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The Ediacaran-Ordovician strata within three major marine basins (Tarim, Sichuan, and Ordos) in China are analyzed. Based on previous studies focusing on the characteristics of the Neoproterozoic-Cambrian strata within the three major basins (East Siberian, Oman, and Officer in Australian) overseas, the carbonate-evaporite assemblages in the target interval are divided into three types: intercalated carbonate and gypsum salt, interbedded carbonate and gypsum salt, and coexisted carbonate, gypsum salt and clastic rock. Moreover, the concept and definition of the carbonate-evaporite assemblage are clarified. The results indicate that the oil and gas in the carbonate-evaporite assemblage are originated from two types of source rocks: shale and argillaceous carbonate, and confirmed the capability of gypsum salt in the saline environment to drive the source rock hydrocarbon generation. The dolomite reservoirs are classified in two types: gypsum-bearing dolomite flat, and grain shoal & microbial mound. This study clarifies that the penecontemporaneous or epigenic leaching of atmospheric fresh water mainly controlled the large-scale development of reservoirs. Afterwards, burial dissolution transformed and reworked the reservoirs. The hydrocarbon accumulation in carbonate-evaporite assemblage can be categorized into eight sub-models under three models (sub-evaporite hydrocarbon accumulation, supra-evaporite hydrocarbon accumulation, and inter-evaporite hydrocarbon accumulation). As a result, the Cambrian strata in the Tazhong Uplift North Slope, Maigaiti Slope and Mazatag Front Uplift Zone of the Tarim Basin, the Cambrian strata in the eastern-southern area of the Sichuan Basin, and the inter-evaporite Ma-4 Member of Ordovician in the Ordos Basin, China, are defined as favorable targets for future exploration. [ABSTRACT FROM AUTHOR]

Dolomite reservoirs flourished during arid climatic periods in the Middle East, primarily in the Permo-Triassic, Upper Jurassic, and Oligo-Miocene formations. These dolomitized reservoirs are frequently linked to evaporites, exhibit isotopically enriched signatures, and tend to occur predominantly in the more restricted regions of carbonate platforms. These observations strongly support their origin through sabkha and evaporative reflux processes. Consequently, dolomite formation and distribution are primarily influenced by early diagenetic processes and climatic conditions during arid periods. Dolomitization has exerted a significant influence on reservoir properties within the studied carbonate platforms. Porosity distribution and variation are jointly controlled by several factors, including dolomite content, texture, crystal size, anhydrite abundance, dolomite cementation, and the extent of burial compaction. While dolomite textures can vary from fabric-preserving to fabric-destroying, the overall reservoir properties exhibit an ascending pattern from intertidal to shoal facies. This trend is primarily determined by the proximity to the source of dolomitizing brines. The downward percolation of brines, coupled with decreasing dolomitizing potential, leads to an increase in dolomite crystal size within depositional cycles as one moves further away from the anhydrite facies. Proximal areas, characterized by fine-grained intertidal and lagoonal facies, are more susceptible to anhydrite cementation and overdolomitization, resulting in significant porosity reduction. Conversely, in more distal regions, reservoir quality substantially improves, particularly in areas dominated by sucrosic dolomite or grain-rich facies. While this trend may be altered by compaction during burial, it underscores the crucial role of dolomitization in preserving porosity, especially in deeply buried carbonate reservoirs. [ABSTRACT FROM AUTHOR]

Maastrichtian to Thanetian carbonate platforms comprise the outcrops of scarcity, especially in Tethys, Zagros Foreland Basin of which is hardly documented. A carbonate platform-to-basin transect in Zagros Basin was done, consisting of two important outcrops, and large cliffs with a vast landscape and good photographic capacity. Based on large benthic foraminifera (LBF) and planktonic foraminifera, these carbonate platforms are referred to as Tarbur and Taleh Zang formations, which are dated to the Maastrichtian and Paleocene (Thanetian-Selandian). Multiple stratigraphic approaches, along with the facies analysis, were used to build the carbonate platform architecture and figure out the most conspicuous factors controlling the evolution of these platforms through time. Ten sedimentary facies belts were identified, ranging from the basin to the proximal and distal shallow-water contexts with carbonate ramps. The distribution of grain-associations in the spatial and temporal scale, facies belts, apparent stratal geometry, and biological evolution accompanied by age dating led to identifying two distinct carbonate models: Maastrichtian distally steepened ramp and Paleocene carbonate ramp, belonging to Tarbur and Taleh Zang carbonate formations, respectively. Due to the first dominating community of Cenozoic Zooxanthellate corals associated with red coralline algae as separate patches, the Paleocene Taleh Zang carbonate ramp was divided into two carbonate modes: Danian-lower Selandian and upper Selandian. [ABSTRACT FROM AUTHOR]

A study on depositional environment, diagenetic history, and sequence stratigraphy of the upper Cretaceous successions of the boundary between the Central and Eastern Alborz zones is lacking. This study attempts to tackle this issue by analyzing a succession composed of 120 meters of medium-to thick-bedded limestones. Facies analysis led to the identification of facies associations of terrestrial, inner ramp (proximal, mid, and distal lagoon and shoal), mid ramp, outer ramp, and basin settings. According to the lateral and vertical changes in facies associations indicating gradual facies variations and the absence of large barrier reef organisms, a carbonate platform of ramp type with a bioclastic shoal is suggested for the studied succession. However, regarding the presence of turbidites in the transition of mid and outer ramp facies, a distally steepened ramp better suits the studied succession. Diagenetic study reveals products of eogenesis, mesogenesis, and telogenesis stages. Sequence stratigraphic analysis based on facies analysis and field observation denoted one 3rd-order depositional sequence, which its maximum flooding surface is equivalent to MFS K180 of the Arabian Plate (AP) with middle Maastrichtian age. A disconformity at the topmost of the studied succession correlates with the upper sequence boundary of megasequence AP9 around the Cretaceous-Paleogene boundary. [ABSTRACT FROM AUTHOR]

To clarify the development rules and main origins of deep tight conglomerate reservoirs in the Mahu area of Junggar Basin, various materials and data from deep wells were systematically researched to determine the reservoir's basic characteristics and effective origins. The results indicate that the reservoir mainly comprises a fine and medium-fine conglomerate, which belongs to the fan delta distributary channel conglomerate. Additionally, it is a typical deep tight conglomerate reservoir with low to ultra-low porosity and permeability, and the gravel primarily consists of volcanic rock composed of tuff and intermediate acid volcanic lava. The cement is mainly composed of laumontite and calcite, and the reservoir has undergone three types of diagenesis: compaction, cementation, and dissolution. The first two types have dual effects of destruction and construction, while the result of dissolution is the widespread development of secondary pore enrichment zones composed of intergranular solution pores formed by the dissolution of zeolite, carbonate cement, and argillaceous matrix, as well as intragranular solution pores formed by the dissolution of feldspar and dark minerals. Unlike the middle and shallow layers, the reservoir space mainly composed of secondary pores and fractures. The effective reservoir is mainly caused by rock composition, dissolution, fracture system, and abnormal high pressure. The rock composition provides a sufficient material basis and is the internal cause, while the dissolution, fracture system, and abnormal high pressure are the external causes. The dissolution forms a secondary pore enrichment zone, the fracture system improves the seepage capacity of the reservoir, and abnormal high pressure can effectively maintain and increase the pores. Four factors control the formation and distribution of relatively highquality deep tight conglomerate reservoirs. [ABSTRACT FROM AUTHOR]

The study aimed to evaluate the humus quality of anthropogenic soils derived from flysch deposits. A total of 10 samples were collected in the top-soil horizon (0-20 cm) of olive groves in Kaštela Bay in Middle Dalmatia, Croatia. Five samples were taken from traditional low-input olive groves (TOG), and the other five samples were from intensive ones (IOG). The soil samples were analysed for basic soil properties: particle size distribution, pH, carbonate content, P2O5, K2O, and soil organic carbon (SOC) content. Humic substance isolation was done following the procedure given by Schnitzer (1982). Spectroscopic characterization of humic substances was carried out by measuring absorbances in VIS spectral range (400-700 nm). Optical index E4/E6 (ratio of optical absorbance at 465 and 665 nm for humic substances in solution) was calculated. The mean value of SOC content in soils of TOG was lower than in soils under IOG (1.20 and 1.60%, respectively). The absorption spectrum of the studied soils showed a monotonous decrease of absorbance from 400 to 700 nm. The E4/E6 indices for soils under TOG varied from 4.60 to 5.00, while for soils under IOG were in the range of 4.83 - 6.89. The E4/E6 indices > 4 revealed low humus quality in studied soils. However, soils under TOG have lower mean values E4/E6 index in comparison to soils under IOG (4.76 and 5.70, respectively), indicating slightly higher humus quality. [ABSTRACT FROM AUTHOR]

