Eurasia Convergence Research Articles

Tectonic Setting and Spatiotemporal Earthquake Distribution in Northern Nubia and Iberia

The spatiotemporal distribution of major earthquakes in the study area (1600–2024) is analyzed to tentatively recognize the possible connections with the short-term (from decades to centuries) evolution of the ongoing tectonic processes. This study suggests that during the period considered, seismic activity has been predominantly related to the shortening processes accommodating the convergence of northwestern Nubia with the Iberian and Moroccan plates that mainly involve the westward escape of the Alboran wedge and the NNE-ward escape of the Iberian block. This deformation pattern is inferred from the seismic activity in the North Atlantic domain, the Rif and Betics belts, the western Iberian fault system (onshore and offshore), the Transmoroccan fault system and the Pyrenean thrust front. Seismic activity in the Tell is mainly driven by the Nubia–Eurasia convergence, even though it can be also influenced by the major westward displacements of the Anatolian–Aegean–Adriatic–Pelagian system. This hypothesis could explain the marked increase in seismic activity that occurred in the Tell in the last decades, when that zone may have been affected by the perturbation triggered by the large post-1939 westward displacement of Anatolia. The pieces of evidence and the arguments reported in this study might provide insights into the possible spatial distribution of major earthquakes in the next decades.

Cenozoic pure-shear thickening of the northern Tibetan Plateau margin: Implications for diverse plateau uplift mechanisms controlled by convergent obliquity

How the deformed Tibetan lithosphere absorbed the convergence of India and Eurasia during the Cenozoic remains enigmatic, primarily due to significant variation in lithospheric deformation across different margins of the plateau. The northern margin of the Tibetan Plateau is uniquely defined by the ∼1600-km-long Altyn Tagh fault system. How this plateau margin uplifted for 2−4 km under a strike slip-dominated deformation regime remains a subject of debate. Understanding the SE Tarim Basin north of this plateau margin is crucial for addressing this issue, as it contains thousands of meters of Cenozoic sediments sourced from the Tibetan Plateau. Here we use well-logging, isopach mapping, and seismic reflection data to characterize the Cenozoic deposition and deformation processes of the SE Tarim Basin, which are closely related to the uplift mechanism of the northern plateau margin. The results show that (1) the Cenozoic strata exhibit minimal variations in thickness, with no evident thickening toward the Tibetan Plateau; (2) the basin has been deformed by high-angle, basement-involved compressional faults since ca. 16 Ma, mainly through the reactivation of pre-Cenozoic structures; and (3) the maximum Cenozoic shortening is merely ∼0.9 km in the area we studied. These findings, integrated with other geological and geophysical observations, argue against the long-distance continental subduction of the Tarim Basin beneath the Tibetan Plateau, which requires the development of a foreland basin with sediments thickening toward the orogen and low-angle, thin-skinned fold-thrust belts involving ∼100−150 km of shortening in the SE Tarim Basin. These results, together with vertical Moho offsets across the fault system, lead us to propose lithospheric-scale pure-shear thickening as the Cenozoic uplift mechanism of the northern Tibetan Plateau margin. By further comparing the various uplift mechanisms operating on different margins of the Tibetan Plateau, we emphasize the significant role of convergent obliquity in controlling diverse plateau uplift mechanisms.

Comparison of Crustal Stress and Strain Fields in the Himalaya–Tibet Region: Geodynamic Implications

