and differentiate the two minerals calcite and dolomite and the bands related to the mineral structure. The (CO3)(2-) group is characterized by four prominent Raman vibrational modes: (a) the symmetric stretching, (b) the asymmetric deformation, (c) asymmetric stretching and (d) symmetric deformation. These vibrational modes of the calcite and dolomite were observed at 1440, 1088, 715 and 278 cm(-1). The significant differences between the minerals calcite and dolomite are observed by Raman spectroscopy. Calcite shows the typical bands observed at 1361, 1047, 715 and 157 cm(-1), and the special bands at 1393, 1098, 1069, 1019, 299, 258 and 176 cm(-1) for dolomite are observed. The difference is explained on the basis of the structure variation of the two minerals. Calcite has a trigonal structure with two molecules per unit cell, and dolomite has a hexagonal structure. This is more likely to cause the splitting and distorting of the carbonate groups. Another cause for the difference is the cation substituting for Mg in the dolomite mineral. Copyright © 2013 Elsevier B.V. All rights reserved.

Thermochemical sulphate reduction can improve carbonate petroleum reservoir quality

NASA Astrophysics Data System (ADS)

Jiang, Lei; Worden, Richard H.; Yang, Changbing

2018-02-01

Interest in the creation of secondary pore spaces in petroleum reservoirs has increased because of a need to understand deeper and more complex reservoirs. The creation of new secondary porosity that enhances overall reservoir quality in deeply buried carbonate reservoirs is controversial and some recent studies have concluded it is not an important phenomenon. Here we present petrography, geochemistry, fluid inclusion data, and fluid-rock interaction reaction modeling results from Triassic Feixianguan Formation, Sichuan Basin, China, core samples and explore the relative importance of secondary porosity due to thermochemical sulphate reduction (TSR) during deep burial diagenesis. We find that new secondary pores result from the dissolution of anhydrite and possibly from dissolution of the matrix dolomite. Assuming porosity before TSR was 16% and the percentage of anhydrite was 6%, modelling shows that, due to TSR, 1.6% additional porosity was created that led to permeability increasing from 110 mD (range 72-168 mD within a 95% confidence interval) to 264 mD (range 162-432 mD within a 95% confidence interval). Secondary porosity results from the density differences between reactant anhydrite and product calcite, the addition of new water during TSR, and the generation of acidity during the reaction of new H2S with the siderite component in pre-existing dolomite in the reservoir. Fluid pressure was high during TSR, and approached lithostatic pressure in some samples; this transient overpressure may have led to the maintenance of porosity due to the inhibition of compactional processes. An additional 1.6% porosity is significant for reserve calculations, especially considering that it occurs in conjunction with elevated permeability that results in faster flow rates to the production wells.

Nanometer-scale features in dolomite from Pennsylvanian rocks, Paradox Basin, Utah

NASA Astrophysics Data System (ADS)

Gournay, Jonas P.; Kirkland, Brenda L.; Folk, Robert L.; Lynch, F. Leo

1999-07-01

Scanning electron microscopy reveals an association between early dolomite in the Pennsylvanian Desert Creek (Paradox Fm.) and small (approximately 0.1 μm) nanometer-scale textures, termed `nannobacteria'. Three diagenetically distinct dolomites are present: early dolomite, limpid dolomite, and baroque dolomite. In this study, only the early dolomite contained nanometer-scale features. These textures occur as discrete balls and rods, clumps of balls, and chains of balls. Precipitation experiments demonstrate that these textures may be the result of precipitation in an organic-rich micro-environment. The presence of these nanometer-scale textures in Pennsylvanian rocks suggests that these early dolomites precipitated in organic-rich, bacterial environments.

Controls on Cyclic Formation of Quaternary Early Diagenetic Dolomite

NASA Astrophysics Data System (ADS)

McCormack, J.; Bontognali, T. R. R.; Immenhauser, A.; Kwiecien, O.

2018-04-01

The origin of sedimentary dolomite and the factors that control its formation within the geological record remain speculative. In most models, dolomite formation is linked to evaporative conditions, high water temperature, increasing Mg/Ca ratio, increasing alkalinity, and high amounts of biomass. Here we challenge these archetypal views, by documenting a case example of Quaternary dolomite which formed in Lake Van at constantly low temperature (<4°C) and without direct control of the latter conditions. Dolomite occurs within highstand sediments related to suborbital climate variability (Dansgaard-Oeschger cycles). We propose that dolomite precipitation is a product of a microbially influenced process, triggered by ecological stress, resulting from reventilation of the water-sediment interface. Independently from the validity of this hypothesis, our results call for a reevaluation of the paleoenvironmental conditions often invoked for early diagenetic dolomite-rich intervals within sedimentary sequences and for caution when interpreting time series of subrecent lacustrine carbonates.

Origin of dolomite in the phosphatic Hawthorne Group of Florida

DOE Office of Scientific and Technical Information (OSTI.GOV)

Compton, J.S.; Hall, D.L.; Mallinson, D.J.

1994-07-01

In addition to large amounts of phosphorite, the Miocene Hawthorn Group of Florida contains abundant dolomite. Dolomite is present as disseminated silt-size rhombs, as friable dolosilt beds, and as pore-filling cement in dolostone beds and clasts. The dolomite formed during early burial diagenesis both in the sulfate-reduction zone, overlapping and extending below sediment depths of phosphorite formation, and in adjacent, nonphosphatic, shallow-water lagoonal environments. Much of the dolomite is closely associated with the fibrous, Mg-rich clay minerals palygorskite and sepiolite. The percent carbonate in the Hawthorn Group increases from north to south; the dominant carbonate mineral in north Florida ismore » dolomite, whereas dolomite and calcite are both abundant in south Florida. The [delta][sup 13]C values of the dolomite, from +1.82 to [minus]6.21[per thousand] PDB, suggest that metastable biogenic carbonate (aragonite and high-Mg calcite) and seawater were the predominant sources of carbonate. However, negative [delta][sup 13]C values of dolomite from northeast Florida suggest that as much as 30--40% of the carbonate was derived from degradation of organic matter. Degradation of organic matter enhanced dolomitization by removing sulfate ion and increasing the carbonate alkalinity of the pore waters. The oxygen and strontium isotopic values along with moderate Na contents indicate a marine origin. Evaporation of seawater or mixing of seawater and meteoric water were apparently not major factors in dolomite formation. The presence of dolomite, along with phosphorite, in reworked sequences can indicate deposition of organic-rich sediments from which most of the organic matter has since been removed.« less

The magnesium isotope (δ26Mg) signature of dolomites

NASA Astrophysics Data System (ADS)

Geske, A.; Goldstein, R. H.; Mavromatis, V.; Richter, D. K.; Buhl, D.; Kluge, T.; John, C. M.; Immenhauser, A.

2015-01-01

Dolomite precipitation models and kinetics are debated and complicated due to the complex and temporally fluctuating fluid chemistry and different diagenetic environments. Using well-established isotope systems (δ18O, δ13C, 87Sr/86Sr), fluid inclusions and elemental data, as well as a detailed sedimentological and petrographic data set, we established the precipitation environment and subsequent diagenetic pathways of a series of Proterozoic to Pleistocene syn-depositional marine evaporative (sabkha) dolomites, syn-depositional non-marine evaporative (lacustrine and palustrine) dolomites, altered marine ("mixing zone") dolomites and late diagenetic hydrothermal dolomites. These data form the prerequisite for a systematic investigation of dolomite magnesium isotope ratios (δ26Mgdol). Dolomite δ26Mg ratios documented here range, from -2.49‰ to -0.45‰ (δ26Mgmean = -1.75 ± 1.08‰, n = 42). The isotopically most depleted end member is represented by earliest diagenetic marine evaporative sabkha dolomites (-2.11 ± 0.54‰ 2σ, n = 14). In comparing ancient compositions to modern ones, some of the variation is probably due to alteration. Altered marine (-1.41 ± 0.64‰ 2σ, n = 4), and earliest diagenetic lacustrine and palustrine dolomites (-1.25 ± 0.86‰ 2σ, n = 14) are less negative than sabkha dolomites but not distinct in composition. Various hydrothermal dolomites are characterized by a comparatively wide range of δ26Mg ratios, with values of -1.44 ± 1.33‰ (2σ, n = 10). By using fluid inclusion data and clumped isotope thermometry (Δ47) to represent temperature of precipitation for hydrothermal dolomites, there is no correlation between fluid temperature (∼100 to 180 °C) and dolomite Mg isotope signature (R2 = 0.14); nor is there a correlation between δ26Mgdol and δ18Odol. Magnesium-isotope values of different dolomite types are affected by a complex array of different Mg sources and sinks, dissolution/precipitation and non

Dolomite surface speciation and reactivity in aquatic systems

NASA Astrophysics Data System (ADS)

Pokrovsky, Oleg S.; Schott, Jacques; Thomas, Fabien

1999-10-01

The surface charge of dolomite (CaMg(CO3)2) was measured as a function of pH (6.5-11.5), pCO2 (10-3.5, 0.01, and 0.96 atm) and ionic strength (0.01, 0.1, and 0.5 M NaCl) using potentiometric titrations in a limited residence time reactor. Dolomite zeta potential (ζ) was determined using streaming potential and electrophoresis techniques at pH 2 to 12 in solutions having ionic strengths from 0.001 to 0.1 M NaCl as a function of aqueous Ca2+, Mg2+, and CO32- concentrations. The point of zero charge (PZC) and isoelectric point (IEP) of dolomite are the same (pH ∼8 at pCO2 ∼10-3.5 atm) and very close to those of calcite and magnesite. On the basis of these results, a surface complexation model (SCM) is proposed that postulates the presence of three distinct primary hydration sites: >CO3H°, >CaOH°, and >MgOH°. The intrinsic stability constants of dolomite surface reactions were determined by fitting the pH dependence of the surface charge and taking into account the isoelectric points and ζ-potential values for a wide range of solution compositions. In most natural aquatic environments, dolomite surface speciation can be modeled using the following species: >CO3-, >CO3Me+, >MeOH2+, >MeHCO3o, and >MeCO3-, where Me = Ca, Mg. The speciation model presented in this study allows description of metal and ligand adsorption onto dolomite surface and provides new insights on the mechanisms that control dolomite dissolution/crystallization in aqueous solutions. In particular, it is shown that dolomite dissolution is controlled by the protonation of >CO3H° surface complexes at pH < 6 and by hydrolysis of >MeOH2+ groups at higher pH.

An application of geostatistics and fractal geometry for reservoir characterization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aasum, Y.; Kelkar, M.G.; Gupta, S.P.

1991-03-01

This paper presents an application of geostatistics and fractal geometry concepts for 2D characterization of rock properties (k and {phi}) in a dolomitic, layered-cake reservoir. The results indicate that lack of closely spaced data yield effectively random distributions of properties. Further, incorporation of geology reduces uncertainties in fractal interpolation of wellbore properties.

Hydrochemical processes and evolution of karst groundwater in the northeastern Huaibei Plain, China

NASA Astrophysics Data System (ADS)

Qian, Jiazhong; Peng, Yinxue; Zhao, Weidong; Ma, Lei; He, Xiaorui; Lu, YueHan

2018-06-01

Major ion geochemistry reveals that the hydrochemical evolutionary process of karst groundwater in the northeastern Huaibei Plain, China, consists of three sub-processes: the dissolution of dolomite, gypsum dissolution with dedolomitization, and mixing with overlying pore water. Understanding hydrochemical evolution has been an important topic in understanding the history, status, and dynamics of the groundwater flow system. The presented study found a hydrochemical boundary roughly corresponding to the thickness of overlying strata equating to 50 m depth, indicating two flow compartments participating in different hydrological cycles—a local shallow rapidly replenished compartment showing lower and more stable main ion concentrations, and a regional deep-flow compartment showing higher and sporadic concentrations of Na+, K+, Ca2+, Mg2+, Cl- and SO4 2-, as well as high total dissolved solids (TDS), total hardness, and sodium adsorption ratio (SAR). In areas with aquifers with low water transmitting ability, groundwater samples show a high chloride ratio and elevated TDS values, indicating salinization of groundwater due to stagnant water flows. Analyses of the data on the saturation indexes and mineral solutions, in tandem with trilinear diagram analysis and petrological observations, indicate that dedolomitization is the dominant process controlling the chemical characteristics of karst groundwater in the study area. Groundwater and pore-water mixing was also observed at the later evolutionary stage of groundwater flow, demonstrating frequent groundwater/pore-water interactions where groundwater is recharged by pore water due to lower groundwater level in the study area.

Development of a carbonate platform with potential for large discoveries - an example from Vietnam

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mayall, M.; Bent, A.; Dale, B.

1996-01-01

In offshore central and southern Vietnam a number of carbonate accumulations can be recognized. Platform carbonates form basin-wide units of carbonate characterized by strong, continuous parallel seismic reflectors. Facies are dominated by bioclastic wackestones with poor-moderate reservoir quality. On the more isolated highs, large buildups developed. These are typically 5-10 km across and 300 m thick. They unconformably overlie the platform carbonate facies which are extensively karstified. In places these are pinnacles, typically 2-5 km across, 300 m+ thick with chaotic or mounded internal seismic facies. The large carbonate buildups are characterized by steep sided slopes with talus cones, reef-marginmore » rims usually developed around only part of the buildup, and a prominent back-stepping geometry. Buildup interior facies form the main potential reservoirs They are dominated by fine to coarse grained coralgal packstones. Fine grained carbonates are associated with deeper water events and multiple karst surfaces can also be identified. Reservoir quality is excellent, largely controlled by extensive dissolution and dolomitization believed to be related to the exposure events. Gas has been found in a number of reservoirs. Heterogeneities can be recognized which could potentially effect production. These include the extensive finer grained facies, cementation or open fissures associated with the karst surfaces, a more cemented reef rim, shallowing upwards facies cycles and faults.« less

Development of a carbonate platform with potential for large discoveries - an example from Vietnam

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mayall, M.; Bent, A.; Dale, B.

1996-12-31

In offshore central and southern Vietnam a number of carbonate accumulations can be recognized. Platform carbonates form basin-wide units of carbonate characterized by strong, continuous parallel seismic reflectors. Facies are dominated by bioclastic wackestones with poor-moderate reservoir quality. On the more isolated highs, large buildups developed. These are typically 5-10 km across and 300 m thick. They unconformably overlie the platform carbonate facies which are extensively karstified. In places these are pinnacles, typically 2-5 km across, 300 m+ thick with chaotic or mounded internal seismic facies. The large carbonate buildups are characterized by steep sided slopes with talus cones, reef-marginmore » rims usually developed around only part of the buildup, and a prominent back-stepping geometry. Buildup interior facies form the main potential reservoirs They are dominated by fine to coarse grained coralgal packstones. Fine grained carbonates are associated with deeper water events and multiple karst surfaces can also be identified. Reservoir quality is excellent, largely controlled by extensive dissolution and dolomitization believed to be related to the exposure events. Gas has been found in a number of reservoirs. Heterogeneities can be recognized which could potentially effect production. These include the extensive finer grained facies, cementation or open fissures associated with the karst surfaces, a more cemented reef rim, shallowing upwards facies cycles and faults.« less

Zincian dolomite related to supergene alteration in the Iglesias mining district (SW Sardinia)

NASA Astrophysics Data System (ADS)

Boni, M.; Mondillo, N.; Balassone, G.; Joachimski, M.; Colella, A.

2013-01-01

One of the main effects of supergene alteration of ore-bearing hydrothermal dolomite in areas surrounding secondary zinc orebodies ( Calamine-type nonsulfides) in southwestern Sardinia (Italy) is the formation of a broad halo of Zn dolomite. The characteristics of supergene Zn dolomite have been investigated using scanning electron microscopy and qualitative energy-dispersive X-ray spectroscopy, thermodifferential analysis, and stable isotope geochemistry. The supergene Zn dolomite is characterized by variable amounts of Zn, and low contents of Pb and Cd in the crystal lattice. It is generally depleted in Fe and Mn relative to precursor hydrothermal dolomite ( Dolomia Geodica), which occurs in two phases (stoichiometric dolomite followed by Fe-Mn-Zn-rich dolomite), well distinct in geochemistry. Mg-rich smithsonite is commonly associated to Zn dolomite. Characterization of Zn-bearing dolomite using differential thermal analysis shows a drop in temperature of the first endothermic reaction of dolomite decomposition with increasing Zn contents in dolomite. The supergene Zn dolomites have higher δ18O but lower δ13C values than hydrothermal dolomite. In comparison with smithsonite-hydrozincite, the supergene Zn dolomites have higher δ18O, but comparable δ13C values. Formation of Zn dolomite from meteoric waters is indicated by low δ13C values, suggesting the influence of soil-gas CO2 in near-surface environments. The replacement of the dolomite host by supergene Zn dolomite is interpreted as part of a multistep process, starting with a progressive "zincitization" of the dolomite crystals, followed by a patchy dedolomitization s.s. and potentially concluded by the complete replacement of dolomite by smithsonite.

SWAT Model Prediction of Phosphorus Loading in a South Carolina Karst Watershed with a Downstream Embayment

Treesearch

Devendra M. Amatya; Manoj K. Jha; Thomas M. Williams; Amy E. Edwards; Daniel R. Hitchcock

2013-01-01

The SWAT model was used to predict total phosphorus (TP) loadings for a 1555-ha karst watershed—Chapel Branch Creek (CBC)—which drains to a lake via a reservoir-like embayment (R-E). The model was first tested for monthly streamflow predictions from tributaries draining three potential source areas as well as the downstream R-E, followed by TP loadings using data...

Geophysical imaging of karst features in Missouri

NASA Astrophysics Data System (ADS)

Obi, Jeremiah Chukwunonso

Automated electrical resistivity tomography (ERT) supported with multichannel analysis of surface waves (MASW) and boring data were used to map karst related features in Missouri in order to understand karst processes better in Missouri. Previous works on karst in Missouri were mostly surficial mapping of bedrock outcrops and joints, which are not enough to define the internal structure of karst system, since most critical processes in karst occur underground. To understand these processes better, the density, placement and pattern of karst related features like solution-widened joints and voids, as well as top of bedrock were mapped. In the course of the study, six study sites were visited in Missouri. The sites were in Nixa, Gasconade River Bridge in Lebanon, Battlefield, Aurora, Protem and Richland. The case studies reflect to a large extent some of the problems inherent in karst terrain, ranging from environmental problems to structural problems especially sinkhole collapses. The result of the study showed that karst in Missouri is mostly formed as a result of piping of sediments through solution-widened joints, with a pattern showing that the joints/fractures are mostly filled with moist clay-sized materials of low resistivity values. The highest density of mapped solution-widened joints was one in every one hundred and fifty feet, and these areas are where intense dissolution is taking place, and bedrock pervasively fractured. The study also showed that interpreted solution-widened joints trend in different directions, and often times conform with known structural lineaments in the area. About 40% of sinkhole collapses in the study areas are anthropogenic. Karst in Missouri varies, and can be classified as a combination of kI (juvenile), kIII (mature) and kIV (complex) karsts.

The role of sandstone in the development of an Ozark karst system, south-central Missouri

USGS Publications Warehouse

Orndorff, R.C.; Weary, D.J.; Harrison, R.W.

2006-01-01

Cave, spring, and sinkhole development in the Ozarks of south-central Missouri is placed in a geologic framework through detailed geologic mapping. Geologic mapping shows that initial dissolution and inception of cave development is concentrated just beneath sandstone beds within Upper Cambrian and Lower Ordovician dolostone. Although rocks of the Ozarks have systematic and pervasive vertical joints, the development of karst conduits is controlled by bedding planes and stratigraphic variability. In the Salem Plateau of south-central Missouri, sinkholes occur in the lower part of the Ordovician Roubidoux Formation, where sinkholes are rimmed with and contain sandstone that has collapsed into voids in the underlying Ordovician Gasconade Dolomite. Cave diving by the Ozark Cave Diving Alliance into Alley Spring, a large (average flow 3.7 m3/s) spring along the Jacks Fork in the Ozark National Scenic Riverways, shows that although the spring discharges from the middle part of the Gasconade, the source of water is a cave passage just beneath the Gunter Sandstone Member of the Gasconade Dolomite. Artesian conditions cause the upward movement of groundwater from cavernous dolostone beneath the sandstone aquitards to the large springs. We hypothesize that sandstone, which is largely impermeable due to silica cementation, acts as a confining unit where hydraulic pressure, combined with mixing of water of differing chemistry, increases dissolution in the underlying dolostone beds. ?? 2006 Geological Society of America.

Puerto Rican Karst-A Vital Resource

Treesearch

Ariel E. Lugo; Leopoldo Miranda Castro; Abel Vale; Tania del Mar López; Enrique Hernández Prieto; Andrés García Martinó; Alberto R. Puente Rolón; Adrianne G. Tossas; Donald A. McFarlane; Tom Miller; Armando Rodríguez; Joyce Lundberg; John Thomlinson; José Colón; Johannes H. Schellekens; Olga Ramos; Eileen Helmer

2001-01-01

The limestone region of Puerto Rico covers about 27.5 percent of the island’s surface and is subdivided into the northern, southern, and dispersed limestone areas. All limestone areas have karst features. The karst belt is that part of the northern limestone with the most spectacular surficial karst landforms. It covers 142,544 ha or 65 percent of the northern...

Karst hydrology and chemical contamination

DOE Office of Scientific and Technical Information (OSTI.GOV)

Field, M.S.

1993-01-01

Ground-water flow in karst aquifers is very different from flow in granular or fractured aquifers. Chemical contamination may be fed directly to a karst aquifer via overland flow to a sinkhole with little or no attenuation and may contaminate downgradient wells, springs, and sinkholes within a few hours or a few days. Contaminants may also become temporarily stored in the epikarstic zone for eventual release to the aquifer. Flood pulses may flush the contaminants to cause transiently higher levels of contamination in the aquifer and discharge points. The convergent nature of flow in karst aquifers may result in contaminants becomingmore » concentrated in conduits. Once contaminants have reached the subsurface conduits, they are likely to be rapidly transported to spring outlets. Traditional aquifer remediation techniques for contaminated aquifers are less applicable to karst aquifers.« less

Stochastic simulation of karst conduit networks

NASA Astrophysics Data System (ADS)

Pardo-Igúzquiza, Eulogio; Dowd, Peter A.; Xu, Chaoshui; Durán-Valsero, Juan José

2012-01-01

Karst aquifers have very high spatial heterogeneity. Essentially, they comprise a system of pipes (i.e., the network of conduits) superimposed on rock porosity and on a network of stratigraphic surfaces and fractures. This heterogeneity strongly influences the hydraulic behavior of the karst and it must be reproduced in any realistic numerical model of the karst system that is used as input to flow and transport modeling. However, the directly observed karst conduits are only a small part of the complete karst conduit system and knowledge of the complete conduit geometry and topology remains spatially limited and uncertain. Thus, there is a special interest in the stochastic simulation of networks of conduits that can be combined with fracture and rock porosity models to provide a realistic numerical model of the karst system. Furthermore, the simulated model may be of interest per se and other uses could be envisaged. The purpose of this paper is to present an efficient method for conditional and non-conditional stochastic simulation of karst conduit networks. The method comprises two stages: generation of conduit geometry and generation of topology. The approach adopted is a combination of a resampling method for generating conduit geometries from templates and a modified diffusion-limited aggregation method for generating the network topology. The authors show that the 3D karst conduit networks generated by the proposed method are statistically similar to observed karst conduit networks or to a hypothesized network model. The statistical similarity is in the sense of reproducing the tortuosity index of conduits, the fractal dimension of the network, the direction rose of directions, the Z-histogram and Ripley's K-function of the bifurcation points (which differs from a random allocation of those bifurcation points). The proposed method (1) is very flexible, (2) incorporates any experimental data (conditioning information) and (3) can easily be modified when

Destruction of dolines: the examples from Slovene karst

NASA Astrophysics Data System (ADS)

Kovacic, G.; Ravbar, N.

2012-04-01

Due to the absence of soil and flat agricultural land, in karst regions, the cultivation of doline bottoms and the clearing of stones on fields and meadows were traditional methods of adapting farming practices to the landscape with limited agricultural potential. In recent years, a variety of activities resulting from comprehensive economic and urban development have increased pressure on karst landscapes. In some areas the surface and the underground are increasingly threatened by industrial activities, uncontrolled settlement and spread of infrastructure, the development of tourism, and intensive agrarian land use. Unsupervised human encroachment on karst landscapes is causing the increasingly more frequent and more widespread degradation of karst relief forms. The intensive reshaping of the landscape has expanded beyond control largely as a result of technological development and mechanization. The excessive modern filling of dolines, as one of the most distinctive karst surface features, has become a major encroachment on the environment for leveling purposes. Such kind of human influence affects the shape of karst features and the appearance of the landscape as well as the intensity of karst processes such as corrosion. Many dolines are filled with general and construction waste, which threatens the existence of unique habitats and quality of groundwater and consequently water supply. This contribution presents some cases of inappropriate management of karst landscape in Slovenia and examines the national legislative framework on spatial planning in karst regions. Unfortunately, in the current legislation, the standards and conditions for the protection of karst landscape characteristics (e.g. dolines) are loose and not fully elaborated. Principally, there are no uniform mechanisms to protect specific relief forms or for the adequate protection of karst. To a large extent, the preservation of the characteristic karst landscape is left to local communities

Treating tar sands formations with dolomite

DOEpatents

Vinegar, Harold J.; Karanikas, John Michael

2010-06-08

Methods for treating a tar sands formation are described herein. The tar sands formation may include dolomite and hydrocarbons. Methods may include providing heat at less than the decomposition temperature of dolomite from one or more heaters to at least a portion of the formation. At least some of the hydrocarbon fluids are mobilized in the formation. At least some of the hydrocarbon fluids may be produced from the formation.

Invasive vascular plant species of limnocrenic karst springs in Poland

NASA Astrophysics Data System (ADS)

Spałek, Krzysztof

2015-04-01

Natural water reservoirs are very valuable floristic sites in Poland. Among them, the most important for preservation of biodiversity of flora are limnocrenic karst springs. The long-term process of human pressure on habitats of this type caused disturbance of their biological balance. Changes in the water regime, industrial development and chemisation of agriculture, especially in the period of last two hundred years, led to systematic disappearance of localities of many plant species connected with rare habitats and also to appear numerous invasive plant species. They are: Acorus calamus, Echinocystis lobata, Elodea canadensis, Erechtites hieraciifolia, Impatiens glandulifera, Solidago canadensis, S. gigantea and S. graminifolia. Fielworks were conducted in 2010-2014.

High Modulus Asphalt Concrete with Dolomite Aggregates

NASA Astrophysics Data System (ADS)

Haritonovs, V.; Tihonovs, J.; Smirnovs, J.

2015-11-01

Dolomite is one of the most widely available sedimentary rocks in the territory of Latvia. Dolomite quarries contain about 1,000 million tons of this material. However, according to Latvian Road Specifications, this dolomite cannot be used for average and high intensity roads because of its low quality, mainly, its LA index (The Los Angeles abrasion test). Therefore, mostly the imported magmatic rocks (granite, diabase, gabbro, basalt) or imported dolomite are used, which makes asphalt expensive. However, practical experience shows that even with these high quality materials roads exhibit rutting, fatigue, and thermal cracks. The aim of the research is to develop a high performance asphalt concrete for base and binder courses using only locally available aggregates. In order to achieve resistance against deformations at a high ambient temperature, a hard grade binder was used. Workability, fatigue and thermal cracking resistance, as well as sufficient water resistance is achieved by low porosity (3-5%) and higher binder content compared to traditional asphalt mixtures. The design of the asphalt includes a combination of empirical and performance based tests, which in laboratory circumstances allow simulating traffic and environmental loads. High performance AC 16 base asphalt concrete was created using local dolomite aggregate with polymer modified (PMB 10/40-65) and hard grade (B20/30) bitumen. The mixtures were specified based on fundamental properties in accordance with EN 13108-1 standard.

3D-Mapping of Dolomitized Structures in Lower Cambrian Phosphorites

NASA Astrophysics Data System (ADS)

Hippler, Dorothee; Stammeier, Jessica A.; Brunner, Roland; Rosc, Jördis; Franz, Gerhard; Dietzel, Martin

2016-04-01

Dolomitization is a widespread phenomenon in ancient sedimentary rocks, particularly close to the Precambrian-Cambrian boundary. Dolomite can form in synsedimentary or hydrothermal environments, preferentially via the replacement of solid carbonate precursor phases. Synsedimentary dolomite formation is often associated with microbial activity, such as bacterial sulfate reduction or methanogenesis. In this study, we investigate dolomitic phosphorites from the Lowermost Cambrian Tal Group, Mussoori Syncline, Lesser Himalaya, India, using micro-CT 3D-mapping, in order to unravel the complex diagenetic history of the rocks. The selected sample shows alternating layering of phosphatic mudstones and sparitic dolostone, in which brecciated layers of phosphorite or phosphatic mudstones are immersed in a dolomite-rich matrix. Lamination occurs on a sub-millimetre scale, with lamination sometimes wavy to crinkly. This fabric is interpreted as former microbial mats, providing the environment for early diagenetic phosphatization. Preliminary electron backscatter imaging with scanning microscopy revealed that dolomite crystals often occur in spherical to ellipsoidal structures, typically with a high porosity. This dolomite is associated with botryoidal apatite, organic matter and small amounts of calcite. Micro-CT 3D-mappings reveal that dolomite structures are cigar-shaped, elongated and up to 600 μm long. They are further arranged in a Mikado-like oriented framework spanning a layer thickness of a few millimetres. Analyses of ambient pore space, with similar elongated outlines and filled with organic matter, suggest a potential coherence of ambient pore space and shape of the dolomite structures. Allowing for other associated mineral phases, such as pyrite and silicates, and their spatial distribution, the present approach can be used to unravel distinct diagenetic reaction pathways, and might thus constrain the proxy potential of these Lower Cambrian dolomitic phosphorites

Relationship between fracturing and porogenesis in a carbonate reservoir: Example from the Middle Turonian Bireno Member in Jebel M'rhila, Central Tunisia

NASA Astrophysics Data System (ADS)

Haj Ali, Hajer; Belghithi, Hanen; Ouali, Jamel Abdennaceur; Touir, Jamel

2016-09-01

relationship between fracturing and the reservoir potentiality of dolomites and the dolomitization process. Although the porosity in dolomites is not important enough, its gradual lateral variation with the distance from the fractures reflects the role of the latter in the porogenesis. The field observation and the results of the petrographic and petrophysical analysis show that the fractures must have played a substantial role in conducting the meteoric waters from the emerged platform surface to its base and laterally, resulting in a cementing dolomitization and a solution-related porogenesis. Therefore, it seems that if the dolomitic Bireno Member is rather a good potential reservoir due to the associated fractures networks.

Enrico Fermi and the Dolomites

NASA Astrophysics Data System (ADS)

Battimelli, Giovanni; de Angelis, Alessandro

2014-11-01

Summer vacations in the Dolomites were a tradition among the professors of the Faculty of Mathematical and Physical Sciences at the University of Roma since the end of the XIX century. Beyond the academic walls, people like Tullio Levi-Civita, Federigo Enriques and Ugo Amaldi sr., together with their families, were meeting friends and colleagues in Cortina, San Vito, Dobbiaco, Vigo di Fassa and Selva, enjoying trekking together with scientific discussions. The tradition was transmitted to the next generations, in particular in the first half of the XX century, and the group of via Panisperna was directly connected: Edoardo Amaldi, the son of the mathematician Ugo sr., rented at least during two summers, in 1925 and in 1949, and in the winter of 1960, a house in San Vito di Cadore, and almost every year in the Dolomites; Enrico Fermi was a frequent guest. Many important steps in modern physics, in particular the development of the Fermi-Dirac statistics and the Fermi theory of beta decay, are related to scientific discussions held in the region of the Dolomites.

Dolomitization in a mixing zone of near-seawater composition, Late Pleistocene, northeastern Yucatan Peninsula

USGS Publications Warehouse

Ward, W. C.; Halley, Robert B.

1985-01-01

18O compositions of Yucatecan dolomite and of modern ground water suggest dolomite precipitation from mixed water ranging from about 75% seawater, 25% freshwater to nearly all seawater. (Isotope analyses are for the most stable calcian dolomites; more soluble, calcium-rich dolomite presumably is analyzed with calcite and thought to be isotopically lighter than the less soluble dolomite.) In the cement sequence, the most stable dolomite is followed by more soluble dolomite as ground water becomes less saline. Isotope analyses, together with position of dolomite in the cement sequence, suggest the most stable calcian dolomite (including limpid dolomite) precipitated from mixed water with large proportions of seawater, and the less stable, more calcian dolomite precipitated from fresher mixed water.

Modern and late Holocene dolomite formation: Manito Lake, Saskatchewan, Canada

NASA Astrophysics Data System (ADS)

Last, Fawn M.; Last, William M.; Halden, Norman M.

2012-12-01

Major advances have occurred in our understanding of modern dolomite formation and penecontemporaneous dolomitization over the past several decades. Manito Lake, located in west-central Saskatchewan, Canada, is a large (65 km2), deep (zmax: 22 m) perennial saline (~ 45 ppt TDS) lake in which modern and late Holocene dolomite coexists with other endogenic and authigenic carbonate precipitates, including aragonite, monohydrocalcite, calcite, and Mg-calcite. Like many other lacustrine dolomites, Manito Lake dolomite is microcrystalline (less than 1 μm to 5 μm), Ca-rich and poor to moderately ordered. It occurs as relatively pure hardgrounds and as a component of nearshore microbialites. It also forms isopachous cements in consolidated siliciclastic shoreline sediments. Manito Lake dolomite is most likely forming by mainly biomediated precipitation at or near the sediment-water interface (i) in pore spaces of coarse siliciclastic sediments (i.e., beachrock), (ii) as fine laminae associated with microbialites, and (iii) as a major component of mudstone hardgrounds and pavements.

Porosity, permeability and 3D fracture network characterisation of dolomite reservoir rock samples.

PubMed

Voorn, Maarten; Exner, Ulrike; Barnhoorn, Auke; Baud, Patrick; Reuschlé, Thierry

2015-03-01

With fractured rocks making up an important part of hydrocarbon reservoirs worldwide, detailed analysis of fractures and fracture networks is essential. However, common analyses on drill core and plug samples taken from such reservoirs (including hand specimen analysis, thin section analysis and laboratory porosity and permeability determination) however suffer from various problems, such as having a limited resolution, providing only 2D and no internal structure information, being destructive on the samples and/or not being representative for full fracture networks. In this paper, we therefore explore the use of an additional method - non-destructive 3D X-ray micro-Computed Tomography (μCT) - to obtain more information on such fractured samples. Seven plug-sized samples were selected from narrowly fractured rocks of the Hauptdolomit formation, taken from wellbores in the Vienna basin, Austria. These samples span a range of different fault rocks in a fault zone interpretation, from damage zone to fault core. We process the 3D μCT data in this study by a Hessian-based fracture filtering routine and can successfully extract porosity, fracture aperture, fracture density and fracture orientations - in bulk as well as locally. Additionally, thin sections made from selected plug samples provide 2D information with a much higher detail than the μCT data. Finally, gas- and water permeability measurements under confining pressure provide an important link (at least in order of magnitude) towards more realistic reservoir conditions. This study shows that 3D μCT can be applied efficiently on plug-sized samples of naturally fractured rocks, and that although there are limitations, several important parameters can be extracted. μCT can therefore be a useful addition to studies on such reservoir rocks, and provide valuable input for modelling and simulations. Also permeability experiments under confining pressure provide important additional insights. Combining these and

Karst development in central Butler County, Kansas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bain, B.A.

1993-02-01

Research was conducted to study the geology and hydrology of sinkholes, springs, and caves formed in Lower Permian, Fort Riley Limestone, located in central Butler County, Kansas. The goal was to better understand the controlling factors of these karst features and the processes that produce them in a portion of Kansas that is undergoing rapid population growth and increased groundwater usage. Research was accomplished in seven phases: literature search, locating karst features, measuring bedrock fracture joint trends, surveying major caves, estimating discharge of springs, dye tracing, and water chemistry analysis. Recognizable karst landforms within the study area were plotted ontomore » a base map to demonstrate their geographic, geologic, and hydrologic relationships. Karst features identified were 125 sinkholes, a major cave system composed of at least three enterable cave segments, and one large spring. The karst terrain found within the study area is clearly a system of interrelated features and processes. Long-term solution of the bedrock allows karst features to form, joints and bedding planes to enlarge, and creates an efficient network of subsurface drainage. Factors that control karst development in the study area are lithology, thickness, and dip of the bedrock; presence of well defined joints and bedding planes; relatively level topography; nearby entrenched river valleys; lack of thick surficial cover; and climate. Of these influences, solutional activity at joints plays a major role in the formation of sinkholes and cave passages; however, a complex combination of all the controlling factors is responsible for the present, unique, and dynamic karst system.« less

A new species of karst-adapted Cnemaspis Strauch, 1887 (Squamata: Gekkonidae) from a threatened karst region in Pahang, Peninsular Malaysia.

PubMed

Grismer, L Lee; Wood, Perry L; Mohamed, Maketab; Chan, Kin Onn; Heinz, Heather M; Sumarli, Alex S-I; Chan, Jacob A; Loredo, Ariel I

2013-12-12

A new species of karst-adapted gekkonid lizard of the genus Cnemaspis Strauch is described from Gua Gunting and Gua Goyang in a karst region of Merapoh, Pahang, Peninsular Malaysia whose unique limestone formations are in immediate danger of being quarried. The new species differs from all other species of Cnemaspis based on its unique suite of morphological and color pattern characters. Its discovery underscores the unique biodiversity endemic to karst regions and adds to a growing list of karst-adapted reptiles from Peninsular Malaysia. We posit that new karst-adapted species endemic to limestone forests will continue to be discovered and these regions will harbor a significant percentage of Peninsular Malaysia's biodiversity and thusly should be conserved rather than quarried.

High salinity facilitates dolomite precipitation mediated by Haloferax volcanii DS52

NASA Astrophysics Data System (ADS)

Qiu, Xuan; Wang, Hongmei; Yao, Yanchen; Duan, Yong

2017-08-01

Although most modern dolomites occur in hypersaline environments, the effects of elevated salinity on the microbial mediation of dolomite precipitation have not been fully evaluated. Here we report results of dolomite precipitation in association with a batch culture of Haloferax volcanii DS52, a halophilic archaeon, under various salinities (from 120‰ to 360‰) and the impact of salinity on microbe-mediated dolomite formation. The mineral phases, morphology and atomic arrangement of the precipitates were analyzed by XRD, SEM and TEM, respectively. The amount of amino acids on the archaeal cell surface was quantified by HPLC/MS. The XRD analysis indicated that disordered dolomite formed successfully with the facilitation of cells harvested from cultures with relatively high salinities (200‰ and 280‰) but was not observed in association with cells harvested from cultures with lower salinity (120‰) or the lysates of cells harvested from extremely high salinity (360‰). The TEM analysis demonstrated that the crystals from cultures with a salinity of 200‰ closely matched that of dolomite. Importantly, we found that more carboxyl groups were presented on the cell surface under high salinity conditions to resist the high osmotic pressure, which may result in the subsequent promotion of dolomite formation. Our finding suggests a link between variations in the hydro-chemical conditions and the formation of dolomite via microbial metabolic activity and enhances our understanding about the mechanism of microbially mediated dolomite formation under high salinity conditions.

Geochemistry and origin of regional dolomites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hanson, G.N.; Meyers, W.J.

1991-01-01

This grant supports the geochemical aspects of the research directed by Profs. W.J. Meyers and G.N. Hanson on the origins of regional dolomites. The field aspects and the stipend for most of the graduate students is provided by donations from oil companies and by grants from NSF and ACS-PRF. Eleven graduate students are involved in dolomite projects allowing diverse range of studies. Each student's results provide new insights to the others which invigorates all of the studies.

Magnesium Isotopic Evidence for Widespread Microbial Dolomite Precipitation in the Geological Record.

NASA Astrophysics Data System (ADS)

Carder, E. A.; Galy, A.; McKenzie, J. A.; Vasconcelos, C.; Elderfield, H.

2005-12-01

The enigma surrounding the `Dolomite Problem' is the relative abundance of dolomite in the geological record versus its very rare occurrence on the surface of the modern Earth despite a particularly favourable modern seawater chemistry. Recent studies of modern dolomite from hypersaline coastal lagoons in Brazil and Pleistocene dolomite from ODP cores collected during ODP Leg 201 on the Peru Margin suggest microbial mediation is an important factor [1]. Indeed, cultures of sulfate-reducing bacteria isolated from the lagoons mediate dolomite precipitation in the laboratory [2, 3]. In this study we report magnesium isotopic analyses of these modern microbial associated dolomites and ancient dolomites of a range of geological ages and environments. The application of stable magnesium isotopes to study dolomite formation and the nature of the processes involved represents a new frontier in isotope geochemistry. Highly accurate determination of the magnesium isotopic composition allows us to distinguish between kinetic and equilibrium isotope fractionation on the basis of the excess of 25Mg. A significant kinetic isotope fractionation is observed in laboratory cultures and surfical microbial mats from the Brazilian lagoons. Older dolomites (<3000 yrs.) taken from cores recovered from the lagoon are much closer to equilibrium. We interpret our data as evidencing an initial microbial mediated nucleation of dolomite that is a kinetic process and a subsequent inorganic addition of dolomite overprinting an equilibrium signature. This is in agreement with a previous major element and crystallographic study of the Brazilian dolomites [1]. The ancient dolomites analysed range in age from Neoproterozoic to Pleistocene and come from diverse geological environments including submarine diagenetic zones, platform carbonates and lagoonal environments. Magnesium isotopic analysis shows evidence of a varying component of kinetic fractionation, smaller than the kinetic end member as

Porosity, permeability and 3D fracture network characterisation of dolomite reservoir rock samples

PubMed Central

Voorn, Maarten; Exner, Ulrike; Barnhoorn, Auke; Baud, Patrick; Reuschlé, Thierry

2015-01-01

With fractured rocks making up an important part of hydrocarbon reservoirs worldwide, detailed analysis of fractures and fracture networks is essential. However, common analyses on drill core and plug samples taken from such reservoirs (including hand specimen analysis, thin section analysis and laboratory porosity and permeability determination) however suffer from various problems, such as having a limited resolution, providing only 2D and no internal structure information, being destructive on the samples and/or not being representative for full fracture networks. In this paper, we therefore explore the use of an additional method – non-destructive 3D X-ray micro-Computed Tomography (μCT) – to obtain more information on such fractured samples. Seven plug-sized samples were selected from narrowly fractured rocks of the Hauptdolomit formation, taken from wellbores in the Vienna basin, Austria. These samples span a range of different fault rocks in a fault zone interpretation, from damage zone to fault core. We process the 3D μCT data in this study by a Hessian-based fracture filtering routine and can successfully extract porosity, fracture aperture, fracture density and fracture orientations – in bulk as well as locally. Additionally, thin sections made from selected plug samples provide 2D information with a much higher detail than the μCT data. Finally, gas- and water permeability measurements under confining pressure provide an important link (at least in order of magnitude) towards more realistic reservoir conditions. This study shows that 3D μCT can be applied efficiently on plug-sized samples of naturally fractured rocks, and that although there are limitations, several important parameters can be extracted. μCT can therefore be a useful addition to studies on such reservoir rocks, and provide valuable input for modelling and simulations. Also permeability experiments under confining pressure provide important additional insights. Combining these

Dolomitization on an evaporitic Paleoproterozoic ramp: Widespread synsedimentary dolomite in the Denault Formation, Labrador Trough, Canada

NASA Astrophysics Data System (ADS)

Zentmyer, R. A.; Pufahl, P. K.; James, N. P.; Hiatt, E. E.

2011-06-01

The Denault Formation (2.1-1.9 Ga) crops out in the Labrador Trough, northeastern Québec and western Labrador. Rocks surrounding the town of Schefferville, Quebec contain textural characteristics consistent with deposition on the middle and outer portions of a storm-influenced shallow ramp. Mid-ramp facies consist of intraclastic grainstones with hummocky cross-stratification (HCS), swaley cross-stratification (SCS), current ripples, and graded event beds. Further outboard, grainstones grade into deeper-water laminites that are composed of even, mm-scale couplets of flat-lying organic and dolomudstone laminae. Scours within the laminites suggest periodic storm activity. Laminites gradually grade into outer ramp deep-water shales. An isolated eastern stromatolitic buildup is separated from these ramp facies by 50 km (present day). This succession can be interpreted as the remnant of a near-continuous margin or may simply represent an isolated accumulation that developed on a pre-existing topographic high. The presence of gypsum pseudomorphs in all lithofacies indicates that the Denault margin was restricted and evaporitic. Four paragenetic stages are recognized in the diagenetic evolution of the Denault Formation: (1) carbonate deposition, contemporaneous marine cementation, authigenic gypsum growth, and precipitation of authigenic chert; (2) synsedimentary mimetic dolomite precipitation; (3) pore-rimming and pore-occluding shallow burial dolomite cement; and (4) fabric destructive, sutured, anhedral burial dolomite. Gypsum crystals occur in all lithofacies, form the nuclei of interstitial dolomite rhombs, average 10 μm in length, and often display swallowtail twinning. Paleoproterozoic ocean water had very low concentrations of dissolved sulfate and evaporation in restricted settings would have been required to form gypsum. Formation of microcrystalline gypsum across this restricted ramp facilitated dolomite precipitation by increasing pore water Mg/Ca ratios and

Surface and subsurface continuous gravimetric monitoring of groundwater recharge processes through the karst vadose zone at Rochefort Cave (Belgium)

NASA Astrophysics Data System (ADS)

Watlet, A.; Van Camp, M. J.; Francis, O.; Poulain, A.; Hallet, V.; Triantafyllou, A.; Delforge, D.; Quinif, Y.; Van Ruymbeke, M.; Kaufmann, O.

2017-12-01

Ground-based gravimetry is a non-invasive and integrated tool to characterize hydrological processes in complex environments such as karsts or volcanoes. A problem in ground-based gravity measurements however concerns the lack of sensitivity in the first meters below the topographical surface, added to limited infiltration below the gravimeter building (umbrella effect). Such limitations disappear when measuring underground. Coupling surface and subsurface gravity measurements therefore allow isolating hydrological signals occurring in the zone between the two gravimeters. We present a coupled surface/subsurface continuous gravimetric monitoring of 2 years at the Rochefort Cave Laboratory (Belgium). The gravity record includes surface measurements of a GWR superconducting gravimeter and subsurface measurements of a Micro-g LaCoste gPhone gravimeter, installed in a cave 35 m below the surface station. The recharge of karstic aquifers is extremely complex to model, mostly because karst hydrological systems are composed of strongly heterogeneous flows. Most of the problem comes from the inadequacy of conventional measuring tools to correctly sample such heterogeneous media, and particularly the existence of a duality of flow types infiltrating the vadose zone: from rapid flows via open conduits to slow seepage through porous matrix. Using the surface/subsurface gravity difference, we were able to identify a significant seasonal groundwater recharge within the karst vadose zone. Seasonal or perennial perched reservoirs have already been proven to exist in several karst areas due to the heterogeneity of the porosity and permeability gradient in karstified carbonated rocks. Our gravimetric experiment allows assessing more precisely the recharge processes of such reservoirs. The gravity variations were also compared with surface and in-cave hydrogeological monitoring (i.e. soil moisture, in-cave percolating water discharges, water levels of the saturated zone). Combined

Geomorphological, pedological, and hydrological characteristics of karst lakes at Conversano (Apulia, southern Italy) as a basis for environmental protection

NASA Astrophysics Data System (ADS)

Lopez, N.; Spizzico, V.; Parise, M.

2009-07-01

The land around Conversano (Apulia, southern Italy) is part of the Murge karst, interesting limestones and dolomitic limestones of Upper Cretaceous age, in a flat environment with sub-horizontal setting. Dolines and karst depressions are the most typical landforms in the area. Filling of these landforms with eluvial deposits locally created the possibility of water stagnancy at the surface. The Conversano territory presents ten karst lakes that represented, until some decades ago, the only water resource available for the local people, who built the typical bell-shaped wells to collect water volumes satisfying local needs during the dry season. Currently, these lakes have no great importance as water supplies, but represent habitats of great naturalistic value that are still able to support the ecological functionality and the wet environments with self-vegetation. Hydrological and hydrogeological studies have been carried out with the aim to fully estimate the related environmental problems. For this purpose, the hydrogeologic data of historical time series have been collected and compared to those of the last 5 years; successively, according to the Thornthwaite method, a hydrological monthly balance has been evaluated to quantify the distribution of water volumes interacting annually between the surface water bodies and the underlying carbonate groundwater. This evaluation has highlighted the need to carefully consider all the parameters concurring to a right definition of water balance for a karst environment, where pedological features, climatic conditions and anthropogenic modifications to the environment represent the elements of a very delicate system. Particularly, on the basis of recent soil map and field surveys, a re-evaluation of the available water capacity, estimated in some 40 mm, has been carried out. The studies have highlighted the need to extend the environmental protection rules to larger areas around the lakes, e.g. at the catchment scale, with

What Can We Learn About Karst Aquifer Heterogeneity From Pumping Tests

NASA Astrophysics Data System (ADS)

Marechal, J. C.; Dewandel, B.; Ladouche, B.; Fleury, P.

2016-12-01

Due to the complexity and duality of flows, well-test interpretation into karst systems constitutes a challenging task for hydrogeologists. This is especially true when the pumping well intersects karst heterogeneities such as the conduit network. The method of diagnostic plots, widely used in oil industry, can be applied to karst hydrogeology. In this paper, the classical response of a well-test into a karst conduit is described on a log-log drawdown derivative curve. It allows identifying successive flow regimes corresponding to the contribution of various karst aquifer subsystems (fractured matrix, karst conduit, main karst drainage network) to the pumped well. In heterogeneous karst systems, the log-log diagnostic plot of drawdown and its derivative in the pumping well can help identifying departures in flow-geometry from the classical homogeneous radial case. Classically, the diagnostic plot can be divided into several portions with: (a) early data used for identifying the karst conduit storage; (b) intermediate data for identifying the type of aquifer model that should be used (e.g. double porosity, anisotropy...); and (c) late data for identifying the possible boundaries. This is illustrated on three examples from Mediterranean karsts in southern France. A one-month duratio pumping test on a well intersecting the main karst drainage network of the Cent-Fonts karst system shows (i) a preliminary contribution of the karst conduit storage capacity followed by (ii) linear flows into the fractured matrix. A pumping test on a well intersecting a small karst conduit of the Corbières karst system shows the existence of (i) bi-linear flow within both the karst conduit and the fractured matrix at early times, followed by (ii) radial flows within the fractured matrix and (iii) finally the contribution of a major karst cavity. A two-months duration pumping test on a deep confined karst aquifer under low permeability rocks into the Gardanne basin shows the existence of

Modern and Unconventional Approaches to Karst Hydrogeology

NASA Astrophysics Data System (ADS)

Sukop, M. C.

2017-12-01

Karst hydrogeology is frequently approached from a hydrograph/statistical perspective where precipitation/recharge inputs are converted to output hydrographs and the conversion process reflects the hydrology of the system. Karst catchments show hydrological response to short-term meteorological events and to long-term variation of large-scale atmospheric circulation. Modern approaches to analysis of these data include, for example, multiresolution wavelet techniques applied to understand relations between karst discharge and climate fields. Much less effort has been directed towards direct simulation of flow fields and transport phenomena in karst settings. This is primarily due to the lack of information on the detailed physical geometry of most karst systems. New mapping, sampling, and modeling techniques are beginning to enable direct simulation of flow and transport. A Conduit Flow Process (CFP) add-on to the USGS ModFlow model became available in 2007. FEFLOW and similar models are able to represent flows in individual conduits. Lattice Boltzmann models have also been applied to flow modeling in karst systems. Regarding quantitative measurement of karst system geometry, at scales to 0.1 m, X-ray computed tomography enables good detection of detailed (sub-millimeter) pore space in karstic rocks. Three-dimensional printing allows reconstruction of fragile high porosity rocks, and surrogate samples generated this way can then be subjected to laboratory testing. Borehole scales can be accessed with high-resolution ( 0.001 m) Digital Optical Borehole Imaging technologies and can provide virtual samples more representative of the true nature of karst aquifers than can obtained from coring. Subsequent extrapolation of such samples can generate three-dimensional models suitable for direct modeling of flow and transport. Finally, new cave mapping techniques are beginning to provide information than can be applied to direct simulation of flow. Due to flow rates and cave

Geochemistry and origin of regional dolomites

NASA Astrophysics Data System (ADS)

Hanson, G. N.; Meyers, W. J.

1989-12-01

The major goal of the carbonate research program at Stony Brook is to better understand the conditions and processes leading to regional diagenesis of carbonate rocks. Our research focuses on studies of ancient, massive dolostones, but we are also studying limestone diagenesis for its own importance, and as it relates to dolomitization. Our approach has been to carry out a very detailed petrographic and geochemical case study to the Mississippian Burlington-Keokuk Fms. of Iowa, Illinois and Missouri, and to develop this as a testing ground for new geochemical and modelling techniques, and for testing various models for regional dolomitization in epicontinental carbonates. The ideas and techniques developed in our Burlington-Keokuk studies are being expanded and applied to carbonate sequences of other ages (Devonian to Neogene), and other tectono-sedimentary settings. The emphasis of this report will be on new developments and results on the Burlington-Keokuk studies and on our diagenetic studies of other strata. Recent research on Burlington-Keokuk rocks include development and application of boron isotopes and the U--Th--Pb system to dolomite studies, investigations of porosity and permeability in the dolostones. Projects on other strata include dolomitization and limestones diagenesis of Devonian carbonates of Alberta and Western Australia, Miocene reefal carbonates of Spain, Neogene carbonates of Curacao and Bonaire, Waulsortian limestones of Ireland, modelling of trace elements and stable isotopes, and experimental growth of calcites to investigate crystallographic controls of trace element incorporation.

Karst landscapes and associated resources: a resource assessment.

Treesearch

James F. Baichtal; Douglas N. Swanston

1996-01-01

The Tongass National Forest contains world-class karst features and the largest concentration of associated dissolved caves known in the state of Alaska. This paper describes the dominant karst formation processes operating in southeast Alaska, the controlling geologic and hydrologic characteristics, and the influence of karst landscapes on associated forest resources...

A remote sensing study of regional variation in sinkhole morphology-Florida karst vs. Minnesota karst

NASA Astrophysics Data System (ADS)

Ernst, C. L.; Hadizadeh, J.; McCarty, J. L.

2010-12-01

In many regions of the United States, database technologies and GIS have facilitated spatial analysis of karst. The purpose of this research was to compare regional latitudinal variation in sinkhole karst morphology via remote sensing techniques. Such comparison may be significant because the development of a karst landscape depends primarily on climate and availability of water as well as lithology. Sinkhole karst, a common karst in the U.S., is morphologically defined as cone-shaped depressions with circular or oval opening to the surface that result from the dissolution of relatively soluble bedrock such as limestone or gypsum. The two regions of interest, north-central Florida and southeastern Minnesota, were selected based on structural and lithological similarity of limestone bedrock and the fact that the bedrock study areas are located in clearly different climate zones. This approach utilized topographic maps, digital elevation models, state karst feature databases, and high resolution 0.6m QuickBirdTM and 0.5m WorldView 1TM satellite images in a GIS environment. Morphological parameters - area, perimeter, minor axis and major axis length - were calculated on a total of 80 sinkholes in the study regions using the zonal geometry function, a tool in the spatial analysis extension provided by ESRITM. Our results show that north-central Florida and southeastern Minnesota karst are statistically different in terms of sinkhole shape and size distribution. Florida has larger sinkholes (2,835 square meter Mean) that are closer to circular shape. Minnesota has smaller (1,213 square meter Mean) and more elliptical sinkholes with a comparatively shorter minor axis. Of the possible explanations, climate appears to be the most likely cause for the observed differences. The higher amount of precipitation in Florida coupled with warmer year round temperatures provides an environment conducive to a more chemically involved hydrological regime, which may be responsible for

Spatial distribution of nitrogen on grazed karst landscapes.

PubMed

Boyer, D G; Alloush, G A

2001-11-27

The impact on water quality by agricultural activity in karst terrain is an important consideration for resource management within the Appalachian region. Karst areas comprise about 18% of the region"s land area. An estimated one-third of the region"s farms, cattle, and agricultural market value are located on karst terrain. Mean nitrate concentrations in several karst springs in southeastern West Virginia exhibit a strong linear relationship with the percentage of agriculture land cover. Development of best management practices for efficient nitrogen (N) use and reduction of outflow of N to water from karst areas requires knowledge about N dynamics on those landscapes. Water extractable NO3-N and NH4-N were measured along transects at four soil depths in two grazed sinkholes and one wooded sinkhole. Distribution of soil NO3-N and NH4-N were related to frequency of animal presence and to topographic and hydrologic redistribution of soil and fecal matter in the grazed sinkholes. Karst pastures are characterized by under drainage and funneling of water and contaminants to the shallow aquifer. Control of NO3-N leaching from karst pasture may depend on management strategies that change livestock grazing behavior in sinkholes and reduce the opportunity for water and contaminants to quickly reach sinkhole drains.

Influence of deformation on dolomite rim growth kinetics

NASA Astrophysics Data System (ADS)

Helpa, Vanessa; Rybacki, Erik; Grafulha Morales, Luiz Fernando; Dresen, Georg

2015-04-01

Using a gas-deformation apparatus stacks of oriented calcite (CaCO3) and magnesite (MgCO3) single crystals were deformed at T = 750° C and P = 400 MPa to examine the influence of stress and strain on magnesio-calcite and dolomite (CaMg[CO3]2) growth kinetics. Triaxial compression and torsion tests performed at constant stresses between 7 and 38 MPa and test durations between 4 and 171 hours resulted in bulk strains of 0.03-0.2 and maximum shear strains of 0.8-5.6, respectively. The reaction rims consist of fine-grained (2-7 μm) dolomite with palisade-shaped grains growing into magnesite reactants and equiaxed granular dolomite grains next to calcite. In between dolomite and pure calcite, magnesio-calcite grains evolved with an average grain size of 20-40 μm. Grain boundaries tend to be straighter at high bulk strains and equilibrium angles at grain triple junctions are common within the magnesio-calcite layer. Transmission electron microscopy shows almost dislocation free palisades and increasing dislocation density within granular dolomite towards the magnesio-calcite boundary. Within magnesio-calcite grains, dislocations are concentrated at grain boundaries. Variation of time at fixed stress (˜17 MPa) yields a parabolic time dependence of dolomite rim width, indicating diffusion-controlled growth, similar to isostatic rim growth behavior. In contrast, the magnesio-calcite layer growth is enhanced compared to isostatic conditions. Triaxial compression at given time shows no significant change of dolomite rim thickness (11±2 μm) and width of magnesio-calcite layers (33±5 μm) with increasing stress. In torsion experiments, reaction layer thickness and grain size decrease from the center (low stress/strain) to the edge (high strain/stress) of samples. Chemical analysis shows nearly stoichiometric composition of dolomite palisades, but enhanced Ca content within granular grains, indicating local disequilibrium with magnesio-calcite, in particular for twisted

Determination of the recharge area and salinization degree of karst springs in the Lamas Basin (Turkey).

