Particle arrangements in clay slurries: The case against the honeycomb structure

Deirieh, Amer; Chang, Irene Y.; Whittaker, Michael; Weigand, Steven; Keane, Denis T.; Rix, James; Germaine, John T.; Joester, Derk; Flemings, Peter B.

doi:10.1016/j.clay.2017.11.010

Cited by 30 publications

(13 citation statements)

References 25 publications

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“…Their random orientation and uniform distribution are identical to the fabric of greenalite in deeper-water BIFs (Rasmussen et al, 2015a(Rasmussen et al, , 2017. This fabric closely resembles the texture of clay slurries (Deirieh et al, 2018) and modern marine muds (Bennett et al, 1981;Kase et al, 2016), supporting a depositional origin for the greenalite particles (Rasmussen et al, 2019). The preservation of depositional textures in parts of the chert implies that early diagenetic silica cementation "froze" the original fabric of the chemical muds, minimizing the effects of diagenesis, burial-related compaction, and metamorphism.…”

Section: Petrography Of Greenalite-rich Intraclastic Chert Bedsmentioning

confidence: 71%

Evidence for anoxic shallow oceans at 2.45 Ga: Implications for the rise of oxygenic photosynthesis

Rasmussen

Muhling

Tosca

et al. 2019

Geology

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Geochemical proxies indicate that atmospheric oxygen levels were <10 -5 times present atmospheric levels (10 -5 × PAL) until the start of the Great Oxidation Event (GOE; 2.33 Ga). However, trace metal and isotopic data from sedimentary rocks have been interpreted to reflect the presence of oxygenated surface oceans ≥2.5 b.y. ago, implying decoupling of the atmosphere and shallow marine systems. Evidence for oxygen in shallow oceans has fueled the idea that oxygenic photosynthesis evolved long before the GOE and that oxygen did not accumulate in the atmosphere because it was scavenged by reductants such as dissolved Fe 2+ , a process thought by some to have formed banded iron formations (BIFs). Here we present high-resolution microscopy showing that 2.45 Ga shallow-water BIFs were deposited as ferrous iron-rich muds dominantly composed of greenalite; these muds were rapidly cemented by silica on the seafloor, and subsequently eroded and redeposited as intraformational chert clasts. Our experimental results and kinetic models show that the accumulation of greenalite required seawater oxygen concentrations <10 -6 × PAL on the shallow shelf. We infer that oxygen levels of the surface oceans and atmosphere were not decoupled 2.45 b.y. ago, but that both were exceedingly low (<10 -5 × PAL). Our findings support the hypothesis that oxygenic photosynthesis evolved shortly before atmospheric oxygenation and was a direct cause of the GOE.

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Section: Petrography Of Greenalite-rich Intraclastic Chert Bedsmentioning

confidence: 71%

Evidence for anoxic shallow oceans at 2.45 Ga: Implications for the rise of oxygenic photosynthesis

Rasmussen

Muhling

Tosca

et al. 2019

Geology

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“…Therefore, the pore size distribution extracted on the basis of MIP or SEM analysis of plunge frozen samples very likely does not describe the native state of the sample. High‐pressure freezing, on the other hand, was shown by the same authors (Deirieh, Chang, et al, ) to effectively suppress ice crystal formation and most likely preserve the native microstructure in clay slurries with high water content (100% to 120% w / w ).…”

Section: Introductionmentioning

confidence: 95%

“…Prior work further assumes that plunge freezing preserves the native microstructure of mudrocks. Researchers use plunge freezing as an alternative to sample drying to avoid alteration of the microstructure due to shrinkage (see Deirieh, Chang, et al, for more details). In plunge freezing, samples are immersed in a liquid cryogen followed by either freeze drying and imaging in a conventional SEM or direct imaging by cryoSEM.…”

Section: Introductionmentioning

confidence: 99%

“…For instance, Delage and Lefebvre () showed in their landmark study that the volume of intruded mercury in plunge‐frozen Champlain clay samples is similar to the natural water content of sister samples and published SEM images of plunge‐frozen samples that revealed a highly porous microstructure resembling a honeycomb. However, Deirieh, Chang, et al () recently demonstrated that plunge freezing of samples with a similar water content does not preserve the microstructure. In fact, the well‐known honeycomb structure observed in plunge‐frozen clay slurries is an artifact that results from the growth of ice crystals.…”

Section: Introductionmentioning

confidence: 99%

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Impact of Drying and Effective Stresses on the Pore Space and Microstructure of Mudrocks

et al. 2019

Self Cite

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The evolution of the pore space of mudrocks induced by drying shrinkage and effective stresses is of importance to several areas of research. Drying is a prerequisite for most mudrock characterization methods, while effective stresses have a direct impact on mudrocks properties such as permeability, compressibility, and strength. Mercury porosimetry intrusion has been widely utilized to show that drying shrinkage and effective stresses lead to the collapse of large pores only (~> 50 nm), while small pores (~< 50 nm) remain unaffected. However, the validity of mercury porosimetry intrusion-derived pore size distributions is greatly doubted in the literature due to the fact that most pores in mudrocks are not directly accessible to the surrounding mercury. This study follows a different approach by utilizing a suite of methods including imaging by transmission electron microscopy and scanning electron microscopy at cryogenic temperature after high-pressure freezing (cryoSEM), and gravimetric porosity measurements to investigate the influence of volumetric changes on the pore space of mudrocks. Contrary to previously published results, we show that volumetric changes induced by drying and effective stresses lead to the collapse of pores of all sizes. Furthermore, we show that porosity measured from SEM images is dependent on SEM resolution and reveals only a fraction of the actual porosity. These results provide valuable insights used to interpret the results of characterization methods requiring drying and modeling of effective stress influence on the properties of mudrocks.

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“…These studies concluded that traditional sample preparation techniques (e.g. plunge freezing) do affect the clay structure significantly [9,10]. Furthermore, the study of the evolution of the micro-structural properties of clays is complicated by the need to take samples at several stages in the process, which requires a series of tests terminated at different stages for subsequent sample collection.…”

Section: Introductionmentioning

confidence: 99%

Monitoring of the nano-structure response of natural clay under mechanical perturbation using small angle X-ray scattering and digital image correlation

et al. 2019

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This paper introduces a new experimental method to monitor the evolving intra-particle, nanometre-scale response during hydro-mechanical tests on undisturbed wet clay samples using small angle X-ray scattering (SAXS). The method uses a newly developed miniature plane-strain one-dimensional compression cell that facilitates simultaneous full-field surface displacement measurements using digital image correlation and SAXS measurements. The 60-120 s acquisition times offered by SAXS at synchrotron facilities are beneficial to study time-dependent mechanisms in clays. The experimental results presented indicate that, for the natural sensitive clay tested in this work, no significant structural changes occur at the intra-particle scale during loading, even when large strains are measured at the macro-scale. In addition, changes that are observed at this scale occur after the end of perturbation, i.e. the creation of new intra-particle structures. Further information is obtained on the orientation evolution of the fabric by the comparative analysis of the individual mineral component response.

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Particle arrangements in clay slurries: The case against the honeycomb structure

Cited by 30 publications

References 25 publications

Evidence for anoxic shallow oceans at 2.45 Ga: Implications for the rise of oxygenic photosynthesis

Evidence for anoxic shallow oceans at 2.45 Ga: Implications for the rise of oxygenic photosynthesis

Impact of Drying and Effective Stresses on the Pore Space and Microstructure of Mudrocks

Monitoring of the nano-structure response of natural clay under mechanical perturbation using small angle X-ray scattering and digital image correlation

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