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Through the analyses of recovered pottery, this study explores the social dimension of an ancestor cult developed at the Petit-Chasseur megalithic necropolis (Upper Rhône Valley, Switzerland) during the Early Bronze Age (2200–1600 BC). The jar votive offerings and domestic pottery from settlement sites were characterized using a range of spectroscopic and microscopic techniques. Acquired archaeometric data allowed identification of six ceramic fabrics and two types of clay substrate—illite- and muscovite-based—which were used in pottery production. The present article discusses the pottery composition in the light of natural resources available in the region, thus shedding light on raw material choices and paste preparation recipes. The Early Bronze Age people that lived in the Upper Rhône Valley seem to have shared a common ceramic tradition, partly inherited from the previous Bell Beaker populations. The compositional correspondence between the jar offerings and domestic pottery revealed that the majority of the known Early Bronze Age groups partook in cultic activities at the Petit-Chasseur megalithic necropolis.

This work aims to unveil the origin, geodynamic significance, and diagenetic history of pyroclastites and associated chert documented within the Upper Anisian volcanosedimentary succession of the Ivanščica Mt. in Central Europe. An abundance of pyroclastic material points to polyphase volcanic activity and deep‐water sedimentation along the rim of an oceanic realm. Radiolarian‐based dating revealed Illyrian age of chert intercalated with pyroclastites. The latter are largely vitro‐crystalloclastic and were emplaced as airborne tuff. The crystalloclasts of sanidine, plagioclase, altered pyroxene, and amphibole are principal tuff constituents merged in the altered glassy matrix consisted of palagonite, clay minerals, and calcite. Variations in alteration assemblages reflect an extensive in situ eogenesis in an open hydrologic system that gradually evolved toward a restricted fluid percolation environment. Mineralogy, chemistry, and occurrence of andesitic tuff clearly denote an explosive volcanic activity formed at the top of suprasubduction zone. Such scenario presumes a complex genesis outlined in following steps: (a) partial melting and dehydration of down‐going Palaeotethyan slab which gave rise to the subduction‐related magmatism {; ; LILE, Th, and LREE [(La/Lu)cn = 6.51−9.42] enrichment ; negative anomalies of Nb‐Ta, P, and Ti [e.g., (Nb/La)n = 0.31−0.44]}; ; ; (b) magma contamination via interaction with continental crust during magma uplift along tectonically weakened zones of upper crust [positive Pb spikes, negative εNd (−4.18 to −4.44), and 147Sm/144Nd ≤ 0.113175]. This is in favour of geodynamic evolution that hypothesizes the existence of an active, ensialic, and mature volcanic arc developed along the southern active continental margins of Euramerica (Laurussia) during Late Anisian subduction of Palaeotethyan lithosphere.

The use of mineral diagenetic indices and organic matter maturity is useful for reconstructing the evolution of sedimentary basins and critical assessments for potential source rocks for petroleum exploration. In this study, the relationship of clay mineral diagenesis and organic matter thermal indices (Rock-Eval Tmax) and calculated vitrinite reflectance (%Ro) were used to constrain the maximum burial depths and temperatures of three distinct intervals within the northern Permian Basin, USA. X-ray diffraction of clay fractions (&lt, 2 &micro, m) consists of illite, chlorite, and illite-smectite intermediates. Primary clay mineral diagenetic changes progressively increase in ordering from R0 to R1 I-S between 2359.5 and 2485.9 m and the appearance of chlorite at 2338.7 m. Rock-Eval pyrolysis data show 0 to 14 wt% TOC, HI values of 40 to 520 mgHC/g TOC, and S2 values of 0 to 62 mg HC/g, with primarily type II kerogen with calculated %Ro within the early to peak oil maturation window. Evaluation of the potential for oil generation is relatively good throughout the Tonya 401 and JP Chilton wells. Organic maturation indices (Tmax, %Ro) and peak burial temperatures correlate well with clay mineral diagenesis (R0&ndash, R1 I-S), indicating that maximum burial depths and temperatures were between 2.5 and 4 km and &lt, 100 &deg, C and 140 &deg, C, respectively. Additionally, the use of clay mineral-derived temperatures provides insight into discrepancies between several calculated %Ro equations and thus should be further investigated for use in the Permian Basin. Accordingly, these findings show that clay mineral diagenesis, combined with other paleothermal proxies, can considerably improve the understanding of the complex burial history of the Permian Basin in the context of the evolution of the southern margin of Laurentia.

