Lithospheric Strength Research Articles

Lithospheric Structure and Strength Variations in Antarctica From Joint Modeling of Elevation, Geoid and Seismic Data

AbstractAntarctica is renowned for its ancient cratons, difficult‐to‐observe sutures and active continental rifts. Detailed lithospheric structure and strength estimates are crucial for understanding the potential distribution, long‐term geological evolution, and deformation patterns of this continent. The lithospheric structure of the Antarctic continent is investigated based on joint modeling of elevation and geoid data with the incorporation of seismic data and thermal constraints. Moreover, these results are used to infer the yield strength envelopes across Antarctica. The laterally variable lithospheric strength is finally generated by vertically integrating the above envelopes. Our results show that the variations in the depth of the lithosphere‐asthenosphere boundary (LAB) are analogous to the variations in the integrated lithospheric strength; these parameters vary from 60 to 220 km and from 0.5 × 1013 Pa m to 4.5 × 1013 Pa m, respectively. Several regions of East Antarctica exhibit thick and strong lithospheric mantle, suggesting the presence of scattered cratonic blocks. In contrast, a thin and weak lithosphere is observed in the tectonically active West Antarctica and East Antarctic orogenic belts. Generally, our new LAB model correlates well with previous estimates, but there is a significant inconsistency beneath the Gamburtsev Subglacial Mountains, where a shallow LAB (∼120 km), high Moho temperature, and low strength (<1.0 × 1013 Pa m) are estimated. We speculate that this anomaly may be similar to the thinned lithosphere in Dronning Maud Land and reflects the removal of the mantle lithosphere during or after the orogenesis associated with the assembly of the Gondwana supercontinent.

The lithosphere-asthenosphere boundary and lithosphere replacement as informed by mantle xenoliths and their host lavas

Alkaline lavas hosting mantle xenoliths occur in the hot back arc of the Cordillera of western Canada and Alaska and provide constraints on lithosphere thickness (within 5 to 10 km) and controls on the lithosphere-asthenosphere boundary (LAB). Such information is complementary to geophysical investigations of lithosphere strength and deformation in similar continental regions. Barometry of spinel lherzolite xenoliths and alkaline lavas from the Cordillera show LAB depths from 50 to 80 km, and marked thinning of the lithosphere at the Cordillera-craton transition coincident with the Rocky Mountain Trench-Tintina Fault. Similar barometric data globally for continental intraplate lavas show a relatively common lava equilibration depth of 65 to 80 km, that mostly coincide with LAB depths observed by seismology, and with the spinel- to garnet peridotite transition. The LAB is inferred as accumulated partial melt, modulated in depth by mantle solidus depression caused by varying H2O storage capacity across the garnet-spinel peridotite phase change. This mechanism does not explain cases where LAB depths are < 65 km, which instead require locally hotter asthenosphere. In many regions preserving a shallow LAB, foundering and wholesale replacement of mantle lithosphere is invoked. With the exception of North China, mantle xenoliths sampled from continental margins record cooling timescales that appear far longer than required for foundering and replacement in the past 50 Myr. Either cooling histories cannot be adequately modelled using closure/diffusion arguments or wholesale replacement of mantle lithosphere is a dubious process.

Spatial variations in the effective elastic thickness of the Indian Ocean lithosphere

The Indian Ocean lithosphere is a complex assemblage of large igneous provinces, seamounts, plateaus and ridges of different loading ages and tectono-thermal evolution. As a proxy for the strength of tectonic plates, effective elastic thickness (Te) illustrates the relationship between surface deformation and lithospheric rheology of the diverse provinces in response to long-term tectonic processes. Mapping the spatial variations in lithospheric rheology can aid in understanding the detailed tectono-thermal history of the Indian Ocean. In this paper, we perform an assessment of the spatial variation of Te for the Indian Ocean from the inversion of the real free-air admittance between free-air gravity anomalies and bathymetry corrected for the effect of density variations within sediments using a continuous wavelet spectral analysis. Incorporating the effect of sediments substantially reduces Te estimates and better corresponds with the tectonic units in the study region. The results show low overall Te over the Indian Ocean attributed to magmatism and temperature during a multistage opening process. We further demonstrate that temperature controls the strength of warm and young oceanic lithosphere, evidenced by the positive correlation between Te and geothermal proxies. Finally, moderately low Te values at the Southwest Indian Ridge suggest a relatively cold ultraslow lithosphere with sparse magmatism compared to typical mid-ocean ridges.

