EVIDENCE OF PALAEOSTRUCTURES RELATED TO FREEZING THROUGH SOIL MICROMORPHOLOGY IN LAZARET CAVE, NICE (FRANCE), 1995, Laafar S. , Rousseau L. , Delumley H. ,

In the Lazaret cave (Nice), the study of soil micromorphology has revealed palaeostructures with a microaggregate facies as well as a round or flat morphology. Observations were performed in the middle of stratigraphic layer C of the archaeological filling which probably belongs to isotopic stage 6. The specific characteristics of these palaeostructures are compared to those observed in certain recent sites which underwent a cold and wet climate. From this comparison, it can be inferred that layer C might have been formed under similar climatic conditions

TECTONIC AND PALEOCLIMATIC SIGNIFICANCE OF A PROMINENT UPPER PENNSYLVANIAN (VIRGILIAN STEPHANIAN) WEATHERING PROFILE, IOWA AND NEBRASKA, USA, 1995, Joeckel R. M. ,

A Virgilian (Stephanian) weathering profile up to 4 m deep, containing a paleosol (basal Rakes Creek paleosol) in the basal mudstone of the Rakes Creek Member and karstified marine sediments in the Ost, Kenosha, and Avoca members below, is restricted to southeastern Nebraska (specifically the Weeping Water Valley) and the Missouri River Valley bluffs of adjacent easternmost Iowa. This weathering profile, informally referred to as the Weeping Water weathering profile, disappears farther eastward into the shallow Forest City Basin in southwestern Iowa. Weeping Water weathering profile features are prominent in comparison to other Midcontinent Pennsylvanian subaerial exposure surfaces, indicating prolonged subaerial exposure, relatively high elevation, and a marked drop in water table along the Nemaha Uplift in southeastern Nebraska. Eastward, on the margin of the Forest City Basin, the basal Rakes Creek paleosol and underlying karst are thinner and relatively poorly developed; paleosol characteristics indicate formation on lower landscape positions. Comparative pedology, the contrasting of paleosol variability, morphology, and micromorphology between different paleosols in the same regional succession, provides a basis for interpreting the larger significance of the basal Rakes Creek paleosol. The stratigraphically older upper Lawrence and Snyderville paleosols in the same area are significantly different in patterns of lateral variability and overall soil characteristics. Weaker eustatic control and stronger tectonic activity may explain the greater west-east variability (and eventual eastward disappearance) of the basal Rakes Creek paleosol. Differences in soil characteristics between the Vertisol-like upper Lawrence and Snyderville paleosols and the non-Vertisol-like basal Rakes Creek paleosol appear to be due to climate change, particularly a shift from more seasonal to more uniform rainfall. This climate change hypothesis is compatible with overall Virgilian stratigraphic trends in the northern Midcontinent outcrop area

Be-7 distribution in surface soil of central Guizhou karst region and its erosion trace, 1996, Bai Zg, Wan Gj, Wang Cs, Wan X, Huang Rg, Santschi Ph, Baskaran M,

Soil erosion in karst region of south China is one of the major environmental problems. Beryllium-7, produced by energetic cosmic rags, has been used to trace the geochemical process of the soil erosion. The study has shown that Be-7 activity profiles present a decreasing logarithmic pattern with soil depth. The maximum permeable depth of Be-7 is 2-5mm in different seasons and locations, which is deeper in autumn than in spring, On the contrary, its apparent activity on boundary soil is higher in spring than in autumn. The Be-7 inventories in soil cores are higher in accumulative locations than in eroded one. Upper hills in the karst region are seriously eroded. Erosive intensity is higher in rainy periods than in dry ones. Influenced by the micromorphology and precipitation, the eroded particles accumulated in shallow basin after a short-distance transportation in winter and spring. However, in summer and autumn, they might be transported into drainage systems

Mn-Fe deposits in shallow cryptic marine environment: examples in northwestern Mediterranean submarine caves, 2001, Allouc J, Harmelin Jg,

