Petrological Characteristics Research Articles

Analysis of genetic sandbodies and coal seams with coal-bearing of Middle-Lower Jurassic in the Junggar Basin

IntroductionThe sediment genetic mechanisms have always been an important branch of the “source-sink” system, and it is also a research hotspot.MethodsConglomerate, sandstone, and coal are developed of Middle-Lower Jurassic in the Junggar Basin, and the genetic mechanism is not clear, which restricts further exploration of oilfield. Based on the core carefully, test data, and outcrop sections, Badaowan and Xishanyao formations are analyzed.ResultsFive types of conglomerate lithofacies and sandstone lithofacies, two kinds of mudstone lithofacies, and one type of coal are identified. Based on the structural-genetic mechanism, the debris flow and traction current with conglomerate are developed, and a method of the semi-quantitative identifying index is proposed based on the sedimentary sequence of lithological characteristics, MPS/BTh, and grain size characteristics as the identification criteria. Depending on fluvio-delta, the genetic bodies of the distribution channel, subaqueous distribution channel, mouth bar, braided channel, and overbank sandstone are divided.DiscussionBy integrating structural, paleoclimatic, and sedimentary environment, it was observed that coal in the Badaowan Formation has the characteristics of continuous and stable distribution of thick layers, whereas multiple sets of discontinuous and instable distribution are observed in the in Xishanyao Formation. Finally, the filling model is established, and the superposition and distribution of sandbodies are clarified.

Integrated geochronological and chemostratigraphic study of middle Miocene strata (Ogallala Group) at the eastern margin of the North American Great Plains

Global and regional shifts in climate and environmental conditions during the Miocene gradually gave rise to the grassland biomes that now dominate the modern North American Great Plains. Strata comprising the Ogallala Group provide critical information for understanding these transitions. Geologic mapping and scientific drilling at the eastern edge of the Ogallala Group in northeastern Nebraska, reveal a basal, pedogenically modified siltstone-dominated interval that was hitherto barely known and never firmly placed in a regional stratigraphic context. Herein, we distinguish this basal siltstone unit of the Ogallala Group in the eastern Niobrara River Valley from the overlying sand-dominated strata of the Valentine Formation on the basis of lithologic characteristics, trends in organic-carbon δ13C chemostratigraphic profiles, and U-Pb dating of detrital zircons. This siltstone unit bears some similarities to the middle Miocene Fort Randall Formation in its type area, which lies ∼75 km to the northwest in the Bijou Hills of South Dakota. Organic δ13C chemostratigraphic profiles generated from outcrops and cores of the basal siltstone in Nebraska indicate that the study area consistently had C3-dominated paleofloras while it was deposited, presumably in the middle Miocene. The youngest detrital zircons from the siltstone-dominated unit were probably deposited directly onto ancient landscapes by supervolcanic airfall events originating some 1,500 km to the west near the intersection of the boundaries of present Oregon, Nevada, and Idaho. These youngest zircons yield a maximum depositional age of ∼15 Ma. This age is in general agreement with the Barstovian (Ba2) mammal biostratigraphic age of the Fort Randall Formation in South Dakota. It is also significantly older than the ∼13 Ma youngest single grain zircon we recovered from sands of the overlying Valentine Formation. Thus, we propose that our integrated geochronologic and chemostratigraphic approach can date Late Cenozoic strata with constraints on the order of 1 m.y., portending broad applicability of our methods in reducing the uncertainties in dating terrigenous sediments in continental basins.

