Tectonic Transition Research Articles

Petrochronological constraints on the late Mesozoic dynamics of paleo-Pacific plate and tectonic transition in Southeast China

ABSTRACT The late Paleoproterozoic tectonic evolution of the southern North China Craton (NCC) remains controversial, largely due to its complex structural position and ambiguous magmatic-metamorphic records. This study presents an integrated petrology, whole-rock geochemistry, and in-situ zircon U-Pb-Hf isotopic investigation of newly identified monzogranites from the Sushui Complex. LA-ICP-MS zircon U-Pb dating yields emplacement ages of 1904 ± 37 Ma and 1895 ± 37 Ma. Geochemically, these rocks are high-K calc-alkaline I-type granites characterized by elevated SiO2 and K2O/Na2O ratios, low A/CNK and Fe2O3 T/MgO values, and zircon saturation temperatures ranging from 635°C to 842°C. They exhibit a moderately fractionated REE patterns ((La/Yb)N = 1.76–35.92) with significant negative Eu anomalies (δEu = 0.42–0.71). Zircons exhibit uniformly negative εHf(t) values (−6.8 to −4.7) and Neo- to Mesoarchean two-stage Hf model ages (TDM2 = 2.82–2.96 Ga). These geochemical and isotopic features, combined with regional correlations, indicate that the monzogranite rocks were likely originated from partial melting of pre-existing Neoarchean TTGs, and formed in a syn-collisional setting. Combined with regional magmatic, metamorphic, and sedimentary evidence, we propose that the southern NCC underwent a tectonic transition from compressional collision to extension between 2.1 and 1.8 Ga. We further interpret the ca. 1.94–1.90 Ga tectono-magmatic events as recording the assembly of the Columbia supercontinent, and the ca. 1.80–1.70 Ga extensional activities as corresponding to its subsequent break-up.

Late Triassic gold mineralization in the Buziwan breccia pipe (North China Craton): Integrated geochronology reveals magma-driven hydrothermal system and tectonic transition during cratonic reactivation

The long-standing debate over whether the 2.2−2.1 Ga magmatism in the North China Craton was characterized by the opening and closing of continental rifts or subduction-collision processes has yet to reach a consensus. In this contribution, we present an integrated petrological and geochemical study on the 2.13−2.08 Ga Dongbaishishan syenites and monzo-syenogranites and Gujiacun monzogranites in the Jiaobei Terrane of the North China Craton. These granitoids display high SiO2, Na2O + K2O, Zr, Nb, Ga, Y, and heavy rare earth element contents, low MgO, Sr, P, Nb, Ta, and Ti concentrations, and negative Eu anomalies (0.25−0.86), together with high zircon saturation temperatures of 817−891 °C (an average of 851 °C), strongly suggesting A-type geochemical affinities. The rocks exhibit evolved Hf isotopic compositions (εHf[t] = −10.61 to +6.52, depleted mantle model ages with reference to the average continental crust [TDMC] = 2.9−2.5 Ga), supporting their derivation from remelting of 2.9−2.5 Ga Archean tonalite-trondhjemite-granodiorite under high heat flow and shallow depths, with minor contributions from juvenile mantle−derived materials. Likewise, the Gujiacun monzogranites and Dongbaishishan monzo-syenogranites and syenites show increasing δ18O values of 5.48‰−12.22‰, especially the Dongbaishishan granitoids, which show more enriched 18O (most δ18O values >8‰, up to 12.22‰), high Al2O3 contents and K2O/Na2O ratios, and low Fe2O3T contents, indicating the incorporation of sedimentary materials into their sources. The three granitoids have high Zr, Y, Nb, Rb, and Ta concentrations and plot mainly in the within-plate field, implying a continental rifting system operated in the North China Craton during 2.2−2.1 Ga. Further, a systematic compilation of published age and geochemistry data of 2.2−2.0 Ga granitoids in the North China Craton was conducted to provide key constraints on the early Paleoproterozoic tectonic setting. All the recompiled granitic rocks can be divided into two groups: group 1 (G1, 2.19−2.08 Ga) and group 2 (G2, 2.10−2.05 Ga). Most of the G1 granitoids exhibit rift-related A-type affinities. Combined with coeval tholeiitic mafic rocks and associated bimodal volcanic-sedimentary sequences, the extensional rifting system interpretation is highly reliable for the North China Craton ca. 2.2−2.1 Ga. In contrast, most of the G2 granitoids show attributes of arc-like I-S−type granites. Associated with synchronous calc-alkaline mafic magmatism, we suggest they were the products of subsequent subduction-collision in the North China Craton at ca. 2.1−1.8 Ga, supporting a consensus that the orogenic event was part of a global network of subduction zones and collisional belts facilitating the assembly of the supercontinent Columbia. This unusual temporal and compositional transition from G1 to G2 magmatism in the North China Craton may hint at a marked tectonic transition from extension to compression environments between 2.2 Ga and 2.0 Ga, potentially linked to global-scale supercontinent aggregation events.

