Abstract:

Recent advances in Meso-Neoproterozoic chronostratigraphic research in China have yielded critical datasets and candidate sections for establishing standardized stratigraphic frameworks. This study presents new chronostratigraphic findings from the southern margin of the North China Craton. Zircon U-Pb dating reveals that tuff interbeds in the Longjiayuan Formation from Luonan County (1 526±16 Ma, MSWD=0.43, n= 8) and Qishan County (1 535±11 Ma, MSWD=0.68, n=12), Shaanxi Province, constrain these deposits to ca. 1.53~1.52 Ga. SHRIMP U-Pb ages of tuffaceous siltstone interbeds in the Duguan Formation further indicate an age older than 1 385±46 Ma (MSWD=1.07, n= 6). Integrating these results with prior studies, we propose a revised Mesoproterozoic chronostratigraphic framework for North China, addressing the stratigraphic void within the Unnamed System and advancing the standardization of the Qingbaikou System. High-precision tuff-zircon ages from the Luoyukou Formation, Longjiayuan Formation, and Duguan Formation enhance regional correlations between the Changcheng System and Jixian System, supporting their establishment as continuous, complete stratigraphic units and strong candidates for global geostratigraphic standards. Nevertheless, the discontinuous distribution of the Unnamed System and Qingbaikou System in North China, coupled with insufficient geochronological constraints, presents challenges for reconstructing the 1.3~0.8 Ga stratigraphic column and formalizing these systems as standardized geostratigraphic units in the near term.

Abstract:

The study of structures along the margins of tectonic units is crucial for exploring the interactions between blocks or plates. The analysis of structural styles near the Zhulazaga ore district on the eastern margin of the Alxa Block not only helps to understand the process of structurally controlled ores, but also can reveal the interaction between the Alxa Block and the North China Plate. The strata in Zhulazaga area is mainly composed of the Mesoproterozoic Zenglongchang Formation and the overlying Agulugou Formation. Results of geological survey show that they are in parallel unconformity contacts. The specific structural styles are: ① the strata form an open anticlinorium, with the axis plunges towards the east and the hinge gently dipping towards the SSE or SSW. During the folding, a series of secondary folds and bedding-cleavage structures are widely developed due to interlayer shearing; ② In the western limb of the fold, the Zenglongchang Formation is thrust over the Agulugou Formation, causing the northeast-verging of folds within the Zenglongchang Formation, which is different from the occurrence of Zenglongchang Formation within the main fold. This is resulted from the top-to-the northeast thrust in the late stage. The formation age of undeformed granite within the folds is 274±3 Ma, which constrains the end time of the regional deformation and is consistent with the mineralization age. Referring to the planar graph and exploration profiles, it is believed that the anticlinorium and fault in the core controlled the mineralization, and the ore bodies were distributed in the transition area from the eastern limb of the anticline to the hinge zone. Based on regional geological data, it is suggested that the anticlinorium formed under the compression associated with the southward subduction of the Paleo-Asian Ocean in the late Paleozoic, followed by the plunging of the hinge related to the sinistral shearing of the Bayan Ul Mountains. The northeastward thrusting is due to the remote effect of the compression in the Tibetan plateau during the Cretaceous. The structural style of rocks near the Zhulazaga area reflects the shortening of the crust and the accompanying shearing during the orogenic process, which is an important example for studying the interaction between blocks or plates.

Abstract:

There are abundant brine-type lithium resources hosted in the Upper Cretaceous Zhoutian Formation of the Jitai Basin, Jiangxi Province. However, its sedimentary evolution and depositional model remain controversial. On the basis of previous studies, through the detailed description of the cores of five boreholes in Meigang area of the Jitai Basin, combined with petrology, mineralogy and sulfur isotopes of gypsum, the lithofacies associations were analyzed, sedimentary facies types and sedimentary characteristics were identified, and the sedimentary evolutionary processes of the Zhoutian Formation were summarized. According to the lithofacies associations and sedimentary structures, the sedimentary system of the Zhoutian Formation can be divided into shore-shallow lake sedimentary system in the lower part and salt lake sedimentary system in the upper part. In the early deposition stage of the Zhoutian Formation, the depositional center was located between Taihe and Zhixia areas in the southeast basin, and was mainly composed of conglomerate, fine sandstone, muddy siltstone and silty mudstone. The alluvian-fluvial facies developed at the edge of the lake basin, transitioning to delta facies in the intra-basin, and to the sedimentary center of the lake basin, shore-shallow lake facies. In the late deposition period of the Zhoutian Formation, the climate gradually became arid, and a salt lake environment was formed by the continuous evaporation of the lake water. The rhythmic deposition of mudstone and gypsum rocks was developed, indicating the periodic salinization and desalination process of the lake water. The δ³⁴S value of gypsum is of 8.0‰~15.4‰, mainly concentrated in the range of 10.1‰~12.8‰, indicating that the gypsum was formed in an open salt-forming environment, and almost unaffected by the bacterial reduction process. In the Meigang area, the salt-bearing strata thicken towards the northwest, with well-developed fractured reservoirs, presenting a promising prospect for lithium brine-type deposit exploration.

