Provenance Of Rocks Research Articles

Characterization and Provenance of Carbonate Rocks for Quicklime and Dololime Production in Twin-Shaft Regenerative Kilns from the Arabian Peninsula and Neighboring Countries

This study analyzes high-grade carbonate rocks from several strategic deposits in the Arabian Peninsula and neighboring countries. The rocks are used locally for quicklime and dololime production in twin-shaft regenerative kilns. Stable C-O-Sr isotopes, along with chemical, mineralogical-petrographic analyses, micropaleontological investigations, cathodoluminescence microscopy, organic carbon speciation, and electron paramagnetic resonance spectroscopy, were used to trace the provenance of these rocks from economically significant non-metallic deposits. The resulting database can help identify and differentiate industrial raw materials that may appear similar chemically and/or macroscopically but have different textures/microstructures that can affect the properties of the derived burnt lime products. Various technological tests, including slaking reactivity, sticking tendency at high-temperature (i.e., 1300 °C), and physico-mechanical behavior of the lime, were performed to evaluate their suitability and predict lime performance in twin-shaft regenerative kilns. Comparison of laboratory and plant results validated the resulting database.

Defining iron-bearing rock sources in compositional data statistical analysis for provenance studies: A case study from South Africa

In iron-bearing rock provenance researches the definition of what is a source vary from an author to another. Issues might occur when the sources are associated with complex weathering profiles. How may the definition of the source influence the results of provenance studies when different types of iron-bearing rocks are encountered within the same weathering profile? In order to deal with this research question, we used a geochemical dataset previously obtained from the study of the ochre geological collection collected around Diepkloof rock shelter, South Africa. We tested the efficiency of Linear Discriminant Analyses (LDA, supervised analysis) and Principal Component Analysis (PCA, non-supervised analysis) in source discrimination and in the attribution of archaeological pieces to the right source. Different assumptions were made: sources were defined by separating or grouping the different lithologies (shale and ferricrete) encountered at the same location. The results show that grouping the different lithologies allows a good attribution of the archaeological pieces to the source it comes from when elements positively correlated with iron are used in the analysis. Separating the different lithologies do not allow a rate of success in archaeological pieces attribution as high as when the lithologies are grouped together. This result might be explained by a highest number of samples that define a source when the different lithologies are grouped together. Further research should be considered in this direction in order to define if this is a general trend.

The Theoretical Potential of Hondsrug Glacial Rock Dust as Soil Remediator in The Netherlands

Agriculture in the Netherlands is a major source of ammonia (NH3) emissions. Deposited nitrogen levels in the Netherlands reached 2-3 times their critical value at the start of 2020. Excess nitrogen in soil may cause declines in biodiversity and ecosystemic disequilibrium. This may lead to acidic and decalcified soils that are less capable of retaining nutrients. The mineral fines in rock dust are proven agents in soil remediation and remineralization. Glacial moraine deposits are a branded source of rock dust and are contained in the glacial till of the “Hondsrug” area, a boulder clay ridge in the northeastern Netherlands. Formerly, erratic rocks from this boulder clay served various practical purposes. The existing apparent inutility of these erratic rocks motivates us to review their potential as rock dust. Lack of chemical analyses on the in situ erratic rocks resorts to an evaluation of their inferred Fennoscandian source rocks which are of igneous and sedimentary lithology. The chemical composition of these inferred source rocks is compared with that of proven rock dust suppliers. It is concluded that even though there are compositional parallels between the rock dust, the Hondsrug area glacial till is comparatively decalcified and mineralogically of limited benefit. Moreover, exceptional magnitudes of erratic rocks are scarcely encountered while at the same time, the bulk is preserved as geological heritage. Despite the adversities, it could be chosen to commence trials with crushing idle erratic rocks in the Hondsrug area whenever this may be assessed as a useful supplement.