Seismic data, borehole image logs, and conventional well logs were used to investigate the distribution and characteristics of paleokarst features in the Aptian carbonates of the Barra Velha Formation in a pilot area of the Santos Basin, Brazil. Multiple seismic attributes were used to enhance details on the seismic data and highlight key seismic parameters including strata deformation and geometry, continuity of seismic events, and fault patterns. The study found that karst structures are controlled by faults and fractures along structural highs, which served as a conduit for the flow of dynamic fluids that dissolved the carbonate materials. Several closed, circular depressions and bright spots identified in the northeastern portion of the study area represent possible sinkhole structures. Epigenic and hypogenic processes due to the action of meteoric water, hydrothermal activity, and intra-formation acidity along regional unconformities in the Barremian-Aptian may have been responsible for the dissolution. Limitations of this study are related to the difficulty of integrating multiple datasets with various scales. However, the higher confidence for the occurrence of the karst features is provided by borehole images at the sub-seismic scale. The findings of this study hold significant relevance for the strategic planning of energy development and carbon sequestration initiatives in the Brazilian continental margins, thereby aiding in informed decision-making. [ABSTRACT FROM AUTHOR]

Ocean alkalinity is critical to the uptake of atmospheric carbon in surface waters and provides buffering capacity towards associated acidification. However, unlike dissolved inorganic carbon (DIC), alkalinity is not directly impacted by anthropogenic carbon emissions. Within the context of projections of future ocean carbon uptake and potential ecosystem impacts, especially through Coupled Model Intercomparison Projects (CMIPs), the representation of alkalinity and the main driver of its distribution in the ocean interior, the calcium carbonate cycle, have often been overlooked. Here we track the changes from CMIP5 to CMIP6 with respect to the Earth system model (ESM) representation of alkalinity and the carbonate pump which depletes the surface ocean in alkalinity through biological production of calcium carbonate, and releases it at depth through export and dissolution. We report a significant improvement in the representation of alkalinity in CMIP6 ESMs relative to those in CMIP5. This improvement can be explained in part by an increase in calcium carbonate (CaCO3) production for some ESMs, which redistributes alkalinity at the surface and strengthens its vertical gradient in the water column. We were able to constrain a PIC export estimate of 51–70 Tmol yr-1 at 100 m for the ESMs to match the observed vertical gradient of alkalinity. Biases in the vertical profile of DIC have also significantly decreased, especially with the enhancement of the carbonate pump, but the representation of the saturation horizons has slightly worsened in contrast. Reviewing the representation of the CaCO3 cycle across CMIP5/6, we find a substantial range of parameterizations. While all biogeochemical models currently represent pelagic calcification, they do so implicitly, and they do not represent benthic calcification. In addition, most models simulate marine calcite but not aragonite. In CMIP6 certain model groups have increased the complexity of simulated CaCO3 production, sinking, dissolution and sedimentation. However, this is insufficient to explain the overall improvement in the alkalinity representation, which is therefore likely a result of improved marine biogeochemistry model tuning or ad hoc parameterizations. We find differences in the way ocean alkalinity is initialized that lead to offsets of up to 1 % in the global alkalinity inventory of certain models. These initialization biases should be addressed in future CMIPs by adopting accurate unit conversions. Although modelers aim to balance the global alkalinity budget in ESMs in order to limit drift in ocean carbon uptake under preindustrial conditions, varying assumptions in the closure of the budget have the potential to influence projections of future carbon uptake. For instance, in many models, carbonate production, dissolution and burial are independent of the seawater saturation state, and when considered, the range of sensitivities is substantial. As such, the future impact of ocean acidification on the carbonate pump, and in turn ocean carbon uptake, is potentially underestimated in current ESMs and insufficiently constrained. [ABSTRACT FROM AUTHOR]

In order to study the formation conditions of deep high-quality reservoirs, taking the Enping Formation and Wenchang Formation in the Southern Huizhou Sag of the Pearl River Mouth Batin as examples, the characteristics of the reservoirs in the study area were analyzed according to the data of rock thin section, cathodoluminescence, scanning electron microscope, reservoir physical properties, and burial history, then to discuss the preservation mechanism and model of primary pore diagenesis in deep reservoirs. The results show that feldspar lithic quartz sandstone is mainly developed in Enping Formation in the Southern Huizhou Sag, and feldspar lithic sandstone is mainly developed in the Wenchang Formation in the Southern Huizhou Sag. The pore types are mainly primary pores, and the porosity ranges from 1.9% to 17. 3%, with an average of 13. 3%, the permeabllity is between with an average of The preservation of primary pores in the reservoir is controlled by many factors. Among them, the lower geothermal gradient inhibits the compaction, the long-term shallow burial in the early stage and the rapid burial in the later stage make the compaction in-sufficient, and the differential cementation of carbonate and the early oll and gas charging hinder the compaction and the formation of the reservoir. The cementation in the sand body lads to the widespread development of primary pores in the reservoir. The resuits provide a baiis for estabiishing a deep exploration and development plan and predicting the horizontal and vertical distribution of high-quaiity reservoirs. [ABSTRACT FROM AUTHOR]

Two wells close to each other (Well A and Well B) have been selected from the same oilfield in southern Iraq. Both wells were drilled through the Mishrif Reservoir, however, perforated within different sub-units. It was observed that one of the wells shows obvious flow naturally while the other did not notice any kind of flow. The type of hydrocarbon interpretation by Gas while drilling method (GWD), the results confirmed that both of these wells were located in oil-bearing reservoir with comparable gas profiles. However, petrophysical properties of the pore distribution and permeability using Neutron Magnetic Resonance (NMR) data in Techlog identified key differences in rock quality between the wells across the perforated intervals. Reservoir quality reveal very wide differences in performance in spite of both wells are penetrating the oil bearing layers within Mishrif reservoir. [ABSTRACT FROM AUTHOR]

A Hildoglochiceras-rich horizon is reported from a thin carbonate intercalation within the siliciclastic Upper Jurassic Jhuran Formation of the Jara Dome, western Kachchh Mainland. The Hildoglochiceras specimens have been used for the first population-level study of the genus based on a multivariate analysis. High phenotype instability in the large sample confirms the occurrence of transient forms between morphospecies. Key morphological traits for interpreting Hildoglochiceras are stated, and the morphospecies Hildoglochiceras kobelli (Oppel) and H. kobelliforme (Bonarelli) are interpreted as a dimorphic pair. The ammonite-rich level is interpreted as a Hildoglochiceras Horizon, which is related to a transgressive pulse and maximum flooding zone interrupting largely restrictive conditions for ammonites. The endemic character of Hildoglochiceras is confirmed and related to its environmental restriction to shelf areas on the palaeomargins of the Trans-Erythraean Trough. A comprehensive review of biostratigraphic interpretations of Hildoglochiceras shows the influence of natural and experimental forcing factors. The uppermost Kimmeridgian to lowermost Upper Tithonian interval is the widest biostratigraphic range assumable for Hildoglochiceras based on existing reports, but most probably it was restricted to, or at least better represented in, Lower Tithonian horizons. The Hildoglochiceras Horizon described here is correlated with a lower part of the Albertinum/Darwini Zone in the Secondary Standard Scale for ammonite-based bio-chronostratigraphy in European and West-Tethyan areas. According to the current state of knowledge, a local rather than wide regional significance is favoured for Hildoglochiceras records before its significance for precise correlation across the Trans-Erythraean Trough. [ABSTRACT FROM AUTHOR]

Sequence stratigraphy is a method that unravels the evolution of sedimentation through time and space within sedimentary basins. Nowadays, the exploration and production of natural resources generated by or related to sedimentary processes depend on constructing a chronostratigraphic framework to identify sequences of distinct hierarchies. In clastic and carbonate successions, exploratory studies focus on higher-rank sequences to evaluate the potential of natural resources and to make discoveries. Conversely, lower-rank (i.e. high-frequency) sequences characterize and highlight the spatial and temporal occurrence of natural resource deposits and heterogeneities, necessary for optimizing production. For instance, high-resolution sequence stratigraphic surfaces may indicate the location of placer deposits or coal seams. In the petroleum industry, high-resolution sequence stratigraphy is applied in reservoir zonation and characterization, which are the stratigraphic essence of 3D geological and fluid flow models. Thus, this methodology can guide reservoir management, forecast and optimize production, and increase the ultimate recovery factor. Recent technological innovations such as virtual outcrop models and Ground Penetration Radar have promoted a significant advance in the visualization of surfaces and stacking patterns, making stratigraphic analysis more accurate and efficient than the traditional use of analogs. [ABSTRACT FROM AUTHOR]