Abstract:

In order to investigate the sedimentary environment, controlling factors and formation pattern of the shale of Longtan Formation of the Upper Permian in eastern Sichuan Basin, systematic tests of organic petrology, organic geochemistry and elemental geochemistry were conducted on the shale samples from Huayingshan profile as the research object. The results indicated that the source rock of the Longtan Formation shale in the studied area is complex. Diagrams of Co/Th-La/Sc, La/Yb-ΣREE and TiO₂-Al₂O₃/TiO₂ suggested that the source rocks of the Longtan Formation shales are mainly Emeishan basalt with high Ti content and intermediate acidic volcanic rocks. The trigonometric diagrams of Th-Sc-Zr, Th-Co-Zr and La-Th-Sc showed that the source rocks were mainly formed in the tectonic background of passive continental margin environment. The average chemical alteration index (CIA) of the Longtan Formation shale was 80.64, indicating moderate to high intensity weathering; the Sr/Cu values ranged from 0.48 to 8.08, with an average of 2.22, and the MgO/CaO values ranged from 0.62 to 52.58, with an average of 14.36, reflecting warm and humid climate condition during the sedimentation period of the Longtan Formation overall. The Sr/Ba values ranged from 0.37 to 1.86 and 100 MgO/Al₂O₃ values ranged from 3.27 to 5.45, indicating a semi-saline transitional sedimentary environment. The mean value of Zr/Al was 7.97×10^-3 and that of 100 Mn/Fe was 0.68, indicating that the sedimentary water in the Longtan period of the Huayingshan area was relatively shallow and was also consistent with the geological background of shallow continental shelf reported by previous studies. The V/(V+Ni) values ranged from 0.62 to 0.98, averaged 0.89, Ni/Co values ranged from 0.47 to 13.81, averaged 5.49, and Ce_anom values had averaged value of 0.03, suggesting that the sedimentary water of the Longtan Formation was mainly in a weakly reductive to reductive environment. In terms of sedimentary environment, organic matter characteristics and geological background, it could be inferred that the organic-rich shale of the Longtan Formation was formed in a warm and humid climate environment. In the background of strong weathering, after the death, the higher plants entered the water body accompanied with the numerous input of terrestrial debris formed by basalt and intermediate acidic volcanic rocks, and high plants rapidly deposited, buried, and effectively preserved under the background of the condition of rapid deposition, and finally that high-quantity source rock with inclined kerogen type was formed.

Abstract:

Catastrophic events contain important geological information, and their relics have economic and scientific value. Discovering and studying catastrophic events is one of the methods to solve geological problems and also a way to improve the understanding of geological science. This article lists the main catastrophic events of the Permian bauxite rock series in western Guangxi basing on field investigations, microscopic feature studies, and analysis of heavy metal elements in the bauxite-bearing rock series, and explains their formation. The main catastrophic events in bauxite-bearing rock formations are volcanic ash season, heavy metal anomalies and earthquake episode. The duration span of volcanic ash deposition can extend to 10 Ma, and the lithology of volcanic ash varies from basic to acidic, showing the arc-related calc-alkaline magma series. Compared to bauxite ore concentration areas in the North China and North Guizhou, the bauxite-bearing rock series in studied sections of western Guangxi is strongly enriched in Cr, with an average value of 400×10^-6 to 900×10^-6, whereas Ni is strongly enriched in some sections, with an average value of 300×10^-6~600×10^-6, Cd is enriched in most sections, but Co is enriched in few sections. In addition, Sb and As are greatly enriched in the rocks with felsic volcanic ash. Six elements including Cr, Ni, Cd, Sb, As, and Co constitute heavy metal anomalies. The seismic relics include soft deformation, seismic turbidite, and small graben, etc. The triggering factors for volcanic ash fall and seismic episode were probably the subduction of the Indosinian plate beneath the southwestern margin of the South China plate, which formed island arc magmas and volcanic eruptions, meanwhile the back arc basin tension caused earthquakes. Volcanic ash not only provides substances such as aluminium and iron for bauxite-bearing rock series, but also heavy metals which generated to heavy metal anomalies

