Search

Es-Sbikhat- El-Mahmel, basin, located at the southeastern piedmont of Aures massif (Northeasten Algeria), is an area with a semi-arid climate. 39 samples were collected during May 2015, for physicochemical analysis. The interpretation of analysis data has shown a chemical facies evolution from bicarbonate-calcium waters into chloride-calcium waters, going through a transition facies marked by sulfate-calcium to sulfate-magnesium waters. The principal component analysis showed that the percentage of the variances expressed is 52.70% for the factor 1, 14.73% for the factor 2 and 11.44 for the factor 3. The binary diagrams and thermodynamic analysis corroborated that interaction water-rock is responsible for the mineralization through the geochemical process of mineral dissolution-precipitation, cationic exchange and anthropogenic pollution.

The Himalayan orogen exposes a range of metamorphosed assemblages, from low-grade Indian shelf sediments of the Tethyan Formation to eclogite and ultra-high pressure rocks documented near the sutur...

Integrated studies were carried out on one hundred and eleven (111) ditch samples retrieved from three wells drilled in Lagos area within the Dahomey Embayment, coastal southwestern Nigeria. The purpose of this study is to determine the provenance, heavy mineral assemblage(s), establish the lowstand - highstand episodes, Quaternary palaeoenvironment and date the encountered lithofacies which constitute sandstones, siltstones with thin beds of lignite. The textural parameters show that the sandstones are medium to fine grained with the lignite consisting of plant fragment remains. Petrographic analyses showed abundant detrital minerals with average modal composition of quartz (Q = 90%), feldspar (F = 2%) and rock fragments (RF = 4%). The QFR ternary plots revealed that the sandstones are quartz arenites of continental block provenance origin deposited under humid climatic setting. This lithofacies has undergone medium distance range of transportation and have been subjected to mechanical and chemical weathering prior deposition. The heavy mineral assemblages and the ratios of Zircon-Tourmaline (ZTR index) in the wells suggest matured sediments. The Apatite: Tourmaline (ATi) ratios showed variations within the studied wells indicating differences in rate of weathering. It is evident that the periods of residence on the floodplain despite similar provenances and fluctuations in ratios, suggest sea level changes. The fluctuations in apatite: tourmaline ratios with respect to weathering are attributed to rapid changes in climatic conditions during the floodplain residence. The high ATi values in sandstone were deposited during relative sea level highstand (transgression), while sandstones with low ATi were deposited during lowstand (regression) in Nigeria and along the West African region. The abundance species of Rhizophora sp., Avicennia africana, Acrostichu mauruem, Laevigatosporite sp., Combretaceae sp., Mitrogynaciliata, Sapotaceae sp., Disopyros sp., Elaeis guineensis and Alchronea spp. indicated depositional transition from mangrove to fresh water swamp due to the episodic highstand and lowstand regimes. The abundance of Podocarpus milianjanus and Retitricolporites hians and the absence of Miocene diagnostic forms suggest late Pleistocene (Tarantian = 0.012–0.126 Ma) deposition.

Detailed sedimentological, geochemical, palynological, and aquatic-microfossil analyses on a new composite profile (Para-Reference Profile Schöningen 13 II and Zeugenblock 13 II [2018]) exposed at the archaeological excavation site of Schöningen 13 II reflect several phases of newly recorded lake level fluctuations and vegetation changes. A pronounced deforestation and the expansion of grasses and herbal plant communities characterize the first steppe (open woodland) phase, which follows the interglacial forest communities. A succeeding tripartite woodland phase predominantly marked by Betula and Pinus is followed by another rather dry steppe phase and a second woodland period, which includes the famous archaeological “spear horizon” 13 II-4ab. Transition into a cold period is indicated by progressive desiccation of the lake and a shift to a steppe/tundra vegetation. Novel 3D images of the 10 most characteristic phases of the Reinsdorf sequence have been constructed based on the botanical data (macro remains as well as palynomorphs), terrestrial vertebrate faunal, geochemical, sedimentological, and previously established data from aquatic microfossils. In addition, a tentative correlation between the post-interglacial phases of the Reinsdorf sequence and Marine Isotope Substages 9d–9a, based on biostratigraphical as well as sedimentological data, is proposed.

Актуальность. В наши дни особое внимание уделяется бассейнам, которые считаются потенциальными на наличие нефте- и газопроявлений. В этом отношении особый интерес проявляется к осадочным бассейнам Намкомсон и Фухань (Южно-Китайское море). В них установлены косвенные признаки глубинной дегазации по рифтовому разлому. Формирование нефти и газа тесно связано с образованием аутигенной сульфидной минерализации. Поэтому все больше вопросов возникает по поводу индикации проявлений нефтегазоностности провинций ассоциациями аутигенных минералов. В связи с этим изучение сульфидов от континентальных до океанических до сих пор является актуальной темой для исследований по всему миру. Цель: исследовать геохимические особенности пиритных образований из донных отложений осадочных бассейнов Намконсон и Фухань Южно-Китайского моря. Методы: масс-спектрометрия с индуктивно связанной плазмой; определение потерь после прокаливания и содержания SiO2 выполнено методом гравиметрии; атомно-эмиссионная спектрометрия с индуктивно связанной плазмой; оптическая и сканирующая электронная микроскопия; рентгеновская дифрактометрия; изотопная масс-спектрометрия. Результаты. Сульфидные образования из данного осадочного бассейна представляют собой агрегаты формы полой трубочки, размеры которых достигают максимум 5 см по длине и 5 мм по диаметру. Также обнаружены крупные сростки в виде ксеноморфных сгустков, сфероидальных образований. Сами агрегаты сложены преимущественно пиритом, присутствуют кварц и альбит. Пирит формирует глобулы и кристаллы формы октаэдра. В пиритных образованиях установлены высокие содержания кобальта (16,5...56,8 г/т), никеля (21,4...377 г/т) и молибдена (20,1...117 г/т). Цериевая аномалия составляет 0,90...0,93 г/т. Изотопные значения δ34S составляют от -32,9 до -47,0 ‰. Данные значения и построенные на их основе генетические диаграммы указывают на гидротермальное происхождение пиритных образований. The relevance. Nowadays, special attention is paid to basins that are considered potential for the presence of oil and gas occurrences. In this regard, the Namkomson and Fuhan sedimentary basins (South China Sea) are of interest. They established indirect signs of deep degassing along the rift fault. The formation of oil and gas is closely related to the formation of authigenic sulfide mineralization. Therefore, more and more questions arise about the indication of manifestations of oil and gas content of provinces by associations of authigenic minerals. In this regard, the study of sulfides from continental to oceanic is still a hot topic for research around the world. The aim of this work is to investigate the geochemical features of pyrite formations from bottom sediments of the Namсonson and Fuhan sedimentary basins of the South China Sea. Methods: inductively coupled plasma mass spectrometer; determination of losses after calcination and SiO2 content was performed by gravimetry; atomic emission spectrometer with inductively coupled plasma; optical and scanning electron microscopes; X-ray diffractometry; isotope mass spectrometry. Results. The sulfide formations from this sedimentary basin are hollow tube-shaped aggregates, up to a maximum of 5 cm in length and 5 mm in diameter. Large aggregates in the form of xenomorphic clots, spheroidal formations were also found. The aggregates themselves are composed mainly of pyrite, quartz and albite are also present. Pyrite forms globules and octahedral crystals. High contents of cobalt (16,5...56,8 g/t), nickel (21,4...377 g/t) and molybdenum (20,1...117 g/t) were established in pyrite formations. The Ce anomaly is 0,90...0,93. The isotopic values of δ34S range from -32,9 to -47,0 ‰. These values and the genetic diagrams derived from them indicate a hydrothermal/diagenetic origin for the pyrite formations.