Transport and deposition of terrestrial organic matter in marine littoral deltas: New evidence from flume experiments and 3D laser scanning

Terrestrial organic matter (TOM) serves as the primary parent material for source rocks in marine-terrestrial transitional environments. The transport and deposition process of TOM affects the development of high-quality source rocks in shallow marine areas. Based on the sequence stratigraphy of the Enping Formation (upper Eocene to lower Oligocene) in the Baiyun Sag and the petrological characteristics of the source rocks, simulation experiments of terrestrial dispersed organic matter deposition constrained by topography, provenance composition, sedimentation period and other conditions were conducted. Comparative experiments of individual constraints such as topographic slope, hydrodynamic conditions, water salinity and particle size of organic matter were also conducted. The results indicate that TOM enrichment in the littoral delta system initially increases with transport distance but subsequently decreases. Four TOM distribution patterns were identified: interrupted, interbedded, lenticular, and banded types. The interrupted, interbedded, and lenticular types predominantly occur in delta plains, whereas the banded type primarily develops in delta fronts and prodeltas. In the early stages of delta formation, gentle slope conditions are more conducive to the forward transport of TOM. As the delta develops, the sediment thickness increases, which reduces the slope gradient and thus weakens the effect on the transport distance of TOM. Higher flow intensity promotes TOM transport, however, wave action can impede forward transport, creating localized TOM enrichment areas on the delta plain. In shallow water, the increase in water salinity enhances the flocculation of TOM, thus reducing the transport distance of TOM. Meanwhile, Smaller TOM particle sizes correspond to greater transport distances and increased heterogeneity in its planar distribution within the delta-shallow sea sedimentary system.

Different levels of interpreting chemical data by prompt gamma activation analysis on polished stone tools in the Carpathian Basin (Hungary)

AbstractAverage chemical composition data can be effectively exploited in provenance, i.e. raw material’s origin, research of archaeological polished stone artefacts where direct correlation with potential raw materials is possible. This study summarizes the success of Prompt Gamma Activation Analysis (PGAA) method on two different levels of chemical data interpretation for variable rock types found in Hungary, in the Carpathian Basin and their wider vicinity, i.e. material characterization and provenance identification level. Characterization of different lithologies is possible by variable combinations of some major element oxides (Si, Mg, Ca, Na, K, Al, Fe and Ti). Applying statistical methods, boxplots and Principal Component Analysis, we proved that serpentinites, nephrites and Mg-Si-rich subgroup of ‘white stones’ can be clearly distinguished, while the ‘green stone’ category cannot be further differentiated, partly overlaps with hornfels and significantly overlaps with other rock types (basalts, metadolerites-metagabbros, andesites and metavolcanites). The provenance identification is successful in the case of contact metabasites and HP metaophiolites, while less exact for nephrites, basalts and hornfels.The non-destructive PGAA proved to be very effective in the identification of certain lithologies, while for other polished stone tool raw materials it has medium certainty and requires complementing methods.

Occurance and pollution risk assessment of emerging contaminants in groundwater in the vicinity of a typical municipal landfill in northeastern China

Emerging contaminants (ECs) present a significant risk to both the ecological environment and human health. However, there is currently limited knowledge regarding the presence of ECs in leachate and the surrounding groundwater environment of landfills. The heterogeneity of aquifers introduces additional uncertainty into the transport of ECs, thereby impacting the accuracy of pollution risk prediction. In this study, the types and concentrations of ECs in the leachate and surrounding groundwater were firstly investigated in a typical landfill in northeastern China. Results show that 6 different ECs were detected in groundwater monitoring wells around the landfill, with concentrations ranging from 1.25-1471 ng/L, higher than most investigated landfills in China. Leachate contained 18 different ECs with concentrations ranging from 0.25-30414 ng/L. Based on the statistical characteristics of lithology reflected by borehole data, random lithology fields were generated and transformed into heterogeneity parameter fields using Markov chain analysis to facilitate the risk assessment of ECs. Following a simulation period of 100 years, it was observed that due to the low permeability of the aquifer, pollutants only spread up to 700 m northward. While pollution plumes may disperse towards residential areas, the probability of exposure to EC in these regions is minimal. Conversely, areas with high pollution risk are predominantly located on the eastern and northern sides of the landfill. This study contributes to a deeper understanding of the impact of landfills on surrounding groundwater environments, and our proposed pollution risk assessment model can serve as a valuable reference for controlling and treating ECs.

