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YANG Shu-sheng, WANG Lu, WANG Yun-xiao, MI Yun-chuan, DONG Tao, HUANG Tai-ping, WANG Feng, SHE Zhong-ming, DUAN Wen-ting
2024,43(5):1073-1085, DOI: 10.20086/j.cnki.yskw.2024.0501
Abstract:
The Yangchang phosphate deposit in the northwest Zhenxiong County is located at the area of Qingba Village in Wanchang Town to Liaoyeba Village in Yanyuan Town (also called Yangchang). The deposit has the characteristics of large reserves of resources, excellent ore quality and concentrated distribution of resources, and is currently the largest concealed monomeric phosphorus-rich deposit in Asia, ranking fifth in the world. The genetic type of the deposit is the shallow marine sedimentary type phosphorite deposit in the Lower Cambrian Meishucun Formation (∈1ms). The ore body is stratified and concealed in the Yangchang anticline. Generally, the ore body develop from east to west, and the mineralization tends to be richer. To date, the Yangchang phosphate deposit has made a major breakthrough in deep mining, revealing 3 layers of phosphorite depositions, and the inferred phosphorus ore resources of grade Ⅰ+Ⅱ+Ⅲ have been discovered in 3 survey areas (Zhujiachang, Fengjiagou and Qingba Village) has a cumulative mineral thickness of 36.77 m and an average P2O5 grade of 22.94%. The potential phosphorite resources estimated as 132.0×108 t, which effectively improves the capacity of phosphorus resources in the country, achieves the deep prospecting breakthrough of strategic minerals in short supply in the country, and has huge potential economic value and social benefits. In this paper, the formation mechanism and enrichment of the early Cambrian Meishucun phosphorus deposit is summarized systematically through the prospecting project results, and an effective deep phosphorite prospecting technology is established, which is helpful to further improve the ore-forming theory of early Cambrian phosphorus deposit, and with important guiding significance for the exploration and development of concealed phosphorus deposits in northeast Yunnan. The discovery of the super large phosphorus deposit in Yangchang has achieved a major breakthrough in deep concealed phosphorus deposit prospecting technology, greatly expanded the amount of phosphorus resources available in Yunnan Province, and laid a solid resource foundation for strengthening the storage and production of important energy and mineral resources, punning the resource economy of Yunnan Province, and building a national important phosphorus chemical industry base of 100 billion. It also provides a strong resource guarantee for the maintenance of energy and resources security of the nation.
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LIU Wen-jie, ZHOU Yan-ling, MI Yun-chuan, NIU Yi-ning, WU Jia-yi, ZHOU Yu-guo, CHEN Jian-bo
2024,43(5):1086-1098, DOI: 10.20086/j.cnki.yskw.2024.0502
Abstract:
The recently discovered Yangchang deposit in Zhenxiong County, Zhaotong City, Yunnan Province is an ultra-large-scaled buried phosphate deposit. Previous research on this deposit mainly focused on the metallogeny, while the study of sedimentary geochemistry and the paleoenvironment is lacked. More importantly, the inorganic (δ13Ccarb) and organic (δ13Corg) carbon isotopes as well as their relationships in the early Cambrian were rarely reported. In this study, three drill cores (ZK001, ZK0701, ZK1512) in Yangchang phosphate deposit were selected for high-resolution investigations of δ13Ccarb and δ13Corg. Both δ13Ccarb and δ13Corg show negative shifts in the top Precambrian Dengying Formation and the bottom of its overlying Zhujiaqing Formation, which is consistent with the global Basal Cambrian Carbon Isotopic Excursion (BACE), likely due to the oxidation of organic carbon reservoir. However, we did not find significant positive shifts in the overlying strata (i.e., Zhujiaqing Carbon Isotopic Excursion, ZHUCE), which may be caused by sedimentary hiatus given that the Yangchang phosphate deposit is mostly intra-clastic phosphorus-rich deposits. Nevertheless, we propose that this phosphate deposit was mainly formed during the Fortunian according to the comparison between the δ13Ccarb in the three drill cores and the composite profile of δ13Ccarb in South China. The comparisons for the δ13Ccarb and δ13Corg values in the drill cores ZK001 and ZK0701, show that the average value of the ΔCcarb-org (difference between δ13Ccarb and δ13Corg) is 28.8‰ and 22.2‰ in the Dengying Formation, and these values change to 31.7‰ and 31.7‰ at the bottom of the Zhujiaqing Formation, and 29.6‰ and 29.8‰, in the middle and upper of the Zhujiaqing Formation, respectively. We propose that the decoupled δ13Ccarb and δ13Corg occurring in the middle of the Zhujiaqing Formation may be caused by the increased primary productivity or buried organic carbon. In summary, the high-resolution paired inorganic and organic carbon isotopes in this work indicate the formation time of Yangchang phosphate deposit and shed light on associated paleoenvironmental changes, which also support the regional stratigraphic correlation.
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MI Yun-chuan, DU Bin, XIA Jian-feng, WANG Feng, ZHOU Qian, HUANG Tai-ping, HU Qing-hua
2024,43(5):1099-1118, DOI: 10.20086/j.cnki.yskw.2024.0503
Abstract:
The Yangchang phosphate deposit is a large-buried shallow marine carbonate stratified phosphorite deposit discovered in the Meishucun Formation (∈1ms) of the Lower Cambrian recently. The understanding of its sedimentary environment and enrichment mechanism is still limited. Representative borehole cores were selected to carry out systematic sedimentary facies cataloguing. By means of sedimentary (microfacies) analysis, mineralogy and mineral chemistry tracing, the characteristics of rock and mineral (assemblage), sedimentary (microfacies) types, sedimentary environment and spatial and temporal distribution of each lithologic section of the Meishucun Formation are analyzed. We also studied the sedimentary environment evolution, the source, migration and enrichment mechanism of phosphorus, and its metallogenic model. The comparative analysis shows that the ore-bearing strata exhibits the nearshore tidal flat facies sedimentary environment with transgression-regressive sequence vertically, 6 microfacies types in 3 subfacies namely supratidic flat, intertidal flat and subtidal flat are identified. Supratidic flat is divided into supratidic flat and supratidic carbonate flat. The intertidal flat is divided into intertidal carbonate flat, intertidal flat and storm current. The subtidal flat developed a low energy subtidal flat. The favorable phosphorus formation environment is the high energy intertidal flat in intertidal flat. Repeated action of tides and waves in the shallow water environment for a long time is conducive to the winnowing, enrichment and reconstruction of phosphorous rich particles, thus forming a phosphorous rock deposit with rich and thick beds in the northwest and poor and thin beds in the southeast of the mining area. To sum up, the ore forming process of the Yangchang phosphate deposit can be divided into three stages, namely: ① initial accumulation and precipitation mineralization stage (phosphorus source carried by upwelling ocean current); ② biochemical deposition and accretion mineralization stage (migration and enrichment driven by microbial decomposition, transformation and compound); ③ winnowing enrichment and re-enrichment mineralization stage (precipitation and enrichment driven by multi-stage wave and tidal action). This new points provides an important basis for prospecting and exploration in the mining area and peripheral areas.
