Structure Of Sedimentary Basins Research Articles

2D Sedimentary structures at the southeast margin of the Tarim Basin, China, constrained by love wave ambient noise tomography

Summary Imaging the detailed structure of sedimentary basins is crucial for natural resource exploration and essential for better analysis and correction of sediment responses when studying deeper interior earth structures using seismic data. In the Tarim Basin, previous studies on the sedimentary structures are mostly obtained by active-source seismic surveys, which can provide high-resolution underground interface information but are highly costly or environmentally unfriendly. In this paper, ambient noise tomography, an efficient and economical method based on background vibration, is employed to construct the sedimentary velocity structure at the southeast margin of the Tarim Basin. Based on ambient noise data collected from a linear dense short-period seismic array, we extract Love wave signals from T-T component cross-correlation functions (CCFs) and measure Love wave dispersion curves at a period band of ∼0.3–11.5 s. Then, we utilize a one-step direct surface wave tomography method to image a fine 2D sedimentary shear wave velocity structure with a depth reaching 10 km. Our results reveal a clear layered sedimentary structure, the paleo Tadong uplift, and the thrust Cherchen fault. Our study provides reference sedimentary velocity models for the southeastern Tarim Basin, focusing on depths shallower than 10 km. This model is intended to serve as crucial input for studies requiring detailed shallow sedimentary velocity data. Moreover, our research demonstrates that the application of the ambient noise tomography method with dense arrays has great potential for enhancing resource exploration efforts in sedimentary basins.

An updated chronostratigraphic framework for the Cenozoic sediments of southeast margin of the Tibetan Plateau: Implications for regional tectonics

As one of the most important accommodation zones during the India-Asia collision, the southeast margin of the Tibetan Plateau (SEMTP) is characterized by many large-scale strike-slip faults, a regional low-relief relict that has been deeply incised by several continental scale rivers that originate from central Tibet, and numerous plant and vertebrate fossil biotas residing in Cenozoic sedimentary basins. Therefore, the SEMTP not only provides a meaningful constraint on the geodynamic evolution of the Tibetan Plateau, but also serves as an exemplar to understand the various interactions among surface uplift, drainage network reorganization, climate change, and biodiversity. Precise dating of Cenozoic sediments in the basins of the SEMTP is crucial for understanding these processes. Previously, the geochronologic framework of Cenozoic sediments in the SEMTP largely relied on fossils and regional stratigraphic correlations, which often involved circular reasoning and large uncertainties. In the past two decades, high-resolution magnetostratigraphy, detrital zircon geochronology, and isotopic dating of interbedded tephra layers have been carried out on SEMTP Cenozoic sedimentary basins in Yunnan and eastern Xizang provinces, SW China. Using these new data, we build a revised chronostratigraphic framework for Cenozoic sediments in SEMTP, and use this updated temporal framework to contextualize regional tectonics and climate change. The new chronostratigraphic framework shows that (1) many of the “Neogene” sedimentary basins based on plant fossils and regional lithostratigraphic correlation in the SEMTP were actually formed in the late Eocene and early Oligocene; (2) most of the Paleogene sedimentary successions in the SEMTP ended at the late Eocene-early Oligocene and were unconformably overlaid by Middle-Late Miocene sediments. Oligocene-Early Miocene sediments are often regionally absent. Sedimentary structures within the basin successions show that Paleogene basins were generally formed in compressional settings while the Late Miocene basins were mostly developed in extensional settings. The new chronostratigraphic framework, together with analyses of sedimentary basin structures, suggests that the SEMTP began to experience crustal shortening early in the India-Asia collision (∼50 Ma), producing Paleogene sedimentary basins and giving rise to the subsequent widespread surface uplift and regional erosion in the Oligocene-Middle Miocene. Tectonic inversion from compression to extension since the Middle Miocene precludes significant uplift of the SEMTP after this time, which may be related to geodynamic changes in the evolution of the Tibetan Plateau.

