Abstract:Abstract:Recent studies on the compositions and structures of multiple terrains within the plateau have offered us an QinghaiTibet opportunity to examine how this plateau was assembled in the context of terrain tectonics. The formation of this plateau resulted from tectonic activities since the late Longterm Paleozoic which is represented by (1) convergence and welding of A number of exotic terrains, and (2) collision induced "orogenic plateaux" and has reached its climax in the Cenozoic. faults (commonly Largescale Strikeslip act as terrain boundary faults) has played a central role in controlling the relative offset, magnitude of lateral extrusion, and the geometry of these terrains. The final assembly and rise of the QinghaiTibet Plateau May result from a combination of contemporaneous processes, e.g. Superdeep subduction (> 600 km) at its southern margin subduction at its northern margin, Intracontinental Inland, deep thermal processes, and lateral uplift of mantle lithosphere. NEtrending Right.

Abstract:Abstract：The deformation features, age, tectonic evolution and tectonic role of the Karakorum fault (KF) have long been controversial. In the Ayila Ri’gyü area in the southeastern segment of the KF, dextral sheared mylonite and mylonitized gneiss-granite are exposed along the fault. Microstructural study indicates high-temperature, dextral shear features, accompanied by the generation of synkinematic leucogranite. The U-Pb ages recorded by synkinematic crystalline zircons imply that：the KF formed at least before 23－２５ Ma and its continuous deformation at least continued to ~12 Ma, when the deformation was accompanied by rapid uplift of the Ayila Ri＇gyü Range and initiation of the Gar basin. Integrated analysis indicates that the growth process of the KF might be a process of northwest-directed propagation and the result of continuous India-Eurasia collision. The cumulative displacement amount is at least 280 km ａｌｏｎｇ the fault， and ａｎ average long-term slip rate is ~11 mm/a ｏｎ ｔｈｅ ｆａｕｌｔ. Rigid block kinematic analysis suggests that material of the Qinghai-Tibet Plateau was extruded toward ~108°N ａｔ a rate of 16.２ mm/a after ~23－25 Ma.

Abstract:Abstract：The determination of macroscopic structural characteristics has great significance for the study of the uplift of the Qinghai-Tibet Plateau and its “dynamic model construction”. The Qinghai-Tibet Plateau represents a gigantic “convergence-intracontinental subduction type” lithospheric block formed by amalgamation of six terranes of three plates (or old land), i.e. the North Kunlun-Altyn Tagh-Qilian terrane of the Tarim-Sino-Korean plate, the South Kunlun terrane and Hoh Xil-Bayan Har terrane of the South China-Southeastern Asian plate and the Qiangtang terrane, Gangdise terrane and Himalayan terrane of Gondwanaland, through multiple breakups, convergences and intracontinental subductions. It is separated from the Indus lithospheric block, Tarim-Alxa-Ordos lithospheric block and Yangtze lithospheric block by the south Qinghai-Tibet Plateau marginal junction zone, north Qinghai-Tibet Plateau marginal junction zone and east Qinghai-Tibet Plateau marginal junction zone respectively. According to the present-day dynamic characteristics, this gigantic lithospheric block (first-order tectonic unit) may be subdivided into four second-order tectonic units, namely, the Himalayan block, northern Tibet block, southern Qinghai block and Kunlun-Altyn Tagh-Qilian block, which are bounded by the Yarlung Zangbo junction zone, Xijir Ulan-Jinsha River junction zone and Central Kunlun junction zone successively. The four blocks may be further divided into several fault-bounded third-order tectonic units (terranes).The various tectonic units making up the gigantic Qinghai-Tibet lithospheric block are situated in a unifying geodynamic system. This geodynamic system is generally manifested as follows：the Himalayan block and Kunlun-Altyn Tagh-Qilian block on the southern and northern sides of the Qinghai-Tibet lithospheric block are asymmetrically thrust toward and stacked on the cold and rigid Indus lithospheric block and Tarim-Alxa-Ordos lithospheric block respectively in the tectonic setting that the Indian plate is continuously and strongly subducted beneath the Eurasian plate and the hot Qinghai-Tibet lithospheric block with ductile rheological properties moves en bloc in a NNE direction. Beneath the northern Tibet block and southern Qinghai block in the interior of the Qinghai-Tibet Plateau, large numbers of low-velocity bodies at depth upwell and propagate horizontally from west to east. In this tectonic setting, the former is superimposed by nearly N-S compression, forming a tectonic framework marked mainly by N-S-trending downfaulted zones and NW- and NE-trending conjugate strike-slip motions； whereas for the latter, except for the Songpan-Garzê terrane that shows south-vergent thrust stacking, the Hoh Xil-Bayan Har terrane is mainly manifested by sinistral strike-slip motion leading to successive eastward extrusion, so that the whole southern Qinghai block experiences thrust propagation toward the Yangtze block and spreading toward the Sanjiang tectonic zone. Therefore, with increasing rate of uplift with time, the plateau also propagates gradually toward the rigid blocks at its peripheries, i.e. the area of the plateau expands progressively. So the plateau boundaries have the nature of propagation. On the basis of the propagation mechanism, two types of dynamic boundary may be distinguished：strike-slip type propagation boundary and thrust type propagation boundary. The typical propagation boundary is located in the Altyn Tagh Mountains on the northern margin of the Qinghai-Tibet Plateau and the Sanjiang area on the eastern margin of the plateau. The dynamic boundary on the southern margin of the plateau belongs to the typical thrust type propagation boundary, while the dynamic boundary in the Qilian and Longmen mountains has both the nature of thrust propagation and the nature of strike-slip propagation.

