Abstract:World-recognized harmonious geochemical baselines data are used to quantify environmental changes and mineral resources. The China Geochemical Baselines (CGB) project, as a part of Global Geochemical Baselines, was implemented from 2008-2014. The China Geochemical Baselines Networks with approximately 1600 reference grids cover the whole China. 6617 soil samples from 3382 drainage catchments were collected across China's whole mainland. 81 geochemical parameters including 78 chemical elements plus other 5 indicators were determined. China geochemical baselines data and maps were produced across the whole China. The baselines data and maps of 76 elements have correlation with geology, mineral resources, climate and human activities.

Abstract:Based on regional stratigraphic correlation and using zircon dating method of tuff layer and andesite rocks in the Late Mesozoic stratigraphic sequence, the authors defined the key time of the sedimentary-fill record. According to the formation contact relationship and the geochemical characteristics of the andesite, the authors also analyzed the tectonic significance of the key geological interface. Some conclusions have been reached:(1) During the Early-Middle Jurassic, the sedimentary sequence was characterized by a suite of lake transgression sequence with the coal-bearing strata of Datong Formation, indicating the tectonic setting of the regional extension; (2) These strata had no sedimentary record from Late Jurassic (160.4±1.1 Ma) to Early Cretaceous (130.1±0.7 Ma), which was dynamically associated with far field effects produced by synchronous convergences toward the east Asia continent of different plates (Siberia, Paleo-Pacific, Tethys); (3) The andesite of Jiugaoshan was developed in the tectonic setting of the continental rift during the Early Cretaceous, which might have been associated with the destruction of the North China Craton. The andesite age of Jiugaoshan was defined in the study. It does not belong to the Tiaojiashan Formation, but corresponds to the Zhangjiakou Formation in Yanshan area.

Abstract:Tongling Scientific Drilling revealed that there exists a red syenogranite at 1775 meters below the surface in Shujiadian,Tongling,which has never been seen at the surface or in other drill holes of Tongling area before,and drilling about 700 meters still intersects the rock. Studies show that the syenogranite is characterized by higher content of SiO₂ and Na₂O+K₂O, and lower content of MgO, Ba and Sr, enrichment of HFSE (high field strength element) such as Zr, Nb, Y and LREE (light rare earth element) except Eu. The rock has a ratio of 10000Ga/Al>2.6,the total Zr+Nb+Ce+Y>350×10^-6, obvious Eu negative anomaly in the chondritenormalized REE patterns and depletion of Ba, Sr, P and Ti in the primitive mantle-normalized trace element diagram, showing Atype granite property. Zircon LA-MC-ICP-MS dating yielded a U-Pb age of 126 Ma for the A-type granite, which is consistent with the age of the other A-type granites in the middle and lower reaches of the Yangtze River (MLRYR), and belongs to the product of the second episode in the three episodes of the magmatism in the area. Researches indicate that the three episodes of magmatism in the MLRYR region had a closed relation to the multiple lithosphere delamination. With the continuing delamination, the deep magma chamber near the crust-mantle migrated to the shallow part, causing partial melting of the crust to form A-type granite when the magma was emplaced along the deep fault. It also marked a peak pull-apart in the tectonic background of the MLRYR region.

Abstract:Intermediate-acidic intrusive rocks are well developed in Shujiadian area of Tongling region. The intrusive rocks are mainly composed of Shujiadian rock body, Linjiachong rock body and several minor rock bodies around them. The intrusive rocks in the area can be divided into high-K calc-alkaline series and shoshonite series. In this study, the authors carried out LA-ICP-MS zircon U-Pb chronological research on the two main rock bodies. The results show that there existed multiple phases in the intermediate-acidic rock intrusion events in this area. The intrusion ages of the granodiorite porphyry, the pyroxene monzodiorite, the quartz monzodiorite, the granodiorite, the granite porphyry and the felsic vein are between 147.0 Ma and 146.9 Ma, 144.8 Ma, 141.0 Ma, 138.0 Ma, between 130.5 Ma and 124.0 Ma, and 129.4 Ma, respectively. On such basis, the authors consider that the intruding order of the intermediate-acidic magma in this area should be granodiorite porphyry→pyroxene monzodiorite→quartz monzodiorite→granodiorite→granite porphyry or felsic vein.