Black coating of hard substrates by Mn and Fe oxides has long been reported from shallow, dark, submarine caves. However, these littoral metallic deposits have never been studied in detail, despite expected analogies with deep-sea polymetallic crusts. Submarine caves are characterized by darkness and low rates of exchanges with the open sea. Lack of primary production and confinement of inner water bodies result in marked oligotrophy and extremely reduced biomass, i.e. conditions close to those prevailing in deep-sea habitats. Field evidences suggested that the formation of Mn-Fe coatings was closely tied to these particular environmental conditions. The goal of this study was to examine the detailed features of Mn-Fe coatings from dark caves with different local conditions, and to try to identify the processes responsible for their deposition. Study sites and methods Three sublittoral, single-entrance, caves were sampled by scuba diving along the coasts of Provence (France, Mediterranean Sea) (fig. 1). The first site is a large karstic cave (Tremies Cave, 16 m depth at entrance floor, 60 m long; Marseille-Cassis area) with an ascending profile which results in a buffered thermal regime and markedly oligotrophic conditions due to warm water trapping in its upper part (fig. 1 and 2). Wall fragments were sampled at 30 m (medium confinement : zone B) and 60 in (strong confinement : zone C) from the cave entrance. The second site is a large tubular cavity open in conglomerate formations (3PP Cave, 15 m depth at entrance floor, 120 m long; La Ciotat) with a descending profile which results in relative permanence of winter temperatures within the inner parts, complex water circulation and presumed greater input of sedimented particles than in the preceding cave (fig.1 and 2). Wall samples were taken at 25 m, 70 in and 100 m from entrance. The third site is a small, horizontal, cave open in quartzite formations (Bagaud Cave, 7 in depth at entrance floor, about 10 m long; WNW of Port-Cros Island, bay of Hyeres). Sampling was performed on walls of a narrow corridor between an anterior room and a smaller inner room. A sporadic outflow of continental waters is located in the inner room. The samples were preserved in 50% ethylic alcohol or studied soon after their sampling. Before carbon coating and SEM examination, or microanalyses with SEM-associated spectrometers, they were treated in a 33% Chlorox solution and thereafter washed in demineralized water and dried. Micromorphology At low-medium magnification (<20,000), the aspect of coatings varies between caves and, especially, between inner-cave locations. All the described structures are made up of Mn and Fe oxides. In Tremies Cave, coatings of walls from zone B are composed of irregular erected constructions (height : 10s to 100s μm) formed by the aggregation of roughly ovoid primary concretions of about 10 μm (fig. 3). The surface of those primary concretions displays numerous lacunose to reticulate films (pores, about 0.5 μm in diameter, are often subrounded). Remnants of these films and organomorphic corpuscles occur also within the primary concretions (fig. 4). On younger substrates (broken wall exposed since 1970), primary concretions are poorly developed and no prominent construction is visible (fig. 5). In more confined conditions (zone C), the erected constructions of ancient coatings are smaller and less numerous than in zone B but are well individualized (fig. 6). In this zone: C, besides some remnants of lacunose to reticulate films (fig. 7), there is an appearance of filaments and ovoid corpuscles (height/width : 10-30/5-15 μm), which seem to be linked to filaments by a short stalk (fig. 8). In 3 PP Cave, at 25-70 m from entrance, wall coatings present porous heaps of primary concretions (fig. 9). The surface and the inside of the latter comprise remnants of lacunose to reticulate films that evoke those observed in Tremies Cave (fig. 10 and 11). On younger substrates (hard parts of sessile invertebrates), coatings are restricted to micrometric organomorphic corpuscles with some remnants of lacunose or fibrous films (fig. 12). At 100 in from the entrance, coatings are shaped by numerous erected constructions, more or less coalescing (fig. 13). Besides remnants of lacunose films, the primary concretions contain interlacing filaments (diameter : 0.2-0.3 μm) forming cords or veils (fig. 14). In Bagaud Cave, the primary concretions are aggregated in irregular heaps (fig. 15). Lacunose films are particularly frequent and tend to form three-dimensional mamillated structures that were not observed in the other caves (fig. 16). In particular, there is an appearance of tubular structures (fig. 17) and of numerous hemispheroidal structures (diameter : 4-5 μm) with an upper orifice (fig. 18 and 19). At higher magnification (20,000), whatever the cave and inner-cave location, the aspect of oxide deposits is rather smooth or, especially, microgranular (fig. 20). Mineral composition The composition of coatings is different between caves and according to their inner-cave location. In both large caves (Tremies and 3 PP), the Mn/Fe ratio increases with the distance from the cave entrance, i.e. when exchanges with the open sea diminish (fig. 21a). This trend is particularly clear in Tremies Cave, where the confinement gradient is strongly marked. Besides, the Mn/Fe ratio also seems to increase when films are present in the analysed volume (some cubic micrometers) (fig. 21b). In Bagaud Cave, the Mn/Fe ratio reaches high values despite the small size of this cave and its low confinement level. Discussion and conclusions SEM observations suggest that in each studied cave, the Mn-Fe coatings are biosedimentary deposits. Genesis of these deposits is assumed to result mainly from the replacement of biofilms (composed of cells and slime, i.e, of extracellular polymeric substance produced by microorganisms) generated by microbial populations colonizing the cave walls. Considering the darkness of the cave-locations, microbes consist mainly in bacteria, but fungi are probably responsible for the filaments and ovoids corpuscules (evoking sporocysts) occurring in innermost parts. Observations at different scales of the morphological features of oxide deposits reveal a structured organisation which varies along the strong environmental gradients (particularly the confinement level) that occur from the entrance to the innermost parts : erected constructions made up of primary concretions become more and more defined and acquire a pseudo-columnar shape. The aspect of biofilms appears to be controlled by the same environmental parameters. In open or relatively open environments, they frequently show a three-dimensional development (with frequent skullcape-like shapes), while in more confined conditions they exhibit a planar layout. These changes reflect either the adaptation of the slime-producing bacteria to the local trophic resources (correlated to the rate of exchange with the open sea) and water movements, or spatial replacement of taxa. It is assumed that slime (mainly composed of water and exopolysaccharides) induces a local increase of the concentration in dissolved Mn and acts as an ion exchange resin that allows the retention of Mn on the functional groups of EPS. These conditions promote the nucleation of Mn oxide crystallites in the slime. Then. the anionic character of Mn oxides in seawater, and their capacity to catalyse the oxydation of Mn2 to Mn4, allow the process to go on without any other biological intervention; thus, the process of crystal growth becomes possible. In caves where Mn is only supplied by seawater (Tremies and 3 PP), the average value of the Mn/Fe ratio of coatings is negatively correlated to the local availability of nutrients. This trend is probably linked to changes in the selectivity of slimes towards the processes of retention of cations, because this ratio is clearly influenced by the occurrence of biofilms. However, independently from trophic resources, the Mn/Fe ratio can be notably increased when additional Mn is provided by the seeping or flowing of continental waters (Bagaud Cave)

