Distribution Of Rocks Research Articles

Late Cryogenian Circum-Rodinia Syn-Subduction Extension: Insights from Highly Fractionated S-Type and A-Type Granitoids in the Northern Tarim Craton

Late Cryogenian–Ediacaran magmatism represents the latest Precambrian tectonothermal event in the Tarim Craton. However, its geodynamic setting and geological significance are controversial. Here, we report the geochronology, whole-rock geochemistry, and Sr-Nd-Hf isotopic compositions of newly identified late Cryogenian A-type and highly fractionated S-type granites from two locations in the northern Tarim Craton. LA-ICP-MS zircon U-Pb analyses yield ages of 642 ± 7 Ma for a syenogranite and 643 ± 4.5 Ma for a mylonitized granite. The syenogranite is weakly peraluminous and shows an A-type granite affinity, as indicated by its high K2O + Na2O contents (8.35–8.64 wt.%), high field strength elements (Zr + Nb + Ce + Y = 435.8 − 463.4 × 10−6), Ga/Al ratios (2.79−2.83), and zircon saturation temperatures (829–844 °C). In contrast, the mylonitized granite contains Al-oversaturated minerals (e.g., garnet) and has high a differentiation index (DI = of 98.9–99.4), with lower zircon saturation temperatures (786–792 °C); the samples display high SiO2 contents (72.99–74.00 wt.%) and A/CNK values (1.16–1.17) and low Nb/Ta and Zr/Hf ratios and are enriched in Rb and depleted in Ba, Sr, which all point to a highly fractionated S-type granite affinity. The granites are characterized by elevated large-ion lithosphere elements (LILEs) and flat high-field-strength elements (HFSEs) patterns, with deep Nb and Ta troughs and pronounced negative Eu anomalies (Eu/Eu* = 0.17–0.38). They show apparently negative εNd(t) values (−10.1 to −9.8 and −6.8 to −7.9, respectively) and εHf(t) values (−9.66 to −1.77 and −33.5 to −1.3, respectively) with Paleoproterozoic crustal model ages, indicating that they were mainly generated by the partial melting of mature crustal materials with a minor contribution from a mantle-derived magmatic source. By integrating with previously published geological, sedimentological, and structural data, we suggest that the granites formed due to a high-temperature gradient in a syn-subduction extensional setting that was probably induced by northward slab rollback of the Paleo-Asian Oceanic lithosphere. Our new data highlight an upper-plate extension in the northern Tarim Craton that constitutes the northern periphery of the Rodinia supercontinent. The linear distribution of late Cryogenian magmatic rocks provides critical evidence for the orogen strike extension of the terminal suture between the Tarim Craton and southwestern Altaids.

Постановка многокритериальной задачи анализа и прогнозирования гранулометрического состава взорванных горных пород

Changes in the mining and geological characteristics of solid mineral deposits, a sharp decrease in the ore grades in many ore fields as well as the intensification of surface mining methods define the need to develop scientific, theoretical and methodological foundations for improving the efficiency of the interaction between the technological elements within the Mine-to-Mill' (M2M) concept, which can be adapted to each specific mining operation and will help to streamline the operating costs. Drilling and blasting is the main technological operation to break the rock off the rock mass and crush it when mining solid minerals. The main purpose of drilling and blasting operations is to create rock material that has the necessary properties for smooth and efficient handling by mining equipment at the subsequent stages of the field development with due account of the technical and economic costs. Formation of the muck pile affects the subsequent technological processes of the mining operation, and consequently, the cost of the end product of the mining company. The purpose of the study was to develop a mathematical model for forecasting and analyzing the particle size distribution of rocks in the muck pile within the 'Mine-to-Mill' system. Methods used. The study is based on a comprehensive approach, which includes scientific analysis and generalization of previously published research results. From the methodological point of view, the study was based on the system analysis methods, as well as on the use of information technologies.