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In the Maritime Alps (NW Italy - SE France), the Middle Triassic-Berriasian platform carbonates of the Provençal Domain are locally affected by an intense hydrothermal dolomitization. This dolomitization resulted from a large-scale hydrothermal circulation related to deep-rooted faults, and is indirect evidence of a significant earliest Cretaceous fault activity in this part of the Alpine Tethys European palaeomargin. New carbonate U-Pb dating and geochemical (stable isotope and noble gases on inclusion-hosted water, 87Sr/86Sr, clumped isotopes) data allowed a better understanding of the timing and mechanisms of the hydrothermal circulation. Hydrothermal fluids probably originated from seawater, which was involved in a deep circulation within the underlying crystalline basement, undergoing heating to more than 200°C and substantial compositional modification by prolonged interaction with basement rocks. Thin cement rims rich in carbonaceous material, locally alternated with hydrothermal dolomite cements, are interpreted as remnants of ephemeral microbial communities that could colonize the upper part of hydrothermal conduits during periods of reduced hot fluid flow and contemporaneous downward seawater infiltration. [ABSTRACT FROM AUTHOR]

The X-ray microtomography was used to visualize and characterize the remobilization oil process inside the porous system of a carbonate rock sample. After being saturated with a brine solution, dodecane oil was injected into the porous media, initially a predominant water-wet system. After an aging process is performed, the system became mixed-wet. The remobilization was induced by the injection of two KI (Potassium Iodide) brine solutions, a high salinity solution injection (1.5 M) followed by a low one (0.3 M). The intention was to achieve, besides the immiscible displacement process, oil remobilization due to the modification of interfacial properties of fluids and wettability caused by low salinity of the injected brine. It was observed that the low salinity brine was capable of shifting the oil inside the porous medium and reduce the residual oil saturation. [ABSTRACT FROM AUTHOR]

Zebra dolomites and carbonate - hosted Au - Ag - Zn ± Pb deposits of Maden village is located in the shelf type carbonate rocks of the Bolkar Mountains. The Zebra dolomite (ZD) locally form and there is no evidence for relation between dolomitization and mineralization. Maden village ZD is characterized by parallel light and dark bands that have similar mineralogy and chemistry by petrographic and SEM + EDX investigation. The δ13 C (V - PDB) composition of the Zebra dolomite from 2.59‰ to 2.72‰ and the δ18 O (V - PDB) values of the Zebra dolomite from -11.39 ‰ to -14.88 ‰. These isotopic values show that the source of oxygen and carbon was derived from marine carbonates and freshwater carbonates. Fluid inclusion studies on Zebra dolomite show homogenization temperatures of 80 °C - 180 °C. Based on petrographic, isotope values and fuid inclusion study, we can say that the dolomitization occurred during the late diagentic conditions prior mineralization. [ABSTRACT FROM AUTHOR]

This paper pertains to the influence of decreasing supplementation to transformation of chemical forms of Ni, Zn and Cu during composting of sewage sludge. A universally used supplementing material constituting a rich source of organic carbon is straw. Addition of straw to sewage sludge is aimed at increasing C/N proportion up to at least 15 due to the risk of formation of toxic forms of nitrogen, concentration of which in sewage sludge is exceptionally high. We have presented in this paper the results of speciation research of three elements applying Tessier’s sequential extraction. It’s been proven that decreasing of straw share in the composted mixture with sewage sludge down to the level of C/N value below the admissible value, has a beneficial effect on the allocation of tested heavy metals towards the forms that are permanently bound in compost matrix. A systematic increase of organic (IV) and residual (V) fractions share and decrease of mobile forms of heavy metals content in bioavailable fractions i.e. ion-exchange (I) and carbonate (II) has been ascertained. [ABSTRACT FROM AUTHOR]

Laser ablation U-Pb analyses of carbonate (LAcarb) samples has greatly expanded the potential for U-Pb dating to a variety of carbonate-producing settings. Carbonates that were previously considered impossible to date using isotope dilution methods may preserve radiogenic domains that can be dated using spatially resolved laser ablation geochronology techniques. Work is ongoing to identify reference materials and to consider best practices for LAcarb. In this study we apply standard and emerging characterization tool sets on three natural samples with the dual goal of enhancing the study of carbonates and establishing a new set of well-characterized natural reference materials for LAcarb studies. We start with the existing carbonate reference material WC-1 from the Permian Reef Complex of Texas, building on the published description to offer a deeper look at U and associated trace elements. We consider a tufa sample from the Miocene Barstow Formation of the Mojave Block, California, as a possible secondary calcite reference material due to its well-behaved U--Pb systematics. There are currently no natural dolomite standards. We present an unusual dolomite sample with very well-behaved U--Pb systematics from the Miocene of the Turkana Basin of Kenya as a possible dolomite reference material for LAcarb dating. In addition to using X-ray fluorescence (XRF) mapping and spectroscopy to better understand U in these natural samples, we have analyzed multiple aliquots of each of them for 87Sr=86Sr by thermal ionization mass spectrometry (TIMS). The Sr isotope compositions are analytically homogeneous within petrographically homogeneous regions of all three samples, and thus these materials could be used as Sr isotope standards as well. While not part of the current contribution, this combination could streamline simultaneous LA analyses of 87Sr=86Sr and U--Pb geochronology. [ABSTRACT FROM AUTHOR]

Occupational lung diseases such as coal worker's pneumoconiosis, often called black lung, are caused by exposures to respirable coal mine dust. Dust composition is increasingly understood as an important disease factor, and it can vary significantly depending on dust source materials and generation processes. For regulatory compliance purposes, the mass concentration and quartz percentage of respirable dust are monitored in U.S. coal mines, but the whole composition is not typically determined. Previous work has indicated that thermogravimetric analysis (TGA) can be used to apportion the respirable dust mass to three important component fractions (i.e., coal, non-carbonate minerals, and carbonate), which should generally correlate with three different dust sources (i.e., coal strata, rock strata, and limestone rock dusting products being applied in the mine). However, a primary shortcoming of that previous work was use of fibrous sampling filters, which limited dust recovery and thus analytical accuracy. Here, an improved TGA application is presented using smooth polycarbonate filters. Based on experiments with laboratory-generated dust samples (masses ranging between 95–1,319 µg), the TGA-derived mass fractions (reported as percentage values) for all three components were found to generally be within ±10% of expected values. [ABSTRACT FROM AUTHOR]

The response of carbonate weathering carbon-sink flux (CCSF) to its environmental drivers is still not well understood on the global scale. This hinders understanding of the terrestrial carbon cycle. Here, we show that there is likely to be a widespread and consistent increase in the global CCSF (ranging from + 9.8% (RCP4.5) to + 17.1% (RCP8.5)) over the period 1950–2100. In the coming years the increasing temperature might be expected to have a negative impact on carbonate weathering. However, the increasing rainfall and anticipated land-use changes will counteract this, leading to a greater CCSF. This finding has been obtained by using long-term historical (1950–2005) and modeled future (2006–2100) data for two scenarios (RCP4.5 and RCP8.5) for climate and land-use change in our CCSF equilibrium model. This study stresses the potential role that carbonate weathering may play in the evolution of the global carbon cycle over this century. Carbonate weathering captures CO2 and represents a large sink of terrestrial carbon that is threatened by climate and land-use change. Here the authors build a model that predicts drivers of carbonate weathering into the future, determining that runoff is an overlooked controlling factor. [ABSTRACT FROM AUTHOR]

Our ability to reliably use radiocarbon (14C) dates of mollusk shells to estimate calendar ages may depend on the feeding preference and habitat of a particular species and the geology of the region. Gastropods that feed by scraping are prone to incorporation of carbon from the substrate into their shells as evidenced by studies comparing the radiocarbon dates of shells and flesh from different species on different substrates (Dye 1994; Hogg et al. 1998). Limpet shells (Patella sp.) are commonly found in prehistoric midden deposits in the British Isles and elsewhere, however these shells have largely been avoided for radiocarbon dating in regions of limestone outcrops. Results from limpets (Patella vulgata) collected alive on limestone and volcanic substrates on the coasts of Ireland indicate that the shells were formed in equilibrium with the seawater, with no significant 14C offsets. Limpets collected from the east coast of Northern Ireland have elevated 14C due to the output of Sellafield nuclear fuel reprocessing plant. In all locations, the flesh was depleted in 14C compared to the shells. The results will have an important consequence for radiocarbon dating of midden deposits as well as the bone of humans and animals who fed on the limpets. [ABSTRACT FROM AUTHOR]