Seafloor methane emissions can affect Earth’s climate and ocean chemistry. Vast quantities of methane formed by microbial decomposition of organic matter are locked within gas hydrate and free gas on continental slopes, particularly in large areas with high sediment accumulations such as deep-sea fans. The release of methane in slope environments has frequently been associated with dissociation of gas hydrates near the edge of the gas hydrate stability zone on the upper slope, with discharges in greater water depths less understood. Here we show, using data from the Rio Grande Cone (western South Atlantic), that the intrinsic, gravity-induced downslope collapse of thick slope sediment accumulations creates structures that serve as pathways for gas migration, unlocking methane and causing seafloor emissions via giant gas flares in the water column. The observed emissions in the study region (up to 310 Mg year−1) are three times greater than estimates for the entire US North Atlantic margin and reveal the importance of collapsing sediment accumulations for ocean carbon cycling. Similar outgassing systems on the Amazon and Niger fans suggest that gravity tectonics on passive margins is a common yet overlooked mechanism driving massive seafloor methane emissions in sediment-laden continental slopes.

The paleoenvironmental reconstruction of Aveiro Lagoon is being carried out based on the sedimentological, paleoecological, geochemical and mineralogical characterization of sediment samples collected systematically in the lagoon. This paper presents results concerning the changes in the chemical and mineralogical composition of the fine fraction (

Data on the mineralogy and geochemistry of rare earth elements (REE + Y) in water, suspended matter and stratified sediment cores from different parts of Lake Onego are presented. The study finds that the dissolved REE + Y in the water from different areas of Lake Onego have common features: (1) a maximum in the area of middle rare earth elements (MREE), (2) a distinct negative Ce anomaly and (3) a positive Eu anomaly. Comparison of the average concentration of elements in the stratified core of the bottom sediments and particulate matter (from the filters and sedimentation traps) from different parts of Lake Onego and the distribution of REE + Y do not reveal any significant differences. The trend of the REE + Y distribution for samples from the South Onego completely coincide the REE + Y distribution in siltstones and sandstones of the Russian Platform Scale Composite (RPSC). In the water area of Lake Onego from south to north, a well-defined trend of changes in REE + Y patterns relative to the RPSC is revealed, with depletion by heavy REE + Y and gradual enrichment by light rare earth elements (LREE). Geochemical and mineralogical data confirm our hypothesis of a significant reformatting of the catchment basin of the Onego Ice Lake in the Late Pleistocene. During the formation of the preglacial lake, a significant part of the catchment area was located south of Lake Onego and is mainly represented by Russian Platform sedimentary rocks. Due to the degradation of the Last Glacier from the Lake Onego depression and the nearby territories, the catchment area changed of its southern and south-eastern sections. Today the composition of the modern sedimentary matter entering Lake Onego is determined by mixing clusters from two geochemically contrasting feeding areas: loose sediments formed by the repeatedly re-deposited products of the weathering of the Fennoscandian Shield's crystalline rock massifs, including Phanerozoic sediments; and to a lesser extent the sediments of the sedimentary cover of the Russian Platform, except the bottom sediments of the South Onego, in which Phanerozoic sedimentary formations have completely predominated throughout the lake's development.

International audience; There is a growing interest in on-site, real-time analytical solutions for mining and environmental projects to characterize large areas and/or volumes of raw materials that are sometimes highly heterogeneous in terms of elemental distribution and mineralogy. Several fast and cost-effective methods are used for rapid on-site screening and real-time chemical and mineralogical characterization, such as portable X-ray fluorescence (pXRF) and X-ray diffraction (pXRD). However, these methods are not always applicable due to limitations in the detection and quantification of light elements (Mg, Al, Si) for pXRF or complex or minor minerals for pXRD, whose results need to be supported by laboratory analysis.This study presents a new methodological approach for in situ rapid chemical and mineralogical characterization of samples, based on the use of a transportable instrument (called ID2B) that allows, in a single acquisition step, a combined XRD-XRF analysis to identify and quantify the chemical elements and their associated minerals. The HI0 harzburgite sample from New Caledonia used to evaluate the data was analyzed in the laboratory (SEM-EDS, EPMA, XRF and XRD) and with the ID2B instrument to highlight the potential of our new methodology. In order to demonstrate the interest of using the ID2B combined XRF-XRD analysis approach directly in the field, where sample preparation is not always easy to implement, this comparison was made on the same sample (HI0), prepared in two different ways, either as a powderized (optimal preparation) or as-sawn (unprepared) sample. After automated processing of the combined XRF-XRD datasets acquired with the ID2B instrument, the chemical elements and mineralogical phases identified on both the powder and as-sawn samples are identical to the laboratory analyses.The chemical proportions calculated from the combined XRF-XRD data sets are also close to the laboratory XRF analysis with relative errors

The 2060 ± 2 Ma Phalaborwa Complex is a pipe-like ultramafic to carbonatite intrusion formed from multiple magma pulses. This produced a main pipe of pyroxenite, carbonatite and foskorite (olivineapatite-magnetite-calcite) and many smaller syenite plugs around the pipe. The complex is the oldest known carbonatite in southern Africa and the only one known to host economic copper deposits. There are no known detailed studies on multi-mineral oxygen and hydrogen isotopes or multi-rock carbonate carbon isotope data for the Phalaborwa Complex. These isotope systems are useful for identifying mineral disequilibrium and alteration, analyzing contamination and constraining the mantle source. Previous work has shown that the nearby Bushveld Complex and Karoo lavas have higher-than-average-mantle oxygen isotope values, and constraining the Phalaborwa Complex magma δ18O values could help place it within the context of major magmatism events on the Kaapvaal Craton. The range in mineral δ18O values for all rock types in the Phalaborwa Complex is 2.24 to 18.3‰, but 90% of diopside and apatite have values within a 1.5‰ range. The δD values for Phalaborwa Complex phlogopite range from -112 to -52‰. The δ18O values of baddeleyite (2.99 ± 0.13‰, 1σ, n=2), olivine (6.12 ± 0.08‰, 1σ, n=2), diopside (7.37 ± 0.40‰, 1σ, n=24), magnetite (3.46 ± 0.75‰, 1σ, n=8), apatite (6.40 ± 0.59‰, 1σ, n=13) and aegirine (6.39 ± 0.65‰, 1σ, n=10) are thought to be magmatic, with most δ18O versus δ18O plots for different mineral pairs signifying equilibrium at high temperatures. Alkali feldspar (9.30 ± 1.15‰, 1σ, n=10) and micas (8.56 ± 3.16‰, 1σ, n=24) have more variable δ 18O values and phlogopite has probably undergone subsolidus exchange or alteration. Magma δ18O values estimated from constituent minerals for pyroxenites (~6.8 to 8.3‰), foskorite (~7.1 & 7.2‰) and carbonatite (~6.5 to 9.0‰) are generally higher than normal mantle magmas. The δ18O value of syenite magma estimated from aegirine is ~8.8 to 10.3‰, and in equilibrium with whole-rock syenite δ18O values (8.7 ± 0.4‰, 1σ, n=5). The phlogopite δD values are consistent with typical mantle magma water δD. Despite evidence for fluid-rock interaction in the carbonatite-foskorite rocks, carbonatite δ13C-δ18O range overlaps with the unaltered, primary igneous carbonatite field (δ18O 8.13 to 12.00‰, δ13C -3.19 to -5.60‰). Local basement rock has average bulk δ18O values of 8.6 ± 0.7‰ (1σ, n=14). This is too low to be a realistic contaminant capable of raising the δ18O values in the mafic rocks, since approximately 66% contamination would be required. The higher δ18O values in the whole-rock syenites are consistent with an origin by partial melting of metasomatized country rock. The high-δ18O values of Phalaborwa Complex pyroxenite-foskorite-carbonatite magmas are from a high-δ18O source, and are similar to those of the Rustenburg Layered Suite of the Bushveld Complex (2060 to 2055 Ma) and Karoo picrites (183 Ma). Hence, it is concluded that the stable isotope data is consistent with a geographically extensive and long-lived high-δ18O mantle source beneath southern Africa.

