Community news

Speleology in Kazakhstan

Shakalov on 04 Jul, 2018
Hello everyone!   I pleased to invite you to the official site of Central Asian Karstic-Speleological commission ("Kaspeko")   There, we regularly publish reports about our expeditions, articles and reports on speleotopics, lecture course for instructors, photos etc. ...

New publications on hypogene speleogenesis

Klimchouk on 26 Mar, 2012
Dear Colleagues, This is to draw your attention to several recent publications added to KarstBase, relevant to hypogenic karst/speleogenesis: Corrosion of limestone tablets in sulfidic ground-water: measurements and speleogenetic implications Galdenzi,

The deepest terrestrial animal

Klimchouk on 23 Feb, 2012
A recent publication of Spanish researchers describes the biology of Krubera Cave, including the deepest terrestrial animal ever found: Jordana, Rafael; Baquero, Enrique; Reboleira, Sofía and Sendra, Alberto. ...

Caves - landscapes without light

akop on 05 Feb, 2012
Exhibition dedicated to caves is taking place in the Vienna Natural History Museum   The exhibition at the Natural History Museum presents the surprising variety of caves and cave formations such as stalactites and various crystals. ...

Did you know?

That microkarren is very small dissolutional channels, commonly 1-3mm across; parallel, convergent or randomly intersecting on a limestone surface. though found in all climatic regions they are most conspicuous in semi-arid and periglacial environments, where dissolutional processes are minimal and very slow. the random patterns of some microkarren may be due to the effects of condensation water [9].?

Checkout all 2699 terms in the KarstBase Glossary of Karst and Cave Terms

What is Karstbase?

Search KARSTBASE:

keyword
author

Browse Speleogenesis Issues:

KarstBase a bibliography database in karst and cave science.

Featured articles from Cave & Karst Science Journals
Chemistry and Karst, White, William B.
See all featured articles
Featured articles from other Geoscience Journals
Karst environment, Culver D.C.
Mushroom Speleothems: Stromatolites That Formed in the Absence of Phototrophs, Bontognali, Tomaso R.R.; D’Angeli Ilenia M.; Tisato, Nicola; Vasconcelos, Crisogono; Bernasconi, Stefano M.; Gonzales, Esteban R. G.; De Waele, Jo
Calculating flux to predict future cave radon concentrations, Rowberry, Matt; Marti, Xavi; Frontera, Carlos; Van De Wiel, Marco; Briestensky, Milos
Microbial mediation of complex subterranean mineral structures, Tirato, Nicola; Torriano, Stefano F.F;, Monteux, Sylvain; Sauro, Francesco; De Waele, Jo; Lavagna, Maria Luisa; D’Angeli, Ilenia Maria; Chailloux, Daniel; Renda, Michel; Eglinton, Timothy I.; Bontognali, Tomaso Renzo Rezio
Evidence of a plate-wide tectonic pressure pulse provided by extensometric monitoring in the Balkan Mountains (Bulgaria), Briestensky, Milos; Rowberry, Matt; Stemberk, Josef; Stefanov, Petar; Vozar, Jozef; Sebela, Stanka; Petro, Lubomir; Bella, Pavel; Gaal, Ludovit; Ormukov, Cholponbek;
See all featured articles from other geoscience journals

Search in KarstBase

Your search for root (Keyword) returned 52 results for the whole karstbase:
Showing 16 to 30 of 52
Karst rocky desertification in southwestern China: Geomorphology, landuse, impact and rehabilitation, 2004, Wang S. J. , Liu Q. M. , Zhang D. F. ,
Karst rocky desertification is a process of land degradation involving serious soil erosion, extensive exposure of basement rocks, drastic decrease in soil productivity, and the appearance of a desert-like landscape. It is caused by irrational, intensive land use on a fragile karst geo-ecological environment. The process is expanding rapidly, and it is daily reducing the living space of residents and is the root of disasters and poverty in the karst areas of southwestern China. The tectonic, geomorphic and environmental background to karst rocky desertification is analysed. Population pressure and the intensive land use that have led to this serious land degradation are described. Although the problem concerns the Chinese Government and some profitable experience in the partial restoration or reconstruction of the ecological environment has been gained, effective remedial action has not been achieved on a large scale.

