Tectonic Control Research Articles

Modeling Climate and Tectonic Controls on Bias in Measured River Incision Rates

AbstractRates of land surface processes provide insights into climatic and tectonic influences on topography. Bedrock incision rates are estimated by dating perched landforms such as strath terraces, assuming a constant bedrock incision rate from terrace abandonment to the next terrace level or present river level. These estimates express biases from the stochastic nature of sediment and water discharge in controlling river incision as well as from using a mobile channel elevation as a reference frame, leading to different incision rates when calculated over different timeframes. We introduce a 1‐D model incorporating fluvial mechanics, tectonics, sediment, and climate variability to predict these biases and assess their sensitivity to climate and tectonics. Findings suggest biases intensify under highly variable climates and slow rock uplift, with climate periodicity being a primary control for our modeled scenarios. Our model provides a mechanism to improve river incision measurement uncertainty, impacting paleoclimate and tectonic geomorphology reconstructions.

Geophysical characterization and 2D gravimetric modeling: Application to tectonic control of the Vitória-Trindade Ridge (VTR–ES, Brazil)

There are numerous inquiries regarding the origin and development of the Vitória-Trindade Ridge (VTR) in eastern Brazil, a major tectonic feature composed of seamounts, guyots, banks, and islands, prompting extensive studies in the region. These investigations aim to create a more precise crustal model to aid in understanding various geological phenomena, such as the separation of South America from Africa, the interaction between continental and oceanic crusts, and the behavior of oceanic fracture zones. These zones may have served as conduits for magma feeding into the ridge and adjacent areas, or the seamounts could have formed due to a fixed mantle plume related to the West-East trend. This study focuses on exploring the tectonic structure of the region, particularly the subsurface of the VTR, utilizing geophysical data modeling techniques. This includes data from topography, gravimetric and magnetic anomalies, and analysis of reflection seismic lines. The research aims to accurately characterize the geological and geophysical context of the continental margin and some igneous features in the offshore region of the Espírito Santo and Bahia states. The anomalous hotspots correlate with pre-existing fracture zones resulting from the Mesozoic rifting of South American and African continents, which due to later tectonic episodes, have masked traces of deep-seated tectonic structures. The integration of geophysical methods, particularly gravimetry and magnetometry, when combined with reflection seismic data and 2D modeling techniques, offer insights into the geodynamic processes involved in the formation of the volcanic ridge. The results obtained showed the interference generated by magmatism in the oceanic crust and the transition zone. The seismic data allowed the visualization of the approximate geometries and interrelationships of some volcanic edifices that are compared with the Davis Bank, located in the central region of the VTR.

Morphological characteristics and controlling factors of the piedmont fan systems in the Zanskar region, Northwest Himalaya, India

Piedmont fans are prominent geomorphic features formed at the transition between mountain slopes and valley floors. This study investigates the morphology of alluvial fans in the Zanskar Basin (ZB) to uncover the key variables influencing their development and morphodynamics. Utilizing advanced GIS and remote sensing techniques, along with field investigations, we conducted a detailed spatial analysis of 103 alluvial fans along the Doda, Tsarap, and Zanskar rivers. This approach allowed for precise mapping and characterization of these fans within complex depositional settings of ZB, particularly where fans merge into bajadas. Our analysis revealed distinct characteristics for the fans, including Fan Area (FA), Fan Slope (SF), Radius (R), Base Length of Fan (BF), Fan Maximum Entrenchment (FME), and Flow Expansion Angle (FEA). A morphometric analysis was then conducted to evaluate the correlation between the fans and their upstream basins. The linear regression analysis demonstrated both positive and negative correlations between these parameters, highlighting the important role of the upstream basins in controlling sediment delivery to fans. The findings suggest that larger basins contribute to the morphological development of fan systems, with larger, less steep fans forming as a result of greater flows and increased sediment supply from basins with denser drainage networks. Lower values of Mountain Front Sinuosity, Valley Floor Width to Valley Height ratio and Basin Elongation suggest that upstream basins in the ZB are significantly influenced by tectonic forces, resulting in linear mountain fronts, V-shaped valleys and elongated upstream basins. The F-99 fan, in particular, has developed a prominent stepped-fan morphology, attributed to differential uplift, vertical incision, and lateral migration of channels across the fan surface. Along the various fronts of the Zanskar, fan morphology is controlled by a complex interplay of long-term tectonic processes, climate, upstream lithology, and basin characteristics. Tectonic forces, particularly the NW-SE-trending ZSZ/STD and ZCT, exert first-order control on fan morphology by influencing sediment-flux and accommodation space. This influence is evident in tectonically modified landforms such as active mountain fronts, fan terraces, elongated basin shapes, wine-glass valleys and triangular facets, all indicating recent uplift and active tectonics in the region. Our results indicate that ZSZ and ZCT exert significant tectonic control over the geometry and evolution of fans, alongside substantial climatic influences.

