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Formation of dolomite

History & formation of the Dolomites, UNESCO World Natural

Formation of the Dolomites The Dolomites are about 250 millions years old and are composed mainly of sedimentary rocks and limestone. Today, we can hardly imagine that once the mighty mountains were an enormous coral reef, formed in the primordial ocean called Tethys Except for models invoking formation of dolomite by direct precipitation, a process thought by most geologists to apply to only a small percentage of all dolostones, each model is based on the assumption that the dolomite of dolostones has been formed by conversion of CaCO 3 sediment or sedimentary rocks to dolostone More than 90 percent of dolomite is made up of the mineral dolomite. It was first described scientifically in the 18th century. But who would have thought that the formation of this mineral is.. dolomite formation are areas where the dissolved sulfate concentration is refluced by microbial sulfate reduction, through the mixing of seawater with large amounts of fresh water, or where low-sulfate alkaline lacustrine environments prevail. Even under these conditions, dolomite formation may be inhibited by the concurren Dolomite is found in sedimentary basins worldwide. It is thought to form by the postdepositional alteration of lime mud and limestone by magnesium-rich groundwater. Dolomite and limestone are very similar rocks

dolomite Formation, Structure, Properties, Uses, & Facts

  1. eral composed of calcium magnesium carbonate CaMg (CO 3) 2. It was first described in 1791 as a rock by the French naturalist and geologist Déodat Gratet de Dolomieu
  2. 1.. IntroductionThe formation conditions of incompletely dolomitized carbonates is often ambiguous (Land, 1985, Morrow, 1990a, Tucker and Wright, 1990, Purser et al., 1994).Examples are known where limestones contain dolomitic mottles (Mountjoy and Halim-Dihardja, 1991) or dolomitic veins and there is a visible segregation of calcite and dolomite within a sample
  3. Dolomite rocks are originally deposited as calcite or aragonite rich limestone, but during diagenesis process, the calcite or aragonite is transformed into dolomite. Chert forms when microcrystals of silicon dioxide grow within soft sediments that become limestone or chalk. The chert formation can be either of chemical or biological origin
Lockport dolostone | Peter Russell Rock Garden

Formation of dolomite Dolomite is formed by the replacement of the calcite ions by the magnesium ions. Depending upon the ratio of the Mg ions in the crystal lattice they have different names (Figure 1). Modern dolomite formation has been found to occur underconditions anaerobic in supersaturated saline lagoons in Brazil Formation of dolomite. Dolomite is formed by the replacement of the calcite ions by the magnesium ions. Depending upon the ratio of the Mg ions in the crystal lattice they have different names . Modern dolomite formation has been found to occur under anaerobic conditions in supersaturated saline lagoons in Brazil As limestone and dolomite shares the same depositional environment as shallow marine, warm water where organism can accumulate which in turn when deposits form carbonate. So in formation of dolomite it is thought to be the alteration of carbonate by magnesium rich water, Magnesium in the water converts calcite into dolomite, This alteration is the chemical change in the limestone which is. Formation of dolomite catalyzed by sulfate-driven anaerobic oxidation of methane: Mineralogical and geochemical evidence from the northern South China Sea Yang Lu, Xiaoming Sun, Huifang Xu, Hiromi Konishi, Zhiyong Lin, Li Xu, Tingting Chen, Xinrong Hao, Hongfeng Lu and Jörn Peckman Findings on synthesis of low-t dolomite have shown that abiotic formation at low temperature is impossible without any heterogeneous surfaces, e.g., seeds 2, 4, 5, 6, 7. This includes biological..

The recently formulated microbial dolomite model provides the opportunity to view the geological history of dolomite formation from a new perspective. A biogeochemical approach to the 'dolomite problem' reveals a plausible connection between Phanerozoic geochemical cycles and dolomite formation The enthalpy of formation of ordered dolomite from calcite and mag' nesite at 85C is -5.74 + 0.25 kJ/mol, for a formula unit of dolomite containing I mol of cations. A synthetically disordered dolomite has an enthalpy of formation of + | .23 ! 0.32 kJlmol. At 85C, four synthetic magnesian calcites with mole fraction, X, of MgCO Fig. 1. Dolomite formation enthalpy as a function of carbon atom displacement from the oxygen atomplane. Positive carbon atom distances indicate that CO32- molecular units form an 'umbrella' that pointstoward Ca21in the crystal. Negative carbon atom distances indicate that the CO32- molecular 'umbrella'points toward Mg21. The bottom of the curve is located at -0.0014 Å, corresponding to -6.4 kJ z mol-1 Main Dolomite (German: Hauptdolomit, Hungarian: Fődolomit, Italian: Dolomia Principale) is a lithostratigraphic unit in the Alps of Europe. Formation was defined by K.W. Gümbel in 1857.. Middle to Late Triassic sedimentary record in the Alpine realm is characterized by presence of various masses of dolomitic rock formations