The 2023 US 50-State National Seismic Hazard Model: Overview and implications

The US National Seismic Hazard Model (NSHM) was updated in 2023 for all 50 states using new science on seismicity, fault ruptures, ground motions, and probabilistic techniques to produce a standard of practice for public policy and other engineering applications (defined for return periods greater than ∼475 or less than ∼10,000 years). Changes in 2023 time-independent seismic hazard (both increases and decreases compared to previous NSHMs) are substantial because the new model considers more data and updated earthquake rupture forecasts and ground-motion components. In developing the 2023 model, we tried to apply best available or applicable science based on advice of co-authors, more than 50 reviewers, and hundreds of hazard scientists and end-users, who attended public workshops and provided technical inputs. The hazard assessment incorporates new catalogs, declustering algorithms, gridded seismicity models, magnitude-scaling equations, fault-based structural and deformation models, multi-fault earthquake rupture forecast models, semi-empirical and simulation-based ground-motion models, and site amplification models conditioned on shear-wave velocities of the upper 30 m of soil and deeper sedimentary basin structures. Seismic hazard calculations yield hazard curves at hundreds of thousands of sites, ground-motion maps, uniform-hazard response spectra, and disaggregations developed for pseudo-spectral accelerations at 21 oscillator periods and two peak parameters, Modified Mercalli Intensity, and 8 site classes required by building codes and other public policy applications. Tests show the new model is consistent with past ShakeMap intensity observations. Sensitivity and uncertainty assessments ensure resulting ground motions are compatible with known hazard information and highlight the range and causes of variability in ground motions. We produce several impact products including building seismic design criteria, intensity maps, planning scenarios, and engineering risk assessments showing the potential physical and social impacts. These applications provide a basis for assessing, planning, and mitigating the effects of future earthquakes.

Understanding the Deep Structure of the Essaouira Basin Using Gravity Data: Hydrogeological Inferences for a Semiarid Region in Central-Western Morocco

The Essaouira Basin, located in central western Morocco, faces a significant threat of water shortage due to both the substantially reduced rainfall caused by climate change and the continuously increasing demand for this essential resource. Groundwater resources are being increasingly exploited to meet the needs of the population, whether for agricultural or domestic purposes. Therefore, it has become necessary to intensify investigations across the entire basin, particularly through indirect methods such as geophysical techniques, to accurately delineate the productive zones. In this context, the present study was undertaken to investigate the deep structure of this basin with the aim of comprehending the functioning of its aquifer system. This study is based on the interpretation of gravity data covering the Essaouira Basin. In addition to their qualitative analysis, these data underwent a methodological approach involving transformations to extract meaningful insights. The observed anomalies were interpreted in terms of (i) thickness variations within the slightly folded sedimentary series of the basin; (ii) Paleozoic basement topography; and (iii) the presence of salt deposits. In fact, among the negative anomalies, some coincide with evaporitic deposits that are known either from the geological outcrops or the seismic surveys carried out in the Essaouira Basin within the framework of petroleum exploration programs, while others coincide with areas of increased thickness of sedimentary sequences. The latter include synclines and basement depressions, where the accumulation of groundwater tends to occur; as a result, they constitute suitable zones for the drilling of water extraction wells. Groundwater flows observed in some existing wells are consistent with this hypothesis. The results of the contact analysis approach implemented within the framework of the study reveals the Essaouira Basin is affected by a fault network whose main direction is parallel to the Atlantic margin (i.e., NNE–SSW). This implies that the extensional tectonic phase responsible for initiating the rifting of the Central Atlantic in the Triassic era has primarily impacted the structural configuration of this basin. This study demonstrates the strong potential of the gravity method as a tool to delineate the deep structure of sedimentary basins and to identify potentially productive groundwater zones. The final results will provide important support to decision makers in sustainable groundwater management, especially in vulnerable areas.

Basin Structure for Earthquake Ground Motion Estimates in Urban Los Angeles Mapped with Nodal Receiver Functions