The verdine facies clay assemblages are regularly encountered in shallow marine sediments of equatorial latitudes where Fe of terrigenous origin is readily available. There, the 7 A Fe-rich green clay (odinite) of syn-sedimentary origin commonly occurs. Previous findings suggested that odinite serves as a precursor of diagenetic chlorite whose importance in porosity conservation has been widely acknowledged. The investigation of Fe-rich clays is, therefore, helpful to constrain the specific conditions and mechanisms, which give rise to chlorite growth, thus illuminating the history of early burial. In this contribution, we studied Cretaceous sediments from the Gabon coast where multiple sedimentary basins came into existence prior, during and after the opening of the South Atlantic. Analyzed core is siliciclastic and petroleum bearing stemming from the fluvio-lacustrine-deltaic environment recovered from depths of ∼1500 m TVD. Electron micro-beam investigation coupled with X-ray diffraction on the clay fraction and spectra fitting revealed odinite, interstratified odinite-chlorite (O-C), and to a lesser extent, illite-chlorite-smectite (I-C-S) and illite-smectite occur as grain coatings and pore-filling phases with a characteristic honeycomb texture. Embryonic chlorite emerges at the contact of odinite and O-C flakes as a particulate authigenic mineralization. Formed from aluminosilicate and Fe-oxyhydroxide debris at sediment-water interface, odinite becomes intrinsically unstable, possibly due to the activity of Fe-reducing bacteria or decaying organic matter creating a prevalently reducing environment that promotes Fe reduction. Such condition facilitated a two-step chlorite growth, which first included a partial chloritization of odinite through the in situ solid-state transformation of 7 A to 14 A layers. Then, with increasing burial, at peak diagenetic conditions (50 °C, ∼1.5 km depth), odinite and O-C both recrystallized to form eogenetic chlorite most likely following the Ostwald ripening mechanism.

Precambrian (1.4 to 1.5 Ga) granite and rhyolite in the St. Francois Mountains at the northeast corner of the Ozark Plateau in Missouri has been altered down to a depth up to 8 meters below the Great Unconformity (the contact between Paleozoic sedimentary rock and underlying Precambrian). Petrographic, geochemical, and mineralogic data indicate that at least two events generated this alteration: 1) surficial weathering due to subaerial exposure of the granite before Cambrian burial—this material is preserved as a paleosol; and 2) alteration due to reaction with basinal fluids channeled along the unconformity from nearby sedimentary basins long after burial by Paleozoic strata. To assess the variation between surficial weathering and basinal fluid alteration, we measured and sampled for petrologic, geochemical, and mineralogic data in the rock at and just below the Great Unconformity at three paleoelevations. Whole-rock geochemical oxide and X-ray diffraction data indicate that K-metasomatism and highly crystalline illite occurred in each profile. The K increase reflects crystallization of authigenic feldspar and illite from basinal fluids that were channeled along the Great Unconformity during younger Paleozoic fluid-flow events. Each profile also exhibits an upward increase in altered feldspar crystals and highly crystalline kaolinite, and an upward decrease in Ca and Na. Such changes reflect soil formation due to reaction with meteoric water before Cambrian burial, indicating that the altered granite was a paleosol before Paleozoic basinal fluid-flow events. Notably, the paleosol at the highest paleoelevation displays the least amount of paleoweathering and the paleosol at the lowest displays the greatest amount of paleoweathering. These results demonstrate that not only can characteristics of the paleosol just below the Great Unconformity be recognized in the St. Francois Mountains, despite subsequent alteration, but also it is possible to detect variations in soil thickness that were controlled by slope steepness and, therefore, water availability and/or soil creep or failure. This spatial relationship is compatible with studies of modern soils which indicate that soil character varies with position on a slope.

