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Diachronous opening of the Rheic Ocean and separation of Avalonian–Cadomian terranes from Gondwana began with a change from an active to passive margin in the late Ediacaran to early Cambrian. During the Cambrian, extension within these terranes was recorded by magmatism and by the development of sedimentary basins. However, the timing, style, and kinematics of this transformation still remain poorly understood and plate-scale models vary significantly. To address this issue, the Přibram–Jince basin in the Bohemian Massif was chosen as a case study since it preserves an excellent record of Cambrian rifting. Here, after Cadomian subduction ceased at ∼527 Ma, extension initiated and a thick pile of continental siliciclastics was deposited in the basin between ∼515 Ma and ∼499 Ma, interrupted by marine transgression at ∼506–503 Ma. Our field, paleocurrent, and rock-magnetic data suggest that the source areas were located to the ∼ESE and to the ∼SW of the basin during the deposition of the lower and upper formations, respectively. Sediment sources changed accordingly from distant metamorphic basement (Gondwana?) and Cadomian volcanic arcs and an accretionary wedge underlying the basin. This redirection marked a change in the tectonic evolution of the basin from orthogonal to dextral oblique extension that enlarged the basin into a pull-apart structure. Integrating this depositional and tectonic record into a large-scale picture, we suggest that strike-slip movements along the former Avalonian–Cadomian belt controlled the diachronous opening of the Rheic Ocean. An inherited suture in the Avalonian ribbon terrane facilitated complete rifting and rift–drift transition while the Cadomian terranes remained attached to Gondwana. The kinematics of this event remains controversial. Either it was opposite along the westerly (sinistral) and easterly (dextral) segments of the belt, which may be explained by interaction with an intervening spreading center, or it was the same dextral transtension.

We propose a conceptual geological model for the collision of multiple basement topographic highs (BTHs; e.g., seamounts, ridges, and horsts) with a forearc accretionary wedge. Even though there are many BTHs on an oceanic plate, there are few examples of modeling the collision of multiple BTHs. We conducted numerical simulations using the discrete element method to examine the effects of three BTH collisions with forearcs. The typical geological structure associated with a BTH collision was reproduced during the collision of the first BTH, and multiple BTH collisions create a cycle of formation of BTH collisional structures. Each BTH forces the basal décollement to move up to the roof décollement, and the roof décollement becomes inactive after the passage of the BTH, and then the décollement moves down to the base. As the active décollement position changes, the sequences of underthrust sediments and uplifted imbricate thrusts are sandwiched between the décollements and incorporated into the wedge. At a low horizontal compressive stress, a “shadow zone” is formed behind (i.e., seaward of) the BTH. When the next BTH collides, the horizontal compressive stress increases and tectonic compaction progresses, which reduce the porosity in the underthrust sediments. Heterogeneous evolution of the geological and porosity structure can generate a distinctive pore pressure pattern. The underthrust sediments retain fluid in the “shadow” of the BTH. Under the strong horizontal compressive stresses associated with the next BTH collision, pore pressure increases along with a rapid reduction of porosity in the underthrust sediments. The distinctive structural features observed in our model are comparable to the large faults in the Kumano transect of the Nankai Trough, Japan, where a splay fault branches from the plate boundary and there are old and active décollements. A low-velocity and high-pore-pressure zone are located at the bottom of the accretionary wedge and in front (i.e., landward) of the subducting ridge in the Kumano transect. This suggests that strong horizontal compressive stresses associated with the current BTH collision has increased the pore pressure within the underthrust sediments associated with previous BTHs.

The Lancang Group in SW Yunnan constitutes a pivotal component of the continental margin bounding the Proto- and Paleo-Tethys oceans, yet its formation timing, composition and tectonic affinity remain ill-defined. In this contribution, we present new zircon U-Pb age and whole-rock geochemistry data from volcanic and sedimentary rock units, which are compiled with published data, to refine the depositional age, provenance and nature of the group and its host terrane. The Lancang Group consists of five formations, two of which (Manlai and Huimin) contain abundant metavolcanic rocks. The metavolcanic rocks show a secular change in geochemistry, from EMORB-like calc-alkaline series of the ca. 495 Ma Manlai Formation, to arc-like high-K series of the Huimin Formation. Five metavolcanic samples from the Huimin Formation yielded zircon U-Pb ages between 478 ± 5 Ma and 442 ± 5 Ma. The late Cambrian-Ordovician arc magmatism is related to an active continental margin setting associated with subduction of the Proto-Tethys Ocean. The time-integrated geochemical variation shown by the volcanic rocks likely reflects evolving maturity of the arc system. The youngest detrital zircon ages of the five formations, in conjunction with age constraints from the interbedded volcanic rocks, suggest that the Lancang Group was largely accumulated during the early Paleozoic. The Lancang Terrane is reconstructed as a continental block, which formed part of the magmatically-active margin of the Proto-Tethys during the early Paleozoic. Provenance analysis based on detrital zircon age spectra and Hf isotope data indicates Gondwana affinities of the terrane. Furthermore, xenocrystic zircon ages and zircon Hf and whole-rock Nd model ages from igneous rocks support presence of Neoarchean-Mesoproterozoic basement underlying the terrane. The reconstructed Lancang Terrane bears important implications for understanding the configuration of the northern margin of Eastern Gondwana and the relationship between the Proto- and Paleo-Tethys oceans.

The Qena Bend of the Nile River, named after Qena town in Upper Egypt, is considered a remarkable geomorphological feature in southern Egypt. It is unique and its geodynamic formation is still not fully understood. This study addresses the relationship between the bend geometry and the structural setting of the underlying basement complex using remotely sensed and aeromagnetic data. The hillshade and drainage extraction algorithms were applied to the digital elevation model (DEM) of the Shuttle Radar Topography Mission (SRTM) to define the lineaments dissecting the limestone plateaus and control the Nile Valley cliffs. Moreover, the Interferometry Synthetic Aperture Radar (InSAR) coherence image was derived from two Sentinel-1 images to delineate and/or confirm the structures, which underlie and control the sand dunes movement. In addition, various edge-detection derivatives were applied on the reduced-to-pole (RTP) aeromagnetic anomaly to define the basement structures. The results showed the derived surface and subsurface structures are controlled by the NW–SE and NE–SW trends of the Suez–Red Sea, Aqaba–Dead Sea, and Qena–Safaga Shear Zone. The RTP anomaly reveals a strong NE–SW positive anomaly zone coinciding with the bend. The magnetic 2D forward modelling and 3D depth inversion suggest the basement consists of granitic rocks (0.02 – 0.033 cgs) and the positive anomaly below the bend probably attributes to a major uplift at a depth of 750 m. This uplift broke the plateau forming NE–SW-oriented weak structural zones along which the bend was developed.

Yanshanian (ca. 200–100 Ma) metallogeny of eastern Asia was dominantly controlled by oblique subduction and rollback of the Izanagi plate, and also, more locally in the north, by closure of the Mudanjiang Ocean basin and accretion of the Bureya-Jiamusi-Khanka block and the Sikhote-Alin terranes. Although exact distances are difficult to estimate due to Early Cretaceous crustal extension, ores related to Yanshanian subduction certainly developed for more than 1500 km landward from the active trench, such as exemplified by those deposits overprinting the Paleoproterozoic Trans-North China orogen. In the northern part of the Yanshanian orogen, and thus hosted within the eastern edge of the Central Asian orogenic belt, Endako-type porphyry Mo deposits related to subduction of the Mudanjiang slab formed throughout northeast China from 200 to 135 Ma. Extensional magmatism related to rollback of the slab led to widespread Au-Ag epithermal vein development and a scattering of small Cu-Au porphyry occurrences across the same area from 125 to 100 Ma. Sinistral strike-slip motion along the continental margin in adjacent Russia, caused by the NNW motion of the Izanagi plate, led to formation of 115–95 Ma post-collisional Cu-Au porphyries, Sn-W ores associated with reduced intrusions, and orogenic gold deposits in the central Sikhote-Alin region. In the North China block, whereas early Yanshanian ore formation was relatively limited, 130–120 Ma extension-related basement uplifts were associated with formation of two of China’s most important orogenic gold provinces on the Jiaodong Peninsula and in the East Qinling; in the latter, the entire period of late Yanshanian extension may be defined by widespread 148–107 Ma Mo-rich porphyry and skarn deposit formation. To the south along the Asian margin, the oblique NW-directed subduction of the Izanagi slab was responsible for the adakitic porphyry Cu deposit formation on the eastern side of the South China block at 175–155 Ma, which continued inland for as much as 500 km to the Cathaysia-Yangtze suture. The transition at 160–150 Ma to development of the Nanling W-Sn belt in the interior of Cathaysia roughly overlaps the time of tectonic switch to slab retreat, which gradually led to seaward migration of the extension-related magmatism forming the 145–133 Ma Sn ores and 110–100 Ma high to low sulfidation epithermal deposits along the Southeast Coast belt. A period of sinistral strike-slip along the southern end of the Tan-Lu fault system was possibly responsible for a tear in the Izanagi plate and consequential S-type magmatism forming W porphyry-skarn ores of the Jiangnan belt at 145–133 Ma and I-type magmatism leading to Fe-Cu-Au skarns at the northern edge of the Yangtze block. In summary, the early Yanshanian of eastern Asia was dominated by widespread subduction-related porphyry Mo formation in the north and localized porphyry Cu formation to the south, followed by late Yanshanian development of world-class Au, Mo, Sn, and W resources during subsequent slab retreat, continental-scale extension, and strike-slip events along continental margin transform faults.

