scholarly journals Dolomite genesis in bioturbated marine zones of an early-middle Miocene coastal mud volcano outcrop (Kuwait)

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ammar Alibrahim ◽  
Michael J. Duane ◽  
Maria Dittrich
Keyword(s):  
Middle Miocene ◽  
Saturation Index ◽  
Mud Volcano ◽  
Microbial Consortia ◽  
Charged Fluids ◽  
Ce Anomaly ◽  
Eu Anomaly ◽  
Dolomite Formation ◽  
Reducing Bacteria ◽  
Dolomite Precipitation

AbstractThe origin of spheroidal dolomitized burrow from Al-Subiya sabkha in Kuwait was previously described as enigmatic as no evidence of precursor calcium carbonate was found in the siliciclastic sediment. An assumption for the genesis of spheroidal dolomite from the same area was attributed to hydrocarbon seepage but no evidence was provided. Here, we investigated a recently discovered early-middle Miocene coastal mud volcano outcrop in Al-Subiya sabkha where dolomitized burrows and spheroidal dolomite are found in bioturbated marine zones, and associated with traces of salt. Conversely, the continental zone lacks bioturbation features, dolomite and traces of salt, which together contrast with bioturbated rich marine zones. Geochemical signatures of Rare Earth Elements + Yttrium show a true positive Ce anomaly (Ce/Ce* > 1.2) and positive Eu/Eu* anomaly of spheroidal dolomite indicating strictly anoxic conditions, and sulphate reduction to sulphide, respectively. Our results are suggestive of a relationship between dolomite formation and interdependent events of hydrocarbon seepage, flux of hypersaline seawater, bioturbation, and fluid flow in the marine zones of the mud volcano. The bioturbation activity of crustaceans introduced channels/burrows in the sediment–water interface allowing for the mixing of seeped pressurized hydrocarbon-charged fluids, and evaporitic seawater. In the irrigated channels/burrows, the seeped pressurized hydrocarbon-charged fluids were oxidized via microbial consortia of methanotrophic archaea and sulphate-reducing bacteria resulting in elevated alkalinity and saturation index with respect to dolomite, thus providing the preferential geochemical microenvironment for dolomite precipitation in the bioturbated sediment.

From poorly-ordered precursors to crystals: Factors contributing to spherulitic growth of dolomite

2021 ◽  
Author(s):  
Juan Diego Rodriguez Blanco ◽  
Adrienn Maria Szucs
Keyword(s):  
Unified Model ◽  
Formation Mechanisms ◽  
Formation Processes ◽  
Ambient Conditions ◽  
Contributing Factors ◽  
Geological Record ◽  
Spherulitic Growth ◽  
Dolomite Problem ◽  
Dolomite Formation ◽  
Dolomite Precipitation

<p>Dolomite is one of the most abundant carbonate minerals in the geological record, yet it barely forms in the present. The contrast in the abundance of dolomite between geological and modern records combined with the impossibility of synthesizing stoichiometric dolomite in the laboratory at ambient conditions are known as the 'dolomite problem'. This enigma has been in the scope of research for decades, trying to understand dolomite formation, mechanisms and the contributing factors. Dolomite is known to form via two abiotic mechanisms; through (1) dolomitization or (2) dolomite cementation. Also, the contribution of microorganisms can result in biotic dolomite crystallization. The mechanisms of dolomite formation at the molecular and nanoscale in biotic and abiotic environments are relatively well-described, but we still struggle to develop a unified model of dolomite formation in modern and ancient settings. In this contribution, we summarize the development of research related to the dolomite formation processes and in particular the direct dolomite precipitation via spherulitic growth of proto-dolomite.</p>

Proto-dolomite formation in microbial consortia dominated by Halomonas strains

Extremophiles ◽  
2019 ◽  
Vol 23 (6) ◽  
pp. 765-781
Author(s):  
Ammar Alibrahim ◽  
Dunia Al-Gharabally ◽  
Huda Mahmoud ◽  
Maria Dittrich
Keyword(s):  
Microbial Consortia ◽  
Dolomite Formation

scholarly journals Implications of Limited Thermophilicity of Nitrite Reduction for Control of Sulfide Production in Oil Reservoirs

2016 ◽  
Vol 82 (14) ◽  
pp. 4190-4199 ◽  
Author(s):  
Tekle Tafese Fida ◽  
Chuan Chen ◽  
Gloria Okpala ◽  
Gerrit Voordouw
Keyword(s):  
Nitrate Reduction ◽  
Nitrite Reduction ◽  
Oil Fields ◽  
Microbial Consortia ◽  
Subsequent Reduction ◽  
Content Type ◽  
Reduction Activity ◽  
Pure Cultures ◽  
Nitrate And Nitrite ◽  
Reducing Bacteria