We constrained sedimentary basin structure using a nodal seismic array consisting of ten dense lines that overlie multiple basins in the northern Los Angeles area. The dense array consists of 758 seismic nodes, spaced ~250–300 m apart along linear transects, that recorded ground motions for 30–35 days. We applied the receiver function (RF) technique to 16 teleseismic events to investigate basin structure. Primary basin-converted phases were identified in the RFs. A shear wave velocity model produced in a separate study using the same dataset was incorporated to convert the basin time arrivals to depth. The deepest part of the San Bernardino basin was identified near the Loma Linda fault at a depth of 2.4 km. Basin depths identified at pierce points for separate events reveal lateral changes in basin depth across distances of ~2–3 km near individual stations. A significant change in basin depth was identified within a small distance of ~4 km near the San Jacinto fault. The San Gabriel basin exhibited the largest basin depths of all three basins, with a maximum depth of 4.2 km. The high lateral resolution from the dense array helped to reveal more continuous structures and reduce uncertainties in the RFs interpretation. We discovered a more complex basin structure than previously identified. Our findings show that the basins’ core areas are not the deepest, and significant changes in basin depth were observed near some faults, including the San Jacinto fault, Fontana fault, Red Hill fault and Indian Hill fault.

Lithosphere density structure of southeastern South America sedimentary basins from the analysis of residual gravity anomalies

We conduct a gravity study of the lithosphere beneath three large sedimentary basins in southeastern South America: Paraná, Chaco-Paraná, and Pantanal. We compile a massive gravity database and estimate the free-air and Bouguer gravity anomalies, resulting in a novel complete Bouguer anomaly map for the study area. To discern the influence of crustal loads with known lithologies, including sediments, basalts, and topography variations of the Moho discontinuity, we calculate their gravity effects and subsequently remove them from the complete Bouguer anomaly, leading to the development of our residual Bouguer anomaly map. This map highlights unknown anomalous masses within the lithosphere. To aid in the interpretation of these residual anomalies, we perform a 2D forward modeling. Based on our results, we propose new boundaries for the Paranapanema block and the Luiz Alves craton. Additionally, we propose that the Ponta Grossa swarm dike has a more substantial impact on the crust and lithosphere than previously considered, and delimit the region of influence of this magmatism in the lithosphere. Moreover, tectonic features such as the São Francisco paleocontinent and the Rio de La Plata craton appear to be associated with negative residual Bouguer anomaly regions. Furthermore, we identify and emphasize the significance of the Western Paraná Suture, which acts as a demarcation between the Paraná Basin region and the Pantanal and Chaco-Paraná basins. Remarkably, this suture appears to play a more important role in shaping the density structure of the southwest of South America than the age and tectonic history of the sedimentary basins.

L.V. Pustovalov and the Development of His Ideas on Oil and Gas Lithology

The article discusses the main directions of lithological research in the field of oil and gas geology, continuing and developing the ideas and research of L.V. Pustovalov. A number of such areas are closely coordinated with other branches of geology – tectonics, stratigraphy, etc. A wide range of such studies includes the analysis of the structure and development of sedimentary basins, the elucidation of the structure of the internal structure of sedimentary complexes, the forecast and search for non-structural traps of oil and gas, the study of natural reservoirs of oil and gas at different hierarchical levels.

The structure of sedimentary basins of Antarctica and a new three-layer sediment model

We use geophysical data together with a recent subglacial bedrock map (BEDMACHINE model) to obtain and investigate a new three-layer sediment model for Antarctica that locally improves the global sediment model. We provide a combined, continuous, sediment model for Antarctica and surrounding oceans by joining such improved continental sedimentary model with an existing global one (GlobSed). Our results reveal large differences between sedimentary basins for Antarctica due to their age and origin. The maximum thickness of sediments is reached under Filchner-Ronne Ice Shelf and off the Weddell Sea coast (10–12 km); further offshore, towards the ocean, the thickness of sediments drops to 4–5 km. We divide the sediment cover into three layers to distinguish material with different velocities. The lower sediment layer (deeper than 7 km) with high P-wave velocities (4.0–4.9 km/s) is found only for Lambert Rift and Filchner-Ronne basin. The middle layer (2–7 km) has large variations for different sedimentary basins: 3.5–3.7 km/s for Lambert Basin; 4.0–4.3 km/s for Ross, Byrd and Bentley basins; 3.3–4.0 km/s for Filchner-Ronne Basin. The upper sediment layer (0–2 km) has large velocity variations, from 2.0 km/s for Ross and Lambert basins (young sediments) to 4.7 km/s for Dronning Maud Land basins. We suggest that P-wave velocities larger than 4 km/s represent old, compacted sediments which belong to the Beacon Supergroup; about 3 km/s refer to Mesozoic (rifted?) sediments; and less than 3 km/s relate to young Cenozoic sediments. According to this criterion, Dronning Maud Land, Bentley and Byrd basins belong to the Beacon Supergroup, while more complex and thicker Ross, Lambert and Filchner-Ronne basins contain sediments from Beacon Supergroup in the middle or lower layer, respectively. Other sedimentary basins with more moderate velocities possibly belong to the East Antarctic Rift System which formed later during Gondwana breakup.

