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ABSTRACT Travertines are non‐marine sedimentary rocks, which are typically hydrothermal in origin and characterized by high depositional rates. Despite great advances in the understanding of the geomorphological, petrological and geochemical aspects of travertines, the recognition of these rocks in the geological record is not an easy task due to the multiple parameters involved in their formation, the variable potential of preservation and the lack of a facies model with application to the geological record. This study applies classic sedimentological and stratigraphic methods, looking for vertical and lateral facies distribution at the Vega Botijuela, Salar de Antofalla, Argentina. Travertines are geomorphologically compartmentalized into proximal, intermediate and distal zones, with spring waters in the proximal zone and mixed carbonate–siliciclastic sedimentation observed towards the distal zone. The presented data corroborate previous assumptions that these systems are dominantly progradational to aggradational. Vertical facies stacking is typically coarsening‐upward, with a dominance of carbonate mudstone interbedded with grainstone, rudstone and boundstone. Distinct facies associations are observed in the Vega Botijuela and are defined here as dome, fissure ridge, gently and steeply inclined slopes, stepped slope and terminal, according to morphological criteria applied elsewhere. Biotic and abiotic travertine precipitation occurs along the geomorphological zones and is related directly to different slope gradients. Throughout the depositional history of travertines, the carbonate facies occur interbedded with siliciclastic deposits from the Salar de Antofalla, generating local facies heterogeneity in the marginal areas of the basin. This is one of the first attempts to establish vertical stacking patterns to characterize facies associations, adding important insights towards the building of a travertine facies model. In this context, these findings can be applied to recognize travertines of the geological record developed in extensional sedimentary basin margins under arid climatic conditions. [ABSTRACT FROM AUTHOR]

The Zagros Fold and Thrust Belt (ZFB) in southwestern Iran emerges as a geological marvel, defined by series of compact anticlines and synclines that the NW–SE trending structures of the Zagros belt. This unique configuration designates the ZFB as the dynamic boundary of the Arabian platform, shaped by the forces of nature. Over time, sedimentation in the expansive basin led to a gradual transformation, with folds originally oriented differently nowfolds axial line inclining southwestward, revealing a progressive shift in fold axial planes. This article presents a pioneering tectono-stratigraphic examination of Miocene Formations in the Fars and Bandar Abbas Hinterland, Southern Iran. The study meticulously explores five locations—Bastak, Taghdis-e Bahar, Dasht-e Arzhan, Saedi Mountain, and Yasuj—analyzing stratigraphic sections of the Miocene Formation. The Isopach map exposes variations in Miocene Formation thicknesses across these sites. In the Arjan plain, significant facies change unfolds, transitioning from Gachsaran Formation's evaporitic sedimentary rocks to Rzak Formation's marine sedimentary rocks and Asmari Formation's calcareous rocks along a northwest–southwest border. These facies change correlates intricately with subtle movements of fault zones—Kareh–Bas, Sabzpooshan, Sarvestan, and Kazerun. The tectono-stratigraphic journey unveils a profound connection between changes in sedimentary basin depth and nuanced alterations in sedimentary rocks' facies, orchestrated by the interplay of various basement faults, some following the Arabian trend, others aligning with the majestic Zagros trend—a symphony of geological forces shaping the Miocene narrative in the Fars and Bandar Abbas Hinterland. [ABSTRACT FROM AUTHOR]

Maps of diluvial boundaries for the North American midcontinent are presented by state and by sedimentary basin. The upper diluvial boundary is the base of Ice Age sediments. For most of the study area, the basal diluvial boundary is the erosional unconformity between Precambrian crystalline rock and the Phanerozoic sedimentary record. The exceptions are Proterozoic to Cambrian rifts: the Midcontinent, East Continent, Fort Wayne, Reelfoot, Rough Creek Graben, and Rome Trough rifts. These are remnants of severe crustal disruption at the onset of the Flood, with varying ratios of volcanic and sedimentary fill. This paper focuses on the basal marine diluvial boundary and the upper diluvial boundary, excluding the rifts, showing the volume and distribution of sediments of the Ice Age. Deep Proterozoic rifts will be addressed in Part II. Detailed state maps of the basal diluvial boundary are shown in the appendix. Maps of the study area reveal cratonic basins of varying size, show a thickening of diluvial strata toward the south, and show the extent of Ice Age deposition. All these aid in understanding the work of the Flood in this region. [ABSTRACT FROM AUTHOR]

Extensive, new outcrops along the MT‐100 state road in the northern part of the central uplift of the 40‐km diameter, 252–259 Ma old Araguainha impact structure, Central Brazil, have become available for investigation. They offer new insight into the contact relationships between the different lithologies and the genesis of different types of impact‐related rocks, as well as the current level of erosion of the structure. Three types of impact melt rock (IMR) with different field relationships and compositions can now be distinguished: (1) Type‐I of granitic composition and occurring mainly as veins and dikes, besides a few larger pods, in the central alkali granite core of the central uplift; (2) Type‐II in the form of plastically deformed clasts of mainly highly silicious compositions in polymict impact breccia; and (3) Type‐III, derived from partially melted conglomerate or sandstone precursors, and that occurs at selected sites in (meta)sedimentary strata of the basement in the immediate environs of the alkali granite core. Both polymict lithic and melt‐bearing (suevitic) impact breccias are recognized in the 110‐m thick integrated section through impact breccia directly overlying the crater floor. This crater floor is composed of (meta)‐sedimentary basement strata with granite injections and, locally, sandstones of the Devonian sedimentary Furnas Formation of the Paraná Basin. Main breccia components are (meta)‐pelites and (meta)sandstones of the basement that is currently favored to be related to the regional Paraguay Belt and to the lower sequence of the Paraná Basin sedimentary strata. Locally, breccia contains clasts of IMR Type‐II, and only very rarely are granitic fragments observed. Clasts of IMR Type‐I have never been observed in the breccia deposits. These new observations preclude significant involvement of alkali granite in the formation of the polymict breccia or in the production of shock melts. They also reveal the major role of the (meta)sedimentary precursors in the production of IMR by shock melting and provide essential information for better understanding the cratering processes involved in the formation of an impact structure in a sedimentary target, of the size of the Araguainha impact structure. [ABSTRACT FROM AUTHOR]

Salt diapirs dominate the structure in many sedimentary basins and control the preservation and migration of hydrocarbon. The formation of salt diapirs generally falls into two endmember models: active (up-building) and passive (down-building) diapirism. In the active model, salt diapirs rise from salt buoyancy to pierce through the sedimentary overburden, whereas in the passive model, salt diapirs result from differential loading of sediments during deposition. These endmember models are mostly conceptual or kinematic, the mechanics of active and passive diapirism and their relative roles and interactions in the formation of salt diapirs remain uncertain. Here, we use two-dimensional high-resolution numerical models to investigate the primary factors and critical conditions for active and passive diapirism. Our results indicate that it is improper to use driving mechanisms to classify salt diapirs, because the buoyancy-driven active salt diapirism involves differential loading, while the passive diapirism requires salt buoyancy. The rise of salt diapirs is more sensitive to the effective viscosity of the overburden than to the salt viscosity. Stiff overburdens could prevent the rise of salt diapirs, but they could be pierced by salt diapirs if plastic yield of the overburden is allowed. During deposition, the coupled salt-sediment deformation, driven by both salt buoyancy and differential loading of sediments, can lead to various diapiric salt structures and minibasins. Regional tectonic stress generally promotes salt diapirism by enhancing strain weakening of salts and overburdens. We suggest that the classification of active and passive salt diapirism is an oversimplification in most cases. We propose a general model of the formation of salt diapirs that usually begins with dome initiation driven by salt buoyancy, followed by syndepositional down-building controlled by sedimentation and differential loading and ends with canopy formation when sedimentation stops. [ABSTRACT FROM AUTHOR]

Thirty-seven portable accelerometers were deployed in the eastern San Francisco Bay communities of Walnut Creek and Concord to study site response in a fault-bounded, urban, sedimentary basin. Local earthquakes were recorded for a period of two years from 2017 to 2019 resulting in 101 well-recorded events. Site response is estimated by two methods: the reference site spectral ratio method and a source-site spectral inversion method. The reference site spectral ratio method allows investigation of the variability of site amplification with source azimuth and frequency. The source-site spectral inversion method yields the best least-squares fit to site response for a database of ground-motion records. Both methods show substantial amplification in the Walnut Creek-Concord basin below 2 Hz indicating strong surface-wave development. Greater amplification is seen for sources aligned along the long axis of the basin. Inversion using close-in sources at short distances yields lower amplification at longer periods than the entire data set due to reduced surface-wave generation for steeper angles of incidence. Inversion of site response spectra for shallow shear-wave velocity using a global search algorithm yields VS30 values consistent with generalized mapping results based on geology and topography but with greater variability due to local site variations. 3D finite-element modeling shows greater amplification in the Walnut Creek-Concord basin with a basin-edge effect likely contributing to higher ground motions. Topography is also seen to lead to increased scattering and shadowing effects. [ABSTRACT FROM AUTHOR]