Evolution of hydraulic conductivity by precipitation and dissolution in carbonate rock, 2003,

The evolution of hydraulic conductivity and flow patterns, controlled by simultaneous  precipitation and dissolution in porous rocks, was examined in a series of laboratory  experiments. Linear flow experiments were performed in columns of crushed calcareous  sandstone by injecting different concentrations of HCl/H2SO4 mixtures at various flow  rates. The effect of simultaneous calcium carbonate dissolution and gypsum precipitation  was analyzed. Changes in head gradient, recorded at specific time intervals during the  experiments, were used to calculate overall hydraulic conductivity of each column. The  effluent acid was analyzed for Ca2+ and SO4  2_ concentrations in order to calculate porosity  changes during the experiments. After each experiment, the rock sample was retrieved and  sectioned in order to study the pore space geometry, micromorphology, and mineral  concentrations. Arange of injected H+/SO4  2_ ratios and flow rates was identified which leads  to oscillations in the effective hydraulic conductivity of the evolving carbonate rock  samples. Because the dissolution of calcium carbonate is a mass transfer limited process,  higher flow rates cause a more rapid dissolution of the porous medium; in such cases, with  dissolution dominating, highly conductive flow wormholes were observed to develop.  At slower flow rates, no wormhole formation was observed, but the porosity varied in  different parts of the columns. Analysis of the sectioned parts of the column, after each  experiment, showed that total porosity increased significantly by dissolution of carbonate  mineral near the inlet of the column and decreased along the interior length of the column by  gypsum precipitation. These findings are in qualitative accordance with conceptual  understanding of such phenomena

Evidence for habitual use of fire at the end of the Lower Paleolithic: Site formation processes at Qesem Cave, Israel, 2007, Karkanas, P. , Shahackgross, R. , Ayalon, A. , Barmatthews, M. , Barkai, R. , Frumkin, A. , Gopher, A. , And Stiner, M. C.

