Stratigraphic Column Research Articles

Identification of subsurface cavities in urban environment

Gravimetry is the most suitable geophysical method for identifying subsurface cavities in urban or industrial environments, as it is unaffected by nearby electromagnetic disturbances. In this study, we used gravimetric geophysical method to understand the land subsidence, collapses, and fissures observed around the sealed Albian drilling site located in the M’Rara region of Northeast of Algeria. Particularly, we would like study the geological observed phenomena and its potential association with the presence of a cavity within the salt layer. According to the stratigraphic column, a salt layer was located at 936 m depth. To better understand the subsurface conditions, A new gravimetric survey was conducted to image the density distribution and identify anomalous zones associated with subsurface cavities. Various gravity data processing techniques, including polynomial fitting of different orders, vertical and horizontal gradient analysis, and three-dimensional inversion, were applied. These methods aim to evaluate the relationship between detected gravity anomalies and the underlying structures, with a focus on their possible correlation with cavities within the salt layer. The gravimetric evidence suggest that the hydraulic drilling is not the cause of the observed phenomena. These cavities are likely formed by water circulation in the subsoil, originating from the Retem Valley.

Reconstructing deltaic palaeoenvironments in southern South America: phytoliths in Miocene estuarine sediments (Paraná Formation)

This study provides new insights into the palaeoenvironments that developed during the Late Miocene in Argentina and represents the first palaeobotanical record for the Paraná Formation at the Salto Ander Egg site. The analysis of the phytolith assemblages identified new morphotypes not previously documented in the literature for the sediments of this region. The importance of these discoveries lies in their potential taxonomic relevance to plant components associated with mangrove environments. The stratigraphic column in the study area is made up of the Paraná Formation (Late Miocene) and other Neogene and Quaternary geological formations. Samples of three sedimentary cycles were taken for the analysis of the phytoliths in levels with internal discontinuities and a high density of sub-vertical tubular biogenic structures and horizontal extensions. The morphotypes identified suggest the presence of species with pneumatophores, features typically found in intertidal mangrove forests. This study highlights the potential of phytolith analysis as a valuable tool for characterising deltaic palaeoenvironments. The phytolith assemblages from the Paraná Formation sediments provide important preliminary insights into a palaeoenvironment that possibly included mangrove forests and saline-adapted plant communities, existing in an ecosystem with freshwater availability within a saline environment, under a warm tropical to subtropical climate.

The new engineering and technological decisions for mine technical reclamation of deep open pits to regenerate mesorelief

The proposes new engineering and technological decisions concerning mine technical reclamation of land disturbed as a result of open pit mining. The authors paid attention to solving environmental problems of mining after-effects through formation of mesorelief. The problem is solved by means of the landscape regeneration: artificial development of objects based on the hypsometric features (hills and ravines), and structure (stratigraphic column of sedimentary rocks; aquifer) which were in nature before technogenic human intervention.Both engineering and technological decisions have been analyzed concerning trends, facilities, and implementation of the mine technical reclamation. Study of scientific sources, concerning land reclamation after activities by mining industry, has helped understand that the problem of terrain reclamation is almost ignored in Ukraine; however, significant negative impact is mentioned. Mining enterprises of Kryvyi Rih, where mine technical reclamation takes place, are exemplified.The current trends of artificial intelligence and robotic facilities use for open pit mining has been represented which prompted the development of a new generation of quarry equipment. A new design of a spreader launch ММD-2 on the basis of rotary caterpillar excavator for the ordered rock storing. Use of the spreader launch ММD-2 has been proposed for reclamation activities. Rock distribution schemes as well as throwing parameters during the launcher operation have been demonstrated. Optimum parameters to apply the launcher while rock throwing have been identified depending upon the rock fraction.Technological concepts have been developed concerning mine technical reclamation of deep open pits. Sequence of the deposit development has been proposed as well as the approach to regenerate the mesorelief. The engineering procedure of mine technical reclamation is divided into six main implementation stages. At the last stage, it is proposed to combine the mine technical reclamation technology with an approach of layer-by-layer mine technical and biological land reclamation using the spreader launch ММD-2.

