scholarly journals Low Temperature Serpentinite Replacement by Carbonates during Seawater Influx in the Newfoundland Margin

Minerals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 184 ◽  
Author(s):  
Suzanne Picazo ◽  
Benjamin Malvoisin ◽  
Lukas Baumgartner ◽  
Anne-Sophie Bouvier
Keyword(s):  
Co2 Sequestration ◽  
Inorganic Carbon ◽  
Structural Features ◽  
Hydrothermal Systems ◽  
Carbonate Precipitation ◽  
Rock Interaction ◽  
Carbonate Production ◽  
High Fluid ◽  
Mn Content ◽  
Seawater Transport

Serpentinite replacement by carbonates in the seafloor is one of the main carbonation processes in nature providing insights into the mechanisms of CO2 sequestration; however, the onset of this process and the conditions for the reaction to occur are not yet fully understood. Preserved serpentine rim with pseudomorphs of carbonate after serpentine and lobate-shaped carbonate grains are key structural features for replacement of serpentinite by carbonates. Cathodoluminescence microscopy reveals that Ca-rich carbonate precipitation in serpentinite is associated with a sequential assimilation of Mn. Homogeneous δ18O values at the µm-scale within grains and host sample indicate low formation temperature (<20 °C) from carbonation initiation, with a high fluid to rock ratio. δ13C (1–3 ± 1‰) sit within the measured values for hydrothermal systems (−3–3‰), with no systematic correlation with the Mn content. δ13C values reflect the inorganic carbon dominance and the seawater source of CO2 for carbonate. Thermodynamic modeling of fluid/rock interaction during seawater transport in serpentine predicts Ca-rich carbonate production, at the expense of serpentine, only at temperatures below 50 °C during seawater influx. Mg-rich carbonates can also be produced when using a model of fluid discharge, but at significantly higher temperatures (150 °C). This has major implications for the setting of carbonation in present-day and in fossil margins.

scholarly journals An emerging coral disease outbreak decimated Caribbean coral populations and reshaped reef functionality

2021 ◽  
Author(s):  
Lorenzo Alvarez-Filip ◽  
F. González-Barrios ◽  
Esmeralda Pérez-Cervantes ◽  
Ana Molina-Hernandez ◽  
Nuria Estrada-Saldívar
Keyword(s):  
Coral Species ◽  
Coral Disease ◽  
Structural Features ◽  
Caribbean Region ◽  
Carbonate Production ◽  
Coral Abundance ◽  
Caribbean Coral ◽  
Coral Communities ◽  
The Caribbean ◽  
Physical Functionality

Abstract Diseases are major drivers of the deterioration of coral reefs, linked to major declines in coral abundance, reef functionality, and reef-related ecosystems services1-3. An outbreak of a new disease is currently rampaging through the populations of the remaining reef-building corals across the Caribbean region. The outbreak was first reported in Florida in 2014 and reached the northern Mesoamerican reef by summer 2018, where it spread across the ~ 450-km reef system only in a few months4. Rapid infection was generalized across all sites and mortality rates ranged from 94% to < 10% among the 21 afflicted coral species. This single event further modified the coral communities across the region by increasing the relative dominance of weedy corals and reducing reef functionality, both in terms of functional diversity and calcium carbonate production. This emergent disease is likely to become the most lethal disturbance ever recorded in the Caribbean, and it will likely result in the onset of a new functional regime where key reef-building and complex branching acroporids (a genus apparently unaffected) will once again become conspicuous structural features in reef systems with yet even lower levels of physical functionality.

scholarly journals Changes in Halogen (F, Cl, Br, and I) and S Ratios in Rock-Forming Minerals as Monitors for Magmatic Differentiation, Volatile-Loss, and Hydrothermal Overprint: The Case for Peralkaline Systems

Minerals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 995 ◽  
Author(s):  
Hans G.M. Eggenkamp ◽  
Michael A.W. Marks ◽  
Petya Atanasova ◽  
Thomas Wenzel ◽  
Gregor Markl
Keyword(s):  
Mineral Chemistry ◽  
Hydrothermal Systems ◽  
Fluid Loss ◽  
Volatile Components ◽  
Compositional Variation ◽  
Magmatic Differentiation ◽  
Charge Balance ◽  
Rock Interaction ◽  
Eudialyte Group ◽  
Volatile Loss

