ABSTRACT The Shilu Iron Mine is one of China's largest high‐grade haematite deposits. Intense regional magmatism has also generated significant reformed magnetite ores. However, the underutilisation of these resources has led to resource waste. This study analyses representative magnetite ore samples to characterise process mineralogical attributes, including chemical composition, mineral species, content, dissemination, grain size, and the occurrence states of Fe and associated Co and Ni, to provide new insights into process optimisation and comprehensive resource utilisation. Results suggest that Fe predominantly occurs in magnetite, with concentrations ranging from approximately 69.81% to 71.46%. Magnetite and pyrite contain Co in favourable occurrence states, even at subeconomic grades. Ni is present in native iron, although in minimal amounts and difficult to separate. Magnetite mainly exhibits euhedral to subhedral equigranular textures, with dispersed features and well‐defined boundaries with gangue minerals. Pyrite occurs in banded or disseminated aggregates. With an estimated 5%–10% gangue entrainment, the iron ore concentrate grade can reach 65.0%–68.5%. Due to the heterogeneous medium‐to‐fine dissemination of magnetite, a staged grinding–separation strategy is recommended: an initial grind to 74 μm (200 mesh) for low‐intensity magnetic separation at the roughing stage, followed by regrinding of the middlings to 44 μm (325 mesh) before flotation, thereby improving magnetite liberation and recovery while limiting over‐grinding and flocculation‐related losses. In summary, reformed magnetite ores show considerable Fe recovery potential. Co can be partially utilised, whereas Ni offers limited value for comprehensive utilisation.
ABSTRACT The Triassic in the Tarim Basin is an important target for continental oil and gas exploration. However, the basin‐scale spatiotemporal configuration of sedimentary systems and the distribution of sand bodies remain poorly constrained due to the combined effects of multi‐stage tectonic activity, variable provenance supply, and complex sediment transport pathways, thereby hindering the prediction and exploration of high‐quality reservoirs. Seismic, logging, core, and heavy‐mineral data were integrated to investigate the provenance of Triassic deposits. Through seismic facies tracing, sedimentary facies identification, and provenance analysis, the types and distribution patterns of sedimentary systems under different provenance settings were systematically constrained. The results indicate that four major provenance systems developed during the Triassic in the Tarim Basin. The western provenance was mainly derived from the Awati tectonic belt and the Keping fault uplift, forming proximal alluvial fan and fan‐delta deposits. The southern provenance was controlled by the uplifted northern margin of the Kunlun Mountains and was represented by a distal fluvial delta system. The northern provenance was jointly influenced by the Kuruktag Mountains and the Tabei Uplift, forming a mixed depositional system comprising alluvial fans, fan deltas, and braided river deltas. The eastern provenance was mainly supplied by the Qilian Mountains and the Altyn Tagh tectonic belt, resulting in a distal braided river delta system. These results highlight the strong control of regionally differentiated provenance systems on Triassic sedimentary filling and provide a geological basis for basin‐wide reservoir prediction and exploration.
ABSTRACT Understanding reservoir heterogeneity in siliciclastic systems requires integrated analysis across multiple scales. This study investigates the Early Cretaceous Lower Goru Formation in the Lower Indus Basin using a multiscale integrated approach that combines seismic stratigraphy with pore‐scale characterisation to constrain depositional environments, sequence architecture, pore system, mineralogy and diagenetic evolution. This study provides the first integrated framework linking seismic‐scale stratigraphy to pore‐scale diagenesis in the Lower Goru Formation, enhancing reservoir quality prediction in mature exploration settings. An integrated workflow of core description, petrophysical analysis, petrography, SEM, and 2D seismic data is employed to delineate stratigraphic architecture and depositional trends. Reservoir heterogeneity is assessed through an evaluation of depositional and diagenetic controls, while machine learning‐based classification enhances facies prediction and strengthens interpretive reliability. Based on core analysis, four facies associations were identified within the reservoir succession, including shoreface, mouth bar, and shelf delta lobe facies associations. The Lower Goru Formation comprises one second‐order sequence and nine third‐order sequences within the studied reservoir interval. Petrographic analysis reveals that the sandstones are fine to medium grained and moderate to well‐sorted reflecting a relatively uniform grain size distribution. Their mineralogical composition is diverse comprising litharenite, feldspathic arenite and quartz arenite. SEM observations reveal a complex pore system comprising primary intergranular macroporosity, secondary intragranular macropores, and intercrystalline micropores, which collectively exert a strong influence on reservoir storage capacity. Diagenesis led to the formation of chamosite and ooids that developed chlorite coatings which inhibited extensive quartz overgrowths while subsequent matrix recrystallisation produced microporous chlorite that further influenced reservoir properties. These integrated findings provide critical insights into the sequence stratigraphy and facies distribution of the Cretaceous sedimentary system and offer valuable guidance for hydrocarbon exploration in the Indus Basin.
