Abstract:

The Luanjiagou borate deposit is located in the Paleoproterozoic Jiao-Liao-Ji orogenic/active belt of the North China Craton. The strata in the area are mainly the Lieryu Formation and the Gaojiayu Formation of the Proterozoic Liaohe Group. The tectonic framework is composed of a series of folds and faults. The magmatic rocks are not developed. There are more than 10 lenticular and lenticular ore bodies, and the wall rock alteration such as serpentinization and chloritization is widely developed. The typical structural features and tectonic systems of the Luangougou borate deposit are systematically studied by geomechanical method, the results showed that the direction of the principal compressive stress in the study area has evolved and transformed from northsouth compression to northwestwest-southeasteast compression-torsion. The mineralization tectonic evolution process can be divided into five stages: “sedimentation→metamorphism→fold-controlled mineralization→fracture-destructive mineralization→final shaping”. The analysis results of the tectonic-mineralization relationship show that the interlayer sliding zones developed in the core, two wings, and hinge zone of the overturned folds, as well as the structural void spaces such as fracture fracture zones and joint-fissure zones, provide key locations for the enrichment and emplacement of ore-forming materials and are favorable sites for borate mineralization. Based on the comprehensive tectonic evolution laws, structural ore-controlling characteristics, combined with orebody geological parameters such as orebody shape, thickness, and grade, the deep prospecting potential prediction was carried out. It is indicated that the area west of the 176 exploration line has good potential for borate resource replacement, and it is recommended to deploy drilling projects in this target area for deep resource verification.

Abstract:

In the Yecheng area of the southwestern Tarim Basin, the Well Yutang-1 encountered Nanhua System source rocks for the first time. The zircon ages of core samples were measured at 695±77 Ma and 794±79 Ma, corresponding to the bottom Bolong Formation of the Nanhua System. The total organic carbon (TOC) content ranges from 0.71% to 1.29%, with an average of 0.87%, representing a medium-quality source rock with certain hydrocarbon generation potential. The development and distribution of the source rocks were controlled by the rift trough that formed during the Nanhua Period. During the syn-rift stage, rapid subsidence coupled with a deep-water anoxic environment provided ideal conditions for source rock development, resulting in the deposition of thick succe-ssions of dark mudstone, shale, and marl, which laid the material foundation for forming medium- to high-quality source rocks. The organic matter is predominantly of sapropelic type with high hydrocarbon generation potential; however, due to prolonged deep burial, the thermal maturity is generally high, and the source rocks are mainly in the gas generation stage. The distribution of the source rocks is highly heterogeneous, controlled by the rift trough, and they are primarily enriched in the center of the depression. Together with the dolomite reservoir of the overlying Sinian Kezisuhumu Formation, they form a complete source-reservoir-caprock assemblage of the “lower source rock and upper reservoir” type. The rift trough profoundlly controls hydrocarbon generation-accumulation efficiency through the “trinity” mechanism consisting of syn-rift control source, post-rift thermal subsidence control heating, and late-stage tectonic activation control migration. This study provides important theoretical guidance and practical value for defining exploration directions in the deep ultra-deep Precambrian strata of the Tarim Basin and for selecting “sweet spot” areas.

Abstract:

Phosphorite-type uranium deposit represents one of the most important occurrences of global uranium resources. A large-scale uranium-bearing phosphorite has been discovered in the Yankong area of Jinsha, Guizhou, demonstrating significant uranium metallogenic potential. However, the co-existence mechanism of phosphorus and uranium in this area remains poorly understood. Therefore, this study selected three sections located near Yankong Subdistrict (Jinsha County, Bijie City), Minxing Subdistrict (Jinsha County, Bijie City), and Panshui Town (Zunyi City). Sixteen uranium-bearing phosphorite samples were systematically collected to conduct whole-rock major, trace, and rare earth element (REE) geochemical analyses, aiming to reconstruct the paleo-sedimentary environment and determine the material sources. Concurrently, to investigate the microscopic occurrence state of uranium within francolite (carbonate-fluorapatite) in the phosphorite, α-track etching, scanning electron microscopy (SEM), and electron probe microanalysis (EPMA) were employed. The results indicate that the samples exhibit high V/(V+Ni), U/Th, Ni/Co and V/Cr ratios, suggesting that the metallogenic period occurred in an extremely anoxic, sulfidic, and strongly reducing environment. The REE partitioning patterns display significant negative Ce anomalies, MREE enrichment, and weak positive Eu anomalies. Combined with the Zn-Ni-Co discrimination diagram, it is inferred that the metallogenic materials originated from a mixture of phosphorus-rich seawater brought by upwelling ocean currents and deep seafloor hydrothermal fluids. Uranium distribution within the francolite is non-uniform and shows a significant positive correlation with phosphorus. Most of the uranium enters the francolite crystal lattice through the isomorphous substitution of U⁴⁺ for Ca²⁺, while a minor portion exists as nanoscale inclusions on the surface of the apatite, achieving phosphorus-uranium co-existence. By studying the metallogenic environment, material sources, and microscopic occurrence states of uranium-bearing phosphorite in the study area, a three-stage metallogenic model consisting of “upwelling synergistic with seafloor hydrothermal injection supplying uranium and phosphorus—hydrothermal convective circulation enrichment—reducing environment precipitation mineralization" for the uranium-phosphorus co-existence deposit in the Yankong area has been established.