PubMed

Yüce, Galip

2005-12-01

The Lamas Basin is an area covering approximately 4,400 km(2) situated on the eastern Mediterranean coast of Turkey covered with highly karstified limestone and dolomitic limestone from the Miocene and Mesozoic age, respectively. Owing to the area's low karstification basement, groundwater in the karst aquifer circulates deep from the surface towards the springs along the coast as well as to the submarine springs. This study aims working out the salinization level and recharge characteristics of the Lamas Basin using environmental isotopes techniques. In the study, the data collected previously to discover, in general terms, the groundwater characteristics within the area are reanalyzed to fulfil the purpose of the study. In conclusion, it is found that the down gradient karst springs discharging along the Mediterranean coast mostly contain groundwater contributions from higher altitudes with depleted delta(18)O and delta(2)H compositions. The delta(18)O-altitude effect was determined as approximately-0.12 per thousand/100 m which may indicate sea-spray intrusion towards inland. As a result, the salinization level of coastal springs changes ranging between 1.2 % and 17.0 %. Owing to the seawater encroachment, Ca-HCO(3) water type changes to Na-HCO(3) or Na-Cl water by the cation exchange during the dry period. As the unique freshwater potential extends along the coastal area, the groundwater production should be exploited in a way that seawater encroachment is kept at minimum.

Imaging groundwater infiltration dynamics in the karst vadose zone with long-term ERT monitoring

NASA Astrophysics Data System (ADS)

Watlet, Arnaud; Kaufmann, Olivier; Triantafyllou, Antoine; Poulain, Amaël; Chambers, Jonathan E.; Meldrum, Philip I.; Wilkinson, Paul B.; Hallet, Vincent; Quinif, Yves; Van Ruymbeke, Michel; Van Camp, Michel

2018-03-01

Water infiltration and recharge processes in karst systems are complex and difficult to measure with conventional hydrological methods. In particular, temporarily saturated groundwater reservoirs hosted in the vadose zone can play a buffering role in water infiltration. This results from the pronounced porosity and permeability contrasts created by local karstification processes of carbonate rocks. Analyses of time-lapse 2-D geoelectrical imaging over a period of 3 years at the Rochefort Cave Laboratory (RCL) site in south Belgium highlight variable hydrodynamics in a karst vadose zone. This represents the first long-term and permanently installed electrical resistivity tomography (ERT) monitoring in a karst landscape. The collected data were compared to conventional hydrological measurements (drip discharge monitoring, soil moisture and water conductivity data sets) and a detailed structural analysis of the local geological structures providing a thorough understanding of the groundwater infiltration. Seasonal changes affect all the imaged areas leading to increases in resistivity in spring and summer attributed to enhanced evapotranspiration, whereas winter is characterised by a general decrease in resistivity associated with a groundwater recharge of the vadose zone. Three types of hydrological dynamics, corresponding to areas with distinct lithological and structural features, could be identified via changes in resistivity: (D1) upper conductive layers, associated with clay-rich soil and epikarst, showing the highest variability related to weather conditions; (D2) deeper and more resistive limestone areas, characterised by variable degrees of porosity and clay contents, hence showing more diffuse seasonal variations; and (D3) a conductive fractured zone associated with damped seasonal dynamics, while showing a great variability similar to that of the upper layers in response to rainfall events. This study provides detailed images of the sources of drip

Experimental study of the mechanism and sequence of calcite-dolomite replacement

NASA Astrophysics Data System (ADS)

Moraila-Martinez, Teresita; Putnis, Christine V.; Putnis, Andrew

2015-04-01

For many years the formation, mechanism and environmental settings of dolomite formation have been under discussion, mainly because dolomite is commonly found in ancient rocks, whereas it is rarely present in modern sediments. The most favoured hypothesis is the 'dolomitization' of limestone by Mg-bearing aqueous solutions [1,2]. The existence of sharp limestone-dolomite contacts in natural rocks suggests that dolomitization involves a coupled dissolution-precipitation process. For a better understanding of the replacement mechanism of calcite by dolomite we performed hydrothermal experiments using Carrara marble cubes of 1.5 mm size, that reacted with 1M (Ca,Mg)Cl2 solutions with a Mg:Ca ratio of 3, at 200°C for different duration times (10, 20, 40, 50 and 58 days). After reaction, the product phases were characterized using Raman spectroscopy, electron microprobe analysis, and scanning electron microscopy. After reaction, the external morphology of the samples was preserved. Back-scattered images revealed two replacement end products: dolomite and magnesite. Grain boundaries of the samples were maintained. Shorter time duration experiments resulted in the replacement reaction occurring mainly along grain boundaries, whereas in longer duration time experiments more replacement was located in the core of the sample. In this type of reaction, grain boundaries are very important for the replacement to occur, acting as fluid pathways, allowing the infiltration of the solution further from the rock surface, enhancing fluid permeability within the sample and allowing further replacement reactions to occur. 1. Kaczmarek S.E., Sibley D.F. On the evolution of dolomite stoichiometry and cation order during high temperature synthesis experiments: An alternative model for geochemical evolution of natural dolomites. Sedimentary Geology. 240, 30-40 (2011). 2. Etschmann B., Brugger J., Pearce M.A., Ta C., Brautigan D., Jung M., Pring A. Grain boundaries as microreactors during

Analysis and application of classification methods of complex carbonate reservoirs

NASA Astrophysics Data System (ADS)

Li, Xiongyan; Qin, Ruibao; Ping, Haitao; Wei, Dan; Liu, Xiaomei

2018-06-01

There are abundant carbonate reservoirs from the Cenozoic to Mesozoic era in the Middle East. Due to variation in sedimentary environment and diagenetic process of carbonate reservoirs, several porosity types coexist in carbonate reservoirs. As a result, because of the complex lithologies and pore types as well as the impact of microfractures, the pore structure is very complicated. Therefore, it is difficult to accurately calculate the reservoir parameters. In order to accurately evaluate carbonate reservoirs, based on the pore structure evaluation of carbonate reservoirs, the classification methods of carbonate reservoirs are analyzed based on capillary pressure curves and flow units. Based on the capillary pressure curves, although the carbonate reservoirs can be classified, the relationship between porosity and permeability after classification is not ideal. On the basis of the flow units, the high-precision functional relationship between porosity and permeability after classification can be established. Therefore, the carbonate reservoirs can be quantitatively evaluated based on the classification of flow units. In the dolomite reservoirs, the average absolute error of calculated permeability decreases from 15.13 to 7.44 mD. Similarly, the average absolute error of calculated permeability of limestone reservoirs is reduced from 20.33 to 7.37 mD. Only by accurately characterizing pore structures and classifying reservoir types, reservoir parameters could be calculated accurately. Therefore, characterizing pore structures and classifying reservoir types are very important to accurate evaluation of complex carbonate reservoirs in the Middle East.

Estimating the proportion of groundwater recharge from flood events in relation to total annual recharge in a karst aquifer

NASA Astrophysics Data System (ADS)

Dvory, N. Z.; Ronen, A.; Livshitz, Y.; Adar, E.; Kuznetsov, M.; Yakirevich, A.

2017-12-01

Sustainable groundwater production from karstic aquifers is primarily dictated by its recharge rate. Therefore, in order to limit over-exploitation, it is essential to accurately quantify groundwater recharge. Infiltration during erratic floods in karstic basins may contribute substantial amount to aquifer recharge. However, the complicated nature of karst systems, which are characterized in part by multiple springs, sinkholes, and losing/gaining streams, present a large obstacle to accurately assess the actual contribution of flood water to groundwater recharge. In this study, we aim to quantify the proportion of groundwater recharge during flood events in relation to the annual recharge for karst aquifers. The role of karst conduits on flash flood infiltration was examined during four flood and artificial runoff events in the Sorek creek near Jerusalem, Israel. The events were monitored in short time steps (four minutes). This high resolution analysis is essential to accurately estimating surface flow volumes, which are of particular importance in arid and semi-arid climate where ephemeral flows may provide a substantial contribution to the groundwater reservoirs. For the present investigation, we distinguished between direct infiltration, percolation through karst conduits and diffused infiltration, which is most affected by evapotranspiration. A water balance was then calculated for the 2014/15 hydrologic year using the Hydrologic Engineering Center - Hydrologic Modelling System (HEC-HMS). Simulations show that an additional 8% to 24% of the annual recharge volume is added from runoff losses along the creek that infiltrate through the karst system into the aquifer. The results improve the understanding of recharge processes and support the use of the proposed methodology for quantifying groundwater recharge.

Geochemistry and origin of regional dolomites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hanson, G.N.; Meyers, W.J.

1989-12-01

The major goal of the carbonate research program at Stony Brook is to better understand the conditions and processes leading to regional diagenesis of carbonate rocks. Our research focuses on studies of ancient, massive dolostones, but we are also studying limestone diagenesis for its own importance, and as it relates to dolomitization. Our approach has been to carry out a very detailed petrographic and geochemical case study to the Mississippian Burlington-Keokuk Fms. of Iowa, Illinois and Missouri, and to develop this as a testing ground for new geochemical and modelling techniques, and for testing various models for regional dolomitization inmore » epicontinental carbonates. The ideas and techniques developed in our Burlington-Keokuk studies are being expanded and applied to carbonate sequences of other ages (Devonian to Neogene), and other tectono-sedimentary settings. The emphasis of this report will be on new developments and results on the Burlington-Keokuk studies and on our diagenetic studies of other strata. Recent research on Burlington-Keokuk rocks include development and application of boron isotopes and the U--Th--Pb system to dolomite studies, investigations of porosity and permeability in the dolostones. Projects on other strata include dolomitization and limestones diagenesis of Devonian carbonates of Alberta and Western Australia, Miocene reefal carbonates of Spain, Neogene carbonates of Curacao and Bonaire, Waulsortian limestones of Ireland, modelling of trace elements and stable isotopes, and experimental growth of calcites to investigate crystallographic controls of trace element incorporation. 118 refs., 46 figs.« less

Hydrogeological characterization and environmental effects of the deteriorating urban karst groundwater in a karst trough valley: Nanshan, SW China

NASA Astrophysics Data System (ADS)

Jiang, Yongjun; Cao, Min; Yuan, Daoxian; Zhang, Yuanzhu; He, Qiufang

2018-02-01

The unique hydrogeology of karst makes the associated groundwater respond quickly to rainfall events and vulnerable to anthropogenic pollutions. In this study, high-frequency monitoring of spring discharge, temperature, electrical conductivity (EC) and pH, along with monthly hydrochemical and microbial analyses, was undertaken at the outlet of Laolondong karst underground river in Nanshan, southwestern China. The aim was to explore the environmental effects of the catchment's urban area on the karst groundwater resources. The monitoring data of a tracer test and the response of discharge to rainfall events demonstrate that conduits and narrow fissures coexist in the Laolongdong karst aquifer. The EC, Na+, Cl- and SO4 2- values (840 μS/cm, 33.7, 38.6 and 137.2 μg/L, respectively), along with high concentrations of fecal coliform bacteria, at the outlet indicate considerable urban pollution in this area. The contaminants sulfate and nitrate showed different relationships with discharge and EC in different stages of a rainfall event. This behavior provided information about aquifer structure and the influence of transport properties. Meanwhile, the hydrological processes of groundwater flow could be modified by urbanization and result in increasing magnitude of urban floods in the underground river. In addition, sulfuric and nitric acids introduced by urbanization not only impact the karst groundwater quality, but also result in a significant perturbation to the carbon cycling system in the karst area.

GIS thematic layers for assessing karst hazard in Murgia region (Italy)

NASA Astrophysics Data System (ADS)

Canora, Filomena; D'Angella, Annachiara; Fidelibus, Dolores; Lella, Angela; Pellicani, Roberta; Spilotro, Giuseppe

2013-04-01

The assessment of karst hazard in a carbonate area may be somewhat complex for the multiplicity of involved factors (geological, hydrological, morphological, anthropogenic, etc.), their history and the slow rate of evolution of the processes. In coastal areas, moreover, the long term sea level variations and the short term oscillations generally influence the generation and evolution of the karst process. Another peculiarity of the karst hazard assessment consists in the difficulty for identifying the location of subsurface forms, which may develop over very large areas without any kind of surface signal. The karst processes and landforms often require specific methods of investigation and mitigation, due to the unique and highly variable characters of karst environments. In addition, the hidden character of the karst processes, often accelerated by human activity, is an issue with significant economic impact, affecting many regions of the world. The assessment of karst hazard in the Murgia plateau (in central-west of Apulia region) is the main goal of this research. For this aim, the typologies of karst phenomena, able to produce hazard in the study area, were individuated and collected in a specific database. The hazard was evaluated on the basis of the probability of occurrence of a phenomenon of instability, active (produced by human activities) or passive (natural evolution of karst process), in relation to the presence, evolution or generation of karst forms on surface or at critical distance from the surface. The critical distance from the surface is defined as the distance at which the local or general destructive evolution of a karst process can produce a variation of the usability of the area or of the value of elements involved in the instability. The thematic layers relative to the factors influencing karst processes and landforms (doline, sinkholes, polje, lame, gravine, caves) were elaborated and managed in a GIS system. The archives of the main karst

Karst database development in Minnesota: Design and data assembly

USGS Publications Warehouse

Gao, Y.; Alexander, E.C.; Tipping, R.G.

2005-01-01

The Karst Feature Database (KFD) of Minnesota is a relational GIS-based Database Management System (DBMS). Previous karst feature datasets used inconsistent attributes to describe karst features in different areas of Minnesota. Existing metadata were modified and standardized to represent a comprehensive metadata for all the karst features in Minnesota. Microsoft Access 2000 and ArcView 3.2 were used to develop this working database. Existing county and sub-county karst feature datasets have been assembled into the KFD, which is capable of visualizing and analyzing the entire data set. By November 17 2002, 11,682 karst features were stored in the KFD of Minnesota. Data tables are stored in a Microsoft Access 2000 DBMS and linked to corresponding ArcView applications. The current KFD of Minnesota has been moved from a Windows NT server to a Windows 2000 Citrix server accessible to researchers and planners through networked interfaces. ?? Springer-Verlag 2005.

Bacterially Induced Dolomite Formation in the Presence of Sulfate Ions under Aerobic Conditions

NASA Astrophysics Data System (ADS)

Sanchez-Roman, M.; McKenzie, J. A.; Vasconcelos, C.; Rivadeneyra, M.

2005-12-01

The origin of dolomite remains a long-standing enigma in sedimentary geology because, although thermodynamically favorable, precipitation of dolomite from modern seawater does not occur. Experiments conducted at elevated temperatures (200 oC) indicated that the presence of small concentrations of sulfate ions inhibits the transformation of calcite to dolomite [1]. Indeed, sulfate ions appeared to inhibit dolomite formation above 2 mM concentration (versus 28 mM in modern seawater). Recently, culture experiments have demonstrated that sulfate-reducing bacteria mediate the precipitation of dolomite at Earth surface conditions in the presence of sustained sulfate ion concentrations [2,3]. Additionally, in a number of modern hypersaline environments, dolomite forms from solutions with high sulfate ion concentrations (2 to 70 times seawater). These observations suggest that the experimentally observed sulfate-ion inhibition [1] may not apply to all ancient dolomite formation. Here, we report aerobic culture experiments conducted at low temperatures (25 and 35 oC) and variable sulfate ion concentrations (0, 0.5, 1 and 2 x seawater values) using moderately halophilic bacteria, Halomonas meridiana. After an incubation period of 15 days, experiments at 35 oC with variable sulfate ion concentrations (0, 0.5 x and seawater values) contained crystals of Ca-dolomite and stochiometric dolomite. The experiment at 35 oC with 2 x seawater sulfate ion concentration produced dolomite crystals after 20 days of incubation. In a parallel set of experiments at 25 oC, precipitation of dolomite was observed after 25 days of incubation in cultures with variable sulfate ion concentrations (0, 0.5 x and seawater values). In the culture with 2 x seawater sulfate ion concentration, dolomite crystals were observed after 30 days. Our study demonstrates that halophilic bacteria (or heterotrophic microorganisms), which do not require sulfate ions for metabolism, can mediate dolomite precipitation

Extreme grain size reduction in dolomite: microstructures and mechanisms.

NASA Astrophysics Data System (ADS)

Kennedy, L.; White, J. C.

2007-12-01

Pure dolomite sample were deformed at room temperature and under a variety of confining pressures (0 - 100MPa) to examine the processes of grain size reduction. The dolomite is composed of > 97 vol. % dolomite with accessory quartz, calcite, tremolite, and muscovite and has been metamorphosed to amphibolite facies and subsequently annealed. At the hand sample scale, the rock is isotropic, except for minor, randomly oriented tremolite porphyroblasts, and weakly aligned muscovite. At the thin section scale, coarser grains have lobate grain boundaries, exhibit minor to no undulose extinction and few deformation twins, although well- developed subgrains are present. Growth twins are common, as is the presence of well developed {1011} cleavage. Mean grain size 476 microns, and porosity is essentially zero (Austin and Kennedy, 2006). Samples contain diagonal to subvertical faults. Fractures are lined with an exceptionally fine-grained, powdered dolomite. Even experiments done at no confining pressure and stopped before sliding on the fracture surfaces occurred had significant powdered gouge developed along the surfaces. In this regard, fracturing of low porosity, pure dolomite, with metamorphic textures (e.g. lobate, interlocking grain boundaries) results in the development of fine-grained gouge. As expected the dolomite exhibited an increase in strength with increasing confining pressure, with a maximum differential stress of ~400MPa at 100 MPa confining pressure. At each chosen confining pressure, two experiments were performed and stopped at different stages along the load-displacement curve: just before yield stress and at peak stress. Microstructures at each stage were observed in order to determine the possible mechanisms for extreme grain size reduction. SEM work shows that in samples with little to no apparent displacement along microfractures, extreme grain size reduction still exists, suggesting that frictional sliding and subsequent cataclasis may not be the

Integration of potential and quasipotential geophysical fields and GPR data for delineation of buried karst terranes in complex environments

NASA Astrophysics Data System (ADS)

Eppelbaum, L. V.; Alperovich, L. S.; Zheludev, V.; Ezersky, M.; Al-Zoubi, A.; Levi, E.

2012-04-01

Karst is found on particularly soluble rocks, especially limestone, marble, and dolomite (carbonate rocks), but is also developed on gypsum and rock salt. Subsurface carbonate rocks involved in karst groundwater circulation considerably extend the active karst realm, to perhaps 14% of the world's land area (Price, 2009). The phenomenon of the solution weathering of limestone is the most widely known in the world. Active sinkholes growth appears under different industrial constructions, roads, railways, bridges, airports, buildings, etc. Regions with arid and semi-arid climate occupy about 30% of the Earth's land. Subsurface in arid regions is characterized by high variability of physical properties both on lateral and vertical that complicates geophysical survey analysis. Therefore for localization and monitoring of karst terranes effective and reliable geophysical methodologies should be applied. Such advanced methods were developed in microgravity (Eppelbaum et al., 2008; Eppelbaum, 2011b), magnetic (Khesin et al., 1996; Eppelbaum et al., 2000, 2004; Eppelbaum, 2011a), induced polarization (Khesin et al., 1997; Eppelbaum and Khesin, 2002), VLF (Eppelbaum and Khesin, 1992; Eppelbaum and Mishne, 2012), near-surface temperature (Eppelbaum, 2009), self-potential (Khesin et al., 1996; Eppelbaum and Khesin, 2002), and resistivity (Eppelbaum, 1999, 2007a) surveys. Application of some of these methodologies in the western and eastern shores of the Dead Sea area (e.g., Eppelbaum et al., 2008; Ezersky et al., 2010; Al-Zoubi et al., 2011) and in other regions of the world (Eppelbaum, 2007a) has shown their effectiveness. The common procedures for ring structure identification against the noise background and probabilistic-deterministic methods for recognizing the desired targets in complex media are presented in Khesin and Eppelbaum (1997), Eppelbaum et al. (2003), and Eppelbaum (2007b). For integrated analysis of different geophysical fields (including GPR images) intended

U.S. Geological Survey Karst Interest Group Proceedings, Carlsbad, New Mexico, April 29-May 2, 2014

USGS Publications Warehouse

Kuniansky, Eve L.; Spangler, Lawrence E.; Kuniansky, Eve L.; Spangler, Lawrence E.

2014-01-01

Karst aquifer systems are present throughout parts of the United States and some of its territories, and have developed in carbonate rocks (primarily limestone and dolomite) that span an interval of time encompassing more than 550 million years. The depositional environments, diagenetic processes, post-depositional tectonic events, and geochemical weathering processes that form karst aquifers are varied and complex, and involve biological, chemical, and physical changes. These factors, combined with the diverse climatic regimes under which karst development in these rocks has taken place, result in the unique dual- or triple-porosity nature of karst aquifers. These complex hydrogeologic systems typically represent challenging and unique conditions to scientists attempting to study groundwater flow and contaminant transport in these terrains.The dissolution of carbonate rocks and the subsequent development of distinct and beautiful landscapes, caverns, and springs has resulted in the most exceptional karst areas of the United States being designated as national or state parks; commercial caverns and known privately owned caves number in the tens of thousands. Both public and private properties provide access for scientists to study the flow of groundwater in situ. Likewise, the range and complexity of landforms and groundwater flow systems associated with karst terrains are enormous, perhaps more than for any other aquifer type. Karst aquifers and landscapes that form in tropical areas, such as the cockpit karst along the north coast of Puerto Rico, differ greatly from karst landforms in more arid climates, such as the Edwards Plateau in west-central Texas or the Guadalupe Mountains near Carlsbad, New Mexico, where hypogenic processes have played a major role in speleogenesis. Many of these public and private lands also contain unique flora and fauna associated with these karst hydrogeologic systems. As a result, numerous federal, state, and local agencies have a

Effects of karst and geologic structure on the circulation of water and permeability in carbonate aquifers

USGS Publications Warehouse

Stringfield, V.T.; Rapp, J.R.; Anders, R.B.

1979-01-01

The results of the natural processes caused by solution and leaching of limestone, dolomite, gypsum, salt and other soluble rocks, is known as karst. Development of karst is commonly known as karstification, which may have a pronounced effect on the topography, hydrology and environment, especially where such karst features as sinkholes and vertical solution shafts extend below the land surface and intersect lateral solution passages, cavities, caverns and other karst features in carbonate rocks. Karst features may be divided into two groups: (1) surficial features that do not extend far below the surface; and (2) karst features such as sinkholes that extend below the surface and affect the circulation of water below. The permeability of the most productive carbonate aquifers is due chiefly to enlargement of fractures and other openings by circulation of water. Important controlling factors responsible for the development of karst and permeability in carbonate aquifers include: (1) climate, topography, and presence of soluble rocks; (2) geologic structure; (3) nature of underground circulation; and (4) base level. Another important factor is the condition of the surface of the carbonate rocks at the time they are exposed to meteoric water. A carbonate rock surface, with soil or relatively permeable, less soluble cover, is more favorable for initiation of karstification and solution than bare rocks. Water percolates downward through the cover to the underlying carbonate rocks instead of running off on the surface. Also, the water becomes more corrosive as it percolates through the permeable cover to the underlying carbonate rocks. Where there is no cover or the cover has been removed, the carbonate rocks become case hardened and resistant to erosion. However, in regions underlain not only by carbonate rocks but also by beds of anhydrite, gypsum and salt, such as the Hueco Plateau in southeastern New Mexico, subsurface solution may occur where water without natural

Transport of agricultural contaminants through karst soil

USDA-ARS?s Scientific Manuscript database

Karst landscapes are common in many agricultural regions in the US. Well-developed karst landscapes are characterized by shallow soils, sinkholes, sinking streams, underground conduits, and springs. In these landscapes surface runoff is minimal and most recharge enters the subsurface relatively quic...

Comparison of the diagenetic and reservoir quality evolution between the anticline crest and flank of an Upper Jurassic carbonate gas reservoir, Abu Dhabi, United Arab Emirates

NASA Astrophysics Data System (ADS)

Morad, Daniel; Nader, Fadi H.; Gasparrini, Marta; Morad, Sadoon; Rossi, Carlos; Marchionda, Elisabetta; Al Darmaki, Fatima; Martines, Marco; Hellevang, Helge

2018-05-01

This petrographic, stable isotopic and fluid inclusion microthermometric study of the Upper Jurassic limestones of an onshore field, Abu Dhabi, United Arab Emirates (UAE) compares diagenesis in flanks and crest of the anticline. The results revealed that the diagenetic and related reservoir quality evolution occurred during three phases, including: (i) eogenesis to mesogenesis 1, during which reservoir quality across the field was either deteriorated or preserved by calcite cementation presumably derived from marine or evolved marine pore waters. Improvement of reservoir quality was due to the formation of micropores by micritization of allochems and creation of moldic/intragranular pores by dissolution of peloids and skeletal fragments. (ii) Obduction of Oman ophiolites and formation of the anticline of the studied field was accompanied by cementation by saddle dolomite and blocky calcite. High homogenization temperatures (125-175 °C) and high salinity (19-26 wt% NaCl eq) of the fluid inclusions, negative δ18OVPDB values (-7.7 to -2.9‰), saddle shape of dolomite, and the presence of exotic cements (i.e. fluorite and sphalerite) suggest that these carbonates were formed by flux of hot basinal brines, probably related to this tectonic compression event. (iii) Mesogenesis 2 during subsidence subsequent to the obduction event, which resulted in extensive stylolitization and cementation by calcite. This calcite cement occluded most of the remaining moldic and inter-/intragranular pores of the flank limestones (water zone) whereas porosity was preserved in the crest. This study contributes to: (1) our understanding of differences in the impact of diagenesis on reservoir quality evolution in flanks and crests of anticlines, i.e. impact of hydrocarbon emplacement on diagenesis, and (2) relating various diagenetic processes to burial history and tectonic events of foreland basins in the Arabian Gulf area and elsewhere.

Wet-dry seasonal and vertical geochemical variations in soil water and their driving forces under different land covers in southwest China karst

NASA Astrophysics Data System (ADS)

Wang, Peng; Hu, Bill X.; Wu, Chuanhao; Xu, Kai

2017-04-01

Karst aquifers supply drinking water for 25% of the world's population, and they are, however, vulnerable to climate change. Bimonthly hydrochemical data in karst soil water samples from July 2010 to July 2011 were obtained to reveal the seasonal and vertical geochemical variations in soil water under five vegetation types in Qingmuguan, a small karst catchment in southwest China. Soil water chemistry was dominated by Ca2+, HCO3-, and SO42- because of the dissolution of limestone, dolomite, and gypsum minerals in the strata. The predominant hydrochemical types in soil water were Ca2+-HCO3-, Ca2+-SO42-, and mixed Ca2+-HCO3-SO42-. Ca2+ and HCO3- concentrations ranked in the following order: shrub land > dry land > afforestation farmland > bamboo land > grassland. In warm and wet seasons, the main ion concentrations in soil water from grasslands were low. Na+, K+, Ca2+, Mg2+, HCO3-, SO42-, and Cl- concentrations in soil water from other lands were high. An opposite trend was observed in cold and dry seasons. Marked seasonal variations were observed in Ca2+, HCO3-, and NO3- in soil water from dry land. The main ion concentrations in soil water from bamboo lands decreased as soil depth increased. By contrast, the chemistry of soil water from other lands increased as soil depth increased. Their ions were accumulated in depth. A consistent high and low variation between the main ions in soil water and the contents of carbonate and CO2 was found in the soil. Hydrochemical changes in soil water were regulated by the effects of dilution and soil CO2.

Relationship between anisotropies of permeability, electrical conductivity, and dielectric permittivity, with application to the Ellenburger dolomite reservoir analog

NASA Astrophysics Data System (ADS)

Kutemi, Titilope F.

The steady-state flow technique was employed to measure the flow rate of clean dry air through thirty core plugs (approximately 1" diameter) of the Ellenburger dolomite, drilled normal and parallel to the dominant fractures. Porosity was estimated by the method of imbibition. Electrical parameters (electrical conductivity and dielectric permittivity) were calculated from electrical resistance and capacitance measured as a function of frequency (100 Hz, 120 Hz, 1 KHz, and 10 KHz) and saturation (dry/ambient and brine saturated conditions). Another set of permeability data obtained by the method of pressure decay on similar samples was used for correlation. Anisotropies of permeability and electromagnetic parameters were established. Empirical relations between porosity (phi), permeability (k), electrical conductivity (sigma), and dielectric permittivity (epsilon) were defined via cross-plots and linear regressions. Prediction of k from sigma and epsilon was attempted; k from sigma was modeled from a combination of the Archie's relation and the Carman-Kozeny relation. Anisotropic EM responses are sensitive to saturation. Anisotropies of conductivity and permeability were observed to be controlled by the pore micro-structure. Although the rock is fractured, the fracture density appears insufficient to dominate the effects of primary structures in these samples of the Ellenburger dolomite. Model-based prediction of permeability from conductivity is generally unreliable, and is attributed to the underlying assumptions of the models, which are not consistent with the properties of the samples used for this study. Permeability was not predictable from dielectric permittivity.

The genetic structure of the chloride ion runoff on the example of karst and non-karst geosystems of Arkhangelsk oblast

NASA Astrophysics Data System (ADS)

Khayrullina, D. N.; Kurzhanova, A. A.

2018-01-01

This paper deals with the estimate the structure of the chloride ion runoff from the karst (on the example of the Sula river basin) and non-karst (on the example of the Vaga river basin) geosystems of Arkhangelsk oblast. The contribution of the surface component predominates in the structure of the chloride ion runoff.For example, the input of surface ion runoff is 49% (for the Sula river basin), 55% (for the Vaga river basin). In time aspect the highest values of variability of the components of the chloride ion runoff are noted for karst geosystems and vary from 38.5% to 55.4% and from 24.7% to 42.9% - for non-karst geosystems.Finally, there is prevalence of the local factors influence because the atmospheric component decreases while ion runoff increases.

Carbonate microfacies analysis of penecontemporaneous dolomites of the Carnian Travenanzes Formation (Southern Alps, Italy)

NASA Astrophysics Data System (ADS)

Niebergall, Simon Michael; Breda, Anna; Preto, Nereo; Habler, Gerlinde; Peckmann, Jörn; Meister, Patrick

2016-04-01

Abundant dolomite (MgCa(CO3)2) occurs in the Middle and Late Triassic carbonate record of the Tethys realm. Whereas dolomite formation is largely related to late diagenesis and/or hydrothermal activity, Preto et al. (2015) suggested a primary origin of dolomite beds and nodules intercalated in clay rich deposits of the Carnian Travenanzes Formation (Fm.; Dolomites, Venetian Alps) based on a transmission electron microscopy study. Thus, dolomites of the Travenanzes Fm. are supposed to have formed during or soon after deposition and its petrographic features may still be indicative of the geochemical conditions prevalent in the depositional setting. The Travenanzes Fm. records both carbonate and siliciclastic input, reflecting a transitional continental to shallow marine environment (Breda and Preto, 2011) with alternations of alluvial plains, sabkhas and/or ephemeral lakes. The goal of this study is to determine the microfacies of the dolomites of the Travenanzes Fm. and to discuss possible depositional environments and scenarios of penecontemporaneous dolomite formation. The samples were taken from the Dibona section described by Breda and Preto (2011). Optical microscopy documented three different types of dolomite: (1) Microcrystalline nodular dolomite shows abundant clay interlayers and fenestral pores filled with coelestine and barite. The homogenous microcrystalline dolomite was further investigated by electron backscatter diffraction (EBSD) mapping, revealing an anhedral to subhedral microstructure of grains ranging from 2 to 10 micrometers in diameter. Some dolomite grew as spherules within the clay matrix. (2) Dolomite pebbles show semi-rounded edges in a dolosparitic matrix. (3) Dolomite with mm- to cm-scale lamination shows regularly spaced undulation with the cuspate side directed upwards. The laminae are also commonly affected by brittle or plastic deformation. Based on the petrographic observations, the following conclusions can be drawn: (1) While the

Re-evaluation of temperature of replacement dolomitization in the Triassic Latemar platform with clumped isotope thermometry

NASA Astrophysics Data System (ADS)

Müller, Inigo Andreas; Rodriguez-Blanco, Juan D.; Storck, Julian-Christopher; Benning, Liane G.; Wilson, Edith N.; Brack, Peter; Bernasconi, Stefano M.

2017-04-01

The Triassic Latemar platform shows different types of dolomitization styles including features such as dolomitized zones around basaltic dykes and patchy reddish or greyish dolomitization features in the central part of the platform. The processes leading to this partial dolomitization are still debated. Different geochemical tools were applied to determine the formation temperature of the patchy dolomite phases, thereby microthermometry on fluid inclusions and clumped isotope thermometry revealed significantly different temperature ranges (100 to 200 °C vs. 40 to 80 °C, from Wilson et al., 1990 and Ferry et al., 2011, respectively). We re-evaluated the origin of these patchy dolomites at Latemar using a new dolomite-specific clumped isotope temperature calibration based on dolomites synthetized in the laboratory at different temperatures. We directly compare the clumped isotope temperatures of patchy dolomites from Latemar with those obtained on the same samples by fluid inclusion microthermometry. With the new dolomite specific clumped isotope temperature calibration it is possible to determine more precisely the dolomite formation temperature and the oxygen isotope composition of the fluid source. Both are critical parameters for better constraining the origin of different dolomite fabrics on the Earth's surface and in ancient sediments. E.N. Wilson, L.A. Hardie and O.M. Phillips, 1990. Dolomitization front geometry, fluid flow patterns, and the origin of massive dolomite: the Triassic Latemar buildup, northern Italy. American Journal of Science 290, 741-796. J.M. Ferry, B.H. Passey, C. Vasconcelos and J.M. Eiler, 2011. Formation of dolomite at 40-80 °C in the Latemar carbonate buildup, Dolomites, Italy, from clumped isotope thermometry. Geology 39, 571-574.

An Experimental Investigation of Infiltration in a Shallow Karst System

NASA Astrophysics Data System (ADS)

Bellin, A.; Becker, M. W.; Borsato, A.

2008-12-01

We present preliminary results of a field investigation of infiltration in a karst terrain in the Dolomiti del Brenta ridge, North-East Italy. A sub-horizontal cave 40 m deep drains a small catchment of about 6,000 m2 at the elevation of 2,600 m a.s.l. in a fractured triassic dolomite formation. The surface is characterized by a thin soil cover, vertical fractures, and karst collapse features (dolines). Water infiltrates through the dolines and vertical shafts which are connected to an unsaturated cave system. Within the cave, water discharge, temperature, and electric conductivity are recorded. Meterological conditions were measured at a weather station installed within the cave contributing area. Furthermore, in order to study residence time distribution in the summer 2007 we conducted a tracer experiment by injecting fluorescein in one of the dolines and recording its concentration within the cave. The recorded time series are statistically non-stationary with a wavelet spectrum strongly variable in time. However, a closer inspection of the water discharge wavelet spectrum reveals three periods in which the local power spectrum is nearly time invariant: November-April, April -July and August-October. In the first period we observe a slow exponential decline of the water discharge. The season is dominated by release of water from subsurface storage, in absence of surface input. In the second period, the system is dominated by snowmelt with a time lag that reduces from 9 hours to 1 hour through the melting season. The variation in time apparently corresponds with reduction in snowpack thickness. In the final period, the system is dominated by rainfall. The lag time in this period is on the order of 1 hour or less. These results suggest that in this hydrologic system the distribution of the residence time, and thus the transfer function relating input to output signals, is not state invariant, as typically assumed in applications. Rather, hydraulic residence time

Facies interfingering and synsedimentary tectonics on late Ladinian-early Carnian carbonate platforms (Dolomites, Italy)

NASA Astrophysics Data System (ADS)

Keim, Lorenz; Brandner, Rainer

2001-11-01

A stratigraphic model for carbonate platform evolution in the Dolomites during the late Ladinian-early Carnian is presented. New light on pre-Raibl growth of individual carbonate platforms of the western Dolomites was shed by biostratigraphic data combined with a revised lithostratigraphy. At the Schlern, Langkofel and Sella, the carbonate factory (Upper Schlern Dolomite) remained productive into the lowermost Carnian (Cordevolian = Aon Zone), and caused a levelling-out of the former steep platform-to-basin relief. In the eastern Dolomites, platforms were producing till basal Julian 2 (Austriacum Zone). At the Sella and Langkofel, the sedimentation pattern after deposition of the Upper Schlern Dolomite was strongly influenced by synsedimentary tectonics. A first phase of extensional tectonics led to local fissures, block-tilting, graben structures and breccia deposits. Composition and fabric of the reworked clasts argue for local-source sediments and short transport distances. The extensional structures are sealed by sediments of Lower Carnian age. Two facies belts (Schlernplateau beds and Dürrenstein Dolomite), which interfinger at the western side of the Sella, reflect the shallow marine environment with terrigenous-volcanoclastic input in the western Dolomites. A second generation of breccias at the Sella documents local fracturing of the Dürrenstein and Upper Schlern Dolomite. Depositional environments across the western and eastern Dolomites were largely dependent on differential subsidence. The sediments of early Carnian age on top of the Schlern platform are a few metres thick only, whereas, in the eastern Dolomite, up to 400-m-thick carbonate sediments ('Richthofen reef' and Settsass platform) were deposited. The most incomplete stratigraphic record is present at the Mendel platform in the west, where Ladinian volcanics are unconformably overlain by late Carnian 'Raibl beds'. The increase in sediment thickness towards the eastern Dolomites becomes partly

Dolomite clumped isotope constraints on the oxygen isotope composition of the Phanerozoic Sea

NASA Astrophysics Data System (ADS)

Ryb, U.; Eiler, J. M.

2017-12-01

The δ18O value of the Phanerozoic Sea has been debated several decades, largely motivated by an 8‰ increase in δ18O of sedimentary carbonates between the Cambrian and the present. Some previous studies have interpreted this increase to be a primary depositional signal, resulting from an increase in the 18O content of ocean water over time, or from a decrease in ocean temperature increasing the oxygen isotope fractionation between seawater and carbonates. In contrast, other studies have interpreted lower δ18O compositions as the products of diagenetic alteration at elevated burial temperatures. Here, we show that the Phanerozoic dolomite δ18O record overlaps with that of well-preserved calcite fossils, and use carbonate clumped isotope measurements of Cambrian to Pleistocene dolomites to calculate their formation temperatures and the isotopic compositions of their parent-waters. The observed variation in dolomite δ18O is largely explained by dolomite formation at burial temperatures of up to 158°C. The δ18O values of dolomite parent-waters range -2 to +12‰ and are correlated with formation temperatures. Such correlation is consistent with the modification of seawater (0±2‰, VSMOW) toward isotopically heavier compositions through water-rock reactions at elevated burial temperatures. The similarity between the dolomite and calcite δ18O records, and published clumped isotope-based calculations of water compositions, suggests that like dolomite, temporal variations of the calcite δ18O record may also be largely driven by diagenetic alteration. Finally, the relationship we observe between temperature of dolomitization and d18O of dolomite suggests platform carbonates generally undergo dolomitization through reaction with modified marine waters, and that there is no evidence those waters were ever significantly lower in d18O than the modern ocean.

Structure and Stability of High-Pressure Dolomite with Implications for the Earth's Deep Carbon Cycle

NASA Astrophysics Data System (ADS)

Solomatova, N. V.; Asimow, P. D.

2014-12-01

Carbon is subducted into the mantle primarily in the form of metasomatically calcium-enriched basaltic rock, calcified serpentinites and carbonaceous ooze. The fate of these carbonates in subduction zones is not well understood. End-member CaMg(CO3)2 dolomite typically breaks down into two carbonates at 2-7 GPa, which may further decompose to oxides and CO2-bearing fluid. However, high-pressure X-ray diffraction experiments have recently shown that the presence of iron may be sufficient to stabilize dolomite I to high pressures, allowing the transformation to dolomite II at 17 GPa and subsequently to dolomite III at 35 GPa [1][2]. Such phases may be a principal host for deeply subducted carbon. The structure and equation of state of these high-pressure phases is debated and the effect of varying concentrations of iron is unknown, creating a need for theoretical calculations. Here we compare calculated dolomite structures to experimentally observed phases. Using the Vienna ab-initio simulation package (VASP) interfaced with a genetic algorithm that predicts crystal structures (USPEX), a monoclinic phase with space group 5 ("dolomite sg5") was found for pure end-member dolomite. Dolomite sg5 has a lower energy than reported dolomite structures and an equation of state that resembles that of dolomite III. It is possible that dolomite sg5 is not achieved experimentally due to a large energy barrier and a correspondingly large required volume drop, resulting in the transformation to metastable dolomite II. Due to the complex energy landscape for candidate high-pressure dolomite structures, it is likely that several competing polymorphs exist. Determining the behavior of high-pressure Ca-Mg-Fe(-Mn) dolomite phases in subduction environments is critical for our understanding of the Earth's deep carbon cycle and supercell calculations with Fe substitution are in progress. [1] Mao, Z., Armentrout, M., Rainey, E., Manning, C. E., Dera, P., Prakapenka, V. B., and Kavner, A

Transport of environmental tracers through a karst system with a thick unsaturated zone

NASA Astrophysics Data System (ADS)

Geyer, Tobias; Sültenfuss, Jürgen; Eichinger, Florian; Sauter, Martin

2010-05-01

is about 15 years with a travel time of water through the unsaturated zone of 10 years (Geyer 2008). This result reflects the variation of estimated ages for different tracers sampled at the Gallusquelle spring. Additionally, we demonstrate that depending on boundary conditions, the unsaturated zone of a karst system may provide a large water storage since the porous matrix can be expected to be close to saturation and the volume fraction of fissures and conduits is small. Literature Cornaton, F., Perrochet, P. (2006): Ground-water age, life expectancy and transit time distributions in advective-dispersive systems: 1. Generalized reservoir theory. - Advances in Water Resources 29 (9): 1267-1291. Geyer, T. (2008): Characterisation of flow and transport in karst aquifers at catchment scale, Ph.D. diss., Georg-August-Universität Göttingen, 103 pp.

Conduit enlargement in an eogenetic karst aquifer

NASA Astrophysics Data System (ADS)

Moore, Paul J.; Martin, Jonathan B.; Screaton, Elizabeth J.; Neuhoff, Philip S.

2010-11-01

SummaryMost concepts of conduit development have focused on telogenetic karst aquifers, where low matrix permeability focuses flow and dissolution along joints, fractures, and bedding planes. However, conduits also exist in eogenetic karst aquifers, despite high matrix permeability which accounts for a significant component of flow. This study investigates dissolution within a 6-km long conduit system in the eogenetic Upper Floridan aquifer of north-central Florida that begins with a continuous source of allogenic recharge at the Santa Fe River Sink and discharges from a first-magnitude spring at the Santa Fe River Rise. Three sources of water to the conduit include the allogenic recharge, diffuse recharge through epikarst, and mineralized water upwelling from depth. Results of sampling and inverse modeling using PHREEQC suggest that dissolution within the conduit is episodic, occurring only during 30% of 16 sampling times between March 2003 and April 2007. During low flow conditions, carbonate saturated water flows from the matrix to the conduit, restricting contact between undersaturated allogenic water with the conduit wall. When gradients reverse during high flow conditions, undersaturated allogenic recharge enters the matrix. During these limited periods, estimates of dissolution within the conduit suggest wall retreat averages about 4 × 10 -6 m/day, in agreement with upper estimates of maximum wall retreat for telogenetic karst. Because dissolution is episodic, time-averaged dissolution rates in the sink-rise system results in a wall retreat rate of about 7 × 10 -7 m/day, which is at the lower end of wall retreat for telogenetic karst. Because of the high permeability matrix, conduits in eogenetic karst thus enlarge not just at the walls of fractures or pre-existing conduits such as those in telogenetic karst, but also may produce a friable halo surrounding the conduits that may be removed by additional mechanical processes. These observations stress the

Soil nitrogen biogeochemical cycles in karst ecosystems, southwest China

NASA Astrophysics Data System (ADS)

Li, Dejun; Chen, Hao; Xiao, Kongcao; Wang, Kelin

2017-04-01

Soil nitrogen (N) status are crucial for ecosystem development and carbon sequestration. Although most terrestrial ecosystems are proposed to be limited by N, some tropical low-land forests have been found to be N saturated. Nevertheless, soil N status in the karst ecosystems of southwest China have not been well assessed so far. In the present study, N status in the karst ecosystems were evaluated based on several lines of evidence. Bulk N content increased rapidly along a post-agricultural succession sequence including cropland, grassland, shrubland, secondary forest and primary forest. Across the sequence, soil N accumulated with an average rate of 12.4 g N m-2 yr-1. Soil N stock recovered to the primary forest level in about 67 years following agricultural abandonment. Nitrate concentrations increased while ammonium concentrations decreased with years following agricultural abandonment. N release from bedrock weathering was likely a potential N source in addition to atmospheric N deposition and biological N fixation. Both gross N mineralization and nitrification (GN) rates decreased initially and then increased greatly following agricultural abandonment. The rate of dissimilatory nitrate reduction to ammonium (DNRA) was highest in the shrubland while lowest in the cropland and forest. Across the vegetation types, DNRA was lowest among the gross rates. Gross ammonium immobilization (GAI) tended to decrease while there was no clear variation pattern for gross nitrate immobilization during the post-agricultural succession. DNRA and nitrate assimilation combined only accounted for 22% to 57% of gross nitrification across the vegetation types. Due to the high nitrate production while low nitrate consumption, net nitrate production was found to vary following the pattern of gross nitrification and explained 69% of soil nitrate variance. Comparison of gross N transformations between a secondary karst forest and an adjacent non-karst forest showed that the gross rates

Sediment carbon fate in phreatic karst (Part 1): Conceptual model development

NASA Astrophysics Data System (ADS)

Husic, A.; Fox, J.; Agouridis, C.; Currens, J.; Ford, W.; Taylor, C.

2017-06-01

Recent research has paid increased attention to quantifying the fate of carbon pools within fluvial networks, but few, if any, studies consider the fate of sediment organic carbon in fluviokarst systems despite that karst landscapes cover 12% of the earth's land surface. The authors develop a conceptual model of sediment carbon fate in karst terrain with specific emphasis upon phreatic karst conduits, i.e., those located below the groundwater table that have the potential to trap surface-derived sediment and turnover carbon. To assist with their conceptual model development, the authors study a phreatic system and apply a mixture of methods traditional and novel to karst studies, including electrical resistivity imaging, well drilling, instantaneous velocimetry, dye tracing, stage recording, discrete and continuous sediment and water quality sampling, and elemental and stable carbon isotope fingerprinting. Results show that the sediment transport carrying capacity of the phreatic karst water is orders of magnitude less than surface streams during storm-activated periods promoting deposition of fine sediments in the phreatic karst. However, the sediment transport carrying capacity is sustained long after the hydrologic event has ended leading to sediment resuspension and prolonged transport. The surficial fine grained laminae occurs in the subsurface karst system; but unlike surface streams, the light-limited conditions of the subsurface karst promotes constant heterotrophy leading to carbon turnover. The coupling of the hydrological processes leads to a conceptual model that frames phreatic karst as a biologically active conveyor of sediment carbon that recharges degraded organic carbon back to surface streams. For example, fluvial sediment is estimated to lose 30% of its organic carbon by mass during a one year temporary residence within the phreatic karst. It is recommended that scientists consider karst pathways when attempting to estimate organic matter stocks

Karst Landscape, China

NASA Image and Video Library

2014-04-28

Karst topography is a geological formation shaped by the dissolution of layers of soluble rock such as limestone. A good example is found in Guangxi Province in southeast China, as seen by NASA Terra spacecraft.

Research approach to teaching groundwater biodegradation in karst aquifers

USGS Publications Warehouse

King, L.; Byl, T.; Painter, R.

2006-01-01

TSU in partnership with the USGS has conducted extensive research regarding biode??gradation of contaminants in karst aquifers. This research resulted in the development of a numerical approach to modeling biodegradation of contaminants in karst aquifers that is taught to environmental engineering students in several steps. First, environmental engineering students are taught chemical-reaction engineering principles relating to a wide variety of environmental fate and transport issues. Second, as part of TSU's engineering course curriculum, students use a non-ideal flow laboratory reactor system and run a tracer study to establish residence time distribution (RTD). Next, the students couple that formula to a first-order biodegradation rate and predict the removal of a biodegradable contaminant as a function of residence time. Following this, students are shown data collected from karst bedrock wells that suggest that karst aquifers are analogous to non-ideal flow reactors. The students are challenged to develop rates of biodegradation through lab studies and use their results to predict biodegradaton at an actual contaminated karst site. Field studies are also conducted to determine the accuracy of the students' predictions. This academic approach teaches biodegradation processes, rate-kinetic processes, hydraulic processes and numerical principles. The students are able to experience how chemical engineering principles can be applied to other situations, such as, modeling biodegradation of contaminants in karst aquifers. This paper provides background on the chemical engineering principles and karst issues used in the research-enhanced curriculum. ?? American Society for Engineering Education, 2006.

Dolomitized cells within chert of the Permian Assistência Formation, Paraná Basin, Brazil

NASA Astrophysics Data System (ADS)

Calça, Cléber P.; Fairchild, Thomas R.; Cavalazzi, Barbara; Hachiro, Jorge; Petri, Setembrino; Huila, Manuel Fernando Gonzalez; Toma, Henrique E.; Araki, Koiti

2016-04-01

Dolomitic microscopic structures in the form of microspheres, "horseshoe- shaped" objects, and thin botryoidal crusts found within microfossiliferous chert within stromatolites of the Evaporite Bed (EB) of the Permian Assistência Formation, Irati Subgroup, Paraná Basin, Brazil, have been investigated by means of optical microscopy, X-ray fluorescence, scanning electron microscopy, Raman spectrometry and energy-dispersive X-ray spectrometry. The microspheres were identified as dolomitized coccoidal cyanobacteria based on similarity in size, spheroidal and paired hemispheroidal morphologies and colonial habit to co-occurring silicified organic-walled cyanobacteria embedded within the same microfabric and rock samples. The co-occurrence of dolomite, pyrite framboids, and abundant dispersed carbonaceous material and silicified cells is consistent with a hypersaline depositional environment with abundant cyanobacterial mats and elevated Mg2 +/Ca2 + ratios and reducing conditions with active anoxic microbial processes near the water-(bio)sediment interface. The abundance of extracellular polymeric substances facilitated anoxic microbial processes (sulfate reduction), providing essential conditions for possible primary microbially induced dolomitization. In most of the dolomitized cells dolomite occurs only as an external layer; in fully dolomitized cells magnesium is richest in the outermost layer. Presumably, the dolomitization process was favored by the presence of anoxic microbial degraders and negatively charged functional groups at the surface of the cyanobacterial cells. Botryoidal dolomite rims of silica-filled fenestrae formed by a similar process and inherited the botryoidal morphology of the cell as originally lining the fenestrae. Silicification interrupted the dolomitization of the largely organic biosediment, mostly by permineralization, but locally by substitution, thereby preserving not only dolomitic microspheres, but also huge numbers of structurally

Improved reservoir characterisation using fuzzy logic platform: an integrated petrophysical, seismic structural and poststack inversion study

NASA Astrophysics Data System (ADS)

Jafri, Muhammad Kamran; Lashin, Aref; Ibrahim, El-Khedr Hassan; Hassanein, Kamal A.; Al Arifi, Nassir; Naeem, Muhammad

2017-06-01

There is a tendency for applying different integrated geophysical approaches for better hydrocarbon reservoir characterisation and interpretation. In this study, petrophysical properties, seismic structural and poststack seismic inversion results are integrated using the fuzzy logic AND operator to characterise the Tensleep Sandstone Formation (TSF) at Powder River Basin (PRB), Wyoming, USA. TSF is deposited in a coastal plain setting during the Pennsylvanian era, and contains cross-bedded sandstone of Aeolian origin as a major lithology with alternative sabkha dolomite/carbonates. Wireline logging datasets from 17 wells are used for the detailed petrophysical evaluation. Three units of the TSF (A-sandstone, B-dolomite and B-sandstone) are targeted and their major rock properties estimated (i.e. shale/clay volume, Vsh; porosity, φEff permeability, K; fluid saturations, Sw and SH; and bulk volume water, BVW). The B-sandstone zone, with its petrophysical properties of 5-20% effective porosity, 0.10-250 mD permeability and hydrocarbon potential up to 72%, is considered the best reservoir zone among the three studied units. Distributions of the most important petrophysical parameters of the B-sandstone reservoir (Vsh, φEff, K, Sw) are generated as GIS thematic layers. The two-dimensional (2D) and three-dimensional (3D) seismic structural interpretations revealed that the hydrocarbons are entrapped in an anticlinal structure bounded with fault closures at the west of the study area. Poststack acoustic impedance (PSAI) inversion is performed on 3D seismic data to extract the inverted acoustic impedance (AI) cube. Two attribute slices (inverted AI and seismic amplitude) were extracted at the top of the B-sandstone unit as GIS thematic layers. The reservoir properties and inverted seismic attributes were then integrated using fuzzy AND operator. Finally, a fuzzy reservoir quality map was produced, and a prospective reservoir area with best reservoir characteristics is

Dolomitic marbles from the ultrahigh-pressure metamorphic Kimi complex in Rhodope, N.E. Greece

NASA Astrophysics Data System (ADS)

Mposkos, E.; Baziotis, I.; Proyer, A.; Hoinkes, G.

2006-09-01

Dolomitic marbles from the Organi and Pandrosos areas of the ultrahigh-pressure (UHP) metamorphic Kimi complex in East Rhodope, N.E. Greece have the mineral assemblage: Cal + Dol + Ol + Phl ± Di ± Hbl ± Spl ± Ti Chu + retrograde Srp and Chl. Several generations of calcite and dolomite with variable composition and texture represent different stages of the P T evolution: The first stage is represented by matrix dolomite (X_MgCO_3 = 0.48) and relic domains of homogenous composition in matrix calcite (X_MgCO_3 = 0.11 0.13); the second stage is evident from precipitation of lath-shaped and vermicular dolomite in matrix calcite. The third stage is represented by veinlets of almost pure CaCO3 and domainal replacement of prior calcite by nearly pure CaCO3 + Ca-rich dolomite (X_MgCO_3 = 0.34 0.43). Matrix dolomite adjacent to CaCO3 veinlets also becomes Ca-rich (X_MgCO_3 = 0.42). In fact, Ca-rich dolomites with X_MgCO_3 in the range of 0.40 0.34 are reported for the first time from metamorphic marbles. Coexisting Ca-rich dolomite and Mg-poor calcite cannot be explained by the calcite-dolomite miscibility gap. This assemblage rather suggests that Mg-poor calcite was aragonite originally, which formed together with Ca-rich dolomite according to the reaction Mg Cal → Arg + Dol (1) at ultrahigh pressures and temperatures above at least 850 °C, when dolomite becomes disordered and incorporates more Ca than coexisting aragonite does in terms of Mg. The simplest explanation of these observations probably is to suggest two metamorphic events: The first one represented by relic matrix carbonates at relatively low to moderate pressures and temperatures of ca. 750 °C, and the second one limited by the minimum temperatures for dolomite disorder (ca. 850 °C) and in the aragonite + dolomite stability field, i.e. at a minimum pressure of 3 GPa and, if the presence of diamond-bearing metapelites nearby is considered, at conditions of at least 850 °C and 4.3 GPa in the diamond

U.S. Geological Survey Karst Interest Group Proceedings, San Antonio, Texas, May 16–18, 2017

USGS Publications Warehouse

Kuniansky, Eve L.; Spangler, Lawrence E.

2017-05-15

Introduction and AcknowledgmentsKarst aquifer systems are present throughout parts of the United States and some of its territories, and have developed in carbonate rocks (primarily limestone and dolomite) and evaporites (gypsum, anhydrite, and halite) that span an interval of time encompassing more than 550 million years. The depositional environments, diagenetic processes, post-depositional tectonic events, and geochemical weathering processes that form karst aquifers are varied and complex. These factors involve biological, chemical, and physical changes that when combined with the diverse climatic regimes in which karst development has taken place, result in the unique dual- or triple-porosity nature of karst aquifers. These complex hydrogeologic systems typically represent challenging and unique conditions to scientists attempting to study groundwater flow and contaminant transport in these terrains.The dissolution of carbonate rocks and the subsequent development of distinct and beautiful landscapes, caverns, and springs have resulted in the most exceptional karst areas being designated as national or state parks. Tens of thousands of similar areas in the United States have been developed into commercial caverns and known privately owned caves. Both public and private properties provide access for scientists to study the flow of groundwater in situ. Likewise, the range and complexity of landforms and groundwater flow systems associated with karst terrains are enormous, perhaps more than for any other aquifer type. Karst aquifers and landscapes that form in tropical areas, such as the cockpit karst along the north coast of Puerto Rico, differ greatly from karst landforms in more arid climates, such as the Edwards Plateau in west-central Texas or the Guadalupe Mountains near Carlsbad, New Mexico, where hypogenic processes have played a major role in speleogenesis. Many of these public and private lands also contain unique flora and fauna associated with these

Petroleum produced water disposal: Mobility and transport of barium in sandstone and dolomite rocks.

PubMed

Ebrahimi, Pouyan; Vilcáez, Javier

2018-09-01

To assess the risk of underground sources of drinking water contamination by barium (Ba) present in petroleum produced water disposed into deep saline aquifers, we examined the effect of salinity (NaCl), competition of cations (Ca, Mg), temperature (22 and 60°C), and organic fracturing additives (guar gum) on the sorption and transport of Ba in dolomites and sandstones. We found that at typical concentration levels of NaCl, Ca, and Mg in petroleum produced water, Ba sorption in both dolomites and sandstones is inhibited by the formation of Ba(Cl) + complexes in solution and/or the competition of cations for binding sites of minerals. The inhibition of Ba sorption by both mechanisms is greater in dolomites than in sandstones. This is reflected by a larger decrease in the breakthrough times of Ba through dolomites than through sandstones. We found that the presence of guar gum has little influence on the sorption and thus the transport of Ba in both dolomites and sandstones. Contrary to most heavy metals, Ba sorption in both dolomites and sandstones decreases with increasing temperature, however the reducing effect of temperature on Ba sorption is relevant only at low salinity conditions. Higher inhibition of Ba sorption in dolomites than in sandstones is due to the greater reactivity of dolomite over sandstone. The results of this study which includes the formulation of a reactive transport model and estimation of partition coefficients of Ba in dolomites and sandstones have significant implications in understanding and predicting the mobility and transport of Ba in deep dolomite and sandstone saline aquifers. Copyright © 2018 Elsevier B.V. All rights reserved.

The current status of mapping karst areas and availability of public sinkhole-risk resources in karst terrains of the United States

USGS Publications Warehouse

Kuniansky, Eve L.; Weary, David J.; Kaufmann, James E.

2016-01-01

Subsidence from sinkhole collapse is a common occurrence in areas underlain by water-soluble rocks such as carbonate and evaporite rocks, typical of karst terrain. Almost all 50 States within the United States (excluding Delaware and Rhode Island) have karst areas, with sinkhole damage highest in Florida, Texas, Alabama, Missouri, Kentucky, Tennessee, and Pennsylvania. A conservative estimate of losses to all types of ground subsidence was $125 million per year in 1997. This estimate may now be low, as review of cost reports from the last 15 years indicates that the cost of karst collapses in the United States averages more than $300 million per year. Knowing when a catastrophic event will occur is not possible; however, understanding where such occurrences are likely is possible. The US Geological Survey has developed and maintains national-scale maps of karst areas and areas prone to sinkhole formation. Several States provide additional resources for their citizens; Alabama, Colorado, Florida, Indiana, Iowa, Kentucky, Minnesota, Missouri, Ohio, and Pennsylvania maintain databases of sinkholes or karst features, with Florida, Kentucky, Missouri, and Ohio providing sinkhole reporting mechanisms for the public.

The current status of mapping karst areas and availability of public sinkhole-risk resources in karst terrains of the United States

NASA Astrophysics Data System (ADS)

Kuniansky, Eve L.; Weary, David J.; Kaufmann, James E.

