Structural Geological Data Research Articles

Study of the Digital Geological Compass in Increasing the Effectiveness and Efficiency of Measuring Geological Structure Data in the Field

This study compares the use of analog geological compasses and digital geological compasses in measuring fracture planes on crystalline rocks at the Lampung region. The measurement results demonstrate that using digital compasses yields higher time efficiency than analog compasses, with a reduction in measurement duration of over 50%. Although the dominant directions of the fracture planes were similar between the two methods, the inclination values and accuracies of each plane were not always consistent. Data processing using rose diagrams and stereonets indicates that the RockD application provides comparable results to measurements obtained using analog compasses. Therefore, the use of digital compass applications such as RockD can serve as an efficient alternative for geologists in collecting field data related to rock fractures, particularly in the context of quantitative data. However, analog geological compass is still recommended for measuring planes with on single-plane characteristics, such as rock bedding and fault mirrors. This study demonstrates the potential for development and transformation from analog geological compasses to digital geological compasses, and further research is needed to investigate the minimum number of fractures that can be measured with a digital geological compass to be considered statistically valid.

Кинематика разрывных нарушений Сахалина по геологическим и сейсмологическим данным

The paper presents a tectonic map of Sakhalin Island showing digitized faults derived from 1:1,000,000 scale tectonic maps and identified by geological surveys (detailed on 1:200,000 and 1:50,000 scale maps). The structural geological data on the kinematics of faults have been compared with seismological data on the earthquake focal mechanisms. A reasonable correspondence of these data has been obtained. The predominant kinematic type of faults is thrust/throw in the southern and northern parts of Sakhalin Island. In the central part of Sakhalin, a mixing of fault kinematic types is observed, mainly thrust faults with rare normal and strike-slip faults. Two uninformative zones have been identified with virtually no data on both structural geology and seismology. The earthquake focal mechanisms with a strike-slip component are dominant at their boundaries.

Quaternary-Active Faults and the Role of Inherited Structures in the Sacramento-San Joaquin Delta, Western Central Valley, Northern California

Seismic sources and their associated hazards within the Sacramento-San Joaquin Delta region of north-central California are relatively poorly characterized as compared to other, more heavily studied regions of northern California, such as the San Francisco Bay Area. Here we present a synthesis of subsurface, bedrock geology, and geodetic datasets from the Delta and from the Coast Ranges and Diablo Range to the northwest and southwest, respectively. We integrate these data and our own surface geologic and geomorphic observations to present a comprehensive review of faults in the Delta that exhibit Quaternary activity. Structural geologic data from the surrounding region highlight the significant influence that Late Cretaceous-to-Paleogene forearc structures exert on the geometry and kinematics of major Quaternary-active structures within the Delta. These inherited structures — including the Pittsburg-Kirby Hills Fault, Midland Fault, and Great Valley Fault System — exhibit a range of geometries and kinematics. Analysis of geomorphology along these structures suggests that these structures combine to accommodate Quaternary strain across the Delta region. A clearer understanding of subsurface geometries and structural relationships, built upon the regional tectonic history, provides insight into modern deformation accommodated on older structures and helps inform interpretations of seismic hazard within the Delta.

The deep structure of the Zagros mountain system according to Taylor approximation seismic tomography data

The seismic tomographic model obtained by the Taylor approximation method provides new constraints on the Earth’s crust and mantle structure beneath the Zagros mountain system at depths of 50—850 km. Based on structural geology and seismic tomography data, we divide the Zagros into Northwestern (Kirkuk, Lurestan, and Dezful regions) and Central (Kazerun and Fars regions) parts. The Central Zagros was formed due to subduction-collision tectonics, and the Northwestern Zagros was formed due to a collision-shear (transpression) tectonic process. Based on the 3D P-velocity model of the Zagros and its surrounding mantle, a high-velocity distal southeastern part of the Arabian Plate was established, subducting under the Central Zagros and the Iranian Plate, following the subduction of the Neotethys. This slab covers an area of 23—32°NL — 49—58°EL, i.e., the Bay of Bengal, the Central Zagros, and the southern part of the Iranian Plate. The maximum horizontal extent of the submerging part of the Arabian slab is 800—1100 km, and the maximum submersion depth is 450—500 km. A number of projections on the horizontal plane of the lines of intersection of the surface of the subducting Arabian Plate with horizontal sections of 50, 100, 200, 300, and 400 km were constructed. We obtained the direction of plate plunging, which in different areas varies from northern to northeastern 30—45°. In the Northwestern Zagros, according to the model, traces of subduction do not appear; however, right-lateral strike-slip deformations along the Main Recent Fault are visible and continue now in the crust. The difference in the types of deformation of the Northwestern and Central Zagros is most likely due to the features of the outlines of the eastern edge of the Arabian Plate and the complex nature of its movements. Analysis of earthquake mechanisms in 1977—2001 shows that the movement of the Arabian Plate could have occurred with frequent alternation in the S-N and N-E directions due to the alternation of spreading processes in the Gulf of Aden and the southeastern part of the Red Sea.

