Karst and Cave RSS news feed Like us on Facebook! follow us on Twitter!
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. ...

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. ...

Speleology in Kazakhstan

Shakalov on 11 Jul, 2012
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 recorder is an instrument designed to continuously or intermittently record measurements [16].?

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.
Engineering challenges in Karst, Stevanović, Zoran; Milanović, Petar
See all featured articles
Featured articles from other Geoscience Journals
Geochemical and mineralogical fingerprints to distinguish the exploited ferruginous mineralisations of Grotta della Monaca (Calabria, Italy), Dimuccio, L.A.; Rodrigues, N.; Larocca, F.; Pratas, J.; Amado, A.M.; Batista de Carvalho, L.A.
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
See all featured articles from other geoscience journals

Search in KarstBase

Your search for anhydrite (Keyword) returned 77 results for the whole karstbase:
Showing 1 to 15 of 77
Recent Anhydrite and Bassanite from Caves in Big Bend National Park, Texas, 1979, Hill, Carol A.

Subsidence and foundering of strata caused by the dissolution of Permian gypsum in the Ripon and Bedale areas, North Yorkshire, 1986, Cooper Ah,
Underground dissolution of thick gypsum beds in the Edlington Formation and Roxby Formation of the Zechstein sequence in North Yorkshire, England, has resulted in a 3 km-wide and 100 km-long belt of ground susceptible to foundering. Within this belt a large subsidence depression at Snape Mires, near Bedale, was largely filled with lacustrine deposits in the later part of the Late Devensian and during the Flandrian. South of Snape Mires the Nosterfield-Ripon-Bishop Monkton area has suffered about 40 episodes of subsidence in the past 150 years, and the presence of several hundred other subsidence hollows indicates considerable activity from the later part of the Devensian onwards. The linear and grid-like arrangement of these subsidence hollows indicates collapse at intersections in a joint-controlled cave system. Linear subsidence features at Snape Mires are also joint-controlled. The transition from anhydrite at depth to secondary gypsum near surface marks the down-dip limit of the subsidence-prone belt. Cavities are propagated upwards by roof collapse of caverns in the gypsum, leading to the formation of breccia pipes. Choking of the pipes can reduce the surface expression of the underground collapse, but the larger cavities are liable to produce pipes that reach the surface even at the eastern boundary of the 3 km-wide belt described. Further subsidence in the Ripon area is predicted and some suggestions for remedial measures are given

Yates and other Guadalupian (Kazanian) oil fields, U. S. Permian Basin, 1990, Craig Dh,
More than 150 oil and gas fields in west Texas and southeast New Mexico produce from dolomites of Late Permian (Guadalupian [Kazanian]) age. A majority of these fields are situated on platforms or shelves and produce from gentle anticlines or stratigraphic traps sealed beneath a thick sequence of Late Permian evaporites. Many of the productive anticlinal structures are elongate parallel to the strike of depositional facies, are asymmetrical normal to facies strike, and have flank dips of no more than 6{degrees}. They appear to be related primarily to differential compaction over and around bars of skeletal grainstone and packstone. Where the trapping is stratigraphic, it is due to the presence of tight mudstones and wackestones and to secondary cementation by anhydrite and gypsum. The larger of the fields produce from San Andres-Grayburg shelf and shelf margin dolomites. Cumulative production from these fields amounts to more than 12 billion bbl (1.9 x 109 m3) of oil, which is approximately two-thirds of the oil produced from Palaeozoic rocks in the Permian Basin. Eighteen of the fields have produced in the range from 100 million to 1.7 billion bbl (16-271 x 106 m3). Among these large fields is Yates which, since its discovery in October 1926, has produced almost 1.2 billion bbl (192 x 106 m3) out of an estimated original oil-in-place of 4 billion bbl (638 x 106 m3). Flow potentials of 5000 to 20 000 bbl (800 to 3200 m3) per day were not unusual for early Yates wells. The exceptional storage and flow characteristics of the Yates reservoir can be explained in terms of the combined effects of several geologic factors: (1) a vast system of well interconnected pores, including a network of fractures and small caves; (2) oil storage lithologies dominated by porous and permeable bioclastic dolograinstones and dolopackstones; (3) a thick, upper seal of anhydrite and compact dolomite; (4) virtual freedom from the anhydrite cements that occlude much porosity in other fields which are stratigraphic analogues of Yates; (5) unusual structural prominence, which favourably affected diagenetic development of the reservoir and made the field a focus for large volumes of migrating primary and secondary oil; (6) early reservoir pressures considerably above the minimum required to cause wells to flow to the surface, probably related to pressures in a tributary regional aquifer