Here we present a strategy to obtain a reliable hydrological simulation over France with the ORCHIDEE land surface model. The model is forced by the SAFRAN atmospheric reanalysis at 8 km resolution and hourly time steps from 1959 to 2020 and by a high-resolution DEM (around 1.3 km in France). Each SAFRAN grid cell is decomposed into a graph of hydrological transfer units (HTUs) based on the higher-resolution DEM to better describe lateral water movements. In particular, it is possible to accurately locate 3507 stations among the 4081 stations collected from the national hydrometric network HydroPortail (filtered to drain an upstream area larger than 64 km 2). A simple trial-and-error calibration is conducted by modifying selected parameters of ORCHIDEE to reduce the biases of the simulated water budget compared to the evapotranspiration products (the GLEAM and FLUXCOM datasets) and the HydroPortail observations of river discharge. The simulation that is eventually preferred is extensively assessed with classic goodness-of-fit indicators complemented by trend analysis at 1785 stations (filtered to have records for at least 8 entire years) across France. For example, the median bias of evapotranspiration is -0.5 % against GLEAM (-4.3 % against FLUXCOM), the median bias of river discharge is 6.3 %, and the median Kling–Gupta efficiency (KGE) of square-rooted river discharge is 0.59. These indicators, however, exhibit a large spatial variability, with poor performance in the Alps and the Seine sedimentary basin. The spatial contrasts and temporal trends of river discharge across France are well represented with an accuracy of 76.4 % for the trend sign and an accuracy of 62.7 % for the trend significance. Although it does not yet integrate human impacts on river basins, the selected parameterization of ORCHIDEE offers a reliable historical overview of water resources and a robust configuration for climate change impact analysis at the nationwide scale of France. [ABSTRACT FROM AUTHOR]

ABSTRACT Carbonate cementation in the Upper Permian sandstones informs the timing and temperature of hydrothermal activity in the south‐western Ordos Basin. This study presents a detailed examination of these hydrothermally influenced carbonate cements, constraining their age, carbonate diagenesis and relationship with regional geodynamic evolution. Sedimentological analyses demonstrate the development of deltaic plain and front sand bodies in the study area, which resulted in interbeds of volcanic matrix‐rich sandstones with matrix‐free sandstones. Petrography and electron microprobe analysis reveal four carbonate mineral growth phases of matrix‐free sandstones in the following sequence; scarce pure siderite, scarce Mg‐rich siderite, abundant blocky calcite and moderately abundant grain‐replacing calcite. The fluid inclusion data show anomalies of homogenization temperature of blocky carbonate cements during early diagenesis, over a wide range of ca 148 to 228°C. In addition, blocky carbonate cements show low δ13C (−5.9 to −13.1‰ Vienna PeeDee Belemnite) and δ18O (clustered tightly from −12.4 to −14.6‰ Vienna PeeDee Belemnite) values, interpreted to result from elevated temperatures during cementation, associated with activation of basement faults and concomitant hydrothermal fluid intrusion triggered by oceanic crust subduction in the south‐west margin of the Ordos Basin. Using in situ calcite U–Pb geochronology, the timing of hydrothermal activity was constrained to ca 247.0 ± 11 to 248.2 ± 4.7 Ma. This work provides a case study for applying intergranular calcite U–Pb dating to determine the absolute timing of fluid flow in sedimentary basins, offering tremendous potential to capture snapshots of various diagenetic evolution stages in sediments. The proposed diagenetic model can also provide new insights and understanding regarding hydrothermally influenced sediments. More importantly, hydrothermal activity may have commenced earlier than previously thought. The North Qinling Orogen uplift and associated Mianlue oceanic crust subduction may have begun at the Permian–Triassic transition with a protracted hydrothermal event in the south‐western Ordos Basin. [ABSTRACT FROM AUTHOR]

In Earth's crust, thermochemical sulfate reduction (TSR) is a common organic–inorganic interaction, which is in close association with the carbon cycle in sedimentary basins and metal sulfide precipitation in Mississippi Valley-type deposits. However, the reaction pathway and mechanism of TSR need further investigation, mainly due to the complex sulfur species involved in this reaction. Here we applied in situ Raman spectroscopy to disclose the stepwise transformation from sulfate to sulfide and the reaction kinetics in the CH 4 -Na 2 SO 4 /MgSO 4 /H 2 SO 4 -H 2 O systems at elevated temperatures and pressures. Our results indicate that sulfate is transformed to H 2 S through a series of reduction and disproportionation reactions. Once dissolved H 2 S reaches a certain concentration, it reacts with sulfate to form intermediate valence sulfur species (S0 and S 3 −), which quickly oxidize methane to generate CO 2 and H 2 S. The formation of S 3 − and S0 is responsible for the autocatalytic effect in TSR. The sulfur speciation significantly affects the reaction kinetics, which could be divided into three stages based on the in situ observations. Extrapolated kinetic data show that TSR could proceed fast under the catalysis of H 2 S, and the half-life of methane is ∼7.10 million years at 200 °C. Subsequent numerical modeling strongly supports that in situ sulfate reduction could provide sufficient reduced sulfur for the formation of giant Mississippi Valley-type deposits, thus serving as an efficient mineralizing mechanism. [ABSTRACT FROM AUTHOR]

Terrestrial sedimentary basins are influenced by rapid changes in the clay content, resulting in significant differences in the lateral sealing capacity (shale gouge ratio, SGR) of different parts of the fault. In the present study, we used a method of setting virtual wells and using seismic inversion data to accurately calculate the SGR of faults in strata composed of interbedded sandstone and mudstone calculate the clay content of the strata and to compensate for the low level of the actual well control. Optimal well spacing was determined based on the variable clay content of the formation. The planar variation of the fault throw was characterized via seismic interpretation. We also examined the lateral sealing of faults. The Putaohua oil layer in the S14 area of the Sanzhao Sag in the Songliao Basin was chosen as an case study. Based on the calculation of fault SGR values and the oil distribution, the evaluation criteria for the fault sealing capacity were determined, and the changes in the lateral sealing capacity of the faults were analyzed. This approach accurately estimates fault SGR values and predicts the effective oil-bearing area within the fault zone. It is also suitable for evaluating the lateral sealing of faults in strata composed of interbedded sandstone and mudstone. Our findings provide an in-depth understanding of the lateral sealing of faults and can aid in further research on petroleum distribution patterns. [ABSTRACT FROM AUTHOR]

ABSTRACT The mechanisms for the deposition of the Cambrian carbonate sedimentary successions remain controversial. The carbonate‐dominated successions (Stage 3 to Stage 10) are well developed in the North China Craton and they are commonly thought to represent a platform setting because of the flat top. In this study, we propose a new scenarioi, that the Cambrian successions in North China are more likely a carbonate ramp rather than a platform. Detailed sedimentological investigation for the Cambrian rocks in the Yanshan area (Stage 4 to Stage 10) reveals a total of 21 lithofacies which can be grouped into 7 facies associations, including sabkha and mixed tidal flat, shoal, carbonate tidal flat, tidal flat on shoal, protected lagoon, mid‐ramp and outer ramp to shelf basin. Sequence stratigraphy analysis of the Cambrian in the Yanshan area reveals nine third‐order depositional sequences, which shows an overall second‐order transgression. A number of sedimentary characteristics, including the gentle depositional slope, abundant open marine deposits, scattered shoals and microbial mounds, absence of slump or gravity flow sediment, domination of subtidal facies cycles and widespread deposits that formed below the storm wave‐base, indicate that the Cambrian sediments in the Yanshan area were deposited in an intracratonic carbonate ramp depositional system. This intracratonic carbonate ramp includes inner ramp, mid‐ramp, outer ramp and shelf basin facies belts, with the inner ramp exhibiting sub‐facies corresponding to tidal flat, protected lagoon and shoal sub‐facies. Sequence stratigraphy analysis indicates that relative sea‐level changes, corresponding to these nine third‐order sequences, show synchronous with the global sea‐level change across the studied sections. This consistency implies that eustatic sea‐level changes could have been a major factor for the sequence stacking patterns in the Yanshan Area. [ABSTRACT FROM AUTHOR]