Radiological characterization related to lithology and risk assessment of bottled natural mineral water

The enhancement of natural radioactivity in groundwater, specifically in natural mineral water, is related to the lithological formations through which water bodies or courses pass. Although natural mineral waters are exempt from monitoring for radioactive substances according to Council Directive 2013/51/EURATOM, this study focuses on the radiological characterization of natural mineral water under Spanish Royal Decree 3/2023. The water studied was taken from Catalan aquifers with different lithological characteristics (sedimentary, metamorphic or granitic) and is sold on local markets. Moreover, radiological data on the water was correlated with its lithological origin and the health risk for different age groups was assessed. Our results showed that of the 26 natural mineral waters studied, 10 exceeded gross alpha screening value (100 mBq/L), all from granitic aquifers. Further research on natural individual radionuclides was conducted on these ten samples. 234U and 238U were at around 1100–1600 mBq/L. In addition, 210Pb was found in two samples, which also presented the highest 226Ra activity, associated with granitic bedrock and the presence of 210Po. The annual effective dose was 179.0 µSv/year and 145.9 µSv/year, exceeding 100 µSv/year mainly due to the contribution of 210Pb > 234,238U > 210Po > 226Ra, in this order. After assessing the lifetime cancer risk, these two samples were determined not to pose a health risk due to ingestion. Although no radiological monitoring is required for natural mineral water, further surveillance is recommendable.

Rifting Basins at the Accretion-Collision Stage of Fold Belt Development: Eastern Slope of the Southern and Middle Urals in the Carboniferous

Research subject. Sedimentary basins within the Mississippian and Early Pennsylvanian (Middle Carboniferous of Russia) rift (sensu lato) structures on the eastern slope of the Southern and Middle Urals. Methods. An analysis of lithological characteristics of sedimentary rocks and relationships with volcanic complexes in order to clarify the evolution of rifting basins. Results. During the Mississippian and Early Pennsylvanian, several large rifting basins were common in this area. The Early Carboniferous rifting basins (Magnitogorsk-Bogdanovskoe graben and Alapaevsk-Kamensk rift) of accretionary margin of the East European craton were characterized by relatively shallow-water (in some places up to coastal-marine and continental) environments, caused by intensive (compensatory) filling of depressions with sedimentary material. In this case, volcanic rocks – those of fissure-type and stratovolcanoes lava flows – also played a significant role. In the Late Visean, the rifting process paused; a relatively shallow shelf basin regime was established throughout the entire area, which persisted until the end of the Early Carboniferous. In the Early Pennsylvanian, due to a hard oblique collision, the rifting process resumed. However, the rifting basins were already smaller in terms of area and most often deeper, whereas the occurring volcanic processes were less intensive. The characteristic feature of these basins was the presence of flysch complexes. The elongated shape of the rifting basins, large thicknesses of sedimentary strata, lateral facies variability, and the abundance of coarse clastic rocks, consisting largely of fragments of directly underlying sediments (Visean, Serpukhovian, Bashkirian), suggest that the Mississippian and Early Pennsylvanian rifts of the Southern and Middle Urals eastern slope had a strike-slip nature, i.e., the rifting basins were pull-apart type depressions.

Combining Remote Sensing Data and Geochemical Properties of Ultramafics to Explore Chromite Ore Deposits in East Oltu Erzurum, Turkey

The present research’s main objective was to apply thorough exploration approaches that combine remote sensing data with geochemical sampling and analysis to predict and identify potential chromitite locations in a complex geological site, particularly in rugged mountainous terrain, and differentiate the ultramafic massif containing chromitite orebodies from other lithologies. The ultramafic massif forming the mantle section of the Kırdağ ophiolite, located within the Erzurum–Kars Ophiolite Zone and emerging in the east of Oltu district (Erzurum, NE Turkey), was selected as the study area. Optimum index factor (OIF), false-color composite (FCC), decorrelation stretch (DS), band rationing (BR), minimum noise fraction (MNF), and principal and independent component analyses (PCA-ICA) were performed to differentiate the lithological features and identify the chromitite host formations. The petrography, mineral chemistry, and whole-rock geochemical properties of the harzburgites, which are the host rocks of chromitites in the research area, were evaluated to verify and confirm the remote sensing results. In addition, detailed petrographic properties of the pyroxenite and chromitite samples are presented. The results support the existence of potential chromitite formations in the mantle section of the Kırdağ ophiolite. Our remote sensing results also demonstrate the successful detection of the spectral anomalies of this ultramafic massif. The mineral and whole-rock geochemical features provide clear evidence of petrological processes, such as partial melting and melt–peridotite interactions during the harzburgite formation. The chromian spinels’ Cr#, Mg#, Fe3+, Al2O3, and TiO2 concentrations indicate that the harzburgite formed in a fore-arc environment. The Al2O3 content and Mg# of the pyroxenes and the whole-rock Al2O3/MgO ratio and V contents of the harzburgite are also compatible with these processes. Consequently, the combined approaches demonstrated clear advantages over conventional chromitite exploration techniques, decreasing the overall costs and supporting the occurrence of chromite production at the site.