Spatial distribution of the critical mineral resource element titanium in China and its influencing factors

In China, titanium is found in multi-metal symbiotic ore deposits that present sorting difficulties, low recovery rates, high production costs, and low overall resource utilization rates. The concentration and distribution of titanium in the pedosphere must be better understood to assess the potential titanium resources. The China Geochemical Baseline project obtained harmonized soil and rock geochemical data covering mainland China and provided reliable data for 76 elements (including titanium) from 3382 top (0–25 cm) and 3380 deep (>100 cm) sediment or alluvial soil samples and 12,201 rock samples. In this study, titanium concentrations were determined by X-ray fluorescence spectrometry under strict quality control. The median titanium concentration values in the top and deep samples, which were considered geochemical baseline values, were 3498 mg/kg and 3406 mg/kg, respectively, with mean values of 3661 mg/kg and 3585 mg/kg, respectively. The titanium concentrations ranged from 266 to 24,674 mg/kg and 324 to 25,504 mg/kg in the top and deep soil samples, respectively. The 75 % range (Q25–Q95) of titanium concentrations in the rock ranged from 978 to 8299 mg/kg. The median titanium concentration was 2555 mg/kg in the rock samples, while the mean concentration was 3089 mg/kg. The geochemical map of titanium indicated that low titanium concentrations below Q25 (<3498 and 3406 mg/kg in the top and deep samples, respectively) are primarily distributed in southern Xinjiang, Tibet, Qinghai, Gansu, and Inner Mongolia. The distribution of low titanium content in the soils is likely attributed to these regions being covered by deserts (e.g., Gobi) and glaciers. Soils with high titanium concentrations are widely distributed in the Emeishan large igneous province at the southwest margin of the Yangzi block, which is related to the large distribution of intermediate-basic rock in the area, as well as along the northeast-southwest direction of the Yangtze block, which extends for nearly 1600 km. Moreover, these soils are mainly associated with the black rock system and intermediate-basic dikes. Soil titanium concentrations are affected by various factors, including the occurrence of tectonic activity and distribution of the black rock system, intermediate-basic rock (especially basalt), and VTi magnetite deposits. In particular, the large igneous province area generated by a mantle column represents the main location of VTi magnetite deposit formation and the area with the highest titanium content. In addition to providing detailed information about the titanium distribution in the pedosphere and rock of mainland China, the project can also provide basic geochemical data for the development and utilization of titanium resources and the formulation of critical mineral industry policies.

Geochemical properties, mechanism of formation, and source of solid bitumen in the Ediacaran Dengying Formation from the central to northern Sichuan Basin, China

Several large gas reservoirs, including the Weiyuan and Anyue gas fields, have been discovered in the Ediacaran Dengying Formation in the Sichuan Basin, indicating vast opportunities for deep-petroleum exploration. Understanding the origin and evolution process of these gas reservoirs is crucial for further petroleum exploration and development. Although the burial history of the Sichuan Basin and its surrounding areas is basically dominated by Paleozoic burial and preservation, and Meso-Cenozoic uplift and erosion. However, the source of the Dengying Formation natural gas in the Sichuan Basin is still a subject of controversy between the Ediacaran and Cambrian source rocks due to high thermal maturity, secondary alteration, and multistage tectonic activities. This study aims to examine the investigation on the properties and genetics of Dengying solid bitumens that existed in the central to northern Sichuan Basin, in order to provide insights into the source and evolution history of the Dengying paleo-oil reservoirs. For this purpose, petrologic, elemental, and organic geochemical analyses were used to investigate the properties, origin, and formation mechanism of solid bitumens. The results indicate that these solid bitumens have suffered intense thermal alteration (EqVRo 2.1%–5.3%), and are classified as pyrobitumens. Solid bitumens in the Gaoshiti bulge and the north slope area were subjected to tectonic thermal events (e.g., Emeishan igneous province) and relatively strong thermochemical sulfate reduction (TSR) alteration. These solid bitumens were assumed to be pyrolysis products of light (condensate) oil. In contrast, solid bitumens in the Weiyuan bulge and the Micangshan uplift area were not influenced by tectonic thermal events but experienced weak TSR alteration, and originated from either normal or heavy crude oil. Moreover, a systematic bitumen-source correlation was carried out using δ13Corg values, bound steranes, and trace element distributions. Results reveal that the solid bitumens in the central Sichuan paleo-uplift were mainly derived from the lower Cambrian Maidiping Formation, those in the north slope area originated from the lower Cambrian Qiongzhusi Formation, while those in the Micangshan area were sourced from the Ediacaran Doushantuo Formation. Structural and burial history analysis implies that the differences in the source of the Dengying paleo-oil reservoir (i.e., solid bitumen) between these study areas are attributed to the distribution of source rocks and their contact relationship with reservoirs. This research successfully obtained insights into the source and genetic mechanism of paleo-oil reservoirs by analyzing the properties of high-maturity solid bitumens, which can guide further exploration and development of deep petroleum resources.