Abstract:

To clarify the spatial distribution characteristics of major potash minerals in low-grade solid potash ores and their implications for water-solution mining performance in the Bieletan mining area of the Qarhan Salt Lake, this study used drill core samples obtained from the 2022 reserve verification project. X-ray diffraction analysis was conducted, and chemical analysis data from both the general survey stage (1967 data) and the reserve verification stage were integrated to investigate the distribution patterns of major potash minerals, such as carnallite and polyhalite, as well as the variation characteristics of KCl content in the ore beds. The results show that halite is the overwhelmingly dominant mineral in the study area, while carnallite and polyhalite are the main potassium-bearing minerals, with the average content of polyhalite being higher than that of carnallite. Significant differences occur in the distribution of potash minerals between the upper and lower ore beds. Carnallite is mainly enriched in the northwestern part of the study area, whereas polyhalite is generally closely associated with carnallite and, in the southeastern part of the upper ore bed, shows spatial correlation with gypsum and clay minerals. Comparison between the general survey and reserve verification data indicates that, after large-scale solid-liquid conversion mining, the distribution of high-grade solid potash ores in the study area has become more dispersed. In the upper ore bed, the average KCl content has decreased and spatial dispersion has increased, whereas in the lower ore bed, KCl content has increased locally and its spatial distribution has become relatively smoother. Comprehensive analysis suggests that carnallite is the principal mineral preferentially dissolved during the solid-liquid conversion process, while the formation of polyhalite may be related to the mixing of K⁺- and Mg²⁺-rich brines released by dissolution with Ca²⁺- and SO^2-₄-rich brines or solvents. The results provide a geological basis for the efficient development, dynamic monitoring, and optimization of solution-mining engineering of low-grade solid potash ores in the Bieletan mining area.

Abstract:

The East Tianshan Bogda (back-arc rift basin) Cu-Zn-B-oil shale-P metallogenic belt possesses favorable metallogenic conditions for prospecting marine volcanic-type boron deposits. The Xixiertake-Yikedaban boron deposit of the study area is located in the central section of the Bogda mineralization belt. High-precision magnetic survey and rock-cutting geochemical profile surveys were carried out to analyze the effectiveness of integrated geophysical and geochemical prospecting information for mineral exploration， and explore an effective combination of exploration techniques for boron ore prospecting in the study area. As a result, one △T positive magnetic anomaly was identified in the area of Xixiertake-Yikedaban, and one large boron deposit was discovered. This indicates that the intergration of regional geological background with B₂O₃ geochemical anomalies, high-precision magnetic positive anomalies, and other geophysical and geochemical information has a good effect on the exploration and evaluation of marine volcanic rock-type boron deposits. This technical method can guide the exploration and prospecting of marine volcanic rock-type boron deposits in the East Tianshan Mountains.

Abstract:

The Quaternary strata in the Lop Nur region contain abundant brine resources. Through systematic analyses of the hydrochemical characteristics, hydrogen, oxygen and strontium isotopic compositions of brines from the Lop Nur and its surrounding areas, and comparison with the isotope data of the Lop Nur brines obtained in 1995, it is confirmed that the brines are mainly recharged by surrounding rivers. The sulfur and potassium components in the brine primarily originate from the Mesozoic-Cenozoic gypsum layers and glauberite deposits distributed in the southern Tianshan Mountains and the northwestern and southwestern margins of the Tarim Basin, as well as from ancient formation brines. During the Quaternary, the western Tarim Basin experienced uplift while the eastern Lop Nur area subsided. Surface water dissolved and carried these materials during flow, eventually converging in the Lop Nur depression. This process resulted in elevated background concentrations of potassium and sulfur in the regional water system, promoting potassium enrichment when the brine underwent evaporation and concentration to the glauberite precipitation stage. Comparison of hydrogen and oxygen isotope data with those from 1995 indicates that evaporation intensity in the Lop Nur region has continued to increase over the past three decades, suggesting an intensified trend of regional aridification.

