Limestone Layers Research Articles

Introduction to The Earth Field In Bukit Batu Putih, Samarinda City, East Kalimantan

This Introduction to Earth Science Field Lecture activity was conducted at Bukit Batu Putih, Samarinda City, which is the Balang Island Formation (Tmpb). This location was chosen because of the dominance of limestone in the area and the significant limestone mining activities. This study aims to understand the local geological characteristics, identify limestone types, and analyze the impact of mining on the surrounding environment. The methodology used in this study includes field observation, geological mapping, and visual analysis and limestone sample assessment. Field observations were conducted to identify the structure and texture of limestone and geological formations around the location. Geological mapping was conducted to map the distribution of limestone and understand the stratigraphic relationship between rock layers. The results of the study indicate that limestone consists of clastic and fossiliferous limestone types, which are formed from calcium carbonate deposits. Mining activities in this area have revealed many limestone layers that have economic potential. However, mining also has environmental impacts, such as changes in land morphology and degradation of water quality. The conclusion of this study emphasizes the importance of understanding regional geology and limestone characteristics for better resource management. Recommendations are provided for improving environmentally friendly mining practices and conservation efforts to maintain the balance of the ecosystem in Bukit Batu Putih.

Geotechnical and geophysical investigations for infrastructure safety zones: a case study of the supporting ring road, Cairo, Egypt

This study aims to evaluate the suitability of subsurface layers for infrastructure development using geophysical and geotechnical studies. Six seismic refraction and six 2D geoelectic profiles were conducted in the study area to analyze the geotechnical characteristics of the subsoil in order to assess its suitability for construction projects. According to the geophysical investigation, there are two main geoelectric strata, each with a different lithology and thickness. The first layer has high resistivity values of more than 200 (Ωm) and its thickness is between 3.5 and 6.3 m. The second layer's resistivity ranges from 0.3 to 200 (Ωm). The findings indicate that the near-surface area of the study site is composed of two layers in addition to the surface layer, which consists of semi-consolidated wadi fill deposits of gravel, sand, and silt with rock fragments. The first layer comprises fractured limestone with clay intercalation, followed by a second layer of marly limestone, which transitions into marl and clay. Both compressional (P) and shear (S) waves were detected and analyzed. The shallow seismic refraction technique indicates that the velocity waves (Vp) in the first and second layers range from 133 to 770 and 790 to 3100 m/s respectively. Various engineering parameters for the second layer were determined, including elastic moduli (bulk modulus, Poisson’s ratio, rigidity modulus, and Young’s modulus), competence scales (stress ratio, concentration index, material index and density gradient), and bearing capacity (ultimate and allowable). The average Poisson ratio for the first and second layers is 0.235. The ultimate bearing capacity (Qu) of the first layer ranges from 379.1 to 1031.2 gm/cm2 and between 1040.8 and 1548.5 gm/cm2 of the second layer. Allowable bearing capacity (Qall) for the first layer is between 126.4 and 343.7 gm/cm2, and for the second layer, it is between 346.9 and 516.2 gm/cm2. According to the geotechnical investigation's findings, the range of liquid limit (LL) values is between 41.20 and 86.30%, the range of plastic limit (PL) values is between 18 and 35.25%, the range of plasticity index (PI) values is between 14.17 and 51.45%, and the range of free swelling values is between 60 and 170%. However, the study identified high-risk areas in the study area. These zones are located in the first and second layers represented by strongly swelling clay layers and strongly fractured limestone, which will have a major impact on the road and buildings. Therefore, this study recommends addressing these problems before any development to protect these areas from subsidence and collapse.

Neogene shale-detached extension and contraction linked system in the Akal Fold and Thrust Belt, Southeast Mexico

Structures related to shale mobility represent an important challenge for proper interpretation in seismic data sets. The large number of seismic sections obtained in recent times of the Akal Fold and Thrust Belt (AFTB) makes this province a natural laboratory for studying shale-related structural styles. The interpretation of two orthogonal 2D seismic sections reveals the geometry of a gravity-driven extension-contraction structural system that developed in the central portion of the AFTB during the Late Miocene to the Early Pliocene. The gravity-driven system was triggered by increasing the sedimentary load in the Miocene and developed a set of listric faults and related growth strata. The contracting structures are the in-sequence fold thrust that evolved from shale-cored detachment anticlines. An Oligocene sequence of soft, weak shale with alternating, rigid layers of sandstone and limestone and a low-resistivity signature acts as the detachment of the gravity-driven system. The progressive sequential restoration of a structural cross section provides more information about the progression of the gravity-driven system. We suggest that mobility started when the Oligocene shale reached a critical condition at >2–3 km burial depth. The coeval northeastward regional Chiapanecan shortening interferes with the last stage of the shale detachment (the Early Pliocene) in the study area and masks the previous interpretation of the gravity-driven system.

