SSP3.5 | Microbial and abiotic minerals: processes and archives of environmental change
EDI

Minerals are formed in great diversity under Earth surface conditions, as skeletons, microbialites, speleothems, or authigenic cements, and they preserve a wealth of geochemical, biological, mineralogical, and isotopic information, providing valuable archives of past environmental conditions. Furthermore, minerals form and dissolve during diagenesis, which modifies the properties of carbonate and clastic rocks. Understanding processes of fluid-rock interactions and interpreting mineral archives still requires fundamental research, with implications for the reconstruction of Earth’s geological record, as well as for man-made systems for carbon capture, utilisation and storage (CCUS), geothermal energy, or critical mineral resources.

In this session we welcome oral and poster presentations from a wide range of research of topics, including process-oriented studies in modern systems, the ancient rock record, experiments, computer simulations, and high-resolution microscopy and spectroscopy techniques. We intend to reach a wide community of researchers sharing the common goal of improving our understanding of the fundamental processes underlying mineral formation, which is essential to read our Earth's geological archive.

Co-organized by BG6/GMPV4, co-sponsored by IAS
Convener: Patrick Meister | Co-conveners: Vinyet Baqués, Michael E. Böttcher, Liam Bullock, David Parcerisa, Sally Potter-McIntyre, Patricia RoeserECSECS
Orals
| Tue, 25 Apr, 10:45–12:30 (CEST)
 
Room -2.21
Posters on site
| Attendance Tue, 25 Apr, 14:00–15:45 (CEST)
 
Hall X3
Posters virtual
| Attendance Tue, 25 Apr, 14:00–15:45 (CEST)
 
vHall SSP/GM
Orals |
Tue, 10:45
Tue, 14:00
Tue, 14:00

Orals: Tue, 25 Apr | Room -2.21

Chairpersons: Patrick Meister, Sally Potter-McIntyre, Michael E. Böttcher
10:45–10:50
Mineral nucleation and growth
10:50–11:20
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EGU23-8926
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SSP3.5
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solicited
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Highlight
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On-site presentation
Mariette Wolthers, Alemeh Karami, and Sergej Seepma

All of the crystals that form in natural waters on Earth are formed through reaction between oppositely charged ions. In these crystals, the ions are present in an ideal, charge-balanced ionic ratio. In contrast, the natural solutions in which they form, contain widely diverging ionic ratios (stoichiometries). Consequently, one type of ion, either the anion or the cation, will be in excess and the other in limitation. Experimental results have shown previously that the solution ionic ratio affects crystal growth rate at constant degree of supersaturation, pH, temperature and ionic strength. This behaviour can be explained with an ion-by-ion growth model (e.g. Wolthers et al., 2012a).

In this presentation, I will illustrate how this imbalance impacts the new formation, i.e. nucleation, of CaCO3, BaSO4 and FeS. Solution stoichiometry affects the timing and rate of nucleation, the charge of the particles formed and potentially their aggregation behaviour (e.g. Seepma et al., 2021), among others. The impact of solution ionic ratio on nucleation and growth varies for the three different mineral systems and indicates that natural mineralisation processes will also depend on solution stoichiometry.

 

References:

Seepma, S., Ruiz Hernandez, S., Nehrke, G., Soetaert, K., Philipse, A. P., Kuipers, B. W. M., & Wolthers, M. (2021). Controlling CaCO3 particle size with {Ca2+}:{CO32-} ratios in aqueous environments. Crystal Growth & Design, 21(3), 1576-1590. https://doi.org/10.1021/acs.cgd.0c01403

Wolthers, M., Nehrke, G., Gustafsson, J. P., & Van Cappellen, P. (2012). Calcite growth kinetics: Modeling the effect of solution stoichiometry. Geochimica et Cosmochimica Acta, 77(4), 121-134. https://doi.org/10.1016/j.gca.2011.11.003

How to cite: Wolthers, M., Karami, A., and Seepma, S.: Abiotic mineral formation: the impact of solution stoichiometry on nucleation and growth, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8926, https://doi.org/10.5194/egusphere-egu23-8926, 2023.

11:20–11:30
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EGU23-15109
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SSP3.5
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ECS
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On-site presentation
Sergej Seepma, Bonny W. M. Kuipers, and Mariette Wolthers

The impact of solution stoichiometry, upon formation of BaSO4 crystals in 0.02 M NaCl suspensions, on the development of particle size was investigated using Dynamic Light Scattering (DLS). Measurements were performed on a set of suspensions prepared with predefined initial supersaturation (Ωbarite = {Ba2+}{SO42-}/Ksp = 1000) and dissolved ion activity stoichiometries (raq = {Ba2+}:{SO42-} = 0.01, 0.1, 1, 10 and 100), at a pH of 5.5 to 6.0, and ambient temperature and pressure. At this Ωbarite and set of raq, the average apparent hydrodynamic particle size of the largest population present in all suspensions grew from ~ 200 nm to ~ 700 nm within 10 to 15 minutes. This was independently confirmed by TEM imaging. Additional DLS measurements conducted at the same conditions in flow confirmed that the BaSO4 formation kinetics were very fast for our specifically chosen conditions. The DLS flow measurements, monitoring the first minute of BaSO4 formation, showed strong signs of aggregation of prenucleation clusters forming particles with a size in the range of 200 – 300 nm for every raq. The estimated initial bulk growth rates from batch DLS results show that BaSO4 crystals formed fastest at near stoichiometric conditions and more slowly at non-stoichiometric conditions. Moreover, at extreme SO4-limiting conditions barite formation was slower compared to Ba-limiting conditions. Our results show that DLS can be used to investigate nucleation and growth at carefully selected experimental and analytical conditions. Additional SEM imaging on formed BaSO4 crystals for a range of initial conditions of Ωbarite (i.e. 31, 200, 1000 and 6000), raq (0.01, 0.1, 1, 10 and 100) and different background electrolytes (i.e. NaCl, KCl, NaNO3, MgSO4 and SrCl2) confirms that {Ba2+}:{SO42-} impacts the growth rate significantly in different directions for the different background electrolytes at the different Ωbarite-values. Furthermore, the BaSO4 crystal morphology varies with raq and the type of background electrolyte. The combined DLS, TEM and SEM results imply that solution stoichiometry should be considered when optimizing antiscalant efficiency to regulate BaSO4 (scale) formation processes.

