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2024, Volume 30,  Issue 5

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2024, 30(5)
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2024, 30(5): 1-2.
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2024, 30(5): 1-1.
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2024, 30(5): 705-706. doi: 10.12090/j.issn.1006-6616.20243004
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Ore Field Structure & Mineralization
Remobilization and transferring of rare earth elements in the formation of regolith-hosted REE deposits
HE Hongping, WANG Heng, LI Xurui, MA Lingya, ZHU Jianxi, YANG Wubin
2024, 30(5): 707-722. doi: 10.12090/j.issn.1006-6616.2024070
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  Objective  Rare earth elements (REEs) are indispensable for high-tech industries, such as clean energy, national defense, and military industries, rendering them strategically critical minerals. In China, regolith-hosted REE deposits constitute one of the most important REE resources, supplying over 90% global heavy rare earth elements (HREE). Understanding the formation of such REE deposits can provide a theoretical basis for their efficient utilization.  Methods  This paper summarizes the recent research results on the two key processes of REE remobilization and transferring and puts forward prospects for future research to deepen the knowledge and understanding of the formation of regolith-hosted REE deposit.  Results  These deposits developed primarily in the weathering crusts of REE-rich granitic rocks, with the REE distribution patterns largely reflecting those of the underlying bedrock. The granitoid weathering crusts are primarily developed by chemical and biological weathering. Clay minerals and Fe–Mn (hydr) oxides, resulting from the weathering of major rock-forming minerals, such as feldspar, mica, and amphibole, serve as the primary hosts for REE ions in weathered crusts. These REE ions originate from the weathering and decomposition of REE-bearing accessory minerals in the bedrock, which exhibit varying degrees of susceptibility to weathering. Furthermore, metabolites such as microbial organic acids can breakdown refractory minerals like monazite and xenotime, facilitating REE remobilization. Simultaneously, microbial action can cause significant REE fractionation, and gram-positive bacteria are significantly more selective for HREE than for LREE. During weathering and leaching processes, REE primarily form REE complex ions within weathering crusts and are then transferred by meteoric water or groundwater. This process is primarily controlled by factors such as pH, secondary mineral formation, and the weathering environment. Notably, in addition to inorganic ligands, such as F− and ${\mathrm{CO}}_3^{2-} $, organic matter can directly interact with REE, acting as organic ligands that aid in REE transfer.  Conclusion  Consequently, the REE remobilization and transferring mechanisms in regolith-hosted REE deposits are predominantly controlled by chemical and biological weathering processes, which result from interactions between inorganic and organic agents. However, the quantitative impact of these processes on the formation of these deposits requires further evaluation.
By-product rare earth elements deposits in China and their resource potential
XIE Yuling, QIN Xuyan, DAI Zuowen, GENG Ziyan
2024, 30(5): 723-746. doi: 10.12090/j.issn.1006-6616.2024081
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  Objective  China is the largest producer of rare earth element (REE) and hosts the largest amount of REE resources. Various types of REE deposits have been reported in China, with alkaline-carbonatite related light REE deposits and ion-adsorption heavy REE deposits being the most important ones. Other REE deposit types include REE placers and deposits with REE by-products. Currently, the development of rare earth resources in China is primarily focused carbonatite-alkaline related light REE deposits and ion-adsorption type heavy REE deposits. REE in placer deposits and other REE by-products have not been effectively utilized.   Methods  Based on existing exploration studies and whole-rock REE geochemistry data analysis, this study provides a brief review of the types and resource potential of deposits with REE by-products in China.   Results  China's by-products REE resource types include marine sedimentary phosphate, coal, bauxite, and magmatic iron-phosphate deposits. These deposits, particularly marine sedimentary phosphate deposits and bauxite, contain enormous potential REE resources. REEs in bauxite are primarily light REE, with some containing high amount of scandium (Sc). In sedimentary phosphate deposits, the proportion of heavy REEs (including yttrium) is high, particularly in the S−P−Al−Sr rich ores that occur as the layers overlying the phosphorite in the Shifang-type phosphate deposits of Sichuan Province. These S−P−Al−Sr rich ores have significantly higher REE content than phosphorite, with medium and heavy REE accounting for over 50%, along with various critical metals, making these ores highly valuable in terms of both resource and economic significance. Furthermore, REE resources in magmatic (iron) phosphate deposits, coal, oil shale, and gold deposits deserve attention.   Conclusions  Owing to the lack of detailed exploration data, the full extent of China's by-products REE resources remains unclear. The comprehensive utilization of resources, as well as the technology for REE recovery and extraction, requires improvement.   Significance  Strengthening the evaluation and comprehensive utilization of China's associated REE resources, particularly by fully utilizing the REE resources associated with phosphate and bauxite deposits, can effectively alleviate the pressure on China's HREE supply. This represents an important measure for implementing China's fundamental national policies on resource conservation and environmental protection.