Estimation of the Sedimentary Basin Structure of the Southeastern Part of the Ishikari Lowland, Hokkaido, Inferred from Receiver Function

There is a very thick (>10 km) sedimentary basin in the Ishikari lowland, the central Hokkaido. This thick sedimentary basin affects strong ground motions observed from earthquakes, e.g., the 2018 Hokkaido Eastern Iburi Earthquake occurred in the southeastern part of the Ishikari lowland. Such a thick sedimentary basin structure is difficult to explore by using microtremor array or seismic reflection. This study investigated the sedimentary basin structures at 16 strong motion stations in the southeastern part of the Ishikari lowland by using the borehole-to-surface spectral ratio and the receiver function method based on the observed strong-motion records. First, at the KiK-net stations, the surface-to-borehole spectral ratio was obtained from observed strong-motion records. The S-wave velocity structure models between the surface and the borehole seismograph were estimated by fitting theoretical spectral ratios to the observed one. Next, the velocity structure models between the surface and the seismic bedrock were derived from the receiver function calculated from the observed records. We used the downhill simplex method to obtain the velocity structure model from the receiver function. The inverse analysis with three different initial models resulted in variations in the estimated velocity structure models. Synthetic velocity waveforms of the aftershock of the 2018 Eastern Iburi earthquake were calculated based on the estimated velocity structure models. The synthetic velocities (0.1-1 Hz) agree with the S waves of the observed records. The synthetic waveforms obtained from three models at each site were very similar. We compare the resulted velocity models with the microtremor array surveys carried out by previous studies. The fundamental mode phase velocities calculated from the velocity structure models obtained from the receiver functions correspond to the observed phase velocity from the microtremor array survey in higher (>0.4-0.8 Hz) frequencies. However, in lower frequencies (<0.4 Hz), the observed phase velocities at HKD184, IKRH03, and IBUH03 agree with the higher-mode phase velocities than the fundamental ones. This agreement suggests that the higher-mode Rayleigh waves dominate the observed phase velocities in the lower frequencies. The velocity structure models estimated from the receiver function analysis indicated that the low Vs (<1.1 km/s) layer deposited thickly in the western part of the Ishikari lowland and the middle Vs (1.1<Vs<2.7 km/s) layers were thick in the eastern part of the lowland. The depth of the estimated seismic bedrock was 12 km at HDKH04, located in the southeastern part of the lowland, which was the deepest between the study sites.

Advances in Deformable Plate Tectonic Models: 2. Reconstructing the Southern North Atlantic Back Through Time

AbstractThe offshore rifted margins of the North Atlantic have a spatially complex crustal structure comprised of variable crustal morphologies, continental blocks, and inherited structures. Recently, deformable plate tectonic models have permitted the interplay of plate kinematics and deformation to be assessed throughout the North Atlantic, and elsewhere. In particular, the ability to calculate temporal variations in crustal thickness has provided insight into the kinematic role of continental blocks and their interplay with large and micro‐tectonic plates during the formation of the North Atlantic offshore rifted margins. In this study, the deformable plate modeling workflow introduced in the companion contribution of this study (Part 1) is used to investigate previously published and newly presented deformable plate models of the Newfoundland, Irish, and West Iberian margins. This approach permits the deformation and subsequent crustal thickness evolution within previously recognized continental blocks and sedimentary basins throughout the southern North Atlantic Ocean to be visualized and assessed from 200 Ma to present day. The segmentation of early rift crustal thicknesses calculated by deformable plate models demonstrate strong correlations with the offshore extension of Appalachian and Caledonian terrane boundaries. Thus, our observations suggest that inherited orogenic boundaries potentially play a key role in the early rift crustal structure of sedimentary basins and the partitioning of deformation around and within continental blocks.