How does dolomite form? -- ScienceDail

  1. About 280 million years ago, in the area of the western Dolomites, the earth began to crumble. Cracks formed in the hard crust and masses of lava emerged from the deep clefts, giving origin to one of the largest volcanic areas in Europe
  2. eralogy, the supply of methane, and microbial activity. You do not currently have access to this article
  3. Dolomite formation is controlled in part by competition between AMO and methanogenesis, which controls the speciation of dissolved CO 2. AMO increases the concentration of CO 3 2 through sulfate reduction, favoring dolomite formation, while methanogenesis increases the pCO 2 of the pore waters, inhibiting dolomite formation. By regulating the pC
  4. Formation. Dolomite is the main constituent in dolomite rocks and dolomitic marbles. It occurs as a replacement deposit in limestone affected by magnesium-bearing solutions, in talc schists, and in other magnesium-rich metamorphic rocks. Dolomite is found in hydrothermal veins associated with lead, zinc, and copper ores
  5. Replacement dolomite in the Latemar carbonate buildup, northern Italy, formed when limestone was infiltrated by and reacted with Mg-rich fluid. It occurs in discrete bodies in sharp contact with unreacted limestone. The dolomite developed in a nearly orthogonal lattice of vertical columns (replacement of limestone breccia pipes) and sheets (replacement along fractures and limestone-dike.
  6. eral composed of calcium magnesium carbonate, ideally CaMg(CO 3) 2. The term is also used for a sedimentary carbonate rock composed mostly of the
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The Doushantuo Formation of the Yangtze Platform (South China) is a succession of marine carbonate (mainly dolomite), siliciclastic, and phosphatic sedimentary rocks deposited immediately after the global-scale Neoproterozoic Marinoan (or Nantuo in South China) glaciation at paleolatitudes of ∼30 °N (19) (Fig. 1 and SI Appendix, Fig. S1 A) Our T ∆47 record indicates that a majority (87%) of these dolostones formed at temperatures of <100 °C. When considering the regional thermal history, modeling of the influence of solid-state reordering on our T Δ47 record further suggests that most of the studied dolostones formed at temperatures of <60 °C, providing direct evidence of a low-temperature origin of these dolostones Common sites for dolomite formation are areas where the dissolved sulfate concentration is reduced by microbial sulfate reduction, through the mixing of seawater with large amounts of fresh water,..

Increase in supersaturation, Mg +2 /Ca +2 ratio and CO-2 3 on the formation of dolomite at near room temperature are subtle except for temperature.This study suggests that microbial mediation is needed for appreciable amount of primary dolomite formation. On the other hand, reactive-transport models depicting dolomitization (temperature range. On the basis of their mode of formation, dolomites can be broadly di-vided into two groups. Primary dolomite is directly precipitated from so-lution either as sediment or cement, whereas secondary dolomite is formed via replacement of precursor CaCO3 in the presence of Mg21-bearing flu-ids

Dolomite: A sedimentary rock known as dolostone or

The low-temperature formation of dolomite (CaMg(CO. 3) 2) is doubtless one of the most intriguing and longstanding mineralogical problems. In brief, the so-called dolomite problem can be described as follows: dolomite is a very common carbonate mineral, which at present does not form under the conditions inferred from most geochem-ical data The formation of the Dolomites. Approximately 285 million years ago, the area that is now Val di Fassa was submerged beneath an expanse of warm, shallow sea.The genesis of the mountain chain that surrounds this area began thanks to the accumulation of shells, sponges, seaweed, mussels, coral and limestone that were gradually transformed into rock

The Middle Triassic carbonates of the Villány Mountains were deposited on a homoclinal carbonate ramp. Many of the carbonates from the 700 m-thick sequence show partial or complete dolomitization. The present paper describes dolomites that occur in a limestone unit as irregular mottles and as pore- and fracture-filling cements. Replacement-type scattered dolomite rhombs in the mottles having. Introduction. Dolomite [CaMg(CO 3) 2] is common in ancient sedimentary rocks of marine origin and is generally thought to have formed through diagenetic processes involving high temperature and pressure or through post-depositional replacement of calcite or aragonite (CaCO 3) (Rosenberg and Holland, 1964; Rosenberg et al., 1967; Hardie, 1987).The crystal structure of dolomite differs from that. 1 1 Reaction pathways towards the formation of dolomite CARLOS M. PINA 2 ∗ 3 Departamento de Cristalografía y Mineralogía, Facultad de Ciencias Geológicas, Universidad 4 Complutense de Madrid, Instituto de Geociencias IGEO (UCM - CSIC), E-28040 Madrid, Spain. 5 6 Abstract: Little is known about the physico-chemical processes that lead to th

