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Highlights • An ultra diffusive leakage experiment was performed within a well at the subsurface of Saint Emilion pilot site. • The gas phase of CO 2 , CH 4 , He and Kr was monitored and quantified in the vadose zone. • Unlike the previous leakage experiments, the migration was mainly diffusive with no advective migration detected. • CH 4 , He and Kr were used as different type of tracers for CO 2 migration. • The analysis of CO 2 /He, CO 2 /Kr and CO 2 /CH 4 ratios showed that the vadose zone acted as a buffering zone. Abstract An ultra-diffusive leakage experiment was performed on the pilot site of Saint-Emilion near Bordeaux in France. It consisted in the injection of 85% CO 2 and 5% of each He, Kr and CH 4 in a vertical well with a very low injection pressure. This study allowed the development of an automated tool that continuously monitored the gas phase within the vadose zone. Measurements showed that the gas plume had a heterogeneous spatial and temporal variation. Mathematical calculations performed on the time series of the gas species showed that diffusive transport mainly occurred in the porous media. However, every stage of the migration could not be driven by diffusive process as shown by the exponential regression. A non-identified transport mechanism may have occurred during the increase of concentration. He was proven to be a suitable temporal tracer for a CO 2 leakage as it was a good temporal precursor. Even if the process was weaker than in the former injection experiments, Kr could show help foreseeing the extent of the gas plume within the pilot site. CH 4 was also shown to be an excellent temporal precursor of CO 2 arrival. The amount of gas migrating through the preferential path identified in the previous experiment was weaker than in the previous study. Moreover, the monitoring showed that a significant amount of injected gas migrated deeper in the vadose zone. The ratios CO 2 /Kr vs. CO 2 /He and the evolution of CO 2 /Kr, CO 2 /He and CO 2 /CH 4 put in evidence three groups of probes. The first consists in the subsurface probes and is characterized by a potential reactive transport of CO2 through the vadose zone such as gas dissolution in the aqueous phase. The second group gathers the closest probes to the injection point and underlines a very slow return to baseline value through diffusion. The third group is characterized by a competition between the process occurring in the first and second group. Isotopic measurement of Kr could not bring relevant information about the CO 2 fates into the vadose zone. However, it shows the possible presence of mechanism transport such as vertical flux and gravitational settlings. Observations from both of all the leakage experiment and future laboratory experiment could improve our understandings of the buffering zone and help to foresee CO 2 leakage for future storage site. [ABSTRACT FROM AUTHOR]

The present study deals with the soil gas geochemical surveys in and around Shanchiao fault to pick the sites for integrated radon monitoring using SSNTDs to better understand the response of tectonic activity of the fault systems. Throughout these surveys, gathered samples of soil gas has been analysed for radon and carrier gases namely CO2, He, N2, O2, CH4 and Ar. The RAD 7 instrument has been utilized for radon analysis and gas chromatograph instrument for analysing the carrier gases. The predominance of gas spread has been explored based on the results of these surveys and three sites have been chosen for integrated observation with regard to seismotectonic activity to examine the affectability of the sites utilizing SSNTDs. From these sites, a site will be chosen for future long duration continuous observance on the premise of its affectability towards the seismotectonic activity inside the territory. [ABSTRACT FROM AUTHOR]

The early life history of many marine organisms includes a dispersive planktonic larval phase which allows for the exchange of individuals among subpopulations. Knowledge of the degree of exchange, or connectivity, is critical to understanding the abundance and distribution of marine populations. Here, we applied geochemical tagging to assess estuarine‐scale larval connectivity among subpopulations of the commercially and ecologically important eastern oyster, Crassostrea virginica. To generate an "atlas" of geochemical signatures associated with spawning sites and potential dispersal pathways from spawning sites, we outplanted recently spawned oyster larvae to stationary moorings and surface drifters, respectively. Using the atlases generated from both outplant methods, we predicted natal origin, and thus larval connectivity, for newly settled oysters (spat) during three field trials over two summers (June 2013, June 2014, and August 2014), within three regions (∼ 35 km × 15 km quadrants) of Pamlico Sound, North Carolina, U.S.A. Patterns of larval connectivity varied both between months and annually but were predominately directed south to north following wind patterns. Predicted self‐recruitment was variable, as up to 100% of spat in a given region displayed signatures consistent with natal origin within that same region. Predicted connectivity patterns varied significantly based on atlases generated from outplanting on stationary moorings vs. surface drifters. For example, drifter‐predicted connectivity followed biophysical larval dispersal models more closely than mooring‐predicted connectivity, while mooring‐predicted connectivity displayed a higher diversity in larval sources. Both connectivity models highlight the need for resource management strategies such as reserve networks to incorporate designs that account for inherent variability in dispersal pathways. [ABSTRACT FROM AUTHOR]

Systematic grid-based soil geochemical baseline surveys have been undertaken in the South Island since 2013 at regional scales in Southland, Otago, Buller, Nelson and Marlborough and more detailed scales such as in Dunedin City and Nelson’s Richmond Range. More than 1300 sites and 3000 samples have now been analysed for their chemical element composition, supported by rigorous quality control procedures. The initial data interpretation shows strong underlying rock control on soil chemistry and localised anthropogenic input, principally in urban areas and through fertiliser application in higher intensity farming areas. The technical success and potential multi-use application of these surveys provide an argument for undertaking a national systematic geochemical baseline survey designed around international best practice. [ABSTRACT FROM AUTHOR]

