scholarly journals Can Primary Ferroan Dolomite and Ankerite Be Precipitated? Its Implications for Formation of Submarine Methane-Derived Authigenic Carbonate (MDAC) Chimney

Minerals ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 413 ◽  
Author(s):  
Fan Xu ◽  
Xuelian You ◽  
Qing Li ◽  
Yi Liu
Keyword(s):  
Iron Reduction ◽  
Extracellular Polymeric Substances ◽  
Microbial Culture ◽  
Reduction Zone ◽  
Secondary Products ◽  
Iron Reducing Bacteria ◽  
Sulfate Reducing ◽  
Dolomite Problem ◽  
Reducing Bacteria ◽  
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 and possible mechanisms of microbial mediated precipitation of primary ferroan dolomite and/or ankerite. In the microbial geochemical Fe cycle, many dissimilatory iron-reducing bacteria (DIRB), sulfate-reducing bacteria (SRB), and methanogens can reduce Fe3+ to Fe2+, while SRB and methanogens can also promote the precipitation of primary dolomite. There are an oxygen respiration zone (ORZ), an iron reduction zone (IRZ), a sulfate reduction zone (SRZ), and a methanogenesis zone (MZ) from top to bottom in the muddy sediment diagenesis zone. DIRB in IRZ provide the lower section with Fe2+, which composes many enzymes and proteins to participate in metabolic processes of SRB and methanogens. Lastly, heterogeneous nucleation of ferroan dolomite on extracellular polymeric substances (EPS) and cell surfaces is mediated by SRB and methanogens. Exploring the origin of microbial ferroan dolomite may help to solve the “dolomite problem”.

scholarly journals Ferroan Dolomitization by Seawater Interaction with Mafic Igneous Dikes and Carbonate Host Rock at the Latemar Platform, Dolomites, Italy: Numerical Modeling of Spatial, Temporal, and Temperature Data

Geofluids ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-14 ◽  
Author(s):  
K. Blomme ◽  
S. J. Fowler ◽  
P. Bachaud ◽  
F. H. Nader ◽  
A. Michel ◽  
...  
Keyword(s):  
Carbonate Platform ◽  
Common Factor ◽  
Temperature Data ◽  
Geochemical Data ◽  
Reactive Flow ◽  
Igneous Activity ◽  
Carbonate Host Rock ◽  
Increasing Temperature ◽  
Favorable Conditions ◽  
Ferroan Dolomite

Numerous publications address the petrogenesis of the partially dolomitized Latemar carbonate platform, Italy. A common factor is interpretation of geochemical data in terms of heating via regional igneous activity that provided kinetically favorable conditions for replacement dolomitization. New field, petrographic, XRD, and geochemical data demonstrate a spatial, temporal, and geochemical link between replacement dolomite and local mafic igneous dikes that pervasively intrude the platform. Dikes are dominated by strongly altered plagioclase and clinopyroxene. Significantly, where ferroan dolomite is present, it borders dikes. We hypothesize that seawater interacted with mafic minerals, causing Fe enrichment in the fluid that subsequently participated in dolomitization. This hypothesis was tested numerically through thermodynamic (MELTS, Arxim-GEM) and reactive flow (Arxim-LMA) simulations. Results confirm that seawater becomes Fe-enriched during interaction with clinopyroxene (diopside-hedenbergite) and plagioclase (anorthite-albite-orthoclase) solid solutions. Reaction of modified seawater with limestone causes ferroan and nonferroan replacement dolomitization. Dolomite quantities are strongly influenced by temperature. At 40 to 80°C, ferroan dolomite proportions decrease with increasing temperature, indicating that Latemar dolomitization likely occurred at lower temperatures. This relationship between igneous dikes and dolomitization may have general significance due to the widespread association of carbonates with rifting-related igneous environments.

Development of magnetic soil from ferroan dolomite

1991 ◽  
Vol 18 (11) ◽  
pp. 2043-2046 ◽  
Author(s):  
A. Moukarika ◽  
F. O'Brien ◽  
J. M. D. Coey ◽  
Mauro Resende
Keyword(s):  
Magnetic Soil ◽  
Ferroan Dolomite

Diagenesis in Upper Jurassic marine sandstones from the North Sea Well 14/26-1 and its significance

Clay Minerals ◽  
1986 ◽  
Vol 21 (4) ◽  
pp. 513-535 ◽  
Author(s):  
C. V. Jeans ◽  
M. J. Fisher
Keyword(s):  
Organic Matter ◽  
North Sea ◽  
Upper Jurassic ◽  
Immature Stage ◽  
Maximum Temperature ◽  
Burial Depth ◽  
Hydrocarbon Generation ◽  
Clay Formation ◽  
Later Phase ◽  
Ferroan Dolomite

AbstractA tightly cemented series of marine sandstones, interbedded with shales and mudstones, occurs in the lower part of the Kimmeridge Clay Formation (Kimmeridgian to Ryazanian) of Arco Well 14/26-1 (Core No. 5, 8067–8085 ft). The well is on the northern flank of the Fraserburgh Spur Basement Ridge. The sediments are in the immature stage of hydrocarbon generation and are now at their maximum temperature and burial depth: the bottom hole temperature is 75°C. The sandstone diagenesis was complex, essentially of an intrinsic type, and took place under considerable overpressures. Initially a series of early cements was precipitated (minor chalcedony, quartz, feldspar, ferroan calcite, non-ferroan dolomite and major ferroan dolomite). A later phase of diagenesis embraced two periods of intrastratal solution (each affecting both the silicate and the carbonate components of the sediment) separated by a phase of calcite precipitation and followed by a phase of kaolinite cementation. The early cements are interpreted as being of the intrinsic miagenetic type. The later phase of diagenesis (alternating intrastratal solution and cement precipitation) resulted from the interaction of (i) the biotic breakdown of organic matter by thermophyllic micro-organisms and (ii) the abiotic thermal alteration of organic matter with the mineral components of the sediment: of particular importance were varying PCO2 and the generation of carboxylic and phenolic acids. The diagenetic pattern is closely comparable to that known from various Upper Jurassic sandy shelf sediments in other parts of the northern North Sea which have very different burial histories.

scholarly journals Gortdrumite, a new sulphide mineral containing copper and mercury, from Ireland

1983 ◽  
Vol 47 (342) ◽  
pp. 35-36 ◽  
Author(s):  
G. M. Steed
Keyword(s):  
Crystal Lattice ◽  
Powder Diffraction ◽  
Empirical Formula ◽  
Sulphide Mineral ◽  
Orthorhombic Crystal ◽  
X Ray ◽  
Ferroan Dolomite

AbstractGortdrumite superficially resembles chalcocite but is more distinctly anisotropic, and is present in a vein containing ferroan dolomite and baryte which cuts dolomitized limestones from the Gortdrum Orebody of County Tipperary, Ireland. It has an empirical formula of approximately (Cu,Fe)6Hg2S5. A distinctive powder diffraction X-ray pattern has been obtained which indicates a probable orthorhombic crystal lattice with a 14.96, b 7.90, and c 24.1 Å. The reflectivity at 589 nm is 25.1 to 27.9% and the VHN10 hardness range 186 to 230.

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