Stratigraphy and microfacies analysis of the Lower–Middle Jurassic platform carbonate succession in the Yeşilovacık (Mersin) area (Central Taurides, S Turkiye)

This study covers the detailed analyses of stratigraphy, microfacies and depositional environments of the Lower-Middle Jurassic carbonate succession in the southern part of Anatolide-Tauride Carbonate Platform in southern Türkiye (south of Central Taurides, around Yeşilovacık). The carbonate succession is composed of the Dibekli and Tokmar formations, and the Işıklıkızıtepe Member which forms the base of the Tokmar Formation. The Dibekli Formation (Upper Sinemurian-Lower Bajocian) is composed of limestones intercalated with intraformational conglomerates in the lower parts, with dolostones in the lower to middle parts and with oncoidal limestones in middle to upper parts. The Işıklıkızıtepe Member (Upper Bajocian) starts with basal conglomerates containing brown-red- iron nodules and consists of sandstone and sandy-clayey limestone alternations. These are overlain by thin limestone layers passing upward to thick-bedded dolostones of the Tokmar Formation (Upper Bajocian–Bathonian). The middle to upper parts of the formation are composed of sandy, oncoidal limestones rich in bivalve shells and end with dolostones-limestone alternations in the upper part. According to microfacies analyzes and litho-bio content; Late Sinemurian-Plesbachian is a period that low-to moderate-energy, restricted inner platform conditions dominated the depositional environments. The presence of comman intraformational conglomerates shows tectonic activity from time to time in this period. The Toarcian to the earliest Bajocian, low-energy intertidal and shallow lagoon conditions dominated the depositional environments, and in the Early Bajocian, the depositional environment changed to a high-energy sand shoal and above wave base environment. The basal conglomerate consisting of brown-red, iron-noduler and bauxite grains at the base of the earliest Late Bajocian indicates a short-term emersion and continued under low energy shallow lagoonal conditions during the Late Bajocian–Bathonian. Environmental changes during the Toarcian to Early Bajocian, and the earliest Late Bajocian short-term emersion, and the environmental changes during the Late Bajocian-Bathonian are interpreted to short-term sea level changes. Yeşilovacık Lower-Middle Jurassic carbonate sequences are correlated with those in peri-Mediterranean platforms. They show close similarities to the other Tauride carbonate sequences in terms of stratigraphy and facies. Paleontological and sedimentological analyses enable us to reconstruct a detailed dating and paleoenvironmental evolution for the Yeşilovacık carbonate deposits during the Lower-Middle Jurassic period.

Oceanic and Sedimentary Microbial Sulfur Cycling Controlled by Local Organic Matter Flux During the Ediacaran Shuram Excursion in the Three Gorges Area, South China.