Lithospheric Folding Controls the Intracontinental Orogen of South China: Insight from Numerical Simulation

Abstract Orogenic processes worldwide have been attributed to various deformation mechanisms. However, the significance of lithospheric folding in these processes has often been overlooked and underestimated. Within the South China Block (SCB), a region marked by notable temporal and spatial variability in intracontinental deformation, the emergence of fold-and-thrust belts during the Paleozoic and Mesozoic periods has captured a scientific interest. The mechanisms governing the genesis of these belts remain a subject of debate, with no discernible subduction interface accounting for the extensive-scale fold-thrust deformation. Moreover, the SCB presents a substantial variation in lithospheric thickness, exceeding 100 km, offering a plausible mechanism for lithospheric folding. To interrogate this mechanism, we conducted lithospheric compression simulations via two-dimensional finite element methods, incorporating variable viscosity both laterally and vertically within the SCB. Our models elucidate that disparities in lithospheric strength beget distinctive deformational manifestation within the SCB. We observe that a weaker lithosphere tends to uplift, whereas a stronger lithosphere tends to subside during compression. Lithospheric strength also influences the Xuefengshan uplift and the spatial distribution of deformational features. In addition, lithospheric folding can account for crustal shortening and the presence of deep anomaly structures. A compelling correlation emerges between lithospheric folding and fluctuations in Moho depth and lithospheric thickness, suggesting its potential influence over the prolonged topographical evolution and shifts in depositional environments within the SCB. This study sheds new light on the role of lithospheric folding in the complex geodynamic history of the SCB and highlights its importance in understanding the broader context of orogenic processes worldwide.

Quantitative estimation of the effective elastic thickness around the Burma Plate and correlation analysis of its influencing factors

The Burma Plate is a microplate that extends along the boundary between the Indian and Eurasian plates. It is characterized by an extraordinarily complex lithospheric tectonic setting, resulting from the continental collision in the north, the oceanic crustal subduction in the south, and the large amount of sediment from the Tibetan Plateau. The lithospheric strength is a key to understanding the tectonic evolution of the Burma Plate. In this study, we use topography and gravity disturbance data to estimate the spatial distribution of effective elastic thickness Te, which is a measure of lithospheric strength. The Tevalues range from ∼10 km to 80 km, with higher values in the Indian Plate than those in the other regions. The non-isostatic flexural effects of sediment loading and subducting slab pull can bias the Te estimation, with maximum reductions of ∼50 km and ∼10 km, respectively. The consistent distributions of the Te and the shear wave velocity anomaly ΔVsat 100 km depth suggest that the lithospheric strength is generally controlled by the thermal structure of the upper mantle. Meanwhile, the Te variations are highly related to the geometry of the subducting Indian Plate along the collision and subduction zones, indicating that the plate tectonics play a dominant role in determining the lithospheric strength of the Burma Plate.

Various lithospheric deformation patterns derived from rheological contrasts between continental terranes: insights from 2-D numerical simulations

Abstract. Continents are formed by the amalgamation of numerous micro-terranes and island arcs, so they have spatially varying lithosphere strengths. The crème brûlée (CB) model and the jelly sandwich (JS) model have been commonly used to describe continental lithosphere strength–depth variations. Depending on the strength of the continental lower crust, the CB and JS models can be further subdivided into two subclasses in which the I subclass (CB-I and JS-I) and II subclass (CB-II and JS-II), respectively, have a strong or weak lower crust. During the continental collision, lithosphere deformation is the byproduct of the comprehensive interaction of multiple terranes. Here we used 2-D thermomechanical numerical models that contain three continental terranes to systematically explore the effects of terranes with various strengths on continental deformation and studied the effects of different rheological assumptions on terrane deformation. We found four types of lithosphere deformation patterns: collision, subduction, thickening and delamination, and replacement. These simulation patterns are seen in observed deformation patterns and structures in East Asia, suggesting they are likely to be naturally occurring modes of intracontinental orogenesis.