Abstract:Abstract：An earthquake of magnitude 6.7 and dozens of aftershocks were recorded by ten REFTEK broad-band seismographs in the range of the array of seismograph stations deployed north and south of the Qilian Mountains in April 2003. These records provide nｅw data for the study of the deep structures on the northern Qinghai-Tibetan Plateau. The focus location and focal mechanism study of the shocks of magnitudes >3 show ｔｈａｔ thｏｓｅ earthquakeｓ ｗｅｒｅ initiated by the Jun Ul Mountain thrust fault in the eastern segment of the northern Qaidam basin sinistral strike-slip fault under north-east compression and ａｒｅ the result of continent-continent collision and intracontinental subduction.The strike-slip fault on the northern margin of the Qinghai-Tibet Plateau dips gently in the shallow levels of the earth′s crust, while in the deep levels it usually dips steeply toward the interior. The structure analysis of the hypocenter area verified the influence of the super-deep subduction of the Indian lithospheric plate on the northern margin of the plateau. The nearly east-west displacement of the strike-slip fault formed by the action of north-south stress is still very intense at present.

Abstract:Abstract：The authors systematically analyzed the focal mechanism solutions of 905 earthquakes （M4.6-8.5） that occurred in and around the Qinghai－Tibet Plateau between 1931 and 2005 and studied the characteristics of the regional stress field and tectonic movement of the lithosphere below the Qinghai-Tibet Plateau. The results show that the NNE or NE horizontal compressional stress due to the northward movement of the Indian plate predominates the tectonic stress fields in and around the study region. The horizontal components of the principal compressional stress P axes are oriented in a nearly NE-SW direction, forming a wide NE-SW compressional stress field in a wide areal extent from the Himalayas to south of Baikal Lake, including western China. Especially in the surrounding areas of the Qinghai－Tibet Plateau, earthquakes caused by reverse and strike-slip faulting are predominant in the Himalayan Mountain front on the southern Qinghai－Tibet Plateau and on the northern and western margins of the plateau, except the eastern margin. It implies that a strong horizontal compressional stress exists around the plateau. The characteristics of the stress field show that the direct cause of the uplift of the Qinghai－Tibet Plateau is due to the compressional stress field formed by the northward movement of the Indian plate and India-Eurasia collision. Many normal fault type earthquakes are concentrated in areas with elevations of >4000 m above sea level on the central Qinghai-Tibet Plateau while the surrounding areas of the Qinghai－Tibet Plateau are subjected to the control of the strong compressional stress field. Of these, many earthquakes are pure normal fault type ones. Their focal mechanism solutions show that the nearly E-W or WNW-ESE horizontal tensional stress controls the lithospheric stress field in the region. The normal fault type earthquake faults mostly strike N-S and the horizontal component of the displacement vectors of the faults is largely oriented in a nearly E-W direction. This indicates that a nearly E-W extensional movement exists in areas with a high altitude in the central part of the plateau and that the extensional movement is the result of the action of the tensional stress field. The dynamics for the extensional movement may be attributed to the gravitational collapse caused by the increasing load of the continuously rising plateau and the regional stress of its surroundings. The study of the regional characteristics of the compressional and extensional stress fields and their tectonic movement on the Qinghai－Tibet Plateau has very great significance for understanding the geodynamic mechanisms of the formation and development of the Qinghai-Tibet Plateau.