The Himalaya–Tibet region represents a complex region of active deformation related to the ongoing India–Eurasia convergence process. To provide additional constraints on the active processes shaping this region, we used a comprehensive dataset of GNSS and focal mechanisms data and derived crustal strain and stress fields. The results allow the detection of features such as the arc-parallel extension along the Himalayan Arc and the coexistence of strike-slip and normal faulting across Tibet. We discuss our findings concerning the relevant geodynamic models proposed in the literature. While earlier studies largely emphasized the role of either compressional or extensional processes, our findings suggest a more complex interaction between them. In general, our study highlights the critical role of both surface and deep processes in shaping the geodynamic processes. The alignment between tectonic stress and strain rate patterns indicates that the crust is highly elastic and influenced by present-day tectonics. Stress and strain orientations show a clockwise rotation at 31°N, reflecting deep control by the underthrusted Indian Plate. South of this boundary, compression is driven by basal drag from the underthrusting Indian Plate, while northward, escape tectonics dominate, resulting in eastward movement of the Tibetan Plateau. Localized stretching along the Himalaya is likely driven by the oblique convergence resulting from the India–Eurasia collision generating a transtensional regime over the Main Himalayan Thrust. In Tibet, stress variations appear mainly related to changes in the vertical axis, driven by topographically induced stresses linked to the uniform elevation of the plateau. From a broader perspective, these findings improve the understanding of driving crustal forces in the Himalaya–Tibet region and provide insights into how large-scale geodynamics drives surface deformation. Additionally, they contribute to the ongoing debate regarding the applicability of the stress–strain comparison and offer a more comprehensive framework for future research in similar tectonic settings worldwide.

India–Eurasia convergence speed-up by passive-margin sediment subduction

The fast increase of convergence rate between India and Eurasia around 65 million years ago (Ma)—from approximately 8 cm yr−1 to a peak rate of approximately 18 cm yr−1—remains a complex geological event to explain1–8, given the inherent uncertainty surrounding the tectonic history and the intricate interplay of forces influencing plate speed9–11. Here we use a combination of geochemical analysis and geodynamic modelling to propose that this rapid convergence can be explained by sediment subduction derived from the northern Indian passive margin. Through isotope and trace element analysis, we find an enhanced contribution of terrigenous sediment melt to the mantle source of the Gangdese magmatic rocks around 65 Ma, concurrent with the acceleration of India–Eurasia convergence. Numerical experiments suggest that subduction of sediments more than 1 km thick covering an approximately 1,000-km-wide ocean basin abutting the northern Indian passive margin starting from 65 Ma could have spurred the increased convergence rate and further led to significant crustal extension, consistent with empirical observations. Our study implies that the acceleration of India–Eurasia convergence marks the arrival of passive-margin-derived sediments, constraining the initial India–Eurasia collision to be around 60 Ma. It further suggests that temporary accelerations in subduction rates might be a common feature at the final stage of continental assembly.

Active Tectonic Deformation of the Qilian Shan, Northeastern Tibetan Plateau

Abstract —The Qilian Shan (or Qilian Mountains), located on the northeastern margin of the Tibetan Plateau, is an actively growing orogenic belt resulting from the far-field impact of the India–Eurasia collision. The northward penetration of the Indian Plate is responsible for intense crustal shortening in the Qilian Shan. However, the tectonic deformation pattern in response to the crustal shortening remains unclear. In this study, we present the regional seismicity, fault activity, and GPS crustal movement velocity field to characterize the active tectonic deformation of the Qilian Shan based on historical data over the past two decades. The results suggest that the western Qilian Shan is characterized by distributed north–south crustal shortening, while the eastern Qilian Shan is dominated by blocklike eastward extrusion of crust along major strike-slip faults coupled with clockwise rotation. North–south crustal shortening and east–west lateral extrusion, two deformation modes responding to the India–Eurasia convergence, match the crustal deformation in the Qilian Shan. The tectonic deformation of the western Qilian Shan is largely in agreement with the former, while the eastern Qilian Shan corresponds closely to the latter. Lower crustal flow beneath the central Tibetan Plateau provides the potential driving force to induce the eastward extrusion of crustal material out of the plateau and the growth of some boundary mountain ranges, such as the Qilian Shan.