Abstract:

A stratigraphically continuous marine sedimentary phosphorus-bearing rock series assemblage developed in the Early Cambrian of Dongchuan, Yunnan, provides an excellent carrier for mineralogical studies. This paper focuses on the Meishucunian phosphorus-bearing rock series in Bailongtan, Dongchuan, Yunnan, and conducts a systematic mineralogical study using optical microscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD). The results show that the minerals in the phosphorus-bearing rock series within the area are mainly authigenic minerals such as carbonate-fluorapatite, dolomite, and quartz, accompanied by more volcanic ash that shows a significant negative correlation with phosphorus content, with scarce terrigenous clastics and hydrothermal minerals mostly attributed to later hydrothermal filling. The sedimentary sequence of the phosphorus-bearing rock series completely record the sedimentary environmental evolution from transgression to regression. The formation of phosphorite is highly temporally coupled with the Meishucunian transgression event, indicating that the phosphorus-rich deep-sea water carried by upwelling currents during the transgression was the main phosphorus source. Carbonate fluorapatite mainly occurs within the shells of algae and small shelly fossils, and is almost absent in cements, revealing that phosphorus was enriched through the dense accumulation and burial of organic remains. In addition, the banded phosphorite has a P₂O₅ content of up to 32.90%, with a few micrometre-scale argillaceous laminae, and formed in a low-hydrodynamic-energy environment. In summary, under a transgressive setting, the phosphorus-rich deep-sea water carried by upwelling currents was the main phosphorus source for the phosphorite in the study area. The formation of phosphorite was dominated by biochemical processes, while cement content, detrital input, and hydrodynamic conditions constrained sedimentary preservation and ore grade. This study provides mineralogical constraints on the source of ore-forming materials and metallogenic theories for the Early Cambrian marine phosphorites in South China.

Abstract:

The long-debated palaeogeographic pattern of the Doushantuo Period in the northeastern Sichuan-western Hubei region has constrained the understanding of phosphorite metallogenic regularity and exploration planning in this area. To address this issue, this study focuses on the sandstones of the Doushantuo Formation in the northeastern Sichuan-western Hubei region. Through systematic analysis of detrital material sources employing methods such as detrital zircon U-Pb geochronology and lithofacies analysis, combined with seismic reflection profiles, we infer the existence of several small-scale palaeo-uplifts during the depositional period of the Doushantuo Formation. These palaeo-uplifts, composed of glacial diamictite of the Nantuo Formation and trending SW-NE, supplied detrital materials to their peripheries, resulting in the formation of the Doushantuo clastic rocks. Furthermore, based on the distribution of carbonate rocks and mudstones/shales, we deduce that several deep-water depositional areas representing rift troughs, also with a SW-NE trend, developed in the study area. Consequently, a new palaeogeographic framework characterized by an alternating pattern of “palaeo-uplifts and rift troughs” for the Doushantuo Period in the northeastern Sichuan-western Hubei region is proposed. Integrated with studies on phosphate distribution patterns, this study suggests that the carbonate platform margin around the aulacogen in the northeastern Sichuan- western Hubei region is the most favorable zone for phosphate enrichment. This conclusion provides a basis for the prediction of regional phosphate prospectivity.

Abstract:

The Cambrian Wusonggeer Formation in the Tarim Basin is a significant subsurface brine reservoir with substantial resource potential due to its enrichment in potassium. Based on an integrated analysis of thin-section petrography, X-ray diffraction, image logging, and comprehensive well-log interpretation, and combined with data from multiple wells and field sections in the northwestern Tarim Basin, this study systematically investigates the res- ervoir characteristics and their primary controlling factors of the Wusonggeer Formation. The results indicate that the formation developed various sedimentary microfacies, including dolomitic mud flat, dolomitic flat, bioclastic shoal, grain shoal, gypsum-bearing dolomitic flat, and mixed siliciclastic-carbonate dolomitic flat. The reservoirs are predominantly composed of algal-related grain dolostones, with a high grain content indicative of a grain-shoal sedimentary environment favorable for reservoir development. The reservoir spaces are diverse, encompassing intragranular pores, intergranular pores, intercrystalline pores, intercrystalline dissolution pores, and fractures. Fractures are notably well-developed in typical wells. Vertically, the reservoirs of the Wusonggeer Formation are concentrated in grain-shoal dolostone intervals with thicknesses ranging from 12 to 51 m, where porosity predominantly falls between 1.2% and 4.3%. Laterally, the Keping outcrop area exhibits locally enhanced porosity of 3% to 5% due to superimposed supergene dissolution, collectively defining a high-quality reservoir characterized by strong heterogeneity and a “fracture-vug” pore system. The fracture network provides effective conduits for fluid migration and is a key controlling factor for reservoir development. The new perspective of the Wusonggeer Formation as a potassium-rich brine reservoir challenges its traditional view primarily as a hydrocarbon reservoir or regional seal, thereby expanding its application potential in the field of potash salt mineralization in saline lake systems.