The northeastern Tibetan Plateau began to grow during the Eocene and it is important to understand the climatic history of Asia during this period of so-called ‘doubthouse’ conditions. However, despite major advances in the last few decades, the evolutionary history and possible mechanisms of Eocene climate change in the northeastern Tibetan Plateau remain unclear. The Xining Basin in the northeastern Tibetan Plateau contains a continuous sequence of Early to Late Eocene non-marine sediments which provides the opportunity to resolve long-term climate changes during this period. In this study, we report the results of analyses of lithofacies, sediment color and geochemistry of bulk samples collected from the Xijigou section of the Xining Basin. An abrupt lithofacies change between the Early (∼52-40 Ma) and Late Eocene (∼40-34 Ma) indicates a change in the depositional environment from a shallow lake to a playa lake in response to a significant climatic shift. During ∼52-40 Ma, higher values of sediment redness (a*), redness/lightness (a*/L*) and higher modified Chemical Index of Weathering (CIW’) indicate a relatively warm and humid climate, while from ∼40-34 Ma the lower values of a*, a*/L* and lower CIW’ imply sub-humid to semi-arid climatic conditions. The paleoclimatic records indicate a long-term (∼52-34 Ma) trend of decreasing chemical weathering, consistent with global climate change. An abrupt sharp excursion of the proxy records during ∼42-40 Ma suggests a relatively brief warm interval, corresponding to the Middle Eocene Climatic Optimum (MECO). We suggest that global cooling substantially reduced humidity in inner Asia, resulting in sub-humid to semi-arid climatic conditions after 40 Ma in the Xining Basin, which may have been responsible for the long-term trend of decreasing chemical weathering during the Eocene. [ABSTRACT FROM AUTHOR]

Copyright of Geochimica Brasiliensis is the property of Sociedade Brasileira de Geoquimica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Geochimica Brasiliensis is the property of Sociedade Brasileira de Geoquimica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Geochimica Brasiliensis is the property of Sociedade Brasileira de Geoquimica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Geochimica Brasiliensis is the property of Sociedade Brasileira de Geoquimica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Geochimica Brasiliensis is the property of Sociedade Brasileira de Geoquimica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract: Currently, most of the archaeological sites on the western Urals (Russian Federation) are heavily destroyed by plowing. Archaeological excavations on the entire area of large monuments, such as medieval rural settlements, are impossible, while local excavations do not provide enough information about the boundaries and layout of the monument as a whole. To obtain more complete information about the site a new approach is proposed, which includes a comprehensive application of non‐destructive nearsurface geophysical and geochemical studies. This approach was applied for the first time in Russia on the Cushman‐3 rural settlement. In the study resistivity, magnetometry, and electrical resistivity tomography (ERT) surveys of the site were consistently applied. As a result, the borders of preserved cultural layers and the thickness in different parts of the site were established. Previously unknown defensive structures in the form of ditches and ramparts, as well as the features of the proper layout were found. Therefore, in most informative sites within the settlement, the soil was drilled using an auger sampler and soil cores were studied for morphological and chemical properties. This made it possible to verify the presence of defensive structures and to study the properties of cultural layers, fillings of the ditches and pits. Soil science techniques allowed us to find the cultural layers outside the ditches, as well as to establish the causes of the destruction of buildings. The combined application of methods of geophysics and soil science made it possible to separate ‘archaeological’ geophysical anomalies from the underlying rocks heterogeneities, which can give ‘false’ anomalies under geophysical surveys. Thus, the consistent application of geophysical and geochemical surveys enables to obtain the most complete (for the non‐destructive study) information about the site, providing high‐speed research and a high degree of reliability of the results due to clarification of the consistent data with minimal volumes of archaeological excavations. [ABSTRACT FROM AUTHOR]

A 3‐year survey has been performed in the Cévennes mountain area, in the South of France, in order to separate surface, shallow sub‐surface and groundwater contributions to the flash flood processes. Electrical conductivity, temperature, pH, major and trace elements, total organic carbon and stable isotopes of water were monitored during low flows and floods, in the small (3.9 km2) granitic catchment of Valescure (Gard, France). The data collected during the campaign are widely presented, in relation to the different hydrological compartments (rainfall, shallow soil water, groundwater, streamwater). This constitutes at present the most complete hydrogeochemical database in the Cévennes area, available within the Hymex data base https://mistrals.sedoo.fr/HyMeX/(Valescure chemistry and water isotopes), DOI of the referenced dataset:https://doi.org/10.6096/MISTRALS-HyMeX.1406. Open Practices: This article has earned an Open Data badge for making publicly available the digitally‐shareable data necessary to reproduce the reported results. The data is available at DOI 10.6096/MISTRALS-HyMeX.140657. Learn more about the Open Practices badges from the Center for Open Science: https://osf.io/tvyxz/wiki. [ABSTRACT FROM AUTHOR]

This work presents the results of geochemical (LA-ICP-MS) study of minerals of peridotites from ophiolite complexes of the Polar Urals to clarify the nature of these formations. The distribution of trace and rare earth elements in clinopyroxenes testifies that there were three types of the mantle substratum, which formed in different geodynamic settings. Two types of primary peridotites were formed upon partial melting of the mantle at different-depth levels in the subduction zone. The first type is represented by lherzolites and diopside harzburgites, formed at partial melting under the spinel facies conditions; the second type is represented by diopside harzburgites, formed under polybaric partial melting under the garnet and spinel facies conditions. In the suprasubduction zone, peridotites experienced fluid-induced partial melting that resulted in crystallization of harzburgites. All types of harzburgites were transformed by ascending melts and fluids (refertilization) and high-temperature hydration with the formation of amphibole. These processes are recorded in variations in the REE spectra of minerals. [ABSTRACT FROM AUTHOR]