Abstract:

The Paleocene to Early Eocene was an important climate transition period in the Cenozoic Era, with multiple extreme heat events leading to a weakening of the earth's surface carbon sink capacity and fluctuations in sea levels. Since the Eocene epoch, marine sediment has been recorded in only three areas in China, and the Karatal Formation in southwest Tarim retains a complete record of marine transgression during this period, making it an important stratum for studying the Cenozoic paleoclimate and the evolution of the paleo-Tethys Ocean. This article focuses on the study of extreme climate sedimentary characteristics recorded by the Karatal Formation. The results show that: ① the Karatal Formation records a reliable astronomical cycle, with a depositional duration of 6.6 Ma, consistent with the Lutetai Stage; ② Five components of the storm sequence, namely grain sequence bedding, parallel bedding, mound cross bedding, wavy bedding and massive mudstone, observed in the Kalatal Formation, indicating that the Tarim Basin was in the tropical-subtropical low-latitude area where storms frequently occurred during the sedimentary period; ③ Affected by differences in sedimentary facies and hydrodynamics, 10 types of ooids have developed, including radial ooid, concentric ooid, superficial ooid, complex ooid, elliptical ooid, and eccentric ooid of primary sedimentary origin, as well as micritic ooid, deformed ooid, negative ooid, and dolomitized ooid of secondary alteration origin. In the middle Eocene, abnormal climate events pushed up sea level and seawater entered the Tarim Basin, which lasted until the end of the Lutetai Stage. During the sedimentation period, under the control of greenhouse effect, storms occurred frequently, CO₂ concentration increased, seawater evaporation increased, and continental weathering intensified. The long-term deterioration of the environment resulted in opportunistic selection characteristics of biological fossils. This article supplements the research on abnormal climate in the Cenozoic era in China with evidence from marine profiles.

Abstract:

Xiangshan ore field in Jiangxi Province is a representative hydrothermal uranium ore field in China.Describing the evolution of uranium metallogenic hydrothermal fluid in Xiangshan ore field and exploring its formation mechanism is of great significance for promoting innovation and breakthroughs in the theory of hydrothermal ore deposit mineralization, and advancing the development of ore deposit studies.However, due to the lack of deep understanding of the mineralization stage and mineralization dynamics mechanism, the evolution of uranium metallogenic hydrothermal fluid in Xiangshan ore field has been a weak link in the study.This paper discusses the hydrothermal process from filling mineralization to metasomatism mineralization in Xiangshan ore field by redeveloping existing ore analysis data and re-observing the macro and micro phenomena, with hydraulic fracturing uranium mineralization as the main focus. The study shows that the main hydrothermal uranium veins in Xiangshan ore field are composed of filling type mineralization and metasomatism type mineralization.Filling type mineralization has high grade and small scale, with K₂O content of 0.88%~7.03% (average 4.03%) and Na₂O content of 0.12%~1.09% (average 0.35%), complex associated components, small apatite particles, and fast mineralization rate. Metamorphic type mineralization is low grade and widely distributed, with K₂O content of 0.09%~4.50% (average 1.15%), Na₂O content of 1.91%~10.01% (average 6.07%), few associated components, good crystallization of apatite, and slow mineralization rate. Uranium mineralization begins with filling type mineralization and ends with metasomatism type mineralization. The temperature of uranium mineralization does not change much, and the ore-forming pressure and redox potential show a gradual increase process. The ore-forming hydrothermal fluid evolves towards an increase in alkalinity.

