Search Results (443)

The timing and nature of the tectonic transition from Neo-Tethyan subduction to India-Asia collision along the NW Himalaya remain debated, particularly regarding the relationship between continental arc and post-collisional magmatism in the Karakoram and Kohistan batholiths. We present zircon U-Pb ages, whole-rock geochemistry, and zircon trace-element data from three granitoid samples from the Attabad Lake area (Karakoram Batholith) and the Nomal area (Kohistan Batholith). Zircon U-Pb dating yields crystallization ages of 103.4 ± 1.7 Ma for the Karakoram diorite, and 46.10 ± 0.79 Ma and 43.59 ± 0.88 Ma for the Kohistan enclave and host quartz monzonite, respectively. The Karakoram diorite shows LREE enrichment [(La/Yb)_N = 5.93–78.52] and positive zircon Ce anomalies (Ce/Ce* = 9.00–18.70), features broadly consistent with crystallization from an oxidized, subduction-related magma. In contrast, the Kohistan quartz monzonite exhibits elevated SiO₂ (65.01–66.35 wt%), low Mg# (25.9–27.2), and a flat to slightly negative Eu anomaly (Eu/Eu* = 0.94), which may reflect crustal melting during post-collisional extension. The enclave displays mantle-like signatures with high Sr (1623 ppm) and a positive Eu anomaly (Eu/Eu* = 1.14), suggesting a mafic recharge event. Zircon Th/U ratios (>0.1) and magmatic REE patterns support a magmatic origin for the dated zircons. These results are compatible with, but do not independently establish, previously proposed regional models. They provide additional local constraints that point to spatially heterogeneous magmatic evolution along the NW Himalayan syntaxis, with continental arc magmatism in the Attabad Lake area during the mid-Cretaceous and a transition to post-collisional extension in the Nomal area during the Eocene. Full article

The Xiaoyinuogaigou (XYN) gold deposit is located in the central Erguna Metallogenic Belt, northeastern China, and represents a characteristic example of Mesozoic gold mineralization in the Mongol–Okhotsk orogenic province. Despite its economic significance, the timing of mineralization and the nature of the ore-forming fluid system have not been well constrained. To address these questions, a systematic investigation of fluid inclusions, isotopes, geochemistry, and geochronology was conducted. The study reveals that: (i) four types of fluid inclusions are identified in auriferous quartz veins, with co-existing aqueous liquid-vapor and NaCl daughter-mineral three-phase inclusions, indicating the involvement of at least two chemically distinct fluids; (ii) the ore-forming fluids are characterized by moderate temperatures (163.2–357.6 °C), low to moderate salinities (3.06–11.34 wt% NaCleqv.), and H–O isotope compositions (δD = −133.3 to −112.3‰; δ¹⁸O fluid (SMOW) = +1.74 to +4.06‰) consistent with a hydrothermal system incorporating a substantial non-magmatic water component; and (iii) REE geochemistry and sulfur isotopes (δ³⁴S = +4.47 to +11.75‰, mean +8.29‰, n = 4) indicate that ore-forming materials were derived at least in part from the ore-hosting granite porphyry. Zircon U–Pb geochronology constrains the granite porphyry crystallization to 180 ± 3 Ma, and hydrothermal monazite U–Pb dating yields an age of 162.3 ± 3.6 Ma (MSWD = 0.95), for a Middle Jurassic hydrothermal event. We therefore conclude that XYN is an epizonal orogenic gold deposit formed during the late compressional to post-collisional transition of the Mongol–Okhotsk orogeny. Full article