Big data analytics brings a novel way for identifying geochemical anomalies in mineral exploration because it involves processing of the whole geochemical dataset to reveal statistical correlations between geochemical patterns and known mineralization. Traditional methods of processing exploration geochemical data mainly involve the identification of positive geochemical anomalies related to mineralization, but ignore negative geochemical anomalies. Therefore, the identified geochemical anomalies do not completely reflect the sought geochemical signature of mineralization, leading to uncertainty in geochemical prospecting. In this study, data for 39 geochemical variables from a regional stream sediment geochemical survey of southwest Fujian Province of China were subjected to big data analytics for identifying geochemical anomalies related to skarn-type Fe polymetallic mineralization through deep autoencoder network. The receiver operating characteristic (ROC) and areas under curve (AUC) were applied to evaluate the performance of big data analytics. The AUC of the anomaly map obtained using all the geochemical variables is larger than the AUC of the anomaly map obtained using only five selected elements known to be associated with the mineralization (i.e., FeO, Cu, Pb, Zn, Mn). This indicates that big data analytics, with the support of machine learning methods, is a powerful tool for identifying multivariate geochemical anomalies related to mineralization. [ABSTRACT FROM AUTHOR]

This paper presents the results of study of seismically induced variations in helium concentration in groundwater in the southern Baikal region. Unlike previous studies, data were obtained not only in Baikal deepwater but also in artesian wells in the southern Baikal region. The correlation coefficients between the data obtained at these observation stations, indicator functions, and an integrated indicator functions were calculated. They provide an objective assessment of time variations in concentrations due to changes in the stress-strain state of the Earth’s crust related to earthquake preparation and hence permit one to predict the time of an earthquake. [ABSTRACT FROM AUTHOR]

Exploiting geothermal (GT) resources requires first and foremost locating suitable areas for its development. Remote sensing offers a synoptic capability of covering large areas in real time and can cost effectively explore prospective geothermal sites not easily detectable using conventional survey methods, thus can aid in the prefeasibility stages of geothermal exploration. In this paper, we evaluate the techniques and approaches used in literature for the detection of prospective geothermal sites. Observations have indicated that, while thermal temperature anomalies detection have been applicable in areas of magmatic episodes and volcanic activity, poor resolution especially from space borne data is still a challenge. Consequently, thermal anomalies have been detected with some degree of success using airborne data, however, this is mostly in locations of known surface manifestations such as hot springs and fumaroles. The indirect identification of indicator minerals related to geothermal systems have been applied using multispectral and hyperspectral data in many studies. However, the effectiveness of the techniques relies on the sophistication and innovative digital image processing methods employed to sieve out relevant spectral information. The use of algorithms to estimate land surface temperature and heat fluxes are also applied to aid thermal anomaly detection, nevertheless, remote sensing techniques are still complementary to geologic, geophysical and geochemical survey methods. While not the first of its kind, this review is aimed at identifying new developments, with a focus on the trends and limitations intrinsic to the techniques and a look at current gaps and prospects for the future. [ABSTRACT FROM AUTHOR]

The Marahiq area represents a portion of the Pan-African belt from the Neoproterozoic age in south Egypt and includes metamorphosed ultramafic rocks, metavolcanic rocks, and granodiorite pluton. The area is characterized by the ancient abandoned Au mine and the recent active talc mines. The present paper provides a preliminary assessment of stream sediments for gold (Au) placer and environmental hazard. Steam sediments from 36 stations were analyzed using ICP-MS for determining the concentration of 53 elements. Various statistical techniques, graphical representations, a set of complementary sediment quality assessment methods, and different mapping methods have been applied. The results showed that Au and the investigated elements were influenced by long history of the ancient mining activities and weathering processes, leading to elevate Au and some heavy metal(loid)s concentrations and exhibit enrichment ratios as follows: Te > As > Au > Cu > Cd > Co > Ni > V. Whereas Cd, Co, and V were attributed to geogenic origin, As, Au, Cu, Ni, and Te were derived from anthropogenic mining activities. It is found that the anomalies of Au and the element of interest are indicative of Au placer and point out a new perspective Au-sulfide mineralization hosted along the favorable tectonic zones that were the main source of Au placer. Both As and Te are good pathfinders to explore Au placer and related mineralization. Environmentally, the excess of As, Cu, Ni, and Te could generate moderate levels of contamination and low level of ecological risk in the sediments. Although As, Cu and Ni posed medium-low potentially adverse effects and low toxicity levels, they cannot cause harmful influences on biological life. Accordingly, streambed sediments are considered as safe and acceptable as inoffensive materials for environmental management. Overall, this study is as reference values for governmental organizations for appraising future environmental pollution in the area. Also, it is fruitful for Au placer and promising with success for Au exploration along the shear zones and strike-slip faults. [ABSTRACT FROM AUTHOR]