2016-05-01

Subsidence from sinkhole collapse is a common occurrence in areas underlain by water-soluble rocks such as carbonate and evaporite rocks, typical of karst terrain. Almost all 50 States within the United States (excluding Delaware and Rhode Island) have karst areas, with sinkhole damage highest in Florida, Texas, Alabama, Missouri, Kentucky, Tennessee, and Pennsylvania. A conservative estimate of losses to all types of ground subsidence was 125 million per year in 1997. This estimate may now be low, as review of cost reports from the last 15 years indicates that the cost of karst collapses in the United States averages more than 300 million per year. Knowing when a catastrophic event will occur is not possible; however, understanding where such occurrences are likely is possible. The US Geological Survey has developed and maintains national-scale maps of karst areas and areas prone to sinkhole formation. Several States provide additional resources for their citizens; Alabama, Colorado, Florida, Indiana, Iowa, Kentucky, Minnesota, Missouri, Ohio, and Pennsylvania maintain databases of sinkholes or karst features, with Florida, Kentucky, Missouri, and Ohio providing sinkhole reporting mechanisms for the public.

Karst mapping in the United States: Past, present and future

USGS Publications Warehouse

Weary, David J.; Doctor, Daniel H.

2015-01-01

The earliest known comprehensive karst map of the entire USA was published by Stringfield and LeGrand (1969), based on compilations of William E. Davies of the U.S. Geological Survey (USGS). Various versions of essentially the same map have been published since. The USGS recently published new digital maps and databases depicting the extent of known karst, potential karst, and pseudokarst areas of the United States of America including Puerto Rico and the U.S. Virgin Islands (Weary and Doctor, 2014). These maps are based primarily on the extent of potentially karstic soluble rock types, and rocks with physical properties conducive to the formation of pseudokarst features. These data were compiled and refined from multiple sources at various spatial resolutions, mostly as digital data supplied by state geological surveys. The database includes polygons delineating areas with potential for karst and that are tagged with attributes intended to facilitate classification of karst regions. Approximately 18% of the surface of the fifty United States is underlain by significantly soluble bedrock. In the eastern United States the extent of outcrop of soluble rocks provides a good first-approximation of the distribution of karst and potential karst areas. In the arid western states, the extent of soluble rock outcrop tends to overestimate the extent of regions that might be considered as karst under current climatic conditions, but the new dataset encompasses those regions nonetheless. This database will be revised as needed, and the present map will be updated as new information is incorporated.

Review: Characterization, evolution, and environmental issues of karst water systems in Northern China

NASA Astrophysics Data System (ADS)

Liang, Yongping; Gao, Xubo; Zhao, Chunhong; Tang, Chunlei; Shen, Haoyong; Wang, Zhiheng; Wang, Yanxin

2018-05-01

In Northern China, karst systems in widely distributed carbonate rocks are one of the most important water supplies for local inhabitants. Constrained by the specific geological and geomorphological conditions, most karst water in this region is discharged as individual or groups of springs. This paper summarizes the characteristics, chemistry, and environmental quality of these karst systems in Northern China. Five structural models of karst water systems were identified based on the relationships between the karst geological strata and karst groundwater flow fields. These specific structural models may closely relate to the attendant environmental geological issues and consistent risks from pollution. Over the past 40 years, the karst water systems in Northern China have suffered from various environmental problems, including deteriorating water quality, the drying up of springs, a continuous decline in the level of karst water, and so on. Based on the field investigation and previous data, a preliminary summary is provided of the environmental problems related to the development and evolutionary trends of karst water in this region. The results highlight the significant challenges associated with karst water, and it is essential that all segments of society be made aware of the situation in order to demand change. In addition, the study provides a scientific basis for the management, protection, and sustainable utilization of karst water resources.

Ab Initio Study of the Structure and Stability of High-Pressure Iron-Bearing Dolomite

NASA Astrophysics Data System (ADS)

Solomatova, N. V.; Asimow, P. D.

2016-12-01

Carbon is subducted into the mantle primarily in the form of metasomatically calcium-enriched basaltic rock, calcified serpentinites and carbonaceous ooze, all of which often contain dolomite. End-member CaMg(CO3)2 dolomite typically breaks down upon compression into two carbonates at 5-6 GPa in the temperature range of 800-1200 K [1]. However, high-pressure X-ray diffraction experiments have recently shown that the presence of iron may be sufficient to stabilize high-pressure dolomite over single-cation carbonates above 35 GPa [2,3]. The structure and equation of state of high-pressure dolomite phases have been debated, creating a need for theoretical calculations. Using density functional theory interfaced with a genetic algorithm that predicts crystal structures (USPEX), we have found a monoclinic phase with space group C2/c. The C2/c structure has a lower energy than previously reported dolomite structures at relevant pressures. It is possible that this phase is not achieved experimentally due to a large energy barrier and a correspondingly large required volume drop, resulting in the transformation to metastable dolomite II. We calculate the equation of state of trigonal dolomite, dolomite III and monoclinic C2/c dolomite to 80 GPa with 0 and 50 mol% CaFe(CO3)2 and compare their enthalpies to single-carbonate assemblages. Although end-member C2/c CaMg(CO3)2 dolomite is not stable relative to single-cation carbonates, C2/c CaMg0.5Fe0.5(CO3)2 is preferred over single-cation carbonates at high pressures. Thus, iron-bearing C2/c dolomite may be an important host phase for carbon in slabs subducted into the lower mantle. [1] Shirasaka, M., et al. (2002) American Mineralogist, 87, 922-930. [2] Mao, Z. et al. (2011) Geophysical Research Letters, 38. [3] Merlini, M. et al. (2012) Proceedings of the National Academy of Sciences, 109, 13509-13514.

New Electrical Resistivity Tomography approach for karst cave characterization: Castello di Lepre karst cave (Marsico Nuovo, Southern Italy).

NASA Astrophysics Data System (ADS)

Guerriero, Merilisa; Capozzoli, Luigi; De Martino, Gregory; Perciante, Felice; Gueguen, Erwan; Rizzo, Enzo

2017-04-01

Geophysical methods are commonly applied to characterize karst cave. Several geophysical method are used such as electrical resistivity tomography (ERT), gravimetric prospecting (G), ground penetrating radar (GPR) and seismic methods (S), in order to provide information on cave geometry and subsurface geological structure. In detail, in some complex karst systems, each geophysical method can only give partial information if used in normal way due to a low resolution for deep target. In order to reduce uncertainty and avoid misinterpretations based on a normal use of the electrical resistivity tomography method, a new ERT approach has been applied in karst cave Castello di Lepre (Marsico Nuovo, Basilicata region, Italy) located in the Mezo-Cenozoic carbonate substratum of the Monti della Maddalena ridge (Southern Appenines). In detail, a cross-ERT acquisition system was applied in order to improve the resolution on the electrical resistivity distribution on the surrounding geological structure of a karst cave. The cross-ERT system provides a more uniform model resolution vertically, increasing the resolution of the surface resistivity imaging. The usual cross-ERT is made by electrode setting in two or more borehole in order to acquire the resistivity data distribution. In this work the cross-ERT was made between the electrodes located on surface and along a karst cave, in order to obtain an high resolution of the electrical resistivity distributed between the cave and the surface topography. Finally, the acquired cross-ERT is potentially well-suited for imaging fracture zones since electrical current flow in fractured rock is primarily electrolytic via the secondary porosity associated with the fractures.

Long distance seawater intrusion through a karst conduit network in the Woodville Karst Plain, Florida

NASA Astrophysics Data System (ADS)

Xu, Zexuan; Bassett, Seth Willis; Hu, Bill; Dyer, Scott Barrett

2016-08-01

Five periods of increased electrical conductivity have been found in the karst conduits supplying one of the largest first magnitude springs in Florida with water. Numerous well-developed conduit networks are distributed in the Woodville Karst Plain (WKP), Florida and connected to the Gulf of Mexico. A composite analysis of precipitation and electrical conductivity data provides strong evidence that the increases in conductivity are directly tied to seawater intrusion moving inland and traveling 11 miles against the prevailing regional hydraulic gradient from from Spring Creek Spring Complex (SCSC), a group of submarine springs at the Gulf Coast. A geochemical analysis of samples from the spring vent rules out anthropogenic contamination and upwelling regional recharge from the deep aquifer as sources of the rising conductivity. The interpretation is supported by the conceptual model established by prior researchers working to characterize the study area. This paper documents the first and longest case of seawater intrusion in the WKP, and also indicates significant possibility of seawater contamination through subsurface conduit networks in a coastal karst aquifer.

Long distance seawater intrusion through a karst conduit network in the Woodville Karst Plain, Florida.

PubMed

Xu, Zexuan; Bassett, Seth Willis; Hu, Bill; Dyer, Scott Barrett

2016-08-25

Five periods of increased electrical conductivity have been found in the karst conduits supplying one of the largest first magnitude springs in Florida with water. Numerous well-developed conduit networks are distributed in the Woodville Karst Plain (WKP), Florida and connected to the Gulf of Mexico. A composite analysis of precipitation and electrical conductivity data provides strong evidence that the increases in conductivity are directly tied to seawater intrusion moving inland and traveling 11 miles against the prevailing regional hydraulic gradient from from Spring Creek Spring Complex (SCSC), a group of submarine springs at the Gulf Coast. A geochemical analysis of samples from the spring vent rules out anthropogenic contamination and upwelling regional recharge from the deep aquifer as sources of the rising conductivity. The interpretation is supported by the conceptual model established by prior researchers working to characterize the study area. This paper documents the first and longest case of seawater intrusion in the WKP, and also indicates significant possibility of seawater contamination through subsurface conduit networks in a coastal karst aquifer.

Long distance seawater intrusion through a karst conduit network in the Woodville Karst Plain, Florida

PubMed Central

Xu, Zexuan; Bassett, Seth Willis; Hu, Bill; Dyer, Scott Barrett

2016-01-01

Five periods of increased electrical conductivity have been found in the karst conduits supplying one of the largest first magnitude springs in Florida with water. Numerous well-developed conduit networks are distributed in the Woodville Karst Plain (WKP), Florida and connected to the Gulf of Mexico. A composite analysis of precipitation and electrical conductivity data provides strong evidence that the increases in conductivity are directly tied to seawater intrusion moving inland and traveling 11 miles against the prevailing regional hydraulic gradient from from Spring Creek Spring Complex (SCSC), a group of submarine springs at the Gulf Coast. A geochemical analysis of samples from the spring vent rules out anthropogenic contamination and upwelling regional recharge from the deep aquifer as sources of the rising conductivity. The interpretation is supported by the conceptual model established by prior researchers working to characterize the study area. This paper documents the first and longest case of seawater intrusion in the WKP, and also indicates significant possibility of seawater contamination through subsurface conduit networks in a coastal karst aquifer. PMID:27557803

Treating tar sands formations with karsted zones

DOEpatents

Vinegar, Harold J.; Karanikas, John Michael

2010-03-09

Methods for treating a tar sands formation are described herein. The tar sands formation may have one or more karsted zones. Methods may include providing heat from one or more heaters to one or more karsted zones of the tar sands formation to mobilize fluids in the formation. At least some of the mobilized fluids may be produced from the formation.

Extraction of magnesium from calcined dolomite ore using hydrochloric acid leaching

NASA Astrophysics Data System (ADS)

Royani, Ahmad; Sulistiyono, Eko; Prasetiyo, Agus Budi; Subagja, Rudi

2018-05-01

Magnesium is widely used in varieties industrial sector. Dolomite is one source of magnesium besides seawater. The extraction of magnesium from dolomite ores can be done by leaching process. In this work, the dolomite leaching to extract magnesium by hydrochloric acid was investigated. The leaching experiments were performed in a spherical glass batch reactor having a capacity of 1000 ml. The effects of the stirring speed, acid concentration, reaction temperature and liquid-solid ratio for each reaction time of 1; 2; and 3 h on the Mg leaching have been evaluated. 5 ml of solution sample were collected from the leached solutions, then it was filtered prior to analysis by ICP OES. The experimental results show that the magnesium extraction increases along with the increase of acid concentration, liquid-solid ratio and temperature. The optimum conditions for magnesium extraction were achieved at temperature 75 °C, extraction time 3 h, the HCl concentration of 2 M, the liquid-solid ratio 20 ml/g and stirring speed of 400 rpm. At this condition 98, 82 % of magnesium were extracted from dolomite. The conclusion obtained from this leaching process is that the magnesium can be extracted from dolomite by using hydrochloric acid solutions.

Anoxic deep-sea microbial dolomite as a paleoceanographic archive - new insights from old "bugs"

NASA Astrophysics Data System (ADS)

Miller, N. R.; Leybourne, M. I.

2010-12-01

Earth’s history of biogenic carbonate production is dominated by pre-skeletal (late Ediacaran) microbe-catalyzed carbonate, including low T/P microbial (aka organogenic) dolomite, but paleoceanographic contexts are unclear due to the lack of proxy control provided by skeletal analogs and/or diagenesis. Microbial communities affiliated with dolomite generation (chiefly sulfate reducers and methanogens) are now known to persist in a diversity of Recent anoxic environments, but only deep-sea settings are sufficiently insulated from eustatic-meteoric diagenesis to preserve long-term records of possible paleoceanographic significance. The Miocene Monterey Formation contains episodic-to-cyclic microbial dolomite intervals interstratified with microfossil calcite, and thereby offers an excellent test the paleoceoanographic archive potential of microbial dolomite. Accordingly, we established a detailed dolomite chemostratigraphic profile (δ18O, δ13C, TOC, trace elements/REEs) from a continuous, thermally immature, Monterey core (offshore Santa Barbara-Ventura Basin), preserving >100 distinct early diagenetic (pre significant compaction, pre-diatom dissolution, post-pyrite) microbial dolomite intervals. Despite dolomite horizons being physically separate from one stratum to the next, they exhibit regular core-wide variations in δ13C and δ18O. Dolomite within the main Monterey depositional interval has entirely negative δ13C values (-2 to -16‰) consistent with generation in the zone of microbial sulfate reduction, whereas positive δ13C values (+2 to +9‰) consistent with generation from methanogenic pore-waters occur in lithologic transitions with bounding formations. Dolomites within the main Monterey depositional interval mirror microfossil calcite δ18O variations, notably pronounced global mid-Miocene enrichment after ~14 Ma linked to cooling and significant expansion of Antarctic ice. Dolomite δ13C mirrors sediment accumulation rate, with lightest values

Mechanical changes caused by CO2-driven cement dissolution in the Morrow B Sandstone at reservoir conditions: Experimental observations

NASA Astrophysics Data System (ADS)

Wu, Z.; Luhmann, A. J.; Rinehart, A. J.; Mozley, P.; Dewers, T. A.

2017-12-01

Carbon Capture, Utilization and Storage (CCUS) in transmissive reservoirs is a proposed mechanism in reducing CO2 emissions. Injection of CO2 perturbs reservoir chemistry, and can modify porosity and permeability and alter mineralogy. However, little work has been done on the coupling of rock alteration by CO2 injection and the mechanical integrity of the reservoir. In this study, we perform flow-through experiments on calcite- and dolomite-cemented Pennsylvanian Morrow B Sandstone (West Texas, USA) cores. We hypothesize that poikilotopic calcite cement has a larger impact on chemo-mechanical alteration than disseminated dolomite cement given similar CO2 exposure. With one control brine flow-through experiment and two CO2-plus-brine flow-through experiments for each cement composition, flow rates of 0.1 and 0.01 ml/min were applied under 4200 psi pore fluid pressure and 5000 psi confining pressure at 71 °C. Fluid chemistry and permeability data enable monitoring of mineral dissolution. Ultrasonic velocities were measured pre-test using 1.2 MHz source-receiver pairs at 0.5 MPa axial load and show calcite-cemented samples with higher dynamic elastic moduli than dolomite-cemented samples. Velocities measured post-experiment will identify changes from fluid-rock interaction. We plan to conduct cylinder-splitting destructive mechanical test (Brazil test) to measure the pristine and altered tensile strength of different cemented sandstones. The experiments will identify extents to which cement composition and texture control chemo-mechanical degradation of CCUS reservoirs. Funding for this project is provided by the U.S. Department of Energy's (DOE) National Energy Technology Laboratory (NETL) through the Southwest Regional Partnership on Carbon Sequestration (SWP) under Award No. DE-FC26-05NT42591. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia LLC, a wholly owned subsidiary of

Study on Karst Information Identification of Qiandongnan Prefecture Based on RS and GIS Technology

NASA Astrophysics Data System (ADS)

Yao, M.; Zhou, G.; Wang, W.; Wu, Z.; Huang, Y.; Huang, X.

2018-04-01

Karst area is a pure natural resource base, at the same time, due to the special geological environment; there are droughts and floods alternating with frequent karst collapse, rocky desertification and other resource and environment problems, which seriously restrict the sustainable economic and social development in karst areas. Therefore, this paper identifies and studies the karst, and clarifies the distribution of karst. Provide basic data for the rational development of resources in the karst region and the governance of desertification. Due to the uniqueness of the karst landscape, it can't be directly recognized and extracted by computer in remote sensing images. Therefore, this paper uses the idea of "RS + DEM" to solve the above problems. this article is based on Landsat-5 TM imagery in 2010 and DEM data, proposes the methods to identify karst information research what is use of slope vector diagram, vegetation distribution map, distribution map of karst rocky desertification and other auxiliary data in combination with the signs for human-computer interaction interpretation, identification and extraction of peak forest, peaks cluster and isolated peaks, and further extraction of karst depression. Experiments show that this method achieves the "RS + DEM" mode through the reasonable combination of remote sensing images and DEM data. It not only effectively extracts karst areas covered with vegetation, but also quickly and accurately locks down the karst area and greatly improves the efficiency and precision of visual interpretation. The accurate interpretation rate of karst information in study area in this paper is 86.73 %.

Interregional comparison of karst disturbance: west-central Florida and southeast Italy.

PubMed

North, Leslie A; van Beynen, Philip E; Parise, Mario

2009-04-01

The karst disturbance index (KDI) consists of 31 environmental indicators contained within the five broad categories: geomorphology, hydrology, atmosphere, biota, and cultural. The purpose of this research is to apply the KDI to two distinct karst areas, west Florida, USA, and Apulia, Italy. Through its application, the utility of the index can be validated and other important comparisons can be made, such as differences in the karst legislations implemented in each region and the effect of time exposure to human occupation to each karst terrain. Humans have intensively impacted the karst of southeast Italy for thousands of years compared to only decades in west-central Florida. However, west-central Florida's higher population density allows the region to reach disturbance levels comparable to those reached over a longer period in Apulia. Similarly, Italian karst is more diverse than the karst found in west-central Florida, creating an opportunity to test all the KDI indicators. Overall, major disturbances for southeast Italy karst include quarrying, stone clearing, and the dumping of refuse into caves, while west-central Florida suffers most from the infilling of sinkholes, soil compaction, changes in the water table, and vegetation removal. The application of the KDI allows a benchmark of disturbance to be established and later revisited to determine the changing state of human impact for a region. The highlighting of certain indicators that recorded high levels of disturbance also allows regional planners to allocate resources in a more refined manner.

New insights to the formation of modern dolomite in a terrestrial low-temperature environment

NASA Astrophysics Data System (ADS)

Zünterl, Andrea; Baldermann, Andre; Boch, Ronny; Dietzel, Martin

2017-04-01

Although dolomite [CaMg(CO3)2] is a rock-forming mineral in ancient carbonate platforms, its occurrence in modern-marine carbonate-depositing settings and in particular in terrestrial, low-temperature environments is scarce - an enigma that is referred to as the "dolomite problem". At present, it is generally accepted that microbial activity, bacterially-mediated sulfate reduction, high aqueous Mg/Ca ratios and anoxic conditions favour the nucleation and crystal growth of dolomite; albeit the precise reaction paths causing the formation of dolomite at low temperatures remain questionable. Here, we present a novel study about the environmental controls and reaction mechanisms leading to the formation of authigenic Mg-Ca carbonates in (active) fault zones of the Erzberg (Styria, Austria) - Europe's largest iron ore opencast mine. Our petrographic and mineralogical results revealed the presence of ˜2-20 cm thick laminated successions of embedded needle-shaped, radiating aragonite and blocky low-Mg calcite (a repetitive sequence also-called "erzbergite") and subsequently deposited (Ca-rich) non-stoichiometric dolomite, which is clogging former voids and unconsolidated sediment in the heavily deteriorated fault zone. First U-Th age determinations of the respective aragonite layers indicate its formation at ˜19,000-13,000 years BP, also suggesting a "young" age of the sedimentary dolomite. Based on the combination of X-ray diffraction and electron microprobe analyses we identified two types of matrix-replacing dolomite: type 1 dolomite is nearly stoichiometric (˜51 mol% CaCO3) and shows a high degree of cation ordering (0.4-0.6), whereas type 2 dolomite is characterized by Ca-excess (˜55 mol% CaCO3) and a low degree of ordering (<0.3). Both types of dolomite grow on the extent of matrix minerals, such as detrital low-Mg calcite, ankerite, siderite, quartz, goethite, chlorite and illitic clay minerals, implying a low-temperature origin of the Ca-excess dolomite and

Retrieving hydrological connectivity from empirical causality in karst systems

NASA Astrophysics Data System (ADS)

Delforge, Damien; Vanclooster, Marnik; Van Camp, Michel; Poulain, Amaël; Watlet, Arnaud; Hallet, Vincent; Kaufmann, Olivier; Francis, Olivier

2017-04-01

Because of their complexity, karst systems exhibit nonlinear dynamics. Moreover, if one attempts to model a karst, the hidden behavior complicates the choice of the most suitable model. Therefore, both intense investigation methods and nonlinear data analysis are needed to reveal the underlying hydrological connectivity as a prior for a consistent physically based modelling approach. Convergent Cross Mapping (CCM), a recent method, promises to identify causal relationships between time series belonging to the same dynamical systems. The method is based on phase space reconstruction and is suitable for nonlinear dynamics. As an empirical causation detection method, it could be used to highlight the hidden complexity of a karst system by revealing its inner hydrological and dynamical connectivity. Hence, if one can link causal relationships to physical processes, the method should show great potential to support physically based model structure selection. We present the results of numerical experiments using karst model blocks combined in different structures to generate time series from actual rainfall series. CCM is applied between the time series to investigate if the empirical causation detection is consistent with the hydrological connectivity suggested by the karst model.

Karst topography : noninvasive geophysical detection methods and construction techniques.

DOT National Transportation Integrated Search

2013-10-01

The objective of this project was to investigate the current state of the practice with regards to karst detection : methods and current karst construction practices and to recommend the best practices for use by the Virginia : Department of Transpor...

Effects of temperature, pressure, and carrier gas on the cracking of coal tar over a char-dolomite mixtures and calcined dolomite in a fixed-bed reactor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seshadri, K.; Shamsi, A.

1998-10-01

A distillation fraction of a coal-derived liquid (tar) was cracked over a char-dolomite mixture, calcined dolomite, and silicon carbide in a fixed-bed reactor. The char-dolomite mixture (FWC) was produced from Pittsburgh No. 8 coal and dolomite in a Foster Wheeler carbonizer. The experiments were conducted under nitrogen and simulated coal gas (SCG), which was a mixture of CO, CO{sub 2}, H{sub 2}S, CH{sub 4}, N{sub 2}, and steam, at 1 and 17 atm. The conversion over these materials under nitrogen was much higher at 17 atm than at 1 atm. At higher pressures, tar molecules were trapped in the poresmore » of the bed material and underwent secondary reactions, resulting in the formation of excess char. However, when nitrogen was replaced by SCG, the reactions that induce char formation were suppressed, thus increasing the yield of gaseous products. The analysis of the gaseous products and the spent bed materials for organic and inorganic carbons suggested that the product distribution can be altered by changing the carrier gas, temperature, and pressure.« less

Mud cracks and dedolomitization in the Wittenoom Dolomite, Hamersley Group, Western Australia

USGS Publications Warehouse

Kargel, J.S.; Schreiber, J.F.; Sonett, C.P.

1996-01-01

Several impure dolomitic limestone beds in an outcrop of the latest Archean Wittenoom Dolomite (Hamersley Group, Western Australia) are polygonally cracked. The cracks appear to be sub-aerial desiccation features, suggesting that the known area of shallow water and locally emergent conditions extended from the far eastern part of the basin (the Carawine Dolomite) over 270 km farther west. This finding places shallow- water or emergent conditions either (1) near the middle of what Trendall (1983) defined as the probable original limits of the Hamersley Basin (Trendall's 'Pilbara Egg') or (2) near the southern edge of what Morris (1993) thought to be a broad carbonate platform which fed a deeper water sequence to the south. In any case, the Hamersley Basin in the area of Bee Gorge and eastward to the Carawine Dolomite may have been a carbonate mudflat in part with restricted circulation of sea water. The Carawine Dolomite and the Wittenoom Dolomite near Bee Gorge may have been affected by carbonate buildups along a shelf edge. Regardless of whether shallow water was widespread or local in the Hamersley basin, shallow water verging on emergence is supported by evidence of diagenetic dedolomitization under conditions of low atmospheric and hydrospheric P(O2) and precipitation of strontianite in the mud-cracked sample. Evidence of shallow water at Bee Gorge is consistent with Trendall's broad evaporite-basin model and with Morris' barred-platform model for the origin of Hamersley carbonates and banded iron-formations.

Contaminant transport in two central Missouri karst recharge areas

USDA-ARS?s Scientific Manuscript database

Karst watersheds with significant losing streams represent a particularly vulnerable setting for ground water contamination because of the direct connection to surface water. Because of the existing agricultural land-use and future threat of heavy urbanization, two losing stream karst basins were ch...

Contaminant transport in two central Missouri karst recharge areas

USDA-ARS?s Scientific Manuscript database

Karst watersheds with significant losing streams represent a particularly vulnerable setting for ground water contamination because of the direct connection to surface water. Because of the existing agricultural land-use and future likelihood of urbanization, two losing stream karst basins were chos...

Contaminant Transport in Two Central Missouri Karst Recharge Areas

USDA-ARS?s Scientific Manuscript database

Karst watersheds with significant losing streams represent a particularly vulnerable setting for ground water contamination because of the direct connection to surface water. Because of the existing agricultural land-use and future threat of heavy urbanization, two losing stream karst basins were ch...

Extending GIS Technology to Study Karst Features of Southeastern Minnesota

NASA Astrophysics Data System (ADS)

Gao, Y.; Tipping, R. G.; Alexander, E. C.; Alexander, S. C.

2001-12-01

This paper summarizes ongoing research on karst feature distribution of southeastern Minnesota. The main goals of this interdisciplinary research are: 1) to look for large-scale patterns in the rate and distribution of sinkhole development; 2) to conduct statistical tests of hypotheses about the formation of sinkholes; 3) to create management tools for land-use managers and planners; and 4) to deliver geomorphic and hydrogeologic criteria for making scientifically valid land-use policies and ethical decisions in karst areas of southeastern Minnesota. Existing county and sub-county karst feature datasets of southeastern Minnesota have been assembled into a large GIS-based database capable of analyzing the entire data set. The central database management system (DBMS) is a relational GIS-based system interacting with three modules: GIS, statistical and hydrogeologic modules. ArcInfo and ArcView were used to generate a series of 2D and 3D maps depicting karst feature distributions in southeastern Minnesota. IRIS ExplorerTM was used to produce satisfying 3D maps and animations using data exported from GIS-based database. Nearest-neighbor analysis has been used to test sinkhole distributions in different topographic and geologic settings. All current nearest-neighbor analyses testify that sinkholes in southeastern Minnesota are not evenly distributed in this area (i.e., they tend to be clustered). More detailed statistical methods such as cluster analysis, histograms, probability estimation, correlation and regression have been used to study the spatial distributions of some mapped karst features of southeastern Minnesota. A sinkhole probability map for Goodhue County has been constructed based on sinkhole distribution, bedrock geology, depth to bedrock, GIS buffer analysis and nearest-neighbor analysis. A series of karst features for Winona County including sinkholes, springs, seeps, stream sinks and outcrop has been mapped and entered into the Karst Feature Database

Dissolution profile of dolomite in chloric acid solution: The effect of chloric acid concentration and pulp density

NASA Astrophysics Data System (ADS)

Solihin, Indriani, Mubarok, M. Zaki

2018-05-01

Dolomite is one of carbonate minerals that contain magnesium. Magnesium is important element used in many aspects of life such as cofactor of many enzymes in human body, nutrient for plants, and raw material in automotive industry. Dolomite can be processed through low temperature process to obtain magnesium and calcium oxide that is needed in important applications such as base material for making drugs, raw material in the synthesize slow release fertilizer, materials for fire retardant, component for catalyst, etc. One of the important step of this low temperature process is dissolution of dolomite. Optimizing the dissolution process determines the % extraction of magnesium and calcium oxide from dolomite. The dissolution of dolomite from Gresik, East Java Provence Indonesia, in chloric acid solution has been conducted. Chloric acid concentration and pulp density are the variables that were observed. The dissolution of magnesium and calcium from Gresik dolomite was found to be very fast. The stable stage of dissolution can be reached for 5-10 seconds. The % extraction is mainly determined by the molar ratio of chloric acid / dolomite. At molar ratio of chloric acid / dolomite equal or above stoichiometric of dolomite dissolution, % extraction of magnesium is almost 100 %.

Dolomite Formation within Microbial Mats in the Sabkha of Abu Dhabi (UAE) and Associated Microsedimentary Structures

NASA Astrophysics Data System (ADS)

Bontognali, T. R.; Vasconcelos, C.; McKenzie, J. A.

2008-12-01

The link between microbial activity and dolomite formation has been evaluated in the coastal sabkha of Abu Dhabi (UAE). This modern dolomite-forming environment is frequently cited as the type analogue for the interpretation of many ancient evaporitic sequences. The investigation of sabkha sediments along a transect from intertidal to supratidal zones revealed a close association between microbial mats and dolomite. Authigenic dolomite occurs within surface and buried microbial mats, which are comprised of exopolymeric substances (EPS). Dolomite forms as a direct consequence of mineral nucleation and growth within microbially produced EPS. The cation-binding effect of the EPS molecules influences the composition of the precipitate. The early stage of this process is characterized by the complexation of an amorphous Mg-Si precipitate, which promotes dolomite development. Mineral formation within EPS appears to be enhanced by evaporation with consequent supersaturation of the pore waters with respect to dolomite. Partial EPS degradation during diagenesis may also provide an additional source of cations. However, the specific mineral-template property of EPS, rather than an increase in cation concentrations, is the key factor for dolomite formation in the studied area of the sabkha. Indeed, within the modern microbial mat located at the surface, dolomite precipitates from pore waters whose composition is very close to seawater. In the supratidal zone, pore water analysis and stable isotope values did not reveal any linkage between dolomite formation and microbial excretion and/or consumption of metabolites along the sediment profiles. This is in contrast with current models, in which dolomite formation is mainly linked to microbial increase of pH and alkalinity or consumption of dissolved SO4 in pore-waters. The EPS of the microbial mats is characterized by an alveolar microfabric, which can be mineralized during early diagenesis, preserving fossil imprints of the

Biodegradation of chlorinated ethenes at a karst site in middle Tennessee

USGS Publications Warehouse

Byl, Thomas Duane; Williams, Shannon D.

2000-01-01

This report presents results of field and laboratory investigations examining the biodegradation of chlorinated ethenes in a karst aquifer contaminated with trichloroethylene (TCE). The study site, located in Middle Tennessee, was selected because of the presence of TCE degradation byproducts in the karst aquifer and available site hydrologic and chlorinated-ethene information. Additional chemical, biological, and hydrologic data were gathered to evaluate whether the occurrence of TCE degradation byproducts in the karst aquifer was the result of biodegradation within the aquifer or simply transport into the aquifer. Geochemical analysis established that sulfate-reducing conditions, essential for reductive dechlorination of chlorinated solvents, existed in parts of the contaminated karst aquifer. Other areas of the aquifer fluctuated between anaerobic and aerobic conditions and contained compounds associated with cometabolism, such as ethane, methane, ammonia, and dissolved oxygen. A large, diverse bacteria population inhabits the contaminated aquifer. Bacteria known to biodegrade TCE and other chlorinated solvents, such as sulfate-reducers, methanotrophs, and ammonia-oxidizers, were identified from karst-aquifer water using the RNA-hybridization technique. Results from microcosms using raw karst-aquifer water found that aerobic cometabolism and anaerobic reductive-dechlorination degradation processes were possible when appropriate conditions were established in the microcosms. These chemical and biological results provide circumstantial evidence that several biodegradation processes are active in the aquifer. Additional site hydrologic information was developed to determine if appropriate conditions persist long enough in the karst aquifer for these biodegradation processes to be significant. Continuous monitoring devices placed in four wells during the spring of 1998 indicated that pH, specific conductance, dissolved oxygen, and oxidation-reduction potentials

Impact of diagenesis and low grade metamorphosis on Triassic sabkha dolomite δ26Mg

NASA Astrophysics Data System (ADS)

Immenhauser, A.; Geske, A.; Richter, D.; Buhl, D.; Niedermayr, A.

2012-12-01

Dolomite is a common rock forming mineral in the geological record but its value as archive of ancient seawater δ26Mg signatures and their variations in time are at present underexplored. Unknown factors include the sensitivity of δ26Mg ratio to processes in the diagenetic and low grade metamorphic domain. Here, we document and discusses the first detailed δ26Mg data set from early diagenetic and burial dolomites. Samples come from the Upper Triassic Hauptdolomit (Dolomia Principale; The Dolomites, Italy) and include coeval dolmicrites that underwent differential burial diagenesis in a temperature range between about 100 and more than 350°C. As indicated by dolmicrite 87/86Sr ratios, sabkha calcian D1 dolomites precipitated from evaporated seawater and stabilized at an early diagenetic stage to D2 dolomites analysed here. With increasing burial temperature, dolomite δ26Mg ratio scatter in the data set decreases with increasing Mg/Ca ratio and degree of order. Specifically, δ26Mg ratio variability is reduced from ~0.7‰ at burial temperatures beneath 100°C to about ~0.2‰ at temperatures in excess of 350°C, respectively, with mean δ26Mg values ranging constantly near -1.9‰. This suggests that, at least for the rock buffered system investigated here, dolmicrite δ26Mg proxy data are conservative and preserve near pristine values even at elevated burial temperatures. At present, the main element of uncertainty is the Mg-isotope fractionation factor between (evaporated) seawater and dolomite. A possible solution to this problem includes the compilation of a data from modern sabkha environments including pore water and calcian dolomite δ26Mg isotope signatures.

Removal of low-concentration phosphorus using a fluidized raw dolomite bed.

PubMed

Ayoub, George M; Kalinian, Houri

2006-04-01

Raw dolomite powder, obtained from dolomitic rocks, was evaluated for its efficiency in removing low concentrations of phosphate present in various water and wastewater matrices. A variety of experimental setups and process variables were tested, in an attempt to determine the optimal scheme (fluidized bed) that will be used to accomplish the objectives of the study. Test influents, including distilled water (DW), synthetic groundwater (SGW), tap water (TW), and sodium-hydroxide (NaOH)-alkalized wastewater treated with liquid bittern (STSE-B) and wastewater treated with lime (STSE-L) were used to assess the effect of influent parameters on the quality of the effluent generated. The adsorptive behavior of dolomite was described by fitting data generated from the study into the Freundlich and Langmuir isotherm models. Regeneration of the dolomite was attempted by the use of an acid (hydrochloric acid), DW, and an alkaline (NaOH). Test results indicate remarkable phosphate removal levels for DW and SGW. Removal levels of 100% were attained, for an average of 307 and 314 bed volumes at inflow concentration levels of 0.28 and 0.34 mg phosphate (PO4)/ L, respectively. Relative adsorption capacities were calculated to be 0.06 and 0.072 mg PO4/g of dolomite, respectively. For TW, STSE-L, and STSE-B, 100% removal before the start of the breakthrough was sustained for averages of 205, 94, and 28 bed volumes at phosphate dosages of 0.34, 0.56, and 0.6 mg PO4/L, respectively. The calculated adsorptive capacities were 0.05, 0.051, and 0.025, respectively. Zeta potential measurement resulted in values of -16.0 mV before treatment and +3.0 mV after complete exhaustion of the bed with PO4-jacked SGW influent, indicating an ionic adsorption of ions of opposite charge to that of the particle surface. Although both the Freundlich and Langmuir isotherms were found to fit the sorption curves, the Langmuir seems to better describe the sorption process in dolomite. Among the three

A glossary of Karst terminology

USGS Publications Warehouse

Monroe, Watson Hiner

1970-01-01

This glossary includes most terms used in describing karst geomorphologic features and processes. The terms are primarily those used in the literature of English-speaking countries, but a few of the more common terms in French, German, and Spanish are included, with references to the corresponding English terms where they are available. The glossary also includes simple definitions of the more common rocks and minerals found in karst terrain, common terms of hydrology, and a number of the descriptive terms used by speleologists. The glossary does not include definitions of most biospeleological terms, geologic structure terms, varieties of carbonate rock that require microscopic techniques for identification, or names describing tools and techniques of cave exploration.

Informal Karst Education in the United States and Internationally

ERIC Educational Resources Information Center

North, Leslie A.

2011-01-01

Despite the abundance of karst terrains and the important role they play in a wide variety of roles including supplying freshwater drinking supplies, no single, comprehensive study investigates the role of informal education for the improved understanding and protection of the terrains. Commonly overlooked anthropogenic karst disturbances…

Biolaminoid facies in a peritidal sabkha: Permian Platy Dolomite of northern Poland

NASA Astrophysics Data System (ADS)

Brehm, Ulrike; Gasiewicz, Andreij; Gerdes, Giesela; Krumbein, Wolfgang

The Platy Dolomite, a carbonate unit in the Zechstein Formation (Upper Permian) of the Leba Elevation, Poland, was deposited in a semi-closed or completely separated back-barrier sabkha environment. This arid, hypersaline zone is comparable to the recent Gavish Sabkha, Sinai. The processes which formed the modern Gavish Sabkha are similar to those responsible for the biolaminoid formation in the Platy Dolomite series. The deposition of this Platy Dolomite was mainly the result of microbial activity building extensive microbial mats. The Platy Dolomite is characterized by loosely packed microbial biolaminoids (a less significantly laminated build-up of biogenetic sediments) with horizontally or obliquely to vertically orientated filaments. Intermediary coated grains occur. Densely packed, flat laminated stromatolitic rocks, pure oolites, and bioclastic sedimentary strata are rarely intercalated with the biolaminoid beds. Laboratory and field investigations indicate that carbonate formation was induced by the chemoorganotrophic bacterial decay of cyanobacterial mats. Magnesium was bound and absorbed by organic matter and later liberated by anaerobic decay. Early diagenetic processes formed Mg2+- and Ca2+-enriched solutions in which carbonates precipitated biologically and chemically. A system of biogenic carbonate formation of the Platy Dolomite microbiolite series is proposed and supported by the results of microbiological laboratory studies.

The World Karst Aquifer Mapping project: concept, mapping procedure and map of Europe

NASA Astrophysics Data System (ADS)

Chen, Zhao; Auler, Augusto S.; Bakalowicz, Michel; Drew, David; Griger, Franziska; Hartmann, Jens; Jiang, Guanghui; Moosdorf, Nils; Richts, Andrea; Stevanovic, Zoran; Veni, George; Goldscheider, Nico

2017-05-01

Karst aquifers contribute substantially to freshwater supplies in many regions of the world, but are vulnerable to contamination and difficult to manage because of their unique hydrogeological characteristics. Many karst systems are hydraulically connected over wide areas and require transboundary exploration, protection and management. In order to obtain a better global overview of karst aquifers, to create a basis for sustainable international water-resources management, and to increase the awareness in the public and among decision makers, the World Karst Aquifer Mapping (WOKAM) project was established. The goal is to create a world map and database of karst aquifers, as a further development of earlier maps. This paper presents the basic concepts and the detailed mapping procedure, using France as an example to illustrate the step-by-step workflow, which includes generalization, differentiation of continuous and discontinuous carbonate and evaporite rock areas, and the identification of non-exposed karst aquifers. The map also shows selected caves and karst springs, which are collected in an associated global database. The draft karst aquifer map of Europe shows that 21.6% of the European land surface is characterized by the presence of (continuous or discontinuous) carbonate rocks; about 13.8% of the land surface is carbonate rock outcrop.

Results of a hydrogeological and hydrogeochemical study of a semi-arid karst aquifer in Tezbent plateau, Tebessa region, northeast of Algeria

NASA Astrophysics Data System (ADS)

Belfar, Dalila; Fehdi, Chemseddine; Baali, Fethi; Salameh, Elias

2017-06-01

The Hammamet Plain, situated in the northwest of the Tezbent mountain range, northeast of Algeria, drains carbonate aquifers through some important karst springs. The physical and chemical characteristics of spring and well water samples were studied for 2 years to assess the origin of groundwater and determine the factors driving the geochemical composition. The ionic speciation and mineral dissolution/precipitation was calculated. Water wells, characterizing groundwater circulation at shallow depths, are moderate to high mineralized waters of Na-HCO3 type. In contrast to the shallow environment, the CO2-rich, deeper waters are of the Ca-HCO3-SO4 type and undergo significant changes in the baseline chemistry along flow lines with increasing residence time. The main factors controlling the groundwater composition and its seasonal variations are the geology, because of the presence of carbonate formations, the elevation and the rate of karst development. In both groups, the carbonate chemistry is diagnostic of the effect of karst development. The supersaturation with respect to calcite indicates CO2 degassing, occurring either inside the aquifer in open conduits, or at the outlet in reservoirs. The undersaturation with respect to calcite shows the existence of fast flow and short residence time conditions inside the aquifer. Interaction between groundwater and surrounding host rocks is believed to be the main process responsible for the observed chemical characteristics of groundwater in the study area.

Karst of the Mid-Atlantic region in Maryland, West Virginia, and Virginia

USGS Publications Warehouse

Doctor, Daniel H.; Weary, David J.; Brezinski, David K.; Orndorff, Randall C.; Spangler, Lawrence E.; Brezinski, David K.; Halka, Jeffrey; Ortt, Richard A.

2015-01-01

The Mid-Atlantic region hosts some of the most mature karst landscapes in North America, developed in highly deformed rocks within the Piedmont and Valley and Ridge physiographic provinces. This guide describes a three-day excursion to examine karst development in various carbonate rocks by following Interstate 70 west from Baltimore across the eastern Piedmont, across the Frederick Valley, and into the Great Valley proper. The localities were chosen in order to examine the structural and lithological controls on karst feature development in marble, limestone, and dolostone rocks with an eye toward the implications for ancient landscape evolution, as well as for modern subsidence hazards. A number of caves will be visited, including two commercial caverns that reveal strikingly different histories of speleogenesis. Links between karst landscape development, hydrologic dynamics, and water resource sustainability will also be emphasized through visits to locally important springs. Recent work on quantitative dye tracing, spring water geochemistry, and groundwater modeling reveal the interaction between shallow and deep circulation of groundwater that has given rise to the modern karst landscape. Geologic and karst feature mapping conducted with the benefit of lidar data help reveal the strong bedrock structural controls on karst feature development, and illustrate the utility of geologic maps for assessment of sinkhole susceptibility.

The massive dolomitization of platformal and basinal sequences: proposed models from the Paleocene, Northeast Sirte Basin, Libya

NASA Astrophysics Data System (ADS)

Mresah, Mohamed H.

1998-03-01

The Paleocene carbonate succession in the Northeast Sirte Basin is composed of two shallowing-upward ramp cycles, where each cycle is under- and overlain by deeper-water, pelagic facies. A significant proportion of each of these two cycles is dolomitized. Petrographic study, supported by geochemical data (stoichiometry, stable isotopes, trace elements, and fluid inclusions), and integrated with broader tectono-sedimentary information, has provided the basis for interpreting these Paleocene dolomites. The use of this integrated approach in the study of dolomites suggests that, despite the much publicized uncertainties in interpreting geochemical analyses of ancient dolomites, the results of the Paleocene dolomites show that the geochemical characteristics are generally consistent with regional stratigraphic distribution and petrographic observations. Four distinct types of dolomite have been recognized in this part of the Sirte Basin. Based on the stratigraphic position and petrographic criteria, two of these types have a platformal setting and the other two are basinal. The platform varieties consist of dolomicrites and pervasive stratal dolomites. The dolomicrites, interpreted to be of syn-sedimentary origin, were probably a product of reflux of seawater, with elevated salinity, as suggested by palaeoenvironmental analysis and supported by geochemical evidence (the average S'80 value is -0.1‰ PDB; the average Sr content is 639 ppm). The pervasive dolomites were formed during the progradation of the platform sequences, and probably stabilized and augmented during shallow burial. A meteoric-marine mixing-zone is thought to have been the most likely process for the formation of these dolomites. This interpretation is supported by geochemical evidence (the average δ18O is -2.4‰ PDB; the average Sr content is 72 ppm) combined with a favourable stratigraphic position. The most characteristic feature related to both mixing-zone and reflux dolomitization is the

Modeling a network of turloughs in lowland karst

NASA Astrophysics Data System (ADS)

Gill, L. W.; Naughton, O.; Johnston, P. M.

2013-06-01

In lowland karst areas of Ireland topographic depressions which get intermittently flooded on an annual cycle via groundwater sources are termed turloughs. These are sites of high ecological interest as they have communities and substrate characteristic of wetlands. The flooding in many turlough basins is due to insufficient capacity of the underground karst system to take increased flows following excessive precipitation events, causing the conduit-type network to surcharge. Continuous water level measurements have been taken in five linked turloughs in the lowland karst area of south Galway over a 3 year period. These water level fluctuations, in conjunction with river inputs and precipitation, were then used to elucidate the hydrogeological controls forming the hydraulic system beneath the ground. A model of the karst network has been developed using a pipe network model with the turloughs represented as ponds. The contribution to the karst network from diffuse flow through the epikarst via the matrix and fracture flow has also been modeled using a combination of an infiltration module and network of permeable pipes. The final model was calibrated against two separate hydrological years and in general provided a good simulation for all of the turloughs water levels particularly for the year with one main filling event. The model also accurately picked up the tidal response observed in these turloughs at shallow depths. The model has been used to predict the groundwater discharge to the coast via the main spring which had not heretofore been possible to measure, being below the sea level.

Process-based monitoring and modeling of Karst springs - Linking intrinsic to specific vulnerability.

PubMed

Epting, Jannis; Page, Rebecca M; Auckenthaler, Adrian; Huggenberger, Peter

2018-06-01

The presented work illustrates to what extent field investigations as well as monitoring and modeling approaches are necessary to understand the high discharge dynamics and vulnerability of Karst springs. In complex settings the application of 3D geological models is essential for evaluating the vulnerability of Karst systems. They allow deriving information on catchment characteristics, as the geometry of aquifers and aquitards as well as their displacements along faults. A series of Karst springs in northwestern Switzerland were compared and Karst system dynamics with respect to qualitative and quantitative issues were evaluated. The main objective of the studies was to combine information of catchment characteristics and data from novel monitoring systems (physicochemical and microbiological parameters) to assess the intrinsic vulnerability of Karst springs to microbiological contamination with simulated spring discharges derived from numerical modeling (linear storage models). The numerically derived relation of fast and slow groundwater flow components enabled us to relate different sources of groundwater recharge and to characterize the dynamics of the Karst springs. Our study illustrates that comparably simple model-setups were able to reproduce the overall dynamic intrinsic vulnerability of several Karst systems and that one of the most important processes involved was the temporal variation of groundwater recharge (precipitation, evapotranspiration and snow melt). Furthermore, we make a first attempt on how to link intrinsic to specific vulnerability of Karst springs, which involves activities within the catchment area as human impacts from agriculture and settlements. Likewise, by a more detailed representation of system dynamics the influence of surface water, which is impacted by release events from storm sewers, infiltrating into the Karst system, could be considered. Overall, we demonstrate that our approach can be the basis for a more flexible and

Thermal decomposition of dolomite under CO2: insights from TGA and in situ XRD analysis.

PubMed

Valverde, Jose Manuel; Perejon, Antonio; Medina, Santiago; Perez-Maqueda, Luis A

2015-11-28

Thermal decomposition of dolomite in the presence of CO2 in a calcination environment is investigated by means of in situ X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The in situ XRD results suggest that dolomite decomposes directly at a temperature around 700 °C into MgO and CaO. Immediate carbonation of nascent CaO crystals leads to the formation of calcite as an intermediate product of decomposition. Subsequently, decarbonation of this poorly crystalline calcite occurs when the reaction is thermodynamically favorable and sufficiently fast at a temperature depending on the CO2 partial pressure in the calcination atmosphere. Decarbonation of this dolomitic calcite occurs at a lower temperature than limestone decarbonation due to the relatively low crystallinity of the former. Full decomposition of dolomite leads also to a relatively low crystalline CaO, which exhibits a high reactivity as compared to limestone derived CaO. Under CO2 capture conditions in the Calcium-Looping (CaL) process, MgO grains remain inert yet favor the carbonation reactivity of dolomitic CaO especially in the solid-state diffusion controlled phase. The fundamental mechanism that drives the crystallographic transformation of dolomite in the presence of CO2 is thus responsible for its fast calcination kinetics and the high carbonation reactivity of dolomitic CaO, which makes natural dolomite a potentially advantageous alternative to limestone for CO2 capture in the CaL technology as well as SO2in situ removal in oxy-combustion fluidized bed reactors.

Hydrochemical constraints between the karst Tabular Middle Atlas Causses and the Saïs basin (Morocco): implications of groundwater circulation

NASA Astrophysics Data System (ADS)

Miche, Hélène; Saracco, Ginette; Mayer, Adriano; Qarqori, Khaoula; Rouai, Mohamed; Dekayir, Abdelilah; Chalikakis, Konstantinos; Emblanch, Christophe

2018-02-01

The karst Tabular Middle Atlas Causses reservoir is the main drinking-water supply of Fez-Meknes region (Saïs Basin) in Morocco. Recent analyses showed a decline in associated groundwater chemical quality and increased turbidity. To understand this hydrosystem, four surveys were undertaken during fall and spring, 2009-2011. Hydrogeochemical studies coupled with isotopic analyses (δ18O, δD and 222Rn) showed that the aquifers between the causses (mountains) and the Saïs Basin are of Liassic origin and at the southern extremities are of Triassic origin. Five recharge zones of different altitudes have been defined, including two main mixing zones in the south. Deuterium excess results suggest local recharge, while a plot of δ18O versus δD characterizes a confined aquifer in the eastern sector. 222Rn results reveal areas of rapid exchanges with an upwelling time of less than 2 weeks. A schematic conceptual model is presented to explain the groundwater circulation system and the behavior of this karst system.

Use of stable isotope-labeled Escherichia coli as a tracer in karst aquifers

USDA-ARS?s Scientific Manuscript database

Bacterial contamination of karst aquifers is a large concern across the globe, yet bacterial transport in karst aquifers is not currently well understood. Groundwater tracers typically used in karst systems include fluorescent dyes and latex microspheres. Not only can these tracers can be cost-prohi...

Colonization by aerobic bacteria in karst: Laboratory and in situ experiments

USGS Publications Warehouse

Personne, J.-C.; Poty, F.; Mahler, B.J.; Drogue, C.

2004-01-01

Experiments were carried out to investigate the potential for bacterial colonization of different substrates in karst aquifers and the nature of the colonizing bacteria. Laboratory batch experiments were performed using limestone and PVC as substrates, a natural bacterial isolate and a known laboratory strain (Escherichia coli [E. coli]) as inocula, and karst ground water and a synthetic formula as growth media. In parallel, fragments of limestone and granite were submerged in boreholes penetrating two karst aquifers for more than one year; the boreholes are periodically contaminated by enteric bacteria from waste water. Once a month, rock samples were removed and the colonizing bacteria quantified and identified. The batch experiments demonstrated that the natural isolate and E. coli both readily colonized limestone surfaces using karst ground water as the growth medium. In contrast, bacterial colonization of both the limestone and granite substrates, when submerged in the karst, was less intense. More than 300 bacterial strains were isolated over the period sampled, but no temporal pattern in colonization was seen as far as strain, and colonization by E. coli was notably absent, although strains of Salmonella and Citrobacter were each observed once. Samples suspended in boreholes penetrating highly fractured zones were less densely colonized than those in the borehole penetrating a less fractured zone. The results suggest that contamination of karst aquifers by enteric bacteria is unlikely to be persistent. We hypothesize that this may be a result of the high flow velocities found in karst conduits, and of predation of colonizing bacteria by autochthonous zooplankton.

A review of Arbuckle Group strata in Kansas from a sedimentologic perspective: Insights for future research from past and recent studies

USGS Publications Warehouse

Franseen, E.K.

2000-01-01

Arbuckle Group and equivalent-age rocks (Cambrian and Lower Ordovician) represent an important record of sediment deposition in the history of the North American continent and they contain important accumulations of hydrocarbons (oil and gas) and base metal deposits. This is true for Kansas as well where Arbuckle strata account for approximately 40% of the volume of produced petroleum and known reserves. However, in comparison to their counterparts in other areas, such as the Ellenburger and Knox, Arbuckle rocks in Kansas remain relatively understudied, especially with respect to sedimentology and diagenesis. The Arbuckle is present in the subsurface in most of Kansas and is absent only in areas of northeastern and northwestern Kansas, and over ancient uplifts and buried Precambrian highs. Arbuckle rocks thicken from north to south and are up to 1,390 feet in the southeastern corner of Kansas. Arbuckle Group and equivalent-age rocks from Kansas and surrounding areas are similar, consisting of platform deposits dominated by ramp-type subtidal to peritidal carbonates (mostly dolomitized) which can be subdivided into cycles, less than 0.5 m to 40 m thick, based on facies type and depositional patterns. Recent studies from central Kansas show that major depositional facies consist of coarse-grained packstones/ grainstones, fine-grained packstones/wackestones/mudstones, stromatolites-thrombolites, intraclastic conglomerate and breccia, and shale. In addition, secondary features include dolomitization, breccia, fracture, and conglomerate related to early subaerial exposure and later karst, burial or structural processes, silicification, and local mineralization. Arbuckle and equivalent strata in the Midcontinent were affected by prolonged subaerial exposure that began immediately after Arbuckle deposition, forming the sub-Tippecanoe to sub-Absaroka unconformity. Favorable reservoir qualities generally are thought to be related directly to basement structural elements and

Estimating exposure to groundwater contaminants in karst areas

NASA Astrophysics Data System (ADS)

Butscher, C.

2012-12-01

Large multidisciplinary projects investigate health effects and environmental impacts of contamination. Such multidisciplinary projects challenge groundwater hydrologist because they demand estimations of human or environmental exposure to groundwater contaminants. But especially in karst regions, groundwater quality is subject to rapid changes resulting from highly dynamic flow systems with rapid groundwater recharge and contaminant transport in karst conduits. There is a strong need for tools that allow the quantification of the risk of contaminant exposure via the karst groundwater and its temporal variation depending on rainfall events and overall hydrological conditions. A fact that makes the assessment of contaminant exposure even more difficult is that many contaminants behave differently in the subsurface than the groundwater, because they do not dissolve and exist as a separate phase. Important examples are particulate contaminants, such as bacteria, and non-aqueous phase liquids (NAPLs), such as many organic compounds. Both are ubiquitous in the environment and have large potential for health impacts. It is known from bacterial contamination of karst springs that such contamination is strongly related to flow conditions. Bacteria, which are present at the land surface, in the soil, rock matrix or the conduit system, are immobile during base flow conditions. During storm events however, they become mobilized and are rapidly transported through the conduit flow system from sources to areas of potential exposure. As a result, bacteria concentrations that most times are low at a spring can show a high peak during storm flow. Conceptual models exist that suggest that the transport of NAPLs in karst aquifers is, just like bacterial contamination, related to flow conditions. Light NAPLs that reach the saturated zone float and accumulate on the water table; and dense NAPLs sink downward in the aquifer until they are trapped in pores, fractures and conduits where

Improved reservoir characterization of the Rose Run sandstone on the East Randolph Field, Portage County, Ohio

DOE Office of Scientific and Technical Information (OSTI.GOV)

Safley, I.E.; Thomas, J.B.

1996-09-01

The East Randolph Field, located in Randolph Township, Portage County, Ohio, produces oil and gas from the Cambrian Rose Run sandstone unit, a member of the Knox Supergroup. Field development and infill drilling opportunities illustrate the need for improved reservoir characterization of the hydrocarbon productive intervals. This reservoir study is conducted under the Department of Energy`s Reservoir Management Program with professionals from BDM-Oklahoma and Belden & Blake Corporation. Well log and core analyses were conducted to determine the reservoir distribution, the heterogeneity of the hydrocarbon producing intervals, and the effects of faulting and fracturing on well productivity. The Rose Runmore » sandstones and interbedded dolomites were subdivided into three productive intervals. Cross sections were constructed for correlation of individual layers and identification of localized faulting. The geologic data was input into GeoGraphix software for construction of structure, net pay, production, and gas- and water-oil ratio maps.« less

Past and present management of water resources in karst environments

NASA Astrophysics Data System (ADS)

Parise, Mario

2010-05-01

Karst is a very peculiar environment, and has a number of intrinsic features that clearly distinguish it from any other natural setting. Hydrology of karst is dominated by absence or very scarce presence of surface runoff, since water rapidly infiltrates underground through the complex network of conduits and fissures that are at the origin of the development of karst caves. The limited presence of water at the surface represented the main problem to be faced by man, starting from the very first historic phases of establishing settlements in karst territories. As often happens in areas with limited natural resources, man was however able to understand the local environment through observations and direct experience, develop technique in order to collect the limited available water resources, and adapt his way of life to the need of the natural environment. In a few words, a sustainable use of the water resources was reached, that went on for many centuries, allowing development of human settlements and agriculture, and, at the same time, protecting and safeguarding the precious hydric resources. Some of the most typical rural architectures built in karst areas of the Mediterranean Basin can be described as examples of such efforts: from the dry stone walls, to many types of storage-houses or dwellings, known with different names, depending upon the different countries and regions. Dry stone walls, in particular, deserve a particular attention, since they had multiple functions: to delimit the fields and properties, to act as a barrier to soil erosion, to allow terracing the high-gradient slopes, to collect and store water. At this latter aim, dry stone walls were build in order to create a small but remarkable micro-environment, functioning as collectors of moisture and water vapour. In the last centuries, with particular regard to the last decades of XX century, the attention paid by man to the need of the natural environment has dramatically changed. This

Karst in the United States: a digital map compilation and database

USGS Publications Warehouse

Weary, David J.; Doctor, Daniel H.

2014-01-01

This report describes new digital maps delineating areas of the United States, including Puerto Rico and the U.S. Virgin Islands, having karst or the potential for development of karst and pseudokarst. These maps show areas underlain by soluble rocks and also by volcanic rocks, sedimentary deposits, and permafrost that have potential for karst or pseudokarst development. All 50 States contain rocks with potential for karst development, and about 18 percent of their area is underlain by soluble rocks having karst or the potential for development of karst features. The areas of soluble rocks shown are based primarily on selection from State geologic maps of rock units containing significant amounts of carbonate or evaporite minerals. Areas underlain by soluble rocks are further classified by general climate setting, degree of induration, and degree of exposure. Areas having potential for volcanic pseudokarst are those underlain chiefly by basaltic-flow rocks no older than Miocene in age. Areas with potential for pseudokarst features in sedimentary rocks are in relatively unconsolidated rocks from which pseudokarst features, such as piping caves, have been reported. Areas having potential for development of thermokarst features, mapped exclusively in Alaska, contain permafrost in relatively thick surficial deposits containing ground ice. This report includes a GIS database with links from the map unit polygons to online geologic unit descriptions.

Karst in Wadi Bani Khalid, Oman

NASA Astrophysics Data System (ADS)

Abdelaziz, Ramadan

2017-04-01

There are several important in Oman. The main aquifer is surficial aquifer and fractured rocks. In fact, the geology of Oman is complex whichmake the hydraulic continuity of bedrock is limited and formaing localized aquifers. caves in Oman are varying types and length, size and geographic formations. Many caves and valleys founded in Oman. Wadi Bani Khalid hosts complex network of fractured rock. Karst in Wadi Bani Kalid made upof Limestone(Calcium, which is dissolve in water.A rain water pass through the rock it is erode the rock and form caves. The cave located in Miqil. The karst was formed in Calcium Carbonate rocks.

