Search Results (296)

The Dongwujiiazi deposit is a structurally controlled orogenic gold deposit situated in the eastern part of the Chifeng–Chaoyang gold belt along the northern boundary of the North China Craton. This study establishes a comprehensive metallogenic model for the Dongwujiiazi gold deposit by integrating whole-rock geochemistry (major and trace elements), in situ trace elements and REEs in zircon, multi-isotope systems (H, O, S, Pb), and precise zircon U–Pb geochronology. Five types of intrusive and associated rocks are identified within the main biotite-pyroxene gneiss host of the Dongwujiiazi gold deposit: mylonitized granitic pegmatite, mylonitized porphyritic monzogranite, propylitized fine-grained quartz monzodiorite, quartz monzonite, and porphyritic dolerite. The gold-bearing polymetallic sulfide ores are composed of pyrite, chalcopyrite, sphalerite, galena, digenite, and native gold. Zircon grains in the Dongwujiiazi gold ore (2502 ± 15 to 2539 ± 18 Ma) are inherited from surrounding Neoarchean gneiss, recording older crustal sources rather than forming contemporaneously with the gold mineralization. H–O isotopes indicate that the ore-forming fluids were mixed in origin, involving both magmatic and metamorphic components. S and Pb isotopes suggest that the mineralizing sulfur was mainly derived from a magmatic source, while lead originated predominantly from lower crustal materials associated with the surrounding high-grade metamorphic rocks. In this study, we present a new metallogenic model for the Dongwujiiazi gold deposit, in which slab-derived and lower-crustal metamorphic fluids interacted with ascending magmas, resulting in fluid mixing and gold precipitation within structurally controlled zones of gneissic host rocks. Combined geochemical and isotopic evidence (H–O, S, Pb) indicates contributions from both magmatic and metamorphic sources, supporting formation as an intracontinental orogenic gold system in an active continental margin. Full article

The Daliangshan Fault Zone (DLSFZ) constitutes a key segment of the Xianshuihe–Xiaojiang Fault System (XXFS) and exerts fundamental control on the eastward extrusion of the Sichuan–Yunnan Block (SYB). In this work, we present new slip rate determinations at three key sites (Tekoujiagu, Yeer, Damulo) along its middle-southern segments using UAV-based high-resolution topography and OSL dating. Results yield late Quaternary slip rates of 4.5 ± 1.4, 3.7 ± 1.1, and 5.5 ± 1.0 mm/a, respectively. Combined with previous data, the slip rate is 1.5–3.1 mm/a in the northern segment, 1.36–4.3 mm/a in the middle and 2.5–4.5 mm/a in the southern segment, which exhibits a spatial pattern of “higher in the south, lower in the north, with transition in the middle”. Temporal evolution suggests increased slip rates from the Late Pleistocene to Holocene. These characteristics indicate that the DLSFZ is a heterogeneous deformation system, where strain focusing on the southern segment reflects the block’s eastward escape constrained by the rigid Sichuan Basin (SB). Thus, the DLSFZ, especially its southern segment, serves as a key structure regulating crustal extrusion at the southeastern margin of the Tibetan Plateau (TP). Full article

The Rio Grande Rise (RGR) is the largest oceanic plateau in the South Atlantic and represents a key natural laboratory for understanding oceanic plateau formation, deep-sea circulation, ecosystem functioning, and ferromanganese crust development. This study presents a critical synthesis of current scientific knowledge on the RGR, integrating geological, geophysical, oceanographic, biological, and geochemical evidence published over the last two decades. Geophysical data reveal a complex tectono-magmatic evolution involving Late Cretaceous plume-related volcanism, crustal thickening, rifting, and subsequent subsidence. The structural framework of the plateau is dominated by the Cruzeiro do Sul Rift, which plays a central role in controlling sedimentation, magmatism, and seawater circulation. Oceanographic studies demonstrate that the interaction between the southern branch of the South Equatorial Current and the complex topography of the RGR generates intense internal tides and bottom currents, strongly influencing sediment transport and benthic habitats. Biological investigations indicate that the RGR hosts diverse deep-sea communities, including sponge grounds, cold-water corals, and associated fauna, whose distribution is tightly linked to geomorphology and hydrodynamics. Ferromanganese crusts occurring on the plateau preserve valuable geochemical records of oceanographic and redox conditions, although their spatial distribution, thickness, and metal budgets remain incompletely constrained. Despite major advances, significant knowledge gaps persist regarding crustal structure, sedimentary evolution, ecosystem functioning, and mineral formation processes. This review highlights these uncertainties and outlines research priorities necessary to improve understanding of oceanic plateaus and deep-sea systems in the South Atlantic. Full article

