Abstract:Abstract：Accompanied by hypabyssal emplacement of high-potassic alkali-rich porphyries, “paired” Cenozoic intracontinental porphyry copper-molybdenum-gold belts, controlled by large strike-slip faults, occurred on the eastern margin of the Qinghai-Tibet Plateau formed by India-Asia collision. Of the two metallogenic belts, the west belt is the Jomda-Markam-Xiangyun copper-molybdenum belt and the east belt is the Zhongdian-Yanyuan-Yao＇an porphyry copper-gold-lead-silver belt. The rock types of ore-bearing porphyry include granite porphyry, monzogranite porphyry and monzonite porphyry with small amount of syenite porphyry. They are distinguished from barren porphyry by their higher SiO2 (>63%) and lower Y (<20×10-6) and their adakitic magma affinity. Alkali-rich porphyry is relatively enriched in large-ion lithophile elements (K, Rb and Ba) and depleted in high-field strength elements (Nb, Ta, Ti and P) with a wider range of Nb/Y ratios and shows strong REE fractionation but no pronounced negative Eu anomaly—all these suggest that the magma source region underwent metasomatism and concentration of ancient subducted oceanic slab fluids and was injected by small streams of melts from the asthenosphere. Ore-bearing adakite-like porphyry might originate from the basaltic lower crust. The latter underwent high-pressure (>40 km) low amphibolite-eclogite facies metamorphism and slab fluid metasomatism and occurs as lower-crustal amphibolite xenoliths in alkali-rich porphyry. Barren syenite porphyry might originate from the hydrated phologopite peridotite-enriched mantle. Its trace element and Su-Nd-Pb isotope systematics indicate that their source region was subjected to much stronger slab fluid metasomatism and mixing of asthenospheric material. Available data of deep geophysical exploration suggest that since 50 Ma BP the Yangtze continental slab was subducted westwards and collided with the subducted Indian continental slab, thus inducing upwelling, thermal erosion and underplating of asthenospheric melts and giving rise to partial melting of the crust-mantle transition zone. The magma of adakite-like porphyry is characterized by the presence of relatively rich water, rich sulfur and higher oxygen fugacity (fo2). It was an important metal and sulfur carrier and formed porphyry copper-gold-lead-silver deposits in a shallow-level closed system.

Abstract:Abstract：The Paleogene Bohai Bay basin may be divided into three rift zones and one rift area, which correspond to the updoming zone of the upper mantle. The tectonic deformation in the basin may be classified into two relatively independent and interconnected Cenozoic tectonic systems: the extensional tectonic system and strike-slip tectonic system. The extensional tectonic system is a linked fault system formed by extensional faults of different scales and transform faults perpendicular or oblique to the extensional faults. In the basin they are dispersed and penetrate into the upper crust and control the distribution and evolution of the Paleogene rifting. Three NE-NNE right-lateral strike-slip faults are superposed on the extensional system. These strike-slip faults and their associated structural elements form the Cenozoic strike-slip tectonic system. The extensional system is a “horizontal layered” thin-skinned tectonics at the crustal scale. The normal faults converge toward great depths or terminate at the detachment fault surfaces within the mid-crust. The strike-slip system is a “vertical belt-like“ thick-skinned tectonics at the crust scale. The strike-slip faults at the shallow level of the crust are merged into the deep fault zones in several ways. The two tectonic systems are concrete manifestations of the active rifting and passive rifting mechanisms in the basin during the Cenozoic.

Abstract:Abstract： Based on TM image interpretation and field observations, this paper describes the geomorphological features of the deeply incised Daduhe and Anninghe River valleys in the Panxi region and analyses the late Cenozoic tectonic deformation features of the Anninghe fault zone. The late Cenozoic tectonic evolution of the Anninghe fault zone may be divided into 5 stages： late Miocene to early Pliocene, late Pliocene to early Pleistocene, early to middle Pleistocene, middle to late Pleistocene, and late Pleistocene to Holocene. The first stage mainly witnessed transpressional strike-slip faulting； in the second stage obliquely tensional strike-slip motion was dominant； the Yuanmou movement occurring in the third stage caused lacustrine strata of the Xigeda Formation to be folded； in the fourth stage normal faulting took place, forming the Anninghe graben-horst structure； in the fifth stage left-lateral strike-slip motion again predominated. Based on a morphostructural analysis of the deep incised valleys of the Daduhe and Anninghe Rivers, late Cenozoic stratigraphic records and deformation features, the authors propose a 4-stage uplift model for the late Cenozoic uplift history of the Panxi plateau： a stage of gentle uplift and regional peneplanation during the early to middle Miocene (before 12 Ma), a stage of fast uplift and deep valley incision during the late Miocene to early Pliocene (from 12 to 3.4 Ma), a stage of development of the Xigeda lake basin along the deeply incised river valleys during the late Pliocene to early Pleistocene (from 3.4 to 1.1 Ma), and finally a stage of fast uplift and development of river terraces during the mid to late Pleistocene. The Panxi plateau may have attained an elevation of more than 3 000 m above sea level by the late Pliocene (before 3.4 Ma).

