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 buried karst is karst topography entirely buried by relatively younger post-rock or sediments and not part of the contemporary landscape [17]. synonyms: fossil karst; (french.) karst couvert, karst fossile, paleokarst; (german.) bedeckter karst, urkarst; (greek.) kaymeno paleokarst; (italian.) carso sepolto; (spanish.) karst soterrado; (turkish.) gomulu karst; (yugoslavian.) pokriveni krs see also covered karst; paleokarst; subsoil karst.?

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 middle ordovician (Keyword) returned 12 results for the whole karstbase:
Scalloped and planar erosion surfaces, Middle Ordovician limestones, Virginia; analogues of Holocene exposed karst or tidal rock platforms, 1977, Read J. F. , Grover G. A. ,

LATE-STAGE DOLOMITIZATION OF THE LOWER ORDOVICIAN ELLENBURGER GROUP, WEST TEXAS, 1991, Kupecz J. A. , Land L. S. ,
Petrography of the Lower Ordovician Ellenburger Group, both in deeply-buried subsurface cores and in outcrops which have never been deeply buried, documents five generations of dolomite, three generations of microquartz chert, and one generation of megaquartz. Regional periods of karstification serve to subdivide the dolomite into 'early-stage', which predates pre-Middle Ordovician karstification, and 'late-stage', which postdates pre-Middle Ordovician karstification and predates pre-Permian karstification. Approximately 10% of the dolomite in the Ellenburger Group is 'late-stage'. The earliest generation of late-stage dolomite, Dolomite-L1, is interpreted as a precursor to regional Dolomite-L2. L1 has been replaced by L2 and has similar trace element, O, C, and Sr isotopic signatures, and similar cathodoluminescence and backscattered electron images. It is possible to differentiate L1 from L2 only where cross-cutting relationships with chert are observed. Replacement Dolomite-L2 is associated with the grainstone, subarkose, and mixed carbonate-siliciclastic facies, and with karst breccias. The distribution of L2 is related to porosity and permeability which focused the flow of reactive fluids within the Ellenburger. Fluid inclusion data from megaquartz, interpreted to be cogenetic with Dolomite-L2, yield a mean temperature of homogenization of 85 6-degrees-C. On the basis of temperature/delta-O-18-water plots, temperatures of dolomitization ranged from approximately 60 to 110-degrees-C. Given estimates of maximum burial of the Ellenburger Group, these temperatures cannot be due to burial alone and are interpreted to be the result of migration of hot fluids into the area. A contour map of delta-O-18 from replacement Dolomite-L2 suggests a regional trend consistent with derivation of fluids from the Ouachita Orogenic Belt. The timing and direction of fluid migration associated with the Ouachita Orogeny are consistent with the timing and distribution of late-stage dolomite. Post-dating Dolomite-L2 are two generations of dolomite cement (C1 and C2) that are most abundant in karst breccias and are also associated with fractures, subarkoses and grainstones. Sr-87/Sr-86 data from L2, C1, and C2 suggest rock-buffering relative to Sr within Dolomite-L2 (and a retention of a Lower Ordovician seawater signature), while cements C1 and C2 became increasingly radiogenic. It is hypothesized that reactive fluids were Pennsylvanian pore fluids derived from basinal siliciclastics. The precipitating fluid evolved relative to Sr-87/Sr-86 from an initial Pennsylvanian seawater signature to radiogenic values; this evolution is due to increasing temperature and a concomitant evolution in pore-water geochemistry in the dominantly siliciclastic Pennsylvanian section. A possible source of Mg for late-stage dolomite is interpreted to be from the dissolution of early-stage dolomite by reactive basinal fluids