Small karst features (karren) of Dugi otok island and Kornati archipelago coastal karst (Croatia), 2004, Perica Draž, En, Marjanac Tihomir, Anič, Ić, Branka, Mrak Irena, Jurač, Ić, Mladen

Dugi otok Island and Kornati archipelago islands are characterized by karst morphology. Small karst features are particulary well developed along the coast in the swash zone, and significant differences can be observed due to different interaction of wave action, bedding attitude, bed thicknesses and lithology. Among other karren types, fissure- and network-type karren are particulary interesting, both of which start developing from initial root karren. The age of some of these small karst features can be estimated by their occurrence in ancient quarries, and we suggest their historic age. We can envisage the future development of these small coastal corrosion forms.


Sediment storage and yield in an urbanized karst watershed, 2005, Hart Evan A. , Schurger Stephen G. ,
In karst watersheds, sinkholes and other drainage features control the temporal and spatial pattern of sediment storage across the landscape. However, studies dealing with sedimentation in karst watersheds are scarce and the sediment storage function of sinkholes and caves has not been investigated using a sediment budget approach. In this study, we use estimates of channel erosion, sinkhole sedimentation, and suspended sediment yield to examine changes in sediment storage in the 9 km2 Upper Pigeon Roost Creek fluviokarst watershed near Cookeville, TN. The study watershed has undergone urbanization over the last ~ 50 years, and sinkholes and caves in the area show signs of recent sedimentation (buried tree roots, buried cultural artifacts, etc.). While sinkholes are generally considered to be sediment sinks, sinkholes examined in this study are shown to cycle between periods of net sediment storage and net sediment loss. Using copyright dates on trash items buried in sinkhole deposits, we estimated the residence time of sinkhole-stored sediment to range from 6 to 10 years. However, other evidence indicates that some sinkholes may store sediment for several centuries. We propose that sediment storage within sinkholes is controlled by several factors including sinkhole drainage area, sinkhole morphology, and basin sediment yield. In addition, changes in sediment storage in karst watersheds are contingent upon random events such as sinkhole collapses. Annual sediment yield was estimated to be 111 Mg km- 2 year- 1 for the entire study watershed and ranged from 11 to 128 Mg km- 2 year- 1 for 3 sub-watersheds. Sediment eroded from the watershed, perhaps during historic settlement of the area, is stored within a large cave system underlying the city. However, the results of a partial sediment budget indicate that the cave is presently a net sediment source. Overall, the findings indicate that the sediment storage function of caves and sinkholes varies spatially and temporally, and that these changes need to be incorporated into sediment budgets for karst watersheds

Ecology and hydrology of a threatened groundwater-dependent ecosystem: the Jewel Cave karst system in Western Australia, PhD Thesis, 2005, Eberhard, S. M.

