Basin System Research Articles

REVIEWS OF PERSPECTIVES ON CONTEMPORARY APPROACHES AND TECHNIQUES IN FLUVIAL SYSTEMS EVALUATION AND MANAGEMENT

This paper reviews fluvial geomorphology perspectives and methodologies for environmental sustainability by exploring and discussing major concepts, themes, and methodologies. To meet the multidimensional aspect of fluvial geomorphology research, multidimensional approaches are now used. Fluvial geomorphology examines river channel morphology and how it is shaped by fluid flows interacting with erodible or resistant boundaries. Understanding equilibrium conditions and thresholds is key. A systems perspective is needed - any river segment is influenced by upstream and downstream conditions as part of an integrated drainage basin system. Field surveys, mapping, remote sensing, and GIS provide important morphological data on river planform, cross-sections, longitudinal profile features, sediment characteristics, etc. Statistical analysis helps detect spatial patterns and trends. Assessing channel changes over long periods is often necessary to fully understand contemporary fluvial processes and forms. Sediment storage and release causes significant time lags. Major human impacts include land use changes affecting hydrology, sediment budgets, channel boundaries; and infrastructure interrupting continuity. Sustainable management requires addressing root causes. Watershed level processes like water balances, erosion patterns, etc. strongly influence fluvial systems - coordinating river channel and upland catchment interventions is key. Models like SWAT, MIKE-SHE, and ANSWERS simulate hydrological processes but have limitations. They require robust spatial datasets spanning geology, topography, land use, climate, etc. Overall, a multidimensional, scale-conscious, historically contextualized assessment framework is required for evaluating fluvial systems. The review highlights techniques and datasets for such integrated diagnosis.

Environmental impacts and nitrogen-carbon-energy nexus of vegetable production in subtropical plateau lake basins.

Vegetables are important economic crops globally, and their production has approximately doubled over the past 20 years. Globally, vegetables account for 13% of the harvested area but consume 25% of the fertilizer, leading to serious environmental impacts. However, the quantitative evaluation of vegetable production systems in subtropical plateau lake basins and the establishment of optimal management practices to further reduce environmental risks are still lacking. Using the life cycle assessment method, this study quantified the global warming, eutrophication, acidification, and energy depletion potential of vegetable production in a subtropical plateau lake basin in China based on data from 183 farmer surveys. Our results indicated that vegetable production in the study area, the Erhai Lake Basin, was high but came at a high environmental cost, mainly due to low fertilizer efficiency and high nutrient loss. Root vegetables have relatively high environmental costs due to the significant environmental impacts of fertilizer production, transportation, and application. A comprehensive analysis showed that the vegetable production in this region exhibited low economic and net ecosystem economic benefits, with ranges of 7.88-8.91 × 103 and 7.35-8.69 × 103 $ ha-1, respectively. Scenario analysis showed that adopting strategies that comprehensively consider soil, crop, and nutrient conditions for vegetable production can reduce environmental costs (with reductions in global warming potential (GWP), eutrophication potential (EP), acidification potential (AP), and energy depletion potential (EDP) by 10.6-28.2%, 65.1-73.5%, 64.5-71.9%, 47.8-70.4%, respectively) compared with the current practices of farmers. This study highlighted the importance of optimizing nutrient management in vegetable production based on farmers' practices, which can achieve more yield with less environmental impacts and thereby avoid the "trade-off" effect between productivity and environmental sustainability.

Tectonostratigraphic models of an extensional back-arc basin: inferences for the evolution of the Pannonian Basin system

