Petrology Of Rocks Research Articles

The effect of rock lithology on the background concentrations of trace elements in alluvial soils: Implications for environmental regulation

To assess the extent of soil contamination with a potentially toxic element, it is important to determine the background concentration of that element in the soil. In this study we decided to investigate the relationship between trace element concentrations in soils and the lithology of their parent rocks. We collected 85 topsoils (0–20 cm) samples from the Petorca, La Ligua, Aconcagua, and Casablanca River basins (Valparaiso region, central Chile). For soil sampling, we chose 11 tributary watersheds free of anthropogenic influence. The areas that contributed to the formation of each alluvial soil were delineated and the parent lithologies were acquired from 1:250,000 geological maps. The results show that the total concentrations of arsenic (As), copper (Cu), lead (Pb), and zinc (Zn) in soil vary considerably among the four river basins studied. Soil concentrations of all elements under study are positively correlated with the presence of andesitic volcanic rocks. Furthermore, soils formed from marine sediments and felsic volcanic rocks had the highest concentrations of Pb and As. The carbonate-bearing marine sediments may have adsorbed As and Pb released by weathering of felsic volcanic rocks found upstream of the study area. In contrast, lithologies dominated by continental sedimentary and plutonic rocks showed negative correlations with the concentrations of As, Cu, Pb, and Zn in the soil. Thus, the differences in soil element concentrations in the watersheds under study were due to the different rock types present in the area. We argue that absolute “one-limit-fits-all” background trace element values may be inadequate to assess the extent of soil contamination. Therefore, it is important to determine background concentrations of soil elements in each river basin in the anthropogenically impacted areas. In contrast, erroneous conclusions can be drawn when background concentrations are determined in one region and then applied in another region that is lithologically different.

Observation and Study of Lithospheric Magnetic Anomalies on Profile SD in Mongolia

To understand the deep tectonic environment at the origin of strong earthquakes along the northern section of the North-South seismic belt and the central continental block of Mongolia, large-scale gravity and geomagnetic surveys and rock sample collection were carried out along the Suhbaatar-Ulaanbaatar-Dalandzadgad profile in Mongolia. The spatial distribution characteristics of the lithospheric magnetic field at 160 geomagnetic measuring points along the profile were then systematically analyzed and summarized. Based on the composition of the lithospheric magnetic field from different sources at different depths combined with the regional geological structure and collected rock sample lithology, the lithospheric magnetic field was further decomposed into different components—the basement, middle layer, and shallow surface—by the upward continuation method. The results show that these components have obvious zoning characteristics and that the lithospheric magnetic field distribution of the Suhbaatar-Ulaanbaatar-Dalandzadgad profile is related to the geological structure, rock lithology, seismic activity, natural remanent magnetization, and magnetic susceptibility. Many destructive earthquakes have occurred in the area where the lithospheric magnetic field changes dramatically, the lithologies are dominantly igneous, and the magnetic susceptibility and natural remanent magnetization are high. In contrast, the lithologies in the area with moderate variation in the lithospheric magnetic field are mostly sedimentary, the magnetic susceptibility and natural remanent magnetization are low, and destructive earthquakes are rare. Since the lithospheric magnetic field reflects the magnetic characteristics of the rocks above the Curie interface, its spatial distribution not only corresponds to the geological structure but also predicts the depth and location of faults. Therefore, it is significant to carry out geomagnetic surveys and rock sampling to analyze the characteristics of geological structures and research regional seismicity.

