Meters In Thickness Research Articles

Lithofacies and Microfacies Study of ATE Maastrichtian Reefal Limestones and Comparison with the Aqra Formation, Northeast and Northern Kurdistan Region-Iraq

The Maastrichtian reefal limestone, which developed variably across the northern and northeastern Kurdistan Region of Iraq, includes the Aqra Formation, which formed extensive platforms in the Aqra-Barzan area throughout the Maastrichtian period. Additionally, bars and lenses of reefal limestone in the upper part of the Tanjero Formation created longitudinal submarine ridges in the Arabian-Eurasian Foreland basin. This study selected three sections: the Aqra Formation in the type section and study the reefal limestone lenses in the Upper part of the Tanjero Formation at the Kunamasi and limestone bars in the Balakaity. Focusing on lithofacies and microfacies to determine if these reefal limestones are part of the Aqra Formation. The type section of the Aqra Formation, located in the Aqra area, features significant reefal limestone approximately 700 meters thick, including rudists with bitumen and some dolomite content. This formation is widely deposited in the Aqra and Barzan areas, overlying the Bekhme platform stratigraphically, and extends geographically from Bujel to Chia Gara anticlines. Four submicrofacies identified in this reefal limestone are Miliolids packstone, Rudists floatstone, Peloidal grainstone, and Bioclastic foraminifera grainstone. In the Kunamasi area, the reefal limestone appears as thick deposits associated with marl and sandy claystone beds, approximately 30 meters thick, and situated above the flysch Tanjero Formation. Key submicrofacies here include Omphalocyclus packstone, Rudists floatstone, and Echinoids grainstone. At the Balakaity section, the reefal limestone consists of a single, thick body exceeding 50 meters in thickness, directly overlying the Tanjero Formation and restricted to the Dar-Alsalam area. The submicrofacies in this section include Foraminifera packstone, Omphalocyclus packstone, and Rudists floatstone. Overall, the microfacies interpretation is the Aqra Formation is deposited as a large platform in inner and middle ramp settings. Conversely, the reefal limestone in the Balakaity and Kunamasi areas appears to be part of submerging islands within the flysch marine environment of the Tanjero Formation during the active Arabia-Eurasian Subduction. Based on depositional context and microfacies analysis can be concluded the reefal limestone in these areas is more likely associated with the Tanjero Formation rather than the Aqra Formation.

Evaluation of CO2 storage potential of Carboniferous sandstones in the Maritime Provinces of Canada

The suitability of Carboniferous sandstones in three regions of the Maritime Provinces of Canada for geological carbon storage was evaluated: the Horton Bluff Formation in the Windsor Sub-basin, the lower Cumberland Group sandstones in the Cumberland–Sackville Sub-basin, and the Pennsylvanian sandstones of Prince Edward Island. the properties of potential reservoirs and characteristics of vertical seals and barriers to lateral migration were evaluated using previously collected well logs, sample descriptions, core analyzes and seismic interpretations. Reservoir quality was found to be the limiting factor in all three regions. Sandstones in the upper Hurd Creek Member of the Horton Bluff Formation locally have porosities up to 15% and permeabilities up to 25 milliDarcies at depths up to 1200 m. their aggregate thickness may be suitable for GCS, but individual sandstones are thin and likely of limited lateral extent. the lower Cumberland Group contains sand-dominated successions up to 1 km thick with low porosity (5–7%) where known in the subsurface. Sandstone bodies in the Bradelle, Green Gables, and Cable Head formations beneath Prince Edward Island exceed tens of meters in thickness with porosities averaging up to 10–12% and permeabilities up to 10 milliDarcies. Evaporites in the overlying Windsor Group would provide a suitable seal for the Horton Bluff Formation; in other areas the top seal would be provided by mud-prone heterolithic intervals. the evaluated areas may provide opportunities for small onshore storage projects. Further work is warranted to delineate reservoir trends and verify the integrity of potential top seals and traps.