Construction of Exploration Data for Greenhouse Gas Geologic Storage: Focusing on Geological Cross-section Data

In this study, the most basic data, underground geological structure data, that is, geological cross-section data, were established to select a candidate site for underground storage of greenhouse gases based on AI. As a target area, the Gyeongsang Basin, where a large amount of sedimentary rocks are distributed, was selected as the greenhouse gas can be stored most effectively in sedimentary rocks. To this end, the acquisition and edit step, the refinement step, and the labeling step were carried out in the order of raw data collection, source data and labeling data construction to construct the geological cross-section data. This data can be downloaded through the AI hub site (https://aihub.or.kr/aihubdata/data/view.do?curr Menu=115&topMenu=100&aihubDataSe=realm&dataSetSn=71390) operated by the Korea Institute for Intelligent Information Society Promotion.

Structure and geodynamic evolution of the lithosphere below Northwest Indian Shield: Constraints from geological, geochronological and multi-scale potential field modelling

The Northwest Indian shield (NWIS) comprises of Archean cratons such as the Bundelkhand (Bh.C), Marwar (MC) and Dharwar (DC), the intervening Proterozoic mobile belts, the Aravalli Delhi Fold Belt (ADFB), Narmada-Son Lineament (NSL) and the Vindhyan basin (VB), the Mesozoic Cambay (CR) and Kutch rift basin (KB) basins and the Saurashtra Continental Block (SCB). The region is covered by thick traps of Deccan Volcanic Province (DVP) thereby masking the geological structures. In this study, we carry out a seismically constrained multi-scale geopotential field interpretation along two long corridors that cut across major Precambrian terrains of the NWIS. The models reveal the Moho varying between 30 and 45 km and LAB between 120 and 180 km. The derived crustal architecture shows that i) the ADFB and NSL are bounded by deep crustal faults having denser crustal rocks, ii) shallow Moho below DVP and CR, iii) presence of thick underplated layer at the base of lower crust in the entire region indicating a strong magmatic imprint. Correlation of modelled lithosphere structure with the structural geological and geochronological data across different terrains of the region suggests that the localized thickening of lithosphere below the ADFB and NSL could be the imprint of paleo-subduction during Proterozoic period, whereas, the thin lithosphere observed below NWIS as a whole represents lithosphere delamination caused by two major LIP events such as 800 Ma Malani and 65 Ma Deccan events. Hence, the proposed evolutionary models across the Precambrian terranes adequately explain the geopotential observations with linkages to present-day lithosphere below NWIS.

Active Collapse in the Central Betic Cordillera: Development of the Extensional System of the Granada Basin

The Betic Cordillera was formed by the collision between the Alboran Domain and the South Iberian paleomargin in the frame of the NW–SE convergent Eurasia–Nubia plate boundary. The central region is undergoing a heterogeneous extension that has not been adequately analysed. This comprehensive study addressed it by collecting structural geologic, seismologic, and geodetic data. The region west of the Sierra Nevada is deformed by the extensional system of the Granada Basin, which facilitates E–W to NE–SW extension. Moreover, the southern boundary of Sierra Nevada is affected by a remarkable N–S extension related to E–W normal to normal–dextral faults affecting the shallow crust. However, geologic and geodetic data suggest that the western and southwestern Granada Basin boundary constitutes a compressional front. These data lead to the proposal of an active extensional collapse from the uplifted Sierra Nevada region to the W–SW–S, over an extensional detachment. The collapse is determined by the uplift of the central Betics and the subsidence in the Alboran Basin due to an active subduction with rollback. Our results indicate that the central Betic Cordillera is a good example of ongoing extensional collapse in the general context of plate convergence, where crustal thickening and thinning simultaneously occur.