The Chinese Continental Scientific Drilling (CCSD) main hole is located in the Sulu ultrahigh-pressure metamorphic (UHPM) belt, providing significant opportunities for studying the metamorphic strata structure, kinetics process and tectonic evolution. Lithology identification is the primary and crucial stage for above geoscientific researches. To release the burden of log analyst and improve the efficiency of lithology interpretation, many algorithms have been developed to automate the process of lithology prediction. While traditional statistical techniques, such as discriminant analysis and K-nearest neighbors classifier, are incompetent in extracting nonlinear features of metamorphic rocks from complex geophysical log data; artificial intelligence algorithms are capable of solving nonlinear problems, but most of the algorithms suffer from tuning parameters to be global optimum to establish model rather than local optimum, and also encounter challenges in making the balance between training accuracy and generalization ability. Optimization methods have been applied extensively in the inversion of reservoir parameters of sedimentary formations using well logs. However, it is difficult to obtain accurate solution from the logging response equations of optimization method because of the strong overlapping of nonstationary log signals when applied in metamorphic formations. As oxide contents of each kinds of metamorphic rocks are relatively less overlapping, this study explores an approach, set in a metamorphic formation model and using the Broyden Fletcher Goldfarb Shanno (BFGS) optimization algorithm to identify lithology from oxide data. We first incorporate 11 geophysical logs and lab-collected geochemical data of 47 core samples to construct oxide profile of CCSD main hole by using backwards stepwise multiple regression method, which eliminates irrelevant input logs step by step for higher statistical significance and accuracy. Then we establish oxide response equations in accordance with the metamorphic formation model and employ BFGS algorithm to minimize the objective function. Finally, we identify lithology according to the composition content which accounts for the largest proportion. The results show that lithology identified by the method of this paper is consistent with core description. Moreover, this method demonstrates the benefits of using oxide content as an adhesive to connect logging data with lithology, can make the metamorphic formation model more understandable and accurate, and avoid selecting complex formation model and building nonlinear logging response equations. [ABSTRACT FROM AUTHOR]

“Sparrow Hills” park is one of Moscow protected areas and an important element of the local nature conservation management. The article presents the results of the eco-geomorphologic analysis of “Sparrow Hills” park. The results focused on ensuring the sustainability of chosen protected area and its ecosystems. This data and findings are the basis for recommendations and guidelines for local authorities.

Chemical tracers are proposed as an effective means of detecting, attributing and quantifying any CO 2 leaks to surface from geological CO 2 storage sites, a key component of Carbon Capture and Storage (CCS) technology. A significant proportion of global CO 2 storage capacity is located offshore, with some regions of the world having no onshore stores. To assure regulatory bodies and the public of CO 2 storage integrity it is important to demonstrate that robust offshore monitoring systems are in place. A range of chemical tracers for leakage have been tested at onshore pilot CCS projects worldwide, but to date they have not been trialled at injection projects or CO 2 release experiments located offshore. Here, for the first time, we critically review the current issues surrounding commercial scale use of tracers for offshore CCS projects, and examine the constraints and cost implications posed by the marine environment. These constraints include the logistics of sampling for tracers offshore, the fate of tracers in marine environments, tracer background levels, marine toxicity and legislative barriers – with particular focus on the Europe and the UK. It is clear that chemicals that form a natural component of the CO 2 stream are preferable tracers for ease of permitting and avoiding cost and risks of procuring and artificially adding a tracer. However, added tracers offer more reliability in terms of their unique composition and the ability to control and regulate concentrations. We identify helium and xenon isotopes (particularly 124,129 Xe), and artificial tracers such as PFCs and deuterated methane as the most suitable added tracers. This is due to their conservative behaviour, low environmental impact and relative inexpense. Importantly, we also find that SF 6 and C 14 are not viable tracers for CCS due to environmental concerns, and many other potential tracers can be ruled out on the basis of cost. Further, we identify key challenges that are unique to using tracers for offshore monitoring, and highlight critical uncertainties that future work should address. These include possible adsorption or dispersion of tracer compounds during ascent through the overburden, longevity of tracers over the timeframes relevant for CCS monitoring, the permissible environmental effects of tracer leakage, and tracer behaviour in seabed CO 2 bubble streams and in dissolved CO 2 . These uncertainties directly affect the selection of appropriate tracers, the injection program and concentrations necessary for their reliable detection, and appropriate sampling approaches. Hence offshore tracer selection and associated expense are currently poorly constrained. Further, there is limited experience of sampling for tracers in the marine environment; current approaches are expensive and must be streamlined to enable affordable monitoring strategies. Further work is necessary to address these unknowns so as to evaluate the performance of potential tracers for CO 2 leak quantitation and provide more accurate costings for effective offshore tracer monitoring programs. [ABSTRACT FROM AUTHOR]

Thermal gradients due to magma dynamics in active volcanic areas may affect the emanating power of the substrate and the background level of radon signal. This is particularly effective in subvolcanic substrates where intense hydrothermal alteration and/or weathering processes generally form hydrous minerals, such as zeolites able to store and release great amounts of H2O (up to ~25 wt.%) at relative low temperatures. To better understand the role played by thermally induced devolatilization reactions on the radon signal, a new experimental setup has been developed for measuring in real time the radon emission from a zeolitized volcanic tuff. Progressive dehydration phenomena with increasing temperature produce radon emissions two orders of magnitude higher than those measured during rock deformation, microfracturing and failure. In this framework, mineral devolatilization reactions can contribute significantly to produce radon emissions spatially heterogeneous and non-stationary in time, resulting in a transient state dictated by temperature gradients and the carrier effects of subsurface gases. Results from these experiments can be extrapolated to the temporal and spatial scales of magmatic processes, where the ascent of small magma batches from depth causes volatile release due to dehydration phenomena that increase the radon signal from the degassing host rock material. [ABSTRACT FROM AUTHOR]