On Crete—as is common elsewhere in the Mediterranean—carbonate massifs form high mountain ranges whereas topography is lower in areas with meta‐clastic rocks. This observation suggests that differences in denudational processes between carbonate‐rich rocks and quartzofeldspathic units impart a fundamental control on landscape evolution. Here we present new cosmogenic basin‐average denudation rate measurements from both 10Be and 36Cl in meta‐clastic and carbonate bedrock catchments, respectively, to assess relationships between denudation rates, processes, and topographic form. We compare total denudation rates to dissolution rates calculated from 49 new and previously published water samples. Basin‐average denudation rates of meta‐clastic and carbonate catchments are similar, with mean values of ~0.10 mm/a and ~0.13 mm/a, respectively. The contribution of dissolution to total denudation rate was <10% in the one measured meta‐clastic catchment, and ~40% for carbonate catchments (~0.05 mm/a), suggesting the dominance of physical over chemical weathering at the catchment scale in both rock types. Water mass‐balance calculations for three carbonate catchments suggests 40–90% of surface runoff is lost to groundwater. To explore the impact of dissolution and infiltration to groundwater on relief, we develop a numerical model for carbonate denudation. We find that dissolution modifies the river profile channel steepness, and infiltration changes the fluvial response time to external forcing. Furthermore, we show that infiltration of surface runoff to groundwater in karst regions is an efficient way to steepen topography and generate the dramatic relief in carbonates observed throughout Crete and the Mediterranean. Key Points: Quantifying chemical and mechanical denudation in meta‐clastic and carbonate bedrockDominance on mechanical denudation in karstic terrainsDissolution and infiltration in carbonate terrains influence the shape and response of river profiles to external forcing [ABSTRACT FROM AUTHOR]

Clumped isotopes provide a theory‐based proxy to reconstruct formation temperatures of carbonates. With the introduction of the empirical transfer function (ETF) and several carbonate standards, interlaboratory comparison has become achievable. Due to the rare occurrence of the multiply substituted isotopologues, the analytical precision of these measurements is very low. In order to improve precision, we investigate the optimal strategy for the conversion into the absolute reference frame using a simulation approach. We find that changing the relative proportions of the standards to include more standards that are closer to the unknown target Δ47 value can greatly improve attainable precision. The inclusion of a hypothetical 4 °C standard results in only modest improvements in final temperature estimates for Earth surface temperature (0 and 40 °C) samples, indicating that the set of ETH‐1–3 standards is suitable for most applications. Full interpolation between two subsequent hypothetical standards, with Δ47 values of CO2 equilibrated at 1000 and 25 °C, results in modest improvements for samples with extreme Δ47 values. With a more optimal distribution of standards it is possible to measure more sample replicates before the uncertainty derived from the ETF becomes limiting. We provide suggestions for the optimal distribution of standards for all target sample Δ47 values and the R code to perform these simulations based on different laboratory settings. These optimizations can also be applied for ETFs using heated and equilibrated gases. We demonstrate numerically how optimizing the distribution and relative abundance of standards can increase measurement precision. Plain Language Summary: Carbonate clumped isotope measurements are a tool to reconstruct the temperature at which a carbonate has formed. Recent studies suggest that repeated measurements of carbonate standards allow for greater interlaboratory consistency and higher accuracy of measurements. In this study we demonstrate that the relative proportion of these standards should be changed to include more standards that are similar to the target clumped isotope composition of the unknown sample. We quantify how the composition of the standards used in a measurement session influences the measurement precision, based on simulations. Key Points: Measuring relatively more standards that are similar in Δ47 to the target sample improves precisionWith an optimal distribution of standards, the number of sample versus standard replicates should be approximately equal per session for smallest uncertaintiesAdding standards with extreme Δ47 values to the ETH‐1–3 set would lead to only minor error reduction at extreme Δ47 values [ABSTRACT FROM AUTHOR]

Changes may be occurring in the carbonate chemistry of fjords due to natural and anthropogenic disturbance of major freshwater sources. We present a high‐frequency time series study of seasonal pH and CO2 partial pressure (pCO2) in a north Patagonian fjord with a focus on changes in freshwater inflows and biological processes. To do this, we monitored pH and pCO2 in situ, along with river streamflow, salinity, temperature, and dissolved oxygen (DO) in the Reloncaví Fjord (41.5°S) for a full year (January to December 2015). Strong seasonal variability was observed in the pCO2, pH, and DO of the fjord's surface waters. During the summer, pCO2 reached its annual minimum (range: 187–571 μatm) and pH its maximum (range: 7.98–8.24), coinciding with lower freshwater inflows (204–307 m3/s) and high DO (280–378 μmol/kg), as well as aragonite saturation states (ΩArag) higher than 1. In contrast, in winter, pCO2 ranged from 461–1,008 μatm and pH from 7.57–8.03, coinciding with high freshwater inflows (1,049–1,402 m3/s), lower oxygen (216–348 μmol/kg), and constant undersaturation of ΩArag. Reloncaví Fjord had an annual air‐water CO2 flux of 0.716 ± 2.54 mol·m−2·year−1 during 2015 and thus acted as a low emission system. The annual cycle was mainly governed by seasonal changes in biological processes that enhanced the shift from a CO2 sink in late spring and summer, caused by high primary production rates, to a CO2 source during the rest of the year caused by high community respiration due to allochthonous organic carbon inputs. Key Points: North Patagonian fjords are aquaculture‐heavy used environments, and there are not available data for understanding major biogeochemical process like air‐sea CO2 fluxes and aragonite saturationA high‐frequency time series of the annual cycle of CO2, pH, and dissolved oxygen in a north Patagonian fjord is evaluatedThe fjord inorganic carbon cycle is very dynamic, primarily driven by varying contributions from primary production and respiration of allochthonous organic carbon [ABSTRACT FROM AUTHOR]

In this interdisciplinary paper, we study the formation of iron precipitates – the so-called Liesegang rings – in Lecce stones in contact with iron source. These phenomena are responsible of exterior damages of lapideous artifacts, but also in the weakening of their structure. They originate in presence of water, determining the flow of carbonate compounds mixing with the iron ions and then, after a sequence of reactions and precipitation, leading to the formation of Liesegang rings. In order to model these phenomena observed in situ and in laboratory experiments, we propose a modification of the classical Keller–Rubinow model and show the results obtained with some numerical simulations, in comparison with the experimental tests. Our model is of interest for a better understanding of damage processes in monumental stones. [ABSTRACT FROM AUTHOR]

A denser CO2 atmosphere and higher temperatures than present‐day conditions are frequently invoked as prevailing conditions for the formation of some ancient hydrous mineralogical associations present at the surface of Mars. The environmental conditions are of particular interest to better understand and constrain the weathering processes of the early Martian crust. For this purpose, 6‐month‐long batch weathering experiments on Martian crust simulants and individual Martian mineral analogs were performed at low temperature (45 °C) under a dense CO2 atmosphere (1 atm). Constraints on the weathering conditions are deduced from the solution properties and thermodynamic calculations, as well as mass balance calculations. Experimental solutions vary from mildly acidic to near neutral (4.75–6.48 pH). The Eh‐pH conditions (Eh from 0.189–0.416 V/standard hydrogen electrode) suggest favorable conditions for the formation of ferric minerals despite an anoxic CO2 atmosphere. The chemical weathering appears to be 4 times more intense for Martian simulants under a CO2 atmosphere than under Earth ambient air. The weathering trend under a CO2 atmosphere involves leaching of alkali and alkaline earth elements (Mg, Ca, Na, and K) and Si and enrichments of the solid phases in Al, Fe, and to a lesser extent Si compared to the initial chemical composition of the starting minerals. This geochemical partitioning between solution and solids resembles those deduced from weathering profiles on Earth. Our results strongly support the idea that carbonates could not have extensively formed at the surface of early Mars despite a dense CO2 atmosphere. Plain Language Summary: Mars orbital and landed missions have provided mineralogical, morphological, and field evidence for liquid water at the surface approximately 3.5 billion years ago. The chemical and mineralogical composition of the Martian rocks have potentially been modified by interaction with this liquid water. The purpose of our study is to use laboratory experiments to constrain the physicochemical conditions of water resulting from the chemical weathering of Martian crust simulants under an atmosphere composed of carbon dioxide, as is the case for Mars. The water in contact with simulants is mildly acidic. The partitioning of chemical elements between the solution and minerals is similar to what is observed on Earth, but weathering is more intense. Despite that Mars had a primitive CO2‐dense atmosphere, the conditions were not favorable to the extensive formation of carbonate at the surface. Key Points: Chemical weathering in mildly acidic conditions under a CO2 atmosphere yielded leaching of alkali and alkaline earth elementsMass balance calculations indicated Al, Fe, and Si enrichment in the weathering productsOur results imply unsuitable conditions for carbonate formation despite CO2 in the Martian atmosphere [ABSTRACT FROM AUTHOR]