This study evaluates the impact of assimilating the Crustal Movement Observation Network of China (CMONOC) global navigation satellite system (GNSS) tropospheric products on heavy-rainfall simulation over the complex terrain of the Sichuan Basin. Using the Weather Research and Forecasting model with the WRF Data Assimilation (WRF/WRFDA) three-dimensional variational (3DVar) system, we conducted a control (CTRL) experiment and a data-assimilation (DA) experiment for a primary heavy-rainfall event during 10–12 August 2020. The DA experiment applied 6 h cycling assimilation of station-based zenith total delay (ZTD) and precipitable water vapor (PWV). Compared with CTRL, DA improved the placement of the primary rainband and the depiction of peak rainfall. On 10 August, the observed rainfall core (~40 mm) over the northwestern basin was underestimated in CTRL (~15 mm) but was strengthened in DA (~25 mm). Hourly verification at a threshold of 2 mm h⁻¹ showed a higher maximum Threat Score (TS) in DA (0.292) than in CTRL (0.250), and the largest instantaneous gain reached 0.061. For 72 h accumulated precipitation, TS was higher in DA across multiple thresholds (≥10, ≥25, ≥50, and ≥100 mm), with the most pronounced improvement for heavier rainfall categories. Diagnostic analysis indicates that GNSS assimilation introduces dynamically consistent low-level moistening and strengthened convergence at 850 hPa, together with a better-aligned vertical ascent structure during the key stage of the event. An additional heavy-rainfall event during 21–23 August 2021 was further examined as a compact robustness test, and the results showed a generally consistent improvement in precipitation distribution and TS after GNSS assimilation. Overall, the present results suggest that cycling assimilation of CMONOC GNSS ZTD/PWV products can provide effective moisture constraints and improve heavy-rainfall simulation over the Sichuan Basin in the examined cases. Full article

Postseismic deformation observed by terrestrial Global Navigation Satellite System (GNSS) and seafloor GNSS-Acoustic techniques (GNSS-A) provides essential constraints on the depth-dependent viscoelastic structure of subduction zones. In this study, we collect and process decadal postseismic observations following the 2011 Tohoku-oki M_w9.0 earthquake, including 232 onshore GNSS stations and six offshore GNSS-A sites. After removing the interseismic velocity terms, we extract the postseismic deformation signals mainly driven by viscoelastic relaxation during the period from 3 to 9 years after the earthquake. The inversion is primarily constrained by horizontal displacements, which have higher accuracy than vertical observations. We adopt a radially layered viscoelastic Earth model with lateral heterogeneity between continental and oceanic domains based on the Burgers rheology and half-space dislocation theory. Using the least-squares principle, we invert for the optimal viscoelastic structure under the strong constraint of fixed mantle viscosity. The optimal continental and oceanic crustal elastic thicknesses are 24.4 km and 37 km, with minimum horizontal Root-Mean-Square errors (RMS) of 5.68 cm and 6.81 cm, respectively. The mantle viscosity shows significant depth-dependence and obvious land–ocean differences. These results verify the critical role of joint land and seafloor geodetic constraints and provide a refined viscoelastic structure model for subduction zones. Full article