Risk assessment of abnormal pressure zones with a focus on shallow gas pockets based on surface gas logging data and statistical relationships

The assessment of alterations in hydrocarbon components preserved in reservoirs is important for oil field management and drilling procedures. Drilling fluid analysis yields valuable insights into the reservoir fluid. This study focuses on identifying and quantifying shallow gas basins in the Azadegan oil field. Risk assessment of abnormal pressure zones with a focus on shallow gas pockets based on surface gas logging data and statistical relationships is also a key aspect of this research. Shifts in the C1 gas ratio to other gas components signify a notable peak in the Asmari Formation. Consistency among various wetness (Wh), balance (Bh), and character (Ch) indices suggests that the Aghajari and Gachsaran formations potentially harbor gas and contain some heavy or residual oil with limited production potential. However, the Asmari Formation shows the potential for natural gas production, while the Gurpi Formation has the potential for wet gas or condensate. Pixler parameters were computed and plotted to affirm the results of other parameters. The investigation of stratigraphic columns for component changes and lithology reveals that lithology plays a pivotal role in preserving valuable fluids. The upper section of the Aghajari Formation, primarily composed of shale-evaporite horizons, exhibits lower frequency compared to its lower part. The Gachsaran Formation displays an exceptional ability to preserve components in anhydrite sections. Although Asmari has a high accretion ratio, the Chilean calcareous sandstone horizons are more prominent in the upper part of the Gurpi Formation. The structural model includes humpback microstructures as controls for shallow gas pockets and component accumulation. Evaporite and shale layers significantly influence the movement of these components across different horizons. The 3D model illustrates migration from the Gurpi Formation to the Aghajari Formation, as both formations serve as sources due to the propagation paths leading to the Pabdeh and Gurpi Formations.

Rmacrostrat : An R package for accessing and retrieving data from the Macrostrat geological database

The geological record is a vast archive of information that provides the only empirical data about the evolution of the Earth. In recent years, concentrated efforts have been made to compile macrostratigraphic data into the online centralized database Macrostrat. Macrostrat is a global stratigraphic database containing information regarding surface and subsurface rock units and their respective ages, lithologies, geographic extents, and various other associated metadata. However, these raw data are currently directly accessible only through the Macrostrat application programming interface, which is a barrier to potential users that are less familiar with such services. This data accessibility hurdle currently prevents full capitalization of the value offered by Macrostrat, particularly its potential to improve understanding of the geological and biological evolution of the Earth. Here, we introduce rmacrostrat, an R package that interfaces with the Macrostrat database to access and retrieve a variety of geological, paleontological, and economic data directly into the R programming environment. In this article, we provide details about how the package can be installed, its implementation, and potential use cases. For the latter, we showcase how rmacrostrat can be used to visualize regional stratigraphic columns, produce regional geologic outcrop maps, and investigate temporal trends in macrostratigraphic units. We hope that this package will make geological data more readily accessible and in turn will facilitate new research utilizing Earth system data.

