Geological Structural Analysis Research Articles

Travertine and calcareous tufa occurrences as an indicator of the ongoing tectonic activity of the Central Slovak Fault System inferred from airborne laser scanning data, geomorphometric, and structural analysis (Northern Slovakia)

The travertine formation process, active over the Quaternary, has enabled the origin of one of the largest travertine accumulations in the Western Carpathians. Travertines and calcareous tufas are associated with the tectonic activity of the Central Slovak Fault System, a 45 km wide and 140 km long N-S oriented fault zone. As the geological mapping, structural analysis, geomorphometric and isobase surface analysis revealed, the development of faults was polyphase and the travertine/tufa precipitation was not a continuous process. In addition, numerous travertine/tufa morphofacial varieties have been recognized within the study area, such as travertine/tufa terraces and tufa cascades, hillslope paludal tufa crust, phytoherm framework tufa barrages, lacustrine microdetrital tufas, bryophyte-dominated self-built channel, and fluvial tufa crust, reflecting its local geomorphology and precipitation factors. In the Revúcka dolina Valley, the travertine/tufa geobodies thus represent a reliable indicator of the tectonic activity over the Neogene up to Quaternary. The structural data provided relevant evidence confirming the character of orogen-parallel extension for the current tectonic/neotectonic regime in the Inner Western Carpathians. High-resolution topography derived from airborne laser scanning and the subsequent application of various geomorphometry techniques allowed quick identification of the edges of the terrace cascade systems and morpholineaments. Based on our observations, in this zone, the significant vertical movements of normal faults took place with a maximum estimated offset of 800–1000 m. The achieved results also support the use of the presented multifaceted methodology to understand the interplay between geomorphogenesis, hydrology, and tectonics.

Unravelling the tectonic evolution of the Dinarides—Alps—Pannonian Basin transition zone: insights from structural analysis and low-temperature thermochronology from Ivanščica Mt., NW Croatia

A comprehensive study, including geological mapping, structural and thermochronological analysis, has been carried out on Ivanščica Mountain (NW Croatia), with the aim to reconstruct the tectonic history of the Dinarides, Southern/Eastern Alps and Pannonian Basin transitional zone. Implementation of structural and thermochronological methods enabled a subdivision of Ivanščica Mt. into two structural domains (from bottom to top): Ivanščica Parautochthon and Ivanščica Imbricate Fan and Cenozoic sedimentary cover. In addition, a sequence of deformational events in tectonic history of this transitional zone is proposed, comprising three extensional and four contractional events starting from Middle Triassic until present times. The two oldest deformational events indicate Middle Triassic (D1) and Early Jurassic (D2) extensional pulses and only occur in volcano-sedimentary successions of the Ivanščica Mt. The oldest contractional event (D3) is related to the obduction of a Neotethyan ophiolitic mélange over an Upper Triassic to Lower Cretaceous succession of the eastern margin of the Adriatic microplate, which resulted in thermal overprint of the Ivanščica Imbricate Fan structural domain in Berriasian—Valanginian times (~ 140 Ma). This event was soon followed by a second contractional event (D4), which resulted in thrusting and imbrication of the Adriatic passive margin successions together with previously emplaced ophiolitic mélange, thermal overprint of the footwall successions, fast exhumation and erosion. Apatite fission track data together with syn-tectonic deposits indicate an Hauterivian to Albian age of this D4 event (~ 133–100 Ma). These Mesozoic structures were dextrally rotated in post-Oligocene times and brought from the initially typically Dinaridic SE striking and SW verging structures to the recent SW striking and NW verging structures. The following extensional event (D5) is associated with the formation of SE striking and mostly NE dipping normal listric faults, and ENE striking dextral faults accommodating top-NE extension in the Pannonian Basin. Deformations were coupled with hanging wall sedimentation of Ottnangian to middle Badenian (middle Burdigalian to upper Langhian; ~ 18–14 Ma) syn-rift deposit as observed from the reflection seismic and well data. A short-lasting contraction (D6) was registered in the late Sarmatian (late Serravallian; ~ 12 Ma). The youngest documented deformational event (D7) resulted in reactivation of ENE striking dextral faults, formation of SE striking dextral faults as well as the formation of E to ENE trending folds and reverse faults. This event corresponds to late Pannonian (late Messinian; ~ 6 Ma) to Present NNW-SSE contraction driven by the indentation and counterclockwise rotation of Adriatic microplate. Recognized tectonic events and their timings indicate that Ivanščica was mainly affected by deformational phases related to the Mesozoic evolution of the Neotethys Ocean as well as Cenozoic opening and inversion of the Pannonian Basin. Therefore, the Mesozoic tectono-sedimentary evolution of Ivanščica Mountain proves the paleogeographic affiliation of its non-ophiolitic Mesozoic structural-stratigraphic entities to the Pre-Karst unit of the Dinarides.