The increased difference in the sulfur isotopic compositions of sedimentary sulfate (carbonate-associated sulfate: CAS) and sulfide (chromium-reducible sulfur: CRS) during the Ediacaran Shuram excursion is attributed to increased oceanic sulfate concentration in association with the oxidation of the global ocean and atmosphere. However, recent studies on the isotopic composition of pyrites have revealed that CRS in sediments has diverse origins of pyrites. These pyrites are formed either in the water column/shallow sediments, where the system is open with respect to sulfate, or in deep sediments, where the system is closed with respect to sulfate. The δ34S value of sulfate in the open system is equal to that of seawater; on the contrary, the δ34S value of sulfate in the closed system is higher than that of seawater. Therefore, obtaining the isotopic composition of pyrites formed in an open system, which most likely retain microbial sulfur isotope fractionation, is essential to reconstruct the paleo-oceanic sulfur cycle. In this study, we carried out multiple sulfur isotope analyses of CRS and mechanically separated pyrite grains (>100 μm) using a fluorination method, in addition to secondary ion mass spectrometry (SIMS) analyses of insitu δ34S values of pyrite grains in drill core samples of Member 3 of the Ediacaran Doushantuo Formation in the Three Gorges area, South China. The isotope fractionation of microbial sulfate reduction (MSR) in the limestone layers of the upper part of Member 3 was calculated to be 34ε = 55.7‰ and 33λ = 0.5129 from the δ34S and Δ33S' values of medium-sized pyrite grains ranging from 100 to 300 μm and the average δ34S and Δ33S' values of CAS. Model calculations revealed that the influence of sulfur disproportionation on the δ34S values of these medium-sized pyrite grains was insignificant. In contrast, within the dolostone layers of the middle part of Member 3, isotope fractionation was determined to be 34ε = 47.5‰. The 34ε value in the middle part of Member 3 was calculated from the average δ34S values of the rim of medium-sized pyrite grains and the average δ34S values of CAS. This observation revealed an increase in microbial sulfur isotope fractionation during the Shuram excursion at the drill core site. Furthermore, our investigation revealed correlations between δ34SCRS values and CRS concentrations and between CRS and TOC concentrations, implying that organic matter load to sediments controlled the δ34SCRS values rather than oceanic sulfate concentrations. However, these CRS and TOC concentrations are local parameters that can change only at the kilometer scale with local redox conditions and the intensity of primary production. Therefore, the decreasing δ34SCRS values likely resulted from local redox conditions and not from a global increase in the oceanic sulfate concentration.

Three-stage formation of cap carbonates after Marinoan snowball glaciation consistent with depositional timescales and geochemistry

At least two global “Snowball Earth” glaciations occurred during the Neoproterozoic Era (1000-538.8 million years ago). Post-glacial surface environments during this time are recorded in cap carbonates: layers of limestone or dolostone that directly overlie glacial deposits. Postulated environmental conditions that created the cap carbonates lack consensus largely because single hypotheses fail to explain the cap carbonates’ global mass, depositional timescales, and geochemistry of parent waters. Here, we present a global geologic carbon cycle model before, during, and after the second glaciation (i.e. the Marinoan) that explains cap carbonate characteristics. We find a three-stage process for cap carbonate formation: (1) low-temperature seafloor weathering during glaciation generates deep-sea alkalinity; (2) vigorous post-glacial continental weathering supplies alkalinity to a carbonate-saturated freshwater layer, rapidly precipitating cap carbonates; (3) mixing of post-glacial meltwater with deep-sea alkalinity prolongs cap carbonate deposition. We suggest how future geochemical data and modeling refinements could further assess our hypothesis.

Unveiling the Dynamics and Sustainability of the Nubian Aquifer System in El-Marashda, Egypt Through Geophysical, and Hydrogeochemical Investigations

AbstractThis research investigates the geophysical, hydrogeochemical, and geological characteristics of the Nubian Aquifer System in the El-Marashda area, located beneath the Eastern Sahara Desert in northeastern Africa. The primary objective is identifying the aquifer geometry, assessing groundwater quality, and evaluating environmental pollution levels. A Magnetotelluric survey was employed to examine the subsurface geological composition and electrical resistivity characteristics of the aquifer system. The study revealed a freshwater-saturated Nubian Sandstone layer at depths between 986 and 1009 m with resistivity values of 101 to 182 Ohm.m, indicating a substantial and potentially sustainable groundwater resource. Overlying limestone and Marly Limestone layers influence the aquifer’s permeability and storage capacity. The chemical analysis of water from three wells showed suitability for drinking and irrigation, with no sodium and magnesium levels hazards. The Heavy Metal Pollution Index (HPI) and Heavy Metal Evaluation Index (HEI) indicated low to medium contamination, posing potential environmental health risks. Human health risk assessments using USEPA methodology found acceptable non-carcinogenic risks, with Hazard Quotients (HQs) for heavy metals below 1 and a negligible Hazard Index (HI). The comprehensive investigation underscores the potential for sustainable groundwater utilization in El-Marashda. It highlights the aquifer’s suitability for irrigation, with low contamination levels and minimal health risks. These findings provide a foundation for informed and sustainable water resource management, environmental protection, and resilient infrastructure development in the region. The methodologies and results align with global standards, demonstrating their applicability in globally diverse geological contexts. This research contributes valuable baseline data for future studies and monitoring efforts, whether at local or global sites, emphasizing the importance of continued investigation to ensure sustainable groundwater management.