Abstract:Abstract: The structural characteristics of the western Shandong mantle branch and its genetic mechanism are discussed according to the outward-younging ring distribution of the strata, ring faults and radial faults, gently dipping detachments and mantle-derived magmatism, as well as regional petrology, petrochemistry and isotope geology. These studies suggest that the NW-trending, steeply dipping ductile shear belt cuts deep-seated pyrolite of the mantle sub-plume beneath North China, resulting in depressurizing and load-releasing to form anatectic magma. The magmatic evolutionary series shows a general trend of evolution from high to low basicity of magma, from great to shallow depths of magmatic intrusion and from strong to weak wall-rock alteration. Strong magmatic intrusion resulted in the uplift of the metamorphic basement and detachment of the cover, thus forming the typical western Shandong mantle branch structure. A number of obviously detached, tilted fault blocks are developed on top of this mantle branch.

Abstract:Abstract：It was considered before that Cd can only limitedly substitute Zn in sphalerite in nature. However, in the recent study of the relationships between Cd and Zn in the Nujiaotang cadmium-zinc deposit, Guizhou, using the electron microprobe, scanning electron microscope and transmission electron microscope, the authors have found that Cd in zinc sulfide mainly exists as an isomorphous element with its content ranging from 0.8% to 37.93%, and that likewise Zn in cadmium sulfide also mainly exists as an isomorphous element with its content ranging from 2.43% to 38.64%. Zinc sulfide and cadmium sulfide show gradational relationship, and there is a good negative correlation between Zn and Cd with a correlation coefficient of > 0.99, forming a ZnS-CdS complete isomorphous series. This discovery has great theoretical significance and practical value not only in mineralogy but also in geochemistry and geology of mineral deposits.

Abstract:Abstract：The Middle Permian Maokou Formation is generally overlain by the Late Permian Emeishan basalts in eastern Yunnan and western Guizhou in the west of the Yangtze platform. It has long been taken for granted that there are no sedimentary breaks or erosion between the Maokou Formation and Emeishan basalts. On the basis of the field investigation and indoor integrated study, the authors present various evidence of the paleo-karst landforms on top of the Maokou Formation, including rugged ancient erosion surfaces, uvalas, dolines or holes, cone karst, tower karst and caves, as well as cave fillings and red soils on the ancient erosion surfaces, and suggest that paleo-karst landforms have great significance in the geological development in an area，which represent a crustal uplift. The systematic study of the paleo-karst not only enriches the content of the study of paleo-karst in China, but also affirms the existence of the Dongwu movement in Yunnan, and also provides important evidence for the activity of the Emeishan mantle plume.

Abstract:Abstract：On the basis of 1∶250 000 mapping of the Boindoi Sheet and Comai Sheet, the time-space structure and evolution of the arc-basin system on the southern side of the Bangong Co-Nujiang junction zone is analyzed by using the archipelagic arc orogeny model. The authors believe that during the Middle-Late Jurassic and Early Cretaceous an archipelagic arc-basin system formed on the southern side of the Bangong Co-Nujiang ocean concomitantly with its southward subduction and extinction, and that during the late Early Cretaceous to Late Cretaceous the arc-basin system evolution on the southern side of the Bangong Co-Nujiang junction zone ended through remnant sea basin sedimentation, closing and subduction, and subsequent collisional orogeny.