Variscan two-mica granites are widespread in the Trás-os-Montes region (NE Portugal), yet their emplacement ages, petrogenesis, and relationship with Variscan deformation phases remain poorly constrained. This study integrates U–Pb zircon geochronology, whole-rock geochemistry, and oxygen isotope data to characterise four peraluminous two-mica granites in the Trás-os-Montes area (Fornos, Carviçais, Fonte Santa, and Bruçó) and to refine their tectonomagmatic context within the Central Iberian Zone. All granites are S-type, ilmenite-series, and derived from reduced magmas, as indicated by their strongly peraluminous compositions, mineral assemblages (muscovite ± biotite), absence of magnetite and presence of ilmenite, and high δ¹⁸O values (>11‰), consistent with partial melting of metasedimentary crust. U–Pb ages reveal two distinct magmatic pulses: an older event at ~340 Ma (Fornos and Fonte Santa granites), predating the onset of C3 deformation and likely associated with late C1 crustal thickening to early C2 tectonics, and a younger pulse at ~320–318 Ma (Carviçais and Bruçó granites). These magmatic pulses are linked to contrasting structural controls, with the older granites emplaced within regional-scale antiforms and the younger intrusions localised along structures related to C3 deformation. Together, these results document two discrete crustal melting events separated by ~20 Ma and record a progressive shift from fold-controlled to strike-slip-dominated granite emplacement during Variscan orogenic evolution. Moreover, the study highlights that tungsten mineralisation is preferentially associated with reduced, crust-derived granites emplaced during specific tectonic regimes, providing new constraints for metallogenic models in NW Iberia. Full article

The Beni Snassen belt (northeastern Morocco) hosts several Mississippi Valley-type Pb-Zn ± Cu occurrences localized along the Variscan basement/Lower Liassic carbonate interface within the Atlasic foreland system. This study integrates geological observations with organic petrography and C-O-S-Pb isotopic systematics to constrain the origin of mineralizing fluids, metal source, and ore-forming processes within a basin-scale metallogenic system. The host sequence consists of unmetamorphosed, dolomitized Pliensbachian carbonates with marl interbeds and organic-rich black shales. Mineralization is structurally focused along ENE-WSW and E-W faults and occurs as massive calcite-galena veins, “en échelon” tension gashes, vug fillings, and solution-collapse breccias. Ore-stage calcite exhibits restricted isotopic variability (δ¹³C = −4.7 to +1.2‰; δ¹⁸O = 14.9 to 19.7‰), consistent with rock-buffered basinal fluids and extensive fluid–carbonate interaction. Calculated δ¹⁸O_H2O values indicate precipitation from evolved saline brines variably mixed with meteoric waters. Galena δ³⁴S values (−20.9‰ to +10.3‰) reflect thermochemical sulfate reduction (TSR) under fluctuating redox conditions. Pb isotope compositions define a tight linear cluster between upper crust and orogene growth curves, indicating a predominantly upper crustal metal source, notably Triassic dolerite–diabase lithologies, with a possible contribution from organic-rich black shales. High-reflectance pyrobitumen (VR₀ up to 4%) indicates thermal conditions exceeding those predicted by local burial history, supporting long-distance migration of hydrocarbon-bearing metalliferous fluids from overpressured basin compartments, most plausibly the adjacent Neogene Guercif Basin. Fault reactivation during Late Miocene transtension fostered basin-scale fluid focusing and ore deposition. Hence, the Beni Snassen district represents a basin-integrated MVT system involving crustal metal leaching, organic-assisted metal transport, TSR-mediated sulfur reduction, and structurally focused fluid flow. These results refine metallogenic models for the Atlasic belts and highlight the exploration potential of structurally reactivated foreland basins hosting coupled hydrocarbon-hydrothermal systems. Full article