Abstract:

Phosphate rock is a critical strategic non-metallic mineral resource in China. Accurate delineation of deep concealed orebodies requires reducing the ambiguity of individual geophysical methods, which depends on understanding the intrinsic physical-property contrasts between phosphate-bearing strata and surrounding rocks. In this study, 392 core samples were collected from six boreholes in the Bailongtan and Laocunzi phosphate deposits, two representative deposits in the eastern Yunnan phosphogenic belt. Density, electrical resistivity, chargeability, magnetic susceptibility, and wave velocity were measured and integrated with quantitative whole-rock mineralogy determined by X-ray powder diffraction (XRD), establishing a multidimensional petrophysical response framework for concealed phosphate deposits. The phosphorite exhibits a distinctive combination of high density, extremely low resistivity, high chargeability, moderately low wave velocity, and weak magnetism. Its mean density, resistivity, and chargeability are 2.76 g/cm³, 245.40 Ω·m, and 3.67%, respectively. These properties differ significantly from those of the carbonate and clastic rocks in the roof and floor (p<0.001), producing pronounced gravity and electrical contrasts. Mineralogical and microstructural analyses indicate that abundant dense fluorapatite is primarily responsible for the high density. The coupled low-resistivity-high-chargeability response arises mainly from a conductive and electrical double-layer polarization network formed by fine-grained semiconductive pyrite preserved during diagenesis, residual organic matter, and highly mineralized pore fluids within micropores and fractures. Abundant primary pores and a weakly cemented framework account for the low wave velocity and strong attenuation of high-frequency acoustic waves. Finite-difference forward modeling using the measured geoelectrical parameters confirms that electrical resistivity tomography can penetrate the resistive overburden and reliably detect deep, low-resistivity ore layers. We therefore propose an integrated exploration strategy for concealed sedimentary phosphate deposits in eastern Yunnan: gravity surveying for regional screening and target delineation, electromagnetic methods for locating low-resistivity zones, induced polarization for identifying highly chargeable, high-grade orebodies, and seismic and magnetic methods for supplementary constraints. These results provide robust petrophysical evidence and a theoretical basis for exploring deep concealed phosphate resources in the region.

Abstract:

Characteristics and hydrogen-oxygen isotopic compositions of halite fluid inclusions in the Hongze sag of the Subei Basin were analyzed to reconstruct the paleoenvironment during salt formation and investigate the supply mechanisms of salt-forming materials. The results reveal that primary halite fluid inclusions in the fourth member of the Funing Formation from SB18 exhibit two distinct types: cumulate and chevron crystals, frequently coexisting within the same strata, indicating an shallow water environment during deposition. The hydrogen-oxygen isotopic composition of these fluid inclusions shows significant deviation from the meteoric water line, clustering in the lower right quadrant. Combined with homogenization temperature data and sedimentary sequences, this pattern reflects intense evaporative conditions during the salt formation process. The sources of salt-forming materials in ancient salt lakes mainly include the weathering and leaching of surface rocks, residual water from marine transgressions, and the lateral infiltration of seawater. Furthermore, the basin's unique “high mountain-deep basin” topography, developed under specific tectonic conditions, provided favorable paleo-environmental settings and accumulation spaces for the concentration of salt-forming materials.