ABSTRACTNitrate reduction to nitrite in oil fields appears to be more thermophilic than the subsequent reduction of nitrite. Concentrated microbial consortia from oil fields reduced both nitrate and nitrite at 40 and 45°C but only nitrate at and above 50°C. The abundance of thenirSgene correlated with mesophilic nitrite reduction activity.ThaueraandPseudomonaswere the dominant mesophilic nitrate-reducing bacteria (mNRB), whereasPetrobacterandGeobacilluswere the dominant thermophilic NRB (tNRB) in these consortia. The mNRBThauerasp. strain TK001, isolated in this study, reduced nitrate and nitrite at 40 and 45°C but not at 50°C, whereas the tNRBPetrobactersp. strain TK002 andGeobacillussp. strain TK003 reduced nitrate to nitrite but did not reduce nitrite further from 50 to 70°C. Testing of 12 deposited pure cultures of tNRB with 4 electron donors indicated reduction of nitrate in 40 of 48 and reduction of nitrite in only 9 of 48 incubations. Nitrate is injected into high-temperature oil fields to prevent sulfide formation (souring) by sulfate-reducing bacteria (SRB), which are strongly inhibited by nitrite. Injection of cold seawater to produce oil creates mesothermic zones. Our results suggest that preventing the temperature of these zones from dropping below 50°C will limit the reduction of nitrite, allowing more effective souring control.IMPORTANCENitrite can accumulate at temperatures of 50 to 70°C, because nitrate reduction extends to higher temperatures than the subsequent reduction of nitrite. This is important for understanding the fundamentals of thermophilicity and for the control of souring in oil fields catalyzed by SRB, which are strongly inhibited by nitrite.

scholarly journals Petrographic Characteristics and Geochemistry of Volcanic Rocks in the Kyaukmyet Prospect, Monywa District, Central Myanmar

2021 ◽  
Vol 3 (4) ◽  
Author(s):  
Toe Naing Oo ◽  
Agung Harijoko ◽  
Lucas Donny Setijadji
Keyword(s):  
Middle Miocene ◽  
Tectonic Setting ◽  
Volcanic Rocks ◽  
Volcanic Field ◽  
Research Area ◽  
Eu Anomaly ◽  
Volcanic Suite ◽  
Copper Gold ◽  
Arc Setting ◽  
Insight Into

The Kyaukmyet prospect lies approximately 5 km ENE of the highsulfidation Kyisintaung copper-gold deposit, Monywa district, central Myanmar. Geologically, the research area is remarked by magmatic extrusion that occurred during the Late Oligocene to Middle Miocene of Magyigon Formation which led to the outcrops of volcanic rocks. Study detailed on petrographical and geochemical of the Kyaukmyet volcanic rocks has not been performed before the present work. The principal aim of this paper is to document the petrographical and geochemical characteristics of volcanic suite rocks exposed in the Kyaukmyet prospect. The results of this data have provided insight into the origin of the rocks and petrogenetic processes during evolution. Petrographically, all the studied volcanic rocks in the research area show that trachytic and porphyritic textures with phenocrysts of quartz, plagioclase, and K-feldspar which are embedded in a fine to medium grained groundmass. The accessory minerals of this rock consist of biotite, chlorite and opaque mineral.Geochemically, these volcanic rocks having calc-alkaline nature and classified as volcanic field (rhyolite) as well as volcanic arc setting. Based on the chondrite normalized spider diagram, LREE has enriched to HREE in this area which indicated negative Eu anomaly and subduction tectonic setting.

scholarly journals Geochemistry, environmental and provenance study of the Middle Miocene Leitha limestones (Central Paratethys)

2017 ◽  
Vol 68 (3) ◽  
pp. 248-268 ◽  
Author(s):  
Ahmed Ali ◽  
Michael Wagreich
Keyword(s):  
Middle Miocene ◽  
Igneous Rocks ◽  
Gradual Transition ◽  
Vienna Basin ◽  
Elemental Ratios ◽  
Ce Anomaly ◽  
Chemical Index ◽  
Styrian Basin ◽  
Input Source ◽  
Chemical Index Of Alteration