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ZHOU Qian, MI Yun-chuan, ZHAO Yong, HUANG Tai-ping, WANG Jia-sheng, HU Qing-hua, XIA Jian-feng, ZAI Xi
2024,43(5):1119-1138, DOI: 10.20086/j.cnki.yskw.2024.0504
Abstract:
The Cambrian life explosion is closely related to the redox environment of plaeoocean, and the Lower Cambrian phosphorite in the Upper Yangtze Block has recorded a relatively complete information of the Early Cambrian. The Yangchang phosphate deposit in western margin of the Yangtze Block is a super-large phosphate deposit occurring in the Meishucun Formation of the Lower Cambrian, which can reconstruct the paleomarine environment of this period. In this paper, ICP-MS and other techniques were used to analyze the elemental geochemical composition characteristics of the phosphorite and its surrounding rocks and explore the geological environment of the Yangchang phosphate deposit. The results show that the CIA value of phosphorite is 46.40~65.60, with an average of 57.43, indicating that the weathering degree is low, the total amount of rare earth element (ΣREE) in phosphorites in this deposit is relatively low (140.0×l0-6~237.4×l0-6), but yttrium is relatively rich (87.0×l0-6~183.2×l0-6). The North American standardized rare earth distribution pattern is relatively flat, the LREE/HREE is of 4.22~7.50, shows that the diffrernce of light and heavy rare earth elements is not obvious, with obvious Ce negative anomaly (0.22~0.42), Eu anomaly is not obvious with δEu of 0.90~1.21, and U/ Th ratio of 2.55~27.68, which reflect that the phosphorite was affected by a certain influx of hydrothermal fluid during the sedimentary of phosphorites. Combined with the analysis of δCe, V/Cr, Y/Ho, Sr/Cu and other elements, it is indicate that from the bottom of Dengying Formation in the Sinian Period, to the phosphate-bearing layer Cambrian Meishucun Formation, to the upper cover Niutitang Formation, the ancient ocean redox environment changes from the relative reduction environment at the bottom to the oxidation environment upward until the top becomes the relative reduction environment. The paleoclimatic environment is cold and dry-warm and moist alternatively appear. The salinity of ancient seawater is the evolution process of salt water to semi-salt water to salt water to fresh water. The above analysis shows that the phosphorite deposit in a relatively oxidized saline water and arid climatic environment, and the climatic environment is relatively arid during sedimentation, and may be affected by the influx of hydrothermal fluid.
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LI Zi-wei, XIE Yu-ling, QIN Xu-yan, DAI Zuo-wen, QU Yun-wei, WEI Yu-rong
2024,43(5):1139-1156, DOI: 10.20086/j.cnki.yskw.2024.0505
Abstract:
Marine sedimentary phosphorites usually contain high rare earth elements (REEs) content, especially the heavy REEs (HREEs), which account for over 30% of the total REEs. The phosphorites may became another important source for HREEs in the future. Phosphorite deposits are widely distributed in China and most of them are found in Yunnan, Guizhou, Sichuan Provinces, etc. High REEs abundances are confirmed in the Zhijin phosphorite deposit in Guizhou Province and with total REEs resource over 3 Mt. The collophanite and apatite are the main host phase for both REEs and P, and the collophanite has complex chemical composition. There are still controversies for the mineral and chemical composition of collophanite. Based on detailed petrological, mineralogical, SEM/EDS, XRD, FIB-TEM and LA-ICP-MS results of phosphorites in Zhijin deposit, this paper discuss the mineral composition of phosphorites and the origin of the complex chemical composition of collophanite. The results show that the most phosphorites in the deposit show the pelletal texture,which is composed of phosphorous pellets and carbonate cement. The mineral composition of the phosphorous pellet is very complex, including mainly fluorapatite and dolomite, and with minor quartz, dolomite, pyrite (some oxidized into limonite), muscovite, solid bitumen and barite. The mineral composition of the cement is mainly dolomite, with minor quartz, pyrite, barite, and trace amounts of zircon, rutile, and liebigite (possibly formed by oxidation of other uranium minerals). The FIB-TEM results show that the cryptocrystalline part of the outer layer of phosphorus pellet is composed of nanoscale mineral aggregates including mainly nanoscale fluorapatite, and small amount of nanoscale dolomite, pyrite and organic matter. The mineral composition of collophanite is similar to that of phosphorus pellet. The discovery of nanoscale fluorapatite, dolomite, pyrite, and organic matter in phosphorite provides reliable evidence for explaining the chemical complexity of collophanite. The discovery of solid bitumen and liebigite in phosphorites, as well as high REEs content in organic matter, also provides new evidence for an alternative occurrence of U and REEs in phosphorites.
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DONG Tao, DU Bin, WANG Feng, YANG Shu-sheng, HUANG Tai-ping, MI Yun-chuan, DUAN Zhao-yan, ZHOU Qian
2024,43(5):1157-1174, DOI: 10.20086/j.cnki.yskw.2024.0506
Abstract:
Phosphate ore is an important strategic mineral resource, and its guarantee degree is related to national resources, energy and food security. Phosphate ore resources in Yunnan Province occupy an important position in the country, with the characteristics of concentrated distribution, simple deposit types, large and medium-sized deposit are abundant, good ore quality and easy mining. With the major breakthrough in mineral prospecting of the Yangchang phosphate deposit in Zhenxiong area in recent years, phosphate ore in Yunnan Province has become one of the hot spots in mineral deposit research. This paper systematically sorted out the types and resource reserves of phosphate ore deposits in Yunnan Province, selected typical deposits of different deposit types for detailed dissections, systematically summarized the metallogenic laws from the aspects of spatial and temporal distribution charac- teristics, ore-bearing rock series characteristics, etc., improved the sedimentary phosphate ore mineralization model in Yunnan Province on the basis of the Yangchang phosphate deposit research, and combined with the results of potential evaluation, delineated 8 key prospecting potential areas. It provides the direction for phosphate rock prospecting in Yunnan Province in the future.
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DAI Zuo-wen, XIE Yu-ling, XU Hang-hang, QU Yun-wei, QIN Xu-yan
2024,43(5):1175-1187, DOI: 10.20086/j.cnki.yskw.2024.0507
Abstract:
Shifang-type phosphorite deposit is an important type of phosphorite deposit in China, which is characterized by large scale, high phosphorus grade, and enrichment in rare earth elements (REEs). However, the enrichment regularity and resource potential of REEs in this type of deposit are not studied in detail. This study takes the typical Shifang-type phosphorite deposit in Mianzhu, Sichuan Province, as the research object. Based on field geological investigation, the distribution and enrichment characteristics of REEs in the deposit are explored through microscopic petrographic observation, scanning electron microscope/energy disperse spectroscopy imaging, and whole-rock geochemical analysis for the phosphorus-bearing layers (phosphorite layer, dark grey and maroon S-P-Al-Sr-rich layers) and their roof and floor rocks (dolomite) in the mining area. In turn, the potential resource of REEs in Shifang-type phosphorite deposits in Sichuan Province is discussed. The results showed that the total REEs (La-Lu+Y) contents in the roof and floor dolomites of the phosphorus-bearing layers are very low (13.6×10-6 on average), the REEs contents in the phosphorite are medium (280.0×10-6 on average), while the REEs contents in the S-P-Al-Sr-rich layers are extremely high (2 053.9×10-6 on average), especially the maroon S-P-Al-Sr-rich layer (up to 3 257.2×10-6). Together with previously published REEs content data from adjacent phosphorite deposit, the average REEs content in S-P-Al-Sr-rich layers in the Shifang-type phosphorite deposits in Sichuan Province is 2 259.4×10-6 with the maximum up to 3 286.8×10-6, of which the average concentration of medium and heavy REEs (Sm~Lu+Y) is 1 276.9×10-6 with the maximum up to 2 213.0×10-6, accounting for 55.1% of the total REEs. REEs contents in the Shifang-type phosphorite deposits in Sichuan Province are much higher than those in ion adsorption-type REEs deposits in southern China, Zhijin REEs-bearing phosphorite deposit, and REEs-rich deep-sea sediments. According to preliminary estimates, the total potential REEs resources associated with the Shifang-type phosphorite deposits in Sichuan Province can reach 252 000 tons, 156 000 tons of which are medium and heavy REEs. The potential medium and heavy REEs resources in the S-P-Al-Sr-rich layer alone can reach 96 000 tons. Therefore, the Shifang-type phosphorite deposits in Sichuan Province have important economic and social value, and the development and utilization of REEs in these deposits are expected to alleviate the current shortage of medium and heavy REEs in China.