Seismicity and state of stress in NE Arabia

Eastern Arabia exhibits low seismic activity although damaging earthquakes are historically known. Despite the proximity to convergent plate boundaries in the Arabia–Eurasia collision zone, the state of stress in northern Oman with its persistent topography of the Oman Mountains (OM) remains enigmatic. We have revised the earthquake catalogue of northern Oman and confirm the detection and location accuracy of the permanent network by comparison with a temporarily densified network across the OM. For the first time, we infer focal mechanisms (FM) for earthquakes in Oman from P-wave polarities. Seismic activity is high in the Northern OM but diminishes rapidly south of 24.5° N. In the Central and Eastern OM, low-magnitude earthquakes occur along topography bounding faults with mostly transtensional FM. Offshore, seismicity follows NE-trending lines in extension of the Semail Gap and the Masirah Fault Zones, up to the Makran trench. Except for an isolated patch of repeated small-magnitude earthquakes, the western Makran trench is seismically quiet. Inversion of FM confirms a NE–SW direction of maximum horizontal stress that aligns with Arabia–Eurasia convergence. In the Central and Eastern OM, maximum horizontal and vertical stresses are balanced. The topography of the OM appears, therefore, not to be generally sustained by compressional forces.

Northward expansion of the West Kunlun orogenic belt during the Cenozoic and its implications for the evolution of the northwest Tibetan Plateau: Constraints from sediment dispersal patterns in the Buya Basin, China

Northward expansion of the West Kunlun orogenic belt during the Cenozoic and its implications for the evolution of the northwest Tibetan Plateau: Constraints from sediment dispersal patterns in the Buya Basin, China

Modern Approaches for Historical Seismograms: Moment Tensor Inversion of the 1947 Squillace Basin, South Italy, Earthquake

Abstract The scientific community has become increasingly aware of the importance of preserving and recovering historical seismic data, also because of their possible use in combination with modern techniques of analysis. Seismograms coming from the analog recording era cover more than 100 yr of seismic activity and may have a great relevance, especially for seismic risk evaluations in regions struck by destructive events in the past centuries but characterized by minor activity in the last decades. In this study we used analog seismograms to investigate an earthquake of presumed magnitude 5.7 that occurred in 1947 in central Calabria, south Italy, a high-seismic risk region framed in a complex geodynamic setting led by northwest-trending Nubia–Eurasia convergence and southeastward Ionian slab rollback. According to seismic catalogs, the 1947 is the only M > 5.5 earthquake instrumentally recorded in an area where the presence of the lateral edge of the Ionian slab has been suggested and an intense debate is still open concerning possible existence, and proper location, of a subduction-transform edge propagator (STEP) fault zone. To study this earthquake, we selected 15 medium- to long-period analog seismograms with related instrumental parameters, and we proceeded with vectorization process and proper waveform corrections. A technique specifically developed for time-domain moment tensor computation through waveform inversion of analog seismograms has been applied to the digitized recordings. The moment tensor solution estimated for the 1947 earthquake indicates strike-slip mechanism, focal depth of 28 km and Mw 5.1. The obtained hypocentral depth and left-lateral kinematics on about west-northwest–east-southeast-oriented fault fit well with the local seismotectonic framework and are compatible with STEP fault activity in central Calabria, furnishing a new seismological constraint to the debate concerning slab edge kinematics. Moreover, the presented analysis is useful for sharing with the scientific community new data and methodological issues related to historical seismogram management.

Present-day kinematics of the northwest Moroccan Atlantic Margin from GNSS data: west southwest extrusion at the western end of the High Atlas

The Global Navigation Satellite System (GNSS) has emerged as a practical and effective technique for studying slow and steady geodynamic movements, enabling continuous monitoring and precise quantification of deformation over different timescales. In Morocco, a network of GNSS stations has been established, offering valuable insights into tectonic processes. This paper focuses on investigating the geodynamic motion of the northwest Moroccan Atlantic Margin. By utilizing GNSS data, subsidence rates and horizontal velocity fields were determined for the first time, providing valuable information for oil and gas exploration activities. The study reveals an active uplift rate of 1 mm/year and a westward horizontal motion of 2.04 mm/year in the Essaouira segment. The paper presents a case study of the Essaouira–Agadir basin (EAB) onshore segment and investigates the anomalous displacement observed in this region compared to other coastal GNSS stations. Possible explanations for the observed movements include local processes such as salt tectonics and regional northwest–southeast compression related to Africa–Eurasia convergence. We suggest that the anomalous movement detected in this work is due to the regional northwest–southeast compression related to Africa–Eurasia convergence imparting an extrusion of the EAB to the west. This research contributes to a better understanding of the geodynamics in the northwest Moroccan Atlantic margin, thereby providing valuable insights for ongoing efforts in oil and gas exploration. Furthermore, it indicates the continued activity of the Agadir fault, which would exhibit a sinistral wrench movement, thus posing a threat to the city of Agadir and its inhabitants.