Abstract:Granitoid plutons are widespread in Gangou of Central Tianshan orogen. Previous studies of the augen granite and the fine-grained granite from north Gangou revealed that their SHRIMP U-Pb dating ages were 428 Ma and 361-368 Ma, respectively. Comparatively, zircon LA-ICP-MS U-Pb dating of the south granitoid pluton in this study yielded the ²⁰⁶Pb/²³⁸U age of 301±1.0 Ma. Major and trace elements show that the granites belong to high-K calc-alkaline series, and their σ=2.67-3.22. In addition, they are enriched in LREE, Rb, K, Th, La, Zr and Hf, and depleted in Ba, Sr, Nb, Ta, P and Ti. They show a transitional features from I-type to A-type. Compared with the Silurian-Devonian granites, late-Carboniferous granits are characterized by lower I_Sr values (0.704771-0.705451), higher ε_Nd(t) (2.14-2.51) and younger T_DM2 (861-891 Ma), suggesting that more new depleted mantel-derived materials contributed to the generation of the granites during post orogen. It is therefore held that the petrogenesis of the late-Carboniferous granites was related to the underplating of the mantle-derived magmas. This study also provides new evidence for Phanerozoic vertical continental crustal growth in the Central Asian orogenic belt.

Abstract:Pangushan granite is genetically related to the well-known Pangushan large-sized tungsten deposit. However, due to great depth, its petrologic and geochemical data had been lacking until it was discovered by the Nanling Scientific Drilling Project (SP-NLSD-2) recently. In this paper, the petrologic and geochemical study conducted by the authors is reported. The granite is found to be ultra-acidic, alkali-rich, Na-poor, K-rich, meta- to weak-peraluminous and K-high calc-alkaline. Its corresponding granitic magma is highly evolved and W and Bi values are significantly higher than their average values in Yanshanian granite in Nanling region, indicating that they were the major ore-forming material source. When the granitic magma was evolved to the greisenization stage, Mo, Bi, Cu, Pb and REE were enriched, while W and Sn were depleted because of their migration into the hydrothermal solution. The intrusion of the Pangushan granite happened during intraplate extension.

Abstract:In this study, the correlation method of structural factors and structural analysis were used to determine the formation mechanism of NNE-trending strike-slip faults in the Tazhong Uplift. The interpretation of 2D and 3D seismic data revealed deformation characteristics of the NNE-striking faults and determined their formation mechanism. NNE-trending strike-slip faults exhibit vertical superposition of compresso-shear faults and tenso-shear faults in seismic profiles. They have experienced two stages of activities:the late Ordovician compresso-shear faulting and the late Silurian-middle Devonian tenso-shear faulting. The formation of the NNE-trending strike-slip faults was controlled by the pre-existing basement weak zone and the evolution of the orogenic belts around Tarim plate. At the end of Middle Ordovician, a NS-trending compressive stress was generated by the subduction and closure of the ocean basin on the south margin of Tarim plate, and it acted on the NE-trending basement weak zone, resulting in the formation of NNE-trending strike-slip faults.Meanwhile, the compressive stress from the northwest margin of Tarim plate vertically acted on the NNE-striking strike-slip fault, leading to the compresso-shear deformation. In late Silurianmiddle Devonian period, the NS-trending compressive stress continually acted on the strike-slip faults, resulting in continued strike-slip deformation. Moreover, the extensional stress from the northwest margin of Tarim plate vertically acted on the NNEstriking strike-slip fault, leading to the tenso-shar deformation.

Abstract:Nanling scientific drilling(NLSD-1)is located at the junction of Yudu-Ningdu-Xingguo county in Jiangxi Province. Tectonically,the hole site of NLSD-1 is located at the intersection of Wuyi and Luoxiao block inside the Cathaysian plate. NLSD-1 aims at solving the scientific problems of regional geology and metallogenic regularity in the ore concentration area. The NLSD-1 hole intersects Qingbaikouan strata at 1373.71 m which are composed of a rhythm layer of tuffaceous volcanic clastic rock consisting of tuffaceous siltstone, tuffaceous sandstone, variable tuff, tuffaceous slate and rhyolite. Based on detailed geological logging and identification of different kinds of lithostratigraphy under microscope, the authors selected zircons from the rhyolite of NLSD-1. A set of high harmonic isotopic ages were obtained by using LA-ICP-MS, which can be used to make sure that the formation age of rhyolite is 381 Ma. This datum provides new information for the further division, assignment and study of geological evolution of stratigraphic age of Late Proterozoic in the middle south area of Jiangxi Province.