Exploration and scientific research of the Jiaojia-type gold deposit
ZHOU Mingling, SUN Liangliang, LYU Junyang, WANG Bin, LIU Xiangdong, BAO Zhongyi, ZHANG Qibin, ZHOU Xiaoping, XIE Tianci, WANG Shanshan, LIU Caijie, XU Shaohui, YAN Chunming, ZHANG Peng, ZHANG Liangliang, YANG Zhenliang, FAN Jiameng, ZHAO Chengle, GUO Meili, LI Ruixiang
2024, 30(5): 747-767. doi: 10.12090/j.issn.1006-6616.2024061
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[Objective] Jiaojia-type gold deposit is a new type of gold mine discovered by Shandong geologists in northwestern Jiaodong in the 1960s, and its output is controlled by regional tectonic fracture zones. Pyrite sericitized alteration generally occurred during the ore-forming period, which is characterized by a large scale, distinct alteration zones, concentration of mineralization, simple morphology of the ore body, relatively uniform grade, and simple mineral combinations. The deposit has gone through 12 years of exploration and scientific research, from discovery to establishment. [Methods] This new type of gold deposit has been rapidly promoted since its establishment and has achieved fruitful prospecting results in China. Deep exploration achievements of the Jiaojia-type gold deposit have been coming up in the Jiaodong area since the 21st century. [Results] The accumulated gold resource reserves submitted have been 3617.12 tons by 2020, which has helped the Jiaodong area become the third largest gold cluster in the world, and gold reserves of China have risen to the second rink in the world. Research on the Jiaojia-style gold mine has also made considerable progress, with the age of mineralization accurately limited to 126~120 Ma and formation occurring under a strong regional extension background. The source of mineralization material has multiple origins, with the Archean tholeiite being the initial source rock of gold-bearing minerals. The ore-forming process is divided into four stages, and the “thermo-extension”metallogenic theory and the step metallogenic model are proposed. The metallogenic depth is about 5~10 km, and the post-metallogenic denudation thickness is 5.2±1.2 km, with the deposits well preserved. [Conclusion] The metallogenic prediction study concluded that the total gold resources in the three major metallogenic zones of Sanshandao, Jiaojia, and Zhaoping in the northwestern Jiaozhou area were 7258~10150 tons of metal at a depth of 5000 m, which demonstrates the immense potential of the deeper part of the Jiaojia-type gold deposits for exploration. A set of key exploration techniques was summarized for different exploration stages, from shallow to deep. [Significance] These studies enriched the metallogenic theory of the Jiaojia-type gold deposit, making the metallogenic prediction results highly accurate, reliable, and effective in guiding the gold exploration in the Jiaodong peninsula.
Electrical characteristics and metallogenic prediction of Baishawo rare metal deposit in northeast Hunan Province
LIU Jianxin, CAO Li, GUO Zhenwei, CAO Chuanghua, CHEN Xu
2024, 30(5): 768-780. doi: 10.12090/j.issn.1006-6616.2024060
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  Objective  The aim of this study is to characterize the deep electrical structure of the Baishawo pegmatite-type deposits, explore the spatial distribution of rare metal mineralization models and ore-conferring carriers, and elucidate the relationship between the location of ore veins to provide a basis for prediction in rare metal mineral exploration.   Methods  Through the controlled-source audio-geomagnetic method (CSAMT) and the conjugate gradient method of inverse measurement of three exploration profiles, deep hidden rock (ore) bodies were detected. Then, by combining these results with the information from drill holes and elemental geochemical anomalies, a comprehensive analysis was carried out to reveal the distribution of the hidden dikes and the mineralization characteristics.   Results  The study showed that the concealed pegmatite veins are mainly located in the Lengjiaxi Group, where they are concentrated on the top of the granite body and around tectonic fissures and have burial depths ranging from 50 to 300 m. The geophysical signature of pegmatite vein mineralization is a high-resistance vein-like geologic body intruded from a deep high-resistance body into a shallow low-resistance body.   Conclusion  The determined distribution and burial depth of concealed pegmatite veins, identified potential concealed veins in the study area, and geophysical characteristics of the pegmatite vein mineralization provide a basis for understanding the formation mechanism of fracture zone-constrained pegmatite veins. Significance The research results provide a scientific basis for follow-up exploration of the Baishawo deposit, reveal the formation mechanism of the pegmatite veins, and provide reliable physical exploration and prediction technology and experience useful for rare metal exploration in northeast Hunan and south China.