U.S. Geological Survey Karst Interest Group: proceedings, St Petersburg, Florida February 13-16, 2001

USGS Publications Warehouse

Kuniansky, Eve L.

2001-01-01

Karst and similar landscapes are found in a wide range of biogeographic classes. In the U.S. for example, Everglades, Mammoth Cave, and Hawaii Volcanoes National Parks have little in common - except karst or pseudokarst, and a cultural past (even though these are very different). This diversity of geologic settings makes karst difficult to categorize and work with when designing a national program such as the recent NPS-USGS Geo-Indicators effort. A GIS-based approach with multiple datalayers is the only sane way to understand and convey the many relationships, in X, Y, and Z axes, between component ecosystems and cultural resources within karst and pseudokarst landscapes. Obviously, karst and cultural landscapes cross modern political as well as biogeographic boundaries. Here again, three-dimensional data are the foundation for understanding similar to that in anatomy and physiology: structure and function. In understanding where the most vulnerable 'pressure points' exist within karst landscapes, we can target landscape-scale ecosystem management to greatest effect. USGS and the National Cave and Karst research Institute could play an extremely significant role in cave and karst management on a national scale beyond NPS or other agency boundaries via cooperative management of three-dimensional karst datasets analogous to programs in several states.

Evolution of collapse valleys in karst - examples from the Carpatho-Balkanides of Serbia

NASA Astrophysics Data System (ADS)

Petrović, Aleksandar S.; Ćalić, Jelena; Spalević, Aleksandra; Pantić, Marko

2016-04-01

Development of valleys in karst is an issue which has not been sufficiently studied in karst surface morphology. THESE valleys are long linear forms whose orthogonal projections resemble normal valleys, but most of their characteristics are strongly influenced by karst process. In largest number of relevant references, this subject is either only briefly mentioned or completely lacking. This paper presents the examples of a particular type of valley in karst formed by cave ceiling collapse close to the topographical surface. Karst of the Carpatho-Balkanides in eastern Serbia is characterized by uneven spatial distribution in several large massifs, but also in a large number of relatively small outcrops (patches and belts), which enable the development of contact karst and fluviokarst. Many morphological elements are of fluvial origin, subsequently modified by karst process. Collapse valleys occur mostly at the downstream contacts (where a seasonal watercourse leaves limestones) or in karst/limestone belts. In the first phase, which is visible on the example of the Radovanska Reka, the river course sinks to the swallets in the riverbed and forms a blind valley. After sinking, the water flows through the tunnel cave, while largest part of the valley remains above the cave. The bottom of the dry valley is dissected by deep dolines, reaching almost to the cave roof. In this part of the study, the area was scanned by a multistation Leica Nova MS 50 (resolution 20 cm @ 10 m). In the second phase, the doline bottoms reach the cave ceilings which develop holes at certain points, as it is case at the Zamna River valley. These hollows tend to enlarge with time, and the surface of the cave ceiling is reduced. The third, final phase is characterised by collapse of larger segments of cave ceilings. Only the natural bridges remain, as the remnants of former caves (e.g. in the Vratna River valley, Ravna Reka valley). These parts of valleys in karst are usually narrow, steep

Petrographic and geochemical evidence for the formation of primary, bacterially induced lacustrine dolomite: La Roda 'white earth' (Pliocene, Central Spain)

USGS Publications Warehouse

Garcia, Del; Cura, M.A.; Calvo, J.P.; Ordonez, S.; Jones, B.F.; Canaveras, J.C.

2001-01-01

Upper Pliocene dolomites ('white earth') from La Roda, Spain, offer a good opportunity to evaluate the process of dolomite formation in lakes. The relatively young nature of the deposits could allow a link between dolomites precipitated in modern lake systems and those present in older lacustrine formations. The La Roda Mg-carbonates (dolomite unit) occur as a 3??5- to 4-m- thick package of poorly indurated, white, massive dolomite beds with interbedded thin deposits of porous carbonate displaying root and desiccation traces as well as local lenticular gypsum moulds. The massive dolomite beds consist mainly of loosely packed 1- to 2-??m-sized aggregates of dolomite crystals exhibiting poorly developed faces, which usually results in a subrounded morphology of the crystals. Minute rhombs of dolomite are sparse within the aggregates. Both knobbly textures and clumps of spherical bodies covering the crystal surfaces indicate that bacteria were involved in the formation of the dolomites. In addition, aggregates of euhedral dolomite crystals are usually present in some more clayey (sepiolite) interbeds. The thin porous carbonate (mostly dolomite) beds exhibit both euhedral and subrounded, bacterially induced dolomite crystals. The carbonate is mainly Ca-dolomite (51-54 mol% CaCO3), showing a low degree of ordering (degree of ordering ranges from 0??27 to 0??48). Calcite is present as a subordinate mineral in some samples. Sr, Mn and Fe contents show very low correlation coefficients with Mg/Ca ratios, whereas SiO2 and K contents are highly correlated. ??18O- and ??13C-values in dolomites range from -3??07??? to 5??40??? PDB (mean = 0??06, ?? = 1??75) and from -6??34??? to -0??39??? PDB (mean = -3??55, ?? = 1??33) respectively. Samples containing significant amounts of both dolomite and calcite do not in general show significant enrichment or depletion in 18O and 13C between the two minerals. The correlation coefficient between ??18O and ??13C for dolomite is extremely

Compression wave studies in Blair dolomite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grady, D.E.; Hollenbach, R.E.; Schuler, K.W.

Dynamic compression wave studies have been conducted on Blair dolomite in the stress range of 0-7.0 GPa. Impact techniques were used to generate stress impulse input functions, and diffuse surface laser interferometry provided the dynamic instrumentation. Experimental particle velocity profiles obtained by this method were coupled with the conservation laws of mass and momentum to determine the stress-strain and stress-modulus constitutive properties of the material. Comparison between dynamic and quasistatic uniaxial stress-strain curves uncovered significant differences. Energy dissipated in a complete load and unload cycle differed by almost an order of magnitude and the longitudinal moduli differed by as muchmore » as a factor of two. Blair dolomite was observed to yield under dynamic loading at 2.5 GPa. Below 2.5 GPa the loading waves had a finite risetime and exhibited steady propagation. A finite linear viscoelastic constitutive model satisfactorily predicted the observed wave propagation. We speculate that dynamic properties of preexisting cracks provides a physical mechanism for both the rate dependent steady wave behavior and the difference between dynamic and quasistatic response.« less

The kinetics of dolomite reaction rim growth under isostatic and non-isostatic pressure conditions

NASA Astrophysics Data System (ADS)

Helpa, V.; Rybacki, E.; Morales, L. G.; Abart, R.; Dresen, G. H.

2013-12-01

During burial and exhumation, rocks are simultaneously exposed to metamorphic reactions and tectonic stresses. Therefore, the reaction rate of newly formed minerals may depend on chemical and mechanical driving forces. Here, we investigate the reaction kinetics of dolomite (CaMg[CO3]2) rim growth by solid-state reactions experiments on oriented calcite (CaCO3) and magnesite (MgCO3) single crystals under isostatic and non-isostatic pressure conditions. Cylindrical samples of 3-5 mm length and 7 mm diameter were drilled and polished perpendicular to the rhombohedral cleavage planes of natural clear crystals. The tests were performed using a Paterson-type deformation apparatus at P = 400 MPa confining pressure, temperatures, T, between 750 and 850°C, and reaction durations, t, of 2 - 146 h to calculate the kinetic parameters of dolomite rim growth under isostatic stress conditions. For non-isostatic reaction experiments we applied in addition differential stresses, σ, up to 40 MPa perpendicular to the contact interface at T = 750°C for 4 - 171 h duration, initiating minor inelastic deformation of calcite. The thickness of the resulting dolomite reaction rims increases linearly with the square root of time, indicating a diffusion-controlled reaction. The rims consist of two different textural domains. Granular dolomite grains (≈ 2 -5 μm grain size) form next to calcite and elongated palisade-shaped grains (1-6 μm diameter) grow perpendicular to the magnesite interface. Texture measurements with the electron backscatter diffraction technique indicate that the orientations of dolomite grains are mainly influenced by the orientation of the calcite educt crystal, in particular in the granular rim. To some extent, the texture of dolomite palisades is also influenced by the orientation of magnesite. The thickness of the two individual layers increases with temperature. At 400 MPa isostatic pressure, T = 750°C and t = 29 hours, a 5 μm thick granular dolomite layer

Investigating surface chemistry-controlled dolomite precipitation in saline, alkaline, and dilute waters

NASA Astrophysics Data System (ADS)

Yoerg, A.; Roberts, J. A.

2017-12-01

Previous experiments have shown carboxylated organic matter facilitates dolomite precipitation at low temperature (< 80°C) in both modern and ancient seawater geochemistries. The efficacy of this mechanism in alternative chemical environments, particularly those typical of modern dolomitic environments, remains unclear. We investigated this question using a series of batch laboratory experiments ranging in duration from hours to several months. Experiments were conducted using fluids representative of environments where dolomite is found/thought to form in the modern, such as evaporative, alkaline lakes, sabkhas, and dilute mixing zones. Results indicate that while carboxylated organic matter promotes mineral precipitation in a variety of chemistries, the resultant mineralogy is primarily a function solution chemistry (i.e. saturation state). Specifically, our results suggest elevated alkalinity may be required to produce a high-Mg phase. In solutions where alkalinity is scarce, only amorphous carbonate phases form in association with organic matter, contrasting the Mg-bearing crystalline phases that result from highly alkaline solutions. Results of high-alkalinity, short-term experiments suggest that initially amorphous material is rapidly transformed into high and low-Mg phases in the presence of carboxylated organic matter, but that within days this mineralogy evolves. Longer timescales or elevated temperature may be necessary to produce an ordered dolomite phase. Additional results from longer term, steady-state experiments and additional analyses (Raman spectroscopy and tender energy spectroscopy) will shed further light on resultant mineralogy and this mechanism of dolomite precipitation.

State-space prediction of spring discharge in a karst catchment in southwest China

NASA Astrophysics Data System (ADS)

Li, Zhenwei; Xu, Xianli; Liu, Meixian; Li, Xuezhang; Zhang, Rongfei; Wang, Kelin; Xu, Chaohao

2017-06-01

Southwest China represents one of the largest continuous karst regions in the world. It is estimated that around 1.7 million people are heavily dependent on water derived from karst springs in southwest China. However, there is a limited amount of water supply in this region. Moreover, there is not enough information on temporal patterns of spring discharge in the area. In this context, it is essential to accurately predict spring discharge, as well as understand karst hydrological processes in a thorough manner, so that water shortages in this area could be predicted and managed efficiently. The objectives of this study were to determine the primary factors that govern spring discharge patterns and to develop a state-space model to predict spring discharge. Spring discharge, precipitation (PT), relative humidity (RD), water temperature (WD), and electrical conductivity (EC) were the variables analyzed in the present work, and they were monitored at two different locations (referred to as karst springs A and B, respectively, in this paper) in a karst catchment area in southwest China from May to November 2015. Results showed that a state-space model using any combinations of variables outperformed a classical linear regression, a back-propagation artificial neural network model, and a least square support vector machine in modeling spring discharge time series for karst spring A. The best state-space model was obtained by using PT and RD, which accounted for 99.9% of the total variation in spring discharge. This model was then applied to an independent data set obtained from karst spring B, and it provided accurate spring discharge estimates. Therefore, state-space modeling was a useful tool for predicting spring discharge in karst regions in southwest China, and this modeling procedure may help researchers to obtain accurate results in other karst regions.

Folk use of medicinal plants in Karst and Gorjanci, Slovenia.

PubMed

Lumpert, Mateja; Kreft, Samo

2017-02-23

Information on the use of medicinal plants in Karst and Gorjanci is not available in the literature, but collection of plants is still an important and widespread practice in these regions. Karst and Gorjanci are two remote regions in Slovenia that are only 120 km apart but have different climates; one region is close to the Italian border, and the other is near the Croatian border. Our aim was to report and compare the use of medicinal plants in both regions. From October 2013 to September 2014, 25 informants each in Karst and Gorjanci were interviewed during field research. The age of the informants ranged from 33 to 89 years, with an average age of 61 years in Karst and 69 years in Gorjanci. The main question was "Which plants do or did you collect from nature and use?" Plants of medicinal, nutritive, veterinary or cosmetic use were considered. A total of 78 and 82 taxa were reported in Karst and Gorjanci, respectively; 65 taxa were reported in both regions. Approximately 64% of the plants in each region were distinctive for only a few informants (fewer than 7). The remaining plants were considered important, and the majority were mutual to both regions. Few reported plants were typical for just one region. Differences in the use of some common medicinal plants were observed, e.g., Matricaria chamomilla was used mostly for the treatment of gastrointestinal disorders, respiratory infections and sore eyes in Gorjanci but as a calmative in Karst. Altogether, 15 different oral and 15 different topical medicinal preparations were reported. Folk knowledge was found to be influenced by the media, particularly popular books about medicinal plants that were published in the 20th century. The present research documents the folk use of medicinal plants in Karst and Gorjanci, Slovenia. This rapidly changing practice needs to be documented before it disappears or changes.

Evaluating Weather Research and Forecasting Model Sensitivity to Land and Soil Conditions Representative of Karst Landscapes

NASA Astrophysics Data System (ADS)

Johnson, Christopher M.; Fan, Xingang; Mahmood, Rezaul; Groves, Chris; Polk, Jason S.; Yan, Jun

2018-03-01

Due to their particular physiographic, geomorphic, soil cover, and complex surface-subsurface hydrologic conditions, karst regions produce distinct land-atmosphere interactions. It has been found that floods and droughts over karst regions can be more pronounced than those in non-karst regions following a given rainfall event. Five convective weather events are simulated using the Weather Research and Forecasting model to explore the potential impacts of land-surface conditions on weather simulations over karst regions. Since no existing weather or climate model has the ability to represent karst landscapes, simulation experiments in this exploratory study consist of a control (default land-cover/soil types) and three land-surface conditions, including barren ground, forest, and sandy soils over the karst areas, which mimic certain karst characteristics. Results from sensitivity experiments are compared with the control simulation, as well as with the National Centers for Environmental Prediction multi-sensor precipitation analysis Stage-IV data, and near-surface atmospheric observations. Mesoscale features of surface energy partition, surface water and energy exchange, the resulting surface-air temperature and humidity, and low-level instability and convective energy are analyzed to investigate the potential land-surface impact on weather over karst regions. We conclude that: (1) barren ground used over karst regions has a pronounced effect on the overall simulation of precipitation. Barren ground provides the overall lowest root-mean-square errors and bias scores in precipitation over the peak-rain periods. Contingency table-based equitable threat and frequency bias scores suggest that the barren and forest experiments are more successful in simulating light to moderate rainfall. Variables dependent on local surface conditions show stronger contrasts between karst and non-karst regions than variables dominated by large-scale synoptic systems; (2) significant

Submerged karst landforms observed by multibeam bathymetric survey in Nagura Bay, Ishigaki Island, southwestern Japan

NASA Astrophysics Data System (ADS)

Kan, Hironobu; Urata, Kensaku; Nagao, Masayuki; Hori, Nobuyuki; Fujita, Kazuhiko; Yokoyama, Yusuke; Nakashima, Yosuke; Ohashi, Tomoya; Goto, Kazuhisa; Suzuki, Atsushi

2015-01-01

Submerged tropical karst features were discovered in Nagura Bay on Ishigaki Island in the southern Ryukyu Islands, Japan. The coastal seafloor at depths shallower than ~ 130 m has been subjected to repeated and alternating subaerial erosion and sedimentation during periods of Quaternary sea-level lowstands. We conducted a broadband multibeam survey in the central area of Nagura Bay (1.85 × 2.7 km) and visualized the high-resolution bathymetric results over a depth range of 1.6-58.5 m. Various types of humid tropical karst landforms were found to coexist within the bay, including fluviokarst, doline karst, cockpit karst, polygonal karst, uvalas, and mega-dolines. Although these submerged karst landforms are covered by thick postglacial reef and reef sediments, their shapes and sizes are distinct from those associated with coral reef geomorphology. The submerged landscape of Nagura Bay likely formed during multiple glacial and interglacial periods. According to our bathymetric results and the aerial photographs of the coastal area, this submerged karst landscape appears to have developed throughout Nagura Bay (i.e., over an area of approximately 6 × 5 km) and represents the largest submerged karst in Japan.

Karst aquifer characterization using geophysical remote sensing of dynamic recharge events

NASA Astrophysics Data System (ADS)

Grapenthin, R.; Bilek, S. L.; Luhmann, A. J.

2017-12-01

Geophysical monitoring techniques, long used to make significant advances in a wide range of deeper Earth science disciplines, are now being employed to track surficial processes such as landslide, glacier, and river flow. Karst aquifers are another important hydrologic resource that can benefit from geophysical remote sensing, as this monitoring allows for safe, noninvasive karst conduit measurements. Conduit networks are typically poorly constrained, let alone the processes that occur within them. Geophysical monitoring can also provide a regionally integrated analysis to characterize subsurface architecture and to understand the dynamics of flow and recharge processes in karst aquifers. Geophysical signals are likely produced by several processes during recharge events in karst aquifers. For example, pressure pulses occur when water enters conduits that are full of water, and experiments suggest seismic signals result from this process. Furthermore, increasing water pressure in conduits during recharge events increases the load applied to conduit walls, which deforms the surrounding rock to yield measureable surface displacements. Measureable deformation should also occur with mass loading, with subsidence and rebound signals associated with increases and decreases of water mass stored in the aquifer, respectively. Additionally, geophysical signals will likely arise with turbulent flow and pore pressure change in the rock surrounding conduits. Here we present seismic data collected during a pilot study of controlled and natural recharge events in a karst aquifer system near Bear Spring, near Eyota, MN, USA as well as preliminary model results regarding the processes described above. In addition, we will discuss an upcoming field campaign where we will use seismometers, tiltmeters, and GPS instruments to monitor for recharge-induced responses in a FL, USA karst system with existing cave maps, coupling these geophysical observations with hydrologic and

Advances in Dynamic Transport of Organic Contaminants in Karst Groundwater Systems

NASA Astrophysics Data System (ADS)

Padilla, I. Y.; Vesper, D.; Alshawabkeh, A.; Hellweger, F.

2011-12-01

Karst groundwater systems develop in soluble rocks such as limestone, and are characterized by high permeability and well-developed conduit porosity. These systems provide important freshwater resources for human consumption and ecological integrity of streams, wetlands, and coastal zones. The same characteristics that make karst aquifers highly productive make them highly vulnerable to contamination. As a result, karst aquifers serve as an important route for contaminants exposure to humans and wildlife. Transport of organic contaminants in karst ground-water occurs in complex pathways influenced by the flow mechanism predominating in the aquifer: conduit-flow dominated systems tend to convey solutes rapidly through the system to a discharge point without much attenuation; diffuse-flow systems, on the other hand, can cause significant solute retardation and slow movement. These two mechanisms represent end members of a wide spectrum of conditions found in karst areas, and often a combination of conduit- and diffuse-flow mechanisms is encountered, where both flow mechanisms can control the fate and transport of contaminants. This is the case in the carbonate aquifers of northern Puerto Rico. This work addresses advances made on the characterization of fate and transport processes in karst ground-water systems characterized by variable conduit and/or diffusion dominated flow under high- and low-flow conditions. It involves laboratory-scale physical modeling and field-scale sampling and historical analysis of contaminant distribution. Statistical analysis of solute transport in Geo-Hydrobed physical models shows the heterogeneous character of transport dynamics in karstic units, and its variability under different flow regimes. Field-work analysis of chlorinated volatile organic compounds and phthalates indicates a large capacity of the karst systems to store and transmit contaminants. This work is part of the program "Puerto Rico Testsite for Exploring Contamination

Runoff generation in karst catchments: multifractal analysis

NASA Astrophysics Data System (ADS)

Majone, Bruno; Bellin, Alberto; Borsato, Andrea

2004-07-01

Time series of hydrological and geochemical signals at two karst springs, located in the Dolomiti del Brenta region, near Trento, Italy, are used to infer how karst catchments work internally to generate runoff. The data analyzed include precipitation, spring flow and electric conductivity of the spring water. All the signals show the signature of multifractality but with different intermittency and non-stationarity. In particular, precipitation and spring flow are shown to have nearly the same degree of non-stationarity and intermittency, while electric conductivity, which mimics the travel time distribution of water in the karst system, is less intermittent and smoother than both spring flow and precipitations. We found that spring flow can be obtained from precipitation through fractional convolution with a power law transfer function. An important result of our study is that the probability distribution of travel times is inconsistent with the advection dispersion equation, while it supports the anomalous transport model. This result is in line with what was observed by Painter et al. [Geophys. Res. Lett. 29 (2002) 21.1] for transport in fractured rocks.

Dolomite dissolution rates and possible Holocene dedolomitization of water-bearing units in the Edwards aquifer, south-central Texas

USGS Publications Warehouse

Deike, R.G.

1990-01-01

Rates of dolomite dissolution can be used to test the concept, based on geomorphologic evidence, that a major part of the Edwards aquifer could have formed within the Holocene, a timeframe of approximately 10,000 years. During formation of the aquifer in the Edwards limestone (Cretaceous, Albian) of the Balcones fault zone, dolomite dissolution and porosity development were synchronous and the result of mixing-zone dedolomitization. Initiation of the mixing zone in the early Holocene (???11,000 years before present) is suggested by the maximum age of formation of major discharge sites that allowed the influx of meteoric water into brine-filled, dolomitic preaquifer units. Dedolomitization, the dissolution of dolomite and net precipitation of calcite, has left aquifer units that are calcitic, and 40 vol.% interconnected pore space. The mass of dolomite missing is obtained by comparison of stratigraphically equivalent altered and unaltered units. One dissolution rate (1.76 ?? 10-4 mmol dolomite kgH2O-1yr-1) is determined from this mass, 104yr reaction time, and a log-linear function describing the increase in mass discharge (three orders of magnitude) during aquifer formation. The second estimated dissolution rate is obtained from the mass transfer of dolomite to solution calculated from the increase in magnesium in pore fluids selected from the modern aquifer to represent a typical flowpath during aquifer formation. A reaction time of 104yr for this mass transfer yields a rate of 0.56 ?? 10-4 mmol dolomite kgH2O-1yr-1. Both of these rates are comparable to modern rates of dolomite dissolution (0.3 to 4.5 ?? 10-4 mmol dolomite kgH2O-1yr-1) calculated from measured reaction times in the Tertiary Floridan aquifer system in Florida and the Madison aquifer in the Mississippian Madison Limestone of the Northern Great Plains. Similarity of these rates to the estimated paleo-rates of dolomite dissolution supports a 104 yr reaction timeframe. The Holocene reaction time also

The formation of lacustrine dolomites: an example from the Tortonian-Messinian sequence at the East Mediterranean margins (northern Israel)

NASA Astrophysics Data System (ADS)

Shaked Gelband, Dotan; Starinsky, Abraham; Stein, Mordechai

2017-04-01

Lacustrine water bodies that filled the tectonic depressions in the Lower Galilee area of Israel during the Tortonian-Messinian periods deposited Bira and Gesher Formations, which comprise marly limestones and dolomites, basalts, and varying amounts of mollusc fossils. Most fossils are gastropods of fresh to brackish water origin, while marine representation is minor and comprise monospecific assemblages of euryhaline bivalves. During the deposition of the Tortonian Bira formation the lakes were mostly influenced by meteoric waters while during the deposition of the Messinian Gesher Formation they became more swampy. Here, we set to establish the deposition conditions of the dolomites in the lacustrine formations. The following petrographic characteristics indicate dolomitization of precursor carbonate sediment during early diagenesis stage: (1) Dolomitized fossils with similar texture as the surrounding dolomite matrix; (2) Common euhedral inner zone crystals, representing original growth in solution or plastic environment; (3) Subhedral outer shape derived from neighboring crystals collisions. More information is given by the δ18O and δ13C values of the dolomites. The δ18O of the inter-layered limestones and dolomites fluctuates between -3‰ to -4‰ (VPDB) in the limestones and +5‰ to -1.5‰ (VPDB) in the adjacent dolomites. These fluctuations are prominent in the Bira formation and become smaller along the sequence with the decrease in the dolomite values. δ13C values of both limestones and dolomites gradually decrease along the stratigraphic section, from -3.5‰ to -10‰ (VPDB) in the limestones, and from 0‰ to -8‰ (VPDB) in the dolomites. The data suggest a dolomitization process controlled by the following events: 1. Evaporation of fresh lake waters originated from the surrounding environment as runoff. It should be emphasized that significant evaporation could take place only in terminal lakes, during periods of relatively dry climate with low

Hydraulic Evolution of Karst Microfracture

NASA Astrophysics Data System (ADS)

Windom, L. M.; Dragila, M. I.; Weisbrod, N.

2017-12-01

Karst terrain comprises an astounding 25% of our planet's potable water resources, yet the evolution of these systems from micro-fracture to open channel is poorly understood. Focusing on the unsaturated portion of an evolving karst system, we present a conceptual model for the hydraulic evolution of micro-fractures into larger conduits. Tensional micro-fractures (< 1mm thick) under unsaturated conditions may be eroded by water flowing either as seepage films or as capillary rivulets. In addition to general erosion, the narrow width of capillary rivulets may etch the beginning of preferential paths within the tensional micro-fractures that will lead to tubular channels. Both fluid mechanisms, seepage and rivulets, were tested in the laboratory, and data of the resulting geochemical erosion rates are presented in the form of calcium dissolution rates measured by inductively coupled plasma atomic emission spectroscopy (ICP-OES).

Identification of karst sinkholes in a forested karst landscape using airborne laser scanning data and water flow analysis

NASA Astrophysics Data System (ADS)

Hofierka, Jaroslav; Gallay, Michal; Bandura, Peter; Šašak, Ján

2018-05-01

Karst sinkholes (dolines) play an important role in a karst landscape by controlling infiltration of surficial water, air flow or spatial distribution of solar energy. These landforms also present a limiting factor for human activities in agriculture or construction. Therefore, mapping such geomorphological forms is vital for appropriate landscape management and planning. There are several mapping techniques available; however, their applicability can be reduced in densely forested areas with poor accessibility and visibility of the landforms. In such conditions, airborne laser scanning (ALS) provides means for efficient and accurate mapping of both land and landscape canopy surfaces. Taking the benefits of ALS into account, we present an innovative method for identification and evaluation of karst sinkholes based on numerical water flow modelling. The suggested method was compared to traditional techniques for sinkhole mapping which use topographic maps and digital terrain modelling. The approach based on simulation of a rainfall event very closely matched the reference datasets derived by manual inspection of the ALS digital elevation model and field surveys. However, our process-based approach provides advantage of assessing the magnitude how sinkholes influence concentration of overland water flow during extreme rainfall events. This was performed by calculating the volume of water accumulated in sinkholes during the simulated rainfall. In this way, the influence of particular sinkholes on underground geomorphological systems can be assessed. The method was demonstrated in a case study of Slovak Karst in the West Carpathians where extreme rainfalls or snow-thaw events occur annually. We identified three spatially contiguous groups of sinkholes with a different effect on overland flow concentration. These results are discussed in relation to the known underground hydrological systems.

Origin of dolomitic rocks in the lower Permian Fengcheng formation, Junggar Basin, China: evidence from petrology and geochemistry

NASA Astrophysics Data System (ADS)

Zhu, Shifa; Qin, Yi; Liu, Xin; Wei, Chengjie; Zhu, Xiaomin; Zhang, Wei

2017-04-01

Although dolomitization of calcite minerals and carbonatization of volcanic rocks have been studied widely, the extensive dolomitic rocks that originated from altered volcanic and volcaniclastic rocks have not been reported. The dolomitic rocks of the Fengcheng Formation in the Junggar Basin of China appear to be formed under unusual geologic conditions. The petrological and geochemical characteristics indicate that the dolomitizing host rock is devitrified volcanic tuff. After low-temperature alteration and calcitization, these tuffaceous rocks are replaced by Mg-rich brine to form massive dolomitic tuffs. We propose that the briny (with -2 ‰ 6 ‰ of δ13CPDB and -5 ‰ 4 ‰ of δ18OPDB) and Mg-rich marine formation water (with 0.7060 0.7087 of 87Sr/86Sr ratio), the thick and intermediate-mafic volcanic ashes, and the tectonically compressional movement may have favored the formation of the unusual dolomitic rocks. We conclude that the proposed origin of the dolomitic rocks can be extrapolated to other similar terranes with volcaniclastic rocks, seabed tuffaceous sediment, and fracture filling of sill.

The formation of the dolomite-analogue norsethite: Reaction pathway and cation ordering

NASA Astrophysics Data System (ADS)

Pimentel, Carlos; Pina, Carlos M.

2014-10-01

Reaction pathways and cation ordering mechanisms involved in the formation of the mineral dolomite in nature still remain poorly understood. This is mainly due to the experimental problems posed by the synthesis of dolomite at ambient conditions, which preclude monitoring its formation in reasonable time scales. However, processes leading to the crystallization of fully-ordered dolomite-like structures can be studied by conducting experiments with mineral analogues, which are more readily precipitated. In this paper we present a study of the formation of the dolomite-analogue norsethite [BaMg(CO3)2] from a slurry which was aged at room temperature during 14 days. We found that norsethite forms by two dissolution-crystallization reactions from an initial amorphous nano-sized precipitate. The first reaction produces a mineral assemblage composed by witherite [BaCO3], northupite [Na3Mg(CO3)2Cl] and norsethite. The second dissolution-crystallization process leads to the almost complete depletion of witherite and northupite in favor of norsethite. While the composition of norsethite crystals rapidly reaches a Ba/Mg = 1 ratio, X-ray diffraction peaks indicate an increase in the crystallinity of those crystals during the first 48 h of reaction. Simultaneously, Ba-Mg cation ordering increases, as shown by the evolution of intensity ratios of certain superstructure and structure reflections. Altogether, these results demonstrate that the formation of fully-ordered norsethite occurs by a sequence of solvent-mediated processes which involve a number of precursors. Our study also suggests that similar processes might lead to the formation of dolomite in natural environments.

Peculiarity and vulnerability of karst settings, analyzed through a review of available environmental indices

NASA Astrophysics Data System (ADS)

Parise, Mario; Mazzei, Marianna

2016-04-01

Karst is a unique environment on Earth, characterized by a variety of peculiar geological and hydrological features, that are expressed by typical landforms at the surface (doline, ponor, polje, etc.) and underground (single cave, sinkhole, complex hypogean systems consisting of sequences of pits and galleries, etc.). Among the main characters of karst, the direct connection between the surface and the underground is at the origin of the fragility of karst settings, and the related high vulnerability. Many different types of natural geological hazards (or geo-hazards) may potentially affect karst lands, with sinkholes and flash floods being the most frequent and typical. In addition, karst is exposed to a variety of anthropogenic disturbances as well, including loss of natural landscapes, destruction of caves and speleothems, and contamination and pollution problems. At this latter regard, it has to be reminded that karst aquifers host high quality groundwaters, that are used as source of drinking water worldwide, with estimates indicating that the supply of drinking water from karst is going to have a significant increase in the next decades, From all of this, the importance in fully defining the karst setting, and in a detail examination of all the natural and anthropogenic events that may cause negative effects on it, comes out. Uniqueness of karst has been acknowledged since a long time, but only in recent years efforts have been made to develop approaches and methods specifically dedicated to this peculiar environment. Such approaches represent definitely a mandatory step in the correct management of karst terranes, providing useful elements to stakeholders, land managers and people living in karst lands about their fragility, and the need to safeguard them and the natural resources therein contained. Starting from these considerations, in this contribution we review the main environmental indices dedicated to karst that have been recently proposed in the

Performance prediction using geostatistics and window reservoir simulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fontanilla, J.P.; Al-Khalawi, A.A.; Johnson, S.G.

1995-11-01

This paper is the first window model study in the northern area of a large carbonate reservoir in Saudi Arabia. It describes window reservoir simulation with geostatistics to model uneven water encroachment in the southwest producing area of the northern portion of the reservoir. In addition, this paper describes performance predictions that investigate the sweep efficiency of the current peripheral waterflood. A 50 x 50 x 549 (240 m. x 260 m. x 0.15 m. average grid block size) geological model was constructed with geostatistics software. Conditional simulation was used to obtain spatial distributions of porosity and volume of dolomite.more » Core data transforms were used to obtain horizontal and vertical permeability distributions. Simple averaging techniques were used to convert the 549-layer geological model to a 50 x 50 x 10 (240 m. x 260 m. x 8 m. average grid block size) window reservoir simulation model. Flux injectors and flux producers were assigned to the outermost grid blocks. Historical boundary flux rates were obtained from a coarsely-ridded full-field model. Pressure distribution, water cuts, GORs, and recent flowmeter data were history matched. Permeability correction factors and numerous parameter adjustments were required to obtain the final history match. The permeability correction factors were based on pressure transient permeability-thickness analyses. The prediction phase of the study evaluated the effects of infill drilling, the use of artificial lifts, workovers, horizontal wells, producing rate constraints, and tight zone development to formulate depletion strategies for the development of this area. The window model will also be used to investigate day-to-day reservoir management problems in this area.« less

Reconstructing geochemical conditions during dolomite formation in a Carnian coastal sabkha using 87Sr/86Sr isotopes - Travenanzes Formation, northern Italy

NASA Astrophysics Data System (ADS)

Rieder, Maximilian; Wegner, Wencke; Horschinegg, Monika; Preto, Nereo; Breda, Anna; Klötzli, Urs; Peckmann, Jörn; Meister, Patrick

2017-04-01

The geochemical conditions that were conducive to primary dolomite formation in extremely shallow evaporitic environments along the Triassic Tethyan margin are still poorly understood. While the massive Triassic dolomites in the Austroalpine and South Alpine realm are largely affected by diagenetic or hydrothermal overprint, Preto et al. (2015) provide evidence of primary dolomite based on nano-crystal aggregates observed under the transmission electron microscope. These dolomites are intercalated in a 100-m-thick sequence of clay (Travenanzes Formation, Southern Alps), deposited on a semi-arid coastal plain in the Late Carnian (Tuvalian II). They may serve as a geochemical archive of evaporative brine composition at the time of dolomite formation. Petrographic and field observations revealed that dolomites occur as three different types, (1) dm- to m-thick homogenous beds, (2) mm-scale laminated (stromatolitic) beds and (3) nodules associated with root traces and palaeosols. In all types, the dolomite is stoichiometrically and structurally well ordered. While the homogeneous dolomites occasionally show a peloidal structure, all types of dolomite are generally microcrystalline. Soft sediment deformation, or brittle deformation with mud infill indicates that the dolomitic sediment was largely unlithified at the time of deposition. We analysed the dolomites under the SEM in backscatter mode and observed largely anhedral structures with grain sizes in the μm-range. The laminated dolomites consist of mm- to cm-scale clay-dolomite alternations, whereby the dolomite often shows a spherulitic growth near the dolomite-clay interface, where further recrystallization was inhibited. We measured strontium isotope ratios (87Sr/86Sr) as an indicator for the source of alkalinity driving dolomite precipitation. Our data are in a range between 0.707672 (homogenous dolomite) and 0.707976 (both 2σ: 4*10-5) (nodular dolomite) indicating a similar trend as in Triassic seawater during

Subterranean karst environments as a global sink for atmospheric methane

NASA Astrophysics Data System (ADS)

Webster, Kevin D.; Drobniak, Agnieszka; Etiope, Giuseppe; Mastalerz, Maria; Sauer, Peter E.; Schimmelmann, Arndt

2018-03-01

The air in subterranean karst cavities is often depleted in methane (CH4) relative to the atmosphere. Karst is considered a potential sink for the atmospheric greenhouse gas CH4 because its subsurface drainage networks and solution-enlarged fractures facilitate atmospheric exchange. Karst landscapes cover about 14% of earth's continental surface, but observations of CH4 concentrations in cave air are limited to localized studies in Gibraltar, Spain, Indiana (USA), Vietnam, Australia, and by incomplete isotopic data. To test if karst is acting as a global CH4 sink, we measured the CH4 concentrations, δ13CCH4, and δ2HCH4 values of cave air from 33 caves in the USA and three caves in New Zealand. We also measured CO2 concentrations, δ13CCO2, and radon (Rn) concentrations to support CH4 data interpretation by assessing cave air residence times and mixing processes. Among these caves, 35 exhibited subatmospheric CH4 concentrations in at least one location compared to their local atmospheric backgrounds. CH4 concentrations, δ13CCH4, and δ2HCH4 values suggest that microbial methanotrophy within caves is the primary CH4 consumption mechanism. Only 5 locations from 3 caves showed elevated CH4 concentrations compared to the atmospheric background and could be ascribed to local CH4 sources from sewage and outgassing swamp water. Several associated δ13CCH4 and δ2HCH4 values point to carbonate reduction and acetate fermentation as biochemical pathways of limited methanogenesis in karst environments and suggest that these pathways occur in the environment over large spatial scales. Our data show that karst environments function as a global CH4 sink.

Porosity Gradient Development Around Karst Features due to Tidal Pumping in Eastern Yucatan Peninsula

NASA Astrophysics Data System (ADS)

Maqueda, A.; Renard, P.

2016-12-01

Water exchange between karst features and the porous matrix around them has been observed in karst aquifers by previous research. The exchange is driven by hydraulic head gradients caused by stormwater runoff or sea tides and may cause mineral dissolution. The authors of this work proposed a conceptual model of porosity development under tidal variations of hydraulic head is proposed. Simulations of reactive transport and porosity evolution were conducted to explore the porosity gradient development around a karst feature. Simulations account for petrophysical properties of porous media and groundwater geochemical characteristics. Data used in simulations corresponds to an eogenetic karst aquifer found on the eastern coast of Yucatan Peninsula in Mexico. Simulations include both analytical and numerical solutions of porosity increase caused by mineral dissolution. The estimated rate of porosity development and associated wall retreat (3-30 cm/100 yr) are large enough to develop karst cavities on time periods relevant to karst formation in the study area (10K yr). The analytical solution could be used to assess porosity increase in rock samples and can be also applied to model slow reactions in porous media under flow driven by sinusoidal hydraulic boundary conditions. The results show a possible alternative mechanism of karst cavity development in a high conductive limestone rock matrix aquifer.

Effects of dicyandiamide and dolomite application on N2O emission from an acidic soil.

PubMed

Shaaban, Muhammad; Wu, Yupeng; Peng, Qi-an; Lin, Shan; Mo, Yongliang; Wu, Lei; Hu, Ronggui; Zhou, Wei

2016-04-01

Soil acidification is a major problem for sustainable agriculture since it limits productivity of several crops. Liming is usually adopted to ameliorate soil acidity that can trigger soil processes such as nitrification, denitrification, and loss of nitrogen (N) as nitrous oxide (N2O) emissions. The loss of N following liming of acidic soils can be controlled by nitrification inhibitors (such as dicyandiamide). However, effects of nitrification inhibitors following liming of acidic soils are not well understood so far. Here, we conducted a laboratory study using an acidic soil to examine the effects of dolomite and dicyandiamide (DCD) application on N2O emissions. Three levels of DCD (0, 10, and 20 mg kg(-1); DCD0, DCD10, and DCD20, respectively) were applied to the acidic soil under two levels of dolomite (0 and 1 g kg(-1)) which were further treated with two levels of N fertilizer (0 and 200 mg N kg(-1)). Results showed that N2O emissions were highest at low soil pH levels in fertilizer-treated soil without application of DCD and dolomite. Application of DCD and dolomite significantly (P ≤ 0.001) reduced N2O emissions through decreasing rates of NH4 (+)-N oxidation and increasing soil pH, respectively. Total N2O emissions were reduced by 44 and 13% in DCD20 and dolomite alone treatments, respectively, while DCD20 + dolomite reduced N2O emissions by 54% when compared with DCD0 treatment. The present study suggests that application of DCD and dolomite to acidic soils can mitigate N2O emissions.

Influence of ameliorating soil acidity with dolomite on the priming of soil C content and CO2 emission.

PubMed

Shaaban, Muhammad; Wu, Lei; Peng, Qi-An; van Zwieten, Lukas; Chhajro, Muhammad Afzal; Wu, Yupeng; Lin, Shan; Ahmed, Muhammad Mahmood; Khalid, Muhammad Salman; Abid, Muhammad; Hu, Ronggui

2017-04-01

Lime or dolomite is commonly implemented to ameliorate soil acidity. However, the impact of dolomite on CO 2 emissions from acidic soils is largely unknown. A 53-day laboratory study was carried out to investigate CO 2 emissions by applying dolomite to an acidic Acrisol (rice-rapeseed rotation [RR soil]) and a Ferralsol (rice-fallow/flooded rotation [RF soil]). Dolomite was dosed at 0, 0.5, and 1.5 g 100 g -1 soil, herein referred to as CK, L, and H, respectively. The soil pH (H2O) increased from 5.25 to 7.03 and 7.62 in L and H treatments of the RR soil and from 5.52 to 7.27 and 7.77 in L and H treatments of the RF soil, respectively. Dolomite application significantly (p ≤ 0.001) increased CO 2 emissions in both RR and RF soils, with higher emissions in H as compared to L dose of dolomite. The cumulative CO 2 emissions with H dose of dolomite were greater 136% in the RR soil and 149% in the RF soil as compared to CK, respectively. Dissolved organic carbon (DOC) and microbial biomass carbon (MBC) increased and reached at 193 and 431 mg kg -1 in the RR soil and 244 and 481 mg kg -1 in the RF soil by H treatments. The NH 4 - -N and NO 3 - -N were also increased by dolomite application. The increase in C and N contents stimulated microbial activities and therefore higher respiration in dolomite-treated soil as compared to untreated. The results suggest that CO 2 release in dolomite-treated soils was due to the priming of soil C content rather than chemical reactions.

SWISSKARST Project - how to document the karst aquifers in Switzerland using the KARSYS approach.

NASA Astrophysics Data System (ADS)

Malard, A.; Vouillamoz, J.; Jeannin, P.-Y.; Weber, E.; Eichenberger, U.

2012-04-01

Swiss karst aquifers are poorly documented although they represent a resource estimated to around 120 km3 of fresh water - which is comparable to the water volume of all Swiss lakes. Within the framework of the Swiss National Research Program 61 an opportunity was given to develop a systematic way to characterize karst aquifers and to describe their hydrological behaviour. The project aims at providing methodologies or guidelines to approach karst systems and to improve their management. This covers a large range of fields such as water supply, civil engineering, renewable energies, natural hazards, etc. In this context SISKA developed a dedicated approach named KARSYS for KARst SYStems characterization. It is based on iterations of 3D geological models combined with some basic hydraulic principles taking place in karst media. The main principles are: (i) The 3D geometry of the aquifer set the framework in which flow processes take place (ii) Aquifers are flooded below the level of the main perennial springs (iii) The expansion of the water table upstream of the main springs is lower than 1% (low water stage). High water gradients are simulated according to the elevation of temporary springs or observations in existing boreholes or caves. The approach explicitly shows through 3D visual that some groundwater bodies may be separated at low water stage and connected at high water. Such 3D views bring often explanations to the interpretation of "strange" or "not repeatable" dye tracer's results. A major input of KARSYS approach is to provide a systematic construction of a conceptual model for all hydrological karst systems. It also considers interactions between adjacent systems, providing new concepts on the delineation of karst systems. KARSYS approach can be applied in a quick and approximate way and improved along in order to reach a precision according to the question to be addressed. Results of KARSYS applications are: (i) The delineation of catchment areas of

The effect of electrolytes on dolomite dissolution: nanoscale observations using in situ Atomic Force Microscopy

NASA Astrophysics Data System (ADS)

Urosevic, Maja; Ruiz-Agudo, Encarnacion; Putnis, Christine V.; Cardell, Carolina; Rodriguez-Navarro, Carlos; Putnis, Andrew

2010-05-01

Dissolution of carbonate minerals is one of the main chemical reactions occurring at shallow levels in the crust of the Earth and has a paramount importance for a wide range of geological and biological processes. Calcite (CaCO3), and to a lesser extent dolomite (CaMg(CO3)2), are the major carbonate minerals in sedimentary rocks and building stone materials. The dissolution of calcite has been thoroughly investigated over a range of conditions and solution compositions. In contrast, dolomite dissolution studies have been traditionally hampered by its low reaction rates compared to calcite and its poorly constrained relationship between cation ordering and reactivity (Morse and Arvidson, 2002). Yet important questions like the so-called 'dolomite problem' (e.g. Higgins and Hu, 2005) remain unresolved and more experimental work is needed in order to understand the role of other dissolved species, such as soluble salts, on the kinetics and mechanism of dolomite dissolution and precipitation. We have explored the effect of different electrolytes on the dissolution rate of dolomite by using in situ Atomic Force Microcopy (AFM). Experiments were carried out by passing alkali halide, nitrate and sulfate salt solutions (NaCl, KCl, LiCl, NaI, NaNO3 and Na2SO4) with different ionic strengths (IS = 10-3, 10-2 and 10-1) over dolomite {1014} cleavage surfaces. We show that all electrolytes tested enhance dolomite dissolution. Moreover, the morphology and density of etch pits are controlled by the presence of different ions in solution. The etch pit spreading rate and dolomite dissolution rate depend on both (1) the nature of the electrolyte and (2) the ionic strength. This is in agreement with recent experimental studies on calcite dissolution (Ruiz-Agudo et al., 2010). This study highlights the role of electrolytes in dolomite dissolution and points to a common behavior for carbonate minerals. Our results suggest that soluble salts may play a critical role in the weathering of

Hazard connected to tunnel construction in Mt Stena karstic area (Rosandra Valley, Classical Karst)

NASA Astrophysics Data System (ADS)

Cucchi, F.; Boschin, W.; Visintin, L.; Zini, L.

2009-04-01

Rosandra Valley -a unique geomorphological environment- is located in the western side of the Classical Karst plateau. This deep limestone gorge is crossed by a stream that is fed by a large basin located in Slovenia. Rosandra Valley is the only example of Classical Karst river valley with surface hydrography; the torrent digs a deep gully into the rock, rich in rapids, swirl holes, small waterfalls, enclosed meanders and basins; here, the first seepage phenomena occur, and part of the water feeds the underground aquifer. Rosandra Valley is theatre to complex structural situation; the NE slope culminates in the structure of Mt Stena, a limestone tectonic scale located between two faults and firmly rooted in the karst platform. Tectonics is quite important for the development of deep karst in this area; Mt Stena, in particular, hosts a comprehensive net of articulated and diversely shaped caves, basically organised on several levels, which stretches over a total of 9,000 metres, bearing testimony to ancient geological and hydrogeological origins. The deepest areas of the system reach a suspended aquifer that is probably sustained by an overthrust and placed about 100 meters above Rosandra torrent underground aquifer. During feasibility studies about Trieste-Divača high velocity railway link, interaction between project and karst features was examined; in fact the proximity of proposal project and Mt Stena karst system suggest to improve the knowledge related to karst and hydrogeological aspects of the massif. Compatibly with the project requirements, risk of voids intersection and water contamination were analyzed. In fact the Mt Stena suspended aquifer partially feeds Rosandra torrent which flows in a protected natural area. Karst features were represented in a 3D model in order to better understand the spatial relationship between railway project and karst system.

Assessment of Deep Seated Geothermal Reservoirs in Selected European Sedimentary Environments

NASA Astrophysics Data System (ADS)

Ungemach, Pierre; Antics, Miklos

2014-05-01

Europe at large enjoys a variety of sedimentary environments. They most often host dependable geothermal reservoirs thus favouring the farming of hot fluids, within the low to medium enthalpy range, among which geothermal district heating (GDH) and combined heat and power (CHP) undertakings hold a dominant share. Three selected reservoir settings, addressing carbonate and clastic deposits, the Central part of the Paris Basin, the Southern Germany Molasse Basin in the Münich area and the Netherland Basin respectively will be presented and the exploratory, modeling and development strategies discussed accordingly. Whereas 2D (reprocessed) and 3D seismics have become a standard in matching the distinctive (reef facies, an echelon faulting, carbonate platform layering) features of a deep buried karst and a key to drilling success in the Molasse Basin, thus emphasizing a leading exploratory rationale, the Netherland and Paris Basin instead benefit from a mature data base inherited from extensive hydrocarbon exploration campaigns, with concerns focused on reservoir modeling and sustainable management issues. As a result the lessons learned from the foregoing have enabled to build up a nucleus of expertise in the whole chain from resource identification to reservoir assessment and market penetration. The seismic risk, indeed a sensitive though somewhat emotional issue, which is requiring special attention and due microseismic monitoring from the geothermal community will also be commented.

Substrate pH and butterfly bush response to dolomitic lime or steel slag amendment

USDA-ARS?s Scientific Manuscript database

Steel slag is a fertilizer amendment with a high concentration of calcium oxide, and thus capable of raising substrate pH similar to dolomitic lime. Steel slag, however, contains higher concentrations of some nutrients, such as iron, manganese, and silicon, compared to dolomitic lime. The objectiv...

Geologic constraints to fluid flow in the Jurassic Arab D reservoir, eastern Saudi Arabia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Laing, J.E.

1991-08-01

A giant oil field located in eastern Saudi Arabia has produced several billion barrels of 37{degree} API oil from fewer than 100 wells. The Upper Jurassic Arab Formation is the main producing unit, and is made up of a series of upward-shoaling carbonate and anhydrite members. Porous carbonates of the Arab D member make up the principle oil reservoir, and overlying Arab D anhydrite provides the seal. Principal reservoir facies are stromatoporoid-coral and skeletal grainstones. Reservoir drive is currently provided by flank water injection. Despite more than 30 years of flank water injection (1.5 billion bbl) into the northern areamore » of the field, a thick oil column remains in the Arab D reservoir. Geological factors which affect fluid flow in this area are (1) a downdip facies change from permeable skeletal-stromatoporoid limestone to less permeable micritic limestone, (2) vertical permeability barriers resulting from shoaling-upward cycles, (3) a downdip tar mat, (4) dolomite along the flanks in the upper portion of the reservoir, (5) highly permeable intervals within the skeletal-stromatoporoid limestone, and (6) an updip, north to south facies change from predominantly stromatoporoid-coral grainstone to skeletal grainstone. These factors are considered in reservoir modeling, simulation studies, and planning locations for both water injection and producer wells.« less

Field observations of extended seawater intrusion through subsurface karst conduit networks at Wakulla Spring in the Woodville Karst Plain, Florida

NASA Astrophysics Data System (ADS)

Xu, Z.; Bassett, S.; Hu, B. X.; Dyer, S.

2016-12-01

Five periods of increased electrical conductivity have been found in the karst conduits supplying one of the largest first magnitude springs in Florida with water. Numerous well-developed conduit networks are distributed in the Woodville Karst Plain (WKP), Florida and connected to the Gulf of Mexico. A composite analysis of precipitation and electric conductivity data provides strong evidence that the increases in conductivity are directly tied to seawater intrusion moving inland and traveling 14 miles against the prevailing regional hydraulic gradient from from Spring Creek Spring Complex (SCSC), a group of submarine springs at the Gulf Coast. A geochemical analysis of samples from the spring vent rules out anthropogenic contamination and upwelling regional recharge from the deep aquifer as sources of the rising conductivity. The interpretation is supported by the conceptual model established by prior researchers working to characterize the study area. This abstract documented the first and longest case of seawater intrusion in the WKP, and also indicates significant possibility of seawater contamination through subsurface conduit networks in a coastal karst aquifer.

Mechanisms of flexural flow folding of competent single-layers as evidenced by folded fibrous dolomite veins

NASA Astrophysics Data System (ADS)

Torremans, Koen; Muchez, Philippe; Sintubin, Manuel

2014-12-01

Flexural flow is thought unlikely to occur in naturally deformed, competent isotropic single-layers. In this study we discuss a particular case of folded bedding-parallel fibrous dolomite veins in shale, in which the internal strain pattern and microstructural deformation features provide new insights in the mechanisms enabling flexural flow folding. Strain in the pre-folding veins is accommodated by two main mechanisms: intracrystalline deformation by bending and intergranular deformation with bookshelf rotation of dolomite fibres. The initially orthogonal dolomite fibres allowed a reconstruction of the strain distribution across the folded veins. This analysis shows that the planar mechanical anisotropy created by the fibres causes the veins to approximate flexural flow. During folding, synkinematic veins overgrow the pre-folding fibrous dolomite veins. Microstructures and dolomite growth morphologies reflect growth during progressive fold evolution, with evidence for flexural slip at fold lock-up. Homogeneous flattening, as evidenced by disjunctive axial-planar cleavage, subsequently modified these folds from class 1B to 1C folds. Our study shows that the internal vein fabric has a first-order influence on folding kinematics. Moreover, the fibrous dolomite veins show high viscosity contrasts with the shale matrix, essential in creating transient permeability for subsequent mineralising stages in the later synkinematic veins during progressive folding.

Messinian Salinity Crisis' Primary Evaporites: the shallow gypsum vs. deep dolomite formation paradox solved

NASA Astrophysics Data System (ADS)

De Lange, G. J.; Krijgsman, W.

2015-12-01

The Messinian Salinity Crisis (MSC) is a dramatic event that took place ~ 5.9 Ma ago, resulting in deposition of 1-3 km thick evaporites at the Mediterranean seafloor. A considerable, long-lasting controversy existed on the modes of their formation, including the observed shallow gypsum versus deep dolostone deposits for the early phase of MSC. The onset of MSC is marked by deposition of gypsum/sapropel-like alternations, thought to relate to arid/humid climate conditions at a precessional rhythm. Gypsum precipitation only occurred at marginal- and dolomite formation at deeper settings. A range of potential explanations was given, most of which cannot satisfactorily explain all observations. Biogeochemical processes during MSC are commonly neglected but may explain that different deposits formed in shallow vs deep environments without exceptional physical boundary conditions for each. A unifying mechanism is presented in which gypsum formation occurs at all shallow water depths but its preservation is limited to shallow sedimentary settings. In contrast, ongoing deep-basin anoxic organic matter (OM) degradation processes result in dolomite formation. Gypsum precipitation in evaporating seawater takes place at 3-7 times concentrated seawater; seawater is always oversaturated relative to dolomite but its formation is inhibited by the presence of dissolved sulphate. Thus conditions for formation of gypsum exclude those for formation of dolomite and vice versa. Another process linking the saturation states of gypsum and dolomite is that of OM degradation by sulphate reduction. In stagnant deep water, ongoing OM-degradation may result in reducing the sulphate and enhancing the dissolved carbonate content. Such low-sulphate / high carbonate conditions in MSC deepwater are. unfavorable for gypsum preservation and favorable for dolomite formation, and always coincide with anoxic, i.e. oxygen-free conditions. Including dynamic biogeochemical processes in the thusfar static

Geochemistry and origin of regional dolomites. Technical progress report, July 26, 1991--April 21, 1992

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hanson, G.N.; Meyers, W.J.

1992-07-01

This grant supports research on the origins and geochemical aspects of regional dolomites. Eight graduate students are involved in research on dolomite allowing a diverse range of studies. This report outlines their work in the field. (JL)

Karst medium characterization and simulation of groundwater flow in Lijiang Riversed, China

NASA Astrophysics Data System (ADS)

Hu, B. X.

2015-12-01

It is important to study water and carbon cycle processes for water resource management, pollution prevention and global warming influence on southwest karst region of China. Lijiang river basin is selected as our study region. Interdisciplinary field and laboratory experiments with various technologies are conducted to characterize the karst aquifers in detail. Key processes in the karst water cycle and carbon cycle are determined. Based on the MODFLOW-CFP model, new watershed flow and carbon cycle models are developed coupled subsurface and surface water flow models, flow and chemical/biological models. Our study is focused on the karst springshed in Mao village. The mechanisms coupling carbon cycle and water cycle are explored. Parallel computing technology is used to construct the numerical model for the carbon cycle and water cycle in the small scale watershed, which are calibrated and verified by field observations. The developed coupling model for the small scale watershed is extended to a large scale watershed considering the scale effect of model parameters and proper model structure simplification. The large scale watershed model is used to study water cycle and carbon cycle in Lijiang rivershed, and to calculate the carbon flux and carbon sinks in the Lijiang river basin. The study results provide scientific methods for water resources management and environmental protection in southwest karst region corresponding to global climate change. This study could provide basic theory and simulation method for geological carbon sequestration in China karst region.

Dolomites and Early Mississippian bioherms, Leadville Formation, Molas Lake, Colorado

DOE Office of Scientific and Technical Information (OSTI.GOV)

Young, L.M.

Two dolomite facies that exhibit little petrographic evidence of their original textures are interpreted to be integral parts of two bioherms. A core facies of rugose corals (Vesiculophylum), pelmatozoans, cephalopods, and brachiopods in a peloid wackestone-packstone matrix forms two mounds 50 x 40 m and 110 x 75 m in diameter and 7 and 20 m high, resting on a basal unit of foraminiferal (endothyrid) ooid, coated-grain grainstone. These mounds are surrounded and onlapped by a bedded flank facies with relic cross-bedding that forms a halo 15-40 m wide around each mound. The facies consists of very coarsely to coarselymore » crystalline dolomite, but field evidence shows that it was originally detrital and is coeval with the core facies. It grades laterally away from the core into a distal flank-intermound facies of dolomudstone interbedded with millimeter-thick laminae of dolomite peloid packstone. This facies occurs up to 100 m from the mounds. Corals in the core facies have been replaced and cemented by nonferroan, nonluminescent sparry calcite at temperatures of at least 200/sup 0/C. The matrix of micrite and skeletal grains is composed of nonferroan, red-orange luminescent calcite. Diagenetic changes have been modest. In contrast, the two flank facies show obliteration of original textures and replacement by inclusion-rich, nonferroan, red-luminescent, anhedral to subhedral dolomite at temperatures of a least 165/sup 0/C. Other than appealing to differences in original porosity and susceptibility to subsurface fluids, it is difficult to explain why these closely associated facies have followed such divergent diagenetic paths.« less

Characterizing fate and transport properties in karst aquifers under different hydrologic conditions

NASA Astrophysics Data System (ADS)

Rodriguez, E.; Padilla, I. Y.

2017-12-01

Karst landscapes contain very productive aquifers. The hydraulic and hydrogeological characteristics of karst aquifers make these systems capable of storing and transporting large amount of water, but also highly vulnerable to contamination. Their extremely heterogeneous nature prevents accurate prediction in contaminant fate and transport. Even more challenging is to understand the impact of hydrologic conditions changes on fate and transport processes. This studies aims at characterizing fate and transport processes in the karst groundwater system of northern Puerto Rico under different hydrologic conditions. The study involves injecting rhodamine and uranine dyes into a sinkhole, and monitoring concentrations at a spring. Results show incomplete recovery of tracers, but breaking curves can be used to estimate advective, dispersive and mass transfer characteristic of the karst system. Preliminary results suggest significant differences in fate and transport characteristics under different hydrologic conditions.

Hydrogeology of northern Sierra de Chiapas, Mexico: a conceptual model based on a geochemical characterization of sulfide-rich karst brackish springs

NASA Astrophysics Data System (ADS)

Rosales Lagarde, Laura; Boston, Penelope J.; Campbell, Andrew R.; Hose, Louise D.; Axen, Gary; Stafford, Kevin W.

2014-09-01

Conspicuous sulfide-rich karst springs flow from Cretaceous carbonates in northern Sierra de Chiapas, Mexico. This is a geologically complex, tropical karst area. The physical, geologic, hydrologic and chemical attributes of these springs were determined and integrated into a conceptual hydrogeologic model. A meteoric source and a recharge elevation below 1,500 m are estimated from the spring-water isotopic signature regardless of their chemical composition. Brackish spring water flows at a maximum depth of 2,000 m, as inferred from similar chemical attributes to the produced water from a nearby oil well. Oil reservoirs may be found at depths below 2,000 m. Three subsurface environments or aquifers are identified based on the B, Li+, K+ and SiO2 concentrations, spring water temperatures, and CO2 pressures. There is mixing between these aquifers. The aquifer designated Local is shallow and contains potable water vulnerable to pollution. The aquifer named Northern receives some brackish produced water. The composition of the Southern aquifer is influenced by halite dissolution enhanced at fault detachment surfaces. Epigenic speleogenesis is associated with the Local springs. In contrast, hypogenic speleogenesis is associated with the brackish sulfidic springs from the Northern and the Southern environments.