The Baraul Banda Formation preserves an important Paleocene–Eocene sedimentary record within the western Kohistan–Ladakh Arc (KLA) and provides new constraints on sediment provenance and tectonic evolution during the final stages of Neo-Tethyan closure. This study integrates stratigraphic observations, detrital zircon U-Pb geochronology, and quantitative provenance analyses to investigate sediment sources and basin development within the western India–Eurasia collision zone. The formation comprises a thick marine siliciclastic succession of conglomerate, sandstone, siltstone, mudstone, and slate deposited in a tectonically active forearc basin. Detrital zircon age spectra are dominated by Mesozoic–Cenozoic populations (48%) with major peaks at ~57–61 Ma, ~70 Ma, ~85–90 Ma, and ~114–115 Ma, accompanied by subordinate Neoproterozoic, Mesoproterozoic, Paleoproterozoic, and minor Archean populations. These age components closely resemble those of the KLA, Karakoram Block, and Lhasa Block. Statistical provenance analyses indicate the strongest affinity with Eurasian arc-related terranes and contemporaneous forearc basin deposits of the Tar and Indus groups, whereas affinity with Indian Plate sources is minor. The provenance record indicates that sediment supply was dominated by erosion of the KLA and the adjacent Karakoram–Lhasa continental margin, with only minor recycled contributions from Indian-derived sources. The youngest zircon populations constrain deposition to the Paleocene–Early Eocene and record rapid erosion of active arc terranes immediately prior to the India–KLA collision. Placed within the regional magmatic chronology, these results support initiation of the KLA by ca. 155 Ma, Late Cretaceous amalgamation with the Karakoram–Lhasa margin at ca. 80–70 Ma, and subsequent collision with India at ca. 60–55 Ma. The KLA therefore remained an active pre-India-collision arc system for approximately 95–100 Myr, whereas collision-related magmatism continued until ca. 40 Ma, extending its complete magmatic history to approximately 115 Myr. Full article

The Bailingshan submarine volcanic-hosted iron deposit in the Eastern Tianshan provides an opportunity to investigate skarn hydrothermal evolution and high-grade Fe mineralization. This study integrates garnet petrography, in situ major- and trace-element analyses, garnet U–Pb geochronology, and amphibole ⁴⁰Ar/³⁹Ar geochronology. Four generations of grossular–andradite garnet (Grt1–Grt4) exhibit systematic textural and compositional variations reflecting the combined effects of crystal-chemical controls, hydrothermal fluid composition, and fluid–rock interaction. U–Pb dating of Grt2 yields 331.8 ± 8.9 Ma, linking the principal skarn formation and Fe mineralization stage to Early Carboniferous volcanism. Amphibole ⁴⁰Ar/³⁹Ar dating yields 302.6 ± 2.4 Ma, constraining a younger, localized hydrothermal overprint with limited Fe addition. Integrated evidence indicates that the Bailingshan deposit formed through a multistage, episodic hydrothermal evolution involving initial skarn formation, the principal Grt2–magnetite stage, subsequent shifts in hydrothermal conditions recorded by Grt3 and Grt4, and a localized late-stage hydrothermal overprint. These results not only constrain the timing of mineralization and subsequent overprinting but also offer valuable exploration implications for high-grade Fe mineralization in the Eastern Tianshan and comparable submarine volcanic-hosted iron districts. Full article

The NE- to E-trending ductile shear zones are well-exposed in the Wulashan–Daqingshan Complex of the Khondalite Belt, an Orosirian collisional orogen in the northwestern North China Craton. However, the timing of the shear zone activity remains ambiguous. In this study, we performed field-based structural observations and apatite and zircon U–Pb geochronology on these shear zones. The results show that the pre- and post-kinematic intrusions yielded magmatic zircon U–Pb ages of 1967 ± 24 Ma and 1812 ± 18 Ma, interpreted to broadly provide the maximum and minimum age constraints for shearing. Meanwhile, eight samples of mylonites gave a range of apatite U–Pb ages between 1878 ± 34 Ma and 1798 ± 29 Ma, considered to record the timing of shear deformation. Moreover, a similar metamorphic zircon U–Pb age of 1876 ± 38 Ma was also obtained from another mylonite. Combined with available data, we summarized that orogen-parallel ductile shear zones in the Helanshan, Qianlishan, Wulashan–Daqingshan and Jining Complexes of the Khondalite Belt have comparable deformation ages of 1904–1823 Ma, 1902–1801 Ma, 1906–1798 Ma and ~1866 Ma, respectively. These late Orosirian (1.90–1.80 Ga) shear zones were inferred to result from the prolonged orogenic processes of the Khondalite Belt, in response to the collision between the Yinshan and Ordos Blocks. Full article