Energy Resources Geology
Exploration prospects of the whole oil and gas system in the Permian hydrocarbon depressions in the Eastern Junggar Basin
ZHI Dongming, XIE An, YANG Fan, MA Qiang, HE Changsong, GOU Hongguang
2024, 30(5): 781-794. doi: 10.12090/j.issn.1006-6616.2024029
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  Objective  Multiple types of oil reservoirs, including conventional oil, tight oil, and shale oil, have been discovered from the slope area to the depression area in the Jimusaer Depression, demonstrating the characteristics of conventional–unconventional ordered coexistence and complete oil and gas system accumulation.  Methods  Source rocks, sedimentary reservoirs, and reservoir formation were examined to explore the rules of oil and gas accumulation in hydrocarbon-rich depressions in the Eastern Junggar.  Results  High-quality, saline, lacustrine facies source rocks are believed to be developed in the Middle Permian of the Eastern Junggar. The source rocks in the Jinan, Jimusaer, and Shishugou Depressions have large scale and best quality and have reached the mature stage of evolution. The inherited ancient uplifts around the Permian hydrocarbon-rich depression provided long-term material sources, with the development of fan deltas, braided river deltas, and saline lake sediments, forming sandy conglomerates, cloudy sandstones, cloudy mudstones, etc., in an orderly manner and demonstrating the characteristics of grain sequence reservoir formation. Conventional oil and gas, tight oil and gas, and shale oil and gas accumulations, demonstrating a complete type of reservoir formation and complete oil and gas system development pattern, are developed from the edge of the basin to the depression area.  Conclusions  The depressions in the Eastern Junggar Basin show a whole oil and gas system pattern.  Significance   Under the guidance of the entire oil and gas system reservoir formation model, the southern slope of the Shishugou Sag and the Lucaogou Formation of the Jinan Sag were selected as important exploration zones for future exploration in the Eastern Junggar.
Geo-hazards & Engineering Geology
Formation and catastrophic evolution of giant landslides in the alpine canyon area of western China
ZHANG Shishu, HU Xinli, ZHANG Guangcheng, LI Yabo, LIU Xinyu, XU Qingyao, RAN Congyan, ZHAO Xiaoping
2024, 30(5): 795-810. doi: 10.12090/j.issn.1006-6616.2024031
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  Objective  Most hydroelectric projects in western China are located in alpine canyons. The intricate geological engineering conditions in this area have contributed to the widespread distribution of landslide disasters across the reservoir banks of hydroelectric projects.  Methods  Based on the engineering geological characteristics of western alpine canyons, correlations between topography, geological structure, landslide material, slope structure, hydrogeological conditions, and the formation and progression of landslides were analyzed. We also delineated the types and features of landslide development in the western region, as well as the mechanisms governing the evolution of typical landslide disasters.  Results  Results indicate that the landslides were characterized by slopes ranging from 30° to 50°, elevations exceeding 1000 m, and volumes surpassing one million cubic meters. Triassic, Ordovician, and Silurian strata were identified as the principal slippery strata in this area. Rainfall and reservoir impoundment significantly influenced landslide stability, leading to erosion, datum uplift, and range expansion. Water level fluctuations resulted in diminished rock and soil properties along the leading edge of advancing landslides.  Conclusion  The most frequent landslides in the western alpine region included accumulated landslides dominated by traction, thrust, and composite mechanisms and rock landslides dominated by bedding, buckling, anti-dip, and seating mechanisms.   Significance   This study elucidates landslide disaster mechanisms under varying evolutionary and mechanical failure processes, providing significant guidance for the identification, monitoring, early warning, and prevention of landslide disasters in the western region.
