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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 speleogen is a secondary cave structure formed by dissolving, such as a dome pit or a scallop [10].?

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Featured articles from Cave & Karst Science Journals
Chemistry and Karst, White, William B.
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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
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Your search for units (Keyword) returned 164 results for the whole karstbase:
Showing 1 to 15 of 164
Fungal communities on speleothem surfaces in Kartchner Caverns, Arizona, USA, , Vaughan Michael J. , Maier Raina M. , Pryor Barry M.

Kartchner Caverns, located near Benson, Arizona, USA, is an active carbonate cave that serves as the major attraction for Kartchner Caverns State Park. Low-impact development and maintenance have preserved prediscovery macroscopic cavern features and minimized disturbances to biological communities within the cave.. The goal of this study was to examine fungal diversity in Kartchner Caverns on actively-forming speleothem surfaces. Fifteen formations were sampled from five sites across the cave. Richness was assessed using standard culture-based fungal isolation techniques. A culture-independent analysis using denaturing gradient gel electrophoresis (DGGE) was used to assay evidence of community homogeneity across the cave through the separation of 18S rDNA amplicons from speleothem community DNA. The culturing effort recovered 53 distinct morphological taxonomic units (MTUs), corresponding to 43 genetic taxonomic units (GTUs) that represented 21 genera. From the observed MTU accumulation curve and the projected total MTU richness curve, it is estimated that 51 percent of the actual MTU richness was recovered. The most commonly isolated fungi belonged to the genera Penicillium, Paecilomyces, Phialophora, and Aspergillus. This culturebased analysis did not reveal significant differences in fungal richness or number of fungi recovered across sites. Cluster analysis using DGGE band profiles did not reveal distinctive groupings of speleothems by sample site. However, canonical correspondence analysis (CCA) analysis of culture-independent DGGE profiles showed a significant effect of sampling site and formation type on fungal community structure. Taken together, these results reveal that diverse fungal communities exist on speleothem surfaces in Kartchner Caverns, and that these communities are not uniformly distributed spatially. Analysis of sample saturation indicated that more sampling depth is required to uncover the full scale of mycological richness across spelothem surfaces.


Contribution to the study of certain Lithobiidae (Chilopoda) of Romanian caves., 1965, Negrea Stefan
This paper comprises the ecological and zoogeographical data of 21 systematic units of Lithobiidae coming from 100 Romanian caves (Transylvania, Banat, Oltenie and Dobroudja). Initially the author describes in a summarising way the provenance of the studied material, after which he exposes fro every species the results of observations carried out by several authors and by himself. Finally he formulates the conclusions concerning ecology and biogeography resulting from his observations. These data are summarised in a synoptic table in which three species can be considered troglobionts, two of which are blind; these are Harpolithobius oltenicus Negrea; Lithobius decapolitus Matic, Negrea et Prunescu; Lithobius daeicus Matic; The other 18 species found are 5 troglophiles, 12 sub-troglophiles and 1 trogloxene.

Contribution on the study of European Bathynella: Bathynella natans Vejdovsky, a dilemma to resolve., 1966, Serban Eugne.
After a minute study of the structure of the 8th male pereiopod in some Bathynella populations from Romania and England, the structure differences which were found allowed to identify two well individualized kinds of pereiopods; they were named type natans and type stammen. Taking into account the striking differences between these two types, B. stammeri (Jakobi), which since 1954 is considered to be a subspecies of the natans species, was separated out of the species B. natans sensu Jakobi (1954). The populations understudied were collected in England and Romania, their minute study being the object of an other note, collaboration with T. Gledhill. The facts led to the conclusion that Jakobis opinion (1954), which dominated the taxonomy of this group, doesnt entirely correspond to the reality, the two taxonomical units being characterized as follows:; Bathynelta natans Vejdovsky, characterized by the 8th male pereiopod (fig. I A) with a triangular, well developed anterior plate (fig. 3 A-D-a; 7 A-D), of the same length with the exopodit, a cylindrical internal lobe (fig. 3 A-D-b,) and a little lobe (fig. 3 A-D-c) of a reduced size;; Bathynella stammeri (Jakobi) differing from the first with respect to the anterior pinte (fig. 2 A-D-a; 6A-C) which is rectangular in shape and has a prolongation in the distal outer angle, to the conelike internal lobe (fig. 2 AD-b), and to the little lobe (fig. 2 A-D-d) which is twolobed in this case. After discussion on the relationship between B. catena Vejd. and B. stammeri (Jakobi) it is shown that differences observed in the 8th male pereiopod structure give important indications about the above species to the effect that they are not very closely related. If one takes into account also their wide spreading area, and the individualisation of some populations due to important, characteristic traits; we are obliged to classify them into two different sub-genera. In the first one, the species catena is included; which will keep by this way the very name of the genus, and in the second, termed here Antrobathynella, the species stammeri. In conclusion, what was till now considered as Bathynella natans Vejdovsky sensu Jakobi, was divided into two distinct species each of them pertaining to two different sub-genera, that is: Bathynella (Bathynella) natans Vejdovsky and Bathynella (Antrobathynella) stammeri (Jakobi). It is demonstrated that the synonymy Jakobi made between B.chappuisi and B. natans is perfectly true under the new conditions too, because it was Delachaux (1919) who rediscovered B.natans Vejd., not Chappuis (1914). The material found by Chappuis in Basel (1914) appears to pertain to B. stammeri (Jakobi) differing both from the individuals from the Grotte de Ver (Delachaux, 1919) and from Prague (Vejdovsky, 1882).