Groundwater is a significant component of the world’s water balance and accounts for >90 % of usable freshwater. Around the world groundwater is an important source of water for major cities, towns, industries, agriculture and forestry. Groundwater plays a role in the ecological processes and ‘health’ of many surface ecosystems, and is the critical habitat for subterranean aquatic animals (stygofauna). Over-abstraction or contamination of groundwater resources may imperil the survival of stygofauna and other groundwater-dependent ecosystems (GDEs). In two karst areas in Western Australia (Yanchep and Leeuwin-Naturaliste Ridge), rich stygofauna communities occur in cave waters containing submerged tree roots. These aquatic root mat communities were listed as critically endangered because of declining groundwater levels, presumably caused by lower rainfall, groundwater abstraction, and/or forest plantations. Investigation of the hydrology and ecology of the cave systems was considered essential for the conservation and recovery of these threatened ecological communities (TECs). This thesis investigated the hydrology and ecology of one of the TECs, located in the Jewel Cave karst system in the Leeuwin-Naturaliste Ridge. A multi-disciplinary approach was used to explore aspects pertinent to the hydrology and ecology of the groundwater system.
Thermoluminescence dating of the limestone suggested that development of the karst system dates from the Early Pleistocene and that caves have been available for colonisation by groundwater fauna since that time. Speleogenesis of the watertable maze caves occurred in a flank margin setting during earlier periods of wetter climate and/or elevated base levels. Field mapping and leveling were used to determine hydrologic relationships between caves and the boundaries of the karst aquifer. Monitoring of groundwater levels was undertaken to characterise the conditions of recharge, storage, flow and discharge. A hydrogeologic model of the karst system was developed.
The groundwater hydrograph for the last 50 years was reconstructed from old photographs and records whilst radiometric dating and leveling of stratigraphic horizons enabled reconstruction of a history of watertable fluctuations spanning the Holocene to Late Pleistocene. The watertable fluctuations over the previous 50 years did not exceed the range of fluctuations experienced in the Quaternary history, including a period 11,000 to 13,000 years ago when the watertable was lower than the present level.
The recent groundwater decline in Jewel Cave was not reflected in the annual rainfall trend, which was above average during the period (1976 to 1988) when the major drop in water levels occurred. Groundwater abstraction and tree plantations in nearby catchments have not contributed to the groundwater decline as previously suggested. The period of major watertable decline coincided with a substantial reduction in fire frequency within the karst catchment. The resultant increase in understorey vegetation and ground litter may have contributed to a reduction in groundwater recharge, through increased evapotranspiration and interception of rainfall. To better understand the relationships between rainfall, vegetation and fire and their effects on groundwater recharge, an experiment is proposed that involves a prescribed burn of the cave catchment with before-after monitoring of rainfall, leaf-area, ground litter, soil moisture, vadose infiltration and groundwater levels.
Molecular genetic techniques (allozyme electrophoresis and mitochondrial DNA) were used to assess the species and population boundaries of two genera and species of cave dwelling Amphipoda. Populations of both species were largely panmictic which was consistent with the hydrogeologic model. The molecular data supported the conclusion that both species of amphipod have survived lower watertable levels experienced in the caves during the Late Pleistocene. A mechanism for the colonization and isolation of populations in caves is proposed.
Multi Dimensional Scaling was used to investigate patterns in groundwater biodiversity including species diversity, species assemblages, habitat associations and biogeography. Faunal patterns were related to abiotic environmental parameters. Investigation of hydrochemistry and water quality characterized the ecological water requirements (EWR) of the TEC and established a baseline against which to evaluate potential impacts such as groundwater pollution.
The conservation status of the listed TEC was significantly improved by increasing the number of known occurrences and distribution range of the community (from 10 m2 to > 2 x 106 m2), and by showing that earlier perceived threatening processes (rainfall decline, groundwater pumping, tree plantations) were either ameliorated or inoperative within this catchment. The GDE in the Jewel Cave karst system may not have been endangered by the major phase of watertable decline experienced 1975-1987, or by the relatively stable level experienced up until 2000. However, if the present trend of declining rainfall in southwest Western Australia continues, and the cave watertable declines > 0.5 m below the present level, then the GDE may become more vulnerable to extinction.
The occurrence and distribution of aquatic root mat communities and related groundwater fauna in other karst catchments in the Leeuwin-Naturaliste Ridge is substantially greater than previously thought, however some of these are predicted to be threatened by groundwater pumping and pollution associated with increasing urban and rural developments. The taxonomy of most stygofauna taxa and the distribution of root mat communities is too poorly known to enable proper assessment of their conservation requirements. A regional-scale survey of stygofauna in southwest Western Australia is required to address this problem. In the interim, conservation actions for the listed TECs need to be focused at the most appropriate spatial scale, which is the karst drainage system and catchment area. Conservation of GDEs in Western Australia will benefit from understanding and integration with abiotic groundwater system processes, especially hydrogeologic and geomorphic processes.


Ecology and hydrology of a threatened groundwater-dependent ecosystem: the Jewel Cave karst system in Western Australia [abstract], 2006, Eberhard S. M.
This thesis investigates the hydrology and ecology of a threatened aquatic root mat community in the Jewel Cave karst system in the Leeuwin-Naturaliste Ridge, Western Australia. Development of the karst system dates from the Early Pleistocene and the caves have been available for colonisation by groundwater fauna since that time. Speleogenesis of the watertable maze caves occurred in a flank margin setting during earlier periods of wetter climate and/or elevated base levels. Watertable fluctuations over the last 50 years did not exceed the range experienced in the Quaternary history. The recent groundwater decline in Jewel Cave was not related to rainfall, nor groundwater abstraction nor nearby tree plantations. However, it did coincide with a reduction in fire frequency within the karst catchment. The resultant increase in understorey vegetation and ground litter may have reduced groundwater recharge through increased evapotranspiration and interception of rainfall. The populations of two genera and species of cave dwelling Amphipoda are largely panmictic. Both species have survived lower watertable levels during the Late Pleistocene. A mechanism for the colonization and isolation of populations in caves is proposed. Faunal patterns (including species diversity, species assemblages, habitat associations and biogeography) were related to abiotic environmental parameters. The ecological water requirements of the community were determined as a baseline for evaluation of impacts such as groundwater pollution. If rainfall continues to decline, and the cave watertable declines > 0.5 m below the present level, then the groundwater ecosystem may become more vulnerable to extinction. The taxonomy and distribution of root mat communities is poorly known and a regional-scale survey is required to properly assess their conservation requirements. Meanwhile, conservation actions for the communities need to be focused at the scale of the karst drainage system and catchment area.