The fault-bounded Nashoba–Putnam terrane, a metamorphosed early Paleozoic, Ganderian arc/back-arc complex in SE New England, lies between rocks of Avalonian affinity to the southeast and middle Paleozoic sedimentary rocks, interpreted as cover on Ganderian basement, in the Merrimack belt to the northwest. U–Pb detrital zircon laser ablation inductively coupled plasma mass spectrometry analysis were conduced on six samples from the Nashoba terrane in Massachusetts and seven samples associated with the Merrimack belt in Massachusetts and SE New Hampshire to investigate their depositional ages and provenance. Samples from the Nashoba terrane yielded major age populations between ~560 and ~540 Ma, consistent with input from local sources formed during the Ediacaran–Cambrian Penobscot orogenic cycle and its basement rocks. Youngest detrital zircons in the terrane, however, are as young as the Early to Middle Ordovician. Six formations from the Merrimack belt were deposited between ~435 and 420 Ma based on youngest zircon age populations and crosscutting plutons, and yielded large ~470–443 Ma age populations. Three of these formations show only Gondwanan provenance. Three others have a mixed Gondwanan-Laurentian signal, which is known to be typical for younger and/or more westerly sedimentary rocks and may indicate that they are the youngest deposits in the Merrimack belt (late Silurian to early Devonian) and/or have been deposited in the equivalent of the more westerly Central Maine basin. Detrital zircon age populations from the Tower Hill Formation, along the faulted contact between the Merrimack belt and Nashoba terrane, are different from either of these tectonic domains and may indicate that the boundary is complex., Le terrane limité par des failles de Nashoba-Putnam, un complexe d’arc/arrière-arc métamorphisé gandérien du Paléozoïque précoce dans le sud-est de la Nouvelle-Angleterre, se trouve entre des roches ayant une affinité avalonienne au sud-est et des roches sédimentaires du Paléozoïque moyen, interprétées comme une couverture du socle gandérien, dans la ceinture de Merrimack au nord-ouest. Six échantillons provenant du terrane de Nashoba au Massachusetts et sept échantillons associés à la ceinture de Merrimack au Massachusetts et dans le sud-est du New Hampshire ont fait l’objet d’une analyse par spectrométrie de masse avec plasma à couplage inductif et par ablation par laser de datation U–Pb sur zircon détritique aux fins de l’examen de leurs âges sédimentaires et de leur provenance. Les échantillons provenant du terrane de Nashoba ont révélé des populations principalement âgées entre environ 560 et 540 Ma, ce qui correspond à la contribution des sources locales apparues durant le cycle orogénique édiacarien-cambrien de Penobscot et aux roches de son socle. Les zircons détritiques les plus récents dans le terrane remontent cependant seulement à l’Ordovicien précoce à moyen. Six formations de la ceinture de Merrimack se sont déposées à peu près entre 435 et 420 Ma selon les populations des âges les plus récents sur zircon et les plutons transversaux, et elles ont présenté de vastes populations âgées d’environ 470 à 443 Ma. Trois de ces formations témoignent uniquement d’une provenance gondwanienne. Trois autres évoquent de façon mixte le Gondwanien et le Laurentien, ce qui est reconnu comme un trait typique des roches sédimentaires plus récentes ou plus à l’ouest et qui pourrait révéler qu’il s’agit de dépôts plus récents dans la ceinture de Merrimack (du Silurien tardif au Dévonien précoce) ou qui se seraient mis en place dans l’unité équivalente du bassin plus occidental du centre du Maine. Les populations d’un âge sur zircon détritique de la Formation de Tower Hill le long de la zone de contact faillé entre la ceinture de Merrimack et le terrane de Nashoba diffèrent de l’un et l’autre de ces domaines tectoniques et pourraient indiquer que leur limite est complexe.

Clastic units unconformably overlie the metamorphic basement of the northern and western parts of the Sakar-Strandzha Zone (SASTZ) in southeast Bulgaria, with suspected late Paleozoic-early Mesozoic depositional ages. In this article, we present new geochemical data and U–Pb detrital zircon geochronology for ten samples from these clastic units. The sedimentary textures are preserved despite the rocks experienced a very-low to low-grade metamorphic overprint. Geochemistry reveals main compositions of arkoses-subarkoses, which have similar trace element and REE characteristics when compared to the Late Carboniferous–Permian and Middle Triassic magmatic bodies in the SASTZ. The source for the sedimentary material derived from acid magmatic rocks of recycled continental arc as demonstrated by tectonic setting discrimination. U–Pb detrital zircon geochronology revealed Late Permian (Lopingian) to Late Triassic (Carnian) maximum depositional ages of the clastic units in the range of 259 Ma to 226 Ma. The main age cluster of Carboniferous zircons (357–301 Ma) is followed in decreasing amount of Permian (298–255 Ma), Ordovician–Silurian (486–419 Ma), Cambrian (542–495 Ma), Neoproterozoic (923–549 Ma) and Triassic (249–226 Ma) age clusters. Few Meso- and Paleoproterozoic (2100–1009 Ma), Neoarchean (2670–2547 Ma) and Devonian (378 Ma and 365 Ma) zircons are present. The prominent clusters of detrital zircons are sourced from the proximal Late Carboniferous–Permian and Middle Triassic magmatic bodies, while Devonian to Cambrian zircons have their source from proximal to distal Ordovician and Cambrian magmatic bodies and the meta-sedimentary protoliths of the SASTZ metamorphic basement, from which inherited Proterozoic–Neoarchean zircons are recycled into the Late Permian to Late Triassic clastic units. The latter are correlated across the northern and western parts of the SASTZ based on their lithology and depositional ages. Most importantly, the main detrital zircon clusters testify for the destruction of the Late Carboniferous–Permian to Middle Triassic magmatic arc system of the SASTZ and related continental-type fluvial–alluvial sedimentation. The provenance from the Cadomian magmatic arc system along the northern periphery of Gondwana is a likely detrital signature for the Neoproterozoic–Cambrian zircons, whereas the provenance of the Mesoproterozoic to Neoarchean detrital zircons might be sought from the Sahara Metacraton and/or Arabian–Nubian Shield in the internal parts of Gondwana. Compared detrital zircon record of the SASTZ is similar to the same record in the adjacent Rhodope and Serbo-Macedonian zones implying a common Paleozoic paleogeographic position, but these zones differ from the detrital record in the Istanbul Zone, also adjacent to the SASTZ.

LiDAR data collected in the Coastal Plain of the Carolinas revealed numerous, mostly NW-SE-oriented lineaments that cross the Cape Fear arch, the longest of which are the 50- to 115-km-long, NW-SE-oriented Faison, Jarmantown, Livingston Creek, and White Marsh lineaments and the ~50-km-long, ENE-WSW-oriented Tomahawk lineament in southeastern North Carolina. Their interpretation is based mainly on locally incised channels, abrupt stream bends, topographic scarps, and linear areas of uplifted Coastal Plain sediments. The Precambrian to Paleozoic Graingers basin or synform in the pre-Cretaceous basement terminates to the southwest along the ~28-km-long, 3- to 7-km-wide Jarmantown high. The ~115-km-long Jarmantown lineament may be the surface expression of the previously reported Neuse fault, the location of which has been controversial. The Jarmantown and other lineaments crossing the Cape Fear arch suggest that the arch is structurally complex. Further investigation of the East Coast fault system (ECFS) along the west side of the Cape Fear arch in North Carolina revealed that it is located farther to the northwest than previously reported, thereby making it continuous with the ECFS in northeastern South Carolina where it forms a ~15° restraining bend. We postulate that the interpreted faults crossing the Cape Fear arch in southeastern North Carolina formed to compensate for the increased compression and change in volume from dextral motion along the fault bend. Holocene paleoliquefaction deposits near the coast, a vertically offset Pleistocene(?) beach ridge along the interpreted Faison fault, and Tertiary surface faults along the ECFS northeast of Smithfield, North Carolina, suggest that large Quaternary earthquakes may have occurred along the ECFS, the Faison and Neuse faults, and other interpreted faults that cross the Cape Fear arch., Des données LiDAR prélevées dans la plaine côtière des Carolines ont mis au jour de nombreux linéaments, principalement orientés du nord-ouest au sud-est, qui traversent l’arc de Cape Fear, parmi lesquels les plus longs sont les linéaments de 50 à 115 kilomètres de longueur orientés du nord-ouest au sud-est de Faison, de Jarmantown, de Livingston Creek et de White Marsh ainsi que le linéament d’une cinquantaine de kilomètres de longueur orienté de l’est-nord-est à l’ouest-sud-ouest de Tomahawk dans le sud-est de la Caroline du Nord. Leur interprétation est essentiellement basée sur des chenaux localement encaissés, des courbes abruptes de cours d’eau, des escarpements topographiques et des secteurs linéaires de sédiments de la plaine côtière soulevés. Le bassin ou pli synforme paléozoïque de Graingers dans le socle précrétacé prend fin au sud-ouest le long de la crête d’environ 28 kilomètres de longueur sur trois à sept kilomètres de largeur de Jarmantown. Le linéament d’environ 115 kilomètres de longueur de Jarmantown pourrait constituer le modelé de la faille précédemment signalée de Neuse, dont l’emplacement a fait l’objet d’une controverse. Le linéament de Jarmantown et les autres linéaments traversant l’arc de Cape Fear laissent supposer que l’arc est d’une forte complexité structurale. Une étude plus poussée du système de failles de la côte est (SFCE) le long du versant occidental de l’arc de Cape Fear en Caroline du Nord a révélé qu’il se trouve beaucoup plus au nord-ouest que précédemment signalé, ce qui en fait un membre continu du SFCE dans le nord-est de la Caroline du Sud, où il crée une inflexion de retenue d’environ 15 degrés. Nous postulons que les failles interprétées traversant l’arc de Cape Fear dans le sud-est de la Caroline du Nord se sont formées pour compenser la compression accrue et la variation du volume découlant du mouvement dextre le long de l’inflexion de la faille. Les dépôts de paléoliquéfaction de l’Holocène près de la côte, une crête de plage verticalement décalée du Pléistocène (?) le long de la faille interprétée de Faison et les failles superficielles du Tertiaire le long du SFCE au nord-est de Smithfield, en Caroline du Nord, permettent de supposer que des séismes importants pourraient être survenus au cours du Quaternaire le long du SFCE, des failles de Faison et de Neuse, ainsi que d’autres failles interprétées traversant l’arc de Cape Fear.

