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The Kerek Formation in Sojomerto, Kendal, Central Java is the westernmost part influenced by the Kendeng zone. The presence of sandstone lithofacies in the study area can be a useful tool for determining composition and the provenance. This study involved field observation and analysis of eight thin sections of sandstone from the field. There is no notable petrographic difference across the sandstone succession in the study. the sandstones are predominantly composed of lithic components (48%-63%), matrix (2%-16%), and quartz (1%-24%) thus classified as lithic arenite and lithic wacke. The combination of quartzfeldspar-lithic (QFL) diagram indicates that the sandstone in research area was the result of volcanic activity which is in the southern part of the study area.

The Sawahlunto Formation is a coal-rich geological formation in the Ombilin Basin, located in central Sumatera. It contains three main coal seams, designated as Seams A, B, and C, with Seam C known for its high-quality coal. The study involved analyzing coal samples from Seam C using petrographic and proximate analysis methods. Petrographic analysis assessed the macroscopic composition and vitrinite reflectance, which are essential for determining the depositional environment and coal rating. Proximate analysis provided additional data necessary for evaluating the coal’s quality. The coal was predominantly composed of vitrinite (79.2%-80.6%) and inertinite (19.2%-20.8%). Plots of the Tissue Preservation Index (TPI) and Gelification Index (GI) indicated a limno-telmatic depositional environment. Vitrinite reflectance ranged from 0.45%-0.51%, classifying the coal as sub-bituminous. The calorific values were 15,117.2 btu/lb and 14,815.94 btu/lb, categorizing the coal as highly volatile bituminous.

Granite-related wolframite-quartz veins are the world's most important tungsten mineralization and production resource. Recent progress in revealing their hydrothermal processes has been greatly facilitated by the use of infrared microscopy and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) analysis of both quartz- and wolframite-hosted fluid inclusions. However, owing to the paucity of detailed petrography, previous fluid inclusion studies on coexisting wolframite and quartz are associated with a certain degree of ambiguity. To better understand the fluid processes forming these two minerals, free-grown crystals of intergrown wolframite and quartz from the giant Yaogangxian W deposit in South China were studied using integrated in situ analytical methods including cathodoluminescence (CL) imaging, infrared microthermometry, Raman microspectroscopy, and fluid inclusion LA-ICP-MS analysis. Detailed crystal-scale petrography with critical help from CL imaging shows repetition of quartz, wolframite, and muscovite in the depositional sequence, which comprises a paragenesis far more complex than previous comparable studies. The reconstruction of fluid history in coexisting wolframite and quartz recognizes at least four successive fluid inclusion generations, two of which were entrapped concurrently with wolframite deposition. Fluctuations of fluid temperature and salinity during precipitation of coexisting wolframite and quartz are reflected by our microthermometry results, according to which wolframite-hosted fluid inclusions do not display higher homogenization temperature or salinity than those in quartz. However, LA-ICP-MS analysis shows that both primary fluid inclusions in wolframite and quartz-hosted fluid inclusions associated intimately with wolframite deposition are characterized by strong enrichment in Sr and depletion in B and As compared to quartz-hosted fluid inclusions that are not associated with wolframite deposition. The chemical similarity between the two fluid inclusion generations associated with wolframite deposition implies episodic tungsten mineralization derived from fluids exhibiting distinct chemical signatures. Multiple chemical criteria including incompatible elements and Br/Cl ratios of fluid inclusions in both minerals suggest a magmatic-sourced fluid with the possible addition of sedimentary and meteoric water. Combined with microthermometry and Raman results, fluid chemical evolution in terms of B, As, S, Sr, W, Mn, Fe, and carbonic volatiles collectively imply fluid phase separation and mixing with sedimentary fluid may have played important roles in wolframite deposition, whereas fluid cooling and addition of Fe and Mn do not appear to be the major driving factor. This study also shows that fluid inclusions in both wolframite and coexisting quartz may contain a substantial amount of carbonic volatiles (CO2 ± CH4) and H3BO3. Ignoring the occurrence of these components can result in significant overestimation of apparent salinity and miscalculation of LA-ICP-MS elemental concentrations. We suggest that these effects should be considered critically to avoid misinterpretation of fluid inclusion data, especially for granite-related tungsten-tin deposits.