Abstract:

The Boluositanmiao Complex in the eastern part of the Alxa Block, is one of the high-grade metamorphic complexes, which has important geological significance for the late Paleozoic tectonic evolution of the Alxa Block. In this paper, a combined study of detailed geological investigation, petrography, LA-ICP-MS monazite U-Pb dating and phase equilibrium modeling, were carried out for felsic gneisses of the Boluositanmiao Complex, which is used to reveal their metamorphic evolution and tectonic implications. Felsic gneisses are mainly composed of garnet-bearing biotite-plagioclase gneiss and biotite-plagioclase gneiss. The garnet-bearing biotite-plagioclase gneiss samples ALS2202 and ALS2204 record peak mineral assemblage of garnet+biotite+muscovite+ilmenite+plagioclase+K-feldspar+quartz+melt. Combined with phase equilibrium modeling, the peak p-t conditions of two samples were constrained at 727~751℃/820~1 030 MPa and 730~751℃/930~1 070 MPa, respectively. In addition, the garnet-biotite-plagioclase-quartz (GBPQ) geothermobarometry yields relatively low metamorphic p-t conditions of 629~672℃/410~490 MPa and 620~657℃/330~400 MPa, which correspond to the retrograde cooling. Based on the above results, a clockwise p-t evolution was obtained for the garnet-bearing biotite-plagioclase gneiss samples ALS2202 and ALS2204. LA-ICP-MS monazite U-Pb analyses obtained the weighted mean ²⁰⁶Pb/²³⁸U ages of 268±4 Ma and 255±2 Ma for the garnet-bearing biotite-plagioclase gneiss sample ALS2207 and the biotite-plagioclase gneiss sample ALS2210, respectively, which may represent the timing of peak metamorphism or anatexis. Based on the mineral assemblage, it suggests that the protolith of these felsic gneisses should be sedimentary rocks. Combined with the clockwise p-t path and previously published data in the region, this indicates a significant crustal thickening process in the middle and late Permian, which may be related to the closure of the Paleo-Asian Ocean.

Abstract:

The Longshan Complex located in the Qinling-Qilian junction zone is the key to understanding the tectonic evolution of this junction. This study conducted petrographic observations, phase equilibrium modeling and monazite U-Pb dating, to better discuss the tectonic implication. Based on petrographical observation and mineral composition analysis, the garnet biotite plagioclase gneisses sample 21LS30-1 of the Longshan Complex display two metamorphic mineral assemblages: the prograde stage (M₁) (biotite + plagioclase + quartz + rutile + ilmenite) and the peak stage (M₂) (biotite + garnet + plagioclase + quartz + rutile + ilmenite + melt). Sample 21LS37 exhibits two sets of metamorphic minerals during different formation stages: the prograde stage (M₁) (biotite+sillimanite+plagioclase+quartz) and the peak stage (M₂) (biotite+sillimanite+garnet+K-feldspar+plagioclase+quartz+ilmenite+melt). Phase equilibrium modeling constrained the peak p-t conditions of the two samples to be 813~821℃, 1.08~1.1 GPa and 815~819℃, 0.93~0.97 GPa, reaching the medium-pressure granulites facies metamorphism. LA-ICP-MS monazite data from the garnet biotite plagioclase gneisses show ²⁰⁶Pb/²³⁸U ages of 451~425 Ma, 455~431 Ma, 415~395 Ma and 415~394 Ma, respectively. The Longshan Complex and the North Qinling Orogenic Belt underwent similar tectonic processes during the Paleozoic. We preliminarily proposed that the Longshan Complex belongs to the western extension of the North Qinling orogenic belt and has experienced Paleozoic continental-continental collisional orogeny.

Abstract:

The Hongshangou porphyry copper-gold deposit is a typical deposit in the Hongshan polymetallic metallogenic area. It is located in the Wu'an depression of Shanxi fault uplift in the southern margin of the central North China Craton. The ore body mainly occurs in the Hongshan syenite porphyry. Muscovite and chlorite are well developed in the mineralization center and periphery. In order to discuss the diagenesis and mineralization significance of muscovite and chlorite in Hongshangou copper-gold deposit, electron probe microanalysis (EPMA) was used to analyze muscovite and chlorite in different occurrences and metallogenic stages of the deposit. The results show that the distribution characteristics of chlorite in the mining area can be divided into three categories: chlorite associated with metal minerals (Chl-1), chlorite altered from hornblende (Chl-2) and chlorite altered from biotite (Chl-3). The three chlorites are all Fe chlorites, indicating that they were formed in a reducing environment. The replacement of Fe to Mg and the replacement of Si to Al^Ⅳ in the structure indicate that the formation of chlorites is affected by Fe- and Mg-rich ore-forming fluids. The formation temperature of chlorite calculated by geological thermometer is between 112~272℃, which belongs to the range of medium-low temperature hydrothermal alteration, LA-ICP-MS results show that the completely altered chlorite is richer in Cu, Sn, Rb, Zn, Ti, Li, Sr, V, Co, Ni and Sn. Muscovite mainly includes primary muscovite (Ms-1) and secondary muscovite (Ms-2), which belong to ordinary muscovite and polysilicic muscovite respectively. The muscovite closely related to mineralization has the characteristics of high Si, Fe and low Al, LA-ICP-MS results show that the muscovite formed in the reducing environment is richer in V and W than the muscovite formed in the oxidizing environment, suggesting the mixing of meteoric water in the later stage of the fluid. Based on the research results of this paper, the ore-forming fluid of Hongshangou copper-gold deposit is acidic in the early stage and gradually changes to neutral in the later stage. The ore-forming environment of copper-gold deposit is near neutral and reduced medium-low temperature environment. The ore-forming fluid is rich in Fe, Mg and poor in Si.

Abstract:

In order to find out the distribution characteristics of rare elements, the genesis of pegmatite and deep prospecting potential of Lijiagou spodumene deposit in Jinchuan County, Sichuan Province, statistical analysis of rare elements from ore-bearing pegmatite, barren pegmatite and wall rock in exploration trenches and drill holes on No.2, 5, 9 and 11 from exploration lines from east to west in the largest No.Ⅰ vein of Lijiagou spodumene deposit, and in situ crystallization simulation calculation was conducted on the Ke'eryin two-mica granite and the ore-bearing pegmatite of No.Ⅰ vein. The analysis results show that the main rare element in No.Ⅰ vein is Li, accompanied with Be, Rb, Sn, Nb and Ta, which have similar characteristics to the rare element in the Jiajika X03 vein. The metallogenetic elements distribution regularity of the No.Ⅰ vein from top to bottom is that Li is enriched in the upper part, Be is enriched in the middle part, Nb and Rb are enriched in the lower part, while Nb and Rb in the Jiajika X03 vein are relatively enriched in the upper part of the ore body. The in situ crystallization simulation calculation indicated that the No.Ⅰ vein of Lijiagou was not formed by crystallization differentiation of a set of magma systems that formed Ke'eryin two-mica granite. The petrogenesis mechanism of the pegmatite of Lijiagou spodumene deposit may be that the first step is the low degree partial melting of the metamorphic sedimentary rock to generate relatively Li rich melt, followed by further enrichment of the melt through crystallization differentiation to form Li saturated melt, and finally crystallization to form spodumene pegmatite.

Abstract:

Niobium is a rare metal and strategic resource that plays an important role in modern industry. The Bayan Obo Nb-REE-Fe deposit is a super-large niobium deposit with 2.2 Mt Nb₂O₅ resources at an average grade of 0.13%. Therefore, it is very important to find out the occurrence and distribution characteristics of niobium. The niobium mineral in the Bayan Obo deposit has the features of fine, scattered and thin, which is difficult to find by polarizing microscope, so it is impossible to achieve the research purpose. On the basis of petrography and EDS analysis, the occurrence and distribution characteristics of niobium in deep aegirine-rich Nb-REE-Fe ores in the Bayan Obo main mine were studied by means of AMICS and EPMA. The results show that the average content of Nb₂O₅ in the ores is 0.15%. Niobium mainly occurs in columbite, pyrochlore, aeschynite, baotite and ilmenorutile, the total mineral content of 5 niobium minerals in aegirine-rich ores is 0.40%. The particle size of niobium mineral is fine, < 90 μm accounts for more than 88.16%, and it is a subhedral or anhedral grain. The results of EPMA show that the average content of Nb₂O₅ in columbite, pyrochlore, aeschynite, baotite and ilmenorutile is 73.46%, 63.42%, 28.43%, 16.03% and 15.81%, respectively. Niobium is mainly occurred in the form of independent niobium minerals, and a few occurred with other minerals in the form of isomorphism and inclusion. Niobium minerals are scattered and mainly distributed among aegirine, monazite and apatite or aegirine, barite and bastnäsite particles, often associated with aegirine, fluorite, monazite, bastnäsite, barite, apatite and other minerals. The chemical composition of niobium minerals is considerably complex, and the phenomenon of isomorphic substitution is common. The chemical formula of 5 kinds of niobium minerals is calculated and quite complex. There are obvious correlations between Nb and some elements in niobium minerals, and there are selective substitution of Ca²⁺ and Th⁴⁺ ions in aeschynite, this further indicates that complex isomorphic substitution of niobium minerals occurs during the formation process. Nb₂O₅ has the highest occupancy rate in pyrochlore and the lowest in baotite, the former is nearly 32 times of the latter. The total occupancy rate of 5 niobium minerals was 90.51%. Pyrochlore, columbite, ilmenorutile and aeschynite are the main industrial minerals for extracting niobium. This study provides a basis for the mineral processing of niobium in order to make full use of the niobium resources in Bayan Obo.