How to cite: Seepma, S., Kuipers, B. W. M., and Wolthers, M.: The Influence of {Ba2+}:{SO42-} Solution Stoichiometry on BaSO4 Crystal Nucleation and Growth in Aqueous Solutions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15109, https://doi.org/10.5194/egusphere-egu23-15109, 2023.

11:30–11:40
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EGU23-16240
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SSP3.5
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Highlight
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On-site presentation
Encarnacion Ruiz-Agudo and Cristina Ruiz-Agudo

In the last decades numerous studies have shown that most calcifying organisms build their shells and skeletons via non-classical crystallization processes, including the formation of transient, metastable amorphous calcium carbonate (ACC) as a precursor phase. Although a significant progress has been achieved at understanding CaCO3 growth via amorphous precursors, there are still aspects that remain unexplored. Knowledge of the role of different elements that are commonly co-precipitated with carbonates at modulating the early stages of calcium carbonate formation and the amorphous to crystalline transition is needed to constrain biomineralisation processes and to allow the understanding of how sensitive calcification is to past, current, and future environmental change. In order to address this issue, we investigated the incorporation of boron and magnesium into ACC precipitated under different pHs. This study evaluates the influence of B and Mg on the stability and water content of ACC and its formation mechanism. This information, together with an analysis of the B and Mg content of ACC formed at different pH conditions, provide insights into the factors controlling the chemical signatures and properties of the carbonate polymorphs formed via the ACC pathway.

How to cite: Ruiz-Agudo, E. and Ruiz-Agudo, C.: An experimental study of the role of ions at modulating the early stages of calcium carbonate formation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16240, https://doi.org/10.5194/egusphere-egu23-16240, 2023.

11:40–12:00
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EGU23-11380
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SSP3.5
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solicited
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On-site presentation
Stefano Bernasconi, Paul Petschnig, Nathan Looser, Jordon Hemingway, and Max Schmidt

Carbonate clumped isotope thermometry can be used to constrain the formation temperature and the oxygen isotope composition of the fluids involved in the precipitation of carbonate minerals. It exploits the preference of 13C-18O bonds in carbonate molecules to form with decreasing temperature. This method has important applications in reconstructing the temperature history of the ocean through time, paleoaltimetry and diagenesis. Dolomite in the rock record can have multiple origins. It can form as a primary precipitate in seawater, during early diagenesis or as a late burial diagenetic phase. Depending on its origin thus dolomite can provide information on earth surface temperatures, or on the diagenetic history of carbonate sequences, particularly in successions and times in earth history where calcite is less abundant.

The use of clumped isotopes to reconstruct dolomitization conditions in ancient sequences, requires determining if the temperatures reconstructed from clumped isotopes reflect the original temperature of formation and how resistant clumped isotope signals are against bond reordering at elevated temperatures during burial. In this contribution we will present a series of heating experiments at temperatures between 360 and 480 °C with runtimes between 0.125 and 426 hours we used to determine bond reordering kinetic parameters. In contrast to the only existing previous study1, which used millimeter-sized hydrothermal dolomite, we used fine grained sedimentary dolomites to test the influence of grains size, surface area-to-crystal volume ratio (S/V), and cation ordering on bond reordering kinetics. Specifically, we analysed a lacustrine dolomite with poor cation ordering and compare it to a replacement dolomite with high cation ordering, both being almost perfectly stoichiometric. Experimental results show a higher susceptibility to solid state bond reordering as well as stable isotope depletion in the lacustrine sample, whereas the replacement dolomite is comparatively resistant, similar to previously studied coarse-grained hydrothermal dolomite. We compare our experimental results to previous work on dolomite and different calcites and derive robust, dolomite-specific kinetic parameters for the disordered kinetic model of Hemingway and Henkes2. We show that Δ47 reordering in dolomite, similar to calcite, is material specific. Furthermore, in contrast to crystallographically well-ordered dolomite, disordered and microcrystalline dolomite with high S/V ratios shows a rapid depletion in stable-isotope and Δ47 values. The application of existing reordering models to our experimental data stresses the need for further experimental temperature-time series experiments to properly constrain dolomite Δ47 reordering over geologic timescales for different dolomite types.

 

1:    Lloyd MK, Ryb U, Eiler JM (2018) Experimental calibration of clumped isotope reordering in dolomite. Geochim Cosmochim Acta 242:1–20

2:    Hemingway, J., D. and G., H. Henkes, (2021) A disordered kinetic model for clumped isotope bond reordering in carbonates. Earth and Planetary Science Letters, 566, 116962.

How to cite: Bernasconi, S., Petschnig, P., Looser, N., Hemingway, J., and Schmidt, M.: Clumped isotope bond reordering in dolomite: new experimental constraints based on low temperature sedimentary dolomites, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11380, https://doi.org/10.5194/egusphere-egu23-11380, 2023.

Microbially influenced minerals
12:00–12:10
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EGU23-14703
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SSP3.5
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Virtual presentation
Francisca Martinez-Ruiz, Adina Paytan, Ricardo Monedero-Contreras, and Gert de Lange

Mediterranean sapropels represent an exceptional example of productivity fluctuations reconstructed from Ba proxies. They have been cyclically deposited in the Mediterranean by the combination of climatically induced increases in primary productivity and changes in bottom-water oxygenation. The main driver behind the deposition of sapropels was the monsoon-related freshwater inputs into the eastern Mediterranean in response to periodic northward shifts of the intertropical convergence zone (ITCZ) that resulted in increasing nutrient supply and subsequently enhanced productivity and Ba accumulation. In general, increasing Ba content in marine sediments has been interpreted as a direct indicator of marine primary productivity. However, the diverse processes involved in barite precipitation are still poorly investigated. For instance, types of productivity and modes of nutrient delivery to the photic zone have been poorly explored in terms of spatial variability across the Mediterranean during sapropel deposition, which is crucial for Ba proxies interpretation. Recent insights from experimental work, as well as observations from microenvironments of intense organic matter mineralization in the ocean water column have demonstrated the role of bacteria and extracellular polymeric substances (EPS) production in barite precipitation. Both bacterial cells and EPS provide charged surfaces that bind metals inducing mineralization, therefore, playing an essential role in promoting locally high concentrations of Ba leading to barite formation. This occurs through P-rich amorphous precursor phases, being phosphate groups in EPS, and bacterial cells the main sites for binding Ba. The ubiquitous presence of bacteria in aquatic systems, and in particular in the mesopelagic zone at depths of intense organic matter mineralization, and their inherent ability to biomineralize, make them extremely important agents in the Ba biogeochemical cycle. Thus, reconstruction and interpretations of past productivity and its potential spatial variations as well as fluctuations over time need to consider this microbial paleoperspective. In fact, in the modern Mediterranean, some significant differences in types of productivity and bacterial production exist, which could have also been important in the past, resulting in regional changes in barite production. Assessing the nature of barite-related processes is therefore crucial for the correct interpretations of primary productivity variations during sapropel deposition. In fact, the strong link between organo-mineralization and microbial processes in the past still requires further investigation to determine factors controlling barite accumulation rates in the Mediterranean sapropels.