RELATION OF MINERALIZATION TO WALL-ROCK ALTERATION AND BRECCIATION, MASCOT JEFFERSON-CITY MISSISSIPPI-VALLEY-TYPE DISTRICT, TENNESSEE, 1994, Haynes F. M. , Keslr S. E. ,
This study was undertaken to assess the relation of Mississippi Valley-type mineralization to wall-rock alteration and brecciation in the Mascot-Jefferson City district, the largest part of the East Tennessee Mississippi Valley-type ore field. The main question of interest was whether the Mississippi Valley-type-forming brines created or greatly enlarged the breccia system that hosts the ore or whether the breccia system was a preexisting paleoaquifer that simply controlled movement of the mineralizing brines. A secondary, and closely related, question was whether brine-wall rock interaction deposited Mississippi Valley-type ore. The breccia system that hosts the East Tennessee ore field began as karst breccias which formed in the upper part of the Late Cambrian-Early Ordovician Knox Group during Middle Ordovician emergence. Brecciation, which was most common at the paleosurface and in a limestone-rich zone about 200 m below the surface, took place when limestone solution caused collapse of primary dolostone layers. Mississippi Valley-type mineralization, consisting of sphalerite and sparry dolomite, fills interstices in the breccias that formed in the limestone-rich part of the Knox Group. Ore is associated with ''recrystalline dolomite'' that replaced limestone and there is an inverse correlation between the original limestone and sphalerite abundance suggesting that the ore-forming fluids reacted strongly with limestone wall rock, possibly dissolving it where alteration was most intense. The assessment of a relation between alteration and Mississippi Valley-type mineralization was based on 3,533 surface drill holes covering the 110-km2 Mascot-Jefferson City district, each of which provided stratigraphic data and quantified estimates of mineralization intensity and alteration intensity. These data show clearly that as much as 50 percent of the limestone in the mineralized breccia section was lost over enormous areas that extend far beyond significant mineralization. The intensity of this effect clearly decreases downdip (toward the east), away from the probable source of meteoric karst-forming waters. These relations, combined with isotopic analyses and reaction path calculations, suggest that breccia formation and limestone dissolution took place during the original karst breccia formation. In contrast, later Mississippi Valley-type mineralization was associated with replacement of limestone by recrystalline dolomite. The main effect of dolomitization on the chemistry of the Mississippi Valley-type brines, an increase in their Ca/Mg ratio, would not cause sulfide precipitation. Thus, it appears unlikely that Mississippi Valley-type-forming brines created much of their ore-hosting breccias or that water-rock interaction was a major cause of Mississippi Valley-type ore deposition

Two Ordovician unconformities in North China: Their origins and relationships to regional carbonate-reservoir characteristics, 1997, Liu B. , Wang Y. H. , Qian X. L. ,
The two unconformities developed on the tops of the Lower Ordovician Liangjiashan Formation (UF1) and the Middle Ordovician Majiagou- or Fengfeng Formation (UF2) are essential boundaries that controlled the formation and distribution of the Lower Paleozoic karst-related reservoirs. UF1 and UF2 have been interpreted as representing short-and long-terms of tectonic uplift, respectively, but new evidence led us to conclude that they were created by different original mechanisms and therefore the related reservoirs should be predicted in different ways. UF1 was commonly interpreted as the result of southern upwarping of the basement, but sequence-stratigraphic analysis supports its origin by eustatic sea-level changes. Spatially, the most favorable regional reservoirs controlled by UF1 should be located in the central area of North China, where the carbonate sediments experienced intensive shallow-subsurface dolomitization with following meteoric water leaching. UF2 was created by tectonic event which resulted in an intra-plate downward flexure and subsequent peripheral bulge. In the depression belt of central North China the younger strata (Fengfeng Fm) were protected, but along the bulge meteoric water eroded them. As a result, the potential regional reservoirs related to UF2 are likely to be distributed along the peripheral-uplift belts, especially around the remnant of the Fengfeng Formation. Based on the analysis of these two unconformities, the Early Paleozoic tectono-sedimentary evolution of North China Plate can be largely divided into four stages: (1) the Cambrian Period, characterized by eustatic sea-level rise and tectonic subsidence; (2) early stage of the Early Ordovician, characterized by eustatic-sea-level fall exceeding tectonic subsidence and development of UF1; (3) from the late stage of the Early Ordovician to the Middle Ordovician, featured by eustatic-sea-level rise and slow tectonic subsidence;(4) from the late stage of the Middle Ordovician to the Early Carboniferous, distinguished by vigorous tectonic uplift and development of UF2