Abstract:

The potential boron resources in the Laguo Co salt lake, Xizang, are immense. However, previous studies have primarily relied on geochemical and hydrogeological approaches focused on the lake's interior, resulting in a lack of understanding regarding the equally prospective solid boron-bearing sedimentary rocks on the lake margins and deep paleo-brines. Surface-to-borehole resistivity imaging has been widely applied in the exploration of brine-type minerals due to its ability to fully utilize boreholes, offering high vertical resolution and enhanced resolution of anomalies adjacent to the borehole. Although numerous arrays exist for this method, significant disparities in imaging effectiveness remain, and research regarding the influence of various surface-to-borehole observation parameters is currently insufficient. To address these issues, this study first established a geological-geophysical model of the periphery of Laguo Co salt lake based on field geological and hydrological data. By calculating the sensitivity of various surface-to-borehole arrays and performing inversion tests on theoretical model response data, the response characteristics of different observation arrays to deep boron-bearing brine layers were compared and analyzed. Furthermore, the influence of observation parameters—specifically the number of boreholes, in-borehole electrode spacing, and borehole casing material—on imaging resolution was investigated. The results indicate that a superimposed configuration comprising the Wenner array, BN-AM array, and A-MNB array can effectively recover the geometric dimensions, burial depth, and resistivity values of boron-bearing brine layers. In particular, the utilization of three boreholes penetrating the boron-bearing brine layer achieves superior imaging accuracy. Additionally, increasing the number of boreholes and reducing the in-borehole electrode spacing both enhance the resolution capability for boron-bearing brine layers. The imaging effect is optimal when the borehole is an open-hole completion.

Abstract:

The Paleogene period was a critical period of global climate transition. As a low-latitude inland basin, the Lanping Basin is located in the middle of the Tethys Ocean metallogenic belt, featuring diverse mineral species and abundant mineral resources. Currently, studies on the geochemical signatures and paleoclimate of this basin remain insufficient. The coupled evolution of tectonic activity and sediment supply during the Paleogene directly modulated paleoenvironmental frameworks and paleoclimatic evolutionary patterns, which bears great significance for constraining mineralization in this region. Taking the Paleogene clastic rocks of the Lanping Basin as the research object, through geochemical analysis of major elements, using weathering indices such as CIA and ICV and various structural-provenance discrimination charts, this paper systematically conducts research on Paleogene paleoenvironment and paleoclimate evolution, provenance attributes, and tectonic background in the source area. Results show that compared to PAAS, the major elements in the clastic rocks of the study area exhibit generally higher SiO₂ content, lower Al₂O₃ content, and significant differentiation in CaO, K₂O and Na₂O contents; Paleogene sources mainly come from the collision of the recycling orogenic belt; The tectonic background of the Yunlong Period was dominated by continental island arcs, with passive continental margin sources beginning to mix in during the Guolang Period, and completely transforming into passive continental margin by the Baoxiangsi Period; The chemical weathering effect of the Yunlong and Guolang Periods was weak, while the degree of weathering in the Baoxiangsi Period was significantly enhanced; The Paleogene climate evolved from arid conditions to a gradual transition between dry and wet climates, and finally to frequent seasonal dry-wet fluctuations under an overall arid background. The paleolake evolved from closed saline lake via semi-open alternating brackish-fresh lake to open freshwater fluvial-lacustrine facies. Co-evolution of paleoclimate, paleoenvironment, provenance and tectonics background supplies geochemical support for exploring metallogenic environment constraints on Yunlong Formation gypsum and Jinding Pb-Zn deposits.

Abstract:

The formation of Sr-rich mineral water in magmatic rock-fault systems cannot be attributed solely to leaching from a single lithology, but is jointly controlled by Sr-rich source rocks, fracture-flow systems, and hydrochemical conditions favorable for Sr preservation. Taking the Shilingxiu mineral-water source area in Xiahuayuan, Zhangjiakou, as a case study, this study integrates shallow geophysical surveys, hydrochemical and rock geochemical analyses, and hydrogeochemical modeling using the PHREEQC software to elucidate the role of the fault-syenite contact zone in controlling Sr release, migration, and enrichment. The results show that the upper 300 m of the study area contains a heterogeneous bedrock-fracture system composed of shallowly buried syenite, fractured andesite, Mg-type water in which Sr occurs predominantly as free Sr²⁺. Celestite is markedly undersaturated, indicating that the prevailing hydrochemical conditions favor the migration and preservation of Sr in dissolved form. Calcite is near equilibrium, whereas dolomite is supersaturated, suggesting that carbonate mineral precipitation may constrain further Sr enrichment. Syenite porphyry has an average Sr content of 764×10^-6 and represents an important potential source rock for groundwater Sr enrichment. Faulting controls the shallow burial of syenite, the distribution of contact zones, and fracture connectivity, thereby locally coupling silicate weathering, carbonate dissolution, and valley-controlled discharge boundaries. The Sr-rich mineral water in the Shilingxiu source area is therefore classified as low-temperature, leaching-derived bedrock-fracture groundwater controlled by the fault-syenite contact zone.

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.