Provenance, paleoweathering, depositional setting and paleoclimatic constraints of cretaceous and neogene deposits of The Mamfe Basin, southwest Cameroon

The Cretaceous and Neogene deposits from the Mamfe Basin consisting of sandstone, shale and claystone were studied using petrography, and major, traces and REEs analyses to address sediment source, environment setting, prevailing paleoclimate as well as tectonic regime of the basin. The angular to subangular shape of detrital grains reflects the mineralogical and textural immaturity of sediments and the proximity of the sediment supply source. Sedimentary rocks are composed of a significant number of lithic debris, organic matter, ostracods as well as subrounded heavy minerals referring to notable igneous and metamorphic rocks bordering the Mamfe Basin. The plots of major element ratios including iron oxide/potasium oxide (Fe2O/K2O) against silicium oxide/aluminium oxide (SiO2/Al2O3) combined with that of sodium oxide/potassium oxide (Na2O/K2O) compared to silicium oxide/aluminium oxide (SiO2/Al2O3) are characteristic of greywacke and shale with few arkoses. The pronounced Eu negative anomaly of chondrite normalized REEs along with the plot of La/Th vs Hf and Co/Th vs La/Sc suggest that sediments are in general from felsic and intermediate source rock provenance, only subordinated contribution of mafic source. The negative anomaly of Yb suggests igneous fractionation under highly reducing conditions. The chemical index of alteration values of 47–70 combined with chemical index of weathering values of 0.6–84 suggest low to moderate weathering process of the sediment in the basin. This result is further confirmed by an index of chemical variability values of 0.6–100 and Zr/Sc ratio of 0.06–2.96. The REEs distribution displays a substantial content in LREE, low content in HREE and noticible proportion of (La/Yb)N ratio (mean >9), poor (Gd/Yb)N ratio in the Cross River Formation (mean <2) and slightly moderate (Gd/Yb)N ratio in the other formations (mean >2). This result implies that sediments from the Ngeme, Nfaitok and Baso formations derived from post-Archean rocks. Geochemical paleoenvironmental proxies including Sr/Cu, Sr/Ba, Ga/Rb vs Sr/Cu and SiO2 vs K2O + NaO2+Al2O3 are in favor of arid to semi-arid conditions during the deposition. Trace Elemental ratios such as Sr/Cu, Sr/Ba, V/Ni, U/Th, Ni/Co, V/Sc, and V/Cr values indicate a predominance of oxic conditions during deposition. In contrast, some authigenic pyrite, hematite, siderite and vivianite which are iron-rich minerals suggests episodic reducing conditions in the basin. The study provides a valuable information in evaluating sediments source, depositional environment, tectonic regime as well as the paleoclimatic conditions prevailing in the basin during the depositional period. The geochemistry of rocks of the Ngeme and Baso formations suggest passive continental margin setting and Ngeme, Nfaitok and Cross River formations suggest oceanic island Arc tectonic setting.

Paleogeography of the Late Precambrian basin in the south of the Siberian Platform

This work is largely a development of the ideas and continuation of the research of S. V. Bogdanova. For many years, she worked at the Department of Lithology of Gubkin University, engaged in research of Precambrian complexes, actively attracting young scientists. In her works, the main regularities of the spatial distribution of Precambrian complexes on ancient platforms were formulated.It is established that a system of folded structures existed on the western periphery of the Siberian Platform in the Late Precambrian already to the border 860 Ma. Some of them had a later age of 640 Ma. On the southern and eastern parts of the frame of the Siberian Platform in the Neoproterozoic, different-aged volcanic arcs that arose during the Neoproterozoic (the Late Riphean and Vendian) are reconstructed. Orogenic complexes from the west and southeast separated the platform sea basin from the Paleoasiatic Ocean and served as sediment provenance for the emerging foreland basin. The sediment provenance of sedimentary material for the Neoproterozoic terrigenous deposits of the sedimentary cover of the Siberian platform were located both inside the platform and on its periphery. The sediment provenances differed in the composition and age of the rocks composing them, and the glacial factor played a significant role in the transfer of sedimentary material. A fairly sharp differentiation of the composition of the sediment provenance rocks determined a wide variety of sedimentary material.Based on the results of U-Pb isotope dating of zircons, the age of the Taseeva Group in the south of the Siberian platform is determined, which cannot be older than 612 ± 6 million years. It is established that the formation of terrigenous deposits of Neoproterozoic productive complexes in the south of the Siberian Platform was significantly influenced by different age sources located both within the platform and on the territories surrounding it. They were composed of magmatic and metamorphic rocks with an age of 2800 up to 600 million years.