The Anadarko Basin of Oklahoma represents a major Paleozoic depocenter that existed along the rifted margins of southwestern Laurentia. In its infancy it accumulated a thick series of Cambrian through Mississippian detritus while further subsidence caused by inversion of the Cambrian Southern Oklahoma Aulacogen resulted in voluminous Pennsylvanian to Permian sediment. This contribution reports new data on K-Ar ages and trace-element geochemistry of detrital illite from middle and upper Pennsylvanian shale used to reconstruct sediment origins at the peak period of subsidence of the Anadarko Basin. X-ray diffraction was used to unveil mineral compositions and abundances of illite polytypes in two size fractions of separated illite (˂1 and 2-1 μm). K-Ar isotopic analyses were completed for both fine fractions, while the laser ablation inductively coupled plasma mass spectrometry was done for the latter. All illite separates consisted of mixtures of authigenic (1Md) and detrital (2M1) illite. The Illite Age Analyses showed that the detrital age of Desmoinesian (Moscovian) shale is the late Ediacaran (584 Ma), while the age of Missourian (Kasimovian) shale is the middle Cambrian (512.5 Ma). Trace-element abundances of all analyzed illite, irrespectively of stratigraphic age, are consistent with those of mica from metamorphic rocks. Based on illite detrital age and geochemistry it was inferred that Desmoinesian (Moscovian) shale represents a mixture of Neoproterozoic and Cambrian detritus sourced locally, whereas Missourian (Kasimovian) shale records a provenance shift toward more distal easterly sources from the Ouachita-(Marathon) foreland. This study has proposed a sediment source transition between the middle and upper Pennsylvanian that likely reflected major changes in the basin paleogeography and progressive development of the east-west (transcontinental) fluvial systems.

Highlights • Coupled geomicrobiology and geomechanics to investigate alterations in shales. • Microbial process can alter the mechanics, mineralogy, and microstructure of shales. • Biogeomechanical alterations reduced permeability by 93% and porosity by 38%. • Microfractures in shales can be sealed during biogeomechanical alterations. • Biogeomechanical alterations can enhance CO2 storage security and caprock integrity. Shales have been a major focus of the energy industry over the past few decades. Recently, there is a paradigm shift in the energy industry to low-carbon solutions, such as carbon capture and storage (CCS), to mitigate global warming caused by carbon footprint. The problem of long-term safe and efficient geological CO2 storage (GCS) and caprock integrity are some of the major challenges impeding large-scale CCS application. Here, we investigated how localized and bulk biogeomechanical alterations could potentially impact caprock integrity and CO2 storage in depleted shale reservoirs. We cultivated the shale core samples (containing both artificial-induced and pre-existing natural fractures) with a cultured microbial solution at specific temperature, time, and growth conditions. Subsequently, we obtain the properties of the fractured shale rock samples impacted by this microbial process. We investigate the impact of the mechanical responses due to the microbial process, on the long-term integrity and storage potentials of CO2 in shale reservoirs. Our results suggest that in Eagle Ford, Marcellus, and Niobrara shale formations, microbially-altered local and bulk mechanical properties can enhance the long-term caprock integrity and CO2 storage security by: (1.) Increasing the localized (+19% unconfined compressive strength, −20% Poisson’s ratio, +35% fracture toughness) and bulk (+50% unconfined compressive strength, −13% Poisson’s ratio) mechanical integrity; (2.) Decreasing permeability (−93%) and porosity (−38%); (3.) Altering the clay mineral content (−56%), calcite content (+21%), and morphology; (4.) Occluding microfractures; and (5.) Mitigating any potential leakage to the atmosphere through the caprock. This study considers the heterogeneity of shales, and provide valuable insights and viable assessment in solving the long-term GCS application in depleted hydrocarbon reservoirs.

The Gabon coastal region located along the western African margin hosts several sedimentary basins that developed prior, during and after the opening of the South Atlantic Ocean. A range of diagenetic processes controlled the distribution of clay paragenesis shown to be of high importance for the understanding of the basin's burial history and geotectonic development. Materials acquired for this study stem from the siliciclastic fluvio-lacustrine-deltaic, petroleum bearing, Early Cretaceous Dentale and Gamba formations cored by two respective wells at depths of ~ 1500 m. Sampled materials were analysed by X-ray diffraction, automated electron microscopy, and inductively coupled plasma mass spectrometry in order to reconstruct eogenetic and mesogenetic variations directing the formation of clay assemblages in the basin. The clay contents in both cores consist of authigenic mixed-layer minerals like illite-smectite, chlorite-smectite and berthierine-chlorite, and some minor detrital illite/mica and chlorite. I-Sm and C-Sm phase chemistry implied that the original dioctahedral (montmorillonite to beidellite) and trioctahedral (saponite) smectite precursors formed out of acid volcanic feedstock during eogenesis. Different magmatic fractionation degrees, from rhyodacite to trachyandesite, reflected in the uniform REE curves of volcanic glass conform to an active geotectonic development of the Cretaceous margins of Africa. Mesogenesis led to the decrease of smectite and formation of mixed-layered phases; I-Sm composition showed maximal burial depths of sediments to be ~ 1000 m and ~ 500 m deeper than today for Gamba and Dentale sediments, respectively. Besides, temperature, a major role in the formation of mixed-layer minerals had the porosity of sediments and geochemistry of smectitic precursors. Thus, Fe-Mg smectite showed higher thermal stability and lower rates of transformations in non-expanding clays during burial compared to Al-rich smectite. Different burial histories of sediments from the two cores can be attributed to rift-related normal faulting and subsequent differential denudation.