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HUANG Tai-ping, XIA Jian-feng, MI Yun-chuan, HU Qing-hua, ZHAO Yong, ZHOU Qian
2024,43(5):1188-1198, DOI: 10.20086/j.cnki.yskw.2024.0508
Abstract:
The Yangchang phosphate deposit in Zhenxiong County, Yunnan Province is a super large sedimentary phosphate deposit evaluated in recent years in the Early Cambrian period. It is characterized by large resource reserves, excellent ore quality, and concentrated resource distribution, and is currently the largest hidden single rich phosphate deposit in Asia. This article mainly uses different analysis methods to conduct systematic mineralogical research on the chemical composition, mineral composition, embedding characteristics, embedding particle size and intergrowth relationship, dissociation degree of the phosphate ore in the deposit. The grinding fineness and ore sorting process methods are also preliminarily explored. Our results show that the samples in this study are high-grade silicon calcium carbonate phosphate ore, with a P2O5 content of 29.34%. The main P-bearing mineral in the ore is fluorapatite which commonly distribute as hidden crystal microcrystal aggregates (commonly known as collophane). The main gangue minerals are quartz, calcite, dolomite, and a small amount of pyrite. The ore is characterized by low magnesium and low silicon, and can be processed using the direct-reverse flotation method. The ore has fine particle size and complex interrelationships, making it difficult to dissociate. During the beneficiation, fine grinding is required to increase the degree of monomer dissociation, but the impact of mechanical entrainment and mud formation caused by excessive grinding on flotation indicators should be paid special attention. The ore has reached the phosphate concentrate index and can be directly processed and utilized. If beneficiation is required, it is recommended to focus on studying the grinding process and exploring joint beneficiation methods to achieve the desired beneficiation effect.
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LEI Meng-dan, ZHONG Ri-chen, CUI Hao, WANG Zhao-yi, CHEN Huan, LI Yan-xia, YU Chang, DENG Yi, LING Yi-fan, LI Mo-jie, LI Zi-meng, CHEN Ang-kuai
2024,43(5):1199-1217, DOI: 10.20086/j.cnki.yskw.2024.0509
Abstract:
Phosphorite deposit is a kind of marine sedimentary phosphate deposit with the francolite as the main ore mineral. These deposits were formed in the upwelling areas during six historical periods after Paleoproterozoic, and are generally related to the biological activity and the intensity of continental weathering. The formation of phosphorite deposits is controlled by marine transgressions and regressions, microbial activities and physical and chemical conditions of sediment pore water. The key factors for the formation of phosphorite deposits with high rare earth elements (REEs) content are low sedimentation rate and periodic submarine storms. Some phosphorite deposits are rich in medium and heavy REEs, which are potential important REE resources. The main host mineral of REEs in phosphorite is francolite. The REEs in francolite are mainly derived from seawater in sedimentary period and sediment pore water in early diagenetic period, and are incorporated into francolite via adsorption or lattice substitution. REEs can be adsorbed on the surface of marine particles by forming as REEs-carbonate complex and released by the marine particles decomposing that is induced by the change of redox conditions in the sediment pore water. Through the previous research, it is found that different marine particles preferentially adsorb different REEs, which results in the formation of different REEs patterns of pore water and then affects the patterns of francolite in phosphorite deposits. The enrichment of REEs in francolite is equal for light, medium and heavy REEs and different REEs patterns in francolite are derived from contrasting fluid sources. In general, seawater can produce a HREEs-enriched pattern, and pore water might yield a MREEs-bulge pattern (enrichment of medium REEs). As the phosphorite deposits with significant REEs contents are characterized by MREEs-bulge patterns that are consistent with Fe-Mn (oxyhydr)oxides input by the submarine hydrothermal process and the pore water in the early diagenetic process, which may indicates the influence of the submarine hydrothermal activities and the early diagenetic process on the REEs enrichment mechanism of phosphorite deposits. In this paper, the metallogenic process of phosphorite deposits is summarized from the characteristics, spatiotemporal distribution and metallogenic control factors of phosphorite deposits; the enrichment behavior and differentiation behavior of REEs in the process of phosphorite mineralization are analyzed from the content and anomaly of REEs in phosphorite deposits; and the possible enrichment mechanism of REEs in phosphorite rocks with abnormal enrichment of REEs is revealed. The study of metallogenic process and REEs enrichment mechanism of phosphorite deposits is of great significance for the prospecting and exploitation of phosphorite deposits that are highly enriched in REEs.
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CHENG Tian-she, YANG Wen-jing, ZHANG Xue-bin, TENG Chao, YANG Xin-jie, CHEN Xi-qing, XIAO Deng, WU Rong-ze, ZHOU Chang-hong
2024,43(5):1218-1234, DOI: 10.20086/j.cnki.yskw.2024.0510
Abstract:
The Aruhan granodiorite intrusion in Xiwuqi, Inner Mongolia, is exposed along the central and eastern parts of the Hegenshan suture zone. LA-ICP-MS zircon U-Pb dating shows that the ages of the granodiorite are ranging from 332±3 to 327 ±1 Ma, suggesting emplacement during the Early Carboniferous. The Aruhan granodiorite is characterized by high contents of SiO2 (65.20% to 68.27%), Al2O3 (15.61% to 17.35%), Sr (472 ×10-6 to 552×10-6) and low contents of MgO (1.16% to 1.61%), Yb (0.86×10-6 to 1.13×10-6), Y (7.29×10-6 to 11.42×10-6, with Na2O/K2O and Sr/Y ratios ranging from 2.56 to 4.35 and 43.45 to 75.68, respectively. The total REE is low (44.73×10-6 to 88.11×10-6), the fractionation of REE is significant , and the anomaly of Eu (δEu=0.79 to 1.07) is not obvious. The geochemical characteristics of the whole-rock indicate that the Aruhan granodiorite belongs to typical high-SiO2 island arc adakites (O-type) series, formed in an environment of active continental marginal arc. The source of the maga might be the product of partial melting of subducting oceanic crust with oceanic sediments, which reacts with overlying mantle peridotite. Crystallization differentiation and contamination by crustal materials might occurre during its emplacement. This discovery may support the fact that the central and eastern parts of the Hegenshan Ocean was not yet closed during the Early Carboniferous. Combined with the regional research, we preliminarily believe that the Hegenshan Ocean may have undergone bidirectional subduction and abatement during the Early Carboniferous, which is different from the previous view that the Hegenshan Ocean underwent unidirectional subduction and abatement northward only.
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SUN Jia-jing, XIE Yu-ling, YU Chao, QU Yun-wei, XIA Jia-ming
2024,43(5):1235-1250, DOI: 10.20086/j.cnki.yskw.2024.0511
Abstract:
The Proterozoic Eon is a critical period of the Earth’s evolution, and the study of its rock records in this period is important for understanding the Earth’s evolution in the Precambrian. The correct interpretation of rock genesis is the basis of the study of rock geotectonics and the premise of revealing the change of earth environment based on rock records. A set of silicon-rich layered rocks generally developed at the bottom of the Changcheng System in the North China Craton, which is considered to be a set of marine quartz sandstones and siliceous rocks formed by shallow metamorphism in rift valley deposition. This paper focuses on the silica-rich layered rocks of Changzhougou Formation at the bottom of the Great Wall System exposed in Huyugou, Changping, Beijing. Through detailed field geological observations, petrological and mineral analysis of typical samples, SEM/EDS (Scanning Electron Microscopy/X-ray Spectroscopy), CL (Cathodoluminescence) imaging, in-situ LA-ICP-MS (Laser Ablation-inductively Coupled Plasma Mass Spectrometry) analysis of quartz, and petrological, micro-thermometry, muffle furnace heating-quenching experiments, and SEM/EDS, EPMA (Electron Probe Microanalysis), LRM (Laser Raman Microscopy) analysis of melt inclusions in quartz, a new understanding of the volcanic origin of the silicon-rich stratified rocks at the bottom of the Great Wall System has been proposed. The results indicate that the silicon-rich stratified rocks at the bottom of the Great Wall System include two types: clastic structures (previously defined as quartz "sandstone") and mosaic structures (previously defined as "quartzite"). The main mineral compositions are quartz and K-feldspar, with minor amounts of zircon, rutile, and other minerals. In the clastic structure rocks, quartz and K-feldspar clasts exhibit angular to subangular shapes, and K-feldspar shows no signs of clay alteration at the edges. The CL of quartz in the two types of rocks mostly shows blue-purple luminous characteristics. Additionally, the formation temperature estimated by the quartz titanium saturation thermometer is concentrated between 550~650℃, indicating characteristics of high-temperature quartz. Both types of rocks contain iron-titanium-rich two-phase melt inclusions in quartz and K-feldspar. Micro-thermometry results of the melt inclusions show that during the heating process to 1 000℃, the composition of the two-phase immiscible melt inclusions changes continuously, when the temperature reaches 1 000℃, with a color reversal occurring at about 1 050℃, and critical homogenization around 1 350℃. Muffle furnace heating-quenching experiments also confirmed that the two-phase melt inclusions in the samples quenched after heating to 1 350℃ became homogeneous. SEM/EDS and EPMA results indicate that the main components of the melt inclusions are iron and titanium oxides, with the dark part being relatively rich in iron and the light part being relatively rich in titanium, and the Fe/Ti ratio of the two phases of the melt inclusions varies greatly. LRM analysis results show that both phases of the melt inclusions are amorphous. Integrating the structural characteristics of the rocks, the CL luminescence characteristics of quartz, the formation temperature estimation of quartz, and the micro-thermometry results of the melt inclusions in quartz, it is believed that the siliceous strata at bottom of the Changcheng System should be siliceous volcanic rocks and volcaniclastic rocks. This indicates that there was a large-scale siliceous volcanic activity in the North China Craton during the Paleoproterozoic, which is related to the rifting of the Columbia Supercontinent. It provides new evidence for the geological evolution of the North China Craton in the Proterozoic. The discovery of iron-titanium-rich melt inclusions in quartz also offers new perspectives on the formation of Precambrian magmatic iron and titanium deposits, particularly the enrichment mechanism of iron and titanium during the magmatic process.