The Structure of Sedimentary Basins of Antarctica and a New Three-Layer Sediment Model

The Structure of Sedimentary Basins of Antarctica and a New Three-Layer Sediment Model

Sedimentary basins of the eastern Asia Arctic zone: new details on their structure revealed by decompensative gravity anomalies

Abstract. In the present study, the structure of sedimentary basins in the eastern Asia Arctic zone is analysed by employing the approach based on decompensative gravity anomalies. Two obtained models, differing in their initial conditions, provide thickness and density of sediments in the study area. They demonstrate essentially new details on the structure, shape, and density of the sedimentary basins. Significant changes in the sedimentary thickness and the depo-centre location have been found for the Anadyr Basin in its continental part. Also, new details on the sedimentary thickness distribution have been revealed for the central part of the Penzhin and Pustorets basins; for the latter, the new location of the depo-centre has been identified. The new model agrees well with the seismic data on the sedimentary thickness for the offshore part of the Chauna Basin confirming that the method is robust. The most significant lateral redistribution of the thickness has been found for the Lower Cretaceous coal-bearing strata in the northern part of the Zyryanka Basin, where the connection of two coal-bearing zones, which was not previously mapped, has been identified. Also, the new details on the sedimentary thickness distribution have been discovered for the Primorsk Basin. Therefore, the new results substantially improve our knowledge about the region, since previous geological and geophysical studies were unsystematic, sparse, and limited in depth. Thus, the implementation of the decompensative gravity anomalies approach provides a better understanding of the evolution of the sedimentary basins and the obtained results can be used for planning future detailed studies in the area.

3D hybrid imaging based on gravity migration and regularized focusing inversion to predict the Poyang Basin interface

Describing and understanding the basement relief of sedimentary basins is vital for oil and gas exploration. The traditional method to map an interface in each spatial direction is based on 3D modeling of gravity Bouguer anomalies with variable lateral and vertical density contrasts using a priori information derived from other types of geoscience data sets as constraints (e.g., well and/or seismic data). However, in the preexploration stage, vertical gravity [Formula: see text], which is sometimes the only available geophysical data, is typically used to recover smooth density contrast distributions under a generic set of constraints. Apparently, the use of the [Formula: see text] component is not sufficient to produce geologically reasonable interpretations with high resolution. To address this, we have developed a novel process of hybrid inversion, combining gravity migration and inversion using the same [Formula: see text] data set, to distinguish the complicated interface between basement and sedimentary basin rocks from a full-space inverted density distribution volume. First, a 3D-migrated model delineating the basic sedimentary basin structure is derived using a focusing gravity iterative migration method, where a priori information is not necessary. Subsequently, under the framework of the regularized focusing conjugate inversion algorithm, a high-resolution density contrast model is inverted for delineation of the basement boundary by integrating the 3D-migrated density model as a priori information. We examine the method using one synthetic example and a field data case, of which a transformed resolution density matrix is developed from logarithmic space to qualitatively evaluate the practical resolutions. The high resolution of the density distribution of the Cretaceous basement with a clear interface is achieved and verified by limited seismic data and strata markers in limited wells.

Grav3CH_inv: A GUI-based MATLAB code for estimating the 3-D basement depth structure of sedimentary basins with vertical and horizontal density variation

This study presents a software tool Grav3CH_inv developed to estimate the three-dimensional depth structure of sedimentary basins from their gravity data through an iterative process. The algorithm linked to the developed code operates recursively both in the wavenumber domain and in the space domain based on a triple method combination. The modelling strategy allows considerations of the model space with an exponential increase in density with depth and also with density variations in the horizontal direction. The accuracy of computation of gravity anomalies in the FFT-based forward procedure is also increased by using the shift-sampling technique which minimizes discretization effects during transformations between the space and wavenumber domains. Given the observed gravity anomalies and the density design of the basin, the iterative procedure performs automatically until the goodness of the fit between the observed and modeled anomaly, either the root-mean-square error or the largest error is below its pre-assigned value. As an advantage, the computing time is acceptably short for such a kind of an modelling problem. The GUI-enabled interactive control functions of the Grav3CH_inv code allow users to set optional settings, style of outputs and export formats, and facilitate operations without requiring coding expertise to perform the relevant procedures of the algorithm. The feasibility and accuracy of the proposed software is demonstrated by evaluating the synthetically produced gravity anomalies of various 3D basin models and also by analyzing an actual gravity data from the Los Angeles basin, California.