Structures of dolomite at ultrahigh pressure and their influence on the deep carbon cycle

PubMed Central

Merlini, Marco; Crichton, Wilson A.; Hanfland, Michael; Gemmi, Mauro; Müller, Harald; Kupenko, Ilya; Dubrovinsky, Leonid

2012-01-01

Carbon-bearing solids, fluids, and melts in the Earth's deep interior may play an important role in the long-term carbon cycle. Here we apply synchrotron X-ray single crystal micro-diffraction techniques to identify and characterize the high-pressure polymorphs of dolomite. Dolomite-II, observed above 17 GPa, is triclinic, and its structure is topologically related to CaCO3-II. It transforms above 35 GPa to dolomite-III, also triclinic, which features carbon in [3 + 1] coordination at the highest pressures investigated (60 GPa). The structure is therefore representative of an intermediate between the low-pressure carbonates and the predicted ultra-high pressure carbonates, with carbon in tetrahedral coordination. Dolomite-III does not decompose up to the melting point (2,600 K at 43 GPa) and its thermodynamic stability demonstrates that this complex phase can transport carbon to depths of at least up to 1,700 km. Dolomite-III, therefore, is a likely occurring phase in areas containing recycled crustal slabs, which are more oxidized and Ca-enriched than the primitive lower mantle. Indeed, these phases may play an important role as carbon carriers in the whole mantle carbon cycling. As such, they are expected to participate in the fundamental petrological processes which, through carbon-bearing fluids and carbonate melts, will return carbon back to the Earth’s surface. PMID:22869705

Transport of barium through dolomite rocks under the presence of guar gum and brine salinities of hydraulic fracturing wastewater

NASA Astrophysics Data System (ADS)

Ebrahimi, P.; Vilcaez, J.

2017-12-01

Hydraulic fracturing wastewater (HFW) containing high concentrations of Ba, is commonly disposed into the deep saline aquifers. We investigate the effect of brine salinity, competing cations (Ca and Mg), and guar gum (most common fracturing viscosifier) on the sorption and transport of Ba through dolomite rocks. To this aim, we have conducted batch sorption and core-flooding experiments at both ambient (22°C) and deep subsurface (60°C) temperature conditions. The effect of mineral composition is assessed by comparing batch and core-flooding experimental results obtained with sandstone and dolomite rocks. Batch sorption experiments conducted using powdered dolomite rocks (500-600 µm particle size) revealed that Ba sorption on dolomite greatly decreases with increasing brine salinity (0 - 180,000 mg-NaCl/L), and that at brine salinities of HFW, chloro-complexation reactions between Ba and Cl ions and changes in pH (that results from dolomite dissolution) are the controlling factors of Ba sorption on dolomite. Organo-complexation reactions between Ba and guar gum, and competition of Ba with common cations (Ca and Mg) for hydration sites of dolomite, play a secondary role. This finding is in accordance with core-flooding experimental results, showing that the transport of Ba through synthetic dolomite rocks of high flow properties (25-29.6% porosity, 9.6-13.7 mD permeability), increases with increasing brine salinity (0-180,000 mg-NaCl/L), while the presence of guar gum (50-500 mg/L) does not affect the transport of Ba. On the other hand, core-flooding experiments conducted using natural dolomite core plugs (6.5-8.6% porosity, 0.06-0.3 mD permeability), indicates that guar gum can clog the pore throats of tight dolomite rocks retarding the transport of Ba. Results of our numerical simulation studies indicate that the mechanism of Ba sorption on dolomite can be represented by a sorption model that accounts for both surface complexation reactions on three distinct

Eogenetic karst hydrology: Insights from the 2004 hurricanes, peninsular Florida

USGS Publications Warehouse

Florea, L.J.; Vacher, H. Leonard

2007-01-01

Eogenetic karst lies geographically and temporally close to the depositional environment of limestone in warm marine water at low latitude, in areas marked by midafternoon thunderstorms during a summer rainy season. Spring hydrographs from such an environment in north-central Florida are characterized by smooth, months-long, seasonal maxima. The passage of Hurricanes Frances and Jeanne in September 2004 over three field locations shows how the eogenetic karst of the Upper Floridan Aquifer responds to unequivocal recharge events. Hydrographs at wells in the High Springs area, Rainbow Springs, and at Morris, Briar, and Bat Caves all responded promptly with a similar drawn-out rise to a maximum that extended long into the winter dry season. The timing indicates that the typical hydrograph of eogenetic karst is not the short-term fluctuations of springs in epigenic, telogenetic karst, or the smoothed response to all the summer thunderstorms, but rather the protracted response of the system to rainfall that exceeds a threshold. The similarity of cave and noncave hydrographs indicates distributed autogenic recharge and a free communication between secondary porosity and permeable matrix - both of which differ from the hydrology of epigenic, telogenetic karst. At Briar Cave, drip rates lagged behind the water table rise, suggesting that recharge was delivered by fractures, which control the cave's morphology. At High Springs, hydrographs at the Santa Fe River and a submerged conduit apparently connected to it show sharp maxima after the storms, unlike the other cave hydrographs. Our interpretation is that the caves, in general, are discontinuous. ?? 2007 National Ground Water Association.

Eogenetic karst hydrology: insights from the 2004 hurricanes, peninsular Florida.

PubMed

Florea, Lee J; Vacher, H L

2007-01-01

Eogenetic karst lies geographically and temporally close to the depositional environment of limestone in warm marine water at low latitude, in areas marked by midafternoon thunderstorms during a summer rainy season. Spring hydrographs from such an environment in north-central Florida are characterized by smooth, months-long, seasonal maxima. The passage of Hurricanes Frances and Jeanne in September 2004 over three field locations shows how the eogenetic karst of the Upper Floridan Aquifer responds to unequivocal recharge events. Hydrographs at wells in the High Springs area, Rainbow Springs, and at Morris, Briar, and Bat Caves all responded promptly with a similar drawn-out rise to a maximum that extended long into the winter dry season. The timing indicates that the typical hydrograph of eogenetic karst is not the short-term fluctuations of springs in epigenic, telogenetic karst, or the smoothed response to all the summer thunderstorms, but rather the protracted response of the system to rainfall that exceeds a threshold. The similarity of cave and noncave hydrographs indicates distributed autogenic recharge and a free communication between secondary porosity and permeable matrix-both of which differ from the hydrology of epigenic, telogenetic karst. At Briar Cave, drip rates lagged behind the water table rise, suggesting that recharge was delivered by fractures, which control the cave's morphology. At High Springs, hydrographs at the Santa Fe River and a submerged conduit apparently connected to it show sharp maxima after the storms, unlike the other cave hydrographs. Our interpretation is that the caves, in general, are discontinuous.

Reactive transport modeling of ferroan dolomitization by seawater interaction with mafic igneous dikes and carbonate host rock at the Latemar platform, Italy

NASA Astrophysics Data System (ADS)

Blomme, Katreine; Fowler, Sarah Jane; Bachaud, Pierre

2017-04-01

The Middle Triassic Latemar carbonate platform, northern Italy, has featured prominently in the longstanding debate regarding dolomite petrogenesis [1-4]. Recent studies agree that ferroan and non-ferroan dolomite replaced calcite in limestone during reactive fluid flow at <0.1 GPa and 40-80°C. Regional igneous activity drove heating that provided kinetically favorable conditions for the replacement reaction. However, the origin of the dolomitizing fluid is unclear. Seawater may have been an important component, but its Fe concentrations are insufficient to account for ferroan dolomite. New field, petrographic, XRD, and geochemical data document a spatial, temporal, and geochemical link between ferroan replacement dolomite and altered mafic igneous dikes that densely intrude the platform. A critical observation is that ferroan dolomite abundances increase towards the dikes. We hypothesize that seawater interacted with mafic minerals in the dikes, leading to Fe enrichment in the fluid that subsequently participated in dolomitization. This requires that dolomite formation was preceded by dike alteration reactions that liberated Fe and did not consume Mg. Another requirement is that ferroan and non-ferroan dolomite (instead of other Fe- and Mg-bearing minerals) formed during fluid circulation within limestone host rock. We present reactive transport numerical simulations (Coores-Arxim, [5]) that predict equilibrium mineral assemblages and the evolution of fluid dolomitizing potential from dike crystallization, through dike alteration by seawater, to replacement dolomitization in carbonate host rock. The simulations are constrained by observations. A major advantage of the simulations is that stable mineral assemblages are identified based on a forward modeling approach. In addition, the dominant igneous minerals (plagioclase, clinopyroxene olivine and their alteration products) are solid solutions. Most reactive transport simulations of carbonate petrogenesis do not

Experimental determination of the solubility product of dolomite at 50-253 °C

NASA Astrophysics Data System (ADS)

Bénézeth, Pascale; Berninger, Ulf-Niklas; Bovet, Nicolas; Schott, Jacques; Oelkers, Eric H.

2018-03-01

The 'dolomite problem', the scarcity of present-day dolomite formation near the Earth's surface, has attracted much attention over the past century. Solving this problem requires having reliable data on the stability and kinetics of formation of this mineral. Toward this goal, the solubility of natural dolomite (CaMg(CO3)2) has been measured from 50 to 253 °C in 0.1 mol/kg NaCl solutions using a hydrogen electrode concentration cell (HECC). The obtained apparent solubility products (Kapp-sp-dol), for the reaction: CaMg(CO3)2 = Ca2+ + Mg2+ + 2CO32-, were extrapolated to infinite dilution to generate the solubility product constants for this reaction (Ksp°-dol). The derived equilibrium constants were fit and can be accurately described by log10Ksp°-dol = a + b/T (K) + cT (K) where a = 17.502, b = -4220.119 and c = -0.0689. This equation and its first and second derivatives with respect to T were used together with corresponding aqueous species properties to calculate the revised standard state thermodynamic properties of dolomite at 25 °C and 1 bar, yielding a Gibbs energy of formation (Δf G298.15∘) equal to -2160.9 ± 2 kJ/mol, (log10Ksp°-dol = -17.19 ± 0.3); an enthalpy of formation (Δf H298.15∘) of -2323.1 ± 2 kJ/mol, an entropy (S298.15∘) of 156.9 ± 2 J/mol/K and heat capacity (Cp298.15∘) of 154.2 ± 2 J/mol/K (uncertainties are 3σ). The dolomite solubility product derived in this study is nearly identical to that computed using SUPCRT92 (Johnson et al., 1992) at 200 °C, but about one order of magnitude higher at 50 and 25 °C, suggesting that dolomite may be somewhat less stable than previously assumed at ambient temperatures.

The major mass movements of the Western Dolomites (Italy)

NASA Astrophysics Data System (ADS)

Ostermann, Marc; Gruber, Alfred

2014-05-01

Major gravitational slope deformations are widely disseminated in the Dolomite Mountains (NE-Italy), one of the world's most conspicuous landscapes and part of the UNESCO world heritage list. Because of their unique geological composition the Dolomites provide a natural laboratory where nearly all kind of mass wasting processes, in all dimensions, can be investigated. Simplified there are thick, rigid carbonatic successions (Triassic-Jurassic) resting on and interfingering with relatively weak successions of shallow marine clastic and of pelagic sediments. In some areas even volcanic successions and crystalline basement rocks are outcropped. Hugh rockslides and long run-out rock avalanches are limited to the carbonates and volcanic rocks. The superposition of Middle and Upper Triassic reefs, showing brittle deformation behaviour, above weak successions of evaporites, clays and marls, characterised by ductile deformation behaviour, leads to a classical "hard on soft" situation. The observable results are rockslides and rock avalanches of several hundred millions of m³ in volume, large scale rock toppling and rock flows and deep-seated gravitational slope deformations (DSGSD). Within the weak successions slow moving rotational landslides and large dimensional earthflows are very common. We focused our research on an area of about 40*40km within the Western and Northern Dolomites, where an inventory of the major gravitational mass movements has been compiled. We combined detailed geological maps with high resolution DEMs and extensive fieldwork data within a GIS-system. The different processes have been characterised and classified based on kinematic criteria, dimension and involved material. Altogether the database consists of 186 entries. Most frequently are landslides and earthflows (146) followed by catastrophic rockslides and rock avalanches (26) and DSGSDs (14). The spatial distribution of the mapped processes has been analysed in terms of the main

The soil biota composition along a progressive succession of secondary vegetation in a karst area.

PubMed

Zhao, Jie; Li, Shengping; He, Xunyang; Liu, Lu; Wang, Kelin

2014-01-01

Karst ecosystems are fragile and are in many regions degraded by anthropogenic activities. Current management of degraded karst areas focuses on aboveground vegetation succession or recovery and aims at establishing a forest ecosystem. Whether progressive succession of vegetation in karst areas is accompanied by establishment of soil biota is poorly understood. In the present study, soil microbial and nematode communities, as well as soil physico-chemical properties were studied along a progressive succession of secondary vegetation (from grassland to shrubland to forest) in a karst area in southwest China. Microbial biomass, nematode density, ratio of fungal to bacterial biomass, nematode structure index, and nematode enrichment index decreased with the secondary succession in the plant community. Overall, the results indicated a pattern of declines in soil biota abundance and food web complexity that was associated with a decrease in soil pH and a decrease in soil organic carbon content with the progressive secondary succession of the plant community. Our findings suggest that soil biota amendment is necessary during karst ecosystem restoration and establishment and management of grasslands may be feasible in karst areas.

Using enteric pathogens to assess sources of fecal contamination in the Silurian Dolomite Aquifer: Preliminary results

USGS Publications Warehouse

Muldoon, Maureen A; Borchardt, Mark A.; Spencer, Susan K.; Hunt, Randall J.; Owens, David

2018-01-01

The fractured Silurian dolomite aquifer is an important, but vulnerable, source of drinking water in northeast Wisconsin (Sherrill in Geology and ground water in Door County, Wisconsin, with emphasis on contamination potential in the Silurian dolomite, 1978; Bradbury and Muldoon in Hydrogeology and groundwater monitoring of fractured dolomite in the Upper Door Priority Watershed, Door County, Wisconsin, 1992; Muldoon and Bradbury in Assessing seasonal variations in recharge and water quality in the Silurian aquifer in areas with thicker soil cover. p 45, 2010). Areas underlain by the Silurian dolomite aquifer are extremely vulnerable to groundwater contamination from various land-use activities, especially the disposal of human wastewater and dairy manure. Currently there is no consensus as to which source of wastewater generates the greater impact to the aquifer.

Greenhouse conditions induce mineralogical changes and dolomite accumulation in coralline algae on tropical reefs

PubMed Central

Diaz-Pulido, Guillermo; Nash, Merinda C.; Anthony, Kenneth R.N.; Bender, Dorothea; Opdyke, Bradley N.; Reyes-Nivia, Catalina; Troitzsch, Ulrike

2014-01-01

Human-induced ocean acidification and warming alter seawater carbonate chemistry reducing the calcification of reef-building crustose coralline algae (CCA), which has implications for reef stability. However, due to the presence of multiple carbonate minerals with different solubilities in seawater, the algal mineralogical responses to changes in carbonate chemistry are poorly understood. Here we demonstrate a 200% increase in dolomite concentration in living CCA under greenhouse conditions of high pCO2 (1,225 μatm) and warming (30 °C). Aragonite, in contrast, increases with lower pCO2 (296 μatm) and low temperature (28 °C). Mineral changes in the surface pigmented skeleton are minor and dolomite and aragonite formation largely occurs in the white crust beneath. Dissolution of high-Mg-calcite and particularly the erosive activities of endolithic algae living inside skeletons play key roles in concentrating dolomite in greenhouse treatments. As oceans acidify and warm in the future, the relative abundance of dolomite in CCA will increase. PMID:24518160

Relationship among land surface temperature and LUCC, NDVI in typical karst area.

PubMed

Deng, Yuanhong; Wang, Shijie; Bai, Xiaoyong; Tian, Yichao; Wu, Luhua; Xiao, Jianyong; Chen, Fei; Qian, Qinghuan

2018-01-12

Land surface temperature (LST) can reflect the land surface water-heat exchange process comprehensively, which is considerably significant to the study of environmental change. However, research about LST in karst mountain areas with complex topography is scarce. Therefore, we retrieved the LST in a karst mountain area from Landsat 8 data and explored its relationships with LUCC and NDVI. The results showed that LST of the study area was noticeably affected by altitude and underlying surface type. In summer, abnormal high-temperature zones were observed in the study area, perhaps due to karst rocky desertification. LSTs among different land use types significantly differed with the highest in construction land and the lowest in woodland. The spatial distributions of NDVI and LST exhibited opposite patterns. Under the spatial combination of different land use types, the LST-NDVI feature space showed an obtuse-angled triangle shape and showed a negative linear correlation after removing water body data. In summary, the LST can be retrieved well by the atmospheric correction model from Landsat 8 data. Moreover, the LST of the karst mountain area is controlled by altitude, underlying surface type and aspect. This study provides a reference for land use planning, ecological environment restoration in karst areas.

Exploring the relationship between vegetation spectra and eco-geo-environmental conditions in karst region, Southwest China.

PubMed

Yue, Yuemin; Wang, Kelin; Zhang, Bing; Chen, Zhengchao; Jiao, Quanjun; Liu, Bo; Chen, Hongsong

2010-01-01

Remote sensing of local environmental conditions is not accessible if substrates are covered with vegetation. This study explored the relationship between vegetation spectra and karst eco-geo-environmental conditions. Hyperspectral remote sensing techniques showed that there were significant differences between spectral features of vegetation mainly distributed in karst and non-karst regions, and combination of 1,300- to 2,500-nm reflectance and 400- to 680-nm first-derivative spectra could delineate karst and non-karst vegetation groups. Canonical correspondence analysis (CCA) successfully assessed to what extent the variation of vegetation spectral features can be explained by associated eco-geo-environmental variables, and it was found that soil moisture and calcium carbonate contents had the most significant effects on vegetation spectral features in karst region. Our study indicates that vegetation spectra is tightly linked to eco-geo-environmental conditions and CCA is an effective means of studying the relationship between vegetation spectral features and eco-geo-environmental variables. Employing a combination of spectral and spatial analysis, it is anticipated that hyperspectral imagery can be used in interpreting or mapping eco-geo-environmental conditions covered with vegetation in karst region.

Reduction Behavior of Dolomite-Fluxed Magnetite: Coke Composite Pellets at 1573 K (1300 °C)

NASA Astrophysics Data System (ADS)

Park, Hyunsik; Sohn, Il; Tsalapatis, John; Sahajwalla, Veena

2018-06-01

High-temperature behavior of magnetite—coke composite pellet fluxed with dolomite was investigated by customized thermogravimetric analyzer (TGA) at 1573 K (1300 °C). The overall reaction was influenced by C/O ratio and dolomite content. The reduction was accelerated by increased amount of dolomite, while the samples with higher C/O ratio showed the improved reduction degree. X-ray diffraction (XRD) pattern of reduced pellet showed the phase changes of the iron oxides. Noticeable iron peaks were observed when the sample reached the final stage of reduction. CO and CO2 gases released from the reaction were measured by Infrared (IR) gas analyzer. Relation between enhanced reducibility of pellets and larger CO gas evolution from the Boudouard reaction was confirmed from the analysis. Compressive strengths were studied for the practical assessment of reduced pellets. Samples with low-reduction degree showed better physical property. Excessive amount of dolomite also deteriorated the integrity of pellets.

Karst geomorphology and hydrology of the Shenandoah Valley near Harrisonburg, Virginia

USGS Publications Warehouse

Doctor, Daniel H.; Orndorff, Wil; Maynard, Joel; Heller, Matthew J.; Casile, Gerolamo C.

2014-01-01

The karst of the central Shenandoah Valley has characteristics of both shallow and deep phreatic formation. This field guide focuses on the region around Harrisonburg, Virginia, where a number of these karst features and their associated geologic context can be examined. Ancient, widespread alluvial deposits cover much of the carbonate bedrock on the western side of the valley, where shallow karstification has resulted in classical fluviokarst development. However, in upland exposures of carbonate rock, isolated caves exist atop hills not affected by surface processes other than exposure during denudation. The upland caves contain phreatic deposits of calcite and fine-grained sediments. They lack any evidence of having been invaded by surface streams. Recent geologic mapping and LIDAR (light detection and ranging) elevation data have enabled interpretive association between bedrock structure, igneous intrusions, silicification and brecciation of host carbonate bedrock, and the location of several caves and karst springs. Geochemistry, water quality, and water temperature data support the broad categorization of springs into those affected primarily by shallow near-surface recharge, and those sourced deeper in the karst aquifer. The deep-seated karst formation occurred in the distant past where subvertical fracture and fault zones intersect thrust faults and/or cross-strike faults, enabling upwelling of deep-circulating meteoric groundwater. Most caves formed in such settings have been overprinted by later circulation of shallow groundwater, thus removing evidence of the history of earliest inception; however, several caves do preserve evidence of an earlier formation.

Natural and Artificial (fluorescent) Tracers to Characterise Hydrogeological Functioning and to Protect Karst Aquifers

NASA Astrophysics Data System (ADS)

Andreo, B.; Mudarra, M.; Marin, A. I.; Barberá, J. A.

2012-12-01

The hydrogeological functioning and response of karst aquifers can be determined by the joint use of natural hydrogeochemical tracers, especially total organic carbon (TOC) and intrinsic fluorescence of water, together with artificial (fluorescent) tracers, under the same hydrodynamic conditions. Sharp and rapid variations in discharge, temperature, electrical conductivity and water chemistry, particularly of natural tracers of infiltration (TOC, intrinsic fluorescence and NO3-) recorded in karst spring water, confirm the existence of well developed karst conduits in the sector of the aquifer being drained, with rapid flows and very short water transit times from the surface to the springs (Mudarra et al., 2011). This is in agreement with the evidence obtained from breakthrough curves of fluorescent dye tracers (uranine, eosine, etc.). However, time lags between maximum concentrations of natural (especially TOC and intrinsic fluorescence) and artificial tracers show that the global system response is faster than that produced from a recharge concentrated at a point on the surface, even in karst sinkholes. Response and transit times of water through the karst can be calculated using both natural and artificial tracers, but flow velocities can really only be quantified using artificial tracers. Analysis of the responses obtained by natural tracers of infiltration (global system response) and artificial tracers (single response) in karst waters has revealed the usefulness and complementarity of both techniques for characterising the hydrogeological functioning of karst aquifers and, even more important, for validating contamination vulnerability mapping in these medium (Zwahlen, 2004; Andreo et al., 2006). In recent decades, several methods have been developed for such vulnerability mapping, but little progress has been made in validating their results. This validation is essential for the adequate protection of water resources in karst media, as has been shown in

Development of a 3D GIS and its application to karst areas

NASA Astrophysics Data System (ADS)

Wu, Qiang; Xu, Hua; Zhou, Wanfang

2008-05-01

There is a growing interest in modeling and analyzing karst phenomena in three dimensions. This paper integrates geology, groundwater hydrology, geographic information system (GIS), database management system (DBMS), visualization and data mining to study karst features in Huaibei, China. The 3D geo-objects retrieved from the karst area are analyzed and mapped into different abstract levels. The spatial relationships among the objects are constructed by a dual-linker. The shapes of the 3D objects and the topological models with attributes are stored and maintained in the DBMS. Spatial analysis was then used to integrate the data in the DBMS and the 3D model to form a virtual reality (VR) to provide analytical functions such as distribution analysis, correlation query, and probability assessment. The research successfully implements 3D modeling and analyses in the karst area, and meanwhile provides an efficient tool for government policy-makers to set out restrictions on water resource development in the area.

Reconstructing conditions during dolomite formation on a Carnian coastal sabkha/alluvial plain using 87Sr/86Sr isotopes - Travenanzes Formation, northern Italy

NASA Astrophysics Data System (ADS)

Rieder, Maximilian; Wegner, Wencke; Horschinegg, Monika; Preto, Nereo; Breda, Anna; Klötzli, Urs; Peckmann, Jörn; Meister, Patrick

2016-04-01

The study of large amounts of dolomite that formed in the Triassic Tethyan realm is hampered by late diagenetic or hydrothermal overprint. These dolomites are difficult to link to past environmental and early diagenetic conditions, and their correlation to models for dolomite formation in modern environments is problematic. Preto et al. (2015) suggested, based on evidence from nano-scale structure analysis by transmission electron microscopy and petrographic observations, that dolomites in the Carnian Travenanzes Formation of the Southern Alps (Dolomites area) represent a preserved primary phase. The Travenanzes Formation was deposited in an extended alluvial plain or coastal sabkha environment subject to a semi-arid climate. Beds and nodules of nearly stoichiometric dolomite are embedded in large amounts of clay, which shielded early formed dolomite from diagenetic fluids. This finding of penecontemporaneous dolomite provides an ideal model case for reconstructing past environmental conditions at the time of dolomite precipitation. While Preto et al. (2015) argued that dolomite formation was mediated by extracellular polymeric substances produced by sulphate-reducing bacteria, it remains unclear whether precipitation occurred from evaporating seawater or mainly from brine derived from evaporating continental groundwater. Both cases exist in modern environments of dolomite formation. In the coastal sabkhas of Abu Dhabi and Qatar, dolomite precipitates from concentrated brine derived from seawater, either through seepage and reflux or through evaporative pumping (the sabkha model). In the coastal ephemeral lakes of the Coorong Lagoon system (South Australia) dolomite precipitation occurs from evaporating groundwater. The goal of this study is to distinguish marine from continental influence during formation of Carnian dolomite using 87Sr/86Sr isotope ratios. Sr isotopes could reveal different origins of ionic solutions for dolomite precipitation, which is not

Differentiated spring behavior under changing hydrological conditions in an alpine karst aquifer

NASA Astrophysics Data System (ADS)

Filippini, Maria; Squarzoni, Gabriela; De Waele, Jo; Fiorucci, Adriano; Vigna, Bartolomeo; Grillo, Barbara; Riva, Alberto; Rossetti, Stefano; Zini, Luca; Casagrande, Giacomo; Stumpp, Christine; Gargini, Alessandro

2018-01-01

Limestone massifs with a high density of dolines form important karst aquifers in most of the Alps, often with groundwater circulating through deep karst conduits and water coming out of closely spaced springs with flow rates of over some cubic meters per second. Although several hydrogeological studies and tracing experiments were carried out in many of these carbonate mountains in the past, the hydrogeology of most of these karst aquifers is still poorly known. Geological, hydrodynamic and hydrochemical investigations have been carried out in one of the most representative of these areas (Cansiglio-Monte Cavallo, NE Italy) since spring 2015, in order to enhance the knowledge on this important type of aquifer system. Additionally, a cave-to-spring multitracer test was carried out in late spring 2016 by using three different fluorescent tracers. This hydrogeological study allowed: 1) gathering new detailed information on the geological and tectonic structure of such alpine karst plateau; 2) defining discharge rates of the three main springs (Gorgazzo, Santissima, and Molinetto) by constructing rating curves; 3) understanding the discharging behavior of the system with respect to different recharge conditions; 4) better defining the recharge areas of the three springs. The three nearby springs (the spring front stretches over 5 km), that drain the investigated karst aquifer system, show different behaviors with respect to changing discharge conditions, demonstrating this aquifer to be divided in partially independent drainage systems under low-flow conditions, when their chemistry is clearly differentiated. Under high-flow conditions, waters discharging at all springs show more similar geochemical characteristics. The combination of geochemistry, hydrodynamic monitoring and dye tracing tests has shown that the three springs have different recharge areas. The study points out that even closely spaced karst springs, that apparently drain the same karst mountain, can

Drilling the Messinian Salinity Crisis as a Model Analogue for Dolomite Deposition at the End of Massive Salt Deposition Events

NASA Astrophysics Data System (ADS)

McKenzie, Judith A.; Aloisi, Giovanni; Anjos, Sylvia; Latgé, Ricardo; Matsuda, Nilo; Bontognali, Tomaso; Vasconcelos, Crisogono

2015-04-01

Sedimentologic and stratigraphic studies of the Lower Cretaceous sequence, deposited in the economically important Campos Basin, southeast Brazil, document the occurrence of ~20-m-thick dolomite intervals overlying the "massive salt" megasequences of the Lagoa Feia Formation. This stratigaphic succession marks the Aptian/Albian transition from extreme evaporitic conditions of the Lagoa Feia Formation to shallow marine conditions of the Macaé Formation, related to the early opening of the South Atlantic. The facies change from evaporites to dolomite is interpreted as a product of dolomitization resulting from the refuxing of hypersaline fluids from shallow embayments with intense evaporation (Latgé, 2001). Although the reflux model provides a mechanism to produce fluids with geochemical composition favorable for dolomite precipitation, it cannot account for all of the factors required to promote dolomite precipitation. In this study, we propose a different model to explain the post-evaporite deposition of massive dolomite based on the study of sequences deposited at the end Messinian Salinity Crisis, which were recovered from the deep basins of the Mediterranean Sea during DSDP/ODP drilling campaigns. At most of these deep-water sites, the cored interval contained unusual dolomite deposits overlying the uppermost evaporite sections. For example, the upper Messinian sedimentary sequence at DSDP Site 374 comprises non-fossiliferous dolomitic mudstone overlying dolomitic mudstone/gypsum cycles, which in turn overlie anhydrite and halite (Hsü, Montadert et al., 1978). We postulate that the end Messinian dolomite is a product of microbial activity under extreme hypersaline conditions. In the last 20 years, research into the factors controlling dolomite precipitation under Earth surface conditions has led to the development of new models involving the metabolism of microorganisms and associated biofilms to overcome the kinetic inhibitions associated with primary

A compact field fluorometer and its application to dye tracing in karst environments

NASA Astrophysics Data System (ADS)

Poulain, Amaël; Rochez, Gaëtan; Van Roy, Jean-Pierre; Dewaide, Lorraine; Hallet, Vincent; De Sadelaer, Geert

2017-08-01

Dye tracing is a classic technique in hydrogeology to investigate surface-water or groundwater flow characteristics, and it is useful for many applications including natural or industrial issues. The Fluo-Green field fluorometer has been successfully tested in a karst environment and is specifically suitable for in-cave karst water monitoring. Karst research often uses dyes to obtain information about groundwater flow in unexplored cave passages. The compact device, alternatively named Fluo-G, meets the requirements of cave media: small (10 × 16 × 21 cm), lightweight (0.75 kg without ballast) and simple in conception. It is easy for cavers to set up and handle compared to other sampling methods. The fluorometer records uranine, turbidity and temperature with a user-defined time-step (1 min - 1 day). Very low energy consumption allows 9,000 measurements with six AA batteries. The device was calibrated and tested in the laboratory and in field conditions in Belgian karst systems. Results are in good fit with other sampling methods: in-situ fluorometers and automatic water sampling plus laboratory analysis. Recording high quality data (breakthrough curves) in karst with in-cave monitoring is valuable to improve knowledge of karst systems. Many hydrological and hydrogeological applications can benefit from such a low-cost and compact device, and finding the best compromise between resources and quality data is essential. Several improvements are possible but preliminary field tests are very promising.

Natural hazards in Slovene karst areas: Flood risk areas in the Upper Pivka valley

NASA Astrophysics Data System (ADS)

Ravbar, N.; Kovacic, G.

2009-04-01

An overview of exceptional natural processes or natural hazards from the human perspective in Slovene karst areas is made. Some types of natural hazards are typical for karst due to the process of karstification and resulting geomorphological and hydrological characteristics of karst landscapes (presence of voids within the rock, absence of superficial flow and presence of specific karst groundwater flow system), while the others occur evenly in all types of landscapes. However, their impact is different in karst as it is in the non-karst landscapes. Examples of particular phenomenon or events, their frequency of occurrence, expansion and caused damage are presented. Special emphasis is laid on high waters in karst poljes, shallow karst areas or contact karst, where flooding emerges due to the raise of karst groundwater table as a consequence of intensive precipitation or snowmelt. Flooding in karst can also appear due to insufficient swallow capacities of the underground channels, which are not capable of conducting surpluses of inflowing water. In opposite to flash floods, the karst floods are more predictable, since they usually occur in the same areas to the same elevation and in the same season of the year. Inhabitants are easily adapted to this phenomenon, setting the settlements and other important infrastructure on elevations above the highest recorded water level. Usually such flooding does not pose serious threat and causes no serious flood damage, except during extreme events, as it was in the case of the autumn 2000 floods. Case study of the Upper Pivka valley, where floods usually cover around 6.6 km2, is treated and explained. During the intensive rain period from September to November 2000, the groundwater table rose for about 20-35 m above the usual level, causing flooding also in the areas, where they have never been recorded before. Precise mapping of the flooded area extents in the discussed area and the height of the water levels was performed

Leaf trait variations associated with habitat affinity of tropical karst tree species.

PubMed

Geekiyanage, Nalaka; Goodale, Uromi Manage; Cao, Kunfang; Kitajima, Kaoru

2018-01-01

Karst hills, that is, jagged topography created by dissolution of limestone and other soluble rocks, are distributed extensively in tropical forest regions, including southern parts of China. They are characterized by a sharp mosaic of water and nutrient availability, from exposed hilltops with poor soil development to valleys with occasional flooding, to which trees show species-specific distributions. Here we report the relationship of leaf functional traits to habitat preference of tropical karst trees. We described leaf traits of 19 tropical tree species in a seasonal karst rainforest in Guangxi Province, China, 12 species in situ and 13 ex situ in a non-karst arboretum, which served as a common garden, with six species sampled in both. We examined how the measured leaf traits differed in relation to species' habitat affinity and evaluated trait consistency between natural habitats vs . the arboretum. Leaf mass per area (LMA) and optical traits (light absorption and reflectance characteristics between 400 and 1,050 nm) showed significant associations with each other and habitats, with hilltop species showing high values of LMA and low values of photochemical reflectance index (PRI). For the six species sampled in both the karst forest and the arboretum, LMA, leaf dry matter content, stomatal density, and vein length per area showed inconsistent within-species variations, whereas some traits (stomatal pore index and lamina thickness) were similar between the two sites. In conclusion, trees specialized in exposed karst hilltops with little soils are characterized by thick leaves with high tissue density indicative of conservative resources use, and this trait syndrome could potentially be sensed remotely with PRI.

An Examination of the Application of Professional Reliance To Management of Karst Resources In British Columbia (Canada)

NASA Astrophysics Data System (ADS)

Ramsey, Carolyn L.; Griffiths, Paul A.

2010-05-01

British Columbia (BC), Canada's most ecologically diverse province, is home to some of the nation's finest karst resources. Many of these are in forested settings, and are often associated with special/unique natural attributes ranging from geomorphology to hydrology, biology and ecology. Karst management in BC forests was shaped initially by concerns for caves and their recreation management, but as of 1997 there was a significant shift to an ecosystem approach to management of karst and cave resources. This new management approach was supported in due course by standards and guidelines for karst assessment and management. The approach also recognized the inherently multidisciplinary nature of this type of work and the frequent need to engage professionals with specialized knowledge of karst, and its natural and cultural resource values. In 2004, the BC Government introduced the Forest and Range Practices Act, a new results-based regulatory framework for forest practices. Government orders made pursuant to regulations under the Act identify categories of karst terrain and associated resource features that must be protected from the potentially damaging effects of roadbuilding and road maintenance, timber harvesting, and silviculture activities. In support of a general shift toward more results-based regulation and "freedom to manage" forest resources, it was argued that the forestry sector and its professionals are qualified, and competent enough, to formulate strategies for protecting and managing forest resources (including karst) without as much government oversight. As a result, forest tenure holders and their professionals are now responsible for assessing protected categories of karst resource features and developing and applying appropriate forest practices for them. Where knowledge beyond the area of forest professionals' expertise is required, the knowledge gaps are to be addressed by hiring suitably qualified professional consultants for advice and

Using enteric pathogens to assess sources of fecal contamination in the silurian dolomite aquifer: preliminary results

USDA-ARS?s Scientific Manuscript database

The fractured Silurian dolomite aquifer is an important, but vulnerable, source of drinking water in northeast Wisconsin. Areas underlain by the Silurian dolomite aquifer are extremely vulnerable to groundwater contamination from various land-use activities, especially the disposal of human wastewat...

The Soil Biota Composition along a Progressive Succession of Secondary Vegetation in a Karst Area

PubMed Central

He, Xunyang; Liu, Lu; Wang, Kelin

2014-01-01

Karst ecosystems are fragile and are in many regions degraded by anthropogenic activities. Current management of degraded karst areas focuses on aboveground vegetation succession or recovery and aims at establishing a forest ecosystem. Whether progressive succession of vegetation in karst areas is accompanied by establishment of soil biota is poorly understood. In the present study, soil microbial and nematode communities, as well as soil physico-chemical properties were studied along a progressive succession of secondary vegetation (from grassland to shrubland to forest) in a karst area in southwest China. Microbial biomass, nematode density, ratio of fungal to bacterial biomass, nematode structure index, and nematode enrichment index decreased with the secondary succession in the plant community. Overall, the results indicated a pattern of declines in soil biota abundance and food web complexity that was associated with a decrease in soil pH and a decrease in soil organic carbon content with the progressive secondary succession of the plant community. Our findings suggest that soil biota amendment is necessary during karst ecosystem restoration and establishment and management of grasslands may be feasible in karst areas. PMID:25379741

Clumped isotope thermometry of calcite and dolomite in a contact metamorphic environment

NASA Astrophysics Data System (ADS)

Lloyd, Max K.; Eiler, John M.; Nabelek, Peter I.

2017-01-01

Clumped isotope compositions of slowly-cooled calcite and dolomite marbles record apparent equilibrium temperatures of roughly 150-200 °C and 300-350 °C, respectively. Because clumped isotope compositions are sensitive to the details of T-t path within these intervals, measurements of the Δ47 values of coexisting calcite and dolomite can place new constraints on thermal history of low-grade metamorphic rocks over a large portion of the upper crust (from ∼5 to ∼15 km depth). We studied the clumped isotope geochemistry of coexisting calcite and dolomite in marbles from the Notch Peak contact metamorphic aureole, Utah. Here, flat-lying limestones were intruded by a pluton, producing a regular, zoned metamorphic aureole. Calcite Δ47 temperatures are uniform, 156 ± 12 °C (2σ s.e.), across rocks varying from high-grade marbles that exceeded 500 °C to nominally unmetamorphosed limestones >5 km from the intrusion. This result appears to require that the temperature far from the pluton was close to this value; an ambient temperature just 20 °C lower would not have permitted substantial re-equilibration, and should have preserved depositional or early diagenetic Δ47 values several km from the pluton. Combining this result with depth constraints from overlying strata suggests the country rock here had an average regional geotherm of 22.3-27.4 °C/km from the late Jurassic Period until at least the middle Paleogene Period. Dolomite Δ47 in all samples above the talc + tremolite-in isograd record apparent equilibrium temperatures of 328-12+13 °C (1σ s.e.), consistent with the apparent equilibrium blocking temperature we expect for cooling from peak metamorphic conditions. At greater distances, dolomite Δ47 records temperatures of peak (anchi)metamorphism or pre-metamorphic diagenetic conditions. The interface between these domains is the location of the 330 °C isotherm associated with intrusion. Multiple-phase clumped isotope measurements are complemented by

Field Investigation and Modeling Development for Hydrological and Carbon Cycles in Southwest Karst Region of China

NASA Astrophysics Data System (ADS)

Hu, X. B.

2017-12-01

It is required to understanding water cycle and carbon cycle processes for water resource management and pollution prevention and global warming influence in southwest karst region of China. Lijiang river basin is selected as our study region. Interdisciplinary field and laboratory experiments with various technologies are conducted to characterize the karst aquifers in detail. Key processes in the karst water cycle and carbon cycle are determined. Based on the MODFLOW-CFP model, new watershed flow and carbon cycle models are developed coupled subsurface and surface water flow models. Our study focus on the karst springshed in Mao village, the mechanisms coupling carbon cycle and water cycle are explored. This study provides basic theory and simulation method for water resource management and groundwater pollution prevention in China karst region.

PLAY ANALYSIS AND DIGITAL PORTFOLIO OF MAJOR OIL RESERVOIRS IN THE PERMIAN BASIN: APPLICATION AND TRANSFER OF ADVANCED GEOLOGICAL AND ENGINEERING TECHNOLOGIES FOR INCREMENTAL PRODUCTION OPPORTUNITIES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shirley P. Dutton; Eugene M. Kim; Ronald F. Broadhead

2003-04-01

A play portfolio is being constructed for the Permian Basin in west Texas and southeast New Mexico, the largest petroleum-producing basin in the US. Approximately 1300 reservoirs in the Permian Basin have been identified as having cumulative production greater than 1 MMbbl of oil through 2000. Of these major reservoirs, approximately 1,000 are in Texas and 300 in New Mexico. On a preliminary basis, 32 geologic plays have been defined for Permian Basin oil reservoirs and assignment of each of the 1300 major reservoirs to a play has begun. The reservoirs are being mapped and compiled in a Geographic Informationmore » System (GIS) by play. Detailed studies of three reservoirs are in progress: Kelly-Snyder (SACROC unit) in the Pennsylvanian and Lower Permian Horseshoe Atoll Carbonate play, Fullerton in the Leonardian Restricted Platform Carbonate play, and Barnhart (Ellenburger) in the Ellenburger Selectively Dolomitized Ramp Carbonate play. For each of these detailed reservoir studies, technologies for further, economically viable exploitation are being investigated.« less

Reaction pathways towards the formation of dolomite-analogues at ambient conditions

NASA Astrophysics Data System (ADS)

Pimentel, Carlos; Pina, Carlos M.

2016-04-01

In this paper we present results of a study of the crystallisation behaviour of the dolomite-analogues norsethite and PbMg(CO3)2 at room temperature and atmospheric pressure. Whereas precipitation of norsethite was previously obtained by mixing solutions (Hood et al., 1974; Pimentel and Pina, 2014a,b), we report, for the first time, the synthesis of PbMg(CO3)2 by using the same method. The formation of both phases was promoted by ageing slurries for periods of time ranging from a few days (norsethite) up to 6 months (PbMg(CO3)2). The crystallisation of both norsethite and PbMg(CO3)2 occurs by sequences of dissolution-precipitation reactions involving several amorphous and crystalline precursor phases, which were identified and characterised by X-ray diffraction and scanning electron microscopy. Depending on the initial composition and Ba:Mg and Pb:Mg ratios in the slurries, different precursors and reaction kinetics were observed. This demonstrates the existence of different reaction pathways towards the formation of the investigated dolomite-analogues. Our experimental results provide new insights into the possible mechanisms of formation of dolomite and other double carbonates in nature.

Simulating flow in karst aquifers at laboratory and sub-regional scales using MODFLOW-CFP

NASA Astrophysics Data System (ADS)

Gallegos, Josue Jacob; Hu, Bill X.; Davis, Hal

2013-12-01

Groundwater flow in a well-developed karst aquifer dominantly occurs through bedding planes, fractures, conduits, and caves created by and/or enlarged by dissolution. Conventional groundwater modeling methods assume that groundwater flow is described by Darcian principles where primary porosity (i.e. matrix porosity) and laminar flow are dominant. However, in well-developed karst aquifers, the assumption of Darcian flow can be questionable. While Darcian flow generally occurs in the matrix portion of the karst aquifer, flow through conduits can be non-laminar where the relation between specific discharge and hydraulic gradient is non-linear. MODFLOW-CFP is a relatively new modeling program that accounts for non-laminar and laminar flow in pipes, like karst caves, within an aquifer. In this study, results from MODFLOW-CFP are compared to those from MODFLOW-2000/2005, a numerical code based on Darcy's law, to evaluate the accuracy that CFP can achieve when modeling flows in karst aquifers at laboratory and sub-regional (Woodville Karst Plain, Florida, USA) scales. In comparison with laboratory experiments, simulation results by MODFLOW-CFP are more accurate than MODFLOW 2005. At the sub-regional scale, MODFLOW-CFP was more accurate than MODFLOW-2000 for simulating field measurements of peak flow at one spring and total discharges at two springs for an observed storm event.

Paleozoic fluid history of the Michigan Basin: Evidence from dolomite geochemistry in the Middle Ordovician St. Peter Sandstone

DOE Office of Scientific and Technical Information (OSTI.GOV)

Winter, B.L.; Johnson, C.M.; Simo, J.A.

1995-04-03

The isotope (Sr and O) and elemental (Mg, Ca, Mn, Fe, and Sr) compositions of the various dolomites in the Middle Ordovician St. Peter Sandstone in the Michigan Basin are determined and the variations are modeled in terms of fluid-rock interaction or as mixing relations. These geochemical models, combined with the paragenetic sequence of the dolomites and late anhydrite cement, suggest the existence of at least four distinct diagenetic fluids in the St. Peter Sandstone during the paleozoic. Fluid 1 has a composition consistent with a modified older (pre-Middle Ordovician) seawater origin, which indicates that the flow path for thismore » fluid had a major upward component. This fluid resulted in the first and volumetrically most important burial dolomitization event, producing dolomite in both carbonate and quartz sandstone lithofacies in the St. Peter Sandstone. Fluid 2 has a composition consistent with a modified Middle to early Late Ordovician seawater origin, suggesting a major downward component for fluid flow. Fluid 2 produced dolomite cement in the carbonate lithofacies that postdates Fluid 1 dolomite. The composition of Fluid 3 is best interpreted to reflect a heated, deep basinal brine that had previously interacted with the K-feldspar-rich rocks near the Cambrian-Precambrian unconformity in the Michigan Basin, indicating a major upward component for fluid flow. Fluid 3 produced dolomite cement in quartz sandstone lithofacies that postdates Fluid 1 dolomite. Fluid 4 resulted in precipitation of late anhydrite in fractures. The {sup 87}Sr/{sup 86}Sr ratio of the anhydrite is consistent with Fluid 4 originating as a dilute fluid that interacted extensively with Silurian gypsum in the Michigan Basin; this indicates that the flow path of Fluid 4 had a major downward component.« less

Evaluating disturbance on mediterranean karst areas: the example of Sardinia (Italy)

NASA Astrophysics Data System (ADS)

de Waele, Jo

2009-07-01

Evaluating the human disturbance on karst areas is a difficult task because of the complexity of these peculiar and unique environments. The human impact on karstic geo-ecosystems is increasingly important and there is an increasing need for multidisciplinary tools to assess the environmental changes in karst areas. Many disciplines, such as biology, geomorphology, hydrology and social-economical sciences are to be considered to sufficiently evaluate the impact on these intrinsically vulnerable areas. This article gives an overview of the evolution of environmental impact on karst areas of the island Sardinia (Italy). For this particular case, the most important impacts in the past 50 years are derived from the following activities, in decreasing importance: (1) mining and quarrying; (2) deforestation, agriculture and grazing; (3) building (widespread urbanisation, isolated homes, etc.) and related infrastructures (roads, sewer systems, aqueducts, waste dumps, etc.); (4) tourism; (5) military activities. To evaluate the present environmental state of these areas the Disturbance Index for Karst environments [Van Beynen and Townsend (Environ Manage 36:101-116)] is applied in a slightly modified version. Instead of considering the indicators of environmental disturbances used in the original method, this slightly modified index evaluates the disturbances causing the deterioration of the environmental attributes. In the Sardinian case study, 27 disturbances have been evaluated, giving rise to the definition of a Disturbance Index ranging between 0 (Pristine) and 1 (highly disturbed). This Disturbance Index simplifies the original KDI method, appears to adequately measure disturbance on Mediterranean karst areas and could be applied with success to other similar regions.

Variations of the spatiotemporal patterns of CVOCs concentrations in northern karst of Puerto Rico

NASA Astrophysics Data System (ADS)

Yu, X.; Ghasemizadeh, R.; Padilla, I. Y.; Irizarry, C.; Yegen, C.; Kaeli, D.; Alshawabkeh, A. N.

2013-12-01

The northern Puerto Rico is characterized as karst topography, where the groundwater is a major source of water use to the island. Various types of Chlorinated Volatile Organic Compounds (CVOCs), which are due to improper disposal of industrial waste, are detected in these karst aquifers. It is important to study the spatiotemporal distribution patterns of the CVOCs in this region, which are posing a serious threat to both the ecological and human health. In this study, various historical CVOCs data from 264 wells across the northern karst region from January 1982 to December 2000 were collected from a number of reports and studies. We found that 38% (99 out of 264) of the sites had at least one sample with CVOC concentration above the standards established to protect human health over the study period. We found that the distribution of the CVOCs spatially varied with areas containing clusters of sites contaminated by different organic compound. The response of CVOC concentrations were occasionally retarded even though they were depleted significantly in the source zones. The study confirmed that the measured CVOC concentrations decreased during the study period at most of the sites. The source origin (toxics release locations and quantities) and the intrinsic characteristics of the karst (high heterogeneity and complex hydraulic behavior) are most likely related with the spatial and temporal distribution patterns of CVOCs. The study of the spatiotemporal patterns of CVOCs concentrations in the northern karst aquifers has important implications on the public water use, especially when it coincides with the recent population growth in this region. Locations of Puerto Rico, the northern karst region of Puerto Rico and 264 sampling sites in the karst region.

Paleoenvironmental and paleohydrochemical conditions of dolomite formation within a saline wetland in arid northwest Australia

NASA Astrophysics Data System (ADS)

Mather, Caroline C.; Skrzypek, Grzegorz; Dogramaci, Shawan; Grierson, Pauline F.

2018-04-01

Groundwater dolocrete occurring within the Fortescue Marsh, a large inland wetland in the Pilbara region of northwest Australia, has been investigated to provide paleoenvironmental and paleohydrological records and further the understanding of low temperature dolomite formation in terrestrial settings over the Quaternary Period. Two major phases of groundwater dolocrete formation are apparent from the presence of two distinct units of dolocrete, based on differences in depth, δ18O values and mineral composition. Group 1 (G1) occurs at depth 20-65 m b.g.l. (below ground level) and contains stoichiometric dolomite with δ18O values of -4.02-0.71‰. Group 2 (G2) is shallower (0-23 m b.g.l.), occurring close to the current groundwater level, and contains Ca-rich dolomite ± secondary calcite with a comparatively lower range of δ18O values (-7.74 and -6.03‰). Modelled δ18O values of paleogroundwater from which older G1 dolomite precipitated indicated highly saline source water, which had similar stable oxygen isotope compositions to relatively old brine groundwater within the Marsh, developed under a different hydroclimatic regime. The higher δ18O values suggest highly evaporitic conditions occurred at the Marsh, which may have been a playa lake to saline mud flat environment. In contrast, G2 dolomite precipitated from comparatively fresher water, and modelled δ18O values suggested formation from mixing between inflowing fresher groundwater with saline-brine groundwater within the Marsh. The δ18O values of the calcite indicates formation from brackish to saline groundwater, which suggests this process may be associated with coeval gypsum dissolution. In contrast to the modern hydrology of the Marsh, which is surface water dependent and driven by a flood and drought regime, past conditions conducive to dolomite precipitation suggest a groundwater dependent system, where shallow groundwaters were influenced by intensive evaporation.

Pesticides and biocides in a karst catchment: Identification of contaminant sources and related flow components

NASA Astrophysics Data System (ADS)

Wagner, Thomas; Bollmann, Ulla E.; Bester, Kai; Birk, Steffen

2013-04-01

Karst aquifers are widely used as drinking water resources. However, their high vulnerability to chemical and bacterial contamination due to the heterogeneity in aquifer properties (highly conductive solution conduits embedded in the less conductive fissured rock) is difficult to assess and thus poses major challenges to the management of karst water resources. Contamination of karst springs by organic micro-pollutants has been observed in recent studies. Within this study the water from different springs draining one karst aquifer as well as the main sinking stream replenishing it were analysed before, during and after a storm water event in order to examine the occurrence of different pesticides and biocides. Contaminants from both urban as well as agricultural origin could be detected in the water with concentrations in the low ng/L range (tebuconazole, carbendazim, diuron, isoproturon, terbutryn, atrazine, dichlorobenzamide (BAM), which is a metabolite of dichlobenil). While some compounds could be followed from the sinking stream to the springs (e.g. dichlorobenzamide) some seem to have a source in the autogenic recharge from the karst plateau (Tebuconazole: wood preservative in buildings). These compounds appear to be related to fast flow components with residence times in the order of days, which are known from a number of tracer tests with fluorescent dyes. However, the occurrence of the pesticide atrazine (banned since 1995 in Austria) in the springs, while on the other hand no current input into the karst occurs, shows that some compounds have long residence times in the karst aquifer. These differences in residence times can hardly be attributed to differences in physico-chemical properties of the compounds and must thus be due to the presence of slow and fast flow components. This is in agreement with the duality of karst aquifers due to highly conductive networks of solution conduits embedded in less conductive fissured carbonate rocks.

Early diagenetic dolomitization and dedolomitization of Late Jurassic and earliest Cretaceous platform carbonates: A case study from the Jura Mountains (NW Switzerland, E France)

NASA Astrophysics Data System (ADS)

Rameil, Niels

2008-12-01

Early diagenetic dolomitization is a common feature in cyclic shallow-water carbonates throughout the geologic record. After their generation, dolomites may be subject to dedolomitization (re-calcification of dolomites), e.g. by contact with meteoric water during emersion. These patterns of dolomitization and subsequent dedolomitization frequently play a key role in unravelling the development and history of a carbonate platform. On the basis of excellent outcrops, detailed logging and sampling and integrating sedimentological work, high-resolution sequence stratigraphic interpretations, and isotope analyses (O, C), conceptual models on early diagenetic dolomitization and dedolomitization and their underlying mechanisms were developed for the Upper Jurassic / Lower Cretaceous Jura platform in north-western Switzerland and eastern France. Three different types of early diagenetic dolomites and two types of dedolomites were observed. Each is defined by a distinct petrographic/isotopic signature and a distinct spatial distribution pattern. Different types of dolomites are interpreted to have been formed by different mechanisms, such as shallow seepage reflux, evaporation on tidal flats, and microbially mediated selective dolomitization of burrows. Depending on the type of dolomite, sea water with normal marine to slightly enhanced salinities is proposed as dolomitizing fluid. Based on the data obtained, the main volume of dolomite was precipitated by a reflux mechanism that was switched on and off by high-frequency sea-level changes. It appears, however, that more than one dolomitization mechanism was active (pene)contemporaneously or several processes alternated in time. During early diagenesis, percolating meteoric waters obviously played an important role in the dedolomitization of carbonate rocks that underlie exposure surfaces. Cyclostratigraphic interpretation of the sedimentary succession allows for estimates on the timing of early diagenetic (de)dolomitization

Hydrogen sulfide capture by limestone and dolomite at elevated pressure. 2: Sorbent particle conversion modeling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zevenhoven, C.A.P.; Yrjas, K.P.; Hupa, M.M.

1996-03-01

The physical structure of a limestone or dolomite to be used in in-bed sulfur capture in fluidized bed gasifiers has a great impact on the efficiency of sulfur capture and sorbent use. In this study an unreacted shrinking core model with variable effective diffusivity is applied to sulfidation test data from a pressurized thermogravimetric apparatus (P-TGA) for a set of physically and chemically different limestone and dolomite samples. The particle size was 250--300 {micro}m for all sorbents, which were characterized by chemical composition analysis, particle density measurement, mercury porosimetry, and BET internal surface measurement. Tests were done under typical conditionsmore » for a pressurized fluidized-bed gasifier, i.e., 20% CO{sub 2}, 950 C, 20 bar. At these conditions the limestone remains uncalcined, while the dolomite is half-calcined. Additional tests were done at low CO{sub 2} partial pressures, yielding calcined limestone and fully calcined dolomite. The generalized model allows for determination of values for the initial reaction rate and product layer diffusivity.« less

Origin of dolomite in Miocene Monterey Shale and related formations in the Temblor Range, California

USGS Publications Warehouse

Friedman, I.; Murata, K.J.

1979-01-01

Dolomites in thick sections of Miocene Monterey Shale and related formations in the Temblor Range of California acquired their isotopic compositions as they formed at shallow depth in the original sediment rich in organic matter, and retained the composition against the vicissitudes of burial diagenesis. The oxygen isotopes of dolomites of successive beds record changes in temperature of bottom water while the carbon isotopes of the same samples indicate changes in the kind of microbial activity (sulfate reduction vs carbohydrate fermentation) that prevailed at shallow depths in the sediment. In an auxiliary study, two samples of dolomite from sediments of Cariaco Basin off Venezuela (DSDP site 147) were found to have ??5C13 of -14.1 and -9.8 per ml PDB, although they occur in a heavy-carbon zone containing bicarbonate as heavy as +8.4 per ml. These dolomites probably originated at shallow depth in the light-carbon zone of microbial sulfate reducers and were buried under later sediments down into the heavy-carbon zone of microbial fermenters of carbohydrates without losing their original light-carbon composition. ?? 1979.

INTERIOR VIEW, NORTH QUARRY, AN ACTIVE DOLOMITE QUARRY, LOOKING NORTH ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

INTERIOR VIEW, NORTH QUARRY, AN ACTIVE DOLOMITE QUARRY, LOOKING NORTH TO THE POWER PLANT OF THE HISTORIC THOMAS COKEWORKS SITE. - Wade Sand & Gravel Company, North Quarry, State Highway 78, Thomas, Jefferson County, AL

Integrated approach for quantification of fractured tight reservoir rocks: Porosity, permeability analyses and 3D fracture network characterisation on fractured dolomite samples

NASA Astrophysics Data System (ADS)

Voorn, Maarten; Barnhoorn, Auke; Exner, Ulrike; Baud, Patrick; Reuschlé, Thierry

2015-04-01

Fractured reservoir rocks make up an important part of the hydrocarbon reservoirs worldwide. A detailed analysis of fractures and fracture networks in reservoir rock samples is thus essential to determine the potential of these fractured reservoirs. However, common analyses on drill core and plug samples taken from such reservoirs (including hand specimen analysis, thin section analysis and laboratory porosity and permeability determination) suffer from various problems, such as having a limited resolution, providing only 2D and no internal structure information, being destructive on the samples and/or not being representative for full fracture networks. In this study, we therefore explore the use of an additional method - non-destructive 3D X-ray micro-Computed Tomography (μCT) - to obtain more information on such fractured samples. Seven plug-sized samples were selected from narrowly fractured rocks of the Hauptdolomit formation, taken from wellbores in the Vienna Basin, Austria. These samples span a range of different fault rocks in a fault zone interpretation, from damage zone to fault core. 3D μCT data is used to extract porosity, fracture aperture, fracture density and fracture orientations - in bulk as well as locally. The 3D analyses are complemented with thin sections made to provide some 2D information with a much higher detail than the μCT data. Finally, gas- and water permeability measurements under confining pressure provide an important link (at least in order of magnitude) of the µCT results towards more realistic reservoir conditions. Our results show that 3D μCT can be applied efficiently on plug-sized samples of naturally fractured rocks, and that several important parameters can be extracted. μCT can therefore be a useful addition to studies on such reservoir rocks, and provide valuable input for modelling and simulations. Also permeability experiments under confining pressure provide important additional insights. Combining these and other

Laboratory analog and numerical study of groundwater flow and solute transport in a karst aquifer with conduit and matrix domains.

