Abstract:

The Central Asian Orogenic Belt (CAOB) is the largest Phanerozoic accretionary orogenic belt on Earth, and central Inner Mongolia is widely regarded as the key segment marking the final closure of the Paleo-Asian Ocean within the CAOB. As a critical region for constraining the tectonic transition that followed the closure of the Paleo-Asian Ocean, central Inner Mongolia has long attracted considerable attention owing to its complex tectono-magmatic evolution. In this study, the monzogranite exposed in the Wulantaolegai area was investigated through petrography, whole-rock major- and trace-element geochemistry, LA-ICP-MS zircon U-Pb geochronology, and zircon Hf isotopic analyses to constrain its emplacement age, magma source, and tectonic setting. The results show that the monzogranite yields a zircon U-Pb age of 259.2±3.8 Ma (MSWD=1.2), indicating emplacement in the Late Permian. Whole-rock geochemical data indicate that the pluton is characterized by high silica (SiO₂=73.43%~75.15%), elevated Al₂O₃ (13.32%~14.24%), high total alkalis (Na₂O+K₂O=8.18%~8.61%), and low Fe-Mg contents, with aluminum saturation indices (A/CNK) of 1.05~1.11. It is enriched in light rare earth elements and large-ion lithophile elements such as Rb, Th, and K, but depleted in heavy rare earth elements and in Nb, Sr, P, and Ti, and is dominated by negative Eu anomalies, thus belonging to weakly peraluminous Ⅰ-type granite. Zircon Hf isotopic compositions yield εHf(t) values of -16.44 to -2.04 and two-stage Hf model ages (t_DM2) of 2 322~1 413 Ma, suggesting that the magma was derived predominantly from partial melting of ancient crustal materials, with the possible involvement of a very minor depleted component. In combination with the regional tectono-magmatic evolutionary framework, we propose that the Late Permian monzogranite in the Wulantaolegai area was generated by crustal remelting under a post-closure lithospheric thinning or extensional regime following the closure of the Paleo-Asian Ocean, indicating that central Inner Mongolia had entered a post-collisional to post-orogenic extensional tectonic regime by the Late Permian.

Abstract:

The Gaochun Cu polymetallic deposit, located in the northern part of the Xuancheng ore concentration district within the Middle-Lower Yangtze River Metallogenic Belt, is a newly discovered mineralization area. This study focuses on diorite porphyry and quartz diorite porphyry exposed by drilling in the Gaochun mining area. Through zircon LA-ICP-MS U-Pb dating, whole-rock major and trace element analysis, zircon in-situ Hf isotopes, and whole-rock Sr-Nd isotope measurements, the formation age, magma source, and petrogenesis of the intrusive rocks are systematically investigated. The results show that the zircon U-Pb ages of diorite porphyry and quartz diorite porphyry are 134.1±2.0 Ma and 133.9±2.2 Ma, respectively, indicating they were products of Early Cretaceous magmatic activity. Geochemically, the rocks are characterized by high-K calc-alkaline and metaluminous affinity, enrichment in large ion lithophile elements (e.g., Rb, Ba, Th), depletion in high field strength elements (e.g., Nb, Ta, and Ti), significant fractionation of light and heavy rare earth elements, and weak Eu anomalies. Sr-Nd-Hf isotopic compositions suggest that the magmas were derived from mixing of an enriched mantle source and ancient crustal materials (Archean-Paleoproterozoic basement), accompanied by varying degrees of fractional crystallization and assimilation. Comparisons with intrusive rocks from the adjacent Chating ore district and the Tongling ore cluster indicate that the Gaochun intrusions are genetically linked to the first stage of crust-mantle interaction in the Middle-Lower Yangtze River Metallogenic Belt, formed in an intracontinental extensional setting following the subduction of the Paleo-Pacific Plate, involving magmatic underplating and mixing. This study provides new petrogeochemical evidence for understanding the deep magmatic-mineralization mechanisms in the Xuancheng ore cluster.