Metals, Volatiles, and Lithostratigraphy of Brothers Submarine Volcano

AbstractRelatively fresh volcanic rocks have been sampled by a remotely operated vehicle in situ from the NE caldera wall of Brothers submarine volcano, associated with Seafloor Massive Sulfide‐SMS deposits. Here, we present the first complete stratigraphic column of the NE caldera wall, comprising at least 12 massive dacitic lava flows, up to 80 m‐thick intercalated with multiple volcaniclastic layers associated with tuffaceous sediment layers. Detailed petrographic and geochemical analyses from hand specimen to crystal to silicate melt scale show chemical variability with depth, correlating partly with an increase in pervasive alteration due to volatile degassing. Moreover, while sulfide saturation occurred prior to volatile exsolution—which sequestrated most chalcophile elements as confirmed by the low metal contents of melt inclusions (e.g., Cu ≤ 1.3 μg/g and Au ≤ 7.0 μg/g)—silicate glass records a Cu enrichment and Au loss with differentiation, with interstitial glass accounting for Cu = 4.2 μg/g and Au = 6.6 μg/g and matrix glass for Cu = 6.0 μg/g and Au = 2.8 μg/g, respectively. Our findings suggest multiple sources for metals compensating for the low initial metal contents: (a) from hydrothermal fluids and volatile percolation ensuing interaction with the host rock and thus also replacement and/or dissolution of pre‐existing magmatic sulfides, (b) directly from the magma, consistent with metal release during magma degassing of metal‐ and Cl‐, and S‐ rich volatiles, and (c) from fluid circulation within unusually metal‐rich andesitic volcaniclastic layers (Cu = 40 μg/g, Au = 1.5 ng/g, and Pt = 0.99 ng/g). Our results elucidate the capacity of such hybrid mineralizing submarine volcanic systems to effectively scavenge, transport, and concentrate metals.

Basin modelling workflow applied to the screening of deep aquifers for potential CO 2 storage

The temporal and spatial scale of interest of CO 2 storage studies lies in between reservoir and basin models. While reservoir modelling software is best fitted to address some of the multiphysics issues related to the behaviour of CO 2 once injected into the subsurface (adsorption, dissolution, near injection wellbore mechanics and temperature, and, in some cases, fluid rock interaction) within a human timescale, basin modelling tools handle better the full basin volume and time-scale heterogeneities that impact the storage potential and risk associated with CO 2 injection. This study takes a basin modelling approach to provide an assessment of the influence of geological evolution on CO 2 storage capacity, both at the reservoir level, by helping to estimate the amount of CO 2 that can be stored in its connected porosity, and at the cap-rock level, by assessing the seal integrity. Our basin model also captures the evolution of the pressure plume induced by the CO 2 injection, taking into account the pressure and temperature fields, aquifer connectivity and permeability, and seal integrity, on a much shorter timescale than is usually considered by such a model. The results show the impact of basin evolution on aquifer properties and consequently on the dissipation of the induced pressure plume. They also highlight the large-scale influence of the CO 2 on the pressure field both vertically along the stratigraphic column, when the pressure plume reaches shallower aquifers through unconformities, and horizontally, when good aquifer injectivity and connectivity allows the pressure plume to dissipate widely.

The carbon release triggered by 1.32 Ga sill emplacement and its potential environmental implications

Magmatic activity is one of the important pathways for the delivery of deep Earth carbon to the surface. The massive carbon release in this process can have significant impacts on atmospheric-oceanic environment. Previous studies have done a lot of work on the relationship between Phanerozoic magmatic activity and carbon release, but there is relatively limited attention has been given to investigating the association between Precambrian magmatic activity and carbon release. The Yanliao Large Igneous Province at 1.32 Ga exhibits extensive development of sills, and the reaction between sills and surrounding rocks triggers the release of carbon. Simultaneously, the magmatic activity during this period is considered as the final response to the breakup of the Columbia supercontinent, coinciding with the occurrence of the Mesoproterozoic Oxygenation Event To explore the connection between this magmatic activity and global carbon cycling, environmental changes and planetary evolution, nine representative stratigraphic columns are selected from the Yanliao area. We use the SILLi 1.0 1D model by utilizing the one-dimensional finite element method (FEM) to simulate and estimate the amount of carbon release triggered by sill emplacement. The simulation results indicate that the emplacement of sills increased the surrounding rock temperature and vitrinite reflectance, leading to a decrease in the total organic carbon (TOC) content. A large amount of organic carbon and inorganic carbon was released, which was initiated by the reaction between sills and surrounding rocks, with a total carbon release up to 1.24 × 1013 tons. The estimated CO2 equivalent released during this magma activity episode is expected to be greater than 4.58 × 1013. In Mesoproterozoic strata, the emplacement of sills activates carbon within the lithosphere could have implications for the global environment. Further work needs to be done in other ancient cratons that possess Lower Riphean strata to find additional evidence of the impact of this magmatic event on the Earth system. From this study, it is evident that magmatic activity during the Precambrian period could promote the activation of carbon in crustal sediments and influence global environment, which can a reference for people to understand the planetary evolution process.