Timeframe of eastern Paleo-Tethys closure: Constraint on the Songpan-Ganzi Complex by big data-based multiproxy provenance analysis

Timeframe of eastern Paleo-Tethys closure: Constraint on the Songpan-Ganzi Complex by big data-based multiproxy provenance analysis

Topography and drainage system evolution in the ‘‘Volubilis basin’’ (South Rifain Ridges, Northern Morocco)

The Volubilis piggy-back basin, located at the front of the Rif belt, northern Morocco, is a subsided area, as a continuation of the deformational orogenic ridges, related to the present-day African and Eurasian convergence. For the first time, by morphotectonic studies, we analyzed the topographic evolution and drainage systems response. Our results proved the influence of active tectonics in the drainage network and topography of the Volubilis basin. The young phase is indicated by a less dissected planation surface comparing to the ridges, as well as by the ε-shaped hypsometric curve of the khoumane river. This latter drains the continuation of the basin and the eastern arc, where the tectonic activity is mostly concentrated. Based on swath analysis, the general trend of tilting was characterized and was attributed to the recent tectonic movement combined with folds growth of the ridges.

Strike‐slip deformation and expansion process of the Qilian fold‐and‐thrust belt: Inferred from gravitational potential energy

In this study, we present a new estimation of the gravitational potential energy (GPE) and explore its relationship with the present‐day stress and strain‐rate field in the Qilian fold‐and‐thrust belt (QFTB), to evaluate how the stress associated with GPE gives rise to tectonic deformation of the QFTB, and to achieve a more comprehensive understanding of stress transfer from the Indian–Eurasian collision belt to the QFTB. Significant features of the stress and deformation in the QFTB derived from our analysis include the following: (1) the stress pattern is verified by the results of the deviatoric stress being inverted by topographic stress modelling, suggesting that topographic stress associated with the lateral variations in crustal thickness and topography should be taken into account when considering the clockwise rotation of the stress field along the strike of the Qilian fold‐and‐thrust belt. (2) Our stress–strain results suggest that the strain derived from the Indian–Eurasian convergence propagated to the north of the Haiyuan Fault. By incorporating with recent seismological results, it is supposed that the Tibetan Plateau has extended to the southern Alxa block, and the Haiyuan Fault may not be the most northeastern crustal boundary of the Tibetan Plateau. (3) The comparison of surface strain, focal stress and topographic stress modelling illustrates that the Qilian fold‐and‐thrust belt is probably deforming in response to the far‐field effect of Indian–Eurasian convergence. The stress transfer from the collisional front to the Qilian fold‐and‐thrust belt appears to be continuous and progressive. Accordingly, we suggest that a diffuse model could better describe the deformation of the Qilian fold‐and‐thrust belt in which lateral expansion is accommodated evenly along the principal axes of stress as a consequence of horizontal lithospheric heterogeneity.