How to cite: Martinez-Ruiz, F., Paytan, A., Monedero-Contreras, R., and de Lange, G.: Processes underlying barite formation in the Mediterranean: a record of marine microbial activity during sapropel deposition, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14703, https://doi.org/10.5194/egusphere-egu23-14703, 2023.

12:10–12:20
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EGU23-2568
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SSP3.5
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ECS
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On-site presentation
Paweł Działak and Andrzej Borkowski

Bacteriophages are abundant in all environments on the Earth. However, their impact on mineral formation remains undiscovered. In our experimental approach, two distinctly different bacteriophages (Pseudomonas phage Φ6 and Escherichia phage P1) were used to assess their influence on mineral formation. Here, we focus on the formation of carbonates and sulfides.

Bacteriophages are supposed to influence carbonate precipitation. We demonstrated that bacteriophages induce the formation of regular ‘viral-like’ mineral particles. These particles were strongly aggregated, while such phenomena did not occur in the control sample. Moreover, bacteriophages induced the formation of vaterite (an unstable form of calcium carbonate), which remained stable for a longer time. 

The origin of framboidal pyrite is an important issue from the point of view of the precipitation of sulfide minerals. It is assumed that ions present in the solution can be bound by bacteriophages and thus influence mineral precipitation. We postulated that bacteriophages might be one of the factors that induce the precipitation of finer mineral particles, which can then be formed into framboid-like structures. 

It seems that bacteriophages may play a crucial role in the precipitation of various minerals. In our research, for both minerals, similar phenomena occurred: (i) change in the shape of mineral particles; (ii) occurrence of aggregation/agglomeration in the presence of bacteriophages; (iii) change in the size of agglomerates/aggregates. Moreover, XRD patterns were different for carbonates precipitated in the presence of bacteriophages. However, such differences were not visible for sulfides, probably due to the strong oxidation caused by the difficulties in maintaining the samples.

How to cite: Działak, P. and Borkowski, A.: Experimental studies on the role of bacteriophages in the formation of carbonates and sulphides, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2568, https://doi.org/10.5194/egusphere-egu23-2568, 2023.

Diagenesis
12:20–12:30
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EGU23-12488
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SSP3.5
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ECS
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On-site presentation
Yu Yan, David Misch, Reinhard Sachsenhofer, and Min Wang

Both the primary mineral composition and secondary diagenetic processes may affect shale reservoir characteristics such as effective porosity, pore throat distribution, resulting permeability, wettability, etc. Hence, a better understanding of shale diagenesis is key to the prediction of shale oil and gas resource potential. The first member of the Qingshankou Formation (K2qn1) in the northern part of the Songliao Basin is an organic-rich shale with great source potential. Attempting to characterize the influence of different diagenetic processes active in the clay mineral-rich formation on pore space evolution, 19 sample from the K2qn1 interval (vitrinite reflectance from 0.55 to 1.58 %Ro) were selected and investigated by optical and scanning electron microscopy (SEM). This maturity window covers the hydrocarbon generative and expulsion stages and hence allows to reconstruct the processes active during organic matter (OM) transformation. Interactions of inorganic mineral grains with products of the transformation products of lamalginite-dominated primary OM (i.e., soluble bitumen) and associated pore space changes could be observed at various maturity stages. SEM visible authigenic quartz is present from the oil window up to the dry gas window, mostly in the form of submicron (nm-μm) size microcrystals embedded in the interparticle pores between clay minerals. Euhedral and subhedral quartz types are occasionally visible in mineral dissolution pores and OM-hosted pores associated with post-oil solid bitumen. Authigenic clay minerals (such as chlorite) are visible along the whole maturity range, but predominantly form in interparticle and OM-hosted pores at maturity levels >1.1 %Ro. Solid bitumen impregnations are often associated with authigenic minerals, forming rims along crystal boundaries. This indicates that the mineral precipitation may be associated with fluid compositional changes which occur during hydrocarbon generation (e.g., formation of water-soluble organic acids, etc.). According to the SEM observations, clay mineral-associated interparticle pores are the main storage space for bitumen in the K2qn1 source rock reservoir. These pores may be occluded at early to peak oil window maturity and re-opened at post-oil window maturity due to the expulsion of main parts of the generated hydrocarbons (pyrobitumen stage). This highlights that hydrocarbon generation and expulsion are key factors in porosity development both with respect to organic (bitumen generation) and inorganic (e.g., authigenic quartz precipitation) transformation reactions.

How to cite: Yan, Y., Misch, D., Sachsenhofer, R., and Wang, M.: Diagenesis in lacustrine organic-rich shales: evolution pathways and implications for reservoir characteristics, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12488, https://doi.org/10.5194/egusphere-egu23-12488, 2023.

Posters on site: Tue, 25 Apr, 14:00–15:45 | Hall X3

Chairpersons: Michael E. Böttcher, Liam Bullock, Sally Potter-McIntyre
Method development
X3.74
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EGU23-3317
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SSP3.5
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ECS
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Yasumoto Tsukada, Stephen Bowden, and Patrick Schmid