In this contribution, new data concerning the distribution of vascular flora alien to Italy are presented. It includes new records, confirmations, exclusions, and status changes for Italy or for Italian administrative regions of taxa in the genera Bunias, Calocedrus, Calycanthus, Celosia, Clerodendrum, Convolvulus, Crassula, Cyclamen, Datura, Dicliptera, Eragrostis, Erigeron, Gamochaeta, Gazania, Impatiens, Kolkwitzia, Leucaena, Ludwigia, Medicago, Muscari, Nigella, Oenothera, Opuntia, Paulownia, Petroselinum, Phyllostachys, Physalis, Pseudosasa, Quercus, Reynoutria, Roldana, Saccharum, Sedum, Semiarundinaria, Senecio, Sisyrinchium, Solanum, Sporobolus, Tulipa, Vachellia, Verbena, and Youngia. Nomenclatural and distribution updates published elsewhere are provided as Suppl. material 1.

Pottery is of high importance in archaeology because once produced it is virtually indestructible and is often found in great quantities at archaeological sites. Thus, it readily serves as a chronological marker allowing scholars to investigate important aspects of ancient populations such as cultural identity, economy, religious beliefs, technological know‐ how, object circulation, and movements of people. The last few decades saw the application of various analytical techniques into the study of archaeological ceramics, which has continuously enhanced the accuracy of material characterization. Hence, the use of natural sciences in archaeology made an impressive research impact serving nowadays as invaluable tool in the study of specific traits of past societies. Current research on the pottery from the Petit‐Chasseur site allowed one to address the problematics of cultural identity of prehistoric societies that had erected the megalithic funerary monuments during the 3rd millennium BC. The cemetery is located in the middle of the Upper Rhône valley that was formed by the glacial and riverine erosion in the Western Alps. To some extent, the Rhône river separates the Helvetic and Penninic nappes dividing the valley in two. Peculiar lithology typical for the above‐mentioned tectonic units has likely generated clay‐rich sediments whose mineral composition may significantly differ. In this contribution we present a variety of ceramic compositions of the pottery from the Petit‐Chasseur site, putting an accent to the make‐up of clayey matrix. Its characterization, performed by X‐ray diffraction and Scanning electron microscopy, revealed the use of different clay‐rich sources to produce vessels which, in a way, have analogue typological and stylistic features. Moreover, the pottery that belongs to particular material culture and that was recovered from the same collective grave was shown to have been manufactured using various clay raw‐materials. In brief, the evidences from the Petit‐Chasseur cemetery permit a question to be posed on whether the utilization of diverse plastic materials was a deliberate economic and/or social choice or is rather related to the raw‐material availability in the Upper Rhône valley. The study of ceramic grave goods from the Petit‐Chasseur site revealed its potential in identifying and defining the cultural identity of prehistoric communities that dwelled in this part of Switzerland during the 3rd millennium BC.