Sedimentary manganese metallogenesis in response to the evolution of the Earth system, 2006, Roy Supriya,
The concentration of manganese in solution and its precipitation in inorganic systems are primarily redox-controlled, guided by several Earth processes most of which were tectonically induced. The Early Archean atmosphere-hydrosphere system was extremely O2-deficient. Thus, the very high mantle heat flux producing superplumes, severe outgassing and high-temperature hydrothermal activity introduced substantial Mn2 in anoxic oceans but prevented its precipitation. During the Late Archean, centered at ca. 2.75[no-break space]Ga, the introduction of Photosystem II and decrease of the oxygen sinks led to a limited buildup of surface O2-content locally, initiating modest deposition of manganese in shallow basin-margin oxygenated niches (e.g., deposits in India and Brazil). Rapid burial of organic matter, decline of reduced gases from a progressively oxygenated mantle and a net increase in photosynthetic oxygen marked the Archean-Proterozoic transition. Concurrently, a massive drawdown of atmospheric CO2 owing to increased weathering rates on the tectonically expanded freeboard of the assembled supercontinents caused Paleoproterozoic glaciations (2.45-2.22[no-break space]Ga). The spectacular sedimentary manganese deposits (at ca. 2.4[no-break space]Ga) of Transvaal Supergroup, South Africa, were formed by oxidation of hydrothermally derived Mn2 transferred from a stratified ocean to the continental shelf by transgression. Episodes of increased burial rate of organic matter during ca. 2.4 and 2.06[no-break space]Ga are correlatable to ocean stratification and further rise of oxygen in the atmosphere. Black shale-hosted Mn carbonate deposits in the Birimian sequence (ca. 2.3-2.0[no-break space]Ga), West Africa, its equivalents in South America and those in the Francevillian sequence (ca. 2.2-2.1[no-break space]Ga), Gabon are correlatable to this period. Tectonically forced doming-up, attenuation and substantial increase in freeboard areas prompted increased silicate weathering and atmospheric CO2 drawdown causing glaciation on the Neoproterozoic Rodinia supercontinent. Tectonic rifting and mantle outgassing led to deglaciation. Dissolved Mn2 and Fe2 concentrated earlier in highly saline stagnant seawater below the ice cover were exported to shallow shelves by transgression during deglaciation. During the Sturtian glacial-interglacial event (ca. 750-700[no-break space]Ma), interstratified Mn oxide and BIF deposits of Damara sequence, Namibia, was formed. The Varangian ([identical to] Marinoan; ca. 600[no-break space]Ma) cryogenic event produced Mn oxide and BIF deposits at Urucum, Jacadigo Group, Brazil. The Datangpo interglacial sequence, South China (Liantuo-Nantuo [identical to] Varangian event) contains black shale-hosted Mn carbonate deposits. The Early Paleozoic witnessed several glacioeustatic sea level changes producing small Mn carbonate deposits of Tiantaishan (Early Cambrian) and Taojiang (Mid-Ordovician) in black shale sequences, China, and the major Mn oxide-carbonate deposits of Karadzhal-type, Central Kazakhstan (Late Devonian). The Mesozoic period of intense plate movements and volcanism produced greenhouse climate and stratified oceans. During the Early Jurassic OAE, organic-rich sediments host many Mn carbonate deposits in Europe (e.g., Urkut, Hungary) in black shale sequences. The Late Jurassic giant Mn Carbonate deposit at Molango, Mexico, was also genetically related to sea level change. Mn carbonates were always derived from Mn oxyhydroxides during early diagenesis. Large Mn oxide deposits of Cretaceous age at Groote Eylandt, Australia and Imini-Tasdremt, Morocco, were also formed during transgression-regression in greenhouse climate. The Early Oligocene giant Mn oxide-carbonate deposit of Chiatura (Georgia) and Nikopol (Ukraine) were developed in a similar situation. Thereafter, manganese sedimentation was entirely shifted to the deep seafloor and since ca. 15[no-break space]Ma B.P. was climatically controlled (glaciation-deglaciation) assisted by oxygenated polar bottom currents (AABW, NADW). The changes in climate and the sea level were mainly tectonically forced