Climate change-induced frequent cyclones are pumping saline seawater into the Sundarbans. Fani, Amphan, Bulbul, and Yaas were the major cyclones that hit the region during 2019–2021. This study represents the changes in the soil parameters, mangrove biodiversity and zonation due to the cyclone surges in the Indian Sundarbans between 2017 and 2021. Increasing tidal water salinity (parts per thousand) trends in both pre-monsoon (21 to 33) and post-monsoon (14 to 19) seasons have been observed between 2017 and 2021. A 46% reduction in the soil organic blue carbon pool is observed due to a 31% increase in soil salinity. Soil organic blue carbon has been calculated by both wet digestion and the elemental analyzer method, which are linearly correlated with each other. A reduction in the available nitrogen (30%) and available phosphorous (33%) in the mangrove soil has also been observed. Salinity-sensitive mangroves, such as Xylocarpus granatum, Xylocarpus moluccensis, Rhizophora mucronata, Bruguiera gymnorrhiza, and Bruguiera cylindrica, have seen local extinction in the sampled population. An increasing trend in relative density of salinity resilient, Avicennia marina, Suaeda maritima, Aegiceras corniculatum and a decreasing trend of true mangrove (Ceriops decandra) has been observed, in response to salinity rise in surface water as well as soil. As is evident from Hierarchical Cluster Analysis (HCA) and the Abundance/Frequency ratio (A/F), the mangrove zonation observed in response to tidal gradient has also changed, becoming more homogeneous with a dominance of A. marina. These findings indicate that cyclone, climate change-induced sea level rise can adversely impact Sustainable Development Goal 13 (climate action), by decreasing organic soil blue carbon sink and Sustainable Development Goal 14 (life below water), by local extinction of salinity sensitive mangroves.

The Huri bauxite deposit is located 40 km northwest of Maragheh City, East Azerbaijan province, northwestern Iran. Bauxite horizons at Huri develop within karstic depressions and sinkholes of carbonate footwalls of the Ruteh Formation, overlain by carbonate of the Elika Formation. Powder X-ray diffraction (PXRD) and scanning electron microscope, coupled with energy dispersive X-ray spectroscopy (SEM-EDS) analyses show that the Huri bauxite ores consist of hematite, diaspore, kaolinite, and lesser amounts of halloysite, pyrophyllite, illite, goethite, clinochlore, amesite, rutile, zircon, and monazite. Based on geochemical studies (Eu/Eu* vs. Sm/Nd and U/Th bivariate diagrams), basalt rocks interbedded in limestone of the Ruteh Formation are the possible precursor rocks of the Huri bauxite deposit. The pH variations of weathering solutions, fluctuations in the groundwater table level, the function of carbonate bedrock as a geochemical barrier, simultaneous precipitation of Fe-bearing minerals, and preferential scavenging of light rare earth elements (LREE) by hematite played an important role in the fractionation of LREE from heavy rare earth elements (HREE) in the Huri bauxite ores. Fluctuations in groundwater table level, increasing pH of acidic solutions percolating downward, preferential adsorption of Ce onto hematite at the base of the profile, and the possible presence of Ce-bearing fluorocarbonates played an important role in increasing Ce anomaly from the top of the profile downward.

À travers l’exemple du recyclage artisanal de batteries au plomb dans des ateliers en « bout de champ » en Inde, cet article donne à voir l’intérêt d’une approche interdisciplinaire pour appréhender les multiples dimensions politiques, techniques et environnementales de l’exploitation de la mine urbaine. Le recours aux sciences humaines et sociales (anthropologie des techniques, géographie sociale), aux sciences de l’ingénieur (génie des procédés) et aux géosciences (géophysique, géochimie) permet ainsi de reconstituer des chaînes logistiques inversées en suivant de proche en proche les flux matériels du plomb ; des chaînes opératoires en décomposant l’ensemble des opérations efficaces sur la matière dans les ateliers et les usines ; des chaînes de contaminations en prélevant des échantillons de sols aux abords des lieux de production. Ce contraste épistémique entre sciences physiques et sciences humaines et sociales permet ainsi de mieux saisir les enjeux induits par la circulation et la transformation des matières récupérées, pour questionner in fine les possibilités de faire science autrement. Using the example of the traditional recycling of lead batteries in “backyard” workshops in India, this article demonstrates the value of an interdisciplinary approach to ascertain the many political, technical and environmental dimensions of the operation of urban mines. The use of human and social sciences (anthropology of techniques, social geography), engineering sciences (process engineering) and geosciences (geophysics, geochemistry) makes it possible to track reverse logistics chains by following the material flow of lead from one step to the next; operations chains by breaking down all the effective operations on the material in workshops and factories; and contamination chains by taking soil samples in the vicinity of production sites. This epistemic contrast between the physical sciences and the humanities and social sciences enables us to better understand the issues involved in the circulation and transformation of recovered materials, and to examine the possibilities of doing science differently.

Lake Kolon (Hungary), situated in the middle of the Turjánvidék area between the saline lakes of the Danube valley and the Homokhátság, is one of the most significant natural aquatic habitats in the Danube–Tisza Interfluve region. The central question of this study is how the lake changed, and how environmental factors and human activities have influenced these paleoenvironmental changes in Lake Kolon. A multiproxy analysis of a core sequence (loss on ignition, grain size, magnetic susceptibility, and geochemistry) provided crucial insights. Notably, correlations are observed in the following relationships: (1) clay, organic matter, and elements derived from organic sources, such as Na, K, and Zn; (2) MS, sand, inorganic matter, and elements originating from inorganic sources, such as Fe, Al, Ti, Na, K, and P; and (3) carbonate content and elements originating from carbonate sources, such as Ca and Mg. The lake’s paleoenvironment underwent significant changes in the past 27,000 years. Late-Pleistocene wind-blown sand provided the bottom for an oligotrophic lake (17,700 BP), followed by a calcareous mesotrophic Chara-lake phase (13,800 BP). Peat accumulation, along with the eutrophic lake phase, began at the Pleistocene–Holocene boundary around 11,700 BP. From 10,300 BP, with the emergence of an extended peatland phase, the percentage of organic matter (peat) increased significantly. Anthropogenic changes occurred from around 9000–8000 BP due to the different emerging cultures in the Carpathian basin, and from 942–579 BP due to the Hungarian settlements and activity nearby, respectively.

Santonian-Campanian tuffaceous siltstone, epiclastic siltstone, arkose, and fossiliferous mudstone occur in a 45-m-thick section of well 1-BRSA-37-RJS drilled in the southern Campos Basin, offshore SE Brazil. Well log data and petrographic and lithogeochemical data obtained from cutting samples were used to propose a schematic model of the volcano's sedimentary paleoenvironment. The volcaniclasts in the tuffaceous siltstone and epiclastic siltstone are scoria basalts, typical of spatter cones associated with monogenetic fields worldwide. The combination of these features with the petrographic ones of the arkoses found in the same well interval is likely to be related to volcaniclastic processes taking place on the continental shelf. Ratios between the immobile trace elements of the volcaniclastic rocks can be explained by mixing between sources in the upper continental crust adjacent to southern Campos and the scoria basalts extruded in the monogenetic fields. The little differentiated, olivine-rich basalts extruded from the scoria and spatter cones suggest a rising asthenosphere mantle extending from hundreds of kilometers eastwards till southern Campos in the Santonian-Campanian. This may have resulted in regional discordances in the Santonian, both in the Campos and Santos basins, and also places the petroleum systems in the southern Campos Basin under the thermal influence of such a rising asthenosphere in the Santonian-Campanian.