Abstract:Abstract：It is hard to acquire high-quality seismic sectionｓ in the Qiangtang basin because of complex surface geological conditions and a low signal-noise ratio. In regard to this problem, the authors deployed test seismic profiles with a total length of ~52 km in Qiangtang and preliminarily developed a set of seismic data acquisition and processing techniques suited to the features of this area. The two processed stacking profiles show informative reflection and reveal the features of spatial distribution of various structural layers above the basement, which provides high-quality data for ascertaining the structural traps and tectonic boundaries and determining the stratigraphic grouping. On the basis of an analysis of the seismic reflection characters, a preliminary study of the burial depth and morphology of the crystalline basement of the Qiangtang basin displayed by the two profiles has been undertaken.

Abstract:Abstract：All the rocks in the east-west planar ductile detachment zone in the Burang area in the western part of the Greater Himalaya terrane have suffered from plastic deformation to different degrees and mylonitization. The foliation of the mylonites dips gently to the east and the stretching lineation plunges to the east at 5°－18°. Asymmetrical rotational strain structure indicates that the ductile detachment had the nature of east-directed movement in the early stage and the features of west-directed brittle-ductile deformation. Electron backscatter diffraction (EBSD) fabric analysis shows that the preferred orientation of deformed quartz in mylonites has two slip systems：the east-directed high-temperature prism{1010}＜a＞ and intermediate-temperature rhomb glide{101 １}＜a＞ system and the west-directed intermediate-temperature rhomb glide {101 １}＜a＞and low-temperature basal glide{0001}＜a＞ system. This, combined with the characteristics of the asymmetric rotational structure prevalent in mylonites, suggests that the east-directed ductile detachment in the early stage formed in an intermediate- to high-temperature environment and that the west-directed brittle-ductile in the late stage formed in an intermediate- to low-temperature environment. Zircon SHRIMP U-Pb dating shows that the protolith of the metamorphic basement in the Burang area of the Greater Himalaya terrane formed at 1863 Ma. The isotopic dating of mylonitic granite and undeformed leucogranite show that the east-west-trending Burang planar ductile detachment took place in the early Miocene, which coincides with the ages of the MCT and STDS on the northern sides of the Greater Himalaya terrane. When the compressional stress produced by northward subduction of the Indian plate acted on the arcuate Himalayan orogenic belt, it was resolved into two components, one being orogen-parallel and the other orogen-perpendicular. The former caused plastic flow of the material of the middle and lower crustal below the orogenic belt, thus forming the Burang planar ductile detachment zone, while the latter resulted in the formation of the MCT and STDS. They are different tectonic styles formed in the same tectonic stress field and same tectonic event. The detachment zｏne is the product of large-scale north-south shortening and uplift and eastward escape of a part of material.

Abstract:Abstract：The broadband seismic survey and aeromagnetic anomaly study show that the lithosphere below the southern part (i.e. Qinghai-Tibet plate) of the West Kunlun tectonic belt was subducted beneath the Tarim basin and that the ophiolite belt of the West Kunlun is the relics of the Paleo-Tethys ocean that closed during the Caledonian orogen． Due to the strong resistance from the rigid old Tarim terrane during the subduction of the Qinghai-Tibet plate, the north-subducting lithosphere broke up and delaminated. Meanwhile, the rebound of the Qinghai-Tibet lithosphere and buoyancy of the asthenosphere caused extensional downfaulting of the upper crust, which allowed the molten magma at depth to upwell, thus resulting in eruption of alkaline magma along the faults. Furthermore, this also formed an antithetic thrust tectonic framework on both sides of the tectonic belt. The West Kunlun Central fault is actually the “fourth suture” of the Qinghai-Tibet Plateau, whereas the North Kunlun tectonic belt just formed by thrusting of the material at the shallow crustal level in the West tectonic belt over the Tarim foreland during delamination of the lithosphere of the Qinghai-Tibet plate.