Abstract:Based on geological research on different regions of South China, different types of mineral deposits and different kinds of production mine enterprises from 1988 to 2016, the author tentatively discusses some key problems concerning deep exploration of mineral resources in such aspects as the target, the theory, the depth, the extent and the efficiency. Under the current technical and economic conditions, the author puts forward some suggestions:firstly, considering the national goal, scientific objectives and personnel, it is necessary to be flexible in the use of various metallogenic theories, to fully use the "Five levels+Basement" exploration model, and to take the potential bedded orebody and layered ore-bearing geological body as the main target in deep exploration of mineral resources. Secondly, according to the principle'from the known to the unknown and from the shallow to the deep', it is necessary to work in the mining areas especially in the orefields and/or ore concentration areas with relatively high degree of shallow geological work and relatively clear understanding of metallogeny, which can reduce the risk and can meet the practical needs. Thirdly, it is necessary to adhere to the principle that the 2000 m, 3000 m 5000 m deep drilling should be deployed in ore deposits, orefields and ore-concentration areas which have the highest degree of favorable geology and prospect so as to achieve the purpose of exploration. Fourthly, it is necessary to adhere to the principle of comprehensive evaluation, comprehensive survey, comprehensive evaluation and comprehensive study, paying attention to the reasonable probing depth and seizing key problem of deep exploration, so as to avoid the rash advance based on single subject of rash. Only in this way can good results be achieved.

Abstract:The Rongna copper deposit is a major exploring breakthrough of Chinalco Resources Corporation in recent years. The Rongna deposit is located in northern island arc of Bangong Co-Nujiang suture zone. Based on geological data of regional geological and mineral survey, 1:50000 magnetic anomaly, and distribution pattern of global porphyry copper deposits, the authors delineated the exploring potential zone in Duolong. According to 1:50000 stream sediment survey and other exploring achievements, Rongna and Naruo deposits were chosen as major exploring targets. Induced polarization survey was conducted as an effective method for delineating the drilling area by summarizing alteration, mineralization and exploration modes of global porphyry copper deposits. Two different geophysical anomaly patterns are generally displayed for the buried porphyry system in plan view:(1) the center of buried porphyry system generally develops the low resistance, moderate polarization, and negative magnetic anomaly, and (2) the pyrite shell surrounding porphyry system forms medium to high resistance, medium to high polarization, and positive magnetic anomaly. The authors infer that medium-high polarization and positive-magnetic anomaly developed surrounding the periphery of the Rongna deposit was triggered by pyrite shell correlated with propylitization belt, whereas the medium polarization and negative magnetic anomaly is located at the center of the mineralization zone. Bonanza grade copper mineralization was achieved after operating reasonable drilling. The exploring procedure of Rongna from the theoretical thinking, geophysical and geochemical anomaly analysis at different scales for effective investment and drilling operation reflects the combination art of scientific research and industrial production.

Abstract:Nanling Scientific Drilling-1(NLSD-1) is the deepest drilling engineering in South China ore concentration. The total drilling depth is 2967.83 m. 120 gold, silver, lead and zinc, bismuth, tungsten and uranium mineralization spots were exposed. Mineralization can be divided into fracture zone, siliceous vein type, quartz-feldspar vein type, which are produced in such forms as tracing detected very favorable industrial orebody potential. Vertical element mineralization regularity exhibits gold-silver-copper combination and lead-zinc combination. Bismuth anomaly is correlated significantly with the thiophile element mineralization. Precious metal mineralization anomalies are concentrated in nappe, whereas tungsten, tin and uranium mineralization tends to increase toward the depth, with both having specialization in lithological strata, tectonics and magmatic rocks in the borehole. According to uncovered information of vertical mineralization regularity revealed by NLSD-1 in combination with regional metallogenic regularity, the authors propose four prospecting directions:(1)V10-V31 in the nappe that extends to the east and to the depth; (2)Tungsten-tin polymetallic mineralization under the nappe; (3)Three deep spatial positions where thick orebodies may occur; (4)Porphyry-explosion breccia type mineralization in the periphery of Gaoshanjiao Hill-Bijia Hill.

Abstract:Dayishan granite is controlled by the Dayishan NW-trending tenso-shear fault structure, with the multiple intrusion characteristics, and the main mineral deposits related to the granite are tin-polymetallic deposits. There are three types of tin deposits in this prospecting area, i.e., altered greisen vein type, granite type and skarn type. The greisen veins of Baishaziling ore block in the planar alignments exhibit oval distribution on a flat, and the length, thickness and quality of veins taper from the middle part outwards, and so does the single vein. The veins at both ends of roof and floor present opposite scratches, and hence it is concluded that there is an oval concealed mother rock body, with its top forming the granite type. For this study the authors conducted tunnel deep drilling, with rich tin orebody of granite type seen in the upper part, and tungsten orebody seen in the lower part. The authors predict that the deep ore exploration has good prospect.