Moganite is a silica polymorph found intergrown with microcrystalline quartz. Raman spectroscopy is used to detect moganite using a band at 501 cm-1, generated by the vibration of a four-membered tetrahedral SiO2. This band is numerically distinct from the most intense band used to identify quartz at 465cm-1, and thus Raman spectroscopy might be considered a reliable methodology to detect moganite. However, the moganite detection using Raman spectra must be done with caution since a band at 503 cm-1 can be caused by a Si-O vibration of silanole (SiOH), and thus the two bands interfere and may mingle. Such interference might be mitigated or increased by sample preparation, but it has not previously been shown with certainty whether powdered or intact rock surfaces, would exhibit the greatest interference. Here, we present a Raman spectroscopic study of different particle sizes on moganite and flint to investigate how it affects moganite detection. We found a Raman band in pristine flint with a similar peak position to moganite, but subsequent to heat treatment at 700 ˚C for 6 hours, the band disappeared indicating the presence of silanole rather than moganite. Powdering the sample in combination with the use of higher laser powers increased this effect and the relative intensity of the silanole band. Overall, the Raman spectrum of flint was found to be more sensitive to laser-power-induced artifacts than moganite. Aggregated quartz powder is known to be affected by laser-induced heating during Raman spectroscopy. However, the effect of the heating on silanole and moganite bands is not as well documented. The peak shift of moganite has a similar trend to the phase transition detected by Raman Spectroscopy and XRD with heat thus the two approaches are consistent. Furthermore, the silanole band is known to change its position by 6 cm-1 at heating from room temperature to 600 ˚C. Based on the results from other research, the peak shift and broadening in the present study can be interpreted as an effect of laser-induced heating. To date, for mineral analyses, the number of studies reporting the effects of laser-induced heating on minerals is limited, which contrasts strongly with Raman spectroscopy of organic materials. The result in the present study suggests that the band shift of silanole and the transition of α-β moganite can be caused by the heat of the laser should be taken into consideration especially when small particle size moganite is being identified by Raman Spectrum. However, this same sensitivity to temperature may indicate potential as a measure of paleotemperature.

How to cite: Tsukada, Y., Bowden, S., and Schmid, P.: The Effect of Laser-induced Heating on Moganite, Silanole and Quartz during Raman Spectroscopy, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3317, https://doi.org/10.5194/egusphere-egu23-3317, 2023.

Mineral nucleation and growth
X3.75
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EGU23-14156
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SSP3.5
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ECS
Alemeh Karami, Janou Koskamp, and Mariette Wolthers

Mackinawite (FeS) is the first iron sulfide phase to form in anoxic systems containing ferrous iron and sulfide. It is a major inorganic scale in oil and gas piping and its catalytic properties make it a potential candidate for a variety of industrial applications including energy storage systems and batteries. This, together with Mackinawite’s potential for remediation through the doping of heaving metal cations, makes it an interesting subject of investigation. Since in natural conditions iron and sulfide do not generally occur in alike concentrations, investigating diverging ratios of iron:sulfide activities, improves our knowledge about iron sulfide early formation in natural and geo-engineered settings.

Here, we investigated FeS formation at a saturation index of 1.8 (~63 fold supersaturation), varying {Fe2+}:{HS-} and at pH 10.2. Particle size distribution was explored using Dynamic Light Scattering measurements, surface charge of particles (Zeta potential) was measured with Electrophoretic Light Scattering and samples were imaged using Transmission Electron Microscopy.

Regarding particle charge, we observed particles that were more negatively charged when the solution had an excess of anions (HS-), compared to solutions with more cation(Fe2+) which led to having particles with less negative net surface charge.

Furthermore, preliminary results indicated non-linear evolution of FeS particle size through time. Higher concentrations of iron promoted formation of larger particles, whereas having more sulfide induced the formation of  smaller particles.

Our observations reveal that FeS particle formation is sensitive to the ratio of {Fe2+}:{HS-} in the solution. When there is an excess of iron, growth and/or aggregation of nuclei is enhanced and predominates over nucleation, in contrast to the other conditions(equal activities, or excess HS-). This behavior may be explained by the zeta potential, which reflects the surface charge of the particles. At pH 10, the FeS particles are negatively charged (Wolthers et al., 2005) and more so at stoichiometric and excess-sulfide conditions. In excess Fe, the particles are less charged and therefore less physically stable and more likely to aggregate, leading to larger particle growth.

How to cite: Karami, A., Koskamp, J., and Wolthers, M.: Investigating the impact of {Fe2+}:{HS-} ratio on FeS formation: preliminary results on particle size and charge, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14156, https://doi.org/10.5194/egusphere-egu23-14156, 2023.

X3.76
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EGU23-3946
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SSP3.5
Patrick Meister

Spherulitic crystal growth structures are omnipresent in the sedimentary realm. They occur as allochems, such as ooids, as crystal fans in stromatolites or as botryoids in tufa and speleothems. The spherulitic structure is due to radially arranged crystallographic axes which manifests as round outer shapes and the characteristic extinction cross under cross-polarized light. Often, spherulitic structures are ascribed to some mystic biological effect, however, without providing any further explanation of the underlying mechanism.

While the overall driving force for spherulitic growth arises from the crystals attempting to reduce their surface energy, several pathways have been suggested in the literature by which the crystal structure and shape relaxes to the stress field imposed by the surface energy. Prominent is the concept of auto-deformation, where low-angle branching is introduced by crystallographic rearrangement in the interior of the crystal, due to cascades of discrete fracturing. In contrast, a growth front nucleation model has been suggested, in which case low-angle branching already nucleates as atoms or ions are being attached. In this mechanism, the stress field is dissipated before the atoms are incorporated permanently in the crystal lattice, which has the advantage that no bond-breaking event would be necessary (Meister, in press1). From a non-classical point of view, the growth front model can be modified in the sense that already existing nano-particles are attaching in an oriented way, so that low-angle boundaries are established.

Ultimately, the prevailing crystal growth mode depends on crystal growth kinetics, as a result of both macroscopic factors – such as the supersaturation ratio of the bulk solution and interfacial energy – and molecular-scale factors that shape the nano-scale energy landscape. The mineralogical and crystallographic structure that can be reached by overcoming the lowest possible kinetic barrier should result, just as predicted by Ostwald’s step rule (Meister, in press2). Inorganic and organic co-solutes may act as modifiers, impacting the interface energy landscape and thereby shifting the boundary between step-flow growth and adhesive growth, facilitating non-crystallographic branching, and, thus, provoking configurations different from idiomorphic crystals.

1) Meister, P. (in press) Spherulitic mineral growth: auto-deformation, growth front nucleation, or semi-oriented attachment? In P. Meister, C. Fischer and N. Preto (Eds.): “Nucleation and growth of sedimentary minerals”, IAS Special Publications, accepted.

2) Meister, P. (in press) Ostwald’s step rule: a consequence of growth kinetics and nano-scale energy landscape. In P. Meister, C. Fischer and N. Preto (Eds.): “Nucleation and growth of sedimentary minerals”, IAS Special Publications, accepted.

How to cite: Meister, P.: Surface stress dissipation during growth front nucleation as mechanism for spherulitic crystal growth, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3946, https://doi.org/10.5194/egusphere-egu23-3946, 2023.