The Dynamics of the India‐Eurasia Collision: Faulted Viscous Continuum Models Constrained by High‐Resolution Sentinel‐1 InSAR and GNSS Velocities

AbstractThe distribution and magnitude of forces driving lithospheric deformation in the India‐Eurasia collision zone have been debated over many decades. Here we test a two‐dimensional (2‐D) Thin Viscous Shell approach that has been adapted to explicitly account for displacement on major faults and investigate the impact of lateral variations in depth‐averaged lithospheric strength. We present a suite of dynamic models to explain the key features from new high‐resolution Sentinel‐1 Interferometric Synthetic Aperture Radar as well as Global Navigation Satellite System velocities. Comparisons between calculated and geodetically observed velocity and strain rate fields indicate: (a) internal buoyancy forces from Gravitational Potential Energy acting on a relatively weak region of highest topography (>2,000 m) contribute to dilatation of the high plateau and contraction on the margins; (b) a weak central Tibetan Plateau (∼1021 Pa s compared to far‐field depth‐averaged effective viscosity of at least 1022–1023 Pa s) is required to explain the observed long‐wavelength eastward velocity variation; (c) localized displacement on fault systems enables strain concentration and clockwise rotation around the Eastern Himalayan Syntaxis. We discuss the tectonic implications for rheology of the lithosphere, distribution of geodetic strain, and partitioning of active faulting and seismicity.

Spatial variations in effective elastic thickness and loading ratio in the Indo-Burma subduction zone based on the joint inversion of Bouguer coherence and admittance

Our knowledge of the mechanical structure and geodynamic evolution of the Indo-Burma Subduction (IBS) Zone is currently limited. The effective elastic thickness (Te) reflect the thermo-rheological characteristics of the subduction zone that aid in understanding the long-term deformation and geodynamic evolution. In the present study, we employed joint inversion of wavelet admittance and coherence to obtain the spatial variation in Te and the loading structure (F) over IBS based on satellite gravity and topography data. The spatial pattern of Te and F exhibit a remarkable correlation with the tectonic features of IBS. The Indo-Burma ranges (IBR) and the Central Myanmar basins (CMB) in the Burma Terrain (BT) are characterized by high lithospheric strength (Te = 35–40 km). In comparison, low lithospheric strength (Te = 15–20 km) prevails over the Shan Plateau (SP). High F (0.6–0.8) values over the Bay of Bengal and the SP indicate the dominance of the internal loading, while medium F (0.5–0.6) values over the CMB suggest mixed loading, probably related to the combined effect of thick sediments and dense downgoing slabs. Comparative analysis of Te with shear wave velocity and curie point depth indicates that the thermal state is crucial in controlling the lithosphere strength. Further, the absence of modern interplate seismic activity over the strong coupling zones characterized by high Te in BT suggests that the Indo-Burma megathrust is locked.

Lithospheric- and crustal-scale controls on variations in foreland basin development in the Northern Alpine Foreland Basin