Highlights • Authigenic marine carbonates along Japan margins present equilibrium Δ 47 signatures. • Pore water δ 18 O at the time of precipitation is estimated by Δ 47 thermometry. • Carbonates were formed during glacial and/or hydrate destabilization periods. • Disequilibrium Δ 47 is likely related to rapid rates of anaerobic methane oxidation. Abstract The chemical and stable isotopic composition of methane-derived authigenic carbonate (MDAC) can be used to document paleoclimate and biogeochemical information in methane cold seeps, such as temperature records determined through clumped isotope (Δ 47) analyses. Previous investigations of MDACs, however, have noted isotopic disequilibrium values, limiting the application of Δ 47 signatures as a proxy for the formation temperature of carbonates at present and former gas seep sites. Here we measured 49 MDAC samples collected from 5 areas along the Eastern margin of the Japan Sea and the northwest Pacific region of Japan. All samples present equilibrium Δ 47 signatures with respect to seafloor temperatures at the time of precipitation, and the results do not appear to be influenced by the Mg content, mineralogy or mixing effect. The pore water δ 18 O values estimated by the Δ 47 thermometer reveal that most of these MDACs formed during glacial and/or hydrate destabilization periods. While our new data shows equilibrium Δ 47 values, the results do not discount the possibility that disequilibrium observed in previous studies could possibly be associated with extremely rapid rates of anaerobic oxidation of methane. Relevant potential mechanisms are discussed. Further investigations are crucial to clarify the utility of Δ 47 in MDACs as a novel proxy for constraining the modern/ancient methane seep environment. This proxy also offers insights into formation and dissociation processes of gas hydrate, a potential energy resource in the future. [ABSTRACT FROM AUTHOR]

The Weiyuan Structure is the largest surface structure in the Sichuan Basin. However, the abundance of the Dengying Formation gas reservoir in the Weiyuan Structure is low. The height of the gas column is 244 m, but the integrated abundance is only 26.4%. After nearly 40 years of exploration, the Gaoshi1 Well and Moxi8 Well yielded gas flows that marked an important exploration success after the discovery of the Sinian Dengying Formation gas reservoir in the Weiyuan Structure, Sichuan Basin, Lower-Paleozoic in 1964. Combined with research examples of oil and gas migration and gas chimneys around the world, the authors used comprehensive geological-geophysical-geochemical research methods to provide a reasonable explanation of the low abundance of the gas reservoir in the Weiyuan Structure based on the surface and subsurface data. The latest research results show that (1) currently, the Weiyuan Structure is the apex of the Dengying Formation in the Mid-Sichuan Basin. The Guang'an, Longnüsi, Gaoshiti-Moxi, and Weiyuan structures are a series of traps in the Dengying Formation with gradual uplifting spill and closure points during the regional uplift of the Himalayan period. The natural gas of the Dengying Formation accumulated in different ways over a wide range and long distance in the Sichuan Basin. (2) At approximately 40 Ma, the Weiyuan area started to uplift and form the present structure, and it is the only outcropped area with the Triassic Jialingjiang Formation and Leikoupo Formation in the surface of the Sichuan Basin (except the steep structural belt in East Sichuan). Caused by the uplift and denudation, the core of the Weiyuan Structure has formed an escaping "skylight" for natural gas. The evidence of a gas chimney includes (1) the component percentage of non-hydrocarbon gas, which decreased from the bottom to the top, (2) the pressure coefficient is normal because the gas reservoir from the Upper Sinian to the Lower Permian commonly have a normal pressure coefficient (an average of 1.0), and (3) the isotope geochemistry of the argon mostly represents abiogenic characteristics of a deep source, and the 40Ar/36Ar ratio is as high as 2 855–5 222 in the Upper Permian. All of these characteristics provide sufficient evidence for a gas chimney effect. The characteristics of low abundance in the Weiyuan Structure can be a reference example for studying the late reconstruction of deep oil and gas reservoirs in the superimposed basins of western China. [ABSTRACT FROM AUTHOR]

Rock aggregates are the most fundamental material of highway, railroad, and other construction activities. The quality of rock aggregates for a given usage is determined by many different test methods, one of the most important of which is the Los Angeles abrasion (LAA) test as it is used to evaluate the resistance to abrasion and wear of aggregates for such applications as railroad ballast, base course material, and asphalt and concrete aggregates. In this study, the relationship between rock texture and LAA loss was investigated for 26 sources of carbonate aggregates found in Iran which constitute the most commonly quarried crushed rock. Regression analyses were used to determine whether rock texture was a useful predictor of LAA loss. The texture of rock aggregate was quantified by texture coefficient (TC), which can be used to put a value on rock texture with studies carried out on the rock thin section using image analysis. In addition, the effects of textural parameters including area weighting of grains or packing density, grain shape, grain elongation, circularity, and orientation of mineral grains, and also TC on the LAA loss were evaluated. Although the results show that weak relationships exist between textural parameters and LAA loss, a strong relationship exists between TC and LAA loss. The results indicate that many textural parameters, together with TC, can be interpreted as rock texture which influences the LAA loss. Also, the results indicate a strong negative correlation between LAA loss and TC, and can be used to predict LAA loss in practical applications. [ABSTRACT FROM AUTHOR]

Graphical abstract Citrate-functionalized calcium-doped europium phosphate nanoparticles were crystallized by thermal decomplexing of Ca2+/Eu3+/citrate/phosphate/carbonate solutions. The crystallization mechanism, luminescence properties and cytocompatibility of this class of nanoparticles were investigated. These biocompatible nanoparticles appear as promising luminescent probes in the field of bioimaging. Abstract Biocompatible nanosystems exhibiting long-lifetime (∼millisecond) luminescence features are particularly relevant in the field of bioimaging. In this study, citrate-functionalized calcium-doped europium phosphates nanophosphors of the rhabdophane type were prepared at different synthesis times by a bioinspired crystallization route, consisting in thermal decomplexing of Ca2+/Eu3+ /citrate/phosphate/carbonate solutions. The general formula of this material is Ca α Eu 1-α (PO 4) 1-α (HPO 4) α ·nH 2 O, with α ranging from 0 to 0.58 and n ∼ 1. A thorough characterization of the nanoparticles has been carried out by XRD (including data processing with Topas 6.0), HR-TEM, TEM, FTIR, TG/DTA, ICP, dynamic light scattering (DLS), electrophoretic mobility, and fluorescence spectroscopy. Based on these results a crystallization mechanism involving the filling of cationic sites with Ca2+ions associated to a concomitant adjustment of the PO 4 /HPO 4 ratio was proposed. Upon calcium doping, the aspect ratio of the nanoparticles as well as of the crystalline domains decreased and the relative luminescence intensity (R.L.I.) could be modulated. Neither the pH nor the ionic strength, nor the temperature (from 25 to 37 °C) affected significantly the R.L.I. of particles after resuspension in water, leading to rather steady luminescence features usable in a large domain of conditions. This new class of luminescent compounds has been proved to be fully cytocompatible relative to GTL-16 human carcinoma cells and showed an improved cytocompatibility as the Ca2+ content increased when contacted with the more sensitive m17. ASC murine mesenchymal stem cells. These biocompatible nanoparticles thus appear as promising new tailorable tools for biomedical applications as luminescent nanoprobes. [ABSTRACT FROM AUTHOR]

The IODP‐ICDP Expedition 364 drilled into the Chicxulub crater, peering inside its well‐preserved peak ring. The borehole penetrated a sequence of post‐impact carbonates and a unit of suevites and clast‐poor impact melt rock at the top of the peak ring. Beneath this sequence, basement rocks cut by pre‐impact and impact dykes, with breccias and melt, were encountered at shallow depths. The basement rocks are fractured, shocked and uplifted, consistent with dynamic collapse, uplift and long‐distance transport of weakened material during collapse of the transient cavity and final crater formation. [ABSTRACT FROM AUTHOR]