Abstract:The Louli gold deposit is located on the northern side of Hongshan alkalic complex, and the host rock of the orebody is the volcanic tufa. This is the first ore deposit of such type found in volcanic tufa in the southern segment of the Taihang Mountain, and its metallogenic regularity and deep metallogenic prospect evaluation are of guiding significance for delineating potential prospective areas and increasing mineral resources. Based on the regional mineralization regularity and geological characteristics, the authors systematically collected rock samples in 2 drill holes, and used Gregorians zonality index method and generalized contrast value method to compute and determine vertical zoning sequence of indicator elements. The results show that different calculation methods may produce somewhat different element orders, but the active stages of hydrothermal fluid and spatial superposition mode of halos are identical. The computed result of two drill holes shows the obvious coexistence of frontal halo and tail halo and axial zoning characteristics. The active process of hydrothermal fluid was analyzed based on the trace elements geochemical parameter axial variation. The results obtained show that the vertical zoning of two drill holes are made up of two stage hydrothermal circulation, suggesting that the formation of gold deposit is of multi-stage characteristics.

Abstract:The Nanling Scientific Drilling-1 (SP-NLSD-1), a subproject of the SinoProbe Program called "Deep Exploration Technology and Experimentation", is situated at the Yinkeng orefield in the junction of Nanling and Wuyi Mountain metallogenic belts. The drilling project, with footage of 2967.83 meters, revealed rhyolite, granodiorite porphyry, granite porphyry and pyroxene diorite porphyry. The magmatic rocks are mainly composed of quartz, plagioclase, potassium feldspar, biotite, amphibole and some accessory minerals, with chloritization, carbonatization and muscovitization. Potassium feldspar is dominated by orthose. Plagioclases are different in granodiorite and granite porphyry. Andesines and albites are dominant in granodiorite porphyry and granite porphyry, respectively. Most of the biotites are eastonites. Derived from biotites, muscovites in granodiorite porphyry have low Al^VI and Fe/(Fe+Mg) values, while muscovites in granite porphyry have high values. Apatites are rich in F and Cl, and garnet belongs to grossularite. Chlorites are prochlorites and pycnochlorites. The chemical composition of biotite suggests that granodiorite porphyry was formed by magma derived from mixture of crust and mantle with relatively high oxygen fugacity, and had undergone magma mixing during the evolution. Granodiorite porphyry, granite porphyry, and pyroxene diorite porphyry crystallized at temperatures of 810-922℃, 764-819℃, 742-747℃, respectively. Comprehensive study suggests that granodiorite porphyry exposed in the Nanling Scientific Drill Hole is similar to granites related to Cu(-Mo)-Pb-Zn-Au-Ag deposits in Nanling region. The granodiorite porphyry is the ore-forming magmatite of Ag-Au-Pb-Zn-Cu mineralization and Niuxingba-Liumukeng deposit. The relationship between W-Bi-U mineralization and magmatism needs further research.

Abstract:Aeromagnetic survey △T maps clearly show that there are two SN-trending aeromagnetic anomaly zones along the Yarlung-Zangbo suture zone, and geological researches have confirmed that the ophiolite rock masses along the Yarlung-Zangbo suture zone extend nearly 2000 km in banded distribution and in ES direction; however, it has been known that the main chromiumcontaining ophiolite rock masses are distributed on the south bank of the Yarlung Zangbo River. There are discontinuously distributed chromium-containing ophiolite rock masses observed on the ground of Luobusha and Zedang, which have small sizes and whose geological study degree is relatively high. There is Xigaze rock mass outcropped westward on the ground, and there are huge rock masses, including Dangqiong, Purang, and Dongpo, further to the west. Aeromagnetic survey maps show that the rock masses, including Xigaze, Dongpo, Purang, and Dangqiong, are obviously consistent with aeromagnetic anomalies. Ground magnetic survey for the above rock masses accurately has determined the relationship between the known rock masses and the aeromagnetic anomalies, and the Luobusha and Zetang rock masses in the eastern section of the Yarlung Zangbo River belong to small rock masses within the negative anomaly range on the northern margin of the strong aeromagnetic anomaly in the south. The chromium-containing ophiolite rock masses along the river in the west are distributed discontinuously, exhibiting short banded or large three-dimensional masses; ground magnetic survey anomalies prominently reflect the unevenness of distribution of the ground magnetite rock masses, with strong serpentinization and strong magnetic anomaly on the margin of the rock masses (including surrounding rocks near rock masses), thus to accurately delimit the range of the rock masses. The aeromagnetic anomalies reflect that there are relatively enriched magnetic minerals in the rock masses; the magnetic minerals might come from the minerals containing such components as FeO, and Fe₂O₃ in the deep part, which upwelled to the upper crust with magma and formed Fe₃O₄ due to serpentinization, thus generating strong magnetism when the temperature was lower than 480℃. Inversion calculation shows that the magnetic bodies are within the depth range of 3-5 km; although the magnetite existing in the ophiolite rock masses and their surrounding rocks was not directly from mantle materials, the magma materials in the chromium- containing ophiolite rock masses were main material contributors to the magnetite. The distribution range of the magnetite roughly corresponds to the orecontaining ophiolite rock masses, thus the aeromagnetic and ground magnetic survey anomalies, together with such methods as magnetotelluric method and reflection seismic method, can yield the geophysical characteristics of the deep structure of the rock masses, in favor of delimiting prospective areas for ore prospecting.