Synsedimentary Compaction of Peat Under the Load of Alluvial System Sediments in the Most Basin (Czech Republic, Lower Miocene): From Weak Compaction to Strong Local Deformation of Clastics and Peat

Alluvial systems affected by peat layer compaction of a variable degree are studied all over the world, especially in areas of large river deltas and coastal plains. Ordinarily studied Holocene peat accumulations do not reach thicknesses of more than 6–10 m. This paper documents four ancient alluvial systems affected by peat compaction during the Lower Miocene in large exposures of open-cast lignite mines within the Most Basin, Czech Republic. Field observations and the study of 3000 borehole sections showed a clear dependence of the thickness and composition of the underlying peat on the scale of the accommodation space for loading by younger alluvial sediments. If the underlying partly compacted peat was tens to hundreds of meters in thickness, significant deformations of the peat appeared during its loading, leading up to the formation of growth faults. In such cases, missing parts of the coal seams were also observed below the alluvial systems. Especially borehole data showed that a linear correlation exists between the thickness of the alluvial sediments and the maximum instantaneous available compaction capacity of the underlying peat.

The Effect of Domain Length and Initialization Noise on Direct Numerical Simulation of Shear Stratified Turbulence

Direct numerical simulation (DNS) has been employed with success in a variety of oceanographic applications, particularly for investigating the internal dynamics of Kelvin–Helmholtz (KH) billows. However, it is difficult to relate these results directly with observations of ocean turbulence due to the significant scale differences involved (ocean shear layers are typically on the order of tens to hundreds of meters in thickness, compared to DNS studies, with layers on the order of one to tens of centimeters). As efforts continue to inform our understanding of geophysical-scale turbulence by extrapolating DNS results, it is important to understand the impact of model setup and initial conditions on the resulting turbulent quantities. Given that geophysical-scale measurements, whether through microstructures or other techniques, can only provide estimates of averaged TKE quantities (e.g., TKE dissipation or buoyancy flux), it may be necessary to compare mean turbulent quantities derived from DNS (i.e., across one or more complete billow evolutions) with ocean measurements. In this study, we analyze the effect of domain length and initial velocity noise on resulting turbulent quantities. Domain length is important, as dimensions that are not integer multiples of the natural KH billow wavelength may compress or stretch the billows and impact their energetics. The addition of random noise in the initial velocity field is often used to trigger turbulence and suppress secondary instabilities; however, the impact of noise on the resulting turbulent energetics is largely unknown. In this study, we conclude that domain lengths on the order of 1.5 times the natural wavelength or less can affect the resulting turbulent energetics by a factor of two or more. We also conclude that increasing the amplitude of random initial velocity noise decreases the resulting turbulent energetics, but that different realizations of the random noise field may have an even greater impact than amplitude. These results should be considered when designing a DNS experiment.

A Review on Metallic Nanoparticles

Metallic nano-particles are nano scale metals that fall between one to one hundred nano meters in length, breadth, and thickness. Faraday looked into the possibility of metallic nanoparticles in solution for the first time in 1856. These days, it is possible to create and modify these nanomaterials with different chemical functional groups, enabling them to engage with medicines, ligands, and antibodies. Applications for metallic nanoparticles in biotechnology, therapeutics, and medication and gene delivery are numerous. The features, benefits, drawbacks, and attributes of metal nanomaterials are outlined in this review. This review also highlights how metallic nanomaterials work as catalysts, which is necessary for stabilization. It provides the readers with detailed information on the synthesis by various methods and characterization, with a particular focus on therapeutic application along with potential side effects and their future perspectives. Recent headway has opened the way to site-specific targeting and drug delivery by these metallic nano particles. Keywords: Surface Atom and Quantum Dot, Metal Nano particle, Gold, Platinum, and Silver Nano particle, Catalyst.

Ultrahigh-Pressure Orange Garnets from the Sedimentary Deposits of the Upper Bug Area (Ukrainian Shield)

The article is dedicated to the investigation of orange garnets from Miocene-Pliocene deposits of the Balta suite and the Sarmatian stage in the Vinnytsia area. The Vinnytsia area is located on the southwestern slope of the Ukrainian Shield. The crystalline basement on most of the area is represented by granitoids of the Berdychiv complex of Paleoproterozoic age, and to a lesser extent by enderbites and charnockites of the Lityn complex of Neoarchean age. Among these, there are mafic and ultramafic bodies ranging from 0.5 to 2 meters in thickness. The sedimentary cover with a total thickness of up to 20 m is represented by sands and clays of the middle Sarmatian, Balta and Quaternary sediments. These deposits are enriched with mantle minerals, predominantly pyrope, and four diamond crystals have also been discovered. We studied the chemical composition (253 crystals) and morphology (278 crystals) of the orange garnets. The studied samples are mostly represented by garnets of pyrope and pyrope-almandine composition, a small part is represented by grossulars. Most of the garnets are unrounded crystal fragments ranging in size from 0.2 to 0.6 mm, exhibiting signs of intense hypergene changes. These are evident in the development of positive (block) and negative relief features, appearing as drop-shaped, cone-shaped, small hilly microrelief and various forms of etching channels. The morphological features suggest that these garnets were probably relocated a short distance from their primary sources and had been present in the weathering crust for an extended period. The original sources of garnets are most likely Precambrian and located on active tectonic zones, which led to their destruction. According to chemical composition data, among orange garnets low-chromium websterite and low-calcium eclogite varieties, as well as garnets of high-iron mantle pyroxenites are dominated. The presence of titanium impurities in many garnets indicates the possible diamond-bearing nature of some primary sources.

