Geologic Map Research Articles

Lateritization and enrichment of ferruginous protore during the peneplanation between uplifts – the case of Mekaneselam iron deposit, NW Ethiopian plateau

ABSTRACT Mekaneselam iron deposit is located in the NW Ethiopian Plateau. The area is constituted by limestone at the bottom followed by mudstone, sandstone and basalt at the top. Geological mapping, geochemical, mineralogical and stratigraphic investigations were conducted to explain the genesis of the deposit. The orebody is hosted by the quartz arenitic Upper Sandstone. At places where the sandstone is removed by erosion the orebody is unconformably overlain by basalt. It occurs as stratified bed and massive (the primary ore orebodies), and lateritic residual to reworked clastic varieties (the secondary/residual ore bodies). The dominant ore minerals are hematite and goethite with gangue minerals quartz and kaolinite. Geochemical composition is dominated by Fe2O3 and SiO2 with subordinate amount of Al2O3. The alkalis and alkaline earth elements were not detected in almost all samples. The stratigraphy, orebody morphology, mineralogy and geochemistry suggest that mineralization was a two-stage process. A primary ore deposition took place during sedimentation of the host sandstone and formed a ferruginous protore. This was later upgraded through deep tropical weathering and lateritization. The supergene process is believed to be facilitated by the relatively long-term peneplanation happened in Ethiopia after the Cretaceous and before the plume-induced Oligocene uplifts of East/Northeast Africa.

A New Geological Map of the Marginal Basins of Eastern Papua New Guinea: Implications for Crustal Accretion and Mineral Endowment at Arc–Continent Collisions

Abstract Accretion of island arc terranes is a fundamental process of crustal growth and the formation of new continents. Convergent margin tectonics, both compressional and extensional, in accretionary orogens also control the origin and distribution of their contained mineral resources, including many of the world’s important Cu and Au deposits. However, the details of crustal growth and accretion are often lost because of deformation and selective preservation during subduction. The Melanesian Borderland, which includes the offshore regions of eastern Papua New Guinea and the Solomon Islands, contains several active and relict arc and backarc systems that have formed in response to more than 50 Ma of subduction and complex plate tectonic adjustments. The composite terrane is a region of some of the fastest growing crust on Earth and also spectacular mineral endowment, including three of the top ten porphyry Cu and epithermal Au deposits in the world. However, more than 80% of the belt is submerged, and so little is known about its geological evolution and makeup. Here, we present the first detailed geological map of the region in one map sheet, including the marginal deep ocean basins. The map identifies and groups the key lithostratigraphic formations and correlates associated tectonic events across the belt. The final compilation is presented at 1:1,000,000 scale, which is sufficient to allow quantitative analysis of crustal growth and accretion during ocean–continent collision throughout the region. The map shows the diversity of assemblages in accreting terranes that may eventually become part of a growing continent and highlights their complex formation and structural relationships. Because so much of that history has occurred offshore, the new map presents the first complete picture of the geology of the region in the critical period leading up to its eventual incorporation in the Australian continent.

Near-Time Digital Mapping for Geoforensic Searches

Inadequate base maps with poor scale or low resolution demonstrate the need for contemporary topographic maps when conducting geological mapping. In neotectonic regimes and areas of dynamic geomorphology, archival or large-scale maps require time-consuming, on-site manual updating while mapping bedrock and superficial geology. In contrast, stable ground conditions may have suitable legacy maps in some locations but not in others, such as where surveying is absent, incomplete or subject to legal restrictions. The geologist tasked with mapping may have to do this on short notice at their first site visit with no time to search for or create digital or physical copies of background maps on a suitable scale. The field mapper may encounter any of the above scenarios, especially the Geoforensic specialist tasked with Search and Rescue, hazard assessment or preparation and desktop study for subsequent search teams or law enforcement. Drone-derived orthoimagery and digital surface modelling can be conducted on-site in near real time to provide high resolution georeferenced maps for direct input of geological information, thus bypassing either non-existent or unsuitable base maps.