The subsidence history and sedimentary architecture of extensional basins are controlled by the interplay between tectonics, mantle dynamics, and climatic variations. Observations from outcrop to regional seismic scales coupled with numerical modelling techniques, including basin-scale stratigraphic, crustal-scale tectonic and mantle-scale subduction models contribute to quantify basin evolution. Here, we review and discuss both tectonic and stratigraphic applications of such models and compare them with observations from the Pannonian Basin system of Central Europe. We show that diachronous localization of back-arc extension, crustal thinning, asthenospheric upwelling and subsequent thermal relaxation are superimposed on an overall slow plate convergence. These processes result in contrasting subsidence and uplift patterns and a variable heat flow evolution in different parts of the basin system. The crustal stress-field of the subbasins does not always reflect their contrasting vertical motions. Extensional deformation generally migrates from the basin margins towards the basin centre. Structural inversion is localized along hot and weak inherited zones from the Middle Miocene to Present. Tectonic subsidence focuses sedimentation along deep depocenters, sourced by exhumed footwalls and from the neighbouring orogens. The overall post-rift sediment progradation are influenced by inherited bathymetries from the preceding syn-rift stage and by enhanced differential vertical motions.

A synproportionation-controlled hybrid hydrothermal mineralization system in the Okinawa Trough

Hybrid hydrothermal systems, in which both water-rock reactions and magmatic fluids contribute to sulfide mineralization, have recently been reported in some submarine arcs and mature back-arc basins. Owing to their high mineralization efficiency, hybrid hydrothermal systems have attracted significant attention from geologists. This study provides first clues for the identification of a novel hybrid hydrothermal system (synproportionation-controlled instead of the more common disproportionation-controlled) in the Tangyin field, Southern Okinawa Trough. The studied samples are native sulfur-type precipitates, primarily composed of elemental sulfur with minor sulfide disseminations. The distinct crystallization conditions and S isotope compositions of elemental sulfur and sulfide disseminations indicate their different genesis. The S in sulfide disseminations (δ34S = −2.7 to 1.6 ‰) is derived from water-rock reaction and subsequently influenced by fluid phase separation, which is further demonstrated by the trace element contents of pyrite (low Tl/Pb, Sb/Pb, Te/As, Te/Sb ratios). In contrast, the elemental sulfur (δ34S = 3.9 to 4.3 ‰) is formed by the synproportionation of magmatic SO2 and hydrothermal H2S from the boiled liquid. A simple two-component mixing calculation indicated that the contributions of the water-rock reactions and magmatic fluids to the Tangyin hydrothermal system were approximately equal. The higher temperature (> 350 °C) and oxygen fugacity conditions may be the key factors for the development of a synproportionation-controlled hybrid hydrothermal system in the Tangyin field. Hydrothermal systems in back-arc basins exhibit higher sulfide accumulation rates than those in mid-ocean ridges; this may be attributed to the prevalence of hybrid hydrothermal vents in back-arc settings.

Current Geological Issues and Future Perspectives in Deep-Time Source-to-Sink Systems of Continental Rift Basins

Current Geological Issues and Future Perspectives in Deep-Time Source-to-Sink Systems of Continental Rift Basins

Tectonic evolution of the early permian Junggar basin: Insights into a foreland basin shaped by lithospheric folding

Foreland basins are shaped by the sedimentary architecture and lithospheric flexure due to the sediment load, slab pull, orogenic growth, and asthenospheric mantle flow. However, it is challenging to differentiate foreland basins from rift basins due to the destructive effects of multiphase orogenesis. Situated at the core of the western Central Asian Orogen Belt, the Junggar Basin holds vital clues regarding the closure of the Paleo-Asian Ocean. There is debate regarding whether it was a compressional foreland basin or an extended rift after the closure of the surrounding oceans. Furthermore, uncertainties persist regarding the fate of the residual oceanic crust and the precise tectonic processes during the collision of the ocean-arc-continent system. Understanding the basin's style during the early Permian period is crucial for deciphering its dynamic tectonic history. This study leverages regional seismic data to reevaluate the overall structure of the Junggar Basin, providing insights into its tectonic context and the mechanisms of intraplate deformation during the early Permian period. The findings reveal significant early Permian deformation features characterized by varying strata thicknesses and unconformities, signifying continuous tectonic activity during deposition. The western and southern depressions that developed from the late Carboniferous to early Permian are in keeping with compressional dynamics and reflect a foredeep basin, while the central uplift corresponds to a forebulge. This study posits that the observed foreland basin system was shaped by lithospheric flexure at the end of the late Carboniferous and lithospheric buckling in the early Permian, which contributed to the creation of uplifted Mosuowan-Baijiahai forebulge in the interior. The Junggar Basin featured a convergent dynamic environment, although the surrounding orogen transitioned into a postcollisional orogen in the Central Asian Orogenic Belt during the early Permian.