Abstract:Abstract：For lack of systematic isotopic study, the study of the origin of Yanshanian granitoids in eastern Inner Mongolia has been focused on their petrology and geochemistry, which leads to controversial views on the origin. There are mainly three views,all of which emphasize that the Yanshanian magmatic rocks originated from mixing of mantle and crust. The authors restudied the origin of the Yanshanian granitoids in the area by using the Nd, Sr and Pb isotope methods. The study shows that all the granitoids have positive εNd（t）values, ranging from +0.75 to +8.12 with an average of +3.07, which indicates that they are genetically associated with the depleted mantle. The whole-rock initial Sr ratios range from 0.7028 to 0.7096, with an average of 0.7063, being intermediately between that (0.702-0.706) of MORB (0.706-0.718) of continental crust, but close to that of MORB. The initial lead ratios of the granitoids are 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb, with their respective averages of 18.3742, 15.5500 and 38.1810, all of which are higher. The μ value calculated from the K-feldspar lead isotope ratios ranges from 9.51 to 8.91, which is lower than the isochronic evolution line (μ = 9.74) of the continent crust. Based on the above data, With Combination of the isotopic study of magmatic rocks in the Hinggan -Mongolia-northern Xinjiang region (a Late Paleozoic geosyncline) adjacent to the study area, the authors think that the Yanshanian granitic magma may have originated from partial melting of the depleted mantle and partial melting of the late Variscan paleo-Mongolian ocean crust derived from the depleted mantle in the area, i.e. the ultimate source of the Yanshanian granitic magma in the area is the depleted mantle. Therefore, a“three-step” evolutional model is brought forward, that is the evolution model of depleted mantle – the ancient Mongolian ocean crust – the marginal continental rejuvenation.

Abstract:Abstract：Volcanic rocks in the Upper Triassic Xiaodingxi Formation in the Shiden-Tue area belong to the Triassic volcanic belt along the banks of the Lancang River in western Yunnan. The author has made a systematical and comprehensive study of the petrographic, petrochemical and geochemical characteristics of the volcanic rocks and determines the tectonic environment of these rocks from a theoretical angle. The study shows that these volcanic rocks are composed dominantly of andesite with subordinate basalt, belonging to the calc-alkaline series, and formed in the island-arc tectonic environment.

Abstract:Abstract：The Nanjing area is a typical representative of the very thick Quaternary cover areas in the Yangtze River delta. This paper reports some basic results obtained since multi-target geochemical survey has been carried out in the area. Through experiments, some key technical criteria and requirements have been worked out and generalized. The authors think that it is feasible to take samples from topsoil at a depth of 0 to 20 cm and deep soil at a depth of ≤150 cm respectively, use the –20 mesh fraction of soil and adopt sampling densities of one sample per square kilometer for topsoil and one sample per 4 square kilometers for deep soil. Two belts polluted by some heavy metallic elements exist in topsoil in the Nanjing areas, and marked enrichment of heavy metallic elements in topsoil has direct influence on the safety of crops and vegetables in the study area. At last, the authors discuss a number of questions as to how to determine the geochemical background values in studied soils, how to examine and appraise environmental geochemical anomalies and how to treat the relationship between the total content of some elements and their effective concentrations in topsoil and so on, and propose relevant suggestions.

Abstract:Abstract：Stable isotope study indicates that the δ34S values of the Baguamiao gold deposit, Liba gold deposit and Xiaogouli gold deposit have a narrower range than those of sediment-hosted deposits and a wider range than those of magmatic or volcanic-hosted deposits. The sulfur was derived from mixing of the sulfur source of seawater sulfate reduction and the deep magmatic sulfur source. The δ18O and δD values of fluid inclusions fall in the overlapped, transitional field of magmatic water and meteoric water but are closer to the magmatic water field and show more pronounced isotopic features of magmatic water. The 3He/4He ratio of Au-bearing quartz veins is higher than that（n×10－8）of the crust and lower than that（n×10－5）of the mantle, implying a crust-mantle mixing source for He. The aforesaid isotope geochemical evidence indicates that there is a certain genetic relation between gold mineralization and magmatism. Magmatic rocks are spatially closely related to gold deposits. Dikes are well developed in the area. They act as the hanging walls and footwalls. The spots or stains in host rocks are thermometamorphic minerals and hydrothermal alteration minerals such as pyrite, pyrrhotite, arsenopyrite, chlorite, quartz, sericite, biotite, cordierite, andalusite, tourmaline and carbonates, indicating that granites provided thermodynamic forcing for mineralization. Based on the stable isotope geochemistry of the Baguamiao, Liba and Xiaogouli gold deposits, combined with the metallogenic environment and regional metallogenic characteristics, the authors suggest that gold deposits in the Fengtai-Xicheng-Limin area are notably different from finely disseminated (Carlin type) gold deposits in that the former are genetically similar to magmatic hydrothermal deposits.