Factors controlling land subsidence in the Southern Hau River Region, Vietnam

The Vietnam's Mekong Delta (VMD) is known to be sinking below the sea due to climate change induced seawater level rise on one hand and land subsidence on the other hand. This phenomenon has deleterious ramifications for sustainable socio-economic advancement, manifesting in infrastructure degradation, recurrent inundation, intrusion of saline water, and reduction of habitable and cultivable areas within the region. Notably, in locales such as the Southern Hau River Region (SHRR), land subsidence rates as high as −10 cm/year have been documented, primarily associated with excessive groundwater extraction. Previous investigations have corroborated this relationship through the congruence between groundwater drawdown cones and areas of subsidence detected via InSAR (Interferometric Synthetic Aperture Radar) or through coupled Terzaghi consolidation theory-groundwater flow numerical modeling. This study extends the understanding of subsidence drivers in the SHRR beyond the groundwater level declining, encompassing tectonic activity, geological - lithological features, and landuse. Utilizing geostatistical analyses based on individual InSAR monitoring points, the study evaluates the respective contributions of these factors to land subsidence in the SHRR. Findings indicate that auto-compaction of young sediments, structural loading, and sediment compaction due to induced groundwater level decline are the principal factors precipitating land subsidence in the SHRR.

Geoheritage of the Sila National Park and surrounding areas (Northern Calabria, Italy)

ABSTRACT This paper introduces a geological map of the Sila mountain block (Northern Calabria, Italy), realized as a tool to promote knowledge of this geological landscape uniqueness and to develop effective geoheritage management and enhancement strategies, also from a geotouristic and geoeducational perspective. The Sila block is defined as a plateau whose morphology is deeply connected to its lithological characteristics and tectonic evolution that combined with exogenous processes over time has conditioned the landscape. The 1:60,000 scale map provides an overall scheme of the main geological units and tectonic elements constituting the study area, as a synthesis of thematic cartography existing in the literature coupled to targeted investigations and field surveys. It also displays the main geosites and geosite systems, identified with the purpose of communicating geoheritage processes/products, which favour an understanding of the surrounding environment, and for tourist purposes.

Characteristics and main controlling factors of the Sangonghe tight sandstone reservoirs in the Shengbei Sub-sag of the Turpan-Hami basin, China