Abstract Inferring redox conditions for ancient marine environments is critical to our understanding of biogeochemical cycles over Earth history. Because of the redox sensitivity of cerium (Ce) relative to other rare earth elements (REEs) and its uptake in marine carbonates, the Ce anomaly (Ce/Ce*) is widely applied to ancient carbonates as a proxy for local redox conditions in the water column. However, carbonate sediments and rocks are particularly vulnerable to multiple stages and styles of post-depositional diagenetic alteration where the diagenetic redox conditions and fluid compositions can vary widely from overlying seawater. Evaluations of the effects of this post-depositional alteration for the Ce anomaly have mostly been limited to ancient carbonate rocks rather than recent, well-characterized analog facies. Here, we report on analyses of REE plus yttrium concentrations (REY) and Ce anomalies in bulk carbonate samples from drill cores collected in the Bahamas (Clino and Unda) that allow us to track loss or retention of primary signals of initial oxic deposition through a range of subsequent alteration scenarios mostly under anoxic conditions. Specifically, these materials have experienced well-constrained overprints linked to meteoric processes and marine burial diagenesis, including dolomitization. Our results show that, regardless of mineralogy, diagenetic fluid composition, and redox state, the REY patterns in these carbonates, including the Ce anomaly, are similar to those of modern oxic seawater, indicating that they likely record the seawater signatures of primary deposition. As such, the Ce anomaly in shallow marine carbonates has the potential to preserve records of primary deposition even when subject to multiple stages and styles of diagenetic alteration, confirming its utility in studies of ancient marine redox. [ABSTRACT FROM AUTHOR]

Pedogenic carbonate is commonly used as a paleoarchive, but its interpretation is limited by our understanding of its formation conditions. We investigated laminated soil carbonate rinds as a high‐resolution paleoarchive in Torrey, Utah, USA, by characterizing and modeling their formation conditions. We compared late Holocene (<5 ka) soil carbonate conventional (C and O) and "clumped" isotopes to modern soil environment and isotope measurements: soil CO2 partial pressure, soil temperature, soil moisture, δ13C‐soil CO2, δ18O precipitation, and δ18O‐soil water. Data unambiguously identified a strong summer seasonality bias, but modeling suggested soil carbonate formed several times throughout the year during infiltration events causing dissolution‐formation reactions. This apparent discrepancy resulted from preferential preservation of calcite formed from the largest annual infiltration events (summer) overprinting previously formed calcite. Soil carbonate therefore formed predominantly due to changes in soil water content. As soil CO2 was at its annual maximum during soil carbonate formation, assuming uniformly low soil CO2 formation conditions for soil carbonate in estimating paleoatmospheric CO2 is likely not viable. Additionally, we showed modern summer δ13C‐soil CO2 and soil CO2 measurements could not produce a modeled δ13C‐soil carbonate consistent with late Holocene observations. We suggest using multiple lines of evidence to identify nonanalogous modern conditions. Finally, a nearly linear radiocarbon age model from a laminated rind showed that rinds can be used as a high‐resolution paleoarchive if samples are from a single depth and the timing and conditions of soil carbonate formation can be constrained through time. Key Points: At Torrey, UT, comparison between modern soil and late Holocene soil carbonate isotopes shows soil carbonate forms during the summerSummer formation seasonality occurs because calcite dissolution‐formation reactions during infiltration events overprint prior materialTorrey soil carbonate rinds are suitable material for high‐resolution paleorecords as proxies of summer soil and vegetation conditions [ABSTRACT FROM AUTHOR]

Highlights • Solids concentration and solids velocitiy were measured inside large scale CFB reactors. • Measurements were conducted during carbonate looping and combustion test campaigns. • A large influence of bed material characteristics on particle flow was determined Abstract A water-cooled dual-channel capacitance probe system was developed for in-furnace measurements of solids concentration and solids velocity in a 1 MW th dual fluidized bed pilot plant. Measurements were conducted in both reactors of the pilot plant during carbonate looping and combustion test campaigns. Solids velocities were derived by cross correlating the signals of the two channels of the capacitance probe. Thus, horizontal profiles of solids concentration and velocity were simultaneously determined in the reactors. These profiles show a strong core annulus flow structure in both reactors of the pilot plant. The influence of bed material characteristics, operating conditions as well as riser geometries on the particle flow structure is evaluated. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Application of a new green surfactant is investigated for the first time regarding chemical EOR. • Impact of the presented surfactant on IFT reduction and wettability alteration is examined. • Effects of salt on IFT reduction and CMC values are demonstrated. • Carbonate and sandstone rocks are utilized for the purpose of wettability alteration tests. • Secondary and tertiary oil recovery schemes are implemented on carbonate rocks to quantitatively compare their efficiency. Abstract Surfactant injection is an important chemical enhanced oil recovery (EOR) technique with beneficial impacts for oil recovery from subsurface reservoirs due to interfacial tension (IFT) reduction and wettability alteration. However, most of the available or proposed synthetic surfactants have negative environmental impacts. Here, a novel synthesis procedure of an amino-acid based (non-toxic; easily biodegradable) surfactant is described and its application for chemical EOR is rigorously tested using IFT, wettability and coreflooding experimental tests. The effect of salinity on the IFT reduction highlights the potential impact of injection water salt concentration on its performance. Two sets of carbonate and sandstone rock samples are used for wettability alteration tests. Two displacement tests quantitatively assess the performance of the proposed surfactant during injection as part of secondary and tertiary recovery schemes. The synthesized amino-acid based surfactant demonstrates good synergy with appropriate injection water salt concentrations. The wettability test results suggest that both sandstone and carbonate reservoir rocks would potentially benefit when subjected to chemical EOR using this surfactant. Comparisons between secondary and tertiary surfactant flooding schemes suggest that the surfactant is potentially more effective during secondary injection. [ABSTRACT FROM AUTHOR]

Abstract The origin of sedimentary dolomite is a subject of long-standing enigma that still awaits resolution. Previous studies have shown that room temperature synthesis of abiotic dolomite is rarely achieved and primary (proto-)dolomite precipitation is closely associated with microbial activities. In this study, we demonstrate through laboratory carbonation experiments that highly negative-charged clay minerals (as indicated by the values of zetal potential) such as illite and montmorillonite can aid the precipitation of abiotic proto-dolomite under ambient conditions, whereas nearly-neutral charged kaolinite exerts negligible influence on such process. In comparison to montmorillonite, illite has higher surface-charge density, thus is more effective in catalyzing proto-dolomite precipitation. Furthermore, the signal of proto-dolomite in carbonate neoformations is enhanced with increasing concentrations of illite or montmorillonite. On the basis of these results, we suggest that clay minerals catalyze dolomite formation perhaps via electrostatic binding of Mg2+ and Ca2+ ions and simultaneous desolvation of these strongly hydrated cations, a crucial step for dolomite crystallization. The resulting proto-dolomites display the morphologies, textures, and structures similar to those of biogenic dolomite reported before, which are considered precursors of ordered sedimentary dolomite. Therefore, our results offer a possible route to authigenic dolomite found in sedimentary environments. [ABSTRACT FROM AUTHOR]