Iran and Regional Convergence in Eurasia

AbstractRegional convergence in Eurasia has been evolving since the collapse of the Soviet Union. The Commonwealth of Independent States was Russia's initial attempt to forge a comprehensive regional integration. However, Russia gradually shifted its focus to economics, and this produced the Eurasian Economic Union (EEU). This organization has concluded numerous cooperation agreements, even with countries outside the borders of Eurasia, raising questions about regional convergence. In addition, with the expansion of China's influence in Central Asia, there has been a shift in the role and scope of the EEU. Iran has concluded a preferential trade agreement with the EEU, including non‐tariff measures and a list of commodities for which barriers have been reduced or cut to zero. The main question of this study is how Iran's presence in this organization will influence Eurasian convergence. We examine the opportunities for, and obstacles to, convergence through an analysis of the forces that can bind an institution like the EEU: cultural and ideological affinities; the hegemony of the most powerful actors; and the potential for solving common problems.

Geodynamics of Alpine Belt and Caribbean Region: Plate - Tectonics and Plume - Tectonics

The origin and evolution of geological structures reflect lithosphere-asthenosphere interaction in the process of lithospheric plate movement. Mantle diapirs contribute significantly to the sedimentary basins formation in Alpine belt and Caribbean region. Mantle diapirs are the result of density inversion in the asthenosphere–lithosphere system in the periods of tectonomagmatic activations. Increasing heat flow and mantle diapirs on the phone of convergence of Africa and Eurasia in Alpine belt and North and South Americas in Caribbean region produce intercontinental seas in the Cenozoic. The analytical solution of the problem give possibility to find the critical parameters connecting the mantle flow dynamics with surface relief evolution. In Alpine belt, the mantle diapirs form new basins at the final stage of Africa–Eurasia collision in the Cenozoic. In the Caribbean region, great mantle diapir separates the North and South Americas in the Mesozoic, and then the diapir is the source for different smaller diapirs during the convergence of these continents in the Cenozoic. The Gulf of Mexico and Pre-Caspian Depression are connected with mantle diapirs upwelling and have common geological-geophysical features as very rich oil-gas and salt bearing structures. Geodynamics of Alpine belt and the Caribbean region is determined by plume - tectonics on background of plate - tectonics in these regions.

Retracing the Africa–Eurasia nascent convergent boundary in the western Mediterranean based on earthquake and GNSS data

In the western Mediterranean, following the intervening continent-continent collision, the subduction of the Tethyan ocean has progressively come to an end or almost in large sectors. Compressional deformation connected with the ongoing Africa–Eurasia convergence has therefore progressively resumed mostly along the southern passive margins of the Mediterranean back-arc basins. The aim of this paper is to trace this nascent boundary and constrain its kinematics through geodetic and seismological data recorded between the Ionian Sea and Gulf of Cadiz, and through pre-existing tectonic data. Based on these data, the nascent plate boundary is drawn, kinematically defined, and compared with the previously identified boundaries in the same region. The nascent boundary is weaving and formed by variably oriented inherited structures. It is characterized by a discrepancy between the general motion of Africa with respect to Eurasia and the local contractional/compressive axes deduced from geodetic and seismic data. The oblique convergence along the nascent boundary matches that recorded in other instances of subduction initiation elsewhere; however, the average convergence rate ( ∼ 5 mm/yr ) in the Mediterranean seems currently too small for such a subduction initiation. Based on the assumption of a future northward tectonic vergence (i.e., Eurasian foreland), the Tyrrhenian, Algerian, and Betic salients, the Oran and Fès recesses, and the Ionian, Trans-Alboran, and Gibraltar transfer zones are identified along the nascent boundary. The latter zones connect salients and recesses through strike-slip displacements. The Algerian offshore hosts a long segment of the boundary characterized by locally increased seismic rate and actual northward vergence that would suggest this area being the first nucleus of subduction initiation in the western Mediterranean, as was previously proposed. • Updated seismic and geodetic view of western Mediterranean geodynamic setting. • Nascent plate boundary between Africa and Eurasia in the western Mediterranean. • Hypotheses on future plate boundary and related modes of deformation.