ANALYSIS AND QUANTITATIVE ASSESSMENT OF GEODIVERSITY AT KARYA MURNI, GORONTALO, INDONESIA

Karya Murni is one of the areas in the northern arm of Sulawesi that has been tectonically influenced. Tectonic processes have implications for the formation of rocks and geological features that have the potential to be developed into geodiversity sites. The development of geological features as a geodiversity site in aspiring geopark Gorontalo can protect valuable geological features from frequent degradation. This research aims to analyze and conduct quantitative assessments of geological diversity in Karya Murni, Gorontalo. The research method used is field observation, laboratory analysis, and geodiversity assessment. Field observations included observing landform, collecting rock samples, and measuring geological structures. Field observations were also carried out to observe aspects of the geodiversity assessment which included science, education, tourism, and risk degradation. Laboratory analysis consists of geomorphological analysis, petrographic analysis, and geological structure data analysis. Geodiversity assessment uses the Geological Survey Center of Indonesia assessment. The results suggest that the geomorphology of the study area can be divided into four geomorphic units - the volcanic hills, denudational hills, Karst hills, and fluvial plain units. The stratigraphy of the research area is divided into four units from the age of the early Eocene to the Holocene - the andesite lava, volcanic breccia, reef limestone, and alluvial deposit units. The geological structure of the study area is a trending northeast–southwest to northwest–southeast. Active faults at the location of the study area consist of the Apitalawu normal fault. At recent states, generally geosites of the Karya Murni have moderate scientific values, the low educational and touristic values and high risk of degradation. The geodiversity potential of the research area can be utilized for further research and education.

Mapping hydrothermal alterations and lineaments associated with epithermal and massive sulphides deposits of Tifraouine (northwest Algerian coast): Use of Landsat 8 OLI data and remote sensing

Within the context of studying mineralizations related to the Miocene volcanic rocks from the northern part of Algeria, Landsat 8 OLI data and remote sensing techniques are carried out to characterize and map hydrothermal alteration outcrops in the Miocene volcanic rocks of Tifraouine on the northwestern Algerian coast, where several indications of mineralization are known. Short-wave infrared (SWIR) bands allowed for the identification of clay alterations, while the visible and near-infrared bands help in the detection of iron alterations. Red-green-blue color combination images of 6/7, 4/2 and 5/6 ratios were produced. Principal component analysis (PCA) was computed to characterise altered zones and extract lineaments. Matched filtering technique (MF) allows direct detection after applying minimum noise fraction (MNF) transformation and pixel purity index to the spectra in order to obtain a distribution map of the target mineral species in studied area. The remote sensing results combined with the structural geological data determine a relationship between mineralization and structural features and show that hydrothermal alterations are clearly controlled by tectonic. They are highly concentrated in the calderas zone and extend towards the Bouzedjar area which allowed checking the map performed according to the field studies. This will contribute to preliminary studies related to mineral exploration and enhance the mining potential of Tifraouine. The acquisition of supplementary data would allow us to extend this study in coming works.

Geochemistry of granulite facies BIFs from the Luis Alves Craton (Southern Brazil): Implications for Archean-Paleoproterozoic depositional and tectonic settings