Clay phases numbering odinite‐like minerals (OLM), chlorite, illite, and smectite along with interstratified odinite‐chlorite (O‐C), illite‐chlorite‐smectite (I‐C‐S), and illite‐smectite are ubiquitous in sediments of the Gamba Formation. The formation itself stems from the Gabon coast of the western African margin where multiple Cretaceous sedimentary basins came into existence prior, during and after the opening of the South Atlantic Ocean. Analyzed core material is siliciclastic and petroleum bearing, originating from the fluvio‐ lacustrine‐deltaic environment drilled at depths of ~1500 m. The OLM and O‐C occur as grain coatings but are more common as pore fillings rendering the characteristic honeycomb texture. Chlorite emerges at the contact of OLM and O‐C flakes as a particulate authigenic mineralization. This study aims to find the mineralogical and geochemical clues to explain diagenetic changes that enabled nucleation of low‐grade diagenetic chlorite in the verdine sedimentary facies. Inferring from a detailed scanning electron microscopy and X‐ray diffraction with spectra modelling, OLM appears to form in shallowly buried sediment from the alumosilicate and Fe‐oxyhydroxide debris brought as a riverine influx. Peculiar geochemical conditions induced a partial chloritization of OLM at practically syn‐sedimentary conditions through the solid‐state transformation of 7 Å to 14 Å layers. With increasing burial, at peak diagenetic conditions (50°C, ~1.5 km depth), the OLM and O‐C both recrystallized to form the eogenetic (monocomponent) chlorite most likely following the Ostwald ripening mechanism. Trioctahedral smectite in the upper part of the Gamba Formation also served as source for chloritization, where dissolution must have been complete resulting in a series of I‐S‐C intermediates. However, the I‐S‐C intermediates did not reach the composition of monocomponent chlorite.

The megalithic cemetery of Petit-Chasseur (Sion, Western Switzerland) is one of the most important prehistoric funerary contexts of Central Europe. The site has been used throughout the Final Neolithic (2800-2450 BC), the Bell Beaker period (2450-2200 BC), and early Bronze Age (2200-1600 BC). The study and classification of the pottery played a key role in defining the cultural identity of prehistoric communities, but, as of yet, did not allow to establish a link with the known settlement sites. In this contribution, we present the results of the multi-element chemical analysis of both Petit-Chasseur pottery and geological materials. Sediment samples were collected from different areas of the Upper Rhône valley, putting an accent to the locations in the vicinity of the known settlement sites. Raw geochemical data obtained by means of the Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and Laser Ablation ICP-MS were subjected to multivariate statistical techniques including the Principal Component Analysis and Linear Discriminant Analysis in order to define possible sources of clayey raw materials. The diverse elemental concentration patterns revealed the use of different types of clay sources in the pottery production taking into account not only a diachronic point of view but also a synchronic one. The conclusion thus emerges pointing out the idea of people coming from different parts of the Upper Rhône valley to gather at the site of Petit-Chasseur, which suggests its role as a political and ceremonial center in addition to the burial function it had as a megalithic cemetery. An in-depth ceramic study is therefore proven to be necessary to thoroughly reconstruct the history of the Petit-Chasseur site adding to our understanding of its significance for prehistoric communities.

The Glasford structure in Illinois (USA) was recognized as a buried impact crater in the early 1960s but has never been reassessed in light of recent advances in planetary science. Here, we document shatter cones and previously unknown quartz microdeformation features that support an impact origin for the Glasford structure. We identify the 4 km wide structure as a complex buried impact crater and describe syn- and postimpact deposits from its annular trough. We have informally designated these deposits as the Kingston Mines unit (KM). The fossils and sedimentology of the KM indicate a marine depositional setting. The various intervals within the KM constitute a succession of breccia, carbonate, sandstone, and shale similar to marine sedimentary successions preserved in other craters. Graptolite specimens retrieved from the KM place the time of deposition at approximately 455 2 Ma (Late Ordovician, Sandbian). This age determination suggests a possible link between the Glasford impact and the Ordovician meteorite shower, an increase in the rate of terrestrial meteorite impacts attributed to the breakup of the L-chondrite parent body in the main asteroid belt

Paleozoic shale successions of Anadarko Basin in the central United States have historically been known as major hydrocarbon sources. Lately, their importance arises from the perspective of unconventional reservoir exploitation. Despite the better understanding of shale diagenesis and the agreement on many aspects of the transition of smectite to illite through a series of mixed-layer illite-smectite (I-S), the origin and composition of the material, and exact processes related to mechanisms of illitization remain controversial in shale. While nowadays most of researchers consider shales to be consisted of “illitic” clays, which comprises both the non-expandable 10Å layers as well as mixed I-S, some authors exclude the presence of smectite in mature shale attributing its appearance in XRD patterns by peculiar diffraction artefacts. The question of the nature of shaley matrix influences greatly rocks’ physicochemical parameters such as porosity/permeability and brittleness, which is essential for amelioration of the unconventional reservoir exploitation practices. In order to shed more light on crystal growth processes and clay mineral composition of shale matrix, an integrated study using different methodology was designed. Samples of Paleozoic shale of the Anadarko Basin were cored at depths from 2000 to 4200 m. Based on comparative mineralogical data - X-ray diffraction, electron microscopy and Infrared Attenuated Total Reflectance - and K-Ar age investigation performed on four illite fractions (2-1 μm