Organically influenced minerals
X3.77
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EGU23-9504
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SSP3.5
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ECS
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Charlotte Dejean, Nathaly Ortiz Peña, Bénédicte Ménez, Cyril Gadal, Hélène Bouquerel, Damien Alloyeau, and Alexandre Gélabert

Manganese oxide minerals are among the most powerful oxidizers on the Earth's surface. They are therefore key minerals both for the origin of life and exobiology issues but also for those concerning current biogeochemical cycles. Most of these manganese oxides are formed by biomineralization processes carried out by microorganisms that must be deciphered to better understand the fate of metals and metalloids in subsurface environments. A recent study showed that liquid-cell scanning transmission electron microscopy (LC-STEM) enables to monitor in situ the growth of Mn-bearing minerals onto Escherichia coli cells. This study has also highlighted the critical role of the chemical functions carried by cell surfaces and exopolymers during biomineralization. However, the contribution of the different functional groups associated to these biopolymers during mineral nucleation and growth remains poorly defined. In order to better assess the role played by these different chemical functions during biomineralization, functionalized polystyrene beads were used here as analogs of biological surfaces. In addition to control beads without functionalization, nine representative types of functionalization were selected, ranging from simple carboxylic and amino groups, to strong chelating agents such as nitrilotriacetic acid (NTA), or more complex proteins such as streptavidin and collagen. Each bead type was exposed to Mn(II)-bearing solution, and mineralization dynamics was continuously monitored in situ by LC-STEM. Mn mineralization was observed for all ten bead types with the formation of pyrolusite (MnO2) at the bead surfaces, as the result of changes in Mn redox state in solution triggered by radiolysis resulting from water and electron beam interactions. For all bead types, mineralization can be described as a nucleation step followed by the formation of larger dendritic structures. However, nucleation site densities, precipitates morphologies, as well as the overall mineral growth kinetics were found to vary significantly between the different grafted chemical functions. The bead surface charge, estimated by electrophoretic mobility, only partly explains these differences in mineralization dynamics. Steric effects, hydrophobicity as well as Mn affinity for the functional groups are certainly important parameters for Mn mineralization. As a result, this study brings interesting constraints on biomineralization processes driven by microorganisms.

How to cite: Dejean, C., Ortiz Peña, N., Ménez, B., Gadal, C., Bouquerel, H., Alloyeau, D., and Gélabert, A.: Impacts of functionalized organic surfaces in Mn oxides formation in situ monitored by electron microscopy, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9504, https://doi.org/10.5194/egusphere-egu23-9504, 2023.

X3.78
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EGU23-17414
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SSP3.5
Hidekazu Kobatake and Haruhiko Inoue

It has been well known that the activity of bacteria causes a promoting crystallization in the natural environment. On the other hand, it has been pointed out that bacteria activity also plays a role in the dissolution of crystals, and the microscopic observation showed that the inhibition of the bacteria affects the pit formation to promote the dissolution of calcite[1]. The authors found a grope of bacteria, which promotes the dissolution process of calcite. We isolated bacteria from calcite-enriched soil and examined their calcite-degrading activity.

To understand the role of bacteria in the dissolution process, In the experiments, the cleavage surface of the calcite was exposed to the culture fluid of the bacteria for 4 days to investigate the effect of bacteria on the calcite dissolution. The surface morphology of the calcite was investigated using an optical microscope and scanning electron microscope after the dissolution experiment in the culture fluid with bacteria.

The calcium ion concentration in the culture fluid of Streptomyces was one-third of control, Escherichia coli DH5a, indicating the promoting the dissolution process of calcite. The surface observation of the calcite surface, which has been exposed in the culture fluid of bacteria shows the etch pits, which were formed during the dissolution process.

Differing from the previous study, [1] the shape of the etch pits showed a rounded and asymmetric shape and deviated from the rectangular, which reflects the symmetry of the surface. These etch pits were formed accompanied by the bacteria colony. And the bacteria colony was formed along the cleavage step on the calcite surface. These observations infer that the inhabitation of the bacteria and the dissolution of the calcite are related to each other and the effect of the surface activity of calcite in the dissolution process could be larger by the biological activity.

Reference

[1] A. Luettge and P.G. Conrad, Direct observation of microbial inhibition of calcite dissolution, App. Env. Micr (70) 2004

How to cite: Kobatake, H. and Inoue, H.: Selective dissolution of calcite in a bacterial habitat environment, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17414, https://doi.org/10.5194/egusphere-egu23-17414, 2023.

Diagenetic rock - fluid interactions
X3.79
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EGU23-9263
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SSP3.5
Sally Potter-McIntyre

Iron (oxyhydr)oxide concretions are cemented mineral masses formed via authigenic cements in sedimentary rocks at any time during diagenesis (syndepositional, burial, and late-stage). These features are common in porous and permeable sandstone and even present on Mars in at least two different locations and formations. One notable study area for the spherules is within the Navajo Sandstone in the Grand Staircase Escalante National Monument (GSENM) in southern Utah. Diagenetic concretions, particularly iron (oxyhydr)oxide mineralogies, are thought to form via a two-fluid mixing model where one fluid has the reactants in solution, then another fluid meets and mixes with the reactant-bearing fluid, and the concretions precipitate. These two fluids could be a reducing fluid that mobilizes iron as Fe2+ and then mixes with an oxidizing fluid to precipitate iron oxyhydr(oxide), but an acidic fluid could mobilize iron as Fe3+ and then interact with a neutral fluid for the same result.  Another proposed model for iron (oxyhydr)oxide concretions calls for calcium carbonate precursor concretions and mobilization of iron by acidic fluids. The acidic, iron-bearing fluid then dissolves the carbonate concretion, which buffers the solution enough to precipitate iron oxyhydr(oxide) in the same morphology as the original calcite concretion. Our research shows that in GSENM, iron concretions and calcite concretions are present within the same stratigraphic horizon and in close proximity. Another field observation is the presence of calcite concretions in clusters along paleo water tables, rather than dispersed in a self-organized spacing within three dimensions like the iron features. Also present within the region are concretions with manganese oxide phases and the iron concretions tend to include manganese oxide, but not calcite. Calcite concretions do commonly contain some iron (oxyhydr)oxides, particularly as rims around grains. In the Entrada Sandstone, also in southern Utah, iron concretions are precipitated from fluid brought in with an igneous intrusion that mobilized the iron within the host rock. Structures in the area acted as baffles keeping the fluid stagnant and iron (oxyhydr)oxide concretions are only present between the igneous dike and the nearest baffle. Calcite concretions in the area are dispersed throughout the host rock (both within and outside of the baffles), suggested that mineral precipitation rates control concretion formation and that iron (oxyhydr)oxide concretions need a longer period of fluid stagnation for formation than do calcite concretions. Understanding the complex formation mechanisms can help to unravel the history of diagenetic fluids of varying chemistries and therefore, the habitability of subsurface environments on both Earth and Mars.