ABSTRACT The onset of the Paleo‐Pacific subduction beneath the South China Block (SCB) remains controversial. This study addresses this issue by analysing the Mesozoic tectonic transition from the E–W‐trending Tethyan tectonic domain to the NE–SW‐trending Paleo‐Pacific tectonic domain within the SCB. Based on comprehensive field investigations conducted across the eastern, central and western segments of the SCB, this study systematically characterises the structural deformation patterns and constrains the timing of tectonic events in these regions. In the western SCB (Xuefengshan intercontinental tectonic system), a Triassic transition is evidenced by a shift from E–W to NNE‐trending folds, as well as the diachronous nature, indicating an east‐derived force. Fault‐strata relationships and Ar–Ar dating indicate that this eastward‐propagating deformation front was active during the Early–Middle Jurassic in the Middle–Lower Yangtze area and during the Middle–Late Jurassic in the southeastern coastal area. A suite of NE‐trending thrust‐nappes, diverse folds (box, chevron, comb and trough), and strike‐slip faults developed in the Middle–Lower Yangtze and southeastern coastal areas during the Early Yanshanian (J 1 –J 2 ). These eastern regions record SE–NW compression from thrust‐nappe systems and folds, unequivocally linking the eastward‐younging tectonic transition to the progressive subduction of the Paleo‐Pacific Plate. Consequently, these findings robustly support a Late Triassic initiation for the Paleo‐Pacific subduction beneath the South China Block.
ABSTRACT Lacustrine sedimentary environments and sand‐body architectures are influenced by lake‐level fluctuations and climate, but understanding their relative contributions in deeply buried successions remains challenging due to the overprinting of diagenetic and tectonic processes. The Permian Shihezi Formation in the southwestern Ordos Basin provides an ideal setting for investigating how lake‐level variability influenced shallow‐water braided delta migration and reorganisation. Recent hydrocarbon exploration has yielded high‐quality cores and well logs, enabling detailed reconstructions of depositional processes. Using these datasets, we reconstruct the sedimentary characteristics, facies architecture and controlling processes of the Permian Shihezi Formation, developing an updated depositional model for its braided‐delta system. A revised sequence‐stratigraphic framework was established from integrated core‐log interpretation, aiding facies and systems‐tract identification. Facies analysis reveals that the braided‐delta system developed on a gently inclined basin margin with strong but variable hydrodynamics, frequent lake‐level shifts and significant long‐distance sediment transport. These characteristics make the Shihezi Formation a valuable analogue for shallow‐water continental systems preserved in other deeply buried basins worldwide. Stratigraphic patterns indicate a transition from early deposition characterised by climate‐related lake‐level variability broadly coincident with global eustatic cycles to later deposition increasingly controlled by regional tectonics, aridification and variations in sediment supply. Early‐stage sedimentation shows a broad temporal correspondence with higher‐order global highstand–lowstand cycles, while later stages record autogenic feedbacks through delta progradation, channel mobility and shoreline stabilisation. These trends suggest that the broad temporal correspondence between global eustatic cycles and regional lake‐level variability may reflect a common climatic background, whereas regional tectono‐climatic controls increasingly shaped later lake‐level and lacustrine‐system evolution.