Rutile is an oxide mineral widely distributed in igneous, metamorphic, and sedimentary rocks; it crystallizes in the tetragonal system. Trace-element abundances in rutile are influenced by the host-rock composition, redox conditions and crystallization history. Rutile exhibits high refractive index, strong dispersion, and adamantine luster. Its enrichment in high field strength elements (HFSEs) can be used to trace its formation environment. Owing to its inclusion-poor, compositionally uniform characteristics, rutile is particularly well-suited to in situ U-Pb geochronology. By integrating spectroscopic analysis, trace-element geochemistry, and U-Pb geochronology, this study systematically characterizes nine rutile samples from Madagascar, Pakistan, and Brazil, establishing a multi-dimensional scheme for origin discrimination. Spectroscopic analyses reveal that the infrared reflection band near 670 cm⁻¹ varies systematically with provenance. It appears as a broad, strong band in Madagascar samples, becomes weaker and narrower in Brazilian samples, and is partially absent in Pakistani samples. The Eg Raman mode of Brazilian rutile is slightly left-shifted and exhibits lower intensity, indicating a distinct lattice strain state. Analyzed samples occupy well-separated compositional fields on Nb–V, V–Ta, Zr–Hf and Nb–Ta binary variation plots. Specifically, Pakistani samples are characterized by high Nb and Ta contents and relatively lower V contents than the Brazilian and Madagascar samples. Madagascar samples show pronounced W enrichment and very low Cr. Brazilian samples display elevated Cr, V, higher U contents and more radiogenic Pb isotope compositions. Zr–W systematics and Cr–Nb bivariate discrimination allow inference of geological genesis. The Madagascar rutile is of hydrothermal origin, whereas the Pakistani and Brazilian rutile are metamorphic, derived from felsic/pelitic and mafic protoliths, respectively. LA-ICP-MS U-Pb geochronology yields a lower-intercept age of 504 ± 13 Ma (MSWD = 1.1) for the Madagascar sample (MD-1). This concordant, low-common-Pb age corresponds to the Pan-African orogeny and suggests strong potential as an in-situ U-Pb dating reference material. The Brazilian and Pakistani samples yield lower-intercept ages of 486 ± 53 Ma and 36.8 ± 2.9 Ma, respectively. However, the larger data scatter precludes their use as reference materials. Full article

The newly discovered Caijiagou gold deposit is hosted in metasedimentary rocks of the Silurian Taiyangsi Formation in the West Qinling Orogen (WQO), central China. Three mineralization stages are recognized: (1) the quartz–sericite–pyrite stage (Stage I), characterized by fine-grained, disseminated pyrite (Py1) and arsenopyrite (Apy1) with trace amounts of native gold; (2) the main ore-stage, the quartz–polymetallic sulfide–ankerite stage (Stage II), which contains coarse-grained euhedral pyrite (Py2) and arsenopyrite (Apy2) intergrown with ankerite and native gold; and (3) the post-ore calcite stage (Stage III), which is barren. Hydrothermal alteration assemblages include silicification, sericitization, pyritization, and carbonatization. In situ trace element analyses show that gold is mainly hosted in Py2 (avg. 2.86 ppm Au) and Apy2 (avg. 1.95 ppm Au), with consistently low Co/Ni ratios (<0.6) in ore-stage sulfides, supporting a metamorphic fluid origin. Sulfur isotope values (δ³⁴S = +6.47‰ to +11.96‰) point to sulfur derived from thermochemical reduction of marine sulfate. Apatite from the main ore stage (Stage II) yields a U–Pb lower intercept age of 237 ± 4.3 Ma (MSWD = 0.89), placing the mineralization in the Middle Triassic (Indosinian orogeny). These results are consistent with a sediment-hosted orogenic gold model, and the geochemical and geochronological signatures provide insights into the ore-forming process and regional metallogeny of the WQO. Full article