How to cite: Potter-McIntyre, S.: Iron (oxyhydr)oxide concretion formation: New insights from southern Utah, USA, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9263, https://doi.org/10.5194/egusphere-egu23-9263, 2023.

X3.80
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EGU23-11426
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SSP3.5
|
ECS
Joonas Wasiljeff, Johanna Salminen, Yann Lahaye, and Joonas Virtasalo

Marine iron-manganese concretions are metal-containing biogeochemical precipitates abundantly encountered in the seafloors of the world ocean. Their importance in paleoenvironmental reconstructions as well as a source for critical metals has been recently realized. Diagenetic and hydrogenetic concretions, however, have different compositions and subsequently can have differing capacities for recording oceanographic processes and for economic utilization. Therefore, their genetic classification can provide crucial information for both environmental and economic applications. Traditionally discrimination of different marine iron-manganese concretion origins has been achieved with geochemical methods, such as investigating their rare earth element content. It is now evident that iron-manganese concretions also host magnetic minerals that are likely formed by facilitation by microbial processes. Currently it is unknown if the different genetic backgrounds of iron-manganese concretions are reflected in their magnetic properties.  

We compared the geochemical and magnetic properties of diagenetic iron-manganese concretions from the Baltic Sea to hydrogenetic concretions from the Pacific. While the commonly utilized geochemical indicators differentiate the concretions found from the two localities as diagenetic and hydrogenetic, it also appears that concentration dependent magnetic parameters such as saturation magnetization and anhysteretic remanent magnetization effectively discriminate between the different types of concretions. Mineral magnetic methods are fast and cost-effective and may provide an alternative tool to quickly screen out diagenetic from hydrogenetic precipitates.

This research is part of the Fermaid project, funded by the Academy of Finland grant 332249.

How to cite: Wasiljeff, J., Salminen, J., Lahaye, Y., and Virtasalo, J.: Mineral magnetic discrimination between diagenetic and hydrogenetic iron-manganese concretions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11426, https://doi.org/10.5194/egusphere-egu23-11426, 2023.

X3.81
|
EGU23-12008
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SSP3.5
|
ECS
Robert Lehmann, Dinusha Eshvara Arachchige, Michaela Aehnelt, and Kai Uwe Totsche

Typically thick aeration zones of topographic groundwater recharge areas are hardly investigated parts of subsurface ecosystems and the subsurface water/matter cycles (Lehmann and Totsche 2020). In fractured bedrock settings, here, mineral surfaces and assemblages, exposed to major flow-paths, can largely differ from the bulk rock-forming compositions. Representing highly diverse and likely important reaction spaces for subsurface matter cycling and groundwater quality, yet, their compositional and morphological diversity, their provided habitat structure and endolithic dwellers, and their matter sources and dynamics are scarcely known. In drill core samples of Triassic limestone-mudstone alternations from the Hainich Critical Zone Exploratory (Collaborative Research Center AquaDiva), we characterized and classified alteration features across regolith down to the phreatic zone. Besides analysis of fracture/pore fillings and rock matrices by digital microscopy, SEM(-EDX), among others, we investigated possible controlling factors like lithofacies associations, depth, water saturation, groundwater flow patterns and oxicity. Generally, strong weathering features with up to 1 mm thick fillings and up to several centimeters thick zones of alteration in rock of the aeration zone contrast with minor features in the phreatic zone. In the limestones and mudstones, major classes of fracture surface coatings, are taken by secondary Fe-oxides and/or clay laminae. Our results highlight the typical presence of diverse and likely dynamic reaction spaces, providing highly diverse microbial habitats. We suggest to carefully consider and explore the diversity and dynamics of mineral fractures surfaces of the aeration zone, and their contributions to element cycling and groundwater quality evolution.

 

References:

Lehmann, R., Totsche, K. U. (2020). Multi-directional flow dynamics shape groundwater quality in sloping bedrock strata. Journal of Hydrology 580. https://doi.org/10.1016/j.jhydrol.2019.124291

How to cite: Lehmann, R., Eshvara Arachchige, D., Aehnelt, M., and Totsche, K. U.: Diversity and patterns of fracture-exposed alteration features in thick recharge-area regolith, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12008, https://doi.org/10.5194/egusphere-egu23-12008, 2023.

X3.82
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EGU23-6691
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SSP3.5
|
ECS
|
Sebastian Mulder and Johannes Miocic

Fluid extraction from geological formations for purposes of subsurface utilization (e.g. hydrocarbon production, fluid storage, geothermal energy production) leads to pore pressure drop in reservoirs. The weight of the rock layers above the reservoir is partially carried by both the reservoir pore pressure and by the reservoir rock itself. Therefore, if fluids are extracted from the subsurface, the reservoir will experience an increase in compressional stress, which may lead to compaction of the reservoir rock. One type of reservoir rock that are highly susceptible to diagenetic processes and compaction due to pore pressure changes are porous sandstones. As the compressional strength of sandstone reservoirs is directly related to the petrographic composition of the rock, understanding the impact of mineralogical composition and textural relationships on reservoir compaction is key. An example of a sandstone reservoir where production related compaction occurs and is associated with surface subsidence and seismicity is the Groningen gas field, situated in the north-eastern part of the Netherlands. However, a detailed model for the reservoir petrography does not exist for the Groningen gas field. The aim of this study is to identify petrographic controls that have an impact on geomechanical behaviour of the gas field by means of optical microscopy (OM) and scanning electron microscopy (SEM) in order to develop a predictive petrographic model. Grain properties, grain displacement, grain contacts, packing texture and paragenetic sequences are studied on a selection of cored wells in the gas field. Mineralogical composition and diagenetic history is determined by OM and its subsequent impact on sandstone compaction. Different phases of clay have been identified by FESEM and EDS that surround clays and occupy the pore space, which locally inhibits cementation of quartz, feldspar or dolomite. Therefore,  the timing and extent of clay growth likely play an important role for the geomechanical stability of the reservoir sandstones. This project will contribute to our understanding of the reservoir heterogeneity of the Groningen gas field and improves our knowledge of subsurface response to subsurface utilisation.

How to cite: Mulder, S. and Miocic, J.: Reservoir compaction: What role does petrographic heterogeneity play in the Groningen Gas field?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6691, https://doi.org/10.5194/egusphere-egu23-6691, 2023.