Controls of tectonics and paleoclimate on depositional–diagenetic evolution and pore types of Upper Cretaceous successions (Sarvak Formation) in the Abadan plain, Iran

This study examines the influence of tectonics and paleoclimate on the diagenetic evolution of Upper Cretaceous carbonate reservoirs (Sarvak Formation) in the Abadan Plain, Zagros Basin, Iran. Through petrographic analysis and scanning electron microscopy, the sedimentary facies, diagenetic processes, and pore system within the Sarvak Formation were analyzed. Facies analysis identified eight microfacies, which were deposited in shallow to deep settings of a carbonate ramp. Among these, the grain-dominated facies (packstone and grainstone) of shoal complexes and reef-talus settings were identified as the most important reservoir facies. The formation's complex diagenetic history includes marine, meteoric, and burial diagenetic processes, with meteoric diagenesis playing a significant role beneath paleoexposure surfaces. The Sarvak Formation was categorized into eight flow units, seven pore size classes, eleven electrofacies, eight velocity deviation zones, and thirteen Lorenz zones. The study's findings indicate that the most favorable reservoir units are located beneath the Cenomanian–Turonian exposure surface, characterized by significant dissolution of rudist-dominated facies due to meteoric processes and karstification. Tectonic uplift, along with weathering and erosion within a warm and humid (tropical) paleoclimate, significantly impacts the diagenetic evolution, pore types, and petrophysical properties of the Sarvak Formation. This research underscores the complex interplay between tectonics, paleoclimate, and petrophysical properties in the Abadan Plain, enhancing our understanding of carbonate systems in tectonically active and paleoclimatically dynamic regions.

Tectonic controls on ore deposit exhumation and preservation: A case study of the Handan-Xingtai iron-skarn district

Despite the growing concern regarding post-mineralization thermo-tectonic processes in recent years, the relative roles in exhuming and preserving ore deposits remain highly controversial. This study presents new apatite fission track and (U-Th)/He data from the Xishimen iron skarn deposit in the Handan-Xingtai district, central North China Craton. Apatite fission track dating yielded central ages ranging from 88 ± 18 Ma to 125 ± 9 Ma, with mean confined track lengths varying between 11.9 ± 0.4 μm and 13.3 ± 0.2 μm. Integrated apatite (U-Th)/He dating provided ages of 42.5 ± 0.8 Ma to 48.1 ± 3.3 Ma. Our new data, combined with previous zircon U-Pb and potassium-bearing mineral 40Ar/39Ar ages, revealed three cooling episodes: very rapid cooling (100–140 °C/Ma) at ca. 130–120 Ma, a protracted slow cooling period (0.2–0.4 °C/Ma) at ca. 120–50 Ma, and moderate cooling (0.8–1.0 °C/Ma) since ca. 50 Ma. The initial rapid cooling phase was primarily attributed to post-magmatic thermal equilibration following the shallow emplacement of the Xishimen deposit. The subsequent cooling phases were controlled by uplift and exhumation processes. Our thermal models indicate an estimated total unroofing thickness of < 3 km, which is shallower than the emplacement depth of the ore deposit (3–5 km). This suggests significant potential for mineral exploration. Furthermore, a comprehensive review of preservation mechanisms for various ore deposits underscores the significant role of tectonics in both exhuming and preserving ore bodies.