The Cenozoic Abanico rift system: Implications of increased southward extension in the southern central Andes, in Chile

The late Eocene-Early Miocene intra-arc Abanico extensional basin represents a major feature in central Chile (∼31°-42°S). Such basin system concentrated the magmatic activity along this Andean region and hosted locally more than 3.000 m of volcanic and volcaniclastic deposits (Abanico Formation) over a southward thinning crust (<35 km thick). South of 34°30′S, major changes occur in and out of the basin realm that modify the rather regular distribution of the geological features observed northwards, namely: 1. Southward termination of the exposures of the Farellones Formation, 2. Increased presence of pre-Abanico volcanic and plutonic exposures in the basin realm, 3. Southward width increase of the basin, 4. Abrupt end in the Maule region of the Cretaceous plutonic swaths exposed in the eastern Coastal Cordillera and westward bend of the swaths of Mesozoic units, 5. Increased presence of primitive volcanic rocks in the west-side of the basin, and 6. Presence, south of 36°S, of the Cura-Mallín Formation on the east-side of the basin. These changes are caused by the oblique orientation of the Abanico basin relative to the Mesozoic structural and paleogeographic trends and are enhanced by the increased southward opening of the basin. This opening would have occurred through a westward scissors-like rotation of the block of continental crust located west of the basin, which corresponds to the present-day Coastal Cordillera south of 34°30′S. The eastern border, which is represented by the El Diablo fault, remained essentially fixed. The westward rotation is supported by the north-northeast orientation of the Mesozoic plutonic and stratified swaths south of 34°30′S. Additionally, the swaths of Mesozoic rocks are obliquely interrupted by the similarly oriented western border of the basin. Previous analogue models designed to understand the opening and closure mechanisms of an extensional basin show that greater extension and subsidence in the basin occur next to the mobile border, which in the Abanico basin was located on its west side. This observation aligns with the increased southward presence of primitive volcanic rocks, like the Colbún Formation, in the region where crustal thinning would have been greater. Analogue models show that the increased southward extension allowed the development of wider depocenters. In the Maule region, an eastern depocenter near the El Diablo fault, hosted the Early to Middle Miocene deposits of the Cura-Mallín Formation. During contraction, deeply rooted reverse faults can involve basement rocks of the basin and bring them up to the surface as observed in the Abanico basin realm in the Tinguiririca and Maule regions. This study also highlights the continuity and importance of the El Diablo fault in the configuration of the basin. It is shown that, notwithstanding the existence of major changes south of 34°30′S, this fault represents a major structural element that remained unchanged along the Andean segment comprised between ∼32° and 36°30′S separating the Cenozoic deposits to the west from Mesozoic deposits to the east. This fault can be traced continuously from, at least, the Aconcagua valley (33°S) to the Maule region (36°30′S), and most probably extends further south. Apart from separating the Cenozoic Abanico basin deposits from the Mesozoic units involved in the east-vergent Andean fold-thrust belt, its trace forms an almost straight line that connects the Palomo, Tinguiririca, Planchón-Peteroa, Descabezados, San Pedro and Rezago volcanic centers and complexes, hot-springs, and hydrothermal alterations.