1. Introduction The last complete accounts of the comparative stratigraphy of the Belgian Caledonian basement, namely the Brabant Massif and the Ardenne inliers (Vanguestaine, 1992; Verniers et al., 2001, 2002) are becoming dated. Indeed, in the last 20 years, progress in the study of the Belgian Lower Paleozoic stratigraphy, but also of the global stratigraphy (Ogg et al., 2008; Gradstein et al., 2012, 2020) has greatly increased, which justifies the present work. The Caledonian basement crops out in the southern half of Belgium and neighbouring countries, where it is observed in two major tectonic units: the Brabant Parautochthon to the N and the Ardenne Allochthon to the S (Fig. 1). The latter belongs to the westernmost part of the Rheno-Hercynian domain and is close to the Variscan front. The Midi-Eifel-Aachen Thrust Fault displaced the Ardenne Allochthon several tens of km to the N, as shown by deep seismic investigations (see recent overview in Mancy & Lacquement, 2006; Meilliez & Lacquement, 2020). This northern shift is responsible for the formation of frequently overturned thrusts sheets which also incorporated Lower Paleozoic units as for example in the Condroz Inlier (e.g. Belanger et al., 2012). The Brabant Massif can be observed in the valleys that incise its southern rim but it is also present to the N under the Mesozoic and Cenozoic cover. In the Ardenne Allochthon the Caledonian basement is exposed in four inliers: Stavelot-Venn Inlier (SVI), Rocroi Inlier, Gi

The upper Assam shelf is a self-slope basin in north-east India, filled with nearly 7 km of sedimentary rocks of tertiary period with the granite basement and various oil fields along the border of the Naga thrust. The major producing fields are structural and strati-structural. The study area is placed in between the Mikir hills and Naga thrust. The objective of the study is to identify potential hydrocarbon reservoir zones in the geologically complex south upper of the Assam shelf using estimates of acoustic impedance and porosity derived by 3D post-stack seismic inversion. Well data, such as sonic velocity and density logs, from two wells (namely, KA and TE) are used in the inversion and validation of results. Inversion results are used to build a geological model in the form of acoustic impedance from which we derive 3D porosity cube which are used for hydrocarbon potential in the Paleocene to lower Oligocene sands, and the Precambrian basement. Although the amplitude maps provide an indication of potential reservoirs, the extent of these zones are much better identified in the inverted impedance maps and the corresponding estimated high-porosity zones. The analysis predicted the potential reservoir rocks in the Sylhet, Kopili and Barail formations, in which the Sylhet and Kopili appear to have good potential zones. Near the vicinity of the Naga thrust belt, the proximity of potential reservoir is predicted in the Kopili, Sylhet formation and in the fractured basement, respectively.

The Main Ethiopian Rift (MER), where active continental rifting creates specific conditions for landslide formation, provides a prospective area to study the influence of tectonics, lithology, geomorphology, and climate on landslide formation. New structural and morphotectonic data from central Main Ethiopian Rift (CMER) and southern Main Ethiopian Rift (SMER) support a model of progressive change in the regional extension from NW–SE to the recent E(ENE)–W(WSW) direction, driven by the African and Somali plates moving apart with the presumed contribution of the NNE(NE)–SSW(SW) extension controlled by the Arabian Plate. The formation and polyphase reactivation of faults in the changing regional stress field significantly increase the rocks' tectonic anisotropy, slope, and the risk of slope instabilities forming. According to geostatistical analysis, areas prone to landslides in the central and southern MER occur on steep slopes, almost exclusively formed on active normal fault escarpments. Landslide areas are also influenced by higher annual precipitation, precipitation seasonality, vegetation density, and seasonality. Deforestation is also an important predisposition because rockfalls and landslide areas typically occur on areas with bushland, grassland, and cultivated land cover. A detailed study on active rift escarpment in the Arba Minch area revealed similar affinities as in a regional study of MER. Landslides here are closely associated with steep, mostly faulted, slopes and a higher density of vegetation. Active faulting forming steep slopes is the main predisposition for landslide formation here, and the main triggers are seismicity and seasonal precipitation. The Mejo area situated on the uplifting Ethiopian Plateau 60 km east of the Great Rift Valley shows that landslide occurrence is strongly influenced by steep erosional slopes and a deeply weathered Proterozoic metamorphic basement. Regional uplift, accompanied by rapid headward erosion forming steep slopes together with unfavourable lithological conditions, is the main predisposition for landslide formation; the main triggers here are intense precipitation and higher precipitation seasonality.

The Quaternary volcanogenic landscape and the volcanogenic sediments of the Netherlands Antilles (NA) (Aruba, Bonaire, Curacao) reflect the most recent stage of the evolution of the Cretaceous to early Cenozoic Great Arc of the Caribbean Plate. They provide a “geoscientific keyhole” to look at its geodynamic and lithological evolution at different scales. This sedimentological, micropaleontological, geomorphological/geo-morphometrical, litho-chemical and mineralogical approach, holistic in essence and focused as to the target, can also be taken to better understand other volcanic arcs or facies zones, e.g., in Colombia. It allows for a climatic-geomorphological zonation governed by uplift and erosion of the volcanic arc in time and space. The host rock quality of landforms for volcanogenic sediments abundant in heavy minerals (HM) that are known as the most suitable markers for provenance and geodynamics can be arranged in decreasing order of significance as follows: coastal-marine volcaniclastic > fluvial–marine (deltaic) > aeolian-coastal-marine > mass wasting > residual > coastal-marine calcareous. The coastal sediments facing towards the plate margin contain Cr–Fe–Ti–Nb–Th–U–Zr-bearing HM which derived from off-shore ophiolites, Precambrian shelf sediments of the South-American Plate, volcanic–subvolcanic units, and mantle source rocks. The Quaternary hydrography evolved on different erosion levels and exposes different basement lithologies of volcanic and subvolcanic type. The drainage system is controlled by faulting (tecto-variance) and the volcanic lithologies (litho-variance) both of which indicate different phases of tectonic and magmatic activity during arc emplacement. This in-active volcanic arc of the Netherlands Antilles has been shaped during the Cenozoic by the climate change and modern tectonics on a deeper level of erosion than the active volcanic arc of the Lesser Antilles.

We present pore-fluid geochemistry and heat-flow data along the SWIM1 fault in the Horseshoe Abyssal Plain (northeastern Atlantic Ocean). The SWIM1 fault is part of the transcurrent plate boundary between Africa and Eurasia and cuts through as much as 5-km-thick sediments overlying >140 Ma oceanic lithosphere. In a number of places, restraining segments (as long as 15 km) of the SWIM1 fault generate anticlines (positive flower structures) that protrude as ∼100-m-high hills above the abyssal plain. Heat flow and gradients of dissolved constituents in pore water are enhanced at these seafloor highs. Transport-reaction modeling confirms that slow advection of deep-seated fluids, depleted in Mg and enriched in Sr and CH4, can explain the observations. The geochemical signature is similar to the one observed at deep-sea mud volcanoes located eastward on the SWIM1 fault. The upward-migrating fluids have interacted with carbonate rocks at maximum 5 km depth, which represent the oldest sedimentary unit on top of the basement. We argue that deep-rooted fluids can generally be mobilized and transported upward along flower structures that formed in restraining-bend segments of long strike-slip faults. Such tectonic settings represent largely unrecognized corridors for mass exchange between lithosphere and ocean.

The Khanka Massif, as the easternmost micro-massif of the Central Asian Orogenic Belt, its tectonic attributes and Paleozoic tectonic evolution remain controversial. In this paper, we present detrital zircon U–Pb age data for sedimentary rocks from the Huangsong Group, in order to provide constraints in this regard. The Huangsong Group has previously been described as the Precambrian basement of the Khanka Massif, consists of slightly metamorphosed sedimentary rocks, and from bottom to top is divided into the Yangmu and Yanwangdian suites. Unexpectedly, the depositional ages of the Yangmu suite are (from bottom to top) 220–205 Ma, 249–239 Ma, and 509–485 Ma. The depositional ages of the Yanwangdian suite are (from bottom to top) 426–390 Ma and 232–220 Ma. Clearly, the rocks do not have a logical stratigraphic sequence and, therefore, we propose that the “Huangsong Group” represents a stack of tectonic terrains with diverse ages (early Paleozoic to early Mesozoic) rather than a continuous sedimentary sequence. The potential sediment sources were mainly a nearby magmatic arc and batholiths, because the zircons are euhedral–subhedral, exhibit well-developed oscillatory zoning, and have high Th/U ratios. The occurrence of Precambrian detrital zircon grains implies the existence of remnants of Precambrian basement along the western margin of the Khanka Massif in the early Paleozoic. A comparison of magmatism in the regional massifs revealed there was a tectonic affinity between the western margin of the Khanka Massif and eastern margin of the Songnen–Zhangguangcai Range Massif in the Paleozoic. Based on the detrital zircon age populations and trace element contents, we conclude that the western Khanka Massif experienced a change from a stable to an active margin setting during the late Paleozoic, which was caused by subduction of the Paleo-Asian oceanic lithosphere.