Abstract:Abstract：Although mineralization in the Devonian lead-zinc-gold polymetallic metallogenic belt in Qinling is related to hydrothermal exhalation-sedimentation. The Zhashan area is distinguished from the Fengtai area in its having a distinctive copper metallogenic setting. REE geochemical studies of rocks and ores in the Mujiazhuang copper deposit show that the REE compositions and distribution patterns of disseminated lean copper ores and near-ore country rocks are essentially consistent, suggesting that the disseminated lean copper ores represent the product of primary concentration of hydrothermal sedimentary rocks with small amount of sulfide formed by the hydrothermal sedimentary event during the Devonian. During this period the primary source bed of the Mujiazhuang copper deposit formed. Laminated siliceous rocks in country rocks might represent the nature of the Devonian hydrothermal sedimentary rocks. The REE composition of massive rich ores represents the result of fluid hydrothermal activity resulting from extensive continent-continent collisional orogeny. The hydrothermal activity not only modified the primary source bed in situ but also may have brought part of ore substances from other places and deposited them; the deposit was then subjected to modification and concentration at the appropriate structural site. Mujiazhuang copper deposit should be of modified origin.

Abstract:Abstract：There are two types of gold orebody in the Shibaqinghao gold deposit：mylonite ore and quartz vein ore.The Pb isotopic composition for mylonite ore is characterized by lower Pb isotope ratios, with 206Pb/204Pb=16.63 to 17.45, 206Pb/204Pb=15.31 to15.48 and 206Pb/204Pb=36.52 to 38.85, and its lead dynamic evolution curve is very close to the model curve of the mantle lead evolution and consistent with the lead isotopic composition of the typical ductile shear zone gold deposit——the Houshihua gold deposit in the area. These suggest that gold in the mylonite ore might be derived from country rocks, and that the ore is the product of late Paleoproterozoic (2040 Ma) ductile shear metamorphism-deformation. The Pb isotopic composition of quartz vein ore is characterized by higher Pb isotope ratios, with 206Pb/204Pb=18.23 to 19.74, 206Pb/204Pb=15.69 to 15.89 and 206Pb/204Pb=38.64 to 40.13, and its lead dynamic evolution curve is very close to the model curve of the upper crust lead evolution and consistent with the lead isotopic composition of the typical Yangshanian magmatic-hydrothermal gold deposit——the Donghuofang gold deposit in the area, suggesting that it is magmatic-hydrothermal gold mineralization. The Donghuofang gold deposit resulted from overlapping of two mineralizations of different natures. This supports the view proposed by the author that the deposit was controlled by overlapping structure.

Abstract:Abstract：The Cailing granite on the eastern margin of the Qitianling granite was precisely dated at 160±2 Ma using zircon SHRIMP, which suggests that the Cailing granite was intruded in the early Yanshanian, rather than in the Indosinian as is considered previously. A few inherited cores record Mesoproterozoic age information, which indicates that Precambrian rocks might be one of the important components in the granitic magma melting source region in the study area.

Abstract:Abstract： Analyses of the climate, geomorphologic features, groundwater dynamics, tectonics and structure, development conditions of interlayer oxidation zones and geological and geochemical characteristics of the ore target beds suggest that the metallogenic conditions of in-situ leachable sandstone-type uranium deposits in the north of the Turpan-Hami basin are notably different from those in the south (the slope zone of Aydingkol Lake, Liaonang depression and Nangfu depression). The basic cause is related to the difference in dynamic evolution in the southern and northern parts of the basin. According to the characteristics of tectonic subsidence, tectonic sequences and influence by plate motion, the tectonic evolution of the basin can be divided into five stages, of which the third stage (Carboniferous to Triassic), the compression-type foreland basin sedimentary stage, laid the foundation of the differences in tectonic evolution between the south and north of the basin, and had profound influence on the distribution of Meso-Cenozoic in-situ leachable sandstone-type uranium deposits, the fourth stage (Jurassic to Cretaceous), the weak extensional-type downfaulted basin stage, provided the material foundation for the formation of uranium deposits in the south of the basin, and the fifth stage (Paleogene to Quaternary), the Cenozoic compressional-type foreland basin stage, provided the sufficient exterior dynamic force for the formation and enrichment of the uranium deposits in the south of the basin.

Abstract:Abstract：Due to the complexity of geological structures in metallic ore areas, seismic techniques applied in metal exploration are still in the experimental stage. Through several years of deep-going experiments, not only major progress in seismic techniques have been made, but pronounced positive geological results have also been obtained in using the seismic method to detect ore-controlling structures and look for local inhomogeneous bodies related to buried metallic ore deposits. The authors summarize some results of seismic and geological experiments obtained in the seismic experimental study of metal exploration and consider that the seismic reflection method can yield good results in the exploration for sedimentary stratabound ore deposits and ore-controlling structure and that the scattering wave method is useful for the study of subsurface local inhomogeneous bodies related to orebodies and the determination of the location of hidden orebodies as well. On that basis, the prospects of application of seismic methods in looking for buried metal deposits at depth are discussed.