Stratigraphic overview of the Neogene Transylvanian Basin, Romania

Although the Transylvanian Basin is often referred as part of the Miocene Pannonian Basin System, we point out important tectonic and sedimentary differences reflected in the stratigraphy. The Neogene of the Transylvanian Basin can be split into two tectonic megasequences: Lower Miocene and Middle to Upper Miocene. The Early Miocene onset of the back arc extension in the Pannonian Basin was not observed in the Transylvanian Basin, where shallow to deep marine sediments were deposited in a flexural basin. Diverse types of facies developed in the continental (e.g., Sânmihai) and marine (e.g., Coruş, Chechiş, Hida) Lower Miocene formations. Although these are poorly constrained to the standard biostratigraphy, recent 87 Sr- 86 Sr data support their limited correlation with the Burdigalian. The Middle Miocene extension in the Transylvanian Basin is very weak compared to that the Pannonian Basin. As the high-resolution Middle Miocene regional biostratigraphy of the Badenian and Sarmatian was calibrated by magnetostratigraphy and radiometric dating of the volcanic tuffs up to the Serravallian/Tortonian boundary, the influence of the regional tectonics on the basin's evolution and stratigraphy can be better understood. The regional tectonics produced a progressive basin isolation starting with the late part of the Middle Miocene. The uplift of the Carpathians isolated the basin at the beginning of the Pannonian and initiated the fan delta, lacustrine, and fluvial sedimentation. The basin was rapidly uplifted and eroded, while post-extensional subsidence was still ongoing in the Pannonian Basin. Endemic fossil assemblages allow only regional-scale correlations for this interval. The uppermost part of the stratigraphic record is represented by the volcano-sedimentary formations generated by the late evolution of the Eastern Carpathians. The sedimentation and subsidence pattern of the Transylvanian Basin reflect the effect of retreating subduction zone in the Eastern Carpathians.

The Styrian Basin: an overview with new insights from seismic data

The Neogene Styrian Basin is the westernmost subbasin of the Pannonian Basin System. The last comprehensive studies on the basin were published in the last millennium. This overview of the current understanding of basin evolution is based on the re-interpretation of partly unpublished reflection seismic data and a wealth of sedimentological and stratigraphic studies performed during the last 25 years. Reflection seismic data indicate the presence of a major E to SE dipping detachment horizon within the pre-Neogene basement reflecting high-strain upper crustal extension during the early Miocene syn-rift stage of basin evolution. Fault block rotations caused subsidence in several subbasins, which developed often with marked asymmetric geometry. The maximum basin depth exceeds 4 km (Gnas Basin). Syn-rift deposits include thick alluvial fan and fan delta sediments overlain in the basin center by deeper marine pelitic rocks. Subduction-related magmatic activity commenced during the syn-rift stage and continued into the middle to late Miocene post-rift stage. Syn- and post-rift sediments are separated by the middle Miocene “Styrian Unconformity”. Shallow marine sedimentation, controlled by third- and fourth-order sea-level variations, prevailed during the early post-rift stage. The final stage of basin evolution was characterized by differential surface uplift, erosion, and Pliocene-Pleistocene basaltic magmatism.

Multivariate approach to assess groundwater resources in the multilayer system of Iullemmeden basin in Dosso Region, Southwestern Niger

The Iullemmeden basin groundwater resources were assessed in the Dosso Region for the groundwater management. Classical and multivariate tools of hydrogeochemistry were thus used to stand out main factors impacting the groundwater mineralization. The multilayer system indicates the occurrence of acidic to basic fresh groundwaters but with an excessive content in some places. Good to excellent drinking groundwaters are largely represented in the system. The categorization of groundwater patterns evolves from (i) mixed types namely Ca/Mg-HCO3, Ca/Mg-Cl, Na-Cl/SO4, Ca-Cl/SO4 and Ca/Mg-Cl/SO4 for the Ct3 particularly; (ii) to chloride types such as NaCl, CaCl and MgCl mostly for Ct1 and Ct2; (iii) and the bicarbonate types precisely Na-HCO3, Ca-HCO3, Mg-HCO3 for Ch. The weathering of silicate minerals and dissolution (carbonate and salts) are the major processes in the multilayer system. The increase of EC and salts (halite and gypsum) in Ct2 could come from the relics of ancient seawater during the last regression. In a lesser extent, fertilizers from agricultural and livestock farming also contribute to the mineralization in the study area. The groundwater assessment of the Iullemmeden sedimentary basin in the Dosso Region stands out the main factors and processes characterizing each aquifer of this system, able to useful for a better groundwater resource management.