A remarkable discovery of electrum on the island of Sylt, northern Germany, and its Scandinavian origin

Abstract. An electrum–quartz pebble with a weight of 10.4 g was discovered in a cliff of Saalian glaciogenic sediments on the west coast of the German North Sea island of Sylt in 2012. It has a roundish water-worn appearance and consists of intergrown electrum and milky quartz. It is the largest known electrum find in Germany, and regarding its weight it also ranks amongst the largest gold finds discovered in Germany. We document and characterize this unusual discovery. Furthermore, an attempt is made to investigate its provenance. Therefore, reference samples of southern Scandinavian gold and electrum deposits and occurrences have been studied and compared to the Sylt find. The Au–Ag content determined by electron microprobe (EMP), trace element signature measured by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), and Pb isotope compositions by multi-collector ICP MS (MC-ICP-MS) suggest a southern Norwegian origin. The most probable source might be the Kongsberg ore district or an adjacent, yet undiscovered, mineralization in the Oslo region. In general, Saalian glaciogenic sediments in Schleswig-Holstein (northern Germany) are dominated by rocks of Swedish provenance. Due to the intake of older Elsterian sediments by younger Saalian glaciers, southern Norwegian rocks are also not uncommon in Saalian sediments. A Saalian ice advance or a combination of Elsterian and Saalian ice advances might have provided a transport mechanism for an electrum sample from a south Norwegian mineralization to the island of Sylt.

Palaeoenvironment evolution and organic matter accumulation of the Upper Triassic mudstones from the eastern Qiangtang Basin (Tibet), eastern Tethys

The Upper Triassic successions in the Qiangtang Basin are important targets for petroleum exploration, although they are poorly understood at present. The black mudstones collected from well QZ-16 are the deepest Upper Triassic source rocks to date and have over-mature organic matter (OM) (Ro > 2). In this study, the total organic carbon (TOC) and systematic inorganic geochemistry were determined to reconstruct depositional conditions (palaeoclimate, palaeosalinity, primary productivity, redox conditions, sedimentation rate, and detrital influx) and to assess the OM accumulation mechanism. The TOC contents of the Bagong Fm. mudstones first decrease and then increase from bottom to top (Unit A to Unit D), and Unit C has the lowest TOC contents. These mudstones have relatively obvious correlations between TOC content and the palaeosalinity proxy (Sr/Ba), redox indexes (U/Al, V/Al, Mo/Al, U/Th, and V/Cr) and sedimentation rate indicator ((La/Yb)N), which indicate that OM accumulation was dominated by both high salinity and a slow sedimentation rate in a dysoxic environment. The high Al2O3/TiO2 ratios indicate that the provenance of these mudstones was primarily from felsic igneous rocks. High detrital influx of felsic igneous rock provenance would have diluted the OM and inhibited OM preservation, as evidenced by the negative correlations between TOC content and detrital influx parameters, including SiO2, Al2O3, TiO2, and K2O. The primary productivity (P/Al and Ba/Al) is poorly correlated with TOC for these mudstones, suggesting that its effect on OM accumulation was negligible or limited. The relatively high TOC contents of mudstones from Units A and B are mainly related to the interaction of dysoxic conditions, a high-salinity water column, slow sedimentation rates, and a low detrital influx. An oxidizing water column with low salinity and a relatively high detrital influx and sedimentation rate upward in Unit C led to greater OM degradation and dilution and the lowest TOC contents. The significant TOC content fluctuations in Unit D may be related to vertical variations in the depositional conditions.

Sedimentary geochemistry of the Weihe River sediments, Central China: implications for provenance and weathering

Modern river sediments sampled from the Weihe River, Central China, were analyzed in regard to facies, grain size, major and trace element, and rare earth element (REE). The main aim of the study was to investigate source rock provenance and paleoweathering intensity. Grain-size and outcrop analyses indicate that sediments from the Weihe River are predominantly slit (< 62 μm) and sand (62 μm to 2000 μm). Major and trace element concentrations show inverse correlations with SiO2 content and grain size. Silty sediments are enriched in REE relative to upper continental crust (UCC), whereas sandy sediments tend to be depleted. UCC-normalized REE distribution fingerprints indicate that the silt sediments are mainly derived from the Loess Plateau, while sandy sediments are mainly sourced from the Qinling Mountains. Discrimination functions and La/Th ratio and Hf abundance discrimination diagram also show that silty sediments are mainly derived from quartzose sediments, the main components of Loess Plateau, while sandy sediments are mainly derived from felsic igneous source, the main components of Qinling Mountains in the region where tributaries flow. The chemical index of alteration (CIA), plagioclase index of alteration(PIA), and chemical index of weathering (CIW) suggest that Weihe River sediments are immature and have experienced relatively minor chemical weathering. This work has an important bearing on the general understanding of the role that source rock characteristics and weathering regime have on the formation of clastic sediments in modern rivers and provides a critical baseline for which future work on the Weihe River sediments can be evaluated against.