Le karst du gypse des Andes de Mendoza-Neuquen (Argentine), 1992, Salomon J. N. , Bustos R.
THE GYPSUM KARST OF MENDOZA-NEUQUEN (ANDES, ARGENTINA) - Gypsum and anhydrite formations are highly developed in the Andes at the latitude of Santiago (Chile) and Mendoza (Argentina), where they have played a fundamental part in the various stages of the Andes orogeny. After a brief description of the geological background of the cordillera and some information on the main gypsum formations (Tabanos, Auquilco, Huitrin, Papol), the authors deal with the specific climatic context of the high cordillera: a cold and dry atmosphere (high altitude) apparently hardly propitious to the appearance of karstic phenomena. The latter nevertheless do exist and are often well-developed (Pozo de las Animas). They come mainly in the shape of domes and dolines whilst in the bottom of the valley numerous ferruginous crusts are noteworthy. Although the endokarst suffers from the fragility of the rock, a number of caves have developed, some of which are outstanding (Cueva del Leon, 1km).

Reactivated interstratal karst--example from the Late Silurian rocks of western Lake Erie (U.S.A.), 1992, Carlson Eh,
Interstratal karst developed in the Late Silurian rocks of western Lake Erie that, after a long interruption, was exhumed and reactivated. The dissolution front of the G evaporite of the Salina Group receded in the downdip direction during these two well-documented periods of subaerial exposure. The karst features that developed in the overlying Bass Islands Dolomite (Pridolian) consist of a large tabular body of collapse breccia and a number of smaller features including breccia pipes, partially filled pipes, blister caves and collapse dolines.The tabular breccia body and the breccia pipes, which originated penecontemporaneously during post-Silurian and pre-Middle Devonian subaerial exposure, occur along the updip edge of the present outcrop belt of the dolostone. They are monolithologic, fragment-supported rubble breccias, with the pipes exhibiting a greater fragment displacement, rotation and rounding, and a smaller fragment size. The matrix sediment of the tabular body is a quartz sand, an equivalent of the basal sandstone that filtered down from the erosion surface. The presence in the matrix sediment of nodular celestite, a later replacement of evaporites that formed when the sediment was still soft, indicates that a sabkha environment existed at the time the breccia was infilled. The partially filled pipes, which form cylindrical caves that are lined with late diagenetic celestite, are believed to be cogenetic with the collapse breccias.The blister caves and dolines occur downdip from the breccias, postdating Pleistocene glaciation and predating isostatic rebound. These caves are isolated, crescent- or oval-shaped openings with domed roofs, averaging about 60 m in width and 4 m in height. The hydration and resulting expansion of lenticular bodies of anhydrite along the receding solution front of the G unit is believed to be the cause of doming. The numerous crescentic caves, originating from the dissolution of this gypsum and the subsequent collapse of the domed roofs, are expressed at the surface as shallow dolines

REACTIVATED INTERSTRIATAL KARST EXAMPLE FROM THE LATE SILURIAN ROCKS OF WESTERN LAKE ERIE (USA), 1992, Carlson Eh,
Interstratal karst developed in the Late Silurian rocks of western Lake Erie that, after a long interruption, was exhumed and reactivated. The dissolution front of the G evaporite of the Salina Group receded in the downdip direction during these two well-documented periods of subaerial exposure. The karst features that developed in the overlying Bass Islands Dolomite (Pridolian) consist of a large tabular body of collapse breccia and a number of smaller features including breccia pipes, partially filled pipes, blister caves and collapse dolines. The tabular breccia body and the breccia pipes, which originated penecontemporaneously during post-Silurian and pre-Middle Devonian subaerial exposure, occur along the updip edge of the present outcrop belt of the dolostone. They are monolithologic, fragment-supported rubble breccias, with the pipes exhibiting a greater fragment displacement, rotation and rounding, and a smaller fragment size. The matrix sediment of the tabular body is a quartz sand, an equivalent of the basal sandstone that filtered down from the erosion surface. The presence in the matrix sediment of nodular celestite, a later replacement of evaporites that formed when the sediment was still soft, indicates that a sabkha environment existed at the time the breccia was infilled. The partially filled pipes, which form cylindrical caves that are lined with late diagenetic celestite, are believed to be cogenetic with the collapse breccias. The blister caves and dolines occur downdip from the breccias, postdating Pleistocene glaciation and predating isostatic rebound. These caves are isolated, crescent- or oval-shaped openings with domed roofs, averaging about 60 m in width and 4 m in height. The hydration and resulting expansion of lenticular bodies of anhydrite along the receding solution front of the G unit is believed to be the cause of doming. The numerous crescentic caves, originating from the dissolution of this gypsum and the subsequent collapse of the domed roofs, are expressed at the surface as shallow dolines