Combined onshore and offshore wide-scale seismic data acquisition and imaging for carbon capture and storage exploration in Havnsø, Denmark

Strong global actions for climate change include carbon capture and storage (CCS) as a feasible solution to reach carbon neutrality and raise opportunities for detailed subsurface investigations. An acquisition set-up designed for onshore-offshore zones was maximized for wide-scale high-resolution structural imaging and implemented to cover a domal structure of interest for CCS utilization close to the town of Havnsø (Denmark). The challenges of the combined acquisition and processing of land and marine multisensor data along a 42 km seismic profile are analyzed, the suggested solutions are applied, and the limitations are discussed. On the onshore side, a nodal array and a seismic landstreamer system were simultaneously used, whereas along the transition zone, a marine seismic streamer and ocean-bottom seismometers were added to record the seismic response generated by two seismic vibrator sources. The adopted sensing domains (velocity, acceleration, and pressure) were studied, and different processing steps were evaluated to enable their processing and subsequent data set merging. Results suggest, as the best approach, a separate prestack processing of the different data sets and the computation of new geometries and new surface-consistent residual static correction after their merging. The data acquired in the transition zone illuminate, for the first time, the subsurface geology of the region, delineating an expected domal closure. The final seismic section shows high continuity of the reflections with good resolution along the entire profile, identifying the main reservoir structure and the surrounding areas, which are important to ensure reservoir integrity and safe exploitation over longer time scales. Shallow and deep reflections are consistent with the stratigraphic column from a well log near the profile. The presented study shows a comprehensive workflow for processing such a multisensor data set in onshore and transition zone settings.

Frontier of the Paleo-Tethys Ocean in the western Mediterranean: Isotopic (Sm-Nd) constraints on sources of Devonian units from Menorca Island

The c. 1000-m-thick pre-orogenic Devonian mainly metapelitic sequence of North Menorca Island shows a fairly complete stratigraphic succession. The rocks of this sequence indicate gradually increasing deeper marine conditions of sedimentation towards its uppermost levels. Furthermore, the obtained sedimentary characteristics resemble those related to a deep and narrow basin-associated deposit. Thin sills of Ti-augite-bearing alkaline gabbros occur within the Devonian sequence. The intensity of Variscan deformation increases downwards through the structure. According to the characteristics of the Devonian sequence and its location within the Variscan Orogen, a correlation with similar units located in the southern sectors of the Central Iberian Zone (Iberian Massif) is suggested. The Devonian metapelitic rocks have geochemical characteristics suggesting that they represent moderately recycled mature siliciclastic sediments, generated from erosion of distant source areas belonging to an upper continental crust. The relatively narrow range of variation observed in initial 143Nd/144Nd ratios supports a similar source for the Menorcan slates (0.51165–0.51182). However, a marked trend is observed in these isotope ratios, from lower values at the base of the stratigraphic column (minimum value of 0.511941) to higher values at the top (maximum value of 0.512131). The 147Sm/144Nd ratios vary between 0.1074 and 0.1238, within the range defined for siliciclastic rocks with felsic crustal provenance. The Nd model ages define a narrow range between 1496 Ma and 1754 Ma (Late Paleoproterozoic–Early Mesoproterozoic), and they are consistently younger up-section. These data rule out a provenance from the erosion of the West Africa Craton, as they are more compatible with a provenance from regions located in the Trans-Saharan Belt or Sahara Metacraton. The characteristics of the Menorcan Devonian sequence are compatible with its deposition in a narrow and deep peri-Gondwanan transtensional basin, generated to the south of an advancing Variscan orogenic wedge. Systematic variations in the Nd isotopic composition indicate the progressive and continuous denudation of increasingly more easterly North African sectors in a collisional context between Laurussia and Gondwana with a marked dextral component. These data must be interpreted in the sense that there was not a large oceanic domain during Devonian times to the south of Iberia, able to block the arrival of detrital material from North Africa. A large tract of the Paleo-Tethys Ocean would therefore not have existed during the Devonian south of Iberia. This ocean must therefore have had limited extent in this period towards the westernmost sectors. The Devonian peri-Gondwanan shelf was apparently continuous around Iberia. This platform was progressively affected by Variscan deformation advancing from north to south and incorporated into the Variscan orogenic wedge with the same vergence.