Deep Geological Structure Analysis of the Dongyang Area, Fujian, China: Insights from Integrated Gravity and Magnetic Data

To explore the deep geological structure of the Dongyang area in Fujian, China, gravity data from the area and its surroundings were collected and processed. Additionally, a high-precision magnetic survey was conducted in the Zhongxian region of this area, with subsequent analysis of the magnetic anomalies. Through the integration of regional geological data, a comprehensive analysis was carried out on the characteristics of gravity–magnetic anomalies and deep geological structures in the Dongyang area. The study indicates that the primary portion of the Dongyang area lies southwest of the expansive circular volcanic structure spanning Dehua to Yongtai. Two significant residual gravity anomalies were identified within the region, interpreted as the Xiaoban-Shuangqishan and Dongyang-Lingtouping residual gravity-positive anomalies. In the Zhongxian region, the magnetic field exhibits complexity with notable amplitude variations. Positive anomalies predominate in the western and northern sectors, while localized positive anomalies are prominent in the eastern region. The central area portrays a circular and disordered mix of positive and negative anomalies. Particularly distinctive are the band-shaped and fan-shaped negative anomalies curving from northeast to southeast through the central region. Various positive and negative anomalies of varying strengths, gradients, and orientations overlay both positive and negative magnetic backgrounds in specific locales. Moreover, the Dongyang area showcases well-developed fault structures, primarily oriented in northeast and northwest directions. Leveraging the regional magnetic attributes in conjunction with regional geological data, 39 faults were deduced in the Zhongxian region of the Dongyang area, delineating three promising mineralization zones.

Aproximación geomecánica usando velocidades de onda y su relación con el parámetro “b”

In this research, an exhaustive and rigorous analysis about microseismicity and its importance for the analysis of geological structures will be presented, with special attention on the application of the GSI table and its relationship with safety. Microseismicity is the technique of detection and analysis of small seismic events that occur during the advance and mining exploitation, and its study is fundamental to guarantee a safe and efficient operation. The presence of these seismic events indicates the existence of stresses and deformations in the geological structures, which can have a significant impact on the safety of the operation. Therefore, microseismicity monitoring is an essential tool for geomechanical risk management. In this thesis the relationship between microseismicity and geological structures will be explored, using the GSI table as an important tool for the interpretation of microseismic data. The GSI table is a tool developed by the International Society for Rock Mechanics to assess the geomechanical stability of rock structures. In this work, the microseismic data will be analyzed and correlated with the GSI table, which will allow a better understanding of the geomechanical characteristics of the mine and a more accurate evaluation of geomechanical risk.

The Concept of Lineaments in Geological Structural Analysis; Principles and Methods: A Review Based on Examples from Norway

The Concept of Lineaments in Geological Structural Analysis; Principles and Methods: A Review Based on Examples from Norway

Preliminary analysis of the indicators and accumulation models of gas hydrates in the central Zhongjiannan Basin, western South China sea