Displacement/Length Scaling Relationships for Normal Faults; a Review, Critique, and Revised Compilation

The relationship between normal fault displacement (D) and length (L) varies due to numerous factors, including fault size, maturity, basin tectonic history, and host rock lithology. Understanding how fault D and L relate is useful, given related scaling laws are often used to help refine interpretations of often incomplete, subsurface datasets, which has implications for hydrocarbon and low-carbon energy applications. Here we provide a review of D/L scaling laws for normal faults, discuss factors that could influence these relationships, including both geological factors and errors in measurement, and provide a critique of previously published D/L databases. We then present our newly assembled database of 4059 normal faults from 66 sources that include explicit information on: 1) fault length and displacement, 2) host rock lithology, 3) host basin tectonic history, and 4) maturity, as well as fault D and L through time when these data are available. We find an overall scaling law of D = 0.3L0.92, which is similar to previously published scaling equations and that varies in response to the aforementioned geological factors. Our data show that small faults (<1 m length) tend to be over-displaced compared to larger faults, active faults tend to be under-displaced compared to inactive faults, and faults with stiffer host rock lithologies, like igneous and carbonate rocks, tend to be under-displaced with respect to faults within softer, more compliant host rocks, like clastic sedimentary rocks. Our dynamic D/L through time data show that faults follow the hybrid fault growth model, i.e., they initially lengthen, during which time they will appear under-displaced, before accumulating displacement. To the best of our knowledge, this is the first comprehensive, integrated, critical study of D/L scaling laws for normal faults and the factors influencing their growth. These revised relationships can now be utilized for predicting fault length or displacement when only one variable is available and provide the basis for general understanding D/L scaling laws in the context of normal fault growth. This underpinning database is open-access and is available for analysis and manipulation by the broader structural geology community.

Improved Unet in Lithology Identification of Coal Measure Strata

Abstract The lithology of underground formations can be determined using logging data, which is important for a variety of subsurface geoscience and industrial applications. Deep learning technology offers the advantage of discovering a potential relationship between input and output variables, making it a great choice for generating fast and cost-effective lithology classification models. To automatically characterize lithologies, a multiclass image segmentation problem is considered and an improved Unet as a solution is adopted. The model’s input data is two-dimensional images composed of rock feature data at different depths, and the outcome is a result of one-dimensional rock lithology classification. The algorithm’s practicality was tested using the logging data set from the Xinjing mining area in Shanxi Province, in north-central China, and an open-source data set of Canadian strata. Our model is tested against the 1D-convolutional neural network (CNN) and XGBoost algorithms using a good logging data set of the same depth and different depths for testing. The results show that the improved Unet method outperforms the 1D-CNN and XGBoost algorithms in the classification of rock lithologies. This algorithm has high application potential in the automatic interpretation of rock lithologies.

Tectonics and shore platform development: Rates and patterns of erosion on recently uplifted mudstone and limestone rocks at Kaikōura Peninsula, New Zealand

On tectonically active coasts, there is a dearth of erosion data documenting how rock coasts adjust (either fast or slow) in response to marine and subaerial processes immediately after coseismic uplift. Here we report erosion rates and evidence of reshaping of shore platform morphology at Kaikōura Peninsula, South Island, New Zealand, following the November 2016 Kaikōura 7.8 (Mw) earthquake, that uplifted platforms by ~1 m and extended their widths. High-resolution topographic data obtained from quarterly surveys over four years using a micro-erosion meter (MEM) and Structure-from-Motion Multi-View Stereo (SfM-MVS) surveys have provided rates of erosion and visual representation of surface morphologies. MEM data revealed variations in erosion, weathering and deposition rates across lithology, tidal positions, and platform elevation after the uplift. After four years, surface downwearing rates for all platforms were on average 2.25 mm/yr, a 104% increase from the pre-uplift rate of 1.10 mm/yr. Average lowering rates on limestone, hard, and soft mudstone platforms were 1.19 mm/yr, 2.31 mm/yr, and 3.21 mm/yr, respectively. Results show a change in patterns of erosion rates and faster rates on mudstone than limestone lithologies, but both faster when compared to pre-uplift rates. Previously reported seasonal trends in erosion rates have disappeared because post-uplift erosion rates are similar during the summer and winter. In contrast, statistically significant differences in lowering rates now exist across rock lithology and elevation. On one MEM site on the harder mudstone platform, a large increase from a pre-uplift erosion rate of 0.43 mm/yr to 19.23 mm/yr (1-year after uplift) and subsequent decline to 1.54 mm/yr after four years demonstrates the role of block detachment not previously seen in the MEM data from Kaikōura. For the first time, we complement MEM data with SfM-MVS-derived orthomosaics to provide evidence of changing rock morphology and processes such as granular disintegration, flaking and algal growth. Results from this study demonstrate how tectonism can fundamentally alter the way in which rock shore erosion rates are influenced by waves, tides, and weathering processes.