Abstract Mineralogical, major, minor, REE and trace element analyses of rock samples were performed on Middle Miocene limestones (Leitha limestones, Badenian) collected from four localities from Austria (Mannersdorf, Wöllersdorf, Kummer and Rosenberg quarries) and the Fertőrákos quarry in Hungary. Impure to pure limestones (i.e. limited by Al2O3 contents above or below 0.43 wt. %) were tested to evaluate the applicability of various geochemical proxies and indices in regard to provenance and palaeoenvironmental interpretations. Pure and impure limestones from Mannersdorf and Wöllersdorf (southern Vienna Basin) show signs of detrital input (REEs = 27.6 ± 9.8 ppm, Ce anomaly = 0.95 ± 0.1 and the presence of quartz, muscovite and clay minerals in impure limestones) and diagenetic influence (low contents of, e.g., Sr = 221 ± 49 ppm, Na is not detected, Ba = 15.6 ± 8.8 ppm in pure limestones). Thus, in both limestones the reconstruction of original sedimentary palaeoenvironments by geochemistry is hampered. The Kummer and Fertőrákos (Eisenstadt–Sopron Basin) comprise pure limestones (e.g., averages Sr = 571 ± 139 ppm, Na = 213 ± 56 ppm, Ba = 21 ± 4 ppm, REEs = 16 ± 3 ppm and Ce anomaly = 0.62 ± 0.05 and composed predominantly of calcite) exhibiting negligible diagenesis. Deposition under a shallow-water, well oxygenated to intermittent dysoxic marine environment can be reconstructed. Pure to impure limestones at Rosenberg–Retznei (Styrian Basin) are affected to some extent by detrital input and volcano-siliciclastic admixture. The Leitha limestones at Rosenberg have the least diagenetic influence among the studied localities (i.e. averages Sr = 1271 ± 261 ppm, Na = 315 ± 195 ppm, Ba = 32 ± 15 ppm, REEs = 9.8 ± 4.2 ppm and Ce anomaly = 0.77 ± 0.1 and consist of calcite, minor dolomite and quartz). The siliciclastic sources are characterized by immobile elemental ratios (i.e. La/Sc and Th/Co) which apply not only for the siliciclastics, but also for marls and impure limestones. At Mannersdorf the detrital input source varies between intermediate to silicic igneous rocks, while in Kummer and Rosenberg the source is solely silicic igneous rocks. The Chemical Index of Alteration (CIA) is only applicable in the shale-contaminated impure limestones. CIA values of the Leitha limestones from Mannersdorf indicate a gradual transition from warm to temperate palaeoclimate within the limestone succession of the Badenian.

scholarly journals Modern dolomite formation caused by seasonal cycling of oxygenic phototrophs and anoxygenic phototrophs in a hypersaline sabkha

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Zach A. Diloreto ◽  
Sanchit Garg ◽  
Tomaso R. R. Bontognali ◽  
Maria Dittrich
Keyword(s):  
High Salinity ◽  
Atmospheric Oxygen ◽  
Microbial Composition ◽  
Anoxygenic Phototrophs ◽  
Geochemical Conditions ◽  
Exopolymeric Substances ◽  
Dolomite Problem ◽  
Dolomite Formation ◽  
Dolomite Precipitation ◽  
Oxygenic Phototrophs

AbstractThe “Dolomite Problem” has been a controversy for over a century, owing to massive assemblages of low-temperature dolomite in ancient rocks with little dolomite forming today despite favorable geochemical conditions. Experiments show that microbes and their exopolymeric substances (EPS) nucleate dolomite. However, factors controlling ancient abundances of dolomite can still not be explained. To decode the enigma of ancient dolomite, we examined a modern dolomite forming environment, and found that a cyclic shift in microbial community between cyanobacteria and anoxygenic phototrophs creates EPS suited to dolomite precipitation. Specifically, EPS show an increased concentration of carboxylic functional groups as microbial composition cycles from cyanobacterial to anoxygenic phototroph driven communities at low-and high- salinity, respectively. Comparing these results to other low-T forming environments suggests that large turnover of organic material under anoxic conditions is an important driver of the process. Consequently, the shift in atmospheric oxygen throughout Earth’s history may explain important aspects of “The Dolomite Problem”. Our results provide new context for the interpretation of dolomite throughout Earth’s history.

scholarly journals Geochemical behavior of REE associated with Laterization process in Daklak Province, Southern Viet Nam

2014 ◽  
Vol 17 (3) ◽  
pp. 69-75
Author(s):  
K. Okamura ◽  
K. Watanabe ◽  
K. Yonezu ◽  
Huyen Thuong Dang ◽  
Du Cong Do ◽  
...  
Keyword(s):  
Noble Metals ◽  
Xrd Analysis ◽  
The Other ◽  
High Demand ◽  
Basaltic Rocks ◽  
Southern Vietnam ◽  
Ce Anomaly ◽  
Eu Anomaly ◽  
Other Hand ◽  
Ree Pattern