This study presents for the first time, the field observations, petrography, mineral chemistry and geochemistry of chloritite hosted in the Al-Barramiya Neoproterozoic ophiolite of the Eastern Desert of Egypt, Arabian-Nubian Shield (ANS). The Al-Barramiya ophiolite is one of the most important ophiolitic sequences exposed in the ANS. It is affected by different types of alterations including carbonatization, listvenitization, chloritization and rodingitization. The Al-Barramiya chloritite occurs as thin layers associated with highly serpentinized peridotite. It is a fine-grained rock entirely composed of chlorite (85–95 vol.%) with minor talc and accessory minerals (epidote, rutile, titanite, corundum and opaque minerals). The chlorite minerals in the chloritite are represented mainly by diabantite, while those in the serpentinites include ripidolite. Depending on the chemical composition of the chlorites, the chlorite in chloritite formed at temperatures ranging between 200 and 250°C, which are lower than those of the disseminated chlorite in the serpentinite (310–345oC), indicating their formation in different hydrothermal stages. The chloritite samples are rich in total REE contents (17.9–27.3 ppm) compared with the associated serpentinites (0.69–0.87 ppm). They are characterized by slightly depleted LREE relative to HREE [(La/Lu)n = 0.8–0.9], with a moderately negative Eu-anomaly [(Eu/Eu*)n = 0.4–0.5]. The negative Eu-anomalies are derived from chloritization fluids or reflect the presence of talc in the chloritite. Based on field work, petrography, mineralogical and geochemical data, the studied chloritite has been interpreted as being derived from the associated serpentinized ultramafics by hydrothermal alterations. This is supported by an enrichment of chloritite in compatible trace elements (Cr = 2031–2534 ppm, Ni = 1264–1988 ppm, Co = 76–101 ppm) similar to that which is observed in the associate serpentinite.

Thermochemical heterogeneities detected today in the Earth’s mantle could arise from ongoing partial melting in different mantle regions. A major open question, however, is the level of chemical stratification inherited from an early magma-ocean (MO) solidification. Here we show that the MO crystallized homogeneously in the deep mantle, but with chemical fractionation at depths around 1000 km and in the upper mantle. Our arguments are based on accurate measurements of the viscosity of melts with forsterite, enstatite and diopside compositions up to ~30 GPa and more than 3000 K at synchrotron X-ray facilities. Fractional solidification would induce the formation of a bridgmanite-enriched layer at ~1000 km depth. This layer may have resisted to mantle mixing by convection and cause the reported viscosity peak and anomalous dynamic impedance. On the other hand, fractional solidification in the upper mantle would have favored the formation of the first crust. Following the impact of the protoplanet Theia, planet Earth likely transformed into a magma ocean. New high temperature and pressure experiments by Xie et al. suggest that a layer enriched in bridgmanite formed during the magma ocean phase of Earth–remnants of this ancient layer today may be responsible for the viscosity peak between 660 and 1500 km in present solid mantle.

The end of an orogenic cycle is commonly associated with a general extensional regime, widespread magmatism and complex metamorphic overprints. The Austroalpine domain in SE Switzerland and N Italy preserves a polyphase tectonic history spanning the Carboniferous Variscan orogeny, the Late Carboniferous–Early Permian post-Variscan extension and the Jurassic rifting. In this study, the late- and post-Variscan evolution of the Austroalpine domain is explored by constraining the timing of intrusion of the Sondalo gabbroic complex in the Campo unit. U–Pb zircon dating on magmatic and metamorphic rocks and trace element geochemistry in zircon are performed using laser ablation coupled with mass spectrometry. The ages of both magmatic and metamorphic rocks range between 289 ± 4 and 285 ± 6 Ma. Trace elements in zircon from magmatic rocks indicate that zircon grew in two different chemical systems: an initial one devoid of garnet and with already crystallized plagioclase, and a second one with an increasing modal amount of garnet and lacking (initial) plagioclase. The second system probably reflects mixing of the initial magma with melt derived from the surrounding partially molten metapelites. New results, existing age data and P - T estimates allow to describe the late- to post-Variscan evolution of the Austroalpine domain. These data are compared and integrated in the framework of the Permian geodynamic setting in Western Europe. We present new arguments to consider the “Permian event” in Europe as a process which was temporally distinct from the collapse of the Variscan orogen. Late-Variscan re-equilibration of the crustal thickness occurred between 310 and 290 Ma (i.e. during the collapse phase). Permian mafic magmas emplaced from 290 to 270 Ma formed either during or even after the latest stages of the Variscan collapse.

Sampling an intact sequence of oceanic crust through lavas, dikes, and gabbros is necessary to advance the understanding of the formation and evolution of crust formed at mid-ocean ridges, but it has been an elusive goal of scientific ocean drilling for decades. Recent drilling in the eastern Pacific Ocean in Hole 1256D reached gabbro within seismic layer 2, 1157 meters into crust formed at a superfast spreading rate. The gabbros are the crystallized melt lenses that formed beneath a mid-ocean ridge. The depth at which gabbro was reached confirms predictions extrapolated from seismic experiments at modern mid-ocean ridges: Melt lenses occur at shallower depths at faster spreading rates. The gabbros intrude metamorphosed sheeted dikes and have compositions similar to the overlying lavas, precluding formation of the cumulate lower oceanic crust from melt lenses so far penetrated by Hole 1256D.