We determined the halogen (F, Cl, Br, and I) and sulfur (S) concentrations in Cl-rich rock-forming minerals from five peralkaline complexes. We investigated sodalite (N = 42), eudialyte-group minerals (N = 84), and tugtupite (N = 8) from representative rock samples derived from Ilímaussaq (South Greenland), Norra Kärr (Sweden), Tamazeght (Morocco), Lovozero, and Khibina (Russian Federation). Taken together, sodalite and eudialyte-group minerals dominate the Cl and Br budget of the investigated rocks. For F, however, several other phases (e.g., amphibole, fluorite, villiaumite, and minerals of the rinkite group and the apatite supergroup) are additional sinks, and parts of the S may be scavenged in generally rare sulfides. The investigated minerals contain Cl at the wt.% level, F and S concentrations are in the hundreds to thousands of µg/g-range, Br is less common (0.2–200 µg/g) and I is rare (mostly well below 1 µg/g). Normalized to Cl, sodalite prefers Br relative to eudialyte-group minerals, while F is always enriched in the latter. Our data show that both F and S may represent important components in eudialyte-group minerals, sometimes at similar levels as Cl, which normally dominates. Sulfur reveals redox-dependent behavior: Under reduced crystallization conditions, S is more compatible in eudialyte-group minerals (EGM) than in sodalite, which flips to the opposite under water-rich and presumably more oxidized conditions. We investigate the applicability of F/Cl, Br/Cl, and S/Cl ratios in these minerals in peralkaline systems to better understand the interplay of magmatic differentiation, fluid loss and hydrothermal overprint. Similar to apatite in metaluminous systems, fractionation of sodalite, and eudialyte-group minerals in peralkaline magmas leads to decreasing Br/Cl ratios. The data presented in this study bear implications for the mineral chemistry and compositional variation of sodalite and especially EGM in general. Volatile components in EGM that are not normally considered, such as F and S, can reach concentrations of thousands of µg/g. Especially in the case of F, with its low atomic weight, the results obtained in this study indicate that it is very significant for formulae calculations, neutral charge-balance, and similar aspects at such concentration levels. This study demonstrates that halogen contents and ratios are sensitive monitors for a variety of processes in magmatic-hydrothermal systems, including magmatic fractionation, volatile loss, and fluid–rock interaction.

scholarly journals Experimental Investigation and Numerical Simulation of CO2–Brine–Rock Interactions during CO2 Sequestration in a Deep Saline Aquifer

2019 ◽  
Vol 11 (2) ◽  
pp. 317 ◽  
Author(s):  
Bo Liu ◽  
Fangyuan Zhao ◽  
Jinpeng Xu ◽  
Yueming Qi
Keyword(s):  
Co2 Sequestration ◽  
Co2 Storage ◽  
Early Period ◽  
Mineral Dissolution ◽  
Solution Ph ◽  
Sem Images ◽  
Deep Saline Aquifer ◽  
Rock Interaction ◽  
Geological Co2 Storage ◽  
Co2 Mineralization

CO2 mineralization is a long-term and secure solution for geological CO2 storage that primarily depends on the CO2–brine–rock interaction during CO2 sequestration in subsurface formations. In this study, lab experiments were conducted to investigate the CO2–brine–rock interaction over short timescales, and numerical simulations were performed to reveal dynamic interactions and equilibrium interactions by applying TOUGHREACT and PHREEQC, respectively. In the experiments, the main ions of HCO3− and Ca2+ were detected in the solution, and calcite dissolution and dawsonite precipitation were observed from SEM images. The simulation results showed that the CO2 dissolution and the solution pH were affected by the temperatures, pressures, types of solutions, and solution concentrations and were further influenced by mineral dissolution and precipitation. The results of the equilibrium simulation showed that the dissolved minerals were albite, anhydrite, calcite, Ca-montmorillonite, illite, K-feldspar, and chlorite, and the precipitated minerals were dolomite, kaolinite, and quartz, which led to HCO3−, K+, and Na+ being the main ions in solutions. The results of the dynamic simulation showed that calcite and dolomite dissolved in the early period, while other minerals began to dissolve or precipitate after 100 years. The dissolved minerals were mainly albite, kaolinite, K-feldspar, and chlorite, and precipitated minerals were Ca-montmorillonite, illite, and quartz. Anhydrite and pyrite did not change during the simulation period, and the main ions were HCO3−, Na+, Ca2+, and Mg2+ in the simulation period. This study provides an effective approach for analyzing the CO2–brine–rock interaction at different stages during CO2 storage, and the results are helpful for understanding the CO2 mineralization processes in deep saline aquifers.

Atmospheric dust stimulated marine primary productivity during Earth’s penultimate icehouse

Geology ◽  
2019 ◽  
Author(s):  
Mehrdad Sardar Abadi ◽  
Jeremy D. Owens ◽  
Xiaolei Liu ◽  
Theodore R. Them ◽  
Xingqian Cui ◽  
...  
Keyword(s):  
Primary Production ◽  
Primary Productivity ◽  
Inorganic Carbon ◽  
Carbonate Precipitation ◽  
Fine Dust ◽  
Deep Time ◽  
Point Count ◽  
Lipid Biomarker ◽  
Dust Fraction ◽  
Marine Primary Productivity

The importance of dust as a source of iron (Fe) for primary production in modern oceans is well studied but remains poorly explored for deep time. Vast dust deposits are well recognized from the late Paleozoic and provisionally implicated in primary production through Fe fertilization. Here, we document dust impacts on marine primary productivity in Moscovian (Pennsylvanian, ca. 307 Ma) and Asselian (Permian, ca. 295 Ma) carbonate strata from peri-Gondwanan terranes of Iran. Autotrophic contents of samples, detected by both point-count and lipid-biomarker analyses, track concentrations of highly reactive Fe, consistent with the hypothesis that dust stimulated primary productivity, also promoting carbonate precipitation. Additionally, highly reactive Fe tracks the fine-dust fraction. Dust-borne Fe fertilization increased organic and inorganic carbon cycling in low- and mid-latitude regions of Pangaea, maintaining low pCO2.