Accurate Feature Extraction from Historical Geologic Maps Using Open-Set Segmentation and Detection

This study presents a novel AI method for extracting polygon and point features from historical geologic maps, representing a pivotal step for assessing the mineral resources needed for energy transition. Our innovative method involves using map units in the legends as prompts for one-shot segmentation and detection in geological feature extraction. The model, integrated with a human-in-the-loop system, enables geologists to refine results efficiently, combining the power of AI with expert oversight. Tested on geologic maps annotated by USGS and DARPA for the AI4CMA DARPA Challenge, our approach achieved a median F1 score of 0.91 for polygon feature segmentation and 0.73 for point feature detection when such features had abundant annotated data, outperforming current benchmarks. By efficiently and accurately digitizing historical geologic map, our method promises to provide crucial insights for responsible policymaking and effective resource management in the global energy transition.

Evidence for a Late Cretaceous to Paleogene basement-involved retroarc wedge in the southern U.S. Cordillera: A case study from the northern Chiricahua Mountains, Arizona

Late Cretaceous to Paleogene contractional deformation in the southern U.S. Cordillera is commonly attributed to the Laramide Orogeny, in part because of the prevalence of moderate- to high-angle, basement-involved reverse faults. However, it is unclear if the tectonic models developed for the archetypal Laramide foreland belt in the U.S. Rocky Mountain region are applicable to the southern U.S. Cordillera. New geologic mapping of the northern Chiricahua Mountains in southeast Arizona, USA, indicates the presence of an originally sub-horizontal thrust fault, the Fort Bowie fault, and a thin-skinned ramp-flat thrust system that is offset by a younger thrust fault, the Apache Pass fault, that carries basement rocks. Cross-cutting relationships and new geochronologic data indicate deformation on both faults occurred between 60 Ma and 35 Ma. A biotite 40Ar/39Ar plateau age of 48 Ma from the hanging wall of the basement-involved Apache Pass fault is interpreted to record erosion related to reverse fault movement and rock uplift. The presence of thrust faults in southeast Arizona raises the possibility of a latest Cretaceous−Eocene retroarc orogenic wedge that linked the Sevier and Mexican thrust belts to the north and south, respectively. Basement-involved deformation does not rule out the presence of a retroarc wedge, and many Cordilleran orogenic systems include basement-involved thrusting.

Geodynamic hazard assessment for the archaeological park-museum by the town of Nikopol

This study was conducted to establish the engineering geological and hydrogeological conditions of the site and to assess the geodynamic hazard in relation to the design and construction of the archaeological park-museum and feeder road in the town of Nikopol (Bulgaria). The studied terrain occupies a river terrace and the foot of a delluvial slope with an elevation of 23-68 m. The tasks of the study are to identify: the geological structure of the slope, the area and depth range of the landslides, the location of the slip surface, the physical and mechanical properties of the engineering geological strata, the hydrogeological conditions, the current stability of landslides, the change of slope stability under the action of various factors. The ground investigation includes analysis of archival and published information on the area; geodetic survey of the landslide; engineering geological mapping; exploratory boreholes; geophysical surveys using the VES method; testing of soil and water samples; compilation of longitudinal engineering geological profiles and slope stability analysis using the computational models. To the south of the study site the slope is affected by an ancient landslide with a volume of about 30 million m3 developed on the right valley slope of the Danube River in the section between the plateau and the river terrace. Consistent landslides occur in its lower part. Slope stability calculations show that the landslides are triggered by a rise in the groundwater level, an earthquake and undermining of the slope base. Rock-falls has developed on the steep rock slopes, composed of moderately to highly weathered and fractured cherty and glauconitic limestones. The size of the rockfall blocks is in the range 0.3-0.8 m3 and their transport distance reaches from 10 m to 50 m from the base of the slope. Stabilization measures and facilities are proposed to strengthen the landslides and rockfalls in the considered section of the slope. For the landslides it is proposed to implement a counterfort embankment on which to build the feeder road, drainage ribs and drainage ditches. For protection of the buildings from collapsing rock debris, an anchored high-strength net is recommended. The design takes into account the trajectory of the falling blocks and their kinetic energy. For monitoring the condition of the landslides and rockfalls, as well as for evaluating the effectiveness of the implemented strengthening, drainage and coastal protection structures, a control and measurement system for regime observation was built.

