Abstract:Reef-building was controlled by the community succession, sea-level elevation and basement changes caused by tectonics. Six kinds of reef-building communities have been sorted out, which possessed different compositions and occupied respective ecological sets. Types and thrivingness of communities were distinctive and replaced one after another in the four stages of reef development. Sedimentary cyclothems are clearly discernible in the reef-facies strata, which could divide into five sequences and fourteen types of parasequences. These se-quences represent varied degrees of rising-falling cycles of the sea-level, which limited community distributions and reef-building velocities. Based on the analysis of community succession, sea-level elevation and paleo-geographic variation in the working area, four stages of tectonic evolution in the Hercynian can be distin-guished , which made up two open-closing cycles between the Qaidam plate and the Qiangtang plate. The reefs were built in the open-closing transitional period of the mid-late Hercynian, while southern margin of the Qaidam plate kept a stable condition continuously.

Abstract:Complete Late Cretaceous to Palaeogene strata are exposed in the Gamba area, Tibet. The strata contain abundant fossils. An accurate chronostratigraphic classification has been made according to the fossil study. The authors suggest that the Cretaceous-Palaeogene be located between the Zongshan Formation and Jidula Forma-tions and be marked by the disappearance of the benthonic forarninifer Orbitoides-Omphalocyclus assemblageand the first occurrence of the Rotalia-Smoutina-Lockhartiz assemblage. The contact between the strata above and below the boundary are disconformable, with a short exposure surface within it. The Palaeogene sandy con-glomerate directly overlies the Late Cretaceous shelf carbonate rocks. The significant change of the deposits rep-resents a tectonic movement. The northern margin of the Indian continent and the southern margin of Gangdise had both shown the distinct phenomenon of shallow-sea biogeographic provincialism till the latest Cretaceous, and in this period they were separated by a deep-sea basin. At the beginning of the Palaeogene the shallow-sea fauna showed the features of the same biogeographic realm in the area, suggesting that the separation of the two continents by the deep-sea basin had disappeared and the northern and southern biogeographic provinces be-longed to a single remnant sea basin. The transformation of the sediment types and stratigraphic and palaeonto-logical characteristics provide fundamentat data for the study the timing of initiation of the collisionbetween the Indian and Asian plates. According to that it may be inferred that the early continent-continent collision took place at the time (- 65 Ma) of the Cretaceous -Palaeogene. The mid-late Palaeogene carbonate platform un-derwent continued compression and deformation, which further indicates that the continent collision had taken place at the beginning of the Palaeogene. The fracturing and olistostromes are the result of sustained sollison and compression.

Abstract:迄今为止，非撞击型超高压变质作用均发生在陆陆碰－撞造山带，这在东半球许多地点已被证实，超高压变质岩石以含柯石英和金刚石包体的榴辉岩和榴辉岩相变质岩石为代表，形成的温压环境为650－800℃，2.6-3.5GPa，研究证明大多数超高压岩石原是陆壳火山－沉积岩系，因此推断大陆深俯冲作用曾经发生，而超高压岩石现今又出露地表或浅表，意味着它们又从深部折返至地表，陆壳岩石深储冲和折返机制已成为大陆动力学研究的热点，但认识莫衷一是，争论的焦点是陆壳俯冲的深度到底多大可以形成超高压岩石？是什么机制使其发生深俯冲而又折返到浅表？本文通过世界上出露规模最大的超高压变质带－大别山碰撞过程的动力学分析，探讨非规则边界的碰撞引起的构造附加压力对超高压石形成的影响作用。模拟计算表明，大陆板块的早期碰撞，会引起碰撞附近的局部应力集中现象（平均压力较周围增大了5－9倍），构造压力在超高压中所占的比例约为20％－35％，由此推测，大别山高压－超高压岩石形成深度可能为65－80km。为此本文提出超高压岩石新成因模式－大陆点碰撞模式。这种模式符合力学基本原理，也符合地质记录和地质过程，可以解释为什么超高压岩石并非沿碰撞造山带全线存在，而是出现某些特定部位。本文提出喜马拉雅山撞带的东西犄角是典型的点碰撞区域，陆壳岩石的超高压变质作用均发生在这两个特定的部位。

