Primary dolomite is believed to be formed through cyanobacterial calcification, yet the details and mechanisms of this process are not fully understood. In this study, a freshwater filamentous cyanobacterium, Leptolyngbya boryana, was cultured and domesticated in artificial freshwater and brackish solutions with various Mg/Ca ratios.

Dolomite is quarried for building and ornamental stone, road stone, and the production of refractory brick. It is the principal ore of magnesium metal and the source of the magnesium used by the chemical industry. It is also used as flux and in preparing mag. salts. Brazil up to 35 cts. or more @ 100.00 per ct.

Dolomite is a common rock-forming mineral. It is a calcium magnesium carbonate with a chemical composition of CaMg(CO3)2. It is the primary component of the sedimentary rock known as dolostone and the metamorphic rock known as dolomitic marble. Limestone that contains … See more

Dolomite may precipitate out of aqueous solutions ( sandstones with a dolomitic cement) and some dolomitic rocks are so-called primary dolomites. These were formed in …

dissolution and dolomite precipitation, comes out as approximately 0.03 scaled length unit x 0.27 cm/unit = 0.008 cm and the. dolomitization profile (b) yield a velocity of 1.74 x 10 -1 cm/yr ...

Primary dolomite can form due to direct precipitation from saline waters in evaporitic environment, both coastal and continental. However, the vast majority of dolomite forms after deposition due to replacement of calcite and aragonite in the presence of Mg-rich waters. This process, called dolomitization, may occur shortly after deposition ...

There are two main mechanisms by which dolomite can form in the natural environment: (1) "directly from solution" or primary dolomite, and (2) dolomites that …

The "dolomite problem" is a long‐standing puzzle in sedimentology and mineralogy. Previous studies have shown that some dolostones are formed by microbes or in hydrothermal–burial environments. Here, we provide a different case in which an abiotic and Ca‐rich dolomite layer precipitated in Lake Sayram, Central Asia, during the early …

The distribution of primary dolomite in the Great Salt Lake is spatially heterogeneous, with only the carbonate mud in the South Arm and ridge‐site between desiccation cracks in the North Arm ...

Two types of dolomite formation are common, that is, dolomitization, which is the replacement of CaCO 3 by CaMg (CO 3) 2, and dolomite cementation, which is the precipitation of dolomite from aqueous solution in primary or secondary pore spaces. The term dolomitization is also, yet incorrectly, applied to dolomite cementation.

Ancient dolomite formed through both primary precipitation and replacement (dolomitization) of CaCO 3, presumably by Mg-rich fluids. In modern systems, primary dolomite is constrained to hypersaline environments, such as lagoons (e.g., Vasconcelos and McKenzie 1997 ) and sabkha environments (e.g., Wright and Wacey 2005 ), and …

The first model resembles the hydrothermal-influenced dolomite model, in which primary dolomite is formed at high-temperature (up to 250 °C) from hydrothermal fluids during and/or penecontemporaneous with sediment deposition, driven by an abnormally high heat flux associated with local volcanism (Yang et al., 2020, Yang et al., …

direct precipitation of dolomite and Mg-rich smectite clays provides evi-dence that silica may be a key to the dolomite problem, as well as constrain-ing palaeoenvironments such as the Pre-salt Barra Velha Formation. Keywords Authigenic clay, dissolved silica, Mg-rich smectite, primary dolomite, surface-induced nucleation and growth, TEM ...

dolomite, type of limestone, the carbonate fraction of which is dominated by the mineral dolomite, calcium magnesium carbonate [CaMg(CO 3) 2]. General considerations Along …

Primary dolomite formation; non-evaporative environments 49 2022 International Association of Sedimentologists., Sedimentology, 70, 48–77 Warthmann et al., 2000; Hood et al., 2011). Recently, microcrystalline and disordered dolomite, which is a precursor of ancient well-ordered massive dolomite, has been found in modern and Neogene …

Dolomite may be the sole or primary constituent of marble. Dolomarble from Fauske, Norway. Width of sample 14 cm. Dolostone is the most important rock type that is composed mostly of it. Dolostone was probably originally limestone which was altered by Mg-bearing water circulating in the rocks. Dolomite does not precipitate out of aqueous ...