This tutorial paper is focused on the mineralogical-petrographic characterization of clayey raw materials with the purpose of sourcing supply basins and answering questions about the provenance of the corresponding archaeological ceramic artefacts. The first part gives general indications of how to profitably study archaeological ceramic thin sections through the polarizing microscope. Brief notes are provided on the theoretical basis of optical microscopy. A scheme is then provided for the petrographic description of ceramic samples, concerning the textural and compositional characteristics of aplastic inclusions and groundmass. Suggestions are also given for identifying any minero-petrographic marker and establishing minero-petrographic groups (MGP) aimed at archaeological ceramic provenance studies. After broadly describing the geological origin of the clay deposits, there is discussion of how to plan a field survey aimed at the location of clay sources and sampling. The importance of the ethnoarchaeometric approach in provenance studies is also underlined. The third part of the paper describes the preliminary treatments to which the clayey raw materials are subjected before reporting on a grain size analysis and how to proceed when performing experimental firing tests. Finally some suggestions are made about how to compare clay firing tests (experimental briquettes) and archaeological ceramic finds when assessing a production centre.

The study of nominally anhydrous minerals with vibrational spectroscopy, despite its sensitivity, tends to produce large uncertainties (in absorbance or intensity) if the observed dispersion of the values arising from the anisotropy of interaction with light in non-cubic minerals is not assessed. In this study, we focused on Raman spectroscopy, which allows the measurement of crystals down to few micrometers in size in back-scattered geometry, and with any water content, down to 200 ppm by weight of water. Using synthetic hydrous single-crystals of olivine and wadsleyite, we demonstrate that under ideal conditions of measurement and sampling, the data dispersion reaches ±30% of the average (at 1σ) for olivine, and ±32% for wadsleyite, mostly because of their natural anisotropy. As this anisotropy is linked to physical properties of the mineral, it should not be completely considered as error without treatment. By simulating a large number of measurements with a 3D model of the OH/Si spectral intensity ratio for olivine and wadsleyite as a function of orientation, we observe that although dispersion increases when increasing the number of measured points in the sample, analytical error decreases, and the contribution of anisotropy to this error decreases. With a sufficient number of points (five to ten, depending on the measurement method), the greatest contribution to the error on the measured intensities is related to the instrument’s biases, and reaches 12 to 15% in ideal cases, indicating that laser and power drift corrections have to be carefully performed. We finally applied this knowledge on error sources (to translate data dispersion into analytical error) on olivine and wadsleyite standards with known water contents to build calibration lines for each mineral in order to convert the intensity ratio of the water bands over the structural bands (OH/Si) to water content. The conversion factor from OH/Si to ppm by weight of water (H2O) is 93108±24005 for olivine, 250868±45591 for iron-bearing wadsleyite, and 57546±13916 for iron-free wadsleyite, showing the strong effect of iron on the spectral intensities.

Facies, microfacies and stable isotope analyses of limestone beds in the northernmost Ñirihuau Basin, North Patagonian Andes, Argentina, document and constrain the past hydrological, sedimentological and climate conditions that prevailed during the deposition of a lacustrine system between ca 15 and 13 Ma. This palaeoenvironment is recorded in the middle section of the Ñirihuau Formation, which holds significance because: (1) It was deposited during a transition from an extensional to a compressional tectonic regime; (2) it spans the Middle Miocene Climatic Optimum and the beginning of the Middle Miocene Climatic Transition; and (3) it contains limestone beds interbedded within a 600 m thick interval of mudstones and siltstones, along with intercalated sandstone and volcaniclastic bodies. Two detailed sedimentary logs were surveyed along the Arroyo Las Bayas, at the western and eastern flank of the David Syncline. Limestones from both stratigraphic sections were sampled as well as isolated limestone beds from two other sites. One facies association was defined and interpreted as a perennial lake associated with a deltaic system and dominated by detrital clastic material. It comprises Facies 1 (Marginal lacustrine) and Facies 2 (Lower delta plain); in both, the presence of grainstones and calcimudstones stands out. Through petrography and cathodoluminescence studies of these continental carbonates, nine microfacies were identified: (a) Intraclastic grainstone, (b) Homogeneous calcimudstone, (c) Silty grainstone, (d) Disrupted micrite, (e) Birds eye micrite, (f) Bioclastic mudstone, (g) Calcimudstone with sparse detrital grains, (h) Fenestral micrite, (i) Stromatolitic boundstone. These indicate mainly bio‐induced subaqueous carbonate precipitation and subordinate deposition by tractive flows with short‐distance transport on a littoral lacustrine environment. Most of these microfacies exhibit very early diagenesis (eogenesis) effects. These features, and the geochemistry results, indicate that they were deposited in a palaeolake system under temperate to warm and humid conditions. Detailed sedimentologic, petrographic and geochemical analyses of the lacustrine deposits registered on the Ñirihuau Formation middle section in the northern sector of the Ñirihuau Basin are presented. The lacustrine carbonates found within these deposits were analysed to characterise the palaeolake system as well as the carbonate factory of the basin, which would enable a better understanding of the hydrologic, sedimentologic and paleoclimatic conditions that would have taken place during their deposition. Furthermore, their possible link to the Middle Miocene Climatic Optimum can be evaluated in light of the new data. Therefore, the results herein presented provide a unique perspective on the conditions that prevailed during the deposition of the lacustrine system that was established between ca 15 and 13 Ma (Langhian–Serravallian) and constitute a valuable contribution to the current knowledge of the Ñirihuau Basin filling and its evolution.