Sedimentary Cover Research Articles

Anomalous geoobjects in the Lithosphere of Uzbekistan and their interrelations with ore deposits

One of the priority tasks of the Geological Service of the Republic of Uzbekistan is the study of the paleozoic foundation under the cover of Meso-Cenozoic sediments, mainly using deep seismic sounding profiles, in order to trace known ore fields and mineralized zones in the overlying part of the basement. In recent years, in the laboratory “Structure of the Lithosphere” of the Institute of Geology and Geophysics named after Kh.M. Abdullayev, new data have been obtained as a result of reinterpretation of a complex of geophysical data. In the present work examines the role of anomalous geoobjects with high and low seismic density parameters along deep seismic sounding (DSS) profiles in the Lithosphere of Uzbekistan from the point of view of their spatial correlation with explored deposits of ore minerals. New regional features of the interrelationships between the geological structure of the lithospheric deep structures of Uzbekistan and the spatial distribution of deposits have been identified.

Maps of Quaternary sediments and features in Austria and neighbouring countries at the scales of 1:500 000 and 1:1 500 000

Abstract Today’s landscape and morphology of Austria is markedly affected by erosional and sedimentary processes active during the Quaternary. Particularly, large glaciers have shaped the landscape of the Eastern Alps. The presented maps at the scales of 1:500 000 and 1:1 500 000 aim to visualise areas, where deposition or erosion in different stages of the Quaternary prevailed. The maps (free download available) were generated with ArcGIS software using available map sheets at larger scales (1:50 000, 1:200 000). No additional field work has been conducted. The most obvious observation is that an extensive cover of Quaternary sediments predominantly occurs in the northern Alpine foreland, especially outside of Austria. The maps show that large glacier tongues of the Middle to Late Pleistocene glaciations (Günz, Mindel, Riss and Würm) existed in the northern and southeastern alpine foreland. In the east, hardly any signs of glacial coverage are visible due to later fluvial cannibalisation of features partly deposited in narrow valleys. Bordering terminal moraines, extensive, terraced fluvial deposits occur within and around the Alps showing that river courses partly changed during the Pleistocene. Aeolian sediments often accompany these sediments, but also cover huge areas in the Vienna and Tulln Basin and the Little Hungarian plain. The distribution of large rockslide events shows that they mainly formed in glacially covered areas as a result of rock destabilisation after glacier retreat. Additionally, the map shows that the alpine foreland is subject of inhomogeneous uplift since the Neogene. For example, between Salzburg and Munich, wide areas are covered by Pleistocene deposits, whereas to the west of Munich and in Upper Austria, recent rivers incised deeper into Neogene sediments.

Phanerozoic Burial and Erosion History of the Southern Canadian Shield from Apatite (U-Th)/He Thermochronology

Patterns of Phanerozoic burial and erosion across the cratonic interior of North America can help constrain the continental hypsometric history and the potential influence of dynamic topography on continental evolution. Large areas of the Canadian Shield currently lack Phanerozoic sedimentary cover, but thermochronology data can help reconstruct the previous extent, thickness, and erosion of Phanerozoic strata that once covered the craton. Here, we report apatite (U-Th)/He (AHe) data for 15 samples of Precambrian basement rocks and 1 sample of Triassic kimberlite from a 1400 km–long east–west transect across the southern Canadian Shield. Single-grain basement AHe dates range from >500 Ma in the west to <250 Ma in the east. AHe dates for the kimberlite in the middle of the transect overlap with the pipe’s Triassic eruption age. These data, combined with previous apatite fission-track data, geologic constraints, and thermal history modeling, are used to constrain the first-order regional thermal history that we interpret in the context of continental burial and erosion. Our burial and erosion model is characterized by Paleozoic burial that was greater to the east, unroofing that migrated eastward through Jurassic time, and little to no post-Triassic burial. This pattern suggests dynamic and tectonic forces related to Appalachian convergence, subduction cessation, and later rifting as drivers. The AHe data contribute to efforts to collect thermochronology data across the Canadian Shield to map out continental-scale burial and erosion patterns. The outcomes can be used to refine mantle dynamic models and test how dynamic topography, far-field tectonics, and other effects influence the surface histories of continental interiors.

