Attempt to determine the amount and rate of chemical erosion taking place in the limestone valley of Center Co., Pennsylvania, , Ewing A.

A comparison of the rock tablet and water hardness methods for determining chemical erosion rates on karst surfaces, 1983, Crowther J.

Paléokarsts et paléo-géomorphologie néogènes des Alpes occidentales et régions adjacentes, 1984, Julian M. , Nicod J.

NEOGENE PALEOKARSTS AND PALEO-GEOMORPHOLOGY IN THE WESTERN ALPS, JURA AND PROVENCE - This text is an attempt to confront our knowledge about the karsts and the problems of landscape evolution (tectonics, paleo-climates, sea level changes). Three periods had been studied: 1/ Early and Middle Miocene, with the development of chemical erosional surfaces and a prevailing sub-superficial karstic solution; 2/ the revolution of the Upper Miocene ("Rhodanian" tectonical phase and the salinity crisis of the Messinian), that caused the deepening of the karstic systems; 3/ the Plio-Villafranchian phase, favoured the production of terra-rossa and the evolution of the karstic caves, except during some dry periods during the Villafranchian.

Approche théorique _simplifiée de la dissolution karstique, 1994, Gombert, P.

The specific behaviour of karsts makes the estimation of karstic denudation very difficult: discharge and water chemical variabili-ties are in fact major characteristics of aquifer karstic systems and cannot be properly estimated by the way of random sampling. The classical empirical methods provide generally high relative errors due to the bad knowledge of the hydrogeological catchment basin and even of the total number of springs. In the case of CORBEL's or WILLIAM's empirical formulas, average relative error can be estimated to about 100 % for a normally known aquifer karstic system : therefore it is impossible to compare different karsts that have not been studied with the same accuracy. The theoretical statisti-cal relationships between karstic denu-dation and a single climatic parameter (rainfall) are open to criticism: main authors tell that effective rainfall and pedological C02 are essential parame-ters of karstic denudation, which are never taken into account. For example, there are different PULINA's formula for different climatic types indicating that it is necessary to use another climatic parameter different from rain-fall! Moreover this way of modelling the data restrains the statistical repre-sentativity of each formula and intro-duces a difficult choice for karsts, which are at the border of two climatic types (or with mountainous parts). Another problem is the case of polar countries karsts where most precipitation is snowy and does not participate in karstic denudation. Therefore a mathematical modelling of carbonate dissolution is shown, based on infiltra-tion rate calculation and knowledge of calco-carbonic equilibrium. Temperature and rainfall are taken into account to determine the efficient part of precipitation, the productivity of pedogenetic C02 and the carbonate solubility constants. This theoretical approach gives the same results but with relative errors under 50 %. Consequently it is easy to compare different karstic countries in the world: hot and wet climates are confirmed to have the main karstogenetic activity but the role of cold countries is rehabilita-ted. Then paleokarstic denudation can be estimated.

Influence of climatic parameters in karstic denudation, 1997, Gombert P. ,

Karstic denudation is empirically estimated by specific dissolution or geochemical balance calculations, which need a precise knowledge of the aquifer, or by mathematical expressions which only depend upon rainfall. It is in fact known that water inflow charged with CO2 is the main karstic agent. We propose a mathematical model called << Maximal Potential Dissolution >> (DMP) and based on efficient infiltration calculation, CO2 soil productivity and knowledge of the calcocarbonic equilibrium

The hydrogeochemistry of the karst aquifer system of the northern Yucatan Peninsula, Mexico, 2002, Perry E. , Velazquezoliman G. , Marin L. ,

Based on groundwater geochemistry, stratigraphy, and surficial and tectonic characteristics, the northern Yucatan Peninsula, Mexico, a possible analog for ancient carbonate platforms, is divided into six hydrogeochemical/physiographic regions: (1) Chicxulub Sedimentary Basin, a Tertiary basin within the Chicxulub impact crater; (2) Cenote Ring, a semicircular region of sinkholes; (3) Pockmarked Terrain, a region of mature karst; (4) Ticul fault zone; (5) Holbox Fracture Zone-Xel-Ha Zone; and (6) Evaporite Region. Regional characteristics result from tectonics, rock type, and patterns of sedimentation, erosion, and rainfall. The Cenote Ring, characterized by high groundwater flow, outlines the Chicxulub Basin. Most groundwater approaches saturation in calcite and dolomite but is undersaturated in gypsum. Important groundwater parameters are: SO4/Cl ratios related to seawater mixing and sulfate dissolution; Sr correlation with SO4, and saturation of Lake Chichancanab water with celestite. indicating celestite as a major source of Sr; high Sr in deep water of cenotes, indicating deep circulation and contact of groundwater with evaporite; and correlation of Ca, Mg, and SO4, probably related to gypsum dissolution and dedolomitization. Based on geochemistry we propose: (1) a fault between Lake Chichancanab and Cenote Azul; (2) deep seaward movement of groundwater near Cenote Azul; and (3) contribution of evaporite dissolution to karst development in the Pockmarked Terrain. Chemical erosion by mixing-zone dissolution is important in formation of Estuario Celestun and other estuaries, but is perhaps inhibited at Lake Bacalar where groundwater dissolves gypsum, is high in Ca, low in CO3, and does not become undersaturated in calcite when mixed with seawater