An indicator mineral and geochemical case study was carried out around the Sisson W-Mo deposit to test modern indicator mineral and analytical methods and document glacial and fluvial dispersal from a significant W-Mo source. Indicator minerals in the 0.25 - 2.0 mm non-ferromagnetic heavy mineral fraction of till and stream sediments include the primary ore minerals scheelite, wolframite and molybdenite, as well as chalcopyrite, joseite, native Bi, bismutite, bismuthinite, galena, sphalerite, arsenopyrite, pyrrhotite and pyrite. Indicator minerals in c. 12 - 14 kg samples define glacial dispersal of at least 10 km down ice (SE) of the deposit and fluvial dispersal at least 4 km downstream. The presence of very coarse (0.5 - 2.0 mm) indicator minerals in till and stream sediments marks proximity (<1 km) to the mineralized source. Indicator elements for the deposit in the <0.063 mm fraction of till, the <0.177 mm fraction of stream sediments, and in stream water includeWand Mo, and various combinations of pathfinder elements Ag, As, Bi, Cd, Cu, In, Pb, Te and Zn. This list of elements is more extensive than previously identified for the Sisson deposit or other studies around W mineralization in glaciated terrain. The study demonstrates that indicator mineral methods, so well known for diamond and gold exploration, have a broader application that includes W-Mo exploration. [ABSTRACT FROM AUTHOR]

The Ollo de Sapo Formation comprises variably metamorphosed felsic peraluminous volcanic rocks and highlevel granites that crop out over some 600km from the Cantabrian coast to central Spain in the northern part of the Central Iberian Zone. The Ollo de Sapo magmatism is not obviously connected with any major tectonic or metamorphic event so its origin is controversial. Some authors, based on trace-elements, have proposed that the Ollo de Sapo magmas originated in a supra-subduction setting but others, based on abnormally high zircon inheritance and field and structural data, favored a rifting environment. Here we present new oxygen and hafnium isotope data from the very characteristic Ollo the Sapo zircons, which in most cases, consist of ca. 485Ma rims and ca. 590-615Ma cores. We found that the Cambrian-Ordovician rims yielded unimodal distributions that cluster around ∂18O = 10, typical of S-type magmas formed from melting of altered crust. The Ediacaran cores, in contrast, cluster around ∂18O = 6.5, consistent with being arc-magmas. Rims and cores have the same average Hf isotope composition, but the rims are considerably more uniform. These data, coupled with existing wholerock element and Sr and Nd isotopic data, indicate that the Ollo de Sapo were S-type magmas that resulted from anatexis of younger-than-600Ma immature sediments mostly derived from different Ediacaran igneous rocks with a wide range of Hf isotope composition. [ABSTRACT FROM AUTHOR]

The North African section of the Gondwana margin was the site of voluminous, arc-related magmatism during the Late Neoproterozoic (Avalonian-Cadomian orogen). The lower (and older) metasedimentary sequence that constitutes the Basal Units of the Allochthonous Complexes of NW Iberia was deposited in that setting. In these units, sedimentation was followed by the intrusion of tonalites and granodiorites in the late Cambrian (ca. 493-489Ma). In the Late Paleozoic, the collision of Gondwana and Laurussia (Variscan orogeny) deformed and metamorphosed the whole ensemble. New whole rock geochemical analysis performed in seven samples of metatonalites and fourteen samples of metagranodiorites are characterized by: i) slight enrichment in incompatible elements (Rb, Ba, Th, U), ii) negative anomalies in Nb, Ta, P, and Ti, and iii) negative anomalies in Eu. These chemical features are in agreement with a subduction-related setting for the genesis of both types of magma, which is also supported by chemical discrimination using tectonic setting diagrams. Positive anomalies of Pb suggest a crustal component. The new geochemical data reveal that the convergent orogen that ruled the paleogeography of the Gondwana periphery during the Neoproterozoic (Cadomian orogen) remained active beyond the Neoproterozoic-Cambrian transition, up to at least late Cambrian times. [ABSTRACT FROM AUTHOR]

Based on analysis of new data on the geodynamical nature, ages of formation, and magmatic sources of contrasting rocks from the tectonic mélange of the Yenisei shear zone, the chronological sequence related to early stages in the evolution of the Paleoasian Ocean was established. The data obtained specify the legend and stratigraphic scheme of the Yenisei Group and peculiarities in the evolution of the Sayany-Yenisei accretionary belt at the final stage of its Neoproterozoic history. [ABSTRACT FROM AUTHOR]