Extracting meaningful geological and structural features from 1D AEM inversions in conductive terrains

Airborne electromagnetic (AEM) survey data are typically inverted with one-dimensional (1D) AEM algorithms because 1D approaches are efficient methods for calculating subsurface conductivity and thickness variations. However, 1D AEM inversion algorithms are known to perform poorly in regions where the geology is 2D or 3D. In 2013, a regional-scale (5 km spaced) TEMPEST AEM survey was acquired across the regolith dominated sedimentary and volcano-sedimentary basin terrain of the Capricorn Orogen in Western Australia. In this contribution, we evaluate the efficacy of 1D inversions of this data to map the resistivity and thickness variations of the basin geology. The limitations of 1D inversions of the Capricorn Orogen AEM data were investigated through the synthetic forward modelling and inversion of two different geological examples: (1) the depth of detection and resolution of a (1 Ωm) conductor beneath conductive regolith, and (2) the geometry resolution of a dipping contact comparing both conductor-over-resistor and resistor-over-conductor scenarios. The main findings from this study are: (1) that 1D AEM inversions reliably resolve the depth of a conductor beneath conductive cover where it is located at approximately 100–150 m below cover, and (2) that dipping layers with a strike perpendicular to an AEM survey line can be accurately recovered when their apparent dip angle is less than 20°. These results are used to interpret the resistivity and thickness variations resolved along a 1D GA-LEI TEMPEST AEM inversion from the north-eastern Yerrida Basin of the Capricorn Orogen to show that there are limitations to the level of detail which can be interpreted from 1D AEM inversions, and that there are implications for interpreters using AEM methods to map sedimentary basin sequences and structure in deeply weathered terrains.

Structure and Density of Sedimentary Basins in the Southern Part of the East-European Platform and Surrounding Area

Modern satellite gravity missions and ground gravimetry provide operational data models that can be used in various studies in geology, tectonics, and climatology, etc. In the present study, sedimentary basins in the southern part of the East European Platform and adjoining areas including the Caucasus are studied by employing the approach based on decompensative gravity anomalies. The new model of sediments, implying their thickness and density, demonstrates several important features of the sedimentary cover, which were not or differently imaged by previous studies. We found a significant redistribution of the low-dense sediments in the Black Sea. Another principal feature is the increased thickness of relatively low-dense sediments in the Eastern Greater Caucasus. The deepest part of the South Caspian basin is shifted to the north, close to the Apsheron Trough. In its present position, it is almost joined with the Terek–Caspian depression, which depth is also increased. The thickness of sediments is significantly decreased in the eastern Pre-Caspian basin. Therefore, the new sedimentary cover model gives a more detailed description of its thickness and density, reveals new features and helps in better understanding of the evolution of the basins, providing a background for further detailed studies of the region.

Distribution and intensity of High-Temperature Low-Pressure metamorphism across the Pyrenean-Cantabrian belt: constraints on the thermal record of the pre-orogenic hyperextension rifting