Depositional palaeoenvironment and models of the Eocene lacustrine source rocks in the northern South China Sea

Element geochemical analysis of 94 ditch cutting samples of the shale source rock from the Wenchang Formation in the Zhuyi sub-basin and the Liushagang Formation in the Weixinan sub-basin was conducted to determine their palaeoenvironment and main controlling factors and to further establish development models. The results indicate that freshwater and a warm and humid climate were characteristics of the depositional palaeoenvironment between Wenchang and Liushagang formations. During the deposition of the Wenchang Formation, the parent rocks mainly consisted of felsic volcanic rocks, the water was characterized by a high palaeoproductivity, shallow-deep water depths, and weakly reducing conditions, whereas during the deposition of the Liushagang Formation, the parent rocks mainly consisted of mafic volcanic rocks, and the palaeoproductivity, palaeowater depth, and reducing conditions of the water were better than during the deposition of the Wenchang Formation. The formation of high-quality source rocks in the Liushagang Formation were mainly controlled by two factors: (1) The mafic igneous rock provenance and strong weathering provided macronutrients (e.g. P, Fe) for water. (2) A high palaeoproductivity provided a source of organic matter, which played a much important role than the preservation condition of organic matter. For the Wenchang Formation, the good preservation of organic matter which was due to the deep water reducing environment, was also necessary. Accordingly, two models were briefly summarized: a productivity and preservation model for the Wenchang Formation source rocks and a productivity model for the Liushagang Formation source rocks. Both of these models can develop high-quality source rocks, but the source rock quality of the former is lower than of the latter, this is mainly attributed to the difference in the nutrients and palaeoproductivity. This study provides valuable guidance for oil and gas exploration in the northern South China Sea and the study of lacustrine source rocks in other areas.

Provenance reconstructions. Article 3. Modern research methods for heavy detrital minerals (garnet, tourmaline, chromespinelide, rutile, chloritoid, pyroxene and amphibole)

Research subject. This article considers accessory minerals, which, unlike zircons, are present in the vast majority of common clastic rocks. Materials and methods. The data on the chemical composition of minerals (garnet, tourmaline, chromespinelide, rutile, chloritoid and clinopyroxene) extracted from the Riphean and Vendian, as well as Upper Permian and Lower Triassic sandstones of the Southern Urals, were used to illustrate the features of applying various methods and techniques. In addition, numerous examples from publications are presented. Results. A number of modern methods for studying accessory minerals, which might be used to elucidate the composition and characteristics of the provenance rocks for terrigenous strata, were reviewed. Conclusions. It is shown that, similar to zircons, accessory minerals possess a significant potential in terms of providing important data on parent rocks.

Geologia Urbana: itinerari in centro città per scoprire la geodiversità litologica