Geology: The Once and Future Crown Jewel of Science?

As a field geologist, I have been involved in the overwhelming excitement of three scientific revolutions—a mini revolution in structural geology, the impact-extinction revolution that freed geology from uncompromising uniformitarianism, and the plate tectonic revolution that turned the routine field of geology into one of the most exciting and essential sciences of the present time. I have also worked across several discipline boundaries, an activity I call scientific trespassing. My career has unfolded in such unexpected ways that, like anyone's life and like the history of our planet, it can only be seen as a most improbable journey. A focus on these three concepts and on the history of geology (a traditional name used here for all the Earth sciences) leads to the understanding that geology was once the crown jewel of sciences, and that after a century of necessary but routine geologic mapping, geology now needs to resume its crown jewel role because the understanding and care of our planet is becoming humanity's most urgent task.

Geological study of the seafloor applied to marine renewable energies

ABSTRACT This paper shows an example of how to create morphological and geological maps of the seabed combining high-resolution bathymetric data and onshore geological information. The mapped area corresponds to the BIMEP offshore test site, located in the south-eastern part of the Bay of Biscay, in the northern part of the Iberian Peninsula. In the Morphological map, using semi-automatic methods, the seafloor is categorized in 10 classes, obtained by the combination of terrain variables and a decision table. In the Geological map, onshore-defined geological units are extended into the continental shelf, and bedding traces, folds, and fractures are depicted. These maps could serve as valuable tools for stakeholders involved in marine energy projects, enabling informed decision-making and promoting sustainable development practices.

Geology of Tolstoj quadrangle (H08), Mercury

ABSTRACT Tolstoj quadrangle (H08) is located in the equatorial area of Mercury, between 22.5°N and 22.5°S and 144° and 216°E. Using the NASA/MESSENGER data, we compiled a geological map of the quadrangle at a scale of 1:3.000.000. The main basemap we used was the MDIS 166 m/pixel BDR mosaic. In addition, mosaics with high-incidence illumination from west and east, MDIS global color mosaics, and the MDIS global DEM have been taken into account. In the map, we considered three feature classes: geological units, lineaments, and surface features. Geological units consist of crater material and plains. Lineaments include crater and pit rims, and structures. Finally, surface features are subdivided into crater chains or clusters, hollows, faculae, bright and dark material. The geological map will be integrated into the global 1:3M geological map of Mercury, which is being prepared in support to the ESA/JAXA BepiColombo mission.

The Cretaceous of the Spanish Central System: a review of the lithostratigraphy, palaeontology and sequence stratigraphy, including new educational perspectives

The Southern part of the Spanish Central System is formed by both terrigenous and carbonate Cretaceous rocks that have been affected by intense dolomitization. They are part of the sediments deposited on the western margin of the Iberian Basin during the Cenomanian–Maastrichtian, the depositional architecture of which has been reconstructed through a detailed sequence stratigraphical study and analysis of its fossil record. It is formed by three large transgressive–regressive cycles in which the carbonate platform moves towards the West, while the terrigenous facies of its base decreases and the overlying clay facies, with gypsum, increases. The integration of sedimentological and palaeontological data and the identification of a set of parasequences has allowed the differentiation of 13 depositional sequences. This research has been essential to carry out modern geological mapping and provide society with a model that improves the economic geology and geotechnical exploration of these areas. Furthermore, this scientific progress has also impacted on the interest of society towards the geosciences and, especially, palaeontology. This has widened the scope for new research fields related to scientific outreach for the community and learning opportunities at different educational levels.