Ion adsorption-type rare earth element deposits in western Peninsular Malaysia: A case study in Bukit Enggang Granite, Kedah

This paper reports on the rare earth element (REE) deposit in Bukit Enggang Granite in Sik, Kedah, and its enrichment patterns. The granitic rock in the study area is porphyritic biotite granite with K-feldspar, quartz and biotite as the main minerals, with randomly arranged K-feldspar phenocrysts. The average REE content in rock samples is 340.9 ppm. The exposed weathered profiles are between 3 to 7 meters in thickness. The C horizon is thicker than the B horizon. The average REE content in soil samples taken from the weathered profiles is 943.9 ppm. Interpretations from laboratory results reveal that the REE deposit in the study area is of the ion adsorption-type, with the REE enrichment in the weathered profiles originating from easily weathered REE bearing minerals in the parent rock, rather than highly resistant minerals like monazite, xenotime and zircon.

Exploring geothermal resources using electromagnetic methods in coastal areas of volcanic islands: Challenges of nearshore and land 3D controlled-source electromagnetic data

Three-dimensional geophysical exploration is essential in identifying favorable areas and derisking high-temperature geothermal projects. In particular, electrical resistivity imaging plays a key role in this exploration due to its sensitivity to the presence of alteration products, geothermal fluid circulation, and temperature. As 3D seismic exploration is rarely effective in volcanic environments, resistivity methods such as magnetotellurics (MTs) are often used to extract deep structural information. However, deep electromagnetic (EM) imaging in coastal areas of volcanic islands with MT can be challenging due to anthropogenic noise induced by urbanized areas concentrated around the coast. The use of active EM sources, such as airborne EM (AEM) and controlled-source EM (CSEM), as a complement to MT is a solution for overcoming anthropogenic noise. However, applying these methods in this context is still challenging due to the proximity to the sea/land interface, large variations in topography and nearshore bathymetry, and the heterogeneity of the near surface. Our approach outlines the challenges of acquiring, processing, and inverting nearshore and land 3D CSEM data in such complex environments. The CSEM data are part of a multimethod geothermal exploration on the island of Martinique in the French West Indies, and its 3D inversion result is compared with the previous regional 3D MT and AEM inversion results. In addition to MT, CSEM may highlight the location of a potential high-temperature paleo-reservoir at shallow depths under the urbanized area of Petite-Anse covered by a paleo-clay cap ranging from a few meters to several hundred meters in thickness. We conclude by proposing possible improvements for CSEM and multimethod methodologies to obtain more reliable exploratory models.

Ekonomik Açıdan Sivas Havzası Doğal Anhidrit Potansiyeli, Rezerv Tahmini ve Jeokimyasal Özellikleri, Orta Anadolu, Türkiye

This study focuses on the economization of natural anhydrite, which has a wide range of uses and is environmentally friendly, in Türkiye. Anhydrite, which is one of the most common evaporitic minerals in the world, has almost no usage area in Türkiye. Evaporite deposits consisting of gypsum, anhydrite, halite, bassanite and selenite are prominent in the country, especially in Tertiary period sedimentary basins. The Sivas basin is one of these important Tertiary basins. Mining operates in the basin are carried out only on gypsum and anhydrite is not utilized. This study is carried out on the geological and geochemical characteristics of anhydrite, which is prominent with its usage areas in the world, its potential in the basin and its economic importance. The geochemical and mineralogical analyses are carried out on anhydrite samples taken from the basin. Anhydrite formations up to 300 meters in thickness are detected in the evaporite deposits that outcrop in most of the basin. In addition, a block model is extracted from the drilling data of a mining company operating in the basin and the reserve is calculated. As a result, it is concluded that the Sivas basin has a high potential in terms of anhydrite and should be brought to the national economy.