High Resolution Strontium Isotope Stratigraphy of L-III Reservoir of Mumbai High and adjoining Cluster 7 areas of Mumbai Offshore Basin, India

ABSTRACTHigh degree of reservoir heterogeneity has always been problematic in the identification and chronostratigraphic mapping of individual layers in a thick limestone sequence, especially when there is poor preservation of index fossils for thin sub-layers in the sequence. The multi-layered Miocene L-III reservoir of Bombay Formation in Mumbai High and adjoining southwestern area of the Mumbai offshore basin of India have suffered from similar issues due to lack of absolute ages and, therefore, the lack of highresolution chronostratigraphy for its individual thin limestone layers. The present study attempts to establish high-resolution chronostratigraphic age constraints of different sub-units, namely A, B, C, D, and E layers, of the L-III unit, using strontium isotope stratigraphy of carbonate (core and cutting) samples cut from 7 wells in Mumbai High and five wells in Cluster-7 area southwest to Mumbai High. The study provides a geochronological age range of ~2.1 Ma for the L-III unit, with the top of L-III in Mumbai High South assigned at 16.6 Ma based on Strontium isotopic analysis. The study has further helped in assigning absolute ages of individual layers of the L-III reservoir, with the A1 sub-unit at 16.6-16.8 Ma, A2 between 16.9-17.9 Ma, B sub-unit at 18.0 Ma and C & D sub-units between 18.2-18.3 Ma. Layer E of the L-III unit was dated to be 18.5-18.6 Ma, and the L-IV top has been assigned to be at 18.7 Ma. The study also correlated the ages obtained in the Mumbai High region with the studied wells southwest of Mumbai High and provided high-resolution strontium isotopic chronostratigraphy for equivalent sub-layers A to E in the Cluster-7 area SW to Mumbai High. These ages have provided new numerical age constraints for the L-III and its sub-units for the first time, are correlatable across different well sections, and are in perfect agreement with reported biostratigraphic ages for the Bombay Formation and the sub-units within. This has important implications for effective reservoir management and performance prediction for the hydrocarbon-producing pays in the studied L-III reservoir unit.

A coupled three-dimensional wormhole modeling in heterogenous carbonate lithology in limited-entry and openhole completions

Wormhole propagation in carbonate formation is a well-researched area with several proposed empirical, analytical, and numerical models to predict the process efficiency. The most reliable and up-to-date model is the two-scale continuum (TSC) model, based on numerical simulation of reactive transport in a porous medium. The model has been utilized in two and occasionally in three-dimensional space but has yet to consider the lithology impact in three-dimensional space (3D). This study demonstrated the impact of lithology considering both openhole and limited-entry completion in 3D space. Moreover, the model considered the acid temperature impact on acidizing efficiency. Results showed that limited entry results in a longer wormhole at the expense of its coverage along the wellbore. Similarly, the higher the number of perforations, the lower the wormhole radius but the higher the coverage. Increasing acid temperature results in better dolomite and lower limestone acid stimulation efficiency. In mixed mineralogy, the positive impact of temperature appears at 50 °C and higher. Wormholes propagate in the limestone sections in layered formation with openhole completion, leaving the dolomite under-stimulated, even at high acid temperatures. Limited entry completion in dolomite layers did not prevent the acid from traveling to the limestone layers but provided limited stimulation in the dolomite section. This is the first study to utilize the TSC model to predict the acid stimulation outcomes at field conditions in 3D space.

An integrated approach for characterization of a fractured-rock carbonate aquifer in the Zagros Region of Iran