ABSTRACTSediment flux analysis offers critical insights into the spatial and temporal distribution of clastic materials in sedimentary basins, enabling the reconstruction of tectonic features and source‐to‐sink processes. This study focuses on the Lower Cambrian Qiongzhusi Formation, a key hydrocarbon source rock and shale gas reservoir in the Sichuan Basin, western Yangtze Block. By integrating lithology, thickness, and density data from drillings and outcrops into a 3D ArcGIS model, we analysed sediment flux to resolve debates about the basin's tectonic history. Results reveal distinct spatial distributions between the upper and lower segments of the Qiongzhusi Formation: (1) The spatial distribution of clastic materials in the lower segment of the Qiongzhusi Formation was primarily controlled by the geomorphic constraints of the extensional trough, (2) The sedimentary center of the upper Qiongzhusi Formation shifted northwestward, exhibiting a distinct northwest‐thickening and southeast‐thinning trend. This spatial reorganisation reflects a fundamental change in basin dynamics: the lower segment's sedimentation was controlled by the geomorphic constraints of a weakly extensional trough, while the upper segment's asymmetric thickness and elevated sediment flux along the northwestern margin (linked to crustal shortening) signal the onset of weak compression. Collectively, these observations indicate a tectonic transition from a weakly extensional trough to a weakly compressive foreland basin, driven by regional compressional forces during the Early Cambrian. This study provides new constraints on the dynamic evolution of the Sichuan Basin.

Latest Early Cretaceous tectonic transition from contraction to large-scale extension in Southeast China: Insights from the magmatism along the Changle-Nan'ao Fault Zone

Rapid tectonic transition, crust-mantle interaction, and gold metallogenesis in the Jiaodong Peninsula, eastern China: Revealed by Early Cretaceous granitoids and microgranular mafic enclaves

Investigations of the pre-Cenozoic tectonic heritage of the Qaidam Basin have provided crucial insights into intracontinental deformation related to subduction and collision along the southern margin of the Eurasian continent. However, the pre-Cenozoic tectono-sedimentary development of the Qaidam Basin and the provenance of the pre-Cenozoic sediments have received limited attention. Here, we integrate sedimentological, heavy mineral and detrital zircon U–Pb data to elucidate the provenance of the Mesozoic strata and the associated pre-Cenozoic tectonic heritage in the SW Qaidam Basin. Our data show that the SW Qaidam Basin was characterized by separate fault-bounded basins with local provenance during the Early to Mid-Jurassic. A unified depression then developed across the basin during the Late Jurassic, with the Eastern Kunlun Range as a persistent detrital source. The Altyn Tagh Range gradually increased in importance through the Jurassic, achieving dominance by the late Early Cretaceous. This tectonic transition likely reflects the far-field effects of subduction along the southern continental margin. Upper Jurassic units in the Washixia and Hongshuigou sections on both sides of the Altyn Tagh Fault display striking similarities, allowing us to establish that the Altyn Tagh Fault experienced a strike-slip displacement of at least 350 km during the Cenozoic.