Evaluation of distributed and semi-distributed hydrological models in complex River Basin system, Nepal

Hydrological information is essential for planning water resource projects and for simulating hydrological models to calibrate and generate streamflow data. This study evaluates the performance of distributed and semi-distributed hydrological models in the Tamakoshi River Basin (TRB), Nepal. The models assessed include the Spatial Process in Hydrology (SPHY), Hydrologiska Byråns Vattenbalansavdelning (HBV), and Hydrologic Engineering Centre Hydrologic Modeling System (HEC-HMS). The models were evaluated using metrics such as Nash-Sutcliffe Efficiency (NSE) ranging from 0.62 to 0.77, Coefficient of Determination (R2) from 0.76 to 0.77, and Percentage Bias (P Bias) from 26.16 % to −3.54 % during daily calibration. All three models were successfully calibrated and validated on a daily and monthly basis using observed discharge data at the Busti station in the TRB. The SPHY model performed better during the calibration period compared to the validation period, while the HBV and HEC-HMS models showed better performance during validation than calibration. Among the statistical indicators, the coefficient of determination closely matched, but NSE and P Bias showed some deviations. This comparative analysis of calibrated and validated models is valuable for filling gaps in hydrological data records and for selecting appropriate hydrological models for planning, managing, and developing water resource projects in the TRB.

The real McCoy: A record of deep‐water basin deposition in southwestern North America during the Cretaceous

AbstractThe McCoy Mountains Formation (McMF) in southern California–Arizona preserves an anomalously thick record of sedimentation during the Mesozoic at a critical time when western North America experienced contrasting tectonic events related to intracontinental rifting along the Mexican Border rift system and consolidation of the North American Cordilleran system. The spaciotemporal interactions among these events and the development of the McCoy basin challenge our understanding of the evolution of the southern extent of North America. At its type locality in the McCoy Mountains, the McMF consists of ~ 7 km of low‐grade metasedimentary rocks, originally interpreted as meandering fluvial to alluvial‐fan deposits. Uncertainty in the initial timing of sedimentation in the McCoy basin has resulted in multiple tectonic models. We measured ~ 7160 m of detailed stratigraphy and present new sedimentological and detrital zircon results showing that the McCoy basin was occupied by deep‐water turbidite systems. These systems deposited an upward‐coarsening succession of fine‐ to coarse‐grained detritus during the Cretaceous (ca. 137–70 Ma). Provenance data indicate that the McCoy basin received sediment from Proterozoic basement rocks and metamorphosed Palaeozoic to early Mesozoic sedimentary units. These source rocks are equivalent to the stratigraphy found in the Grand Canyon and Colorado Plateau regions and were likely shed from the southward‐advancing Maria fold‐thrust belt and possibly the southern Sevier belt in southern Nevada and California. These results, combined with subsidence curves typical of foreland basins, favour deposition within a subaqueous flexural foreland basin system. The presence of a Cretaceous foreland basin this far southwest challenges previously proposed models and suggests that the contractional tectonic regime associated with the North American Cordillera extended into the southwestern most United States during the Early–Late Cretaceous.

The role of the Messinian evaporites in the identification of potential gas storage sites: A review of the Adriatic foreland basin system (Italy)

AbstractFocusing on the late Miocene succession stratigraphic successions including the evaporite deposits from the Messinian salinity crisis (MSC) of the Adriatic foreland basin, a revision of available boreholes and seismic data allowed us to recognize the presence of reservoirs and seals systems that can be considered of potential interest for the storage of natural and synthetic gas. Potentially good reservoir sites can be found where porous rocks referable to siliciclastic turbiditites (Marnoso‐arenacea and Laga Fms) or shallow‐water carbonates (Bolognano Fm) preferentially involved in anticlinal structures and covered by thick MSC evaporites, which may represent effective reservoir seals. The integrated reconstruction of porous rocks distribution and facies, thickness, and lateral continuity of the overlying evaporites, allows the identification and zonation of geological settings in the Adriatic foredeep, backbulge and foreland with peculiar stratigraphy and deformations, only partially considered before, that may deserve consideration in the research of potential gas storage sites.