Palustrine Deposits on a Late Devonian Coastal Plain--Sedimentary Attributes and Implications for Concepts of Carbonate Sequence Stratigraphy, 2006, Macneil Alex J. , Jones Brian,
Palustrine deposits in coastal environments can cover thousands of square kilometers and are stratigraphically important. Palustrine deposits that originated in supratidal marshes can be used to track shifts in the shoreline position, whereas palustrine deposits that formed in marshes above the peritidal realm are indicative of subaerial unconformities. Despite the importance of these deposits, there are few documented examples of ancient coastal palustrine deposits, and their sedimentary attributes remain poorly understood. Misinterpretation of coastal palustrine deposits as marine deposits, or calcrete, may partly explain this situation. The Upper Devonian Alexandra Formation, exposed in the Northwest Territories of Canada, is formed of two reef complexes that are separated by a Type I sequence boundary. At the landward part of the platform, this boundary is marked by a succession of coastal-plain deposits that is ~ 50 cm thick. The most distinct aspect of this succession are palustrine deposits characterized by charophytes, skeletal (Rivularia) stromatolites, and various pedogenic features including complex crack networks, root traces, and authigenic kaolinite. Karst features and calcrete, generally regarded as typical indicators of subaerial exposure, are not found. This study highlights the sedimentary attributes that can be used to identify ancient palustrine deposits in marine coastal regions, distinguish these deposits from calcrete, and demonstrates their sequence stratigraphic significance, when found in marine limestone successions. It clearly demonstrates that palustrine deposits, like those found in the Alexandra Formation, should be considered indicative of subaerial unconformities and sequence boundaries, in the same manner as karst and calcrete

Impacts of Juniper Vegetation and Karst Geology on Subsurface Flow Processes in the Edwards Plateau, Texas, 2006, Dasgupta S, Mohanty Bp, Kohne Jm,
Impacts of Ashe juniper (Juniperus ashei J. Buchholz) and karst geology on the regional water cycle in the Edwards plateau region of Texas are complex and not well understood. The objective of our study was to gain a comprehensive understanding of the subsurface flow processes occurring at a juniper woodland site on the Edwards Plateau near Honey Creek State Natural Area. A 2.3-m-deep, 7-m-long trench was excavated at the downslope end of a 7 by 14 m experimental plot, and time domain reflectometry (TDR) probes were installed at various locations within the trench face to measure volumetric water contents. A multi-port telescopic boom type rainfall simulator was used to provide artificial rainfall on the plot. Six rainfall simulations and two dye-tracer tests were conducted on the plot during a 7-mo period. Subsurface flow was visually inspected at various locations on the trench face during artificial rainfall experiments and water content was monitored near slow and fast flow regions using TDR probes. The total volume of subsurface flow was also recorded after each rainfall simulation event. Results demonstrated that subsurface flow occurred in a bimodal manner, consisting of preferential/macropore flow around juniper root channels and planar fractures in the limestone, and pseudo-matrix flow through the soil matrix (water flowing primarily through the intermediate layers and lenses of soil between the rock layers). Preferential/macropore flow at the trench face depended on imposed boundary conditions and was independent of antecedent moisture content in the soil matrix. Pseudo-matrix flow response time decreased with high rainfall. During large rainfall events (>200 mm), water exchange was observed between the fractures and soil matrix. No apparent water exchange occurred between fractures and the soil matrix during small rainfall events. The dye studies indicated that fractures and juniper root channels are primary pathways for preferential/macropore flow occurring within the plot

Extended Abstract: Ecology and hydrology of a threatened groundwater-dependent ecosystem: the Jewel Cave karst system in Western Australia, 2006, Eberhard, Stefan M.