However, modern dolomites are rare in earth surface environment and the processes governing dolomite formation are an actively debated topic of current research. Herein, we show for the first time how high-temperature dolomite can precipitate directly from subaqueous cooling layers of vented hydrothermal fluids within sufficient time dolomites from the Yudongzi outcrop in the Feixianguan Formation, in order to constrain the most likely origin of the dolomite, and therefore promote further exploration efforts in high-quality reservoirs. 2. Geological Setting The Yudongzi outcrop is located at the southern boundary of the Tianjingshan anticline at 'sabkha dolomite') dolomite formation is the Peru continental margin, where dolomite was first recovered by deep-sea dredging during the Nazca Plate Project (Kulm et al., 1981, 1984) and during the Ocean Drilling Programme (ODP) Leg 112 (Suess et al., 1988). Different dolomite assem-blages with variable d13C values ranging from )1 Formation of the Earth, dolomite and early life The Earth was born in a ball of fire in the bright, hot, early solar system, about 4.6-billion years ago. As the Earth cooled, a primary broth formed over the thin crust to create the first oceans, and gases exhaled from within - mainly water vapour and carbon dioxide - formed the first. The formation of talc from dolomite and silica-rich fluid occurs at low temperatures in the metamorphism of the CaO-MgO-SiO 2 -CO 2 -H 2 O system and plays important roles in the formation of economically viable talc deposits, the modification of dolomite reservoirs, and other geological processes. However, disagreement remains over the.

The Khor Al-Adaid sabkha in Qatar is among the rare extreme environments on Earth where it is possible to study the formation of dolomite-a carbonate mineral whose origin remains unclear and has been hypothetically linked to microbial activity. By combining geochemical measurements with microbiologi The experimental replacement of calcite and aragonite by dolomite under a variety of conditions indicates that dolomitization can take place in marine and lacustrine environments under two conditions: (i) low dissolved sulfate concentrations and (ii) insubstantial contemporaneous silica diagenesis. Common sites for dolomite formation are areas where the dissolved sulfate concentration is. So the name Dolomite became soon established, and in 1794 Richard Kirman introduced the Dolomite as a new mineral; the name from there became used to name the dolostone rocks and finally gave the Dolomites their actual name. In the 19th century the genesis of both the Dolomite Mountains as the rock forming them became a major problem in geology Neoproterozoic marine dolomite cements represent reliable, albeit complex, archives of their palaeoenvironment. Petrological and high‐resolution geochemical data from well‐preserved fibrous dolomite and pyrite in the upper Ediacaran (ca 551·1 to 548·0 Ma) Dengying Formation in south‐west China are presented and discussed here.The aim of this research is to reconstruct the redox state.

The dolomite does not appear to be preferentially located in the portion of the cores in which sulfate is absent. Based on the association between the abundance of high-Mg calcite (HMC) and dolomite, it is thought that dolomites formed in response to the dissolution of HMC. INTRODUCTION The formation of dolomite in continental organic-rich. @article{osti_5386129, title = {Formation of diagenetic dolomite in coastal sabkha along Arabian (Persian) Gulf}, author = {Patterson, R J and Kinsman, D J.J.}, abstractNote = {Aragonitic intertidal sediments are being dolomitized in the subsurface supratidal environment of a sabkha along the south shore of the Arabian (Persian) Gulf as a result of the percolation of wind-driven marine-derived. New thermodynamic data are presented for the Gibbs energy of formation of dolomite (CaMg(CO3)2(s)). Using electrochemical cells, we find DGf ° (CaMg(CO3)2(s))) equal to -2147.82 kJ z mol -1 . The performance of lattice energy calculations on dolomite, calcite, and magnesite yields a theoretical value of -2148.90 kJ z mol -1 for DGf ° (CaMg(CO3)2(s))) The dolomite in the Yuntai Mountain, Shibing, Guizhou, China constitutes the gentle stratum, affected by several weathering processes. It is coupled with a vertical joint development, which makes it easy to form the collapse and stone peaks corroded by running water. The aim of this paper is to study the effects of weathering processes of dolomite outcropping in the Yuntai Mountain (Shibing.