HALITE SALTERN IN THE CANNING BASIN, WESTERN-AUSTRALIA - A SEDIMENTOLOGICAL ANALYSIS OF DRILL CORE FROM THE ORDOVICIAN-SILURIAN MALLOWA SALT, 1992, Cathro Dl, Warren Jk, Williams Ge,
The Late Ordovician-Early Silurian Mallowa Salt of the Carribuddy Group, Canning Basin, north-west Australia, is the largest halite deposit known in Australia, attaining thicknesses of 800 m or more within an area of approximately 200 000 km2. Study of 675 m of drill core from BHP-Utah Minerals' Brooke No. 1 well in the Willara Sub-basin indicates that the Mallowa Salt accumulated within a saltern (dominantly subaqueous evaporite water body) that was subject to recurrent freshening, desiccation and exposure. Textures and bromine signatures imply a shallow water to ephemeral hypersaline environment typified by increasing salinity and shallowing into evaporitic mudflat conditions toward the top of halite-mudstone cycles (Type 2) and the less common dolomite/anhydrite-halite-mudstone cycles (Type 1). The borate mineral priceite occurs in the capping mudstones of some cycles, reinforcing the idea of an increasing continental influence toward the top of mudstone-capped halite cycles. The rock salt in both Type 1 and Type 2 cycles typically comprises a mosaic of large, randomly orientated, interlocking halite crystals that formed during early diagenesis. It only partially preserves a primary sedimentary fabric of vertically elongate crystals, some with remnant aligned chevrons. Intraformational hiati, halite karst tubes and solution pits attest to episodic dissolution. Stacked Type 2 cycles dominate; occasional major recharges of less saline, perhaps marine, waters in the same area produced Type 1 cycles. The envisaged saltern conditions were comparable in many ways to those prevailing during the deposition of halite cycles of the Permian Salado Formation in New Mexico and the Permian San Andres Formation of the Palo Duro Basin area in Texas. However, in the Canning Basin the cycles are characterized by a much lower proportion of anhydrite, implying perhaps a greater degree of continental restriction to the basin. The moderately high level of bromine in the Mallowa Salt (156.5 43.5 ppm Br for primary halite, 146.1 54.7 ppm Br for secondary halite) accords with evolved continental brines, although highly evaporative minerals such as polyhalite and magnesite are absent. The bromine levels suggest little or no dissolution/reprecipitation of primary halite and yet, paradoxically, there is little preservation of the primary depositional fabric. The preservation of early halite cements and replacement textures supports the idea of an early shutdown of brine flow paths, probably at burial depths of no more than a few metres, and the resultant preservation of primary bromine values in the secondary halite