РЕКОНСТРУКЦИЯ ОСАДКОНАКОПЛЕНИЯ В АЛДАНО-МАЙСКОМ ОСАДОЧНОМ БАССЕЙНЕ (ЮГО-ВОСТОК СЕВЕРО-АЗИАТСКОГО КРАТОНА) НА ОСНОВЕ СЕЙСМОСТРАТИГРАФИЧЕСКОГО РАЗРЕЗА

Sedimentation history of the Aldan-Maya sedimentary basin was reconstructed based on the seismostratigraphic section. A total of 10 reconstructions cover the stages of formation of the main sedimentary structures - the Riphean (Late Proterozoic) Aldan and Yudoma-Maya troughs, overlying Vendian-Cambrian deposits, as well as periods of tectonic restructuring. Studies that use a seismostratigraphic section and geological data to investigate the formation of the sedimentary cover contribute to a more substantiated and visual understanding of the evolution of the structure in question over one and a half billion years.

ТЕКТОНИЧЕСКОЕ СТРОЕНИЕ И ИСТОРИЯ ГЕОЛОГИЧЕСКОГО РАЗВИТИЯ ЗЕЯ-БУРЕИНСКОГО ОСАДОЧНОГО БАССЕЙНА ПО РЕЗУЛЬТАТАМ КОМПЛЕКСНОЙ ИНТЕРПРЕТАЦИИ МАТЕРИАЛОВ БУРЕНИЯ И СЕЙСМОРАЗВЕДКИ

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, 2D and 3D CDPM seismic data, taking into account the integrated interpretation of gravity and magnetic survey data, geological survey materials, a map was constructed on the surface of the pre-Mesozoic basement of the sedimentary basin, as well as structural maps on 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 constructing 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 constructed. During the tectonic zoning of the sedimentary cover, the classification of tectonic elements was adopted, which is widely used in the tectonic zoning of oil and gas regions, proposed by V.D. Nalivkin and updated at 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, mega- and mesomonoclines. On the contrary, 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.

Detection of potential reservoirs of the Mezen syneclise of the Eastern European platform

The possibility of discovering new hydrocarbon deposits within the north-eastern segment of the European part of Russia will reduce the cost of transporting hydrocarbons to major industrial centres. And access to Russia’s most important transport artery, the Northern Sea Route, in the context of the growing importance of the tanker fleet and reorientation of sales markets proves the need to build up the region’s resource base. However, it is necessary to take into account the environmental and climatic risks associated with hydrocarbon production in the Arctic conditions, as well as their transport. This paper presents the data of paleoreconstructions of sedimentation settings of Precambrian sedimentary strata in the light of updating the history of development of the Mezen-Belomr region and studying the reservoir properties of the Riphean-Wendian part of the sedimentary cover section. As a result, formations with enhanced filtration-capacity properties were identified. The Vendian part of the section is characterised by good values of open porosity (up to 20.89%).

СТРУКТУРНО-ГЕОДИНАМИЧЕСКИЕ СИСТЕМЫ ВОСТОЧНОЙ АРКТИКИ

The research considered in the article was aimed at studying the structure and evolution of the Eastern Arctic structural-geodynamic systems. The tectonic model of the base of the Eastern Arctic plate section determines their vertical zonality in terms of structure and tectonics based on the interpretation of seismic and other geophysical survey data correlated with varying degrees of reliability with the studied sections in the adjacent or remote areas. Accordingly, the models of vertical structure and formational composition built on this basis are largely hypothetical and tend to change (even fundamentally) as geological and geophysical information accumulates. Geodynamic analysis of formation of the Eastern Arctic structural-geodynamic systems was based on tectonic-geodynamic paleoreconstructions reflecting interactions among blocks of the consolidated crust. The results obtained made it possible to significantly update, expand and, in some cases, refine the understanding of the structure of the basement and individual reference horizons of the sedimentary cover in this part of the water area. It was also concluded that the East Arctic waters are of significant interest in terms of hydrocarbon exploration, however, the assessment of their hydrocarbon potential is difficult due to poor geophysical knowledge and lack of wells.

Инженерно-геологические изыскания в междуречье р. Камы и нижнего течения р. Белой для строительства зданий и сооружений1

The article considers the engineering-geological conditions of the territory of industrial and civil engineering development. Oil production, the cities expansion, and favorable natural conditions cause the intensive construction of buildings for various purposes, and industrial facilities. Information about the characteristics of soils, the level of groundwater occurrence, geological and physical processes that are important for choosing a foundation is needed for proper construction of objects. The geological structure of the area under consideration is characterized by a thick Paleozoic sedimentary cover overlain by Quaternary deposits such as sandy loam, loam, sand, and gravel-pebble rocks.