Abstract:

The newly discovered high-quality green jadeite in Guatemala is comparable to the high-end green jadeite from Myanmar, gradually becoming an important source of high-quality green jadeite jewelry materials in the domestic jewelry market. However, research on its petromineralogy and typomorphic characteristics remains relatively weak. This study selects a large number of Guatemalan high-quality green jadeite materials and jewelry that have appeared in the Chinese market as research subjects. Through microscopic observation, laser Raman spectroscopy, EMPA, and other testing methods, a systematic analysis of their mineral assemblages and compositional characteristics was conducted. The research findings indicate that the high-quality Guatemalan green "Mayan Green" jadeite materials appearing in the market are primarily composed of omphacite minerals, with secondary minerals including phlogopite, phengite, zoisite. Omphacite can be classified into three different formation stages, Omp-Ⅰ, II, and III, based on its mineral assemblages and their interrelationships. Among them, the high-quality Guatemalan green jadeite jewelry are mainly composed of omphacite formed in the Omp-Ⅲ stage, characterized by relatively low Mg (average 7.59%) and Fe (average 1.57%) contents, relatively high Cr content (average 0.24%), and a jadeite component X_jd>0.5 (average 0.53). Existing research indicates that the jadeites in different segments of the Motagua Fault System in Guatemala possess distinct mineral assemblages. However, the high-quality green jadeite jewellerys studied in this paper exhibit a relatively uniform mineral composition in the domestic market, primarily composed of pure omphacite. They may contain two specific metal mineral inclusions, chalcocite and nickeline. The endmember composition and mineralogical characteristics show significant differences compared to other sources of high-quality green jadeite, enabling effective differentiation between high-quality Guatemalan green jadeite, traditional Myanmar green jadeite, and high-quality green jadeite from other origins by providing essential reference characteristics in petrology and mineralogy.

Abstract:

The Manono region of the DRC is rich in pegmatite-type lithium, tin, niobium and tantalum resources. In the historical production process, only tin and niobium tantalum minerals were recovered, while lithium-containing minerals were discharged with tailings and stored until now. To determine the occurrence characteristics of lithium-containing minerals in tailings, the process mineralogy of lithium-containing minerals in tailings samples was studied by particle size analysis, X-ray fluorescence spectroscopy (XRF), chemical multi-element analysis, X-ray diffraction, scanning electron microscopy, and other comprehensively methods. The results indicate that the Li₂O grade of the lithium-containing tailings sample is 1.05%, and 95.04% of the lithium element in the ore is distributed in spodumene. The mineral content of spodumene in the raw tailing ore sample is 13.1%. Spodumene is mainly distributed in medium-coarse grains and has a simple association with other minerals, with low weathering degree. The Li₂O content in spodumene is 7.9%. Through the study of process mineralogy of lithium-containing minerals, it has been determined that the lithium-containing tailings belong to the spodumene-type (tailings) deposit, with good mineralogical indicators for mineral processing, providing a technical basis for the recovery of spodumene from tailings.

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:

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:

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 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:

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:

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:

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:

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:

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:

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:

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:

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:

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.