Chronology of the Black Sea over the last 25,000 years, 1972, Degens Et, Ross Da,
Deep-water sediments of the Black Sea deposited during Late Pleistocene and Holocene time are distinguished by three sedimentary units: (1) a microlaminated coccolith ooze mainly consisting of Emiliania huxleyi; (2) a sapropel; and (3) a banded lutite. The base of the first unit lies at 3,000 years B.P., that of the second at 7,000 years B.P., and that of the third at least at about 25,000 years B.P. Fossils and geochemical criteria are used to decipher the environmental events of this time period. Beginning with the base of the section dated at about 25,000 years B.P. we witness the final stage of metamorphosis from anoxic marine to oxic freshwater conditions. By the time this stage ended, about 22,000 years B.P., the Black Sea had become a truly freshwater habitat. The lake phase lasted about 12,000 to 13,000 years. Sedimentation rates were in the order of 1 m/103 years, but began to decrease as sea level rose during the last 5,000 years of this phase (9,000-15,000 years B.P.). Starting at about 9,000 years B.P. and continuing to 7,000 years B.P., Mediterranean waters occasionally spilled over the Bosporus as a consequence of ice retreat and sea level rise. This marked the beginning of a gradual shift from freshwater to marine, and from well aerated to stagnant conditions. At about 7,000 years B.P. when deposition of unit 2 started, the H2S zone was well established. Sedimentation rates dropped to 10 cm/103 years. Environmental conditions similar to those of today finally became established around 3,000 years B.P., almost exactly the time when Jason and the Argonauts sailed through the Bosporus in search of the Golden Fleece

Ecological and biogeographical trends in Harpacticoids., 1976, Jakobi Hans
The majority of harpacticoids show a great dependence on the peculiarities of their habitat. This research attempted to detect the possible existence of biogeographical and ecological trends. The limited biogeographical data is discussed, so this is applied the method of analysis of morpho-ecological correlation (Jakobi, 1962) developed to determine ecological trends. This way, all characteristics of the harpacticoidean body selected were studied to check their adaptative value. Based on those results it was possible to establish and to define ecological units. Data were then subjected to statistical tests of homogeneity for variance and significance. Graphs are used to demonstrate the natural adaptation process. Diagrams permit one to recognize the general tendencies as well as degrees of specific evolution. Nevertheless, quite different principles such as type formation and atomic orbit model analogy, were applied to understand biogeographic trends. The change of the endopodits of the 4th leg of adult males (Enp. P4 male) is utilized as an example.

Les massifs karstiques des Alpes occidentales, trame structurale et bioclimatique, 1984, Nicod, J.
THE KARSTIC MASSIFS OF WESTERN ALPS: structural and bioclimatic framework - The structural conditions determine several types of karst units: the northern Prealps (thrusts), the southern Jura (folded or tabular), the southern Prealps (faulted and folded plateaus), the complex land of Low Provence, and the high karsts of Inner Alps. The bioclimatic framework explains the altitudinal sequence of current processes. The value of the runoff, the part of the snow, and the biochemical parameters (vegetation, CO2), have particularly holded the attention. The specific dissolution reaches its maximum in the wooded mountain karsts. Heritages also determine the landforms (glacial, periglacial, terra-rossa).