PubMed

Faulkner, Jonathan; Hu, Bill X; Kish, Stephen; Hua, Fei

2009-11-03

New mathematical and laboratory methods have been developed for simulating groundwater flow and solute transport in karst aquifers having conduits imbedded in a porous medium, such as limestone. The Stokes equations are used to model the flow in the conduits and the Darcy equation is used for the flow in the matrix. The Beavers-Joseph interface boundary conditions are adopted to describe the flow exchange at the interface boundary between the two domains. A laboratory analog is used to simulate the conduit and matrix domains of a karst aquifer. The conduit domain is located at the bottom of the transparent plexiglas laboratory analog and glass beads occupy the remaining space to represent the matrix domain. Water flows into and out of the two domains separately and each has its own supply and outflow reservoirs. Water and solute are exchanged through an interface between the two domains. Pressure transducers located within the matrix and conduit domains of the analog provide data that is processed and stored in digital format. Dye tracing experiments are recorded using time-lapse imaging. The data and images produced are analyzed by a spatial analysis program. The experiments provide not only hydraulic head distribution but also capture solute front images and mass exchange measurements between the conduit and matrix domains. In the experiment, we measure and record pressures, and quantify flow rates and solute transport. The results present a plausible argument that laboratory analogs can characterize groundwater water flow, solute transport, and mass exchange between the conduit and matrix domains in a karst aquifer. The analog validates the predictions of a numerical model and demonstrates the need of laboratory analogs to provide verification of proposed theories and the calibration of mathematical models.

Facies analysis of an Upper Jurassic carbonate platform for geothermal reservoir characterization

NASA Astrophysics Data System (ADS)

von Hartmann, Hartwig; Buness, Hermann; Dussel, Michael

2017-04-01

The Upper Jurassic Carbonate platform in Southern Germany is an important aquifer for the production of geothermal energy. Several successful projects were realized during the last years. 3D-seismic surveying has been established as a standard method for reservoir analysis and the definition of well paths. A project funded by the federal ministry of economic affairs and energy (BMWi) started in 2015 is a milestone for an exclusively regenerative heat energy supply of Munich. A 3D-seismic survey of 170 square kilometer was acquired and a scientific program was established to analyze the facies distribution within the area (http://www.liag-hannover.de/en/fsp/ge/geoparamol.html). Targets are primarily fault zones where one expect higher flow rates than within the undisturbed carbonate sediments. However, since a dense net of geothermal plants and wells will not always find appropriate fault areas, the reservoir properties should be analyzed in more detail, e.g. changing the viewpoint to karst features and facies distribution. Actual facies interpretation concepts are based on the alternation of massif and layered carbonates. Because of successive erosion of the ancient land surfaces, the interpretation of reefs, being an important target, is often difficult. We found that seismic sequence stratigraphy can explain the distribution of seismic pattern and improves the analysis of different facies. We supported this method by applying wavelet transformation of seismic data. The splitting of the seismic signal into successive parts of different bandwidths, especially the frequency content of the seismic signal, changed by tuning or dispersion, is extracted. The combination of different frequencies reveals a partition of the platform laterally as well as vertically. A cluster analysis of the wavelet coefficients further improves this picture. The interpretation shows a division into ramp, inner platform and trough, which were shifted locally and overprinted in time by other

The newest findings on Red Lake (Dinaric karst of Croatia)

NASA Astrophysics Data System (ADS)

Andrić, Ivo; Jukić, Branimir

2014-05-01

Red Lake in the Dinaric karst (Croatia) is of the deepest karst lakes in the world. Even so, through the history of Red Lake's research there were many controversies in the conclusions and the theories concerning its genesis, geomorphology and hydrology. This work has for a goal to present the newest research results won with the help of emerging technologies based on LiDAR and SoNAR methods. The measurements took place during September 2013. New generation of equipment developed to advance the geoscientific research has been deployed during the field work and the gathered data enabled the analysis which led to a new understanding of the lake's morphology. Some of the results confirmed already known and well documented features of Red Lake whereas others disputed widely accepted assumptions in the scientific community and general public. The objective of this paper is also groundwork for further research in the field of karst hydrology and a new insight on local and regional scale.

Evaluation of karst water quality as an early reference of land suitability mapping for vaname shrimp (Litopenaeusvannamei) culture media

NASA Astrophysics Data System (ADS)

Wildan, D. M.; Affandi, R.; Pratiwi, N. T. M.; Krisanti, M.; Ayu, I. P.; Iswantari, A.

2017-01-01

Vaname shrimp (Litopenaeusvannamei) is one of the excellent fishery commodities in Indonesia. Vaname shrimp farming can be conducted in low salinity water. Low salinity water sources which could be used as culture media is karst water because it has a high mineral. The research was aimedto evaluate land suitability mapping for pond as the vaname shrimpculture mediaseen from the water quality. Research was conducted in May and August 2016. Water sampling was conducted in several locations; Ancol-Jakarta (seawater), Ciseeng-Bogor (karst water salinity), Ciampea-Bogor (karst freshwater), and Situ Gede Bogor (freshwater). Evaluating the suitability of karst water quality for vaname shrimp culture media, done by the results of karst water quality analysis compared with seawater and SNI 01-7246-2006 on shrimp vaname culture media. The results showed that Karst water of Ciseeng and Ciampea could not directly use as vaname shrimp culture media. It is needed water quality treatment of ozonation and aeration of karst water to improve water quality. Ozonation and aeration treatments were able to improve the quality of karst water up to approach the living quality standard of vaname shrimp media.

Organic Carbon Storage in Four Ecosystem Types in the Karst Region of Southwestern China

PubMed Central

Wang, Shijie; Guo, Ke; Yang, Jun; Zhang, Xinshi; Li, Guoqing

2013-01-01

Karst ecosystems are important landscape types that cover about 12% of the world's land area. The role of karst ecosystems in the global carbon cycle remains unclear, due to the lack of an appropriate method for determining the thickness of the solum, a representative sampling of the soil and data of organic carbon stocks at the ecosystem level. The karst region in southwestern China is the largest in the world. In this study, we estimated biomass, soil quantity and ecosystem organic carbon stocks in four vegetation types typical of karst ecosystems in this region, shrub grasslands (SG), thorn shrubbery (TS), forest - shrub transition (FS) and secondary forest (F). The results showed that the biomass of SG, TS, FS, and F is 0.52, 0.85, 5.9 and 19.2 kg m−2, respectively and the corresponding organic cabon storage is 0.26, 0.40, 2.83 and 9.09 kg m−2, respectively. Nevertheless, soil quantity and corresponding organic carbon storage are very small in karst habitats. The quantity of fine earth overlaying the physical weathering zone of the carbonate rock of SG, TS, FS and F is 38.10, 99.24, 29.57 and 61.89 kg m−2, respectively, while the corresponding organic carbon storage is only 3.34, 4.10, 2.37, 5.25 kg m−2, respectively. As a whole, ecosystem organic carbon storage of SG, TS, FS, and F is 3.81, 4.72, 5.68 and 15.1 kg m−2, respectively. These are very low levels compared to other ecosystems in non-karst areas. With the restoration of degraded vegetation, karst ecosystems in southwestern China may play active roles in mitigating the increasing CO2 concentration in the atmosphere. PMID:23451047

Use of chemical and isotopic tracers to assess nitrate contamination and ground-water age, Woodville Karst Plain, USA

USGS Publications Warehouse

Katz, B.G.; Chelette, A.R.; Pratt, T.R.

2004-01-01

Concerns regarding ground-water contamination in the Woodville Karst Plain have arisen due to a steady increase in nitrate-N concentrations (0.25-0.90 mg/l) during the past 30 years in Wakulla Springs, a large regional discharge point for water (9.6 m3/s) from the Upper Floridan aquifer (UFA). Multiple isotopic and chemical tracers were used with geochemical and lumped-parameter models (exponential mixing (EM), dispersion, and combined exponential piston flow) to assess: (1) the sources and extent of nitrate contamination of ground water and springs, and (2) mean transit times (ages) of ground water. Delta 15N-NO3 values (1.7-13.8???) indicated that nitrate in ground water originated from localized sources of inorganic fertilizer and human/animal wastes. Nitrate in spring waters (??15N-NO3=5.3-8.9???) originated from both inorganic and organic N sources. Nitrate-N concentrations (1.0 mg/l) were associated with shallow wells (open intervals less than 15 m below land surface), elevated nitrate concentrations in deeper wells are consistent with mixtures of water from shallow and deep zones in the UFA as indicated from geochemical mixing models and the distribution of mean transit times (5-90 years) estimated using lumped-parameter flow models. Ground water with mean transit times of 10 years or less tended to have higher dissolved organic carbon concentrations, lower dissolved solids, and lower calcite saturation indices than older waters, indicating mixing with nearby surface water that directly recharges the aquifer through sinkholes. Significantly higher values of pH, magnesium, dolomite saturation index, and phosphate in springs and deep water (>45 m) relative to a shallow zone (<45 m) were associated with longer ground-water transit times (50-90 years). Chemical differences with depth in the aquifer result from deep regional flow of water recharged through low permeability sediments (clays and clayey sands of the Hawthorn Formation) that overlie the UFA

Effect of brine salinity and guar gum on the transport of barium through dolomite rocks: Implications for unconventional oil and gas wastewater disposal.

PubMed

Ebrahimi, Pouyan; Vilcáez, Javier

2018-05-15

This research aimed to elucidate the effect of brine salinity and guar gum on the sorption and transport of Ba in dolomite rocks collected from the Arbuckle formation in Oklahoma, USA. Guar gum represents the most important organic additive used in viscosified fracturing fluids, and Ba constitutes the most common and abundant heavy metal found in unconventional oil and gas (UOG) wastewater. Batch experiments conducted using powdered dolomite rocks (500-600 μm particle size) revealed that at brine salinities of UOG wastewater, chloro-complexation reactions between Ba and Cl ions and pH changes that results from dolomite dissolution are the controlling factors of Ba sorption on dolomite. Competition of Ba with common cations (Ca and Mg) for hydration sites of dolomite, plays a secondary role. Core-flooding experiments conducted to analyze the transport of Ba through natural and synthetic dolomite core plugs are in agreement with the batch sorption experimental results. The transport of Ba through dolomite rocks, increases with increasing brine salinity (0-180,000 mg-NaCl/L). The presence guar gum (50-500 mg/L) does not affect the transport of Ba through dolomite rocks of high flow properties (25-29.6% porosity, 9.6-13.7 mD permeability). However, core-flooding experiments conducted using tight dolomite rocks (6.5-8.6% porosity, 0.06-0.3 mD permeability), revealed that guar gum can retard the transport of Ba by clogging high permeability/porosity regions of tight dolomite rocks. The mechanism of Ba sorption on dolomite can be represented by a sorption model that accounts for both surface complexation reactions on three distinct hydration sites (>CaOH o , >MgOH o , and >CO 3 H o ), and the kinetic dissolution of dolomite. These results are important in understanding and predicting the fate of Ba present in UOG wastewater disposed into deep dolomite saline aquifers. Copyright © 2018 Elsevier Ltd. All rights reserved.

Trace element mobility in dolomitic argillites of the Mesoproterozoic Belt-Purcell Supergroup, Western North America

NASA Astrophysics Data System (ADS)

González-Álvarez, Ignacio; Kerrich, Robert

2011-04-01

The Belt-Purcell Supergroup comprises dolomite-rich stratigraphic units in a dominantly siliciclastic succession, where sedimentation spans 1400-1470 Ma. Dolomitic units are variable mixtures of co-sedimented argillite and primary carbonate post-depositionally converted to secondary dolomite. Based on rare earth element (REE) relationships three distinct REE patterns are identified in the dolomite-rich units: Type 1 (T1d; d = dolomitic sample) with REE patterns parallel to post-Archean Upper Continental Crust (PA-UCC), albeit at lower absolute abundances due to dilution by carbonate content; Type 2 (T2d) with Heavy REE (HREE) enrichment but Light REE (LREE) depletion relative to T1d; and Type 3 (T3d) with enrichment in LREE and HREE relative to T1d, but erratic Middle REE (MREE) patterns. There is a progressive increase of ΣREE from T1d through T2d to T3d, whereas for ΣLREE/ΣHREE T2d < T1d < T3d. T1d-T2d and T3d represent three different "snapshots" of a continuous process. In terms of timing, dolomitization of calcite primary sediment in all samples likely took place broadly during burial diagenesis, as inferred for most Proterozoic dolomites. T1d is easily explained by provenance: however, T2d and T3d cannot be related to provenance, weathering or sedimentary sorting processes to explain higher concentrations of HREE referenced to PA-UCC and consequently developed in the sediment from a T1d precursor. The same three REE signatures have been described in previous studies in counterpart siliciclastic counterparts throughout the Belt-Purcell Supergroup at three different locations. Mobility of normally stable REE is accompanied by mobility of normally isochemical high field strength elements (HFSE) in T2d and T3d to give REE/REE, HFSE/HFSE, REE/HFSE and Y/HREE fractionations. No specific REE-HFSE signatures are apparent in the carbonate-rich units as compared to their non-dolomitic siliciclastic counterparts. This unusual mobility of REE and HFSE reflected in T2d

Research on Evaluation and Control of Karst Water Resources in a Certain Tunnel of Dalian Subway

NASA Astrophysics Data System (ADS)

Wang, Guang Qiang

2018-05-01

Taking a certain tunnel in Dalian Metro as the research object, to evaluate the situation of karst development through geophysical prospecting and drilling data in study area. Karst water resources can be evaluated by quality and quantity in the study area, the correlation of the ion content can be analyzed according to the analysis results of chemical composition of groundwater and the maximum water inflow in karst water section tunnel can be calculated by using the Oshima Yoshi formula. Put forward measures and methods of groundwater control and tube well dewatering based on these evaluation, it has certain guiding significance for tunnel construction in karst area.

Selected Micropollutants as Indicators in a Karst Catchment

NASA Astrophysics Data System (ADS)

Zirlewagen, Johannes; Schiperski, Ferry; Hillebrand, Olav; Nödler, Karsten; Licha, Tobias; Scheytt, Traugott

2015-04-01

High flow dynamics and variations in water quality are typical for karst springs and reflect the complex interaction of different flow and storage components within a karst system. Event-based monitoring of mobile micropollutants in spring water combined with information on their input is used (1) to quantify the impact of certain contamination scenarios on spring water quality and (2) to gain additional information on the intrinsic characteristics of a karst system. We employ the artificial sweeteners acesulfame and cyclamate as source specific indicators for sewage along with the herbicides atrazine and isoproturon for agriculture. The study site is the 45 km² rural catchment of the perennial karst spring Gallusquelle in SW-Germany (mean discharge: 0.5 m³/s). Overflow events of a stormwater detention basin (SDB, combined sewer system) are known to impact water quality. Most of the sewer system is situated in the SW of the catchment. Most agricultural land is found in the NE. Neither atrazine nor significant amounts of isoproturon were detected in wastewater. Concentrations and mass fluxes of acesulfame and cyclamate in wastewater were determined. The combined evaluation of the persistent compound acesulfame with the rather degradable cyclamate allows for the distinction of long and short transit times and thus slow and fast flow components. The same applies for atrazine (persistent) and isoproturon (degradable). In Germany, acesulfame was licensed in 1990, atrazine was banned shortly after, in 1991. During low flow conditions only atrazine (max. 4 ng/L) and acesulfame (max. 20 ng/L) were detected in spring water. After a recharge event without SDB overflow concentrations as well as mass fluxes of both compounds decreased, reflecting an increasing portion of event water in spring discharge. A breakthrough of isoproturon (max. 9 ng/L) indicated the arrival of water from croplands. After a recharge event accompanied by a SDB overflow cyclamate was detected at max

Evaluation of subsidence hazard in mantled karst setting: a case study from Val d'Orléans (France)

NASA Astrophysics Data System (ADS)

Perrin, Jérôme; Cartannaz, Charles; Noury, Gildas; Vanoudheusden, Emilie

2015-04-01

Soil subsidence/collapse is a major geohazard occurring in karst region. It occurs as suffosion or dropout sinkholes developing in the soft cover. Less frequently it corresponds to a breakdown of karst void ceiling (i.e., collapse sinkhole). This hazard can cause significant engineering challenges. Therefore decision-makers require the elaboration of methodologies for reliable predictions of such hazards (e.g., karst subsidence susceptibility and hazards maps, early-warning monitoring systems). A methodological framework was developed to evaluate relevant conditioning factors favouring subsidence (Perrin et al. submitted) and then to combine these factors to produce karst subsidence susceptibility maps. This approach was applied to a mantled karst area south of Paris (Val d'Orléans). Results show the significant roles of the overburden lithology (presence/absence of low-permeability layer) and of the karst aquifer piezometric surface position within the overburden. In parallel, an experimental site has been setup to improve the understanding of key processes leading to subsidence/collapse and includes piezometers for measurements of water levels and physico-chemical parameters in both the alluvial and karst aquifers as well as surface deformation monitoring. Results should help in designing monitoring systems to anticipate occurrence of subsidence/collapse. Perrin J., Cartannaz C., Noury G., Vanoudheusden E. 2015. A multicriteria approach to karst subsidence hazard mapping supported by Weights-of-Evidence analysis. Submitted to Engineering Geology.

A Compilation of Provisional Karst Geospatial Data for the Interior Low Plateaus Physiographic Region, Central United States

USGS Publications Warehouse

Taylor, Charles J.; Nelson, Hugh L.

2008-01-01

Geospatial data needed to visualize and evaluate the hydrogeologic framework and distribution of karst features in the Interior Low Plateaus physiographic region of the central United States were compiled during 2004-2007 as part of the Ground-Water Resources Program Karst Hydrology Initiative (KHI) project. Because of the potential usefulness to environmental and water-resources regulators, private consultants, academic researchers, and others, the geospatial data files created during the KHI project are being made available to the public as a provisional regional karst dataset. To enhance accessibility and visualization, the geospatial data files have been compiled as ESRI ArcReader data folders and user interactive Published Map Files (.pmf files), all of which are catalogued by the boundaries of surface watersheds using U.S. Geological Survey (USGS) eight-digit hydrologic unit codes (HUC-8s). Specific karst features included in the dataset include mapped sinkhole locations, sinking (or disappearing) streams, internally drained catchments, karst springs inventoried in the USGS National Water Information System (NWIS) database, relic stream valleys, and karst flow paths obtained from results of previously reported water-tracer tests.

Analysis of the maximum discharge of karst springs

NASA Astrophysics Data System (ADS)

Bonacci, Ognjen

2001-07-01

Analyses are presented of the conditions that limit the discharge of some karst springs. The large number of springs studied show that, under conditions of extremely intense precipitation, a maximum value exists for the discharge of the main springs in a catchment, independent of catchment size and the amount of precipitation. Outflow modelling of karst-spring discharge is not easily generalized and schematized due to numerous specific characteristics of karst-flow systems. A detailed examination of the published data on four karst springs identified the possible reasons for the limitation on the maximum flow rate: (1) limited size of the karst conduit; (2) pressure flow; (3) intercatchment overflow; (4) overflow from the main spring-flow system to intermittent springs within the same catchment; (5) water storage in the zone above the karst aquifer or epikarstic zone of the catchment; and (6) factors such as climate, soil and vegetation cover, and altitude and geology of the catchment area. The phenomenon of limited maximum-discharge capacity of karst springs is not included in rainfall-runoff process modelling, which is probably one of the main reasons for the present poor quality of karst hydrological modelling. Résumé. Les conditions qui limitent le débit de certaines sources karstiques sont présentées. Un grand nombre de sources étudiées montrent que, sous certaines conditions de précipitations extrêmement intenses, il existe une valeur maximale pour le débit des sources principales d'un bassin, indépendante des dimensions de ce bassin et de la hauteur de précipitation. La modélisation des débits d'exhaure d'une source karstique n'est pas facilement généralisable, ni schématisable, à cause des nombreuses caractéristiques spécifiques des écoulements souterrains karstiques. Un examen détaillé des données publiées concernant quatre sources karstiques permet d'identifier les raisons possibles de la limitation de l'écoulement maximal: (1

Fractal dimension, walk dimension and conductivity exponent of karst networks around Tulum.

NASA Astrophysics Data System (ADS)

Hendrick, Martin; Renard, Philippe

2016-06-01

Understanding the complex structure of karst networks is a challenge. In this work, we characterize the fractal properties of some of the largest coastal karst network systems in the world. They are located near the town of Tulum (Quintana Roo, Mexico). Their fractal dimension d_f, conductivity exponent ˜{μ} and walk dimension d_w are estimated using real space renormalization and numerical simulations. We obtain the following values for these exponents: d_f≈ 1.5, d_w≈ 2.4, ˜{μ}≈ 0.9. We observe that the Einstein relation holds for these structures ˜{μ} ≈ -d_f + d_w. These results indicate that coastal karst networks can be considered as critical systems and this provides some foundations to model them within this framework.

Investigating the mechanisms of surface-bound functional groups in overcoming kinetic barriers to the precipitation of ordered dolomite at low temperature (Invited)

NASA Astrophysics Data System (ADS)

Kenward, P. A.; Roberts, J.; Fowle, D.; Goldstein, R.; Moore, D.; Gonzalez, L. A.

2013-12-01

The mineral dolomite, while abundant in the geologic record, is scarce in modern environments and limited to specific environments, due to kinetic barriers at low temperature (< 50°C). The microbial mediation of dolomite has been extensively studied using numerous microorganisms and disordered dolomite has been synthesized under abiotic conditions. However these studies either yielded disordered dolomite or failed to elucidate the specific mechanism(s) necessary to achieve the precipitation ordered phases of dolomite. Our work [1,2] demonstrates laboratory synthesis of dolomite at 25 °C using microcosms composed of either microbial biomass or abiotic carboxylated polystyrene micro-spheres and fluids with a range of marine-type compositions. We identify the density of surface-bound carboxyl-groups of organic matter as a primary control in ordered dolomite formation at low temperatures under the conditions studied. We hypothesize that surface-bound carboxyl-groups, such as those associated with organic matter or microbial biomass, overcome slow reaction kinetics for dolomite precipitation by dehydrating Mg2+ in an energetically favorable reaction. The precipitation of solid carbonate phases remains the most effective means of permanently sequestering CO2 from the atmosphere. As such, an increased understanding of dolomite kinetics at low temperature affords us the opportunity to apply this mechanism to engineered systems designed to enhance carbon sequestration in environments which do not kinetically favor the formation of carbonate mineral phases. [1] Kenward et al. (2013) AAPG, in press. [2] Roberts et al. (2013) PNAS, in press.

Preliminary conceptual models of the occurrence, fate, and transport of chlorinated solvents in karst regions of Tennessee

USGS Publications Warehouse

Wolfe, W.J.; Haugh, C.J.; Webbers, Ank; Diehl, T.H.

1997-01-01

Published and unpublished reports and data from 22 contaminated sites in Tennessee were reviewed to develop preliminary conceptual models of the behavior of chlorinated solvents in karst aquifers. Chlorinated solvents are widely used in many industrial operations. High density and volatility, low viscosity, and solubilities that are low in absolute terms but high relative to drinkingwater standards make chlorinated solvents mobile and persistent contaminants that are difficult to find or remove when released into the groundwater system. The major obstacle to the downward migration of chlorinated solvents in the subsurface is the capillary pressure of small openings. In karst aquifers, chemical dissolution has enlarged joints, bedding planes, and other openings that transmit water. Because the resulting karst conduits are commonly too large to develop significant capillary pressures, chlorinated solvents can migrate to considerable depth in karst aquifers as dense nonaqueous-phase liquids (DNAPL?s). Once chlorinated DNAPL accumulates in a karst aquifer, it becomes a source for dissolved-phase contamination of ground water. A relatively small amount of chlorinated DNAPL has the potential to contaminate ground water over a significant area for decades or longer. Conceptual models are needed to assist regulators and site managers in characterizing chlorinated-solvent contamination in karst settings and in evaluating clean-up alternatives. Five preliminary conceptual models were developed, emphasizing accumulation sites for chlorinated DNAPL in karst aquifers. The models were developed for the karst regions of Tennessee, but are intended to be transferable to similar karst settings elsewhere. The five models of DNAPL accumulation in karst settings are (1) trapping in regolith, (2) pooling at the top of bedrock, (3) pooling in bedrock diffuse-flow zones, (4) pooling in karst conduits, and (5) pooling in isolation from active ground-water flow. More than one conceptual

Factors Affecting Public-Supply Well Vulnerability in Two Karst Aquifers

PubMed Central

Musgrove, MaryLynn; Katz, Brian G; Fahlquist, Lynne S; Crandall, Christy A; Lindgren, Richard J

2014-01-01

Karst aquifers occur in a range of climatic and geologic settings. Nonetheless, they are commonly characterized by their vulnerability to water-quality impairment. Two karst aquifers, the Edwards aquifer in south-central Texas and the Upper Floridan aquifer in western Florida, were investigated to assess factors that control the movement of contaminants to public-supply wells (PSWs). The geochemistry of samples from a selected PSW or wellfield in each aquifer was compared with that from nearby monitoring wells and regional PSWs. Geochemistry results were integrated with age tracers, flow modeling, and depth-dependent data to refine aquifer conceptual models and to identify factors that affect contaminant movement to PSWs. The oxic Edwards aquifer is vertically well mixed at the selected PSW/wellfield, although regionally the aquifer is geochemically variable downdip. The mostly anoxic Upper Floridan aquifer is affected by denitrification and also is geochemically variable with depth. In spite of considerable differences in geology and hydrogeology, the two aquifers are similarly vulnerable to anthropogenic contamination. Vulnerability in studied PSWs in both aquifers is strongly influenced by rapid karst flowpaths and the dominance of young (<10 years) groundwater. Vulnerability was demonstrated by the frequent detection of similar constituents of concern in both aquifers (nitrate, atrazine, deethylatrazine, tetrachloroethene, and chloroform). Specific consideration of water-quality protection efforts, well construction and placement, and aquifer response times to land-use changes and contaminant loading are discussed, with implications for karst groundwater management. PMID:24841501

Factors affecting public-supply well vulnerability in two karst aquifers

USGS Publications Warehouse

Musgrove, MaryLynn; Katz, Brian G.; Fahlquist, Lynne S.; Crandall, Christy A.; Lindgren, Richard J.

2014-01-01

Karst aquifers occur in a range of climatic and geologic settings. Nonetheless, they are commonly characterized by their vulnerability to water-quality impairment. Two karst aquifers, the Edwards aquifer in south-central Texas and the Upper Floridan aquifer in western Florida, were investigated to assess factors that control the movement of contaminants to public-supply wells (PSWs). The geochemistry of samples from a selected PSW or wellfield in each aquifer was compared with that from nearby monitoring wells and regional PSWs. Geochemistry results were integrated with age tracers, flow modeling, and depth-dependent data to refine aquifer conceptual models and to identify factors that affect contaminant movement to PSWs. The oxic Edwards aquifer is vertically well mixed at the selected PSW/wellfield, although regionally the aquifer is geochemically variable downdip. The mostly anoxic Upper Floridan aquifer is affected by denitrification and also is geochemically variable with depth. In spite of considerable differences in geology and hydrogeology, the two aquifers are similarly vulnerable to anthropogenic contamination. Vulnerability in studied PSWs in both aquifers is strongly influenced by rapid karst flowpaths and the dominance of young (<10 years) groundwater. Vulnerability was demonstrated by the frequent detection of similar constituents of concern in both aquifers (nitrate, atrazine, deethylatrazine, tetrachloroethene, and chloroform). Specific consideration of water-quality protection efforts, well construction and placement, and aquifer response times to land-use changes and contaminant loading are discussed, with implications for karst groundwater management.

Hydrologic and geochemical dynamics of vadose zone recharge in a mantled karst aquifer: Results of monitoring drip waters in Mystery Cave, Minnesota

USGS Publications Warehouse

Doctor, Daniel H.; Alexander, E. Calvin; Jameson, Roy A.; Alexander, Scott C.

2015-01-01

Caves provide direct access to flows through the vadose zone that recharge karst aquifers. Although many recent studies have documented the highly dynamic processes associated with vadose zone flows in karst settings, few have been conducted in mantled karst settings, such as that of southeastern Minnesota. Here we present some results of a long-term program of cave drip monitoring conducted within Mystery Cave, Minnesota. In this study, two perennial ceiling drip sites were monitored between 1997 and 2001. The sites were located about 90 m (300 ft) apart along the same cave passage approximately 18 m (60 ft) below the surface; 7 to 9 m (20 to 30 ft) of loess and 12 m (40 ft) of flat-lying carbonate bedrock strata overlie the cave. Records of drip rate, electrical conductivity, and water temperature were obtained at 15 minute intervals, and supplemented with periodic sampling for major ion chemistry and water stable isotopes. Patterns in flow and geochemistry emerged at each of the two drip sites that were repeated year after year. Although one site responded relatively quickly (within 2-7 hours) to surface recharge events while the other responded more slowly (within 2-5 days), thresholds of antecedent moisture needed to be overcome in order to produce a discharge response at both sites. The greatest amount of flow was observed at both sites during the spring snowmelt period. Rainfall events less than 10 mm (0.4 in) during the summer months generally did not produce a drip discharge response, yet rapid drip responses were observed following intense storm events after periods of prolonged rainfall. The chemical data from both sites indicate that reservoirs of vadose zone water with distinct chemical signatures mixed during recharge events, and drip chemistry returned to a baseline composition during low flow periods. A reservoir with elevated chloride and sulfate concentrations impacts the slow-response drip site with each recharge event, but does not similarly

Techniques to better understand complex epikarst hydrogeology and contaminant transport in telogenetic karst settings

USDA-ARS?s Scientific Manuscript database

The movement of autogenic recharge through the shallow epikarstic zone in soil-mantled karst aquifers is important in understanding recharge areas and rates, groundwater storage, and contaminant transport processes. The groundwater flow in agricultural karst areas, such as Kentucky’s Pennyroyal Plat...

Applications of GIS and database technologies to manage a Karst Feature Database

USGS Publications Warehouse

Gao, Y.; Tipping, R.G.; Alexander, E.C.

2006-01-01

This paper describes the management of a Karst Feature Database (KFD) in Minnesota. Two sets of applications in both GIS and Database Management System (DBMS) have been developed for the KFD of Minnesota. These applications were used to manage and to enhance the usability of the KFD. Structured Query Language (SQL) was used to manipulate transactions of the database and to facilitate the functionality of the user interfaces. The Database Administrator (DBA) authorized users with different access permissions to enhance the security of the database. Database consistency and recovery are accomplished by creating data logs and maintaining backups on a regular basis. The working database provides guidelines and management tools for future studies of karst features in Minnesota. The methodology of designing this DBMS is applicable to develop GIS-based databases to analyze and manage geomorphic and hydrologic datasets at both regional and local scales. The short-term goal of this research is to develop a regional KFD for the Upper Mississippi Valley Karst and the long-term goal is to expand this database to manage and study karst features at national and global scales.

From evaporated seawater to uranium-mineralizing brines: Isotopic and trace element study of quartz-dolomite veins in the Athabasca system

NASA Astrophysics Data System (ADS)

Richard, Antonin; Boulvais, Philippe; Mercadier, Julien; Boiron, Marie-Christine; Cathelineau, Michel; Cuney, Michel; France-Lanord, Christian

2013-07-01

Stable isotope (O, H, C), radiogenic isotope (Sr, Nd) and trace element analyses have been applied to quartz-dolomite veins and their uranium(U)-bearing fluid inclusions associated with Proterozoic unconformity-related UO2 (uraninite) ores in the Athabasca Basin (Canada) in order to trace the evolution of pristine evaporated seawater towards U-mineralizing brines during their migration through sediments and basement rocks. Fluid inclusion data show that quartz and dolomite have precipitated from brines of comparable chemistry (excepted for relatively small amounts of CO2 found in dolomite-hosted fluid inclusions). However, δ18O values of quartz veins (δ18O = 11‰ to 18‰) and dolomite veins (δ18O = 13‰ to 24‰) clearly indicate isotopic disequilibrium between quartz and dolomite. Hence, it is inferred that this isotopic disequilibrium primarily reflects a decrease in temperature between the quartz stage (˜180 °C) and the dolomite stage (˜120 °C). The δ13C values of CO2 dissolved in dolomite-hosted fluid inclusions (δ13C = -30‰ to -4‰) and the δ13C values of dolomite (δ13C = -23.5‰ to -3.5‰) indicate that the CO2 dissolved in the mineralizing brines originated from brine-graphite interactions in the basement. The resulting slight increase in the fluid partial pressure of CO2 (pCO2) may have triggered dolomite precipitation instead of quartz. δ18O values of quartz veins and previously published δ18O values of the main alteration minerals around the U-ores (illite, chlorite and tourmaline) show that quartz and alteration minerals were isotopically equilibrated with the same fluid at ˜180 °C. The REE concentrations in dolomite produce PAAS-normalized patterns that show some similarities with that of UO2 and are clearly distinct from that of the other main REE-bearing minerals in these environments (monazite, zircon and aluminum phosphate-sulfate (APS) minerals). The radiogenic isotope compositions of dolomite (87Sr/86Sri = 0.7053 to 0

Transport of free and particulate-associated bacteria in karst

NASA Astrophysics Data System (ADS)

Mahler, B. J.; Personné, J.-C.; Lods, G. F.; Drogue, C.

2000-12-01

Karst aquifers, because of their unique hydrogeologic characteristics, are extremely susceptible to contamination by pathogens. Here we present the results of an investigation of contamination of a karst aquifer by fecal indicator bacteria. Two wells intercepting zones with contrasting effective hydraulic conductivities, as determined by pump test, were monitored both during the dry season and in response to a rain event. Samples were also collected from the adjacent ephemeral surface stream, which is known to be impacted by an upstream wastewater treatment plant after rainfall. Whole water and suspended sediment samples were analyzed for fecal coliforms and enterococci. During the dry season, pumping over a 2-day period resulted in increases in concentrations of fecal coliforms to greater than 10,000 CFU/100 ml in the high-conductivity well; enterococci and total suspended solids also increased, to a lesser degree. Toward the end of the pumping period, as much as 50% of the fecal coliforms were associated with suspended sediment. Irrigation of an up-gradient pine plantation with primary-treated wastewater is the probable source of the bacterial contamination. Sampling after a rain event revealed the strong influence of water quality of the adjacent Terrieu Creek on the ground water. Bacterial concentrations in the wells showed a rapid response to increased concentrations in the surface water, with fecal coliform concentrations in ground water ultimately reaching 60,000 CFU/100 ml. Up to 100% of the bacteria in the ground water was associated with suspended sediment at various times. The results of this investigation are evidence of the strong influence of surface water on ground water in karst terrain, including that of irrigation water. The large proportion of bacteria associated with particulates in the ground water has important implications for public health, as bacteria associated with particulates may be more persistent and more difficult to inactivate. The

FATE AND TRANSPORT OF PETROLEUM RELEASED FROM UNDERGROUND STORAGE TANKS in Areas of Karst Topography

EPA Science Inventory

The study determines the transport and ultimate fate of petroleum products within a region of karst geomorphology. The paper entails a complete literature review, including references that pertain to contaminant transport within karst aquifers

Submerged Humid Tropical Karst Landforms Observed By High-Resolution Multibeam Survey in Nagura Bay, Ishigaki Island, Southwestern Japan

NASA Astrophysics Data System (ADS)

Kan, H.; Urata, K.; Nagao, M.; Hori, N.; Fujita, K.; Yokoyama, Y.; Nakashima, Y.; Ohashi, T.; Goto, K.; Suzuki, A.

2014-12-01

Submerged tropical karst features were discovered in Nagura Bay on Ishigaki Island in the South Ryukyu Islands, Japan. This is the first description of submerged humid tropical karst using multibeam bathymetry. We conducted a broadband multibeam survey in the central area of Nagura Bay (1.85 × 2.7 km) and visualized the high-resolution bathymetric results with a grid size of 1 m over a depth range of 1.6-58.5 m. Various types of humid tropical karst landforms were found to coexist within the bay, including fluviokarst, doline karst, cockpit karst, polygonal karst, uvalas, and mega-dolines. We assume that Nagura Bay was a large karst basin in which older limestone remained submerged, thus preventing corrosion and the accumulation of reef sediments during periods of submersion, whereas the limestone outcropping on land was corroded during multiple interglacial and glacial periods. Based on our bathymetric result together with aerial photographs of the coastal area, we conclude that the submerged karst landscape has likely developed throughout the whole of Nagura Bay, covering an area of ~6 × 5 km. Accordingly, this area hosts the largest submerged karst in Japan. We also observed abundant coral communities during our SCUBA observations. The present marine conditions of Nagura Bay are characterized by low energy (calm sea) and low irradiance owing to the terrestrial influence. Such conditions have been emphasized by the presence of large undulating landforms, which cause decreases in wave intensity and irradiance with depth. These characteristics have acted to establish unique conditions compared to other coral reef areas in the Ryukyu Islands. It may play an important role in supporting the regional coral reef ecosystem.

Distribution of uranium and thorium in dolomitic gravel fill and shale saprolite

DOE PAGES

Phillips, D. H.; Watson, D. B.

2014-12-05

The objectives of this study were to examine (1) the distribution of U and Th in dolomitic gravel fill and shale saprolite, and (2) the removal of uranium from acidic groundwater by dolomitic gravel through precipitation with amorphous basaluminite at the U.S. DOE Oak Ridge Integrated Field Research Challenge (ORIFRC) field site west of the Oak Ridge Y-12 National Security Complex in East Tennessee. Media reactivity and sustainability are a technical concern with the deployment of any subsurface reactive media. Because the gravel was placed in the subsurface and exposed to contaminated groundwater for over 20 years, it provided amore » unique opportunity to study the solid and water phase geochemical conditions within the media after this length of exposure. This study illustrates that dolomite gravel can remove U from acidic contaminated groundwater with high levels of Al 3+, Ca 2+, NO 3-, and SO 4 2- over the long term. As the groundwater flows through high pH carbonate gravel, U containing amorphous basaluminite precipitates as the pH increases. This is due to an increase in groundwater pH from 3.2 to ~6.5 as it comes in contact with the gravel. Therefore, carbonate gravel could be considered as a possible treatment medium for removal and sequestration ofUand otherpHsensitive metals from acidic contaminated groundwater. Thorium concentrations are also high in the carbonate gravel. Thorium generally shows an inverse relationship with U from the surface down into the deeper saprolite. Barite precipitated in the shallow saprolite directly below the dolomitic gravel from barium present in the acidic contaminated groundwater.« less

Application of [sup 87]Sr/[sup 86]Sr, [delta][sup 18]O and [delta][sup 13]C isotopes to diagenesis correlation and connectivity of a fractured chalk reservoir, the Sidi El Kilani field, Tunisia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mearns, E.W.; McBride, J.J.; Bramwell, M.

1996-01-01

Oil is produced primarily from open fracture porosity in Upper Cretaceous chalk in the Sidi El Kilani oil field. Strontium Stratigraphy analyses of primary, unaltered matrix chalk has confirmed a Campanian to Maastrichtian age and has allowed dating of the reservoir with a resolution of [+-]1 Ma. This has facilitated reservoir correlation and has indicated where section is missing in certain wells due to faulting. [sup 87]Sr/[sup 86]Sr, [delta][sup 18]O and [delta][sup 13]C analyses suggest an early generation of fracture fill calcite cement may have formed by redistribution of CaCO[sub 3] from underlying carbonate sequences at temperatures in the regionmore » 35-55[degrees]C. Calcite cemented fractures tend to be healed and are not productive. Strontium Isotope Residual Salt Analyses (SrRSA) conducted on core, provide information on the formation water chemistry and reservoir connectivity at the time of oil filling. These data suggest that the NW-SE trending fault system that bisects the field is sealed across much of the fault plane. The main oil pool lies SW of the fault. A later generation of dolomite and barite cements, associated with productive open fractures, have Sr-O-C composition consistent with precipitation from fluids circulating at the time of hydrocarbon charge at temperatures close to current reservoir conditions of 70-75[degrees]C. Predicting the distribution of dolomite cemented open fractures has thus helped guide the development strategy of the field.« less

Application of {sup 87}Sr/{sup 86}Sr, {delta}{sup 18}O and {delta}{sup 13}C isotopes to diagenesis correlation and connectivity of a fractured chalk reservoir, the Sidi El Kilani field, Tunisia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mearns, E.W.; McBride, J.J.; Bramwell, M.

1996-12-31

Oil is produced primarily from open fracture porosity in Upper Cretaceous chalk in the Sidi El Kilani oil field. Strontium Stratigraphy analyses of primary, unaltered matrix chalk has confirmed a Campanian to Maastrichtian age and has allowed dating of the reservoir with a resolution of {+-}1 Ma. This has facilitated reservoir correlation and has indicated where section is missing in certain wells due to faulting. {sup 87}Sr/{sup 86}Sr, {delta}{sup 18}O and {delta}{sup 13}C analyses suggest an early generation of fracture fill calcite cement may have formed by redistribution of CaCO{sub 3} from underlying carbonate sequences at temperatures in the regionmore » 35-55{degrees}C. Calcite cemented fractures tend to be healed and are not productive. Strontium Isotope Residual Salt Analyses (SrRSA) conducted on core, provide information on the formation water chemistry and reservoir connectivity at the time of oil filling. These data suggest that the NW-SE trending fault system that bisects the field is sealed across much of the fault plane. The main oil pool lies SW of the fault. A later generation of dolomite and barite cements, associated with productive open fractures, have Sr-O-C composition consistent with precipitation from fluids circulating at the time of hydrocarbon charge at temperatures close to current reservoir conditions of 70-75{degrees}C. Predicting the distribution of dolomite cemented open fractures has thus helped guide the development strategy of the field.« less

[Characteristic of ammonia nitrogen adsorption on karst underground river sediments].

PubMed

Guo, Fang; Chen, Kun-Kun; Jiang, Guang-Hui

2011-02-01

Karst aquifers are one of the most important aquifers in Southwestern China. One of the characteristics of karst aquifers is the enhanced permeability permits high flow velocities are capable of transporting suspended and bedload sediments. Mobile sediment in karst may act as a vector for the transport of contaminates. 14 sediment samples were collected from two underground rivers in two typical karst areas in Liuzhou city, Guangxi Autonomous Region, China. According to simulated experiment methods, characteristic of adsorption of ammonia nitrogen on sediment was studied. The results of ammonia nitrogen adsorption dynamics on sediments showed that the maximum adsorption velocity was less than 2 h. The adsorption balance quantity in 5 h accounted for 71% - 98% of the maximum adsorption quantity. The maximum adsorption quantity of ammonia nitrogen was 385.5 mg/kg, which was sediment from a cave in the middle areas of Guancun underground river system. The study of isotherm adsorption indicated adsorption quantity of NH4+ increase followed by incremental balance concentration of NH4+ in the aquatic phase. Adsorption quantity of ammonia nitrogen in sediments has a relative linear relationship with adsorption balance concentrations. Adsorption-desorption balance concentrations were all low, indicating sediments from underground rivers have great adsorption potential. Under the condition of low and high concentrations of ammonia nitrogen in overlying water, Langmuir and Tempkin couldn't simulate or simulate results couldn't reach remarkable level, whilst Linear and Freundlich models could simulate well. Research on different type sediments, sampling times and depths from two underground rivers shows characteristic of ammonia nitrogen adsorption on karst underground river sediments doesn't have good correspondence with the type of sediments. One of the reasons is there is no big difference between sediments in the development of climate, geology, hydrological conditions

New insights to the formation of dolomite and magnesite through hydrothermal alteration of Ca-carbonates: An experimental approach

NASA Astrophysics Data System (ADS)

Kell-Duivestein, Isaac; Dietzel, Martin; Baldermann, Andre; Mavromatis, Vasileios

2017-04-01

Advanced knowledge about the physicochemical conditions and reaction paths underlying Ca-Mg carbonate formation, such as dolomite and magnesite, during the advanced stage of diagenesis is a pre-requirement for the accurate interpretation of proxy signals established from carbonate-hosting sedimentary archives. In this study, hydrothermal precipitation experiments were performed in order to trace and quantify the evolution of elemental (Ca, Mg and Sr) and stable isotopic δ18O signatures during the (trans)formation of intermediate aragonite and low-Mg calcite to more stable dolomite and magnesite in the presence of Mg- and Na-chloride-rich brines. Therefore, 330 mg of inorganic CaCO3 seed material (aragonite or calcite) was reacted with 30 mL of an artificial brine solution, originally containing 0.2 M of MgCl2(aq) and 0.1 M or 0.05 M of NaHCO3, in Teflon-lined stainless steel autoclaves at temperatures of 150, 180 and 220˚ C over the course of 365 days. The evolution of reaction products and of the experimental solutions was monitored by ICP-OES, CRDS, FTIR, XRD, EMPA and SEM analyses as well as pH and alkalinity measurements. Based on the apparent solid-phase composition and reactive fluid chemistry the following sequence of mineral growth was established: aragonite and/or low-Mg calcite reacted with aqueous Mg2+ ions to form intermediate huntite, brucite and high-Mg calcite, subsequently altered to Ca-excess dolomite and Ca-rich magnesite and finally converted to nearly stoichiometric endmembers. A progressive evolution in the stoichiometry of dolomite (from 42 to 50 mol% MgCO3) and magnesite (from 80 to 98 mol% MgCO3) as well as the increase in the degree of cation order in dolomite (from 0.26 to 0.74) were observed during this reaction sequence, implying a kinetic drive towards the (thermodynamically stable) end members. The latter processes were also traced, by means of δ18O isotope exchange kinetics between fluid and precipitating solids in bulk (Δ = δ18

A rock physics and seismic reservoir characterization study of the Rock Springs Uplift, a carbon dioxide sequestration site in Southwestern Wyoming

DOE PAGES

Grana, Dario; Verma, Sumit; Pafeng, Josiane; ...

2017-06-20

We present a reservoir geophysics study, including rock physics modeling and seismic inversion, of a carbon dioxide sequestration site in Southwestern Wyoming, namely the Rock Springs Uplift, and build a petrophysical model for the potential injection reservoirs for carbon dioxide sequestration. Our objectives include the facies classification and the estimation of the spatial model of porosity and permeability for two sequestration targets of interest, the Madison Limestone and the Weber Sandstone. The available dataset includes a complete set of well logs at the location of the borehole available in the area, a set of 110 core samples, and a seismicmore » survey acquired in the area around the well. The proposed study includes a formation evaluation analysis and facies classification at the well location, the calibration of a rock physics model to link petrophysical properties and elastic attributes using well log data and core samples, the elastic inversion of the pre-stack seismic data, and the estimation of the reservoir model of facies, porosity and permeability conditioned by seismic inverted elastic attributes and well log data. In particular, the rock physics relations are facies-dependent and include granular media equations for clean and shaley sandstone, and inclusion models for the dolomitized limestone. The permeability model has been computed by applying a facies-dependent porosity-permeability relation calibrated using core sample measurements. Finally, the study shows that both formations show good storage capabilities. The Madison Limestone includes a homogeneous layer of high-porosity high-permeability dolomite; the Weber Sandstone is characterized by a lower average porosity but the layer is thicker than the Madison Limestone.« less

A rock physics and seismic reservoir characterization study of the Rock Springs Uplift, a carbon dioxide sequestration site in Southwestern Wyoming

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grana, Dario; Verma, Sumit; Pafeng, Josiane

We present a reservoir geophysics study, including rock physics modeling and seismic inversion, of a carbon dioxide sequestration site in Southwestern Wyoming, namely the Rock Springs Uplift, and build a petrophysical model for the potential injection reservoirs for carbon dioxide sequestration. Our objectives include the facies classification and the estimation of the spatial model of porosity and permeability for two sequestration targets of interest, the Madison Limestone and the Weber Sandstone. The available dataset includes a complete set of well logs at the location of the borehole available in the area, a set of 110 core samples, and a seismicmore » survey acquired in the area around the well. The proposed study includes a formation evaluation analysis and facies classification at the well location, the calibration of a rock physics model to link petrophysical properties and elastic attributes using well log data and core samples, the elastic inversion of the pre-stack seismic data, and the estimation of the reservoir model of facies, porosity and permeability conditioned by seismic inverted elastic attributes and well log data. In particular, the rock physics relations are facies-dependent and include granular media equations for clean and shaley sandstone, and inclusion models for the dolomitized limestone. The permeability model has been computed by applying a facies-dependent porosity-permeability relation calibrated using core sample measurements. Finally, the study shows that both formations show good storage capabilities. The Madison Limestone includes a homogeneous layer of high-porosity high-permeability dolomite; the Weber Sandstone is characterized by a lower average porosity but the layer is thicker than the Madison Limestone.« less

The effect of CO2 at low temperature and pressure on solutions supersaturated with silica in the presence of limestone and dolomite

USGS Publications Warehouse

Lovering, T.G.; Patten, L.E.

1962-01-01

The effect of 1 atm of CO2 over initially neutral solutions supersaturated with silica, at room temperature, as contrasted with 1 atm of air was determined over a period of 5 months, together with changes brought about by the introduction of calcite and dolomite to these solutions in the form of either chips or finely ground powder. In the absence of CO2 all solutions quickly reached equilibrium and no silica precipitated. In the presence of CO2 approximately two-thirds of the silica precipitated as silica gel within the first 2 months; the amount of silica precipitated was not affected by the presence of limestone or dolomite. Silica gel precipitated as a fine powder in the presence of finely ground calcite and dolomite, but as a cloudy gelatinous mass in the presence of coarse chips of dolomite and calcite, and in the absence of either calcite or dolomite. Preferential leaching of calcium from dolomite took place, both in the presence of air and in the presence of CO2, but was more pronounced in the presence of air. There was no evidence of physical replacement of either limestone or dolomite by precipitated silica. ?? 1962.

A review of stormwater management in karst

USDA-ARS?s Scientific Manuscript database

Stormwater management can be a challenge in any environment, but it is especially difficult in karst terrain. The characteristic dissolution of bedrock creates depressions in topography as well as voids in the subsurface, resulting in problems such as collapse sinkhole development, groundwater cont...

Studying the flow dynamics of a karst aquifer system with an equivalent porous medium model.

PubMed

Abusaada, Muath; Sauter, Martin

2013-01-01

The modeling of groundwater flow in karst aquifers is a challenge due to the extreme heterogeneity of its hydraulic parameters and the duality in their discharge behavior, that is, rapid response of highly conductive karst conduits and delayed drainage of the low-permeability fractured matrix after recharge events. There are a number of different modeling approaches for the simulation of the karst groundwater dynamics, applicable to different aquifer as well as modeling problem types, ranging from continuum models to double continuum models to discrete and hybrid models. This study presents the application of an equivalent porous model approach (EPM, single continuum model) to construct a steady-state numerical flow model for an important karst aquifer, that is, the Western Mountain Aquifer Basin (WMAB), shared by Israel and the West-Bank, using MODFLOW2000. The WMAB was used as a catchment since it is a well-constrained catchment with well-defined recharge and discharge components and therefore allows a control on the modeling approach, a very rare opportunity for karst aquifer modeling. The model demonstrates the applicability of equivalent porous medium models for the simulation of karst systems, despite their large contrast in hydraulic conductivities. As long as the simulated saturated volume is large enough to average out the local influence of karst conduits and as long as transport velocities are not an issue, EPM models excellently simulate the observed head distribution. The model serves as a starting basis that will be used as a reference for developing a long-term dynamic model for the WMAB, starting from the pre-development period (i.e., 1940s) up to date. © 2012, The Author(s). GroundWater © 2012, National Ground Water Association.

Gypsum karst in Italy: a review

NASA Astrophysics Data System (ADS)

De Waele, Jo; Chiarini, Veronica; Columbu, Andrea; D'Angeli, Ilenia M.; Madonia, Giuliana; Parise, Mario; Piccini, Leonardo; Vattano, Marco; Vigna, Bartolomeo; Zini, Luca; Forti, Paolo

2016-04-01

Although outcropping only rarely in Italy, gypsum karst has been described in detail since the early XXth century (Marinelli, 1917). Gypsum caves are now known from almost all Italian regions (Madonia & Forti, 2003), but are mainly localised along the northern border of the Apennine chain (Emilia Romagna and Marche regions), Calabria, and Sicily, where the major outcrops occur. Recently, important caves have also been discovered in the underground gypsum quarries in Piedmont (Vigna et al., 2010). During the late 80s and 90s several multidisciplinary studies have been carried out in many gypsum areas. All this work converged into a comprehensive overview in 2003 (Madonia & Forti, 2003). Further detailed studies focused on the gypsum areas of Emilia Romagna (Chiesi et al., 2010; Forti & Lucci, 2010; Demaria et al., 2012; De Waele & Pasini, 2013; Ercolani et al., 2013; Columbu et al., 2015; Lucci & Piastra, 2015; Tedeschi et al., 2015) and of Sicily (Madonia & Vattano, 2011). Sinkholes related to Permo-Triassic gypsum have been studied in Friuli Venezia Giulia (Zini et al., 2015). This presentation will review the state of the art regarding different aspects of evaporite karst in Italy focusing on the main new results. References Chiesi M., et al. (2010) - Origin and evolution of a salty gypsum/anhydrite karst spring: the case of Poiano (Northern Apennines, Italy). Hydrogeology Journal, 18, pp. 1111-1124. Columbu A. et al. (2015) - Gypsum caves as indicators of climate-driven river incision and aggradation in a rapidly uplifting region. Geology, 43(6), 539-542. Demaria D. et al. (Eds.) (2012), Le Grotte Bolognesi, GSB-USB, 431 p. De Waele J., Pasini G. (2013) - Intra-messinian gypsum palaeokarst in the northern Apennines and its palaeogeographic implications. Terra Nova 25, pp. 199-205. Ercolani M., et al. (Eds.) (2013), I Gessi e la Cave i Monte Tondo. Studio multidisciplinare di un'area carsica nella Vena del Gesso Romagnola. Memorie Ist. It. Spel. II(26), 559 p

Management Can Reduce Mobility of Escherichia coli compared to traditional groundwater tracers within karst terrains

USDA-ARS?s Scientific Manuscript database

An understanding of fundamental processes controlling pathogen movement is necessary to protect water resources across the globe. Limited filtration and turbulent flow make karst aquifers susceptible to microbial contamination. Groundwater tracers typically used in karst terrains include fluorescent...

Hydrograph monitoring and analysis for sustainable karst water management in Nyadeng Spring, East Borneo

NASA Astrophysics Data System (ADS)

Widyastuti, M.; Fatchurohman, H.; Fathoni, W. A.; Hakim, A. A.; Haryono, E.

2018-04-01

Karst aquifer stores abundant water resources within its matrix, conduits, and intergranular pores. Karst aquifer plays an important role in providing water supply, especially in the areas nearby that commonly dry and lack of surface water resources. Karst spring hydrograph analysis is very fundamental step to–assess and determines the condition of the catchment area in karst terrain. Recession curve is believed to be the most stable part in single flood hydrograph that represents the aquifer characteristics. Nyadeng is one of the most significant karst springs that located in Merabu Karst Area, East Borneo. Villagers in Merabu highly depend on Nyadeng Spring for fulfilled their freshwater need. Hydrograph monitoring has been initiated for one year in Nyadeng Spring as a preliminary action for karst water management in Merabu. Water level data series obtained using automatic water level data logger and then correlated with manual discharge measurement to generate stage-discharge rating curve. The stage-discharge rating curve formula for Nyadeng Spring calculated as y = 0,0102e5,8547x with r2 value = 0.8759. From the combination of several single flood events, Master Recession Curve (MRC) was generated to determine flow regime as the main consideration for karstification degree calculation. From the MRC result, flow regimes formula determined as Qt = 3.2-0.001t + 1.2(1-0.012t)+1.6(1-0.035t) indicated that one sub-regime with laminar flow and two sub-regimes with turbulent flow existed. From the MRC formula, the degree of karstification in Nyadeng Spring classified at seventh scale (developed karstification of the aquifer) based on Malik’s karstification degree (2012). The degree of karstification in Nyadeng Spring indicates that the aquifer formed by large conduit channels, fissures, and macro fissures which are able to provide significant water sources that can be utilized for multi purposes. Therefore, it is concluded that spring hydrograph monitoring provide

Physical and Hydrological Meaning of the Spectral Information from Hydrodynamic Signals at Karst Springs

NASA Astrophysics Data System (ADS)

Dufoyer, A.; Lecoq, N.; Massei, N.; Marechal, J. C.

2017-12-01

Physics-based modeling of karst systems remains almost impossible without enough accurate information about the inner physical characteristics. Usually, the only available hydrodynamic information is the flow rate at the karst outlet. Numerous works in the past decades have used and proven the usefulness of time-series analysis and spectral techniques applied to spring flow, precipitations or even physico-chemical parameters, for interpreting karst hydrological functioning. However, identifying or interpreting the karst systems physical features that control statistical or spectral characteristics of spring flow variations is still challenging, not to say sometimes controversial. The main objective of this work is to determine how the statistical and spectral characteristics of the hydrodynamic signal at karst springs can be related to inner physical and hydraulic properties. In order to address this issue, we undertake an empirical approach based on the use of both distributed and physics-based models, and on synthetic systems responses. The first step of the research is to conduct a sensitivity analysis of time-series/spectral methods to karst hydraulic and physical properties. For this purpose, forward modeling of flow through several simple, constrained and synthetic cases in response to precipitations is undertaken. It allows us to quantify how the statistical and spectral characteristics of flow at the outlet are sensitive to changes (i) in conduit geometries, and (ii) in hydraulic parameters of the system (matrix/conduit exchange rate, matrix hydraulic conductivity and storativity). The flow differential equations resolved by MARTHE, a computer code developed by the BRGM, allows karst conduits modeling. From signal processing on simulated spring responses, we hope to determine if specific frequencies are always modified, thanks to Fourier series and multi-resolution analysis. We also hope to quantify which parameters are the most variable with auto

Imaging of underground karst water channels using an improved multichannel transient Rayleigh wave detecting method

PubMed Central

Zheng, Xuhui; Liu, Lei; Li, Gao; Zhou, Fubiao; Xu, Jiemin

2018-01-01

Geological and hydrogeological conditions in karst areas are complicated from the viewpoint of engineering. The construction of underground structures in these areas is often disturbed by the gushing of karst water, which may delay the construction schedule, result in economic losses, and even cause heavy casualties. In this paper, an innovative method of multichannel transient Rayleigh wave detecting is proposed by introducing the concept of arrival time difference phase between channels (TDP). Overcoming the restriction of the space-sampling law, the proposed method can extract the phase velocities of different frequency components from only two channels of transient Rayleigh wave recorded on two adjacent detecting points. This feature greatly improves the work efficiency and lateral resolution of transient Rayleigh wave detecting. The improved multichannel transient Rayleigh wave detecting method is applied to the detection of karst caves and fractures in rock mass of the foundation pit of Yan’an Road Station of Guiyang Metro. The imaging of the detecting results clearly reveals the distribution of karst water inflow channels, which provided significant guidance for water plugging and enabled good control over karst water gushing in the foundation pit. PMID:29883492

Imaging of underground karst water channels using an improved multichannel transient Rayleigh wave detecting method.

PubMed

Zheng, Xuhui; Liu, Lei; Sun, Jinzhong; Li, Gao; Zhou, Fubiao; Xu, Jiemin

2018-01-01

Geological and hydrogeological conditions in karst areas are complicated from the viewpoint of engineering. The construction of underground structures in these areas is often disturbed by the gushing of karst water, which may delay the construction schedule, result in economic losses, and even cause heavy casualties. In this paper, an innovative method of multichannel transient Rayleigh wave detecting is proposed by introducing the concept of arrival time difference phase between channels (TDP). Overcoming the restriction of the space-sampling law, the proposed method can extract the phase velocities of different frequency components from only two channels of transient Rayleigh wave recorded on two adjacent detecting points. This feature greatly improves the work efficiency and lateral resolution of transient Rayleigh wave detecting. The improved multichannel transient Rayleigh wave detecting method is applied to the detection of karst caves and fractures in rock mass of the foundation pit of Yan'an Road Station of Guiyang Metro. The imaging of the detecting results clearly reveals the distribution of karst water inflow channels, which provided significant guidance for water plugging and enabled good control over karst water gushing in the foundation pit.

The development of deep karst in the anticlinal aquifer structure based on the coupling of multistage flow systems

NASA Astrophysics Data System (ADS)

Xu, M.; Zhong, L.; Yang, Y.

