Dolomite (Mineral)
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 ...
Lacustrine dolomite in deep time: What really matters in early dolomite …
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., …
"Microcrystalline Dolomite in a Middle Permian Volcanic …
Lacustrine dolomite nucleation commonly occurs in modern and Neogene evaporitic alkaline lakes. As a result, ancient lacustrine microcrystalline dolomite has been conventionally interpreted to be formed in evaporitic environments. This study, however, suggests a non-evaporitic origin of dolomite precipitated in a volcanic–hydrothermal …
Dolomite and dolomitization: Implications for reservoir
The dolomite cements, generally found in carbonates and clastics, are precipitated directly from pore fluids during diagenesis (Tucker and Wright, 1990; Chen et al., 2019). The dolomite cement can also be primary dolomite cement or the replacement of calcite cement (Adams and Mackenzie, 1998).
Dolomite – Geology is the Way
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 ...
Dolomite and Dolomitization | SpringerLink
Dolomite is a trigonal–rhombohedral, ordered Ca, Mg carbonate mineral (CaMg (CO 3) 2) occurring primarily in sedimentary and metamorphic rocks. …
A New Model for Formation of Lacustrine Primary …
We propose a new mechanism to explain the formation of high-temperature primary dolomites, combining an understanding of …
Co‐precipitation of primary dolomite and Mg‐rich clays in …
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 …
An Early Holocene Primary Dolomite Layer of Abiotic …
Our results demonstrated that these dolomites have obvious cation ordering and euhedral crystals, and their oxygen isotope values are similar to ostracods in the same horizon, suggesting a primary origin. These euhedral and rhombic dolomite grains are consistent with dolomite precipitated slowly in an abiotic way rather than by microbial …
Dolomites and dolomitization | SpringerLink
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.
(PDF) Estimation of dolomite formation: Dolomite …
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 ...
Abiotically-formed, primary dolomite in the mid-Eocene …
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.
(PDF) Microbial primary dolomite from a Norian carbonate …
Microbial primary dolomite 471 2006 The Authors. Journal compilation 2006 International Association of Sedimentologists, Sedimentology, 53, 465–480
Primary dolomite in the Late Triassic Travenanzes
In particular, primary dolomite is hypothesized to have precipitated in the Precambrian (Tucker, 1982), perhaps from aragonite-dolomite seas (Hood et al., 2011;Hood & Wallace, 2012) and in the ...
Minerals | Free Full-Text | Can Primary Ferroan Dolomite …
Microbes can mediate the precipitation of primary dolomite under surface conditions. 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 secondary products. This paper reviews the process …
Dolomite and dolomitization model- a short review
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 …
Dolomite Mineral | Uses and Properties
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
A route for the direct crystallization of dolomite
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 …
Dolomite Rock
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 …
Abiotically-formed, primary dolomite in the mid-Eocene …
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 …
An Early Holocene Primary Dolomite Layer of Abiotic …
We report a case of a primary abiotic lacustrine dolomite layer formed during the early Holocene in Lake Sayram, Central Asia. …
Preservation of primary structures and fabrics in dolomite
Article: Preservation of primary structures and fabrics in dolomite. Abstract Several mechanisms show that dolomitization does not universally destroy all primary structures and fabrics (organic and inorganic) in carbonate sediments, and that the nature of the dolomitizing water may determine, in part, the degree of preservation.
Proto-dolomite spherulites with heterogeneous interior …
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.
Genetic types and distinguished characteristics of dolomite and …
With an example of the primary dolomite pre- cipitated in microbial mats on the Sabkha coast and microbial dolomite in the Fourth Member of Dengying Formation in the Sichuan Basin, petrological and geochemical features of such dolomite are elaborated. In microbial mats on the modern coast of Abu Dhabi (99.60% microbes are Desulfovibrio ...
Dolomite
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 ...
How does dolomite form? Scientists show the influence of …
The process of recent primary dolomite formation is restricted to extreme ecosystems such as bacterial mats in highly saline lakes and lagoons. "As these systems are very limited in space, there ...
Dolomite
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.
(PDF) Dolomite: Occurrence, Evolution and Economically …
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 ...
A New Model for Formation of Lacustrine Primary Dolomite by Subaqueous
1 Introduction. Genetically, natural dolomites can be grouped into two families: (1) primary dolomites precipitated from solution, either as dolomitic sediment within/at the base of the water column or as dolomite cement within pre-existing voids, and (2) secondary dolomites formed through replacement (dolomitization) of calcite or …
Can Primary Ferroan Dolomite and Ankerite Be …
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 ...