The Niukutoudong deposit, in the Qimantage metallogenic belt, western East Kunlun Orogenic Belt, is a recently discovered cobalt-rich polymetallic deposit. This study integrates zircon U-Pb geochronology and whole-rock geochemistry of the ore-hosting intrusions to constrain their emplacement ages, petrogenesis, and tectonic setting, thereby constraining the Early Devonian tectonic evolution of the East Kunlun area. The geochronological results for four samples demonstrate that the granite porphyry, granite, granodiorite, and gabbroic diorite at Niukutoudong were emplaced in the Early Devonian (403.7–406.3 Ma). Geochemically, the granite, granodiorite, and gabbroic diorite are high-K calc-alkaline, metaluminous to weakly peraluminous I-type granitoids, characterized by consistent enrichment in LREEs, negative Eu anomalies, enrichment in LILEs, and depletion in HFSEs. The granite porphyry, by contrast, is a peraluminous A-type granite distinguished by elevated total REE contents, pronounced negative Eu anomalies, and high HFSE abundances. The regional source characteristics of coeval intrusions, integrated with key incompatible element ratios (e.g., Nb/Ta, Ba/Nb), imply that the Early Devonian Niukutoudong intrusions were probably generated through crust–mantle interaction. Integrated evidence indicates that the Niukutoudong intrusive rocks formed in a post-collisional extensional environment following the closure of the Proto-Tethys Ocean. The mixed crust–mantle signature common to both regional and local Early Devonian intrusive rocks indicates that the East Kunlun Orogenic Belt had already transitioned from syn-collisional crustal thickening into a post-collisional extensional stage by the Early Devonian, marked by lithospheric thinning, asthenospheric upwelling, and crust–mantle interaction. This magmatism records the tectonic regime shift and likely has a genetic link with the Niukutoudong Co-polymetallic mineralization, offering critical insights into the Qimantage metallogenic framework. Full article

The thermal history of carbonate successions is fundamental to constraining hydrocarbon generation and reservoir diagenesis, yet traditional proxies such as vitrinite reflectance and apatite fission-track analysis are often inapplicable to marine carbonates because organic matter and suitable heavy minerals are scarce. This study evaluates an integrated carbonate isotope (Δ₄₇) thermometry and in situ U-Pb geochronology approach using a micrite matrix and three dolomite-bearing samples from the Upper Permian Changxing Formation in the Yuanba area, northern Sichuan Basin, southwestern China. The measured apparent clumped isotope temperatures (TΔ₄₇) range from 127.8 to 174.6 °C. The micrite matrix yields a U-Pb age of 257 ± 1.2 Ma, consistent with an early depositional or syndepositional origin, whereas the dolomite samples yield younger diagenetic ages. Coupling these time–temperature constraints with an exchange–diffusion model for solid-state reordering provides a preliminary, well-scale thermal scenario for the sampled intervals. The preferred model suggests rapid heating during Late Permian–Early Triassic and Middle Jurassic burial, followed by peak heating to approximately 220 °C in the Late Cretaceous at modeled maximum burial depths exceeding 8000 m, and subsequent cooling during Yanshan–Himalayan uplift and denudation. A conditional maturity model predicts that the underlying Wujiaping Formation source rocks entered the main gas-generation window (1.3% < Ro < 2.6%) by the Middle Jurassic and became overmature during peak heating in the Late Cretaceous. This dual-proxy framework is promising for carbonate-dominated petroleum systems but requires validation with a larger sample set and independent thermal indicators. Full article