УЛЬБАНСКИЙ ТЕРРЕЙН (ЗОНА) КАК ЧАСТЬ ЮРСКОГО АККРЕЦИОННОГО КОМПЛЕКСА СИХОТЭ-АЛИНСКОГО ОРОГЕННОГО ПОЯСА

New data are reported on the age of Triassic-Jurassic cherts replaced up the section by siliceous mudstones, and then by mudstones, which together with basalts form thin (up to hundreds of meters) plates and lenses that pinch out along the strike at different levels of the multi-kilometer terrigenous section of the Ulban terrane (zone). In the Nimelen subzone (the Albazino gold deposit area), their time interval of formation is Norian-Early Toarcian and that of host terrigenous deposits is Pliensbachian-Bathonian. In the Mewachan subzone, cherts and siliceous–clayey rocks are Middle Triassic-Callovian in age and terrigenous rocks are Middle-Late Jurassic (including Tithonian). A comparison of deposits of the Ulban terrane with deposits of the Samarka terrane which are well-studied and similar in age and composition allows us to consider the Ulban terrane (zone) as part of the Jurassic accretionary complex of the Sikhote-Alin orogenic belt. There are also sufficient indications to believe that its structural features are consistent with the subduction model. The basis for this is that the Triassic-Jurassic cherts and siliceous–clayey rocks accumulated for about 45 million years at a rate of about 1.8 m/million years characteristic for the oceanic plate sedimentary cover. At the same time, a gradual transition from cherts to mudstones is observed evidencing the movement of the oceanic plate into the subduction zone. The inclusion of its fragments in the terrigenous section is the result of their being detached in the trench and under the overhanging slab. Tectono-stratigraphic columns of the subzones of the Ulban terrane and a scheme of zoning of the Jurassic accretionary prism have been compiled with four structural-age levels along its entire length.

Patterns of Alluviation in Mixed Bedrock‐Alluvial Channels: 2. Controls on the Formation of Alluvial Patches

AbstractUnderstanding the development and spatial distribution of alluvial patches in mixed bedrock‐alluvial rivers is necessary to predict the mechanisms of the interactions between sediment transport, alluvial cover, and bedrock erosion. This study aims to analyze bedrock alluviation patterns using a 2D morphodynamic model, and to use the model results to better understand the mechanisms responsible for alluvial patterns observed experimentally. A series of simulations are conducted to explore how alluvial patterns in mixed bedrock‐alluvial channels form and evolve for different channel slopes and antecedent sediment layer thicknesses. In initially bare bedrock low‐slope channels, sediment cover increases with increasing sediment supply because areas of Froude‐subcritical flow enable sediment deposition, while in steep‐slope channels the flow remains fully supercritical and the model predicts so‐called runaway alluviation. For channels initially covered with sediment, the model predicts a slope‐dependent sediment supply threshold above which sediment cover increases with increasing sediment supply, and below which the bedrock becomes fully exposed. For a given sediment supply, the fraction of bedrock exposure and average alluvial thickness converge toward the equilibrium value regardless of the initial cover thickness as long as it exceeds a minimum threshold. Steep channels are able to maintain a continuous strip of sediment under sub‐capacity sediment supply conditions by achieving a balance between increased form drag as bedforms develop and reduced surface roughness as the portion of alluvial cover decreases. In lower‐slope channels, alluvial patches are distributed sporadically in regions of the subcritical flow.

Patterns of Alluviation in Mixed Bedrock‐Alluvial Channels: 1. Numerical Model

AbstractMixed bedrock‐alluvial rivers can exhibit partial alluvial cover, which plays an important role in controlling bedrock erosion rates and landscape evolution. However, numerical morphodynamic models are generally unable to predict quasi‐steady persistent patches of depositional alluvial features under conditions where the sediment supply is less than the sediment transport capacity of the channel. Hence, we present a new two‐dimensional depth‐averaged morphodynamic model that can be applied to both fully alluvial and mixed bedrock‐alluvial channels, and we use the model to gain insight into the mechanisms responsible for the development of sediment patches and patterns of bedrock alluviation. The model computes hydrodynamics, sediment transport, and bed evolution using a roughness partitioning that accounts for differential roughness of sediment and bedrock, roughness due to sediment transport, and form drag. The model successfully replicates observations of bar development and migration from a fully alluvial flume experiment, and it models persistent sediment patches observed in a mixed bedrock‐alluvial flume experiment. Numerical experiments in which the form drag, sediment transport roughness, and bedform stress correction were neglected did not successfully reproduce the observed persistent sediment cover in the mixed bedrock‐alluvial case, suggesting that accounting for these different roughness components is critical to successfully model sediment dynamics in bedrock channels.