Integrated analyses of in situ zircon U-Pb ages and geochemistry were conducted on both granitic and metasedimentary borehole samples from immediately below the Cenozoic sedimentary cover of the northern South China Sea basin. Our work suggests that basement rocks of the South China Sea basin are not Proterozoic or Paleozoic rocks, as previously speculated based on gravity-magnetic inversion work. The analyzed metavolcaniclastic and metasedimentary rocks were likely deposited at or soon after ca. 145 Ma but prior to ca. 85 Ma. A nearby source in coastal South China is proposed based on the generally immature nature of the metasedimentary rocks and the lack of detritus from older basement rocks farther inland. The vast majority of the metavolcaniclastic samples have sparse ca. 250–190 Ma (particularly 200–190 Ma) zircons. This magmatic quiescence is consistent with the existence of a coastal magmatic gap to the east of Hainan Island during this time, previously interpreted as reflecting a period of flat-slab subduction. Metaclastic samples mostly exhibit a dominant ca. 180–120 Ma zircon population, indicating extensive magmatism along the coastal areas. This finding, together with previously reported ca. 190–180 Ma I-type coastal granites and our newly dated ca. 115–98 Ma volcanic and granitic rocks under the western part of the South China Sea basin can best be interpreted by the former presence of an Andean-type continental arc during the Middle Jurassic – Early Cretaceous. Magmatism along this arc ceased soon after 90 Ma or before ca. 85 Ma, with its last pulse represented by a small group of ca. 100–85 Ma granitic intrusions in the eastern part of the northern South China Sea basin. The arc appears to have jumped toward the Western Pacific Ocean at or soon after 90 Ma, starting the development of the Western Pacific-type plate margin.

A deep excavation should be designed and implemented together with the precautions to prevent any loss of stability and structural damage in the infrastructure and superstructure elements of the neighboring parcels and risks against construction worker's health and safety. This study represents an example of soil damage that may occur due to foundation excavation. The features of the soil affected by the excavation were analyzed through a geological survey and soil models were created for each analysis stages. The study investigates the slope stability analyses that take place during the foundation excavation with the commonly used limit equilibrium (LE) methods. In this article, slope problems that may occur around the excavation before the construction of the basement of a 3-storey school building in Istinye Neighborhood of Istanbul Sarıyer district are examined. First, geotechnical and structural parameters were determined by obtaining detailed drilling reports of the region. Then the study area was modeled with the Rocscience Slide 6.0 program based on the limit equilibrium method. Following the evaluation of the basement excavations, a beveled excavation was made for the safety of the basement construction after the excavation and the stability of the slope excavations was found to be sufficient.

Resistivity measurements were carried out to delineate the depth of the basement rocks (bedrock) and the lithology of the overlying sediments for the purpose of bridges construction route. The survey was conducted at three sites: Andro, Duma and Manwashi, north Nyala, Southern Darfur State, Western Sudan. These sites (Andro, Duma and Manwashi ) are located along Nyala _ El-Fashir road at a distance approximately of 15km, 42km and 75km from Nyala (respectively). The surface geology of the area is dominated by the basement complex rocks which are overlain by thin layer of superficial deposits The modeling of the VES data was done using IX1D software. The final results of the modeled and interpreted resistivity data are presented in the form of geoelectrical sections. These sections have shown a close agreement with the geological and hydrogeological conditions of the area. Three zones were identified in these sections, they are the top dry zone (3m) representing the superficial deposits, the middle zone (Saturated zone) represents the groundwater aquifer. It varies in lithology from weathered and cracked basement rocks to the Alluvial deposits with a significant heterogeneous nature which varies from clayey, silty, sandy, pebbly and boulders layers. The bottom zone (Fresh basement rocks) represents the bedrock. It indicate an increase of hardness and compaction from Andro , Duma and Manshawi sites respectively. These findings can be used successfully for constructions the bridges of the three sites.

Reactivation of pre-existing structures and their influence on subsequent rift evolution have been extensively analysed in previous research on rifts that experienced multiple phases of rifting, where pre-existing structures were deemed to affect nucleation, density, strike orientation, and displacement of newly formed normal faults during later rifting stages. However, previous studies paid less attention to the extensional structures superimposing onto an earlier compressional background, leading to a lack of understanding of, e.g. the reactivation and growth pattern of pre-existing thrust faults as low-angle normal faults and the impact of pre-existing thrust faults on newly formed high-angle faults and subsequent rift structures. This study investigating the spatial relationship between intra-basement thrust and rift-related faults in the Enping sag, in the northern South China Sea, indicates that the rift system is built on the previously deformed basement with pervasive thrusting structures and that the low-angle major fault of the study area results from reactivation of intra-basement thrust faults. It also implies that the reactivation mode of basement thrust faults is dependent on the overall strain distribution across rifts, the scale of basement thrust faults, and the strain shadow zone. In addition, reactivated basement thrust faults influence the nucleation, dip, and displacement of nearby new faults, causing them to nucleate at or merge into downwards it, which is representative of the coupled and decoupled growth models of reactivated thrust faults and nearby new faults. This work not only provides insights into the growth pattern of rift-related faults interacting with reactivated low-angle faults but also has broader implications for how basement thrust faults influence rift structures, normal fault evolution, and syn-rift stratigraphy.

This research work is aimed electrical resistivity survey for groundwater development conducted in Mubi and Maiha local government area of Adamawa State, in order to delineate the groundwater potential zones and determining the depth and thickness of sediments layers, and recommend suitable depth for drilling. Fourteen vertical electrical soundings (VES) were carried out within the study area using Schlumberger electrodes configuration was used for the field data acquisition. The field data obtained was analyzed using IX1D computer software and, VES1-14 resistivity model indicate 3-4 layered earth models. The interpretation shows positive inference in terms of a well-defined weathered basement and as such, it is likely to possess requisite hydro-geological characteristics that could supply underground water in fair quantity to well when drilled. Therefore, VES number denoted (R) are recommended for drilling at approximate depths of 40±5 to 50±5 meters.

A large anticline structure that includes the West Azov and Remivka blocks occurs in the western part of the Azov Domain of the Ukrainian Shield. These blocks are composed of rocks of the Mesoarchean (3.2-3.0 Ga) granite-greenstone association and relics of an older basement. The anticline is divided into two parts by the Bilotserkivka structure of sub-latitudinal strike; the northern part includes the Huliaipole and Remivka blocks, and the southern part is comprised of the Saltycha anticline. The Archean plagiogranitoids of the West Azov underwent intense dislocation metamorphism during the Paleoproterozoic. In many areas they were transformed into plagioclase gneisses that were attributed to the Paleoarchean “Kainkulak thickness” of the Azov Series. Detailed geological-structural and geochronological studies are required to define the age of these gneisses.We have chosen two areas for our studies: the Lantsevo anticline within the Bilotserkivka structure, and the Ivanivka area in the eastern part of the Saltycha anticline. The Bilotserkivka structure is composed of rocks of the Central Azov Series and highly deformed Archean formations. We have dated plagiogneisses of the Lantsevo anticline. These rocks contain large relics of metamorphic rocks of unknown age, including two-pyroxene and pyroxene crystalline schists, and pyroxenemagnetite quartzites (BIF). In terms of chemical composition, two-pyroxene crystalline schists correspond to tholeiitic basalts and basaltic komatiites. Ferruginous-siliceous rocks belong to the Algoma type typical for the Archean greenstone belts. Biotite gneisses are similar to the medium-pressure tonalite-trondhjemite-granodiorite rocks (TTGs). The U-Pb age of zircon crystallization from biotite gneisses is 3299 ± 11 Ma. At 30 km in the western part of the Bilotserkivka structure, we have previously identified quartz diorites having an age of 3297 ± 22 Ma. In terms of geochemical characteristics, they correspond to low-pressure TTGs. These data show that the Bilotserkivka structure is a block representing an ancient basement. In the Ivanivka area in the eastern part of the Saltycha anticline, the strike of the Archean rocks was reorientated from northwestern to latitudinal. The studied dislocated trondhjemites of the Ivanivka area correspond to TTGs in terms of the geochemical characteristics. They contain numerous relics of highly altered amphibolites. The U-Pb age of zircon crystallization from trondhjemite is 3013 ± 15 Ma. These rocks are of the same age as TTGs of the Shevchenko Complex cutting through the sedimentary-volcanogenic rocks of the greenstone structures of the Azov Domain. They share age and geochemical characteristics with biotite and amphibole-biotite gneisses of the “Kainkulak thickness” in Zrazkove village located at the Mokra Konka river (3.1-3.0 Ga) and with biotite gneisses in the lower reaches of the Kainkulak river (2.92 Ga). Thus, gneisses of the “Kainkulak thickness” in fact represent the Mesoarchean TTGs of the Shevchenko Complex, which were transformed in the Paleoproterozoic time due to the dislocation metamorphism. Late Paleoarchean (3.3 Ga) tonalites are known in the West Azov and the KMA domains; they probably also occur in the basement of the Middle Dnieper domains, where detrital zircons of this age have been reported. These data allow us to conclude the existence of a large Late Paleoarchean (3.3 Ga) protocraton, in which the Mesoarchean (3.2-3.0 Ga) greenstone belts and TTGs of the eastern part of the Ukrainian Shield and the KMA Domain were formed.