Abstract Carbonate escarpments are submarine limestone and dolomite cliffs that have been documented in numerous sites around the world. Their geomorphic evolution is poorly understood due to difficulties in assessing escarpment outcrops and the limited resolution achieved by geophysical techniques across their steep topographies. The geomorphic evolution of carbonate escarpments in the Mediterranean Sea has been influenced by the Messinian salinity crisis (MSC). During the MSC (5.97–5.33 Ma), the Mediterranean Sea became a saline basin due to a temporary restriction of the Atlantic-Mediterranean seaway, resulting in the deposition of more than one million cubic kilometres of salt. The extent and relative chronology of the evaporative drawdown phases associated to the MSC remain poorly constrained. In this paper we combine geophysical and sedimentological data from the central Mediterranean Sea to reconstruct the geomorphic evolution of the Malta Escarpment and infer the extent and timing of evaporative drawdown in the eastern Mediterranean Sea during the MSC. We propose that, during a MSC base-level fall, fluvial erosion formed a dense network of canyons across the Malta Escarpment whilst coastal erosion developed extensive palaeoshorelines and shore platforms. The drivers of geomorphic evolution of the Malta Escarpment after the MSC include: (i) canyon erosion by submarine gravity flows, with the most recent activity taking place <2600 cal. years BP; (ii) deposition by bottom currents across the entire depth range of the Malta Escarpment; (iii) tectonic deformation in the southern Malta Escarpment in association with a wrench zone; (iv) widespread, small-scale sedimentary slope failures preconditioned by oversteepening and loss of support due to canyon erosion, and triggered by earthquakes. We carry out an isostatic restoration of the palaeoshorelines and shore platforms on the northern Malta Escarpment to infer an evaporative drawdown of 1800–2000 m in the eastern Mediterranean Sea during the MSC. We interpret the occurrence of pre-evaporite sedimentary lobes in the western Ionian Basin as suggesting that either evaporative drawdown and canyon formation predominantly occurred before salt deposition, or that only the latest salt deposition at the basin margin occurred after the formation of the sedimentary lobes. Highlights • We reconstruct the geomorphic evolution of the Malta Escarpment. • During MSC, subaerial and coastal erosion formed canyons and palaeoshorelines. • Gravity flows, bottom currents and tectonic deformation shaped escarpment after MSC. • We infer a drawdown of 1800–2000 m in the eastern Mediterranean during MSC. [ABSTRACT FROM AUTHOR]

The electrochemical performance of SiO-SnCoC composite anode for high-energy lithium-ion batteries was evaluated with particular emphasis on the impact of Alginate as a polymeric binder, as well as fluoroethylene carbonate (FEC) as electrolyte additive. It was found that the presence of FEC and the use of alginate pH 3 as binder help to improve the electrochemical stability of the composite anode, showing the best electrochemical performance with a high specific capacity, great capacity retention, and excellent coulombic efficiency. Particularly, the high precision self-discharge current study revealed that the alginate binder slowed down the parasitic reactions between the lithiated anode and the non-aqueous electrolyte. [ABSTRACT FROM AUTHOR]

Abstract The partitioning of REE,Y and Sc (R3+) between olivine and melt has been investigated experimentally during basalt-carbonate interaction. Three synthetic basalts (meltMg# 72 , meltMg# 75 and meltMg# 78) were doped with 0, 10 and 20 wt% CaCO 3 and then equilibrated for 72 h at 1 atm, 1,150, 1,200 and 1,250 °C, and the QFM oxygen buffer. The thermal decomposition of CaCO 3 produced CaO contents in the melt up to ~22 wt%. Regular relationships are found between the ionic radius and the partition coefficient (D R 3+), showing typical near-parabolic patterns. D R 3+ is weakly dependent on temperature, but decreases with increasing CaCO 3 in the starting material (e.g., D Sc decreases from 0.20 to 0.13). From the point of view of the lattice strain theory, D R 3+ is described in terms of the radius of the crystal site (r 0), the Young Modulus (E) due to the elastic response of that site to lattice strain caused by cation insertion, and the strain-free partition coefficient (D 0 3+). The value of r 0 decreases as Ca cations are accommodated into the more distorted M2 site of olivine via progressive Ca Fe substitutions. This mechanism is accompanied by a higher proportion of Mg cations entering into the smaller M1 site, making the optimum ionic radius smaller and favoring the crystallization of more forsteritic olivines from decarbonated melts. The enrichment of Ca in the crystal lattice is also proportional to the number of Si and Ca cations available in the melt. This causes E to be anticorrelated either with Ca in olivine or the activity of CaO in the melt. R3+ cations behave as network modifiers and, during basalt-carbonate interaction, the increasing abundance of non-bridging oxygens enhances the solubility of REE, Y and Sc in the melt. As a consequence, D 0 3+ is negatively correlated with the degree of melt depolymerization. Additionally, the strain of the crystal lattice dominates the D R 3+ parabolic patterns and D 0 3+ is strongly controlled by forsterite and aluminium concentrations in olivine. The accommodation of REE, Y and Sc in the crystal lattice requires maintenance of local charge-balance by the generation of vacancies, in accord with a paired substitution of R3+ and a vacancy for Mg in octahedral sites. Highlights • REE, Y and Sc (D R 3+) partitioning between olivine and melt is investigated. • D R 3+ is experimentally quantified as a function of CaO. • D R 3+ decreases drastically with increasing CaO in the basaltic melt. • D R 3+ depends on both the degree of melt depolymerization and crystal structure. • The entry of R3+ in olivine is attained by generation of vacancies. [ABSTRACT FROM AUTHOR]

Highlights • Microbial induced carbonate precipitation is an effective soil stabilization method. • Geophysical methods useful to monitor subsurface changes due to soil stabilization. • Geophysical method induced polarization is spatially and temporally insightful. • Induced polarization (IP) is sensitive to formation/dissolution of minerals. • IP is a prime candidate to monitor microbial induced carbonate precipitation. Abstract Microbial induced carbonate precipitation (MICP) is a promising soil stabilization method performed by stimulating soil microbes that are naturally occurring and ubiquitous in soil systems. The precipitated carbonate acts as a cementation agent to bind loose soil at grain to grain contacts. MICP has been extensively tested and proven in laboratory environments, as well as in limited field trials; however, long term field applications still remain challenging, partly due to quality control and monitoring issues. Induced polarization (IP), an established geophysical method in mineral exploration, is a prime candidate for MICP monitoring and characterization. This study presents the geophysical results of a 15-day field-scale MICP project. The MICP treatment involved the injection of molasses (carbon source for microbial proliferation) and urea in a Ca2+ rich aquifer. IP monitoring successfully delineated, spatially and temporally, the propagation of MICP in the treatment area, while common resistivity measurements failed to capture any MICP related changes. Reduced hydraulic conductivity in the treatment area versus untreated area, further supports that MICP has changed the physical properties of the subsurface. Furthermore, conventional geochemical monitoring as well as X-ray diffraction analysis confirmed carbonate precipitation in samples from discrete wells in the treatment area. [ABSTRACT FROM AUTHOR]

The Eocene succession of the El Basatin Section in Gebel Mokattam, east of Cairo, consists, from base to top, of two main units; the Mokattam and Maadi Formations. The Mokattam Formation consists of two Members, the Building Stone Member and the Giushi Member. The Upper Building Stone Member yielded six species of Nummulites belonging to the Upper Lutetian. These species are: Nummulites farisi Hussein et al., 2004; Nummulites cf. praegizehensis Boukhary and Hussein‐Kamel, 1993; Nummulites cf. gizehensis (Forskål, 1775); Nummulites discorbinus (Schlotheim 1820) and Arxina schwageri (Silvestri, 1928) emended by Boukhary et al. 2012 and Nummulites crassichordatus Boukhary et al., 2010. The Giushi Member yielded three species that indicate a Bartonian age. These species, which continued from their first appearance in the Upper Building Stone Members, are N. discorbinus, A. schwageri and N. crassichordatus. The Maadi Formation, which has been previously considered to be of Bartonian–Priabonian age, is devoid of fossils in the study section. The two members of the Mokattam Formation represent a carbonate platform facies. The deposition of the Upper Building Stone Member was disturbed during the Lutetian by slumping and a convolute‐bedding interval, indicating a short hiatus. The subsequent regression resulted in a very shallow marine to near‐shore facies in the above Maadi Formation. [ABSTRACT FROM AUTHOR]

Abstract Carbonate platform islands are important landscape features in the northeastern part of the Okavango Delta region of Botswana, the Chobe Enclave. However, the formation processes and the timing of these "Chobe Islands" remain unclear. They are assumed to be the result of late Quaternary hydrological changes. Records of such changes are poorly preserved, though the occurrence of beach ridges in the Middle Kalahari Basin attests to the existence of large paleo-lakes in the past. Carbonate rocks from the Chobe Island appear to be relics of palustrine environments, but their relationship with the other hydrological archives is still unclear. Here, we report optically stimulated luminescence dating of key sedimentary beds in and around a single Chobe Island. It was necessary to model dose rate evolution for each sample individually, taking into account post-depositional changes in the sediment chemistry and its burial depth. The resulting ages suggest that the dated units were deposited between MIS6 to MIS1. The carbonate platform itself appears to have been deposited in two phases, separated by either an unexpectedly long (∼40 ka) depositional hiatus or an episode of erosion. This study demonstrates the potential of using luminescence dating in such settings, and offers the possibility of linking sedimentary processes within the Chobe Enclave to regional paleo-hydrological records. [ABSTRACT FROM AUTHOR]