Geology of the Golobar and Rumaceo faults, Basque-Cantabrian Pyrenees

ABSTRACT The lateral transition between different styles of deformation is crucial for understanding local-scale structures since it influences orogenic reconstructions at the crustal scale. This is especially important at the westernmost Basque-Cantabrian Pyrenees, where the transition from the thin-skinned Basque-Cantabrian Pyrenees to the thick-skinned Cantabrian Mountains remains a subject of debate. To address this, detailed geological mapping and proper fault characterisation are critical. This research focused on the surface characterisation of the Golobar Fault System, one of the faults located at the transition between the two styles of deformation. The results of this study include not only a detailed geological map of the Golobar Fault System but also its integration with neighbouring seismic sections and well data. This approach enhances the understanding of the deeper portions and lateral thickness variations, thereby providing a more comprehensive understanding of the Golobar area within the regional framework.

Rockfall Mapping and Monitoring Across the Kalymnos Sport Rock Climbing Sites, Based on Ultra-High-Resolution Remote Sensing Data and Integrated Simulations

This manuscript presents a multidisciplinary study that proposes a methodology for delineating and categorizing vulnerability at rockfall risk areas to avoid human injuries and infrastructure damage caused by rockfalls. The presented workflow includes (i) classical geological mapping, (ii) the interpretation of high-resolution satellite data for observing the spatial distribution of fallen boulders, (iii) analytical hierarchy processing of spatial information within a Geographical Information System (GIS) platform, (iv) close-range remote sensing campaigns with Unmanned Aerial Systems (UASs), and (v) integrated simulation of rockfall events. This methodology was applied to Kalymnos Island, which belongs to the Dodecanese Islands complex of the southeastern Aegean Sea in Greece. It is characterized by unique geomorphological features, including extensive vertical limestone cliffs that span the island. These cliffs make it one of the world’s most densely concentrated areas for sport climbing. The results highlighted the areas that the local authorities need to focus on and suggested measures for increasing the safety of climbers and infrastructure.

Machine Learning Algorithms for Lithological Mapping Using Landsat 9 Data in Central Western Highlands of Yemen

This research designed the lithological units of the Central Western Highlands of Yemen (encompassing parts of Dhamar, Raymah, Sana’a, and northern Ibb) using Landsat 9 imagery. The area's complex geological features, characterized by units of the Yemen Volcanic Group from the Tertiary and Quaternary eras, Tertiary granite intrusions, and limestone, sandstone, metamorphic rocks, and Quaternary deposits, pose challenges for traditional field mapping techniques. By leveraging the spectral resolution of Landsat 9, this study aims to achieve accurate classification and mapping of lithological units. ENVI 5.6 software was used for image processing, applying a supervised classification approach represented by the two most common methods: Support Vector Machine (SVM) and Maximum Likelihood Classifier (MLC), based on training samples for each lithological class. The accuracy assessment of the classification was validated through an error matrix. The overall accuracy of SVM reached 85.3% with a Kappa coefficient of 0.8, while the overall accuracy of MLC reached 83.3% with a Kappa coefficient of 0.8, indicating a high degree of consistency and reliability in the classification process. This signifies a highly reliable classification outcome. The findings of this study highlight the significant advantages of utilizing Landsat 9 for detailed geological mapping of complex terrains, demonstrating a notable improvement in efficiency and accuracy over traditional methodologies. It can be relied upon to classify lithological units in other areas.

Enhancing Oil and Gas Exploration and Development: The Role of Remote Sensing

The oil and gas industry are getting weaker in terms of exploration and development; it demands a new generation of game-changing solutions as far as resource extraction is concerned with environmental footprints. Remote sensing technology has become an essential facilitator in this mission by giving detailed spatial data and information to support decisions. This article looks at the diverse ways in which remote sensing is used to contribute to oil and gas exploration, from geological mapping and resource assessment through environmental monitoring to regulatory compliance. Using satellite, airborne and geophysical data to identify the best drilling locations, conduct hydrocarbon potential assessment and monitor any environmental consequences is possible with modern technology its need for ground surveys and exploratory drilling. Remote sensing is also playing a key role in exploration activity and EOR by monitoring surface deformation. In the end, use of remote sensing does more than just make operations easier and lowers operational costs in the oil and gas industry and supports environmentally and risk mitigation. Keywords: Oil and Gas Exploration, Geological Mapping, Environmental Monitoring, Drilling Optimization, Remote sensing