The Lower Cretaceous volcanic–sedimentary succession in the Dehui Graben of the southern Songliao Basin preserves critical records of syn-rift volcanism and basin filling in NE China. This study presents an integrated dataset of zircon cathodoluminescence (CL) imaging, LA-ICP-MS U-Pb geochronology, trace-element geochemistry, and LA-MC-ICP-MS Lu-Hf isotopic analyses for four representative Yingcheng Formation samples collected from three boreholes (D102, D21, and D83) in the Dehui Graben. Zircon grains from samples S1 (gray crystal-vitric tuff, Well D102, 3050.5 m) and S3 (gray tuff, Well D21, 2287 m) are predominantly euhedral to subhedral with well-developed oscillatory zoning, elevated Th/U ratios (>0.4), and chondrite-normalized REE patterns characterized by depletion in light REEs, enrichment in heavy REEs, and pronounced negative Eu anomalies, all of which are diagnostic of a magmatic origin. The 37 zircon analyses from S1 yield ²⁰⁶Pb/²³⁸U ages ranging from 109 to 122 Ma, with a KDE peak at ~116 Ma and two inherited grains at 158 Ma and 262 Ma, whereas the 43 analyses from S3 define a narrow age population between 110 and 123 Ma with a KDE peak at ~114 Ma and a single inherited grain at 145 Ma. Together, these ages constrain Yingcheng Formation felsic volcanism in the Dehui Graben to the Aptian stage of the Early Cretaceous. In marked contrast, the 54 zircon analyses from S2 (dark gray crystal-rich tuff, Well D21, 2288 m) exhibit a polymodal distribution dominated by an Early Jurassic population (KDE peak ~181 Ma), with subordinate Permian–Triassic (~251 Ma) and Carboniferous (~325 Ma) components and a complete absence of Cretaceous-aged zircons. We interpret this population entirely as inherited (xenocrystic) zircons entrained from conduit wall rocks during the incipient phase of volcanic eruption. Notably, S2 and S3 were collected from the same well at depths separated by only 1 m, yet they display fundamentally contrasting zircon age spectra. This abrupt vertical discontinuity is consistent with a two-phase eruptive model in which an early xenocryst-rich volcaniclastic unit (S2), possibly related to conduit-wall entrainment during the initial eruptive stage, was rapidly followed by a juvenile magma-derived tuff (S3). Sample S4 (gray coarse sandstone, Well D83, 3273 m) contains 84 detrital zircon grains spanning 112 to 440 Ma, with a dominant Early Jurassic peak (~179 Ma) that correlates with widespread granitoids in the Zhangguangcai Range and a youngest single-grain age of 110.5 Ma that constrains the maximum depositional age of the Yingcheng Formation. All 86 zircon Lu-Hf analyses yield positive εHf(t) values (+0.8 to +9.2), with two-stage Hf model ages (TDM2) clustering between 536 and 1100 Ma and peaking at ~700–800 Ma (Neoproterozoic). These data indicate that the parental magmas were predominantly derived from partial melting of Neoproterozoic juvenile crust extracted from a depleted mantle source. Among the four samples, S3 records the highest mean εHf(t) (+7.1) and the youngest mean TDM2 (~672 Ma), which may indicate a relatively stronger depleted-mantle affinity during the extensional stage at ca. 114 Ma. The positive εHf(t) values of the ~181 Ma S2 xenocrysts further imply that the Early Jurassic magmatic event in this region also sampled juvenile Neoproterozoic crust, which thus served as the common source basement for both episodes of magmatism. A regional compilation reveals a systematic north-to-south younging trend of syn-rift volcanism across the Songliao Basin (Yingtai ~119 Ma, Dehui ~115 Ma, Wangfu ~110 Ma), with the Dehui Graben occupying a critical intermediate position that is consistent with the southeastward migration of back-arc extension possibly related to Paleo-Pacific slab rollback. Full article