Real-time prediction of formation lithology using drilling parameters: an example from Ca Tam oilfield

Construction of stratigraphic column is an important stage in minerals exploration and researching the historical development of geological processes. Besides, determining and identifying the boundaries of lithological layers also helps a lot in minimizing the risk of drilling complications and incidents as well as increasing efficiency in drilling. In this study, the authors focus mainly on applying machine learning algorithms to classify lithology and identify stratigraphy directly from the real-time drilling data of 02 wells in the Ca Tam oil field. The proposed model has high accuracy, this result demonstrates the great superiority and effectiveness of applying this method. The model using the Fuzzy c-means algorithm has predicted and identified relatively accurately the three main lithological groups in the study area: sandstone, claystone, and clay. The study's encouraging findings demonstrate the need for further focus and funding on this new strategy in the future to raise the effectiveness of oil and gas well drilling in Vietnam.

Enhanced heat flow assessment in Gulf of Hammamet and Pelagian Sea: Temperature corrections and conductivity adjustments

This study proposes new corrections of formation temperatures combined to correction of formation conductivities to reconstruct the heat flow map of the Gulf of Hammamet-Pelagian Sea, Eastern Tunisia. For that, a new linear Cross-Plot temperature correction approach, based on Bottom Hole Temperatures (BHT) and Drill Stem Temperatures (DST) of 63 drilled boreholes, was applied. In addition, and as temperature is transmitted from the substratum to the top of a stratigraphic column owing to the thermal conductivity, the latter was investigated according to a high appraisal of ±5 m and taking into account porosity variation with depth. The produced corrected thermal conductivity and geothermal gradient allowed to calculate the corrected heat flow in the Gulf of Hammamet – Pelagian Sea. Results show that the corrected geothermal gradient varies between 23 °C/Km and 58 °C/Km with a regional mean of about 39 °C/Km. The corrected heat flow rises from 49.5 to 119 mW/m2 with a regional mean of about 68 mW/m2. Variation of heat flow is dependent of the geodynamic evolution of the area where high heat flows follow folding structures and relatively low heat flows follow major trending faults. The major variations are E-W, N-S and NW-SE in direction following the major structural trends.

Pedogenesis of pelitic rocks of the Serra da Saudade Formation - Bambuí Group

ABSTRACT Serra da Saudade Formation corresponds to the upper part of the stratigraphic column of the Bambuí Group. Few studies have addressed the soil properties and pedogenesis of the pelitic rocks rich in potassium minerals of this formation. This study analyzed siltstone-derived soils, some of which are glauconitic (green siltstone; “verdete”), to understand the role of the main pedogenetic factors and processes in the landscape of the Central-West region of the Minas Gerais State, covered by Cerrado vegetation. Nine soil profiles were described, and their morphological, physical, chemical and mineralogical properties were analyzed. Soils were classified as Neossolos Litólicos (P1, P3, P6, P8 and P9), Cambissolos Háplicos (P2 and P5), Argissolo Vermelho-Amarelo (P4) and Argissolo Acinzentado (P7). The main active pedogenetic processes identified in the study area are melanization, goethization, argiluviation and elutriation. These are essentially controlled by the nature of the parent material and position of the soil in the relief. Soils are typically shallow, dystrophic, highly Al-saturated and contain essentially quartz and micas in the coarse fractions (sand and silt) and illite/glauconite and kaolinite in the clay fraction. In soil environments with siltstone and green siltstone under “dry forests”, the soil water pH was higher and high levels of exchangeable calcium and magnesium, a eutrophic character and high-activity clay were observed. Barium, chromium, lead and zinc contents were high in all studied soils. Green siltstone-derived soils have peculiar physical and chemical properties, divergent from those developed from other glauconitic rocks on the Earth surface. However, greenish tones in horizons are common in all these soils.