The Northern Alpine Foreland Basin (i.e., Molasse Basin) developed due to flexural subsidence from slab- and topographic loading during continental collision between the Adriatic and European plates. Previous studies highlight a diachronous transition from underfilled- to overfilled conditions in the Molasse Basin in response to orogen-parallel variations in flexural subsidence and sediment supply. In this contribution, we investigate the lithospheric- and crustal-scale orogenic process(es) that generated this diachronous transition. For this, we conducted a tectonostratigraphic analysis of the Molasse Basin. Firstly, we constructed a 3D geological model to derive the architecture of the European margin during the Eocene onset of flexure. Second, 2D/3D reflection seismic- and borehole data were used to characterise the spatiotemporal development of depositional environments and syn-flexural normal fault kinematics in the German Molasse. Our data show a stepwise rather than continuous eastward migration of the underfilled- to overfilled transition. Furthermore, syn-flexural fault kinematics document a Rupelian to early Burdigalian northward younging trend and higher cumulative Cenozoic offsets in the Eastern German Molasse (< 230 m) compared to the Western German Molasse (< 150 m). This implies a west-to-east increase in the curvature of bending of the European plate, induced by along-strike variations in the magnitude of applied loads and/or European lithospheric strength variations. These variations drove lateral variations in accommodation space and sediment supply. Subsequently, this led to the diachronous underfill-to-overfilled transition in the Molasse Basin. Taken together, we suggest that the diachronous transition was driven by spatiotemporal variations in the thickening of the orogenic wedge supported by slab detachment, promoted by subduction- and collision of the irregular European margin.

Extensional exhumation of cratons: insights from the Early Cretaceous Rio Negro–Juruena belt (Amazonian Craton, Colombia)

Abstract. This study presents results from apatite fission track (AFT) thermochronology to investigate the thermal history and exhumation dynamics of the Rio Negro–Juruena basement, situated within the western Guiana Shield of the Amazonian Craton. AFT dating and associated thermal history modeling in South America has largely been restricted to the plate's margins (e.g., Andean active margin, Brazilian passive margin, and others). Our paper reports on low-temperature thermochronological data from the internal part of the western Guiana Shield for the first time. This area is part of a vast cratonic lithosphere that is generally thought to be stable and little influenced by Mesozoic and Cenozoic tectonics. Our data, however, show AFT central ages ranging from 79.1 ± 3.2 to 177.1 ± 14.8 Ma, with mean confined track lengths of ca. 12 µm. Contrary to what might be expected of stable cratonic shields, inverse thermal history modeling indicates a rapid basement cooling event in the early Cretaceous. This cooling is interpreted as a significant exhumation event of the basement that was likely driven by the coeval extensional tectonics associated with back-arc rifts in the Llanos and Putumayo–Oriente–Maranon basins. The extensional tectonics facilitated both basement uplift and subsidence of the adjoining basins, increasing erosional dynamics and consequent exhumation of the basement rocks. The tectonic setting shifted in the late Cretaceous from extensional to contractional, resulting in reduced subsidence of the basins and consequential diminishing cooling rates of the Guiana Shield basement. Throughout the Cenozoic, only gradual, slow subsidence occurred in the study area due to regional flexure linked to the Andean orogeny. Comparative analysis with low-temperature thermochronology data from other west Gondwana cratonic segments highlights that exhumation episodes are highly controlled by tectonic inheritance, lithospheric strength, and proximity to rift zones. This study underscores the complex interplay between tectonic events and the response of cratonic lithosphere over geological timescales and highlights extensional settings as an important geological context for craton exhumation.

Rift Propagation Interacting With Pre‐Existing Microcontinental Blocks

AbstractRift propagation is a 3D thermo‐mechanical process that often precedes continental breakup. Pre‐existing microcontinental blocks and the associated lithospheric strength heterogeneities influence the style of rift propagation. Interestingly, some rifts propagate into pre‐existing blocks and eventually cut through them (e.g., the Zhongsha Block and the Reed Bank), while others bypass these microcontinental blocks forming distinct overlapping rift branches (e.g., the East African Rift System). In this study, we use 3D numerical models to investigate the interaction between microcontinental blocks and rift propagation under different far‐field extension rates. In doing so, we assess the impact of mantle lithospheric thicknesses and lower crustal rheology on the style of rift propagation. Our models reproduce the two types of rift propagation, characterized by propagating rifts that either split or bypass the pre‐existing microcontinental blocks. We find that lithospheric thickness exerts dominant control, while lower crustal rheology of microcontinental blocks and the extension rate have less effect on rift propagation. Our model results can explain rift propagation patterns, block rotation and strong lithospheric thinning in the South China Sea, the East African Rift System, and the Woodlark Basin.