Soil patch heterogeneity improves plant productivity and nutrients regulated by arbuscular mycorrhizal fungi

AbstractThe interlacing and mosaic distribution of karst soil and rock result in the high spatial heterogeneity of the natural karst habitat. Karst plants are suffered from spatially heterogeneous microhabitats with different‐sized patches. Arbuscular mycorrhizal (AM) fungi are crucial in regulating plant productivity and nutrients in heterogeneous karst environments. However, how spatial patch heterogeneity influences plant productivity and nutrient utilization by AM fungi regulation in karst soil remains unclear. A simulated heterogeneity experiment regarding soil grid patches was conducted by planting Bidens pilosa into a microcosm of a square device. Experimental treatments included the mycorrhizal fungus treatments inoculation with (M+) or non‐inoculation with (M−) Glomus etunicatum fungus, and the spatial heterogeneity treatments involved homogeneous patches (HO), heterogeneity‐small patches (HS), and heterogeneity‐large patches (HL). The growth and nutritional traits of plants were analyzed. The results showed that AM fungus promoted the productivity and nutrient uptake of B. pilosa by substantial increases in biomass, nitrogen (N) accumulation, phosphorus (P) accumulation, and N/P ratio. The spatial heterogeneity promoted the biomass and N and P accumulations of B. pilosa when inoculating with AM fungus. The mycorrhizal colonization rate and hyphae length were greater in HS than in HO and HL under the M+ treatment, with a greater response ratio of biomass, N and P under HS conditions. These indicated that the heterogeneous small patches had a greater promotion of the biomass production and nutrients of B. pilosa with inoculation of AM fungus because extensive fungal hyphae can acquire soil resources in more distant patches outside the root zone with more economical metabolic costs compared to roots. We thus conclude that patch heterogeneity contributes to plant productivity and nutrient utilization regulated by AM fungi in karst soil, and the broader nutrient capture induced by extraradical hyphae of AM fungi may be an adaptive mechanism for karst plants to cope with heterogeneous environmental conditions.

Quaternary Urban Geology and the Foundation of Heritage Building: Notable Historical Cases in Sawahlunto, Indonesia

Sawahlunto is a city located in West Sumatra, Indonesia, known as a city rich in coal mining activities and often referred to as the “City of Batubara.” The history of Sawahlunto coal mining dates back to the Dutch colonial era in the late 19th century when coal was discovered in the area. It has been designated as a national geopark area (KGN) in 2018 and then designated as a UNESCO World Heritage Site (WDU) in 2019. One of its prominent landmarks is the Ombilin Coal Mine, which. Sawahlunto also boasts other historical landmarks and preserved buildings. The study objectives are: to identify rock types, topographic features, and other phenomena, along with measurements of heritage buildings; to analyze the rock distribution for determining the origin of rocks for heritage buildings in urban development and to describe the heritage building; and to describe the development of heritage building in Sawahlunto The mixed method was incorporated, where geological mapping method was used to determine information on the distribution of rocks and material origin for urban development, heritage building foundation analysis and content analysis on heritage buildings. The study found the building materials are rocks from the result of erosion originating around the city of Sawahlunto are: Sedimentary rock facies in the Ombilin Basin. The heritage buildings used local materials as they were abundant during that time. Sawahlunto’s heritage buildings not only have historical and cultural heritage, but also contain urban geological heritage that should be further studied as part of urban development.