Long-span bridges are critical components of transportation infrastructure because they promote efficient connectivity between agricultural production centers, tourist destinations, and major urban areas. To construct these structures, the balanced cantilever method is widely used; however, the lack of rigid longitudinal connections between the pylons and the deck often allows for large displacement demands during seismic activities. Fluid viscous dampers (FVDs) are employed to mitigate these effects. This study investigates the impact of using FVDs at the abutments of the Hisgaura cable-stayed bridge located on the Curos-Malaga corridor in the department of Santander, Colombia. A nonlinear response history analysis was conducted using seismic records from crustal sources, scaled to the local seismic hazard, and performed in SAP2000©. The results indicate that the presence of FVDs does not adversely affect the axial forces in the stay cables under the Extreme Event Limit State I. Furthermore, demand reductions were observed at the pylon closest to the abutment (Pylon 4). Under critical seismic records, reductions of up to 81.95% in relative deck-pylon displacement, 62.17% in bending moment, and 58.46% in base shear were achieved. These findings demonstrate an improved global structural behavior under severe seismic loading conditions. Full article

Northeast China, situated in the eastern Central Asian Orogenic Belt (CAOB), marks the terminal closure zone of the Paleo-Asian Ocean (PAO) (eastern segment). At present, due to extensive Quaternary cover, the structural deformation characteristics and deep structure of the Solonker Suture Zone in the east of the Nenjiang–Balihan fault remain poorly constrained, which limits our understanding of the tectonic evolution of the PAO. This study integrates deep seismic reflection (DSR) and magnetotelluric (MT) sounding profiles to investigate the crustal structural, sedimentary framework, and tectonic evolution of the oceanic and continental crusts along the western slope of the Songliao Basin. Two regional detachment surfaces (D1 and D2) were identified. The D2 interface demarcates the upper crust’s basal boundary, overlain by multiple high-amplitude monoclinic reflections. The area below the D2 interface exhibits a network structure of arcuate and variably oriented reflections, indicating a dual-layered orogenic structure. The upper crust exhibits distinct structural domains defined by strongly contrasting monoclinal reflections: north-dipping, low-resistivity zones in the southern sector and south-dipping, high-resistivity zones in the northern sector. These oppositely oriented reflections have been interpreted as marking an Early Paleozoic accretionary wedge and oceanic island arc, respectively. Interposed between these opposing structural domains, the Paleozoic to Early Mesozoic forearc basin sequences are preserved, with a pre-Middle Permian oceanic basin identified north of the study area. By integrating characteristics of seismic reflection sequences with regional geological data, this paper clarifies the processes of closure and collision at the northern margin of the PAO (Eastern Segment). Full article

The northern Vietnam shelf, particularly the area adjacent to the Red River Fault Zone, is characterized by complex geology and active neotectonics. However, the patterns of degassing and the origins of hydrocarbon gases in this region remain poorly understood. In particular, the potential links between deep-seated fluid migration, fault systems, and gas anomalies in island groundwater systems have not been systematically investigated. This study presents preliminary results of dissolved methane, its homologues (C₂–C₅), helium, hydrogen, and carbon dioxide measurements in groundwater from Co To Island (Northern Vietnam), with the aim of identifying gas origins and assessing structural controls on fluid migration. A significant methane anomaly was discovered, with concentrations reaching up to 10% by volume in the northwestern part of the island. The hydrocarbon homologous series is traced up to pentane (C₅), and CO₂ content is also elevated, with a maximum of 5.4%. The average He concentration of 10.8 ppm significantly exceeds atmospheric equilibrium values, with maximum recorded concentrations of 18 ppm for He and 34.5 ppm for H₂. Stable carbon isotope analysis of methane (δ¹³C-CH₄ values ranging from −50.2‰ to −49.7‰ VPDB), combined with the presence of a complete C₁–C₅ hydrocarbon series and elevated mantle/crustal tracers (He, H₂), indicates a predominantly thermogenic/metamorphogenic origin for the gases, ruling out a purely biogenic source. The spatial distribution of anomalies is structurally controlled, closely associated with the NE-SW trending Co To Fault system and its intersections with subsidiary faults, as corroborated by recent electrical resistivity tomography data. These findings indicate intensive, focused gas leakage from a deep-seated source, likely related to thermogenic/metamorphic processes and active fault-mediated degassing. The results highlight the significant hydrocarbon potential of the region and underscore the critical role of neotectonic activity in controlling fluid migration pathways in island aquifer systems. Full article