Role of Metasomatism in the Development of the East African Rift at the Northern Tanzanian Divergence: Insights From 3D Magnetotelluric Modeling

AbstractThe Northern Tanzanian Divergence in the East Africa Rift is arguably the best place on Earth to study the controls on rifting of thick lithosphere. Here, where the East Africa Rift intersects the Tanzanian Craton and the Mozambique Belt, the relationships between volcanism, faulting, pre‐existing structures and lithospheric thickness and composition can be observed. In this work, we carry out the first lithospheric‐scale 3D magnetotelluric modeling of the Northern Tanzanian Divergence and combine the results with experimental electrical conductivity and petrology models to calculate mantle composition, which is also inferred in the craton from reanalysis of garnet xenocryst data. Our results show that metasomatic materials exist in the cratonic lithospheric mantle and the relatively undeveloped southern part of the rift zone. However, the lithospheric mantle of the Mozambique Belt and the more developed northern section of the rift is more resistive and does not contain metasomatic phases. Combined with geochemical data from erupted lavas, these results suggest that, in zones that have experienced voluminous Cenozoic magmatism, melting events have destroyed the metasomes and dehydrated the mantle. Since the presence of magma is a primary control of lithospheric strength, rifting may become limited as the lithospheric mantle becomes dehydrated and harder to melt.

Variations of the effective elastic thickness evidence for a wide diffusive boundary between the North American and Eurasian plates in Siberia

Northeastern Eurasia is one of the least explored regions in the world. Very little geophysical data is available for this inaccessible area. Even the exact location of the plate boundary between Eurasia and North America remains a subject of ongoing debate. The effective elastic thickness (EET) of the lithosphere is a proxy for lithospheric strength and can provide insight into the thermal regime and tectonic processes. We have computed a high-resolution map of the EET for northeastern Eurasia using the fan wavelet coherence technique applied to the Bouguer gravity anomalies and topography/bathymetry data, appropriately adjusted to account for the influence of density variations within sediments. The results obtained provide insights into different tectonic regimes within this predominantly understudied region. In particular, we identify the boundary between the Eurasian and North American plates in Siberia as a rheologically weak diffusive zone extending from the Verkhoyansk and Sette-Daban Ranges to the eastern boundary of the Chersky Range. Unlike the Sette-Daban and Verkhoyansk Ranges, which were formed by plate collision and have an EET of 30–50 km, other mountainous regions have much lower EET values, usually less than 15 km. These areas have recently experienced tectonic activity that has weakened the lithosphere.

Lithospheric weakening by a small-scale plume and its geodynamic implications

The process of small-scale mantle plume emplacement within the continental lithosphere influences the dynamic topography and architecture of the lithosphere-asthenosphere boundary (LAB). Furthermore, plume emplacement alters the rheology of the crust and lithospheric mantle through melt-driven, mechanical and thermal weakening. Previous studies of plume emplacement within the lithosphere have described these outcomes, albeit without considering plume-driven weakening. In this study, we quantitatively evaluated the effects of small-scale plume-driven predefined weakening of the continental lithospheric mantle and crust on dynamic topography and LAB depth changes using a series of two-dimensional numerical models. Model calculations showed that small plume-driven predefined weakening led to short-wavelength dynamic topography and LAB depth reduction through both mechanical and thermal erosion of the lithospheric mantle by the plume. An increase in the degree of weakening decreased the lithospheric strength and reduced the LAB depth, thereby transforming the short-wavelength topography from depressions to elevations as the extensional kinematics shifted to compression. Our model findings explain the topography, lithospheric strength, and LAB depth constrained from natural small-scale plume emplacement zones.