ABSTRACT The fossil record serves as the primary source of information for understanding how biodiversity has changed over deep time, offering unique insights into the dynamics of diversification and extinction and their underlying drivers. Much of the focus has been on global diversity trends, often overlooking the complex interplay between origination and extinction events that have shaped life through geological time. In this study, we present taxonomically described fossil leaves from the early Paleogene horizon of Rajasthan (India), that exhibit morphological affinities with the extant genera of Zingiberales. Based on their unique combination of morphological characters, the fossils are assigned to a new genus and species, that is, Paleozingiberum gurhanensis gen. nov. et sp. nov., and identified as an extinct genus within the Zingiberales enriches our knowledge of the evolutionary history of the group, providing critical insights into its early diversification, paleobiogeography, and ecological adaptations during the early Paleogene. Our findings expands the known diversity of extinct Zingiberales and suggest that the initial radiation of the order included a now‐extinct clade that survived the end‐Cretaceous mass extinction but disappeared during the Cenozoic. This systematic analysis not only strengthens the fossil record of the order but also contributes to a broader understanding of macroevolutionary trends, including patterns of diversification and extinction across deep time. These fossils, along with earlier finds, highlights the key role of the Indian subcontinent in early evolution and diversification of this tropical monocot lineage.
ABSTRACT This study aimed to reconstruct weathering intensity, sedimentation rates and to elucidate associated environmental changes recorded in floodplain deposits of the Chemoga watershed of the Upper Blue Nile Basin (UBNB) in Ethiopia. A 20‐m sediment core, CGC2023, was analysed for major oxide geochemistry ( n = 23), clay mineralogy ( n = 23) and carbon dating ( n = 18) to characterise temporal variations in weathering and sedimentation processes. Radiogenic dating reveals that the core stratigraphy experienced multiple hiatuses, sediment discontinuities and an age reversal, which collectively indicate substantial paleoenvironmental changes in the region. The major oxide concentrations indicate a depth‐dependent concentration change, reflecting temporal shifts in weathering intensity. The upper section (10 m) of the core shows intense chemical alteration, with enrichment of Al 2 O 3 , Fe 2 O 3 and MnO, and depletion of SiO 2 , Na 2 O, MgO and K 2 O. In addition to the geochemical data, the clay mineralogy result illustrated the clay mineralogy assemblage is depth dependent change, kaolinite (up to 67%) in the upper stratigraphy, absent when the depth increases, while illite dominates (up to 100%) on depth increase, chlorite (up to 56%), and smectite (up to 18%) occur in the core profile with distribution varying with depth and age. The sediments were produced through four distinct stages of chemical weathering and erosion (~42.5–1.3 cal kyr BP). Stage I (undated) marks the beginning, with a basal layer showing minor chemical alteration. The transition to Stage II (42.58–39.99 cal kyr BP) involves an increase in chemical weathering intensity (CIA, 75.2–79.9) and a sedimentation rate (0.42–0.44 mm year −1 ). Stage III (37.19–18.58 cal kyr BP) follows, characterised by declining chemical weathering (CIA, 51.6–74.4) and rising sedimentation rate (0.06–1.105 mm year −1 ). Transitioning to Stage IV (9.012–1.686 cal kyr BP), advanced chemical weathering (CIA, 85–89) and a high depositional rate (0.27–4.17 mm year −1 ) emerge, likely reflecting the intensified Holocene climate variability and anthropogenic impact.
ABSTRACT The enrichment of tricyclic terpanes (TT) relative to hopanes (H) is a well‐documented phenomenon in marine‐derived crude oils from the Platform‐Basin region of the Tarim Basin, NW China. However, the genetic mechanisms remain incompletely understood and their petroleum geological implications lack systematic investigation. To investigate their enrichment mechanism, this study examines the distribution characteristics of tricyclic terpanes in crude oils from the Tazhong and Tabei areas that have been subjected to different secondary processes. The results show that the C 23 TT/(C 23 TT + C 30 H) ratio shows an exponential positive correlation ( R 2 = 0.87) with the C 28 25‐N/C 29 hopane ratio (biodegradation indicator) in biodegraded crude oils, while in Tabei crude oils this ratio exhibits a linear positive correlation with the Ts/(Ts + Tm) ratio (thermal maturity indicator), indicating both biodegradation and thermal maturity can cause tricyclic terpane enrichment relative to hopanes. In Tazhong oils, the C 23 TT/(C 23 TT + C 30 H) ratio displays a negative correlation with the toluene/ n ‐heptane ratio (gas wash indicator), suggesting gas washing leads to relative depletion of tricyclic terpanes. This decrease may be superimposed by the effects of evaporation and migration fractionations. The diagram of C 23 TT/(C 23 TT + C 30 H) versus Ts/(Ts + Tm) effectively distinguishes normally matured oils, severely biodegraded oils, and the oils experienced strongly evaporation distillation, showing good potential for genetic identification of variously altered oils in complex petroleum systems.