Integrated stratigraphical, hydrogeochemical, and geophysical studies to characterize the shallow groundwater aquifers in Wadi Araba area, western Gulf of Suez, Egypt

The construction of the New Galala City besides great mining (e.g., konoozmisr) and Seawater Reverse Osmosis Desalination Plant projects in the semiarid Gulf of Suez region of Egypt increases the demand for groundwater resources. So, the current research provides integrated stratigraphical, hydrogeochemical, and geophysical studies to investigate the shallow groundwater aquifers in Wadi Araba area on the western side of the Gulf of Suez. The stratigraphic column starts with pre-Cambrian basement rocks which are non-conformably overlain by sedimentary succession of Phanerozoic Erathem. A detailed land magnetic profile has been conducted and processed to estimate the aquifer’s geometrical parameters. This includes the subsurface spatial extension and thickness to delineate the prevailed subsurface structures in the study area. Lithostratigraphically, these aquifers are represented by the Paleozoic- lower Cretaceous siliciclastic-dominated sediments of the Nubia Group and fractured carbonate-dominated facies of the upper Cretaceous Galala Formation. Lithological characters, sedimentary facies (fluvial to shallow and open marine), microfacies types, and diagenesis processes (e.g., compaction, cementation, dissolution, and fracturing) are the main factors that affect the quality of the shallow aquifers in the study area. The main microfacies of the studied aquifers are quartz arenite, subarkose, sublitharenite, mudstone/wackestone, and packstone/grainstone. These facies are characterized by different primary and secondary porosities. According to the water sampling standard methods, nineteen groundwater samples were collected from the available hand-dug wells and springs from the Nubian sandstone aquifer and the Upper Cretaceous aquifer, respectively. Inductively coupled plasma–mass spectrometry (ICP–MS), titration, spectrophotometer and a flame photometer were used to obtain a complete chemical analysis. The results of hydrochemical analyses indicated that total dissolved solids (TDS) and concentrations of major ions as well in the lower Cretaceous aquifer increase toward the Gulf of Suez and in general higher than that of springs of the Upper Cretaceous Aquifer. The predominant factors influencing groundwater chemistry include seawater intrusion, evaporation, mineral alteration, dissolution of fossils, and ion exchange. Groundwater in the study area is unsuitable for drinking except in one sample and moderately suitable for irrigation with caution for higher salinity in samples located near the Gulf of Suez.

Palynological data from the hauterivian Avilé Member, Pampa Tril section, Agrio Formation, Neuquén Basin, Argentina

The present contribution provides data to the palynological characterization of the non-marine deposits of the Avilé Member, Agrio Formation (Pampa Tril and San Eduardo sections), Neuquén Basin, Argentina. The Avilé Member, which represent a low-order regressive event, is one of the most important hydrocarbon reservoirs in the subsurface of the eastern part of the basin. A continental palynological association mainly represented by gymnosperms with Classopollis as a dominant taxon was recorded. The findings of Shambeipollenites proxireticulatus in the unit, extend the biostratigraphical range of the species to the Hauterivian and suggest the Neuquén Basin as an important dispersal place for the species within Gondwana landmass during the Early Cretaceous. A conifer-dominated forest was indicated by the pollen assemblage. The high percentages of Classopollis, the presence of pollen with Gnetidae affinity (Weltwischia/Ephedra) added to the evidence of fluvial-aeolian interaction given by the lithology, may be indicative of a deposition in a dryland setting. The recovered palynoflora was compared to published palynological data from different units underlying and overlying the Avilé Member, in order to evaluate the response of the vegetation in the central part of the basin, during the onset of non-marine accumulation relative to a sea level fall and the subsequent flooding again of the basin. An important variation in abundance between two groups of conifers (Cheirolepidiaceae versus Araucariaceae) is observed throughout the Agrio Formation members. Going up in the stratigraphic column there is an evident increase in abundance of Araucariaceae and a decrease in Classopollis and ferns spores.