Study on the contamination of fracture-karst water in Boshan District, China, 1997, Zhu X. Y. , Xu S. H. , Zhu J. J. , Zhou N. Q. , Wu C. Y. ,
Boshan is an industrial city in the center of Shandong Province where ground water is the only source for the urban water supply. The major water resource is fracture-karst water in the middle Ordovician carbonate rocks. Based on the hydrogeological investigation and mapping in this area we studied the geologic and hydrogeologic settings, the major pollution sources and the pathways of contamination, the principal contaminants, and their spatial distribution in ground water. The ground-water quality has also been estimated by the fuzzy mathematic method. The geostatistical method, such as the kriging method, was taken to simulate spatial distribution of the contaminants. The grey system method was adopted to forecast future contamination. An attempt at the remediation of Cr6 contamination in fracture-karst water was also discussed. Finally, some proposals for the protection of the ground-water environment in Boshan District are offered

Karst in Enclosing Rocks of Kimberlite Diatremes on the Siberian Platform , 1998, Filippov, Andrej G.

Karst is widely developed in enclosing carbonate rocks of kimberlite diatremes in Yakutia. The Lower Silurian, and Lower and Middle Ordovician marine carbonate and carbonate-terrigenous rocks were exposed to karstification. The age of the forms is Middle and Upper Carboniferous, Cretaceous-Paleogene, Neogene-Quaternary and Quaternary. Karst forms are found on different elements of macro-relief, such as the top part of high plateaux armoured by traps, high plateau slopes, low carbonate plateaux. With respect to elements of meso-relief, karst has developed in watersheds, valley slopes, and under the bottoms of valleys.


Dolomitization and Dolomite Neomorphism: Trenton and Black River Limestones (Middle Ordovician) Northern Indiana, U.S.A, 2000, Yoo Chan Min, Gregg Jay M. , Shelton Kevin L. ,
The Trenton and Black River Limestones are dolomitized extensively along the axis of the Kankakee Arch in Indiana, with the proportion of dolomite decreasing to the south and southeast of the arch. Planar and nonplanar dolomite replacement textures and rhombic (type 1) and saddle (type 2) void-filling dolomite cements are present. Three stages of dolomitization, involving different fluids, are inferred on the basis of petrographic and geochemical characteristics of the dolomites. Nonferroan planar dolomite has relatively high {delta}18O values (-1.8 to -6.1{per thousand} PDB) and has 87Sr/86Sr ratios (0.70833 to 0.70856) that overlap those of Middle Ordovician seawater. Petrography, geochemistry, and the geometry of the dolomitized body suggest that the planar dolomite was formed in Middle and Late Ordovician seawater during the deposition of the overlying Maquoketa Shale. Ferroan planar and nonplanar dolomite occurs in the upper few meters of the Trenton Limestone, confined to areas underlain by planar dolomite. This dolomite contains patches of nonferroan dolomite with cathodoluminescence (CL) characteristics similar to underlying planar dolomite. Ferroan dolomite has relatively low {delta}18O values (-5.1 to -7.3{per thousand} PDB) and has slightly radiogenic 87Sr/86Sr ratios (0.70915 to 0.70969) similar to those obtained for the overlying Maquoketa Shale. These data indicate that ferroan dolomite formed by neomorphism of nonferroan planar dolomite as fluids were expelled from the overlying Maquoketa Shale during burial. The absence of ferroan dolomite at the Trenton-Maquoketa contact, in areas where the earlier-formed nonferroan planar dolomite also is absent, indicates that the fluid expelled from the overlying shale did not contain enough Mg2 to dolomitize limestone. Type 1 dolomite cement has isotopic compositions similar to those of the ferroan dolomite, suggesting that it also formed from shale-derived burial fluids. CL growth zoning patterns in these cements suggest that diagenetic fluids moved stratigraphically downward and toward the southeast along the axis of the Kankakee Arch. Type 2 saddle dolomite cements precipitated late; their low {delta}18O values (-6.0 to -7.0{per thousand} PDB) are similar to those of the type 1 dolomite cement. However, fluid-inclusion data indicate that the saddle dolomite was precipitated from more saline, basinal fluids and at higher temperatures (94{degrees} to 143{degrees}C) than the type 1 cements (80{degrees} to 104{degrees}C). A trend of decreasing fluid-inclusion homogenization temperatures and salinities from the Michigan Basin to the axis of Kankakee Arch suggests that these fluids emerged from the Michigan Basin after precipitation of type 1 cement