Abstract:The Tibetan Plateau, which is made up of a number of terranes, has the world's most thick crust. There is a long-term dispute concerning crustal thickness across the Bangong-Nujiang suture (BNS) from the Lhasa terrane to the Qiangtang terrane. This paper mainly reports the result of the study of deep seismic reflection profile in this area. A clear reflection of Moho was detected, which reveals the change of crustal thickness from the Lhasa terrane to the Qiangtang terrane. Moho exhibits a sharp decrease of 6.2 km across the BNS and becomes 12.5 km shallower from the northernmost Lhasa terrane to the south Qiangtang terrane at 28 km north of the BNS. The viewpoint based on deep seismic reflection data denies previous understanding of a 20 km offset.

Abstract:The existence of magma pocket in the depth of Tengchong volcanic basin of Yunnan Province is a topic which has aroused much attention. Extensive studies have been conducted from many aspects but there still exist different opinions. It was previously inferred by the authors based on low-resistivity anomalies that, underneath the craters of Xiaokong Mountain, Dakong Mountain and Heikong Mountain, there is a low-resistivity magma pocket with a depth range of 13-30 km and sizes of 25 km (from east to west) by 30 km (from south to north), on the east of which is Dayingjiang Fault. Based on seismic reflection survey, gravity and aeromagnetic survey data, this paper further discusses other geophysical characteristics of the magma pocket. Because of volcanic eruption, not only local material depletion is present near the craters, but the magma pocket itself depletes magma material as well; after the filtering of local negative gravity anomaly of surficial volcano, the gravity upward continuation map shows a negative gravity anomaly corresponding to the low-resistivity body on the north of Dakong Mountain, which is closely related to the depletion of aqueous low-density material from magma pocket in molten state at high temperatures. The entire negative gravity anomaly corroborates the existence of low-resistivity magma pocket. The Tengchong Mazhan magma pocket has temperatures of 397-651℃, with a mean value of 527℃, so magnetic body is impossibly present at the main central place of the pocket. After processing of the aeromagnetic data to eliminate the influence of surficial volcanic rock, large strong magnetic anomaly was still found, close to low-resistivity body in size, and it is presumed that the magnetic anomaly is at the top of the magma pocket at a depth above 15 km; as magma pocket temperature decreases gradually, new magnetic mineral will be formed below 480℃; as a result, there appears relatively strong magnetic body at the top of the pocket with a similar range to that of the pocket. Only seismic reflection at shallow depths reveals clearly that the relatively continuous reflected wave interface is a reflection of the interface among shallow volcanic rock, aquifer and granite. The reflected wave velocity map exhibits a number of velocity zones relatively continuous in vertical direction, the reflection interface towards deep formation is very discontinuous, presumably because of multiple times of magma upwelling, variable eruption times and different magma components, so the inhomogeneity of magma pocket material gives a novel geophysical model, indicating that magma pocket components are uneven; although aqueous mineralized melt constitutes a generality of low resistivity, uneven temperature shows variation in components of magma at different periods; in the pathway of magma pocket going towards ground surface, the eastern granite is underlain by high-velocity low-temperature material; and between two large concealed granite plutons in the east and west of the Dayingjiang River fault zone deeply underneath Xiaokong Mountain, Dakong Mountain and Heikong Mountain, is the newest volcanic eruption pathway, which is a low-velocity pathway.