Banded Iron Formations (BIF) developed strongly during the Neoarchean – Paleoproterozoic Eras linked with global environmental processes such as the Great Oxidation Event (GOE) and changes in geodynamics, sea level, geobiology, hydrothermal systems, and sediment deposition conditions. BIF development and distribution worldwide are also related to supercontinent cycles, being a powerful tool to understand the evolution of plate tectonics. In this paper, we used field-based geological-structural data, petrography, X-ray diffraction, and lithogeochemical analyses to perform the first characterization of Banded Iron Formations at the Luis Alves Craton (LAC), Southern Brazil. The LAC BIF are classified as oxide and silicate facies, both with granoblastic texture. Oxide facies consists of quartz and magnetite. Besides these minerals, silicate facies contains olivine and ferrosilite, evidencing granulite metamorphism. Based on major elements oxide facies has a hydrothermal signature, with low content of Al2O3 and TiO2, whereas silicate facies register a continental sediment contribution been more enriched in these elements, MgO, MnO, and CaO. Trace-elements also indicate the main source for both silicate and oxide facies, which is seawater with a major influence of low-T hydrothermal sources, besides continental sedimentation sources. The Ce/Ce × anomaly is true negative, representing oxidizing waters, which also may represent a shallow water column depth. The depositional environment is inferred as a shallow, restricted basin. Oxide facies represents sedimentation closer to hydrothermal vents and with weak influence from continental clastic sedimentation, while silicate facies represent sedimentation closer to an adjoining continental landmass. Oxide facies has more Algoma-like characteristics, such as higher Fe and Eu contents, Sm/Yb and Eu/Sm typical of higher hydrothermal fluid inputs, and low siliciclastic contribution. On the other hand, silicate facies resembles Superior-type BIF, with higher siliciclastic contribution, negative Ce/Ce × anomalies, and Eu/Eu* <1.8. In summary, we propose the LAC BIF is representative of a transitional environment from Algoma-to Superior-type. The first depositions of the LAC BIFs may have developed within an Algoma-like environment during the Neoarchean. The waning tectonic and volcanic activity during the Siderian shifted to a platformal environment, with shallower waters that may induce the deposition of carbonates typical of Superior-type deposits. The depositional basin may have been closed by the Rhyacian and those sediments were then pushed down to the lower crust and underwent granulite facies metamorphism.

High-Resolution Mapping Using Digital Imagery of Unmanned Aerial Vehicle (UAV) at Quarry Area, Machang, Kelantan

Traditional structural and engineering geological survey data can only be acquired at the bottom of slopes or by climbing high rock walls in most quarries; these data frequently provide an incomplete picture of the area. UAV technology enables the safe study of difficult-to-access or hazardous locations. The key to future advancements in mining efficiency is the acquisition of high-precision, high-resolution 3D-positioned data. The goal of this research is to produce a high-resolution mapping from photographs captured by UAV. A DJI Mavic Pro 2 captured an image of a 0.131 km2 region of the Bukit Buloh Quarry Center. The final outputs in the forms of Orthomosaic and Digital Surface Model (DSM) were generated using Pix4Dmapper software. By comparing the coordinates of 6 Ground Control Points (GCPs) with coordinates determined using the RTK GPS method, the horizontal and vertical accuracies of the obtained UAV products were calculated. The vertical Root Mean Square Error (RMSE) for the geometric correctness of the data based on the 6 GCPs was 0.044 m. For large-scale maps, the resulting model met the American Society for Photogrammetry and Remote Sensing (ASPRS) accuracy standards. In a conclusion, UAV photogrammetry has evolved into a strong technology that can be used as a viable alternative to traditional mapping methods, particularly the use of expensive measurement equipment and labour. Besides its ability to analyze output data in qualitative or quantitative form, accurate mapping data is essential not only for 3D modelling but also for predicting geological risk in the quarry area.

Oblique collision and accretionary processes in the South Borborema Province: Insights from structural geology and geophysical data

During orogenesis, the forming structures vary according to several factors such as the nature of rocks, geological environment, P-T conditions, and type of collision. Deformational styles play a significant role in orogenic processes. While thin-skinned tectonics comprise only supracrustal deformation, in thick-skinned tectonics both supracrustal rocks and the basement are deformed reaching Moho depths. Both styles may coexist in a single orogenic system and the recognition of different sectors may help to unravel the nature of the orogen. In this paper, we apply the definition of tectonic styles to the São Miguel do Aleixo Shear Zone, a major transpressive shear zone in the Sergipano Belt, NE Brazil. It separates domains with different structural and metamorphic grades and provides evidence for understanding the tectonic implications of this structure and its role in the evolution of the orogen. We suggest that the São Miguel do Aleixo Shear Zone is a major crustal boundary formed during the oblique collision with and a possible transitional region between areas with dominant thin-skinned and thick-skinned tectonics. The presence of both tectonic styles together with metamorphic grade and geological environment lead to suggest that accretionary processes had a key role in the evolution of the Sergipano Belt.