In Ethiopia, obsidian is mainly found in the Afar Depression and the Main Ethiopian Rift. The compositional and petrological features of these obsidians vary. Some volcanic centers show that varying volcanic eruptions from a single center may not necessarily imply variable chemistry. Obsidian has been dated using K/Ar, Ar/Ar, and fission track methods to determine the time of eruption but there are also a few dates on artifacts by hydration dating to establish the time of tool manufacture. Many of the geological sources were utilized by prehistoric populations beginning at least since the Early Stone Age but obsidian became commonly used during the Middle Stone Age. Obsidian based stone tool use for scraping in Ethiopia persisted until recent times.

Recent observations of shale gas breakthroughs in the Weiyuan marine shale gas play in the Sichuan Basin have attracted great interest. To better understand these breakthroughs, we have used core description, cyro-focused ion beam scanning electron microscopy data, X-ray diffraction data, organic geochemistry, and well-logging data to better understand the reservoir characteristics carbonaceous shale, calcareous shale, and siliceous shale lithology, with a focus on organic-rich shale units. We find that conventional well-log methods are effective in mapping the spatial distribution of organic-rich shale in the Weiyuan area where the total organic carbon (TOC) content in the Longmaxi Formation ranges from 1.35% to 6.95%, averaging 4.42%. The kerogen is type I-II, and the vitrinite reflectance (Ro) is greater than 2.57%, which indicates that the formation is susceptible to shale gas accumulation. The clay mineral content ranges from 48 to 63 wt% (avg. 51 wt%) with illite and chlorite averaging 73.8% and 25.7%, respectively. The brittle mineral quartz and plagioclase content ranges from 32 to 61 wt% (avg. 47 wt%). Compared to the surrounding lithologic units, the marine shale exhibits relatively high gamma ray, neutron, sonic, resistivity, potassium, and uranium (U) values and relatively low density, photoelectric effect, and thorium/U values, allowing us to construct crossplots to define the units of interest. Using the same process, we quantify the TOC content providing a spatial distribution of organic-rich shale using conventional well logging.

The present work focuses on the upper Cretaceous (Cenomanian-early Campanian) carbonate successions in selected wells from northwestern Iraq. These successions are represented by Gir Bir (Cenomanian-early Turonian), Wajna (late Santonian) and Mushorah (early Campanian) Formations. The succession has affected by early burial near-surface, unconformity-related and deep burial diagenesis represented by cementation, neomorphism, dolomitization, dedolomitization, silicification, authigenesis of glauconite and pyrite, compaction, micritization, solution and porosity formation. The common porosity types are intergranular, fenestral, intercrystalline, moldic, vuggy, channel and fracture. Three porosity zones (I, II, and III) are identified depending on variation in gamma ray which reflects their shale content. The upper part of zone (II) is highly porous and regarded on the main reservoir unit in the middle and upper parts of the Gir Bir Formation. Fracture and moldic and vuggy dissolution features in addition to karstic and fissure features are responsible for the porosity increase in the fractured reservoir unit.

The stock of shale gas in the Shahezi shale reservoir in the Changling fault depression, Songliao Basin, is believed to be worth exploring. In-depth study on the pore structure and fractal characterization of organic matter (OM) can help better understand the pore system of shale reservoir, which has implications for the exploration of lacustrine shale. To demonstrate the nanoscale pore structure and irregularity of the isolated OM, we collected a large number of samples and then conducted a series of laboratory experiments, such as X-ray diffraction, scanning electron microscopy, and [Formula: see text] and [Formula: see text] adsorption experiments to determine the pore structure parameters and reveal their heterogeneity according to Frenkel-Halsey-Hill theory. As suggested by the experimental results, the pore size distribution curve of the [Formula: see text] and [Formula: see text] exhibits similar pore peaks, whereas the trends of change in bulk shale and isolated OM samples are basically paralleled. The pore volume of the isolated OM ranges between 0.034 and [Formula: see text], which is approximately 0.90–3.06 times that of bulk shale samples. As for the fractal dimensions [Formula: see text] (2.594 on average) and [Formula: see text] (2.657 on average) of bulk shale, they are larger as compared with isolated OM, indicating that inorganic minerals can make a significant difference in the heterogeneity of shale pores. The fractal dimensions ([Formula: see text] and [Formula: see text]) of bulk shales indicate a close correlation with the parameters of pore structure, whereas there is no significant correlation observed between the dimensions of isolated OM and its parameters. In addition, thermal maturity and solid bitumen have only limited impact on the OM pore structure of isolated OM samples. Then, we conducted further research to reveal that the insoluble OM macerals derived from terrestrial higher plants can be used to explain the difference in pore structure and heterogeneity between isolated OM samples. Therefore, we arrived at the conclusion that the composition of macerals depends on the exact pore structure and fractal characteristics of isolated OM samples with similarity in thermal maturity.

Ion beam implantations are widely performed to understand the effects of irradiation-induced displacement damage on nuclear structural materials. However, the volume of material that can be investigated is often limited by the maximum energies of accelerator facilitates, leading to a limitation in the thickness of samples whose mechanical properties can be evaluated. The Lawrence Berkeley National Laboratory's 88-Inch Cyclotron offers a wide range of ions and energies, allowing for material ion implantations at larger scales than typical. Four HT-9 SS-J-geometry tensile specimens were polished and then irradiated with deuterons at the 88-Inch Cyclotron to doses of approximately 0.2 dpa prior to small scale tensile testing. The results from this study show irradiation hardening characterized by the tensile test results and black dot irradiation defects. Additionally, a comprehensive look at low temperature irradiations of high-Cr F/M steels is presented and our results show agreement with the available data.

The provenance of GEMS (glass with embedded metal and sulfides) in cometary type interplanetary dust particles is investigated using analytical scanning transmission electron microscopy and secondary ion mass spectrometry. We review the current state of knowledge and closely examine the densities, elemental compositions and distributions, iron oxidation states, and isotopic compositions of a subset of GEMS in chondritic porous interplanetary dust. We find that GEMS are underdense with estimated densities that are 35–65% of compositionally equivalent crystalline aggregates. GEMS low densities result in a lower contribution to the bulk compositions of IDPs than has been assumed based on their volume fraction. We also find that element/Si ratios, assumed to be primary (indigenous), are instead perturbed by contamination and secondary alteration, including pulse heating during atmospheric entry. Fe in pyrrhotite inclusions was oxidized and Mg, S, Ca, and Fe were depleted relative to lithophile Al and Si, resulting in reduction in element/Si ratios. Because they trap outgassing elements, Fe-rich oxide rims that formed on the surface of GEMS are serendipitous “witness plates” to the changes in composition that accompany atmospheric entry. As a result of alteration, GEMS elemental compositions cannot reliably inform about their provenance. Except for highly anomalous oxygen isotope ratios measured in some large GEMS grains that indicate a contribution from circumstellar dust, oxygen isotope compositions are generally poor indicators of provenance. Prior work indicates that most GEMS fall close to the terrestrial oxygen isotope composition, which, however, does not exclude a presolar interstellar origin. Nitrogen isotopic compositions are more diagnostic. Elevated 15N/14N ratios indicate that GEMS accreted in conjunction with formation of organic matter by ion–molecule reactions in a cold (