The Zhongjiannan Basin is located in the western continental margin of the South China Sea (SCS). It was recently reported that there are geophysical indicators of gas hydrates in the northern Zhongjiannan Basin. However, due to the lack of in-depth studies, it remains unknown whether geophysical indicators of gas hydrates are also available in the central and southern Zhongjiannan Basin. Based on the latest geophysical data, we have identified the seismic anomaly features of gas hydrates and observed an obvious bottom simulating reflector (BSR) in the seismic section in the central Zhongjiannan Basin. Based on a comprehensive analysis of seismic characteristics, geological structures (e.g., faults, diapirs and pockmarks) and regional sedimentary conditions, we propose three accumulation models of gas hydrates in the central Zhongjiannan Basin. The first model is that gas develops in deep depression areas, migrates upwards from deep source rocks along vertical faults and forms reservoirs in shallow formations. The second model is that gas also forms in deep depression areas and rises along mud diapirs or gas chimneys from source rocks to shallow formations, with reservoirs formed above diapirs and/or mud volcanoes. The third model is that gas is mainly generated in slope areas where strata are relatively thin and fault structures are well developed; gas migrates upwards from source rocks along vertical faults, and reservoirs are formed beneath pockmarks. The geophysical indicators of gas hydrates are found for the first time in the central Zhongjiannan Basin of the SCS, yielding an important reference for further exploration and development.

Structural analysis applied to the tectonostratigraphic reconstruction of the Abadia dos Dourados Metavolcano-sedimentary Sequence, southern Brasília Orogen: Implications for the West Gondwana assemblage

Structural analysis is a valuable tool for organizing the stratigraphy of metamorphic terranes. It allows the reconstruction of pre-to sin-orogenic geological scenarios by unraveling the main transformations, such as distortion, rotation and translation, associated with the collisional process in orogenic belts. The Brasília Orogen, for example, encompasses a complex spectrum of lithological associations and structural patterns that are not well understood because this orogenic belt still has a limited coverage of detailed structural analysis work. The implications of this are problematic for the reconstruction of pre- and sin-collisional processes related to the evolution of western Gondwana. Therefore, this contribution focuses on the Abadia dos Dourados Metavolcano-sedimentary Sequence located between the states of Minas Gerais and Goiás, Brazil. The study includes a field-based structural investigation, including geologic mapping and structural analysis at various scales of observation. It was recognized that the Abadia dos Dourados Metavolcano-sedimentary Sequence comprises a bimodal volcanic association with metarhyolite, metabasalt, banded iron formation and tourmalinite, as well as metapelites and metapsamites from base to top. The data provide additional evidence for a rift-related or back-arc basin-related model for the origin of the Meso-to Neoproterozoic volcano-sedimentary sequences in the Brasília orogen. The structural framework indicates a northeast-southwest crustal shortening event associated with the collision of the Paranapanema and São Francisco-Congo crustal blocks. The event initially produced a large (about 10 km) northeast-verging recumbent fold nappe in the area, which caused a stratigraphic inversion of the metavolcanic-sedimentary sequence. The structure underwent progressive deformation, resulting in superposition patterns between folds, foliations, and intersection lineations. In addition, the structural framework suggests that the West Gondwana collage may be related to a progressive rather than a multiphase structural evolution in the southern Brasília Orogen.

STRUCTURAL POSITION AND DISTRIBUTION OF THE LOWER CRETACEOUS BLACK SHALE DEPOSITS WITHIN THE SILESIAN NAPPE OF THE UKRAINIAN CARPATHIANS