The Heilongjiang Complex in Northeast China (NE China), located at the primary suture zone between the Jiamusi and Songliao blocks, formed by the closure of the Mudanjiang Ocean. Understanding the opening and closure of the Mudanjiang Ocean is fundamental to deciphering the tectonic transition from the closure of the Paleo-Asian Ocean to the subsequent subduction of the Paleo-Pacific Ocean. This study conducted a comprehensive investigation of garnet amphibolite, epidote blueschist, and garnet-mica schist from the Heilongjiang Complex to constrain their protolith characteristics and metamorphic evolution. Phase equilibrium thermodynamic modeling of the garnet amphibolite revealed peak metamorphic pressure-temperature (P-T) conditions of 10.5−12.4 kbar and 693−724 °C, suggesting an intermediate geothermal gradient associated with the warm subduction of basaltic oceanic crust during the early stages of Mudanjiang Ocean subduction. The garnet amphibolites exhibit normal mid-ocean-ridge basalt−like geochemical signatures, with zircon U-Pb dating indicating a Late Permian protolith age of the oceanic crust ca. 255−254 Ma. Subsequent amphibolite-facies metamorphism occurred ca. 197 Ma. The epidote blueschist records peak P-T conditions of 13.2−14.7 kbar and 488−505 °C with geochemical affinities similar to those of ocean-island basalt. Zircon U-Pb ages of 263−260 Ma suggest its formation from a basaltic seamount setting within the Mudanjiang Ocean during the Middle Permian. The peak P-T conditions modeled for garnet-mica schist (15.2−16.0 kbar and 512−540 °C) also indicate a low geothermal gradient, comparable to that of the epidote blueschist. The 40Ar/39Ar phengite ages (187−165 Ma) of the metasedimentary rocks in the Heilongjiang Complex record the tectonic evolution from subduction of Mudanjiang Ocean crust to eventual collision between the Jiamusi and Songliao blocks. Integrating these findings with previous research, we propose a new tectonic framework for the evolution of the Mudanjiang Ocean. The Heilongjiang Complex represents a distinct orogenic rock sequence that records a complete and continuous Wilson cycle. The initial opening of the Mudanjiang Ocean is attributed to a backarc extensional environment in the western Jiamusi block, driven by the westward subduction of the Mongol-Okhotsk Ocean during the latest Carboniferous to Permian. The eventual closure of the Mudanjiang Ocean and the subsequent amalgamation of the Jiamusi and Songliao blocks occurred during the Late Triassic to Middle Jurassic, resulting from the westward subduction and compression of the Paleo-Pacific plate beneath the Jiamusi block. The Mudanjiang Ocean existed as a branch of Panthalassa or the Paleo-Pacific Ocean from the Early Permian to Middle Jurassic, with an estimated lifespan of ∼116 m.y. (ca. 288−172 Ma).

Summary The northeastern Tibetan Plateau is bounded by the left-lateral Altyn Tagh and Haiyuan faults. How crustal motion along these fault systems transitions to crustal shortening and uplift is key for deciphering the geodynamic link between the escape tectonics and the growth of the Tibetan Plateau. Here, we use the PS-InSAR observations, combined with GNSS and leveling data, to obtain a high-resolution 3D model of the present-day crustal motion in the northeastern Tibetan Plateau. The resolved deformation field covers the entire northeastern Tibetan Plateau with a spatial resolution of approximately 0.01° × 0.01 °. Our analysis of slip rates and strain partitioning reveals that crustal motion along the Altyn Tagh fault gradually diminishes eastward and is absorbed by thrusting and uplift in the Qilianshan orogenic belt within the plateau. A similar tectonic transition occurs between the Haiyuan fault and the Liupanshan orogen on the eastern margin of the plateau. Some of the eastward crustal motion is accommodated by the younger Xiangshan-Tianjingshan fault system to the north of the Haiyuan fault, indicating the ongoing northward expansion of the Tibetan Plateau. Our results align with geological evidence of crustal deformation in the past few million years, highlighting the continuing tectonic transition from eastward crustal motion along the left-lateral strike-slip faults to the growth of the Tibetan Plateau.