Abstract:Magmatic underplating is an important process in the interaction between the crust and mantle and for un-derstanding continental accretion. However, identification of underplating process is a very difficult task. Based on seismic, geothermal and geoelectrical data collected during the site-selection investigations for the Chinese continental scientific drilling project, it is inferred that an event of magmatic underplating occurred accompany-ing the Jiashan-Xiangshui continental rift system in the Eogene Period. This magmatic underplating process had the same heat origin with the rift system. The thickness of the transition zone between the crust and the mantle is about 3 km and composition of the zone might be the interbed of peridotite and basic granulites. To-gether with the data of basalts in the area, it is estimated that the average rate of vertical thickening of the con-tinental crust owing to the magmatic underplating is about 0. 1 mm/year.

Abstract:The origin of the South China Sea has long been a hot subject of research, as it is related to the interaction of two large convergent zones, the Tethys and the Circum-Pacific, as well as to the geodynamics of the marginal seas of the West Pacific. The Sea of Japan and the South China Sea, as part of the inner zone of the West Pacific marginal seas, have many common features such as the age, shape and topography of the sea bas-in , the multi-axial and multi-stage seafloor spreading, westward propagating crustal extension, and the mantle geochemistry. These may imply their common origin. The South China Sea basin has a cuneiform shape. The seafloor spreading in the South China Sea and the rifting of its continental shelf were characterized by south-ward jumping and westward propagating development. The crustal extension decreased westward. These may be portrayed as a westward tipping scissors, whose opening was caused by the splitting of the East Asia conti-nental margin under approximately N-S oriented dextral shearing. Numerous N-S running dextral faults devel-oped in the Indochina Peninsula and within the South China Sea basin when it was opening, indicative of the existence of dextral stress at the time. The present eastern border of the South China Sea is occupied by a N-S running subduction zone, not a large dextral fault; this may be ascribed to the destruction of previous structure by the docking and obduction of the Philippine Archipelago along the present Manila trench. Since the Late Mesozoic, convergence toward Eurasia with various direction and speed occurred in the West Pacific domain, the Indian segment of the Tethys domain, and the Australian segment of the Tethys domain. These convergent forces competed and compounded each other, forming the geodynamic background for the development of " large shearing" in the margin of East Asia. This shearing was characterized by the alternative sinistral transcompression and dextral transtension, and might be driven by convergence-induced mantle flow. In the period when the influence of the India-Tibet convergence predominant, the East Asian margin was split under the stress field of dextral transtension, and then opened the South China Sea and other seas of the inner zone of the West Pacific margin

Abstract:Fission-track analysis indicates that the uplifting process of the northern segment of Altyn Tagh fault zone at the Aksay-Dangjin Pass since the Cenozoic can be divided roughly into three stages,43. 6~24. 3Ma,19. 6-13. 6 Ma and 9~7 Ma BP. The tectonic uplift of the Altyn Tagh fault zone related to the sinistral strike-slip movement in the Cenozoic occurred during 19. 6 -13. 6 Ma,and the uplift became rapid in 9~7 Ma BP, thus forming the Altun Mountains. The uplift was initiated in the early -middle Cenozoic (43. 6~24. 3 Ma) at a rate of 0. 227 mm/a;the second uplift occurred in the middle Cenozoic (19. 6~13. 6 Ma) at a rate of 0. 35 mm/a; and the third took place in the late Cenozoic (9-7 Ma)at an average rate of 0. 94 mm/a. The middle-late Cenozoic activation model shows that the fault zone appears to have undergone uplifting and sinistral strike-slip movement during 19. 6~13. 6 Ma; later it had sinistral strike-slip and thrust characters, giving rise to pull-apart basins after 9-7 Ma. The fission-track age of apatite from the eastern part of the Altyn Tagh fault zone is older than 30 Ma and that of apatite from the northern margin of the Qaidam Basin is 43. 6-24. 3 Ma, dif- ferent from the apatite fission-track ages of the Altyn Tagh fault zone. The age data of the samples taken from the Altyn Tagh fault zone on the northern margin of the Qaidam Basin indicate that the sinistral strike-slip movement along the fault zone seems not to have affected the uplifting of the northern margin of the Qaidam Basin. The middle-late Cenozoic tectonic uplift and sinistral strike-slip movement of the Altyn Tagh fault zone were related to the collision between thelndian and Eurasian plates and the tectonic uplift of Qinghai-Tibet Plateau.