Increasing the reliability of the probabilistic assessment of the forecast for identifying oil- and gas-bearing local structures during geological exploration work on a geodynamic basis

On the basis of tectonophysical models at the regional and local levels, the paper provides an analysis of the role of geodynamic factors that increase the likelihood of assessing the detection of oil- and gas-bearing structures at geological exploration stages. It proposes a consideration of geodynamic criteria during prospecting works to develop and substantiate scientific and methodological approaches to the possibility of accumulation and preservation of hydrocarbon components in the sedimentary cover structures. The obtained results allow to correct the geological model of the proposed field in the area of structural heterogeneity, to reveal the connection between productive formations, as well as the other factors, for the successful discovery of economically viable development targets.

PRINCIPLES OF CALCULATIONS AND ARRANGEMENT OF LOCAL DRAINAGE SYSTEMS IN PRIVATE BUILDING TERRITORIES

Abnormally heavy rains in the first two spring months of 2023 revealed the unpreparedness and lack of protection of many settlements in the Kyiv region from excessive moisture and inundation. Among them, is Novi Petrivtsi village, where the natural conditions for surface runoff and precipitation infiltration (lack of visible surface slopes and poorly permeable cover sediments) are unfavourable and significantly complicated by buildings, and a network of highways. The long-term retention of water on the surface, the rise of groundwater levels, and the layered structure of the upper part of the geological section provide grounds for the use of combined local drainage systems with compliance with drainage standards of at least 3,0 m. Since the high density of buildings often does not allow for contour drainage around residential buildings, it is necessary to lay single-line horizontal drainage to a greater depth than for a conventional contour drainage of 3,5 meters or more. However, the lack of roadside ditches and other water intakes and means of orderly drainage do not allow homestead drainage systems to work as efficiently as possible. This requires the creation of an orderly system of water intakes (trenches and closed collectors) on the scale of the village. Foreign experience convinces that the rational planning of such systems is possible under the conditions of establishing the character of rainfall distribution with a resolution of 1–5 minutes in time and a step of 500 m across the area. Meteorological radar is used to record radar images of rain and study its intensity. An effective solution to the water drainage problem is impossible without detailed engineering and geological investigations. Due to them, litho-facies inhomogeneities in the aeration zone and water-saturated stratum, which lead to the retention and support of groundwater, were discovered in the local area. Taking into account the spatial boundaries of these engineering and geological elements allow drainage more efficiently. Drainage capacity is substantiated by forecasts of changes in the maximum amount of precipitation per day and two days in a row. Due calculating the drainage capacity, it should be taken into account that the maximum amount of precipitation in the future period will have a guarantee of 0,5-2,0% less than the actual maximum values. In the calculation part, the main attention is paid to the selection of equations for determining the width of influence of a single horizontal drain. Five formulas have been selected that can be used to solve similar problems. The time of onset of the established mode of operation of a single drain was calculated. Future research should focus on the collection of high-resolution rainfall and local urban runoff data, as well as the implementation of urban drainage models.

New insights into crustal and geological structures beneath the Southern Benue trough of Nigeria and parts of Cameroon Volcanic Line from tailored gravity data