The underground thermal fluid is one of the significant factors controlling the formation and quality of reservoirs. The Huangliu Formation (N1h) in YF1 area of the central depression belt in the Yinggehai Basin, South China Sea, is characterized by intense thermal fluid activities related to mud diapir and large-scale shallow-water gravity flow deposits. The multi-episodic invasion of high-temperature and CO2-rich thermal fluid into the formation induces complex water-rock reaction during diagenetic process, providing a preferable investigation opportunity for revealing how thermal fluid affects reservoir quality. This study characterizes the reservoirs in the formation through core and thin section analyses as well as physical property test. The reservoirs are dominated by fine-grained sandstone characterized by medium porosity (15.2–21.3%) and lower permeability (0.56–15.75mD). Based on an analysis of casting thin section, cathode luminescence (CL), scanning electron microscope (SEM), carbon and oxygen isotope, inclusion test, and electron-probe microanalysis (EPMA), we systematically investigate the diagenetic patterns and pore evolution process for the reservoirs in the formation. The episodic invasion of thermal fluid occurred approximately 0.4 Ma ago plays an important role in controlling reservoir development: The CO2-rich formation water induces massive late-stage dissolution, resulting in a higher proportion of dissolved pores (38.7–46.4%), which improves the porosity of reservoirs at a depth of 2600–3100 m. Nevertheless, the late dissolution together with carbonate cementation occurred in closed diagenetic system blocks most seepage channels. Furthermore, the relatively high level clay mineral transformation in the YF1 area leads to a higher content of authigenic illite (44–62%) in the formation. Massive authigenic illite severely blocks the pore throats in fine sandstone, reducing permeability. This study offers an insight to the understanding of mud diapir-derived thermal fluid affecting and controlling the quality of reservoirs in some areas of the Yinggehai Basin.

The prediction of “sweet spot” of multi-lithology composite tight oil and gas reservoirs within mixed siliciclastic-carbonate sequences is a hot topic in oil and gas exploration. There are mixed lacustrine carbonate-siliciclastic rocks in the Da'anzhai Member of Ziliujing Formation in the Eastern Slope of western Sichuan Depression. The reservoir lithology is complex, and the main factors controlling the development of high-quality reservoirs are yet to be known. Based on a large number of drilling, core and thin section observation, well log and seismic data, this paper systematically studies the characteristics and factors controlling the development of the mixed siliciclastic-carbonate reservoir. The results show that the reservoir is composed primarily of coquina, sandstone, breccia and shale in lithology, and its development is mainly controlled by sedimentary microfacies, diagenesis, tectonism (fracturing) and paleogeomorphology during the sedimentary period. The effective fractures in reservoirs of the low-energy shell shoal facies are well developed with relatively good physical properties. With the change of sedimentary microfacies from low-energy shoal to high-energy shoal to arenaceous shoal, the hydrocarbon production capacity worsens step by step. Diagenesis, such as dissolution and fracturing, has a certain effect on reservoir physical properties. The palaeogeomorphic highs and slopes had well-developed fractures during the sedimentary period which are conducive to constructive dissolution, and thus they are favorable zones for reservoir development. The development of structural fractures further amplifies the influence of dissolution; thus the fracture zones are also favorable for the development of high-quality reservoirs. The favorable sedimentary facies zone and fracture development degree serve as the core factors for the formation of high-quality mixed reservoirs. The muddy limestone with certain dissolved pores and structural fractures deposited under the low-energy shell shoal setting is of relatively high-quality reservoir in the Da'anzhai Member.

In recent years, the discovery of the Jurassic oil reservoirs in the Western Thrust Belt of the Ordos Basin reveals that the Jurassic formation in this area has huge oil and gas potential. The pre-Jurassic paleogeomorphology plays a vital role in the formation of the Jurassic oil reservoirs. In this paper, the impression method is applied to restore the pre-Jurassic paleogeomorphology of the Hongde area in the western Ordos Basin, using a large number of drilling, logging, well testing and the latest 3D seismic data. The pre-Jurassic paleogeomorphological units in the study area can be categorized into five groups, including ancient channel valley, ancient terrace, slope, interchannel mound, and low residual mound facies. The oil reservoirs are mainly distributed in highland areas such as slope belts and low residual mounds, the main areas where hydrocarbons accumulate. In addition, the branch ditches in the study area are developed to the southeast and merged into the Ganshan ancient channel. The sandstone in the confluence area of the branch gully is well sorted and connected under frequent scouring by the river. The sand bodies of good connectivity therefore form a drainage system for long-term hydrocarbon migration. The formation of the Jurassic reservoirs in the study area is mainly affected by sedimentary facies, deposition location, and hydrocarbon migration pathway (or fault) of pre-Jurassic paleomorphology. The results from this study can be useful for the prediction of the Jurassic sweet spots in the western margin of the Ordos Basin.

Geophysical surveys in the Lakes Tazenat, Aydat, Chambon and Lacassou combined with a multiproxy study of sediment cores highlight Late Holocene abrupt environmental changes in the northern part of the French Massif Central (FMC). Dating landslide-induced dust layers and subaqueous slope failures impacting lake basin sedimentary fills suggest regional triggering by palaeo-earthquakes (cluster of events) either in the Puy-de-Sancy volcano area, or along the regional Limagne fault. In the present study, a cluster of palaeo-earthquakes occurring in the Sancy area between AD 1243 and 1270 are documented in the Lakes Montcineyre, Chauvet, Pavin and Guery, as well as by the formation of Lake Lacassou following the last emplacement of the Dent du Marais landslide in the Chaudefour glacial valley around AD 1250 ± 30. Former cluster of earthquakes occurring near the Limagne fault between AD 580 and 650 are evidenced in Lake Tazenat and in maar Lake Pavin. Lake Pavin present lake-level was similarly favoured by the cluster of earthquakes between AD 1243 and 1270 and the occurrence of a slump and an outburst flood event resulting in the bypassing of a palaeo-outlet. Holocene earthquakes near the Limagne fault are suggested in maar Lake Tazenat by coeval mass wasting deposits (MWDs) around 2250 ± 50 cal. BP and around 2730 ± 30 cal. BP. A landslide-induced dust layer dated between 2760 and 2520 cal. BP at the transition from paludal to lacustrine deposits in the Chaudefour glacial valley is suggesting that the formation of Lake Chambon resulted from a first emplacement of the Dent du Marais landslide. Radionuclides and radiocarbon dating in Lake Tazenat suggest variable sedimentation rates over the last millennia due to: (i) floods during the Little Ice Age, (ii) coeval MWDs at the basin edges and an erosive turbidite in the central basin between AD 575 and 625, and (iii) lake eutrophication since AD 1945. More gravity cores are needed to directly sample and date the youngest generation of coeval MWDs detected on seismic profiles in order to test the impact in this lake of the cluster of major historical earthquakes in the FMC between AD 1450 and 1490 near the Limagne fault.