Prediction of the Height of Water Flowing Fractured Zone Based on the MPSO-BP Neural Network Model

The height of the water flowing fractured zone (HWFFZ) is the key parameter for safe coal mining under water bodies. In order to improve the accuracy of prediction model of the HWFFZ, the grey relational analysis (GRA) is used to quantitatively analyze the influencing factors of the HWFFZ, the main influencing factors of the HWFFZ under the condition of comprehensive mechanized mining and comprehensive top coal caving mining are selected scientifically, and these five factors that include mining depth, mining thickness, inclined length of working face, hard rock lithology proportion coefficient, and coal seam dip angle are selected as the discriminant indexes for predicting the HWFFZ. Nonlinear inertia weight adjustment, linear adjustments of local acceleration factor and global acceleration factor, and Gaussian mutation operation are introduced into particle swarm optimization (PSO) algorithm to improve the performance of PSO algorithm. The modified particle swarm optimization (MPSO) algorithm is used to optimize the initial weights and thresholds of back propagation (BP) neural network, and the prediction model of the HWFFZ based on MPSO-BP neural network algorithm is established according to the measured data. The prediction results are compared with those of PSO-BP neural network model and empirical formulas, the results show that the prediction accuracy of MPSO-BP neural network prediction model is higher than that of PSO-BP neural network prediction model and empirical formulas, and its prediction mean relative error (MRE) is smallest. The model also has good application effect and certain guiding significance for actual production.

Caves in clastic rocks (Muğla, SW Türkiye)

Caves evolution is controlled by lithological properties, discontinuities, water, climate, and physico-mechanical properties of soluble rocks, vegetation and human impact. This study investigates the cave formation in Upper Miocene-Pliocene clastic rock in Menteşe town of Muğla. The lithology, physico-mechanical properties and hydrogeologic factors of host rocks and morphology of the caves in Asar Hill and Damlam stream valley were examined. The caves are 1.47-9.71 m long, 2.24-19.36 m wide and 1.38-27 m high. Four joint sets and bedding planes affect the clastics in the Asar Hill area. Mudstones (low plasticity clay, sandy clay) are in soft-very soft rock, while conglomerate is in moderate-hard rock class. The mudstone removal has started the formation of the caves. The vegetation roots act as groundwater circulation paths in the Damlam stream area. Water has eroded mudstone and muddy matrix of conglomerate following cracks and led to the formation of the caves. Water infiltration may have led to stalactite, flowstone and travertine formation in Damlam stream caves. Possible cave collapse could threaten life and property in the Asar Hill area, and may cause the destruction of internal structures of the caves in the Damlam stream. Thus, precautionary measures such as continuous monitoring and protection must be taken in both cave areas.

Mapping the spatial distribution of fossil geothermal manifestations and assessment of geothermal potential of the Tangyin rift, Southeast of Taihang Mountain in China