Paleozoic successions of Anadarko Basin in the central United States are largely composed of shale intervals and have historically been known as major hydrocarbon sources. Lately their importance arises from the perspective of unconventional reservoir exploitation. Clay mineral evolution in these sediments and, in particular, the processes related to illite growth have, however, remained relatively under‐ researched. K‐Ar data on illite has been proven to be very useful for the understanding of illitization processes in shale. Still, dating of mudstone by the K‐Ar method may reveal a range of ages that are older, younger or coincide with stratigraphic ages. Illite particle nucleation‐ growth process acts as a major control on K‐Ar ages that occasionally may be significantly different than expected. This research examines Paleozoic shale of the Anadarko Basin cored at depths from 2980 to 3160 m. Based on comparative mineralogical data, X‐ray diffraction (XRD) and electron microscopy (SEM‐EDS) performed on three illite fractions (

The Avalon Zone hosts well-preserved examples of high- and low-sulfidation epithermal Au-Ag mineralization and associated phyllosilicate alteration. Using examples from the Hope Brook and Hickey's Pond high-sulfidation systems (HSS) and the Heritage low-sulfidation system (LSS), this study presents new data on the mineralogical and chemical characterization of phyllosilicates associated with epithermal Au-Ag deposits. Electron probe microanalysis and X-ray diffraction studies revealed that the HSS examples contain Fe muscovite ((K0.62–0.79Na0.10–0.37Ca0.00–0.01)Al1.31–1.72(Mg0.01–0.08Fe0.05–0.19)(Al1.00–1.24Si2.76–3.00O10)(OH)2), paragonite ((K0.05–0.30Na0.78–1.02Ca0.00–0.01)Al1.66–1.84(Mg0.00–0.01Fe0.02–0.04)(Al1.01–1.11Si2.89–2.99O10)(OH)2), Al clinochlore ((Mg2.42–2.65Fe1.62–1.78)(Si2.57–2.69Al1.31–1.43O10)(OH)8), pyrophyllite, kaolin minerals, illite-smectite (I-Sme) and chlorite-smectite (C-Sme). Conversely, the LSS examples contain Fe-Mg muscovite ((K0.44–0.76Na0.00–0.02Ca0.00–0.01)Al1.55–1.82(Mg0.17–0.31Fe0.05–0.12)(Al0.55–0.71Si3.29–3.45O10)(OH)2), Al clinochlore ((Mg2.17–2.56Fe1.59–2.01)(Si2.71–2.92Al1.08–1.29O10)(OH)8), and I-Sme and C-Sme intermediates. Chlorite geothermometry indicated that HSS and LSS assemblages crystallized at average temperatures of 261 °C and 145 °C, respectively. Mica and chlorite from HSS and LSS are defined by Tschermak substitution and high-temperature polytypism (2M1 and IIb, respectively). In the HSS examples, one or more pulses of hot, acidic fluid reacted with host rocks generating an envelope of advanced argillic alteration (Fe-Ms, Kln, Pg, Prl) around a vuggy silica core. This is bounded by a zone of argillic alteration (Fe-Ms, Kln), with sericitic/chloritic alterations (Fe-Ms, Al-Clc) developed in distal parts of the systems. In the LSS, near-neutral hydrothermal fluids led to the formation of broad phyllic/chloritic zones (Fe-Mg Ms and Al-Clc). A low temperature overprint with 1M mica, Ib clinochlore ((Mg2.48–2.74Fe1.58–1.73)(Si3.05–3.15Al0.85–0.95O10)(OH)8), kaolinite and Sme-poor I-Sme and C-Sme is attributed to late waning stage hydrothermal activity and/or weathering. A close paragenetic link was established between Fe-Mg muscovite and Ag mineralization at Heritage, as well as between Fe-Mg muscovite and bladed calcite, suggesting boiling as the precipitation mechanism. The present study provides guidance on how phyllosilicate assemblages have the potential to discern HSS versus LSS mineralization during early prospection in terranes with limited exposure, and to contribute to the reconstruction of their hydrothermal record.