On the More Complex Wavelength Dependency of Airy Isostasy in Icy Shells of Ocean Worlds

AbstractThe topography of ocean worlds is often used to infer ice shell thicknesses by assuming topography is compensated by a basal root. We systematically test the stability of isostatically compensated topography in ice shells. At short horizontal wavelengths, lithospheric strength can support surface topography, while at long wavelengths, buoyancy forces can support topography at the surface and base of the ice shell over geologic time scales. These behaviors are also seen for Airy isostasy in terrestrial worlds. Contrastingly at intermediate scales, the mechanically weak lower ice shell can inhibit the transfer of buoyancy forces to the surface. Factors such as surface temperature can alter the contribution of lithospheric strength, decreasing the stability of a compensating root. This nuanced understanding of icy shell lithospheres provides crucial insights for interpreting surface features and inferring underlying ice shell thickness, with substantial relevance for upcoming space missions to the Jovian system.

Thermodynamics of continental deformation

Continental deformation is known to be controlled by the interplay between tectonic and gravitational forces modulated by thermal relaxation-controlled lithospheric strength leading to oscillations around an equilibrium state, or to runaway extension. Using data-driven thermomechanical modelling of the Alpine Himalayan Collision Zone, we demonstrate how deviations from an equilibrium between mantle dynamics, plate-boundary forces, and the thermochemical configuration of the lithosphere control continental deformation. We quantify such balance between the internal energy of the plate and tectonic forces in terms of a critical crustal thickness, that match the global average of present-day continental crust. It follows that thicker intraplate domains than the critical crust (orogens) must undergo weakening due to their increased internal energy, and, in doing so, they dissipate the acquired energy within a diffused zone of deformation, unlike the localized deformation seen along plate boundaries. This evolution is controlled by a dissipative thermodynamic feedback loop between thermal and mechanical relaxation of the driving energy in the orogenic lithosphere. Exponentially growing energy states, leading to runaway extension are efficiently dampened by enhanced dissipation from radioactive heat sources. This ultimately drives orogens with their thickened radiogenic crust towards a final equilibrium state. Our results suggest a genetic link between the thermochemical state of the crust and the tectonic evolution of silicate Earth-like planets.

Lithospheric strength of the Anatolian plateau and implications for strong earthquake activity in Turkey

On February 6, 2023, the doublet earthquake including two main shocks with magnitudes MW7.8 and MW7.5, occurred near the western side of the East Anatolian Fault at the southeast boundary of the Anatolian Plateau in Turkey. Based on the WGM2012 Bouguer gravity anomaly data and the Etopo1 topography data, this study first introduced a joint inversion of admittance and coherence functions and used the Bayesian optimal parameter estimation method to obtain the effective elastic thickness Te and loading ratio F of the lithosphere for various tectonic units in the Anatolian Plateau. Secondly, we discussed the characteristics and influencing factors of the lithospheric mechanical strength and analyzed its relationship with seismic activity. The lithospheric mechanical strength of the Anatolian Plateau showed clear lateral heterogeneity and a "weak-strong-weak" spatial pattern from east to west, reflecting various tectonic processes. At last, the strong seismic activity was found where the lithospheric strength was low in the Anatolian Plate. We also incorporated GPS strain rate and other results to investigate the tectonic background and primary causes of the MW7.8 and MW7.5 doublet earthquakes in Turkey. The results have a good insight into urban safety design in the Turkish region, including post-disaster rehabilitation, earthquake hazard assessment, and loss reduction.

Tectono‐Magmatic Evolution of Asymmetric Coronae on Venus: Topographic Classification and 3D Thermo‐Mechanical Modeling

AbstractVenus is the only other Earth‐sized planet in the Solar System but it does not exhibit evidence of plate tectonics that dominates geological processes on Earth. Surface deformation on Venus is mainly driven by mantle convection and plume‐lithosphere interactions, likely represented by the widespread development of the circular volcano‐tectonic features known as coronae. Here, we present a joint study of mission data analysis and 3D modeling of asymmetric coronae on Venus. We systematically analyze 155 of the largest coronae on Venus in terms of surface topography and morphology. We establish that 75% of those coronae are radially asymmetric, and further sub‐categorize them based on their adjacent topography. This analysis reveals that many asymmetric coronae are positioned at a topographic transition between a lowland and plateau (termed topographic margin). With state‐of‐the‐art 3D numerical models, we investigate the physical processes behind plume‐margin interactions on Venus. We find that several tectonic styles may be responsible for asymmetric coronae at topographic margins, including lowland‐sided subduction, plateau‐sided lithospheric dripping, and an embedded plume. The gradient in lithospheric strength across the topographic margin controls these tectonic styles, and larger gradients enhance lithospheric resurfacing and the lifetime of the coronae. We also find that the density increase associated with the basalt‐to‐eclogite phase change provides the extra negative gravitational force required for downgoing crust to be recycled into the mantle. The models presented in this study reproduce a wide set of asymmetrical corona features found on Venus and suggest that they are generally more long‐lived than symmetric coronae.