A great breakthrough was achieved on the Middle Devonian's oil-gas exploration in the Longmenshan area in northwestern Sichuan. However, only the Guanwushan Formation was researched in detail. The underlying formation - Jinbaoshi Formation as a set of the potential well reservoir and its reservoir characteristics have not been discussed. Based on the section's fine description, thin section analysis, and core borehole logging, combined with petrophysical analysis, the reservoir characteristics, controlling factors, and evolution process of the Jinbaoshi Formation reservoir in the Longmenshan area are deeply studied in this paper. The results showed that the Jinbaoshi Formation has developed a set of sand-shale interbedding deposit of terrigenous clastic and carbonate rocks. The reservoir lithology is mainly quartz sandstone and calcareous quartz sandstone. The quartz sandstone reservoir has good physical properties, but the calcareous quartz sandstone has the characteristics of strong heterogeneity, low porosity, and permeability. Residual intergranular pores are mainly developed in the reservoir space. And the development of intercrystalline pores and intergranular dissolved pores can also be seen, but the development frequency is low, and the scale is small. Among them, the Devonian Jinbaoshi Formation quartz sandstone's average porosity is about 8%, and the highest is 18.43%. The main diagenesis types of the Jinbaoshi Formation are compaction, recrystalization, and dissolution. Compaction is the main reason for the destruction of original pores, and dissolution is the main driving force for later porosity and permeability improvement. Rock fragments, calcareous silty clasts, and bioclastic grains are the main dissolution objects. The formation of intergranular dissolved pores significantly improves the physical properties of the reservoir. Therefore, the reservoir development of the Jinbaoshi Formation is mainly controlled both by favourable sedimentary facies and diagenesis. Quartz sandstone and calcareous sandstone of the Jinbaoshi Formation were controlled by early sedimentary facies in the syngenetic rock stage and developed more early intergranular pores; in the early diagenesis stage, compaction-pressure solution and cementation resulted in residual intergranular pores. In the middle-late diagenesis stage, the calcareous cement is dissolved, and more pores were formed.

We present the results of geochemical investigations, including stable isotope, of the Eemian (MIS 5e) and Vistulian (Weichselian, MIS 5a–d, MIS 3–4) sediments of the palaeolake horizons from Gorzow Wielkopolski site (NW Poland). Our analyzes comprised two profiles from different parts of lake basin, each approximately 11-m long. The deposits represent two cycles of lake accumulation (two limnic layers), each ended by peat deposition, separated by mineral fluvial deposits. The lower and upper limnic layers, despite several similar geochemical features, are records of two separate phases of the lake's functioning. The palynological data suggest that the mineral deposits separating them are not continuous succession, but contain a stratigraphic hiatus. We characterized six geochemical zones (GZ), which correspond well with lithological features of deposits and climatic changes, and reflect the changing environmental conditions (redox conditions, variability and intensity of denudation, biological productivity, and fertility of the environment). In the first phase of lake's development, some influence of the surface material supply is visible, indicated by the increased content of lithophilous elements, (e.g. potassium), as well as closely correlated with them copper and zinc. Slow accumulation of carbonates dominated the limnic layers due to their abundant supply from the catchment area. The greatest variations of isotopic values of carbonates occur in the bottom and at the top of the stratigraphic profile and are related to the changing environmental conditions in the lake's basin (water level and temperature variations). The differences in carbon and nitrogen isotope values suggest different sources of organic matter accumulated in the studied basin and varying trophy of the environment. The higher mercury content is related to the course of climate change and is the highest in cold periods. We identified five main phases of evolution of the palaeolake at Gorzow Wielkopolski site. The lake accumulation began during the final phase of the Wartanian (Late Saalian) Glaciation (MIS 6). Initially the palaeolake harmonically developed and reached its maximum depth (Early and Middle Eemian, MIS 5e). Next the palaeolake became shallower and transformed into the peatbog (Late Eemian, MIS 5e). In the Early Vistulian period (or Early Weichselian, MIS 5a–d), the lake re-existed, initially as a flow-through lake. Finally in middle Vistulian (or Middle Weichselian – Pleniglacial, MIS 3–4), the palaeolake declined and mire developed.

Resumen En este trabajo presentamos los primeros resultados de los análisis tecno-morfológicos y geoquímicos realizados en 12 piezas de obsidiana recuperadas en el Norte de Pampa Seca (sur de Córdoba y San Luis). En esta área se propuso un aumento de la ocupación para el Holoceno tardío, junto con recurrencia en la ocupación de los sitios y la presencia de estrategias tecnológicas que calificamos como conservada en la mayoría de los contextos. En ese marco se destaca la identificación de recursos exóticos, como la ortocuarcita y la obsidiana, que no contaban con antecedentes de estudios previos. Los artefactos de obsidiana se registraron en 11 sitios superficiales distribuidos en toda el área. Por medio de la técnica de Fluorescencia de Rayos-X, se identificaron tres fuentes de obsidiana que vincula a los grupos locales con recursos procedentes de cordillera y piedemonte del oeste, distantes entre 250 y 575 km. La estrategia tecnológica aplicada para su manejo permite confirmar la presencia poco frecuente de la obsidiana en el equipamiento de los cazadores recolectores de la región pampeana, introducida como parte de vínculos de interacción social entre poblaciones. Abstract In this paper we present the first results of the techno-morphological and geochemical analyzes carried out on 12 pieces of obsidian recovered in the North of Pampa Seca (south of Córdoba and San Luis). In this area, an increase in occupation was proposed for the late Holocene, together with recurrence in the occupation of the sites and the presence of technological strategies that we qualify as conserved in most contexts. In this framework, the identification of exotic resources, such as orthoquartzite and obsidian stands out, which had no antecedents of previous studies. Obsidian artifacts were recorded at 11 surface sites distributed throughout the area. By means of the X-ray Fluorescence technique, three sources of obsidian were identified that link local groups with resources from the western mountain range and foothills, between 250 and 575 km apart. In this sense, the technological strategy applied for its management allows confirming the infrequent presence of obsidian in the equipment of hunter-gatherers in the Pampean region, introduced as part of social interaction networks between populations.

A core region is the first place for expected shifts in archaeological materials before, during, and after political changes like state emergence and imperial consolidation. Yet, studies of ceramic production have shown that there are sometimes limited or more subtle changes in the ceramic economy throughout such political fluctuations. This article synthesizes recent efforts to address political economic changes via geochemical characterization (neutron activation analysis; NAA) in the Lake Pátzcuaro Basin in western Mexico. This region was home to the Purépecha state and then empire (Tarascan; ca. AD 1350–1530), one of the most powerful kingdoms in the Americas before European arrival. The combined ceramic dataset from four sites in the region result in eight geochemical groups. Our analysis indicates that the region experienced long-term and relatively stable ceramic production that was not substantially altered by the emergence of the state and empire. In addition, we find evidence for (1) dispersed, localized production; (2) long-lived compositional ceramic recipes; and (3) a complex ceramic economy with differential community participation. We discuss why documenting local ceramic production and craft production more generally is important for the study of past political economies.

Scotland for its small size possesses a more complex geology than anywhere else in the world, consequently the country has a rich mineral legacy. There are around 650 mineral species now known to occur in Scotland; most of these are silicates, but the assemblage also includes oxides, sulphides and sulphates. Most formed by igneous or metamorphic processes. The igneous minerals produced depends on the nature of the intrusion, be it granitoid or basic to ultrabasic, and also on when it formed in the intrusive cycle; i.e. in early magmatic stages or in late-stage veining. Metamorphic minerals are the product of temperature, pressure and the nature of the precursor rock. A few minerals, such as carbonates and iron oxides are of sedimentary origin, and some formed by the addition of material (mostly metal elements) to rocks, a process known as mineralisation. The choice of mineral GCR sites is based on the presence of rare species and/or unusually large concentrations of minerals and/or the provision of good evidence of geological processes. All sites have national significance and the Meall Tairneachan-Creag An Loch Ba–Zn–Pb deposit is of world-class importance. The coverage of the nation’s mineral species is demonstrated by providing a brief description of them which highlights the sites at which they occur. Thus it will be seen that some minerals are predominant at a number of sites: e.g. galena is the main ore mineral at Leadhills-Wanlockhead, Tyndrum and Strontian. Similarly silica, mostly in the form of quartz is present at many sites, but only in its more exotic form such as agate or cairngorm is it the raison d’etre for its choice as a GCR site.