Introduction: We considered the general principles of creating complex geophysical models for the lithosphere of the central part of the East European Craton and the role of geothermal models in such models. In order to form a reliable initial estimate for a thermal model of the upper crust, we generalised the data on the content of heat generation elements in the rocks of the Early Cambrian basement. Initial data: We studied the peculiar features of the total content of rare and scattered elements obtained using the method of inductively coupled plasma atomic mass spectrometry in the samples of typical rocks of the studied region. A consolidated database was compiled for the content of heat generation elements (potassium, thorium, uranium) and the total content of silica in typical rocks of the crystalline basement of the craton. Assessment of heat generation of the basement rocks: We calculated the heat generation of the crystalline basement rocks in the area based on the initial data on the concentration of radiogenic elements. To assess the values of heat generation, we used the data on the density of the rocks of the basement of the East European Craton and its individual parts. The obtained results of the assessment of heat generation characterise the upper inhomogeneous part of the basement extending to the lower border of the region’s graviactive layer. Data analysis and discussion: We obtained the value of heat generation of the Early Cambrian basement rocks that varies from 0.1 to 7.54 μW/m3 with the average value of 0.528 μW/m3 . Data analysis showed that there was no correlation between the density of the region’s basement rocks and the calculated values of their heat generation. A stable connection was found between the content of silica (SiO2 ) and the value of the calculated heat generation of the rocks. As for the main groups of the basement rocks, heat generation tends to be related to the composition of the rocks, but there is no connection to the age of the formation of the rocks. Conclusions: We presented the main results of the conducted research and outlined a plan for the formation of an initial estimate for the heat generation of the upper crust in the thermal model of the region’s lithosphere.

The current article presents stratified data on physical properties of rocks and ores from the Monchegorsk ore area (Kola region). The constructed petrodensity and petromagnetic maps reflect peculiar features of changes in petrophysical parameters of both Paleoproterozoic intrusive rocks and host rocks at the Archean basement of the area. To assess the complementarity degree of physical properties of the rocks and geophysical fields, we additionally analyzed the structure of geophysical anomalies (Δg, ΔZ) in the study area. It allowed constructing a distribution scheme for geophysical heterogeneity in the area and assessing their nature. The conducted studies showed that nickel-bearing and potentially nickel-bearing intrusions in the Monchegorsk ore area were highly dense, but composed of weakly magnetic rocks. Layering of the gabbro-labradorite massif of the Main Ridge is reflected in petrophysical parameters, i. e. endocontact gabbro and gabbronorite show an increased density and magnetic susceptibility compared to leucocratic gabbro and labradorite in the core of the intrusion. Thus, petrophysical data indicate a general increase in the basicity of the rocks towards the bottom of the intrusion. The discrepancy between intense geophysical anomalies and physical parameters of near-surface rocks of the block adjacent to the gabbro-labradorite massif of the Main Ridge in the southeast was revealed. This fact indicates a layer of dense rocks under the supracrustal basement rocks (a complex of gneisses and amphibolized volcanic-sedimentary rocks) and rocks of the Imandra-Varzuga structure. This layer can be composed of potentially nickel-bearing rocks of the Imandra complex, including intrusions of the clinopyroxene-wehrlite formation series exposed in some areas. According to the configuration pattern of the identified axes of local magnetic anomalies, the Archean blocks are considered isolated areas given the uniform pattern they create, i. e. Belomorian — isometric structures, Kola — linearly extended. Therefore, during transformation of the structural plan in the Paleoproterozoic, the Archean blocks gave differentiated responses to the emerging stress-strain state of the environment and were subject to heterogeneous deformations. The performed work, including integrated results of petrophysical studies with the analysis of the structure of geophysical anomalies in the ore region, is relevant in substantiating a strategy for prospecting for new ore occurrences and patterns of their localization, as well as for developing criteria for predicting industrial ores in the region. At the same time, the studies carried out make it possible to answer questions related to the reconstruction of the geodynamic settings that took place during the formation of the region’s crust.

To provide information on best model to predict Phosphorus (P) Sorption unto Soils derived from Basement Complex Rock, Alluvium, Coastal Plain Sand and Imo Shale Parent Materials in 3 states of Nigeria. Completely randomized design was used to collect surface soil samples in 3 replications from 4 locations in Nigeria. Samples were collected from Idanre, Koko, NIFOR and Uhonmora in Ondo, Delta and Edo states Nigeria, laboratory analysis was carried out in the Central analytical laboratory of Nigerian Institute for Oil-Palm Research (NIFOR) Benin City, Nigeria between march 2016 and September 2017. Soil samples were equilibrated in 25 ml of 0.01 M CaCl2 containing various concentration of P as KH2PO4 to give 0, 50, 100, 150, 200 and 250 mg/L P for 24 hours (h) at room temperature 25 ± 2oC. 3 drops of CHCl3 was added to inhibit P mineralization. The suspension was shaken for 24 h on a reciprocating mechanical shaker, centrifuged at 7000 rpm After equilibration, decanted and P determined using spectrophotometer. The sorption data were fitted to linear Freundlich and Langmuir sorption isotherm. Considering the Freundlich model, P adsorption capacity (a) and P sorption energy (n) was highest in soils B (1400 mg kg-1) and (2.806 L kg-1) respectively. The Freundlich model fitted better to the data obtained with average root mean square error (RMSE) and R2 value of 0.69 and 0.951 respectively, as against average RMSE and R2 value of 1.60 and 0.883 respectively obtained from Langmuir model. The sorption data fitted well to Freundlich and Langmuir isotherms of which Freundlich Adsorption model was found to be better based on lowest RMSE (0.69) and highest regression (R2 = 0.951) value. Freundlich model should be adopted to determine P sorption characteristics of the soils studied. These predictors, however, need further works to validate reliability.

The southern edge of the Eyre Peninsula, experienced a separation from proto-Antarctica in the Cretaceous and has been projected to extend into Terre Adelie Craton, Antarctica. The Archaean and Palaeoproterozoic rocks of the southern Eyre Peninsula, have been modified by the Kimban Orogeny (~1730–1690 Ma) with the development of the regionally extensive Kalinjala Shear Zone, which has been correlated with the Mertz Shear Zone in Antarctica. In this contribution, new structural observations associated with the granulite facies Kalinjala Shear Zone, together with other shear zones, all showing similar kinematics of dextral top-to-the-north transport will be described. The Kimban Orogeny overprints and reworks a major lithospheric boundary between the Gawler Craton and a sequence of preceding events related to the ~ 1850 Ma Cornian Orogeny. Shear zones were initiated during the early stage of the Kimban Orogeny (KD1) in a dextral simple-shear regime, transitioning into a pure-shear (KD2) dominated regime. With shortenings of > 90% in the Kalinjala Shear Zone localized into regions containing pre-existing Tourneford Metdolerite Dykes emplaced at ~ 1810 Ma into the granites of the Donington Suite (1850–1843 Ma) and a basement of 2000–1859 Ma paragneisses. Geometrical relationships reveal the operation of oblique extrusion during the Kimban Orogeny, where a coaxial component acted sub-horizontal and orthogonal to the trend of the Kalinjala Shear Zone. Regions of low-strain and a ‘pinched-in’ and inverted sequence of Mesoproterozoic metasedimentary cover, the Hutchison Supergroup, are bounded by major km-scale shear zones with steep west-dipping tectonic contacts. Post-Kimban subvertical east–west-trending joints and faults record a rifting event which can be related to a Gondwana breakup. With post-rift Neogene fault activity recording additional tectonic episodes where pre-existing basement structures exert significant control on their orientation and distribution. Palaeogeographical reconstructions between the Eyre Peninsula and the Terre Adelie Craton, based on matching basement geology and structural style, are compared and reconciled with this new information.

The Carter-Knox field is located on a northwest-southeast–trending faulted anticline in the southeastern part of the Anadarko Basin. Three-dimensional seismic and well data were used to develop a model for the geometry and evolution of the structure. The Carter-Knox structure formed during contractional deformation associated with the Wichita basement uplift in the Pennsylvanian. It is characterized by different structural styles in two main structural units. The lower unit, which includes the Cambrian Arbuckle Group to Mississippian Sycamore Limestone, is folded into a broad anticline associated with one or more frontal faults and back thrusts, with a change in vergence along trend. The upper unit, which includes the Upper Mississippian Springer shale to the Morrowan Primrose and the overlying Pennsylvanian growth units, is marked by a tight faulted detachment fold with a steep front limb, associated with multiple thrust faults that detach within the Springer shale. Kinematic reconstruction shows differential shortening between the two main structural packages. The evolution of the structure was episodic, resulting in two major angular unconformities within the Pennsylvanian. A major Permian unconformity truncates the structure. The southwestern flank of the structure was rotated along an active flexural hinge in the basement because of sedimentary loading, resulting in thickening of growth units on this flank. The Carter-Knox structure is an analogue for other thin-skinned structures in the Anadarko Basin and illustrates the impact of the thick-skinned Wichita uplift on the thin-skinned fold-thrust structures in the basin.