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WU Jian-liang, LIAO Zhi-hua, BAI Yun, WANG Bo, QIN Yu-long, LIU Wen, XU Yun-feng, ZHANG Tong, JING Yang, XIONG Chang-li
2024,43(5):1251-1267, DOI: 10.20086/j.cnki.yskw.2024.0512
Abstract:
The Mesozoic and Cenozoic tectonic magmatic activity in the Lhasa block has always been one of the research hotspots in the basic geology of the Qinghai-Xizang Plateau. There are many Cenozoic, especially Miocene magmatic rocks developed in the western part of the Lhasa block. This article takes the newly discovered Miocene granite in the Anglonggangri area of the western Lhasa block as the research object, and explores its rock types, rock genesis, and tectonic background. The Miocene granites in the Anglonggangri area are composed of fine-grained muscovite monzonitic granite and medium-fine-grained monzonitic granite, with a small amount of dark inclusions developed internally. The zircon U-Pb age of fine-grained muscovite monzonitic granite is 9.95±0.14 Ma, and the zircon U-Pb age of medium-fine-grained monzonitic granite is 10.68±0.2 Ma, both from the Miocene. Both of them have the characteristics of high silicon (SiO2=72.35%~74.74%), rich potassium (K2O/Na2O=1.15~1.45, all greater than 1), high aluminum (Al2O3=14. 35%~14.83%), and weak peraluminum peraluminum (A/CNK=1.08~1.14). The number of CIPW corundum molecules is greater than 1%. The differentiation of light and heavy rare earth elements is very obvious, with a moderate negative Eu anomaly, enriched in large ion lithophile elements such as Rb, Th, K, and depleted in high field strength elements such as Nb, relatively enriched in high field strength elements such as Hf and Zr, Sr, Ba, P, Ti, etc. These characteristics indicate that it is a high potassium calcium alkaline series of peraluminous S-type granite. Both of them have relatively low Sr, high Sr/Y, La/Yb ratios, and extremely low Y and Yb contents. The granite in the research area originated from a thickened lower crustal environment and underwent a certain degree of magma mixing. Based on the comprehensive regional research results, the formation of Miocene granites in the Anglonggangri area may be related to the northward subduction of the Indian plate into the north Lhasa block, where plate tearing occurred and high-temperature asthenosphere material flowed through the plate fragments, causing partial melting of the lower crust.
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GUO Qiang, XIAO Jing, LIU Nian, WANG Qiang-qiang, XU Qiang, WU Yong, YAN Zhang-lei, LIU Meng-kui, DING Tong
2024,43(5):1268-1280, DOI: 10.20086/j.cnki.yskw.2024.0513
Abstract:
In recent years, the exploration of sandstone-type uranium deposits in the northern part of China has made breakthroughs in the Mesozoic and Cenozoic red-colored sedimentary formations. However, there is a great controversy about the mechanism of uranium mineralization in red beds, which has become a hot topic of current research. A large amount of uranium mineralization outcrop information is developed in the Neogene red layer in the Kuqa Depression. Carrying out relevant research is very helpful in analyzing the uranium enrichment mechanism in the red variegated layer. Through systematic sedimentology, petrology and mineralogy, the uranium mineralization spots in the red variegated layer of the Jidike Formation were dissected, and a relatively special type of uranium mineralization was discovered: the mineralized layer was located in a lacustrine sedimentary environment under an arid background. It is produced in a large set of red mudstone in the shape of a thin layer of lens. The mineralization lithology is gray-green marl and develops a large number of reddened siliceous masses. The mineralization has layer-controlled characteristics and is closely related to the siliceous masses. The siliceous mass has a combination of reddish microcrystalline quartz, fluorite, uranite, calcite and a small amount of natural arsenic, chalcopyrite and barite intergrowth minerals. The siliceous mass is very similar to the granite-type siliceous vein uranium mineralization in South China, showing the characteristics of deep hydrothermal origin. It is comprehensively judged that this mineralized layer has dual effects of sedimentation and hydrothermal fluid, and is a special hot water deposition type uranium mineralization. This type of uranium mineralization discovery provides direct and strong evidence that deep hydrothermal fluids could carry uranium into sedimentary basins to undergo uranium mineralization, and improve the theory of sedimentary uranium mineralization in continental basins.
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LIAN Tao, SUN Li, WANG Fang, LIU Fu-lai, DENG Wen-ting
2024,43(5):1281-1301, DOI: 10.20086/j.cnki.yskw.2024.0514
Abstract:
In this study, the whole-rock geochemistry and zircon U-Pb ages are reported for the meta-basic rocks of the Li’eryu Formation of the South Liaohe Group from the cobalt exploration area in Kuandian. These data provide a significant insight into the tectonic background, as well as the source of cobalt. Geochemical features of the meta-basic rocks in boreholes show that they are orthorhombic amphibolite, and have similar rare-earth elements (REEs) patterns, with slightly negative Eu anomalies. REEs and trace elements compositions have affinity to those of E-MORB. Based on the mineral compositional analyses and p-t estimates using conventional geothermobarometers, the clinopyroxene-bearing amphibolite (ZK2-1) records p-t conditions of p=0.82~1.00 GPa and t= 712~751℃, which probably constrained the peak high amphibolites-facies stage. The metamorphic p-t conditions of (clinopyroxene-bearing) amphibolite (ZK1-1 and ZK3-1) are p= 0.42~0.81 GPa, t= 688~759℃ and p=0.59~0.85 GPa, t=703~739℃, respectively, which represent the conditions of the retrograde stage. The metamorphic zircon from the meta-basic rocks yield the SHRIMP U-Pb ages of 1 857~1 850 Ma. The integrated study of geochemistry and zircon U-Pb dating reveals that their protoliths of the meta-basic rocks are mid-Paleoproterozoic tholeiitic basalt and formed in an extended tectonic environment. Their protoliths underwent significant crustal assimilation imply that the scale of the mid-Paleoproterozoic oceanic basin may be limited. By comparing the geochemical characteristics of meta-basic rocks in the North and South Liaohe groups, it is believed that meta-basic rocks in the Kuandian area are not the main source of cobalt mineralization. The material sources of cobalt mineralization still needs further research.