Study on effective elastic thickness of lithosphere and its tectonic significance in surrounding area of Ordos Block

Based on EIGEN6C4 gravity field model data and ETOPO1 topographic data, we adopt the correlation analysis method based on Fan wavelet to calculate and analyze the distribution characteristics of effective elastic thickness (Te) and load ratio (F) of lithosphere in surrounding of Ordos block. On this basis, the relationship between the lithosphere Te and geological structure, seismic distribution, terrestrial heat flow and crustal deformation is analyzed. The results show that the lithosphere Te in the surrounding area of the Ordos block is obviously different among the tectonic blocks. The lithosphere Te value is low in the south of Qinling orogenic belt and the east of Fen-Wei graben basin. The maximum lithosphere Te value is distributed in the northwest and northeast margin of Ordos block. The lithosphere Te value is negatively correlated with the load ratio F. Earthquakes mainly occur in areas with low lithosphere Te value. Small lithosphere Te value indicates low strength of lithosphere. In such areas, the ability to resist crustal deformation is weak, and it is easy to generate stress accumulation and breed earthquakes. The area with high terrestrial heat flow value corresponds to low lithosphere Te value, showing a negative correlation. However, this negative correlation does not exist in the northwest margin of Ordos Block and Alashan border area, and the eastern margin of Ordos Lvliangshan area. Haiyuan-Liupanshan area has strong tectonic activity, frequent earthquakes and low lithosphere Te value. The internal strain accumulation of Ordos block is small, and the lithosphere Te value is high. The strain rate of the northern Shanxi fault depression zone is large, but the lithosphere Te value is also large, it is speculated that the terrestrial heat flow is the main factor affecting the lithosphere Te value.

The stability of cratons is controlled by lithospheric thickness, as evidenced by Rb-Sr overprint ages in granitoids

The ancient cores of modern continents, cratons, are the oldest blocks of “stable” lithosphere on Earth. Their long-term survival relies on the resistance of their underlying thick, strong, and buoyant mantle keels to subsequent recycling. However, the effect of substantial geographical variations in keel thickness on the post-assembly behaviour and mass movement within these continental cores remains unknown. Here, we demonstrate that the spatial distribution of fluid-reset in-situ Rb-Sr ages for Paleo-Mesoarchean (3.6–2.8 billion years ago; Ga) granitoids of the Pilbara Craton, Australia shows remarkable correlation with independently-constrained lithospheric thickness models. Without craton-wide heating/magmatic events, these anomalously young Rb-Sr ages document episodes of fluid infiltration into granitoid complexes as a response to lithospheric reactivation by far-field stresses. This correlation implies that craton-wide fluid mobilization triggered by extra-cratonic Neoarchean to Mesoproterozoic (2.8–1.0 Ga) tectonic events is facilitated by variations in lithospheric strength and thickness. Compared to areas of older overprints, the two-thirds of the craton comprised of younger reset ages is underlain by comparatively thin lithosphere with higher susceptibility to reactivation-assisted fluid flow. We propose that even the strongest, most pristine cratons are less stable and impermeable than previously thought, as demonstrated by the role of granitoid complexes and cratons as selective lithospheric “sponges” in response to minor tectonic forces. Therefore, variations in lithospheric thickness, likely attained before cratonization, exert a crucial control on billions of years of fluid movement, elemental redistribution and mineralization within ancient continental nuclei.