ABSTRACT Saddle dolomite is a Ca–Mg carbonate characterized by curved crystal faces, curved cleavage and sweeping extinction under cross‐polarized light. Saddle dolomite and, generally, Ca–Mg carbonates with curved crystal faces, are often assigned to the burial (hydrothermal) realm and serve as proxy archives for hydrogeochemical processes in sedimentary basins and orogens. At present, the physicochemical conditions leading to the formation of these peculiar warped carbonates are unclear, and the mechanisms inducing the curvature of their crystal lattice are debated. This study uses laboratory experiments to assess the factors controlling the formation of carbonates with curved crystal faces as a function of fluid temperature, reactant size, fluid salinity and fluid Mg : Ca. Results show that a range of magnesium calcites with curved surfaces form at elevated temperatures (ca 220°C) from calcium‐rich fluids (Mg : Ca = 0.43) within a wide range of fluid salinities (5 to 40 wt.%). Magnesium calcites that nucleate epitaxially on rhombohedral or saddle dolomite substrates exhibit warped surfaces, while those that nucleate on calcite seeds form flat surfaces. Although the two crystal habits can co‐occur, Mg‐calcites with curved crystal faces (Mg : Ca of 0.35 to 0.40) tend to be more calcium‐rich than those with flat faces (Mg : Ca of 0.58 to 0.74). In experiments with higher fluid temperature (230°C), calcite reactants undergo replacement by dolomite exhibiting planar crystal faces. The results collectively indicate that the formation of Ca–Mg carbonates with warped surfaces is likely related to a combination of geochemical and physical parameters and various threshold limits, as opposed to one specific parameter, for example, elevated fluid temperature, as is commonly reported in the literature. Although most of the present experimental precipitates are disordered magnesian calcites with bent crystal faces, it is reasonable, at the level of a tentative working hypothesis, that these represent precursors of many ancient saddle dolomites commonly found in burial settings. [ABSTRACT FROM AUTHOR]

This paper describes the Santos Basin Underwater Soundscape Monitoring Project (PMPAS-BS), a Brazilian ocean soundscape monitoring initiative. The main objective of the project is to quantify and assess hydroacoustic noise of anthropogenic origin in a large sedimentary basin extending from 23° S to 28° S on the southeastern Brazilian continental margin of the South Atlantic Ocean. Noise associated with oil and gas (O&G) exploration and production activities is the primary target, but this oceanic region also has busy shipping lanes for commercial, military, and fishing vessels. The two main hubs of Brazil’s export and import of goods by sea are located in this region: Santos and Rio de Janeiro ports. The project has three measurement components: mobile monitoring based on gliders and drifting acoustic profilers, fixed shallow-water monitoring based on acoustic measurements at coastal stations near shipping lanes associated with exploration and production activities in the Santos Basin, and fixed oceanic monitoring based on deep-water mooring lines equipped with passive autonomous acoustic recorders near production units, shipping lanes, and areas with lower intensity of O&G activities (pristine or reference sites). Numerical modeling of anthropogenic underwater acoustic noise has also been included as a fourth project component. The PMPAS-BS covers an area of more than 251,000 km² and uses several instruments with different methods and sensors for acoustic measurements. Its results provide current sound levels over a very large region of the western South Atlantic, both in areas more and less affected by anthropogenic activities. [ABSTRACT FROM AUTHOR]

Interpretation of the seismic reflection profiles associated with borehole data from the petroleum industry offers a novel way to study sill emplacement in sedimentary basins. This study uses this approach to reveal the intrusive part of the Tarim Large Igneous Province (LIP) within the basin, which has not been systematically reported. A large number of igneous intrusions (sills) are identified in the sedimentary layers of the Central Tarim Basin. The burial depth of the sills is 6–8 km, and they are mainly located within the upper Ordovician strata. According to their seismic facies and drilling data, it is inferred that they are dolerite sills. Based on the uplift of the overlying strata above the intrusions, it is concluded that the sills were mainly formed during the depositional period of the middle Permian Kupukuziman Formation and Kaipailezike Formation (early stage), with a few formed during the depositional period of the upper Permian strata (late stage). It is likely that these two stages of sill intrusion correspond to the main basaltic eruptions within the basin and the mafic dike emplacement in the Bachu area of the Tarim LIP, respectively. The study suggests that that the dolerite sills reported in this study are also an important component of the Permian Tarim LIP. [ABSTRACT FROM AUTHOR]

The provenance of most basin systems today is interpreted based on radiogenic ages or the geochemical composition of detrital minerals, which has all but replaced the use of whole-rock geochemical approaches that can effectively complement provenance information inferred from detrital approaches. Here, we further investigate previous provenance models developed using detrital zircon U-Pb geochronology by applying whole-rock major and trace element geochemistry of fine-grained clastic rocks from the late Oli-gocene–middle Miocene Tyonek Formation, late Miocene Beluga Formation, and Pliocene Sterling Formation in the Cook Inlet Basin, Alaska, USA. When taken alone, our new geochemical data suggest solely intermediate igneous sediment sources to the basin. When paired with existing detrital zircon U-Pb data, however, significant mixing of felsic and mafic sediment sources is evident, which indicates that thorough mixing of geochemically distinct source terranes can mask the input from individual sources in whole-rock geochemical studies. Furthermore, we demonstrate that both weathering and provenance influence the major element chemistry of sediment source terranes as well as the resultant basinal strata. Our conclusions indicate that the combination of whole-rock geochemistry with other detrital approaches provides a robust interpretation of sedimentary basin provenance. [ABSTRACT FROM AUTHOR]

The Qaidam Basin is the largest sedimentary basin within the Tibetan Plateau, with up to ∼15-km-thick deposits accumulated in the Cenozoic. Understanding how it deformed in response to the far-field effects of India-Eurasia collision is critical to improving our knowledge of the mechanism underlying northward plateau growth. Unlike typical compressional basins, where upper-crustal deformation concentrates at their margins, the Qaidam Basin features the development of many NW- to WNW-striking folds across the entire basin. Why crustal shortening occurred in the interior of Qaidam Basin, ∼100 km away from the margins, together with the underground geometries beneath these folds, remains unknown. Herein, based on newly acquired three- and two-dimensional (3-D and 2-D) seismic reflection data, borehole logging, and scaled physical analog modeling, we investigated the geometries, kinematics, and formation mechanisms of the folds within the interior of Qaidam Basin. For the first time, we reveal three local weak layers in the Lulehe, Upper Xiaganchaigou, and Shangyoushashan Formations, respectively. They consist mainly of mudstone intercalated with evaporites and limestones, and they have different spatial distributions that are likely confined by major faults and folds. These mechanically weak layers became locally thickened or thinned in response to tectonic loading and/ or facilitated detachment slip to form many décollement folds that were observed at the surface. The shallow deformation above the weak layers is largely decoupled from underlying basement-involved faulting and folding, which mostly terminate upward in these weak layers. Analog modeling results suggest that the lowermost and widely distributed décollement layer in the Lulehe Formation likely facilitated long-distance rapid propagation of deformation into the basin interior. In sum, our study highlights the significance of multiple weak layers during Cenozoic deformation in the Qaidam Basin interior. [ABSTRACT FROM AUTHOR]

Sedimentary basins record crustal-scale tectonic processes related to the construction and demise of orogenic belts, making them an invaluable archive for the reconstruction of the evolution of the North American Cordillera. In southwest Montana, USA, the Renova Formation, considered to locally represent the earliest accumulation following Mesozoic–Cenozoic compressional deformation, is widespread but remains poorly dated, and its origin is debated. Herein, we employed detrital zircon U-Pb and (U-Th)/ He double dating and sanidine 40Ar/39Ar geochronology in the context of decimeterscale measured stratigraphic sections in the Renova Formation of the Muddy Creek Basin to determine basin evolution and sediment provenance and place the basin-scale record within a regional context to illuminate the lithospheric processes driving extension and subsidence. The Muddy Creek Basin is an extensional half graben in southwest Montana that is ∼22 km long and ∼7 km wide, with a >800-m-thick sedimentary package. Basin deposition began ca. 49 Ma, as marked by multiple ignimbrites sourced from the Challis volcanic field, which are overlain by a tuffaceous fluvial section. Fluvial strata are capped by a 46.8 Ma Challis ignimbrite constrained by sanidine 40Ar/39Ar dating. An overlying fossiliferous limestone records the first instance of basinal ponding, which was coeval with the cessation of delivery of Challis volcanics–derived sediment into the Green River Basin. We attribute initial ponding to regional drainage reorganization and damning of the paleo–Idaho River due to uplift and doming of the southern Absaroka volcanic province, resulting in its diversion away from the Green River Basin and backfilling of the Lemhi Pass paleovalley. Detrital zircon maximum depositional ages and sanidine 40Ar/39Ar ages show alternating fluvial sandstone and lacustrine mudstone deposition from 46 Ma to 40 Ma in the Muddy Creek Basin. Sediment provenance was dominated by regionally sourced, Challis volcanics–aged and Idaho Batholith– aged grains, while detrital zircon (U-Th)/He (ZHe) data are dominated by Eocene cooling ages. Basin deposition became fully lacustrine by ca. 40 Ma, based on an increasing frequency of organic-rich mudstone with rare interbedded sandstone. Coarse-grained lithofacies became prominent again starting ca. 37 Ma, coeval with a major shift in sediment provenance due to extension and local footwall unroofing. Detrital zircon U-Pb and corresponding ZHe ages from the upper part of the section are predominantly Paleozoic in age, sourced from the Paleozoic sedimentary strata exposed in the eastern footwall of the Muddy Creek detachment fault. Paleocurrents shift from south- to west-directed trends, supporting the shift to local sources, consistent with initiation of the Muddy Creek detachment fault. Detrital zircon maximum depositional ages from the youngest strata in the basin suggest deposition continuing until at least 36 Ma. These data show that extension in the Muddy Creek Basin, which we attribute to continued lithospheric thermal weakening, initiated ∼10 m.y. later than in the Anaconda and Bitterroot metamorphic core complexes. This points to potentially different drivers of extension in western Montana and fits previously proposed models of a regional southward sweep of extension related to Farallon slab removal. [ABSTRACT FROM AUTHOR]