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2024,43(5):1302-1312, DOI: 10.20086/j.cnki.yskw.2024.0515
Abstract:
The Maevatanana gold deposit in Madagascar is a quartz-vein type gold deposit hosted in a greenstone belt, and its genesis is highly controversial. This article conducts elemental geochemical analysis and dating of the Maevatanana gold deposit, and explores the mineralization age and process of the Maevatanana gold deposit in Madagascar. The gold content of gneiss is 1.11×10-9~80.8 ×10-9, with an average of 19.55×10-9; pyrite is the main gold-bearing mineral in gneiss, with a Re-Os isotopic age of 752±27 Ma. The gold grade of the gold-bearing quartz vein is 26.44×10-6~132.22×10-6, and pyrite is the main gold-bearing mineral. The Re-Os isotopic age of pyrite in the gold-bearing quartz vein is 535±26 Ma, representing the mineralization age of the Maevatanana gold deposit. The Re-Os isotope isochron ages of two phases of pyrite correspond to the time of two collisions during the Pan Afri- can orogeny event. The gold content in gneiss is much higher than the average grade of the crust, and encapsulated gold can be seen in pyrite. The Re-Os isotopic age of pyrite indicates intrusion of granite and gabbro at 752±27 Ma. The Madagascar terrane underwent extensive metamorphism from greenschist to amphibolite facies, and gold in volcanic sedimentary rocks was activated, migrated, and enriched to form a source layer. The mineralization age of the gold-bearing quartz vein is 535 ± 26 Ma, which is consistent with the age of the Cambrian post collisional A-type granite in central northern Madagascar. Field evidence and geochemical data indicate a close genetic relationship between the Maevatanana gold deposit and the Cambrian post collisional A-type granite. During the process of magma ascending, the high-Si melts entered the magma and gradually evolved into ore-forming fluids, which enter the host structures and enrich mineralization.
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SUN Guo-quan, FAN Hong-hai, GAO Yong-bao, PANG Ya-qing, GAO Fei, XUE Chun-ji, FAN Bao-cheng
2024,43(5):1313-1327, DOI: 10.20086/j.cnki.yskw.2024.0516
Abstract:
Chloritization is a typical middle-low temperature hydrothermal alteration type of early ore-forming stage in Shulouqiu deposit of Changjiang rock mass in southern Zhuguang. In this paper, the chlorite in the horizontal alteration zone around the ore body are studied comprehensively by optical microscopy, electron probe and scanning electron microscopy. Based on the lithological characteristics and genesis of chlorite, they are divided into five types: fissure filling chlorite, biotite altered chlorite, feldspar altered chlorite, dolomite altered chlorite and spherical chlorite. The five types of chlorite are all trioctahedral iron-rich chlorite with the same structure type, belonging to three species: vermicular chlorite, ferromagnesian chlorite and uraninite chlorite. Then, the five types of chlorite may have formed in the same period of fluid action in the early ore-forming period, with the formation temperature between 219~282℃ and log fO2 between -47.74~-43.69. Combined with previous research results in the region, the early ore-forming fluid may be a crust-mantle mixed fluid dominated by mantle-derived materials, with strong reducibility. Its formation is related to the intrusion of regional basic veins, which provides a reducing field for the mineralization system, resulting in the reduction and precipitation of U6+ in the ore-forming fluid.
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YUAN Xiao, CHEN Cui-hua, XIE Wei, YANG Shan-tao, LAI Xiang, YANG Kui, CHEN Xiao-jie, CAI Yun-hua
2024,43(5):1328-1338, DOI: 10.20086/j.cnki.yskw.2024.0517
Abstract:
The Lijiagou pegmatite-type lithium spodumene deposit is one of the typical deposits in the Ke’eryin ore field, located in the central part of the Songpan-Ganzi fold belt in Sichuan Province, China. Through recent exploration and assessment, the Lijiagou deposit has been identified as a super-large spodumene deposit, drawing significant attention from domestic and international scholars. The mineral processing characteristics of the Lijiagou deposit vary with elevation, necessitating an accurate evaluation of the industrial value of the ore. Based on detailed microscopic and hand specimen observations, this study employs various methods and techniques, including X-ray powder diffraction (XRD), electron probe microanalysis (EPMA), laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), chemical element analysis, chemical phase analysis, and the mineral liberation analyzer system (MLA). These methods and techniques are used to determine the composition of the ore, identify the types and occurrence states of beneficial and harmful elements, and clarify the ore’s processing properties. The results will provide theoretical and technical support for the comprehensive utilization of rare metal resources in the region. The average grade of lithium ore is 0.94%, with approximately 84.7% of Li derived from spodumene. The average grade of Rb2O is 0.13%, meeting the industrial-grade requirements for comprehensive recovery of associated elements. The spodumene exhibits a wide range of grain sizes and is highly heterogeneous, requiring multiple stages of grinding. Based on the liberation characteristics, it is recommended to grind the material to -0.075 mm before entering the final flotation process.
Volume 43,2024 Issue 5
磷矿成矿作用及找矿方向
专题研究
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LI Ming-ze, QIN Yu-long, LI Zheng, XU Yun-feng, WU Wen-hui, LIU Wei, YE Ya-kang, ZHOU Xiong
2018,37(3):366-378, DOI:
Abstract:
This paper discusses the petrogenesis of the two-mica granite and its genetic relationship with pegmatite in Jiajika area, west Sichuan Province, by detailed field investigation and laboratory analysis. The whole rock analytical results show that SiO2 content of two-mica granite is 73.93%~75.06%, and total alkali is 7.90%~8.36% with high concentration of K, suggesting high-K calc-alkaline series; the content of Al2O3 is 14.24%~14.77%, and A/CNK=1.14~1.24, implying strong peraluminous S type granite; ΣREE=31.18×10-6~41.67×10-6,LREE/HREE=4.15~6.41,δEu=0.46~0.70, and CaO/Na2O=0.07~0.12(<0.3),indicating that its source might have been pelite with rare content of psammite, and high ratio of Al2O3/TiO2 (133.1~279.8) implies that it is high-pressure-low-temperature post-collision granite. The SiO2 content of the granite pegmatite is 72.59%~80.91%, the total alkali is 5.26%~10.60%, Al2O3 is 11.79%~17.64%, σ=0.74~3.80; A/CNK=0.98~2.38; ΣREE=4.03×10-6~8.29×10-6, LREE/HREE=2.61~10.40, and δEu=0.18~0.68. There are considerable differences between two-mica granite and granite pegmatite in the aspect of the content of major and trace elements. And there is close genetic relationship between granite and pegmatite in the area. Magma immiscibility might be the key factor for the formation of (ore-bearing) granite pegmatite. The pegmatite melt riched in volatile components might be separated during the upwelling of granite magma and metasomatized minerals in wall rock to further concentrate rare metal elements during its migration. The difference between two-mica granite and pegmatite might cause the apparent differences in REEs and elements such as Th, Sr, Ti, Y, Rb and Nb. The different characteristics of pathways and environments that the pegmatite melt passed and emplaced might have resulted in element concentration variance in different sites. In comparison with two-mica granite, there existed a certain degree of jumping characteristic during the formation and evolution of the pegmatite in Jiajika area.
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GAN Yuan-lu, WANG Chao-wen, LEI Xin-rong, LI Zhuo-yang, WANG Hui-ning, ZHANG Yun-yun, LI Yi-long
2015,34(3):418-426, DOI:
Abstract:
Guilin Chicken Blood Red Jasper (CBRJ) is a kind of quartz jasper. It is characterized by bright red to black colors and high hardness. However, few researches have been focused on the field occurrence, geological background, rock structure and genesis of its color. Field surveys indicate that the Guilin CBRJ is hosted in low-grade metamorphic sandstones which experienced vapor-water hydrothermal metamorphism and iron oxide dissemination. It occurs in the Sanmenjie Formation of Neoproterozoic Danzhou Group in Longsheng area in the north of Guangxi. Tectonically, the ore deposit of Guilin CBRJ is located at the juncture of Yangtze and Cathaysian plates, which has undergone a complex geological process. Its formation was related to multi-phase tectono-magmatic activities from Neoproterozoic to Triassic. Detailed analyses of mineralogy, micro-texture and geochemical composition of Guilin CBRJ were carried out by polarizing microscope, X-ray diffraction, and electronic microprobe. The results indicate that the CBRJ is mainly composed of quartz and hematite, with dolomites in some samples. Quartz grains exhibit two types of allotriomorphic equigranular texture and idiomorphic porphyroblastic texture. The latter one, in which distinct enlargement texture can be observed, reveals a metasomatic metamorphism phase. Hematite occurs in three types: ① single crystal existent between or inside the quartz particles, ② dusty crystals wrapped in the quartz particles, and ③ disseminated crystals filled between the quartz particles. The Fe3+ in the hematite should be responsible for the color of the CBRJ. Electron microprobe analysis shows that the hematites of single crystal and disseminated crystals have 78.9%~85.6% iron oxides, but the dusty crystal is too small to be analyzed. In combination with the different generations of quartz and hematite, the authors have reached the conclusion that the formation of different types of these minerals in the Guilin CBRJ was consistent with the regionally geological evolution in this area.