Prevention and control of land subsidence and earth fissures in Suzhou–Wuxi–Changzhou region
ZHU Jinqi, GONG Xulong, YU Jun, ZHANG Yun, ZHANG Yan, YE Shujun, WANG Caihui, XU Shugang, WU Jianqiang, WANG Guangya, LIU Mingyao, GU Chunsheng, MIN Wang, GONG Yabing
2024, 30(5): 811-833. doi: 10.12090/j.issn.1006-6616.2024051
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  Objective  The Suzhou–Wuxi–Changzhou region is one of the most severely affected areas by land subsidence, both in China and globally. In the early 1970s, land subsidence occurred and resulted in the formation of ground fissures caused by differential subsidence, thus resulting in significant economic losses. In this century, the rate of ground subsidence has decreased, with some areas experiencing regional ground resilience. The unique developmental history of ground subsidence allows one to comprehensively interpret its evolutionary process and causal mechanisms. This study aims to unravel the life cycle and driving forces of land subsidence in the Suzhou–Wuxi–Changzhou region.   Methods  To achieve this, a multifaceted approach was employed, including long-term and large-scale monitoring of three-dimensional seepage, stress, and strain, complemented by physical experimental models and numerical simulations. An analysis was conducted to synthesize the macro-evolutionary patterns and causal mechanisms of land subsidence and the formation of ground fissures.   Results and Conclusion   The findings indicate that land subsidence in the Suzhou–Wuxi–Changzhou region exhibits distinct characteristics that evolve through five discernible stages: initiation, rapid development, deceleration, stagnation, and rebound. The development of land subsidence is intricately connected to groundwater extraction, with stratum deformation arising predominantly from the compaction and dewatering of aquifers and aquitards due to pumping. During the subsidence phase, primary aquifer sand and contiguous aquitards are identified as the primary contributors to subsidence. By dissecting the causal mechanisms of land subsidence and ground fissures, this study delineates the spatiotemporal evolution of the structural compression and rebound of strata under varying conditions of deep groundwater exploitation, restriction, and prohibition, along with their respective contributions to subsidence. Ground fissures, which act as a secondary geological hazard at certain stages of subsidence, exhibit a spatial distribution and occurrence time that are closely related to groundwater levels, land subsidence, bedrock undulations, and soil-layer structural disparities. The life cycle of ground fissures can be encapsulated by the mechanical processes of compression, tension, shearing, and rebound, which highlights the triggers and critical thresholds for fissure formation due to differential subsidence. An integrated “sky–air–ground” monitoring system that can perform full-section fiber-optic monitoring in geological boreholes and amalgamates diverse technical methods is established to obtain scientific and granular data support for land-subsidence control and prevention. Furthermore, an innovative finite-element coupling interface element method customized for regional and site-specific scales is developed. This method successfully simulates the mechanisms of stratum deformation as well as the genesis and propagation of ground fissures under complex three-dimensional geological conditions, thus facilitating the precise identification and management of subsidence and fissure prone areas.   Significance   This study highlights the government’s land subsidence control measures at various stages, which are characterized by technological innovations such as groundwater extraction restrictions and bans, thus setting a precedent for land subsidence management and groundwater resource stewardship in other provinces and cities across China.
Fundamental Geology & Regional Geology
Petrogenesis and geological significance of the Late Indosinian adakitic granites in the East Kunlun Orogen
WANG Bingzhang, LI Wufu, ZHENG Ying, WANG Chuntao, ZHAO Zhongguo, JIN Tingting, CAO Jinshan, FU Changlei
2024, 30(5): 834-864. doi: 10.12090/j.issn.1006-6616.2024030
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  Objective  The Indosinian collision process of the East Kunlun Orogenic Belt remains a subject of debate. The newly discovered Triassic adakitic granites in the Xiaonanchuan area of East Kunlun provide new geological evidence that constrains the evolution of collisional orogenesis.   Methods  This study conducted petrological, geochemical, zircon U-Pb, and Lu-Hf isotopic analyses of the Moshigou and Bentoushan granitic intrusions in the Xiaonanchuan area to investigate their petrogenesis and tectonic settings. By integrating previous research on magmatism and sedimentation during the late Indosinian period within the East Kunlun Orogenic Belt, a preliminary discussion was conducted on collisional orogensis process.   Results and Conclusion  The Moshigou intrusion consists of granodiorite and monzogranite with zircon U-Pb ages of 209–208 Ma. The Bentoushan intrusion is composed of granodiorite with zircon U-Pb ages of 201–200 Ma. These granitoids have high SiO2 and Al2O3 contents and are rich in sodium. They also have high Sr contents (398×10−6–613×10−6) and Sr/Y ratios (50–97) and are depleted in heavy rare earth elements without Eu anomalies, exhibiting typical geochemical characteristics of adakitic rocks. The Moshigou granitoids have negative whole-rock εNd(t) (−3.60 to −3.34) and variable zircon εHf(t) (−1.3 to +5.9), indicating their derivation from the partial melting of the thickened lower crust. The Bentoushan granitoids have negative whole-rock εNd(t) (−1.65 to −1.55) and positive zircon εHf(t) (+3.4 to +7.3), suggesting their origin from meta-basic rock-dominated thickened lower crust with eclogite residue. Significance These results suggest that they were formed in a post-collisional extension setting. A comprehensive analysis indicates that the East Kunlun Orogenic Belt was in the collision and post-collision stages during the Late Triassic. The post-collision stage can be further divided into two phases of magmatic activity: early and late phases of the Late Triassic.

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