This fifth paper on Scottish mineral Geological Conservation Review (GCR) sites describes five sites of highest conservation value that reflect a wide range of mineral occurrences and formative systems. Host rocks are predominantly basalts of different ages and varying compositions, although in one site the host rocks are mostly basalts and basaltic andesites. The geology and mineralogy of each site differs considerably. Many zeolites have been identified from Skye, Mull and inland localities, their formation resulted from percolating aqueous surface waters or magmatic fluids in amygdales or veins. At some localities geodes and amygdales have been filled with agates some of which are of exquisite quality. Studies of agates reveal that their origin is complex.

As one of the most important margin seas around the west Pacific, the eastern China seas are important sink for terrigenous materials and forms multiple geology structures. So research the composition and spatial distribution of sediments could help us to understand the dynamics mechanism of the marine sedimentary environment, further to comprehend the land-sea interaction process. Based on high spatial resolution sediment survey in the eastern China seas, the distribution diagram of the sediment types was compiled to reveal the space regularities of sediment. In this study, the Principal Component Analysis (PCA) method was used to identify the controlling factors that are the main controls of the sediment distribution in the study area, which revealed three factors (F1, F2 and –F1) representing grain size categories of >5.75φ, 4.25–5.75φ and 1.50–3.00φ, respectively. F1 represents fine sediments (>5.75φ), -F1 represents coarse sediments (1.50–3.00φ), and F2 represents intermediate-sized sediments (4.25–5.75φ). The sediment transport patterns of the different grain size categories in the eastern China seas are discussed in the context of a comprehensive analysis of sediment grain size composition, material sources, flow patterns, and other factors. The results show that fine-grained sediments represent a “distant” sink of terrigenous material that formed in a stable and low-energy sedimentary environment. The coarse sediment deposits were formed in the late Pleistocene when the hydrodynamic conditions were relatively strong, and the intermediate-sized sediments were distributed in an area with a high concentration of suspension representative of mid-strength hydrodynamic conditions.

Rare earth elements (lanthanide and yttrium, abbreviated as REY) provide important support for national security, energy production, environmental protection and economic growth. In recent years, many studies have shown that the content of REY in some coal or coal by-products is close to or even higher than that in traditional REY ore, which makes coal a potential source of REY. This study took the No. 17 coal of Panzhou mining area in Liupanshui coal field as the research object, and the content and occurrence modes of REY in raw coal and 7 density fraction samples were studied. The results show that the content of REY in the raw coal reaches 220.67 μg/g, which is significantly higher than the average REY in the World coal and Chinese coal as reported in the literature. Gravity separation has a certain pre-enrichment effect on REY and the fraction sample ＞1.8 g/cm3 has the highest REY of 426.27 μg/g (equal to rare earth oxide 0.1%). Study on correlation between REY and ash yields reveals that the organic affinity of the light rare earth is higher than the medium rare earth and the heavy rare earth. As shown by XRD and XRF, the major minerals in coal are kaolinite, quartz and calcite, and the content of REY in coal is significantly related to Al and Si and kaolinite, which implies that REY occur mainly in kaolinite. LA-ICP-MS was adopted to determine chemical composition of micro-zone in kaolinite in coal and the results show that there is no obvious correlation between REY and the content of Al and Si. This indicates that the REY occurred probably in the form of adsorption. The research results provide a scientific reference for the potential extraction of the associated REY in the coal.

This fifth paper on Scottish mineral Geological Conservation Review (GCR) sites details sites of highest conservation value for hydrothermal veins and associated mineral assemblages. The GCR sites are both large and small reflecting variations in past economic mining and extraction history. During the long mining histories, and after, the sites have yielded new mineral species and a new metal. From the largest ore field for lead, zinc and copper 80 or so minerals have been recognised, including nine new species, one of which was established as the first sulphite, scotlandite. Elsewhere gold and silver were also extracted. For some veins the country rocks were analysed to determine whether they provided the vein elements for primary and secondary minerals, and sometimes dated. Two sites exhibit polymetallic mineralization, i.e., five elements in the mineral assemblages. In one site veins in close proximity to a sanukitoid pluton received signature elements from the intrusion. Veins in various areas formed in faults, fractures and shears which became conduits for ground waters reacting with vein minerals. Oxygen in the water reacted with lead, zinc and copper minerals and in the presence of CO2 and SO4 supergene mineral assemblages formed in appropriate alkalinities. It is therefore possible to establish paragenetic sequences and calculate stability fields for specific assemblages. Alkalinities and formation temperatures may also be obtained through fluid inclusions studies and isotope analysis.

This, the fourth paper on Scottish Mineral GCR sites, deals with minerals produced during the late stages of granitic rocks creation. Five sites are described and interpreted, encompassing both minerals within intrusive rocks and those which formed in the adjacent country rocks. The former range from previously-mined, porphyry-style copper-molybdnum sulphide concentrations to one of the few Scottish occurrences of tungsten mineralization. Mineral deposits formed in mostly calcareous country rocks by the exchange of elements between granitic bodies and them are generally referred to as skarns. They are geographically more widespread than the within-granite bodies, and comprise calc-silicate minerals such as diopside, grossular garnet, wollastonite and, more rarely vesuvianite. In one instance, the skarns contain a wide range of mineral assemblages including some with boron fluoride minerals and mineable concentrations of iron ore. Probably the most enigmatic of these is an apparent exoskarn type assemblage but is devoid of an associated granite.

Rare earth elements (REEs) mobilize, fractionate, and are re-distributed during supergene processes, and thus provide a powerful tool with which to quantitatively reconstruct the effects of chemical weathering. Moreover, under certain conditions, the REEs can concentrate to levels in the regolith sufficient to form giant regolith-hosted REE deposits, that are now responsible for much of the World’s production of heavy REEs (HREEs). Understanding the supergene behavior of the REEs is an important first step towards applying the REEs as a geochemical tool and meeting the growing global demand of the REEs. Thermodynamic calculations predict that dissolution of the main REE minerals in REE-rich protoliths, namely synchysite-(Y), gadolinite-(Y), hingganite-(Y), yttrialite-(Y), allanite-(Ce), eudialyte, chevkinite-(Ce), britholite, euxenite and loparite-(Ce), should occur spontaneously during weathering. It therefore follows that a high abundance of these minerals in the protolith implies high mobility of the REEs during weathering and consequently a high potential for the discovery of economic REE resources. Dissolution of apatite is promoted by metamictization or structural distortion and could be also important at low pH. In contrast, some LREE-fluorocarbonate minerals, notably bastnasite-(Ce) and parisite-(Ce), and monazite-(Ce) are likely thermodynamically stable in acidic environments. Thus, they would be preserved in the regolith. Zircon, titanite, aeschynite, fergusonite, and xenotime-(Y) are resistant to acidic dissolution, consistent with their common occurrence as residual minerals. In the cases of the world-class regolith-hosted REE deposits in South China, the groundwater is mildly acidic to circumneutral and carbonate-rich. The REEs are consequently transported dominantly as hydrated cations and carbonate complexes, depending on the pH. The general inheritance of the REE pattern of the regolith groundwater in the clay-sorbed fraction in the regolith indicates that the REEs in regolith are scavenged from the regolith groundwater. Elemental anomalies of specific REEs in the clay-sorbed fraction are very likely caused by an anomalously high REECO3+ fraction in the corresponding regolith groundwater, suggesting a preferential uptake of the REECO3+ complexes by the clay minerals, feasibly by halloysite through intercalation as interlayer complexes. This reaction is expected to be particularly important for the sorption and enrichment of the HREEs in the regolith. Depending on the pH and carbonate concentration of the water, surface complexation on clay minerals or interlayer intercalation particularly in halloysite control the pattern of REE enrichment. Mixing of the regolith groundwater with the alkaline and carbonate-rich aquifer groundwater increases the pH and carbonate concentration and, in turn, affects the ability of the mixed water to transport the HREEs. Interplay of aqueous complexation with the regolith mineralogy significantly affects the REE fractionation and re-distribution during groundwater-regolith interaction.