The Sangonghe tight sandstone hydrocarbon reservoirs in the Shengbei Sub-sag of the Turpan-Hami Basin are key areas for hydrocarbon exploration. However, previous research has mostly focused on petrological characteristics, physical properties, and pore types. There is a lack of understanding regarding diagenesis, microscopic pore-throat features, and the impact of overpressure on the reservoir. This gap in knowledge poses a disadvantage for future studies and hydrocarbon exploration. This study examines the Sangonghe tight sandstone hydrocarbon reservoirs in the Shengbei Sub-sag of the Turpan-Hami Basin. It combines cast thin sections, physical property tests, high-pressure mercury injection experiments, low-temperature nitrogen adsorption experiments, and well logging overpressure identification to investigate the basic characteristics, diagenesis, and microscopic pore-throat features of these reservoirs. Based on this analysis, the study identifies the main controlling factors of the reservoir properties and presents three key findings. First, the reservoir rocks are primarily composed of lithic sandstone and feldspathic lithic sandstone with porosity ranging from 4% to 10% and permeability ranging between 0.1 and 10 mD, classifying it as a low-porosity, low-permeability tight sandstone reservoir. Second, the reservoir has undergone several diagenetic processes, with significant compaction and common occurrences of cementation and metasomatism. Acidic dissolution is the main dissolution process, but it is relatively weak. The pore-throat system exhibits poor and concentrated sorting, with nanometer-sized pores being predominant. These include 'ink-bottle' pores with narrow necks and wide bodies, and parallel plate-structured fissure pores. Finally, the development of the reservoirs is mainly influenced by sedimentation, dissolution, and overpressure. The parent rock provenance features a high content of stable heavy minerals, larger grain sizes, and thicker sand body layers. These factors enhanced the reservoir's resistance to compaction and promoted the development of primary intergranular pores. Additionally, organic acid fluids caused extensive dissolution of feldspar and lithic fragments, resulting in the formation of numerous secondary dissolution pores. Additionally, under-compaction overpressure helped preserve primary pores, while hydrocarbon generation overpressure extended the hydrocarbon generation period. This extended period provided the driving force for fluid migration, enhanced the transformation of reservoir space, and aided in hydrocarbon accumulation.

Numerical simulation of the stress-strain state near the injection well at deep disposal facilities for liquid radioactive waste

Relevance. The need to predict deformations of the earth's surface near injection wells pumping liquid radioactive waste, as well as their stability when pressure changes in the well during injection. Aim. To perform a numerical analysis of the stress-strain state of the structural elements of the injection well and the surrounding rock mass using the finite element method, to determine the magnitude of the deformations of the earth's surface and define the stability of the well and the strength of the cement stone at the maximum injection pressure of liquid radioactive waste. Objects. Near-wellbore zone of one of the injection wells located at the liquid radioactive waste injection site. Methods. Numerical finite element method for calculating the stress-strain state of the near-wellbore zone, taking into account the distribution of the elastic properties of rocks along the simulated section and the main structural elements of the well. Results. The authors have developed the numerical finite element scheme of one of the injection wells, taking into account its main structural elements, as well as allowing you to set the pressure distribution within the exploited horizon during the injection of waste. In the model, the distribution of the elastic properties of rocks along the section was set, taking into account their lithological features. The authors carried out the analysis of the hydrodynamic parameters of the well operation and determined the maximum pressure at the wellhead during the injection of liquid radioactive waste, equal to 1.71 MPa. Numerical modeling of the stress-strain state of the near-wellbore zone was performed in two stages: for the conditions of an idle well and taking into account the pressure distribution at the maximum waste injection pressure. The distribution of vertical displacements at the level of the earth's surface, as well as at the top of the operational horizon at the maximum pressure of liquid radioactive waste injection, is obtained. It is shown that at such a pressure, the largest uplifts will be: on the earth's surface – 4.5 cm, on the top of the production horizon – 11 cm. An assessment of the stability of the well structural elements at a maximum waste injection depth of 280 m, corresponding to the maximum pressure, showed that the stresses in the well and cement stone are much lower than the values that can lead to their violation. For cement stone, the safety factor at a maximum pressure of 1.71 MPa was equal to 7.8.

Comprehensive characterizations of core sediments recovered from Shenhu W17 well in South China sea and its impact on methane hydrate kinetics