Abstract:Abstract：The seismic profile from Yecheng-Gar (Shiquanhe) in the West Kunlun on the Qinghai-Tibet Plateau deployed by the Sino-French joint project traversed major structural units in the West Kunlun tectonic syntax. Through a receiver function analysis of three-component P wave data recorded by 36 stations for 128 teleseismic events, the authors obtained the variation trend of the receiver functions with the azimuth and epicenter distance for these stations and analyzed its relationship with crustal structure. The shear wave velocity distribution in the upper 120 km of the crust ａｎｄ ｕｐｐｅｒ ｍａｎｔｌｅ was obtained by the inversion of average receiver functions at various stations. On that basis, combined with interpretations of geological structure, the phenomenon that the inclined surface of the Kangxiwar fault becomes gradually nearly upright and then drags southward slightly has been found, which is markedly manifested by sediments of the Tarim foreland basin thrustｅ structures, and in addition it is also inferred that there is décollement beneath the basin. The Bangong Co-Nujiang suture also has traces of northward subduction. So it is deduced that the long distance effect of India-Tibet collision is hindered at the West Kunlun, and the stress is released by subsidiary faults at the surface and a foreland structural model of basin sediments is constructed.

Abstract:Abstract：The Beishan orogen is located at the junction between the Tarim-Sino-Korean and Kazakhstan plates, and its main orogenic event occurred in the Early Paleozoic. Eclogites are associated with ultramafic-mafic rocks and collisional granites in the south belt of the Beishan orogen, which suggests that this belt might represent a plate boundary. SHRIMP U-Pb isotope dating of zircons from the Beishan eclogite yielded an eclogite-facies metamorphic age of 819 ± 21 Ma and a protolith age of 1007 ± 20 Ma, indicating an important plate breakup and subduction-collision event in the Neoproterozoic. Recently an event of Neoproterozoic plate breakup and ophiolitic oceanic crust formation has also been reported in the North Qaidam marginal area in the southern Qilian Mountains adjacent to the Beishan, suggesting the occurrence of a regional breakup event in a Neoproterozoic oceanic basin in western China, which is called the Rodinian Supercontinent breakup event. However, it should be emphasized that the eclogitic-facies metamorphism in the Beishan took place in the Neoproterozoic, while that for the North Qaidam marginal eclogite occurred in the Early Paleozoic (500-440 Ma) though its protolith is the Neoproterozoic oceanic crustal rock, suggesting another subduction-collision event after the Neoproterozoic subduction-collision event in the Beishan.

Abstract:Abstract：The Hongliuxia volcanic field is located at the junction of the Altyn Tagh strike-slip fault and the northern Qilian Shan frontal trust fault. In this area, an andesitic dike, ~85 Ma old, cuts through ~105 Ma shoshonitic and basaltic lavas. Major and trace element studies and Sr and Nd isotopic analyses of this suite of rocks show that this younger dike has anomalous geochemistry, as compared to nearby basalts. This dike has the following salient features：(1) peralkaline with Na2O+K2O=11.8% and A/CNK=0.5540；(2) highly enriched in HFSE (e.g. Zr=1421 μg/g, Hf=26.4 μg/g, Y=48.2μg/g, Nb=104.0μg/g and Ta=8.5μg/g)；(3) a pronounced positive Ce anomaly (Ce/Ce*=1.128)；(4) nearly flat chondrite-normalized MREE and HREE distribution patterns；and (5) similar initial Sr but notably low Nd (by >2 εNd units) isotope ratios, as compared to those in the Hongliuxia shoshonitic basalts. These differences reflect not only the difference in geochemistry of their respective source regions but also the difference in behaviors of dissolution or crystallization of dominant minerals and accessory minerals during partial melting and magmatic evolution.fractionaｌ crystallization of anorthite and enhanced dissolution of zircons in its source regions are the main controlling factors responsible for the anomalous geochemistry of this dike. The geochemical processes reｃｏｒｄｅｄ by this dike may help the interpretation of similar intermediate-acid alkaline volcanic rocks since the Mesozoic on the Qinghai-Tibet Plateau.