Abstract:In the past twenty years, more and more mineral deposits were discovered in basins. The traditional geochemical exploration methods are not effective in mineral exploration of concealed deposits in basins. Deep-penetrating geochemistry provides a new approach for exploration in basins. The case history studies from the concealed sandstone-type uranium deposit hosted in a sedimentary basin, the concealed Ag-polymetallic deposit in a volcanic basin, the concealed Cu-Ni deposit in a basin covered by metamorphic rocks and the concealed Au deposit covered by loess have led the authors to reach the following conclusions:(1) Uranium is converted to uranyl ions[UO₂]²⁺ under the oxidizing condition and is easy to migrate under the influence of groundwater movement along sandstone pore structure and tectonic fissures; the uranyl ions are absorbed on clay minerals after migrattion to earth's surface, because clay layers have a net negative charge, which needs to be balanced by interlayer cations; leaching of mobile forms of elements in soils and separation of fine-grained soils can be used to determine the orebodies; (2) The Yueyang Ag-polymetallic deposit was nearly formed in the same period as the volcanic rock; Ore-bearing fluid migrated to earth's surface along tectonic fissures in the formation process of the deposit; mobile forms of metals in ore-bearing fluid were absorbed on clay minerals; leaching of mobile forms of elements in soils and separation of fine-grained soils can be used to determine the orebodies in volcanic basins; anomalies of elements are directly displayed over the blind orebodies; (3) the contact zone between intrusive mass and metamorphic rock generated a lot of tectonic fissures in the process of emplacement of the ultrabasic intrusion; and the fluid would take ore-forming elements Cu and Ni and migrate to earth's surface and form cyclic anomaly; (4) ore-forming elements Au and Ag in the form of complexes, nano-scale elemental or alloy particles taken by fluid migrated upward in the oreforming process of Au deposits in Luoning basin; compound or nanoparticles which dissociated from orebodies or rocks could penetrate loess pores and migrated upward to earth's surface and were absorbed on clay minerals; separation of fine-grained soils can be used to determine the orebodies. In this paper, the authors built deep-penetrating geochemical models for mineral deposits in basins based on application effects, anomaly shapes, characteristics of the covers, occurrences of the ore-forming elements, and migration patterns. The above results will provide theoretical and technical support for geochemical exploration in basins.

Abstract:The Donggualin gold deposit is located in the Zhenyuan gold orefield of the Ailaoshan gold ore belt. Based on field investigation, the authors figured out the prospecting criteria of trace elements by multivariate statistical methods and, in combination with geochemical parameters information, counted out the axial zonation of the ore deposit, built the ideal zoning model of the primary superimposed halos, constructed criteria for evaluating the ore potential in depth and clearly indicated the orientation in search for deep orebodies. Some conclusions have been reached:(1)The ore-forming element Au is close to elements Ni, Co, Cu, Mn, Sb, Sn, and the axial zonation of the ore deposit from top to bottom is As-Bi-Mn-Pb-Sb-B-Sn-Cu-Co-Hg-Ni-Zn-Au-Ag-Mo. (2) The front halo elements and the rear halo elements are existent together, suggesting that the orebodies extend in the deeper place; furthermore, deep ore prospecting should be carried out in the NE direction of the ore bodies. (3) Indexes such as(B×As×Hg×Sb)_D/(Mn×Ni×Co×Sn)_D can be used to predict the ore potentials in the deep portions of the orebodies.

Abstract:This paper deals with the in-site real-time fluid analysis in the drill hole WFSD-4S. The abnormal fluid during the earthquake was discussed after excluding the influence of chemical reaction affected by mud additives and anomaly characteristics caused by lithologic changes. The research shows that two strong earthquakes were accompanied by abnormal occurrence of Rn, Ar, N₂ and O₂ in WFSD-4S. What deserves attention is the daily average concentrations of radon were over 2.5 times higher than the background value. The mud gas yielded high concentrations above Principal Slip Zone (PSZ) in 931 m,which should appear in 1084m through the lithology investigation. It is inferred that the underground gas migration channel was opened and gas migrated upward because of the earthquake preparation process, which resulted in anticipating the response characteristics of fault gases.

Abstract:The age and genesis of plagiogranite in Karamaili ophiolitic melange of Xinjiang are still in controversy. In this study, the geochemical characteristics and LA-ICP-MS zircon U-Pb ages of the plagiogranite were determined. It is found that the rare earth and trace element characteristics of plagiogranite in east Qingshui are different from those of plagiogranite and cumulate gabbro in ophiolite, but are similar to those of massive gabbro. The geochemical characteristics of plagiogranite in east Qingshui and massive gabbro also show partial melting trend. The age of plagiogranite in east Qingshui is(342.0±3.8)Ma, suggesting that it was probably the product of post-collisional tectono-thermal event in early Carboniferous rather than the leucocrate in ophiolite.