Posters virtual: Tue, 25 Apr, 14:00–15:45 | vHall SSP/GM

Chairpersons: Patricia Roeser, Vinyet Baqués, David Parcerisa
Minerals in saline environments
vSG.14
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EGU23-16421
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SSP3.5
Amanda M. Oehlert, Alan M. Piggot, Erica P. Suosaari, Alvaro T. Palma, Luis R. Daza, Tianshu Kong, Clément G.L. Pollier, Cecilia Demergasso, Guillermo Chong, and R. Pamela Reid

Saline lakes are known to be sensitive to changes in environmental conditions on a broad temporal scale. Therefore, variations in the mineralogical, geochemical, and sedimentological characteristics of these settings have often been interpreted to reflect oscillations in climatic conditions. However, recent work has shown that microbial communities can also influence the formation of carbonate and evaporite minerals in saline lake environments, especially in the salars of South America. Here, both abiotic and organomineralization pathways can be found to exist within the same salar environments, indicating a high degree of spatial heterogeneity of mineralization processes in such settings. Thus, the drivers of the resulting mineral assemblage can be complicated to disentangle through space and time. A process-level understanding of first-order controls on mineral assemblages can provide new insights into sedimentological dynamics of salar environments.

Babel (2004) published a conceptual model based on marine-fed systems that established links between salinity and the style of gypsum mineral deposition. Based on field and laboratory analyses conducted on sediments in the Salar de Llamara, we adapted this model for a continental saline lake setting (Reid et al., 2021). In the present study, we aimed to test whether our salar-scale conceptual model was applicable more generally to continental saline lake environments. To accomplish this goal, we investigated a 15-year time series of electrical conductivity, a proxy for salinity, collected in five saline lake/wetland systems situated along the margin of the Salar de Atacama. Based on this dataset, we predicted the style and mineralogy of mineral deposition in each setting using our salar-scale conceptual model. Next, we compared our predictions with published field descriptions of the occurrences of biofilms, microbial mats, microbialites, and evaporite deposits in these lakes. Through a principal component analysis, we evaluated environmental characteristics such as electrical conductivity, pH, and dissolved oxygen as controls on mineral morphology and mineralogy.

Results indicate that salinity is a first-order control on sedimentological expression in the lakes of the Salar de Atacama, although the transition between organomineralization pathways and physicochemical precipitation may occur at different salinity values than observed in other saline lake settings. Broadly in agreement with our model from the Salar de Llamara, granular precipitates of carbonate minerals formed within microbial mats were associated with environments characterized by low salinity, while microbial mats with laminated precipitates were found in settings with moderate salinity in the Salar de Atacama. High salinity environments contained crystalline bottom types characterized by selenitic morphology. Because some South American salars have been cited as living laboratories analogous to the ancient conditions that fostered the evolution of terrestrial and Martian life, these insights into mineralization are important. Improved constraints on the controls of carbonate and evaporite mineral deposition in saline lake environments will elucidate the definition of habitable environments, and provide a testing ground for the production and preservation of chemical and morphological biosignatures through time.

How to cite: Oehlert, A. M., Piggot, A. M., Suosaari, E. P., Palma, A. T., Daza, L. R., Kong, T., Pollier, C. G. L., Demergasso, C., Chong, G., and Reid, R. P.: Environmental controls on sedimentary deposits in saline lake environments, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16421, https://doi.org/10.5194/egusphere-egu23-16421, 2023.

vSG.15
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EGU23-15767
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SSP3.5
Alan M. Piggot, R. Pamela Reid, and Amanda M. Oehlert

Although thought to be high-resolution archives of paleoenvironmental changes, subsurface sediments deposited in saline lakes situated in salar environments have rarely been studied. To address this knowledge gap, sediment cores of varying depths ranging from 0.42 to 2.2 meters were collected from four saline lakes along the eastern margin of the Salar de Atacama, Chile. Characterization included sedimentological descriptions of lithification, sedimentary structures (microbial mats and microbialites), and color, as well as discrete measurements of total organic carbon content. Radiocarbon analysis was conducted on organic matter in the sediments.  The recovered subsurface lithologies were heterogenous in color, stratigraphic features, and age dates, especially when compared between the lakes. Intervals of coarser sediment in the Soncor system lakes Chaxa, Burros Muertos and Barros Negros, appeared to be crystalline and were likely precipitated during periods characterized by higher salinity lake waters. Sediment cores collected from the Soncor system were broadly characterized by low total organic carbon content and punctuated intervals of coarse grained material deeper in the core. In the core collected from Aguas de Quelana, variations in lithology and hardgrounds were commonly observed. In concert, these results suggest that the eastern periphery of the salar was impacted by changes in salinity and water depth as these wetland area experienced changes in extent as a result of changes in wet and dry periods. Radiocarbon dating conducted on organic matter sampled at 4 intervals from each core revealed ages that were significantly older than expected, possibly due to local reservoir effects and subsurface hydrological dynamics. There were five age reversals documented in the transect of cores suggesting that the sources of radiocarbon may have changed over time. Results indicate that the geologic records of saline lake environments are as heterogeneous through time as they are in space.

How to cite: Piggot, A. M., Reid, R. P., and Oehlert, A. M.: Sedimentological characterization of geological cores from marginal lakes in the Salar de Atacama, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15767, https://doi.org/10.5194/egusphere-egu23-15767, 2023.

vSG.16
|
EGU23-3769
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SSP3.5
|
ECS
Guoding Yu, Jing Yuan, and Keyu Liu

We used the textures and chemical composition of authigenic cements in Paleogene sandstones from DN2 Gas Field of Kuqa Foreland Basin (KFB) and evidence of associated fluids from fluid inclusions and formation water measurements to infer timing of fluid migration and discuss link between fluids and tectonics. Eodiagenesis occurred with the participation of meteoric waters and connate waters. Mesodiagenesis operated in the context of high salinity fluids, which were interpreted to originate from overlying Neogene evaporite. Halite, anhydrite, glauberite, carnallite and thenardite are major minerals for the evaporite. Homogenization temperatures measured in this study and K-Ar dating performed on authigenetic illites by previous study indicate that initial migration of high salinity fluid occurred during the late Miocene (12.4–9.2 Ma). The period is consistent with the crucial phase (13–10 Ma) witnessing the rapid development of southern Tianshan and the stage when calcite and anhydrite veins formed in the studied strata. These results suggest that diagenesis related to high salinity fluids probably occurred as a response to Tianshan’s rapid uplift and related tectonic processes. The flow of high salinity fluids was probably driven by density gradient and channeled and focused by fractures formed contemporaneously.