The spatial prediction of geothermal sites along the southeast side of Taihang Mountain in the Tangyin rift is a critical goal in the development of renewable energy resources in cities such as Hebi in Henan province, which has significant potential for geothermal energy production due to the existence of deep faults and Cenozoic volcano. The study aimed to delineate areas with high geothermal manifestations for detailed geothermal exploration and well-test drilling. To define favorable zones for geothermal potentiality, multi-source datasets were chosen to generate evidence thematic layers that demonstrate the distribution of geothermal anomalies such as geologic maps, structural maps, Land Surface Temperature maps (LST), and hydrothermal mineral alterations maps. The remote sensing and Geographical Information System (GIS) approaches were integrated to map fossil geothermal manifestations and appraise the promising geothermal zones from Landsat 8 OLI/TIRS and Advanced Spaceborne Thermal Emission and Reflection Radiometer-Digital Elevation Model (ASTER-DEM) dataset using the Analytic Hierarchy Process (AHP), which is one of the Mult-criteria Decision Making methods. Results show LST values ranging from 22.6°C to 45.4°C, with the highest values found along the faults and volcanic areas. The hydrothermal alteration minerals discriminated from band ratios of 4/2, 6/5, and 6/7 for iron oxide, ferrous minerals, and clays reveal the presence of high amount of montmorillonite and illite minerals along the faults and volcanoes which are related to hot fluid circulation from subsurface. Structural analysis shows that the major structural trend follows the NNE Tangdong and Tangxi faults, with high density on the west side of the Tangxi fault where there is good exposure of outcrop but less fault density on the east side due to sedimentation in a low land which may conceal geological structures. Lastly, all the thematic layers of geothermal factors were reclassified, ranked, and integrated by the weight overlay logic model based on the influence of geothermal suitability to map potential areas for geothermal resources whereby 5 zones were obtained ranging from very poor to very good. The promising potential sites are mostly found along the highly deep structures of the major Tangxi fault crosscutting the permeable lithology of carbonate rocks and around the Hebi volcanoes. The distribution of hot springs and geothermal wells of the Hebi field were correlated and verified against the potential geothermal anomalies map. The overall integrated method proposes an advanced technique for designing the Tangyin rift’s exploration plan and development actions for geothermal resources utilization, which can be used for exploration of any unveiling geothermal potential sites.

New geophysical logging techniques for practical problem solving at complex hydrogenetic uranium deposits

In-situ uranium recovery features high economic efficiency and low environmental impact as compared with other uranium production techniques. The article presents the experimental results on the application of new geophysical logging methods at a uranium deposit of hydrogenetic type. Complex hydrogenetic uranium deposits have a nonuniform lithology, varied permeability and alternation of permeable and water-resistant rocks. The development of such deposits is often complicated by a number of factors affecting the production process. The common methods of geophysical research in wells provide insufficiently reliable information about the geological structure of interwell space. As a result, it is difficult to control and monitor the production process, which can lead to inefficient consumption of chemical reagents, undesirable leakage beyond the limits of production blocks, incomplete extraction of uranium reserves, etc. To solve the problem of insufficient studies of interwell space, the method of radiowave geointroscopy was tested. This method is based on the measurement of electrical resistance. The tests were carried out in two stages, during the periods of high-rate production. By comparing the measurement results in different dimensions, the electrical resistance maps were plotted. The interpretation of the measurement results made it possible to obtain reliable data on the actual distribution of solutions in the interwell space in a given period of time, to identify areas of excessive concentrations of solutions (stagnant zones), to assess acidification dynamics in production blocks, and to delineate potentially difficult areas of the blocks.

Evaluasi Kerentanan Akuifer Menggunakan Metode Simple Vertical Vulnerability Berdasarkan Hasil Penyelidikan Geolistrik (Studi Kasus di Desa Sumberpasir, Kecamatan Pakis, Kabupaten Malang)