Depositional history of the late Pleistocene limestones of the Kenya coast, 1984, Braithwaite Cjr,
The coastal limestones of Kenya extend approximately 180 km N-S from Malindi to the Tanzanian border. They are at least 20 m thick and may be subdivided into sedimentary units representing major periods of marine deposition punctuated by sub-aerial erosion. Their foundations are formed by thick fluvial and aeolian quartz sands but there is local evidence of marine deposition following these. In the main limestone unit, deposited about 240,000 years ago, initial high energy shallow-shelf deposition was replaced by quiet water sediments with scattered corals. Sea level stood about 8 m higher than at present. Quartzose sands were confined to western areas. A return to shallow water heralded a new phase of emergence and erosion, producing karst surfaces and sub-aerial sediments. These are overlain by herring-bone cross-bedded quartz-rich calcarenites which were the products of a tidally dominated shelf and, at Watamu and Wasini, pass upwards into aeolian dune deposits. However, these were also emersed and subject to karst erosion before deposition of a further widespread marine limestone. Within this, coral knolls are well developed. Much of the sediment accumulated in shallow water, but the ecological succession indicates that knolls were at times in deeper waters. These deposits formed about 125,000 years ago when sea level ultimately stood 15-20 m above its present position. More recently in the area sea level has again fallen. However, the descent was not continuous and pauses were marked by marine terrace formation and subsequent karst erosion with sub-aerial deposition. Brief reversals caused both terraces and sediments to be overlain by thin marine deposits. Sea level paused at its present position about 30,000 years ago when the present reef platform was probably defined. It continued to fall to a maximum of about-120 m before rising to its existing level 7000 years ago and beginning the current cycle of sediment accumulation

Climatostratigraphic scheme of the Black Sea pleistocene and its correlation with the oxygen-isotope scale and glacial events, 1988, Zubakov V. A. ,
New evidence from the Asov Sea-Black Sea region shows that after the Cobb Mountain magnetic event (1.1 myr) there were 8 saline water events, with Mediterranean molluscs penetrating into the Asov Sea (five times farther than the western Manych Strait), and 7 or 10 cold freshwater events. During the freshening phase, the Caspian Sea molluscan fauna penetrated into the Black Sea; each time the Caspian mollusc assemblage was characterized by a new species of Didacna. Thus, some 18-20 bioclimatostratigraphic units can be distinguished in the Asov Sea-Black Sea section for the last 1 myr. Their numerical age is estimated by some dozen thermoluminescence dates and 12 magnetic-polarity datum planes. The Karangatian s. lato corresponds to the interval 300,000-50,000 yr, the Uzunlarian to 580,000-300,000 yr, and the Chaudian to 1,100,000-600,000 yr. The Karangatian and Tyrrhenian marine terraces correspond to marine isotope stages 5 and 7, the Uzunlarian and Milazzian to stages 11-15, and the Chaudian and Sicilian to stages 16-28. The number and ages of glacial-interglacial cycles in continental Europe are identical to the climatic cycles in the Black Sea and Mediterranean

IMPLICATIONS OF A PALEOMAGNETIC STUDY OF THE SILICA NAPPE, SLOVAKIA, 1991, Marton P. , Rozloznik L. , Sasvari T. ,
The Silica nappe (s.l.) of the Inner West Carpathians consists of an essentially non-metamorphic, platform-type sedimentary complex of Mesozoic (chiefly Triassic) age. Palaeomagnetic samples were collected from 16 sites throughout the southern and northern Gemeric parts of this unit and from one site of the Mesozoic Meliata series which underlies the Silica nappe (s.s.) in south Gemer. The samples from each site were treated using thermal demagnetization and well-grouped magnetic directions of individual components were found for 13 (14) sites. Detailed analysis of the directional data showed (a) post-folding magnetization for four late Triassic-Jurassic sites in the eastern Slovak Karst, (b) synfolding magnetization for five sites in the western Slovak Karst with a direction corresponding to local palaeomagnetic data of African affinity for the late Cretaceous and (c) primary magnetizations in the northern Gemeric area for only two rock units with a declination difference which implies a relative rotation between these units. As all secondary remanences are of normal polarity it is very likely that their acquisition is related to the emplacement of the Silica nappe during the early late Cretaceous. The dominant remagnetization mechanism probably is CRM but occasional contributions of TVRM are also conceivable

A geological review of Abercrombie caves, 1991, Osborne, R. A. L.

Abercrombie caves (near Jenolan, N.S.W.) have developed in metamorphosed marble forming part of the Upper Silurian Kildrummie Formation. Geological structure and changes in lithology have strongly influenced cave development with pyritic thinly bedded units in the marble being preferentially eroded. The Abercrombie Arch originated as a through cave in Pliocene times, 4-5 millions years ago.