DISLOCATION OF THE EVAPORITIC FORMATIONS UNDER TECTONIC AND DISSOLUTION CONTROLS - THE MODEL OF THE DINANTIAN EVAPORITES FROM VARISCAN AREA (NORTHERN FRANCE AND BELGIUM), 1993, Rouchy J. M. , Groessens E. , Laumondais A. ,
Within the Franco-Belgian segment of the Hercynian orogen, two thick Dinantian anhydritic formations are known, respectively in the Saint-Ghislain (765 m) and Epinoy 1 (904 m) wells. Nevertheless, occurrences of widespread extended breccias and of numerous pseudomorphs of gypsum/anhydrite in stratigraphically equivalent carbonate deposits (boreholes and outcrops), suggest a larger extent of the evaporitic conditions (fig. 1, 2). The present distribution of evaporites is controlled by palaeogeographical differentiation and post-depositional parameters such as tectonics and dissolution. These latter have dissected the deposits formerly present in all the structural units. By using depositional, diagenetic and deformational characters of these formations, the article provides a model for the reconstruction of a dislocated evaporitic basin. This segment of the Hercynian chain is schematically composed of two main units (fig. 1, 3) : (1) the autochthonous or parautochthonous deposits of the Namur synclinorium, (2) the Dinant nappe thrusted northward over the synclinorium of Namur. The major thrust surface is underlined by a complex fault bundle (faille du Midi) seismically recognized over more than 100 km. A complex system of thrust slices occurs at the Hercynian front. Except for local Cretaceous deposits, most of the studied area has been submitted to a long period of denudation since the Permian. Sedimentary, faunistic and geochemical data argue for a marine origin of the brines which have generated the evaporites interbedded with marine limestones. Sedimentary structures. - The thick evaporitic formations are composed of calcium-sulfates without any clear evidence of the former presence of more soluble salts (with the exception of a possible carbonate-sulfate breccia in the upper part of the Saint-Ghislain formation). As in all the deeply buried evaporitic formations, the anhydrite is the main sulfate component which displays all the usual facies : pseudomorphs after gypsum (fig. 4A, B), nodular and mosaic (fig. 4C), laminated. The gypsum was probably an important component during the depositional phase despite the predominant nodular pattern of the anhydrite. Early diagenetic nodular anhydrite may have grown during temporary emersion of the carbonates (sabkha environments), but this mechanism cannot explain the formation of the whole anhydrite. So, most of the anhydrite structures result from burial-controlled gypsum --> anhydrite conversion and from mechanical deformations. Moreover, a complex set of diagenetic processes leads to various authigenic minerals (celestite, fluorite, albite, native sulfur, quartz and fibrous silica) and to multistaged carbonate <> sulfate replacements (calcite and dolomite after sulfate, replacive anhydrite as idiomorphic poeciloblasts, veinlets, domino-like or stairstep monocrystals...). These mineral transformations observed ill boreholes and in outcrops have diversely been controlled during the complex evolution of the series as : depositional and diagenetic pore-fluid composition, pressure and temperature changes with burial, bacterial and thermochemical sulfate reduction, deep circulations favored by mechanical brecciation, mechanical stresses, role of groundwater during exhumation of the series. Deformational structures. - A great variety of deformational structures as rotational elongation, stretching, lamination, isoclinal microfolding, augen-like and mylonitic structures are generated by compressive tectonic stresses (fig. 4D to J). The similarities between tectonic-generated structures and sedimentary (lamination) or diagenetic (pseudo-nodules) features could lead lo misinterpretations. The calcareous interbeds have undergone brittle deformation the style and the importance of which depend of their relative thickness. Stretching, boudins, microfolds and augen structures F, H. I) affect the thin layers while thicker beds may be broken as large fractured blocks dragged within flown anhydrite leading to a mylonitic-like structure (fig, 4G). In such an inhomogeneous formation made of interlayered ductile (anhydrite) and brittle (carbonate) beds, the style and the intensity of the deformation vary with respect to the relative thickness of each of these components. Such deformational features of anhydrite may have an ubiquitous significance and can result either from compressive constraints or geostatic movements (halokinesis). Nevertheless, some data evidence a relation with regional tangential stresses: (1) increase of the deformation toward the bottom of the Saint-Ghislain Formation which is marked by a deep karst suggesting the presence of a mechanical discontinuity used as a drain for dissolving solutions (fig. 3, 4); (2) structural setting (reversed series, internal slidings) of the Epinoy 1 formation under the Midi thrust. However, tectonic stresses also induce flowing deformations which have contributed to cause their present discontinuity. It can be assumed that the evaporites played an active role for the buckling of the regional structure as detachment or gliding layers and more specifically for the genesis of duplex structures. Breccia genesis. - Great breccia horizons are widely distributed in outcrops as well as in the subsurface throughout the greater part of the Dinant and Namur units (fig. 2). The wide distribution of pseudomorphosed sulfates in outcrops and the stratigraphical correlation between breccia and Saint-Ghislain evaporitic masses (fig. 2) suggest that some breccia (although not all) have been originated from collapse after evaporites solution. Although some breccia may result from synsedimentary dissolution, studied occurrences show that most of dissolution processes started after the Hercynian deformation and, in some cases, were active until recently : elements made of lithified and fractured limestones (Llandelies quarries) (fig. 5A), preservation of pseudomorphs of late replacive anhydrite (Yves-Gomezee) (fig. 5B, C), deep karst associated with breccia (Douvrain, Saint Ghislain, Ghlin boreholes) (fig. 3, 4, 5D)). Locally, the final brecciation may have been favored by a mechanical fragmentation which controlled water circulations (fig. 5E). As postulated by De Magnee et al. [19861, the dissolution started mostly after the Permian denudation and continued until now in relation with deep circulations and surface weathering (fig. 6). So, the above-mentioned occurrences of the breccia are logically explained by collapse after dissolution of calcium-sulfates interbeds of significant thickness (the presence of salt is not yet demonstrated), but other Visean breccia may have a different origin (fig. 5F). So, these data prove the extension of thick evaporitic beds in all the structural units including the Dinant nappe, before dissolution and deformation. Implications. - Distribution of Visean evaporites in northern France and Belgium is inherited from a complicated paleogeographic, tectonic and post-tectonic history which has strongly modified their former facies, thicknesses and limits (fig. IA, 6). Diversified environments of deposition controlled by both a palaeogeographical differentiation and water level fluctuations led to the deposition of subaqueous (gypsum) or interstitial (gypsum, anhydrite) crystallization. Nevertheless, most of the anhydrite structures can be interpreted as resulting from burial conversion of gypsum to anhydrite rather than a generalized early diagenesis in sabkha-like conditions. Deformation of anhydrite caused by Hercynian tangential stresses and subsequent flow mechanisms, have completed the destruction of depositional and diagenetic features. The tectonic deformations allow us to consider the role of the evaporites in the Hercynian deformations. The evaporites supplied detachment and gliding planes as suggested for the base of the Saint-Ghislain Formation and demonstrated by the structural setting of Epinoy 1 evaporites in reverse position and in a multi-system of thrust-slices below the Midi overthrust (fig. 7). So, although the area in which evaporation and precipitation took place cannot be exactly delineated in geographic extent, all the data evidence that the isolated thick anhydritic deposits represent relics of more widespread evaporites extending more or less throughout the different structural units of this Hercynian segment (fig. 1B). Their present discontinuity results from the combination of a depositional differentiation, mechanical deformations and/or dissolution