The Yerrida Basin in the south-eastern Capricorn Orogen, WA is a Proterozoic sedimentary basin that is prospective for base metals. A regional TEMPEST airborne electromagnetics (AEM) survey over the Capricorn Orogen, coinciding magnetotelluric (MT) survey and available downhole electrical property measurements provide an opportunity to compare the electrical conductivity of the rocks, and the electromagnetic (EM) responses of near surface and deeper sedimentary packages of the Yerrida Basin. Of particular interest is assessing whether it is possible to obtain reliable structural and stratigraphic information from, and to what depth, such as is required for exploration of basin terrains. The MT data were modelled using a 3D inversion algorithm, and the AEM data were modelling using a 1D inversion algorithm. An integrated interpretation of the two datasets allows surface geology to be mapped and for a conductivity section to be created to several kilometres depth. Electrical property measurements showed that one of the stratigraphic units, the Johnson Cairn Formation, is anomalously conductive and hence is readily mapped allowing faults, folds, thickness variations etc to be inferred from the inversions. The underlying and resistive Juderina Formation also gives rise to EM responses, albeit less strong. The results suggest significant modification of the published geological map of the area. The study demonstrates the usefulness of EM methods for exploring sedimentary terrains, but this is greatly facilitated by the presence of conductive stratigraphic units. While not always common practice in green fields exploration, it is recommended that electrical petrophysical measurements are made before committing to large scale EM surveys to better constrain interpretations. [ABSTRACT FROM AUTHOR]

Near coasts and shelves are strongly affected by the hydrodynamic forces and involves important information about the long term and permanent changes. Understanding the past dynamic transformations of shelves and near coasts can shed the future projections about effects of climate changes. High-resolution seismic and multibeam bathymetry data shed light on sedimentation since the last sea level lowstand in the Bandırma Bay, southern shelf area of the Marmara Sea. Five different seismic units were identified from the bottom upward based on seismic stratigraphic analysis, which are bounded by the reflection surfaces. Differential hydrological and depositional processes in the bay are shown by the definition and mapping of these unique seismic units and surfaces in the shallow sedimentary record: The water level in the basin crossed the threshold between the two basins, and advancing flows began from the north to the western basin. The basin continued to fill with water, and progressive depositions were interrupted with the onlaps of U3–4. The water level rose above the threshold in both basins, resulting in the two lakes becoming a single lake and the creation of marine conditions. The initial deposition in the eastern basin was fluvial, deposited in the form of regressive systems tracts. The overall morphology and stratigraphic settings observed in Bandırma Bay have nearly the same characteristics as those observed in the Sea of Marmara (like northern and western Marmara shelf, Gemlik Bay, Büyükçekmece Bay etc.) oceanography, implying that similar hydrodynamic conditions and erosional and depositional processes are controlled mainly by sea level changes controlled by climate changes related to morphological properties. [ABSTRACT FROM AUTHOR]

The use of the HVSR (Horizontal-to-Vertical Spectral Ratio) method on single-station microtremor measurements is well documented in small alluvial plains for bedrock mapping. In large sedimentary basins, like the Po Plain, its application is still debated. To shed some light on this issue, we investigated two seismogenic structures buried below the Po Plain Quaternary deposits: the Mirandola and Casaglia anticlines. We acquired and analysed a dense distribution of HVSR data covering the two areas and mapped the frequency and amplitude values of the observed resonance peaks. The top of both anticlines is highlighted by high amplitude peaks picturing E-W elongated sectors with high-impedance contrast, where Quaternary deposits are reduced in thickness to about 60–130 m and directly overlay the Pliocene (Mirandola) and Miocene (Casaglia) marine units. In Mirandola, the high-amplitude peaks also correspond to higher resonance frequencies, while in Casaglia, the distribution of resonance frequencies is relatively uniform suggesting a flatter crestal region and the lateral continuity of the resonance surface. The combination of peak frequency and amplitude information on a dense grid of measurement points is thus confirmed to be useful for identifying and mapping buried geological structures such as structural highs. Further modelling is being carried out to estimate the depth of the surface responsible for the observed resonances, through calibration with borehole information. [ABSTRACT FROM AUTHOR]

This is the second of a two-part New Zealand Journal of Geology and Geophysics Special Issue on understanding sedimentary systems in Aotearoa-New Zealand's Hikurangi Subduction Margin (HSM). This volume includes six research papers that explore sediment-tectonic interactions operating over a range of spatio-temporal scales. We take a distinctive perspective moving from the subduction deformation front in the Hikurangi Trough, upslope to the subduction wedge, and onshore to the Coastal Ranges. Temporally, papers span the onset of subduction in the Miocene, to disentangling provenance of turbidity currents triggered by the 2016 CE Kaikōura Earthquake. Collectively, the studies in the special issue reveal a complicated and continually evolving margin, where active tectonics and volcanism, coupled with vigorous climatic and oceanographic drivers, modulate erosion, transport, and depositional cycles of vast volumes of terrigenous sediment into ocean basins. Despite decades of significant research advances in our knowledge of the HSM, considerable scope remains for future work. A deeper understanding of fundamental tectonic-sediment interactions operating on active margins, along with the significant geohazards they pose remain outstanding research needs. Collectively, Volumes 1 and 2 highlight enduring interest in the HSM as a globally important natural laboratory for the study of subduction zone geoscience. [ABSTRACT FROM AUTHOR]

The Transylvanian basin is one of the major Tertiary sedimentary basins in the Carpathian-Pannonian region. Its thick sedimentary fill contains prominent Middle Miocene age salt that forms major diapir structures at the basin margins. The microstructural characteristics of the rock salt represent one of the main factors that determines the potential of a salt body for storage of hydrogen. The main aim of this study is to extend our understanding of the deformation mechanism of Praid rock salt located at the eastern margin of the Transylvanian basin. Based on petrography, we identified two types of rock salt: (1) layered salt with rather uniform grain size distribution showing alternation of greyish (clay mineral bearing) and white (clear halite) layers, and (2) massive grey salt with large, elongated halite crystals, accompanied by sub-micrometer size grains of halite. To shed light on the microstructure of the rock salt, we performed electron backscatter diffraction (EBSD) mapping, and studied gamma-irradiated samples both in the massive and layered salt samples. Dislocation creep and pressure solution creep were identified which acted concurrently in the Praid rock salt. The total strain rate falls between 1.2 and 1.3×10−10 s−1. The results of this study reveal a complex deformation history of the salt body where coexisting and migrating fluids have played an important role. The outcome of this project contributes to the hydrogen storage potential assessment for the Transylvanian salt and to a better understanding of the structural evolution of the Transylvanian basin. [ABSTRACT FROM AUTHOR]

Dating the onset of ancient (>1 Ma) karstification is a challenge. One approach is to date the earliest calcite cements in speleothems. We show the benefits of in situ U-Pb dating directly on thin sections from ancient (ca. 30 Ma) thin (<1 mm) speleothems in the karstified Lower Oligocene lacustrine-palustrine carbonates of the Paris Basin (France), which cannot be dated using other methods. We dated 32 calcite rafts (a type of speleothem), one geopetal cement, and 10 calcite cements precipitated along the karstic walls. The ages of the calcite rafts and cements at 29 ± 1 Ma (Lower Oligocene) fall within the age range of the host deposits (≈29 Ma) previously deduced from palaeontological evidence. We demonstrate that cementation of the carbonate host rock, its dissolution, and the speleothem precipitation occurred within 2 m.y. after deposition. Ostracods and intraclasts trapped within Rupelian calcite rafts clearly indicate that the karst developed deep underground shortly before a phase of lacustrine-palustrine sedimentation at the surface. This very early dissolution episode is attributed to the uplift of the Paris Basin as a result of the far-field intraplate deformation induced by the alpine orogenesis. This study shows that in situ U-Pb geochronology on ancient calcite rafts is a promising technique for the indirect dating of karstification and, more broadly, for dating geodynamic events and diagenetic evolution of sedimentary basins. [ABSTRACT FROM AUTHOR]

