Keqiang Zhao

Stream-sediment anomalies around the Sawayardun gold deposit integrate mineralized detritus with variable lithological and hydraulic backgrounds. This study evaluates whether multielement coherence and spatial continuity can distinguish Au-related signals from that mixed background in 1080 primary samples and 35 field duplicates. Au is strongly right-skewed (median 1.62 ng/g, P95 6.55 ng/g, maximum 754.3 ng/g). Correlation and hierarchical clustering identify Au–As–Sb–Mo as the most persistent mineralization-related association, with a secondary Bi contribution; Ag and Cu provide important local support, whereas Co–Cr–Ni–Sn–W mainly record broader lithological variation. Three rotated factors explain 75.35% of total variance. F1 explains the largest share (39.78%) and is most effective for characterizing lithological background, whereas F3 (17.28%) is most effective for gold targeting because Au, As, Sb, and Mo load together and its high scores form spatially coherent clusters. A robust composite index and P95 spatial grouping delineate eight targets. T1–T3 substantially reproduce conventional anomalies HS4, HS2, and HS1; T4 partly overlaps HS3; and T5–T6 are new multielement targets. Maximum Au values in HS1–HS4 are 14.9, 14.4, 49.8, and 754.3 ng/g, respectively, and each anomaly is supported by a different pathfinder suite. Removing the maximum Au value leaves the F3 loading vector nearly unchanged (r = 0.997). The strongest sedimentary Au responses are most plausibly related to upstream mineralized shear zones, weathering release of Au-bearing sulfides, and hydraulic concentration, but catchment mixing and a possible nugget effect preclude direct inference of orebody boundaries. The results provide a transparent basis for staged field verification rather than confirmation of mineralization.

Thermomagnetic-fraction geochemistry has shown promise beneath transported cover, but area-scale applications rarely combine explicit element-association analysis, statistical robustness tests and transparent target prioritization. We evaluate this workflow in the largely covered Jing’erquan Ni-Cu metallogenic area using 985 soil samples collected over approximately 140 km² at an average spacing of about 300 m (7.0 samples km⁻²). After removal of pre-existing strongly magnetic grains, 100 g aliquots were heated under oxygen-limited conditions at 650 °C for 45 min, and the newly generated magnetic fraction was separated at an instrument-current setting of 1 A. Twelve indicators were analyzed using descriptive statistics, correlation analysis, hierarchical clustering, principal component analysis (PCA), spatial clustering and a three-term composite score. Four rotated factors explain 75.1% of the variance; Cr and Ni load at 0.95 on F2, while TFe₂O₃, Zn, Co and Cu covary on F1. Pearson–Spearman matrix agreement (r = 0.990), winsorized-versus-original Pearson agreement (r = 0.999), and PCA factor-congruence coefficients (>0.998) show that the principal associations are not controlled by the largest Cu, Ni or Cr values. Alternative composite weights retain all eight named follow-up targets, although internal ranking changes when Cu is emphasized. Among them, JQ-1–JQ-4 are assigned high follow-up priority by the expert-informed score. The coincidence of JQ-1 with the known Jing’erquan Ni-Cu mining area provides an internal plausibility check for the workflow, whereas JQ-2–JQ-8 remain unverified follow-up targets. These results show that the thermomagnetic-fraction dataset delineates multielement surface geochemical anomalies in covered terrain and can serve as a complementary screening tool for subsequent Ni-Cu exploration.

The Minghuazhen Formation in the Cangdong Sag of the Bohai Bay Basin is a key sedimentary unit for investigating regional provenance evolution, paleoclimate variations, and hydrocarbon potential in Eastern China. This study integrates mineralogical and geochemical analyses to explore sedimentary characteristics. Techniques include X-ray diffraction (XRD), major/trace element compositions, rare earth element (REE) distributions, and organic carbon content. XRD data and elemental ratios (e.g., Al/Ti, Zr/Sc) suggest a predominant felsic provenance, sourced from acidic magmatic rocks. The enrichment with light rare earth elements (LREE: La–Eu) and notable negative Eu anomalies in the REE patterns support the interpretation of a provenance from the Taihangshan and Yanshan Orogenic Belts. Geochemical proxies, such as the Chemical Index of Alteration (CIA) and trace element ratios (e.g., U/Th, V/Cr, Ni/Co), indicate a warm and humid depositional environment, characterized by predominantly oxic freshwater conditions. Organic geochemical parameters, including total organic carbon (TOC), total nitrogen (TN), and C/N ratios, suggest that organic matter primarily originates from aquatic algae and plankton, with C/N values predominantly below 10 and a strong correlation between TOC and TN. The weak correlation between TOC and total carbon (TC) indicates that the organic carbon is mainly biological in origin rather than carbonate-derived. Although the warm and humid climate promoted the production of organic matter, the prevailing oxic conditions hindered its preservation, resulting in a relatively low hydrocarbon generation potential within the Minghuazhen Formation of the Cangdong Sag. These findings provide new insights into the sedimentary evolution and hydrocarbon potential of the Bohai Bay Basin.