There are indications of water pollution due to industrial waste, which can be seen from the rivers and springs condition in Sumberpasir Village. So it is necessary to investigate the vulnerability of the aquifer using SVV method. There are three parameters that must be calculated as the index value of the SVV method, thickness of the unsaturated zone, percolation value, and material type of the unsaturated zone. From the three parameter values, the SVV index will be obtained as an aquifer vulnerability assessment. The SVV index was mapped into the distribution of aquifer vulnerability using the Surfer program. The results of the study resulted in five types of rock lithology materials as a result of interpretation from geoelectrical investigations based on adjustments to actual conditions in the field. The layer with the lowest resistivity is clay, the second layer is tuff, the third layer is sandy tuff, the fourth layer is pumice, and the fifth layer is breccia. From the three parameters of the SVV calculation, the SVV index value is between 54 which is interpreted as having a moderate vulnerability until 76 with a very low vulnerability. So that Sumberpasir Village is considered likely to be safe against aquifer vulnerability. The distribution of vulnerability levels in the research location is divided into three, very low vulnerability (18.65% of the total area Sumberpasir Village), low vulnerability (60.03%), and medium vulnerability (21.32%).

Mechanical Properties of Different Lithological Rocks: A Case Study of the Coal Measure Strata in the Eastern Margin of Ordos Basin, China

In this paper, the mechanical behaviors of different lithological rocks of coal measure strata from Shanxi Formation in the eastern margin of the Ordos Basin, China, were investigated through uniaxial compression tests, and the deformation characteristics and failure modes of different lithological rocks were investigated. On this basis, the energy evolution of different lithology rocks was also discussed. The results show that there are obvious differences in the mechanical properties of different lithology rocks in coal measure strata, resulting in different wellbore instability prevention measures and fracturing measures in different lithology strata. Under the uniaxial compression condition, the peak strain of different lithological rocks is obviously different, and the denaturation characteristics are also obviously different, and the failure modes of rocks are mainly the tensile fracture mode, suggesting that the rock samples have strong brittle characteristics. With the increase of the strain, the total energy of different lithological rocks of the coal measure strata increases, and the elastic energy first increases and then decreases rapidly, whereas the dissipated energy first increases slowly and then increases rapidly. Each energy at the peak point is different, and the average total energy of shale, silty shale, siltstone, fine sandstone, and coal is 0.022 J/cm3, 0.045 J/cm3, 0.052 J/cm3, 0.042 J/cm3, and 0.003 J/cm3, respectively, indicating that there are obvious differences in the energy evolution laws of the different lithological rocks.

The Early Permian assembly of the Jiamusi Massif and Khanka Massif: Evidence from sediment sources

The Jiamusi‐Khanka Massif is an important tectonic unit of the Central Asian Orogenic Belt in North‐east China. Its Late Palaeozoic tectonic properties and the timing of assembly have restricted the understanding of the tectonic evolution process at the eastern segment of the Central Asian Orogenic Belt for a long time. Based on the study of clastic rock petrology and zircon U–Pb chronology of the Early Permian Erlongshan Formation in Mishan, it is clear that the zircon age of the Early Permian Erlongshan Formation in Mishan is mainly Late Palaeozoic, with a major age peak at 300 ± 3 Ma and secondary age peaks at 356 ± 7 Ma and 475 ± 10 Ma. The provenance mainly comes from the magmatic arc source area, and Early Palaeozoic (500–420 Ma) detrital zircons mainly come from the south‐east margin of Jiamusi Massif, Late Palaeozoic (400–270 Ma) detrital zircons mainly come from the eastern margin of Jiamusi Massif and the northern margin of Khanka Massif. Among them, detrital zircons of a special age group 330–310 Ma come from the north of Khanka Massif, while 490–470 Ma detrital zircons which are common in the Early‐Middle Permian strata of Khanka Massif come from Jiamusi Massif. Combined with the evidence of petrology and palaeontology, this paper believes that the Early Permian Jiamusi Massif and Khanka Massif should be a unified Massif, that is, Jiamusi‐Khanka Massif.