Karst aquifers typically exhibit a wide range of dissolution effects that include end-members of matrix, fractured-rock, and conduit-dominated types. This study employs an integrated approach involving geological studies, hydrogeological assessments, hydrochemical and isotopic analysis, and dye tracer tests to investigate the Sarvak limestone aquifer (SLA) in the Zagros Region, southwest Iran. Key characteristics of the SLA include numerous stratification boundaries, thin limestone layers with intercalated siliceous and marl impurities, extensive joint and fracture networks, predominant autogenic recharge, and absence of notable point recharge features (e.g., sinkholes, dolines), and the exchange flow with the Bakhtiari River (B-R) has made it a unique aquifer. Numerous pieces of evidence, such as low spatial and temporal changes in groundwater level, insignificant seasonal variations in the hydrochemical and isotopic composition of water samples, and the supersaturation state of groundwater with calcite and dolomite minerals, suggested a slow flow regime in many parts of the SLA. This regime is characterized by low velocity and long residence time of groundwater. The results reveal that despite the high solubility of carbonate rocks, extensive joint networks can limit significant karst development, leading to fluid flow behavior similar to that of fractured-rock aquifers. Therefore, SLA can be considered a fractured-rock and karst aquifer. The identified paths with fast flow in the dam area are unremarkable and cannot provide a large portion of the Pelle Khan Spring discharge.

Cretaceous Limestone Dolomitization and Argument of Its Mg2+ Sources: Exampling the Bekhme and Qamchuqa Formations in the Zagros Collision Belt

This study unveils new considerations regarding the dolomitization of the Bekhme and Qamchuqa formations (BQFs), two reefal Cretaceous units in the Iraqi Zagros collisional belt. Previous studies proposed the dolomitization of these formations due to the ascent of Mg-rich hydrothermal solutions through deep faults but lacked substantial supporting evidence. This paper present new considerations suggesting that the dolomitization of the BQFs resulted from the Cretaceous environmental conditions and basin paleogeographic setting of the platform on which these formations were deposited. To justify this consideration, seven proofs presented. First is the occurrence of dolomite as vast layers extending tens of kilometers laterally and bounded between limestone beds, which resemble a strata-bound occurrence. Second is the absence of vertical selective dolomitization such as, hydrothermal mineralization, vertical dolomite dykes, hydrothermal vents, tubes, or zones. Third is the barrenness of most of the fault surfaces and their surrounding rocks with selective dolomitization. Fourth is the sharp boundary between the dolomite and limestone layers, indicating a sudden environmental change from lagoon to reef or forereef. Fifth is the record of dolomitization in the sediments reworked by bioturbation, evident in thalassinoides burrows. Sixth is the succession of BQFs underlain by limestone and green marl devoid of dolomitization and hydrothermal upward movement. Seventh is the contradictory notion of hydrothermal dolomitization among the most recent study published in the Science journal which atributed dolomitization to normal temperate on earth surface. In the present study, the source of the Mg is argued and its presence is attributed to the warmth of the Arabian platform (plate) near the equator during the Cretaceous period. Another source is the connection of the Arabian platform with the Neo-Tethys Sea, which was the locus of Mg-rich mafic volcanism in the form of arcs and mid-oceanic ridge topography, which supplied a voluminous amount of Mg to the Arabian carbonate platform through ocean currents.

Taphonomy of the middle Miocene regular echinoid spines from Cairo-Suez District, Egypt: Palaeoecological and palaeoenvironmental interpretations

The palaeoecology and palaeoenvironment of a dense cluster of regular echinoid spines that occur in an oyster-rich limestone layer are interpreted based on detailed taphonomic study. The paucispecific macrobenthic assemblage associated with these echinoid spines have been studied in the middle Miocene Geniefa Formation, Gebel Gharra, Cairo-Suez District of Egypt. Both echinoid spines and macrobenthic assemblages are dominated by moderately to well-preserved, moderately packed, highly disarticulated, moderately to poorly sorted, re-oriented, and moderately to highly fragmented specimens, confirming parautochthonous nature of this assemblage. The spines are commonly encrusted and bored. At least four taxonomic groups of encrusters are identified, including juvenile oysters, sheet-like cheilostome bryozoans, serpulids, and balanoid barnacles. The diversity of bioerosional ichnotaxa is moderate and includes Gastrochaenolites, Entobia, Maeandropolydora, Trypanites, and Spirolites. Moreover, some echinoid spines display distinct biting traces of fish, representing the first recorded of fish tooth bite marks on remains of regular echinoid spines from the Miocene deposits of Egypt. The faunal composition and trophic structure of the studied faunal assemblage indicate fully oxygenated and euhaline shallow-marine environment with meso- to eutrophic productivity level. The controlling environmental parameters include substrate consistency, bathymetry, water energy, surface-water productivity, and rate of sedimentation. Furthermore, two scenarios for sclerobionts colonisation and development of fish bite marks have been proposed. In the first syn vivo scenario, predatory fish either focused on the encrusting organisms attached to the spines or attacked the echinoid as a food source, resulting in the separation of spines from their original test during the echinoid’s life. In the second post-mortem scenario, disarticulated spines serve as a hard substrate for the colonisation of sclerobionts. Once again, the spines became subject to attacks by fish that fed on the encrusters, resulting in additional bite marks.