Therefore, dolomite formation needs now to connect with the presence of smectite minerals in the precipitation medium. As revealed from petrographic characters of dolomite with its associated smectite (Fig. 4 a–h), the studied dolomite has been interpreted as a primary precipitate enclosing the previously-precipitated smectitic clay …

Dolomite is a mineral and a rock-forming mineral that is composed of calcium magnesium carbonate (CaMg (CO3)2). It is named after the French mineralogist Déodat Gratet de Dolomieu, who first …

Mineralogically, the mudrock facies is composed of clay minerals (40%), quartz (30%) and dolomite (30%) (Table 1). In thin section, dolomite occurs as. Discussion. In lacustrine/palustrine environments, several processes had been considered to interpret the primary/diagenetic dolomite.

On the basis of the mode of formation, dolomites can broadly be divided into two groups: primary dolomite and secondary dolomite. 2 Primary dolomite precipitate directly from aqueous solution, mostly at or near room temperature (20-35 o C), with no CaCO 3 dissolution involved. 3 However, dolomite can also form as a secondary phase …

To test this hypothesis, the hydrology and mineralogy of Deep Springs Lake, a playa setting with primary dolomite precipitation has been explored. In this study, the central playa sites with the highest sedimentation rates were found to have dissolved silica concentrations close to saturation. Rietveld refinement showed that bulk mineral ...

We propose a new mechanism to explain the formation of high-temperature primary dolomites, combining an understanding of …

The abundant occurrence of primary dolomite in the Deep Springs Lake provides an ideal scenario for understanding sedimentary dolomite formation. Recent laboratory works have shown that the addition of 1 to 2 mM dissolved silica to solutions with high Mg : Ca ratios will promote incorporation of magnesium into the carbonate structure …

Dolomite is a common rock-forming mineral. It is the primary constituent of dolomite rock ( dolostone) and dolomarble. It is similar to the most common carbonate mineral calcite. These two share some similarities in …

Meanwhile, primary dolomite mediated by microbes often contains more Fe2+ than standard dolomite in modern microbial culture experiments. Ferroan dolomite and ankerite have been regarded as ...

Here, we examined early Holocene sediments containing a 12-cm-thick layer that consists of abundant partially ordered dolomite (mean > 50 wt%) collected from Lake Sayram, Central Asia. By combining mineralogical and geochemical evidence, we con-firmed a primary and abiotic origin of this dolomite layer.

Abstract. Dolomite is not a simple mineral; it can form as a primary precipitate, a diagenetic replacement, or as a. hydrothermal metamorphic phase, all that it requires is permeability, a ...

In all of these so-called primary dolomite localities, dolomite apparently forms by almost instantaneous reaction of newly precipitated calcite or aragonite crystals with seawater and/or percolating ground water. The geochemistry of the dolomitizing water is unusual. Salinity is higher than normal seawater (3.5%) and the ratio of dissolved ...

Structural and isotopic characteristics of dolomites and relationships between temperature, salinity, and fluid density. (a) Cross‐plot of dolomite stoichiometry and cation ordering, showing ...

The main exception to this is primary dolomite that forms in evaporitic settings as a relatively late product of seawater evaporation. These primary dolomites are rare though. One of the more unusual primary …

The primary aqueous inclusions in the saddle dolomite cements are characterized by very high salinities, ranging from 17.9 to 25.1 wt% NaCl equivalent (Fig. 5 C), pointing to hypersaline dolomite parent fluids. This implies that the formation of saddle dolomites resulted from a single hot episode, likely related to hydrothermal activity …