Magnetotelluric (MT) inversion models are widely used to interpret crustal conductivity structures related to fluid pathways, deformation zones, and mineralization processes; however, evaluating the reliability of inversion-derived anomalies remains challenging when datasets contain subtle station-dependent distortions or residual cultural noise. We present a jackknife-inspired, model-space diagnostic framework based on leave-one-station-out (LOSO) inversion to quantify station influence and improve interpretation reliability. The workflow consists of (1) generating a LOSO inversion ensemble using identical inversion settings, (2) computing ensemble statistics and standardized perturbation metrics to identify sensitive zones, and (3) applying distribution-based diagnostics to classify station influence and guide construction of an ensemble-refined model. Synthetic experiments demonstrate that the framework distinguishes localized station-controlled artifacts from broadly supported structural responses, allowing targeted correction without altering robust features. Application to a field MT dataset acquired in a noise-affected environment shows that a mid-crustal conductive structure remains stable across the LOSO ensemble, while some shallow anomalies exhibit strong station dependence. The resulting ensemble-refined model introduces only localized modifications, demonstrating that ensemble-based model-space diagnostics provide a practical and reproducible strategy for validating MT inversion results and improving confidence in exploration-oriented conductivity interpretations. Full article

Geothermal field characteristics fundamentally control hydrocarbon generation, phase evolution, and preservation, and are particularly critical in deep to ultra-deep hydrocarbon exploration. The Tazhong Uplift is a key area for deep to ultra-deep hydrocarbon exploration in the Tarim Basin; however, its deep thermal regime and controlling factors remain inadequately characterized. This study aims to accurately characterize the geothermal field and crustal thermal structure of the Tazhong Uplift to provide thermal constraints for ultra-deep exploration. We systematically compiled system steady-state temperature data from 24 wells, bottom-hole temperature (BHT) data from 51 wells, and rock thermal property measurements. Using the one-dimensional steady-state heat conduction equation, present-day geothermal gradients at 0–5000 m depths and terrestrial heat flow were calculated, and formation temperatures were predicted at deep horizons (6000–10,000 m). Results show geothermal gradients at 0–5000 m of 18.5–26.7 °C/km (average 23.06 °C/km) and heat flow of 39.3–59.8 mW/m² (average 48.1 mW/m²), both significantly higher than basin averages. The distribution of the geothermal field is jointly controlled by basement structure and rock thermophysical properties. Basement highs typically exhibit elevated geothermal gradients and high heat flow. The dual-layer structure of “upper clastic rocks (low thermal conductivity, high heat production) + lower carbonate rocks (high thermal conductivity, low heat production)” results in a vertical differentiation characterized by a “high-upper, low-lower” geothermal gradient. Notably, the thick Upper Ordovician mudstone acts as a regional “thermal blanket”, significantly reducing geothermal parameters in the northern slope area. Crustal thermal structure analysis indicates a “cold mantle” signature of cratonic basins, with a thermal lithosphere thickness of ~134–145 km and a Moho temperature of ~581 °C. These findings reveal that despite the ultra-deep burial (>8000 m), the “cold” thermal background and the thermal regulation of the overlying diverse lithologies maintain formation temperatures within a range favorable for liquid hydrocarbon preservation, significantly expanding the depth limit for oil exploration in the Tarim Basin. Full article