Deciphering the laminated botryococcus-dominated shales in saline lacustrine basin, Western Qaidam Basin, NW China: Implications for shale oil potential

Given the high lipid content and potentially huge biomass, the explosive occurrence Botryococcus is regarded as a significant marker of high-quality oil source rocks in petroliferous basins. However, they are rarely discovered in saline lacustrine source rocks, and the formation mechanism of these alga-rich shales remains uncertain. In this study, abundant Botryococcus fossils were firstly found, accounting for an average of 43.5% of the total organic debris from the upper Xiaganchaigou Formation in the Yingxiongling and Zhahaquan hydrocarbon-rich sags of the western Qaidam Basin. The Botryococcus-dominated palynofacies assemblages were usually interpreted as derived from a distal oxic shelf environment. These Botryococcus-dominated sediments were characterized by a perfect laminated texture and composed of detrital, carbonate, and clay laminae. The Botryococcus fossils exclusively occur in the detrital laminae with large-grained quartz and feldspar and low carbonate content, possibly reflecting increased river input under relatively heavy precipitation. The cyclothymic deposition between these Botryococcus-rich detrital laminae and other laminae probably indicates that sufficient terrestrial nutrient inputs and lake salinity decreases driven by periodic heavy precipitation result in Botryococcus bloom under fresh or brackish water environments. These Botryococcus-dominated shales in the western Qaidam Basin usually have a high oil-prone hydrocarbon generation potential, as evidenced by their organic geochemistry parameters. These sediments have biomarker features extremely similar to crude oil with a high relative abundance of C20–C24 tricyclic terpanes, phytane, C27ααR sterane, and a unimodal distribution of n-alkanes with the maximum at n-C18. Therefore, these Botryococcus-dominated shales are possibly important oil sources of these prolific oil sags. Additionally, these high-quality source rock sequences can reach a few tens of meters in thickness and evidently have significance for future shale oil resources.

Hydrothermal alteration of chromitite-dunite pairs from the Sabzevar ophiolite (NE Iran): Chemical and nano-textural evolution of Cr-spinel

Hydrothermal alteration of chromitite bodies in the form of pods (from a few centimeters to a few tens of meters in thickness) from the central sector of the Sabzevar ophiolite belt (NE Iran) was examined down to the nanoscale. The main Cr-spinel alteration feature corresponds to homogeneous cores (primary Cr-spinel) either rimmed by or locally replaced by heterogeneous domains composed of spinel grains with little or no inclusions / pores. The chemical evolution of spinel in response to hydrothermal alteration is found to follow two distinct chemical trends: (i) in the massive and semi-massive chromitites, the trend consists in the progressive increase of Cr without Fe3+ incorporation; (ii) in serpentinized dunites containing disseminated Cr-spinel grains, the increase in Cr occurs in conjunction with Fe3+ incorporation. These two trends involve a decrease in the spinel Mg/(Mg + Fe2+) ratio. Nanoscale observation using transmission electron microscopy (TEM) shows that porous ferrian Cr-spinel which are poorer in Al and Mg and richer in Cr and Fe than the primary Cr-spinel, contains relicts of the primary Cr-spinel as well as intercalated platelets of newly formed magnetite and lizardite/chlorite. Automated crystal orientation mapping reveals that the (001) and (111) planes of newly formed lizardite/chlorite and Cr-spinel/magnetite, respectively, are parallel. The replacement of the primary Cr-spinel by porous ferrian Cr-spinel and magnetite is found to be isomorphic. The pores, ranging from 2 to 15 μm in size, may act as pathways for the aqueous solutions involved in the serpentinization process, which fed the crystallization of alteration minerals in the pores. The two different compositional trends in chromite grains from massive/semi-massive chromitite and hosted in serpentinized dunite are best explained, using mass-balance calculation, by considering the influence of the Cr-spinel/(Cr-spinel+olivine) initial ratio in the rock (XChr) and the dissolution of Mg at a water-to-rock ratio (w/r) above one. In general, at the cm-to-meter scale, Al and Fe exchange between chromitites and their serpentinized dunite envelope was not observed in the central sector of the Sabzevar ophiolite belt; however, such Al and Fe transfer is clearly observed in other parts of this ophiolite belt, where hydrothermal alteration of podiform chromitites produced magnetite ores. Comparatively, the small extend of chromitite alteration observed here, likely reflects the product of lesser fluid-rock interaction with w/r ratio close to one instead of >103 estimated for the magnetite ores based on the magnitude of the Al transfer to their dunite envelope.