Strain Distribution Along the Qilian Fold-and-Thrust Belt Determined From GPS Velocity Decomposition and Cluster Analysis: Implications for Regional Tectonics and Deformation Kinematics

The Qilian fold-and-thrust belt (QFTB) offers an excellent example to demonstrate the strain transition from strike–slip shearing to oblique crustal shortening, which plays an important role in dissecting the stress propagation of Indian–Eurasian convergence from the plateau interior to the surrounding blocks. Various geological or numerical models have attempted to describe the regional tectonic characteristics of the QFTB. However, these models only interpret one or part of the deformation behaviors in the QFTB, and the strain distribution across and along the QFTB as well as its deformation kinematics remains to be determined. Therefore, in this work, we applied the method of velocity decomposition and cluster analysis using combined GPS data to determine the strain partition or accommodation in different parts of the QFTB as well as tectonic relationships with surrounding blocks, which will contribute to distinguishing which model is more suitable for delineating the present-day deformation kinematics of the QFTB. Our analysis indicates that the western part of the QFTB is dominated mainly by crustal shortening perpendicular to the trend of the QFTB, coupled with lateral extension along the trend of the QFTB, while the eastern part of the QFTB is characterized mainly by lateral extrusion owing to the impact of two large eastward-striking left-slip faults (East Kunlun fault and Haiyuan fault), which are accommodated by an obvious velocity gradient boundary belt centered on two diamond basins (Qinghaihu and Gonghe basins) associated with their boundary faults. The active tectonics of the QFTB are obviously divided into two distinct groups: one group is a pure shear–strain pattern, accounting for strong crustal shortening in the western part of the QFTB, and the other group is a simple shear–strain pattern, accounting for the obvious lateral extrusion in the eastern part of the QFTB.

Basic Role of Extrusion Processes in the Late Cenozoic Evolution of the Western and Central Mediterranean Belts

Tectonic activity in the Mediterranean area (involving migrations of old orogenic belts, formation of basins and building of orogenic systems) has been determined by the convergence of the confining plates (Nubia, Arabia and Eurasia). Such convergence has been mainly accommodated by the consumption of oceanic and thinned continental domains, triggered by the lateral escapes of orogenic wedges. Here, we argue that the implications of the above basic concepts can allow plausible explanations for the very complex time-space distribution of tectonic processes in the study area, with particular regard to the development of Trench-Arc-Back Arc systems. In the late Oligocene and lower–middle Miocene, the consumption of the eastern Alpine Tethys oceanic domain was caused by the eastward to SE ward migration/bending of the Alpine–Iberian belt, driven by the Nubia–Eurasia convergence. The crustal stretching that developed in the wake of that migrating Arc led to formation of the Balearic basin, whereas accretionary activity along the trench zone formed the Apennine belt. Since the collision of the Anatolian–Aegean–Pelagonian system (extruding westward in response to the indentation of the Arabian promontory) with the Nubia-Adriatic continental domain, around the late Miocene–early Pliocene, the tectonic setting in the central Mediterranean area underwent a major reorganization, aimed at activating a less resisted shortening pattern, which led to the consumption of the remnant oceanic and thinned continental domains in the central Mediterranean area.

Two-phase intracontinental deformation mode in the context of India–Eurasia collision: insights from a structural analysis of the West Kunlun–Southern Junggar transect along the NW margin of the Tibetan Plateau

The convergence of India and Eurasia, which began in the early Cenozoic, established the Tibetan Plateau and the Circum-Tibetan Plateau Basin and Orogen System. When and how the convergence-driving strain propagated into this system is important in deciphering the growth processes of the Tibetan Plateau. We conducted a structural analysis of the West Kunlun–southern Junggar transect along the NW margin of the Tibetan Plateau to establish the propagation of deformation and, through this, to determine the plateau growth processes. Our results suggest a two-phase deformation mode. The first-stage features deformation confined to pre-existing weak zones (e.g. the West Kunlun orogen, the Buchu Uplift and the Tian Shan orogen) during the Paleogene, when the intracontinental strain is speculated to be mainly consumed by shortening of these weak zones. The second stage is characterized by deformation propagating into the foreland regions since the early Miocene, where shortening along the foreland fold–thrust belts on a scale of tens of kilometres and decreasing basinwards had a key role in absorbing intracontinental strain. We suggest that this two-phase deformation mode may reflect a shift in the governing mechanism of the expansion of the Tibetan Plateau from a rigid block to a critical wedge taper style. Thematic collection: This article is part of the Fold-and-thrust belts collection available at: https://www.lyellcollection.org/cc/fold-and-thrust-belts