2017-12-01

Under the background of neotectonics, the multistage underground flow system has been form due the different responses of main stream and tributaries to crust uplift. The coupling of multistage underground flow systems influences the development of karst thoroughly. At first, the research area is divided into vadose area, shunted area and exorheic area based on the development characteristics of transverse valley. Combining the controlling-drain action with topographic index and analyzing the coupling features of multistage underground flow system. And then, based on the coupling of multistage underground flow systems, the characteristics of deep karst development were verified by the lossing degree of surface water, water bursting and karst development characteristics of tunnels. The vadose area is regional water system based, whose deep karst developed well. It resulted the large water inflow of tunnels and the surface water drying up. The shunted area, except the region near the transverse valleys, is characterized by regional water system. The developed deep karst make the surface water connect with deep ground water well, Which caused the relatively large water flow of tunnels and the serious leakage of surface water. The deep karst relatively developed poor in the regions near transverse valleys which is characterized by local water system. The exorheic area is local water system based, whose the deep karst developed poor, as well as the connection among surface water and deep ground water. It has result in the poor lossing of the surface water under the tunnel construction. This study broadens the application field of groundwater flow systems theory, providing a new perspective for the study of Karst development theory. Meanwhile it provides theoretical guidance for hazard assessment and environmental negative effect in deep-buried Karst tunnel construction.

A large-scale integrated karst-vegetation recharge model to understand the impact of climate and land cover change

NASA Astrophysics Data System (ADS)

Sarrazin, Fanny; Hartmann, Andreas; Pianosi, Francesca; Wagener, Thorsten

2017-04-01

Karst aquifers are an important source of drinking water in many regions of the world, but their resources are likely to be affected by changes in climate and land cover. Karst areas are highly permeable and produce large amounts of groundwater recharge, while surface runoff is typically negligible. As a result, recharge in karst systems may be particularly sensitive to environmental changes compared to other less permeable systems. However, current large-scale hydrological models poorly represent karst specificities. They tend to provide an erroneous water balance and to underestimate groundwater recharge over karst areas. A better understanding of karst hydrology and estimating karst groundwater resources at a large-scale is therefore needed for guiding water management in a changing world. The first objective of the present study is to introduce explicit vegetation processes into a previously developed karst recharge model (VarKarst) to better estimate evapotranspiration losses depending on the land cover characteristics. The novelty of the approach for large-scale modelling lies in the assessment of model output uncertainty, and parameter sensitivity to avoid over-parameterisation. We find that the model so modified is able to produce simulations consistent with observations of evapotranspiration and soil moisture at Fluxnet sites located in carbonate rock areas. Secondly, we aim to determine the model sensitivities to climate and land cover characteristics, and to assess the relative influence of changes in climate and land cover on aquifer recharge. We perform virtual experiments using synthetic climate inputs, and varying the value of land cover parameters. In this way, we can control for variations in climate input characteristics (e.g. precipitation intensity, precipitation frequency) and vegetation characteristics (e.g. canopy water storage capacity, rooting depth), and we can isolate the effect that each of these quantities has on recharge. Our results

Geomorphometric correlations of vegetation cover properties and topographic karst features based on high-resolution LiDAR DTM of Aggtelek Karst, NE Hungary

NASA Astrophysics Data System (ADS)

Székely, Balázs; Telbisz, Tamás; Koma, Zsófia; Kelemen, Kristóf; Szmorad, Ferenc; Deák, Márton; Látos, Tamás; Standovár, Tibor

2015-04-01

Topography and lithology are two major factors influencing the vegetation cover, its mosaic pattern and lateral transitions. In karstic areas the topography has a high diversity, microtopographic landforms influence the local ecological setting, vegetation structure. Presence of sinkholes of various sizes and geometric arrangements causes rapid lateral variation of the slope, aspect patterns as well as highly modify the soil water balance in time and space. These diversity of factors defines a mosaicked habitat pattern for vegetation assemblages. The World Heritage Site Aggtelek Karst/Slovakian Karst Caves has characteristic natural and environmental properties concerning the geomorphological as well as the ecological values. In order to be able to study the topographic influence on the ecological setting, a high-resolution digital terrain model (DTM) and digital surface model (DSM) have been derived from airborne laser scanning data depicting the karstic micro- and macrotopographic Landscape elements and the envelope surface of the canopy. Additional vegetation parameters like closure and average height have been derived from a normalized digital surface model (nDSM). Extensive mapping of vegetation properties has been carried out: centered on points of a grid array several vegetation-specific data - including composition and structure of tree and shrub layers, herbacesous vegetation and tree regeneration - have been acquired. Various classification patterns - based on trees pecies composition, vertical vegetation structure - have been derived from this data set. The comparison of the vegetation classification data and the geomorphometric DTM derivatives yielded interesting results. Certain vegetation characteristics often correlate with the geomorphometric properties. We interpret this similarity as sensitivity of vegetion to fine-scale variations in geomorphic properties like aspect, illumination conditions and soil properties. However, in many cases the

Further biogeochemical characterization of a trichloroethene-contaminated fractured dolomite aquifer: Electron source and microbial communities involved in reductive dechlorination

USGS Publications Warehouse

Hohnstock-Ashe, A. M.; Plummer, S.M.; Yager, R.M.; Baveye, P.; Madsen, E.L.

2001-01-01

A recent article presented geochemical and microbial evidence establishing metabolic adaptation to and in-situ reductive dechlorination of trichloroethene (TCE) in a fractured dolomite aquifer. This study was designed to further explore site conditions and microbial populations and to explain previously reported enhancement of reductive dechlorination by the addition of pulverized dolomite to laboratory microcosms. A survey of groundwater geochemical parameters (chlorinated ethenes, ethene, H2, CH4, DIC, DOC, and ??13C values for CH4, DIC, and DOC) indicated that in situ reductive dechlorination was ongoing and that an unidentified pool of organic carbon was contributing, likely via microbial respiration, to the large and relatively light onsite DIC pool. Petroleum hydrocarbons associated with the dolomite rock were analyzed by GC/MS and featured a characteristically low ??13C value. Straight chain hydrocarbons were extracted from the dolomite previously found to stimulate reductive dechlorination; these were particularly depleted in hexadecane (HD). Thus, we hypothesized that HD and related hydrocarbons might be anaerobically respired and serve both as the source of onsite DIC and support reductive dechlorination of TCE. Microcosms amended with pulverized dolomite demonstrated reductive dechlorination, whereas a combusted dolomite amendment did not. HD-amended microcosms were also inactive. Therefore, the stimulatory factor in the pulverized dolomite was heat labile, but that component was not HD. Amplified Ribosomal DNA Restriction Analysis (ARDRA) of the microbial populations in well waters indicated that a relatively low diversity, sulfur-transforming community outside the plume was shifted toward a high diversity community including Dehalococcoides ethenogenes-type microorganisms inside the zone of contamination. These observations illustrate biogeochemical intricacies of in situ reductive dechlorination reactions.

Factors affecting public-supply well vulnerability in two karst aquifers.

PubMed

Musgrove, MaryLynn; Katz, Brian G; Fahlquist, Lynne S; Crandall, Christy A; Lindgren, Richard J

2014-09-01

Karst aquifers occur in a range of climatic and geologic settings. Nonetheless, they are commonly characterized by their vulnerability to water-quality impairment. Two karst aquifers, the Edwards aquifer in south-central Texas and the Upper Floridan aquifer in western Florida, were investigated to assess factors that control the movement of contaminants to public-supply wells (PSWs). The geochemistry of samples from a selected PSW or wellfield in each aquifer was compared with that from nearby monitoring wells and regional PSWs. Geochemistry results were integrated with age tracers, flow modeling, and depth-dependent data to refine aquifer conceptual models and to identify factors that affect contaminant movement to PSWs. The oxic Edwards aquifer is vertically well mixed at the selected PSW/wellfield, although regionally the aquifer is geochemically variable downdip. The mostly anoxic Upper Floridan aquifer is affected by denitrification and also is geochemically variable with depth. In spite of considerable differences in geology and hydrogeology, the two aquifers are similarly vulnerable to anthropogenic contamination. Vulnerability in studied PSWs in both aquifers is strongly influenced by rapid karst flowpaths and the dominance of young (<10 years) groundwater. Vulnerability was demonstrated by the frequent detection of similar constituents of concern in both aquifers (nitrate, atrazine, deethylatrazine, tetrachloroethene, and chloroform). Specific consideration of water-quality protection efforts, well construction and placement, and aquifer response times to land-use changes and contaminant loading are discussed, with implications for karst groundwater management. © 2014 The Authors. Groundwater published by Wiley Periodicals, Inc. on behalf of National Ground Water Association.

A New Methodology for Open Pit Slope Design in Karst-Prone Ground Conditions Based on Integrated Stochastic-Limit Equilibrium Analysis

NASA Astrophysics Data System (ADS)

Zhang, Ke; Cao, Ping; Ma, Guowei; Fan, Wenchen; Meng, Jingjing; Li, Kaihui

2016-07-01

Using the Chengmenshan Copper Mine as a case study, a new methodology for open pit slope design in karst-prone ground conditions is presented based on integrated stochastic-limit equilibrium analysis. The numerical modeling and optimization design procedure contain a collection of drill core data, karst cave stochastic model generation, SLIDE simulation and bisection method optimization. Borehole investigations are performed, and the statistical result shows that the length of the karst cave fits a negative exponential distribution model, but the length of carbonatite does not exactly follow any standard distribution. The inverse transform method and acceptance-rejection method are used to reproduce the length of the karst cave and carbonatite, respectively. A code for karst cave stochastic model generation, named KCSMG, is developed. The stability of the rock slope with the karst cave stochastic model is analyzed by combining the KCSMG code and the SLIDE program. This approach is then applied to study the effect of the karst cave on the stability of the open pit slope, and a procedure to optimize the open pit slope angle is presented.

Occurrence and transport of pharmaceuticals in a karst groundwater system affected by domestic wastewater treatment plants.

PubMed

Einsiedl, Florian; Radke, Michael; Maloszewski, Piotr

2010-09-20

The occurrence of two pharmaceuticals, ibuprofen and diclofenac, in a vulnerable karst groundwater system was investigated. The hydrogeology of the karst system was identified by collecting (3)H samples in groundwater over 27years and by performing tracer tests. The isotopes and tracer data were interpreted by mathematical modeling to estimate the mean transit time of water and to characterize the hydrogeological flow paths in the groundwater system. By this approach, a mean (3)H transit time of 4.6 years for the fissured-porous karst aquifer was determined, whereas the fast flowing water in the conduit system showed a mean transit time of days. Both pharmaceuticals which infiltrated along sinkholes and small streams into the karst system were detected in concentrations of up to approximately 1 microg/L in effluent water of the wastewater treatment plants. Diclofenac was present in most samples collected from four springs discharging the karst groundwater to the rivers Altmühl and Anlauter in concentrations between 3.6 and 15.4 ng/L. In contrast, ibuprofen was rarely detected in groundwater. The results of this study suggest that both pharmaceuticals move into the fractured system of the karst system and go into storage. Thus dilution processes are the dominant control on the concentrations of both pharmaceuticals in the fractured system, whereas biodegradation is likely less important. Copyright (c) 2010 Elsevier B.V. All rights reserved.

All in the Training: Techniques for Enhancing Karst Landscape Education through Show Cave Interpretation

ERIC Educational Resources Information Center

North, Leslie; van Beynen, Philip

2016-01-01

Despite the abundance of karst terrains and a universal lack of knowledge about the role they play in supplying freshwater resources, informal environmental education through guided show cave tours is poorly understood. This study evaluated techniques for educating cave guides on how to disseminate information about human-karst interactions to…

Integrated Research Methods for Applied Urban Hydrogeology of Karst Sites

NASA Astrophysics Data System (ADS)

Epting, J.; Romanov, D. K.; Kaufmann, G.; Huggenberger, P.

2008-12-01

Integrated and adaptive surface- and groundwater monitoring and management in urban areas require innovative process-oriented approaches. To accomplish this, it is necessary to develop and combine interdisciplinary instruments that facilitate adequately quantifying cumulative effects on groundwater flow regimes. While the characterization and modeling of flow in heterogeneous and fractured media has been investigated intensively, there are no well-developed long-term hydrogeological research sites for gypsum karst. Considering that infrastructures in karst regions, particularly in gypsum, are prone to subsidence, severe problems can arise in urban areas. In the 1880's, a river dam was constructed on gypsum-containing rock, Southeast of Basel, Switzerland. Over the last 30 years, subsidence of the dam and an adjacent highway has been observed. Surface water infiltrates upstream of the dam, circulates in the gravel deposits and in the weathered bedrock around and beneath the dam and exfiltrates downstream into the river. These processes enhance karstification processes in the soluble units of the gypsum. As a result an extended weathering zone within the bedrock and the development of preferential flow paths within voids and conduits can be observed. To prevent further subsidence, construction measures were conducted in two major project phases in 2006 and 2007. The highway was supported by a large number of pillars embedded in the non- weathered rock and by a sealing pile wall, to prevent infiltrating river water circulating around the dam and beneath the foundation of the highway. To safeguard surface and subsurface water resources during the construction measures, an extensive observation network was set up. Protection schemes and geotechnical investigations that are necessary for engineering projects often provide "windows of opportunity", bearing the possibility to change perceptions concerning the sustainable development of water resources and coordinate future

Baseflow index assessment and master recession curve analysis for karst water management in Kakap Spring, Gunung Sewu

NASA Astrophysics Data System (ADS)

Fatchurohman, H.; Adji, T. N.; Haryono, E.; Wijayanti, P.

2018-04-01

Karst terrain occurs in combination of high solubility rock and well developed secondary porosity. Over the time, groundwater resources have not been well managed including karst aquifers. Karst aquifers formed in a very complex hydrological system. Developed in fracture media and soluble rocks have led karst aquifers into various porosity types and aquifer properties. Karst spring hydrograph is an essential element for water resource management. The form of karst spring hydrograph reflects the aquifer characteristics. The shapes of flood discharge hydrographs represent aquifer responses to recharge and contain information about the interior condition of karst drainage basin. Every year, Gunung Sewu karst area is suffering to severe water scarcity. The development of sub-terrain drainage networks lead into the minimum surface water resources. Kakap Spring is perennial gravity spring that located adjacently to the border of Gunung Sewu and the alluvial formation of Baturetno. Kakap spring play vital role regarding water supply in Giriwoyo sub-district as the spring fulfill most of the water needs in Giriwoyo sub-district. Kakap Spring utilized by the local authorities as the main source for pipeline water and distributed to the households. Water level data series obtained using automatic water level data logger and then correlated with manual discharge measurement to generate stage-discharge rating curve. The stage-discharge rating curve formula for Kakap Spring calculated as y = 14,504e8,9763x with r2 value = 0.8582. From the MRC result, flow regimes formula determined as + 400 (1-0,005t) + 700 (1-0,01t)., indicated that the aquifer dominated by turbulent flow regime. From the MRC formula, the degree of karstification in Kakap Spring classified at eighth scale. The average baseflow index in Kakap Spring calculated using recession curve analysis with the BFI index = 0,7485.

Petrology and dolomitization of the C' zone, Red River Formation (Ordovician), in a deep core, Williston basin, Richland County, eastern Montana

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zenger, D.H.

Unocal's Superior [number sign]1 Vanderhoof 97-foot (29.6 m) core consists of 63 feet (19.2 m) of the upper part of the C' burrowed member (BM) overlain by 34 feet (10.4 m) of the C' laminated member (LM) of the productive Red River Formation. The LM is mainly laminated, anhydritic, stylolitic, essentially unfossiliferous dolomudstone to calcareous dolomudstone with more minor dolomitic lime mudstone. The unit represents a restricted, hypersaline, inner shelf environment. The BM is burrow-mottled (Thalassinoides ), skeletal, dolomitic wackestone to grainstone matrix to calcareous dolowackestone (burrow fills) and represents near-normal salinity, inner shelf conditions. Dolomite is primarily replacive andmore » in the LM occurs as 25--50 [mu]m rhombs floating in mudstone or associated with stylolites, and as nonplanar, polymodal (5--50 [mu]m) crystals in totally dolomitized intervals. Most BM dolomite consists of 20--160 [mu]m, primarily nonplanar crystals in the largely replaced burrow fills; it also occurs as crystals that are disseminated or focused along stylolites (as in LM), as large crystals selectively and pseudomorphically replacing echinoderm fragments, and more rarely as late-stage, void-filling saddle dolomite. Previous theories of dolomitization have invoked descending brines. Geochemical data, in particular depleted [delta][sup 18]O and relatively low amounts of trace elements Sr and Na, but high Fe and Mn content, reveal that if brines were responsible for early diagenetic replacement, the dolomite has not retained such geochemical memory; rather it has undergone modification, acquiring later diagenetic, burial signatures. Possibly more of the replacement itself was later and deeper than previously thought.« less

A new genetic mechanism of natural gas accumulation.

PubMed

Yang, Chengyu; Ni, Zhiyong; Wang, Tieguan; Chen, Zhonghong; Hong, Haitao; Wen, Long; Luo, Bing; Wang, Wenzhi

2018-05-29

Natural gas of organic origin is primarily biogenic or thermogenic; however, the formation of natural gas is occasionally attributed to hydrothermal activity. The Precambrian dolomite reservoir of the Anyue gas field is divided into three stages. Dolomite-quartz veins were precipitated after two earlier stages of dolomite deposition. Fluid inclusions in the dolomite and quartz are divided into pure methane (P-type), methane-bearing (M-type), aqueous (W-type), and solid bitumen-bearing (S-type) inclusions. The W-type inclusions within the quartz and buried dolomite homogenized between 107 °C and 223 °C. Furthermore, the trapping temperatures and pressures of the fluid (249 °C to 319 °C and 1619 bar to 2300 bar, respectively) are obtained from the intersections of the isochores of the P-type and the coeval W-type inclusions in the quartz. However, the burial history of the reservoir indicates that the maximum burial temperature did not exceed 230 °C. Thus, the generation of the natural gas was not caused solely by the burial of the dolomite reservoir. The results are also supported by the presence of paragenetic pyrobitumen and MVT lead-zinc ore. A coupled system of occasional invasion by hydrothermal fluids and burial of the reservoir may represent a new genetic model for natural gas accumulation in this gas field.

Delineation of karst terranes in complex environments: Application of modern developments in the wavelet theory and data mining

NASA Astrophysics Data System (ADS)

Alperovich, Leonid; Averbuch, Amir; Eppelbaum, Lev; Zheludev, Valery

2013-04-01

Karst areas occupy about 14% of the world land. Karst terranes of different origin have caused difficult conditions for building, industrial activity and tourism, and are the source of heightened danger for environment. Mapping of karst (sinkhole) hazards, obviously, will be one of the most significant problems of engineering geophysics in the XXI century. Taking into account the complexity of geological media, some unfavourable environments and known ambiguity of geophysical data analysis, a single geophysical method examination might be insufficient. Wavelet methodology as whole has a significant impact on cardinal problems of geophysical signal processing such as: denoising of signals, enhancement of signals and distinguishing of signals with closely related characteristics and integrated analysis of different geophysical fields (satellite, airborne, earth surface or underground observed data). We developed a three-phase approach to the integrated geophysical localization of subsurface karsts (the same approach could be used for following monitoring of karst dynamics). The first phase consists of modeling devoted to compute various geophysical effects characterizing karst phenomena. The second phase determines development of the signal processing approaches to analyzing of profile or areal geophysical observations. Finally, at the third phase provides integration of these methods in order to create a new method of the combined interpretation of different geophysical data. In the base of our combine geophysical analysis we put modern developments in the wavelet technique of the signal and image processing. The development of the integrated methodology of geophysical field examination will enable to recognizing the karst terranes even by a small ratio of "useful signal - noise" in complex geological environments. For analyzing the geophysical data, we used a technique based on the algorithm to characterize a geophysical image by a limited number of parameters

1D Thermal-Hydraulic-Chemical (THC) Reactive transport modeling for deep geothermal systems: A case study of Groß Schönebeck reservoir, Germany

NASA Astrophysics Data System (ADS)

Driba, D. L.; De Lucia, M.; Peiffer, S.

2014-12-01

Fluid-rock interactions in geothermal reservoirs are driven by the state of disequilibrium that persists among solid and solutes due to changing temperature and pressure. During operation of enhanced geothermal systems, injection of cooled water back into the reservoir disturbs the initial thermodynamic equilibrium between the reservoir and its geothermal fluid, which may induce modifications in permeability through changes in porosity and pore space geometry, consequently bringing about several impairments to the overall system.Modeling of fluid-rock interactions induced by injection of cold brine into Groß Schönebeck geothermal reservoir system situated in the Rotliegend sandstone at 4200m depth have been done by coupling geochemical modeling Code Phreeqc with OpenGeoSys. Through batch modeling the re-evaluation of the measured hydrochemical composition of the brine has been done using Quintessa databases, the results from the calculation indicate that a mineral phases comprising of K-feldspar, hematite, Barite, Calcite and Dolomite was found to match the hypothesis of equilibrium with the formation fluid, Reducing conditions are presumed in the model (pe = -3.5) in order to match the amount of observed dissolved Fe and thus considered as initial state for the reactive transport modeling. based on a measured composition of formation fluids and the predominant mineralogical assemblage of the host rock, a preliminary 1D Reactive transport modeling (RTM) was run with total time set to 30 years; results obtained for the initial simulation revealed that during this period, no significant change is evident for K-feldspar. Furthermore, the precipitation of calcite along the flow path in the brine results in a drop of pH from 6.2 to a value of 5.2 noticed over the simulated period. The circulation of cooled fluid in the reservoir is predicted to affect the temperature of the reservoir within the first 100 -150m from the injection well. Examination of porosity change in

Investigation of Submarine Groundwater Discharge and Preferential Groundwater Flow-paths in a Coastal Karst Area using towed Marine and Terrestrial Electrical Resistivity

NASA Astrophysics Data System (ADS)

O'connell, Y.; Daly, E.; Duffy, G.; Henry, T.

2012-12-01

Large volumes of groundwater, containing nutrients and contaminants enter the coastal waters of southern Galway Bay on the west coast of Ireland through submarine groundwater discharge (SGD). The SGD occurs through karstified Carboniferous limestone in a major karst region comprising the Burren and Gort Lowlands. The Carboniferous limestones have experienced extensive dissolution resulting in the development of an underground network of conduits and fissures that define a trimodal groundwater flow pattern across the region. Groundwater discharge to the sea in this area is exclusively intertidal and submarine. Storage in the karst is limited and typical winter rainfall conditions result in the karst system becoming saturated. Temporary lakes (turloughs) form in lowlying areas and act as large reservoirs which provide storage to enable the transmission of the large volumes of water in the system to the sea. Between 2010 and 2012, terrestrial and shallow marine geophysical surveying has been undertaken to investigate preferential groundwater flow-paths and SGD locations in order to quantify the groundwater-seawater interactions in this coastal karst system. A report into the groundwater system of this karst region following a major flood event proposed a conceptual conduit model defined by extensive water tracing, water level monitoring, hydrochemical sampling, geological mapping and drilling. Limited information about the dimensions of the conduits was known. Electrical resistivity tomography (ERT) profiling to depths of 100m below ground level, with multiple array configurations, has been carried out to investigate the modes of groundwater flow in to and out of both temporary and permanent freshwater lakes in the system. Towed dipole-dipole profiles have been recorded to investigate conduits beneath a permanent lake exhibiting a tidal influence despite its location 5.5 km from the seashore. The ERT data indicates significant variations in subsurface resistivities

Assessment of the potential for karst in the Rustler Formation at the WIPP site.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lorenz, John Clay

2006-01-01

This report is an independent assessment of the potential for karst dissolution in evaporitic strata of the Rustler Formation at the Waste Isolation Pilot Plant (WIPP) site. Review of the available data suggests that the Rustler strata thicken and thin across the area in depositional patterns related to lateral variations in sedimentary accommodation space and normal facies changes. Most of the evidence that has been offered for the presence of karst in the subsurface has been used out of context, and the different pieces are not mutually supporting. Outside of Nash Draw, definitive evidence for the development of karst inmore » the Rustler Formation near the WIPP site is limited to the horizon of the Magenta Member in drillhole WIPP-33. Most of the other evidence cited by the proponents of karst is more easily interpreted as primary sedimentary structures and the localized dissolution of evaporitic strata adjacent to the Magenta and Culebra water-bearing units. Some of the cited evidence is invalid, an inherited baggage from studies made prior to the widespread knowledge of modern evaporite depositional environments and prior to the existence of definitive exposures of the Rustler Formation in the WIPP shafts. Some of the evidence is spurious, has been taken out of context, or is misquoted. Lateral lithologic variations from halite to mudstone within the Rustler Formation under the WIPP site have been taken as evidence for the dissolution of halite such as that seen in Nash Draw, but are more rationally explained as sedimentary facies changes. Extrapolation of the known karst features in Nash Draw eastward to the WIPP site, where conditions are and have been significantly different for half a million years, is unwarranted. The volumes of insoluble material that would remain after dissolution of halite would be significantly less than the observed bed thicknesses, thus dissolution is an unlikely explanation for the lateral variations from halite to mudstone and

Hydraulic seals and their origin: Evidence from the stable isotope geochemistry of dolomites in the Middle Ordovician St. Peter Sandstone, Michigan basin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Winter, B.L.; Johnson, C.M.; Valley, J.W.

1995-01-01

Regionally extensive, overpressured natural gas pools within the St. Peter Sandstone (Middle Ordovician) of the Michigan basin are bounded by rock types that include 3-7-m-thick zones of low-permeability, low-porosity carbonates or diagenetically banded quartz sandstones. Replacive dolomite from an approximately 5-m-thick carbonate interval in the east-central portion of the Michigan basin has very low {delta}{sup 13}C values that systematically decrease from approximately -5% at the top to -10% (PDB) at the base. {delta}{sup 18}O values for the replacive dolomite also decrease systematically with depth from approximately 27 to 23% (SMOW). These data suggest an upward decrease in isotope exchange betweenmore » the replacive dolomitization fluid and the precursors rock (i.e., the system was rock dominated at the top of the carbonate interval), which implies upward, cross-formational movement of the dolomitizing fluid. Fluid-rock interaction modeling suggest that the dolomitizing fluid had a total dissolved carbon (TDC) content of approximately 4000 ppm and a {delta}{sup 13}C value of -27%, which indicates that the carbon was primarily derived from organic diagenesis. Sr isotope and major element data suggest that this dolomitizing fluid had a modified seawater origin. The {delta}{sup 13}C values of sandstone intervals from three locations in the central portion of the Michigan basin range from -9 to -4% and are relatively invariant at a particular locality; therefore, the TDC of the dolomitizing fluid in the central Michigan basin is interpreted to have contained only about 20-30% organic carbon. The fact that all dolomites analyzed in the St. Peter Sandstone have much lower {Delta}{sup 13}C values that carbonates in adjacent formations indicates that dolomitization and the formation of hydraulic seals were related to organic matter diagenesis.« less

Geology and ground water in Door County, Wisconsin, with emphasis on contamination potential in the Silurian dolomite

USGS Publications Warehouse

Sherrill, Marvin G.

1977-01-01

Door County, a recreational and fruit-growing area bordering Lake Michigan in northeastern Wisconsin, has had a long history of ground-water contamination from surface and near-surface sources. Contamination is most severe in late summer when fruit-canning operations and the influx of tourists create additional wastes. Silurian dolomite is the upper bedrock unit in the county and yields generally adequate supplies of very hard water with locally objectionable concentrations of iron and nitrate. Thin soil cover and well-fractured dolomitic bedrock give easy entry to ground-water contaminants throughout large parts of Door County. Many contaminants enter the dolomite by surface or near-surface seepage. There is little attenuation of contamination concentrations in the well-jointed dolomite, and contaminants may travel long distances underground in a relatively short time. The major source of ground-water contamination is bacteria, from individual waste-disposal systems, agricultural, industrial, and municipal wastes. Areas of the county underlain by contaminated zones include only a small percentage of the total ground-water system and are separated by large volumes of ground water free of contamination. (Woodard-USGS)

Depletion of E. coli in permeable pavement mineral aggregate storage and reuse systems.

PubMed

Myers, B R; Beecham, S; van Leeuwen, J A; Keegan, A

2009-01-01

Permeable pavement reservoirs provide an important opportunity for the harvesting and storage of stormwater for reuse. This research aims to determine whether storage in dolomite, calcite and quartzite mineral aggregates in the base course of a permeable pavement impacts on the survival of the pathogen indicator organism Escherichia coli (E. coli) in storage. The reasons for depletion were also investigated. Twelve model permeable pavement storage reservoirs were filled, in triplicate, with dolomite, calcite and quartzite. Three reservoirs contained no aggregate. After filling with pathogen spiked rainwater, the concentration of E. coli was examined for 22 days in the reservoirs. The reservoirs were then agitated to determine if there was E. coli present which was not in aqueous suspension. The results of the experiments show that there is no significant difference in the depletion of E. coli found in reservoirs without aggregate, and those filled with dolomite or calcite. The rate of depletion was found to be significantly lower in the quartzite filled reservoirs. Agitation of the reservoirs yielded increases in the aqueous concentration of E. coli in all reservoir types, suggesting that the bacteria are adhering to the surface of the mineral aggregate and to the reservoir walls.

Dolomitization of Quaternary reef limestones, Aitutaki, Cook Islands

USGS Publications Warehouse

Hein, J.R.; Gray, S.C.; Richmond, B.M.; White, L.D.

1992-01-01

The primary reef framework is considered to have been deposited during several highstands of sea level. Following partial to local recrystallization of the limestone, a signle episode of dolomitization occurred. Both tidal and thermal pumping drove large quantities of seawater through the porous rocks and perhaps maintained a wide mixing zone. However, the isotopic, geochemical and petrographic data do not clearly indicate the extent of seawater mixing. -from Authors

Coastal lithofacies and biofacies associated with syndepositional dolomitization and silicification (Draken Formation, Upper Riphean, Svalbard).

PubMed

Fairchild, I J; Knoll, A H; Swett, K

1991-01-01

The Draken Formation (120-250 m) of northeast Spitsbergen (Svalbard) forms part of a thick Upper Proterozoic carbonate platform succession. It consists predominantly of intraformational dolomitic conglomerates, with excellent textural preservation. Six main lithofacies were recognized in the field: quartz sandstones, stromatolitic mats, conglomerates with silicified intraclasts, dolostone conglomerates with desiccated mudrocks, oolitic/pisolitic grainstones and fenestral dolostones. A series of five main gradational biofacies were recognized from silicified (and rare calcified) microfossils. Biofacies 1 represents low-energy subtidal benthos (erect filaments) and plankton (acritarchs and vase-shaped microfossils) whereas biofacies 2 to 5 are microbial mat assemblages (with filamentous mat-builders, and associated dwellers and washed-in plankton) ranging from basal intertidal to high intertidal/supratidal. Colour values (a measure of the lightness of the colour shade) of sawn rock samples were quantified using a Munsell chart, and exhibit a pronounced variation (means of major groups varying from 4.0 to 5.95) across the spectrum of subtidal to supratidal sediments as inferred from other criteria. The lightening in progressively more exposed sediments is related to lowering of organic carbon contents, probably mainly by oxidation. Six types of early cement have been recognized. Calcite microspar (type 1) is common as a subtidal cement in many Proterozoic formations, whereas types 2 (subtidal isopachous fringes), 3 (subtidal hardground dolomicrite) and 4 (intertidal meniscus dolomicrite) are very similar to Phanerozoic examples except for their dolomitic mineralogy. Types 5 and 6 are complex and variable dolomite growths associated with expansion and replacive phenomena. They characterize the fenestral lithofacies and compare with modern supratidal cements. Consideration of diagenetic fabrics and truncation textures of intraclasts indicates that leaching

Coastal lithofacies and biofacies associated with syndepositional dolomitization and silicification (Draken Formation, Upper Riphean, Svalbard)

NASA Technical Reports Server (NTRS)

Fairchild, I. J.; Knoll, A. H.; Swett, K.

1991-01-01

The Draken Formation (120-250 m) of northeast Spitsbergen (Svalbard) forms part of a thick Upper Proterozoic carbonate platform succession. It consists predominantly of intraformational dolomitic conglomerates, with excellent textural preservation. Six main lithofacies were recognized in the field: quartz sandstones, stromatolitic mats, conglomerates with silicified intraclasts, dolostone conglomerates with desiccated mudrocks, oolitic/pisolitic grainstones and fenestral dolostones. A series of five main gradational biofacies were recognized from silicified (and rare calcified) microfossils. Biofacies 1 represents low-energy subtidal benthos (erect filaments) and plankton (acritarchs and vase-shaped microfossils) whereas biofacies 2 to 5 are microbial mat assemblages (with filamentous mat-builders, and associated dwellers and washed-in plankton) ranging from basal intertidal to high intertidal/supratidal. Colour values (a measure of the lightness of the colour shade) of sawn rock samples were quantified using a Munsell chart, and exhibit a pronounced variation (means of major groups varying from 4.0 to 5.95) across the spectrum of subtidal to supratidal sediments as inferred from other criteria. The lightening in progressively more exposed sediments is related to lowering of organic carbon contents, probably mainly by oxidation. Six types of early cement have been recognized. Calcite microspar (type 1) is common as a subtidal cement in many Proterozoic formations, whereas types 2 (subtidal isopachous fringes), 3 (subtidal hardground dolomicrite) and 4 (intertidal meniscus dolomicrite) are very similar to Phanerozoic examples except for their dolomitic mineralogy. Types 5 and 6 are complex and variable dolomite growths associated with expansion and replacive phenomena. They characterize the fenestral lithofacies and compare with modern supratidal cements. Consideration of diagenetic fabrics and truncation textures of intraclasts indicates that leaching

Dolomitization in Late Jurassic-Early Cretaceous Platform Carbonates (Berdiga Formation), Ayralaksa Yayla (Trabzon), NE Turkey

NASA Astrophysics Data System (ADS)

Yıldız, Merve; Ziya Kırmacı, Mehmet; Kandemir, Raif

2017-04-01

ABSTRACT Pontides constitute an E-W trending orogenic mountain belt that extends about 1100 km along the northern side of Turkey from the immediate east of Istanbul to the Georgian border at the east. Tectono-stratigraphically, the Pontides are divided into three different parts: Eastern, Central, and Western Pontides. The Eastern Pontides, including the studied area, comprise an area of 500 km in length and 100 km in width, extending along the southeast coast of the Black Sea from the Kizilirmak and Yesilirmak Rivers in the vicinity of Samsun to the Little Caucasus. This area is bordered by the Eastern Black Sea basin to the north and the Ankara-Erzincan Neotethyan suture zone to the south. The Late Jurassic-Early Cretaceous platform carbonates are widely exposed in E-W direction in the Eastern Pontides (NE Turkey). The Platform carbonates shows varying lithofacies changing from supratidal to platform margin reef laterally and vertically, and was buried until the end of Late Cretaceous. The studied Ayralaksa Yayla (Trabzon, NE Turkey) area comprises one of the best typical exposures of formation in northern zone of Eastern Pontides. In this area, the lower parts of the formation are pervasively dolomitized by fabric-destructive and fabric-preserving replacement dolomite which are Ca-rich and nonstoichiometric (Ca56-66Mg34-44). Replacement dolomites (Rd) are represented by D18O values of -19.0 to -4.2 (VPDB), D13C values of 4.4 to 2.1 \\permil (VPDB) and 87Sr/86Sr ratios of 0.70889 to 0.70636. Petrographic and geochemical data indicate that Rd dolomites are formed prior to compaction at shallow-moderate burial depths from Late Jurassic-Early Cretaceous seawater and/or partly modified seawater as a result of water/rock interaction and they were recrystallized at elevated temperatures during subsequent burial. In the subsequent diagenetic process during the Late Cretaceous when the region became a magmatic arc, as a result of interaction with Early Jurassic volcanic

Karst features detection and mapping using airphotos, DSMs and GIS techniques

NASA Astrophysics Data System (ADS)

Kakavas, M. P.; Nikolakopoulos, K. G.; Zagana, E.

2015-10-01

The aim of this work is to detect and qualify natural karst depressions in the Aitoloakarnania Prefecture, Western Greece, using remote sensing data in conjunction with the Geographical Information Systems - GIS. The study area is a part of the Ionian geotectonic zone, and its geological background consists of the Triassic Evaporates. The Triassic carbonate breccias where formed as a result of the tectonic and orogenetic setting of the external Hellenides and the diaper phenomena of the Triassic Evaporates. The landscape characterized by exokarst features closed depressions in the Triassic carbonate breccias. At the threshold of this study, an in situ observation was performed in order to identify dolines and swallow holes. The creation of sinkholes, in general, is based on the collapse of the surface layer due to chemical dissolution of carbonate rocks. In the current study airphotos stereopairs, DSMs and GIS were combined in order to detect and map the karst features. Thirty seven airphotos were imported in Leica Photogrammetry Suite and a stereo model of the study area was created. Then in 3D view possible karst features were detected and digitized. Those sites were verified during the in situ survey. ASTER GDEM, SRTM DEM, high resolution airphoto DSM created from the Greek Cadastral and a DEM from digitized contours from the 1/50,000 topographic were also evaluated in GIS environment for the automatic detection of the karst depressions. The results are presented in this study.

Effectiveness of airborne multispectral thermal data for karst groundwater resources recognition in coastal areas

NASA Astrophysics Data System (ADS)

Pignatti, Stefano; Fusilli, Lorenzo; Palombo, Angelo; Santini, Federico; Pascucci, Simone

2013-04-01

Currently the detection, use and management of groundwater in karst regions can be considered one of the most significant procedures for solving water scarcity problems during periods of low rainfall this because groundwater resources from karst aquifers play a key role in the water supply in karst areas worldwide [1]. In many countries of the Mediterranean area, where karst is widespread, groundwater resources are still underexploited, while surface waters are generally preferred [2]. Furthermore, carbonate aquifers constitute a crucial thermal water resource outside of volcanic areas, even if there is no detailed and reliable global assessment of thermal water resources. The composite hydrogeological characteristics of karst, particularly directions and zones of groundwater distribution, are not up till now adequately explained [3]. In view of the abovementioned reasons the present study aims at analyzing the detection capability of high spatial resolution thermal remote sensing of karst water resources in coastal areas in order to get useful information on the karst springs flow and on different characteristics of these environments. To this purpose MIVIS [4, 5] and TASI-600 [6] airborne multispectral thermal imagery (see sensors' characteristics in Table 1) acquired on two coastal areas of the Mediterranean area interested by karst activity, one located in Montenegro and one in Italy, were used. One study area is located in the Kotor Bay, a winding bay on the Adriatic Sea surrounded by high mountains in south-western Montenegro and characterized by many subaerial and submarine coastal springs related to deep karstic channels. The other study area is located in Santa Cesarea (Italy), encompassing coastal cold springs, the main local source of high quality water, and also a noticeable thermal groundwater outflow. The proposed study shows the preliminary results of the two airborne deployments on these areas. The preprocessing of the multispectral thermal imagery

Resetting of Mg isotopes between calcite and dolomite during burial metamorphism: Outlook of Mg isotopes as geothermometer and seawater proxy

NASA Astrophysics Data System (ADS)

Hu, Zhongya; Hu, Wenxuan; Wang, Xiaomin; Lu, Yizhou; Wang, Lichao; Liao, Zhiwei; Li, Weiqiang

2017-07-01

Magnesium isotopes are an emerging tool to study the geological processes recorded in carbonates. Calcite, due to its ubiquitous occurrence and the large Mg isotope fractionation associated with the mineral, has attracted great interests in applications of Mg isotope geochemistry. However, the fidelity of Mg isotopes in geological records of carbonate minerals (e.g., calcite and dolomite) against burial metamorphism remains poorly constrained. Here we report our investigation on the Mg isotope systematics of a dolomitized Middle Triassic Geshan carbonate section in eastern China. Magnesium isotope analysis was complemented by analyses of Sr-C-O isotopic compositions, major and trace element concentrations, and petrographic and mineralogical features. Multiple lines of evidence consistently indicated that post-depositional diagenesis of carbonate minerals occurred to the carbonate rocks. Magnesium isotope compositions of the carbonate rocks closely follow a mixing trend between a high δ26Mg dolomite end member and a low δ26Mg calcite end member, irrespective of sample positions in the section and calcite/dolomite ratio in the samples. By fitting the measured Mg isotope data using a two-end member mixing model, an inter-mineral Δ26Mgdolomite-calcite fractionation of 0.72‰ was obtained. Based on the experimentally derived Mg isotope fractionation factors for dolomite and calcite, a temperature of 150-190 °C was calculated to correspond to the 0.72‰ Δ26Mgdolomite-calcite fractionation. Such temperature range matches with the burial-thermal history of the local strata, making a successful case of Mg isotope geothermometry. Our results indicate that both calcite and dolomite had been re-equilibrated during burial metamorphism, and based on isotope mass balance of Mg, the system was buffered by dolomite in the section. Therefore, burial metamorphism may reset Mg isotope signature of calcite, and Mg isotope compositions in calcite should be dealt with caution in

Karst groundwater: a challenge for new resources

NASA Astrophysics Data System (ADS)

Bakalowicz, Michel

2005-03-01

Karst aquifers have complex and original characteristics which make them very different from other aquifers: high heterogeneity created and organised by groundwater flow; large voids, high flow velocities up to several hundreds of m/h, high flow rate springs up to some tens of m3/s. Different conceptual models, known from the literature, attempt to take into account all these particularities. The study methods used in classical hydrogeology—bore hole, pumping test and distributed models—are generally invalid and unsuccessful in karst aquifers, because the results cannot be extended to the whole aquifer nor to some parts, as is done in non-karst aquifers. Presently, karst hydrogeologists use a specific investigation methodology (described here), which is comparable to that used in surface hydrology. Important points remain unsolved. Some of them are related to fundamental aspects suc h as the void structure - only a conduit network, or a conduit network plus a porous matrix -, the functioning - threshold effects and non-linearities -, the modeling of the functioning - double or triple porosity, or viscous flow in conduits - and of karst genesis. Some other points deal with practical aspects, such as the assessment of aquifer storage capacity or vulnerability, or the prediction of the location of highly productive zones. Los acuíferos kársticos tienen características originales y complejas que los hacen muy diferentes de otros acuíferos: alta heterogeneidad creada y organizada por el flujo de agua subterránea, espacios grandes, velocidades altas de flujo de hasta varios cientos de m/h, manantiales con ritmo alto de flujo de hasta algunas decenas de m3/s. Diferentes modelos conceptuales que se conocen en la literatura tratan de tomar en cuenta todas estas particularidades. Los métodos de estudio usados en hidrogeología clásica- pozos, pruebas de bombeo y modelos distribuidos- son generalmente inválidos y no exitosos en acu

Unprotected karst resources in western Iran: the environmental impacts of intensive agricultural pumping on the covered karstic aquifer, a case in Kermanshah province

NASA Astrophysics Data System (ADS)

Taheri, Kamal; Taheri, Milad; Parise, Mario

2015-04-01

Bare and covered karst areas, with developed karstic aquifers, cover 35 percent of the Kermanshah province in western Iran. These aquifers are the vital sources for drinking and agricultural water supplies. Over the past decade, intensive groundwater use (exploitation) for irrigation imposed a significant impact on the carbonate environments. The huge amount of groundwater over-exploitations has been carried out and still goes on by local farmers in the absence of appropriate governance monitoring control. Increasing in water demands, for more intense crop production, is an important driving force toward groundwater depletion in alluvial aquifers. Progressive groundwater over-exploitations from underlying carbonate rocks have led to dramatic drawdown in alluvial aquifers and deep karst water tables. Detecting new sources of groundwater extractions and prohibiting the karst water utilization for agricultural use could be the most effective strategy to manage the sustainability of covered karst aquifers. Anthropogenic pressures on covered karst aquifers have magnified the drought impacts and caused dryness of most of the karst springs and deep wells. In this study, the combination of geophysical and geological studies was used to estimate the most intensively exploited agricultural zones of Islam Abad plain in the southwestern Kermanshah province using GIS. The results show that in the past decade a great number of deep wells were drilled through the overburden alluvial aquifer and reached the deep karst water resources. However, the difficulties involved in monitoring deep wells in covered karst aquifer were the main cause of karst water depletion. Overexploitation from both alluvial and karst aquifers is the main reason for drying out the Arkawazi, Sharafshah, Gawrawani karst springs, and the karst drinking water wells 1, 3 and 5 of Islam Abad city. Karst spring landscape destructions, fresh water supply deficit for inhabitants, decreasing of tourism and

Karst spring real time monitoring to identify the groundwater circulation in the feeding aquifer

NASA Astrophysics Data System (ADS)

Sappa, Giuseppe; Ferranti, Flavia; De Filippi, Francesco M.; Cardilo, Giulia

2017-04-01

About one quarter of the world's population is largely or entirely dependent on groundwater from karst systems. However, karst aquifers have specific hydraulic and hydrogeological characteristics that render them highly vulnerable to pollution from human activities. Intrinsic vulnerability of a karst aquifer takes account of the inherent geological, hydrological and hydrogeological characteristics of an area; however, it is independent of the nature of contaminants. Groundwater circulation is usually very rapidly as a function of high rainfall input. As consequence, in case of contamination, these systems are characterized by limited attenuation processes in the unsaturated zone. The analysis of karst spring responses to rainfall events, at the catchment scale, is one promising approach for groundwater flow characterization. Karst springs are, in fact, an important source of information in order to understand the circulation characteristics in such complex systems. The karst Pertuso Spring, located in the Upper Valley of Aniene River, is the main outlet of a large aquifer which is one of the most important water resource in the southeast part of Latium Region, Central Italy, used for drinking, agriculture and hydroelectric supplies. This paper deals with Pertuso Spring data collected from December 2014 to March 2016, using a multiparametric probe which directly interfaces with a data logger for real-time recording of hourly data. This instrument simultaneously measures up to 6 parameters (pH, groundwater level, temperature, electric conductivity, redox and dissolved oxygen). In particular, water temperature, electrical conductivity and rainfall data coming from meteorological stations have been studied to identify the groundwater circulation in the aquifer feeding Pertuso Spring. The study of the lag time between peak rainfall and peak of T and EC allow to highlight the seasonal vulnerability of this aquifer.

Regional dolomitization of the Waulsortian limestone in southeastern Ireland: Evidence of large-scale fluid flow driven by the Hercynian orogeny

NASA Astrophysics Data System (ADS)

Hitzman, M. W.; Allan, J. R.; Beaty, D. W.

1998-06-01

The Lower Carboniferous Waulsortian limestone has been affected by late diagenetic, regional burial dolomitization over an area of ˜7000 km2 extending 170 km northeastward from the Hercynian front. The dolostone is composed of two components: (1) a very fine crystalline replacive component, and (2) a coarse-crystalline, baroque component that fills vuggy porosity developed within the replacive dolostone. Fluid inclusions within the coarse-crystalline component of the regional dolostone indicate that the dolomitizing solutions were warm (˜100 °C) and moderately saline (10 13 wt% NaCl equivalent). The replacive dolomite displays systematic decreases in crystal size and degree of xenotopic texture northward. Both components of the regional dolostone display a regular northward increase in mean δ18O values; the replacive dolomite has 87Sr/86Sr values that decrease northward. These laterally variable characteristics suggest that regional dolomitization resulted from large-scale, north-directed fluid flow of heated brines developed in response to topographic uplift associated with collapse of the continental margin south of Ireland during the Hercynian (Variscan) orogeny.

Some new cave diving exploration results from Croatian karst area

NASA Astrophysics Data System (ADS)

Garasic, Davor; Garasic, Mladen

2017-04-01

In the recent years, several international cave diving expeditions took place in the Dinaric karst of Croatia. The objectives were conducting a new research of previously known karstic springs and also exploring new ones. The deepest karst cave in Croatia filled with water is Crveno jezero (lake) near Imotski town, with water depth of 281 meters and total cave depth of 528 meters. Volume of water in this cave is about 16 millions m3. Diving expeditions were held in 1997 and 1998.The deepest karst spring in the Dinaric karst of Croatia is Vrelo of Una River (with max discharge about 100 m3/s), where divers measured depth of -248 meters. Explorations were made in 2007 and 2016. Sinac spring in Pla\\vsko Polje has been dived to the depth of -203 meters. Cave diving was done in 1984, 1999, 2003, 2007 - 2016. Furthermore, very popular springs of the river Kupa (-155 m) in Gorski Kotar (explored since1995 till 2015), river Gacka (-105 in depth, 1150m in length) in Lika, explored from 1992 to 2016, river Cetina (-110 m in depth, 1300 m in length), cave diving explored from 2000 to 2016 in the Dalmatinska Zagora, Rumin Veliki spring (- 150 m in depth) in the Sinjska Krajina (explored and dived in 2006 and 2010), than rivers Krnjeza and Krupa in Ravni kotari with diving depths of over 100 meters (in 2004 and 2005) and so on. Along the Adriatic coast in Croatia there are many deep and long submarine springs (vrulje), ie. caves under seawater springs. called - vruljas for example Vrulja Zecica with over 900 meters ine length and Vrulja Modrič with completely flooded cave channels that extend over 2300 meters in length. Cave diving was conducted from 2010 to 2016. Vrulja Dubci is also worth mentioning (dived and explored in 2000), 161 meters deep and so on. Tectonic activity plays a dominant role in the creation and function of these caves. Geological, hydrogeological and lithostratigraphic conditions are also very important in speleogenesis of these caves in Croatian karst

Intrinsic vulnerability, hazard and risk mapping for karst aquifers: A case study

NASA Astrophysics Data System (ADS)

Mimi, Ziad A.; Assi, Amjad

2009-01-01

SummaryGroundwater from karst aquifers is among the most important resources of drinking water supply of the worldwide population. The European COST action 620 proposed a comprehensive approach to karst groundwater protection, comprising methods of intrinsic and specific vulnerability mapping, hazard and risk mapping. This paper presents the first application of all components of this European approach to the groundwater underlying the Ramallah district, a karst hydrogeology system in Palestine. The vulnerability maps which were developed can assist in the implementation of groundwater management strategies to prevent degradation of groundwater quality. Large areas in the case study area can be classified as low or very low risk area corresponding to the pollution sources due to the absence of hazards and also due to low vulnerabilities. These areas could consequently be interesting for future development as they are preferable in view of ground water protection.

Reservoir characterization of the Upper Jurassic geothermal target formations (Molasse Basin, Germany): role of thermofacies as exploration tool

NASA Astrophysics Data System (ADS)

Homuth, S.; Götz, A. E.; Sass, I.

2015-06-01

The Upper Jurassic carbonates of the southern German Molasse Basin are the target of numerous geothermal combined heat and power production projects since the year 2000. A production-orientated reservoir characterization is therefore of high economic interest. Outcrop analogue studies enable reservoir property prediction by determination and correlation of lithofacies-related thermo- and petrophysical parameters. A thermofacies classification of the carbonate formations serves to identify heterogeneities and production zones. The hydraulic conductivity is mainly controlled by tectonic structures and karstification, whilst the type and grade of karstification is facies related. The rock permeability has only a minor effect on the reservoir's sustainability. Physical parameters determined on oven-dried samples have to be corrected, applying reservoir transfer models to water-saturated reservoir conditions. To validate these calculated parameters, a Thermo-Triaxial-Cell simulating the temperature and pressure conditions of the reservoir is used and calorimetric and thermal conductivity measurements under elevated temperature conditions are performed. Additionally, core and cutting material from a 1600 m deep research drilling and a 4850 m (total vertical depth, measured depth: 6020 m) deep well is used to validate the reservoir property predictions. Under reservoir conditions a decrease in permeability of 2-3 magnitudes is observed due to the thermal expansion of the rock matrix. For tight carbonates the matrix permeability is temperature-controlled; the thermophysical matrix parameters are density-controlled. Density increases typically with depth and especially with higher dolomite content. Therefore, thermal conductivity increases; however the dominant factor temperature also decreases the thermal conductivity. Specific heat capacity typically increases with increasing depth and temperature. The lithofacies-related characterization and prediction of reservoir

Picos de Europa National and Regional parks (Northern Spain): the karst underground landscape

NASA Astrophysics Data System (ADS)

Ballesteros, Daniel; Jiménez-Sánchez, Montserrat; Rodríguez-Rodríguez, Laura; José Domínguez-Cuesta, María; Meléndez-Asensio, Mónica; García-Sansegundo, Joaquín

2015-04-01

Karst caves represent an environmental with a high value from the Geoheritage and Geodiversity points of view given by hidden underground landscape practically reserved to the speleologists. Nevertheless, cave surveys, 3d models of caves and DEMs, and pictures can be used to approach the endokarst geoheritage characterization. The Picos de Europa National and Regional parks include the 14% of World's Deepest Caves (>1 km depth); moreover these parks shows a high environmental value related with seven protection figures: Biosphere Reserve, Special Protection Area, the Site of Community Importance, and four Natural Monument. The aim of this work is to present the Geoheritage values of the underground landscape of the Picos de Europa National and Regional parks. These parks involve several alpine karst massifs up to 700 km2 and 2,600 m asl, as the Picos de Europa mountains (declared Global Geosite by its geomorphological interest), the Mampodre Massif, and the Peñas Pintas and Yordas peaks (sited in Riaño dam area). The alpine karst involves a large underground landscape formed by more than 3,700 epigenic caves with 403 km of conduits. The 95 % of the cave conduits are located in the Picos de Europa mountains and correspond to caves up to 18.9 km length and 1.6 km depth; the 5 % of cave conduits are sited in other small karst areas and include caves up to 1.5 km length and 200 m depth. The karst caves present high natural, scientific and cultural values. The natural value corresponds to the singularity and the spectacular vertical development of the caves and a very high Geodiversity of cave features. The karst shows a high concentration of deep caves (81 caves deeper than 500 m) that is twice higher than the concentration of other karst areas, as Arabika Massif (Western Caucasus). The natural value is mainly related to the presence of geomorphological and hydrogeological features, highlighting high vadose canyons and shafts, old phreatic and epiphreatic conduits

Karstification at Beskonak dam site and reservoir area, southern Turkey

DOE Office of Scientific and Technical Information (OSTI.GOV)

Degirmenci, M.

1993-10-01

Beskonak dam and hydroelectric power plant are planned to be constructed on the Koepruecay river, 40 km east of the Antalya city. In the dam site and reservoir area, Koepruecay Conglomerates of Miocene age and the Beskonak Formation (sandstone-claystone) alternating with each other crop out vertically. Koepruecay conglomerates, with the components of limestone fragments and carbonate texture, are karstic and permeable, whereas the Beskonak Formation is impermeable. At the northern edge of the reservoir area, the Olukkoeprue karst springs discharge at a minimum of 30 m{sup 3}/s. These springs discharge mainly through vertical and subvertical joint systems. Intensive superficial karstificationmore » developed along the joint systems and the terrane reveals columns of rocks, called {open_quotes}fairy chimneys.{close_quotes} Olukkoeprue springs represent the discharge point for a large and continuous system of underground solution cavities. In the Koepruecay basin, there are numerous karstic features within the conglomerates. Within the reservoir area, Kurukoeprue cave, with a length of 530 m, is an example of these caves developed within the conglomerates. In some parts of the reservoir area, where the groundwater level is lower than the surface-river elevation, a highly developed karstification zone is present within the fluctuation range of groundwater between depths of 40 and 50 m. The above-mentioned Kurukoeprue cave is an active cave developed in the dam site and its vicinity. The solution conduits developed along the system of mostly vertical fractures and joints are interconnected, thus giving rise to a three-dimensional conduit network. On the other hand, a majority of these conduits have clay and calcite filling materials. Karstification in the dam site varies with depths exponentially. Data suggest that karstification has a vertical extention as deep as -220 m. 4 refs., 9 figs.« less

A preliminary study on the feedback of heat transfer on groundwater flow in a Karst geothermal field

NASA Astrophysics Data System (ADS)

Kong, Y.; Pang, Z.; Hu, S.; Pang, J.; Shao, H.; Kolditz, O.

2014-12-01

In deep sedimentary basins, groundwater movement can significantly alter the heat flow pattern. At the same time, heat flux induced temperature change can reversely determine the flow regime through density dependent convection process. In Karst aquifers, the heterogeneity in the carbonate rocks makes the identification of this feedback much more complex. In this work, a preliminary study has been made on this feedback in Xiongxian geothermal field. The Karst aquifer in our site has an average thickness of about 1000 m, and is overlaid by over 400 m of quaternary clay, and subsequently 600 m of Neogene sandstone. Geothermal energy has been exploited in the site for space heating. During the heating period from Nov 15th to Mar 15th every year, hot water was extracted from the aquifer and re-injected after the heat extraction. A detailed temperature logging has been carried out in the field, both before and after the heating period, with the consideration that temperature distribution will be affected by the re-injection of cold water. The vertical distribution of temperature in the cap rock shows a constant positive gradient over depth. The heat flux at different locations has been calculated respectively. It is found to decline from southwest to northeast, with the highest value of 113.9 mW/m2 to the lowest of 80.6 mW/m2. This pattern can be well explained by the tectonic features. More interestingly, two inflection points appear on the temperature profile of the Karst layer, revealing strong influence from the cold re-injection water. Also, a 3℃ temperature difference was observed in the June and October measurement, which is related to the reservoir recovery. Currently, a 3D numerical model is being constructed, using the open-source software OpenGeoSys. Heat transport process is coupled with density dependent flow in a monolithic approach, to simulate both heat conduction and groundwater convection. This model will help to quantify the feedback from heat

Structural control in sinkhole development and speleogenesis: a case study from the High Murge karst landscape (Apulia, Italy)

NASA Astrophysics Data System (ADS)

Pepe, M.; Parise, M.

2012-04-01

The Murge plateau is the main karst sector of Apulia, an almost entirely carbonate region of SE Italy. It can be, in turn, subdivided into two sectors: High Murge, the inland plateau, where remnants of an ancient tropical karst are still recognizable; and Low Murge, closer to the Adriatic Sea, with smoother karst morphologies and landforms, but, at the same time, hosting some of the longest underground karst system in the region (Parise, 1998, 2006). Even though showing low energy relief, the landscape of High Murge is very articulated when examined at greater detail, with several interesting karst features. Among these, sinkholes are definitely the most significant, showing a variety of typologies and, at the same time, a high frequency, both as individual features and as coalescent landforms, giving origin to more complex depressions (Parise, 2011). Previous studies carried out in the High Murge through morphometric analysis of the main sinkholes identified on the 1:25,000 scale topographic maps from the Italian Army Geographical Institute indicated their likely genesis in a low relief cockpit karst (Sauro, 1991). Over such landscape, developed in Upper Tertiary, a hydrographic pattern was superimposed, that partly opened some of the depressions, also dismantling sectors of the karst relief and producing talus deposits (Caldara & Ciaranfi, 1988). In the present work we take into consideration the southern countryside of Ruvo di Puglia. Choice of the area, which extends over 15 km2, was dictated by presence of a high number of sinkholes, and of several important caves with prevailing vertical development, including the deepest pit ever explored in Apulia (Grave della Ferratella, depth - 320 m). The cave is nowadays not accessible, due to clogging caused by land use changes during the 80's. Based upon extensive field surveys and interpretation of multi-year aerial photographs (time range 1955-2003), integrated by surveying in selected caves, the main hydro

Sedimentation in Rio La Venta Canyon in Netzahualcoyotl Reservoir, Chiapas, Mexico

NASA Astrophysics Data System (ADS)

de La Fuente, J. A.; Lisle, T.; Velasquez, J.; Allison, B. L.; Miller, A.

