KarstBase a bibliography database in karst and cave science.
Featured articles from Cave & Karst Science Journals
Characterization of minothems at Libiola (NW Italy): morphological, mineralogical, and geochemical study, Carbone Cristina; Dinelli Enrico; De Waele Jo
Chemistry and Karst, White, William B.
The karst paradigm: changes, trends and perspectives, Klimchouk, Alexander
Long-term erosion rate measurements in gypsum caves of Sorbas (SE Spain) by the Micro-Erosion Meter method, Sanna, Laura; De Waele, Jo; Calaforra, José Maria; Forti, Paolo
The use of damaged speleothems and in situ fault displacement monitoring to characterise active tectonic structures: an example from Zapadni Cave, Czech Republic , Briestensky, Milos; Stemberk, Josef; Rowberry, Matt D.;
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;
Sedimentology, 1997, Vol 44, Issue 2, p. 177-195
Spheroidal dolomites in a Visean karst system - Bacterial induced origin?
Nielsen P. , Swennen R. , Dickson J. A. D. , Fallick A. E. , Keppens E. ,
Abstract:
Spheroidal dolomite crystals occur in the karstified top of a Dinantian dolomite sequence in eastern Belgium. The spheroidal dolomite crystals are best developed at the base of the karst system. The dolomite crystals are characterized by a spherulitic or dumb-bell inclusion pattern, and are overgrown by dolomite cements with a rhombohedral outline. They are considered to be bacterially related precipitates based on, (1) textural similarities with documented bacteriogenic precipitates, (2) the presence of 'bacterial' microspheres and framboidal pyrite embedded within the dolomite, and (3) their general geological setting. The geochemical characteristics of the dolomites and associated minerals support a bacterial origin. The ubiquity of framboidal pyrite, depleted in S-34 (delta(34)S = - 22.4 to - 25.5 parts per thousand CDT), testifies to a period of bacterial sulphate reduction. The isotopic composition of the spheroidal dolomites (delta(13)C = - 2.4 to - 3.2 parts per thousand PDB and delta(18)O = - 3.8 to - 3.4 parts per thousand PDB) suggest a contribution from oxidized organic carbon produced during bacterial sulphate reduction. Sulphate reduction may also result in a concomitant O-18 depletion if the system is nearly closed. It is however, evident from the sulphur isotopic composition of associated framboidal pyrite that the system was fairly open. The O-18 depletion of the spheroidal dolomite crystals (delta(18)O = - 3.8 to - 3.4 parts per thousand PDB) and their occurrence adjacent to, and within karst cavities suggests a mixing zone origin, with a significant proportion of freshwater in it. The rhombohedral cement-overgrowths have calculated delta(18)O values in the range of 0 to 5.3 parts per thousand PDB, which reflect precipitation from normal to slightly evaporated contemporaneous seawater
Spheroidal dolomite crystals occur in the karstified top of a Dinantian dolomite sequence in eastern Belgium. The spheroidal dolomite crystals are best developed at the base of the karst system. The dolomite crystals are characterized by a spherulitic or dumb-bell inclusion pattern, and are overgrown by dolomite cements with a rhombohedral outline. They are considered to be bacterially related precipitates based on, (1) textural similarities with documented bacteriogenic precipitates, (2) the presence of 'bacterial' microspheres and framboidal pyrite embedded within the dolomite, and (3) their general geological setting. The geochemical characteristics of the dolomites and associated minerals support a bacterial origin. The ubiquity of framboidal pyrite, depleted in S-34 (delta(34)S = - 22.4 to - 25.5 parts per thousand CDT), testifies to a period of bacterial sulphate reduction. The isotopic composition of the spheroidal dolomites (delta(13)C = - 2.4 to - 3.2 parts per thousand PDB and delta(18)O = - 3.8 to - 3.4 parts per thousand PDB) suggest a contribution from oxidized organic carbon produced during bacterial sulphate reduction. Sulphate reduction may also result in a concomitant O-18 depletion if the system is nearly closed. It is however, evident from the sulphur isotopic composition of associated framboidal pyrite that the system was fairly open. The O-18 depletion of the spheroidal dolomite crystals (delta(18)O = - 3.8 to - 3.4 parts per thousand PDB) and their occurrence adjacent to, and within karst cavities suggests a mixing zone origin, with a significant proportion of freshwater in it. The rhombohedral cement-overgrowths have calculated delta(18)O values in the range of 0 to 5.3 parts per thousand PDB, which reflect precipitation from normal to slightly evaporated contemporaneous seawater
Keywords: belgium, carbon, cavities, cavity, cements, crystals, depletion, dinantian, dolomite, dolomites, england, isotope, isotopic composition, karst, karst cavities, karst system, microspheres, minerals, mixing, mixing zone, o-18, organic carbon, organic-carbon, origin, part, pattern, precipitation, pyrite, range, reduction, scotland, seawater, sequence, sulphate reduction, sulphur, support, system, time, times, values, visean, zone,