The Tieshilong Pb-Zn polymetallic district is located along the northern margin of the Dongpo ore field in the middle section of the Nanling metallogenic belt, southern Hunan, China. It represents a typical granite-related, fault-controlled hydrothermal vein-type lead–zinc polymetallic deposit in southern Hunan. In recent years, large-scale tin mineralization has been newly discovered during exploration in the deeper and peripheral areas of the district. However, the timing and genetic nature of this tin mineralization remain undetermined, which limits understanding of the characteristics of the deposit’s metallogenic system and its deep exploration potential. In this study, we present in situ cassiterite U–Pb geochronology and trace element data from deep Pb-Zn-Sn orebodies in the Tieshilong mining district. LA-ICP-MS U-Pb analyses of cassiterite yield a Tera–Wasserburg lower-intercept age of 159.2 ± 6.2 Ma (MSWD = 1.4), indicating that Sn mineralization occurred during the Late Jurassic. This age overlaps, within uncertainty, with the main ca. 160~150 Ma W–Sn metallogenic event recognized throughout the Nanling belt. Trace element data reveal that Tieshilong cassiterite is enriched in Fe (1100–5800 ppm) and W (120–11,660 ppm), and depleted in Nb (0.1–87 ppm) and Ta (0–7.1 ppm). The Zr/Hf ratios range from 23 to 52, with a mean value of approximately ~36, which is close to the chondritic values. These geochemical signatures, together with the occurrence of cassiterite intergrown with hydrothermal quartz and its replacement by later sulfides, support precipitation from a granite-related magmatic–hydrothermal system. Based on the findings and the literature, the Tieshilong deposit is therefore interpreted as a Pb–Zn-dominant expression of a Late Jurassic granite-related polymetallic system, in which deeper Sn ± W mineralization was overprinted by later Pb–Zn–Cu sulfide mineralization along fault-controlled fluid pathways. The recognition of cassiterite-bearing, medium- to high-temperature assemblages at depth suggests that down-dip extensions, fault intersections, and strike-inflection zones of the ore-controlling structures represent priority targets for future exploration. Full article

The Ediacaran Dengying Formation 2nd Member (hereafter 2nd Member) in the Sichuan Basin is influenced by major tectonic events including the Caledonian, Indosinian, and Himalayan orogenies and this strata has experienced a complex hydrocarbon accumulation history, resulting in inconsistent gas–water contacts. To elucidate this complex history, this study investigates the diagenetic mineral filling sequence within the Dengying 2nd Member in the Penglai area. We integrated data from analytical techniques such as cathodoluminescence (CL), in situ trace element analysis, U–Pb geochronology, and fluid-inclusion microthermometry. Based on these analyses, this study established the paragenetic sequence, incorporating both diagenesis and hydrocarbon accumulation, for the Dengying 2nd Member. This sequence comprises eight distinct phases of mineral precipitation and hydrocarbon emplacement: fibrous dolomite, granular dolomite, fine crystalline dolomite, first-phase bitumen, medium crystalline dolomite, saddle dolomite, second-phase bitumen, and quartz. From this sequence, we propose a four-stage hydrocarbon accumulation model for the Dengying Formation: (1) primary migration and accumulation during the Indosinian period; (2) oil cracking to gas during the Yanshanian period; and (3) and (4) two distinct stages of gas pool adjustment during the Himalayan period. Corresponding to these stages, this study developed distinct accumulation models and simulated migration and accumulation processes during key stages. The results indicate that the distribution of paleo-oil pools exerts significant control over the location of present-day gas accumulations. Initial oil charge was controlled by the distribution of carrier beds and hydrocarbon charging pathways, with water zones observed more frequently in the lower intervals of the Dengying 2nd Member. Subsequently, gas generated from oil-cracking filled these carrier beds, with areas of gas enrichment correlating with zones of high paleo-oil saturation. Finally, during the later adjustment stages, fault activity induced gas remigration and leakage, significantly impacting the final trapping configuration and preservation of gas accumulations. Full article