Late Palaeozoic structural evolution of the Patch Bank Ridge and Utsira High, northern North Sea

AbstractThis study focuses on the Late Palaeozoic development of the area east of Utsira High in the North Sea, where the stratigraphic section below the late Permian Rotliegend Group is undrilled. We use regional 3D seismic data to study structuring, sediment distribution and geomorphology across the Patch Bank Ridge and Utsira High in the North Sea. The results show that the Stord Basin and the bounding Utsira East fault initially developed during the Late Palaeozoic extension, probably during the Devonian, and that the Utsira Shear Zone controlled the location of Late Palaeozoic depocentres. The Patch Bank Ridge is an uplifted part of the Stord Basin where we identify Late Palaeozoic growth strata along the southern and northern flanks, indicating a similar timing of the structural evolution in this area. Two key wells, in the Sele High and Ling Depression, are used to relate a Late Palaeozoic isopach map with regional structuring, surface tilt and basement morphology to the enigmatic parts of the Late Palaeozoic basin system. Our results supplement regional models for the Late Palaeozoic basin development, we suggest that the deeply eroded Devonian half‐grabens preserved on the Utsira High formed parts of an extensive basin system that show stratigraphic expansion towards their bounding faults. The Top Basement surface at these highs offers several distinct geomorphologies that evolved during three periods of exposure, expressed as (i) a tilted and rugose landscape, (ii) distinct drainage networks and (iii) peneplain surfaces. Cover sediments place these landscapes to the (i) Devonian, (ii) Carboniferous/Permian/Triassic and (iii) Late Triassic periods.

The Derim Derim Dolerite, greater McArthur Basin, Australia: Using subsurface data to characterise a mesoproterozoic magma plumbing system

The application of high-resolution seismic reflection data has spurred major advances in knowledge of the emplacement of sub-volcanic mafic magma plumbing systems in sedimentary basins, highlighting the importance of interconnected sheet intrusions in facilitating lateral magma transport, the links between host rock mechanical properties and emplacement processes, and providing insights into how intrusive activity in basins impacts their resource potential. However, most studies have focused on Mesozoic-Cenozoic mafic magma plumbing systems situated along offshore rifted margins characterised by extensive subsurface datasets. The extensive Mesoproterozoic (c. 1300 Ma) Derim Derim Dolerite, which intrude the greater McArthur Basin in northern Australia, provide a unique opportunity to study the emplacement of a Proterozoic magma plumbing system due to its penetration by numerous hydrocarbon and mineral drillholes, in addition to seismic reflection coverage. Understanding the emplacement of this system is important because of its interactions with prospective unconventional shale reservoirs in the Velkerri and Kyalla Formations, which represent one of the world's oldest known petroleum systems. This paper focuses on characterising the intrusion emplacement and magma plumbing system using an array of subsurface data, to constrain the distribution, morphology, and emplacement mechanisms of the Derim Derim Dolerite.The morphology of the large, strata-concordant intrusions encountered at shallow present-day depths (<2 km) in the greater McArthur Basin is indicative of greater original emplacement depths of >3–4 km, suggesting a significant extent of uplift and erosion. Density-derived porosity values for the Velkerri and Kyalla Formations are anomalously low for their present-day depths, corroborating a greater palaeo-depth at time of emplacement. The extent of alteration of the host rock surrounding the Derim Derim Dolerite is highly variable, with a small number of occurrences of graphitisation of the organic matter adjacent to intrusions. However, this appears to be highly localised and the detrimental impact of the Derim Derim Dolerite on potential reservoir and/or source rocks appears generally minimal.