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

THE EVOLUTION OF THE MIDDLE TRIASSIC (MUSCHELKALK) CARBONATE RAMP IN THE SE IBERIAN RANGES, EASTERN SPAIN - SEQUENCE STRATIGRAPHY, DOLOMITIZATION PROCESSES AND DYNAMIC CONTROLS, 1993, Lopezgomez J. , Mas R. , Arche A. ,
The Upper Permian-Triassic strata of the SE Iberian Ranges, eastern Spain, display the classic Germanic-type facies of Buntsandstein, Muschelkalk and Keuper. The Muschelkalk is represented by two carbonate units with a siliciclastic-evaporitic unit in between. Their ages range from Anisian to basal Carnian (Middle Triassic to base of the Upper Triassic). The carbonate units represent ramps that evolved during the early thermal subsidence period which succeeded the first rift phase. Seven facies have been distinguished, representing shoals, tidal flats, organic buildups and lagoons, as well as a karst horizon in the lower carbonatic unit. Most of the carbonates were dolomitised. Three processes of dolomitization are invoked: mixing waters, penecontemporaneous seepage refluxion, and deep burial. The top of the Buntsandstein and the Muschelkalk facies are subdivided into two depositional sequences, including lowstand, transgressive and highstand systems tracts, with superimposed tectonic and eustatic controls

GEOMORPHOLOGY, STRATIGRAPHY AND C-14 CHRONOLOGY OF ANCIENT TUFAS AT LOUIE-CREEK, NORTHWEST QUEENSLAND, AUSTRALIA, 1994, Drysdale R, Head J,
Louie Creek is a karst springfed stream situated in the seasonally humid tropics of northwest Queensland, Australia. It rises as a series of small exsurgences along the eastern edge of the Barkly Tableland. As it enters the lowlands of the Carpentaria plain, the creek deposits tufa which produces a series of cascades. This modern tufa extends discontinuously for about 1.5 km. A series of ancient tufas, in places lying adjacent to sites of modern deposition, extends discontinously for about 8 km downstream. At least two ancient tufa units are preserved at one location, Little Indarri site. The older unit comprises a sequence of well-preserved barrages with an orientation transverse to present-day stream flow. In places, erosion has reduced these barrages to their calcrete substrate. The older tufa is overlain in places by sediment which has become cemented to form a second calcrete unit. This sediment is in turn succeeded by the younger ancient tufa. Subsequent river incision has removed part of the sediment from the older unit and exposed several contact points between the ancient tufa and calcrete units. Radiocarbon dating of the Little Indarri site tufas, as well as other ancient Louie Creek units, yielded apparent ages ranging from approximately 30 to approximately 14 ka BP, suggesting that conditions were sufficiently wet during the period immediately preceding and throughout the Last Glacial Maximum for tufa deposition to occur. However, ancient tufa formation occurred during a phase of net river aggradation. There is geomorphic evidence that such aggradation was a result of an increased sediment supply to the fluvial system, most likely in response to conditions drier than present. Results from studies elsewhere in the region support such a Late Pleistocene trend. Incision of Louie Creek, which postdates the youngest of the dated ancient tufas, is most likely to have resulted from a shift to wetter conditions during the early Holocene