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.

Inversion of Gravity Data Constrained by a Magnetotelluric Resistivity Model: Application to the Asal Rift, Djibouti

AbstractBefore exploiting a geothermal resource in a volcanic setting such as the Asal rift, it is necessary to acquire a better knowledge of the subsoil, with the objective of locating the geothermal reservoir and evaluating the resource characteristic (permeability, temperature, etc.). For this type of resource, geophysical exploration methods are essential (such as gravimetry, magnetotellurics, etc.). However, a particular data type does not necessarily have the resolution and sensitivity. Furthermore, individual inversions of these geophysical data face the ambiguity of the non‐uniqueness of the inverse solution. In this paper, we present a new linear approach of gravity data using the constraint of a MT resistivity model. We coupled the resistivity and density using inversion cross‐gradients and the linear correlations. The approach was tested and validated on synthetic data and applied to gravity and MT data in the Asal Rift. Multiple inversions with different levels of coupling provided a series of density models. We applied the principal component analysis (PCA) technique to assess these models. We were able to define two dominant processes acting differently on the density and resistivity distribution at depth, namely the geothermal activity of the rift and the structural control of active tectonics.

CH4 and CO2 Emissions From Different Tectonic Settings Along the Western Margin of the Ordos Block in China: Output and Correlation With the Regional Tectonics

AbstractThe investigation of tectonic controls on CH4 and CO2 emissions was conducted by measuring the fluxes of the gases in the different tectonic units along the northwestern margin of the Ordos Block in China, a region renowned for its intricate tectonic configuration. The mean fluxes of CH4 ranged from −1.5 to 1.1 mg m−2 d−1, while CO2 fluxes spanned from 2.0 to 29.2 g m−2 d−1. Notably, the Minqin, Ordos, and Haiyuan blocks primarily exhibited absorption characteristics for CH4. In contrast, within the Hetao and Yinchuan grabens, both degassing and absorption processes coexist. A striking observation was that blocks with high internal deformation exhibited significantly higher CH4 and CO2 fluxes compared to those in the stable blocks. Additionally, regions experiencing extensional deformation demonstrated greater gas emission than those undergoing compressional deformation. The spatial distribution of CH4 and CO2 fluxes at the study points exhibited a similar trend to faults in the Yinchuan Graben. Our findings revealed that CH4 and CO2 are mainly of biogenic origin, accompanied by abiotic emissions from underground. And the gas source, migration pathway, and tectonic stress were the primary factors influencing gas emission, with tectonic stress playing a pivotal role. This stress controlled the formation of tectonic structures, changed the degassing pathway, and served as the driving force for gas migration. The results of this study offer valuable insights into the mechanisms governing CH4 and CO2 emission in faulted regions. Furthermore, our results may contribute to future assessments aimed at quantifying the contribution of geological sources to greenhouse gas emissions.

Far–field tectonic controls on deposition in the Appalachian Basin – A case study of Late Cambrian–Late Ordovician strata in Morrow County, Ohio

Far–field tectonics can often be overlooked when studying orogens, particularly when much of the deformation occurs near the loading loci. As stresses are propagated further from the loading into the craton, whether compressional, extensional, or shear, faults and fractures within the basement often act as pathways for stress transmission, traveling along these pre-existing planes of weakness, or creating new. The Appalachian Basin in the eastern United States is a classic foreland basin example that showcases far-field tectonic influence on deposition and structure. This study characterizes the structural architecture of the basement along the western Appalachian Basin margin by analyzing well log data from 2,662 wells to create structure, isopach, trend surface, and residual maps of Late Cambrian through Upper Ordovician strata (Knox through Black River). Fourteen lineaments interpreted as faults were delineated, creating two series of horsts and grabens. The northeast–southwest faults are related to structures that formed during Keweenawan extension, and the northwest–southeast faults are related to structures that formed during the Grenville Orogeny. Both sets of faults stem from the Precambrian basement and are shown to have been reactivated during the Blountian Tectophase of the Taconian Orogeny (Black Riverian deposition), creating localized thinning and thinning adjacent to the lineaments. Furthermore, these faults appear to have undergone additional reactivation since the deposition of these strata in a transtensional regime to create the observed horst and graben structures. Overall, far–field tectonics plays an important role in understanding the geologic history of a basin.