Integrated Interpretation of Electrical Resistivity Tomography for Evaporite Rock Exploration: A Case Study of the Messinian Gypsum in the Sorbas Basin (Almería, Spain)

In this study, we conduct an investigation of the Sorbas Basin (Almería, Spain) on the Messinian gypsum unit using geophysical prospecting methods. Geophysical electrical resistivity tomography (ERT) methods were applied to study the subsurface of this gypsum unit, the exploitation of which could be of interest economically, with different commercial specifications for alabastrine and selenitic gypsums. For the interpretation of the different ERT images, the data for the surface geology, borehole cores, and seismic refraction conducted at a point within the ERT profiles were used. The results obtained from this investigation can be used as a reference for other similar studies in other regions. It was observed that selenitic gypsum is more resistive than alabastrine gypsum; therefore, the diagenetic processes of dehydration (anhydritization) and hydration (gypsification) increase the “percolation” phenomenon through possibly ensuring a greater connectivity of the shale matrix. Fracturing and moisture can be used to fully determine the resistivity of the purest and most resistive gypsum, to the point of considerably lowering the resistivity in an entire area affected by fracturing. The use of different tests with different lengths for the same profile can help one better understand the structure of the gypsum body in the subsurface, especially when there are shale intercalations or more- or less-pure levels of gypsum that do not reach a value of a few meters in thickness, because these thinner levels of a few meters are not defined in the ERT images when the test is performed at depths of up to 75 m.

Controlling influence of water and ice on eruptive style and edifice construction in the Mount Melbourne Volcanic Field (northern Victoria Land, Antarctica)

The Mount Melbourne Volcanic Field (MMVF) is part of the West Antarctic Rift System, one of Earth’s largest intra-continental rift zones. It contains numerous small, compositionally diverse (alkali basalt–benmoreite) flank and satellite vents of Late Miocene–Pliocene age (≤12.50 Ma; mainly less than 2.5 Ma). They demonstrate a wide range of morphologies and eruptive mechanisms despite overlapping compositions and elevations, and they occur in a relatively small area surrounding the active Mount Melbourne stratovolcano. The volcanic outcrops fall into several main categories based on eruptive style: scoria cones, tuff cones, megapillow complexes, and shield volcanoes. Using the analysis of lithofacies and appraisal of the internal architectures of the outcrops, we have interpreted the likely eruptive setting for each center and examined the links between the environmental conditions and the resulting volcanic edifice types. Previous investigations assumed a glacial setting for most of the centers but without giving supporting evidence. We demonstrate that the local contemporary environmental conditions exerted a dominant control on the resulting volcanic edifices (i.e., the presence or absence of water, including ice or snow). The scoria cones erupted under dry subaerial conditions. Products of highly explosive hydrovolcanic eruptions are represented by tuff cones. The water involved was mainly glacial (meltwater) but may have been marine in a few examples, based on a comparison of the contrasting internal architectures of tuff cones erupted in confined (glacial) and unconfined (marine, lacustrine) settings. One of the glaciovolcanic tuff cones ceased activity shortly after it began transitioning to a tuya. The megapillow complexes are highly distinctive and have not been previously recognized in glaciovolcanic successions. They are subglacial effusive sequences emplaced as interconnected megapillows, lobes, and thick simple sheet lavas. They are believed to have erupted at moderately high discharge and reduced cooling rates in partially drained englacial vaults under ice, probably several hundred meters in thickness. Finally, several overlapping small shield volcanoes crop out mainly in the Cape Washington peninsula area. They are constructed of previously unrecognized multiple ‘a‘ā lava-fed deltas, erupted in association with a thin draping ice cover c. 50–145 m thick. Our study highlights how effectively water in all its forms (e.g., snow, ice, and any meltwater) or its absence exerts a fundamental control on eruption dynamics and volcano construction. When linked to published ages and40Ar/39Ar dates produced by this study, the new environmental information indicates that the Late Pliocene–Pleistocene landscape was mainly an icefield rather than a persistent topography-drowning ice sheet. Ice thicknesses also generally increased toward the present.