ABSTRACT The Sulaiman Range, a lesser‐explored complement in Southern Punjab, has yielded promising fossil discoveries through recent expeditions. Extensive fieldwork in the Sakhi Sarwar outcrops (Dera Ghazi Khan district) led to the identification of a fossil‐rich locality situated 9 km west of Sakhi Sarwar. Lithological analysis and comparisons with documented mammalian fauna from the Sulaiman Range and Siwaliks suggest the Drebh site belongs to the Litra‐Chaudhwan Formation, correlating with the Chinji‐Dhok Pathan Formation of the Siwaliks. This site showcases a diverse assemblage of fossil faunas, spanning the late Middle Miocene to Pliocene epochs, underscoring its significance for regional paleontological research. Overall, 24 fossil specimens have been collected and described here, which include Selenoportax lydekkeri , Selenoportax vexillarius , Pachyportax latidens , Tragoportax punjabicus , Merycopotamus dissimilis , Bovid indet., Reduncini indet., Dorcatherium majus , Dorcatherium minus and Dorcatherium nagrii . The specimens include horncores, fragments of the maxillae and mandibles, as well as isolated teeth. First‐time documentation from this locality, these fossils augment taxonomic, stratigraphic, and biogeographic data. Based on faunal affinities and faunal composition with the Nagri‐Dhok Pathan Formation (Siwaliks), suggest a shared late Middle Miocene–Pliocene ecosystem constrained the age and ecological context of the Sulaiman Range. Overall, the faunal composition recommends a late Middle Miocene to Pliocene age and also indicates that the study area was part of a large‐size ecosystem during the time in question.
ABSTRACT Late Neoproterozoic post‐collisional granites at El‐Bakriya area include calc‐alkaline granite (monzogranite) and A‐type granites (syenogranite and alkali feldspar granite). The post‐collisional A‐type granites form a ring complex that consists of an inner core of alkali feldspar granite and outer syenogranite with gradational contacts between them. Most of the mineralization in the El‐Bakriya area is concentrated in alteration zones such as albitization and greisenization, where many fluorite and baryte veins or stocks are found to be closely associated. PRISMA hyperspectral data distinguish among these post‐collisional granitoid types, utilizing various image processing techniques. Remote sensing analysis further highlights that the transitions between the granitic plutons are predominantly affected by hydrothermal alteration. A‐type granites contain a diverse array of accessory minerals including silicate minerals (garnet, zinnwaldite, muscovite, zircon, allanite, thorite, topaz, titanite, chlorite, and epidote) and non‐silicate minerals (columbite, pyrochlore, bastnäsite, monazite, apatite, fluorite, and Fe‐Ti oxides). Monzogranite has geochemical characteristics of post‐collisional calc‐alkaline granite, while syenogranite and alkali feldspar granite show characteristics of anorogenic granite. Compositional gaps and sharp intrusive contacts between the two phases suggest distinct magma sources. The post‐collisional calc‐alkaline monzogranite was evolved from a primary magma that was generated during the delamination process. This process induces extensive partial melting, generating mafic magmas that eventually evolved into monzogranite. The overall chemical characteristics of the A‐type granites are consistent with evolution from a single parental magma that was generated by partial melting of a juvenile crust, followed by extensive fractional crystallization and overprinting by late magmatic fluids. The alkali feldspar granite was formed at a shallower depth (5.5–9.3 km; av. 7.3 km) than syenogranite (6.3–9.9 km; av. 8.4 km). El‐Bakriya intrusion has mineralized zones associated with the apical and marginal parts of the alkali feldspar granite, where the hydrothermal solutions and the volatiles are concentrated in the upper part of the magma chamber before complete crystallization of granitic melts.