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ZHANG Li-cheng, WANG Yi-tian, CHEN Xue-feng, MA Shi-qing, WANG Zhi-hua, YU Chang-fa
2013,32(4):431-449, DOI:
Abstract:
The Hongyuntan iron deposit is hosted in pyroclastic rocks of the Lower Carboniferous Yamansu Formation. The ore bodies occur as layers, stratoid bodies or lenses. The principal ore mineral is magnetite, together with minor maghemite, specularite, pyrite and trace chalcopyrite. The gangue minerals include garnet, diopside, actinolite, chlorite, tremolite, epidote, biotite, albite and quartz. The ore structures are mainly of massive and disseminated forms, with occasional banded or veined forms. The ore textures are of subhedral-anhedral granular and metasomatic types. The wall rock alteration shows symmetrical zoning, and the alteration colors change from dark to light from ore bodies outwards. On the basis of observed mineral assemblages and ore fabrics, two periods of ore deposition were recognized, i.e., skarn period and hydrothermal ore-forming period, which could be further subdivided into four metallogenic stages, namely skarn stage, retrograde alteration stage (main ore-forming stage), early hydrothermal stage and quartz-sulfide stage. Electron microprobe analyses show that the end member of garnet is mainly andradite-grossularite. The composition of pyroxene is mainly diopside-asteroite. The amphiboles is composed mainly of actinolite and tremolite with minor magnesiohornblende. The composition of these skarn minerals suggests that skarn in the Hongyuntan iron deposit is calcic skarn, belonging to metasomatic skarn. The characteristics of main and trace elements suggest that the formation of magnetite was closely related to the skarn. In combination with geological characteristics, the authors suggest that the skarn might have resulted from interaction between Ca-rich pyroclastic and Fe-rich magmatic hydrothermal fluid which was transported along the fault system. The formation of magnetite was hence related to the regressive metamorphism of the skarn.
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2009,28(5):495-500, DOI:
Abstract:
This paper has mainly recommended a mineral abbreviation list (see Table 2 and Table 3). Table 2, which contains 243 minerals, was compiled by IUGS Subcommittee on the Systematic of Metamorphic Rocks (SCMR) in 2007. The author selected other 29 minerals and, on such a basis, formulated Table 3. Thus, the total mineral abbreviations come to 272. It is hoped that they can be popularized in future and become more and more perfect through utilization, so as to provide a basis for ultimate standardization and unification.
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Gan Guoliang Yichang Institute of Geology, Mineral Resources, Chinese Academy of Geological Sciences Department of Grologicol, Atmospheric Sciences, lows State Univeraity, Ames, IAS0011, U.S.A
1993,12(2):144-181, DOI:
Abstract:
This paper presents partition coefficients of 69 chemical elements (Li, Rb,Cs, K, Na, Ca, Ba, Sr, Mn, Fe, Mg, Cu, Pb, Zn, Co, Ni, Be, La, Ce, Nd,Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y, Sc, Cr, In, Ga, Al, B,Cd, Sb, Bi, U, Th, Zr, Hf, Si, Ti, Ge, Sn, Mo, Nb, Ta, W, V, P, F, Cl,S, N, O, C, As, Pu, Re, Os, He, Ne, Ar, Kr and Xe) and the univalent radical (OH) in 28 minerals (olivine, clinopyroxene, orthopyroxene, amphibole,biotite, Phlogopite, plagiocla-se, K--feldspar, quartz, magnetite, ilmenite, garnet,zircon, apatite, allanite, topaz, sphene, cordierite, hauyne, leucite, nepheline,whit-lockite, brookite, petovskite, melilite, armalcolite, spinel and rutile) from 8 types of rocks, namely metaluminous (ultra) basic rock, peralkaline (ultra) basic rock, metaluminous intermediate rock, peralkaline intermediate rock,metaluminous acid rock, peralkaline acid rock, peraluminous acid rock and ultra-acid rock. It is found through an integrated ahalysis and comparison that the composition and structure of minnerals and melts seem to be the most important factors controlling mineral-melt element partitioning. Importanceshould be attached to minral structure and Al-supersaturation of melt which have, not been discussed by research workers. Finally, the present state and theproblems to be solved in the study of mineral--melt element partition coefficients are analysed, and the future trends of this research field are predibted.
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2008,27(2):135-151, DOI:
Abstract:
本文以表格的形式列举了经国际矿物学协会(IMA)新矿物与矿物命名委员会(CNMMN)批准、并于2003年度正式发表的新矿物共55种,其中硅酸盐31种,磷酸盐5种,砷酸盐2种,硫酸盐4种,硫化物3种,碳酸盐2种,钒酸盐2种,硼酸盐1种,硒化物1种,硫盐1种,氧化物1种,氢氧化物1种,复杂卤化物1种.文中表格依次列出了矿物的中外文名称及化学式、晶系及晶胞参数、主要粉晶数据、物理性质、光学性质、产状及共生(伴生)组合等.
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XU Jie, ZHANG Gui-bin, LI Nan, LIN Meng, WANG Jia-xing
2020,39(3):323-334, DOI:
Abstract:
The combination of multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS) and laser ablation provides a useful tool for tracing the geological process by analyzing minerals under microscales. As one of the non-traditional stable isotopes, boron isotope has attracted more and more attention. In this study, the authors developed an in-situ method for high-precision analysis of B isotope in tourmaline with high-content boron and muscovite with low-content boron. Tourmaline and glass reference materials were applied to correcting the mass fractionation respectively, and in-situ B isotopes of two natural samples from southwestern Tianshan were also tested. In addition, the boron isotope of the in-house standard T-PKU was calibrated as -13.07‰±0.42‰ (2SD, n=66). The above testing results reveal that the condition of LA-MC-ICPMS is stable for a long term and suitable to producing high quality data about tourmaline with minimum spot size of 10 μm and muscovite with > 20×10-6 B concentration. The B isotopes of tourmaline and paragonite in Tianshan samples are helpful for tracing fluids sources.
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YAN Ruogu, QIU Zhili, DONG Chuanwan, LI Liufen
2009,28(3):292-298, DOI:
Abstract:
High grade black jadeite is a kind of upscale and fashionable jade material that has become one of the jadeites characterized by fastest growing values in the past 20 years. Based on a comparison of mineralogical and geochemical characteristics between black jadeites (inky black jades)from different producing areas of the world, the authors hold that the black jadeites currently on the market can be mainly classified into jadeite jade, omphacitic jadeite jade and hornblende jade whose main components are jadeite, omphacite and dark green hornblende respectively. They include black chicken jade, ink jadeite and black kosmochlor from Myanmar and jade negro and galactic gold from Guatemala, with black chicken jades similar to those from Myanmar also seen in Japan and Kazakhstan. The research results suggest that the main mineral composition, jade structure and inclusion characteristic combinations of black jadeite jades from different producing areas have their respective typomorphic natures, which can be used as the distinctive characteristics for their sources.