Abstract:

In recent years, a new breakthrough in mineral exploration has been achieved in the Choushuigou area of Beishan, Gansu Province, where medium-sized and above VMS-type copper polymetallic deposits have been discovered. However, there is still controversy over their diagenesis and mineralization age, and a lack of precise dating basis has constrained the summary of mineralization laws and analysis of mineralization processes. Based on field geological surveys, the LA-ICP-MS zircon U-Pb dating was employed to conduct high-precision isotopic chronology on the ore-hosting phyllitic basaltic tuff. The U-Pb age of the zircon is 277.4±0.72 Ma, which is from the late Early Permian period. Therefore, it is classified as the Permian Jinta Formation rather than the previously classified Carboniferous Hongliuyuan Formation, indicating that the late Early Permian was also an important period for submarine volcanic-hydrothermal mineralization in the area. Comprehensive analysis demonstrates that the diagenesis and mineralization in the Choushuigou area occurred within an extensional rift setting during the Early Permian. The deposit exhibits definitive characteristics of the VMS-type copper polymetallic deposit, and the phyllitic basaltic tuff of the Permian Jinta Formation and VMS-type copper polymetallic deposits are key directions for breakthroughs in regional mineral exploration.

Abstract:

The Qingchengzi ore concentration area in eastern Liaoning Province is located within the Jiao-Liao-Ji tectonic belt. Since the gold and polymetallic ore deposits are strictly controlled by the "silicon-calcium interface" within transitional zone between the Paleoproterozoic Dashiqiao and Gaixian formations of the Liaohe Group, precise correlations of ore-hosting strata are crucial for regional and deep metallogenic prediction and exploration. This study focuses on 170 marble core samples from the Dashiqiao Formation and 2 granite porphyry core samples intruding into the marble, collected from one 1 000 m deep drillhole (ZK12-11) and two 2 000 m deep drillholes (ZK11-8, ZK12-20) recently conducted in the Qingchengzi ore concentration area. Carbon-oxygen isotopic and zircon U-Pb geochronological analyses were conducted on the marble and granite porphyry samples, respectively. Carbon-oxygen isotopic results show that the δ¹³C_V-PDB values of the marbles from the three drillholes have no positive anomaly. This suggests that the protoliths of marbles were deposited after the Lomagundi-Jatuli Event (2.33~2.06 Ga or 2.22~2.1 Ga) and stratigraphically correspond to the upper, thin- to medium-bedded, ore-bearing marble member of the Dashiqiao Formation. Therefore, the bottoms of the 1 000~2 000 m drillholes have not yet reached the lower-middle, non-ore-bearing, thick-bedded marble member of the Dashiqiao Formation that are characterized by positive carbon isotope anomaly. This finding indicates significant potential for deep metallogenic prediction and exploration beneath the currently explored horizons in the Qingchengzi ore concentration area. Zircon U-Pb dating of two granite porphyry samples intruding into the marbles in drillhole ZK11-8 from Taoyuan area yielded crystallization ages of 221±3 Ma and 222±1 Ma, respectively. These results confirm that the emplacement of granite porphyry dykes and the main mineralization epoch in the Qingchengzi area occurred during the Late Triassic at around 220 Ma. In addition, the carbon-oxygen isotopic results demonstrate that the intrusion of dykes and subsequent hydrothermal alteration significantly impacted the isotopic compositions of the carbonate rocks, leading to decreases in their δ¹³C_V-PDB and δ¹⁸O_V-SMOWvalues. In contrast, regional metamorphism had no significant or inhomogeneous effect on the carbon-oxygen isotopes of the carbonate rocks. Even within high-grade metamorphosed orogenic belts, some marbles may largely retain the primary carbon-oxygen isotopic signatures of their sedimentary protoliths, and can therefore provide critical evidence for paleoenvironmental studies and regional stratigraphic correlation. It is recommended that future deep metallogenic explorations in the Qingchengzi ore concentration area should focus on the upper member of the Dashiqiao Formation near regional faults such as the Jianshanzi and Erdaogou faults showing no positive carbon isotope anomaly, especially the strata with strong hydrothermal alteration and low carbon-oxygen isotopic compositions within this formation, as well as the peripheral zones of Late Triassic granitic porphyry dykes within this sequence.