Where the Mekong River discharges into the East Sea (also known as the South China Sea), it has formed the world's third largest delta plain with an area of ~50,000 km2. Numerous cores recovered from the subaerial delta reveal that it has prograded ~220 km southeastward within the past 7,500 years. Recent extensive seismic and geochemical surveys of the adjacent subaqueous delta indicate that the Mekong River forms a classic sigmoidal, cross-shelf clinoform immediately off its distributaries that is up to 15 m thick, with topset, foreset, and bottomset facies. These deposits are constrained within water depths of 20 m. Mekong-derived sediment packages extend ~300 km along shelf in the southwestward direction to the tip of the Ca Mau Peninsula, where they form a distal mud depocenter up to 22 m thick. These sediment packages can also be traced into the Gulf of Thailand to water depths of 25 m. The proximal and distal deposits cover ~11,000 km2 of the shelf. Historically, the Mekong Delta has prograded seaward at a mean rate of >30 m yr-1, or 7 km2 yr-1; however, study of the past 43 years of Landsat images indicates that the mode of sedimentation in the delta shifted starting in 2005. From 1973 to 2005, the Mekong Delta's seaward shoreline growth decreased gradually from a mean of 7.8 m yr-1 to 2.8 m yr-1, and after 2005 it became negative, with a retreat rate of -1.4 m yr-1. The net deltaic land area gain has also been slowing, with the mean rate decreasing from 4.3 km2 yr-1 (1973-1979) to 1.0 km2 yr-1 (1995-2005), and then to -0.05 km2 yr-1 (2005-2015). Thus, in about 2005, the subaerial Mekong Delta transitioned from a constructive mode to an erosional (or destructive) mode. Furthermore, not only is the subaerial Mekong Delta land area gradually diminishing, but high-resolution CHIRP sonar profiling surveys off the east-central Ca Mau Peninsula reveal that this portion of the subaqueous delta is also eroding. With the construction of more dams, sand mining, delta subsidence, increasing storms, and sea level rise, the Mekong Delta will likely face more destructive changes, with erosion both of coastlines and underwater deposits. [ABSTRACT FROM AUTHOR]

The log ratio methodology converts compositional data, such as concentrations of chemical elements in a rock, from their original Aitchison geometry to interpretable real orthonormal coordinates, thereby allowing meaningful statistical processing and visualization. However, it must be taken into account that the original concentrations can be flawed by detection limit or imprecision problems that can severely affect the resulting coordinates. This paper aims to construct such orthonormal log ratio coordinates, called weighted pivot coordinates, that capture the relevant relative information about an original component and treat the redundant information in a controlled manner. Theoretical developments are supported by a thorough simulation study. Weighted pivot coordinates are then applied to the geochemical mapping of catchment outlet sediments from the National Geochemical Survey of Australia illustrating their advantage over possible alternatives. [ABSTRACT FROM AUTHOR]

Archaeological science and field investigations are making greater use of multi-element geochemical survey as a tool for site prospection and intra-excavation analysis. This increasing use of geochemical survey is allowing a new field of geoprospection to develop, a technique that has specific relevance to the investigation of sites containing archaeometallurgical evidence, due to the high geochemical loadings within archaeological contexts produced from past metalworking activities. Correspondingly, there have been relatively few published examples that compare the results of geochemical surveys against excavation data. This study reports the use of geochemical data to investigate a multi-period mining site-scape at Alderley Edge, Cheshire, UK. The geochemical data is analysed using principle component analysis, which facilitates the identification of a number of geochemical anomalies. The site taphonomy and stratigraphic evolution of this mining site-scape is complex, with naturally occurring areas of lead and copper mineralization and a history of exploitation since the early Bronze Age. The geochemical anomalies were compared to the results of excavation within the survey area and this combination of excavation and prospection data allowed the reasons for the different geochemical anomalies to be explained. The article highlights the potential of using multi-element geochemical survey to investigate sites containing archaeometallurgical remains and provides a discussion of why context specificity is essential to correctly interpret multi-element geochemical data. Copyright © 2017 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

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Based on the results of multipurpose regional geochemical surveys of the Guizhou Province, geochemical characteristics of soil Se and Se-rich land resources in the central area of Guiyang City were studied and evaluated. Major conclusions are as follows: (1) the Se content in surface soil of the central area of Guiyang City was 0.17-2.89 mg kg, and the average was 0.78 mg kg, which were respectively 2.6 and 3.9 times of the national background value of soil and the world background value of soil. The Se content in deep soil was 0.11-1.48 mg kg, and the average was 0.44 mg kg, which were respectively 1.5 and 2.2 times of the national background value of soil and the world background value of soil. The soil Se content decreased with the increase in the soil depth on the vertical profile, and the surface soil had a higher Se content. (2) Distribution of Se content was mainly affected by parent material, physicochemical properties of soil and other components, soil type, and land use type. Parent material played a key role, as the soil Se content was mainly originated from parent rock and increased with the background value of Se in parent rock, physicochemical properties of soil and other components had certain influences upon the Se content. Se was shown to have a significant linear positive correlation with S and organic carbon but no significant correlation with pH value. Se content varied with different types of soil as follows: skeleton soil > yellow soil > paddy soil > limestone soil > purple soil. Land use type also had certain influences upon the soil Se content as follows: dry land > construction land > garden plot > grassland = garden plot > forest land. (3) Taking 0.4 mg kg ≤ ω (Se) <3.0 mg kg as the standard for Se-rich soil, Se-rich soil of the study area covered an area of 2224 km and 92.5% of the total area; the remaining is general soil. The study area had no Se-excess soil. Therefore, the central area of Guiyang City has a high proportion of Se-rich land, a large area of Se-rich land resources, and a moderate selenium enrichment strength, which have been rarely seen anywhere and provide advantageous resources for the development of Se-rich featured agriculture. [ABSTRACT FROM AUTHOR]