A preliminary study on the formation of acid mine drainage through rock geochemical test in the coal mining areas

Acid mine drainage (AMD) is the biggest issue occurring in every mining industry. Therefore, it is necessary to check the rock, particularly its potency to form acid mine drainage. PT X in Lahat, South Sumatra does not yet own a distribution model for the PAF and NAF rocks. Thus, this research was conducted to determine the distribution of PAF and NAF rocks as an initial potency for the formation of acid mine drainage. Six samples in the field were taken from the pit walls, in which these sample codes were A, B, C, D, E, and F, respectively. These samples were subjected to the static and kinetic tests in the laboratory. The static test showed that a sample with a potency to form acid was sample E, while the other five samples did not have any potency to form acid. Afterwards, kinetic tests were conducted with a daily cycle for 25 days. The result showed that the sample F had lower pH value, compared with the other five samples. Thus, based on this study, it can be concluded that the only sample having the potency to form acid was sample F, while the other samples, namely A, B, C, D, and E, respectively, did not have any potency to form acids.

Mechanical analysis of toppling failure using FDEM: A case study for soft-hard interbedded anti-dip rock slope

In recent years, massive interbedded sandstone and slate anti-dip slopes have been discovered in the southwest and northwest regions of China. The distinct mechanical properties of different rock layers make these slopes particularly unique. In this paper, the finite-discrete element method (FDEM) is used to study the toppling failure mechanism of soft-hard interbedded anti-dip rock slopes (SHIADRSs). Firstly, the numerical model of soft-hard interbedded anti-dip rock slope (SHIADRS) is established based on a centrifugal loading test. Then, the stress state, evolution of displacement and cracks, and progress of toppling failure in the SHIADRS are analyzed. Besides, the effect of rock structure, slope angle, dip angle, and rock mechanical properties on the toppling failure of SHIADRS is discussed. The simulation results show that the toppling failure process of SHIADRS can be divided into three stages. The stress distribution in hard rock (HR) is obviously different from that in soft rock (SR) layers. HR layers bear greater bending moments than HR layer during the toppling failure of the soft-hard interbedded anti-dip rock slopes. In addition, the stability of SHIADRS is negatively correlated with the slope angle and the dip angle of rock layer. Compared to the inclination angle of rock layers, the slope angle has a more significant impact on the stability of slopes. The internal friction angle of the rock layer has almost no effect on the toppling failure of SHIADRS.

Effect of Geochemical Reactivity on ScCO2–Brine–Rock Capillary Displacement: Implications for Carbon Geostorage

The displacement efficiency of supercritical CO2 (scCO2) injection in the storage zone and its primary trapping mechanism in the confining zone are strongly tied to the capillary phenomenon. Previous studies have indicated that the capillary phenomenon can be affected by geochemical reactivity induced by scCO2 dissolution in formation brine. To quantify such changes, thin disk samples representing a sandstone storage reservoir, siltstone confining zone, and mudstone confining zone were treated under a scCO2-enriched brine static condition for 21 days at 65 °C and 20.7 MPa. Geochemical alterations were assessed at the surface level using scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy and X-ray fluorescence. Before and after treatment, the wettability of the scCO2–brine–rock systems was determined using the captive-bubble method at fluid-equilibrated conditions. Pore size distributions of the bulk rocks were obtained with mercury injection capillary pressure, nuclear magnetic resonance, and isothermal nitrogen adsorption. The results indicate the dissolution of calcite at the surface, while other potentially reactive minerals (e.g., clays, feldspars, and dolomite) remain preserved. Despite alteration of the surface mineralogy, the measured contact angles in the scCO2–brine–rocks systems do not change significantly. Contact angle values of 42 ± 2° for sandstone and 36 ± 2° for clay-rich siltstone/calcite-rich mudstone were determined before and after treatment. The rocks studied here maintained their water-wettability at elevated conditions and after geochemical reactivity. It is also observed that surface alteration by geochemical effects did not impact the pore size distributions or porosities of the thin disk samples after treatment. These results provide insights into understanding the impact of short-term geochemical reactions on the scCO2–brine capillary displacement in the storage zone and the risks associated with scCO2 breakthrough in confining zones.