Quantitative characterization of geomorphological and topographical features of debris-flow channels at the Alpe di Succiso mountain, Northern Apennines (Italy)

ABSTRACT This study combines the traditional method of geological and geomorphological mapping with a quantitative GIS analysis to examine landforms and debris flows channels. Using a high-resolution DEM (5 m) as a base, the geomorphological map highlights the various landforms around the Alpe di Succiso (Northern Apennines, Italy), including glacial and cryoclastic features, slope landforms and deposits due to gravity (particularly debris flow) and deposits due to running waters. The methodology applied to the channels is based on the geomorphometric parameters derived from the DEM, including Topographic Wetness Index (TWI), Terrain Ruggedness Index (TRI), Slope Angle, and Elevation extracted every 10 m along each channel and grouping the channels in four classes based on their lengths. Within each class, multiple ranking criteria were employed for the identification of channels showing anomalous or common patterns. Debris flow channels exhibit anomalous patterns in the geomorphometric parameters, indicating significant variations in their topographical characteristics..

The Cretaceous World (GSL SP544)

The Cretaceous System was first established by Jean Baptiste Julien d'Omalius d'Halloy based on his geological mapping of France and the adjacent areas of the Low Countries and Northern Italy. His map, which was published in 1822, has a legend with a rock unit identified as ‘ Terrain Crétacé ’ and that was the birth of the Cretaceous System that we still use today. Unlike many of the other geological systems, there was no definitive publication. The Cretaceous, as currently defined, occupies the interval of time from 145 Ma to 66 Ma, making it one of the longest in the Phanerozoic. The Cretaceous includes both icehouse and greenhouse (even hothouse) conditions and much of the time is characterised by exceptionally high sea levels.

Introduction to the Cretaceous System: Regional Studies (SP 545)

The Cretaceous System was first established by Jean Baptiste Julien d'Omalius d'Halloy based on his geological mapping of France and the adjacent areas of the Low Countries and Northern Italy. His map, which was published in 1822, has a legend with a rock unit identified as ‘ Terrain Crétacé ’ and that was the birth of the Cretaceous System that we still use today. Unlike many of the other geological systems, there was no definitive publication, only an account about the generation of the map. The Cretaceous, as currently defined, occupies the interval of time from 145 Ma to 66 Ma, making it one of the longest in the Phanerozoic. The Cretaceous includes both icehouse and greenhouse (even hothouse) conditions and much of the time is characterised by exceptionally high sea levels. These have provided us with widespread deposits of Cretaceous age, from the Arctic to the Antarctic, and all latitudes between. The range of sediments, both marine and terrestrial, is also a backdrop to a range of faunas and floras, some of which are widespread while others are endemic as a result of the Cretaceous dispersion of the continents.

Toward Smart Urban Management: Integrating Geographic Information Systems and Geology for Underground Bearing Capacity Prediction in Casablanca City, Morocco