The article presents the results of studying the structural position and distribution of potentially oil-generating, organic-enriched Lower Cretaceous black shale deposits of the Shypot Formation, developed within the Silesian Nappe, using the methods of geological mapping and structural analysis. We concluded, that these deposits, which are exposed in the Vicha River basin near the town of Volovets among a continuous field of Oligocene flysch, are the part of the stratigraphic succession of the Silesian Nappe, and they are not a large olistolith or an allochthonous tectonic remnant of another, more internal nappe. Shypot Formation fills a large (1 × 3 km) subvertical tectonic lens. The rocks of the Shypot Formation are represented here by medium-rhythmic flysch: sandstone beds alternating with dark gray and black foliated mudstone (black shale) layers. They are lithified products of both medium-density turbidite flows and hemipelagic deposition of clayey material with a significant amount of organic matter. In the contact zone of the tectonic lens with the surrounding rocks, the deposits are intensively deformed, almost isoclinal folds with subvetrical hinges are observed, which suggest the strike-slip movements. A tectonic mélange is recorded here, which is represented by small blocks (clastolites) of brittle sandstones, sometimes similar to Shypot sandstones, placed in a silt-pelitic ductile matrix. Foliation of the mélange matrix is also subvertical and close to the meridional and/or subcarpathian direction. The structural studies carried out show that in the zone of this contact there were compressive stresses perpendicular to the Carpathian orogen, and stress fields that caused strike-slip movements, most likely right-lateral along the Carpathian thrusts. The tectonic lens is located within the broad Latorytsa-Stryi shear zone, and probably extruded out from deep horizons by transpressive movements (compression and strike-slip) and forms a “positive flower structure”. The vertical foliation in the mélange suggests that small blocks of Shypot sandstones were extruded up together with the ductile mélange matrix during diapirism. Similar processes probably led to the rise of a large lens of Shypot sandstones as the positive flower structure. The studies suggests that the black shale deposits of the Shypot Formation, enriched with organic matter, are widespread at some depth within the Silesian Nappe, and in some places are pushed up to the level of the Oligocene flysch. As a result, the Shypot Formation and Oligocene flysch are now in direct contact along faults/mélange zones. The presence of Lower Cretaceous potentially oil- and gas-generating black shale deposits within the Silesian Nappe significantly increases the prospects for oil and gas exploration in this area.

An Application of 3D Cross-Well Elastic Reverse Time Migration Imaging Based on the Multi-Wave and Multi-Component Technique in Coastal Engineering Exploration

Precise surveys are indispensable in coastal engineering projects. The extensive presence of sand in the coastal area leads to significant attenuation of seismic waves within unsaturated loose sediments. As a result, it becomes challenging for seismic waves to penetrate the weathered zone and reach the desired depth with significant amount of energy. In this study, the application of three-dimensional (3D) cross-well elastic reverse time migration (RTM) imaging based on multi-wave and multi-component techniques in coastal engineering exploration is explored. Accurate decomposition of vector compressional (P) and shear (S) waves is achieved through two wavefield decoupling algorithms without any amplitude and phase distortion. Additionally, compressional wave pressure components are obtained, which facilitates subsequent independent imaging. This study discusses and analyzes the imaging results of four imaging strategies under cross-correlation imaging conditions in RTM imaging. The analysis leads to the conclusion that scalarizing vector wavefields imaging yields superior imaging of P- and S-waves. Furthermore, the imaging results obtained through this approach are of great physical significance. In order to validate the efficacy of this method in 3D geological structure imaging in coastal areas, RTM imaging experiments were performed on two representative models. The results indicate that the proposed 3D elastic wave imaging method effectively generates accurate 3D cross-well imaging of P- and S-waves. This method utilizes the multi-wave and multi-component elastic wave RTM imaging technique to effectively leverage the Earth’s elastic medium without increasing costs. It provides valuable information about the distribution of subsurface rock layers, interfaces, and other structures in coastal engineering projects. Importantly, this can be achieved without resorting to extensive excavation or drilling operations. This method addresses the limitations of current cross-well imaging techniques, thereby providing abundant and accurate geological and geophysical information for the analysis and interpretation of 3D geological structures in coastal engineering projects. It has important theoretical and practical significance in real-world production, as well as for the study of geological structures in coastal engineering.

Analysis of Geological Structure based on 3D Virtual Outcrop Model and Physical Properties of Rocks in Wringinanom District, Gresik Regency

The Covid-19 pandemic has caused geological mapping activities to be hampered. This study aims to create a 3D virtual rock outcrop model which is compiled from 2D rock outcrop images with Measured Stratigraphy (MS), strike & dip and the value of rock physical parameters to analyze geological structures in Wringinanom District, Gresik Regency. Analysis of geological structures will be contained in the form of folding reconstructions with rock physical parameter as a validation and descriptions of fault orientation. This research modeled 21 rock outcrops and will be tested 6 core sedimentary rock samples. Physical rock parameter tests in the form of density tests through the comparison of mass weighing results with dimensional measurements by calipers and P-wave velocity tests using the Ultrasonic Pulse Velocity (UPV) method. Petrological descriptions of core rock samples are based on direct observations. The results of 3D virtual rock outcrop integrated with measurements in the field can be used in analyzing geological structures. The study area consists of anticlines with the direction of layering the south (southwest) and north (northeast) wings and 50-degree reverse faults with southeast dipping orientation (N153°E). The folding reconstruction consists of sandstone (top), sandstone-clay interlude, and claystone (top) in the Pucangan Formation and sandstone (bottom) and claystone (bottom) in the Lidah Formation where the presence of fossil layers of bivalve mollusks is a firm correlation. The physical parameters of rocks cannot validate the reconstruction of folds due to the influence of differences in physical values of the sample supported by petrological descriptions.