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HE Shi-ping, WANG Hong-liang, XU Xue-yi, ZHANG Hong-fei, REN Guang-ming
2007,26(4):295-309, DOI:
Abstract:
Early Paleozoic volcanic rocks in Tianshui and Baoji areas along the eastern segment of North Qilian orogenic belt consists of Hongtubu basaltic lavas and Chenjiahe intermediate-acid volcanic rocks. Geochemical analyses show that Hongtubu basaltic lavas are similar to the intercalated basalts in Chenjiahe intermediate-acid volcanic rocks in characteristics, both fallen in the tholeiite series with high TiO2 (1.50%~2.73%). Their∑REE are 65.97×10-6~133.46×10-6 and 78.04×10-6~175.55×10-6 respectively, both are slightly enriched in LREE [(La/YbN being 2.00~4.40 and 2.71~4.40 respectively],and both have no obvious Eu anomaly or weak Eu negative anomaly(δEu being 0.85~1.10 and 0.85~0.99 respectively). Basalts from two groups are typically characterized by selected enrichment of LILEs, low abundances of HFSEs relative to NMORB, and prominent troughs of Nb and Ta, with low Nb/La ratio(0.28~0.43), which indicates the affinity of these volcanic rocks to island arc tholeiite(IAT). In addition, εNd(t)(+2.22~+4.08)values of basalts suggest that their mantle sources are similar to the depleted mantle source. Zr/Nb=17.21~36.33 and Ce/Nb=5.73~8.17, implying geochemical characteristics of N-MORB. Sr, Nd and Pb isotopes from Hongtubu basalts are similar to those in Chenjiahe basalts in composition. In the diagrams of εNd(t)-(87Sr/86Sr)t, (207Pb/204Pb)t-(206Pb/204Pb)t,(87Sr/86Sr)t-(206Pb/204Pb)t and εNd(t)-(206Pb/204Pb)t for basalts, the data are fallen in the DM, EMⅠand EMⅡ areas, probably with a little crustalontamination, indicating that the magma of basalts might have had a mixed gin.Thentermediate-acid volcanic rocks from Chenjiahe belong to the calc-alkaline series,they have relatively high abundances of REE∑REE=127.51×10-6~276.01×10-6), and are significantly enriched in LREE[(La/YbN= 4.79~13.51]. Most intermediate-acid volcanic rocks show weak Eu negative anomaly (δEu=0.53~1.20). The trace element patterns of Chenjiahe acid volcanic rocks are similar to those of the ocean ridge granite (ORG), with marked troughs of Nb, Ta, Zr and Hf. A synthetic study shows that the Chenjiahe intermediate-acid volcanic rocks in the eastern segment of North Qilian orogenic belt were formed in an island-arc setting, whereas the Hongtubu basalts were formed in an intra-arc rift setting (or an initial back-arc basin setting), probably being products of the early spreading evolution of the island_arc system towards the back-arc basin in the eastern segment of North Qilian during late Early Paleozoic. The results obtained provide evidence for the existence of the trench-arc-basin system at the juncture of Qilian and North Qinling orogenic belts.
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2022,41(1):185-194, DOI:
Abstract:
The geochemical characteristics and abnormal sources of As, Cd, Cr, Cu, Hg, Ni, Pb and Zn in the soil of Southern Xuancheng were analyzed and studied by using the 1:250 000 land quality geochemical survey data. It is found that the geological background is the main controlling factor for the content of soil elements, and that the spatial distribution characteristics of heavy metal elements in the surface and deep soil in the area are significantly consistent with the geological background and sedimentary environment. The high content of heavy metal in the soil parent rock geological background (Hetang Formation, Piyuancun Formation and Lantian Formation, etc) is the main influencing factor for the high anomaly of soil heavy metal elements. In addition, mining and atmospheric dry and wet deposition are also one of the factors affecting high anomaly of heavy metals in soil. It is found that Pb, Hg, Cd and Cr in soil have input sources of atmospheric dry and wet deposition. The main impact index of heavy metal in soil pollution risk in the survey areas was Cd. The proportion of samples that soil Cd exceeded the control value of soil pollution risk of agricultural land was 2.56%. The morphological analysis results show that soil Cd is mainly in ion-exchange state. Combined with crops investigation, it is found that there is a certain ecological risk in the area with high abnormal soil Cd.
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LIN Bin, TANG Ju-xing, ZHENG Wen-bao, LENG Qiu-feng, LIN Xin, WANG Yi-yun, MENG Zhan, TANG Pan, DING Shuai, XU Yun-feng, YUAN Mei
2016,35(3):391-406, DOI:
Abstract:
The Cuonadong leucogranite is one of the most important parts of North Himalayan leucogranite belt. Geochemical data show that Cuonadong leucogranite is the calcium alkaline and strong peraluminous granite with high silica (SiO2 is 74.20%~74.52%), poor iron (Fe2O3 is 0.04%~0.20%, FeO 0.04%~0.58%), poor magnesium (MgO is 0.06%~0.14%), and calcium alkaline (σ is 2.15~2.32) as well as strong peraluminous nature (A/CNK is 1.11~1.15). Its total rare earth is relatively low (∑REE is 47.24×10-6~57.59×10-6), with enrichment of LREE (LREE is 39.85×10-6~49.23×10-6), depletion of HREE (HREE is 6.91×10-6~8.68×10-6) and obvious negative Eu anomaly (0.49~0.80). It is characterized by an enrichment of some large ion lithophile elements (Rb, Th, U, K) and loss of high field strength elements (Nb, Ta, Zr Ti). Zircon U-Pb dating results show that the Cuonadong leucogranite's formation time is Miocene (21 Ma), which belongs to the peak of the late stage of north Himalayan leucogranite (24~12 Ma). Zircon εHf(t) values are negative with a wide variation (-3.92~-17.64), which shows that its magma source was the crust, mostly from the metapelite, with the probable mixing of many kinds of materials in its source. The petrogenesis of Cuonadong leucogranite is that the high Himalayan crystalline rock series experienced decompression melting during the rapid pull-back of the plate in the post-collision tectonic setting, with the initial magma crystallization temperature being 675~702℃.
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PAN Rong-hao, ZHU Lei, WANG Si-jia, WANG Ji-chen, WU Jia-yi, HOU Tong
2022,41(3):519-536, DOI:
Abstract:
Quantitatively determining the timescale during mantle-derived magma ascent from the source to eruption or emplacement is essential for the understanding of magmatism, however, the timescales of eruption/emplacement are still poorly constrained. Shanxi Datong Cenozoic volcanic field, north of the North China Craton, is an ideal area for the investigation. In this study, we focused on the mantle olivine xenocrysts entrained in ca. 0.2 Ma Shenquansi alkali basalt, and its timescale of residence in the host magma prior to eruption. According to mineral chemistry, cores of these mantle olivine xenocrysts have Fo values up to 97.7, which can be defined as extremely magnesian olivine. They are also characterized by the extremely low contents in Ca, Mn and Ni, suggesting they were captured from metasomatized mantle peridotite. Moreover, both of the mantle olivine xenocrysts display complex CaO profiles, attributed to complex magmatic processes in the magma plumbing system. The reaction rim widths of one olivine xenocryst vary significantly, implying it has experienced multiple crack processes when captured or dur- ing transport. The Fo values of the mantle olivine xenocrysts rims are about 70, indicating they are in diffusion equilibrium with the host magma (alkali basalt) at rims. Timescales obtained by Fe-Mg diffusion chronometry of olivine mantle xenocrysts show that they have only resided in the magma for months. For a lithospheric mantle thickness of 40~70 km, the fastest average ascent rate may exceed 500 m/d.
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CAO Guang-yue, XUE Huai-min, WANG Jin-guang
2014,33(6):1019-1038, DOI:
Abstract:
In this paper,LA-ICP-MS zircon U-Pb dating was carried out for four samples of volcanic rocks from Qingshan Group in Jiaodong area and, as a result, their concordant ages were obtained, which are 119.4±0.9 Ma, 118.2±1.0 Ma,120.2±0.9 Ma and 120.0±0.8 Ma, respectively. The results show that all the volcanic rocks in Jiaodong area were formed from about 120 Ma to 118 Ma in the Early Cretaceous period. The ages of Qingshan Group volcanic rocks from Shandong Province controlled by Tan-Lu fault are similar to those from the Su-Wan segment of the Tan-Lu fault zone,but younger than those around the Tan-Lu fault zone,which indicates that the duration of volcanic eruption along Tan-Lu fault is probably longer than the duration in other areas under the background of lithospheric thinning in eastern China. Geochemically, all the intermediate and acidic volcanic rocks have high K2O, ALK, LREE values and low MgO, TiO2, Ni, Cr, HREE values. According to the geochemical features, the volcanic rocks can be subdivided into trachyte-trachydacite and rhyolite. The trachyte-trachydacite is characterized by LILE enrichment(Rb,Ba,K)and HFSE depletion(Nb,Ta,Ti,P), but the rhyolite exhibits stronger depletion of Ba,Sr and HFSE (Ti,P). Compared with the rhyolite,the trachyte-trachydacite possesses higher Sr and Ba values as well as La/Nb and Ba/Nb ratios,but lower Rb/Ba ratios and δEu values. All these data indicate that they might have been derived from different magma sources. It is inferred that the trachyte-trachydacite rocks were derived from the mixture of the partial melting of the lower crust(Yangtze Craton or North China Craton)and enriched lithospheric mantle. In addition, the rhyolites were related to the partial melting of the lower crust in the regional extension environment and high geothermal anomaly background with crystallization differentiation during the magma evolution.