During the last years the interest towards urban areas as possible sites for educational activities concerning the Earth Sciences has been growing. The “Urban Geology” project developed by the Earth Sciences Department of the Universita degli Studi di Milano offers to high school teachers a model of a low-cost outdoor geological activity, with a particular focus on the importance of rocks as georesources and heritage stones in architecture.In a first phase, a pilot itinerary in the centre of Milan for discovering rocks in architecture was structured involving the undergraduate students of Natural Sciences and then proposed to teachers attending the TFA (Tirocinio Formativo Attivo) and in the frame of the “Piano Lauree Scientifiche”. The Milan city centre is characterized by a lithological geodiversity that allows the observation of a great number of rocks of different origin and provenance, most of which are also widespread in the neighbouring cities. For each of the identified rocks, a short guide is made available to the teachers, with lithological description, petrographic classification and additional information on the origin, provenance and use in historical buildings. The guide may be used as preparatory material before the guided excursion, or as a support for more detailed studies after the visit, also offering ideas for interdisciplinary connections (art and architecture, history, economy). The supplied material may also help the teachers in organizing their own itinerary.The itinerary was proposed as didactic activity guided by Department tutors to high school classes (around 190 students up to now), as well as to the general public during the “Settimana del Pianeta Terra 2018” (80 participants).After the first positive experiences with the guided excursion, the project was further developed in the framework of the “Progetti Alternanza Scuola – Lavoro” (School – Work Alternance Projects) and was carried out by a total of 75 students from high schools located in Milan, San Donato Milanese, Bergamo and Lecco. The data collection on the field was performed using a specific multimedial tool, the GeoODK Collect App (http://ona.io/mzucali; http://ona.io/ibollati) for Smartphone. Through such projects, groups of students were able to create itineraries of Urban Geology in their own cities, illustrate their work to the public and share the data online. A workflow to reproduce the activity also in other areas is finally proposed.

PETROGRAFI KARAKTERISTIK BATUPASIR FORMASI GAMPING WUNGKAL IMPLIKASI UNTUK PROVENAN, DIAGENESIS, DAN PROSES PENGENDAPAN, FORMASI GAMPING WUNGKAL, KECAMATAN BAYAT, KABUPATEN KLATEN, PROVINSI JAWA TENGAH

Gamping Wungkal Formation, middle Eocene to Upper Eocene, which consists of sandstones, sandy marl, claystone and limestone which are the problems of provenance rock, diagenesis and its deposition process. Retrieval of stratigraphic data to determine the deposition process which is divided into several facies and determine its depositional environment, petrographic observations to determine the type of rock, provenance, tectonic settings. Interpretation of tectonic settings of sandstones Gamping Wungkal Formations on QFL diagram plots include recycled orogens, foreland uplift sub-zones while the plot in the QmFLt diagram of the provenance rock is the same as the QFL diagram, which is recycled orogen, sub-zone foreland uplift, rock model from recycled orogen foreland uplift sub-zone. The sandstone diagenesis of the Gamping Wungkal Formation in the study area is included in the mesodiagenesis stage where the compaction or burial process still dominates, the depositional environment in the study area is an area formed in the transitional environment or intertidal flat (Middle tidal flat) and subtidal (Lower tidal flat).

Changes in environment and provenance within the Changjiang (Yangtze River) Delta during Pliocene to Pleistocene transition

This study investigates heavy mineral assemblages in sediments of the modern Changjiang Delta (Yangtze River) and the Quaternary/Pliocene (Q/N) boundary strata within the delta area with the aim of deciphering changes in sediment provenance and the depositional environment during the Pliocene to Pleistocene transition. Major heavy mineral assemblages in the modern Changjiang sediments originate from their provenance rocks, while the distribution of unstable (amphibole), ultrastable (zircon, tourmaline, and rutile), and altered minerals (limonite, leucoxene) are closely related to the climate and the hydrodynamic environment within the catchment. The ratio of a certain unstable mineral (amphibole) to an altered mineral (limonite) is considered to be a sensitive indicator of the chemical weathering intensity that is largely affected by climate conditions. Heavy mineral data of core sediments reveal distinctly different environments and provenances between the upper (Quaternary) and lower (Pliocene) sedimentary strata in the Changjiang Delta. The Pliocene sediments are characterized by abnormally high contents of limonite (42%), leucoxene (8%) and zircon (15%), but an extremely low amphibole content (5%). Enrichment of zircon is indicated from the mid-lower Changjiang catchment, where granitoid rocks are widely distributed. The strong enrichment of altered minerals and the considerable great loss of unstable minerals suggest that Pliocene weathering was much stronger than it is nowadays. In contrast, high contents of amphibole, garnet, and pyroxene, and the low stable mineral content in the Quaternary strata indicate that sediment provenances may have extended to the upper Changjiang catchment, which underwent weak chemical weathering. These results imply that Changjiang as a large river system might have drained the East China's continental margin prior to the Q/N transition. The distinct heavy mineral assemblages found at the Q/N boundary in the Changjiang Delta are indicative of a drastic environment with provenance changes in response to intensive neotectonics. It is thus inferred that sensitive heavy mineral indices can be used to indicate the Q/N boundary in the Changjiang Delta, where reliable geochronological proxies have rarely reached an agreement.