Microtremor tests and finite element numerical simulations were used to analyze the seismic ground motion effects of the Yunnan Dayao sedimentary basin. The results of the microtremor relative to the reference point spectral ratio (HS/HR) method showed that the spectral ratio curves of each observation point in Dayao basin show multipeak characteristics, indicating that the site consists of different soil layers; the predominant frequencies of each observation point mainly are 6~9 Hz in the basin and there are lots of differences in the predominant frequencies of different observation points, which indicate that the site stiffness of each observation point is different; the differences of spectral ratios between the east–west directions (EW) and the north–south directions (NS) reveal the site's anisotropy. The amplification coefficient characteristics of each observation point in the basin obtained by numerical simulation show that the predominant frequency is 6 ~ 9 Hz; the amplification coefficients of each observation point are different; the edge effect and the focusing effect amplify the seismic ground motion in the basin; the different amplification coefficients of the two sub‐basins reflect the significant effect of the basin soil layers' differences on the seismic ground motion, the site is softer and amplification coefficients are larger; the slope degree of basin edges significantly affects the seismic ground motion near the basins edge, the amplification coefficients of the slope steeper and amplification coefficients larger. This study demonstrates that the microtremor test spectral ratio (HS/HR) method has good reliability applied to the analysis of basin effect and combining the finite element numerical simulation method is more effective in revealing the basin effect mechanism. [ABSTRACT FROM AUTHOR]

The Ediacaran–Cambrian deposits of Brittany (Brioverian series) contain both a few isolated pluricentimetric discoid structures, dome-shaped or "donut"-shaped, and a multitude of centimetric to infracentimetric more or less elliptical fossils or pseudofossils. The discoid and elliptical Brioverian structures are compared to similar fossils and pseudofossils found worldwide, and interpreted considering both sedimentary and biological hypotheses. This synthesis of more or less enigmatical fossils from the Ediacaran–Fortunian deposits of Brittany completes the previous descriptions of more well-known discoid and elliptical Brioverian structures such as Nimbia-like and Chuaria-like fossils. It provides a better understanding of the diversity of the Brioverian fossils and original sedimentary structures. [ABSTRACT FROM AUTHOR]

The study presents a review of the Geology of the Senegalo-Mauritanian (S-M) sedimentary basin with a glance on stratigraphy, tectonic evolution, and integrated petroleum systems. The S-M basin is a typical Mesozoic-Cenozoic passive margin which opened westward from the Northwest African craton into the Atlantic Ocean. The basin overlies a Paleozoic sequence which represents part of the Taoudeni basin. Rifting and tectonic movements associated with the breakup of Gondwana and the formation of the Atlantic Ocean began in the Triassic and have led to a subdivision of the basin into three stages: pre-rift (Proterozoic-Paleozoic), syn-rift (Late Triassic-Middle Jurassic), and post-rift (Middle Jurassic-Present). Pre-rifting phase, made of sediments deposited between the Precambrian and Devonian, is mainly continental detrital rocks. The main deposits of the syn-rift stage are Triassic evaporites and Jurassic volcanic intrusion from the Central Atlantic Magmatic Province (CAMP). The post-rift segment consists of an Upper Jurassic-Lower Cretaceous carbonate platform overlain by a predominantly progradation and transgressive Cretaceous-Tertiary clastic sequence, up to 12,000 m thick in places. The S-M basin exhibits oil and gas potential. Indeed a total of three petroleum systems exist in the basin: the Lower Paleozoic Petroleum System (LPPS), the Subsalt Petroleum System (SSPS), and the Cretaceous-Tertiary Petroleum System (CTPS). Previous source rock analyses have shown a good quantity of total organic content (TOC) and type I kerogen; type I, II, and III for the LPPS and CTPS, respectively. The main reservoirs comprised fractured sandstone of Cambrian to Ordovician and Devonian, with good porosity up to 20%, karstified Oligocene limestone, and Maastrichtian and Miocene sandstones. The primary seals include the Upper Cretaceous and Tertiary marine mudstone and shale for these petroleum systems. Both stratigraphic and structural traps were derived from seismic profiles and included growth faults, slope truncation, turbidite-related traps, salt-related structures, carbonate bank deposits, and structures related to volcanism. Preserved extensional structures before the rifting and especially normal faults along the Paleozoic section have served as migration pathways for hydrocarbon in the Southern sub-basin. [ABSTRACT FROM AUTHOR]

The North American craton interior preserves a >1 Ga history of near surface processes that inform ongoing debates regarding timing and drivers of continental‐scale deformation and erosion associated with far‐field orogenesis. We tested various models of structural inversion on a major segment of the Midcontinent Rift along the Douglas Fault (DF) in northern Wisconsin, which accommodated ≳10 km of total vertical displacement. U‐Pb detrital zircon and vein calcite Δ47/U‐Pb thermochronometry from the hanging wall constrain the majority of uplift (≳8.5 km) and deformation to 1052–1036 Ma during the Ottawan phase of the Grenvillian orogeny. Combined U‐Pb zircon dates, Δ47/U‐Pb calcite thermochronometry, and field data that document syn‐ to early post‐depositional deformation in the footwall constrain a second stage of uplift (1–1.5 km) ca. 995–980 Ma during the Rigolet phase of the Grenvillian orogeny. A minor phase of Appalachian far‐field orogenesis is associated with minimal thrust reactivation. Our combined analyses identified the 995–980 Ma Bayfield Group as a Grenvillian foreland basin with an original thickness 0.5–2 km greater than currently preserved. By quantifying flexural loading and other subsidence mechanisms along the Douglas Fault, we identify dynamic subsidence as a mechanism that could be consistent with the development of late‐Grenvillian transcontinental fluvial systems. Minimal post‐Grenvillian erosion (0.5–2 km) in this part of the craton interior has preserved the Bayfield Group and equivalent successions, limiting the magnitude of regional erosion that can be attributed to Neoproterozoic glaciation. Plain Language Summary: Around 1.1 billion years ago, volcanic rocks and sediments began accumulating in a large rift basin around the present‐day Lake Superior region of North America. Continent‐continent collision on the edge of North America caused rifting to cease and major uplift to occur on thrust faults in the rift. The timing of the tectonic shift and the amount of crustal uplift and the number of uplift episodes are all poorly constrained. Our new geochronology precisely identifies the age of two major uplift episodes, ∼1.05 and ∼0.98 billion years ago. Mineral veins that formed during uplift record the age and temperature of formation, which enables reconstruction of an uplift history. We conclude that the collisional event ∼1.05 billion years ago resulted in ≳8.5 km of uplift followed by 1.0–1.5 km of uplift ∼0.98 billion years ago. A sedimentary basin associated with collision ∼1.0 billion years ago may have been part of a vast transcontinental river system. The surface underlying the Great Unconformity, a surface representing missing time, regionally did not undergo much erosion following uplift, suggesting long‐term stability of the North American craton interior over the last ∼0.98 billion years. Key Points: U‐Pb zircon and calcite dates constrain two‐stage Grenvillian inversion of the Midcontinent Rift on the Douglas Fault (DF) in northern WisconsinΔ47/U‐Pb thermochronometry constrains vertical displacement of ≳8.5 and ∼1.5 km in the Ottawan and Rigolet Grenvillian phases, respectivelyBasin analysis and clay mineralogy constrain original thickness, subsidence drivers, and erosion of a ca. 1010–980 Ma Grenvillian foreland [ABSTRACT FROM AUTHOR]

Despite the elevated heat flow known in the Western part of the South Slave Region (Northwest Territories, Canada), a continuous and equilibrium geothermal gradient was never measured in boreholes below the communities where geothermal energy could be developed. This paper aims to predict the geothermal gradient and assess the Earth's natural heat flow below the communities of Fort Providence, Kakisa, Hay River, and Enterprise. Temperatures from drill-stem tests and bottom well logs were corrected for drilling disturbance and paleoclimate. The thermal conductivity and heat generation rate of the geological formations were determined from the literature and with new laboratory measurements. Original 1D models were developed to evaluate subsurface temperature through the sedimentary formations based on a thermostratigraphic assessment. The results indicate a geothermal gradient that varies from 44.1 ± 10.6 °C km−1 to 59.1 ± 14.9 °C km−1 and heat flow that varies from 105.5 mW m−2 to 160.2 mW m−2 below the communities. These estimates were in agreement with the equilibrium geothermal gradients measured in Cameron Hills, south of the four communities, and were used to verify our predictions. The highest geothermal gradient (59.1 ± 14.9 °C km−1) was estimated at Hay River, which, therefore, has the most favorable geological conditions for geothermal development. [ABSTRACT FROM AUTHOR]