Spatial and temporal evolution of magmatic arcs: Geochemical diversity and tectonic controls

We review the main petrologic and geochemical features of magmatic rocks from continental arcs compared to their intra-oceanic equivalents. Both types share a number of characteristics, including their typical HFSE-depleted incompatible element patterns and isotopic Sr, Nd, Pb and Hf features, intermediate between those of N-MORB and continental crust. They are thought to derive from the partial melting of the mantle wedge metasomatized by fluids emanating from the downgoing plate. They are dominantly hydrous fluids provided by the breakdown of amphibolites and antigorite serpentinites, but a significant role is attributed to felsic hydrous melts derived from oceanic metabasalts and associated sediments. The more enriched character of magmas from continental arcs with respect to those from intra-oceanic arcs is ascribed to their genesis from a less depleted mantle wedge in a milder thermal regime, to the enrichment of their source via subduction erosion of the continental margin, and finally to their contamination during ascent and storage within a thicker crust.

Geologic and Tectonic Controls on Deep Fracturing, Weathering, and Water Flow in the Central California Coast Range

AbstractThe creation of fractures in bedrock dictates water movement through the critical zone, controlling weathering, vadose zone water storage, and groundwater recharge. However, quantifying connections between fracturing, water flow, and chemical weathering remains challenging because of limited access to the deep critical zone. Here we overcome this challenge by coupling measurements from borehole drilling, groundwater monitoring, and seismic refraction surveys in the central California Coast Range. Our results show that the subsurface is highly fractured, which may be driven by the regional geologic and tectonic setting. The pervasively fractured rock facilitates infiltration of meteoric water down to a water table that aligns with oxidation in exhumed rock cores and is coincident with the adjacent intermittent first‐order stream channel. This work highlights the need to incorporate deep water flow and weathering due to pervasive fracturing into models of catchment water balances and critical zone weathering, especially in tectonically active landscapes.

Evolution of Neoproterozoic siliciclastic Kerur Formation in the light of sequence stratigraphic framework: Badami Basin, Karnataka, India

Field-based sedimentology, state of the art facies analysis and sequence stratigraphic framework analysis have revealed the controls of local and global tectonics, basin-marginal slope, climate and changes in relative sea level (RSL) over the sedimentation pattern and evolution of a Neoproterozoic Kerur Formation within the Badami Group of Kaladgi Supergroup in India. The entire succession shows three major cycles of deposition. Facies study and fluvial architectural elemental analysis suggest considerable variations in depositional environments as well as palaeogeography. A transition from basin-margin alluvial cone deposits to braided system, initially with fluctuating ephemeral flows then to a steadier semi-perennial nature, is discernible within the 1st cycle, in response to decreasing depositional slope with rising water table. The initial alluvial cone and braided ephemeral streams of high slope areas is designated as a product of low accommodation systems tract (LAST), while the semi-perennial system with steadier flows, representing the axial river of the initial rift valley, appears to be a product of high – accommodation systems tract (HAST). The 2nd cycle begins with a perennial and steady braided river system and grades upward to a shallow marine succession, comprising wave-dominated, well-sorted sandstone, with a granular transgressive lag at the base. Thus, the bottommost fluvial interval of the 2nd cycle constitutes the lowstand systems tract (LST). The marine succession represents deposits of outer shelf offshore to foreshore-beach settings and is composed of an initially deepening and fining upward transgressive systems tract (TST), followed by a coarsening and shallowing upward highstand systems tract (HST) with a maximum marine flooding surface (MFS) in between, demarcated by a shale-rich condensed zone. The 3rd cycle, with its prograding alluvial fan and aggrading braided fluvial deposits and restricted occurrence, represents only the low accommodation systems tract (LAST) with a subaerial unconformity at the base. The basin evidently initiated in the western sector, followed by its eastward expansion during the first major rejuvenation of the basin margin faults, after the deposition of the 1st cycle. After the basin-wide deposition of the 2nd cycle, restricted development of the 3rd cycle took place in the western sector only, following the second major rejuvenation of the fault system. The proposed sedimentological model, supported by established geochronological constraints, suggests that the sedimentation in the 1st cycle begins with scree cones, alluvial fans and braided ephemeral channel networks, originated from faulted basin margins within a riftogenic setting possibly related to the global-scale extensional tectonics of Rodinia breakup. After the expansion of the basin, the marine inundation has been correlated to the transgression that possibly took place during the post-rift maturation stages.