Local coupled Markov chain model for simulating varied stratigraphy

The coupled Markov chain (CMC) model is widely employed to simulate geological uncertainty based on sparse borehole data, owing to its simplicity, parameter efficiency, and computational effectiveness. However, the existing CMC methods exhibit limitations in accurately predicting the orientation and significant dip angle changes of soil stratigraphy. These limitations stem from their reliance on a globally constant Walther constant, resulting in generated layer boundaries converging to a fixed angle. To address these issues, this study develops a local CMC model to enhance the accuracy of predicting layer sequences and describe the geological uncertainty of complex geological structures using limited borehole and surface data. In the proposed local CMC method, the global geological profile is decomposed into interconnected fragments, guided by reference boreholes. For each CMC fragment, the likelihood of observational scenarios is determined to identify the layer orientation and optimal Walther’s constant corresponding to the local geological profile. By combining the most likely realizations from all CMC fragments, the final geological profile and stratigraphic uncertainty are obtained. Illustrative case studies demonstrate that the proposed approach effectively addresses the limitations of conventional CMC models in accurately simulating significant changes in layer orientation and dip angle variations, given the same conditions of sparse borehole data. The employed localization strategy enables the prediction of geological profiles that encompass special layers such as soil interlayers, anticlines, and synclines, which cannot be well achieved by conventional CMC models. The local CMC model significantly improves the matching accuracy of geological model in situations with limited boreholes. Therefore, it plays a crucial role in the analysis of geological structures under data-scarce conditions.

LITHO-STRUCTURAL MAPPING USING REMOTE SENSING AND FIELD WORK TECHNIQUES: A CASE STUDY FROM CENTRAL SALT RANGE ARA, RAWAL AND SIDHANDI VILLAGE, PUNJAB PAKISTAN

In the Central Salt Range lithological structural mapping has been a great challenge and of great interest to geologists as it is in rugged and inaccessible mountain terrain. In this paper a comprehensive lithological mapping conducted in the villages of Ara, Rawal and Sidhandi which are located in Central Salt Range region of Punjab, Pakistan. This study uses a combination of remote sensing techniques and field work to elucidate the geological and structural characteristics of the study area. Due to complex tectonic history and mineral resources Central Salt Range is of great geological interest. In this research we combined data from geological field observations and satellite images to produce detailed lithological and structural maps. Remote sensing data help to identify surface features and geological structures. These ground truth observations are complemented by extensive field work including geological mapping and structural analysis. Our work represent a diverse rock composition in the study area, including sedimentary rocks and various fault systems. We classify fault zones on basis of their characteristics, and our structural analysis provides insight into the fault history of the region. Moreover, the study discusses the implications of these geological features for understanding regional tectonics, potential mineral deposits, and land resources in the area. This work demonstrates the synergy between remote sensing techniques and fieldwork in understanding the geological complexities of the Central Salt Range. This work provides valuable information for geological mapping and risk assessment in the area. Additionally, this research demonstrates the importance of a multidisciplinary approach in geological investigations, emphasizing the importance of integrating remote sensing and field data to enhance our understanding of complex geological environments. Keywords: Litho-structural mapping, Remote sensing, Fieldwork techniques, Central Salt Range, Ara, Rawal, and Sidhandi villages, Punjab, Pakistan, Geological analysis, Satellite imagery, Structural mapping, Fault systems, Geological features, Tectonic history, Mineral resources, Sedimentary rocks, Deformation history

Structural geology and deformation analysis in the Búzios-Itapu area, Santos Basin — offshore Brazil