Updated conceptual and numerical model of the Los Humeros Geothermal Field

The Los Humeros Geothermal Field is one of the five geothermal fields currently operating in Mexico. In this study, an updated conceptual model was developed considering studies of geology, hydrology, hydrogeology, structural geology, hydrogeochemistry, geophysics, temperature and pressure data from wells, as well as previous conceptual models. To explain the behavior of this geothermal field in greater detail, as many studies as possible were integrated into the conceptual model, which required building a 3D numerical model of fluid flow and heat transfer using the TOUGH3 simulator code. The numerical model has an area of 400 km2 and a thickness of 4 km, and it is composed of 64,000, each 500 m long × 500 m wide × 100 m high. In addition, ten rock types were included in the numerical model assigning different permeability values, from 4.00E-14 to 5.28E-17 m2. Model calibration was carried out considering downhole temperature profile data from 38 wells. The obtained modeling temperatures achieved a global Root Mean Square Error (RMSE) of 35.81 °C, while for specific wells from 16.14 to 60.39 °C. The numerical model was validated under transient-state conditions during production history, using bottom pressure data of wells H-1 and H-1D from 1982 to 2006, reaching an RMSE pressure of 4.43 bar, corresponding to 3.05% of the maximum pressure. The conceptual model update developed improves previous numerical models of Los Humeros because it allows considering registered variations of bottom pressure over the almost entire exploitation history. This updated conceptual model will help locate new exploration wells and define extraction policies.

Analisis Tipe Longsoran Daerah Pohe Kota Gorontalo Berdasarkan Orientasi Struktur Geologi

Administratively, the research area is located in Pohe Village, Hulonthalangi sub-district, Gorontalo City, Gorontalo Province. Astronomically, the research area is at coordinates 00030'16.10"- 00030'41.58" north latitude and 12302'36.10"- 12303'19.55" east longitude. The purpose of this study was to analyze the type of landslide based on the orientation of the geological structure of the Pohe area and the type of landslide based on the orientation of the geological structure of the Pohe area. The method used in this research is retrieval of field data, namely lithological data, geological structure data and slope data of the research area, then structural data processing using dips 6.0 software application and analyzed using stereographic projections. Based on the results of identification and stereographic analysis, it shows that in the research area there are 2 types of landslides, namely plane failure and toppling failure. The type of plane failure is found at stations 1.1, 1.2, 1.3, 1.4, and 1.6. While the type of landslide toppling failure is found at stations 1.5, 1.7, and 1.8.

Integrated interpretation: Defining risk corridors by combining 3-D seismic interpretation with induced seismicity hypocenters

Development of a resource play is subject to intrinsic risks. These may include the risk of incurring unexpected costs or shutdowns due to anomalous induced seismicity, or risks associated with reservoir stimulation that differs from prior empirical or numerical models. These two risks may be related causally, as completion effectiveness could be adversely affected by loss of fracture fluids into fault systems and/or damage zones, irrespective of the occurrence of induced seismicity. We outline a novel strategy for pre-operational risk assessment that is guided by the interpretation of 3-D seismic data, principles of structural geology and available induced seismicity data from surrounding operations. We integrate regional seismic structural mapping with results of previous experimental studies to develop a corridor-based risk-assessment approach. This approach is illustrated by a case study from the Duvernay play in Alberta, Canada, where subtle basement-rooted strike-slip faults and associated Riedel shears have been activated during previous hydraulic-fracturing completion programs. Unlike previous case studies in this area, we combine analysis of several adjoining 3-D seismic and induced seismicity datasets in order to map regional risk corridors. Given the general infeasibility of exhaustive detection and mapping of all potentially seismogenic faults, our approach relies on established structural principles, analog settings (flower structures) and analysis of fault-slip potential to quantify the probability of activation within a defined corridor that contains interpreted faults.