Natural Gas Hydrates (NGH) is considered a vast unconventional energy source that holds significant promise in addressing future energy demands. In Shenhu area (located at northern slope of the South China Sea, SCS), there has been conducted a series of further studies of NGH such as exploration, drilling, and twice field production testing. The lithological characteristics of cores from marine sediments and their influence on methane hydrate (MH) formation are relatively unknown and merits further investigation. In this study, we conducted a chain of lithological characterization on the core sediments recovered from Shenhu W17 well, the coring well which located near the 1st NGH field production in SCS. The core sediments are classified as clayey-silt, its median grain size is 6.91 μm, comprising primarily clay minerals, quartz, and calcite. According to X-ray diffraction analysis, the main content of clay minerals is illite-smectite layers, illite, chlorite, and kaolinite, respectively. Porosity of the core sediments is 32.5% and the permeability is 7.8 mD based on mercury intrusion tests. Four types of primary pores are identified based on SEM and QEMSCAN analysis: intergranular pore, intercrystalline pore, intragranular pore, and pores associated with marine fossils. Moreover, the influence of the recovered core sediments (0–40 wt%) on MH formation kinetics were examined with morphology observed to elucidate the MH-core sediments interaction. The induction time was reduced significantly to ∼20 min in the presence of SCS core sediments. A two-stage MH formation behavior is observed with a maximum gas uptake of 134.1 Vg·Vw−1: (a) an initial MH formation at the gas-liquid interface with MH upward growth and fine-grain sediments migration; and (b) a second stage of significant MH growth with layered formation of MH and core sediments. The capillary channels of MH formed facilities the migration of core sediments, which in turn provides additional gas-liquid contact area for MH formation. The study provides valuable insights on the role Shenhu core sediments in MH formation, which is essential for understanding the spatial heterogeneity of NGH in reservoir and for designing suitable production strategy.

Petrological Characteristics and Physico-Mechanical Properties of Dokhan Volcanics for Decorative Stones and Building Material Applications

Wide varieties of igneous rocks are extensively utilized as stones for decoration purposes and as a potential source for building. With the use of petrological (mineralogical and chemical) and physico-mechanical analyses, the current work accurately mapped the Dokhan Volcanics (DV) and utilized them as decorative stones and their prospective in building materials using Frattini’s test. Field observations indicate that metavolcanics, DV, and monzogranites are the principal rock units exposed in the studied area. The DV rocks are characterized by a dense series of stratified, rhyolitic to andesitic lava interspersed with a few pyroclastics. Andesite, andesite porphyry, dacite, and rhyolite are the primary representatives of the selected DV. The lack of infrequent appearance of mafic units in the current volcanic eruptions indicates that the primary magma is not mantle-derived. This is supported by their Mg# (17.86–33.57). Additionally, the examined DV rocks have Y/Nb ratios above 1.2, suggesting a crustal source. The role of fractionation is interpreted by their variation from andesite passing through dacite to rhyolite, which is indicated by gradual negative distribution groups between silica and TiO2, Fe2O3, CaO, MgO, Co, and Cu from andesite to rhyolitic lava. Additionally, a wide range of widely used DV rocks like Y/Nb, Rb/Zr, and Ba/Nb point to crustal contamination in the rhyolitic rocks. The partial melting of the lower crust can produce andesitic magma, which ascend to higher crustal levels and form lava of calc-alkaline. A portion of this lava may split, settle at shallow crustal depths, and undergo differentiation to create the DV rocks. Based on the results of physico-mechanical properties, the studied samples met the requirements for natural stone to be used as decorative stones, whether as interior or exterior installations. The pozzolanic assessment of the studied rocks revealed their usability as supplementary cementitious materials in the building sector.

Lithology and sedimentation conditions of the latest Cretaceous of the Klementyeva Mountain section (Eastern Crimea)

Overall study of the boundary Maastrichtian–Danian deposits of Klementyeva Mountain section (Eastern Crimea) was carried out. The lithological characteristics of carbonate, carbonate-argillaceous and clastic rocks were described in detail, the dynamic of changes in foraminifera assemblages was analyzed. For the first time, geochemical and isotopic data were obtained for this section. The stratigraphic complement of the Upper Maastrichtian and Lower Danian has been specified. Late Campanian – Early Maastrichtian age of the underlying deposits was established, for the first time. The Klementyevskaya Formation was formed in deep-sea pelagic paleoenvironments on the submerged part of the outer shelf, and the overlying Lower Danian sediments were formed in shallow waters of the inner shelf with terrigenous sedimentation and high hydrodynamic activity.