This comment highlights a whole series of datasets on thallium concentrations in the environment that were overlooked in the recent review by Karbowska, Environmental Monitoring and Assessment, 188, 640, 2016 in this journal. Geochemical surveys carried out over the last few decades all over the world at various scales and using different sampling media have reported the concentration of thallium (and dozens more elements) in tens of thousands of samples. These datasets provide a 'real-world' foundation upon which source apportionment investigations can be based, monitoring programs devised and modelling studies designed. Furthermore, this comment also draws attention to two global geochemical mapping initiatives that should be of interest to environmental scientists. [ABSTRACT FROM AUTHOR]

Unpublished chemical and isotopic data taken in November 1992 from the three major Saharan aquifers, namely the Continental Intercalaire (CI), the Complexe Terminal (CT) and the phreatic aquifer (Phr), were integrated with original samples in order to chemically and isotopically characterize the largest Saharan aquifer system and investigate the processes through which groundwaters acquire their mineralization. Instead of classical Debye--Hückel extended law, a specific interaction theory (SIT) model, recently incorporated in PHREEQC 3.0, was used. Inverse modeling of hydrochemical data constrained by isotopic data was used here to quantitatively assess the influence of geochemical processes: at depth, the dissolution of salts from the geological formations during upward leakage without evaporation explains the transitions from CI to CT and to a first end member, a cluster of Phr (cluster I); near the surface, the dissolution of salts from sabkhas by rainwater explains another cluster of Phr (cluster II). In every case, secondary precipitation of calcite occurs during dissolution. All Phr waters result from the mixing of these two clusters together with calcite precipitation and ion exchange processes. These processes are quantitatively assessed by the PHREEQC model. Globally, gypsum dissolution and calcite precipitation were found to act as a carbon sink. [ABSTRACT FROM AUTHOR]

The article considers the outcomes of pedogeochemical and ecological investigations of Gyumri soils implemented for the first time after the devastating earthquake of 1988. 75% of the city soils are characterized by a low level of summary pollution with heavy metals. However, a moderate level of potential ecological risk is common to the city, and from positions of both geochemical and ecological risk assessment Cd and Pb are priority pollutants to Gyumri soils. [ABSTRACT FROM AUTHOR]

We present a geochemical study of recently discovered Martian meteorite Northwest Africa ( NWA) 5790 and use our results to constrain its origin and relationship with the other nakhlites. This nakhlite is a clinopyroxene cumulate composed of phenocrysts of augite, olivine, and rare oxides surrounded by a mesostasis composed of vitrophyric glass, feldspars, oxides, phosphates, and fine-grained olivines and augite. Petrography, and major and trace element compositions of the phases present are consistent with derivation of NWA 5790 from a parental magma common to all the nakhlites. Olivine cores grew from a distinct, incompatible-element enriched magma and are surrounded by rims containing augite inclusions that grew from the nakhlite parental liquid, supporting previous arguments for xenocrystic olivine cores in nakhlites. Rare earth element microdistributions suggest derivation of NWA 5790 augites from an evolved, relatively oxidized magma, produced by augite fractionation from the common nakhlite parental liquid. Augite grain shapes and CSD patterns are consistent with rapid cooling and derivation near the top of the nakhlite cumulate pile, but patterns are distinct from other nakhlites thought to have formed near the stratigraphic top. The high mesostasis abundance (~44 vol%) indicates solidification near the top of the nakhlite pile close to locations suggested for nakhlites NWA 817 and Miller Range ( MIL) 03346. However, the geochemical and petrographic characteristics of these three samples do not permit their placement in a simple stratigraphic order as would occur in a single lava flow. This lack of simple ordering suggests that the nakhlite lava flow split into multiple sections as would occur during breakouts from a single lava flow. Finally we note that NWA 5790 is unique among currently available nakhlites in having phenocryst abundances low enough to allow it to flow. [ABSTRACT FROM AUTHOR]

Soils developed in karst regions have naturally high background values of molybdenum (Mo) due to geological factors. However, the enrichment mechanism of Mo in these soils are not fully understood, making it challenging to assess their ecological risk and utilize Mo-rich land resources. To shed light on this issue, this study collected and analyzed data from the 1:50,000 geochemical survey in Guangxi, including 536,503 sets of soil data and 3043 sets of rock data, as well as 40 sets of carbonate rock-soil from typical karst regions. The results showed that soil Mo enrichment is highly correlated with the distribution of carbonate rocks in karst regions. The carbonate rocks in these regions contain Mo ranging from 0.03 to 1.06 mg·kg−1 (with a mean of 0.22 mg·kg−1). In comparison, the soil Mo derived from carbonate rocks can reach up to 6.00 mg·kg−1 (with a mean of 2.75 mg·kg−1), representing an average enrichment of soil Mo that is 24 times higher compared to the carbonate parent rock. The enrichment of soil Mo in karst regions is primarily controlled by secondary enrichment during the weathering process of carbonate. During the insoluble residue accumulation process, the dissolution of carbonate leads to a dramatic reduction in bedrock volume, and the adsorption of clay minerals and Fe minerals in insoluble residues plays an essential role in Mo enrichment during these stages. During the soil-forming stage of the insoluble residue, most Mo leaches into the water body due to the mineral transformation of insoluble residue. Consequently, as Fe–Mn nodules in soils become more enriched with increasing weathering intensity, some Mo is absorbed and passivated by iron and manganese oxides (hydroxides). Accordingly, the contribution of Fe–Mn nodules and the degree of leaching were closely related to the enrichment of soil Mo in karst regions. This study provides insights into the enrichment mechanisms of Mo in soils developed in karst regions, which will help to evaluate their ecological risk in these environments. [Display omitted] • Soil Mo is correlated with the distribution of carbonate rocks in karst area. • Soil Mo higher in karst regions (mean 2.32 mg kg−1) than in non-karst regions. • Bedrocks volume reduction and mineral composition affect soil Mo enrichment. • Adsorption of Mo by Fe-Mn nodules contributes to the enrichment. [ABSTRACT FROM AUTHOR]