SEDIMENT-HOSTED GOLD MINERALIZATION IN THE RATATOTOK DISTRICT, NORTH SULAWESI, INDONESIA, 1994, Turner S. J. , Flindell P. A. , Hendri D. , Hardjana I. , Lauricella P. F. , Lindsay R. P. , Marpaung B. , White G. P. ,
The Ratatotok district in the Minahasa Regency of North Sulawesi, Indonesia is an area of significant gold mineralisation. Gold has been mined in the district since at least the 1850s, and intensively by the Dutch between 1900 and 1921 with a recorded production of 5,060 kg of gold. Newmont began exploring the district in 1986, and has delineated a major sediment-hosted replacement-style deposit at Mesel, and other smaller deposits in an 8 X 5 km area. A total drill-indicated resource of over 60 metric tonnes of gold ( 2 Moz) is reported for Mesel, and three of the smaller deposits. Approximately 80% of this resource is refractory. Silver grades are usually low (< 10 g/t). The Mesel deposit is similar to many Carlin-type deposits in carbonate hostrocks, alteration, geochemical signature and ore mineralogy, but is distinct in tectonic setting. The discovery of replacement-style mineralisation at Mesel, in an impure limestone within a Tertiary island arc environment, demonstrates that deposits with outward characteristics similar to Carlin-type mineralisation are not restricted to a continental setting. Carbonate sediments in the Ratatotok district were deposited in a Late Miocene restricted basin. Later compressional tectonics caused uplift that resulted in karst development in the limestone and erosion of the adjacent volcanic arc with deposition of a thick epiclastic unit. This was followed by intrusion of shallow level pre-mineral andesite into the sequence. Mineralisation at Mesel, and probably elsewhere in the district, is synchronous with the late-stage reactivation of strike-slip faults. Mineralising fluids at Mesel were focussed along steep structures sympathetic to these faults, and trapped below a relatively impermeable andesite cap rock. Hydrothermal fluids caused decalcification of the silty, more permeable carbonate units with the formation of secondary dolomite, deposition of fine arsenian pyrite, silica veinlets and gold. Volume loss due to decalcification and dolomite formation caused collapse brecciation which enhanced fluid flow and further mineralisation. This locally culminated in total decarbonation and deposition of massive silica. Late-stage stibnite occurs in structural zones within the ore deposit, whereas arsenic (as realgar and orpiment) and mercury (as cinnabar) are concentrated on the periphery. Elsewhere in the Ratatotok district, gold mineralisation is restricted to replacement-style mineralisation in permeable zones along limestone-andesite contacts, open-space-filling quartz-calcite veins and stockworks, and residual quartz-clay breccias. The residual breccias are developed in-situ, and are interpreted to form by dissolution of the wallrock limestone from around pre-existing mineralisation. This has resulted in widespread eluvial gold occurrences

HIGH-RESOLUTION SEISMIC EXPRESSION OF KARST EVOLUTION WITHIN THE UPPER FLORIDIAN AQUIFER SYSTEM - CROOKED LAKE, POLK COUNTY, FLORIDA, 1994, Evans Mw, Snyder Sw, Hine Ac,
We collected 43 km of high resolution seismic reflection profiles from a 14.5-hectare lake in the central Florida sinkhole district and data from three adjacent boreholes to determine the relationship between falling lake levels and the underlying karst stratigraphy. The lake is separated from karstified Paleogene to early Neogene carbonates by 65-80 m of siliciclastic sands and clays. The carbonate and clastic strata include three aquifer systems separated by clay-confining units: a surficial aquifer system (fine to medium quartz sand in the upper 20-30 m), the 25-35 m thick intermediate aquifer system (in Neogene siliciclastics), and the highly permeable upper Floridan aquifer system in Paleogene to early Neogene limestones. Hydraulic connection between these aquifer systems is indicated by superjacent karst structures throughout the section. Collapse zones of up to 1000 m in diameter and > 50 m depth extend downward from a prominent Middle Miocene unconformity into Oligocene and Upper Eocene limestones. Smaller sinkholes (30-100 m diameter, 10-25 m depth) are present in Middle to Late Neogene clays, sands, and carbonates and extend downward to or below the Middle Miocene unconformity. Filled and open shafts (30-40 m diameter; 10-25 m depth) ring the lake margin and overlie subsurface karst features. The large collapse zones are localized along a northeast-southwest line in the northern ponds and disrupt or deform Neogene to Quaternary strata and at least 50 m of the underlying Paleogene carbonate rocks. The timing and vertical distribution of karst structures are used to formulate a four-stage model that emphasizes stratigraphic and hydrogeologic co-evolution. (1) Fracture-selective shallow karst features formed on Paleogene/early Neogene carbonates. (2) Widespread karstification was limited by deposition of Middle Miocene clays, but vertical karst propagation continued and was focused because of the topographic effects of antecedent karst. (3) Groundwater heads, increase with the deposition of thick sequences of clastics over the semipermeable clays during Middle and Late Neogene time. The higher water table and groundwater heads allowed the accumulation of acidic, organic-rich soils and chemically aggressive waters that percolated down to Paleogene carbonates via localized karst features. (4) After sufficient subsurface dissolution, the Paleogene carbonates collapsed, causing disruption and deformation of overlying strata. The seismic profiles document an episodic, vertically progressive karst that allows localized vertical leakage through the clay-confining units. The spatial and temporal karst distribution is a result of deposition of sediments with different permeabilities during high sea levels and enhanced karst dissolution during low sea levels. Recent decreases in the potentiometric elevation of the Floridan Aquifer System simulates a sea-level lowstand, suggesting that karst dissolution will increase in frequency and magnitude

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