Abstract:

Neoproterozoic mafic dyke swarms are key indicators for reconstructing the timing and dynamic processes of the Rodinia supercontinent breakup. Based on systematic analyses of zircon chronology, whole-rock geochemistry, and zircon Lu-Hf isotopes, this study investigates the petrogenesis and geodynamic setting of a newly discovered diabase dyke swarm in the Mianning area on the western Yangtze Block, South China. LA-ICP-MS zircon U-Pb dating reveals that the Mianning diabase crystallized at 835.8±4 Ma, indicating its formation during the Neoproterozoic. The diabase exhibits variable SiO₂ content (45.2% to 48.0%) and MgO (6.82% to 8.15%) contents, as well as Mg^# values (46~57), along with high Al₂O₃ (14.00%~15.75%) content. The studied rocks display relatively flat rare earth element (REE) distribution patterns, with enrichment in Rb, Ba, and K, and depletion in Nb, Ta, Sr, and P. The studied rocks exhibit enriched zircon Lu-Hf isotopes [εHf(t) = -2.2~1.6]. Petrogenetic analysis indicates that the Mianning diabase originated from low-degree partial melting of an enriched mantle wedge, with the mantle source having been modified by fluids derived from altered oceanic crust. The Neoproterozoic Mianning diabase on the western Yangtze Block formed in an extensional continental arc setting, implying that the western margin of the Yangtze Block may have been located at the periphery of the Rodinia supercontinent during the Neoproterozoic era.

Abstract:

Late Neoarchean granitoid gneisses are widely distributed in the Early Precambrian metamorphic basement of the Liaonan Block, the North China Craton (NCC), and record important information on the formation and evolution of the continental crust in the Early Precambrian. In this study, we present zircon LA-ICP-MS U-Pb ages, trace element compositions, and Lu-Hf isotopic data from four granitoid gneiss samples collected from the Liaonan Block. Most zircons exhibit oscillatory zoning and high Th/U ratios (0.18～2.21), along with REE patterns characterized by depleted LREEs and enriched HREEs, consistent with a magmatic origin. The ²⁰⁷Pb/²⁰⁶Pb weighted mean ages of the four granitoid samples are 2 529±10 Ma (MSWD=0.12, n=14), 2 475±27 Ma (MSWD=3.1, n=13), 2 502±15 Ma (MSWD=2.7, n=14), and 2 478±8 Ma (MSWD=0.81, n=25), respectively, recording the magmatic events related to crustal differentiation during the late Neoarchean. Zircon Hf isotopic compositions show positive εHf(t) values (+0.11 to +5.29), with two-stage model ages (t_DM2) ranging from 2.9 to 2.7 Ga, suggesting the granitoids were derived mainly from partial melting of juvenile crust formed during this period. A few zircons yield negative εHf(t) values (-3.2 to -0.8) and older t_DM2 ages of 3.12～2.90 Ga, reflecting the involvement of ancient reworked continental crustal components older than 2.9 Ga. Combining the new results with published zircon Hf isotope data, it has been demonstrated that the Liaonan Block experienced major crustal growth during 2.9～2.7 Ga and crustal reworking at 2.5 Ga and 2.47 Ga, which were driven by upwelling mantle. The resulting widespread potassic granitic rocks signify the stabilization and cratonization of the block.