The Amudian (late Lower Paleolithic) site of Qesem Cave in Israel represents one of the earliest examples of habitual use of fire by middle Pleistocene hominids. The Paleolithic layers in this cave were studied using a suite of mineralogical and chemical techniques and a contextual sedimentological analysis (i.e., micromorphology). We show that the lower ca. 3 m of the stratigraphic sequence are dominated by clastic sediments deposited within a closed karstic environment. The deposits were formed by small scale, concentrated mud slurries (infiltrated terra rosa soil) and debris flows. A few intervening lenses of mostly in situ burnt remains were also identified. The main part of the upper ca. 4.5 m consists of anthropogenic sediment with only moderate amounts of clastic geogenic inputs. The deposits are strongly cemented with calcite that precipitated from dripping water. The anthropogenic component is characterized by completely combusted, mostly reworked wood ash with only rare remnants of charred material. Micromorphological and isotopic evidence indicates recrystallization of the wood ash. Large quantities of burnt bone, defined by a combination of microscopic and macroscopic criteria, and moderately heated soil lumps are closely associated with the woodash remains. The frequent presence of microscopic calcified rootlets indicates that the upper sequence formed in the vicinity of the former cave entrance. Burnt remains in the sediments are associated with systematic blade production and faunas that are dominated by the remains of fallow deer. Use-wear damage on blades and blade tools in conjunction with numerous cut marks on bones indicate an emphasis on butchering and prey-defleshing activities in the vicinity of fireplaces.

MORPHOLOGICAL INDICATORS OF SPELEOGENESIS: HYPOGENIC SPELEOGENS, 2009, Audra P. , Mocochain L. , Bigot J. Y. , Nobecourt J. C.

Hypogenic speleogenesis can be identi?ed at different scales (basinal ?ow patterns at the regional scale, cave patterns at cave system scale, meso- and micromorphology in cave passages). We focus here on small scale features produced by both corrosion and deposition. In the phreatic zone, the corrosion features (speleogens) are a morphologic suite of rising ?ow forms, phreatic chimneys, bubble trails. At the water table are thermo-sulfuric discharge slots, notches with ?at roofs. Above a thermal water table the forms re?ect different types of condensation runoff: wall convection niches, wall niches, ceiling cupolas, ceiling spheres, channels, megascallops, domes, vents, wall partitions, weathered walls, boxwork, hieroglyphs, replacement pockets, corrosion tables, and features made by acid dripping, such as drip tubes, sulfuric karren and cups. Each type of feature is described and linked to its genetic process. Altogether, these features are used to identify the dominant processes of speleogenesis in hypogenic cave systems. Hypogenic caves were recognized early, especially where thermal or sulfuric processes were active (MARTEL, 1935; PRINCIPI, 1931). However SOCQUET (1801) was one of the earliest modern contributors to speleogenetic knowledge, and probably the ?rst to identify the role of sulfuric speleogenesis by condensation-corrosion due to thermal convection. More recent major contributions evidenced the role of sulfuric speleogenesis and hydrothermalism (e.g. DUBLYANSKY, 2000; EGEMEIER, 1981; FORTI, 1996; GALDENZI AND MENICHETTI, 1995; HILL, 1987; PALMER AND PALMER, 1989). However, most of these case-studies were often considered as “exotic”, regarding the “normal” (i.e. epigenic) speleogenesis. Only recently, KLIMCHOUK (2007) provided a global model, allowing the understanding of “hypogenic” speleogenesis and gathering the characteristics of hypogenic caves. Consequently, the number of caves where a hypogenic origin is recognized dramatically increased during the last years. The hypogenic origin can be recognized at the regional scale (deep-seated karst in basins), at the scale of an individual cave system because of distinctive features in its pattern, by studying the morphology of the cave conduits, or at the local scale of wall features made by corrosion processes (i.e. speleogens). Such type of features depict the characteristics of local cave development, and by extension the characteristics of speleogenesis. The description and interpretation of hypogenic speleogens is generally scattered in the literature. The aim of this paper is to gather the most important hypogenic speleogens, considered here as indicators, and used for the identi?cation and characterization of the hypogenic speleogenesis. Our knowledge is based on the compilation of about 350 caves from the literature, and the study of some of the most signi?cant caves (AUDRA, 2007; AUDRA et al., 2002, 2006). In this paper, we focus on the speleogens (i.e. wall- scale corrosion features) as indicators of hypogenic speleogenesis; we exclude here solution feature at larger scale such as conduits and cave systems and depositional features (sediments). Some of the features observed in the sulfuric caves are speci?cally caused by this strong acid. Some features are closely associated with hydrothermalism. Other features that are widespread in hypogene caves are created without sulfuric in?uence. The following typology mainly takes into account the type of runoff. In con?ned settings with slow phreatic ?ow, cave features are common to all types of hypogene processes, whether they are sulfuric or not (i.e. carbonic, hydrothermal…). In uncon?ned settings, condensation-corrosion processes take place above the water table. These aerial processes, enhanced by the oxidation of sul?des by the thermal convections, and by the microbial processes, result in a large variety of cave features. Some features are closely related to speci?c processes. Consequently, they are considered as valuable indicators of the sulfuric speleogenesis.