Video: New Insights into Formation of Mineral Dolomite Geology

Formation of dolomite mottling in Middle Triassic ramp

Significance Massive Paleozoic and Precambrian dolostone successions have long puzzled geologists in light of the kinetic barriers that inhibit low-temperature dolomite nucleation and precipitation (i.e., the dolomite problem). Significantly, the widely accepted hypothesis that such massive dolomites are the product of burial-hydrothermal dolomitization challenges their validity as. Recently, the formation of forsterite during contact metamorphism of dolomite has emerged as a kind of 'standard' in the study of reactions for two reasons. First, mineral reactants and products have simple chemical compositions, very limited chemical variability, and well-defined thermodynamic properties Cells in the post-log phase were harvested and used to mediate the formation of dolomite in solutions with various sulfate concentrations of 0, 3, 29.8, and 100 mM and salinities of 140, 200, and 280‰. X-ray diffraction (XRD) spectra showed that proto-dolomite, monohydrocalcite, and aragonite formed in samples with cells, yet only aragonite. Introduction. Dolomite is a type of carbonate mineral that mainly consists of Mg 2+, Ca 2+, and CO 3 2-.Due to its high abundance on Earth and well-known significance in oil and gas reservoirs (Zengler et al., 1980; Warren, 2000; Gregg et al., 2015), much attention has been paid to the formation mechanisms of dolomite and the related controlling environmental factors dolomite may have formed directly from water with an evaporitic signature under burial conditions; this interpretation assumes that the original isotopic values of dolomite were not modified during late diagenesis. Keywords: Bakken Formation, Williston Basin, dolomitization, stable isotopes, fluid inclusions

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Drummond Dolomite. Drummond Island is part of what geologist call the Engadine corona, which is a vast formation of dolomite originating on the eastern tip of Great Manitoulin Island and extending westward in a great arc to the vicinity of Manistique in Michigan's Upper Peninsula. Dolomite, the underlying rock of Drummond Island, is calcium. The Leg 133 sites differ from other anoxic hemipelagic areas in which extensive sulfate reduction and methanogenesis have been documented in that the sediments are dominated by CaCO 3.Recrystallization of calcium carbonate apparently buffers the isotopic composition of the system, masking large isotopic changes that might be induced by additions of isotopically light or heavy CO 2 derived from.

Formation of Dolomite and Chert - Compare Natur

The Culebra Dolomite Member of the Rustler Formation, a thin (10 m) fractured dolomite aquifer, lies approximately 450 m above the repository horizon of the Waste Isolation Pilot Plant (WIPP) in southeastern New Mexico, USA. Salinities of water in the Culebra range roughly from 10,000 to 200,000 mg/L within the WIPP site The mineral dolomite and the uncertainties surrounding its origin have attracted the attention of earth scientists for over a century. The core of the dolomite problem is the apparent paradox posed by the paucity of dolomite in modern marine depositional environments versus its relative abundance in the sedimentary rock record. Solving this problem requires knowledge of the conditions under.

Dolomite and dolomitization model- a short review

Fingerprint Dive into the research topics of 'Enthalpies of formation of dolomite and of magnesian calcites.'. Together they form a unique fingerprint. calcium magnesium carbonate Chemical Compound The Lockport Group in western NY consists of (ascending) the Gasport Dolomite, Goat Island Dolomite, Eramosa Dolomite, and Guelph Dolomite whose contacts are revised herein. The group is about 160 to 175 feet thick and consists of massive to medium-bedded, argillaceous dolomite with minor amounts of dolomitic limestone and shale Dolomite is abundant in ancient sedimentary sequences and constitutes economically important oil and gas reservoirs. However, because it is virtually impossible to form abiotically at Earth's surface conditions, its mechanism of formation remains unclear and debated Dolomite (MgCa(CO. 3) 2) is an important petroleum reservoir rock mineral common in ancient sedimentary rocks which is infrequently found in modern environments. The mechanism of dolomite formation remains poorly understood, although recent research has focused on the contribution of microbial processes. Sabkha is the Arabic term fo The decomposition of dolomite into CaO and MgO was performed at 1073 K in vacuum and at 1273 K in an Ar atmosphere. The dolomite calcined in vacuum was found to have a higher specific surface area and a higher micropore volume when compared to the dolomite calcined in the Ar atmosphere. These pyrolysis products of dolomite were reacted with CO<sub>2</sub> at 673 K for 21.6 ks