Abstract:

Currently, scholars at home and abroad have gained profound insights into the genesis mechanisms of porphyry molybdenum deposits developed in arc and rift environments. However, scientific questions regarding the diagenesis, mineral source regions, and other aspects of porphyry molybdenum deposits within the North China Craton remain controversial and warrant further investigation. This paper reports the (rhyolitic porphyry)diagenetic and mineralization ages, along with the Hf isotopic composition of mineralized rhyolitic porphyry from the Dawan porphyry molybdenum deposit within the Laiyuan Complex. The study reveals: the SHRIMP zircon U-Pb age of the rhyolitic porphyry is 137.1±0.6 Ma, the Re-Os isochron age of six molybdenite samples is 140.6±1.9 Ma, and the rhyolitic porphyry has εHf(t) values of -28.2~-22.3, the Re isotopic content of Dawan porphyry molybdenum deposit ranges from 19×10^-6 to 26×10^-6, showing characteristics of a crust-mantle mixed source with a predominant crustal component. The Mujicun porphyry copper deposit and Dawan porphyry molybdenum deposit are spatially associated with relatively consistent diagenetic and mineralization ages. Furthermore, the Hf isotopic compositions of the gabbro-diorite from the Laiyuan complex, the mineralized dioritic porphyry from Mujicun, and the mineralized rhyolitic porphyry from Dawan are similar, suggesting a possible common magmatic source for the gabbro-diorite, dioritic porphyry, and rhyolitic porphyry. Within Late Mesozoic extensional tectonic setting, the ore-bearing rhyolitic porphyry originated from gabbroic parent magma formed by partial melting of enriched lithospheric mantle. During its ascent, the gabbroic magma underwent significant lower crustal mixing. Thermal erosion may be the deep mechanism for the formation of ore-bearing porphyry of Dawan Porphyry Mo deposit in the North China Craton.

Abstract:

The Yanshanian granites widely distributed in Southern Jiangxi serve as important metallogenic hosts for granite-type rare metal deposits. Taking the Jiangkengli Nb-Ta deposit in Shicheng as the research object, this study systematically compares the geochemical differences between mineralized and non-mineralized granites through field geological surveys, petrographic analysis, whole-rock geochemical testing, and U-Pb chronology. The results show that the mineralized granites are predominantly sodic calc-alkaline series, which are significantly enriched in Al₂O₃, ^TFe₂O₃, and MnO compared with non-mineralized granites. They are characterized by low total rare earth elements (ΣREE<20×10^-6), low Nb/Ta (<3), low Zr/Hf (<5), and high Rb/Sr (>150), based on which quantitative discrimination indices for mineralized granites are established. Isotopic chronology reveals that the monazite U-Pb age of zinnwaldite-albite granite is 144.9±0.8 Ma. Combined with regional metallogenic age comparisons, it is inferred that 145~140 Ma represents a unique Nb-Ta mineralization period in Southern Jiangxi. The ore-forming mechanism indicates that the deposit formed through the synergistic evolution of highly differentiated magma and F/Li- rich fluid alteration. This study provides key geological references for rare metal prospecting in Southern Jiangxi.

Abstract:

The Hangjinqi area in Inner Mongolia is one of the significant uranium-bearing regions in the northern Ordos Basin, with favorable geological conditions and promising exploration prospects for mineralization. This paper conducts sedimentological, petrological and geochemical analyses on the core samples of the Middle Jurassic Zhiluo Formation from the borehole X7-6 in the Hangjinqi area, systematically studying the conditions conducive to uranium enrichment and mineralization. The research results show the lower section of the Zhiluo Formation comprises braided river deposits, mainly composed of the thick-bedded gray sandstone and thin mudstone interbedded with thin coal seams, rich in carbonaceous debris and pyrites, while the upper section is characterized by meandering river and deltaic sedimentation, dominated by purple-red siltstone and mudstone.The geochemical characteristics exhibit a "right-inclined" pattern with enrichment of light rare earth elements and depletion of heavy rare earth elements. The chemical index of alteration (CIA) values rangs from 54 to 77,indicating moderate chemical weathering of the Zhiluo Formation during deposition. The paleoenvironmental and paleoclimatic discrimination indicators Sr/Cu, U/Th, V/Cr, Ni/Co, V/(V+Ni), and Sr/Ba values suggest that the paleowater system during the deposition of the Zhiluo Formation was an oxygen-rich freshwater environment, and the paleoclimate underwent a transition from alternating dry and wet conditions to arid and semi-arid conditions. The tectonic setting of source areas of the Zhiluo Formation are continental arcs, and the provenances are primarily composed of the upper crustal felsic rock. The sedimentary environments, tectonic setting, paleoclimate and provenance characteristics can provide favorable geological conditions for uranium enrichment and mineralization in the Zhiluo Formation of the Hangjinqi area.