Sediment grain size does matter: implications of spatiotemporal variations in detrital zircon provenance for early Paleozoic peri-Gondwana reconstructions

A comprehensive understanding of the relationship between the Sino-Korean Craton (SKC) and the Gondwana supercontinent is crucial for accurate reconstruction of the tectonic evolution and early Paleozoic paleogeography of East Asia. To explore the link between the SKC and peri-Gondwana, we provide new detrital zircon U–Pb age data from litho- and bio-stratigraphically constrained lower Cambrian to Lower Ordovician sandstone deposits from the eastern margin of the SKC (Taebaeksan Basin). Results indicate that the two distinct age spectra of detrital zircon resulted from provenance change combined with a strong function of sediment grain size within host siliciclastic rocks of the Taebaek Group. The age spectra from coarse-grained sandstones display Paleoproterozoic (1.9 Ga) and Neoarchean (~ 2.5 Ga) peaks, indicating that the sediments were supplied from the basement rocks of the SKC. Conversely, age spectra from fine-grained siliciclastics contain late Mesoproterozoic (~ 1.0 Ga) and Neoproterozoic (~ 0.6 Ga) peaks, with or without a Paleoproterozoic signal, consistent with a Gondwanan sediment origin. These different age populations have been documented in multiple Cambrian and Ordovician sequences of the SKC and are consistently well correlated with sediment grain size. Coarse-grained sediments, sourced primarily from local basement rocks, were deposited in coastal, nearshore, and shelf environments, whereas fine-grained sediments were derived from more distal sources (i.e., the Gondwana mainland and/or the Gyeonggi Marginal Belt) and deposited in inner to outer shelf settings. Therefore, the repeated occurrence of sediment with two distinct provenances in the Cambrian–Ordovician siliciclastics of the SKC is likely a result of provenance shift integrated with changing depositional environments in an epeiric platform. This yielded variations in sediment grain size and source rock provenance, with and/or without a tectonic activity. Consequently, our results indicate that the SKC was adjacent to Gondwana during the early Paleozoic.

The age and country rock provenance of the Molopo Farms Complex: implications for Transvaal Supergroup correlation in southern Africa

The age and country rock provenance of the Molopo Farms Complex: implications for Transvaal Supergroup correlation in southern Africa

Provenance identification based on EPMA analyses of heavy minerals: Case study of the Toki Sand and Gravel Formation, central Japan

AbstractTo perform efficient provenance analysis, a method for quick identification of heavy minerals by using an electron probe microanalyzer (EPMA) was developed. The concentrations of 28 elements were measured in individual grains to identify the mineral species based on their chemical composition. Provenance rocks can be identified based on the abundance ratio of identified minerals and the chemical composition of specific minerals. This method was applied to samples from the Toki Sand and Gravel Formation in the Tono area, central Japan. At the sampling location, gravels of the Naegi‐Agematsu Granite and the Nohi Rhyolite were observed in the upper member, whereas gravels of only the Nohi Rhyolite were observed in the lower member. Heavy‐mineral compositions of the bedrock samples of the Nohi Rhyolite and the Naegi‐Agematsu Granite, as well as the sediments at the sampling location, were measured by EPMA analysis. Both bedrocks commonly contain ilmenite, biotite, allanite, and zircon, and the abundance ratios of heavy minerals were similar. Instead, MnO contents of ilmenite grains and Y2O3 contents of zircon grains were used as indexes to distinguish the two bedrocks. As a result, the Y2O3‐rich zircon grains (≥ 1 wt%) observed in the Naegi‐Agematsu Granite were obtained in the upper member but not in the lower member. The MnO contents of ilmenite grains were higher in the Naegi‐Agematsu Granite and the upper‐member sediments than those in the Nohi Rhyolite and the lower‐member sediments, although the difference was small probably because of Mn dissolution due to secondary alteration. These results indicate that the Naegi‐Agematsu Granite was added to the provenance of the sampling location after deposition of the lower member, which is consistent with the geological description. The change in provenance could have been caused by uplift and denudation of the Atera Mountains associated with reactivation of the nearby Atera Fault.