Investigation of oil/water two-phase flow behavior in laminated shale porous media considering heterogeneous structure and fluid-solid interaction

The laminated structure of continental shale oil reservoirs introduces significant macro and micro heterogeneity, posing challenges for efficient shale oil extraction. Existing microscopic experimental and simulation methods are insufficient to accurately simulate the fluid flow behavior in mud–lime interactive laminated shale reservoirs. This study delves into the complexities of laminated shale reservoirs with a focus on their heterogeneous structure and wettability. Using scanning electron microscopy, we extracted the structural features of laminated shale reservoirs and established a Multicomponent and multiphase -multi relaxation time-Lattice Boltzmann model(MCMP-MRT-LBM) that considers nanoscale effects such as wall adsorption, liquid–solid slippage, and liquid–liquid slippage. We investigated the occurrence state, the flow behavior, and the phase seepage characteristics of crude oil in laminated shale at different water saturation stages and explored the reasons behind interlayer channeling and the conditions under which crude oil is mobile within limestone and mudstone layers. Then, we examined the impact of varying factors, including heterogeneous wettability, displacement pressure gradients, and pore size, on relative permeability, water injection capacity, sweep efficiency, and crude oil recovery in laminated reservoirs. The results indicate that wettability and pore size distribution, driven by capillary and viscous forces, dictate the occurrence state of remaining oil. Wettability primarily influences fluid distribution, whereas pore size distribution substantially impacts fluid morphology. It also highlights the pivotal role of flow velocity differences between layers in causing interlayer channeling. Increasing the capillary number promotes crude oil mobility within mudstone layers, with the initiation pressure gradient in mudstone layers being 2.5 times that of the limestone layer. The examination of the oil–water relative permeability reveals the dominance of pressure gradients in affecting oil flow capabilities, while pore size significantly influences water flow capacity. By optimizing various factors, it is possible to enhance water injection capacity and sweep efficiency, resulting in a substantial 5%–10% increase in crude oil recovery from laminated shale reservoirs.

Nodal Analysis of Naturally Flowing Wells in Faihaa Oil Field, Yamama Formation

This study focuses on the Yamama Formation, a significant carbonate reservoir in southern Iraq that is one of the most important productive reservoirs in the region. The Formation is characterized by porous limestone interspersed with thin layers of argillaceous and tight limestone. The Yamama reservoir in the Faihaa oil field is divided mainly into four units; YA, YB, YC, and YD. YA and YB units are considered to be the most important oil-bearing subunits due to their good petrophysical properties. The main objective of the study is to determine the optimum production rates of four naturally flowing wells in the Faihaa oil field using the Inflow Performance Relationship and Vertical Lifting Performance curves. The study investigates four critical parameters; tubing size, water cut, reservoir pressure, and wellhead pressure, and their impact on well performance. The study finds that wellhead pressure is the primary determinant of well performance, and deviations from the original tubing size have adverse effects on well performance. An increase in water cut beyond the recommended threshold, coupled with a reduction in reservoir pressure, results in decreasing well performance. The study underscores the importance of careful monitoring and analysis of these parameters to sustain and enhance well performance in the Faihaa oil field, providing valuable insights for well operators and petroleum engineers. The study's findings can be used to optimize well performance and increase oil production rates, with significant implications for the petroleum industry.

Electrical Resistivity Tomography (ERT) for investigating subsurface structures in the karst area of the Ek Leuntie Cave, Aceh Province