Introduction: Sedimentary basins are naturally porous and permeable subsurface formations that underlie approximately half of the United States. In addition to being targets for geologic CO2 storage, these resources could supply geothermal power: sedimentary basin geothermal heat can be extracted with water or CO2 and used to generate electricity. The geothermal power potential of these basins and the accompanying implication for geologic CO2 storage are, however, understudied. Methods: Here, we use the Sequestration of CO2 Tool (SCO2TPRO) and the generalizable GEOthermal techno-economic simulator (genGEO) to address this gap by a) estimating the cost and capacity of sedimentary basin geothermal power plants across the United States and b) comparing those results to nationwide CO2 sequestration cost and storage potential estimates. Results and discussion: We find that across the United States, using CO2 as a geothermal heat extraction fluid reduces the cost of sedimentary basin power compared to using water, and some of the lowest cost capacity occurs in locations not typically considered for their geothermal resources (e.g., Louisiana, South Dakota). Additionally, using CO2 effectively doubles the sedimentary basin geothermal resource base, equating to hundreds of gigawatts of new capacity, by enabling electricity generation in geologies that are otherwise (with water) too impermeable, too thin, too cold, or not deep enough. We find there is competition for the best sedimentary basin resources between water- and CO2-based power, but no overlap between the lowest-cost resources for CO2 storage and CO2-based power. In this way, our results suggest that deploying CO2-based power may increase the cost of water based systems (by using the best resources) and the cost of CO2 storage (by storing CO2 in locations that otherwise may not be targeted). As such, our findings demonstrate that determining the best role for sedimentary basins within the energy transition may require balancing tradeoffs between competing priorities. [ABSTRACT FROM AUTHOR]

The Rakaia River in the South Island of New Zealand is a unique catchment in which to trace active detrital gold transport, deformation and concentration from near-coeval orogenic sources. The catchment hosts widespread small late Cenozoic hydrothermal alteration zones, some of which are gold-bearing, in actively rising and eroding mountain headwaters. Detrital gold liberated from the sources is distinctively porous with abundant micron-scale silicate inclusions, especially albite. Fine gold (∼200–100 µm) has been transported >100 km downstream, but coarse gold remains highly diluted in proximal fluvial sediments. Fine gold is also diluted by coarse fluvial sediments that form the upper kilometre of the Canterbury sedimentary basin southeast of the mountain front. Minor re-concentration of fine gold occurs in a bedrock gorge at the mountain front, and on steep ocean beaches beyond the river mouth. Despite the long-distance transport, the fine gold particles have been only superficially modified by surface smearing and minor flattening. The gold may have travelled in suspension in the river, buoyed by electrostatically adhering fine micas, in contrast to detrital garnets that were rounded in bed-load. In contrast, detrital gold on the western side of the mountains has been flattened to thin flakes during bed-load transport. [ABSTRACT FROM AUTHOR]

To meet the growing global demand for metal resources, new ore deposit discoveries are required. However, finding new high-grade deposits, particularly those not exposed at the Earth's surface, is very challenging. Therefore, understanding the geodynamic controls on the mineralizing processes can help identify new areas for exploration. Here we focus on clastic-dominated Zn–Pb deposits, the largest global resource of zinc and lead, which formed in sedimentary basins of extensional systems. Using numerical modelling of lithospheric extension coupled with surface erosion and sedimentation, we determine the geodynamic conditions required to generate the rare spatiotemporal window where potential metal source rocks, transport pathways, and host sequences are present. We show that the largest potential metal endowment can be expected in narrow asymmetric rifts, where the mineralization window spans about 1–3 Myr in the upper ∼ 4 km of the sedimentary infill close to shore. The narrow asymmetric rift type is characterized by rift migration, a process that successively generates hyper-extended crust through sequential faulting, resulting in one wide and one narrow conjugate margin. Rift migration also leads to (1) a sufficient life span of the migration-side border fault to accommodate a thick submarine package of sediments, including coarse (permeable) continental sediments that can act as source rock; (2) rising asthenosphere beneath the thinned lithosphere and crust, resulting in elevated temperatures in these overlying sediments that are favourable for leaching metals from the source rock; (3) the deposition of organic-rich sediments that form the host rock at shallower burial depths and lower temperatures; and (4) the generation of smaller faults that cut the major basin created by the border fault and provide additional pathways for focused fluid flow from source to host rock. Wide rifts with rift migration can have similarly favourable configurations, but these occur less frequently and less potential source rock is produced, thereby limiting potential metal endowment. In simulations of narrow symmetric rifts, the conditions to form ore deposits are rarely fulfilled. Based on these insights, exploration programmes should prioritize the narrow margins formed in asymmetric rift systems, in particular regions within several tens of kilometres from the paleo-shoreline, where we predict the highest-value deposits to have formed. [ABSTRACT FROM AUTHOR]

We numerically solve the acoustic radiative transfer equation for seismic S‐waves via Monte Carlo simulation. By assuming a von Kármán‐type random medium with anisotropic scattering, we are able to simulate a realistic medium and determine its attenuation properties. In this study, we present an improved method, called QEST, to determine the frequency‐dependent intrinsic and scattering attenuation by nonlinear envelope inversion for a 1‐D multilayer model. Additionally, the spectral source energy of earthquakes and the energy site amplification of stations are determined. The code was applied to real data from the northern and southern Leipzig‐Regensburg fault zone (LRZ), Germany, as well as fluid‐induced earthquakes at the Insheim geothermal reservoir, Germany. The attenuation was analyzed in several frequency bands between 4.2 and 33.9 Hz and between 6.0 and 67.9 Hz, respectively. The inversion results reveal that the crystalline crustal subsurface along the LRZ shows little to no depth dependence, but there are differences in attenuation between the north and south. At Insheim, the near‐surface sedimentary basin exhibits significantly greater absorption and scattering than the crystalline basement. The inversion also shows that isotropic scattering can be an oversimplification and thus underestimate attenuation. Plain Language Summary: Seismic attenuation is an important property of the subsurface. It determines the amplitude decay of a seismic wave emitted by an earthquake with time and distance. Seismic attenuation can be divided into scattering and intrinsic attenuation. Scattering is caused by small‐scale heterogeneities in the earth, while intrinsic attenuation is caused by anelastic processes such as internal friction. Differentiating between scattering and intrinsic attenuation poses a challenge. In this study, we present an advancement for the determination of seismic attenuation that considers the heterogeneity of the Earth's crust. We apply this new method to three distinct regions to assess the depth‐dependent scattering and intrinsic attenuation. The findings reveal that pure crystalline rock exhibits little depth dependence, whereas the attenuation properties of a sedimentary basin differ significantly from those of the underlying crystalline rock. Overall, quantifying depth‐dependent seismic attenuation enhances our ability to accurately estimate seismic hazards. Key Points: We invert for frequency‐dependent intrinsic and scattering Q with anisotropic scattering using envelope fitting in a multilayer modelWe estimate seismic moments and corner frequencies for small earthquakes using a 1‐D attenuation modelWe observe a strong attenuation contrast between a sedimentary basin and the underlying crystalline basement [ABSTRACT FROM AUTHOR]

The study examines the specific features of the structure and composition of strata of the Tyushevskaya basin of Eastern Kamchatka, which formed at the site of the Vetlovsky basin, which is marginal marine in nature. This structure probably began to form in the Late Eocene–Oligocene. A scheme for its evolution is proposed. In the modern structure, sediments of the Tyushevskaya basin overlie the material complexes and structures of various terranes and participate in the accretionary structure of the region. Sedimentary formations are predominantly facies-variable coarse coastal-marine and/or deltaic sediments, which change upsection to deeper-water flysch formations. Oil-bearing manifestations are associated with these complexes. [ABSTRACT FROM AUTHOR]

Authigenic minerals have been studied in Phanerozoic volcanosedimentary deposits in the northern part of the Asian continent–Pacific Ocean transition zone. The following were found: chlorite, mica, corrensite, rectorite, defective chlorite, kaolinite, smectite, calcite, barite, gypsum, epsomite, zeolites, cristobalite, quartz, and goethite. The minerals corrensite and rectorite have significant indicative properties, as do the assemblages corrensite–laumontite, corrensite–epsomite–authigenic calcite and mica–kaolinite–quartz. Such a range of minerals indicates that the thickness of sediments in the studied basins could reach 3–5 km, and their formation temperature could be more than 150°C. The mica–kaolinite assemblage may indicate epicontinental sedimentation conditions associated with coal formation on nearby land, the corrensite–chlorite assemblage may indicate conditions favorable for the evaporation of seawater, and the presence of laumontite in it may indicate periodic calcium supply to the sedimentary basin. The periods of mineral formation, possibly associated with global climatic events, have been identified: 113–120, 110–113, 105–110, 93–95, 72–83, 61–72, 56–61, 33–56 Ma, which can serve as benchmarks to determine sedimentation conditions and the framework for more reliable stratigraphic constructions. [ABSTRACT FROM AUTHOR]