RAPID ENTRENCHMENT OF STREAM PROFILES IN THE SALT CAVES OF MOUNT SEDOM, ISRAEL, 1995, Frumkin A, Ford Dc,
Rock salt is approximately 1000 times more soluble than limestone and thus displays high rates of geomorphic evolution. Cave stream channel profiles and downcutting rates were studied in the Mount Sedom salt diapir, Dead Sea rift valley, Israel. Although the area is very arid (mean annual rainfall approximate to 50 mm), the diapir contains extensive karst systems of Holocene age. In the standard cave profile a vertical shaft at the upstream end diverts water from a surface channel in anhydrite or elastic cap rocks into the subsurface route in the salt. Mass balance calculations in a sample cave passage yielded downcutting rates of 0.2 mm s(-1) during peak flood conditions, or about eight orders of magnitude higher than reported rates in any limestone cave streams. However, in the arid climate of Mount Sedom floods have a low recurrence interval with the consequence that long-term mean downcutting rates are lower: an average rate of 8.8 mm a(-1) was measured for the period 1986-1991 in the same sample passage. Quite independently, long-term mean rates of 6.2 mm a(-1) are deduced from C-14 ages of driftwood found in upper levels of 12 cave passages. These are at least three orders of magnitude higher than rates established for limestone caves. Salt cave passages develop in two main stages: (1) an early stage characterized by high downcutting rates into the rock salt bed, and steep passage gradients; (2) a mature stage characterized by lower downcutting rates, with establishment of a subhorizontal stream bed armoured with alluvial detritus. In this mature stage downcutting rates are controlled by the uplift rate of the Mount Sedom diapir and changes of the level of the Dead Sea. Passages may also aggrade. These fast-developing salt stream channels may serve as full-scale models for slower developing systems such as limestone canyons

Karst Geomorphology and Hydrogeology of the Northeastern Mackenzie Mountains, District of Mackenzie, N.W.T., PhD Thesis, 1995, Hamilton, James P.