Abstract The main island of New Caledonia (NC) is surrounded by the second largest barrier reef in the world after the Australian Great Barrier Reef. The Upper Pleistocene evolution of this barrier reef–lagoon complex offers the opportunity to examine the response of a modern mixed tropical siliciclastic/carbonate system to relative sea-level changes and to better constrain the relative role of lagoon backfilling and paleo-drainage system in sediment transfer across the shelf. This paper mainly focuses on the results of chronostratigraphic and sedimentological interpretations of new seismic, bathymetric and coring data collected in the SW NC lagoon. Several significant points are highlighted from this study and allow the construction of a refined model which includes the evolution of both the SW NC mixed shelf and lagoon. New results show that the NC lagoon has not recorded a reciprocal sedimentation during glacial-interglacial sea-level cycles but a unique mixed regime. Strong contrasts are observed and these depend above all on the two lagoon domains: the outer coral plateau and the inner lagoon depression corresponding to a semi-closed proximal basin which is separated from the plateau by a basement ridge. In the depression, clastic sediments remain dominant from early flooding to highstand stages while carbonate sedimentation continued through time across the coral plateau. This spatial contrast between terrigenous and carbonate deposits was maintained throughout various sea level cycles. Thus, even if spatial segregation is also observed for other examples of mixed shelf environments, the SW NC shelf appears quite unique in comparison to the other mixed systems when considering conceptual models of reciprocal sedimentation. Moreover, the presence of a semi-enclosed lagoon depression allows the preservation of larger volume of terrigenous deposits. This semi-filled geometry of the lagoon is assumed to be the result of several factors: a significant subsidence that offers accommodation for aggrading deposits, evacuation through channels of sediments mobilized during storm events, the tidal currents, and fairweather wave dynamics. Lastly, the inherited morphologic and structures may explain the geomorphic evolution of the "escarpment margin" type of the SW NC rimmed shelf and its differentiation with the opposite SE NC ramp type shelf. Highlights • A semi-filled lagoon geometry • Differs from general conceptual model of reciprocal sedimentation of mixed sliclastic/carbonate system • Strong spatial contrast between clastic inner lagoon depression and outer lagoon coral plateau [ABSTRACT FROM AUTHOR]

Abstract To better understand changes in vegetation and climate during the Last Glaciation in Southwest (SW) China, we studied microfossil assemblages in a peat/lake-sediment core collected in Tengchong Basin that spans the interval 66.6–11.8 ka (1 ka = 1000 cal yr BP), approximately equivalent to marine isotope stages (MIS) 4 to 2. The results show that patterns of climate change in Tengchong during the Last Glaciation were different from those in eastern China, and suggest that, compared with modern climates, SW China was cool and semi-humid during MIS 4, cold and semi-humid in the early and middle stages of MIS 3, and cool and humid in the late stage of MIS 3. During the Last Glacial Maximum (LGM), it was cool and dry, whereas after the LGM the climate remained dry but became warmer. Down-core changes in Abies and Picea pollen amongst the woody plants broadly match records of geochemical indices in parallel peat/lake-sediment cores and stalagmite oxygen isotope records from monsoonal Asia. Heinrich events 1–5 and volcanic eruption events are recognized in the Abies + Picea curve. As inferred from the microfossil assemblages in the Tengchong cores, the coldest interval in SW China during the Last Glaciation might not have been the LGM. Highlights • Microfossil data and geochemical indices are used and compared in rebuilding the paleoclimate in Tengchong. • Climate events Heinrich 1–5 are recognized from Abies + Picea curve. • The coldest period during the Last Glaciation in SW China might not be the traditional "LGM". [ABSTRACT FROM AUTHOR]

Abstract Sedimentological, paleontological, and geochemical data from core XK-1 in the Xisha Islands, South China Sea, allow a detailed documentation of the evolution of the reef-bank system from the early Pliocene to the late Pleistocene and of the aeolianite deposits from the late Pleistocene to the Holocene. A bank characterized by heterozoan carbonates occurred until 1.7 Ma. Between 1.7 and 0.2 Ma, the system turned into a reef dominated by photozoan carbonates. After 0.2 Ma, the aeolianite deposits, composed of heterozoan skeletal grains, occupied this area. A Pliocene to Pleistocene decrease in the abundance of planktonic foraminifera and some benthic foraminifer species generally associated with deep water settings indicates a long-term shallowing-upwards trend, resulting from the large-scale eustatic sea-level falls. Seven exposure horizons are recorded in core XK-1, due to high-frequency sea-level changes. The thickness of the reef body in the individual cycles increased after the Middle Pleistocene transition. This is interpreted as a consequence of the increase in duration of the short-term sea-level highstands. The formation of heterozoan aeolianite deposits after 0.2 Ma is probably caused by climate cooling, related with the intensification of East Asian winter monsoon. The rapid increase in coral abundance at ~1.7 Ma correlates well with a sharp decline in nutrient level, recorded by decreases in geochemical nutrient indexes values, declines in bryozoan and red algae (rhodolith) abundance, and decreases in the abundance of foraminifer species indicative of elevated nutrient-level. This correlation indicates that the carbonate factory turnovers were also affected by nutrient-level fluctuations, which could be linked to a paleoceanographic reorganization. These results demonstrate that together with sea-level fluctuations, also paleoceanographic changes had a significant effect on the Pliocene-Holocene tropical carbonate system. Highlights • Photozoan reef-bank system developed from 1.7 to 0.2 Ma in the Xisha Islands. • Thickness of reef units increased after the Middle Pleistocene transition. • Nutrient level in the Xisha Islands decreased after 1.7 Ma. • Heterozoan components after 0.2 Ma were caused by winter monsoon cooling. [ABSTRACT FROM AUTHOR]

Highlights • The binary mixtures of [C 2 mmim][NTf 2 ]/[C 4 mmim][NTf 2 ] + DMC/DEC were prepared. • The density and dynamic viscosity of the binary mixtures were measured. • The excess molar volumes and viscosity deviations were calculated. • The properties were discussed with the extension of the alkyl chain of the cation. Abstract Two hydrophobic ionic liquids (ILs) 1-alkyl-2, 3-dimethylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([C 2 mmim][NTf 2 ] and [C 4 mmim][NTf 2 ]) were synthesized. The binary mixtures of the two ILs were prepared with dimethyl carbonate (DMC) or diethyl carbonate (DEC) over the entire mole fraction range, respectively. The density and viscosity of the binary mixtures were investigated at temperature ranging from 293.15 to 328.15 K. The excess molar volumes and viscosity deviations were calculated for the four binary mixtures. The effects of the extension of the alkyl chain of the cation on the above properties are discussed. The Redlich-Kister equation was used for the fitting of the excess molar volumes and viscosity deviations versus mole fraction. The thermal expansion coefficients of the systems were obtained according to the density. [ABSTRACT FROM AUTHOR]

Abstract Carbonate reservoirs are characterized by strong permeability heterogeneity mainly linked to the predominant pore type. In this work, we present a case study focused on a shallow borehole (160 m depth) located at the eastern end of the Betic Cordillera, SE of Spain. This borehole sampled a marly seal (deep marine marls rich in planktonic organisms from Messinian – upper Tortonian) on top of a carbonate reservoir (algae limestone from Miocene - upper Tortonian). Laboratory analysis show that most of the samples from the reservoir correspond to grainstone and packstone limestone types, and that the quality of this reservoir is controlled mainly by its detritic composition and a high content of bioclasts. The aim of this work is to show the suitability of using standard geophysical logging to assess permeability supported by laboratory and Lugeon tests. Two approaches have been used based on Kozeny's equation (pseudo-k log) and Mari et al. (2011) work (Ik-Seis log). Both ways require obtaining specific surface which is an indicator of pore type. This calculation is based on porosity and Vp/Vs relations. Porosity has been obtained from resistivity and sonic logs constrained by laboratory measurements. Shear wave velocity has been inferred from Stoneley wave velocity since this formation is considered as slow (Vs lower than 1500 m/s). Pseudo-K and Ik-Seis logs have been scaled using the Lugeon tests results. Both logs reproduce the heterogeneities found in the in-situ test. Finally, an analysis of the dependence of different seismic attributes to the specific surface has been performed to check the suitability of using solely sonic measurements to assess permeability. This can be useful for boreholes were laboratory or field tests are not available. Highlights • Full Wave sonic constrained by standard lab measurements and Lugeon test can be useful to assess permeability in carbonates. • A combination of different seismic attributes can be also suitable to estimate permeability and detect permeable zones • Conventional logs can provide valuable information for reservoir characterization in a wide range of applications [ABSTRACT FROM AUTHOR]