The latest geological and geophysical information on the Zeya-Bureya sedimentary basin (Russia, Far East) is summarized. Based on drilling data from corehole and deep wells and 2D and 3D CDPM seismic data, taking into account the integrated interpretation of gravity and magnetic survey data and geological survey materials, a map was compiled for the surface of the pre-Mesozoic basement of the sedimentary basin, as well as structural maps for the top of the Cretaceous formations. The maps reflect a series of rift grabens and uplifts identified by the authors on seismic time sections during their reinterpretation. The method of compiling maps is given. A geological map of sediments overlying the pre-Mesozoic basement of the Zeya-Bureya sedimentary basin and a tectonic map of the sedimentary cover were compiled. During tectonic zoning of the sedimentary cover, the classification of tectonic elements was adopted that is widely used in the tectonic zoning of oil and gas regions, proposed by V.D. Nalivkin and updated at the Trofimuk Institute of Oil and Gas Geology and Geophysics, Siberian Branch, Russian Academy of Sciences (INGG SB RAS). As a result of tectonic zoning in the basin, the Inner Region and the Outer Belt were identified, and the tectonic elements complicating them were characterized. A characteristic feature of the Outer Belt is the presence of large intermediate structures: monoclines and mega- and mesomonoclines. Conversely, the Inner region of the basin is characterized by the presence of a large negative structure, complicated by smaller positive and negative elements. The main stages of the formation and development of the sedimentary cover of the Zeya-Bureya sedimentary basin are identified and described: rifting, early syneclise, late syneclise, and neotectonic. [ABSTRACT FROM AUTHOR]

A new industrial genetic ("aphanitic") type of phosphorite deposits has been identified. In terms of the genetic, tectonic, facies, and geochemical features, this type differs fundamentally from the known micrograined, granular, nodular, shelly, and pebbly phosphorite deposits. They are the first industrial accumulations of phosphorus matter in the history of our planet. Conditions for their accumulation existed only in the Ediacaran period, when mass phosphatization of sediments with the formation of phosphate nodules as ribbon-shaped layers took place under the influence of early diagenetic processes. Phosphates were accumulated in basins with synsedimentary block structure inherited from paleorift structures and seismically active tectonic environment. The multidirectional displacement of blocks generated a complex seafloor relief and facies heterogeneous complex of sediments ranging from reefogenic-stromatolitic sediments in the uplifting areas to pelitic sediments in the dipping areas. The latter areas were marked by a massive input of sedimentary material significantly enriched in the planktonic organic matter. Transformation of organophosphorus compounds during the sulfate reduction promoted the phosphatization of sediments and the formation of aphanitic phosphorites, which differ from other ore types by anomalously high concentrations of As, Sr, and Ba and by anomalously low contents of U and REE. [ABSTRACT FROM AUTHOR]

Based on potential field data, anomalies derived from the EIGEN6C4 satellite model were used to interpret various structural features of the coastal plain, Southwest Cameroon volcanic line, northwestern margin of Congo Craton (CC) and southern extension of Pan-African belt. Since building a global comprehension of unknown phenomena about Earth's materials is of high relevance given the tectonic complexities of the investigated area, some edge enhancement techniques were applied to the gravimetric data. After generating the Bouguer anomalies, a cosine filter was used to provide the residual data set that should characterize the gravity effect arising from superficial density sources, and finally, some amplitude and phase-based edge detection methods were used to interpret the computed Bouguer and residual data. The results of this research work have demonstrated that the enhanced horizontal gradient amplitude and fast sigmoid edge detector (FSED) filters could detect density boundaries more successfully than the other filters tested. The structural map generated by FSED revealed that the delineated lineaments are oriented NW–SE, NE–SW, N–S and NNE–SSW. In addition, important tectonic features such as Central Cameroon, Kribi–Campo and Sanaga shear zones are indicative of the effectiveness of this methodological approach and the CC limit was better highlighted in this research work. In general, the lineament map enhances the knowledge of the structural setting of the Douala Kribi–Campo sedimentary basin as well as unexposed fracture zones that may have caused seismic events in recent years. [ABSTRACT FROM AUTHOR]

In response to the problems of unclear distribution of deep-water pre-salt carbonate reservoirs and formation conditions of large oil fields in the Santos passive continental margin basin, based on comprehensive utilization of geological, seismic, and core data, and reconstruction of Early Cretaceous prototype basin and lithofacies paleogeography, it is proposed for the first time that the construction of pre-salt carbonate build-ups was controlled by two types of isolated platforms: inter- depression fault-uplift and intra-depression fault-high. The inter-depression fault-uplift isolated platforms are distributed on the present-day pre-salt uplifted zones between depressions, and are built on half- and fault-horst blocks that were inherited and developed in the early intra-continental and inter-continental rift stages. The late intra-continental rift coquinas of the ITP Formation and the early inter-continental rift microbial limestones of the BVE Formation are continuously constructed; intra- depression fault-high isolated platforms are distributed in the current pre-salt depression zones, built on the uplifted zones formed by volcanic rock build-ups in the early prototype stage of intra-continental rifts, and only the BVE microbial limestones are developed. Both types of limestones formed into mound-shoal bodies, that have the characteristics of large reservoir thickness and good physical properties. Based on the dissection of large pre-salt oil fields discovered in the Santos Basin, it has been found that both types of platforms could form large-scale combined structural-stratigraphic traps, surrounded by high-quality lacustrine and lagoon source rocks at the periphery, and efficiently sealed by thick high-quality evaporite rocks above, forming the optimal combination of source, reservoir and cap in the form of "lower generation, middle storage, and upper cap", with a high degree of oil and gas enrichment. It has been found that the large oil fields are all bottom water massive oil fields with a unified pressure system, and they are all filled to the spill-point. The future exploration is recommended to focus on the inter- depression fault-uplift isolated platforms in the western uplift zone and the southern section of eastern uplift zones, as well as intra-depression fault-high isolated platforms in the central depression zone. The result not only provides an important basis for the advanced selection of potential play fairways, bidding of new blocks, and deployment of awarded exploration blocks in the Santos Basin, but also provides a reference for the global selection of deep-water exploration blocks in passive continental margin basins. [ABSTRACT FROM AUTHOR]

Developments in ultradeep azimuthal resistivity (UDAR) technology has recently progressed from their application in high-angle and horizontal wells to low-angle and vertical wells. This has presented the opportunity to assess their suitability as derisking tools because of their ability to look ahead of the bit, up to c. 100 ft (c. 30.5 m). Dominated by a complex interplay of structure, sedimentation, and volcanic activity, the NE Atlantic Margin presents a challenging environment to plan and drill wells safely and within planned budget, with many wells drilled within the Faroe–Shetland Basin (FSB) currently the most expensive to-date within the United Kingdom continental shelf (UKCS). The limited number of wells drilled in the FSB and their geographical sparsity relative to those of other areas of the UKCS, make offset analysis and derisking a challenge. The often-unpredictable distribution of igneous rocks throughout the basin presents significant challenges in the planning and drilling of oil and gas wells. Up to 88% of igneous intrusions within the FSB are estimated to be below seismic resolution, which alongside variation in composition, presents significant issues related to drilling safely, efficiently and successfully. Within this paper, we investigate the use of UDAR technology and how they could be deployed in areas of complex volcanic geology such as the West of Shetland (WoS). This paper reviews the nature of the drilling experiences within the FSB to date, the impact it has on exploration, and how improvements in drilling technology could help decrease nonproductive time (NPT). [ABSTRACT FROM AUTHOR]

The development of oil and gas production technologies has made it possible to take a new look at the prospects of increasing the raw material base of oil in areas with developed production infrastructure. The projects of exploration and preparation for development of high-carbon low-permeability strata, primarily shale formations, occupy a special position today, as the world experience has shown their potential for oil and gas production. High-carbon shale formations are widely spread in Russia. The most significant of them include the Bazhenov Formation of Western Siberia and the Domanik sediments of the Eastern European Platform, the hydrocarbon potential of which is estimated ambiguously. The ambiguity of hydrocarbon potential estimation is related to the uneven distribution of organic matter determined by the variability of sedimentation conditions. The paper presents the results of the study of Upper Devonian sediments, based on analytical geochemical data of well cores and extracts of bitumoids from them. The analysis of the confinement of zones of increased concentration of organic matter to certain sedimentary conditions and facies zones made it possible to estimate the volume of mobile hydrocarbons in the amount of 5.3 billion tonnes preserved in the high carbonaceous strata. The obtained data on HC volumes were compared with the reservoir properties, studied using X-ray tomography, of low-permeability hydrocarbon-bearing clay-siliceous strata, which allowed us to consider the Upper Devonian carbonaceous strata as an important reserve for maintaining oil production in the future in one of the developed oil-producing regions of the European part of Russia. [ABSTRACT FROM AUTHOR]