2002-12-01

Sedimentation of Rio La Venta as it enters the Netzahualcoyotl Reservoir in Chiapas, Mexico, threatens a unique part of the aquatic ecosystem. Rio La Venta enters the reservoir via a narrow canyon about 16 km long with spectacular, near-vertical limestone bluffs up to 320 m high and inhabited by the flora and fauna of a pristine tropical forest. Karst terrain underlies most of the Rio La Venta basin in the vicinity of the reservoir, while deeply weathered granitic terrain underlies the Rio Negro basin, and the headwaters of the Rio La Venta to the south. The Rio Negro joins Rio La Venta 3 km downstream of the upper limit of the reservoir and delivers the bulk of the total clastic sediment (mostly sand and finer material). The canyon and much of the contributing basin lie within the Reserva de la Biosfera, Selva El Ocote, administered by the Comision Nacional de Areas Naturales Protegidas, part of the Secretaria de Medioambiente y Recursos Naturales. The Klamath National Forest Forest has cooperated with its Mexican counterparts since 1993 in natural resource management, neo-tropical bird inventories, wildfire management, and more recently in watershed analyses. Rates of sedimentation are estimated from bathymetric surveys conducted in March, 2002. A longitudinal profile down the inundated canyon during a high reservoir level shows an inflection from a slope of 0.0017 to one of 0.0075 at 7.2 km downstream of the mouth of Rio Negro. The bed elevation at this point corresponds to the lowest reservoir level, suggesting that the gentler sloping bed upstream is formed by fluvial processes during drawdown and that downstream by pluvial processes. Using accounts that boats could access Rio Negro during low water levels in 1984, we estimate an annual sedimentation rate of roughly 3 million cubic meters per year. This suggests that boats might no longer be able to access the most spectacular section of canyon upstream of Rio Negro within a decade, depending on how the

Common Ion Effects In Zeoponic Substrates: Dissolution And Cation Exchange Variations Due to Additions of Calcite, Dolomite and Wollastonite

NASA Technical Reports Server (NTRS)

Beiersdorfer, R. E.; Ming, D. W.; Galindo, C., Jr.

2003-01-01

c1inoptilolite-rich tuff-hydroxyapatite mixture (zeoponic substrate) has the potential to serve as a synthetic soil-additive for plant growth. Essential plant macro-nutrients such as calcium, phosphorous, magnesium, ammonium and potassium are released into solution via dissolution of the hydroxyapatite and cation exchange on zeolite charged sites. Plant growth experiments resulting in low yield for wheat have been attributed to a Ca deficiency caused by a high degree of cation exchange by the zeolite. Batch-equilibration experiments were performed in order to determine if the Ca deficiency can be remedied by the addition of a second Ca-bearing, soluble, mineral such as calcite, dolomite or wollastonite. Variations in the amount of calcite, dolomite or wollastonite resulted in systematic changes in the concentrations of Ca and P. The addition of calcite, dolomite or wollastonite to the zeoponic substrate resulted in an exponential decrease in the phosphorous concentration in solution. The exponential rate of decay was greatest for calcite (5.60 wt. % -I), intermediate for wollastonite (2.85 wt.% -I) and least for dolomite (1.58 wt.% -I). Additions of the three minerals resulted in linear increases in the calcium concentration in solution. The rate of increase was greatest for calcite (3.64), intermediate for wollastonite (2.41) and least for dolomite (0.61). The observed changes in P and Ca concentration are consistent with the solubilities of calcite, dolomite and wollastonite and with changes expected from a common ion effect with Ca. Keywords: zeolite, zeoponics, common-ion effect, clinoptilolite, hydroxyapatite

Vulnerability of karst aquifers to agricultural contaminants: A case study in the Pennyroyal Plateau of Kentucky

USDA-ARS?s Scientific Manuscript database

Karst landscapes are common in many agricultural regions in the US. Well-developed karst landscapes are characterized by shallow soils, sinkholes, sinking streams, underground conduits, and springs. In these landscapes surface runoff is minimal and most recharge enters the subsurface relatively quic...

[Distribution of 137Cs and relative influencing factors on typical karst sloping land].

PubMed

Zhang, Xiao-Nan; Wang, Ke-Lin; Zhang, Wei; Chen, Hong-Song; He, Xun-Yang; Zhang, Xin-Bao

2009-11-01

Based on the field survey and the analysis of a large number of soil samples, the distribution of 137 Cs and its influencing factors were studied using 137 Cs tracer technology on typical karst sloping land. The results indicate that the distribution of 137 Cs in soil profile in karst areas show the similar characteristics as that in non-karst areas, fitted an exponential pattern in forest soils and a uniform pattern in cultivated soils. In the sinkhole points in karst areas, 137 Cs exists in deep soil layers and its specific activity vary from 1.7 to 3.3 Bq/kg in soil layers above 45cm, suggesting the existing soil around karst sinkhole is mainly formed by the accumulation of erosion materials. The 137 Cs specific activity in the soil from two rock cracks are 16.8 Bq/kg and 37.6 Bq/kg respectively, which are much higher than that in the soil around the rock, this phenomenon indicates that bare rock is an important influencing factor for 137 Cs spatial movement. With the increment of altitude, the 137 Cs area activity exhibits an irregular fluctuation and evident spatial heterogeneity. On the forest land, the 137 Cs area activities which range from 299.4 to 1 592.6 Bq/m2 are highly positively correlated with the slope gradient and positively correlated with the altitude; while on the cultivated land, the 137 Cs area activities which range from 115.8 to 1478.6 Bq/m2 are negatively correlated with the slope gradient but negatively correlated with the altitude. Topography, geomorphology and human disturbance intensity are the key factors influencing 137 Cs spatial distribution.

Comparison of Recharge Estimation Methods During a Wet Period in a Karst Aquifer.

PubMed

Guardiola-Albert, Carolina; Martos-Rosillo, Sergio; Pardo-Igúzquiza, Eulogio; Durán Valsero, Juan José; Pedrera, Antonio; Jiménez-Gavilán, Pablo; Liñán Baena, Cristina

2015-01-01

Management of water resources, implying their appropriate protection, calls for a sound evaluation of recharge. Such assessment is very complex in karst aquifers. Most methods are developed for application to detrital aquifers, without taking into account the extraordinary heterogeneity of porosity and permeability of karst systems. It is commonly recommended to estimate recharge using multiple methods; however, differences inherent to the diverse methods make it difficult to clarify the accuracy of each result. In this study, recharge was estimated in a karst aquifer working in a natural regime, in a Mediterranean-type climate, in the western part of the Sierra de las Nieves (southern Spain). Mediterranean climate regions are characterized by high inter-annual rainfall variability featuring long dry periods and short intense wet periods, the latter constituting the most important contribution to aquifer water input. This paper aims to identify the methods that provide the most plausible range of recharge rate during wet periods. Six methods were tested: the classical method of Thornthwaite-Mather, the Visual Balan code, the chloride balance method, and spatially distributed methods such as APLIS, a novel spatiotemporal estimation of recharge, and ZOODRM. The results help determine valid methods for application in the rest of the unit of study and in similar karst aquifers. © 2014, National Ground Water Association.

Reservoir transport and poroelastic properties from oscillating pore pressure experiments

NASA Astrophysics Data System (ADS)

Hasanov, Azar K.

Hydraulic transport properties of reservoir rocks, permeability and storage capacity are traditionally defined as rock properties, responsible for the passage of fluids through the porous rock sample, as well as their storage. The evaluation of both is an important part of any reservoir characterization workflow. Moreover, permeability and storage capacity are main inputs into any reservoir simulation study, routinely performed by reservoir engineers on almost any major oil and gas field in the world. An accurate reservoir simulation is essential for production forecast and economic analysis, hence the transport properties directly control the profitability of the petroleum reservoir and their estimation is vital for oil and gas industry. This thesis is devoted to an integrated study of reservoir rocks' hydraulic, streaming potential and poroelastic properties as measured with the oscillating pore pressure experiment. The oscillating pore pressure method is traditionally used to measure hydraulic transport properties. We modified the method and built an experimental setup, capable of measuring all aforementioned rock properties simultaneously. The measurements were carried out for four conventional reservoir-rock quality samples at a range of oscillation frequencies and effective stresses. An apparent frequency dependence of permeability and streaming potential coupling coefficient was observed. Measured frequency dispersion of drained poroelastic properties indicates an intrinsically inelastic nature of the porous mineral rock frame. Standard Linear Model demonstrated the best fit to the experimental dispersion data. Pore collapse and grain crushing effects took place during hydrostatic loading of the dolomitic sample and were observed in permeability, coupling coefficient and poroelastic measurements simultaneously. I established that hydraulically-measured storage capacities are overestimated by almost one order of magnitude when compared to elastically

Quantification of frequency-components contributions to the discharge of a karst spring

NASA Astrophysics Data System (ADS)

Taver, V.; Johannet, A.; Vinches, M.; Borrell, V.; Pistre, S.; Bertin, D.

2013-12-01

Karst aquifers represent important underground resources for water supplies, providing it to 25% of the population. Nevertheless such systems are currently underexploited because of their heterogeneity and complexity, which make work fields and physical measurements expensive, and frequently not representative of the whole aquifer. The systemic paradigm appears thus at a complementary approach to study and model karst aquifers in the framework of non-linear system analysis. Its input and output signals, namely rainfalls and discharge contain information about the function performed by the physical process. Therefore, improvement of knowledge about the karst system can be provided using time series analysis, for example Fourier analysis or orthogonal decomposition [1]. Another level of analysis consists in building non-linear models to identify rainfall/discharge relation, component by component [2]. In this context, this communication proposes to use neural networks to first model the rainfall-runoff relation using frequency components, and second to analyze the models, using the KnoX method [3], in order to quantify the importance of each component. Two different neural models were designed: (i) the recurrent model which implements a non-linear recurrent model fed by rainfalls, ETP and previous estimated discharge, (ii) the feed-forward model which implements a non-linear static model fed by rainfalls, ETP and previous observed discharges. The first model is known to better represent the rainfall-runoff relation; the second one to better predict the discharge based on previous discharge observations. KnoX method is based on a variable selection method, which simply considers values of parameters after the training without taking into account the non-linear behavior of the model during functioning. An amelioration of the KnoX method, is thus proposed in order to overcome this inadequacy. The proposed method, leads thus to both a hierarchization and a quantification

Simple, simultaneous gravimetric determination of calcite and dolomite in calcareous soils

USDA-ARS?s Scientific Manuscript database

Literature pertaining to determination of calcite and dolomite is not modern and describes slow methods that require expensive specialized apparatus. The objective of this paper was to describe a new method that requires no specialized equipment. Linear regressions and correlation coefficients for...

[Variation Characteristics and Sources of Heavy Metals in an Urban Karst Groundwater System during Rainfall Event].

PubMed

Ren, Kun; Yang, Ping-heng; Jiang, Ze-li; Wang, Zun-bo; Shi, Yang; Wang, Feng-kang; Li, Xiao-chun

2015-04-01

The groundwater discharge and heavy metal concentrations (Mn, Pb, Cu and As) at the outlet of Nanshan Laolongdong karst subterranean river, located at the urban region in Chongqing, were observed during the rainfall events. Analysis of flow and concentrations curves was employed to study their responses to the rainfall events and explore the internal structure of karst hydrological system. Principal component analysis (PCA) and measurements were used to identify the sources of heavy metals during rainfall. The result showed that the discharge and concentrations of the heavy metals responded promptly to the rainfall event. The variation characteristics of flow indicated that Laolongdong subterranean river system belonged to a karst hydrological system including fractures together with conduits. Urban surface runoff containing large amounts of Mn, Pb and Cu went directly to subterranean river via sinkholes, shafts and karst windows. As a result, the peak concentrations of contaminants (Mn, Pb and Cu) flowed faster than those of discharge. The major sources of water pollution were derived from urban surface runoff, soil and water loss. Cave dripwater and rainwater could also bring a certain amount of Mn, Pb and As into the subterranean river. Urban construction in karst areas needs scientific and rational design, perfect facilities and well-educated population to prevent groundwater pollution from the source.

Structural characterization and numerical simulations of flow properties of standard and reservoir carbonate rocks using micro-tomography

NASA Astrophysics Data System (ADS)

Islam, Amina; Chevalier, Sylvie; Sassi, Mohamed

2018-04-01

With advances in imaging techniques and computational power, Digital Rock Physics (DRP) is becoming an increasingly popular tool to characterize reservoir samples and determine their internal structure and flow properties. In this work, we present the details for imaging, segmentation, as well as numerical simulation of single-phase flow through a standard homogenous Silurian dolomite core plug sample as well as a heterogeneous sample from a carbonate reservoir. We develop a procedure that integrates experimental results into the segmentation step to calibrate the porosity. We also look into using two different numerical tools for the simulation; namely Avizo Fire Xlab Hydro that solves the Stokes' equations via the finite volume method and Palabos that solves the same equations using the Lattice Boltzmann Method. Representative Elementary Volume (REV) and isotropy studies are conducted on the two samples and we show how DRP can be a useful tool to characterize rock properties that are time consuming and costly to obtain experimentally.

Coho Salmon populations in the Karst landscape of north Prince of Wales Island, southeast Alaska.

Treesearch

M.D. Bryant; D.N. Swanston

1998-01-01

Karst topography is a unique and distinct landscape and its geology may have important implications for salmon productivity in streams. The relationship between salmonid communities and water chemistry and the influence of habitat was examined in a set of streams on north Prince of Wales Island, southeast Alaska. Streams in karst landscapes showed higher alkalinities (...

The cost of karst subsidence and sinkhole collapse in the United States compared with other natural hazards

USGS Publications Warehouse

Weary, David J.

2015-01-01

Rocks with potential for karst formation are found in all 50 states. Damage due to karst subsidence and sinkhole collapse is a natural hazard of national scope. Repair of damage to buildings, highways, and other infrastructure represents a significant national cost. Sparse and incomplete data show that the average cost of karst-related damages in the United States over the last 15 years is estimated to be at least $300,000,000 per year and the actual total is probably much higher. This estimate is lower than the estimated annual costs for other natural hazards; flooding, hurricanes and cyclonic storms, tornadoes, landslides, earthquakes, or wildfires, all of which average over $1 billion per year. Very few state organizations track karst subsidence and sinkhole damage mitigation costs; none occurs at the Federal level. Many states discuss the karst hazard in their State hazard mitigation plans, but seldom include detailed reports of subsidence incidents or their mitigation costs. Most State highway departments do not differentiate karst subsidence or sinkhole collapse from other road repair costs. Amassing of these data would raise the estimated annual cost considerably. Information from insurance organizations about sinkhole damage claims and payouts is also not readily available. Currently there is no agency with a mandate for developing such data. If a more realistic estimate could be made, it would illuminate the national scope of this hazard and make comparison with costs of other natural hazards more realistic.

Transport of free and particulate-associated bacteria in karst

USGS Publications Warehouse

Mahler, B.J.; Personne, J.-C.; Lods, G.F.; Drogue, C.

2000-01-01

Karst aquifers, because of their unique hydrogeologic characteristics, are extremely susceptible to contamination by pathogens. Here we present the results of an investigation of contamination of a karst aquifer by fecal indicator bacteria. Two wells intercepting zones with contrasting effective hydraulic conductivities, as determined by pump test, were monitored both during the dry season and in response to a rain event. Samples were also collected from the adjacent ephemeral surface Stream, which is known to be impacted by an upstream wastewater treatment plant after rainfall. Whole water and suspended sediment samples were analyzed for fecal coliforms and enterococci. During the dry season, pumping over a 2-day period resulted in increases in concentrations of fecal coliforms to greater than 10,000 CFU/100 ml in the high-conductivity well; enterococci and total suspended solids also increased, to a lesser degree. Toward the end of the pumping period, as much as 50% of the fecal coliforms were associated with suspended sediment. Irrigation of an up-gradient pine plantation with primary-treated wastewater is the probable source of the bacterial contamination. Sampling after a rain event revealed the strong influence of water quality of the adjacent Terrieu Creek on the ground water. Bacterial concentrations in the wells showed a rapid response to increased concentrations in the surface water, with fecal coliform concentrations in ground water ultimately reaching 60,000 CFU/100 ml. Up to 100% of the bacteria in the ground water was associated with suspended sediment at various times. The results of this investigation are evidence of the strong influence of surface water on ground water in karst terrain, including that of irrigation water. The large proportion of bacteria associated with particulates in the ground Water has important implications for public health, as bacteria associated with particulates may be more persistent and more difficult to inactivate. The

Hydrogen sulfide capture by limestone and dolomite at elevated pressure. 1: Sorbent performance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yrjas, K.P.; Zevenhoven, C.A.P.; Hupa, M.M.

1996-01-01

Sulfur emission control in fossil fuel gasification plants implies the removal of H{sub 2}S from the product gas either inside the furnace or in the gas clean-up system. In a fluidized-bed gasifier, in-bed sulfur capture can be accomplished by adding a calcium-based sorbent such as limestone or dolomite to the bend and removing the sulfur from the system with the bottom ash in the form of CaS. This work describes the H{sub 2}S uptake by a set of physically and chemically different limestones and dolomites under pressurized conditions, typically for those in a pressurized fluidized-bed gasifier (2 MPa, 950 C).more » The tests were done with a pressurized thermobalance at two p{sub CO{sub 2}} levels. Thus, the sulfidation of both calcined and uncalcined sorbents could be analyzed. The effect of p{sub H{sub 2}S} was also investigated for uncalcined limestones and half-calcined dolomites. The results are presented as conversion of CaCO{sub 3} or CaO to CaS vs time plots. The results are also compared with the sulfur capture performance of the same sorbents under pressurized combustion conditions.« less

Quantitative Analysis of Karst Conduit Structure Parameters and Hydraulic Parameters Based on Tracer Test

NASA Astrophysics Data System (ADS)

Qiang, Z.; Zhiqiang, Z.; Xu, M.; Jinyu, S.; Jihong, Q.

2017-12-01

The Old Town of Lijiang is famous as the world cultural heritage since 1997, while characterized by its ancient buildings and natural scenery, water is the soul of the town. Around Heilongtan Springs, there are a large quantity of springs at the Old Town of Lijiang , which is an important part of the World Cultural Heritage. Heilongtan Springs is 2420m above the sea level, the annual variation of the flow rate varies greatly (0 8042 x 104 m3 / year). Recharge area Jiuzihai depressions is 6km long, 3km wide and 2800m above sea level, as main karst water recharge area karst funnel and the sink hole are developing on this planation surface, in the research area medium to thick layers of limestone made up Beiya formation (T2b) of Triassic system distributed widely, karst is strongly developed and the fissure caves water occurrence. In order to exploring the application of tracer test in karst hydrogeology, a tracer test was conducted from Jiuzihai depressions to Ganze Spring. Based on the hydrogeological conditions in the study area, tracer test was used for analysis of groundwater connectivity and flow field characteristics, quantitative analysis of Tracer Breakthrough Curves (BTC) with code Qtracer2. The results demonstated that there are hydraulic connection between Jiuzihai depressions with Ganze Spring, and there are other karst conduits in this area. The longitudinal dispersivity coefficient is 0.24 m2/s, longitudinal dispersivity is 12.06m, flow-channel volume is 3.08×104 m3, flow-channel surface area is 3.27×107m2, mean diameter is 1.42m, Reynolds number is 25187, Froude number is 0.0061, respectively. The groundwater in this area is in a slow turbulent state. The results are of great significance to understand the law of groundwater migration, establish groundwater quality prediction model and exploit karst water resources effectively.

Development of a process-oriented vulnerability concept for water travel time in karst aquifers-case study of Tanour and Rasoun springs catchment area.

NASA Astrophysics Data System (ADS)

Hamdan, Ibraheem; Sauter, Martin; Ptak, Thomas; Wiegand, Bettina; Margane, Armin; Toll, Mathias

2017-04-01

Key words: Karst aquifer, water travel time, vulnerability assessment, Jordan. The understanding of the groundwater pathways and movement through karst aquifers, and the karst aquifer response to precipitation events especially in the arid to semi-arid areas is fundamental to evaluate pollution risks from point and non-point sources. In spite of the great importance of the karst aquifer for drinking purposes, karst aquifers are highly sensitive to contamination events due to the fast connections between the land-surface and the groundwater (through the karst features) which is makes groundwater quality issues within karst systems very complicated. Within this study, different methods and approaches were developed and applied in order to characterise the karst aquifer system of the Tanour and Rasoun springs (NW-Jordan) and the flow dynamics within the aquifer, and to develop a process-oriented method for vulnerability assessment based on the monitoring of different multi-spatially variable parameters of water travel time in karst aquifer. In general, this study aims to achieve two main objectives: 1. Characterization of the karst aquifer system and flow dynamics. 2. Development of a process-oriented method for vulnerability assessment based on spatially variable parameters of travel time. In order to achieve these aims, different approaches and methods were applied starting from the understanding of the geological and hydrogeological characteristics of the karst aquifer and its vulnerability against pollutants, to using different methods, procedures and monitored parameters in order to determine the water travel time within the aquifer and investigate its response to precipitation event and, finally, with the study of the aquifer response to pollution events. The integrated breakthrough signal obtained from the applied methods and procedures including the using of stable isotopes of oxygen and hydrogen, the monitoring of multi qualitative and quantitative parameters

Heteroepitaxial growth of cadmium carbonate at dolomite and calcite surfaces: Mechanisms and rates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Callagon, Erika Blanca R.; Lee, Sang Soo; Eng, Peter J.

Here, the systematic variation of rates and the mechanism of cadmium uptake on the (104) surface of dolomite (CaMg(CO 3) 2) were investigated using in situ and ex situ atomic force microscopy (AFM), ex situ specular X-ray reflectivity (XR), and ex situ X-ray fluorescence (XRF). Selected experiments were performed on the calcite (CaCO 3) (104) surface for comparison. Aqueous solutions of CdCl 2, CaCl 2, and NaHCO 3, undersaturated with respect to calcite and supersaturated with respect to otavite (CdCO 3) and the (Cd xCa 1-x)CO 3 solid solution, were reacted with dolomite surfaces for minutes to days. Calcite substratesmore » were reacted with solutions containing 1-50 μM CdCl 2, and with no added Ca or CO 3. Thin carbonate films following the Stranski-Krastanov growth mode were observed on both substrates. Specular XR and XRF revealed the formation of nm-thick Cd-rich carbonate films that were structurally ordered with respect to the dolomite (104) plane. Epitaxial films adopted the calcite crystal structure with a d 104- spacing (3.00 Å) larger than those of pure dolomite (2.88 Å) and otavite (2.95 Å) indicating either a solid solution with x approximate to 0.5, or a strained Cd-rich carbonate with a composition near that of otavite. The growth rate r of this phase increases with the initial supersaturation of the solution with respect to the solid solution, beta max, and follows the empirical relationship, as determined from XRF measurements, given by: r = 10 -4.88 ± 0.42 (β 2.29 ± 0.24 max - 1), (in units of atoms of Cd/Å 2/h).The morphology of the overgrowth also varied with β max, as exemplified by AFM observations. Growth at step edges occurred over the entire β max range considered, and additional growth features including 3 Å high monolayer islands and ~ 25 Å high tall islands were observed when log β max > 1. On calcite, in situ XR indicated that this phase is similar to the Cd-rich overgrowth formed on dolomite and images obtained from X

Heteroepitaxial growth of cadmium carbonate at dolomite and calcite surfaces: Mechanisms and rates

DOE PAGES

Callagon, Erika Blanca R.; Lee, Sang Soo; Eng, Peter J.; ...

2016-12-10

Here, the systematic variation of rates and the mechanism of cadmium uptake on the (104) surface of dolomite (CaMg(CO 3) 2) were investigated using in situ and ex situ atomic force microscopy (AFM), ex situ specular X-ray reflectivity (XR), and ex situ X-ray fluorescence (XRF). Selected experiments were performed on the calcite (CaCO 3) (104) surface for comparison. Aqueous solutions of CdCl 2, CaCl 2, and NaHCO 3, undersaturated with respect to calcite and supersaturated with respect to otavite (CdCO 3) and the (Cd xCa 1-x)CO 3 solid solution, were reacted with dolomite surfaces for minutes to days. Calcite substratesmore » were reacted with solutions containing 1-50 μM CdCl 2, and with no added Ca or CO 3. Thin carbonate films following the Stranski-Krastanov growth mode were observed on both substrates. Specular XR and XRF revealed the formation of nm-thick Cd-rich carbonate films that were structurally ordered with respect to the dolomite (104) plane. Epitaxial films adopted the calcite crystal structure with a d 104- spacing (3.00 Å) larger than those of pure dolomite (2.88 Å) and otavite (2.95 Å) indicating either a solid solution with x approximate to 0.5, or a strained Cd-rich carbonate with a composition near that of otavite. The growth rate r of this phase increases with the initial supersaturation of the solution with respect to the solid solution, beta max, and follows the empirical relationship, as determined from XRF measurements, given by: r = 10 -4.88 ± 0.42 (β 2.29 ± 0.24 max - 1), (in units of atoms of Cd/Å 2/h).The morphology of the overgrowth also varied with β max, as exemplified by AFM observations. Growth at step edges occurred over the entire β max range considered, and additional growth features including 3 Å high monolayer islands and ~ 25 Å high tall islands were observed when log β max > 1. On calcite, in situ XR indicated that this phase is similar to the Cd-rich overgrowth formed on dolomite and images obtained from X

Characterisation of the heterogeneity of karst using electrical geophysics - applications in SW China

NASA Astrophysics Data System (ADS)

Binley, A. M.; Cheng, Q.; Tao, M.; Chen, X.

2017-12-01

The southwest China karst region is one of the largest globally continuous karst areas. The great (structural, hydrological and geochemical) complexity of karstic environments and their rapidly evolving nature make them extremely vulnerable to natural and anthropogenic processes/activities. Characterising the location and properties of structures within the karst critical zone, and understanding how the landform is evolving is essential for the mitigation and adaption to locally- and globally-driven changes. Because of the specific nature of karst geology and geomorphology in the humid tropics and subtropics, spatial heterogeneity is high, evidenced by specific landforms features. Such heterogeneity leads to a high dynamic variability of hydrological processes in space and time, along with a complex exchange of surface water and groundwater. Investigating karst hydrogeological features is extremely challenging because of the three-dimensional nature of the system. Observations from boreholes can vary significantly over several metres, making conventional aquifer investigative methods limited. Geophysical methods have emerged as potentially powerful tools for hydrogeological investigations. Geophysical surveys can help to obtain more insight into the complex conduit networks and depth of weathering, both of which can provide quantitative information about the hydrological and hydrochemical dynamics of the system, in addition to providing a better understanding of how critical zone structures have been established and how the landscape is evolving. We present here results from recent geophysical field campaigns in SW China. We illustrate the effectiveness of electrical methods for mapping soil infil in epikarst and report results from field-based investigations along hillslope and valley transects. Our results reveal distinct zones of relatively high electrical conductivity to depths of tens of metres, which we attribute to localised increased fracture density. We

TEAM Science Advances STEM through Experiential Learning about Karst Geology at the Ozark Underground Laboratory.

NASA Astrophysics Data System (ADS)

Haskins, M. F.; Patterson, J. D.; Ruckman, B.; Keith, N.; Aley, C.; Aley, T.

2017-12-01

Carbonate karst represents approximately 14% of the world's land area and 20-25% of the land area in the United States. Most people do not understand this three dimensional landscape because they lack direct experience with this complicated geology. For the last 50 years, Ozark Underground Laboratory (OUL), located in Protem, MO, has been a pioneer in the research of karst geology and its influence on groundwater. OUL has also provided surface and sub-surface immersion experiences to over 40,000 individuals including students, educators, and Department of Transportation officials helping those individuals better understand the challenges associated with karst. Rockhurst University has incorporated OUL field trips into their educational programming for the last 30 years, thus facilitating individual understanding of karst geology which comprises approximately 60% of the state. Technology and Educators Advancing Missouri Science (TEAM Science) is a grant-funded professional development institute offered through Rockhurst University. The institute includes an immersion experience at OUL enabling in-service teachers to better understand natural systems, the interplay between the surface, sub-surface, and cave fauna, as well as groundwater and energy dynamics of karst ecosystems. Educating elementary teachers about land formations is especially important because elementary teachers play a foundational role in developing students' interest and aptitude in STEM content areas. (Funding provided by the U.S. Department of Education's Math-Science Partnership Program through the Missouri Department of Elementary and Secondary Education.)

Contamination investigation in a karst region

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bentowski, J.E.

1993-03-01

A series of springs in the karst region of north central Kentucky appeared to have been contaminated. These springs are within 1/2 mile of two sinkholes which were filled-in as permitted landfills for inert waste and then developed into an industrial park. A pre-remedial site inspection was performed under the authority of the Superfund laws in late 1989. A preliminary site visit included site reconnaissance and geologic field work to locate the springs. A review of historical serial photos aided in the planning the investigation program consisting of magnetic and soil gas surveys and the taking environmental soil and watermore » samples. The soil gas survey indicated potential soil sampling locations. Seventeen surface and subsurface soil samples were taken. Eleven water samples were taken from various springs, rivers and the local public water supply. The analytical results from soil samples taken over the largest sinkhole matched nine inorganic and eleven volatile organic compounds also found in the spring water and sediment samples. The springs are roughly on strike with major fracture systems reported in the literature. The success of this investigation emphasizes the importance of proper geologic consideration for contaminant monitoring in karst regions.« less

Microcrystalline dolomite within massive Japan Sea methane hydrate: origin and development ascertained by inclusions within inclusions.

NASA Astrophysics Data System (ADS)

Snyder, G. T.; Kakizaki, Y.; Matsumoto, R.; Suzuki, Y.; Takahata, N.; Sano, Y.; Tanaka, K.; Tomaru, H.; Imajo, T.; Iguchi, A.

2017-12-01

Microcrystalline dolomite grains were recently discovered as inclusions within relatively pure massive gas hydrate recovered from the Joetsu Basin area of the Japan Sea. These grains presumably formed as a consequence of the highly saline conditions in fluid inclusions which developed between coalescing grain boundaries within the growing hydrate. Stable carbon and oxygen isotopic composition of the dolomite is consistent with crystal growth occurring within such fluids. In addition to stable isotopes, we investigate trends in Mg/Ca ratios of the grains as well as the composition of inclusions which exist within the dolomites. Preliminary research shows that these inclusions retain valuable information as to the conditions which existed at the time of formation, as well as the dynamics of these extensive hydrate deposits over time. This study was conducted under the commission from AIST as a part of the methane hydrate research project funded by METI (the Ministry of Economy, Trade and Industry, Japan).

A role for calcium hydroxide and dolomite in water: acceleration of the reaction under ultraviolet light.

PubMed

Nagase, Hiroyasu; Tsujino, Hidekazu; Kurihara, Daisuke; Saito, Hiroshi; Kawase, Masaya

2014-04-01

Organic environmental pollutants are now being detected with remarkably high frequency in the aquatic environment. Photodegradation by ultraviolet light is sometimes used as a method for removing organic chemicals from water; however, this method is relatively inefficient because of the low degradation rates involved, and more efficient methods are under development. Here we show that the removal of various organic pollutants can be assisted by calcined dolomite in aqueous solution under irradiation with ultraviolet light. It was possible to achieve substantial removal of bisphenol A, chlorophenols, alkylphenols, 1-naphthol and 17β-estradiol. The major component of dolomite responsible for the removal was calcium hydroxide. Our results demonstrate that the use of calcium hydroxide with ultraviolet light irradiation can be a very effective method of rapidly removing organic environmental pollutants from water. This is a new role for calcium hydroxide and dolomite in water treatment. Copyright © 2013 Elsevier Ltd. All rights reserved.

Estimation of underground river water availability based on rainfall in the Maros karst region, South Sulawesi

NASA Astrophysics Data System (ADS)

Arsyad, Muhammad; Ihsan, Nasrul; Tiwow, Vistarani Arini

2016-02-01

Maros karst region, covering an area of 43.750 hectares, has water resources that determine the life around it. Water resources in Maros karst are in the rock layers or river underground in the cave. The data used in this study are primary and secondary data. Primary data includes characteristics of the medium. Secondary data is rainfall data from BMKG, water discharge data from the PSDA, South Sulawesi province in 1990-2010, and the other characteristics data Maros karst, namely cave, flora and fauna of the Bantimurung Bulusaraung National Park. Data analysis was conducted using laboratory test for medium characteristics Maros karst, rainfall and water discharge were analyzed using Minitab Program 1.5 to determine their profile. The average rainfall above 200 mm per year occurs in the range of 1999 to 2005. The availability of the water discharge at over 50 m3/s was happened in 1993 and 1995. Prediction was done by modeling Autoregressive Integrated Moving Average (ARIMA), with the rainfall data shows that the average precipitation for four years (2011-2014) will sharply fluctuate. The prediction of water discharge in Maros karst region was done for the period from January to August in 2011, including the type of 0. In 2012, the addition of the water discharge started up in early 2014.

Abiotically-formed, primary dolomite in the mid-Eocene lacustrine succession at Gebel El-Goza El-Hamra, NE Egypt: An approach to the role of smectitic clays

NASA Astrophysics Data System (ADS)

Wanas, H. A.; Sallam, E.

2016-08-01

This study discusses the role of smectitic clays in the formation of an abiotic (physio-chemical) primary dolomite within an evaporative alkaline-saline marginal lake system, in the absence of carbonate precursor and microbes. The present work has been achieved in terms of textural, mineralogical, and geochemical characteristics of dolostones in the Mid-Eocene (Bartonian) lacustrine succession cropping out at Gebel El-Goza El-Hamra (Shabrawet area, NE Egypt). This lacustrine succession is 15-16 m thick, and made up of alternating horizontal beds of dolostone, marlstone and mudrock that show some pedogenic and subaerial exposure features. The dolostones are composed mainly of dolomite (60-90%), smectite (20-30%) and quartz grains (5-10%). The dolomite comprises fine-crystalline rhombs to micro-spherical crystals with no obvious relics of microbial activity and/or carbonate precursor. It is, ordered, nearly stoichiometric (with 46-50% mole of MgCO3) and has δ18O and δ13C values ranging from + 0.44 to + 2.96 VPDB ‰, and 0.93 to - 8.95 VPDB ‰, respectively. The smectite occurs as thin mats that are commonly intergrown and associated with dolomite. Mineralogical, textural and stable isotopic results of the dolomite indicated that the dolomite was formed as an abiotic primary precipitate in alkaline saline lacustrine systems. In this respect, the gel-like highly viscous smectitic medium plus progressive CO2 degassing, elevated evaporation, low sedimentation rate, low sulphates level and alkaline soil solution lowered the kinetic barriers of dolomite precipitation from solution and promoted the incorporation of Mg2 + in the structure of dolomite. Consequently, the presence of smectitic clays in evaporative saline lakes is significant for dolomite formation because they can generate a gel-like highly viscous medium and provide Mg2 + that can facilitate the physcio-chemical precipitation of primary dolomite from solution at ambient temperatures. However, more work is

Modeling of karst deformation and analysis of acoustic emission during sinkhole formation

NASA Astrophysics Data System (ADS)

Bakeev, R. A.; Stefanov, Yu. P.; Duchkov, A. A.; Myasnikov, A. V.

2017-12-01

In this paper, the fracture pattern and formation of a sinkhole are estimated depending on the rock properties. The possibility of using geophysical methods for recording and analyzing acoustic emission to monitor and predict the state of the medium is considered. The problem of deformation of the sedimentary cover over the growing karst cavity is solved on the basis of the elastoplastic Drucker-Prager-Nikolaevsky model and the equation of damage accumulation. The specified kinetics of accumulation of damages allows us to describe slow processes of degradation of the strength of the medium under stresses that are low for the development of inelastic deformations. The results are obtained for different values of the strength of karst rock; we show the influence of the kinetic parameters of damage accumulation on the shape of collapse depressions. We also model acoustic emission caused by the material fracture. One can follow different stages of the karst development by looking at patterns of cells which fail at a given time. Our observations show the relation between the intensity of material fracture and the intensity of seismic emission.

Diagenesis and reservoir quality of Bhuban sandstones (Neogene), Titas Gas Field, Bengal Basin, Bangladesh

NASA Astrophysics Data System (ADS)

Aminul Islam, M.

2009-06-01

This study deals with the diagenesis and reservoir quality of sandstones of the Bhuban Formation located at the Titas Gas Field of Bengal Basin. Petrographic study including XRD, CL, SEM and BSE image analysis and quantitative determination of reservoir properties were carried out for this study. The sandstones are fine to medium-grained, moderately well to well sorted subfeldspathic arenites with subordinate feldspathic and lithic arenites. The diagenetic processes include clay infiltration, compaction and cementation (quartz overgrowth, chlorite, kaolinite, calcite and minor amount of pyrite, dolomite and K-feldspar overgrowth). Quartz is the dominant pore occluding cement and generally occurred as small euhedral crystals, locally as large pyramidal crystals in the primary pores. Pressure solution derived from grain contact is the main contributor of quartz overgrowths. Chlorite occurs as pore-lining and pore filling cement. In some cases, chlorite helps to retain porosity by preventing quartz overgrowth. In some restricted depth interval, pore-occlusion by calcite cement is very much intense. Kaolinite locally developed as vermiform and accelerated the minor porosity loss due to pore-occlusion. Kaolinite/chlorite enhances ineffective microporosity. Kaolinite is a by-product of feldspar leaching in the presence of acidic fluid produced during the maturation of organic matter in the adjacent Miocene or deeper Oligocene source rocks. The relation between diagenesis and reservoir quality is as follows: the initial porosity was decreased by compaction and cementation and then increased by leaching of the metastable grains and dissolution of cement. Good quality reservoir rocks were deposited in fluvial environment and hence quality of reservoir rocks is also environment selective. Porosity and permeability data exhibit good inverse correlation with cement. However, some data points indicate multiple controls on permeability. Reservoir quality is thus controlled by

Assessment of key transport parameters in a karst system under different dynamic conditions based on tracer experiments: the Jeita karst system, Lebanon

NASA Astrophysics Data System (ADS)

Doummar, Joanna; Margane, Armin; Geyer, Tobias; Sauter, Martin

2018-03-01

Artificial tracer experiments were conducted in the mature karst system of Jeita (Lebanon) under various flow conditions using surface and subsurface tracer injection points, to determine the variation of transport parameters (attenuation of peak concentration, velocity, transit times, dispersivity, and proportion of immobile and mobile regions) along fast and slow flow pathways. Tracer breakthrough curves (TBCs) observed at the karst spring were interpreted using a two-region nonequilibrium approach (2RNEM) to account for the skewness in the TBCs' long tailings. The conduit test results revealed a discharge threshold in the system dynamics, beyond which the transport parameters vary significantly. The polynomial relationship between transport velocity and discharge can be related to the variation of the conduit's cross-sectional area. Longitudinal dispersivity in the conduit system is not a constant value (α = 7-10 m) and decreases linearly with increasing flow rate because of dilution effects. Additionally, the proportion of immobile regions (arising from conduit irregularities) increases with decreasing water level in the conduit system. From tracer tests with injection at the surface, longitudinal dispersivity values are found to be large (8-27 m). The tailing observed in some TBCs is generated in the unsaturated zone before the tracer actually arrives at the major subsurface conduit draining the system. This work allows the estimation and prediction of the key transport parameters in karst aquifers. It shows that these parameters vary with time and flow dynamics, and they reflect the geometry of the flow pathway and the origin of infiltrating (potentially contaminated) recharge.

Use of limestone karst forests by Bornean orangutans (Pongo pygmaeus morio) in the Sangkulirang peninsula, east Kalimantan, Indonesia.

PubMed

Marshall, Andrew J; Salas, Leonardo A; Stephens, Suzette; Engström, Linda; Meijaard, Erik; Stanley, Scott A

2007-02-01

The Indonesian province of East Kalimantan is home to some of the largest remaining contiguous tracts of lowland Dipterocarp forest on the island of Borneo. Nest surveys recently conducted in these forests indicated the presence of a substantial population of Eastern Bornean orangutans (Pongo pygmaeus morio) in the Berau and East Kutai regencies in the northern half of the province. The Sangkulirang Peninsula contains extensive limestone karst forests in close proximity to the lowland Dipterocarp forests inhabited by orangutans in these regencies. Orangutans have been sighted in these limestone karst forests, but the importance of this forest type for orangutans has been unclear. Therefore, we conducted 49 km of nest surveys in limestone karst forest to obtain the first quantitative estimates of orangutan densities in this habitat, and walked 28 km of surveys in nearby lowland Dipterocarp forests for comparison. We also gathered basic ecological data along our transects in an attempt to identify correlates of orangutan abundance across these habitat types. Undisturbed limestone karst forests showed the lowest orangutan densities (147 nests/km(2), 0.82 indiv/km(2)), disturbed limestone forests had intermediate densities (301 nests/km(2), 1.40 indiv/km(2)), and undisturbed lowland Dipterocarp forests contained the highest density (987 nests/km(2), 5.25 indiv/km(2)), significantly more than the undisturbed limestone karst forests. This difference was not correlated with variation in liana abundance, fig stem density, or stump density (an index of forest disturbance). Therefore, other factors, such as the relatively low tree species diversity of limestone karst forests, may explain why orangutans appear to avoid these areas. We conclude that limestone karst forests are of low relevance for safeguarding the future of orangutans in East Kalimantan.

Integrated petrophysical and sedimentological study of the Middle Miocene Nullipore Formation (Ras Fanar Field, Gulf of Suez, Egypt): An approach to volumetric analysis of reservoirs

NASA Astrophysics Data System (ADS)

Afife, Mohamed M.; Sallam, Emad S.; Faris, Mohamed

2017-10-01

This study aims to integrate sedimentological, log and core analyses data of the Middle Miocene Nullipore Formation at the Ras Fanar Field (west central Gulf of Suez, Egypt) to evaluate and reconstruct a robust petrophysical model for this reservoir. The Nullipore Formation attains a thickness ranging from 400 to 980 ft and represents a syn-rift succession of the Middle Miocene marine facies. It consists of coralline-algal-reefal limestone, dolomitic limestone and dolostone facies, with few clay and anhydrite intercalations. Petrographically, seven microfacies types (MF1 to MF7) have been recognized and assembled genetically into three related facies associations (FA1 to FA3). These associations accumulated in three depositional environments: 1) peritidal flat, 2) restricted lagoon, and 3) back-shoal environments situated on a shallow inner ramp (homoclinal) setting. The studied rocks have been influenced by different diagenetic processes (dolomitization, cementation, compaction, authigenesis and dissolution), which led to diminishing and/or enhancing the reservoir quality. Three superimposed 3rd-order depositional sequences are included in the Nullipore succession displaying both retrogradational and aggradational packages of facies. Given the hydrocarbon potential of the Nullipore Formation, conventional well logs of six boreholes and core analyses data from one of these wells (RF-B12) are used to identify electrofacies zones of the Nullipore Formation. The Nullipore Formation has been subdivided into three electrofacies zones (the Nullipore-I, Nullipore-II, and Nullipore-III) that are well-correlated with the three depositional sequences. Results of petrographical studies and log analyses data have been employed in volumetric calculations to estimate the amount of hydrocarbon-in-place and then the ultimate recovery of the Nullipore reservoir. The volumetric calculations indicate that the total volume of oil-in-place is 371 MMSTB at 50% probability (P50), whereas

Calcite and dolomite in intrusive carbonatites. II. Trace-element variations

NASA Astrophysics Data System (ADS)

Chakhmouradian, Anton R.; Reguir, Ekaterina P.; Couëslan, Christopher; Yang, Panseok

2016-04-01

The composition of calcite and dolomite from several carbonatite complexes (including a large set of petrographically diverse samples from the Aley complex in Canada) was studied by electron-microprobe analysis and laser-ablation inductively-coupled-plasma mass-spectrometry to identify the extent of substitution of rare-earth and other trace elements in these minerals and the effects of different igneous and postmagmatic processes on their composition. Analysis of the newly acquired and published data shows that the contents of rare-earth elements (REE) and certain REE ratios in magmatic calcite and dolomite are controlled by crystal fractionation of fluorapatite, monazite and, possibly, other minerals. Enrichment in REE observed in some samples (up to ~2000 ppm in calcite) cannot be accounted for by coupled substitutions involving Na, P or As. At Aley, the REE abundances and chondrite-normalized (La/Yb)cn ratios in carbonates decrease with progressive fractionation. Sequestration of heavy REE from carbonatitic magma by calcic garnet may be responsible for a steeply sloping "exponential" pattern and lowered Ce/Ce* ratios of calcite from Magnet Cove (USA) and other localities. Alternatively, the low levels of Ce and Mn in these samples could result from preferential removal of these elements by Ce4+- and Mn3+-bearing minerals (such as cerianite and spinels) at increasing f(O2) in the magma. The distribution of large-ion lithophile elements (LILE = Sr, Ba and Pb) in rock-forming carbonates also shows trends indicative of crystal fractionation effects (e.g., concomitant depletion in Ba + Pb at Aley, or Sr + Ba at Kerimasi), although the phases responsible for these variations cannot be identified unambiguously at present. Overall, element ratios sensitive to the redox state of the magma and its complexing characteristics (Eu/Eu*, Ce/Ce* and Y/Ho) are least variable and in both primary calcite and dolomite, approach the average chondritic values. In consanguineous

Sustainable yield of a karst aquifer system: a case study of Jinan springs in northern China

NASA Astrophysics Data System (ADS)

Kang, Fengxin; Jin, Menggui; Qin, Pinrui

2011-06-01

Based on the long-term monitoring data of rainfall, groundwater levels, groundwater abstraction, spring flow rates and groundwater quality, an assessment has been undertaken of the sustainable yield of a karst aquifer system in Shandong Province, northern China, to maintain perennial outflow of the karst springs while meeting water demands. One of the fundamental indicators for sustainable yield of groundwater is identified as maximum allowable water-level drawdown. A regional three-dimensional finite-difference numerical model has been developed to optimize the schemes associated with well fields and their locations and sustainable yields, in the Jinan spring catchment and its adjacent karst groundwater catchments, with the aim of maintaining the water level higher than the allowable lowest water level of 27.5 m above sea level. Furthermore, measures necessary to move towards sustainable use of the karst groundwater are outlined, drawing on contingency plans of water-source replacement and artificial recharge, dual water supply (based in water quality), use of the spring waters themselves, and groundwater quality protection.

Evaluation of Karst Soil Erosion and Nutrient Loss Based on RUSLE Model in Guizhou Province

NASA Astrophysics Data System (ADS)

Zeng, Cheng; Li, Yangbing; Bai, Xiaoyong; Luo, Guangjie

2018-01-01

Based on GIS technology and RUSLE model, the spatial variation characteristics of soil erosion were analyzed in karst areas, and the relationship between soil erosion and soil nutrient loss was discussed. The results showed that the soil differences in spatial variation between nutrient losses. The results illustrate the total soil erosion in is 10316.31 × 104t • a-1, accounting for 84.95% of the total land area in Guizhou Province. The spatial distribution of soil erosion showing the characteristics of the southeast to the northwest strip. The annual average soil erosion modulu is 691.94 t • km-2 • a-1, of which karst is 720.28t • km-2 • a-1 and non-karst is 689.53 t • km-2 • a-1. The total nutrient losses such as soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP) and total potassium (TK) were 596.72 × 104t • a-1 due to soil erosion, and SOC, TN and TP and TK were 38.13, 1.61, 0.41 and 14.70t • km-2 • a-1, respectively. The average amount of loss and total loss are the largest in non-karst, and four kinds of nutrient is the smallest in karst gorge. The spatial variation of soil erosion in the study area is the process of increasing the erosion area with the increase of the erosion rate, and the difference of the spatial distribution of soil erosion determines the spatial distribution of soil nutrient loss.

Retention of neodymium by dolomite at variable ionic strength as probed by batch and column experiments.

PubMed

Emerson, H P; Zengotita, F; Richmann, M; Katsenovich, Y; Reed, D T; Dittrich, T M

2018-10-01

The results presented in this paper highlight the complexity of adsorption and incorporation processes of Nd with dolomite and significantly improve upon previous work investigating trivalent actinide and lanthanide interactions with dolomite. Both batch and mini column experiments were conducted at variable ionic strength. These data highlight the strong chemisorption of Nd to the dolomite surface (equilibrium K d 's > 3000 mL/g) and suggest that equilibrium adsorption processes may not be affected by ionic strength based on similar results at 0.1 and 5.0 M ionic strength in column breakthrough and equilibrium batch (>5 days) results. Mini column experiments conducted over approximately one year also represent a significant development in measurement of sorption of Nd in the presence of flow as previous large-scale column experiments did not achieve breakthrough likely due to the high loading capacity of dolomite for Nd (up to 240 μg/g). Batch experiments in the absence of flow show that the rate of Nd removal increases with increasing ionic strength (up to 5.0 M) with greater removal at greater ionic strength for a 24 h sampling point. We suggest that the increasing ionic strength induces increased mineral dissolution and re-precipitation caused by changes in activity with ionic strength that lead to increased removal of Nd through co-precipitation processes. Copyright © 2018 Elsevier Ltd. All rights reserved.

Arsenic occurrence, mobility, and retardation in sandstone and dolomite formations of the Fox River Valley, Eastern Wisconsin.

PubMed

Thornburg, Katie; Sahai, Nita

2004-10-01

Elevated levels of groundwater arsenic (approximately 100 microg L(-1) = 1.3 x 10(-6) M) are found in the Fox River Valley, eastern Wisconsin. The goals of this study were to identifythe sources of As contamination and to determine the reactions responsible for As mobilization and retardation in areas lacking a discrete zone of As-enriched sulfides, shown previouslyto cause elevated arsenic in groundwater. Detailed mineralogical and chemical analyses were conducted on samples from the Sinnipee Group dolomite and St. Peter sandstone in eastern Wisconsin. Solution chemistry was monitored in batch reactions of dolomite, quartz, and sulfide mineral fractions with a 0.01 M CsCl solution at pH 7 for 3 weeks in air. Results indicate that arsenic is present in isomorphous substitution with pyrite/marcasite (FeS2), which occurs as disseminated veins, grains, and nodules in the dolomite and sandstone. The released As subsequently sorbs on the ferric oxyhydroxides formed or coprecipitates in a scorodite-like phase. Significantly, oxidative dissolution of the disseminated As-rich FeS2 grains and nodules is sufficient to explain the elevated As levels observed in eastern Wisconsin groundwater. Although complete uptake of As is observed in the batch experiments, persistent elevated As levels with spatial and temporal variations in regional groundwaters are attributed to differences in the type of sulfide occurrence (discrete horizon vs dispersed grains, veins, and nodules), variations in the dissolved oxygen content of the groundwater, and variable (limited) buildup of reacted surface layers on sulfide grains in the natural flow-through system. Discrete nanoparticulate As phases, As surface precipitates on sulfides, and sorbed As on dolomite and quartz are eliminated as major sources, and sorption of arsenic on dolomite and quartz is deemed less important than association with ferric oxyhydroxides for retardation in the regional system.

Using MODFLOW drains to simulate groundwater flow in a karst environment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Quinn, J.; Tomasko, D.; Glennon, M.A.

1998-07-01

Modeling groundwater flow in a karst environment is both numerically challenging and highly uncertain because of potentially complex flowpaths and a lack of site-specific information. This study presents the results of MODFLOW numerical modeling in which drain cells in a finite-difference model are used as analogs for preferential flowpaths or conduits in karst environments. In this study, conduits in mixed-flow systems are simulated by assigning connected pathways of drain cells from the locations of tracer releases, sinkholes, or other karst features to outlet springs along inferred flowpaths. These paths are determined by the locations of losing stream segments, ephemeral streammore » beds, geophysical surveys, fracture lineaments, or other surficial characteristics, combined with the results of dye traces. The elevations of the drains at the discharge ends of the inferred flowpaths are estimated from field data and are adjusted when necessary during model calibration. To simulate flow in a free-flowing conduit, a high conductance is assigned to each drain to eliminate the need for drain-specific information that would be very difficult to obtain. Calculations were performed for a site near Hohenfels, Germany. The potentiometric surface produced by the simulations agreed well with field data. The head contours in the vicinity of the karst features behaved in a manner consistent with a flow system having both diffuse and conduit components, and the sum of the volumetric flow out of the drain cells agreed closely with spring discharges and stream flows. Because of the success of this approach, it is recommended for regional studies in which little site-specific information (e.g., location, number, size, and conductivity of fractures and conduits) is available, and general flow characteristics are desired.« less

Spatial heterogeneities and variability of karst hydro-system : insights from geophysics

NASA Astrophysics Data System (ADS)

Champollion, C.; Fores, B.; Lesparre, N.; Frederic, N.

2017-12-01

Heterogeneous systems such as karsts or fractured hydro-systems are challenging for both scientist and groundwater resources management. Karsts heterogeneities prevent the comparison and moreover the combination of data representative of different scales: borehole water level can generally not be used directly to interpret spring flow dynamic for example. The spatial heterogeneity has also an impact on the temporal variability of groundwater transfer and storage. Karst hydro-systems have characteristic non linear relation between precipitation amount and discharge at the outlets with threshold effects and a large variability of groundwater transit times In the presentation, geophysical field experiments conducted in karst hydro-system in the south of France are used to investigate groundwater transfer and storage variability at a scale of a few hundred meters. We focus on the added value of both geophysical time-lapse gravity experiments and 2D ERT imaging of the subsurface heterogeneities. Both gravity and ERT results can only be interpreted with large ambiguity or some strong a priori: the relation between resistivity and water content is not unique; almost no information about the processes can be inferred from the groundwater stock variations. The present study demonstrate how the ERT and gravity field experiments can be interpreted together in a coherent scheme with less ambiguity. First the geological and hydro-meteorological context is presented. Then the ERT field experiment including the processing and the results are detailed in the section about geophysical imaging of the heterogeneities. The gravity double difference (S2D) time-lapse experiment is described in the section about geophysical monitoring of the temporal variability. The following discussion demonstrate the impact of both experiments on the interpretation in terms of processes and heterogeneities.

River Intrusion in Karst Springs in Eogenetic Aquifers: Implications for Speleogenesis

NASA Astrophysics Data System (ADS)

Martin, J. B.; Gulley, J.; Screaton, E. J.

2008-12-01

Conceptual models of speleogenesis generally assume uni-directional transport in integrated conduit systems from discrete recharge points to discharge at karst springs. Estavelles, however, are karst springs that function intermittently as discrete recharge points when river stage rises more rapidly than local aquifer heads. As river water chemistry changes between baseflow and floods, estavelles should influence mass transport through (e.g. organic carbon, nutrients, and oxygen) and speleogenesis within karst systems. Estavelles are common in our study area in north-central Florida, particularly along the lower reaches of the Santa Fe River, where it flows across the unconfined karstic Floridan aquifer. River stage in this unconfined region can rise much faster than aquifer heads when large amounts of rain fall on the confined regions in its upper reaches. Backflooding into the estavelles during elevated river stage drives river water into the ground, causing some springs to reverse and other springs to recirculate large volumes of river water. Floodwaters originating in the confined region are highly undersaturated with respect to calcite, and thus river water transitions from slightly supersaturated to highly undersaturated with respect to calcite during flood events. As a result, conduits connected to estavelles are continuously enlarged as springs reverse or recirculate calcite-undersaturated river water. It has been suggested that currently flooded caves (i.e. karst conduits) associated with springs in Florida formed entirely underwater because speleothems, which are prevalent in flooded caves in the Yucatan and Bahamas, have not been observed by cave divers. Results of this study indicate that the absence of speleothems does not necessarily provide evidence of a continuous phreatic history for underwater caves. Instead speleothems that formed in caves while dry could have been dissolved by backflooding of estavelles with undersaturated water

Adaptations of indigenous bacteria to fuel contamination in karst aquifers in south-central Kentucky

USGS Publications Warehouse

Byl, Thomas D.; Metge, David W.; Agymang, Daniel T.; Bradley, Michael W.; Hileman, Gregg; Harvey, Ronald W.

2014-01-01

The karst aquifer systems in southern Kentucky can be dynamic and quick to change. Microorganisms that live in these unpredictable aquifers are constantly faced with environmental changes. Their survival depends upon adaptations to changes in water chemistry, taking advantage of positive stimuli and avoiding negative environmental conditions. The U.S. Geological Survey conducted a study in 2001 to determine the capability of bacteria to adapt in two distinct regions of water quality in a karst aquifer, an area of clean, oxygenated groundwater and an area where the groundwater was oxygen depleted and contaminated by jet fuel. Water samples containing bacteria were collected from one clean well and two jet fuel contaminated wells in a conduit-dominated karst aquifer. Bacterial concentrations, enumerated through direct count, ranged from 500,000 to 2.7 million bacteria per mL in the clean portion of the aquifer, and 200,000 to 3.2 million bacteria per mL in the contaminated portion of the aquifer over a twelve month period. Bacteria from the clean well ranged in size from 0.2 to 2.5 mm, whereas bacteria from one fuel-contaminated well were generally larger, ranging in size from 0.2 to 3.9 mm. Also, bacteria collected from the clean well had a higher density and, consequently, were more inclined to sink than bacteria collected from contaminated wells. Bacteria collected from the clean portion of the karst aquifer were predominantly (,95%) Gram-negative and more likely to have flagella present than bacteria collected from the contaminated wells, which included a substantial fraction (,30%) of Gram-positive varieties. The ability of the bacteria from the clean portion of the karst aquifer to biodegrade benzene and toluene was studied under aerobic and anaerobic conditions in laboratory microcosms. The rate of fuel biodegradation in laboratory studies was approximately 50 times faster under aerobic conditions as compared to anaerobic, sulfur-reducing conditions. The

Calculation of the Strip Foundation on Solid Elastic Base, Taking into Account the Karst Collapse

NASA Astrophysics Data System (ADS)

Sharapov, R.; Lodigina, N.

2017-07-01

Karst processes greatly complicate the construction and operation of buildings and structures. Due to the karstic deformations at different times there have been several major accidents, which analysis showed that in all cases the fundamental errors committed at different stages of building development: site selection, engineering survey, design, construction or operation of the facilities. Theory analysis of beams on elastic foundation is essential in building practice. Specialist engineering facilities often have to resort to multiple designing in finding efficient forms of construction of these facilities. In work the calculation of stresses in cross-sections of the strip foundation evenly distributed load in the event of karst. A comparison of extreme stress in the event of karst and without accounting for the strip foundation as a beam on an elastic foundation.

Molecular characters of melon (Cucumismelo L. "Tacapa") in response to karst critical land

NASA Astrophysics Data System (ADS)

Rachmawati, Yuanita; Daryono, Budi Setiadi; Aristya, Ganies Riza

2017-06-01

Yogyakarta district has 158.600 ha critical land and spread off in three Agro Ecosystem zones. Two of them are karsts critical land. Critical lands which contain calcium carbonate in high concentration and water dehydration in upper surface give abiotic stress in wide range of plant. Melon cultivar TACAPA has superior characteristic derived from parental crossing, ♀ Action 434 and ♂ PI 371795 and potential to be developed in karsts critical land. Abscicic acid (ABA) is a phytohormone expressed by plant in abiotic stress condition. CmBG1 is a gene which regulate ABA hormone in melon. The purposes of this research were examining the molecular character of melon cultivar TACAPA in response to karsts critical land in order to study molecular characterization of CmBG1 gene. Analysis was done qualitatively by using Reverse Transcriptase-PCR (RT-PCR) and Electrophoresis, while quantitative analysis was conducted by observing absorbance score in spectrophotometer. CmBG1 gene expression is examined by using Real time PCR (qPCR). Molecular characters obtained are CmBG1 detected in size ±1258 bp, CmBG1 gene concentrations in melon which planted in control media are lower than melon in critical lands media. These results are similar with the real time quantitative analysis method. It also be revealed that melon TACAPA is more potential plant compared to another cultivar that can be developed in karst critical land area.

Speleogenesis, geometry, and topology of caves: A quantitative study of 3D karst conduits

NASA Astrophysics Data System (ADS)

Jouves, Johan; Viseur, Sophie; Arfib, Bruno; Baudement, Cécile; Camus, Hubert; Collon, Pauline; Guglielmi, Yves