Micromorphology of cave sediments, 2013, Karkanas P. , Goldberg P.

Cave sediments are commonly fine grained and lack macroscopic sedimentary structures. Only a detailed analysis of the micromorphological characteristics permits an accurate determination of the sedimentary dynamics of such cave deposits. Microscopic sorting, grading, clast orientation, lamination, intercalation, deformation structures, and porosity are some of the features used to identify microfacies such as lacustrine, slack water, debris flow, slumping, sheet wash, hyperconcentrated flows, and solifluction. In combination with micromorphological data derived from post-depositional diagenetic trend sand anthropogenic evidence, it is possible to reconstruct the evolution of a cave, and the climatic history and landscape volution of the area.

Karstification by Geothermal Waters, 2013, Dublyansky, Y. V.

Thermal waters moving through soluble rock may create voids ranging in sizes from enlarged porosity and cavernosity to extensive two- and three-dimensional cave systems. Hydrothermal caves develop in a number of settings including deep seated phreatic, shallow phreatic (near-water table), and subaerial (above the thermal water table). Speleogenesis in eachsetting involves specific mechanisms, resulting in diverse features of cave macro-, meso-, and micromorphology. Mechanisms most characteristic of the hydrothermal speleogenesis are the free convection (in both subaqueous and subaerial conditions) and the condensation corrosion. This chapter describes the morphology of hydrothermal caves

Clay cortex in epikarst forms as an indicator of age and morphogenesis—case studies from Lublin–Volhynia chalkland (East Poland,West Ukraine), 2014,

Clay cortex from the contact zone between the host rock (chalk) and infilling deposits were examined in

paleokarst forms (pockets, pipes, and dolines of different age) from the Lublin–Volhynia chalk karst region. In light of the sedimentological and micromorphological analyses, it seems possible to work out a model as the basis for genetic and stratigraphic discussions. (1) Dolineswith the Paleogene orNeogene mineral infills are characterized by (a) homogeneous, residual type of massive clay gradually passing into the chalkmonolith, and at the sametime(b) relatively thickweathered zone. (2) Pipeswith glacigenic mineral infill fromthe Saalian Glacial are characterized by (a) sharp contact between host rock and clay, (b) narrow weathering zone of chalk, (c) diffuse nature of the contact zone between residual clay and mineral infill, and (d) contamination of clay by clastic material. (3) Pocketswith glacigenic mineral infill and traces of theWeichselian periglacial transformation are characterized by (a) strong contamination of chalk by quartz grains, (b) diffuse transition between clay and infill: fromclayey matrixwith single quartz grains (at the contactwith chalk) to clayey coatings and intergranular bridges (in the infill), (c) intensive weathering (cracking) of mineral grains in the infill.