Early Precambrian basement components of the Cathaysia Block in South China exhumed by Phanerozoic orogenic events

Ancient rock assemblages formed during the early history of the Earth are normally regarded as continental nuclei and they occur in old cratons. In recent years, they have been reported from different orogenic belts, but the reasons why they occur in orogenic belts are yet to be constained. The Cathaysia Block in South China is a continental block that witnessed multiple episodes of orogenic events and ancient basement rocks sporadically occur in the Wuyi area, where intense metamorphic alteration can be seen. This area is therefore ideal for addressing the above issue. New data, in combination with a review of previous studies, show that the ancient basement components of the Cathaysia Block formed during > 1.93 – 1.75 Ga and are mostly reworked ancient crustal materials (∼3.8 – 2.5 Ga). The first episode of metamorphism recorded in this area can be traced back to the Paleoproterozoic, but the features of this metamorphism are unclear. The early Paleozoic metamorphic rocks occur across the Wuyi area, and their protolith ages are dominantly Neoproterozoic, with a small amount of Paleoproterozoic rocks. This episode of metamorphism is characterized by high geothermal gradients, possibly corresponding to an arc setting. The early Mesozoic high-grade metamorphism of the Wuyi area is characterized by low geothermal gradients, indicating significant crustal thickening during the orogenic event. The spatial distribution of the early Mesozoic high-grade metamorphic rocks and the early Precambrian basement rocks of the Cathaysia Block are almost the same. Considering that the ancient basement rocks of the Cathaysia Block have been found in the Wuyi area, it is inferred that both the early Paleozoic and the early Mesozoic orogenic events should have facilitated the exhumation of the early Precambrian basement components. It is further suggested that the final exhumation of these ancient basement rocks is dominated by the early Mesozoic orogenic event because compared with other orogenic events of this continental block, this orogeny influenced rocks from deeper crustal levels (with the highest metamorphic pressures). Such a mechanism of ancient basement rocks exhumed by overprinted orogenic events might apply to many other high-grade terranes.

Petrogenesis of Andesite Rocks in Datae Area, Sidenreng Rappang Regency, South Sulawesi Province

The research area is in the Datae Area, Watangpulu District, Sidenreng Rappang Regency, South Sulawesi Province. This study aims to determine the distribution of volcanic rocks, determine the crystallization phase based on petrographic analysis, and determine the type, magma affinity and tectonic environment based on geochemical data. The method used in this study was field data collection and rock sampling for analysis through petrographic analysis and geochemical analysis using the X-Ray Fluorescence (XRF) method by analysing the main elements, trace elements and rare earth elements (REE). The results of the petrographic analysis show that the rocks found in the field are volcanic breccia and ignimbrite. Volcanic breccia showed coarse-grained texture composed of angular to rounded andesite fragments and pyroclastic material fused together in a matrix. Meanwhile, ignimbrite showed fine grained texture with lapilli to boulder-sized fragments, poor sorting, open-packed and non-layered structure. Based on the Total Alkali Silika (TAS) diagram, AFM diagram, and binary diagram, the results of the geochemical analysis showed that the rocks found in the study area were andesite and trachy-andesite, while the magma affinity area is high-K calc-alkaline and shoshonitic. High-K calc-alkaline magmas are associated with subduction zones and are characterized by elevated levels of potassium and aluminum, while shoshonitic magmas are typically found in intraplate or back-arc settings, characterized by their distinctive potassium, sodium, and barium-rich compositions. The results from ternary diagram and geochemical Spider plots proved that the magma tectonic environment is island arc—continental arc basalt, indicating that the rock was formed in a subduction area. This research supports previous research regarding the tectonics of the western arm of Sulawesi, which stated that this area was formed by subduction.