calcite | mineral | Britannica

Dolomite formation is controlled in part by competition between AMO and methanogenesis, which controls the speciation of dissolved CO2. AMO increases the concentration of CO3[2-] through sulfate reduction, favoring dolomite formation, while methanogenesis increases the pCO2 of the pore waters, inhibiting dolomite formation The process of red soils formation from these dolomites can be split into two stages: dolomitic rock to yellowish brown soil and yellowish-brown soil to red soil above . The weathering of dolostone into yellowish brown soil is accompanied by a significant loss of carbonates (MgO and CaO) against a concentration of SiO 2 , Fe 2 O 3 , Al 2 O 3. The Lockport Formation is the cap stone of Niagara Falls and forms the upper crest of the upper falls of the Genesee River in Rochester, NY. The Lockport Formation is of the Middle Silurian age (420 million) and is primarily composed of a hard Dolomitic Limestone with lower l... ayers of shale. The rocks formed from marine sediments that were. A journey through the history of how the Dolomites, with their rugged rock faces and gentle alpine meadows, were formed If you take a look at the history of how the Dolomites came to be, you will encounter the differing characteristics of their rock formations - the Sciliar and the Sella group for instance, have a flat-topped formation whereas the Sassolungo and the Three Peaks have a jagged.

The reconstruction of the Dolomites as an ancient atoll landscape seemed so radical, that Mojsisovics was obligated to find a private publisher for his revolutionary work (MOJSISOVIC 1879. The word Dolomite is now a scientific term applied for mineral formation. Not all the rocks of this region are made of dolomite. The Latemar and the Marmolada (the highest peak of the Dolomites - 3343 m) for example are limestones, a slightly different rock with similar origins. When these rocks formed, they were all limestones Conclusions • Dolomite is a major carbonate mineral. • Its formation from secondary origin is common. • Dolomite is generally formed from the replacement of the Ca ions with the Mg ions. • In the ancient dolomite the type of its formation can be of different mechanisms it could not be easily understood The dolomite problem is well recognized as such. Dolomite has been found in soil, coal, rivers, lakes, pearls and even kidney stones of Dalmatian dogs. A diagenetic dolomitization in these examples is not possible. Also chemical experiments show [Wright], that the supposed geological formation mechanism of limestone under current static. Lastly, some dolomites contain an excess of magnesium (Mg) and are called magnesian dolomite or high-magnesium dolomite. The excess magnesium is probably in the form of magnesium carbonate minerals, of which magnesite (MgCO3) is a possible candidate. They plot outside the left margin of the ternary diagram

These effects, together with possible nonstoichiometry of dolomite (i.e., formation of magnesian calcite), make the system with dolomite a highly complicated one. The speciation curves for dolomite are plotted at p C O 2 = 5 and p 0 = 2 and different p s p 1 values; it results that at p s p 1 equal 16.54 and 16.7, the. A correlation between methanogenesis and dolomite formation has been reported; however, the mechanism underlying this association is not fully understood. In this study, we conducted forced carbonate precipitation experiments at room temperature in calcite-seeded Ca/Mg carbonate solutions containing either purified non-living biomass or bound extracellular polymeric substances (EPS) of the.

Opalized fossil plesiosaur vertebra (Australia) | Opalized

Dolomite is a very common mineral, and is known for its saddle-shaped curved crystal aggregates. A unique, isolated Dolomite occurrence in Eugui, Spain has provided colorless transparent crystals that resemble the Iceland Spar variety of Calcite.The occurrence of Kolwezi, in the Congo, has produced some fascinating, cobalt-rich specimens that are a beautiful hot pink color and highly popular The Drakes Formation is composed of dolomite, limestone, mudstone, and shale. Dolomite, dolomitic limestone, and mudstone are most abundant and are commonly composed of silt-sized grains, are sparsely fossiliferous or unfossiliferous, partly laminated, and locally mud cracked and ripple marked. The Bardstown Member, which makes up only a small. The inorganic formation of dolomite alone is too inefficient to explain the importance of dolomitic rocks in the stratigraphic record. However (micro-)organisms can significantly increase the. Dolomites require no exceptional explanation. They form via diagenesis (a sort of chemical rearrangement in the deep subsurface) from calcite, the main ingredient of limestone. Creationism does not explain the origin of dolomite. Limestone could not have formed quickly from massive precipitation, because the formation of calcite releases heat Part of the calcium ions in the crystal lattice are replaced by magnesium ions, leading to the formation of dolomite (CaMg(CO 3) 2). Marble is a metamorphic rock resulting from the recrystallization of limestone under high pressure and temperature. Whether chalk, limestone, dolomite or marble, all carbonate rocks are subject to erosion

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