This thesis describes the geomorphology and hydrogeology of karst systems in portions of the northeastern Canyon Ranges of the Mackenzie Mountains and the Norman Range of the Franklin Mountains. N.W.T. In the region, mean annual temperatures are -6 to -8°C, total annual precipitation is 325 to 500 mm, and permafrost has a widespread to continuous distribution. The area was glaciated in the Late Wisconsinan by the Laurentide Ice Sheet.
The Canyon Ranges and Norman Range are composed of a sequence of faulted and folded miogeoclinal sedimentary rocks that span the Proterozoic to Eocene. The geology is reviewed with an emphasis on strata that display karst. Included are several dolomite and limestone formations, two of which are interbedded with evaporites in the subsurface. The principal groundwater aquifer is the Lower Devonian Bear Rock Formation. In subcrop, the Bear Rock Formation is dolomite and anhydrite, outcrops are massive calcareous solution breccias. This is the primary karst rock.
The regional distribution and range of karst landforms and drainage systems are described. Detailed mapping is presented from four field sites. These data were collected from aerial photography and ground surveys. The karst has examples of pavement, single and compound dolines, subsidence troughs, polje, sinking streams and lakes. and spring deposits. The main types of depressions are subsidence and collapse dolines. Doline density is highest on the Bear Rock Formation. Surficial karst is absent of less frequent in the zone of continuous permafrost or outside the glacial limit.
At the field sites, water samples were collected at recharge and discharge locations. Samples were analyzed for a full range of ionic constituents and many for natural isotopes. In addition, several springs were monitored continuously for discharge, temperature, and conductivity. Dye tracing established linkages between recharge and discharge at some sites. These data are summarized for each site, as is the role of permafrost in site hydrology.
The relationships between geological structure, topography, ,and groundwater systems are described. Conduit aquifers are present in both dolomite and limestone. These systems are characterized by discharge waters of low hardness and dissolved ion content. Aquifers in the Bear Rock Formation have a fixed flow regime and often have highly mineralized discharge. At the principal field site. there was a time lag of 40 to 60 days between infiltration and discharge in this unit. At a second site, flow through times were on the order of years. Variability in these systems is attributed to bedrock properties and boundary conditions.
Preliminary rates of denudation are calculated from the available hydrochemical data. Total solutional denudation at the primary field site is approximately 45 m³ kmˉ² aˉ¹ (mm kaˉ¹). The majority is attributed to the subsurface dissolution of halite and anhydrite. The predominance of subsurface dissolution is linked to the high frequency of collapse and subsidence dolines and depressions.
The karst features and drainage systems of the northern Mackenzie Mountains date to the Tertiary. Glaciation has had a stimulative effect on karst development through the subglacial degradation of permafrost and the altering of boundary conditions by canyon incision.


Un aquifre gypseux de haute montagne : mesures physico-chimiques et traage dans la valle de Gbroulaz (Vanoise, France), 1996, Dzikowski M. , Nicoud G. , Arfib B. , Paillet A. , Rovera G.
During the high flow period of summer 1995, conductivity and temperature were periodically measured in two losses and five springs along a gypsum and anhydrite outcrop in the Gbroulaz valley. These experiments together with a water chemical analysis and an artificial tracer test have highlighted two kinds of flows through the evaporitic formations. The springs are characterised by a rapid flow directly influenced by the infiltration of melt water in a surficial karst. A slower flow shows a deeper circulation through a saturated and fissured milieu. So, in a high mountainous area, the gypsum layer shows a surficial karst over a fissured aquifer. This interpretation allows us to explain the stability of the physico-chemical parameters for the springs, which are not influenced by karstic flow conditions.