The proven gold deposits in the Jiaodong Peninsula, North China Craton, exceed 5,500 tons; these deposits are termed “Jiaodong type” or “Craton destruction type” owing to their unique geological features. Metallogenic chronology has dated the formation of these deposits at 120 ± 2 Ma. The development of such significant gold deposits in a relatively short period can be characterized as “explosive gold mineralization” and its driving factors are still under investigation. To clarify the geochemical characteristics, genesis and thermal history of a newly discovered quartz monzodiorite in the Tianqishan area, Shandong Province and their relationship with gold mineralization, the geochemistry of major and trace elements, zircon U–Pb isotope chronology, zircon Hf isotopes, and apatite fission track (AFT) thermochronology are analyzed. Our results show that the Tianqishan quartz monzodiorite, emplaced at ca. 119 Ma, is a metaluminous, high-K calc-alkaline rock, formed by mixing of mantle and crustal melts in a tectonic setting of North China Craton thinning. The AFT thermal history modeling results reveal four cooling events since the formation of the Tianqishan quartz monzodiorite and affirm two extensional stages in the Jiaodong Peninsula during the Early Cretaceous. The rapid exhumation of the crust of the Jiaodong Peninsula terminated at approximately ca. 120 ± 2 Ma, which may be due to the decoupling between crustal detachment and lithospheric mantle detachment in the Jiaodong Peninsula. Notably, the explosive mineralization of gold deposits aligns with the end of rapid exhumation in the Early Cretaceous, suggesting that decoupling between crustal and lithospheric mantle detachment is a plausible explanation for this phenomenon. This study provides critical new insights into the geodynamic processes governing Early Cretaceous lithospheric thinning and offers key constraints on the mechanisms driving explosive gold mineralization in the Jiaodong Peninsula.

Nanhong agate, esteemed for its vivid color and natural shine, is experiencing a scarcity in supply despite its high demand. The primary deposits of agate, typically found near the surface, have not been extensively explored due to the predominance of traditional manual excavation methods. This research examined the Nanhong agate deposits in the Zhaojue–Meigu region of Liangshan, China, employing the integration of geological and geophysical surveys. Field geological surveys allowed us to outline the general areas where agate is found. Following this, using magnetic surveys, vertical electrical sounding, and controlled-source audio magnetotellurics, agate deposits were located within the conglomerate layer of the second member of the Feixianguan Formation from the Lower Triassic period at depths of less than 100 m. Our results identify mineralized layers, Xuanwei Formation mudstone, and the underlying bedrock, thus supporting the creation of a mineral prediction map. This research provides essential insights and guidance for agate exploration and the development of associated mineral resources.

The Hongshan complex, located in the southern part of the Taihang Mountains in the central part of the North China Craton, consists of syenite stocks (including fine-grained biotite aegirine syenite, medium-grained aegirine gabbro syenite, coarse-grained aegirine gabbro syenite, syenite pegmatite, and biotite syenite porphyry), with monzo-diorite and monzo-gabbro dikes. This paper presents zircon U-Pb ages and Hf isotope data and whole-rock geochemical data from the Hongshan complex. LA–ICP-MS zircon U–Pb age from the fine-grained biotite aegirine syenite, monzo-diorite, and monzo-gabbro are 129.3 ± 2.0 Ma, 124.8 ± 1.3 Ma, and 124.1 ± 0.9 Ma, respectively, indicating their emplacement in the Early Cretaceous when the North China Craton was extensively reactivated. The monzo-diorite and monzo-gabbro have low SiO₂ contents (48.94–57.75 wt%), total alkali contents (5.2–9.4 wt%), and εHf (t) values of −22.3 to −18.4 and are enriched in MgO (4.0–8.2 wt%), Al2O3 (14.3–15.8 wt%), light rare earth elements (LREEs) and large ion lithophile elements (LILEs). Interpretation of elemental and isotopic data suggests that the magma of monzo-diorite and monzo-gabbro were derived from partial melting of the enriched lithospheric mantle metasomatized by slab-derived hydrous fluids. Syenites with high alkali (K₂O + Na₂O = 9.4–13.0 wt%) and Sr contents (356–1737 ppm) and low Yb contents (0.94–2.65 ppm) are enriched in Al (Al₂O₃ = 16.4–19.1 wt%), but depleted in MgO (0.09–2.56 w%), Cr (Avg = 7.16 ppm), Co (Avg = 6.85 ppm) and Ni (Avg = 9.79 ppm), showing the geochemical features of adakitic rocks associated with thickened lower crust. Combining zircon ¹⁷⁶Hf/¹⁷⁷Hf ratios of 0.282176 to 0.282359, εHf(t) values of −18.3 to −11.8 and εNd (t) values of −11.1 to −8.2, we conclude that the syenite magma was derived from the mixing of the thickened lower crust and the enriched lithospheric mantle magma. These magma processes were controlled by Paleo-Pacific plate subduction and resulted in the destruction and thinning of the central North China Craton.