This thesis investigates the hydrology and ecology of a threatened aquatic root mat community in the Jewel Cave karst system in the Leeuwin-Naturaliste Ridge, Western Australia. Development of the karst system dates from the Early Pleistocene and the caves have been available for colonisation by groundwater fauna since that time. Speleogenesis of the watertable maze caves occurred in a flank margin setting during earlier periods of wetter climate and/or elevated base levels. Watertable fluctuations over the last 50 years did not exceed the range experienced in the Quaternary history. The recent groundwater decline in Jewel Cave was not related to rainfall, nor groundwater abstraction nor nearby tree plantations. However, it did coincide with a reduction in fire frequency within the karst catchment. The resultant increase in understorey vegetation and ground litter may have reduced groundwater recharge through increased evapotranspiration and interception of rainfall. The populations of two genera and species of cave dwelling Amphipoda are largely panmictic. Both species have survived lower watertable levels during the Late Pleistocene. A mechanism for the colonization and isolation of populations in caves is proposed. Faunal patterns (including species diversity, species assemblages, habitat associations and biogeography) were related to abiotic environmental parameters. The ecological water requirements of the community were determined as a baseline for evaluation of impacts such as groundwater pollution. If rainfall continues to decline, and the cave watertable declines > 0.5 m below the present level, then the groundwater ecosystem may become more vulnerable to extinction. The taxonomy and distribution of root mat communities is poorly known and a regional-scale survey is required to properly assess their conservation requirements. Meanwhile, conservation actions for the communities need to be focused at the scale of the karst drainage system and catchment area.


Origin and reservoir characteristics of Upper Ordovician TrentonBlack River hydrothermal dolomite reservoirs in New York , 2006, Smith, Jr. , L. B.

In the past decade, more than 20 new natural gas fields have been discovered in laterally discontinuous dolomites of the Upper Ordovician Black River Group in south-central New York. The dolomites form around basement-rooted wrench faults that are detectable on seismic data. Most fields occur in and around elongate faultbounded structural lows interpreted to be negative flower structures. Away from these faults, the formation is composed of impermeable limestone and forms the lateral seal for the reservoirs. In most cases, the faults die out within the overlying Trenton Limestone and Utica Shale. Most porosity occurs in saddle dolomitecoated vugs, breccias, and fractured zones. Matrix porosity is uncommon in the Black River cores described for this study. The patchy distribution around basement-rooted faults and geochemical and fluid-inclusion analyses supports a fault-related hydrothermal origin for the saddle and matrix dolomites. This play went for many years without detection because of its unconventional structural setting (i.e., structural lows versus highs). Using the appropriate integrated structural-stratigraphic-diagenetic model, more hydrothermal dolomite natural gas reservoirs are likely to be discovered in the Black River of New York and in carbonates around the world. 


Tectonic-hydrothermal brecciation associated with calcite precipitation and permeability destruction in Mississippian carbonate reservoirs, Montana and Wyoming , 2006, Katz D. A. , Eberli G. P. , Swart P. K. , Smith Jr. L. B.