Despite their proximity, the Búzios and Itapu oil fields in the Santos Basin have different structural configurations. The study of the deformation pattern of the area and the relationship of the observed structures with the tectonic evolution of the basement is important to understand the geologic setting and evolution of the studied oil fields. In this work, a 3D PSDM seismic volume calibrated with well data was used to characterize the different types of structures, the distinct structural domains that occur in the Pre-Salt of the Búzios and Itapu fields, and the relationship between the basement trends and the structures in the sedimentary section. The Búzios field is formed by a series of half-grabens and horsts elongated in the NE-SW and NW-SE trends. Over the structural highs, a wide carbonate platform was developed. The Itapu field is a structural high related to a single elongated half-graben with a N-S main trend. The main structural pattern in the area is defined by normal faults that indicate an extensional process, typical of rift evolution. However, there are several structures that show indication of oblique-like deformation with strike-slip displacements, throughout the studied area. A very important issue is the discussion of the hierarchy of the observed structures, both rift extensional structures, and the oblique-like ones.

Geologi Daerah Buyat Dan Sekitarnya, Kecamatan Kotabunan, Kabupaten Bolaang Mongondow Timur, Provinsi Sulawesi Utara

This research focuses on the eastern part of the northern arm of Sulawesi to understand the geological conditions, including geomorphology, lithology, stratigraphy, and geological structure. The goal is to determine the geological history and map the geological conditions to identify potential mineral resources. The research methods include a qualitative approach through field observations such as morphology, outcrop descriptions, lithology, geological structure measurements, stratigraphic relationships, as well as an inventory of natural resources and geological disaster risks. The quantitative approach involves calculations and analyses, including geomorphological analysis, petrography, paleontology, geological structure, stratigraphy, and the reconstruction of geological history. The research results identify four geomorphological units (karst, denudational, volcanic, alluvial) and six geological units at the research site. Andesite and volcanic breccia are the oldest units dating back to the Miocene. At the end of the Miocene, uplift and subsidence formed intrusive hills of diorite and limestone. Volcanic activity ceased in the Miocene. In the Pliocene, sandstone formed due to river transport. The rock formation process continues to the present, with alluvial deposit units resulting from the breakdown of rocks around the lake. Geological structure analysis reveals fault lines with the main stress direction from northwest to southeast. Relative fault data indicates fault inclination values suggesting the main stress direction is northwest-southeast. The geological history in the research area began in the Miocene with magmatism and tectonic activities, forming andesite and volcanic breccia units. This history extends to the formation of alluvial deposit units in the present. The research provides in-depth insights into the geological history and potential mineral resources in the region, serving as a foundation for further research.

Geological Structure Model for Recharge Area in Patuha Geothermal Field

Geothermal sustainability requires geological structure analysis using gravity methods for groundwater management. Geological structure analysis reviews fault data. Geological structure as a pathway for fluid movement for groundwater management in the research area, especially the Patuha Geothermal Field, West Java. This study uses global gravity model, terrestrial gravity, DEM, and geological data. The gravity method applied in this research involves calculations for latitude correction, free air correction, bouguer correction and terrain correction. The final results of this research are free air anomaly, complete Bouguer anomaly, and model evaluation (MRSE, MRE, and MAE). Free air anomaly results from free air correction of global gravity model data. DEM topography analyzes free air anomaly. The FAA data model evaluated RMSE at 1.27, MRE at 0.004, and MAE at 0.83. 138.02–280.26 mgal is the FAA range. The research area’s elevation range is 836–2431 m. Topography and free air anomaly correlate 0.75. Positive high connection. Mountains and plateaus may have positive gravity anomalies. Free air, bouguer, terrain, and CBA are applied to global gravity model data. The CBA model evaluation indicates quality. RMSE is 1.47, MRE is 0.012, and MAE is 1.11. CBA fluctuation implies fault spread. Faults serve as water flow conduits and channels, increasing the risk of infiltration. Meanwhile, cracks are being distributed as conduits and for infiltration. This research forms the basis for developing and increasing geothermal production so that further studies are needed regarding the influence of geological structures for reservoir in geothermal areas.