The reconstruction of fossil planation surface in China, 2002, Feng Jl, Cui Zj,
On the basis of results of relative subjects, the fossil planation surface has been discussed by the authors from the point of geomorphologic view. The discussion contents included the characteristic information, research methods, paleotopography (gradient and altitude) and other problems about fossil planation surface. The recognition and reconstruction of fossil planation surface mainly rely on the following characteristic information: ( i) the character of erosion unconformity surface; (ii) the paleo-weathering crust and residual deposits; (iii) the paleo-karst and filled deposit in the paleo-karst under the unconformity surface, and (iv) the character and environment of sediment above the unconformity surface. According to the above-mentioned characteristic information, the authors recognized and reconstructed two stages of fossil planation surface on Paleo-land of North China and Yangtze Paleo-land. These two fossil planation surfaces formed from Middle Ordovician to Lower Carboniferous and from Lower Permian to Upper Permian respectively. The paleo-gradient of fossil planation surface changed within 0.31parts per thousand-1.32parts per thousand, mostly less than 1.0parts per thousand. According to the developing depth of paleo-karst, the authors considered that in Suqiao buried-hill region of Paleo-land of North China, the paleo-altitude is 300 m or so above paleo-sea-level. The authors hope that the research is in favor of discussion about rising scale and process of the Tibetan Plateau. Besides, the research of fossil planation surface can provide a theoretical base for relative research, such as the reconstruction of paleoenvironment, the evolution and drift of paleo-continent, the formation and distribution of weathering ore deposits, the reservior and prospection of oil and gas, etc

Fallen arches: Dispelling myths concerning Cambrian and Ordovician paleogeography of the Rocky Mountain region, 2003, Myrow Paul M. , Taylor John F. , Miller James F. , Ethington Raymond L. , Ripperdan Robert L. , Allen Joseph,
High-resolution sedimentologic, biostratigraphic, and stable isotope data from numerous measured sections across Colorado reveal a complex architecture for lower Paleozoic strata in the central Cordilleran region. A lack of precise age control in previous studies had resulted in misidentification and miscorrelation of units between separate ranges. Corrections of these errors made possible by our improved data set indicate the following depositional history. The quartz-rich sandstone of the Sawatch Formation was deposited during onlap of the Precambrian erosion surface in the early Late Cambrian. The overlying Dotsero Formation, a regionally extensive carbonate- and shale-rich succession records blanket-like deposition with only minor facies changes across the state. An extremely widespread, meter-scale stromatolite bed, the Clinetop Bed, caps the Dotsero Formation in most areas. However, a latest Cambrian erosional episode removed 9-11 m of the upper Dotsero Formation, including the Clinetop Bed, from just east of the Homestake shear zone in the Sawatch Range eastward to the Mosquito Range. The overlying Manitou Formation differs in character, and thus in member stratigraphy, on the east vs. west sides of the state. These differences were previously interpreted as the result of deposition on either side of a basement high that existed within the Central Colorado Embayment or Colorado 'Sag,' a region of major breaching across the Transcontinental Arch. This paleogeographic reconstruction is shown herein to be an artifact of miscorrelation. Biostratigraphic data show that the northwestern members of the Manitou Formation are older than the members exposed in the southeastern part of the state and that there is little or no overlap in age between the two areas. This circumstance is the result of (1) removal of older Manitou Formation strata in the southeast by an unconformity developed during the Rossodus manitouensis conodont Zone, and (2) erosion of younger Manitou strata in central and western Colorado along Middle Ordovician and Devonian unconformities. Deciphering these complex stratal geometries has led to invalidation of long-held views on western Laurentian paleogeography during the Cambrian and earliest Ordovician, specifically the existence of the Colorado Sag and a northeast-trending high within the sag that controlled depositional patterns on either side. The mid- Rossodus uplift and resultant unconformity eliminated any and all Upper Cambrian and Lower Ordovician deposits in southern Colorado and northern New Mexico, and thus their absence should not be misconstrued as evidence for earlier nondeposition in this region. Lithofacies distribution patterns and isopach maps provide no evidence that highlands of the Transcontinental Arch existed in Colorado prior to the mid-Rossodus age uplift event. In fact, regional reconstructions of earliest Paleozoic paleogeography along the entire length of the purported Transcontinental Arch should be reevaluated with similarly precise biostratigraphic data to reconsider all potential causes for missing strata and to eliminate topographic elements not supported by multiple stratigraphic techniques. This study illustrates how seriously paleogeographic reconstructions can be biased by the presumption that missing strata represent periods of nondeposition rather than subsequent episodes of erosion, particularly in thin cratonic successions where stratigraphic gaps are common and often inconspicuous