Abstract:Magmatism is regarded as the deep response to the subduction and collision and also a petroprobe to explore the deep process. The Tuluyin area lies in the east of East Kunlun orogenic belt (EKOB), close to the south of the middle fault of EKOB. Based on detailed field investigation, the authors studied the petrology, geochemistry and geochronology of Tuluyin granitoids. Geochemical composition shows that Tuluyin granitoids are lithologically dominated by granodiorite. The SiO₂ varies from 68.49% to 70.87%. The total alkali content is in the range of 5.94%~7.16%, and the K₂O/Na₂O ratios vary from 0.34 to 0.57. Mg^# values are medium in granitoids (35.92-41.86). The A/CNK values (1-1.07) are lower than 1.1, showing that they belong to slightlyperaluminous calc-alkaline I-type granites. The rocks are enriched in light RRE (LRRE) with a flat heavy RRE (HRRE) pattern. There are no or weak negative Eu anomalies. The ratios of (La/Yb)_N are in the range of 4.17-9.14, with the total REE content varying from 118.91×10^-6 to 143.97×10^-6. The rocks are enriched in large ion lithophile elements (Rb, Th, Ba) and depleted in high field strength elements (Nb, Ta, P, Ti). LA-ICP-MS zircon U-Pb dating shows a crystallization age of 245 Ma, identical with the age of Xiadeboli and Aikengdelesite granitoids, suggesting that they all belong to the Early Indosinian period. Geochemical characteristics indicate that these rocks were derived from partial melting of the crust, with the addition of mass and heat flow from the mantle. Based on the existing geochronologic, geochemical and geological data, the authors hold that Tuluyin granitoids were formed under a background of the Anyemaqen-Paleo-Tethys Oceanic crust subducted into EKOB.

Abstract:Tuchengzi Formation is a widely distributed continental sedimentary stratum in northern Hebei and western Liaoning provinces. Since the 1980s, the stratigraphic age of this formation has attracted much attention and aroused heated debate among researchers. Through LA-ICP-MS U-Pb dating of zircons, the authors obtained two early Late Jurassic ages of this formation in Qianjiadian area. One of them is 157.6±0.7 Ma for the lower part, and the other is 157.1±1.0 Ma for the upper part. Combined with previous data, the ages of Tuchengzi Formation should be 163-130 Ma in the Yanshan area. During this period, Tuchengzi Formation showed mobility and intermittent sedimentary characteristics. The primary sedimentary ages of Yanshan area should be 146-137 Ma, and the contact relationship between Tiaojishan, Tuchengzi and Zhangjiakou formations are not in unconformity. The authors consider that they should be products of the same ectonic setting in most cases.

Abstract:The Northern Taihang Mountain is located in the central part of North China Carton, characterized by Mesozoic intermediate-acid magmatic rocks and plenty of important porphyry-skarn Cu-Mo deposits and hydrothernal gold deposits. A new Cu-W orebody within the Chiwawu granitoid was recently discovered in the southernmost part. The authors conducted field survey and zircon U-Pb dating of different granitic petrofacies from the Chiwawu Cu-W ore district, and then used the data obtained to constrain the timing and origin of granitc rocks. The Chiwawu pluton shows obviously textural and compositional variation from the inner part to the outer part, ranging from porphyritic granodiorite at the inner part, granodiorite at the transition part to quartz diorite at the periphery and several porphyry dykes. These new zircon LA-ICPMS U-Pb analyses of quartz diorite, granodiorite, porphyritic granodiorite and granodiorite porphyry dyke yielded excellent concordant ages of 134±1 Ma, 133±1 Ma,131±2 Ma and 128±1 Ma, respectively, indicating that the Chiwawu pluton was formed during the Early Cretaceous period (134-131 Ma). Combined with available chronologic data, the authors recognized two regional magmatic-metallogenic events during the Mesozoic time in Northern Taihang Mountain.

Abstract:Tugurige is a middle-sized gold deposit in Buyant Block, Inner Mongolia. The NW-striking gold-bearing quartz veins penetrate the Late Paleozoic rock mass and Lower Proterozoic Buyant Group. The orebody stably extends along the strike and the dip. The metallic minerals mainly include pyrite, chalcopyrite and galena, whereas the gangue minerals are predominately quartz and calcite. The alteration in the wall rocks includes silicification, sericitization and epidotization. The Re-Os dating of molybdenite samples from gold ore yielded a Re-Os isochron age of (305.6±4.5) Ma with an average of (313.5±4.8) Ma. This implies that the Au and Mo mineralization occurred in Late Carboniferous. The Re content of molybdenites in the Tugurige gold deposit is 42.42×10^-6-307.7×10^-6, suggesting that the ore-forming material was derived mainly from a mixed source of crust and mantle.

Abstract:Pb, Zn, Sn polymetallic anomalous zones of the Pulao area are situated in the Changshan ore-forming belt in northern Laos. 1:50000 stream sediment geochemical survey identified major anomalies of Pb and Sn, accompanied by other anomalies of Zn, Ag, W, Sb, Bi, As, Hg, Cu and Au. 1:10000 soil geochemical survey delineated 3 comprehensive anomalous zones of Pb, Zn and Sn, which are characterized by high intensity and big size with distinct concentration centers. Test of the anomalies gave rise to 13 Pb, Zn, Sn polymetallic ore spots. Based on study and analysis of geochemical distribution of elements in the anomalous zones and their anomalous features, the authors hold that the polymetallic anomalies are related to mineralization, with potential in search for Pb, Zn, Sn and polymetallic deposits in the area.