Tectonic controls on the morphometry of alluvial fans in an arid region, northeast Iran

ABSTRACT The morphology of alluvial fans provides valuable information about changes in tectonic, climate, base level, and drainage basin characteristics. This study aims to evaluate the relationship between active tectonics and morphometric characteristics of alluvial fans in the less studied southern region of the Joghatay mountain, northeast Iran. The study area includes 13 alluvial fans and their corresponding catchment basins in a region with semi-arid climate. Morphometric characteristics of alluvial fans and their corresponding drainage basin including fan area, fan slope, sweep angle, fan toe length, fan radius, basin area, basin slope, fan’s width-to-length ratio, asymmetry factor, and basin shape were measured. Our results revealed a negative relationship between the slope of alluvial fans and their corresponding basin area. The weak correlation between the drainage basin area and the fans area may be attributed to the lithology and active tectonics in the study area. The small sweep angle values of the studied alluvial fans can be attributed to the activity of thrust faults and presence of an uplifting anticline that resulted in formation of elongated alluvial fans in our study area. Analysis of the relationship between the morphometric characteristics of the fans and their corresponding basins indicated a negative correlation, which can be attributed to the sediment transport efficiency of the basins.

The Intraplate Stress Field of West Africa

AbstractWest Africa continues to host a growing number of low and intermediate‐magnitude earthquakes (M2‐5) along its passive margins, and its continental interior. Earthquake activity in these regions raises the need to comprehend the causes and the tectonic controls of the seismicity. Unfortunately, such studies are rare. Here, we apply single‐station inversion techniques to constrain fourteen focal mechanisms, computed after compiling a set of high‐quality waveforms. We describe the connection between seismicity, the contemporary stress field, anthropogenic activity and Holocene fault scarps in the region. Our results indicate transpressive stresses acting on the inherited brittle structures in the passive margins. We also observe a compressive regime in the intracontinental failed rifts. We attribute the seismicity to the reactivation of “weak” faults in the Neoproterozoic and Mesozoic failed rifts, the passive transform structures, and the intracratonic Precambrian brittle shear zones.

Genesis of Rare Metal Granites in the Nubian Shield: Tectonic Control and Magmatic and Metasomatic Processes

The Igla Ahmr region in the Central Eastern Desert (CED) of Egypt comprises mainly syenogranites and alkali feldspar granites, with a few tonalite xenoliths. The mineral potential maps were presented in order to convert the concentrations of total rare earth elements (REEs) and associated elements such as Zr, Nb, Ga, Y, Sc, Ta, Mo, U, and Th into mappable exploration criteria based on the line density, five alteration indices, random forest (RF) machine learning, and the weighted sum model (WSM). According to petrography and geochemical analysis, random forest (RF) gives the best result and represents new locations for rare metal mineralization compared with the WSM. The studied tonalites resemble I-type granites and were crystallized from mantle-derived magmas that were contaminated by crustal materials via assimilation, while the alkali feldspar granites and syenogranites are peraluminous A-type granites. The tonalites are the old phase and are considered a transitional stage from I-type to A-type, whereas the A-type granites have evolved from the I-type ones. Their calculated zircon saturation temperature TZr ranges from 717 °C to 820 °C at pressure &lt; 4 kbar and depth &lt; 14 km in relatively oxidized conditions. The A-type granites have high SiO2 (71.46–77.22 wt.%), high total alkali (up to 9 wt.%), Zr (up to 482 ppm), FeOt/(FeOt + MgO) ratios &gt; 0.86, A/CNK ratios &gt; 1, Al2O3 + CaO &lt; 15 wt.%, and high ΣREEs (230 ppm), but low CaO and MgO and negative Eu anomalies (Eu/Eu* = 0.24–0.43). These chemical features resemble those of post-collisional rare metal A-type granites in the Arabian-Nubian Shield (ANS). The parent magma of these A-type granites was possibly derived from the partial melting of the I-type tonalitic protolith during lithospheric delamination, followed by severe fractional crystallization in the upper crust in the post-collisional setting. Their rare metal-bearing minerals, including zircon, apatite, titanite, and rutile, are of magmatic origin, while allanite, xenotime, parisite, and betafite are hydrothermal in origin. The rare metal mineralization in the Igla Ahmr granites is possibly attributed to: (1) essential components of both parental peraluminous melts and magmatic-emanated fluids that have caused metasomatism, leading to rare metal enrichment in the Igla Ahmr granites during the interaction between rocks and fluids, and (2) structural control of rare metals by the major NW–SE structures (Najd trend) and conjugate N–S and NE–SW faults, which all are channels for hydrothermal fluids that in turn have led to hydrothermal alteration. This explains why rare metal mineralization in granites is affected by hydrothermal alteration, including silicification, phyllic alteration, sericitization, kaolinitization, and chloritization.