Strontium isotope characterization and major ion geochemistry of karst water flow, Shentou, northern China, 2006, Wang Yanxin, Guo Qinghai, Su Chunli, Ma Teng,
SummaryKarst water is the most important source of water supply for Shanxi province, northern China. The Shentou springs are representative of the 19 major karst springs at Shanxi. The total area of the Shentou karst water system is 5316 km2, the Middle Ordovician limestone being its major karst aquifer. In this study, data about the strontium isotope geochemistry and major ion hydrochemistry were analyzed to understand the flow patterns and hydrogeochemical processes of karst water at Shentou. The contour map of TDS value of karst water and that of Sr concentration are similar, showing the general tendency of increase from the northern, western and southern boundary to the discharge area. The average values of 87Sr/86Sr ratios of karst water decrease from recharge (0.7107) to discharge area (0.7102), evolving towards those of limestone hostrocks. Comparison of 87Sr/86Sr ratios with Sr content suggests that isotopic compositions of some karst water samples from the recharge and flow through area should be the result of interaction between aquifer limestone matrix and strontium-poor recharge waters of meteoric origin. However, for samples from the discharge area that are plotted above the mixing line, mixing with groundwater in the Quaternary aquifers with high 87Sr/86Sr ratios may be another factor controlling Sr isotope chemistry. Two major groundwater flow paths were discerned from hydrogeological and geochemical data. Along both flow paths, the 87Sr/86Sr ratios of karst water show a general tendency of decrease. Geochemical modeling of the major ion geochemistry of karst water using PHREEQC also indicates that the chemistry of springs should be affected by the incorporation of groundwater in Quaternary aquifer. The effect of the mixing action on the spring hydrochemistry in flow path 1 is more remarkable than that in flow path 2, according to different mixing ratios in both paths (30% in flow path 1 and 5% in flow path 2)

Paleokarst of the USA: A Brief Review, 2011, Palmer A. N. , Palmer M. V.

Paleokarst consists of solutional features from a prior geomorphic phase that have been preserved by  burial or by a substantial change in local environment. The two major paleokarst horizons in North  America are of Early-Middle Ordovician (post-Sauk) age and Mississippian-Pennsylvanian (post-Kaskaskia) age. There are also several less extensive paleokarst zones. They all differ in detail but  typically include remnants of surface karst features, caves, breccias, hypogenic porosity, and related  mineral suites. In places they provide high-permeability zones significant to water supply, or serve as  hosts to petroleum, ores, and later karst development. Studies of paleokarst give significant evidence for  past geologic and hydrologic conditions, both surficial and deep seated.


PALEOKARST CRUST OF ORDOVICIAN LIMESTONE AND ITS CAPABILITY IN RESISTING WATER INRUSHES IN COAL MINES OF NORTH CHINA, 2013, Mou L. , Li G.

With increase in mining depth of the Carboniferous-Permian coal seams in North China, it is particularly important to study the heterogeneity of karst development in the underlying Middle Ordovician limestone and determine any impermeable strata that may prevent the pressurized karst water from bursting into coal mines. Detailed analysis of the exploratory borehole data suggests presence of a paleokarst crust at the top of Middle Ordovician Fengfeng Formation. Because of its mechanical strength and low permeability to water, the paleokarst crust can function as an additional water-resisting layer. This paper takes Sihe Mine of Shanxi Province as an example to study the geotechnical and hydrogeological characteristics of the paleokarst crust. Incorporation of this additional hydrological barrier led to more minable coal seams in the coalmine.


Results 1 to 12 of 12
You probably didn't submit anything to search for