Sulphate rocks as an arena for karst development., 1996, Andrejchuk Vjacheslav, Klimchouk Alexander
The rocks in which karst systems develop are most commonly composed of carbonate sulphate and chloride minerals. The sulphate minerals are quite numerous, but only gypsum and anhydrite form extensive masses in sedimentary sequences. Other minerals, which represent sulphates of K, Mg and Na, normally occur as minor beds (0.1-5.0 m), or as inclusions associated with chloride rocks. However some minerals precipitated in salt-generating basins, such as mirabilite and glauberite (typically formed in the Kara-Bogaz-Gol Gulf, salt lakes of Siberia and in China), form sequences up to 5-10 m thick where karst may develop. Due to the very high solubility of Na -sulphates, karst processes and features occurring in these rocks resemble salt karst. Thus, the term sulphate karst, although not strictly correct, is used mainly to indicate karst developed in gypsum and anhydrite.

The dissolution and conversion of Gypsum and Anhydrite., 1996, Klimchouk Alexander
The development of karst is a complex system driven by the dissolution of a host rock and the subsequent removal of dissolved matter by moving water. It is the process that, at various stages, initiates or triggers associated processes including erosion, collapse and subsidence. The dissolution of sulphate rocks proceeds by different mechanisms and at different rates to those associated with the dissolution of carbonate rocks. For each rock type different factors influence the process. This chapter is an attempt to summarise the present knowledge of the dissolution chemistry and kinetics of gypsum and anhydrite. These are important for the genetic interpretation of karst features in these rocks. The gypsum-anhydrite-gypsum transitions and recrystallization processes are also addressed, because of their importance to karst development.

Evaporites, brines and base metals: What is an evaporite? Defining the rock matrix, 1996, Warren J. K. ,
This paper, the first of three reviews on the evaporite-base-metal association, defines the characteristic features of evaporites in surface and subsurface settings. An evaporite is a rock that was originally precipitated from a saturated surface or near-surface brine in hydrological systems driven by solar evaporation. Evaporite minerals, especially the sulfates such as anhydrite and gypsum, are commonly found near base-metal deposits. Primary evaporites are defined as those salts formed directly via solar evaporation of hypersaline waters at the earth's surface. They include beds of evaporitic carbonates (laminites, pisolites, tepees, stromatolites and other organic rich sediment), bottom nucleated salts (e.g. chevron halite and swallow-tail gypsum crusts), and mechanically reworked salts (such as rafts, cumulates, cross-bedded gypsarenites, turbidites, gypsolites and halolites). Secondary evaporites encompass the diagenetically altered evaporite salts, such as sabkha anhydrites, syndepositional halite and gypsum karst, anhydritic gypsum ghosts, and more enigmatic burial associations such as mosaic halite and limpid dolomite, and nodular anhydrite formed during deep burial. The latter group, the burial salts, were precipitated under the higher temperatures of burial and form subsurface cements and replacements often in a non-evaporite matrix. Typically they formed from subsurface brines derived by dissolution of an adjacent evaporitic bed. Because of their proximity to 'true' evaporite beds, most authors consider them a form of 'true' evaporite. Under the classification of this paper they are a burial form of secondary evaporites. Tertiary evaporites form in the subsurface from saturated brines created by partial bed dissolution during re-entry into the zone of active phreatic circulation. The process is often driven by basin uplift and erosion. They include fibrous halite and gypsum often in shale hosts, as well as alabastrine gypsum and porphyroblastic gypsum crystals in an anhydritic host. In addition to these 'true' evaporites, there is another group of salts composed of CaSO4 or halite. These are the hydrothermal salts. Hydrothermal salts, especially hydrothermal anhydrite, form by the subsurface cooling or mixing of CaSO4- saturated hydrothermal waters or by the ejection of hot hydrothermal water into a standing body of seawater or brine. Hydrothermal salts are poorly studied but often intimately intermixed with sulfides in areas of base-metal accumulations such as the Kuroko ores in Japan or the exhalative brine deeps in the Red Sea. In ancient sediments and metasediments, especially in hydrothermally influenced active rifts and compressional belts, the distinction of this group of salts from 'true' evaporites is difficult and at times impossible. After a discussion of hydrologies and 'the evaporite that was' in the second review, modes and associations of the hydrothermal salts will be discussed more fully in the third review

Dissolution and conversions of gypsum and anhydrite., 1996, Klimchouk A. B.

Results 1 to 15 of 77
You probably didn't submit anything to search for