Coupling Relationship between Basin Evolution and Hydrocarbon Reservoirs in the Northern Central Myanmar Basin: Insights from Basin and Petroleum System Modeling

Coupling Relationship between Basin Evolution and Hydrocarbon Reservoirs in the Northern Central Myanmar Basin: Insights from Basin and Petroleum System Modeling

Research on the relative threshold of sustainable development of the complex system in the Yellow River Basin

As a complex system, the sustainability of basins is crucial for the development and stability of human society. This study creatively combined Otsu algorithm with analytic hierarchy process to determine the relative threshold of sustainable development of the Yellow River basin system, aiming to provide a new perspective for the application of threshold theory to the study of sustainable development. The results showed that among the 24 sustainable development evaluation indicators, the Per Capita Cultivated Area (F24) had the greatest impact, while the Ecological Water use (F2) and Agricultural Water use (F19) indicators had the greatest impact range. For different subsystems, the sustainable development indices of the eco-environment subsystem in the upstream of the Yellow River exhibited more significant changes, while that of the socio-economic subsystem exhibited more prominent changes in the midstream. However, the sustainable development indices of the water-sand subsystems in the upstream, midstream, and downstream fluctuated greatly, with a maximum value occurring downstream. The sustainable development threshold was further determined to be 0.408 for the complex system in the Yellow River Basin. The sustainable development thresholds differed in upstream, midstream, and downstream, which ranged from 0.4201 to 0.4524. Based on the sustainable development threshold, the sustainable development status of the Yellow River Basin had continued to improve since 2017, and a high level of sustainability had been maintained. However, the sustainable status is a dynamic process of change, and changes in natural conditions or policies may affect the state of sustainable development.

Application of Analytical Hierarchy Process in evaluation of neotectonic variability on drainage basin systems in the Edea – Eseka region (SW Cameroon Atlantic Coast)

Complex geology and tectonics of the SW Cameroon Atlantic Coast are responsible for the present-day landscapes of the Edea – Eseka Region (EER). The EER is tectonically active and shows differential tectonic uplift, contrasting relief, variations in erosion rates, in river incision, and in channel gradient. Drainage system divides are dynamic features of a landscape that migrate over time during the development of river networks. To study the neotectonic variability in this region, we investigate the drainage river system and the topographic expression of active regional tectonics across the EER. From the Digital elevation model (DEM, 30 m pixel resolution) using Geographic Information System (GIS) interpretive techniques, we extracted eleven morphometric parameters of thirty-two main drainage basins which were combined with Analytical Hierarchy Process (AHP) method. The inter-relationships between these indices grouped into four categories such as watershed geometry, relief characteristics, drainage texture analysis and regional tilting/uplift; can determine the influence of regional tectonic activity in the shape development of drainage basins. The results of the landscape analysis reveal significant variations of the morphometric parameters within the study area indicate a strong tectonic control. From the AHP values, the area is subdivided into high (∼25 %), moderate (∼43.75 %), and low (∼31.25 %) regional tectonic classes. The spatial distribution of different AHP classes shows a gradational pattern from coast to hinterland, suggesting a gradual decrease (from west to east) in the neotectonic activity in the EER drainage basin systems. The moderate-to-high neotectonic activity (∼68.75 %), demonstrates the complexity of the EER unstable tectonic character due to lithospheric mantle dynamism/asthenospheric upwelling as well as the Cameroon Volcanic Line (CVL) activity.

Granulometric and Mineralogical Characterization of Sands from the Middle Course of the Kasai River (Ilebo Territory, Kasai Province, DRC)