The importance of REE for modern industries is proved by the high demand. The abundance of REE is richer than that of noble metals like gold or silver. However, supply sources are concentrated in China. The share of the product of REE was highest in 2009 (over 90%) and that is used as a national strategy.Mining industry in Vietnam is mainly developed in northern part. Deposits of principle metals are located around Hanoi, and REE deposits (Dong Pao) is also explored in Lai Chau Province. On the other hand, few bauxite mine is in southern Vietnam and the REE exploration is not conducted enough. Therefore, the study about REE in southern Vietnam is significant. Samples are from mainly basalt and granite. REE pattern, which is normalized by the abundance of chondrite, of basaltic rocks and laterites shows that is decreases monotony. That amount of REE is low (50-180ppm). REE pattern of magnetite rocks and laterites has no Eu and Ce anomaly. On the other hand, illuminate rocks and laterites have strong negative Eu anomaly. Clay minerals were observed by XRD analysis using hydraulic elutriation. The result of REE pattern and sequential extraction, it is indicated that the form of HREE is changed and adsorbed to clay and LREE is leached out. In tailing in Stop 16, it is observed that the concentration of HREE (about 3 times to 5 times than that of before washing). Eu anomaly is affected by reductive environment of the cooling of magma, and it is considered that Ce anomaly is occurred by the change of Ce form (Ce3+ to Ce4+). CeO2 is insoluble to water in the soil. From the XRD analysis, the cause of HREE concentration in water treatment is considered by the clay mineral

scholarly journals Iron Oxide–Modified Carbon Electrode and Sulfate-Reducing Bacteria for Simultaneous Enhanced Electricity Generation and Tannery Wastewater Treatment

2021 ◽  
Vol 9 ◽  
Author(s):  
Faiz Miran ◽  
Muhammad Waseem Mumtaz ◽  
Hamid Mukhtar ◽  
Sadia Akram
Keyword(s):  
Iron Oxide ◽  
Sulfate Reducing Bacteria ◽  
Charge Transfer Resistance ◽  
Tannery Wastewater ◽  
Microbial Consortia ◽  
Anode Surface ◽  
Transfer Resistance ◽  
Sulfate Reducing ◽  
Catalytic Sites ◽  
Reducing Bacteria

The microbial fuel cell (MFC) is emerging as a potential technology for extracting energy from wastes/wastewater while they are treated. The major hindrance in MFC commercialization is lower power generation due to the sluggish transfer of electrons from the biocatalyst (bacteria) to the anode surface and inefficient microbial consortia for treating real complex wastewater. To overcome these concerns, a traditional carbon felt (CF) electrode modification was carried out by iron oxide (Fe3O4) nanoparticles via facile dip-and-dry methods, and mixed sulfate-reducing bacteria (SRBs) were utilized as efficient microbial consortia. In the modified CF electrode with SRBs, a considerable improvement in the bioelectrochemical operation was observed, where the power density (309 ± 13 mW/m2) was 1.86 times higher than bare CF with SRBs (166 ± 11 mW/m2), suggesting better bioelectrochemical performance of an SRB-enriched Fe3O4@CF anode in the MFC. This superior activity can be assigned to the lower charge transfer resistance, higher conductance, and increased number of catalytic sites of the Fe3O4@CF electrode. The SRB-enriched Fe3O4@CF anode also assists in enhancing MFC performance in terms of COD removal (>75%), indicating efficient biodegradability of tannery wastewater and a higher electron transfer rate from SRBs to the conductive anode. These findings demonstrate that a combination of the favorable properties of nanocomposites such as Fe3O4@CF anodes and efficient microbes for treating complex wastes can encourage new directions for renewable energy–related applications.

scholarly journals Cr(VI) Reduction by Sulfidogenic and Nonsulfidogenic Microbial Consortia

2003 ◽  
Vol 69 (3) ◽  
pp. 1847-1853 ◽  
Author(s):  
Y. Meriah Arias ◽  
Bradley M. Tebo
Keyword(s):  
Gel Electrophoresis ◽  
Time Course ◽  
Denaturing Gradient Gel Electrophoresis ◽  
Small Subunit ◽  
Ribosomal Genes ◽  
Microbial Consortia ◽  
Sulfate Reducing ◽  
Pcr Products ◽  
Gradient Gel Electrophoresis ◽  
Reducing Bacteria

ABSTRACT In time course experiments, bacterial community compositions were compared between a sulfidogenic and two nonsulfidogenic Cr(VI)-reducing consortia enriched from metal-contaminated sediments. The consortia were subjected to 0 and 0.85 mM or 1.35 mM Cr(VI), and Cr(VI) reduction, growth, and denaturing gradient gel electrophoresis profiles of PCR products of small-subunit (16S) ribosomal genes were compared. Results showed that although Cr(VI) was completely reduced by the three consortia, Cr(VI) inhibited cell growth, with sulfate-reducing bacteria being particularly sensitive to Cr(VI) toxicity relative to other bacteria in the consortia.

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