Miocene tuffs preserved in argillaceous sediment interbedded with lacustrine successions are commonly encountered throughout the Dinarides Lake System (DLS) in south-eastern Europe. In this contribution the volcanic glass degradation and co-genetic Mn-Fe precipitation were studied in a 14.68 Ma felsic tuff from DLS Livno-Tomislavgrad Basin. Microbial activity has been involved in both reactions thus adding the interest of revealing effects of biotic and abiotic processes taking place during tuff eogenesis. X-ray diffraction and electron microbeam analysis with energy-dispersive X-ray spectroscopy revealed the pitting or granular structures developed at glass rims along with smectite flakes protruding from a degrading glass. Mn-Fe mineralization emerges in the form of Mn-Fe coatings, an initial step to micronodule formation, where traces of biogenetic influence included a high content of phases rich in structural Mn (IV) (i.e., ranci&eacute, ite and jacobsite) and presence of microbial microfossils. Co-genetic ties between glass degradation and Mn-Fe precipitation were established through the report of dioctahedral smectite formed out of altered glass, which then served as nuclei of the ongoing biotic and abiotic Mn-Fe mineralization. These processes manifest on a continuous involvement of microbial life in the course of eogenesis of pyroclastic material in lacustrine environments.

In the southern U.S. states, expansive soils are frequently encountered, presenting an important hazard in geotechnical engineering. This research relies on mineralogical and geochemical clues to explain the swelling behavior of smectite-rich, high-plasticity soils, documented in a series of geomechanical swelling tests that were performed on the soils stabilized with the metakaolin (MKG) and fly ash (FAG) based geopolymers. These geopolymers were mixed with the soil at several concentration levels. The lowest swelling percentage was shown to correspond to the sample stabilized with 12% FAG and was attributed to the neoformation of calcium silicate hydrates that acted as a cementitious material, preventing the soil from expanding by occupying the pore space, thus binding the clay particles together. Conversely, the 12% MKG-stabilized soil exhibited enormous expansion, which was explained by montmorillonite swelling to the point that it gradually began to lose its structural periodicity. The relatively high abundance of the newly formed feldspathoids in MKG-treated samples is believed to have greatly contributed to the overall soil expansion. Finally, the cation exchange capacity tests showed that the percentage of Na+ and Ca2+, as well as the pH value, exercised strong control on the swelling behavior of smectitic soils.

Perialpine areas of central Europe have undergone significant changes following the last Alpine glaciation and especially through the Holocene time. This study relies on geochronological, mineralogical and geochemical clues to explain the formation and paleoenvironmental significance of Fe Mn nodules reported from the young soils (~4.5 ka BCE) of Geneva Basin in western Switzerland. Having on average 2 mm in diameter, the nodules usually possess an onion-like and quasi-layered internal architecture defined by selective enrichments in Fe and Mn. Fe-rich mica is largely present in soil matrix and has served as a main source of Fe and Mn. Susceptible to favourable Eh-pH conditions several steps in mica weathering were recognised leading to the formation of nodules – vermiculitization, microcracking, Fe Mn segregation and re-precipitation. Mineral alterations were boosted by long periods of summer warm climate during Boreal and Atlantic times as suggested by the increasing illite-smectite content and a disappearance of hydroxyl-interlayered clays from analysed colluvium. Moreover, archaeological ages and radiocarbon dating of charcoal yielded coherent Fe Mn encrustation ages (4.8–4.3 ka BCE and 4.5–4.4 ka BCE, respectively) that coincide with the Holocene temperature maximum (~4 ka BCE) in Central Europe. Terrain morphology that led to better water retention formed earlier than ~8 ka BCE ago, during undefined Late Glacial time, promoting seasonal changes in redox conditions, thus facilitating the mobilization, distribution and re-precipitation of Fe and Mn. Established conditions lasted until Late Neolithic (3.4–2.2 ka BCE) when different agricultural practices changed favourable hydromorphic environment effectively putting an end to further nodule formation.