The Mississippian Madison Formation contains abundant fracture zones and breccias that are hydrothermal in origin based on their morphology, distribution, and geochemical signature. The hydrothermal activity is related to crustal shortening during the Laramide orogeny. Brecciation is accompanied by dedolomitization, late-stage calcite precipitation, and porosity occlusion, especially in outcrop dolomites. The tectonic-hydrothermal late-stage calcite reduces permeability in outcrops and, potentially, high-quality subsurface reservoir rocks of the subsurface Madison Formation, Bighorn Basin. The reduction of permeability and porosity is increased along the margins of the Bighorn Basin but not predictable at outcrop scale. The destruction of porosity and permeability by hydrothermal activity in the Madison Formation is unique in comparison to studies that document enhanced porosity and permeability and invoke hydrothermal dolomitization models. Hydrothermal breccias from the Owl Creek thrust sheet are classified into four categories based on fracture density, calcite volume, and clast orientation. Shattered breccias dominate the leading edge of the tip of the Owl Creek thrust sheet in the eastern Owl Creek Mountains, where tectonic deformation is greatest, whereas fracture, mosaic, and chaotic breccias occur throughout the Bighorn Basin. The breccias are healed by calcite cements with d18O values ranging between _26.5 and _15.1xPeedee belemnite (PDB), indicating that the cements were derived from isotopically depleted fluids with elevated temperatures. In the chaotic and mosaic breccia types, large rotated and angular clasts of the host rock float in the matrix of coarse and nonzoned late-stage calcite. This appearance, combined with similar d18O values across even large calcite veins, indicates that the calcite precipitated rapidly after brecciation. Values for d13C(_5–12xPDB) from the frontal part of the Owl Creek thrust sheet indicate equilibrium between methane and CO2-bearing fluids at about 180jC. Fluid inclusions from the eastern basin margin show that these cements are in equilibrium with fluids having minimum temperatures between 120 and 140jC and formed from relatively low-salinity fluids, less than 5 wt.% NaCl. Strontium isotope ratios of these hydrothermal fluids are more radiogenic than proposed values for Mississippian seawater, suggesting that the fluids mixed with felsic-rich basement before migrating vertically into the Madison Formation. We envisage that the tectonic-hydrothermal late-stage calcitecemented breccias and fractures originated from undersaturated meteoric ground waters that migrated into the burial environment while dissolving and incorporating Ca2+ and CO3 2_ and radiogenic Sr from the dissolution of the surrounding carbonates and the felsic basement, respectively. In the burial environment, these fluids were heated and mixed with hypersaline brines from deeply buried parts of the basement. Expulsion of these fluids along basementrooted thrust faults into the overlying strata, including the Madison Formation, occurred most likely during shortening episodes of the Laramide orogeny by earthquake-induced rupturing of the host rock. The fluids were injected forcefully and in an explosive manner into the Madison Formation, causing brecciation and fracturing of the host rock, whereas the subsequent and sudden decrease in the partial pressure of CO2 caused the rapid precipitation of calcite cements. The explosive nature of hydrothermal fluid migration ultimately produces heterogeneities in reservoir-quality carbonates. In general, flow units in the Madison Formation are related to sequence boundaries, which create vertical subdivisions in the porous dolomite. The late-stage calcite cement surrounds hydrothermal breccia clasts and invades the dolomite, reducing porosity and permeability of the reservoir-quality rock. As a consequence, horizontal flow barriers and compartments are established that are locally unpredictable in their location and extent and regionally predictable along the margins of the Bighorn Basin. 


Successive Paleocene and Eocene infillings of polyphase paleokarsts within the Cretaceous limestones of the Emporda thrust sheets (Catalan Pyrenees, Spain) : relationships between tectonics and karsti, 2007, Peybernes Bernard, Fondecavewallez Marie Jose, Combes Pierre Jean, Seranne Michel,
The Mesozoic series of the southern units of the Pyrenean Emporda thrust sheets (Montgri and Figueres nappes, Catalonia, Spain) were finally emplaced over the autochthonous basement and its Cenozoic cover during Eocene times. However, they have originally been folded by the 'Laramian' compressional event (Late Cretaceous/Early Paleocene), while they were still in their root zone more than 50 km to the N-NE. Postdating the Santonian, the emersion of the Cretaceous tectorogen induced karst formation at the expense of Berriasian to Santonian limestone sequences. Karst cavities of this paleokarst 1 (lapiaz and canyons) were subsequently coated with a fine, red or black, Microcodium-bearing, continental silt, and infilled with marine chaotic breccias. Following a new episode of emersion then erosion, the original paleokarst 1 was cross-cut by newly formed cavities of the paleokarst 2, filled with Lutetian-Bartonian marine breccias. Both types of marine breccias (Paleocene then Eocene in age) are now relatively well dated by means of planktonic foraminifera (Globigerinacea) occurring within the argillaceous-sandy matrix, and for the older ones, within the argillaceous-sandy or carbonate, finely laminated, interbedded hemipelagites, that mark the top of marine sequences tens of centimetres thick. The relationships of the 'Laramian' and 'Pyrenean' compressional tectonic events, occurring from latest Cretaceous to Bartonian, with the development of paleokarsts 1 and 2 are analysed in the perspective of the progressive southwards emplacement of the Montgri thrust sheet, during Eocene time