Ek Leuntie Cave, in the southern city of Banda Aceh, Aceh Province, is recognized as an educational media based on geopark sites because it holds a 7400-year paleotsunami track record. As a karst area, Ek Leuntie Cave is vulnerable to the impact of geological disasters such as earthquakes, sinkholes and subsidence. As an effort to reduce the negative impact of geological disasters, geophysical studies have been applied in the Ek Leuntie Cave Karst area. The study aims to identify the subsurface geological structure of the Karst area. The identification was carried out using the Electrical Resistivity Tomography (ERT) method of Wenner-Schlumberger configuration applied to two measurement trajectories that have South-North and West-East directions in front of the Ek Leuntie Cave door. ERT data acquisition results were then modeled in inversion using Res2Dinv software to produce a 2D model of the subsurface geological structure of the Ek Leuntie Cave karst area based on variations in rock resistivity values. Interpretation of subsurface geological structure modeling is validated with shallow drilling data (Hand Auger). The inversion modeling results show that the rock resistivity value in the Ek Leuntie Cave area reaches a depth of 30 m which has a resistivity value of 0 - 1000 Ωm. The results of the interpretation of resistivity values and validation of drill data show that the Ek Leuntie Cave area is covered by a layer of sand with fine to coarse texture and the layer below is a layer of limestone at a depth of ± 0.4 meters with a resistivity value of 50 - 250 Ωm. Limestone generally shows porosity with the possibility of caves or pores in the rock formation at Ek Leuntie Cave, making it vulnerable to damage from earthquakes, landslides, and subsidence. The results of the study are expected to provide updated information in efforts to develop the Ek Leuntie Cave geopark area.

Identification of Underground River Flow Using VLF (Very Low Frequency) and Geoelectricity at Karstic Area

Mapping underground river karst areas in the karst mountains Cianjur, West Java, has been done using electromagnetic methods and Geoelectricity Dipole-dipole. Karst constituent formation region of West Java area is limestone, clay stone, limestone fractured, hard and dense limestone, and limestone containing no water (rigid). The aim of this research is to search for the existence of underground rivers using electromagnetic and geoelectric wave surveys. VLF method consists of 13 line with a length of 750 m and a 10 m spacing. Based on the results of data processing VLF method is known that the equivalent current density (ECD) demonstrated high conductive rocks. While Geoelectricity method consists of 10 line, the arrangement is a parallel between the distance of the line with a space of 20 m andlength between 300 m.VLF data interpretation results indicate anomalous equivalent current density (ECD) with high scores range from 180-300% indicated fractured limestones are occupied by water, while the resistivity anomaly from 0.45 to 7.40 Ω.m indicated as weathered limestone layers accumulated dengn clay stone, resistivity values 186-701 Ω.m, fractured limestones indicated that fills with water. With sizes ranging 5-15 m cavity, each line with nearly the same distance at a depth of approximately 15-105 m, there is a large cavity-cavity interconnected.

A Comparative Analysis and Environmental Interpretation of the First Cycle of Nfayil Formation in Two Distinct Southern Desert Locations, Iraq

Nfayil Formation (Middle Miocene) is considered the equivalent of Fatha Formation; it is exposed in the western and southern Desert of Iraq with two members: a carbonate Lower Member that is composed of three cycles of limestone and marlstone intercalation and an Upper clastic Member of sandstone and claystone with thin layers of limestone. It extends from the western to the southern desert with a systematic succession of two or three cycles of lower members each one consisting of an interbedding of soft olive-green marl with medium tough shelly limestone rich with oyster shells. The upper member disappears in many localities due to erosion activity. From the field observation this succession was normally exposed in the southern Desert at the western parts of Al-Muthanna Governorate to the south of Dewaniyah Governorate, while in the eastern part of Al-Muthanna Governorate to the south of Al-Nasiriya Governorate, the beds showed a different lithology and fossil content. The olive-green marl turned to be rusty red with a higher content of fossils, the shelly limestone bed rich with oyster shells became red in colour, rusty and the oyster shells were substituted by pelecypods shells with the same concentration. A microfacies analysis study supported by chemical and X-ray analysis was carried out to predict the depositional environment and deposition circumstances in both sections. The thin section, chemical analysis and X-ray analysis were accomplished at the laboratories of the Iraq Geological Survey. Chemical analyses showed a high ratio of MgO oxide in Nasiriya section compare with Samawa section, that result was supported by X-ray analyses which refer to calcite mineral as the only mineral exists in Samawa beds wile in Nasiriya minerals of dolomite, quartz, feldspar and clay minerals were appeared.Environments extracted from thin section study showed more local fluctuations in sea level in Samawa section.