Chemical weathering intensity and geochemical characteristics of Cretaceous terrigenous clastic rock‐purple soil profiles in the Pushi area, Xichang

The Pushi area of South‐west China features a large area of purple soil that formed by the weathering of Cretaceous terrigenous clastic rocks. In this study, four vertical profiles of the purple soil (P1, P2, P3, and P4) derived from different pedogenic parent rocks were investigated. Specifically, the chemical weathering intensity and element migration, enrichment, and differentiation characteristics were analysed and the influencing factors of chemical weathering were explored. According to the discrimination map of major and trace elements and content characteristics of rare earth elements, the soil profiles are controlled by complex chemical weathering processes. Various geochemical parameters and indicators exhibited good correlation, and the chemical weathering intensity of the profiles followed the order P1 (mudstone) > P3 (silty mudstone) > P4 (argillaceous siltstone) > P2 (sandstone). The overall chemical weathering intensity of argillaceous rocks was slightly higher than that of sandstone, and the four profiles generally reflected medium to strong chemical weathering. The migration, enrichment, and differentiation characteristics of geochemical elements were found to be mainly affected by different chemical weathering intensities and stages, followed by leaching deposition. The chemical weathering characteristics varied for the four profiles with different pedogenic parent rocks, which could be mainly attributed to internal factors such as the lithology of the pedogenic parent rock and external topographic factors such as altitude.

Application of Geoelectrical Resisivity Method for Iron Sand Exploration in Ulakan Tapakis Padang Pariaman

There is no doubt about the presence of iron sand around the west coast of West Sumatra. Several studies have been carried out, but in Ulakan Tapakis area is still under observation, and no investigation of its potential and distribution. One of the methods that can provide models and subsurface descriptions is using goelectrical resistivity method. The geoelectrical application in Ulakan Tapakis was used Wenner-Schlumberger array into 4 section. The section was designed perpendicular to the beach with a length of 47 meters for short lines and 470 meters for long line, the distance between sections was about 65 meters. The results obtained in the form of pseudosection types. Each section describes the distribution and lithology of rocks below the surface. The combination of all sections gives an overview of the iron sand model at Ulakan Tapakis. From the model obtained the results of geoelectrical measurements with the Wenner-Schlumberger array, the distribution of iron sand can be found along the coast of the study area at a depth of 0.7 m - 3 m in short line and 40 m in long line with resistivity values ranging from 52 - 289 Ωm

The origin of a complex breccia body within the Upper Cretaceous/Early Eocene succession on Pag Island (Karst Dinarides, Croatia): karstic dissolution and collapse or dilational faulting and collapse origin?

A kilometre west of Pag Town on Pag Island, Croatia, within the Upper Cretaceous shallow-water carbonate succession, there is a large breccia body that has an irregular, quasi-circular shape and a subvertical-oblique position in relation to the bedding of the host rock. The breccia clasts and fragments consist almost entirely of the Upper Cretaceous host rock with only sporadic clasts of the Lower Eocene foraminiferal (alveolinid) limestones. In the brecciated body, there are three breccia types. 1) crackle breccia, 2) mosaic breccia, and 3) chaotic breccia. Based on the textural and structural characteristics of these types of breccia such as chaotic appearance and random fabric, very poorly sorted material, angular fragments, the composition reflecting only the host rock lithology, two genetic scenarios or concepts for the origin of Pag Town breccia body were considered, with observations supporting each of them. The first concept involves host rock dissolution resulting in a widened dissolution cavity into which wall and roof rocks progressively collapsed, and the second concept involves the collapse of voids produced by dilational fault displacement. A common prerequisite to both opposing scenarios is the existence of a subsurface cavity or void where the accumulation of rock clasts and fragments occurred. It is assumed that the timing of the cavity formation is related mainly to karstification during the Late Cretaceous-Early Eocene emersion phase or is related to dilational faulting during the Palaeogene Dinarides thrusting event.