This study addresses sediment dynamics within the fluvial system of the middle Kasai Basin, specifically between Ilebo town (pk605) and the confluence with the Loange River (pk525). The primary aim is to characterize the granulometric and mineralogical evolution of sand bars in the Kasai River, which pose navigational challenges in this section of the basin. The study seeks to answer the following question: How do the granulometric and mineralogical characteristics of sands transported by the middle course of the Kasai River evolve? The research employs laboratory granulometric techniques. Twenty sand samples were collected from sand bars along the middle and navigable course of the Kasai River during the flood recession period, ranging from upstream to downstream. Sieving was conducted using an AFNOR-type sieve column, followed by sedimentometric analyses and the calculation of various Folk &amp; Ward textural parameters using the Excel program Gradistat. Additionally, six samples underwent automated mineralogical analysis using a QEMSCAN FEG Quanta 650. Granulometric analysis revealed that the sands from the middle course of the Kasai River are unimodal, with fine to medium grains in the granulometric fraction ranging from 186.2 µm to 426.8 µm. Most of these sands are moderately to well graded, with grains showing granulometric symmetry and, less commonly, fine asymmetry. Their kurtosis is largely mesokurtic, with occasional leptokurtic and platykurtic characteristics, indicating multiple depositional environments. The study demonstrates that the evolution of these granulometric parameters is uneven along the middle course of the Kasai River, though overall, the parameters exhibit limited variation. This suggests minimal and regular sediment inputs, consistent with the relative regularity of granulometric variations in environments characterized by free sedimentation. Automated mineralogical analysis identified a diverse mineralogical assemblage, dominated by quartz, followed by calcite, iron oxides, orthoclase, plagioclase, and kaolinite. Additionally, a group of minerals that do not exceed the 0.55% threshold—such as illite, apatite, ilmenite, muscovite, chlorite, biotite, montmorillonite, rutile, pyrophyllite, siderite, zircon, and dolomite—was identified. Consequently, the mineralogical evolution is not uniform throughout the middle course of the Kasai River, showing a sawtooth variation. This study clarifies the evolution of the granulometric parameters of Kasai River sands, which are influenced by the river's hydrodynamic regime. It also elucidates the mineralogical evolution, linked to the petrographic nature of source areas, which are distributed based on their mechanical resistance to abrasion, chemical alteration, and the morphology of the riverbed. The findings from this research contribute significantly to the field of sedimentology and integrated river management

Long-term stability of sediment routing on an active continental margin: Insights from detrital zircon U-Pb ages and measured stratigraphy of Carboniferous to Miocene strata, Sierra de Narváez, NW Argentina

The complex Phanerozoic tectonic evolution of the western margin of South America, including extensional, neutral, and contractional deformation regimes, provides an opportunity to test how sedimentary systems were affected by variable tectonics on a long-lived active margin. Here, we report new geologic mapping, measured stratigraphic sections, paleocurrent measurements, and detrital zircon U-Pb ages from the Fiambalá area, NW Argentina, that together constrain the evolution of sediment routing and basin systems of the northern Sierras Pampeanas during Carboniferous to Miocene time. Carboniferous to Triassic strata of the Paganzo Group include fluvial, lacustrine, and eolian intervals deposited in an extensional setting with SSW-directed paleocurrent orientations. The Mesozoic El Pedernal Formation consists of a lower, basalt interval and an upper, conglomerate and sandstone interval, which has a new detrital zircon maximum depositional age of ca. 88 Ma. Observed strata of the Miocene Tambería Formation include fluvial to eolian sandstones of the lower member of the formation and alluvial conglomerates of the middle member. Whereas lower member Tambería fluvial strata have SSW-oriented paleocurrents, middle member conglomerates indicate broadly E-directed paleoflow.Detrital zircon age distributions of the Paganzo Group, El Pedernal Formation, and Tambería Formation are remarkably consistent, with dominant age peaks ca. 1.3–0.9 Ga and ca. 660-450 Ma. The ages and relative magnitudes of these peaks are consistent with derivation from igneous sources associated with Choiyoi magmatism (330-215 Ma), the Famatinian (490-450 Ma) and Pampean (540-510 Ma) orogens, basement of the MARA block (ca. 1.3–0.9 Ga), and recycling of Neoproterozoic to Cambrian sedimentary successions derived from central Gondwana (ca. 1.3–0.9 Ga, 650-590 Ma, 540-510 Ma).The consistent paleocurrent orientations and detrital zircon U-Pb ages of the Carboniferous Paganzo Group to the Miocene lower member of the Tambería Formation suggest that a S-directed axial drainage network with a consistent sediment source area persisted in the region for ∼300 Myr. This axial drainage network was succeeded by an E-directed transverse drainage network initiated between 15 Ma and 8 Ma due to growth of the Andean thrust wedge, coeval with tectonic compartmentalization and drainage modification of nearby foreland depocenters. These findings highlight the potential for long-term persistence of drainage networks on continental margins under changing tectonic regimes.