scholarly journals Arsenic and Antimony in Hydrothermal Plumes from the Eastern Manus Basin, Papua New Guinea

Geofluids ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Zhigang Zeng ◽  
Xiaoyuan Wang ◽  
Haiyan Qi ◽  
Bowen Zhu
Keyword(s):  
Papua New Guinea ◽  
New Guinea ◽  
Hydrothermal Activity ◽  
Hydrothermal Systems ◽  
Ambient Seawater ◽  
Hydrothermal Plume ◽  
Rock Interaction ◽  
Eastern Manus Basin ◽  
Manus Basin ◽  
Hydrothermal Plumes

Studies on the concentrations of arsenic (As) and antimony (Sb) in seawater columns are very important for tracing hydrothermal plumes and understanding fluid characteristics of seafloor hydrothermal systems. The total As, Sb, Mn, and Cl− concentrations of three hydrothermal plume seawater column samples have been studied at Stations 18G, 18K, and 18B in the eastern Manus back-arc basin, Bismarck Sea, Papua New Guinea. At Stations 18G and 18K, the plumes above North Su and near the Suzette site in the SuSu Knolls hydrothermal field are both enriched in As, Sb, and Mn and depleted in Cl, as a result of contribution of As-Sb-Mn-enriched and Cl-depleted vent fluid outputs to the hydrothermal plume, which is most likely generated in the subseafloor by fluid-rock interaction, magma degassing, or phase separation (boiling of hydrothermal fluid). The plume at Station 18B is enriched in As, Sb, Mn, and Cl, suggesting that As-Sb-Mn-Cl-enriched fluid discharges from vents, which have been generated by fluid-rock interaction. The concentrations of As and Sb anomalous layers, like manganese (Mn), are higher than those of the other layers in the three hydrothermal plume seawater columns. As and Sb with Mn showed a positive correlation (R2>0.8, p<0.05), and the distributions of As and Sb within the hydrothermal plume are not controlled by particle adsorption or biogeochemical cycles, suggesting that As and Sb, like Mn, can be used to detect and describe the characteristics of hydrothermal plumes in seawater environment. In addition, anomalous layer with As/Sb ratio lower than those of ambient seawater at the same temperature is found in the eastern Manus basin, suggesting that the As/Sb ratio may also act as an effective tracer reflecting the effect of hydrothermal activity on As and Sb in the seawater column.

An Experimental Investigation of the Use of Combined Resistivity and Temperature Logs for Scale Monitoring In Carbonate Formations During CO2 Sequestration

2014 ◽  
Vol 137 (3) ◽  
Author(s):  
Abdulrauf Rasheed Adebayo ◽  
Hasan Y. Al-Yousef ◽  
Mohammed Mahmoud
Keyword(s):  
Co2 Sequestration ◽  
Co2 Storage ◽  
The United States ◽  
Co2 Injection ◽  
Petrographic Analysis ◽  
Base Line ◽  
Geochemical Analysis ◽  
Overburden Pressure ◽  
Rock Interaction ◽  
Dissolution And Precipitation

This study investigates the prospect of using permanent downhole resistivity and temperature sensors for scale monitoring during CO2 sequestration in saline carbonate aquifer. Current industry practice involves continuous geochemical analysis of produced formation water and petrographic analysis of cuttings at the surface. A major limitation of such methods is that formation scale dynamics is not captured in situ and in real time. Moreover, high cost and compositional change of produced fluid caused by evolution of dissolved gases are other setbacks. In this study, resistivity and temperature measurements were logged continuously for several months at 30 min interval during CO2 storage in brine saturated core samples. Carbonate samples were acquired from Indiana outcrops in the United States and cut into cylindrical cores. Samples were saturated with synthetic formation brine and CO2 was injected and stored at a temperature of 45 °C, pore pressure of 2000 psig, and an overburden pressure of 2500 psig. The pressure, temperature and resistivity of samples were collected and transmitted to a PC computer at an interval of 30 min for the period of storage. A base line log recorded after CO2 injection but prior to CO2/brine/rock interaction (CBRI) allowed us to track onset of dissolution and precipitation. Deflection away from the baseline either inward or outward during the period of storage marks two distinct reaction phenomenon-dissolution and precipitation. Our hypothesis was justified by results of geochemical analysis of prestorage brine and poststorage brine, and also by petrographic study of the cores. Several other tests were also run to ensure consistency. This study is new compared to previous works in the following ways: Many previous works focused on the applicability of electrical resistivity measurements to track CO2 migration by way of resistivity change as a function of CO2 saturation changes during CO2 sequestration. Many others also studied the effect of CO2 injection on the petrophysical and electrical properties of rocks. Previous works of these types used continuous flow of fluid in and out of the sample and such flow experiments lasted only few hours. The fate of formation resistivity under static condition and at longer storage period was not considered.

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