ABSTRACT Pre‐orogenic orthogneisses with Tonian‐Cryogenian crystallization ages from the Eastern and Southern Dom Feliciano Belt are preserved as orthogneiss xenoliths and roof pendants intruded by voluminous post‐collisional magmatism during the amalgamation of Western Gondwana. These rock fragments occur in different localities in Southern Brazil and Uruguay, encompassing distinct units that include the gneisses from Chácara das Pedras and Piratini, and the Cerro Bori Orthogneisses and Chafalote Metamorphic Suite (CMS) granulites from the Cerro Olivo Complex. These rocks may be related to one another, as they share similar crystallization ages of approximately 800 Ma, subduction‐related geochemical affinities, and record evidence of a collisional metamorphic event at approximately 650 Ma. However, their common metamorphic history is poorly characterized, because most felsic‐intermediate protoliths lack suitable mineral paragenesis for conventional geothermobarometric and P–T modelling techniques. This work presents a study of the metamorphic evolution of these high‐grade sequences, based on petrography, thermobarometry, and pseudosection modelling. Peak metamorphic conditions vary significantly across the studied units: from 3.2–7.5 kbar and 520°C–670°C in the Chácara das Pedras Gneiss, to 4.5–6.2 kbar and 690°C–800°C in the Piratini Gneiss, 7.1–7.5 kbar and 765°C–795°C in the CMS granulites, and 4.3–5.5 kbar and 625°C–740°C in the Cerro Bori Orthogneiss. In conjunction with available literature data, the Punta del Este Terrane records higher average pressures (ca. 6–8 kbar) than the Pelotas Terrane (ca. 5 kbar). Variable preservation of near‐isothermal decompression features reflects different exhumation mechanisms: channel flow in CMS granulites and rapid erosion in Piratini Gneiss, versus slower exhumation in Cerro Bori and Chácara das Pedras units. Metamorphic field gradients (27°C/km–39°C/km) indicate moderate thermal regimes comparable to Himalayan‐type collisional settings, supporting the correlation of these orthogneisses as metamorphic remnants of the Piratini Orogeny within the Brasiliano/Pan‐African orogenic cycle.
ABSTRACT The Bainiuchang deposit, located in southeastern Yunnan Province, is one of the most important super‐large Pb–Zn–Ag deposits in China. This study focuses on calcite from this deposit. Based on systematic field geological surveys and sampling, combined with macroscopic morphological observations and microstructural analyses, LA‐ICP‐MS was employed to systematically investigate the petrographic characteristics, genetic mechanism, and formation process of calcite, as well as the constraints of fluid evolution on mineralisation. The results show that calcite can be classified into ore‐bearing and barren types, both occurring as veins and in dendritic‐network forms. Their morphological features indicate that structural control was the dominant factor governing vein formation and modification. The total Fe + Mn contents of ore‐bearing calcite (> 0.94%) are significantly higher than those of barren calcite (0.13%–0.22%). The ore‐bearing calcite displays a wide range of ΣREE (0.99–736.98 μg/g) and diverse REE distribution patterns, whereas barren calcite exhibits low ΣREE (0.34–18.83 μg/g), weak REE fractionation and LREE depletion. Ce anomalies are not pronounced in either type; however, Eu anomalies indicate a gradual transition of the ore‐forming fluid from reducing to oxidising conditions. The ore‐forming materials were derived predominantly from deep granitic magma. Rare earth elements were transported mainly as complexes in the fluid and their distribution characteristics were significantly influenced by the influx of meteoric water and interaction with wall rocks. Geochemical indicators such as Fe, Mn and REE can thus serve as key discriminators for distinguishing ore‐bearing from barren calcite. Integrating these results with previous studies, this study concludes that the Bainiuchang deposit is a typical magmatic‐hydrothermal deposit.