Precambrian fault reactivation revealed by structural and K-Ar geochronological data from the spent nuclear fuel repository in Olkiluoto, southwestern Finland

Integrated structural/geochronological studies help unraveling complex brittle deformation histories. We have analysed the structural geological database of brittle faults from the ONKALO™ underground facility for spent nuclear fuel in Olkiluoto in southwestern Finland. Based on the structural geological data from eleven representative fault zones, we classify the Olkiluoto brittle structural features into four fault systems, referred to as Fault system I to IV. The classification is based on their structural properties and tectonic history, crosscutting relationships, fault rock mineralogical characterization and 3D modelling. Some constraints on the timing of faulting are provided by K-Ar dates on synkinematic illite from fault gouge samples. Our results show that the bedrock in southwestern Finland experienced numerous brittle deformation phases between ca. 1.75 and 0.9 Ga. N-S strike-slip faults (Fault systems I and II) formed at mid-crustal levels ca. 1.79–1.75 Ga ago in response to NW-SE/NNW-SSE compression soon after the Svecofennian orogeny. Later E-W striking oblique dextral/normal faults (Fault system III) are tentatively associated with the Gothian orogeny 1.6 Ga ago. These three fault systems were reactivated during NE-SW compression ca. 1.3–1.2 Ga ago, coeval with intrusion of a regional swarm of olivine diabase sills. E-W compression at the onset of the Sveconorwegian orogeny ca. 1.1–1.0 Ga ago resulted in the formation of SE dipping low-angle thrust faults (Fault system IV) and the selective reactivation of fault system II and III. Overall E-W extension during the collapse of the Sveconorwegian orogen ca. 0.97–0.87 Ga ago caused the localised reactivation of fault systems III and IV. Our research approach, which is integral to the siting process of repositories for spent nuclear fuel, demonstrates that the basement in southwestern Finland experienced repeated reactivation since the Mesoproterozoic, suggesting that future deformation localization is likely to be also accommodated by reactivation of existing brittle structures rather than formation of new faults.

Bottom‐Up and Top‐Down Control on Hydrothermal Resources in the Great Basin: An Example From Gabbs Valley, Nevada

AbstractThe Great Basin in the western United States hosts various hydrothermal systems, including both active geothermal systems and ancient systems preserved as mineral deposits. New magnetotelluric and structural geologic data were collected in the Gabbs Valley area of western Nevada to demonstrate the advantage of imaging the full crustal column below known hydrothermal systems. Three‐dimensional models are developed and jointly interpreted where the key findings are bottom‐up and top‐down controls on hydrothermal systems. Bottom‐up control is dictated by weaknesses in the brittle‐ductile transition that allow hydrothermal fluids to propagate into the crust; these are often collocated with Miocene volcanic structures. Top‐down control is dominated by modern Walker Lane and Basin and Range tectonics that control fluid transport through the middle and upper crust. This study demonstrates that the characterization of regional mineral and geothermal resources is better informed by imaging lower crustal structures and preferential pathways to the surface.

