摘要:Core V36-06-3, approximately 12m long, was raised from the lower part of the continental slope of the continental South China Sea from a water depth of 2,809 m. Analyses of planktonic foraminifera, CaCO_3 content and oxygen isotopes(δ~(18)O) in shells of Globigerinoides sacculifer show that the trend of the sea surfacetemperature change at this site over the last 130,000 years is consistent with that in other oceans, while the expression of the dissolution cycles of calcium carbonates here is contrary to that in the Pacific Ocean but consistent with that in the Atlantic Ocean, which means that the dissolution was intense and the CaCO_3 content was slightly low during the glacial ages, but the reverse was true for the interglacial ages. The reason for this is that during the glacial ages large quantity of terrigenous detrital materials were brought into the abyssal and bathyal Zones, thus diluting the calcium carbonate deposits and intensifying their dissolution.

摘要:On the basis of studies of the graptolite sequence at the Xiaoyangqiao section in the vicinity of Dayangcha Village and at the Qinggouzi and Muxiantougou sections near Hunjiang City, southeastern Jilin, five graptolite zones may be recognized in the 'Yeli Formation' in ascending order: 1. Rhabdinopora parabola zone, 2. Anisograptus zone, 3. Psigraptus zone, 4. Callograptus? taizehoensis zone, and 5. Adelograptus-Clonograptus zone. The correlation of each zone with its equivalents in other areas both in China and abroad and the Cambrian-Ordovician boundary are discussed.

摘要:The Qinling Mountains separating the northern from the southern China plate is a key region for the study of structural evolution of eastern Asia. It is composed of the Palaeozoic fold belt in its northern part and the Variscan and Indosinian fold belts in its southern part. The evolution of the former is marked by the closure of a northward subducting oceanic basin in the early stage, followed by southward obduction of ophiolites and intracontinental thrusting during the Variscan; whereas that of the latter is represented by intracontinental, shallow crustal deformation on the basis of a large-scale detachment structure(with a horizontal slip of at least of 100 km). Since the late Palaeozoic, however, both of the belts have been cut by a series of east-west sinistral strike-slip faults.

摘要:Symmetrical folding of a single layer and folding process of an overfold are analyzed by using the finite element method. In the analysis, the constituent substances are assumed to be isotropic and incompressible and to behave as Newtonian fluids. The penalty function method is used to deal with incompressibility, The results of the analysis are compared with the data measured in the field and with those obtained by the elastopla(?)e finite element analysis, It shows that the overfold geometry may be well simulated by using the viscous fluid model. Thus, a possible mechanism of the formation of overfold is proposed.

摘要:The Xihuashan granite is typically representative of the tungsten-bearing granites widespread in theNanling area of South China. It was considered in the past to have been formed by partial melting of the upper continental crust, with its source rocks most probably of the Sinian or Cambrian. However, detailed REE analyses, studies of the Rb-Sr isotopic system and melting experiments of metasedimentary rocks all argue against this idea. Moreover, stable isotopic data also indicate a deep source origin for S, C, H and O. The authors thus propose a genetic concept of the lower continental crustal source of the Xihuashan granite, and point out further that tungsten deposits related to this kind of granite are linked in some way to deep-seated structure and concentrated along NNE-NE- and ENE-striking major deep fault belts above the transitional zone between mantle uplift and mantle depression.

摘要:The etouchang-typeiron deposit is a typical stratabound deposit in the northern part of central Yunnan. The discussion centres on the controlling effect of the generation and development of the structural system in the orefield on the formation of this type of deposit and establish a time-space ore-control model so as to get a better understanding of the mechanism for its formation.During the formation and enrichment of the Etouchang-type iron deposit, the structures performed a dual control function on the generation and distribution and also on the reformation and enrichment of the source bed. The Etouchang-type iron deposit is a typical example for the stratabound deposits of which the formation and distribution are controlled by the generation and development of structural systems.During the embryonic period of the longitudinal structural system shortly after the Dongchuan movement, a N-S rift valley-type trough appeared between the Lüzhijiang fault zone and the Luoci-Yimen fault zone. It was along the marginal areas of the trough that the iron-rich clay and sand of dominant terrigenous origin were accumulated, constituting the source bed of iron.During the Jinning movement, the basement had been finally formed and the longitudinal structural system took shape. During the Chengjiang movement, the longitudinal structural system was strengthened and the central Yunnan xi-type structure appeared, which controlled the activities of the Na-rich magma and thermal fluids, and the consequent reformation of the source bed, themigration and enrichment of iron substance and the formation of economic deposits. The LuociYimen fault zone controlled the distribution of the iron orefield while the lateral structures(e. g., the Etouchang compounding shear structure) controlled the occurrence of the deposit.The reformation and enricbment of the Etouchang-type iron deposits were concomitant with the formation of an ore-controlling structure. The scale and grade of the orebodies were strictly controlled by the structural pattern, and the orebodies occurred in the shear structures and were enriched in the tensional portion of a compressive structure.