We have developed a multiscale approach for solving 2D and 3D nonlinear inverse problems of gravity data in estimating the basement topography. The inversion is carried out in two stages in which the long-wavelength features of the basement are first estimated from smoothed gravity data via a stochastic optimization algorithm. The solution of this stage is used as the starting model for a deterministic optimization algorithm to reconstruct the short-wavelength features from the full-spectrum gravity data. The forward problem is capable of handling lateral and vertical variations in the density of sediments. Two cases are considered regarding prior knowledge about the density: (1) The density contrast between sediments at the surface and the underlying basement and its vertical variations are a priori known, and (2) only the density contrast at the surface is known with its vertical gradient to be recovered in the inversion. In the former case, the unknowns of the problem are the depths, whereas in the latter case, they are the depths and density gradients defined individually for each prism. Therefore, the inverse problem is ill-posed and has many local minima. The stochastic optimization algorithm uses a random initial model and estimates a coarse model of the basement topography. By repeating the stochastic inversion, an ensemble of solutions is formed defining an equivalent domain in the model space supposed to be within the neighborhood of the global minimum of which several starting solutions are extracted for the secondary deterministic inversion. The presented methodology has been tested successfully in converging to the global minima in 2D and 3D cases with 50 and 2352 total number of prisms, respectively. Finally, the inversion algorithm is used to calculate the thickness of the sediments in the South Caspian Basin using the EIGEN-6c4 global gravity model.

There is no consensus about the geological nature of the westernmost portion of the Iberian Massif. In the present research, the detrital zircon U–Pb signatures of Jurassic strata of the Lusitanian Basin, known to be west-sourced, are combined with published U–Pb data for the Precambrian-Palaeozoic basement and otherLusitanian Basin units to better understand this poorly exposed portion of the Iberian Massif. Cryogenian to Ediacaran ages prevail in a northern Upper Jurassic unit, while Lower and Upper Jurassic rocks in southern locations yield mostly Carboniferous to upper Permian zircons. These age results, coupled with their respective U/Th ratios, suggest that the basin covers two distinct terranes of the Iberian Massif. Another noteworthy feature of west-derived deposits is the abundance of < 310Ma ages. It is proposed that a combination of crustal thinning in the West Iberian Margin with regional eastward basement tilt, favoured the enrichment of relatively young zircon in the western shoulder of the basin relative to its eastern margin. The detrital zircon age signatures also reveal a middle to late Permian thermal event in restricted areas, which is probably associated with the oldest stages of Alpine extension in West Iberia.

Twenty-two Vertical Electrical Sounding (VES) were carried out to evaluate groundwater potential and aquifer protective capacity of the overburden units using Schlumberger configuration. It was observed that H-curve is the dominant curve type in the study area. The Geo-electro stratigraphic section revealed that the geologic sequence beneath the study area is composed of topsoil, highly weather basement, partly fractured basement and fresh basement. The first layer has an average thickness and resistivity of 1 m and 130 Ωm, respectively. The second layer has an average thickness of 14 m and an average resistivity of 53 Ωm. The third layer is partly fracture basement with an average resistivity of 747 Ωm while at some VES point represents fresh basement. The highly weathered basement and partly fracture basement layer make up the water bearing formation of the area. Dar-Zarrouk parameter revealed that the area under study has protective capacity range from weak to good capacity of the overburden material. Areas that are classified as poor and weak are indicative areas are thus vulnerable to infiltration of leachate and other surface contaminations. The groundwater potential of the area ranges from low to moderate potential; the moderate zone constitutes 86% while the low potential constitutes 14% of the study area. The transverse resistance within the study area ranges from 119.6 to 6983.7 ohms-m2 with an average value of 1024.59 ohms-m2. Hydraulic conductivity values determined from geoelectrical technique range from 3.05 to 38.04 m/day with an average value of 14.86 m/day.

В 2021 году А.А. Драгуновым при помощи системно-геодинамического дешифрирования были выявлены Восточно-Оренбургский и Западно-Оренбургский геодинамически активные очаги генерации углеводородов Оренбургского нефтегазоконденсатного месторождения. Было предположено, что ряд малых залежей юго-запада Оренбургской области также получают от них подпитку. Целью представленной работы являлась попытка проследить вышеуказанные очаги генерации углеводородов в фундаменте и осадочном чехле на основе переинтерпретации временных разрезов региональных сейсмических профилей. Методы работы. Выделение тектонических нарушений проводилось вручную с применением авторских методических приемов приближений и последовательной детализации. После чего выполнялось системное обобщение и анализ полученных результатов в свете перспектив нефтегазоносности юго-запада Оренбургской области. Результаты работы. В результате работ было рассмотрено глубинное строение очагов, отмечены сейсмогеологические особенности их обнаружения. В местах картирования очагов генерации на временных разрезах зафиксированы неотектонические разломы «цветкового» типа, хаотическая вертикально направленная локально усиленная сейсмическая запись под ними ниже отражающего горизонта, отождествляемого с породами фундамента. Прослежена связь глубинных разломов и связанных с ними новейших оперяющих разломов с солянокупольными структурами кунгурского возраста. По результатам комплексного геологического анализа структурных построений выявлена схематическая сеть неотектонических разломов фундамента, судя по которой, Оренбургское нефтегазоконденсатное месторождение и другие, более мелкие месторождения углеводородов и выявленные сейсморазведочными работами структуры юго-запада Оренбургской области имеют закономерное распределение внутри крупной радиально-концентрической структуры диаметром около 180 км. Данная структура, вероятно, представляет собой зону разуплотнения в фундаменте, в пределах которой в осадочном чехле образовались перспективные в плане нефтегазоносности структуры. Уникальное и самое крупное в пределах юго-запада Оренбургской области Оренбургское месторождение находится в центре макроструктуры, являясь, возможно, результатом работы главных очагов генерации УВ в фундаменте. Вдоль радиальных и концентрических разломов сосредоточены более мелкие месторождения углеводородов. Кроме того, Оренбургское месторождение приурочено к зоне наложения двух концентров, что, возможно, является значительным фактором при обнаружении крупных месторождений. В качестве выводов даны рекомендации для дальнейших исследований и поиска возможных геодинамически активных очагов генерации углеводородов в пределах Русской платформы In 2021, A.A. Dragunov, using system-geodynamic decoding, identified the East-Orenburg and West-Orenburg geodynamically active centers of hydrocarbon generation of the Orenburg oil and gas condensate field. It was assumed that a number of small deposits in the south-west of the Orenburg region also receive recharge from them. The aim of the presented work was an attempt to trace the above-mentioned sources of hydrocarbon generation in the foundation and sedimentary cover on the basis of reinterpretation of time sections of regional seismic profiles. Methods. The selection of tectonic disturbances was carried out manually using the author's methodological techniques of approximations and sequential detailing. After that, a systematic generalization and analysis of the results obtained was carried out in the light of the prospects for oil and gas potential of the south-west of the Orenburg region. Results. As a result of the work, the deep structure of the foci was considered, the seismogeological features of their detection were noted. Neotectonic faults of the "flower" type, chaotic vertically directed locally enhanced seismic recording under them below the reflecting horizon identified with the basement rocks were recorded in the places of mapping the generation centers on time sections. The connection of deep faults and the newest feathering faults associated with them with salt-dome structures of the Kungur age is traced. According to the results of a comprehensive geological analysis of structural structures, a schematic network of neotectonic basement faults has been identified, judging by which the Orenburg oil and gas condensate field and other smaller hydrocarbon deposits and the structures identified by seismic surveys in the southwest of the Orenburg region have a regular distribution within a large radial-concentric structure with a diameter of about 180 km. This structure probably represents a zone of decompression in the foundation, within which promising structures in terms of oil and gas potential were formed in the sedimentary cover. The Orenburg deposit, which is unique and the largest within the south-west of the Orenburg Region, is located in the center of the macrostructure, possibly being the result of the work of the main centers of HC generation in the foundation. Smaller hydrocarbon deposits are concentrated along the radial and concentric faults. In addition, the Orenburg field is confined to the zone of overlap of two concenters, which is probably a significant factor in the discovery of large deposits. As conclusions, recommendations are given for further research and search for possible geodynamically active centers of hydrocarbon generation within the Russian platform.

We have developed 3D inversion models derived from airborne gravity and magnetic data, which are constrained by seismic and well data, in eastern Somaliland. The density model reveals a northwest–southeast-trending basin, 125 km long and 25 km wide and called the Dood Arale Basin. The basin comprises two subbasins separated by a basement high and is infilled by up to 2500–3200 m of sediments. Smaller and shallower subbasins are also identified to the west of Lafaweyne and northeast of Dararweyne. The density model shows that the top basement in the platform areas is at approximately 1500–1700 m in depth and shallows to approximately 300 m at the Bur Anod, Hagraajin, and Hagrin Ranges and northwest of Eil Afwein. The basement depths in these areas are more uncertain and could be deeper because they occur in areas of high gravity anomalies caused by a combination of near-surface high-density sediments and high-density plutonic bodies within the basement. The susceptibility model indicates that the basement consists of very weakly magnetized metasediments of the Inda Ad Complex intruded by three northeast–southwest-trending magnetic bodies with upper surfaces at depths of approximately 300–3000 m. These magnetic bodies are interpreted as plutonic complexes of similar age and composition to the Lower Cretaceous syenite intrusions outcropping at Gorei in the Shilah Madu Range. Seismic reflection profiles image the sedimentary sequences, but they do not clearly map the top basement or detect any of the plutonic bodies. The plutonic bodies could have controlled the location of the basin’s border faults and contributed to the high geothermal gradient recorded at the Faro Hills-1 well. The Upper Cretaceous Gumburo and Jesomma Formations in the basin could potentially have reached maturation close to and above the plutonic bodies within the center of the basin.