Radar Attenuation Characteristics of Low Reflectivity Zones in the Martian South Polar Layered Deposits

AbstractBoth sets of Martian polar layered deposits (PLDs) display semi‐rhythmic reflector stratigraphy in radargrams. The southern PLDs (SPLD), among other peculiarities, also contain widespread, distinctive deposits with few to no reflections that commonly occur at or near the top of the stratigraphic column. Here, we study the low reflectivity zones (LRZs) to determine whether they exhibit radar properties indicative of non‐water ice. We find that the previously reported CO2‐ice LRZ exhibits a distinct radar signature compared to all other LRZs. We also found behavior that suggests that the other LRZs may contribute to increased radar signal attenuation, which does not support a CO2 ice composition. We observe many instances of LRZs comprising the entire SPLD column and find that the radar attenuation varies across different LRZs, suggesting unique properties within each of these deposits. Variable radar attenuation of LRZs may be connected to differences in bulk compositions, radar‐sensitive roughness characteristics, and/or distributions of stratigraphic materials.

Evolución de las cuencas Tumaco, Atrato y San Juan sobre una plataforma continua a lo largo del margen pacífico colombiano

Several authors have interpreted the Colombian Pacific margin as a succession of oceanic terrane accretions, with generation of forearc basins under a compressive-transpressive tectonic regime during the Late Cretaceous-Miocene. New data acquired in the last decade, consisting of reprocessed seismic lines, geological cross-sections, stratigraphic data from wells, and new stratigraphic columns, are analyzed in this study. We suggest that the proposed models of successive terrane accretions are not supported by the new data; rather, the onshore basins were likely controlled by a marine platform from the Late Cretaceous to the Middle-Late Eocene, with reef growth to the end of this period. In the Late Cretaceous, contemporary to the sedimentation stage, effusive magmatism, mainly basaltic, also occurred. Since Oligocene time, the basins were affected by three different tectonic processes. First, during the Oligocene-Early Miocene, an extensional-transtensional event occurred in the Tumaco Basin and San Juan Sub-basin, which produced horst and graben structures and domino faults, along with the emplacement of igneous bodies in the eastern flank of the basins. The Atrato Sub-basin was affected by local reverse faulting towards its eastern edge. Second, during the Mid-Late Miocene, the western side of the Tumaco Basin was uplifted, and transpressive deformation occurred in the San Juan Sub-basin as evidenced by the San Juan and Garrapatas fault systems. Finally, in the Atrato Sub-basin, a transpressional regime is evidenced by the Baudó anticline. Our results suggest there is no evidence of oceanic terrane accretions in the abovementioned basins during the Late Cretaceous-Middle Eocene. Furthermore, we do not see evidence of a subduction system during that period. We conclude that subduction in western Colombia could have begun during the Early Oligocene instead.

Lipid biomarker profile of the Permian organic-rich shales (Irati Formation) in the northernmost of Parana Basin, Brazil.

The Irati Formation (Paraná Basin) is a mixed carbonate and organic-rich shale sequence intruded by Jurassic-Cretaceous basic rocks, featuring Brazil's most important oil shale deposits with different maturity levels. For the first time, the distribution of oil shale biomarkers from an outcrop section (quarry) of the Irati Formation in the northernmost Paraná Basin was analyzed by GC-MS and GC-MS/MS to determine the thermal evolution, organic matter origin and the depositional paleoenvironment. The organic-rich shale at the northernmost border of the basin has high similarity with the central and southernmost areas, indicating a primary control able to induce cyclic sedimentation in a broad (106 km2) and restricted environment. PCA and HCA analysis of bulk and molecular parameters showed changes in the organic matter composition and paleoenvironmental conditions throughout the stratigraphic column. Nonetheless, there are significant differences compared to the central-eastern and southern areas of the basin. Contrasting with the southern region, the north, predominates biphytane, low and medium gammacerane index. Pr/n-C17, Ph/n-C18, HI and OI values suggest type II/III kerogen from marine organic matter with freshwater input. Among the steranes, those of stereochemistry ααα 20R predominate over ααα 20S, and the presence of βTm indicates the shales are less thermally evolved.