Abstract The late Carboniferous—early Permian sedimentary record from the Minas de Henarejos area, located in the SE Iberian Ranges, E Spain, is a key location to study the transition between the Variscan and the Alpine tectonic regimes and the changes between the Carboniferous to Permian flora related to the end of the cold stage of the Late Paleozoic Ice Age in the equatorial zone. The Minas de Henarejos Basin is unique in the Iberian Ranges, as it contains a thick succession of Carboniferous continental sediments rich in macroflora remains and with thick coal beds. The area was subjected to iron and coal mining during different periods of the nineteenth and twentieth centuries and at present it offers magnificent outcrops due to the intense coal extraction work carried out at the beginning of the last decade. The present multidisciplinary study has allowed us to define three new informal lithostratigraphic units based on their lower and upper boundaries, lithological, mineralogical, and sedimentary characteristics, the presence of macroflora, and their degree of deformation. The oldest Minas de Henarejos Unit (1), unconformably overlying Variscan basement, is characterized by dark gray lutites, sandstones, conglomerates, and coal beds deposited in low sinuosity fluvial systems that evolved to lacustrine systems. Based on its macroflora content, this unit has been dated as Stephanian B (late Carboniferous). The overlying Narboneta Unit (2), separated by an erosional unconformity, comprises white breccias and conglomerates of proximal alluvial fans and incipient fluvial systems. These are overlain by the red conglomerates of the Fuente del Compadre Unit (3), again separated by an erosional conformity. All three units underwent compressive deformation linked to the late-stage Variscan compressive regime, which is not noted in the overlying middle Permian Boniches Fm., this latter unit deposited after a long hiatus and comprising red conglomerates of fluvial systems related to large alluvial fans and linked to the extensional Alpine phase. A change in the type of paleosols, from the Histosols of wet climates to Entisols of alternating wet and dry periods, is in agreement with the clay mineral compositions, which suggests humid climate conditions during the Carboniferous and early Permian and a change to more arid conditions during Middle Permian times.

The Karamaili Granite Belt (KGB) in the southern margin of the Eastern Junggar is the most important tin metallogenic belt in the southwestern Central Asian Orogenic Belt. The plutons in the western part have a close genetic relationship with tin mineralization. The zircon U-Pb ages of the Kamusite, Laoyaquan, and Beilekuduke plutons are 315.1 ± 3.4 Ma, 313.6 ± 2.9 Ma, and 316.5 ± 4.6 Ma, respectively. The plutons have high silica (SiO2 = 75.53%–77.85%), potassium (K2O = 4.43%–5.42%), and alkalis (K2O + Na2O = 8.17%–8.90%) contents and low ferroan (Fe2O3T = 0.90%–1.48%), calcium, and magnesium contents and are classified as metaluminous–peraluminous, high-potassium, calc-alkaline iron granite. The rocks are enriched in Rb, Th, U, K, Pb, and Sn and strongly depleted in Ba, Sr, P, Eu, and Ti. They have strongly negative Eu anomalies (δEu = 0.01–0.05), 10,000 Ga/Al = 2.87–4.91 (>2.6), showing the geochemical characteristics of A-type granite. The zircon U/Pb ratios indicate that the above granites should be I- or A-type granite, which is generally formed under high-temperature (768–843 °C), low-pressure, and reducing magma conditions. The high Rb/Sr ratio (a mean of 48 > 1.2) and low K/Rb ratio (53.93–169.94) indicate that the tin-bearing plutons have undergone high differentiation. The positive whole-rock εNd(t) values (3.99–5.54) and the relatively young Nd T2DM model ages (616–455 Ma) suggest the magma is derived from partially melted juvenile crust, and the underplating of basic magma containing mantle materials that affected the source area. The results indicate the KGB was formed in the tectonic transition period in the late Carboniferous subduction post-collision environment. Orogenic compression influenced the tin-bearing plutons in the western part of the KGB, forming highly differentiated and reduced I, A-type transition granite. An extensional environment affected the plutons in the eastern sections, creating A-type granite with dark enclaves that suggest magma mixing with little evidence of tin mineralization.