The putative earliest Cambrian trilobite–brachiopod association in southern Sichuan Basin of South China

ABSTRACT Parabadiella is considered the earliest trilobite representative in South China and was originally recovered from the mid-upper part of the Guojiaba Formation, in Liangshan section. Previous studies suggested that the earliest brachiopod co-occurred with the oldest trilobite, and the Parabadiella–Eoobolus association from the Xihaoping Member (Cambrian Series 2, Stage 3), in southern Shaanxi was considered the first trilobite–brachiopod assemblage zone in South China. Therein, brachiopods occur together with trilobites recovered in Well JS103 seemingly extending the First Appearance Datum deeply in the lower Cambrian at the central Yangtze Platform. Well JS103 is a shale gas exploration well that targets the lower Cambrian Jiulaodong Formation in southern Sichuan Basin. The uppermost fossiliferous layers are siliciclastic rocks nearly 10 metres thick. Here, two distinct trilobite zones are found, including the lower Parabadiella Zone and the upper Wutingaspis–Eoredlichia Zone. Additionally, the lowermost part of the Guojiaba Formation is poorly fossiliferous, and ranges from 200 to 250 metres in thickness. Thus, the discovery of the brachiopod–trilobite assemblage provides new insights into the biostratigraphy in Sichuan and is of great potentials for biostratigraphic correlation of the siliciclastic rocks in the western margin of the Yangtze Platform.

Detection of Haqlaniyah cave within carbonate stratigraphic sequence rocks using 2D resistivity imaging technique, Haditha, western Iraq

The western desert of Iraq is characterized by a widespread karst phenomenon and caves. The study area is a site for the establishment of a primary school inAl- Haqlanighah village Haditha area, during leveling the land with a bulldozer, the ground collapsed, causing a hole with a diameter of up to two meters. Two-dimensional resistivity imaging has been applied to detect the depth and extent of the subsurface cave within carbonate rocks and along two cross-image lines in the array of Dipole-dipole and an electrode distance of 5 meters, each length of 105m. 2D Dipole-dipole imaging technique is obtained the inverse models which shows the resistivity variation between the anomalous of background resistivity of rocks and part of cavity is about 750:100 Ω.m. These models showed that the depth 11m at the cavity operator to the roof of cavity. While the actual depth at same location of this cavity measured of 11.35m approximately. The results of this study showed that the extension of the cave along the first track is 52 meters in a direction of west-east, 11 meters depth to the ceiling of the cave, 31-35 meters to the bottom of the cave. While the extension of this cave along the second track is 20 meters in a direction south-north, and the depth to the ceiling of the cave is 12 meters and 32-34 meters to the bottom of the cave. The stratigraphic succession of the study area, starting from bottom withAnah Formation, overlain by unconformity brecciated bed, ranging from 6 to 30m meters in thickness, followed by Euphrates Formation in the top. The unconformity layer is less cohesive than the rocks beneath and above it. So it was the best area for the caves to be formed as a result of dissolving its rocks by leaking rain water and groundwater. Therefore, it must be a pre-engineering preparation before starting any urban construction of the population in the study area or adjacent areas to avoid risks.

Historic subsurface dimension stone quarry and the stability of its galleries as a function of pillar width and thickness of cover bed

There are historic subsurface dimension stones in the capital of Hungary (Budapest) that were excavated in porous limestone. The stability of these subsurface openings is important, since most of them are located in urban areas, where existing buildings or new structures are planned to be built. The paper presents a detailed study considering the geometry of the system and the mechanical parameters of the limestone. The geometry of the cellar system was obtained using terrestrial laser scanning (TLS). The cover beds are few meters in thickness, and the width of the pillar is between 2.50 and 3.98 m, according to the measurements. The rock mass parameters which were used in the calculations were obtained from laboratory tests. A finite element (FEM) software Rocscience (RS2) were applied to model the stability of the galleries. Calculations were made for various geometries taking into account the thickness of cover beds and the width of pillars. Altogether 70 models were made. A surface load of 150 kN/m2 was also applied to model the buildings. New relationships between cover bed thickness, pillar width and displacements are outlined to compare these results to previous works. The strength reduction factor was also calculated for all geometries, indicating the changes in the stability of these underground quarries and pointing out the importance of cellar geometries.