Comprehensive Physical Properties and Exploration Potential of the Permian Igneous Rocks in the Southwestern Sichuan Basin

The Permian igneous rocks in the Sichuan Basin represent a major breakthrough, opening up a new prospect for oil and gas exploration, and igneous reservoirs have become a new field of oil and gas exploration. Gravity-magnetic-electric exploration is an effective means of identifying igneous rocks and helps in reducing the multiplicity of the prediction results. However, the lithology of igneous rocks is quite different, and the exploration theory and evaluation techniques need urgently to be improved. In order to deeply study the response characteristics of the gravity-magnetic-electric and physical properties of the Permian igneous rocks in the Sichuan Basin and their relationships with the reservoir parameters, physical property testing was carried out on outcrop samples of the Permian igneous rocks in southwestern Sichuan. The comprehensive physical properties of the samples with different lithologies, including basalt, tuff, and volcanic breccia, were analyzed and studied. Based on the geological characteristics of the igneous rocks, such as the mineral composition, microstructure, and reservoir properties, a multi-parameter intersection relationship model for the resistivity, polarizability, density, magnetic susceptibility, and their relationships with the reservoir parameters was established, and effective parameters favorable for igneous rock identification and reservoir evaluation were identified. The results of this study provide a physical basis and technical support for non-seismic exploration of igneous oil and gas reservoirs in the Sichuan Basin.

Controlling Effect of Wave-Dominated Delta Sedimentary Facies on Unconventional Reservoirs: A Case Study of Pinghu Tectonic Belt in Xihu Sag, East China Sea Basin

In order to find the “sweet spots” of unconventional oil and gas from the Pinghu Formation in the Pinghu Tectonic Belt, we are committed to clarifying the development and distribution rules of coal-measure source rocks and tight reservoirs as well as the controlling factors. Using 3D seismic and logging data, combined with logging constraints of target lithology and pyrolysis experiments of source rock, "source and reservoir" research of uncoventional oil and gas was carried out in the Pinghu Tectonic Belt. The results show that two stages of regression and one stage of transgression occurred in the Pinghu Formation, resulting in river-controlled and wave-controlled delta-neritic facies dominated by sedimentary facies, source rocks developed in interdistributary bay and swamp microfacies, and tight sandstones in point bar and distributary channel microfacies are developed. The accumulation of coalbed methane and shale gas is controlled by the sedimentary facies and the degree of thermal evolution under the factors of burial depth. The accumulation of tight sandstone is closely related to the dominantly sedimentary facies and diagenetic modification of physical properties and faults. It is concluded that the structural type, type and distribution of faults, and depositional environment of the Pinghu Tectonic Belt in the Xihu Sag are the key factors controlling the development and accumulation of coal-measure source rocks and tight sandstone reservoirs. This understanding provides a clear direction for the deep exploration of unconventional oil and gas in the sag and provides a reference for finding reservoir “sweet spots.”

Advances in Defining Ecosystem Functions of the Terrestrial Subsurface Biosphere.

The subsurface is one of the last remaining ‘uncharted territories’ of Earth and is now accepted as a biosphere in its own right, at least as critical to Earth systems as the surface biosphere. The terrestrial deep biosphere is connected through a thin veneer of Earth’s crust to the surface biosphere, and many subsurface biosphere ecosystems are impacted by surface topography, climate, and near surface groundwater movement and represent a transition zone (at least ephemerally). Delving below this transition zone, we can examine how microbial metabolic functions define a deep terrestrial subsurface. This review provides a survey of the most recent advances in discovering the functional and genomic diversity of the terrestrial subsurface biosphere, how microbes interact with minerals and obtain energy and carbon in the subsurface, and considers adaptations to the presented environmental extremes. We highlight the deepest subsurface studies in deep mines, deep laboratories, and boreholes in crystalline and altered host rock lithologies, with a focus on advances in understanding ecosystem functions in a holistic manner.