The El Bola mafic–ultramafic intrusion (EBMU) in Egypt’s Northern Eastern Desert represents an example of Neoproterozoic post-collisional layered mafic–ultramafic magmatism in the Arabian–Nubian Shield (ANS). The intrusion is composed of pyroxenite, olivine gabbro, pyroxene gabbro, pyroxene–hornblende gabbro, and hornblende-gabbro, exhibiting adcumulate to heter-adcumulate textures. Mineralogical and geochemical analyses reveal a coherent trend of fractional crystallization. Compositions of whole rock and minerals indicate a parental magma of ferropicritic affinity, derived from partial melting of a hydrous, metasomatized spinel-bearing mantle source, likely modified by subduction-related fluids. Geothermobarometric calculations yield crystallization temperatures from ~1120 °C to ~800 °C and pressures from ~5.2 to ~3.1 kbar, while oxygen fugacity estimates suggest progressive oxidation (log fO2 from −17.3 to −15.7) during differentiation. The EBMU displays Light Rare Earth element (LREE) enrichment, trace element patterns marked by Large Ion Lithophile Element (LILE) enrichment, Nb-Ta depletion and high LILE/HFSE (High Field Strength Elements) ratios, suggesting a mantle-derived source that remained largely unaffected by crustal contribution and was metasomatized by slab-derived fluids. Tectonic discrimination modeling suggests that EBMU magmatism was triggered by asthenospheric upwelling and slab break-off. Considering these findings alongside regional geologic features, we propose that the mafic–ultramafic intrusion from the ANS originated in a tectonic transition between subduction and collision (slab break-off) following the assembly of Gondwana.

Tectonic inversion is often a dramatic event with significant implications, yet pinpointing its timing is challenging. The Red River fault, one of the most important high-strain structures in Southeast Tibet, experienced a kinematic reversal, but the exact timing remains debatable. The Dali normal fault system, situated at the northwestern end of the Red River fault, is kinematically linked to the right-lateral Red River fault. This linkage provides an excellent opportunity to unravel the timing of tectonic inversion. The Dali fault system also cuts across the hairpin-shaped reach of the Jinsha River, and its impact on river development would shed light on the landscape evolution influenced by normal faults. This study focuses on the Daju-Lijiang and Chenghai faults, two major branches of the Dali fault system, using zircon fission-track, apatite (U-Th)/He dating, and thermal modeling to reveal rapid exhumation in the footwalls starting at ca. 11−8 Ma and ca. 9−8 Ma, respectively. This shift indicates a tectonic transition from near east−west compression to east−west extension at the end of the Red River fault around the late Miocene (ca. 11−7 Ma), which is also supported by available data in the region. Furthermore, the normal faulting activity along the Daju-Lijiang fault since ca. 11−8 Ma neatly explains spatial and temporal variations in river incision between Tiger Leap Gorge and First Bend, which were influenced by oroclinal bending on the footwall. Tributary river profile analyses and geomorphic features show significant differences along the two sides of the Chenghai fault, which confirms the impact of normal faulting on differential incision of the Jinsha River. The mid−late Miocene transition in faulting styles appears widespread around the Chuan-Dian Block in Southeast Tibet, encompassing enhanced/weakened thrusting, the onset of strike-slip movements, and tectonic inversion. We propose that block translation relative to India’s northward advance and block rotation collectively induced stress field changes, leading to nearly synchronous tectonic adjustments in the Chuan-Dian Block during the mid−late Miocene. Overall, the Dali fault system exemplifies the coupled interplay between extensional deformation and fluvial landscape evolution.