The initial phase of the Hönne Valley Reef at Binolen (northern Rhenish Massif, Middle Devonian)

The Hagen-Balve Reef Complex of the northern Rhenish Massif, Germany, is one of the best examples for the globally widespread Givetian to Frasnian reefs. At its eastern end, in the Hönne Valley, it reaches up to 1000 metres in thickness. In general, there is limited knowledge concerning the faunas and palaeoecology of Rhenish initial reef phases. A unique section at Binolen exposes the sharp boundary between the underlying, siliciclastic Upper Honsel Formation and the lower part of the reefal Hagen-Balve Formation. A ca. 14 m thick succession is assigned to the new Binolen Member and investigated in terms of carbonate microfacies, micro-, and macrofaunas. Seven microfacies types (MF) characterise a crinoidal coral-stromatoporoid garden setting (MF-2 to MF-6) or allobiostrome of an initial open platform turning upsection into a coral parabiostrome (MF-7/8). The base of the Asbeck Member is locally defined by the appearance of back-reef facies types, such as fenestral limestones (MF-9), which indicate the transformation into a bioherm. Low-diversity conodont faunas prove an influx of open shelf organisms for the Binolen Member and suggest a lower Givetian age (probably Polygnathus timorensis Zone). There are two new Givetian conodont biofacies types characteristic for open biostrome settings, the Bipennatus Biofacies and a Simple Cone Biofacies. Thin sections reveal over 40 different reef builders (rugose and tabulate corals, stromatoporoids, and chaetetid sponges). Around 4200 microfossils from conodont residues consist of agglutinating foraminifers, calcareous sponge spicules (e.g. Heteractinida), scolecodonts, echinoderms (mostly crinoid ossicles and holothurian sclerites), pyritised benthic ostracods, assumed calcified moulds of chitinozoans, subordinate microvertebrates, and other groups. They were analysed quantitatively in order to document changing distribution patterns and environments through time. We distinguish six microfossil-based biofacies types (BF), namely the Ostracoda Biofacies (BF-O), Foraminifera Biofacies (BF-F), Scolecodont Biofacies (BF-S), Chitinozoa Biofacies (BF-C), Porifera-Scolecodont Biofacies (BF-PS), and Porifera-Echinodermata Biofacies (BF-PE). Microfacies and microfossil assemblages led to a reconstruction of the local facies development, consisting of seven successive depophases with further subdivisions. At the base, the sudden termination of siliciclastic influx enabled a proliferation of reef builders and microfaunas (Depophase I), followed by a longer deepening phase characterised by exclusive bioclastic wackestones (Depophase II). Depophase III is a short regressive phase with crinoidal coral-stromatoporoid floatstones. Depophase IV is characterised by fluctuations in facies and relative sea-level, which results in three subphases. Depophase V resembles Depophase III, but with argillaceous interbeds and more abundant scolecodonts. It is followed by an interval with coral-stromatoporoid rudstones, which grade into coral-dominated bafflestones of an (auto)parabiostrome (both Depophase VI). Depophase VII represent the back-reef facies, including fenestral pack-bindstones of the basal Asbeck Member. The systematic analysis of reefal microfaunas represents pioneer work that should be tested and expanded to other reefs of the Rhenish Massif and beyond.

Late Jurassic Safir evaporite salts, Sab'atayn Basin, Yemen: Lithofacies distribution, cyclicity, and mineralogy

This study aims to interpret and evaluate the Late Jurassic Safir rock unit in Sab'atayn Basin in Yemen according to its lithofacies distribution, cyclicity, and mineralogy. The study is conducted on six wells, namely, Halewah-09, Khahtan-01, Azal-25, Al-Nasr-27, Baraqish-01, and Dost Alwihda-01, based on the responses and characteristics of integrated wireline logs. The Safir Member is divided into several cycles and interpreted as a regular rhythmic deposition of halite interbedded with thin clastic (shales and sands) laminations at the top. The cycle diversity is caused by the sedimentation supply invasion (influx) from the hinterland during sea-level regression. The mineralogical analysis of the evaporite salts reveals that the log responses at the studied basin wells have a cylindrical shape, indicating low gamma ray and bulk density readings. Additionally, the high-resistivity log values designate evaporite salts, which also refer to nonpotash evaporite minerals (e.g., halite with gypsum and kieserite) in small quantities. These salts are deposited under brackish or hypersaline aqueous evaporation by periodically entering seawater through a barrier into a restricted basin. The Safir salt in Sab'atayn Basin developed throughout a restricted rift basin connected only to the east and south by the Gulf of Aden across Mukalla Arch, containing grabens and intragraben highs that are the most prosperous areas for hydrocarbon exploration in Yemen, where salt has accumulated by hundreds of meters in thickness.