Provenance Studies of Ilmenite from Red Sediments, Bhimunipatnam Coast, East Coast of India

Abstract Mineral chemistry of the ilmenites, drawn from the red sediments along the Bhimunipatnam coast, Andhra Pradesh, India was determined by EPMA technique. The major constituents are TiO2 and FeO, and the value of Ti/(Ti + Fe) &amp;lt; 0.5 of these ilmenites indicate that they are relatively fresh ‘ferrian ilmenites’ and were contributed recently to the red sediments in the study area. Using the mineral chemical data, the end-member composition of the analyzed ilmenites was calculated, which reveals that they are of ‘ilmenite - hematite’ and ‘ilmenite - geikielite - hematite’ composition, derived from calc-alkaline magma-sourced charnockites and metapelitic khondalite suite of rocks respectively of the Eastern Ghats granulite belt. The TiO2 content and Mn/Mg ratio of the study ilmenites indicate that these rocks constitute their provenance in the Gosthani river basin. Their back scattered electron (BSE) and scanning electron (SEM) images show their prominent sub-angular to sub-rounded shape, corroborating the study under microscope, with some preserving signatures of exsolution intergrowth, earlier deformation and rounded shape, all of which are attributed to their transportation by the Gosthani river, after their liberation from their provenance rocks.

Combining chemical and X-Ray microtomography investigations on crustal xenoliths at Mount Etna: evidence of volcanic gas fluxing

Crustal xenoliths embedded in lavas offer chances to provide information on the lithology of the volcano basement and the process occurring during magma ascent. In this work we studied seven xenoliths found among the scoriae ejected during several paroxysms occurred between 2011 and 2016 at the South East Crater (SEC) of Mount Etna volcano. These samples are characterized by massive presence of glass and vesicles resulting in a foam-like appearance of their texture. A detailed study of their textural and chemical features was carried out combining XRF, SEM-EDS, two-dimensional observation and Synchrotron X-ray microtomography (3D imaging). This multidisciplinary approach allowed us to identify and quantify the components of the samples, individuate the likely provenance rock, ascribable to the Numidian Flysch outcropping west of the Etnean edifice. 2D and 3D imaging were successfully applied to estimate the amount of the phases constituting the samples (grains + glass + vesicles) and the degree of partial melting that occurred during the interaction with the basaltic melt and gaseous phase. The sedimentary rocks underwent profound changes led by partial melting, gas fluxing, vesiculation and selective alkali enrichment. These processes could not be driven exclusively by the prolonged contact with the molten phase but must be considered as result of a significant contribution from the volatiles rising through the plumbing system and the sedimentary basement.

Mineral composition and rock provenance of a prehistoric stone axe head from the surroundings of Nevestino village, Kyustendil District, SW Bulgaria

This paper presents a petrographical study of a stone axe head which is an exhibit of the Historical Museum in the town of Kyustendil, SW Bulgaria, and is of supposed Bronze Age origin. The methods used comprise optical and electron microscopy, and electron microprobe analysis. The results show that the stone axe head is made of microgabbro rock. This rock in mineral composition, mineral chemistry, and metamorphic alteration is similar to gabbro rocks of the Struma Diorite Formation, which crops out on large areas in SW Bulgaria. Thus, it is proposed that the rock provenance of the studied stone tool is the Vlahina Planina mountain or Osogovo Planina one since the nearest outcrops of the Struma Diorite Formation there are in a distance of ~ 4–5 km away from the place of finding. Use of local rock for production of an every-day tool reveals good knowledge of local natural materials by prehistoric people and suggests a settled way of life.

Evidence for impact melt sheets in lunar highland smooth plains and implications for polar landing sites

Smooth plains units attributed to fluidized basin ejecta occur over much of the lunar highlands. We examined 4–20 km diameter Imbrian- and Eratosthenian-period craters in the southern highlands that have high 12.6-cm wavelength radar backscatter and circular polarization ratios associated with their interior walls but not with their proximal ejecta. Of these craters, about 70% occur on or very near deposits of Imbrian highland plains. We propose that melt-rich ejecta from basin-forming impact events, near the top of the stratigraphic section, supplies fragmental material that is exposed in the interior wall regolith of these small craters. These results support previous interpretations of 70-cm radar data, which provide insight on the near-surface morphology and rock provenance in proposed smooth plains landing sites such as that of Chandrayaan-2.