Real-time lithology identification from drilling data with self & cross attention model and wavelet transform

Accurate lithology identification during drilling operations is pivotal for optimizing drilling efficiency and informed decision-making. Traditional methods, such as mud logging, Logging While Drilling (LWD), and Measurement While Drilling (MWD), often face challenges such as delays and inaccuracies, lacking consistent utilization of real-time engineering data across all drilling sites. Consequently, these methods frequently overlook the complex interactions of influencing factors, resulting in underutilized geological information that could significantly enhance operational outcomes. This paper introduces the SelfAttention-CrossWT (SACWT) model, an innovative approach that integrates self-attention and cross-attention mechanisms with Wavelet Transform (WT) to utilize real-time drilling parameters, including Weight on Bit (WOB) and Rate of Penetration (ROP). The SACWT model effectively harnesses both temporal and frequency-domain characteristics of drilling data, facilitating comprehensive extraction of latent patterns and dynamics, which substantially improves lithology identification accuracy. The output of the model is the real-time lithology classification at the drill bit's depth. The performance of the SACWT model is compared with Long Short-Term Memory (LSTM) networks and a Self-Attention (SA) model that does not utilize frequency-domain data. When applied to a dataset from the Volve oil field, the SACWT model achieved identification accuracies of 87% and 91% in two separate test wells, outperforming traditional methods. These results underscore the model's efficacy and the significant potential of utilizing real-time drilling data for enhanced lithological characterization. This breakthrough offers a robust framework for future exploration and development operations, providing a more precise, efficient, and cost-effective approach to geological analysis.

Petrological characterization for material provenance of haniwa earthenware from mounded tombs in the Kibi region, Japan

To determine the provenance of the materials used in the production of haniwa earthenware unearthed from mounded tombs (kofun) in the Kibi region (modern Okayama Prefecture) during the Kofun period (late 3rd – 6th century CE) of Japan, we carried out petrological analyses of haniwa sherds, including optical microscopy, X-ray diffractometry, X-ray fluorescence spectroscopy, and electron-probe analysis. The 25 haniwa sherds analyzed from 12 representative mounded tombs are composed of mineral and rock inclusions with variable grain size set in a clay matrix. The dominant inclusions are quartz, K-feldspar, and plagioclase, associated with minor amounts of amphibole, volcanic glass, and granitic rocks in all the haniwa sherds, and small amounts of hornfels, quartz rock, and accessory minerals, including mica, ilmenite, and chromite, in some of the sherds. Amphibole and plagioclase have compositional variations indicative of the mixing of tephra and granitic components. The compositions of volcanic glass inclusions are similar to those of the Aira-Tanzawa and Kikai-Akahoya tephras widely distributed in southwestern Japan. Bulk chemical compositions show magmatic differentiation trends, which are variable between individual tombs. From these results, it is concluded that the paste materials of haniwa in the Kibi region were commonly derived from weathered granitic rocks mixed with minor amounts of three widespread tephras. The variations of chemical and mineralogical compositions are probably the reflection of local geologic settings, suggesting the presence of specific mining sites of paste materials around each tomb. The mining sites could be located at the bases of hills of granitic rocks covered by widespread tephras and in some cases, near the flood plain of big river systems.

Provenance and tectonic evolution of the forearc basin along the northwestern Central Qilian belt, northeastern Tibet