Recent studies along the southern Baltic Sea coast have revealed sedimentary records of catastrophic storm surges that significantly exceed the magnitude of storms documented by instrumental measurements. The present study aimed to apply heavy mineral analysis for storm surge deposits along coasts of Gulf of Gdansk (southern Baltic), as well as for contemporary marine, beach, dune and coastal plain sediments, to test the applicability of the method and to provide new insights into the depositional processes and sediment sources of the storm deposits. The transparent, 0.125–0.25 mm heavy mineral fraction (>2.85 g/cm3) in 118 sediment samples was investigated, and the results were subjected to multivariate statistical analyses (cluster, PCA, LDA). Storm deposits showed higher concentrations of heavy minerals comprising enrichment in garnet, zircon, and rutile. General heavy mineral assemblage depended on regional provenance and primary sediment sources. However, flooding regime (overwash or inundation) played a key role in selective hydrodynamic sorting of grains and mineralogical composition of storm deposits. Interpretation of deposits formed in inundation regime was more certain than deposits formed in overwash regime. In the latter case, deposits showed more similarities to adjacent mineral provinces. Statistical analyses proofed that heavy minerals together with other sedimentological descriptors may be a promising proxy for recognition of deposits related to defined sedimentary environment or identification of particular sedimentological process, e.g. event layers resulted from storm surges.

The crude oils from the reservoirs of Mela-01 and Mela-04 wells located in the Kohat Basin, Pakistan, were geochemically analyzed to evaluate the origin, depositional conditions, and thermal maturity of the rock units and possible facies from which these oils were sourced. Gas chromatography-mass spectrometry (GC-MS) was performed on the samples to obtain biomarker and non-biomarker parameters. Analyzed non-biomarker parameters, including carbon preference index (CPI), terrigenous to aquatic ratio (TAR), isoprenoids pristane to phytane (Pr/Ph), and biomarker parameters, including steranes and dibenzothiophene/phenanthrene (DBT/P) of aromatic compounds, were utilized in the present study to achieve the objectives. Most of these parameters suggest a mixed source of organic matter (marine/terrestrial) with sub-oxic conditions in the source rocks for the analyzed oil samples in the studied wells from Mela oilfield, Kohat Basin. Furthermore, the CPI and different biomarker parameters such as steranes C29 S/S + R, ββ/αα + ββ), moretane to hopane (M29/C30H), pentacyclic terpanes C27 (Ts/Ts + Tm), H32 (S/S + R) hopanes, and aromatic methylphenanthrene index (MPI) indicate that the analyzed oils have originated from thermally mature rocks falling in the oil window. As the studied Kohat Basin has multiple source rocks and contributes to the major petroleum production of the country, the present investigations reveal that its okthe Mela oils were generated by the strata of mixed organic matter that were deposited in marine sub-oxic conditions. Furthermore, this study suggests that this stratum would also have been produced in unexplored surrounding areas such as Tirah, Orakzai, and the Bannu Depression.

The Yamaat Uul mafic complex with Cu-Ni mineralization is located in the Khangai Mountains of Western Mongolia. We have received new unique data for mafic rocks of the complex: U-Pb dating (SHRIMP II), mineralogy (WDS) and geochemistry (XRF, ICP-MS), Sm-Nd and Rb-Sr isotope data and sulphur isotopes. The Yamaat Uul mafic complex consists of two intrusions: Intrusion 1 is represented by rocks of plagioclase cumulates and olivine–pyroxene cumulates; Intrusion 2 consists of monzogabbro. Intrusions 1 and 2 are different in composition of minerals such as olivine, plagioclase and biotite. The monzogabbro has higher contents of incompatible elements (REE, K, Ti, P) than rocks of Intrusion 1. Zircon U-Pb dating of the anorthosite and Bt-Am-Ol gabbronorite shows a Late Permian age (255.8 ± 2.9 Ma and 262.6 ± 3.1 Ma, respectively) for the Yamaat Uul mafic complex. All of the rocks of the complex are derived from a unified parental melt due to different amounts of trapped melts in plagioclase and olivine–pyroxene cumulates and without crustal contamination. The Cu-Ni mineralization of the complex has a low degree of evolution of the sulphide melt, similar to PGE-Cu-Ni mafic–ultramafic intrusions of the Khangai Mountains (Nomgon and Oortsog Uul). The Yamaat Uul mafic complex together with other mafic–ultramafic intrusions of the Khangai Mountains is related to the Khangai LIP and can be considered as potential for the PGE-Cu-Ni. The new geological, petrological, geochemical and isotope–geochronological data can later be used to reconstruct the geotectonics of the Khangai Mountains and the Central Asian orogenic belt as a whole.

This article discusses the geochemical and petrological evolution of the São José do Campestre granite complex (SJCgr), the last Neoarchean plutonic event so far described in the São José do Campestre massif in NE Brazil. We report field, petrographic, zircon U-Pb dating, and whole rock and mineral chemistry for representative SJCgr samples. Laser ablation zircon U-Pb data indicate that the granite emplacement took place at 2664 ± 13 Ma. The rocks comprising the SJCgr have relatively well-preserved primary textures and fabrics and compositions varying from gabbro to syenogranite. Major and trace element contents reveal a metaluminous, calc-alkaline through transitional to alkaline signature, and LILE- and LREE-enriched series analogous to late Archean sanukitoid and modern arc granitoid. The evolution of the SJCgr is envisaged as follows: (1st) partial melting of a metasomatized mantle (2.5–3.0 GPa, ~85–102 km, 1,000–1,200°C), generating a basaltic to basaltic andesitic magma; (2nd) fractional crystallization (FC) of olivine at mantle or lower crustal depth, leading to the parental magmas of the magmatic series; and (3rd) 40–15% FC of olivine gabbro-norite and olivine monzonite cumulates (400–600 MPa, 15–23 km). The SJCgr shares similarities with post-collisional granitoids and, thus, would represent the last Neoarchean episode of mantle-derived magma in Northeastern Brazil.

Columnar-jointed tuffs (bentonites) are located below the Lower Carboniferous Tideswell Dale Sill, Derbyshire, in an abandoned quarry. There are three zones of prismatic joints, columnar joints (∼60 cm thick and mean column width of 4.1 cm) and massive, conchoidally fractured rock sequentially from the dolerite contact downwards. The rocks are very fine-grained (1–10 µm) and consist mainly of sanidine, interlayered illite/smectite, and hematite, with minor quartz, apatite, montmorillonite, anatase and detrital minerals. High K2O and Fe2O3, low Na2O and low MgO are interpreted as due to alteration of felsic volcanic ash. The bentonite was contact-metamorphosed by the sill to temperatures of c. 300 °C. The progression of fracture geometries, thermal considerations and application of theories of column formation indicate that columns formed downwards away from the sill, due to prograde contact metamorphism of the originally clay-rich bentonite. The formation of columnar fracture networks by shrinkage due to igneous heating may have implications for the effectiveness of bentonite as a barrier for disposal of high-level radioactive waste. Regional dimensions include documenting widespread felsic explosive volcanism and inferring a Triassic oxidation event from palaeomagnetic data.