摘要:The Qarhan potash-magnesium salt deposit, which consists from east to west of four playa districts, namely Huobuxun, Qarhan, Dabuxun and Bieletan, may be divided from bottom to top into three salt beds(S_1, S_2 and S_3), with potash salts mainly occurring in S_3. The paper lays emphasis on the evolutionary history of the deposition of Salt Bed S_3 and the modes of formation of potash salts in the Qarhan playa.The analysis of the data obtained from more than 170 boreholes and the geochemical studies on bromine, magnesium and calcium reveal the existence of four concentration stages and three dilution stages during the ormation of the Upper Salt Bed S_3. In the process of concentration, evaporation of brine and precipitation of salt minerals dominated, which obeyed the regularity indicated by the phase diagram of the quaternary system Mg-Na-K/Cl~-H_2O. In the dilution stages, however, mixing of brines, dissolution of salts(especially the playa) and mechanical clastic deposition played the leading role. The prerequisite for mixing in the Qarhan salt deposit lies in that chloride type brine of the northeastern part coexists with magnesium sulfate type brine of the southwestern part in the same salt lake. The appearance of bassanite has verified the process of mixing. The dissolution refers to the partial dissolution of the salt beds originally deposited. Particularly in the last dilution process, approximately 200 km~2 of the playa north of the Tuanjie Lake had been dissolved before a new-born lake took form.Solid potash salts were formed in three ways:(1) The surficial brine of the Dabuxun lake coexistent with the playa had an intercompensational relationship with the intercrystalline brine in the playa. As a result, K~+ ions were collected into the lake, and layered Carnallite precipitated from lake brine during the seasons of evaporation, which was accelerated by the action of wind.(2) Disseminated potash-magnesium salts were formed by further concentration of intercrystalline brine.(3) Dissolution and reformation of the playa resultedin the formation of a new-born salt lake, in the drying of which brine collected the potash-magnesium salts originally dispersed over the playa into local low-lying areas, forming finally stratoid potash-magnesium salts.

摘要:Sourthern China referred to in this paper embraces all the provinces to the south of latitude 32° N within the territory of China, exclusive of Tibet and Taiwan.The paper is based on the data obtained from temperature measurements of 680 boreholes drilled for petroleum, coal and hydrogeology. The depth of these boreholes ranges between 1,000 and 2,000m in most cases, being generally not less than 400m and reaching 7,000m in maximum.Through the elaboration and analysis of the temperature data, isotherm maps showing the temperatures at depths of 1,000m, 2,000m and 3,000m respectively and a geothermal gradient map of southern China have been compiled. These maps indicate that the earth's temperature distribution in southern China is characterized by a elatively low value in areas of its central part and those to the west of the Anning River valley of the western part(30℃, 40℃ and 70℃ at depths of 1,000m, 2,000m and 3,000m respectively), and a comparatively high value in the southeastern coastal areas and western Yunnan(60℃, 80℃ and over 120℃ respectively), and that the geothermal gradient also increases from less than 1.5℃/100 m in the central part towards both the east and the west to 2.0-3.0℃/100m or even over 4.0℃/100m.The earth's temperature distribution is strictly controlled by the deep structure of the earth's crust and is very closely related to the character of the regional geological structure, The stable central areas remarkably differ in the earth's temperature distribution from the tectonicalty active areas such as the southeastern coastal areas and the Jinggu-Tengchong area in western Yunnan, the former being lower than the latter. Meanwhile, due to the well-developed karst features in southern China, the strong groundwater flow may exert certain cooling effect on the temperature down to a depth of about 1,500m.According to the regularity of the earth's temperature distribution, regional deep structure of the earth's crust, regional geological structure and hydrogeological conditions, the following four models are proposed to explain the mechanism of formation and distribution of the earth's temperature fields in southern China: 1) onduction type; 2) convection type; 3) deep heat-source conduction-convection type; and 4) precipitation infiltration cooling type.