The age and properties of detrital zircon grains in a forearc basin provide crucial information on the history of convergent plate margins. These data can be used to constrain provenance dispersal patterns, establish source-to-sink relationships, and reveal the tectonic framework and subduction history. The Qilian orogen in the northeastern margin of the Tibetan Plateau records the tectonic history of the Proto-Tethys Ocean from its initial spreading and subduction to final closure. However, the timing of subduction initiation and the subduction polarity of the Proto-Tethys Ocean remain controversial. The Qilian orogen includes the North Qilian, Central Qilian, and South Qilian belts. A succession of sedimentary rocks along the northwestern margin of the Central Qilian belt, previously considered to be Precambrian in age, has been redefined based on detailed field investigation and geochronology. U-Pb analysis of detrital zircon grains from metasedimentary rocks of the Gongcha Group of the northwestern Central Qilian belt yielded Paleozoic ages between 530 and 470 Ma, with prominent Mesoproterozoic and Paleoproterozoic ages between 1800 and 1000 Ma. In contrast, the overlying Duoruonuoer Group yielded predominantly early Paleozoic ages between 465 and 434 Ma, with a few older age populations. This change in source is reflected in a substantial increase in volcanic detritus within the Duoruonuoer Group as compared to the Gongcha Group. The detrital zircon age spectra and lithologic characteristics indicate the Gongcha and Duoruonuoer Groups constitute the lower and upper volcanic-sedimentary strata in the forearc basin. Based on resemblances of statistical ages and εHf(t) values of zircon, we interpret that the early Paleozoic intrusive and volcanic units and Precambrian basement rocks of the Central Qilian belt were the main source of the Gongcha and Duoruonuoer Groups, verifying the southward subduction of the North Qilian Ocean, a portion of the larger Proto-Tethys Ocean, beneath the Central Qilian belt. The detrital zircon ages reveal that the initial subduction of the Proto-Tethys Ocean in the Qilian orogen occurred ca. 530 Ma and closed ca. 435 Ma. These forearc sedimentary units constitute the tectonic boundaries between the Central Qilian belt and North Qilian belt.

A new rhynchonellid fauna (Brachiopoda) from the Wordian (middle Permian) of Coahuila, Mexico: Stratigraphy and paleoenvironments

Seven brachiopod species of the order Rhynchonellida of a new locality (Las Margaritas I section) from the Las Delicias Formation in Coahuila, Mexico are described. The fauna includes four taxa identified as Bryorhynchus bisulcatum, Leiorhynchioidea schucherti, Leiorhynchoidea amygdaloidea, and Paranorella imperialis, as well as three species assigned with open nomenclature: Leiorhynchioidea cf. scelesta, Stenoscisma sp., and Rhynchopora sp. The brachiopod fauna identified, together with the record of different middle Permian ammonoids allowed us to establish a Wordian (middle Guadalupian) age for the Las Margaritas I section. The assignment of this relative age enabled restricting the stratigraphic range of Leiorhynchioidea schucherti and Paranorella imperialis to the middle Guadalupian since previously had only been related inaccurately to the middle Permian. The record of the species Bryorhynchus bisulcatum, Leiorhynchioidea cf. scelesta, and Leiorhynchoidea amygdaloidea, as well as the genus Stenoscisma is the first in Mexico. The preservation of specimens, lithological features, and associated fauna suggest that rhynchonellid brachiopods were deposited in different platform facies: shallow lagoonal or offshore, characterized by low to medium energy, stenohaline conditions, and continuous terrigenous input.

Groundwater dynamics clustering and prediction based on grey relational analysis and LSTM model: A case study in Beijing Plain, China

Study regionBeijing Plain, China Study focusThe traditional zoning of groundwater systems relies on lithological characteristics and hydraulic connections. However, the influence of climate change and human activities has led to the emergence of diverse dynamic patterns within these systems. Additionally, the differences in groundwater dynamic characteristics are often ignored when modeling with machine learning methods. In this study, a new clustering method named GRA-CLU was proposed to classify dynamic types of groundwater. Then, regional models are built using LSTM based on the dynamic zoning, aiming to incorporate hydrogeological significance into the pure data-driven model.New hydrological insights for the region: The GRA-CLU method classified the study area into six groundwater dynamic types. Compared with the traditional hydrogeological units, the new zoning result identified two dynamic types that have never been considered: urban influence zone and mountain-plain junction zone where surface water interacts with groundwater. Through analysis, the significant rise of groundwater levels in 2021 was more influenced by heavy rainfall events rather than human activities. This study further explored the performance of LSTM regional models based on the six dynamic zones. The results indicated that the NSE of models increased by 5.7–50.0 %, the improvement was more obvious in zones with irregular fluctuations. The RMSE decreased by 31.5–59.8 %, particularly noticeable in zones with regular annual fluctuations and large samples.