The spatial and geological characteristics of fault- and paleokarst-controlled carbonate-hosted reservoirs in the Tabei Uplift, Tarim Basin, China

Seismic interpretation and characterization of Middle Ordovician carbonates of the northern Tarim Basin in China reveal a series of deep-seated, sub-vertical conjugate strike-slip faults, together with sets of apparently layer-bound fractures striking parallel or orthogonal to the faults. Detailed stratigraphic analysis, well logging response interpretations (including formation microscanner images), coupled with core sample and thin section observations highlight vertical and lateral partitioning of fracturing and dissolution processes. Fracturing and dissolution development are most intense in grain-supported host rocks (grainstones, packstones) deposited in relatively shallow water conditions. Reservoir pore spaces vary systematically from north (Tahe) to south (Shunbei), which can be attributed to their proximity to a major regional angular unconformity with overlying Upper Devonian to Carboniferous sequences. Larger-scale dissolved fracture-cavity reservoirs are developed in the northern Tahe area due to the combined effects of faulting, surface karstification, and river system development close to the base Carboniferous erosion surface. Farther south, where the rocks lie farther from the paleoerosion surface, reservoir space is characterized by smaller, more structurally controlled open cavities bounded by fault slip surfaces, breccias, and open fractures. The observed interactions between paleokarstification intensity, tectonic controls, and host rock lithological layering—and their control over the observed reservoir complexity—are likely to occur in carbonate reservoirs worldwide.

Extensive palaeo-surfaces beneath the Evans–Rutford region of the West Antarctic Ice Sheet control modern and past ice flow

Abstract. The subglacial landscape of Antarctica records and influences the behaviour of its overlying ice sheet. However, in many places, the evolution of the landscape and its control on ice sheet behaviour have not been investigated in detail. Using recently released radio-echo sounding data, we investigate the subglacial landscape of the Evans–Rutford region of West Antarctica. Following quantitative analysis of the landscape morphology under ice-loaded and ice-unloaded conditions, we identify 10 flat surfaces distributed across the region. Across these 10 surfaces, we identify two distinct populations based on clustering of elevations, which potentially represent remnants of regionally coherent pre-glacial surfaces underlying the West Antarctic Ice Sheet (WAIS). The surfaces are bounded by deeply incised glacial troughs, some of which have potential tectonic controls. We assess two hypotheses for the evolution of the regional landscape: (1) passive-margin evolution associated with the break-up of the Gondwana supercontinent or (2) an extensive planation surface that may have been uplifted in association with either the West Antarctic Rift System or cessation of subduction at the base of the Antarctic Peninsula. We suggest that passive-margin evolution is the most likely of these two mechanisms, with the erosion of glacial troughs adjacent to, and incising, the flat surfaces likely having coincided with the growth of the WAIS. These flat surfaces also demonstrate similarities to other identified surfaces, indicating that a similar formational process may have been acting more widely around the Weddell Sea embayment. The subsequent fluctuations of ice flow, basal thermal regime, and erosion patterns of the WAIS are therefore controlled by the regional tectonic structures.