Orogenic cyclicity and episodic tectono-magmatic processes in the formation of the Paleozoic northern Yili magmatic arc, Central Asian Orogenic Belt

To understand the orogenic cyclicity that built the northern Yili magmatic arc in the southern Balhkash-Yili arc of the Central Asian Orogenic Belt, we synthesize its tectono-magmatic processes using new and existing U-Pb geochronological dates (228), Hf-in-zircon (1605 spots), bulk-rock geochemical data (1458), and Sr-Nd isotopic analyses (461) of magmatic rocks. Based on temporal-spatial distribution of magmatic rocks and their geochemical composition, four magmatic episodes (ca. 470−440 Ma, 420−380 Ma, 350−320 Ma, and 300−260 Ma) punctuated by a magmatic gap (ca. 440−420 Ma) and two high-flux magmatic pulses (ca. 380−350 Ma and 320−300 Ma) were recognized. These episodic magmatic processes are proposed to be dynamically associated with changes in configuration of the subducted Junggar oceanic slab, including 470−440 Ma initial subduction, 440−420 Ma flat subduction, 420−380 Ma retreating subduction, 380−350 Ma advancing subduction, and 350−320 Ma retreating subduction, followed by slab break-off in ca. 320−300 Ma and subsequent lithospheric delamination in a post-collisional setting during the Permian (ca. 300−260 Ma). In addition, tectonic transition (ca. 380 Ma and 320 Ma) from extension to compression were suggested to be closely related to the two phases of porphyry Cu mineralization events in the Balkhash-Yili arc. High crustal thickness and more mature arc evolution with prominent crust-mantle interaction may be responsible for the significant porphyry Cu endowment in the northern Balkhash-Yili arc.

Spatial Distribution and Petrophysical Characterization of Reservoir Rocks in the AB Unit

Spatial Distribution and Petrophysical Characterization of Reservoir Rocks in the AB Unit

Structural Traits of Cuitzeo Lake, Central Mexico, and Areas of Geothermal Potential

Cuitzeo Lake, in the central part of the Trans Mexican Volcanic Belt, is in an extensional region associated with the Cuitzeo graben, where magmatic ascent appears to provide the heat sources for the surface, geothermal manifestations. A profuse distribution of andesitic rocks is observed throughout the study area of 50×50 km2. Gravity and magnetic field 3D inversions are calculated to obtain density and magnetic susceptibility distributions to 7000 m depth, from which we analyze N-S and E-W cross-sections and obtain density and magnetic susceptibility geosurfaces that help characterize anomaly areas of interest. We use satellite-derived gravity and magnetic data in our evaluation, owing to their high-resolution characteristics and uniform coverage of the study area. Analysis initiates with the San Agustín del Maíz region (SAM), exhibiting surface geothermal manifestations, to characterize its density and susceptibility characteristics, then the analysis is extended to the whole study area. Several outcropping, low magnetic susceptibility regions, like the one associated with SAM, are suggested as potential geothermal targets. Density geosurfaces point to two volumes where magmatic material may intrude, coinciding with active geologic faults. The analysis presented here can be extended to neighboring regions in the Cuitzeo Lake area and may constitute a fast, unexpensive exploration methodology in similar geothermal districts.

Carbonate Resources in Viet Nam: Exploiting, Processing and Using

Vietnam has a carbonate rock distribution area of about 60,000 km2, accounting for nearly 20% of the territory's area. Carbonate rocks in Vietnam are located in many different stratigraphy, their ages from Pre Cambrian to Triassic. Carbonate rocks in Vietnam include limestone, marble, and dolomite. Carbonate rock has been made up for hundreds of millions of years. However, the use of carbonate rock resources in Vietnam is inconsequential, reducing its value. The author of the article introduces an overview of carbonate rock resources in Vietnam, and the reality of exploiting and processing carbonate resources in Vietnam. Since then, gave warnings about illogical in the use of carbonate rock resources. At the same time, it also makes recommendations for the rational use of carbonate rock resources for sustainable development.