The Southern Beishan Orogenic Belt (SBOB), an integral part of the Southern Central Asian Orogenic Belt (CAOB), is characterized by extensive Late Paleozoic magmatism. These igneous rocks are the key to studying the tectonic evolution process and the ocean–continent tectonic transformation in the southern margin of the CAOB and Paleo-Asian Ocean. We present zircon U-Pb chronology, in situ Lu-Hf isotopes, and whole-rock geochemistry data for Early–Middle Devonian volcanic rocks in the Sangejing Formation and granites from the Shuangyingshan-Huaniushan (SH) unit in the SBOB. The Wudaomingshiu volcanic rocks (Ca. 411.5 Ma) are calc-alkaline basalt-basaltic andesites with low SiO2 (47.35~55.59 wt.%) and high TiO2 (1.46~4.16 wt.%) contents, and are enriched in LREEs and LILEs (e.g., Rb, Ba, and Th), depleted in HREEs and HFSEs (Nb, Ta, and Ti), and weakly enriched in Zr-Hf. These mafic rocks are derived from the partial melting of the depleted lithosphere metasomatized by subduction fluid and contaminated by the lower crust. Wudaomingshui’s high-K calc-alkaline I-type granite has a crystallization age of 383.6 ± 2.2 Ma (MSWD = 0.11, n = 13), high Na2O (3.46~3.96 wt.%) and MgO (1.25~1.68 wt.%) contents, and a high DI differentiation index (70.69~80.45); it is enriched in LREEs and LILEs (e.g., Rb, Ba, and Th) and depleted in HREEs and HFSEs (e.g., Nb, Ta, and Ti). Granites have variable zircon εHf(t) values (−2.5~3.3) with Mesoproterozoic TDM2 ages (1310~1013 Ma) and originated from lower crustal melting with mantle inputs and minor upper crustal assimilation. An integrated analysis of magmatic suites in the SBOB, including rock assemblages, geochemical signatures, and zircon εHf(t) values (−2.5 to +3.3), revealed a tectonic transition from advancing to retreating subduction during the Early–Middle Devonian.

Geodynamic and magmatic evolution of the Kamyaran ophiolite complex, NW Iran: Tectonic transition from oceanic subduction to continental collision

Abstract Clarifying the Cretaceous evolution of the NE Asian continent has always been a key issue in unraveling the intracontinental responses of overriding plate to the subduction of Paleo‐Pacific plate during the past decades. However, the structural details and precise timing of the transition from the Early Cretaceous extension to the Late Cretaceous shortening are still poorly constrained. Here we present structural and geochronological data about the Pikou strike‐slip fault zone of the southern Liaodong Peninsula, where the Liaonan‐Wanfu metamorphic core complex (MCC) is well exposed, to decipher this vital tectonic transition. Field observations and structural analysis show that the Pikou strike‐slip fault zone is a sinistral transpressional fault zone that reworked the Liaonan‐Wanfu MCC. Inversion of fault‐slip data indicates that the brittle sinistral faulting was a result of NW‐SE compression. Geochronological constraints suggest that the Pikou strike‐slip fault zone was initiated as the high‐angle brittle normal faults at ca. 102 Ma, and then transformed into a sinistral transpressional fault zone in the early Late Cretaceous. Our new data, together with the regional multidisciplinary data, further confirm that the tectonic transition occurred at ca. 87 Ma. Thereby the Cretaceous evolution of the NE Asian continent since 135 Ma can be modified as the significant NW‐SE extension of 135–102 Ma, the gradually weakening extension of 102–87 Ma and the NW‐SE compression of 87–79 Ma. Their geodynamics were controlled by the alternating slab rollback and low‐angle subduction of the Paleo‐Pacific plate.

In rift basins, the vertical development and distribution of hydrocarbon source rocks show a makeable variability tightly linking to the tectono-stratigraphic interaction and evolution. This is also highly focused for petroleum industry, which is posing challenges for systematic hydrocarbon accumulation patterns. In the Zhu-1 Sub-basin of the Pearl River Mouth basin, the Eocene rift-related strata are important intervals for potential hydrocarbon exploration. This study analyzes the temporal and spatial attributes caused by tectonic transitions using 3D-seismic, drilling and logging well, and geochemical data, uncovering the impact of tectonic transition on the formation and development of hydrocarbon source rocks in the Eocene rift-related strata in the Zhu-1 Sub-basin. The results indicate that tectonic transitions caused by the HZ movement (∼43 Ma) have affected the migration of the centers of depocenter and subsidence and drove the formation of two main hydrocarbon source rocks in the upper and lower sections of the Wenchang Formation. The migration of rifting activity has influenced the lateral distribution of high-abundance dark high-quality hydrocarbon source rocks, and expand the range of high-quality hydrocarbon source rocks. The half-graden styles in the different sag change associated with tectonic transitions, and basement uplift and magmatic bottoming reshape the internal stratigraphic structure of the half-graden, leading to the variability of hydrocarbon accumulations. The proposed three hydrocarbon distribution modes, gentle slope dominant, steep-slope dominant and double-slope dominant, were developed in different sags. These models provide important geological theoretical support for the search of potential large-scale hydrocarbon reservoirs in the Pearl River Mouth basin, South China Sea.