Abstract:There exist abundant Se-rich soil resources over 400 km² in the Yili area, Jiangsu Province, and a part of natural Se-rich rice has been produced in this area. By systematically studying and analyzing newly-obtained elemental geochemical data from the typical samples about rice seeds, soil, rock and soil solution related to Se-rich rice origin, this paper discusses the main controlling factors and geological environment or geochemical background for producing the natural Se-rich rice in the Yili area, and summarizes distribution and migration characteristics of some trace elements such as Se within rice as well as soil and rock. Some conclusions have been reached:(1) Se concentration in rice is significantly correlated to Se and TOC in soil, with the correlation coefficient (R) being 0.81. Detection rate of Se-rich rice is 100% when Se concentration is more than 0.5 mg/kg in soil; (2) Permian coal-bearing strata seem to be main primitive sources to form Se-rich soil, and the variegated argillaceous siltstone and shale within the strata are important Se-rich rocks, and the average Se concentration is 17.22 mg/kg in these rocks, which is more than 5 times higher than the average Se concentration in the local soil; and there are some obvious positive correlation between rock thickness and Se concentration in its overlying soil:where the sedimentary thickness of the Se-rich rock increases, the Se concentration is higher in the overlying soil layer; (3) The above-mentioned Se-rich rock formation includes a layer of iron and manganese nodule sediments lenticular in form, its thickness is about 5-30 cm, and there are abundant Fe, Mn, Cd, S, P and some other elements in the nodule sediments; the weathering and transferring process to form soil may contain a part of Cd, but the Cd that exceeds the value of the standard sample has not been yet detected in those relevant Se-rich rice seeds; (4) the available Se concentration is lower than 0.02 mg/kg in the cultivated soil, and the ratio of the available Se concentration to Se concentration is from 0.16% to 2% or so in the cultivated soil; and the most cultivated soils that enrich selenium are acidic, their pH values are between 4.6 and 6.5; the original Se-rich rocks are more acidic, with their pH values being generally between 4.2 and 5.5; (5) Se migration process is a series of continuous dilutions or homogeneous movements. Se-rich farmland distribution is influenced by the terrain, rainfall, fault belt and some other factors. The natural Se-rich farmland is formed in the small basin in hills, valley and piedmont plain with fault belts becoming the natural boundary of Se-rich farmland.

Abstract:The Shawan fault is one of the most important faults in Pearl River delta. To explain the Quaternary activity of Shawan fault, the authors conducted a series of work, such as 1:50000 geological mapping, chronological study, determination of radon, shallow seismic reflection and combined drilling verification. According to the analysis of Quaternary geomorphology and fracture coupling as well as the characteristics of historical seismic reflection, the fault is still active. Field survey and shallow seismic reflection show that the fault didn't cut Quaternary strata, and radon measurement also shows that the intensity of the fault activity is weak; ESR chronology shows that the activity intensity was relatively strong before late Pleistocene, and afterward it became weak; tectonic analysis of Luohanshan indicates that local area of Luohanshan was in a tension environment, but activity intensity has become weaker and weaker since late Holocene. In short, Shawan fault is still active, but the intensity is weak.

Abstract:The Sichuan-Gansu-Shaanxi border area has experienced many great earthquakes with complicated tectonic deformation and tectonic activities, which is the reason why this area is important for study of seismic risk. In order to better understand in-situ stress environment of Tianshui area and to evaluate the seismic risk, it is necessary to conduct deep borehole in-situ stress measurement. In this study, data were gathered from 9 in-situ stress sensors installed in deep borehole (600 m) in the southwest of Gangu County, Gansu Province and 14 in-situ stress sensors installed in deep borehole (400.12 m) at Sandui Town, Sichuan Province. The in-situ stress data reveal that the geostress level of the region is relatively high and both horizontal principal stresses in two tests are larger than the vertical stress (S_H >S_h >S_v). The direction of the current maximum horizontal principal stress is N41°E in Gangu borehole and is N85°W in Sandui borehole. The directions of the current maximum horizontal principal stress reflect that the present activity property of the north margin of west Qinling fault is thrust and sinistral slip, and that the present activity property of the Qingchuan fault is thrust and dextral slip. The activity of the north margin of west Qinling fault and the Qingchuan dault was analyzed by Coulomb friction sliding criterion, and the results reveal that the current in-situ stress levels have reached the critical condition of sliding instability. Based on the in-situ stress state and earthquake migration data, it is suggested that more attention should be paid to the Sichuan-Gansu-Shaanxi border area. The results obtained by the authors have great significance for analysis of active faults, long-term monitoring of in-situ stresses, assessment of the regional geological environment and geological disasters prevention.