Relation between Walash and Kolosh Formations and geology of their equivalent metamorphosed greywackes and arenites in Sulaimaniyah Governorate, Kurdistan Region, Northeast Iraq

The previous studies documented the tectonics setting, petrology, and geochemistry of the Penjween area (with Shalair Valley) before 70 years and considered it as an area of igneous rocks, and tectonically composed of three thrust sheets. According to these studies, the area includes two main igneous rock units: The Penjween Ophiolite Complex comprised of gabbro, peridotite, and granitoid intrusions at the south. The second unit is Kata Rash Volcanic rocks (Kata Rash conglomerate of the present study) which are located in the north and northeast and comprised of mafic, intermediate and felsic volcanic rocks. The present study disagrees with the previous documentation of these rocks and changed the claimed Kata Rash Volcanic Rocks and Penjween Ophiolite to metamorphosed conglomerates and coarse sandstones of the proximal facies that belong to metamorphosed sediments of Walash Formation (or Group) that was deposited in a large Paleocene Foreland Basin. The Walash Group and Kolosh Formation (as unmetamorphosed, coarse and fine sandstones or greywackes) were deposited as deep basin distal facies in the basin while Kata Rash Conglomerate belongs to coastal facies. All the above five units are deposited by turbidity currents during Paleocene-Eocene and they correlated, in the present study, stratigraphically along the basin paleodip from the present location of the Shalair valley to the south of Sulaymaniyah City. The Naopurdan Formation is recognized for the first time in the Penjween area and its facies and foraminifera are documented and correlated with Sinjar Formation. The above siliciclastic sediments were derived from volcanic source areas inside Iran and depending on the field, lab, and evaluations of the previous studies, the present study drew sedimentary stratigraphic columns and cross-sections for the Penjween and Sulaimanyiah areas and correlated their units along 100 km across the latter two areas. The correlation linked the Kolosh Formation with stratigraphic units of the Penjween area for the first-time supposing deposition during Paleocene-Eocene and sharing the same foreland basin which is aided by the first record of the occurrence of the Kolosh Formation in Chwarta by nannofossils and petrography.

About the spatial and chronological relationship between the Mousterian and Micoquian industries of East Europe

The geography of the Middle Paleolithic of East Europe (referring to the European part of the former USSR) shows two main peculiarities. The first is a very uneven (patchy) spatial distribution of sites which form dense local accumulations separated by vast empty spaces. The second is the nearly ubiquitous cooccurrence of the Mousterian and Micoquian industries. Both are present in all major accumulations from Transcarpathia in the west to the Volga-Don interfluve in the east, including also the Prut-Dniester region, the Donets-Azov basin, the Crimean Peninsula and the Northwestern Caucasus. The distribution areas of the two industries in East Europe not merely overlap but coincide (except the Northeastern Caucasus where only Mousterian assemblages are known by now). This pattern does not agree well with the opinion that these industries should be regarded as two independent cultural traditions, unless one assumes they were time-transgressive. In contradiction to some of the available absolute dates, the relative chronology of the Mousterian and Micoquian assemblages seems to corroborate such an assumption. The analyses of the published stratigraphies of the sites where both industries occur in one stratigraphic column shows that, as a rule, the Micoquian tends to overlay the Mousterian. Such a situation was observed at Kůlna (Czechia), Biśnik, Nietoperzowa, Ciemna, Zwierzyniec (Poland), Korolevo 1, Jezupol 1 (Ukraine), Ripiceni Izvor (Romania). The inverse sequence was found in Crimea, at Kabazi 2, Karabi Tamchin and, probably, Shaitan-Koba. Therefore, there are grounds to think that at least in some parts of east Central and west Eastern Europe the two technocomplexes succeeded one another.