Abstract:Abstract：A strongly peraluminous (SP) granites belt, extending over 100 km from east to west, is distributed 800-100 km south of the Bangong Co-Nujiang junction zone. It consists of several intrusions such as the Songmuguo intrusion and Yangxiongle intrusion. The intrusions are emplaced on both south and north sides of the Ngangzê Co-Sereba fault and involve five intrusion events. They all belong to high-K, calk-alkaline, SP granites and are post-collisional SP granites of Mid-Late Jurassic age. Study suggests that the formation of the belt is related to the southward subduction and closing of the Nyima segment of the Bangong Co-Nujiang junction zone before the Middle Jurassic. The limited length of the SP granite belt and its earlier regional emplacement time show that the Meso-Tethys is composed of multiple blocks and closed in different times.

Abstract:Abstract：Metallogeny of continents is an important research frontier in the contemporaneous metallogenic study, and its theoretical framework is conceived and established by gaining a deep knowledge and understanding of metallogeny in the continental collisional orogen. For a long time, geologists cannot reach a common view on the stages of collisional metallogeny and dynamic process in various stages because of a poor understanding of metallogeny in typical collisional orogens and coupling and genetic relations between the collisional orogenic process and crust/mantle interaction on the one hand and metallogenesis on the other. The Qinghai-Tibet Plateau orogen, which is characterized by the occurrence of large-scale, intense and young mineralization as well as many types of large and well-preserved deposit, is regarded as an ideal natural laboratory for studying ore-forming processes on continents and solving the above-mentioned problems. Through three years of systematical research on the metallogeny in the collisional orogen of the plateau, our project team has established a temporal-spatial framework of major mineralization events on the plateau, proposed a model of geodynamics and tectonic constraints on the ore-forming processes and put forward a set of complete theories on metallogeny in the collisional orogen. Three ore-forming processes and twelve deposit types are proposed in the new theories；they are：(1) metallogeny in the period of syn-collisional orogeny (65–41 Ma, four deposit types)；(2) metallogeny in the period of late-collisional transformation (40–26 Ma, four deposit types)；and (3) metallogeny in the period of post-collisional crustal extension (25–0 Ma, four deposit types). The corresponding key factors controlling the ore-forming processes are：(1) collisional orogenic setting, crustal magmatic activity and large-scale shear deformation;(2) intercontinental plate transformation setting, mantle-derived magmatic activity and large-scale strike-slip motion-nappe thrusting-shear deformation；and (3) post-collisional crustal extension setting, crust/mantle magmatic activity and hydrothermal convection system.

Abstract:Abstract：The Pulang porphyry copper deposit is located on the eastern margin of the Dege-Zhongdian block on the western side of the Garze-Litang junction zone, in the southern segment of the Indosinian Yidun-Zhongdian island-arc belt. The strata of the copper district are the Upper Triassic Tumugou Formation, and there mainly outcrops the Indosinian Pulang composite intermediate-acid porphyry. Structural fissures are well developed and rocks are strongly altered, showing typical “porphyry type” alteration zoning with intense silicic alteration zone → silicic-potassic alteration zone → phyllic alteration zone → propylitic alteration zone from the center outward. Magmatic rocks, strata emplaced by magma, hydrothermal alteration and structural space for hydrothermal fluid transport and deposition of ore substances controlled the occurrence of this deposit. The mineralization occurred in the Pulang composite porphyry and mineralization and alteration occur in company. A pipe-shaped orebody composed of veinlet-disseminated ores formed in the center of the intrusion and vein-shaped orebodies formed at edges of the intrusion. The dominant ore element of the deposit is copper, with many subordinate useful components such as gold, silver, molybdenum, palladium and sulfur. The deposit reaches the superlarge size.

Abstract:Abstract：The Qinghai-Tibet Plateau lies in the junction between the Indian plate and Eurasian plate, on the northern margin of Gondwanaland. Collision of the Indian plate with the Eurasian plate about 65 Ma ago resulted in reworking of the tectonic framework and metallic ore deposits and also the formation of a nｅw tectonic framework and new metallic ore deposits, which made metallic ore deposits on the Qinghai-Tibet Plateau distinctive. This paper deals with dominant mineral deposits of such metals as chromium, iron, copper-molybdenum, lead-zinc, tin, gold, antimony and cesium on the Qinghai-Tibet Plateau.