Evolution of ice sheets on early Mars with subglacial river systems

Geological observations have revealed that early Martian terrains were carved with by numerous networks of valleys, which provides evidence that prolonged water activity sculpted the ancient surface of Mars during the late Noachian and the early Hesperian ages. Although such geological records would in theory require a large volume of liquid water under a long-term stable “warm and wet” climate, several model studies have indicated a contrasting “cold and icy” climate in early Mars, such that the formation of large-scale ice sheets on highlands would provide a vast reservoir of meltwater. In this study, we developed a global ice sheet model, named ALICE (Accumulation and ablation of Large-scale ICE-sheets with dynamics and thermodynamics) to perform the first simulation of the evolution of ice sheets coupled with a paleo-Mars global climate model. We began our calculations of glacial formation from the initial state with the ocean water amount corresponding to a 500 m global equivalent layer (GEL) for “cool and wet” atmospheric conditions with a surface pressure of 2 bar, H2 mixing ratios of 0% and 3%, and obliquities of 20°, 40°, and 60°.Our results show that all the water of the ocean and lakes were transferred to ice sheets within ~105 Mars years, and extensive ice sheets (thousands of meters in thickness) were formed in the southern low to middle latitudes. When geothermal heat flux was suitably high and the atmosphere contained 3% of H2, continuous subglacial melting supplied enough water due to widespread temperate-based ice sheets, forming runoff systems in the southern highlands where most valley networks are observed. With an obliquity of 40°, meltwater carved early Martian terrains within a relatively brief geological timescale (~105 Mars years). We also revealed that CO2 only atmosphere (H2 mixing ratio of 0%) could not reproduce temperate-based ice sheets and subglacial erosions even with assumed higher geothermal heat fluxes. There is still a possibility that several valleys were produced by short-lived climatic warming events, such as volcanism and meteorite impacts, which could produce the vast amount of meltwater required to sculpt valley systems.

Frictional controls on the seismogenic zone: Insights from the Apenninic basement, Central Italy

Crustal seismicity is in general confined within the seismogenic layer, which is bounded at depth by processes related to the brittle-ductile transition (BDT) and in the shallow region by fault zone consolidation state and mineralogy. In the past 10-15 years, high resolution seismological and geodetic data have shown that faulting within and around the traditional seismogenic zone occurs in a large variety of slip modes. Frictional and structural heterogeneities have been invoked to explain such differences in fault slip mode and behaviour. However, an integrated and comprehensive picture remains extremely challenging because of difficulties to properly characterize fault rocks at seismogenic depths. Thus, the central-northern Apennines provide a unique opportunity because of the integration of deep-borehole stratigraphy and seismic reflection profiles with high resolution seismological data and outcrop studies. These works show that seismic sequences are limited within the sedimentary cover (depth < 9-10 km), suggesting that the underlaying basement plays a key-role in dictating the lower boundary of the seismogenic zone.Here we integrate structural data on exhumed outcrops of basement rocks with laboratory friction data to shed light on the mechanics of the Apenninic basement. Structural data highlight heterogeneous and pervasive deformation where foliated and phyllosilicate-rich rocks surround more competent quartz-rich lenses up to hundreds of meters in thickness. Phyllosilicate horizons deform predominantly by folding and foliation-parallel frictional sliding whereas quartz-rich lenses are characterized by brittle signatures represented by extensive fracturing and minor faulting. Laboratory experiments revealed that quartz-rich lithologies have relatively high friction, μ≈0.51, velocity-strengthening to neutral behaviour, and elevated healing rates. On the contrary, phyllosilicate-rich (muscovite and chlorite) lithologies show low friction, 0.23 <μ < 0.31, a marked velocity strengthening behaviour that increases with increasing sliding velocity and negligible rates of frictional healing.Our integrated approach suggests that in the Apenninic basement deformation occurs along shear zones distributed on thickness up-to several kilometres, where the frictionally stable, foliated, and phyllosilicate-rich horizons favour aseismic deformation and therefore confine the depth of major earthquake ruptures and the seismogenic zone.