Delineation of the proper locations for wastewater disposal in arid regions using TEM and ERT techniques: A case study at Rubiki industrial zone, Badr City, Egypt

Proper wastewater disposal is crucial for the sustainable development of rapidly growing megacities worldwide. The emergence of waterlogging near evaporation ponds (EVP) and in desert areas surrounding these cities poses a significant environmental threat. This study employs an integrated approach, combining transient electromagnetic (TEM) and 2D-electrical resistivity tomography (2D-ERT) methods with remote sensing techniques, to understand wastewater flow patterns around EVPs and identify suitable disposal sites. The research focuses on a complex subsurface structure in the Cairo-Suez district, characterized by extensive surface waterlogging. Initial monitoring relies on satellite imagery and land use-land cover maps. TEM provides an overview of subsurface layer distribution, while 2D-ERT offers detailed insights into near-surface flow paths. To address the limitations of geoelectrical methods in locating conductive layers, advanced inversion techniques (AIS) are applied. The findings reveal a four-layer subsurface composition, with waterlogging primarily attributed to the argillaceous limestone layer interbedded with shale. This layer is shallower in the eastern and northwest areas, correlating with higher instances of waterlogging. Moving northward, the argillaceous limestone layer deepens, and the upper clastic layer thickens, resulting in reduced waterlogging. The study underscores the influence of subsurface structure on near-surface layer distribution. Based on these findings, optimal wastewater disposal sites are recommended, with a focus on the northern region where the argillaceous limestone layer is deeper and the upper clastic layer is thicker. To mitigate waterlogging, the installation of disposal wells is highly advised, leveraging the insights derived from this research. This study offers a versatile and reproducible approach suitable for both pre-project planning and post-project phases in desert regions.

Gold-arsenic sulfide mineralization of the Kayancha area, Gorny Altai

Gold-arsenic sulfide type mineralization has first been revealed for the Gorny Altai region. The mineralized zones associate with lamprophyre dikes and are controlled by steeply dipping faults transecting the Vendian-Cambrian terrigenous-carbonate-volcanogenic sequence. The ore bodies are localized in horizons of basic metavolcanic rocks, enclosed between limestone layers. The near-ore metasomatites are composed of the paragenesis of albite, magnesiosiderite, and sericite. The gold content is related to fine dissemination of arsenic pyrite and arsenopyrite. Gold in the primary and oxidized ores is
 submicroscopic and finely dispersed. The sulfur isotopic composition of the sulfides (δ34SCDT = 0 ‰) indicates an association of the mineralization with a deep-seated magmatic source. The Kokpatas gold deposit in western Uzbekistan is considered as an analogue.

Impact assessment of the effects of the former uncontrolled landfill of Sidi Yahya Oujda (Morocco) on groundwater using physicochemical, geological and electrical triple approaches

This study is part of the geophysical mapping of the former site of the uncontrolled Sidi Yahya Oujda landfill. It also aims to show the contribution of the integrated interpretation of geological and geophysical data in the diagnosis of illegal dump sites. The application was made on the rehabilitated site of the former uncontrolled Oujda landfill located in Sidi-Yahya, which was closed in 2005. Geological and geophysical studies by electrical resistivity tomography (TRE) were carried out at the site level. Nine 475 m long TRE profiles with an investigation depth of up to 110 m were generated to image the subsoil. Analysis of the physicochemical and metallic composition of the leachate from this site and the groundwater taken from 3 nearby wells revealed significant pollution of the leachate with a COD of 12780 mg. O2/L and a BOD5 of 525.34 mg. O2/L. The groundwater had high electrical conductivity (average of 3.9 mS/cm), chloride content (710 mg/L average) and nitrate content (74.62 mg/L average). The metal concentrations in the leachate and groundwater far exceeded the Moroccan standards, with high average values for zinc (619.22 μg/L), copper (318.12 μg/L), nickel (233.76 μg/L), chromium (169.16 μg/L), L) and iron (12940 μg/L). Geologically, a context was highlighted with lateral lithological variations and the presence of faults. The waste/leachate layer has low resistivity values (<10 Ω m) and a thickness of up to 25 m. It rests on terrains of different geological natures. In the southern part of the site, there is a layer of red clay with a thickness of up to 50 m and low resistivities (<10 Ω m), which overlies a layer of limestone with high resistivity values (>100 Ω m). In the northern part, we encounter a discontinuous and thin layer of fractured dolomites with resistivities greater than 50 Ω m. This layer of dolomite rests on a layer of clays.