ABSTRACT Accurate evaluation of fracture effectiveness and activity in buried‐hill reservoirs remains challenging because fracture development is commonly controlled by multi‐stage tectonic overprinting, lithological heterogeneity, weathering‐related mechanical contrasts and complex present‐day stress fields. These difficulties are, particularly, pronounced in buried‐hill intervals composed of crystalline basement rocks, metamorphic or igneous lithologies and weathered fractured zones, where fracture density alone is insufficient to determine reservoir effectiveness. To address this problem, this study develops a geomechanics‐constrained and interval‐specific workflow for evaluating fracture activity and effectiveness within buried‐hill reservoirs. The proposed approach integrates laboratory‐derived rock mechanical parameters, log‐based dynamic–static elastic parameter calibration, seismic structural interpretation, lithology‐constrained three‐dimensional geomechanical modelling and fracture‐scale stress analysis. The workflow explicitly links buried‐hill lithological subdivision, present‐day stress tensor reconstruction, fracture orientation characterisation and three‐dimensional Mohr stress analysis. Different buried‐hill lithologies and weathering zones are assigned distinct mechanical parameters to better represent the vertical and lateral heterogeneity of the reservoir interval. The numerical stress model is iteratively constrained by measured in situ stress data, wellbore information and structural interpretation to improve mechanical consistency. Fracture activity is quantitatively evaluated by resolving the normal and shear stresses acting on mapped fracture sets under the present‐day stress regime, whereas fracture effectiveness is assessed by jointly considering fracture orientation, stress state, lithological layering and mechanical stratification. Model predictions are further validated using borehole image logs, drilling responses and production performance, allowing effective fracture intervals within the buried hill to be identified more reliably. The results show that effective fractures in buried‐hill reservoirs are primarily controlled by stress–structure–lithology coupling rather than by fracture density alone. Fractures that are critically oriented with respect to the present‐day stress field and hosted in mechanically favourable lithological or weathered intervals exhibit higher activation potential and better agreement with observed fracture development and well productivity. This study provides a more geologically constrained, mechanically consistent and interval‐specific framework for fracture effectiveness evaluation in buried‐hill reservoirs. The proposed workflow improves the linkage among geological interpretation, geomechanical simulation, fracture activity assessment and reservoir performance prediction and, therefore, offers practical guidance for sweet‐spot identification and development optimisation in fractured buried‐hill systems.
ABSTRACT The Middle Miocene Climatic Optimum (MCO) was followed by the Middle Miocene Climatic Transition (MMCT), a major Cenozoic cooling event that triggered evaporite deposition in the Carpathian realm. At Muntele Piatra Verde (MPV), Eastern Carpathians, Romania, this interval offers a rare opportunity to examine the interplay between global climate change, regional salinity crises and volcanic activity. The present study investigates how marine conditions at MPV evolved from the peak warmth of the MCO into the cooling of the MMCT, as recorded in lithology, foraminiferal assemblages and stable isotope data. We integrate mineralogical analyses, detailed biozonation and δ 13 C and δ 18 O measurements of Orbulina spp. across two stratigraphic successions. In Section 1 (S1), volcanic‐influenced sandstones in the lower sector with low‐diversity foraminifera give way to carbonate‐rich marls with diversified assemblages, culminating in the first occurrence (FO) of Globoturborotalia druryi and Globorotalia transsylvanica at the Langhian–Serravallian boundary (~13.82 Ma). Tuffs interbedded with gypsum mark the onset of the Badenian Salinity Crisis (~13.8 Ma), followed by Section 2 (S2) represented by brecciated gypsum and overlying shales. Biostratigraphy and radiometric dating indicate evaporite deposition lasted ~200 kyr (13.8–13.6 Ma). In this time interval, δ 18 O‐derived sea‐surface temperatures (SSTs) dropped from ~26°C below the tuff (S1) to temperatures less than 14°C above the gypsum (S2), while δ 13 C values capture the CM6 positive excursion above the boundary. This multiproxy record documents a ~10°C cooling across the MMCT, firmly linking regional evaporitic and volcanic phases to global climate change. These findings apply to various sedimentary settings, enabling both regional and global correlations of events.