Early Carboniferous granitoids, distributed in the Yining and Central Tianshan blocks, Chinese western Tianshan, are important for deciphering their tectonic contexts and evolutionary history of the South Tianshan Ocean. Here we present LA-ICP-MS zircon U-Pb ages, in situ Hf isotopic data, and whole-rock geochemical data of the monzogranites and syenogranites from the Kalejun Mountains, southern part of the Yining Block, aiming to constrain their petrogenesis and geodynamic background. The results reveal that these monzogranites and syenogranites were emplaced at 356 Ma and 344 Ma, respectively. Geochemically, they are characterized by high SiO2 (68.74-75.76 wt.%) and K2O (4.58-6.18 wt%), low MgO (0.14-0.76 wt.%) and P2O5 (0.04-0.24 wt.%) contents. In addition, they are depleted in Ba, Sr, Eu, Ti, Nb, and Zr, and enriched in Rb, Cs, Th, and U. These features indicate that the Kalejun granites are high-silica I-type granites. The low positive epsilon(Hf)(t) values (+1.1 to +8.2) and old T-DM2(Hf) model ages (1294 to 827 Ma) of the studied zircons imply that the parental magma of these granites were derived from the reworking of Proterozoic basement with minor involvement of juvenile materials. Combined with the Late Devonian to Early Carboniferous magmatic activities in the Yining and Central Tianshan blocks (e.g. the discovery of A-type bubble rhyolites and high-Mg andesites), it is suggested that the Kalejun granites were likely related to the roll-back of the South Tianshan oceanic slab. Finally, we argue that the subduction of South Tianshan Ocean probably terminated at the end of the Early Carboniferous.

The article briefly describes current understanding of the tectonic regime of study area. It is related to the field geological practice of students of Industrial University of Tyumen. Study area is located at the western edge of Sukhoi Log town, Sverdlovsk region. The relevance of the work is related to the educational process. Information about the geological structure of the Devonian and Carboniferous formations of study area is collected. Some of the most characteristic outcrops of Paleozoic are described. Actual information about the Ural mountain genesis is given. The list of studied objects includes the outcrop of Eifelian reefal limestones near to the Shata waterfall and the ruins of a volcano. According to other researchers, it is a part of Middle Devonian volcanic arc, which was formed over the subduction zone. Here the Ordovician-Silurian Paleouralian Ocean were subducted under the collage of different-age terrains and paleocontinents (Paleozoic basement of the modern West Siberian Plate). A possible section across the Middle Devonian subduction zone of study area is presented. Similar objects associated with the oil and gas are known in the Pre-Jurassic basement of Western Siberia. The limestones and volcanic massifs exposed near the Sukhoi Log are good natural equivalents of the objects of oil and gas exploration in Western Siberia.

[The Andean cordillera, the Himalayan collisionorogen, and the Apennine thrust belt are archetypes of different orogens associatedwith different sedimentary basins. Sediment storage capacity, maximum inforedeeps where slab retreat induces rapid subsidence of the downgoing plate, isminimum in broken retroarc basins where flat‐slab subduction leads to basininversion and uplift of basement blocks on the overriding plate. , Abstract Central Argentina from the Pampean flat‐slab segment to northern Patagonia (27°–41°S) represents a classic example of a broken retroarc basin with strong tectonic and climatic control on fluvial sediment transport. Combined with previous research focused on coastal sediments, this actualistic provenance study uses framework petrography and heavy‐mineral data to trace multistep dispersal of volcaniclastic detritus first eastwards across central Argentina for up to ca. 1,500 km and next northwards for another 760 km along the Atlantic coast. Although detritus generated in the Andes is largely derived from mesosilicic volcanic rocks of the cordillera, its compositional signatures reflect different tectono‐stratigraphic levels of the orogen uplifted along strike in response to varying subduction geometry as well as different character and crystallization condition of arc magmas through time and space. River sand, thus, changes from feldspatho‐litho‐quartzose or litho‐feldspatho‐quartzose in the north, where sedimentary detritus is more common, to mostly quartzo‐feldspatho‐lithic in the centre and to feldspatho‐lithic in the south, where volcanic detritus is dominant. The transparent‐heavy‐mineral suite changes markedly from amphibole ≫ clinopyroxene > orthopyroxene in the north, to amphibole ≈ clinopyroxene ≈ orthopyroxene in the centre and to orthopyroxene ≥ clinopyroxene ≫ amphibole in the south. In the presently dry climate, fluvial discharge is drastically reduced to the point that even the Desaguadero trunk river has become endorheic and orogenic detritus is dumped in the retroarc basin, reworked by winds and temporarily accumulated in dune fields. During the Quaternary, instead, much larger amounts of water were released by melting of the Cordilleran ice sheet or during pluvial events. The sediment‐laden waters of the Desaguadero and Colorado rivers then rushed from the tract of the Andes with greatest topographic and structural elevation, fostering alluvial fans inland and flowing in much larger valleys than today towards the Atlantic Ocean. Sand and gravel supply to the coast was high enough not only to promote rapid progradation of large deltaic lobes but also to feed a cell of littoral sediment transport extending as far north as the Rio de la Plata estuary.]

This study investigates relicts of some granitic Gondwanan basement unexpectedly outcropping in the northwest of Central-East Iranian Microcontinent (CEIM) and incorporated into an ophiolitic melan...

[Abstract Although much is known about the interaction of faulting and sedimentation within the basins of active segmented continental rift systems, little is known about these processes within the interaction zones of varying geometries that separate the young interacting segments. We address this problem by exploring the non‐volcanic rift interaction zones (RIZ) along the humid, magma‐poor juvenile western branch of the East African Rift System (WB‐EARS). We examine the large‐scale ‘cross‐over’ relief profiles (basin‐to‐basin through‐going profiles extending across RIZs), the spatial patterns of rift‐linking faults (breaching faults), and axial stream morphology. Our results show that: (1) the RIZs are at different stages of their evolution; (2) distinct long‐wavelength 2‐D cross‐over topographic relief shapes, directionality of axial stream flow (sediment routing patterns), and breaching fault patterns characterise RIZs at the various stages of the linkage of interacting rift basins; (3) these stages include unbreached, partially‐breached, recently‐breached, and breached RIZs; (4) deforming RIZs exhibit different styles of directionality of breaching, including a unidirectional (distinct propagator and receiver segments), bi‐directional propagation (both segments act as propagators and receivers), and nucleation and outward propagation of a narrow intra‐RIZ subsidiary rift basin; (5) RIZ breaching is facilitated by overlap rift‐flank deformation, and/or rift tip propagation structures in the form of rift splaying, border fault rotation (rift‐tip rotation), and fault cluster networks and (6) the lateral propagation of breaching faults at the rift tips and flanks, facilitated by localized stress concentrations, is modulated by the extension direction and inherited basement structures. Our findings offer a broader insight into the geometries, structural, and morphological evolution of RIZs, and provide first‐order predictions of the large‐scale sedimentation patterns of humid early‐stage continental rift environments. Our models provide testable hypotheses for linking rift architecture and patterns of early stage sedimentation applicable to ancient rift basins., During the early stages of continental extension, isolated rift segments propagate laterally and interact to link‐up at RIZs. In this study, we investigate RIZs in East Africa to decipher the stages of their evolution and gain insights relevant for understanding the evolution of rift systems. ]

Oceanic crust formed at slow-spreading ridges is currently subducted in only a few places on Earth and the tectonic and seismogenic imprint of the slow-spreading process is poorly understood. Here we present seismic and bathymetric data from the Northeastern Lesser Antilles Subduction Zone where thick sediments enable seismic imaging to greater depths than in the ocean basins. This dataset highlights a pervasive tectonic fabric characterized by closely spaced sequences of convex-up Ridgeward-Dipping Reflectors, which extend down to about 15 km depth with a 15-to-40° angle. We interpret these reflectors as discrete shear planes formed during the early stages of exhumation of magma-poor mantle rocks at an inside corner of a Mid-Atlantic Ridge fracture zone. Closer to the trench, plate bending could have reactivated this tectonic fabric and enabled deep fluid circulation and serpentinization of the basement rocks. This weak serpentinized basement likely explains the very low interplate seismic activity associated with the Barbuda-Anegada margin segment above.