Interaction between the far-field stress and crustal boundary faults in the kinematics of active deformation around the Lut Block, Eastern Iran

We investigate the effects of far-field stresses and major crustal boundary faults in the deviation of local stresses around the Lut Block of the southeastern Iranian plateau in the light of the 2010–2011 Rigan earthquakes. Dextral 2010 (Mw 6.5) and sinistral 2011 (Mw 6.2) Rigan earthquakes occurred in the southern edge of the Lut Block, where there is no report of moderate to large magnitude historical and instrumental seismicity. To address the style and distribution pattern of local stresses, we apply the inversion method to focal mechanism solutions of 74 earthquake events (1933–2018, Mw ≥ 4.8). The data were separated into six clusters including the Tabas – Dasht-e-Bayaz, East Lut, Kahurak, Rigan, Shahdad – Bam, and West Lut – Kuhbanan zones. Moving toward the Rigan area, the results indicate a gradual deflection in the direction of the horizontal σ 1 axis along the East Lut fault system (i.e., from north to south, Dasht-e-Bayaz: N044°E, East Lut: N051°E, Kahurak: N066°E, Rigan: N077°E), while it reveals a sharp change along the West Lut fault system (i.e., from north to south, Tabas: N044°E, West Lut – Kuhbanan: N010–13°E, Shahdad – Bam: N013–26°E, Rigan: N077°E). The deviation in the long-lasting strike-slip/transpressional stress regimes along the eastern and western boundaries of the Lut Block is mainly controlled by the geometry and kinematics of the East Lut fault system, and the direction of the Arabia – Eurasia convergence, respectively. The geodynamic interaction of the East and West Lut fault systems which bound the crustal block on both sides has a significant effect on the evolution of local stresses in the southern edge of the Lut Block, which is bounded by second-order faults that are the termination of the major faults. The results may apply to other crustal blocks limited in some boundaries by the second-order splays of crustal faults with different geodynamic implications. • We study stress states by inversion of focal mechanism data around the Lut Block. • Stress along the E and SE edges is mainly influenced by the East Lut fault system. • Along the W and SW edges stress is mainly controlled by the far-field stress regime. • Geodynamic interaction of major faults mainly affects local stresses in the S edge.

Dynamics of the African Plate 75 Ma: From Plate Kinematic Reconstructions to Intraplate Paleo‐Stresses

AbstractPlate reconstruction studies show that the Neotethys Ocean was closing due to the convergence of Africa and Eurasia toward the end of the Cretaceous. The period around 75 Ma reflects the onset of continental collision between the two plates as convergence continued to be taken up mostly by subduction of the Neotethys slab beneath Eurasia. The Owen transform plate boundary in the northeast accommodated the fast northward motion of the Indian plate relative to the African plate. The rest of the plate was surrounded by mid‐ocean ridges. Africa was experiencing continent‐wide rifting related to northeast‐southwest extension. We aim to quantify the forces and paleostresses that may have driven this continental extension. We use the latest plate kinematic reconstructions in a grid search to estimate horizontal gravitational stresses (HGSs), plate boundary forces, and the plate's interaction with the asthenosphere. The contribution of dynamic topography to HGSs is based on recent mantle convection studies. We model intraplate stresses and compare them with the strain observations. The fit to observations favors models where dynamic topography amplitudes are smaller than 300 m. The results also indicate that the net pull transmitted from slab to the surface African plate was low. To put this into context, we notice that available tectonic reconstructions show fragmented subduction zones and various colliding micro‐continents along the northern margin of the African plate around this time. We therefore interpret a low net pull as resulting from either a small average slab length or from the micro‐continents' resistance to subduction.