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This paper investigates the deep-sea morphology and sedimentary processes within the Santa Catarina Plateau and the Vema Channel, prominent features crucial for influencing bottom circulation in the western South Atlantic and regulating the exchange of deep and bottom waters between the Argentine and Brazil basins. The study leverages a unique dataset comprising multibeam data for generating detailed digital terrain models and sub-bottom profiling records, alongside numerical modeling of bottom current velocities (GLORYS12V1 reanalysis). Numerous sediment waves, predominantly cresting mudwaves and mass-wasting deposits associated with steeper sea floor gradients, were identified in the region, aligning with findings from the Argentinian and South Brazilian slopes. The investigation of these features contributes not only to the identification of contourites but also to the enhancement of understanding regarding deep-water circulation within the 3,500-to-4,500-meter range. This depth range serves as a critical transition zone between the Argentine and Brazil basins and plays a pivotal role in elucidating the northward distribution of Antarctic Bottom Water (AABW), an integral component of the Atlantic meridional circulation. In contrast to prior studies that focused on specific regions of the plateau, this research offers a comprehensive overview of the region's morphology and sedimentary processes, thereby advancing comprehension of deep-water circulation dynamics between the Argentinian and Brazilian basins. [ABSTRACT FROM AUTHOR]

The Devonian-Carboniferous (D-C; 359 Ma) boundary is marked by widespread deposition of organic-matter-rich black shales associated with the Hangenberg mass extinction event. The Exshaw Formation spans the D-C boundary in the Western Canada Sedimentary Basin (WCSB) and includes the basal Exshaw Shale deposited under broadly anoxic waters. The sediments at the base of the Exshaw Shale were deposited synchronously during a transgressive event across the WCSB, spanning the geographic variability of the basin. The variable Corg content of the shale was affected by local nutrient upwelling and paleotectonic features impacting water depth and circulation. To characterize the link between paleogeography and nutrient cycling, geographic (N = 20 locations) and stratigraphic (N = 6 locations) trends of δ13^^ and δ15^^ were examined throughout the WCSB, representing a range of depositional settings. The δ15^^ values range between 0.0 and 6.3%" and δ13^^ from -29.5 to -26.8%. Phytoplankton production in focused upwelling zones acquired a relatively 15N-depleted signature through isotopic fractionation during nutrient assimilation, and the residual nutrient pool was 15N-enriched. The advection of surface waters away from the location of upwelling supported additional phytoplankton growth and the deposition of sediments with higher δ1^ values. The stratigraphic sections include black laminated and burrowed mudrock sequences that record changes in paleoredox conditions, water depth, and tectonism over time. Up-core from the base of the Exshaw, the Corg content decreases and simultaneously δ15^^ increases, suggesting a decrease in eutrophic conditions. Variable δ13^^ and δ15^^ trends demonstrate that there is no "type" isotopic profile spanning the D-C boundary in the WCSB. [ABSTRACT FROM AUTHOR]

One‐dimensional site response analysis (1D SRA) remains the standard practice in considering the effect of local soil deposits and predicting site‐specific ground motions, although its range of applicability to realistic seismic wavefields is still in question. In this 1D approach, horizontal and vertical ground shaking are assumed to be induced by vertically propagating shear and compressional waves, respectively. A recent study based on analytical two‐dimensional (2D) plane waves and simple point source earthquake simulations has shown two mechanistic limitations in this 1D modelling technique for general inclined seismic waves, that is, systematic over‐prediction of the vertical motion and wave trapping in the 1D soil column. In this article, we evaluate in detail the applicability of this 1D modelling approach to realistic three‐dimensional (3D) simulated seismic wavefields in shallow sedimentary basins. Linear‐viscoelastic 1D SRA predictions using two types of input motions that are commonly used in practice—rock outcrop and in‐column motions, are compared with the reference true site response results from 3D earthquake simulations in terms of various measures in the frequency and time domain. It is shown that the horizontal motion in the 3D seismic wavefield exhibits dominant shear wave propagation phenomenon, while the vertical motion is a combined effect of compressional and shear waves and can be over‐predicted by the 1D approach when the incident seismic waves are inclined. Direct evidence of the wave refraction process that leads to the vertical motion over‐prediction is provided. 1D SRA with in‐column inputs can yield motions that have significantly longer duration compared to the true 3D site response solution due to trapped waves, casting in doubt the frequent need for increased soil damping in existing site studies to compensate for wave attenuation due to scattering alone. Sensitivity investigation on the increase of soil profile damping by a multiplier Dmul shows Dmul values compatible with those found in the literature for both horizontal and vertical motions. It is shown that the level of Dmul optimized for a best match of the spectral acceleration is dependent on the characteristic of the input motion and a larger Dmul is typically required for the vertical component. In contrast, 1D SRA with outcrop motions predicts motions with shorter significant duration due to its inability to capture the basin‐edge generated surface waves. A suite of ground motion simulations was performed to assess the sensitivity of the observations to the basin geologic structure including the velocity gradient, rock‐basin impedance contrast and basin depth. The analysis results show that the accuracy of the simplified 1D procedure is dependent on the wavefield composition of both the input motions and the true 3D site response solution. While the horizontal motions in shallow sedimentary basins can, to the first order, be reasonably captured by the simplified 1D approach, 1D SRA for the vertical component is in general not reliable and contributions from inclined shear waves should be accounted for in site‐specific evaluation of the vertical design ground motion. [ABSTRACT FROM AUTHOR]

This study interprets gravity data in parts of southeastern Nigeria using spectral analysis and 2D modeling. The study area is bounded by Latitudes 5°N 30' to 6°N 30' and Longitudes 7°E 0' to 8°E 0'. The Bouguer gravity data was obtained from the Nigerian Geological Survey Agency (NGSA) in Geosoft grid file format. The study uses the spectral analysis method and 2D modeling with GM SYS to estimate the average depth of the sedimentary strata and the basement from the Bouguer anomaly map. The data sets cover the southern part of the Anambra basin and the northern Niger Delta complex. Regional-residual separation was applied to the Bouguer gravity data through the polynomial fitting of the first degree. This gave rise to the residual and regional maps. Further filtering actions accentuated the subtlest anomalies peculiar to the study area. Spectral analysis results reveal two depth models: deep source (D1) and shallow source (D2). The deep source represents depths within the basementrelated sources, while the Shallow source is associated with shallow-related gravity sources. D1 varies from 1.50 km to 4.02 km with an average value of 2.95 km, while D2 varies from 1.91 km to 0.514 km with an average value of 1.50 km. The thickest depth of the Modelled cross-section is at about 6845.62 m, which is within the tertiary recent sediment with clayey sands and shale extending beyond the study area. The average or actual sedimentary thickness of 2.95 km suggests that the area will be plausible for hydrocarbon exploration. The thickest sedimentary cover represents density variation in sedimentary rock of the basin, which occurs at the southern part of block 4 (Okigwe). [ABSTRACT FROM AUTHOR]

Sedimentary basins are widely distributed on Earth. Among them, the small basins account for their majority. In China, small basins account for over 80% of the total number of basins, while in aspect of the industrial oil and gas reservoirs, the small-scale basins contribute less than 10% which is far less than large and medium-sized basins (>76%). However, the hydrocarbon abundances per unit area (HAPUA) of most small-scale petroliferous basins are high; for some basins characterized by "small but enriched", the HAPUAs are much higher than large to medium-sized petroliferous basins, resulting in higher exploration effectiveness. A comprehensive study of 16 small-scale basins containing conventional oil and gas in China was implemented. They are divided into remnant and proto small-scale basins based on the differences in basin formation mechanisms and dynamic environments. Furthermore, the proto small-scale basins are subdivided into strike-slip basin, rift basin, and thermal basin. Remnant small-scale petroliferous basins generally undergo three imperative evolutionary stages, including the proto- basin construction stage with development of the main source rock, the reformed and remnant stage, and the late buried and hydrocarbon generation stage. The residual source rocks in the proto-basin provide a resource foundation, and the deep burial in the late stage is the key link for hydrocarbon generation and accumulation. The three subtypes of proto small-scale basins, strike- slip, rift, and thermal basins, are all formed and developed in relatively active dynamic environments. They are generally characterized by rapid subsidence and deposition, relatively high geothermal fields, active deep background, and later-stage modification. This dynamic environment results deposition of "small but thick" strata in the basin and forms various structural traps. It also benefits the extraordinary growth and prosperity of organisms, the formation of high-quality source rocks, and hydrocarbon generation and accumulation. There are similarities between the "small but rich" petroliferous basins and the "small rock bodies forming large ore deposits" in terms of the formation dynamic environment and ore-forming theory. The two fields can be compared and mutually referenced in scientific research and academic thinking. [ABSTRACT FROM AUTHOR]