Whereas a straightforward link between crustal thinning and geothermal gradients during rifting is now well established, the thermal structure of sedimentary basins within hyperextended domains remains poorly documented. For this purpose, we investigate the spatial distribution of rift-related High-Temperature Low-Pressure (HT/LP) metamorphism recorded in the preserved hyperextended rift basins inverted and integrated in the Pyrenean-Cantabrian belt. Based on Vitrinite Reflectance (Ro) data measured in 169 boreholes and more than 200 peak-metamorphic temperatures (Tmax) data obtained by Raman Spectroscopy of Carbonaceous Material (RSCM) added to ∼425 previously publishedTmaxdata, we propose a new map depicting the spatial distribution of the HT/LPmetamorphism of the Pyrenean-Cantabrian belt. We also provide three regional-scale geological cross-sections associated with RoandTmaxdata to constrain the distribution of paleo-isograds at depth. Based on these results, we show that the impact of rift-related metamorphism is restricted to the pre- and syn-rift sequence suggested by the depth profiles of Rovalues measured in different tectonostratigraphic intervals (pre-, syn- and post-rift and syn-convergence sediments). However, a small strip of early orogenic sediments (Santonian in age) appears also affected by high temperatures along the North Pyrenean Frontal Thrust and above the Grand Rieu ridge, which we attribute to the percolation of hot hydrothermal fluids sourced from the dehydration of underthrust basement and/or sedimentary rocks at depth during the early orogenic stage. The map shows that the HT/LPmetamorphism (reaching ∼500 °C) is recorded with similar intensity along the Pyrenean-Cantabrian belt from the west in the Basque-Cantabrian Basin to the east in the Boucheville and Bas-Agly basins, for similar burial and rift-related structural settings. This thermal peak is also recorded underneath the northern border of the Mauléon Basin (calibrated by wells). It suggests that the high temperatures were recorded at the basement-sediment interface underneath the most distal part of the hyperextended domain. At basin-scale, we observe in the Basque-Cantabrian, Mauléon-Arzacq and Tarascon rift segments an asymmetry of the thermal structure revealed by different horizontal thermal gradients, supporting an asymmetry of the former hyperextended rift system. Using our results, we compare the Pyrénées to the Alps that also recorded hyperextension but no HT/LPmetamorphic event and suggest that the high-temperature record within the basins depends on high sedimentation rate promoting a thermal blanketing effect and circulation of hydrothermal fluids.

Assessmemt of hydrocarbon potential of uplift structures in sedimentary basins from their geological history (Ateshgah structure in Baku Archipelago)

Assessmemt of hydrocarbon potential of uplift structures in sedimentary basins from their geological history (Ateshgah structure in Baku Archipelago)

Physical and Chemical Regularities of Water’s Composition Formation in Natural and Technogenic Geological Structures of Closed Coal Mines (“Water-Rock” Model Verification)

The physical and chemical modelling helped to establish the regularities of the groundwater’s composition formation in the areas of coal mines that are being abandoned. We demonstrated that the unusual features of the composition of the subsurface waters in natural and technogenic structures of Russia and Ukraine resulted from “water–rock–gas” system’s chemical processes. “Aluminosilicates–water” system consecutively produces solutions corresponding to the HCO3–Ca → HCO3–Na(Mg) → HCO3–SO4–Na(Mg) → SO4–Na(Mg) series of changes in composition, “limestone-water” system produces solutions corresponding to the HCO3–Ca → Cl–Ca series, “dolomite-water” system consecutively produces aqueous solutions of the HCO3–Mg → Cl–Mg series, and “rock salt-water” system produces acidic Cl– Na type waters. We proved that water composition of technogenic complexes is determined by the features of geological structure of sedimentary basins, relations between reaction water masses and rocks (W/R), O2 and Co2 closeness-openness of W/R system.

Sedimentary basement structure of the Southwest Sub-basin of the East Vietnam Sea by 3D direct gravity inversion

In this paper, we present a procedure based on Parker’s three-dimensional direct gravity inversion to determine the sedimentary basement depth rapidly and objectively. In the foregoing procedure, the Bouguer gravity anomaly is continued downward near the seabed before inversion, and the mean depth of the basement is constrained by the power density spectrum of the gravity anomaly. The bulk density of sediment and basalt rocks are also constrained by the logging data obtained from Expedition 349 Scientists (Expedition 349 Scientists, in: International Ocean Discovery Program Preliminary Report, 349, (2014). doi:10.14379/iodp.pr.349.2014). The sedimentary basement depth of the Southwest Sub-basin (SWSB) of the East Vietnam Sea (South China Sea) derived from the inversion of the downward continued Bouguer anomalies has more detail and accuracy than the sediment basement depth inverted from Bouguer anomaly at the sea level. The calculated basement depth and the sedimentary thickness in the SWSB vary from 4.0 to 6.5 km and from 0.5 to 2.0 km, respectively. The crustal thickness beneath the SWSB ranges from 4.0 to 7.5 km. Our model is consistent with sedimentary basin structure where spreading ridge valley is presented as the deepest points in the sedimentary basement and the terrain along the two banks of the valley is elevated. In addition, the SWSB is divided into four structure domains that are useful for the geodynamic and tectonic implications of the SWSB and surrounding area.