Geochemistry of onshore deposits from Rio del Rey sub-basin of the western Atlantic margin of Cameroon (Coastal basin, Southwest Cameroon): provenance and environments of sedimentation

The Rio del Rey sub-basin belonging to the Cretaceous–Cenozoic coastal basins of Cameroon is studied with geochemistry (major and trace elements) associated to mineralogy, palynology and petrography. One dominant facies (calcareous shales/siltstones/claystones) occurs in the Cretaceous series and two others (calcareous fine- to coarse-grained sandstones and calcareous claystones/shales in the Paleocene series. Ratios of LREE/HREE (9.27–24.23), Cr/Th (2.24–12.60), Th/Sc (0.54–6.10), Eu/Eu* (> 1 on PAAS normalized and ˂ 1 on Chondrite normalized), Al2O3/TiO2 (10.42–112.93) plotted in the Ce vs. La/Yb, Zr vs.TiO2 and La/Sc vs.Th/Co diagrams indicate that the sediments derivate from felsic rocks associated with subordinate intermediate composition to mafic igneous rocks. CIA (Chemical Index of Alteration, 61.69–92.76), PIA (Plagioclase to Index of Alteration; 62.16–99.47) and K2O/Na2O ratios (0.08–22.13) suggest that the source rocks have experienced low to high weathering (during the Paleocene), high chemical weathering (at the Campanian–Maastrichtian transition) and moderate to high chemical weathering (during the Cenomanian). The Zr/Sc vs. Th/Sc diagram of sample groups reveals that the Paleocene coarse-grained sediments have higher zircon content. Al/Si ratios, low in the coarse-grained (0.04–0.06) and high in the fine-grained (0.2–0.58) sediments, behavior of Al/Si vs. CIA and some elemental concentrations, such as Zr, Hf, Ca, K, and Na, suggest that the geochemical composition is controlled by grain sizes. The petrographic and X-ray diffraction results point early to mesodiagenesis effects and an important role of sea level change on the environments of sedimentation. These latter vary from marginal to shallow marine during the Cretaceous and fluctuated between shallow marine/lagoonal and brackish/littoral settings during the Paleocene according to facies analysis and palynology, with marine species such as Dinopterygium cladoides and continental species such as Classopollis sp. The SiO2 vs. Al2O3 + K2O + Na2O plot suggests that a predominant semi-arid to arid climate with periodically semi-humid periods was the rule during the Paleocene, The Arc-Rift-Collision, with two sets of high and low-silica rocks and SiO2 vs. K2O/Na2O diagrams, indicates a Collisional or Active Continental Margin tectonic as also recorded in the Cretaceous and Paleocene deposits in the Douala coastal sub-basin and in the Cretaceous Campo coastal sub-basin in Cameroon. These tectonic events could reflect the Precambrian basement history linked to the Neoproterozoic orogeny. The geological history of the Rio del Rey sub-basin is similar to those of Nigerian and Brazilian East costal basins, with local variations of the sea level changes on both sides of the Atlantic Ocean and the sediments distribution which is related to the source rock lithology.

Comparison of The Electrode Configuration of The Resistivity Geoelectric Method for Landslide Analysis on Highway Suban, Bandar Lampung

Jalan Raya Suban Bandar Lampung is located on the physiography of Bukit Barisan which is influenced by the movement of the Sumatran Fault, causing morphological conditions in the form of hills and steep slopes. This condition triggers the occurrence of disasters, one of which is landslides. In this study, the lithology of subsurface rocks and slides in the landslide-prone zone was examined using the Wenner-Schlumberger and Wenner-Alpha configuration geoelectrics. The Wenner-Schlumberger configuration has deeper penetration but lower resolution subsurface images, while the Wenner-Alpha configuration has less deep penetration but lower resolution surface images. The use of these two configurations is to take advantage of the advantages and reduce the disadvantages of each configuration in landslide analysis. The measurement results in the Wenner-Schlumberger and Wenner-Alpha configurations identified that the upper layer consists of weathered rock associated with clay tuff and sandy tuff with a resistivity of 1 m – 95.6 m, the second layer is clay sand from the Campang Formation with a resistivity value of 95.6 m – 250 m and the third layer is a mixture of breccia and igneous rock from the Tarahan Formation with a resistivity value of more than 250 m. The clay-sand layer was identified as the slip plane in the study area