The Jiaodong Peninsula hosts one of the largest gold provinces in the world. The Xincheng gold deposit, located within the Jiaojia gold metallogenic belt, is the largest deposit in this belt and represents a super-large fractured alteration-type gold deposit hosted in fracture zones with relatively well-preserved conditions. Mineralization and hydrothermal alteration are controlled by the Jiaojia Fault zone and its subsidiary faults. The Jiaojia Fault (JJF) serves as the principal ore-hosting structure of the Xincheng deposit, and its multi-stage activity has governed the mineralization, subsequent modification, and preservation of the deposit. However, the post-mineralization cooling, uplift, and exhumation history of the deposit remains poorly constrained. In this study, zircon and apatite fission-track thermochronology analyses were conducted, and inverse thermal history modeling of apatite was performed to reconstruct the tectonic-metallogenic evolution of the Xincheng gold deposit. The zircon fission-track ages range from 90.0 ± 4.0 to 118.0 ± 5.2 Ma, which are younger than the mineralization age (~120 Ma), indicating that the region experienced widespread cooling during the Late Early Cretaceous. This cooling event was likely related to crustal uplift and exhumation triggered by a transformation of the tectonic regime. The apatite fission-track ages range from 15 ± 1.8 to 38 ± 2.7 Ma, recording the Cenozoic cooling and uplift history after mineralization. The inverse thermal history modeling results show that the post-mineralization cooling process can be divided into three stages. The first stage, from 42 ± 5 to 30 ± 4 Ma, is characterized by rapid cooling, with an average cooling rate of 4.23 °C/Myr. The second stage, from 30 ± 4 to 12 Ma, represents a period of slow cooling, with an average cooling rate of 0.98 °C/Myr. Since 12 Ma, the third stage has been marked by renewed rapid cooling, with an average cooling rate of 4.17 °C/Myr. Variations in cooling rates among different stages reflect adjustments in the regional tectonic stress field and the influence of activity along the JJF. Based on the fission track thermochronological data and a reasonable estimate of the geothermal gradient, the total amount of exhumation since 120 Ma is calculated to be approximately 8.22 km. Integration of these results indicates that the shallow portion of the deposit has undergone a certain degree of erosion; however, the overall preservation conditions remain favorable, and significant exploration potential persists at depth and along strike. This study constrains the post-mineralization cooling and erosion history of the Xincheng gold deposit, reveals the controlling role of multi-stage tectonic activity on deposit preservation, and provides new temporal constraints and a scientific basis for preservation assessment and deep exploration of gold deposits in the Jiaodong Peninsula and in regions with similar tectonic settings. Full article

Volcanic magma plumbing systems is essential for understanding crustal–mantle material exchange and the dynamics of volcanic activity. The magnetotelluric method (MT) offers an effective tool for imaging conductive features from the crust to the lithospheric mantle. However, current survey strategies face a tradeoff between imaging resolution and acquisition cost. Here, we construct a lithosphere-scale synthetic model of a magma plumbing system and use 3D MT inversion, sensitivity analysis, and point spread function evaluation to assess the resolving capability of sparse versus dense arrays. Our results show that large-scale conductive anomalies in the mid–lower crust and lithospheric mantle can be reliably imaged using a sparse regional array with targeted densification in the crustal anomaly zone. This approach reduces field costs and computational demand. Guided by these findings, we conducted MT observations across the Longgang volcanic field and identified low-resistivity anomalies extending from the lithospheric mantle into the mid–lower crust. These features are consistent with the dense array MT inversion results. Our study demonstrates that an array strategy combining wide-area sparse coverage with targeted densification offers a cost-effective approach to image deep conductive structures, which may provide practical guidance for optimizing MT survey design in volcanic regions. Full article

Copper is a critical metal for the global energy transition. Yet, declining discovery rates and increasing demand necessitate more efficient mineral exploration strategies grounded in a mineral systems approach. The Carajás Province (Amazonian Craton, Brazil) is one of the world’s premier copper-producing regions, hosting several iron oxide–copper–gold (IOCG) and related deposits. The Northern Copper Belt (NCB), located near the boundary between the Carajás and Bacajá domains, records a multiphase deformational and metallogenetic evolution from the Neoarchaean to Paleoproterozoic. Despite extensive previous studies, uncertainties remain regarding the geometry, depth, and continuity of the regional structures that control copper mineralization, as well as the nature of the tectonic boundary between the Carajás and Bacajá domains. As a result, through an integration of airborne magnetic, gravity, gamma-ray spectrometry, morpholineament, and spatial analyses, we characterized the tectono-structural framework of the NCB and the southern Bacajá Domain. This will provide new constraints on the geodynamic evolution of this world-class copper metallogenic belt, elucidating crustal-scale structures and patterns of hydrothermal alteration and fluid pathways, and enhancing understanding of the potential for further discoveries. Full article