Geological studies and structural analysis of the Umm Anab metavolcanics and related quartz veins: implications for Pan-African volcanism in the Egyptian Nubian Shield

Geological studies and structural analysis of the Umm Anab metavolcanics and related quartz veins: implications for Pan-African volcanism in the Egyptian Nubian Shield

3D Digital Outcrop Model for Geological Structure Analysis in Mae Moh Coal Mine, Lampang Province, Thailand

3D Digital Outcrop Model for Geological Structure Analysis in Mae Moh Coal Mine, Lampang Province, Thailand

Depth‐based correlation analysis between the density of lineaments in the crystalline basement's weathered zones and groundwater occurrences within the Voltaian basin, Ghana

AbstractGeological structures have been shown by studies to have influence on the occurrence, storage and transportation of groundwater. Understanding the structural network of an area unearths a deep insight into the groundwater dynamics of the area. A geological structural analysis was carried out to reveal the geological structural network of Ghana's Voltaian basin. Using aeromagnetic data, structural density models were generated using the Center for Exploration Targeting grid analysis technique for two depth ranges (that is up to 100 m and 300 m) over the Voltaian basin. The total length of geological structures (lineaments) delineated at depths up to 100 m and 300 m were more than 5000 km and more than 8000 km, respectively. Given this, the study area was observed to be structurally dense at each of the aforementioned depths. The structural density models were discretized into five classes (very low, low, moderate, moderately high and very high regions), each of which was evaluated to determine their spatial association with known locations of groundwater occurrences within the study area using the frequency ratio technique. Frequency ratio results for both structural density models derived at 100 m and 300 m depths show the existence of a strong correlation between high structural density model classes and the known groundwater occurrences. The structural density models were further evaluated using the receiver operating characteristics curve. The area under the receiver operating characteristics curve scores indicates that, although both structural density models showed very good performance (with receiver operating characteristics scores greater than 0.7), the 300‐m depth structural density model performed better than the structural density model generated at a depth of 100 m (with their receiver operating characteristics scores being 0.721 and 0.715, respectively). The obtained results corroborate with literature assertion that groundwater occurrence within the Voltaian basin is mainly associated with structural features. It is expected that the outputs of this study would guide future groundwater exploration programmes within the study area.

Aquifer Potential Analysis Based On Hydrostratigraphy and Geological Lineament In Kokap Region, Kulon Progo, Yogyakarta, Indonesia

As a water-poor region, a study on the potential of water resources is urgently needed in the Kokap area, Kulon Progo. The purpose of this research is to carry out a hydrogeological survey to obtain an overview of water resources that can be approached from the groundwater aquifer potential. The method used is a hydrogeological survey in the field to determine the condition of morphology, rocks, geological structures, and hydrogeology; equipped with hydrostratigraphic analysis and geological lineament. The hydrostratigraphic analysis was made based on the interpretation of secondary data in the form of geoelectric, while the geological structure analysis was carried out based on the interpretation of DEM and Landsat imagery. The results showed that the Kokap area has hydrostratigraphy in the form of free aquifers 0 – 20 m thick and aquitards 0 – 8 m thick. Aquifug is at a depth of 4 - 20 m. With a lineament density of up to 808/km and supported by relatively intensive weathering, the Kokap area has the potential to have a fairly good groundwater aquifer configuration, with aquifer boundary types namely H1, H2, H4, H5 and V1, V2, V3.

Alpine structural evolution of the Internal Piedmont Zone in the Upper Viù Valley (Lanzo Valleys Ophiolite, Western Alps)

New structural data have been collected in the high-pressure meta-ophiolites exposed in the Lanzo Valleys (i.e., the Lanzo Valleys Ophiolite, LVO) and tectonically overlying the continental crust of the Dora-Maira and Gran Paradiso massifs in the Western Alps. Detailed geological mapping and structural analysis carried out in the south-western sector of the LVO (i.e., the Upper Viù Valley) allow to distinguish four ductile deformation phases, corresponding to the subduction-related D1 phase, the early exhumation-related D2-phase and the late exhumation-related D3 and D4 phases. The geometry of structures and kinematics have been reconstructed, and their regional tectonic meaning is discussed in the frame of the Alpine tectonic evolution of the Internal Piedmont Zone (i.e., the remnants of the Alpine Tethyan oceanic lithosphere) in the Western Alps.