Evidence for habitual use of fire at the end of the Lower Paleolithic: Site formation processes at Qesem Cave, Israel, 2007, Karkanas, P. , Shahackgross, R. , Ayalon, A. , Barmatthews, M. , Barkai, R. , Frumkin, A. , Gopher, A. , And Stiner, M. C.
The Amudian (late Lower Paleolithic) site of Qesem Cave in Israel represents one of the earliest examples of habitual use of fire by middle Pleistocene hominids. The Paleolithic layers in this cave were studied using a suite of mineralogical and chemical techniques and a contextual sedimentological analysis (i.e., micromorphology). We show that the lower ca. 3 m of the stratigraphic sequence are dominated by clastic sediments deposited within a closed karstic environment. The deposits were formed by small scale, concentrated mud slurries (infiltrated terra rosa soil) and debris flows. A few intervening lenses of mostly in situ burnt remains were also identified. The main part of the upper ca. 4.5 m consists of anthropogenic sediment with only moderate amounts of clastic geogenic inputs. The deposits are strongly cemented with calcite that precipitated from dripping water. The anthropogenic component is characterized by completely combusted, mostly reworked wood ash with only rare remnants of charred material. Micromorphological and isotopic evidence indicates recrystallization of the wood ash. Large quantities of burnt bone, defined by a combination of microscopic and macroscopic criteria, and moderately heated soil lumps are closely associated with the woodash remains. The frequent presence of microscopic calcified rootlets indicates that the upper sequence formed in the vicinity of the former cave entrance. Burnt remains in the sediments are associated with systematic blade production and faunas that are dominated by the remains of fallow deer. Use-wear damage on blades and blade tools in conjunction with numerous cut marks on bones indicate an emphasis on butchering and prey-defleshing activities in the vicinity of fireplaces.

A proposed conceptual model for the genesis of the Derbyshire thermal springs, 2007, Brassington Fc,
Ten thermal springs occur in seven centres in Derbyshire, England, with temperatures up to 27.5 {degrees}C compared with an ambient groundwater temperature of about 9 {degrees}C. The springs discharge from a karstic Dinantian limestone aquifer along the boundary with the overlying Namurian strata around the edge of a regional dome structure. The water is heated by deep circulation to as much as 1 km, with the hottest spring being at Buxton spring, where the water is 5000 years old. A comparison of flow data from the Buxton spring with groundwater hydrographs shows seasonality in the thermal flows, suggesting that the loading effects produced by recharge are transmitted through this deep aquifer system. From a review of the geological history and the hydrogeology and the use of measurements on the Buxton spring it is suggested that the thermal flow system may have its roots in ancient convection cells possibly established in the deeply buried aquifer in late Carboniferous-Early Permian times. Subaerial erosion during the Pliocene removed the impermeable cap rocks and allowed both the thermally heated water to form warm springs and this deep groundwater circulation to be recharged by meteoric waters. The location of the individual springs is likely to date from the downcutting during the Late Pleistocene that formed the modern river valley topography

FOSSIL VERTEBRATES AND PALEOMAGNETISM UPDATE OF ONE OF THE EARLIER STAGES OF CAVE EVOLUTION IN THE CLASSICAL KARST, SLOVENIA: PLIOCENE OF ČRNOTIČE II SITE AND RAČIŠKA PEČINA CAVE, 2007, HorÁ, Č, Ek I. , Mihevc A. , Zupan Hajna N. , Pruner P. , BosÁ, K P.

For the first time in the Classical Karst, paleontological data enabled to match the magnetostratigraphic record precisely with the geomagnetic polarity timescale in two studied sites: (i) a series of speleothems alternating with red clays in Račiška pečina Cave (Matarsko podolje), and (ii) an unroofed paleocave of the Črnotiče II site (Podgorski kras Plateau) completely filled by fluvial clastic sediments covered by speleothems. The later sites are also characterized by a rich appearance of fossil tubes of autochthonous stygobiont serpulid Marifugia cavatica. The vertebrate record is composed mostly of enamel fragments of rodents and soricomorphs. Absence of rootless arvicolids as well as taxonomic composition of the mammalian fauna suggests the Pliocene age of both sites. For (i) Račiška pečina (with Apodemus, cf. Borsodia) it was estimated to middle to late MN17 (ca 1.8–2.4 Ma), while (ii) the assemblage from Črnotiče II (with Deinsdorfia sp., Beremedia fissidens, Apodemus cf. atavus, Rhagapodemus cf. frequens, Glirulus sp., Cseria sp.) is obviously quite older: MN15–MN16 (ca 3.0–4.1 Ma). In respect to congruence of biostratigraphic and paleomagnetic data and a reliable sedimentary setting of the samples we propose to apply the respective datum also as the time of one ancient speleogenetic phase in the Classical Karst.


Results 16 to 30 of 52
You probably didn't submit anything to search for