Study on the Controlling Factors and Laws of Deep Carbonate Geothermal Reservoirs in the Jizhong Depression

The absence of regional electrical data has constrained our comprehension of the deep geological structures in the Jizhong Depression. This limitation has impeded the exploration of factors and principles governing geothermal reservoirs. Historically, studies on these factors primarily centered on geothermal field attributes, such as anomalous geothermal flux, geothermal gradients, and deep Moho variations. In our research, we undertook an exhaustive interpretation of extended-period magnetotelluric readings. This was amalgamated with prior regional geological and geophysical studies to discern deep geological structural details pertinent to geothermal resource components, encompassing heat sources, pathways, reservoirs, and cap rocks. Our analysis spanned the foundational surface of the Cenozoic era, fault configurations, carbonate formation distribution, and layers with low velocity yet high conductivity. We also statistically evaluated geothermal wells, their density, and the water temperature attributes across various structural entities. This aided in comprehending how structural units influence thermal well features. Our research delineated the spatial interrelation between geothermal well distribution and deep geological structures, including carbonate rock distribution, Cenozoic thickness, fault patterns, and profound low-velocity, high-conductivity layers. Moreover, we scrutinized how structural unit types impact thermal well attributes, offering insights into the formation principles of deep carbonate geothermal reservoirs within the Jizhong Depression. Our findings suggest that the genesis of deep geothermal resources in the Jizhong Depression is swayed by regional geological conditions. Notably, the distribution of regional and especially deep geothermal wells is intimately tied to regional stratigraphy, structural designs, and profound geological structural traits. Furthermore, the temperature within geothermal wells correlates strongly with the burial depth, carbonate formation thickness, Cenozoic thickness, and proximity to fault channels responsible for fluid movement and heat transmission.

NON-KARSTIC SPELEOGENESIS IN SANDSTONE ROCKS OF UKRAINIAN CARPATHIANS

Due to the limited distribution of karst rocks and, accordingly, the small number of karst caves in the Ukrainian Carpathians, the caves of non-karst (pseudokarst, clastokarst) genesis attract considerable attention from cave researchers. The latter most often develop in massive and coarse-grained sandstone strata, usually found as part of flysch strata. The caves of non-karstic genesis are widely spread in the Cretaceous and Paleogene sandstone formations of the Ukrainian Carpathians. Most of them are developed in the massive sandstone of the Yamna Formation of the Palaeocene. The primary information about all caves on the territory of Ukraine is collected by the Commission for Accounting and Documentation of Caves of the Ukrainian Speleological Association (UkrSA), and by local caving clubs and individual researchers. Currently, the number of discovered caves in the sandstone of the Ukrainian Carpathians exceeds the number of mapped caves, not to mention their detailed description. The minimal information about each cavity includes the name, entrance coordinates, total length, and depth (amplitude) resulting from the cave survey. The additional description could contain knowledge about the history of the cave discovery, origin, geological settings, microclimate, sediments, inhabitants, paleontological and archaeological remains, etc. At present, many caves have been discovered in a few microregions: Kliuch Ridge, near Skole; the tract Drybka, between Yaremche and Yamna; on Sokilsky Ridge, and its south-eastern orographic continuation at tracts Protiate Kaminnia and Lekeche; Polonyna Runna; Lubnia Village; and Chorna Gora Ridge. Few yet not mapped cavities are known in Bubnyshche, Synytsia Mt., and some other sites. Most caves belong to three genetic types: tectonic, gravitational, and selective corrosion. The largest among tectonic caves is Tectonic (Dovbush) cave near Yamna Village, which is 388 m long. The longest selective-corrosion cave is 92 m long. Some caves with fissure-like morphology could also be of cryogenic origin. We suggest that the caves with the fissure-like morphology are the forms of paleoseismic dislocations. Keywords: sandstone; pseudokarst; speleogenesis; selective corrosion; Ukrainian Carpathians.