The Yana–Kolyma collision orogen, Eastern Siberia, is one of world-class gold economic belts, where large gold deposits are localized, mainly in the Upper Paleozoic and Lower Mesozoic clastic rocks. Dike-hosted orogenic gold deposits are found and to a lesser extent studied, but they are important for understanding the structural control of mineralization within the framework of the orogen. Orogenic gold deposits of the Vyun ore field are hosted in Kimmeridgian–Titonian mafic, intermediate and felsic dikes, but they have no genetic connection with dikes. The late formation of deposits led to the fact that previously reactivated polydeformed structures were subsequently mineralized. The study of the structural control of mineralization is also complicated by superimposed late tectonic events. Based on the analysis of collected field materials, this paper presents the results of the study of deformation structures of the Vyun ore field within the framework of the Mesozoic evolution history throughout the geological time of the eastern convergent margin of the Siberian Craton. Four stages of deformations are identified. The pre-mineralization deformations and metamorphic and magmatic events share a common NE-SW shortening (D1 phase), which is related to the subduction of the Oymyakon oceanic slab and collision of the Kolyma–Omolon superterrane from the eastern margin of the Siberian Craton. This first stage is characterized by the superposition of several tectonic events under conditions of compression and progressive deformations (D1/1 and D1/2). Ore mineralization was formed at the end of compression in the same stress field (D1/2). Its structural control is determined by reactivation of older dikes and faults. Dikes are areas of heterogeneous stress and heterogeneous strain, being favorable for the concentration of ore fluids. The metallogenic time of formation of the gold mineralization is synchronous with the tectonic event, which likely reflects the final stages of the Kolyma–Omolon microcontinent–Siberian Craton collision of the Valanginian during crustal thickening. The main impulse of the Au mineralization D1/2 phase coincided with a slowdown in convergence. The post-mineralization tectonic regime was related to the Aptian–Late Cretaceous tectonic transition from compression to transpression. Transpressional tectonics were determined accordingly by W-E (D2 phase) and N-S (D3 phase) stress fields caused by several accretion events in the Cretaceous on the northern and eastern margins of Siberia. D4 phase extensional structures were caused by the opening of the Eurasian Oceanic basin in the Arctic in the Paleocene. The obtained results have a first-order impact on the understanding of the structural control of orogenic gold deposits and their relationship to the evolution of the host orogen. The new findings improve the tectonic knowledge of an area of interest for ore deposit exploration targeting orogenic gold deposits in Phanerozoic terranes of craton margins.

The timing of the final assembly of the China–Mongolia Block remains a subject of debate. This work presents zircon U–Pb–Lu–Hf isotopes, and whole-rock major and trace element data of granitoid samples from the north of Erenhot, within the Uliastai continental margin. Zircon U–Pb dating indicates that the intrusive timing of the granitoids was in the Pennsylvanian (318–298 Ma). Most granitoid samples are metaluminous to slightly peraluminous, exhibiting depletions in Nb–Ta–Ti–Sr–P and enrichments in Rb–Th and positive ε Hf (t) values (+11.87 to +15.19). They may be I-type granitoids, originating from the partial melting of juvenile crust. Calculations and compilations reveal a successive peak of Late Pennsylvanian whole-rock La/Yb ratios and Cisuralian zircon saturation temperatures, which might align with the Late Carboniferous tectonic transition from orogeny to lithosphere thinning in the Uliastai continental margin. Our findings suggest that closure of the Hegenshan Ocean occurred during the Middle Pennsylvanian, implying that the final assembly of the China–Mongolia Block was completed by the Late Carboniferous.