We utilized a high-resolution tailored gravity dataset to investigate the geological structure beneath the Southern Benue Trough of Nigeria and along the Cameroon Volcanic Line (CVL). The tailored gravity data was obtained by applying a stochastic combination technique to integrate global gravity field model, terrestrial gravity data, and residual gravity data over the study area. We then carried out gravity techniques to compile the Bouguer gravity map and to estimate the crustal thickness. To obtain suitable estimates of the reference depth and density contrast of the Moho interface, we fitted the gravimetrically determined Moho geometry to the seismic estimates by minimizing the Root-Mean-Square of their differences. A minimum RMS of 3.6 km at a reference depth of 26 km and a density contrast of 450 kgm−3 was achieved over the study area. Our results reveal a dense magmatic feature criss-crossing the central portion of the study area. This phenomenon led to a thinning of the crust and formation of various geological structures, mainly at the southern end. We could see a very thick sedimentary cover within some of these structures possibly occasioned by compressional and extensional tectonic forces acting at the southwest end. Our study reveals that these compacted sedimentary covers could be important habitats for mineralization. We have also been able to refine and depict the lateral extent of the crustal architecture at a fine scale using our tailored gravity dataset. We concluded that the tectonic events beneath the study area are complex and point to several geophysical factors earlier revealed in published studies. However, a narrowing of two or more conjugate plates (margins) propelled by an upward force may have primarily led to the upward displacement of some of the magmas in-between those plates forming the intrusive rocks.

Geophysical contribution using electrical resistivity to study the Triassic sandstone aquifer, southeastern Tunisia

A study was conducted to analyze the electrical resistivity structure of the Triassic Sandstone Aquifer in southeastern Tunisia in regions without constraints from nearby well data. The aim was to determine how the geometry, depth, thickness, and lateral extension of the aquifer within the Medenine region. Seven profiles, including two-dimensional profiles and vertical electrical soundings, were collected, with electrodes spaced between 4 and 5 m apart depending on the desired depth penetration. Geological outcrops and stratigraphic data from nearby water wells were used to constrain the final models, however these wells could only be used roughly as most of them were too far from a given profile. The models from two-dimensional inversions showed that the alluvium in the upstream region of Oued Nagueb had a maximum thickness of about 10 m, whereas in the downstream reaches, the thickness decreased to 4 m. The models indicated that the sandy clays of the alluvium may reduce the infiltration of surficial water into the Triassic Sandstone aquifer. The study area has a gradual thinning of the sedimentary cover from west to east, causing the Triassic Sandstone aquifer to deepen toward the west. The fine-grained sandstone which is characteristic of the Triassic Sandstone aquifer was detected at depths of approximately 40 m in the eastern region and more than 77 m in the western region of the study area. The electrical resistivity models imaged the Medenine fault, which may influence the structural configuration of the Triassic Sandstone aquifer. One model (ERT7) indicated that the Medenine fault acts as a water barrier and retards the groundwater movement of the aquifer. These findings provide information on the extent and depth of the aquifer for future groundwater exploration in the area and can serve as a reference model for analyzing aquifers in northeastern Tunisia.

Lithological Investigation of The Drill Core from a Sedimentary Cover in the Area of the Siljan Ring, Central Sweden

The ring structure of Siljan, located in the central part of Sweden, is considered by many researchers to be a meteorite (impact) crater. Impact craters are among the most complex geological objects on the Earth. The origin and formation of these structures still raises many questions. To find answers to these questions we need reliable geological information about the structure of the crater and the composition of the rocks. Information about the thickness and geological structure of the Siljan Ring area sedimentary cover will help to understand the process of the Siljan Ring structure’s formation as well as other similar geological formations on the Earth. Here, we present the results of laboratory studies of sedimentary rock samples taken from four exploration wells drilled in the vicinity of the Siljan Ring crater, which made it possible to compile their detailed lithological description. The laboratory studies included a structural analysis of the samples, and a texture and mineralogical analysis in thin sections. A structure analysis was carried out visually, while structural and mineralogical analyses were carried out on thin sections using a polarizing microscope and a scanning electron microscope. The main components of the rocks (minerals and fragments), along with their ratio and secondary transformations, were determined. The results of the structural analysis of the samples, and the textural and mineralogical analysis of the rocks in thin sections, showed that the sediments’ composition in the sedimentary cover near the Siljan Ring structure changes in different areas in accordance with their facies and stratigraphic characteristics. Furthermore, a change in the thickness of the sections and the succession sequences of rock units was established. A change of this nature is presumably caused by tectonic disturbances of an endogenous or impact source.