Study on the Stress Distribution and Stability Control of Surrounding Rock of Reserved Roadway with Hard Roof

According to field observation and theoretical analysis, the failure of the 1523103 reserved roadway is mainly affected by the lateral support pressure, rock mass strength, and support mode. With the mining of the 152309 working face, the lateral pressure of coal pillars on both sides of the reserved roadway increases, and since the lithology of the two sides and the floor of the roadway is weak, the reserved roadway experiences spalling and floor heave. Through numerical simulation, the distribution law of surrounding rock stress and the displacement of surrounding rock are obtained after the roof cutting and pressure relief of the reserved roadway with hard roof. According to the cause of surrounding rock failure of a reserved roadway, the combined control technology of roof cutting and pressure relief, grouting anchor cable support, and bolt support is put forward. After cutting the roof and releasing the pressure on the working face, the lateral support pressure of the two sides of the roadway is significantly reduced, the deformation of the two sides of the roadway is small, the maximum shrinkage rate of the section is reduced from 70% to 11%, and the deformation of the surrounding rock of the 1523103 reserved roadway is effectively controlled. The successful control of the surrounding rock in the 1523103 tunnel reduces the number of coal pillars to be installed, improves the coal extraction rate, and is conducive to the sustainable utilization of limited natural resources and the sustainable development of the coal industry.

Sedimentary Characteristics and Hydrocarbon-Generation Potential of the Permian Pingdiquan Formation in Dongdaohaizi Sag, Junggar Basin, Northwest China.

After several years of extensive exploration, a series of oil and gas reservoirs or structures have been discovered in the Dongdaohaizi sag, situated in the hinterland of the Junggar Basin. However, in recent years, some wells around the sag have failed. Herein, sedimentary facies, the plane distribution of dark mudstone, geochemical characteristics of source rocks, and the control of sedimentary facies on the distribution and development of source rocks in the Permian Pingdiquan Formation in the Dongdaohaizi sag were systematically investigated. A combined geological and geochemical method was used to fully understand the distribution law and resource potential of the source rocks in this area. Investigation results indicate that the Pingdiquan Formation primarily inherited continuous deposition, and the sedimentary facies of the sag, such as semideep lake, shore-shallow lake, prefan delta, fan delta front, and fan delta plain, were developed from the center sag to the outside. The fan delta facies, predominantly distributed in the northern margin of the sag, are characterized by lithology mainly composed of sandy conglomerate and coarse sandstone. The sandstone has a coarse particle size and poor sorting ability, while lacustrine mudstone is widely developed in the sag with a large sedimentary thickness, which is the primary source rock of the Dongdaohaizi sag. The source rocks in the Pingdiquan Formation exhibit medium-to-good quality. The organic matter is categorized as types II1-III, and the thermal evolution maturity is in the mature-high mature stage, indicating a high resource potential. The development of the source rock in the Dongdaohaizi sag is closely related to the sedimentary environment. The sedimentation rate of fan delta facies is high and burial is fast, bringing a large amount of terrestrial organic matter to the lake, thereby increasing the nutrition and organic matter quantity of the lake. Due to the stable water of the lake, low energy at the bottom, and medium conditions of strong reduction, a large amount of organic matter accumulated in the deep to semideep lake facies of the study area, resulting in the development of thick dark mudstone with a thickness of over 400 m. The abundance of organic matter has reached a good level, and the maturity and content of organic matter are high, signifying a high hydrocarbon-generation potential.

Metallogenic Prediction of the Zaozigou Gold Deposit Using 3D Geological and Geochemical Modeling

Deep-seated mineralization prediction is an important scientific problem in the area of mineral resources exploration. The 3D metallogenic information extraction of geology and geochemistry can be of great help. This study uses 3D modeling technology to intuitively depict the spatial distribution of orebodies, fractures, and intrusive rocks. In particular, the geochemical models of 12 elements are established for geochemical metallogenic information extraction. Subsequently, the front halo element association of As-Sb-Hg, the near-ore halo element association of Au-Ag-Cu-Pb-Zn, and the tail halo element association of W-Mo-Bi are identified. Upon this foundation, the 3D convolutional neural network model is built and used for deep-seated mineralization prediction, which expresses a high performance (AUC = 0.99). Associated with the metallogenic regularity, two mineral exploration targets are delineated, which might be able to serve as beneficial achievements for deep exploration in the Zaozigou gold deposit.