To effectively manage the sustainable urban development of cities, it is crucial to quickly understand the geological and geotechnical attributes of the underground. Carrying out such studies entails significant investments and focused reconnaissance efforts, which might not align seamlessly with large-scale territorial planning initiatives within a city accommodating more than 3 million inhabitants, like Casablanca in Morocco. Additionally, various specific investigations have been conducted by municipal authorities in recent times. The primary aim of this study is to furnish city managers and planners with a tool for informed decision-making, enabling them to explore the geological and geotechnical properties of soil foundations using Geographic Information Systems (GISs) and geostatistics. This database, initially intended for utilization by developers and construction engineers, stands to economize a substantial amount of time and resources. During the urban planning of cities and prior to determining land usage (five- or seven-floor structures), comprehending the mechanical traits (bearing capacity, water levels, etc.) of the soil is crucial. To this end, geological and geotechnical maps, along with a collection of 100 surveys, were gathered and incorporated into a GIS system. These diverse data sources converged to reveal that the underlying composition of the surveyed area comprises silts, calcarenites, marls, graywackes, and siltstones. These formations are attributed to the Middle Cambrian and the Holocene epochs. The resultant geotechnical findings were integrated into the GIS and subjected to interpolation using ordinary kriging. This procedure yielded two distinct maps: one illustrating bearing capacity and the other depicting the substratum. The bearing capacity of the soil in the study zone is rated as moderate, fluctuating between two and four bars. The depth of the foundation remains relatively shallow, ranging from 0.8 m to 4.5 m. The outcomes are highly promising, affirming that the soil in Casablanca boasts commendable geotechnical attributes capable of enduring substantial loads and stresses. Consequently, redirecting future urban planning in the region toward vertical expansion seems judicious, safeguarding Casablanca’s remaining green spaces and the small agricultural belt. The results of this work help to better plan the urban development of the city of Casablanca in a smarter way, thus preserving space, agriculture, and the environment while promoting sustainability. In addition, the databases and maps created through this paper aim for a balanced financial management of city expenditures in urban planning.

Geological and mining mapping approach by coupling geological and geophysical field data: application to the Central Domain of the Mbere division (Adamawa-Cameroon)

This study is based on the coupling of geological field data with geophysical studies in the geological mapping of the Central Domain of the Mbere Division (Adamawa-Cameroon). The first step was to calculate the residual grid associated with the geophysical data that will be used for the mapping of the basement. The second step before mapping consisted in calculating the analytical signal associated with the residual grid, used to interpret the geological formations under cover or in intrusion. Subsequently, a geological mapping approach based on the categorisation of geophysical signatures into ranges using the Encom Discover program was adopted. This approach is based on the analysis of the relief of geophysical anomalies. The process of categorisation which is done iteratively, takes into consideration in the same georeferenced space, the resolution of the input data, the variation of the field considered and the structural model previously interpreted. The result of the categorisation is then compared to the spatial distribution of outcrop data to build the geological model. The application of this approach to the Central Domain of the Mbere Division led to the production of a synthetic geological map at a scale of 1/75,000. The superposition of this map to the topographic model allows to observe a concordance between the Cretaceous basins represented by their edge faults and the topographic depression zones. The various mineral indicators (primary and secondary) collected during the fieldwork, combined with the geological model (1:75,000 scale) as well as the Cretaceous deposits and vein intrusion models were used to create the mineral indicators and targets map for this sector. All these models can thus be used to underpin mineral exploration projects in the study area.

Development of a 3D Geologic Model Used in the Seismic Hazard and Liquefaction Hazard Analysis of Madison County, Tennessee

ABSTRACT Madison County of western Tennessee is approximately 100 km southeast of the New Madrid seismic zone and, thus, is subject to potentially dangerous seismic shaking and liquefaction events. Holocene floodplain alluvium and associated Pliocene/Pleistocene terraces of the Forked Deer and Hatchie Rivers cover a large part of Madison County. Underlying these unconsolidated sediments are approximately ∼650 m of poorly consolidated Paleogene and Cretaceous terrestrial and marine sediments, which are underlain by Paleozoic limestone bedrock. Uniform regional geology used in the 2014 United States Geological Survey seismic hazard maps assumes a homogenous seismic velocity structure above bedrock. Three-dimensional geologic mapping of the ∼700 m of Quaternary, Neogene, Paleogene, and Cretaceous sediments conducted in this study provides a more detailed velocity structure, resulting in a more accurate and detailed map of the expected ground motions in Madison County during future earthquakes. In addition, the surface geologic map reveals regions that are susceptible to liquefaction. This paper discusses the methods used to construct the surface geology map, subsurface structure contour maps, isopach maps, and 3D geologic model used in the seismic hazard and liquefaction hazard analyses of Madison County, Tennessee, and summaries of the results of these analyses are presented.