Abstract:

The Mesozoic magmatic activity in the Bozhushan area of southeastern Yunnan plays an important role in regional tectonic evolution and mineralization. A large number of aplite bodies are developed around the Bozhushan pluton in this area, yet previous studies on the timing and petrogenesis of such rocks remain limited. This paper focuses on the Dashanjiao aplite in Bozhushan and investigates its genesis and metallogenic implications through LA-ICP-MS zircon U-Pb dating, whole rock major and trace element analysis, and zircon Lu-Hf isotopic testing. Dating results indicate that it formed in the Late Cretaceous (89.1~87.5 Ma), consistent with the age of regional Yanshanian granites. Geochemical characteristics reveal that it is a highly fractionated S type granite, characterized by peraluminous to metaluminous composition, enrichment in silicon and alkali, and depletion in magnesium and iron. Zircon εHf(t) values range from -7.79 to -5.07, with t_DM2 model ages of 1 451~1 300 Ma, suggesting that the magma was derived from partial melting of Mesoproterozoic crust. The pluton formed in a post collisional extensional setting under the background of Pacific Plate subduction. Its geochemical features (e.g., depletion in Ba and Sr, high Rb/Sr ratio) reveal significant magmatic crystallization differentiation. Combined with previous research findings, it is concluded that the aplite and the granites in the region are products derived from the same source region but underwent different degrees of crystallization differentiation, the Late Cretaceous highly fractionated S-type aplite originated from the low-temperature melting of Mesoproterozoic clay-rich crust, and the associated magmatic hydrothermal differentiation process played an important controlling role in regional W-Sn-Ag polymetallic mineralization.

Abstract:

The Qijia gold deposit is a recently discovered quartz-vein type gold deposit located in the Chifeng-Chaoyang gold district along the northern margin of the North China Craton, hosted in the Mesozoic porphyroid granite. The gold mineralization can be divided into three mineralization stages: quartz±pyrite, quartz-polymetallic sulfide, and quartz-carbonate±pyrite. The gold mineralization is closely related to the silicification and sericitization. Based on field geological investigations, we systematically studied the occurrence state of gold from the Qijia gold deposit by using optical microscope and scanning electron microscope observations, combined with electron microprobe analysis for gold grains. The results indicate that gold in the Qijia gold deposit primarily occurs in three forms: fissure gold, interstitial gold, and inclusion gold. Gold grains are mainly observed in pyrite, followed by quartz, with occasional occurrences of chalcopyrite and galena. According to the grain size, gold can be subdivided into coarse-grained gold, medium-grained gold, fine-grained gold, and micro-grained gold, with fine-to micro-grained gold dominant. Gold exhibits diverse morphologies, predominantly granular-based, along with needle-like, leaf-like, hook-like, and branch-like forms. The compositions of gold grains are primarily Au and Ag, with gold fineness range between 678 and 883. They are mainly native gold and electrum, containing trace amounts of Te, Fe, and S. Based on comprehensive geological and geochemical characteristics, we proposed that the Qijia gold deposit belongs to the mesothermal magmatic-hydrothermal type gold deposit.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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℃.

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.

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.

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.

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.

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.

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.

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.

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.

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.