ABSTRACT In fault‐controlled composite hydrocarbon accumulation zones, the transport capacity of oil‐source faults governs hydrocarbon enrichment. This study focuses on the Mesozoic oil‐source faults in the Chengdao‐Zhuanghai area of the Bohai Bay Basin. By integrating data on oil‐source fault characteristics, well logging and hydrocarbon reserve distribution and employing methods such as effective normal fault stress analysis, shale gouge ratio analysis, cross‐plot analysis and analytic hierarchy process, the factors influencing the transport capacity of oil‐source faults were identified. A quantitative evaluation formula for oil‐source fault transport capacity was established and its impact on hydrocarbon accumulation in the Mesozoic strata was analysed. The research shows that among the major controlling faults in the Mesozoic, the Chengbei Fault, Chengbei 30 North Fault, Chengbei 30 South Fault, Zhuanghai 104 South Fault and Chengbei 304 Fault are oil‐source faults, while the Chengbei 20 Fault is a non‐oil‐source fault. The transport capacity of Mesozoic oil‐source faults is primarily determined by three factors: fault activity characteristics during the hydrocarbon accumulation period, fault sealing properties and static fault characteristics. Oil‐source faults with greater extension lengths, higher fault activity rates during the accumulation period and poorer sealing properties exhibit stronger hydrocarbon transport capacity, resulting in larger hydrocarbon distribution areas in the associated Mesozoic blocks. The transport capacity of oil‐source faults correlates with the hydrocarbon reserves in the related Mesozoic blocks, with a correlation coefficient of 88%. The findings of this study provide guidance for further exploration of fault‐block reservoirs in faulted basins.
ABSTRACT The Chah‐Nar Pb–Zn deposit in the southern Sanandaj–Sirjan Zone, Iran, represents Early Palaeozoic stratiform sulfide mineralization hosted by organic‐rich volcano‐sedimentary rocks deposited in a Proto‐Tethyan back‐arc basin. Despite the occurrence of stratiform Pb–Zn mineralization in the Southern Sirjan Basin, the origin, fluid evolution, and regional metallogenic significance of the Chah‐Nar deposit remain insufficiently constrained. This study integrates field observations, ore petrography, lithogeochemistry, fluid inclusion microthermometry, and SCO isotope data to evaluate the ore‐forming processes and genetic setting of the deposit. Mineralization occurs as stringer, massive, and bedded ore facies, which are best interpreted to record a transition from early seafloor to shallow subseafloor sulfide deposition to later hydrothermal replacement. Fine‐grained bedded sulfides are interpreted to represent an early synsedimentary to early diagenetic stage, whereas coarser massive and replacement sulfides are most consistent with later focused hydrothermal flow, possibly guided by synsedimentary extensional faults. Fluid inclusions in quartz associated with the stringer and massive ore facies yield homogenization temperatures of 165°C–268°C and salinities of 3.0–9.9 wt.% NaCl equivalent, consistent with low‐ to moderate‐salinity basinal fluids. Sulfur isotope compositions of sulfides (δ 34 S CDT = −5.8‰ to +16.9‰) indicate seawater‐derived sulfur modified by multiple reduction pathways, with bacterial sulfate reduction dominant in the bedded ores and thermochemical sulfate reduction more important in the stringer and massive ores. Carbon and oxygen isotope data further indicate fluid–rock interaction involving seawater‐derived basinal fluids, organic‐rich sediments, and isotopically lighter hydrothermal components. Collectively, the geological, textural, geochemical, fluid inclusion and isotopic evidence indicates that the Chah‐Nar deposit formed by discharge of metal‐bearing basinal fluids into a reduced, organic‐rich sedimentary environment, with fluid flow focused by synsedimentary faulting. The integrated dataset is most consistent with interpretation of Chah‐Nar as a SEDEX‐type Pb–Zn system developed in an Early Palaeozoic back‐arc rift setting. These results refine the metallogenic model for the southern Sanandaj–Sirjan Zone and highlight the roles of basin architecture, focused fluid flow and redox‐controlled sulfur reduction in Palaeozoic Pb–Zn mineralization in Iran.
ABSTRACT The coastline of the Shandong Peninsula is 3121 km long, encompassing various coastal types such as silty‐muddy, sandy, and bedrock coasts. Based on long‐term remote sensing monitoring data from 1984 to 2018 and detailed field monitoring data of typical coastal sections from 2015 to 2024, this paper systematically analyses the dynamic change characteristics of the Shandong Peninsula coastline. The results show that the total length of the continental coastline of Shandong Province increased by 829.35 km from 1984 to 2018, the proportion of artificial coastline rose to 72.03%, and the sandy coastline decreased by 47.17%. The coastal section of the Shell Bank Island in Binzhou is dominated by natural factors, showing characteristics of “natural control, long‐term continuity, and intensified erosion and down cutting”. The average erosion rate from 2016 to 2024 was 4.5 m/a. The Jiulong Bay coastal section in Weihai is dominated by human activities, showing characteristics of “human dominance, phased fluctuation, and rapid stabilisation after restoration”, with a significantly weakened erosion trend after restoration. Naturally, the sharp decline in sediment discharge from the Yellow River, sea level rise, and frequent extreme weather constitute the fundamental driving forces. Anthropologically, the expansion of artificial coastlines, beach sand mining, and unreasonable engineering construction have significantly accelerated erosion. It is recommended to implement classified prevention and control for different coastal types and promote the shift from passive protection to proactive adaptation and systematic management.