The noble metal (PGE and Au) geochemical specialization of igneous rocks of the Bashkir meganticlinorium and adjacent areas of the East European Platform is characterized for the first time. The identical plots of normalized PGE and Au concentrations of igneous rocks in these regions indicate similar conditions and mechanisms of the formation of the noble metal geochemical specialization during the emplacement of magmatic bodies. It is established that a specific feature of noble metal geochemical specialization (the 'rhodium anomaly') in magmatic complexes of the Bashkir meganticlinorium and eastern areas of the East European Platform is determined by the concentrations of noble metals in sulfide minerals (pentlandite); i.e., it is 'primary' in origin. [ABSTRACT FROM AUTHOR]

This study focuses on the soil in Jiangnan city in China using multi-target geochemical survey data, with statistical methods and Arcgis platform, together with classification map of agricultural land as the base map. We calculate the content of heavy metals in each plot using: the single factor pollution index method, Nemerow pollution index and the potential ecological risk index method to evaluate the risk of 7 kinds of soil heavy metal content. The average contents of some metals investigated were lower than the cultivated soil background values of China. The area of cultivated soil affected by human activities is not obvious. The single pollution index of heavy metals in order of size is HgAs

Hydrogeologic field work in remote settings is often challenging: assessing spring behaviour and aquifer characteristics can be expensive in both time commitment and resources needed to assess these systems. In this study, we document the hydrology and geochemistry of 47 perennial karst springs in the Kaweah River, a mountain river basin in the Sierra Nevada, California. After preliminary hydrogeochemical characterization and grouping, selected springs were continuously monitored to further assess aquifer characteristics in each group. Later, in areas without previous dye-tracing work, traces were conducted to establish connections between large sinking streams and springs. The springs have a wide range of inter-spring and intra-spring variability in discharge and geochemistry. We assessed this variability by performing statistical comparisons with spring chemistry and principal components analysis of all measured variables. Results show that springs can be divided into two distinct groups: high elevation springs of the Mineral King Valley and lower elevation springs throughout the rest of the basin. Continuous discharge, temperature and specific conductivity data from four springs (two from each group) were then used to characterize the hydrograph recession behaviour of springs in each group. Both groups showed statistically similar baseflow recession slopes, suggesting that both groups contain baseflow storage compartments with similar hydrogeologic properties. The biggest difference between each group is the variability in amount of water remaining in the aquifer during baseflow conditions. High elevation springs have lower baseflow discharges, relative to peak flow, than lower elevation springs, despite the fact that more precipitation falls at higher elevation. This is likely caused by differences in the amount of soil and epikarst storage, which are related to recent geomorphic events: high elevation aquifers were glaciated as recent as 41 thousand years ago (kya), while there is no evidence that low elevation aquifers were glaciated. As a result, lower elevations have developed thicker soils, weathered bedrock and epikarst. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The Upper No. 3 coal of the Early Permian age is a major workable seam in the southwestern Shandong coalfield, which is located in the eastern part of North China. From Early Jurassic to Neogene, the coalfield was subjected to intensive tectonic processes, leading to a significant rearrangement in depth of coal seams. In this paper, three Upper No. 3 coals occurring at −228, −670 and −938 m in the Luxi, Liangbaosi, and Tangkou mines, respectively, were collected to investigate their mineralogical and geochemical characteristics, with emphasis on modes of occurrence and origin of epigenetic minerals. The three coal seams are similar in vitrinite reflectance, volatile matter yield, and maceral components, suggesting insignificant influence from the tectonic activities on coal rank. Terrigenous minerals (e.g., kaolinite and quartz) are comparable in both types and distribution patterns in the three coals. The presence of siderite and pyrite of syngenetic or penecontemporaneous origin indicate they were emplaced during peat accumulation. The distribution of epigenetic minerals (e.g., calcite, ankerite, and dolomite) are associated with the underground water activities, which were Ca (Mg, Fe)-bearing. [ABSTRACT FROM AUTHOR]

Traditional methods for studying surface water and groundwater interactions have usually been limited to point measurements, such as geochemical sampling and seepage measurement. A new methodology is presented for quantifying groundwater discharge to a river, by using river surface temperature data obtained from airborne thermal infrared remote sensing technology. The Hot Spot Analysis toolkit in ArcGIS was used to calculate the percentage of groundwater discharge to a river relative to the total flow of the river. This methodology was evaluated in the midstream of the Heihe River in the arid and semiarid northwest China. The results show that the percentage of groundwater discharge relative to the total streamflow was as high as 28%, which is in good agreement with the results from previous geochemical studies. The data analysis methodology used in this study is based on the assumption that the river water is fully mixed except in the areas of extremely low flow velocity, which could lead to underestimation of the amount of groundwater discharge. Despite this limitation, this remote sensing-based approach provides an efficient means of quantifying the surface water and groundwater interactions on a regional scale. [ABSTRACT FROM AUTHOR]