Search results for "dolomite"
showing 10 items of 29 documents
Dissolution and precipitation of gypsum and carbonate minerals in soils on evaporite deposits, central Sicily: isotope geochemistry and microfabric a…
1993
Abstract Soil profiles developed from carbonate- and sulphate-rich deposits of the Gessoso-Solfifera Formation (Miocene) were sampled in central Sicily (544 mm annual precipitation and a strongly seasonal rainfall regime). Carbon and oxygen isotope data supported by mineralogical and thin section investigations indicate that meteoric waters and groundwaters dissolve and repricipitate carbonates and gypsum in the soil profiles. The boundary between the C horizon and the overlying one is the formation site of 18O depleted carbonates (calcite and/or dolomite) presumably precipitated from percolating waters during wet periods. Greater δ18O values of carbonates in the shallower horizons suggest …
Coarse-grained cryogenic aragonite as end-member of mineral formation in dolomite caves
2018
Abstract Cryogenic carbonate particles (single crystals and aggregates) have recently been recognized as important witnesses of permafrost dynamics, as they can be used to estimate the thickness and timing of development of permafrost. In this study, the petrography and geochemistry of coarse-grained cryogenic aragonite (CGCAr) identified in Zoolithen Cave in NE Bavaria, Germany, are described in detail for the first time. We provide a sequence of carbonate precipitation during freezing, where CGCAr mark the final crystallization phase in freezing water on ice. Our results support the notion that host rock composition, solution chemistry, and cave ventilation play an important role for arag…
Geochemistry and mineralogy of travertine deposits of the SW flank of Mt. Etna (Italy): Relationships with past volcanic and degassing activity
2007
Abstract Travertine deposits outcropping in the lower SW flank of Mt. Etna were studied for their mapping, as well as for their chemical, mineralogical and isotopic compositions. These deposits are dated to about 24 to 5 ka in the Adrano area, located at the western limit of the study area. In this area travertines show high Mg contents and are composed mostly of dolomite, thus apparently ruling out any primary deposition in favour of a diagenetic origin. Travertines outcropping near Paterno, in the east part of the study area, should be younger than 18 ka. Those located to the SSW of Paterno (Paterno–Diga) show high Sr contents and aragonite as dominant mineralogical phase, thus suggesting…
The origin and timing of multiphase cementation in carbonates: Impact of regional scale geodynamic events on the Middle Jurassic Limestones diagenesi…
2009
The Middle Jurassic carbonates of the eastern part of the Paris Basin display surprisingly low values of porosity and permeability (Φ < 15‰ and K < 0.5 mD). The main objective of this study is to determine the causes and timing of the cementation that altered the petrophysical properties of these carbonates thereby destroying their potential as oil reservoirs; a fate that did not befall their equivalents in deeper, central parts of the Paris Basin. Using petrographic and geochemical analyses (stable O and C isotopes, Sr isotopes, major elements), we identify six calcitic spar stages, two dolomite stages, and several episodes of fracturing and stylolitization ordered in paragenetic sequence.…
Fluid geochemistry in a low-enthalpy geothermal field along a sector of southern Apennines chain (Italy)
2020
Abstract The chemical and isotopic features of the fluids (water and gases) in the Lucane thermal area (southern Italy) have been investigated in order to verify their origin, water temperature in the geothermal reservoir, and to recognize the main natural processes concerning the water composition during ascent towards the surface. The Lucane geothermal system is placed in the southern sector of the Apennines chains, a seismically active area, close to the southern base of the Mt. Alpi carbonate massif. Along the study area, two main sets of high-angle faults form an almost orthogonal fault system that, as suggested by local structural geology, acts as a preferential pathway for uprising d…
Geochemical characteristics of waters in mineralised area of Peloritani Mountains (Sicily, Italy)
2009
Abstract This paper presents the results of a study on the geochemistry of waters circulating in the mineralised area of the south-eastern sector of Mt. Peloritani (north-eastern Sicily, Italy), aimed at basic understanding of the geochemical processes influencing their chemical composition. Chemico-physical parameters and data on 26 major and minor chemical elements are reported for 103 water samples. Water chemistry is mainly dominated by dissolution of carbonates and hydrolysis of aluminosilicate minerals. Total dissolved salts (TDS) range from 80 to 1398 mg/L. All the waters exhibit E H characteristic of an oxygenated environment. Excluding two samples, which show very high H + activity…
Seepage carbonate mounds in Cenozoic sedimentary sequences from the Las Minas Basin, SE Spain
2016
Abstract A number of carbonate mounds composed of indurate, strongly folded and/or brecciated calcite and dolomite beds occur interstratified in Cenozoic sedimentary sequences from the Las Minas Basin. Part of the fabric of the rock forming the carbonate mounds is composed of laminated to banded dolostone similar to the host rock but showing contrasted lithification. Moreover, the carbonate deposits of the mounds display aggrading neomorphism of dolomite, partial replacement of dolomite by calcite, calcite cementation, and extensive silicification, locally resulting in box-work fabric. Eight main lithofacies were distinguished in the carbonate mound deposits. In some lithofacies, chert is p…
Assisted phytostabilization of soil from a former military area with mineral amendments.
2019
Abstract Due to the presence of toxic pollutants, soils in former military areas need remedial actions with environmentally friendly methods. Greenhouse experiments were conducted to investigate the aided phytostabilization of multi-heavy metals (HMs), i.e. Cd, Cr, Cu, Ni, Pb, Zn, in post-military soil by Festuca rubra and three mineral amendments (diatomite, dolomite and halloysite). The amendments were applied at 0 and 3.0% to each pot filled with 5 kg of polluted soil. After seven weeks of the phytostabilization, selected soil properties, biomass yield of F. rubra and immobilization of HMs by their accumulation in plant and redistribution among individual fractions in soil were determine…
Use of Calcined Dolomite as Chemical Precipitant in the Simultaneous Removal of Ammonium and Phosphate from Synthetic Wastewater and from Agricultura…
2019
Phosphorus as phosphate and nitrogen as ammonium or nitrate are the main nutrients in wastewaters and agricultural sludges. They runoff easily to waterways and cause eutrophication in water bodies. However, ammonium and phosphate could be precipitated simultaneously and used as recycled nutrients. In this research, dolomite calcined at 650 °
A geochemical survey of the telese hypothermal spring, southern Italy: Sulfate anomalies induced by crustal deformation
2002
This study deals with a chemical survey (major ions and Li+, F–, Br–, and ) on water samples collected from April 1998 to April 1999, from the Telese thermal spring, southern Italy, in order to investigate possible variations in the chemical composition of the spring. Water samples are of the calcium bicarbonate type, with small fluctuations in outlet temperature (20.05 ± 0.23°C), pH (6.23 ± 0.16), and TDS (2415 ± 35 mg/l). The concentrations of major ions stayed nearly constant, except for . All analyzed waters are saturated or oversaturated relative to calcite and dolomite. The higher saturation indices of the water samples relative to calcite and dolomite observed during the summer of 19…