Geology, Mineralogy and Analysis of Tectonic Fracturing of Barite Mineralization’s in Bateun Jeudari Paleozoic basement, Eastern High Atlas, Morocco

Bateun Jeudari barite and iron deposit located in the eastern High Atlas Shales; It occupied the Hercynian fault system trending N70 to N90. It corresponds to large hydrothermal vein associated with micro-fracturing rocks type in stockwork form, hosted in the Paleozoic schists and perlite. The petrographic, geochemical analysis and belayed scanning electron microscopy results shows the presence of the barite associated with iron minerals. The petrographic indicates the structures composed by ferruginous and white barite associate locally to quartz. The established model of the barite and iron deposit gives the presence intravenous sedimentary tissues formed from a low salinity solution. Moreover, the structures and morphology of the mineralization reflect the tectonic control responsible for the establishment of the mineralization by faulting movements. Thus, it corresponds to barium-rich occurrences related to a compression period ENE-WSW, probably of Visean- Namurian age.

Nonmatrix pores form high-permeability zones in carbonate layers: The Furna Feia cave in the Potiguar Basin, Brazil

Studying nonmatrix porosity in reservoirs is challenging, especially between core samples and seismic scales. To fill this gap, this work studied a karst system as an analog for a nonmatrix carbonate reservoir. We used a multidisciplinary approach, analyzing host rock data (petrography, petrophysics, and tectonic history) and porosity geometry (terrestrial laser scanner, ground penetrating radar, and field analysis). The karst system occurs in Cretaceous carbonates of the Jandaíra Formation along a regional subaerial unconformity that forms the boundary between lagoonal facies (bed package II) and tidal bar facies (BP-III). BP-I (tidal bar 1) is observed at the base of the cave, while BP-II is in the middle of the cave walls, and BP-III (tidal bar 2) occurs at the ceiling. We find that matrix pores are more pervasive in BP-I. Nonmatrix pores predominate in BP-II and BP-III but mostly in the boundary between them. Horizontal dissolution (decametric-cavernous pores) is more intense along the subaerial unconformity. Metric nonmatrix pores, such as gigapores (pockets) and cavernous pores (cupolas), occur within dolomitic lagoonal facies but predominate in tidal bar facies at the cave ceiling. Most of these metric pores are elongated, and their principal axes are preferentially oriented along NW–SE-striking fractures, indicating tectonic control of the Poço Verde Fault Zone. In this way, we conclude that nonmatrix porosity follows tectonic features below a subaerial unconformity, forming high-permeability zones in carbonate layers. Dolomitization guides the fractures intensity, leading to their consequent enlargement. The features studied here led to cave evolution. These findings can guide karst reservoir prediction.

Interactions between Cenozoic tectonics and landscape dynamics in Londrina, Paraná, Brazil

The Londrina City, located in southern Brazil, is situated on the basalt of the Paraná Igneous Province (PIP), near tectonic structures such as the Guaxupé faults and the São Jerônimo-Curiúva and São Sebastião lineaments, with a history of reactivation in the Cenozoic. Between 2015 and 2018, low-magnitude earthquakes hit the municipality, suggesting a possible connection with these structures. This study investigates the relationship between Cenozoic tectonics and geomorphological dynamics, combining quantitative geomorphological analysis with field analysis of faults. The results reveal signs of tectonic control on the landscape, with two pulses of regional uplift/base level drop affecting the drainage network. Reactivated segments, especially at intersections of NE and NW structures, influence dynamics, with variations in uplift rates between basins and block rotation under a transtensive regime. Recent earthquakes are related to the reactivation of an N50-60E fault scarp, possibly the Guaxupé Fault, indicating recurrent tectonic movement. Paleostress analyses identify three deformation pulses, highlighting the complexity of landscape evolution in intraplate regions. These findings enhance understanding of regional tectonics, emphasizing the need to comprehend landscape evolution in interior plate areas, such as the South American Plate.