The rapid urbanization across the Kumaun Himalaya has made it gradually necessary to evaluate land stability, as unstable land can significantly increase the risks of disasters. The present study conducts a comparative analysis of the three rapidly growing towns of Kumaun Himalaya, namely Almora, Haldwani, and Nainital, using a comparative geospatial framework that applies the Analytical Hierarchy Process (AHP) and Shannon Entropy (SE) approach. Thirteen conditioning factors influencing land stability were considered to delineate stability zones. The final stability maps divide the area into five stability classes. The stability assessment of Haldwani town using the AHP technique reveals that nearly 42% of its area lies in the very low to moderate stability zone. Likewise, for Almora town, it shows about 60% of the area that comes under very low to moderate stable zones. Similarly, for Nainital town, it shows about 62% of its area lies in very low to moderate stable zones. On the contrary, the stability analysis results of the SE technique reveal that Almora falls under 50% of the total area in very low to moderate stability zones. Haldwani town highlights similar to 47% of the area lies in very low to moderate stability zones. Nainital town demonstrates about 53% of the area in very low to moderate stability classes. The AHP and SE models were validated using Receiver Operating Characteristic (ROC) curve, which yielded Area Under Curve (AUC) values of 0.879 for Haldwani, 0.763 for Nainital, and 0.794 for Almora for the SE model, and 0.948 for Haldwani, 0.742 for Almora, and 0.769 for Nainital for the AHP model. The comparison of AHP and SE results enhances reliability, offering valuable guidance for sustainable urban development and hazard mitigation in the Himalayan region.
The transition of body structure from soft body to hard body is the milestone event in the evolution of early eukaryotes. In this paper, we report some of the earliest Vase-shaped microfossils (VSMs) from the calcareous shale intervals in the similar to 1.56 Ga Gaoyuzhuang Formation of North China. These VSMs are interpreted as possible testate amoebae in affinity and may represent the earliest fossil record of unicellular heterotrophic protozoa with the ability of test building so far. Palaeoecologically, the finding of the Gaoyuzhuang VSMs likely indicates that the three-level energy pyramid composed of producer-decomposer-primary consumer in the food chain may have already been established in the early Mesoproterozoic oceans.
Today, the term 'productive horizon' is widely used in the practice of geological exploration. There are two fundamentally different approaches to the interpretation of this term. According to the first, it means a certain part of a geological section, which is identified using geological research methods to determine the place in the geohistorical chronicle of the investigated region and the position on stratigraphic diagrams, and accordingly, can be considered as a certain stratigraphic unit ('tratigraphic term'). According to another interpretation, the productive horizon characterizes the strata of rocks productive for hydrocarbons from the position of oil and gas geology, i.e. a reservoir, a cap, a fluid. This term refers only to an oil and gas-saturated reservoir in a field, its meaning as one of the components of a hydrocarbon system and no stratigraphic content – 'reservoir term'. The practice of conducting geological exploration works both in Ukraine and abroad (mainly in the countries of the former USSR) shows that the term 'productive horizon' in its content is a stratigraphic unit, that is, a stratigraphic subdivision. Since, in the current edition of the Stratigraphic Code of Ukraine, there is no information on the stratigraphic division of hydrocarbon-productive deposits of oil and gas-bearing regions of Ukraine. This publication aims to draw the attention of the geological community to the objective reality of the long-term existence of oil and gas stratigraphy and the integration of its terminological base into the Stratigraphic Code of Ukraine by developing appropriate subdivisions that would reflect the features of division, correlation and indexation of hydrocarbon-bearing strata.