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2014,33(4):747-762, DOI:
Abstract:
Cordierite is a mineral material characterized by low thermal expansion coefficient and good thermal shock resistance. Cordierite mineral material is relatively rare in nature, so cordierite is synthesized usually by the method of artificial synthesis. Based on the newest investigation results of synthetic cordierite, this paper deals with the progress of researches on such synthesis methods of cordierite as high purity oxide solid reaction at high temperature, natural mineral solid reaction at high temperature, the utilization of industrial wasted materials, the employment of agricultural wasted materials, the sol-gel and the low-temperature combustion synthesis. At present, the method of natural mineral solid reaction at high temperature is used for the preparation of cordierite in industry. In spite of a lot of advantages, this method also has many disadvantages. Therefore, the development trend of cordierite synthesis seems to solve the problem as to how to apply other synthesis methods to industrial preparation.
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GUO Li-he, HAN Jing-yi, LUO Hong-yu
2006,25(4):349-356, DOI:
Abstract:
At present, the infrared transmission spectroscopy is the best technique for determining whether jadeite is polymer-impregnated or not, and the infrared reflectance spectroscopy is a nondestructive and rapid determination method that provides mainly the fundamental frequency vibration spectra data of minerals and shows new application potentials in gemological research, especially in the identification of gem species. The gemological application of IR reflectance spectroscopy and the identification system of IR spectra of gems, including a database of 318 spectra and a searching and identifying program, are described in this paper.
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2013,32(4):485-495, DOI:
Abstract:
Petrology, geochemical and Nd isotopic data are reported for the Neoproterozoic Danba metabasalt in the Kangdian Rift on the western margin of the Yangtze block. Samples were collected from alkaline basalts, which are enriched in MgO, TiO2, with Mg# being 0.51~0.59. They have high total rare earth elements and show high fractionation between LREE and HREE. The trace elements are characterized obviously by enrichment of Th, Nb, Ta, Zr, Hf and LREE but depletion of Y and HREE. Their geochemical and Nd isotopic characteristics suggest that they are similar to OIB. The basaltic magma was generated in an intraplate setting, and was generated by partial melting of OIB mantle source region, with variable degrees of contamination of SCLM during magma ascending; in addition, some samples might have experienced contamination of the lower crust. These samples reveal some plume magmatism characteristics in petrochemistry, and imply that magmatism was probably related to the Neoproterozoic plume event, which resulted in the breakup of Rodinia supercontinent.
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LUO Yue-ping, DENG Wang-hui, DUAN Ti-yu, WANG Chun-sheng
2011,30(Z1):181-186, DOI:
Abstract:
As more and more treated turquoises appear on Chinese gem market, the authors collected lots of turquoises from different deposits on Chinese gem market in order to sum up the characteristics of the natural turquoises on Chinese gem market. At the same time, different types of treated turquoises were studied to find general difference between them and natural turquoises. The results show that natural turquoise and treated turquoise have different shades of color, inclusions and appearances. IR spectra of both natural and treated turquoises were studied, indicating that there are absorption peaks at 1 735, 1 600 and 1?500 cm-1 in treated turquoises, which are caused by the man-made polymer. If the turquoise is treated by polymer, there are absorption peaks at 1 735, 1 600 and1 500 cm-1 in a turquoise, and this can serve as convincing evidence in this aspect.
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2013,32(4):529-537, DOI:
Abstract:
The newly-exposed lower strata of the Xiamaling Formation near Tielingzi Village in Jixian County contain rich siderites. This paper reports the basic geological characteristics of these siderite-rich strata in terms of the field outcrop, petrology and major elements. Studies show that the profile is characterized by black shale interbedded with silty iron-rich layers/siderite concrete layers, and also has minor siltstone. Some iron-rich strata have turned into limonite layers in the outcrop because of intense weathering. Siderite is the main iron mineral phase in the strata. Siderites can form iron concretes, showing micritic or microcrystalline granulitic textures under the microscope, or form silty ferruginous layers with almost a comparable amount of silty quartz; it can also distributed sporadically in siltstone and black shale with relatively coarse particles. There also exists very little siderite residue in weathered limonite layers. The overall features of major elements show that the strata are rich in SiO2, TFe and TOC, but poor in MnO, CaO, MgO, P2O5 and S. Except for ferriciron in weathered layers, there is mainly ferrous iron in the strata. The TOC content decreases in order of siderite concrete, silty iron-rich layer, black shale and siltstone. The correlation diagram between TFe and Al2O3 content shows a negative correlation in iron-rich layers, while a positive correlation between them exists in normal black shale and siltstone, which suggests that iron in the former form originated from the ocean itself, while iron in the latter form originated mainly from terrigenous detritus. In addition, FeO content has a positive correlation with TOC content in fresh samples, which implies that the genesis of siderites may have some relationship with organic matter.
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1997,16(1):81-90, DOI:
Abstract:
From the discovery of the first new mineral hsianghualite in 1958 to the end of 1995,74 new minerals found in China had been approved by IMA CNMMN. Among them, 2/3 were discovered after 1981. The discovery of new minerals in China has the following features:(1) With the development of analytical methods, the number of new minerals discovered per year increases gradually: from the end of 1950s to 1960s, only one new mineral was discovered every year on the average, whereas from 1980s till now, three new minerals were discovered averagely every year. (2) The structures of many new minerals have been determined. (3) Most of the new minerals are in the lower category, mainly in the monoclinic system, and perfect crystals are rare; hsianghualite has the most abundant crystal faces, whose ideal faces can reach 146. (4) Among those new minerals, silicates take the first place in number, followed by native elements, alloys, and then oxides. (5) The modes of occurrence of new minerals are varied, most of them occurring in oxidized zones of various deposits and deposits related to ma fic or ultramafic rock masses. There are a few new minerals occurring in skarn and placer deposits or even in cosmic dusts and meteorite.(6) The new minerals are characterized by wide but uneven distribution. Till now, new minerals have been discovered in 20 provinces or autonomous regions, especially in Hebei, Qinghai, Inner Mongolia and Henan. The number of new minerals found in North China is larger than that found in South Chine. (7) The number of discoverers of new minerals is in tens. The first discoverer of new mineral is Prof. Huang Yunhui, whereas Prof. Yu Zuxiang is the one who discovered the most numerous new minerals in China, totally disclosing 11 new minerals by himself or together with other experts. Most of the discoverers are members of the Chinese Academy of Geological Sciences, China University of Geosciences, and Institute of Geochemistry, Academia Sinica as well as other educational and scientific research institutions. The discovery of new minerals has promoted the development of mineralogy in China. Tens of discoverers were awardees of the National Natural Sciences Prize or the Science and Technology Progress Prize of the Ministry of Geology and Mineral Resources for the discovery and research results of new minerals in 1980s. More than 60 new mineals discovered in China were collected by the Geological Museum of China, with some of them exhibited in the Minerals and Rocks Exhibiting Room.
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TAO Ji_xiong 1, HU Feng_xiang 1, CHEN Zhi_yong 1, 2
2003,22(2):112-118, DOI:
Abstract:
Indosinian S-type granites are widely distributed in central Inner Mongolia on the northern margin of North China landmass. Spread in nearly EW direction, the granites have formed a gigantic compound granite belt, with porphyritic biotite-admellite and moyite being the two main types. SiO2is abundant, Al2O3is 12.38%~15.34%. A/NKC (molecule ratio)>1.1, K2O/Na2O=1.1~3.1,δ=1.9~2.6,ΣREE is 45.778 ×10-6~486.501×10-6, andδEu=0.1~0.8. A series of zircon U-Pb surface ages (207~227 Ma) for the granites have been recently obtained from 1/50 000 regional geological survey. As the lithofacies and geochemical characteristics of the granites are similar to those of S-type granites, the authors conclude that the Indosinian granite in this area was formed in a post-collision setting instead of in the setting of syn-collision between North China plate and Siberia plate.