Abstract:Abstract：Field investigations of the geomorphology of river valleys and neotectonic deformations in the source region of the Yangtze River, northern Tibet, show that the region is characterized by a parallel type drainage pattern and wide and narrow valleys of different shapes. Since the Neogene, the region mainly has undergone a tectonic evolution from compression in the early stage and extension in the late stage, thus forming three tectonic deformation styles, i.e.: folds-thrusts and strike-slip shear in the early stage and normal faults and grabens in the late stage. Neotectonic movement has not only controlled the geomorphological features of the river valleys and drainage pattern but also affected the distribution of the river terraces and shape and structure of diluvial (alluvial) fans. The main drainage system in the source region of the Yangtze River formed at least by headward erosion along the faults of different natures generated by neotectonic movement during the Holocene.

Abstract:Abstract：Located on the northeastern margin of the Qinghai-Tibet Plateau, the Minxian-Wudu area in the West Qinling is tectonically a transition zone between two major tectono-morphological units in China. Tectono-morphological study shows that four planation surfaces are developed in this area; they are planation surfaces I (mountain top surface), II (main planation surface) and III and IV (erosional surface), which formed before the Middle Cretaceous-late Paleocene and at 3.6, 2.5 and 1.8 Ma respectively. Four to seven terraces are developed for main rivers in this area, and terrace IV and those of still smaller orders in these rivers have similar characteristics. The variations in attitude of these planation surfaces and terraces indicate that the crustal uplift in the area occurred in several stages and heterogeneously：the average uplift rate has been 0.42–0.57 mm/a and the 3.6–1.8 Ma period was a stage of rapid crustal uplift; the uplift rate became low at 1.8 Ma but the uplift accelerated markedly since the late Pleistocene (0.15 Ma), suggesting that the plateau is now in a new stage of uplift acceleration.

Abstract:Abstract：The macroscopic characteristics, mineral and clastic compositions, textures, carbon and oxygen stable isotopes and paleontological and paleoecological characteristics of Mid-Upper Jurassic carbonates in the Qiangtang basin, northern Tibet, have been studied systematically based on detailed field section surveys. Study shows that the carbonate rocks mainly include micrite, grainstone and packstone. The δ13C and δ18O values show two cyclic variations from low→high→low→high→low from the Quemo Co Formation→the Buqu Formation→Xiali Formation→Suowa Formation→Xueshan Formation. The Quemo Co and Xueshan formations are dominated by fluvial-dominated deltaic deposits, the Buqu Formation by carbonate ramp deposits, the Xiali Formation by tidal flat-deltaic deposits and the Suowa Formation by tidal flat-lagoonal deposits. The water table in the Mid-Late Jurassic Qiangtang basin showed the rising and falling cycles from shallow→deep→shallow→deep→shallow in the general trend of water table lowering. Meanwhile, the depocenter of the basin migrated from east to west and the Jurassic sedimentary environment of the Qiangtang basin is controlled by the combined regional tectonic evolution and global sea level change.

Abstract:Abstract：This paper proposes a new pattern of tectonic units of China based on the petrological structure model of the lithosphere under continental China and five types of lithosphere, namely, cratonic lithosphere, orogenic lithosphere, rift lithosphere, marginal-sea oceanic crust lithosphere and island arc lithosphere,distinguished according to the dynamic properties of the lithosphere, combined with the present characteristics of compression in the west and extension in the east of continental China. The content of the new pattern is as follows：the lithospheric discontinuity along the western boundaries of the Sichuan,Ordos and Yinchuan basins is used as the boundary to divide continental China into two first-order tectonic units, i.e. the western China tectonic unit and the eastern China tectonic unit;the above-mentioned different types of lithosphere are considered as their second-order tectonic units; and some subtypes of the orogen-type lithosphere are the third-order tectonic units. On the basis of the new pattern of tectonic units, combined with the geological history, their formation processes and implications for ore finding are also discussed briefly in this paper.