The Humber Margin of Newfoundland preserves the most distal exposures of Proterozoic basement in northeastern Laurentia. Age uncertainty has permitted a range of hypotheses for its origin and links to subsequent tectonic events. One hypothesis has proposed large-scale orogen-parallel displacement between basement blocks in western Newfoundland. The apparent absence of Grenville- (∼1250–950 Ma sensu lato) or Taconic-aged (∼480–450 Ma) magmatism or metamorphism on the Corner Brook Lake Block (CBLB), which are defining features of the Humber Margin, has been reconciled by restoring the CBLB to a pre-Taconic position in Labrador with >400 km of post-Taconic dextral motion along the Humber River Fault. To test this model and better define the basement and Paleozoic rifted margin of North America, we conducted a geochronological study of the CBLB and the basement of the adjacent Humber Margin at Indian Head Range using tandem in situ and isotope dilution U-Pb zircon and titanite geochronology. These basement blocks, separated by the Humber River Fault, consist of ∼1500 and ∼1250 Ma protoliths, 1140 to 1135 Ma magmatism, 1000 to 970 Ma metamorphism, and ∼607 Ma intraplate magmatism. These basement blocks are also overlain by similar late Ediacaran to Cambrian siliciclastic successions with similar detrital zircon age spectra. From this set of geological data, we conclude that the Humber River Fault did not accommodate significant orogen-parallel displacement. New basement ages and a revised compilation of detrital zircon ages from overlying rift-related deposits contribute to a geochronologic cratonic reference datum for western Newfoundland9s crystalline basement, whose protolith has a restricted age range from circa 1500 to 950 Ma. New age constraints for metasedimentary rocks are also used to document a 1250 to 1135 Ma succession at Indian Head Range and a ∼1000 Ma succession on the CBLB associated with Grenvillian orogenesis. Protracted late Grenvillian tectono-thermal events are inferred from cores and metamorphic overgrowths of ∼990 to 920 Ma detrital titanite in late Ediacaran conglomerate overlying CBLB basement.

Geological and geochemical studies of gold mineralization in Bode-Saadu axis, Southwestern Basement Complex, Nigeria have been conducted in order to study their mode of occurrence, structural settings, pattern of distribution and potential. Geological studies reveal that granite and gneiss granite are the prominent rocks in the area and exist in the north-eastern, north-western and southwestern part of the area whereas mica and amphibole schist occur as low-lying exposure. Petrographic studies reveal spatial association between gold mineralization and the fractured zones. Geochemical studies show that the gold concentration in rocks and stream sediments from the region is low with the exception of a few areas with high values ​​and is related to the occurrence of fissure in the northeast-west direction. The distribution pattern of gold in the region is skewed NE-SW, indicating that gold mineralization is structurally controlled. Keywords: Geochemical prospecting; Geological studies; Gold mineralization; Structurally controlled.

The Banchetta-Rognosa tectonic unit (BRU), covering an area of 10 km2 in the upper Chisone valley, consists of two successions referred to a continental margin (Monte Banchetta succession) and a proximal oceanic domain (Punta Rognosa succession) respectively. In both successions, Mesozoic meta-sedimentary covers discordantly lie on their basement. This paper presents new data on the lithostratigraphy and the metamorphic evolution of the continental basement of the Monte Banchetta succession. It comprises two meta-sedimentary sequences with minor meta-intrusive bodies preserving their original lithostratigraphic configuration, despite the intense Alpine deformation and metamorphic re-equilibration. Phase equilibrium modeling points to a metamorphic eclogitic peak (D1 event) of 20–23 kbar and 440–500 °C, consistent among three different samples, analyzed from suitable lithologies. The exhumation P–T path is characterized by a first decompression of at least 10 kbar, leading to the development of the main regional foliation (i.e. tectono-metamorphic event D2). The subsequent exhumation stage (D3 event) is marked by a further decompression of almost 7–8 kbar associated with a significant temperature decrease (cooling down to 350–400 °C), implying a geothermal gradient compatible with a continental collision regime. These data infer for this unit higher peak P–T conditions than previously estimated with conventional thermobarometry. The comparison of our results with the peak P–T conditions registered by other neighboring tectonic units allows to interpret the BRU as one of the westernmost eclogite-facies unit in the Alps.

The timing of the opening of the West Paleo-Tethys Ocean in Eastern Alps remains unclear. To constrain this event, we present new zircon U-Pb ages, Hf isotopic compositions, and whole-rock major- and trace-element data for the meta-mafic rocks (amphibolites) in the southern and western Saualpe crystalline basement, Eastern Alps. Zircon U-Pb dating of three samples yield crystallization ages of 418 ± 6 Ma, 417 ± 3 Ma and 415 ± 3 Ma, indicating that they formed during the earliest Devonian. Geochemically, these meta-mafic rocks have relatively low SiO2 and MgO contents and high TiO2 contents. They are enriched in light rare earth elements (LREE), particularly in Nb and Ta, and show relatively flat heavy rare-earth elements (HREE) patterns, suggesting that they have affinities with the alkaline oceanic island basalts (OIB). The geochemical characteristics, together with the positive eHf(t) values of 0.7–11.1, imply that the OIB-like meta-mafic rocks originated from partial melting of a lherzolite source including spinel and garnet. The primary magma shows complex sources involving asthenospheric, lithospheric mantle and subducted slab components, which was subsequently modified by crustal contamination. This reveals that the magma formed in a slab window environment associated with mid-ocean ridge subduction. The contemporaneous OIB-like alkaline amphibolites were also found in the Central Austroalpine basement and in Northwestern Turkey. We suggest that the Late Silurian–earliest Devonian OIB-like magmatism is related to a back-arc extension setting along the northern margin of Gondwana leading to the separation of the European Hunic terranes and hence placing age constraints on the opening of the West Paleo-Tethys Ocean.

Research subject. Brachiopods from the core of the Kurgan-Uspenskaya-1 parametric borehole. The borehole was drilled in the south of Western Siberia 80 km southeast of the Kurgan town. Brachiopods were collected at a depth of 1,525.4 m in the IV tectonic block (core interval 1,450–1,794 m) in the greenish-gray marls of the Famennian stage of the Upper Devonian.Materials and methods. The paleontological material is presented in the form of complete undamaged shells and individual valves of small- and medium-sized brachiopods. The safety of brachiopods makes it possible to determine their species and genera, sometimes in open nomenclature. The article provides a brief description of the available material.Results. 11 species of brachiopods of the subtype Rhynchonelliformea belonging to six orders and nine genera were identified. The following ten species were described: Orbinaria fallax (Pand.), Semiproductus amplus Bubl., Schuchertella sp., Dalejina? sp., Camarotoechia panderi (Sem.et Moell.), C. volucera Nal., Athyris tobolica Nal., Cleiothyridina tenuilineata (Row.), Cl. ex gr. pectinata (Sem. et Moell.), Retzia? sp. The presented information allows conclusions about the age of the sediments enclosing the brachiopods under study and expands the existing knowledge of both the composition of the Upper Famennian brachiopods of the basement of the south of Western Siberia and their geographical and stratigraphic distribution.Conclusion. An analysis of the stratigraphic distribution of the described brachiopods taking into account data on foraminifera allowed us to determine the age of the host rocks as the very top of the Famennian stage. The composition of the brachiopods allows these rocks to be correlated with coeval deposits of the East European Platform, Timan, the Urals, Kuzbass, the Gorny Altai, Kazakhstan and North America.

Research subject. The Riphean paleorift system of the White Sea, most of which is overlain by the waters of the White and Barents Seas and the platform cover of the East European Platform. This allowed numerous researchers to classify it as an aulacogen. The system was revealed by geophysical methods in the relief of the crystalline basement of the platform in the form of a frame of deep extended trenches of northwestern strike, subparallel to the edge of the East European platform.Materials and methods. Personal observations of the authors within the Onega-Kandalakcha paleorift, Baikal rift zone; a detailed study of seismostratigraphic sections of these zones; extensive literature data on the structure of modern rift zones. A comparative analysis of the structure of the most studied and currently active Baikal and East African rift systems, as well as the Karoo rift system of the Late Paleozoic origin with the paleorift system of the White Sea.Results. The following types of structural parageneses, which are characteristic of both modern rift systems and ancient paleorift systems, were identified. 1. Genetic relationship (inheritance?) of riftogenic structures with more ancient basement structures. 2. Structural paragenesis of concentric complexes in rift propagation zones. 3. Comparability of the area of horizontal extension of the lithosphere of the White Sea paleorift system with extension zones of modern continental rifts. 4. The fundamental similarity of the structure: the complex of paleorifts of the White Sea with modern continental rift systems: the presence of long deep trough segmentation of grabens and semi-grabens separated by bridges, which were accommodation zones with polarity reversal along the strike of the rift zone, displacement of the rift relative to the mantle ledge, the existence of a gently dipping normal fault (detachment), etc.Conclusion. The riftogenic nature of the aulacogens in the northeastern segment of the East European Platform has been confirmed.

Two geophysical tools were used to delineate the configuration of the Nubian sandstone aquifer in the study area. Three hundred magnetic points were measured and analyzed to evaluate the subsurface structural setting and to trace the basement relief, which control the aquifer’s geometry. The magnetic interpretations refer to dominant faults that strike in various directions, namely N–S, NE–SW, and NW–SE. The top of the basement complex was recorded at depths of 384–1286 m, and the aquifer thickness ranged from 299 to 1169 m. Thirty vertical electrical sounding points of AB/2 with depths ranging from 1.5 to 700 m were used to estimate the parameters of the Nubian sandstone aquifer. The geoelectrical data indicate that the area consists of 5 units; the first unit is composed of sand and gravel, the second unit of ferruginous sandstone, the third unit of clay, the fourth unit of dry sandstone, and the last unit of sandstone saturated with groundwater. The groundwater in the study area is freshwater of high quality usable for all purposes.

The Sierra Nevada de Santa Marta Massif (SNSM) in the Northern Andes affords an insight into lower crustal section structural relations. This polymetamorphic basement comprises high-grade gneisses,...