Characterization of Groundwater Physico-chemical Parameters in Lake Chad Polders: The Case of the Bol-bagassola Polder

Located southwest of Lake Chad (Bol-Bagassola), the study area is characterized by a Sahelian-type climate underlain by more recent sedimentary cover. The aim of this manuscript is to assess the overall impact of agricultural activities on groundwater quality in the polders (Bol and Bagassola), in order to gain a better understanding of agricultural pollution. To achieve this objective, a water sampling campaign was carried out to study hydrodynamics and hydrochemistry. As a result of this study, piezometric levels are not sufficiently heterogeneous. The pH is around neutral with an average of 7.68, and water temperatures vary between 25.3°C and 32.5°C. Conductivities ranged from 334µS/cm to 9800µS/cm, exceeding the maximum WHO/Chad standards limit of 2500µS/cm. Most of the variables (chemical parameters) are below the drinking water quality limits defined by WHO/Chad standards, with the exception of the open wells (P1, P2) at Malkoura, which show very high concentrations of potassium, sulfate, sodium, chloride, ammonium and magnesium, and the high iron signature observed in boreholes F9 and F12 at Talia. These variables (chemical parameters) enabled us to define the bicarbonate calcic and magnesian facies, followed by chloride sodium and potassium or sulfate sodium for the single F9 borehole at Malkoura. The predominance of bicarbonate facies can be explained by the dissolution of evaporites in the reservoir.

Magmatism at an ultra-slow spreading rift: high-resolution geomorphological studies of a Red Sea Rift segment in Hadarba Deep

The mid-ocean rift in the Red Sea is one of the youngest rifting systems on Earth. Only recently, state-of-the-art methods and modern deep-sea instruments have been used to explore this young and unique volcanic system. During the first autonomous underwater vehicle surveys of the Red Sea Rift in Spring 2022, we collected multibeam bathymetry, backscatter, sub-bottom profiler data, and water column data over a 9 km long ridge segment in the Hadarba Deep between 22.49°N and 22.56°N to investigate the volcano-tectonic processes of this ultra-slow spreading segment (12 mm/year spreading rate). The high-resolution hydroacoustic data was used to (1) delineate and quantify the geometry of tectonic structures and individual lava flows, (2) define lava flow morphology and eruption style, (3) estimate relative ages of flows and features, and (4) retrace the evolution of the volcanic activity. In addition, the geochemistry of several young lava flows provides information on the relation between the different magma that supply these eruptions. About 90 eruptive units with variable sedimentary cover have been identified within the 43 km2mapped region. The oldest lava flows are buried under 3 to 4.2 m of sediment, indicating ages of up to ~30 ka based on average sedimentation rate estimates (~14 cm/ka), while the youngest eruptions are covered by<10 cm of sediment, and are thus younger than 700 years. Three volcanic phases have been identified based on changes in flow morphology and distribution, and tectonic pattern. All three axial phases have an average eruptive frequency of ~100-250 years. The segment displays an overall low tectonic extension (<10% of the total extension) and low vertical offset. Our geomorphological maps, analyses, and statistics reveal a moderately faulted, ultra-slow spreading MOR segment in the Red Sea with a surprisingly large amount of magmatic extension, implying that the segment has been underlined by a large magma supply for at least 15 ka. All these observations provide valuable implications for the formation history of the Red Sea Rift and the formation of ultra-slow spreading crust.

3D‐seismic evidence for thick‐skinned tectonics in a ‘classic’ thin skinned tectonics region (external Alpine foreland, Switzerland)

AbstractThe north‐western Alpine foreland in Switzerland and France comprises the Late Miocene Jura Mountains, considered a type example for thin‐skinned thrusting where deformation of the sedimentary cover is decoupled from the basement along a regional basal detachment. To what extent basement faults were involved during its deformation is a matter of debate. We use 3D seismic data to investigate the deformation style along the easternmost tip of the Jura range in unprecedented detail. Here, basement‐rooted normal faults were not only repeatedly reactivated before thrust belt formation but also contemporaneously active as reverse/transpressional faults. They either propagated up into the Mesozoic succession without interruption (‘hard linkage’) or apparently controlled the localisation of Mesozoic faults via smaller‐scale shear zones (‘soft linkage’). Our analysis of the resulting fault geometries questions the existence of a large‐scale basal detachment in this area and points out the importance of thick‐skinned fault reactivation.

Textbooks on lithology of carbonate rocks

Carbonate rocks cover one fifth of the Earth’s sedimentary cover, having great economic significance and bearing important information about the mechanisms and settings of their formation. Research into carbonate rocks allows not only the settings of ancient epochs to be reconstructed, but also to the evolution of those settings to be established. Peer-reviewed textbooks are a good source of learning materials for university students investigating the origin and specifics of these rocks.