Quaternary basaltic volcanic fields of the American Southwest

AbstractThe southwestern United States contains numerous monogenetic basaltic volcanoes distributed in intraplate volcanic fields. We review, on a regional scale, our current understanding of the Quaternary basalts with a focus on aspects pertinent to hazard assessment, such as physical volcanology and geochronology, while also summarizing the several petrogenetic conceptual models that have been proposed for the range of local tectonic settings in the region. We count 2229 volcanoes in 37 volcanic fields (including the Pinacate volcanic field, which is mostly in northern Sonora, Mexico). Volcanic landforms are dominantly scoria cones and ramparts with attendant lava fields that have a spectrum of ‘a'ā and blocky to pāhoehoe morphologies, while a small percentage of the volcanoes are maars and tuff cones. Explosive eruption styles that were driven mainly by magmatic volatiles, where they have been studied in detail, included Hawaiian, Strombolian, violent Strombolian, and sub-Plinian activity. The latter two have resulted in substantial fallout deposits that can be traced tens of kilometers from source vents. Phreatomagmatic styles have produced pyroclastic current (mainly pyroclastic surges), ballistic, and fallout deposits. These eruption styles pose hazards to humans when they occur in populated areas and to air travel and regional infrastructure even in sparsely populated areas. All but one of the major volcanic fields (fields that contain ∼100 or more Quaternary volcanoes) together form a northwest-southeast–trending band, which we suggest may reflect an influence of plate-boundary-related shearing on melt segregation in the upper mantle along with other factors; this view is consistent with recent global positioning system (GPS) and structural geologic data indicating the influence of dextral motion along the North America-Pacific plate boundary deep inside the Southwest. Of the 2229 Quaternary volcanoes identified, ∼548 (25%) have been dated, and only ∼15% have been dated with methods such as 40Ar/39Ar and cosmogenic surface exposure methods that are considered optimal for young basalts. Acknowledging the large uncertainty due to the poor geochronological data coverage, we use a simple Poisson model to provide a first-order estimate of recurrence rates of monogenetic volcanoes on the scale of the region as a whole; recurrence rates using our compiled age data set range from 3.74 × 10−4 yr−1 to 8.63 × 10−4 yr−1. These values are only based on dated and mapped volcanoes, respectively, and do not account for undated and buried volcanoes or other uncertainties in the volcano count. The time between monogenetic eruptions in the Southwest is similar to the repose times of some polygenetic volcanoes, which suggests that the regional hazard is potentially commensurate with the hazard from a reawakening stratovolcano such as those in the Cascade Range. Notable in our review is that only a few volcanoes have been the subject of physical volcanological characterization, interpretation, and detailed petrologic study that may elucidate factors such as magma generation, ascent (including time scales), and controls on eruption style.

Geochemical anomaly definition using multifractal modeling, validated by geological field observations: Siah Jangal area, SE Iran

Recognition of geochemical anomalies is a pivotal assignment in exploration projects. This study aims to delineate different AuCu geochemical anomalies using number-size (N-S) and concentration-area (C-A) multifractal models in the Siah Jangal area, SE Iran. In this research, lithogeochemical datasets were applied for the exploration of Au and Cu. A comparison between geochemical anomaly maps based on the N-S and C-A fractal models shows the N-S fractal modeling is a powerful tool for separation of weak elemental geochemical anomalies in all of sampling zones. Based on a comparison between the results of these two methods and field studies, the geochemical anomaly zones, defined by the N-S fractal model, are more accurate than those recognized by the C-A fractal model. The obtained results of the N-S and C-A fractal models have been interpreted with the extensive set of information including structural interpretation, geological and alteration data. Au and Cu mineralization in the Siah Jangal area are hosted mainly by Oligocene-Miocene sub-volcanic rocks, especially strongly altered porphyric quartz diorite, hornblende diorite and diorite. Moreover, the positive dependence between various alteration zones and high concentrations of Au and Cu proves that strongly anomalous areas are correlated with these alteration zones. High grade Au (> 1000 ppb) and Cu (>150 ppm) are associated with the altered sub-volcanic rocks in the northern, eastern, and SW parts of the study area. Therewith, the strong anomaly populations are mostly occurred within the fault and fracture systems in the study area. This is a promising signal because quartz-sulfide veins and veinlets are associated with such structures.

Port Heritage, Planning Challenges and the Role of GIS Tools in Multi Layered Cities

The aim of this study is to present arguments showing that on the port heritage area, underground cultural inventory should be considered from the historic landscape point of view within the framework of the conservation plans. This study focuses on the Yenikapi region, whose settlement history of the Historical Peninsula changed following the rescue excavation performed at the end of The Bosphorus Rail Tube Crossing Project (Marmaray). The area covering the Port of Theodosius, whose multi-layered urban formation started in the Neolithic period and which was one of the most significant grain trade ports in the Byzantine era, and the port heritage within the background of this area consist of important spatial formations. However, waterfront regeneration projects have disrupted the spatial continuity of cultural heritage under the effect of neoliberal policies. The methodology of the study, which involves the use of the Geographical Information System (GIS), is based on the overlapping of the archaeological surveys from the Istanbul Archaeology Museum, geological structure data from the Istanbul Metropolitan Municipality, and historical maps. The conservation planning approach in a metropolitan city like Istanbul, whose archaeological layers reflect the port heritage, should be developed by applying the concept of historic urban landscape.