Abstract:Abstract：Geochemical exploration is mineral exploration carried out by using variations of element contents in various kinds of media. Therefore geochemical mapping is the most fundamental work for geochemists, just as geological mapping for geologists. Variations in element background values in various types of rock have an important influence on the prognostic process during geochemical prognosis of ore deposits. Seven-six elements for geochemical mapping in southwestern China may be divided into two groups：(1) the element group with less influence of lithological variation on metallogenic prognosis, and (2) ｔｈｅ element group with more influence of lithological variation on metallogenic prognosis. The first element group consists of Hg, Cd, Sb, Au, Sn, Mo, Ag, U, Pb, Bi and W, which are characterized by the ratios of the highest background values in rocks to the anomaly thresholds in the prognostic region of <1 and the ratios of the maximum background values to the minimum background values of <4. This geochemical method is very effective for searching for minerals of these elements. The second element group consists of Pt, Co, Cr, Cu, Ni, V and Ti, which are characterized by the ratios of their highest background values in rocks to the anomaly thresholds in the prognostic region of >1 and the ratios of maximum background values to the minimum background values of >8. This paper deals with the elements Sn (belonging to the first element group) and Cu (belonging the second element group). Sn deposits in southwestern China are closely related to Sn geochemical anomalies, whereas Cu deposits in southwestern China are not necessarily bound up with giant Cu geochemical anomalies. For the second element group, the multifractal filter technique should be used to suppress different background interferences and extract mineralization information from the geochemical anomalies of the elements.

Abstract:Abstract：Metamorphic rocks of the Meso- and Cenoproterozoic Dongyan Formation in central Fujian are an important source bed of lead-zinc polymetallic deposits. The metamorphic rocks consist of three basic-acid volcanic-sedimentary cycles and show the features of bimodal volcanic rocks. Each volcanic cycle starts with basic rocks and ends with acid rocks, and marine carbonate rocks often occurred during dormant periods, especially at ｔｈｅ end of each cycle. Lead-zinc-silver deposits are usually associated with basic volcanic rocks. Petrological and chemical analyses of the metamorphic rocks of the Dongyan Formation reveal that the protoliths of the metamorphic rocks of the formation have the features of continental rift tholeiite and formed in an intraplate rift environment. The tectonic setting should be the extensional environment in the interior of the continental plate.

Abstract:Abstract:Study of four well cores and relevant data of other wells obtained from the Upper Permian Changxing Formation in the Huanglongchang structure has demonstrated that there are organic reefs in cores from the Huanglong No. 1 well and Huanglong No. 4 well but no reefs in cores from the Huanglong No. 3 well and Huanglong No. 5 well. The reefs consist of sponge bafflestones, wh ICH belong to carbonate platform margin reefs. Due to little difference in physical properties of reef and strata strong heterogeneity Nonreef, in reefs and outstanding multiple solutions to the prediction problem, the authors used the prediction method of combining geological, logging and seismic approaches to determine the boundary of the organic reef gas reservoir in the Huanglong No.1 well area and found an organic reef gas reservoir on the western side of the Huanglong No. 5 well. Thus a practical method for predicting reefs is provided.

Abstract:Abstract：The sedimentary evolution of the Late Paleozoic Youjiang basin is dealt with on the basis of the study of the sedimentary characteristics of the Late Paleozoic deep-water sedimentary strata, basalt geochemistry and important tectonic events of the sections at Badu of Tianlin, Pohe of Napo and Pingxu and Yangyu of Baise. The authors suggest that after the continental-margin rifting and separation in the late Early Devonian, the Youjiang basin underwent a complete evolutionary sequence from the formation stage of a rift basin (late Early-early Late Devonian), formation stage of an oceanic basin (Late Devonian-Early Carboniferous), strong spreading stage of the oceanic basin (Late Carboniferous-Middle Permian), contraction stage of the oceanic basin (Late Permian-early Middle Triassic), closing and rapid filling stage of the oceanic basin (late Middle Triassic).

Abstract:Abstract：The coastal area of southern Fujian is one of the areas with the highest level of urbanization in China, with its GDP accounting for 51.64% of Fujian Province. It has become the core area for the construction of the "economic district at the west coast of the Taiwan Strait". A city is an ecosystem centering on the human society as well as a system of the unity of opposites with the urban society (population, labor and intelligence) on the one hand and the urban space (geology, resources and natural environment) on the other. Regional crustal stability is considered an essential condition for urban construction, while water is an indispensable natural resource for urban development. The weathering crust of granite is well developed along the coast of southern Fujian and the engineering-geological problem of the soft soil environment is prominent. The paper focuses on the regional stability of a city, supply-demand balance of urban water resources and engineering geological problems that may be involved during urban construction.