How to cite: Yu, G., Yuan, J., and Liu, K.: Diagenesis of Paleogene sandstones and its response to tectonics in Kuqa Foreland Basin, western China, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3769, https://doi.org/10.5194/egusphere-egu23-3769, 2023.

Diagenesis and reservoir properties
vSG.17
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EGU23-1024
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SSP3.5
|
ECS
|
Taping He and Yaoqi Zhou

Abstract: In recent years, tight oil, an important unconventional oil and gas resource, has become a research hotspot of global oil and gas exploration. The typical representative of the tight oil reservoir is the Chang 6 reservoir of the Yanchang Formation in Ordos Basin. Its lithology is tight, and the pore throat is small and complex, making it difficult to describe the microscopic pore throat characteristics. Under the influence of pore throat structure, tight sandstone reservoir seepage characteristics are also more complex, which is an important factor affecting oil and gas exploration and development. Therefore, how to effectively characterize the microscopic pore throat characteristics of tight sandstone reservoirs is a key issue in the study of unconventional oil and gas resources. To clarify the characteristics and influencing factors of Chang 6 reservoir in this area, the rock mineral composition, diagenesis, and physical properties of Chang 6 tight sandstone in the Longdong area of Ordos Basin were studied utilizing rock core photos, casting thin sections, field emission scanning electron microscope, high-pressure mercury injection and constant rate mercury injection, and the influence of diagenesis on pore throat was qualitatively analyzed. The results show that the sandstone in the study area is mainly lithic feldspar sandstone and feldspar lithic sandstone, and the interstitial material is mainly clay minerals. The reservoir pore types are mainly residual intergranular pores, dissolution pores, and micropores. The pore throats are mainly distributed in the range of 0.004-100 μm, less distributed less than 0.1 μm, and more than 1 μm. The pore radius of each sample is concentrated between 60-348 μm. The throat radius of each sample is dispersed between 0.12-1.5 μm, and the roaring type is fine-micro roar type, showing strong heterogeneity. The throat mainly controls reservoir permeability, and the proportion of small throat increases with the decrease of permeability.

How to cite: He, T. and Zhou, Y.: Microscopic characteristics analysis of tight sandstone reservoir: a case study from Chang 6 sandstones of Yanchang formation in Longdong area, Ordos basin, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1024, https://doi.org/10.5194/egusphere-egu23-1024, 2023.

vSG.18
|
EGU23-1034
|
SSP3.5
|
ECS
gaixia cui, shouyu xu, and qinlian wei

Abstract:As a typical representative of unconventional gas reservoirs, tight sandstone gas reservoirs have the characteristics of large reserves and rich oil and gas resources, and have become an important exploration and development target for the government and enterprises. As one of the large oil-bearing basins in China, Ordos Basin contains many sets of oil-bearing strata, which are rich in oil and gas resources and have obvious characteristics of source-reservoir-cap assemblage. Longdong area in the southwest of the basin, under the influence of sedimentary environment and tectonic factors, continuously deposited a set of relatively complete tight thick sandstone, and the multi-layer system is generally rich in oil and gas. With the deepening of the exploration of tight sandstone oil and gas, the area has gradually become a new oil and gas development replacement area.The physical properties, lithology, pore structure and other parameters of the reservoir in the study area were studied by using casting thin section, scanning electron microscope, high pressure mercury injection, physical property analysis and gas testing data. The results show that the main rock types of He 8 member in the study area are lithic quartz sandstone ( 61.6 % ) and lithic sandstone ( 15.06 % ). The grain size of the reservoir is coarse and the sorting is medium. The pore types are mainly intragranular dissolved pores, followed by intergranular pores and intercrystalline micropores.The reservoir thickness range and lithology in the study area vary greatly and the heterogeneity is strong. Reservoir properties are controlled by sedimentary facies and diagenesis. Sedimentary facies fundamentally control the reservoir physical conditions, sand body structure has an important influence on reservoir physical properties, cutting type single sand body reservoir physical properties is relatively good, splicing type sand body reservoir physical properties, poor isolated single sand body.Compaction is the main reason for the densification of reservoir physical properties. Water mica is the primary factor for the densification of reservoir caused by cementation. The dissolution degree of reservoir is low, and the effect of improving reservoir quality is limited. The research results can provide reliable geological basis and scientific basis for further exploration and development of the lower section of He 8 in Longdong area.

How to cite: cui, G., xu, S., and wei, Q.: Influence of diagenesis on reservoir in He 8 member of the Permian Shihezi Formation in Longdong Area, Ordos Basin, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1034, https://doi.org/10.5194/egusphere-egu23-1034, 2023.

vSG.19
|
EGU23-7275
|
SSP3.5
|
ECS
Tong Jia, Liqiang Zhang, Zhenping Xu, Cai Chen, and Yiming Yan

Mechanical compaction is an important diagenesis of sandstone. Particle breakage commonly occurs during mechanical compaction, and plays a significant role in controlling the physical properties of the sandstone reservoir. However, existing experimental and numerical simulation methods have limitations in simulating mechanical compaction when considering particle breakage. In this study, a discrete element method (DEM) is purposed, which takes the maximum contact stress as the criterion of particle breakage and realizes particle breakage by particle cutting. Nine sets of numerical simulations were carried out with different breakage thresholds of reference particle (diameter = 6mm) and Weibull modulus. The parameters were calibrated according to the experimental data in published literature. On this basis, the compaction simulations of coarse sand with and without particle breakage were carried out, and the simulated vertical stress was 50Mpa. The results show that particle breakage caused by mechanical compaction significantly controls the porosity and pore structure. When the vertical stress reached 50 MPa, compared to the simulation results without considering particle breakage, the porosity difference rate caused by particle breakage was 4.63%; the radius difference rates of pores and throats were 2.78% and 6.8%, and the number difference rates of pores and throats were 4.95% and 8.74%, respectively. The simulation method can be used as an important technique in the study of sandstone diagenesis and is significant for revealing the formation process and mechanism of oil and gas reservoirs.

How to cite: Jia, T., Zhang, L., Xu, Z., Chen, C., and Yan, Y.: Effect of particle breakage caused by mechanical compaction on pore characteristics of sandstone: A DEM numerical simulation study, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7275, https://doi.org/10.5194/egusphere-egu23-7275, 2023.