Ophiolites are fragments of ancient oceanic lithosphere, serving as geological indicators for reconstructing ocean-continent transitions, plate convergence and paleo-ocean evolution in orogenic belts. The Kekedieba ophiolite was recently identified during a 1:50,000 regional geological survey. To constrain its formation age, material source and tectonic setting, this study conducted systematic petrological observations, geochemical testing and zircon U-Pb geochronological analyses on the ophiolite. This ophiolite consists of typical end-members, such as cumulate gabbro and diabase dykes. Trace element analyses and geochemical discrimination diagrams reveal that the basalts exhibit geochemical characteristics typical of mid-ocean ridge basalt (MORB), and the ophiolite suite as a whole belongs to the low-K tholeiite series. Differences in the degree of partial melting in the source region among various end-member rocks further indicate the complexity of its tectonic setting. LA-ICP-MS zircon U-Pb dating shows that the formation age of the gabbro is 321.4 ± 2.7 Ma, indicating that the Kekedieba ophiolite formed in the late Early Carboniferous. Combined with its tectonic slice-association relationship with Early Carboniferous island-arc volcanic rocks, it is identified as fragments of a SSZ-type supra-subduction zone ophiolite, which provides direct evidence for the subduction evolution of regional paleo-plates. Although some extrusive units retain MORB-like geochemical signatures inherited from early seafloor spreading, the island-arc affinities of the full lithological suite and subduction imprints in cumulates confirm a dominant SSZ origin. Full article

The Lower Anti-Atlas Supergroup (LAAS) constitutes a major Proterozoic sedimentary archive exposed along the northern margin of the West African Craton (WAC), yet its age, internal stratigraphy, and regional correlations remain controversial. This study integrates detailed sedimentological investigations, lithostratigraphic correlations, petrography, and new LA-ICP-MS U–Pb zircon geochronology from the Igherm Inlier (western Anti-Atlas, Morocco) to refine the evolution of the LAAS. Three representative stratigraphic sections allow subdivision of the succession into five lithostratigraphic units: the Coarse-Grained Quartz Sandstone, Lower Siliciclastic–Carbonate, Quartz Sandstone, Upper Siliciclastic–Carbonate, and Volcanic units. These units are correlated, from base to top, with the Tasserda Formation, Ifrane n’Taghatine Formation, Oumoula (Mimount) Formation, Tizi n’Taghatine Group, and Tachdamt Formation recognized elsewhere in the Anti-Atlas. Sedimentological data indicate deposition within a long-lived shallow-water system that evolved from tide-influenced braided fluvial channels, through mixed tidal-flat and peritidal platform environments, to extensional basaltic volcanism. Newly identified reworked volcanic tuffs from the Lower Siliciclastic–Carbonate Unit yield a maximum depositional age of 1857 ± 33 Ma, providing the first direct temporal constraint for this interval. Additional maximum depositional ages of 1880 ± 30 Ma for the Oumoula Formation and 1970 ± 29 Ma and 1904 ± 41 Ma for the Tizi n’Taghatine Group are consistent with previously published constraints. Detrital zircon populations with predominantly Paleoproterozoic and subordinate Archean dates were likely derived from the WAC. Correlation of zircon age spectra with those of the Taoudeni Basin supports the existence of extensive intracratonic depositional systems that evolved across the WAC during the Nuna and Rodinia supercontinent cycles, culminating in Tonian syn-rift magmatism represented by the ca. 883 Ma Tachdamt Formation. Full article

The Huomaxie granite in Ningdu, southern Jiangxi Province, is located in the central part of the Cathaysia Block. Previous studies assigned this pluton to the Huitong batholith as S-type granite, but lacked precise geochronological and petrogenetic constraints. This paper presents systematic petrography, whole-rock geochemistry, zircon U–Pb dating, in situ Hf isotopic analysis, and electron microprobe analysis (EPMA) of muscovite from the muscovite monzogranite of the pluton. The weighted mean ²⁰⁶Pb/²³⁸U age is 420.1 ± 3.1 Ma. The rocks are silicic, high-K calc-alkaline, and peraluminous S-type granites. Zircon ε_Hf(t) values range from −15.0 to −11.8, with two-stage Hf model ages (T_DM2) of 2360–2150 Ma. Geochemical characteristics and muscovite composition data indicate that the magma was derived from high-temperature partial melting of psammitic sedimentary rocks. Tectonic discrimination diagrams suggest that the pluton formed in a post-orogenic extensional setting. It was generated by lower crustal melting induced by asthenospheric upwelling. Full article