Abstract:Chronological data show that two phases of basic volcanic activity appeared at about 2. 7 Ga and 2. 5 Ga in the North China craton in the Early Precambrian and represented two extensive crustal growth events respec-tively. Distribution and geochemical feature of basic volcanic rocks, and relationship and associations between basic volcanic rocks and other rocks suggest that the outpouring of basic volcanic rocks between landmasses in the Neoarchean increased crystal area, pieced the previously isolate mini - landmass together and caused the crustal growth. Within a landmass crust grew dominantly in the way of mantle plume. In the homogeneous part of the crust, where some magma intruded into the shallower crust and even spilt over the earth's surface, crust was mainly thickened in the way of underplating of basic magma. These two patterns of crustal growth, which supplemented each other, jointly resulted in the North China Paleocontinent of the end Archean.

Abstract:采用激光拉曼、阴极发光和电子探针技术,确认冀西北石榴角闪二辉麻粒岩锆石中保存早期高压变质包体矿物组合:石榴石(Grt)+单斜辉石(Cpx)+斜长石(Pl)+石英(Qtz)+金红石(Rt)、单斜辉石(Cpx)+斜长石(Pl)+石英(Qtz)和石榴石(Grt)+单斜辉石(Cpx)+斜长石(Pl)+石英(Qtz)。其中少量锆石具有继承性锆石的核,而多数锆石则形成于高压麻粒岩相变质阶段。利用TWQ方法限定石榴角闪二辉麻粒岩锆石中所保存的高压包体矿物组合的变质温度条件为750～820℃,压力为1.07～1.40 GPa。该项研究成果对于如何识别高压麻粒岩以及深入研究其成因机制均具有重要的科学意义。

Abstract:Zircons from the Taoyuanzhai volcanic rock, central Dabie orogenic belt, Anhui Province, are dated using conventional and SIMS (1270) U-Pb methods. The eruption age is given at 129-136 Ma, suggesting a Late Jurassic-Cretaceous volcanic event, as well as a volcanic basin in the area. It is also suggested that the tectonic environment was probably similar to that of the North Huaiyang in the north. According to the residual vol-canic topology, the height above sea and comparison to the thickness of volcanic sediments of the adjacent North Huaiyang Mesozoic volcanic basin, the erosion is estimated at about 3000 m in depth.

Abstract:The East Tianshan, located in northeastern Xinjiang and in the middle of Central Asia, has many tectono-magmatic belts connecting with those in Central Asia and is rich in metal deposits. Compressional collision be-tween Kazakhstan and the Tarim palaeoplate provided excellent conditions for mineralization and consequently a large number of endogentic metallic deposits were formed. The East Tianshan is one of the very important met-allogenic belts in China, the discovery of the Tuwu-Yandong large porphyry copper deposit is the most impor-tant breakthrough in mineral exploration in Xinjiang, and even in the whole China. It has good ore potentials. Based on the systematical records of metallogenic geological settings, characteristics of representative ore de-posits and late Palaeozoic geodynamic evolutions, four metallogenic series and seven mineralization types are rec-ognized. Late Palaeozoic crustal evolution went through the extension stage, compression stage, collision stage, post-collisional extension stage, strike-slip stage and partial extension stage, and each stage is accompanied by a type of ore deposit or a metallogenic series.

Abstract:The ductile shear zone type gold deposits refer to those whose ore-forming mechanism and ore-controlling factors are closely related to the ductile shear zone and its evolution. Different ductile shear zones are well devel-oped in the northern Altun area. The controls of ductile shear zone on gold deposits are as follows. (1) The re-gional distribution of gold deposits (and gold spots) is controlled by ductile shear zones. (2) The ductile-brittle shear zones formed in the evolution process of ductile shear zones both are as only ore-bearing structures and control the shape, attitude, scale and distribution of mineralization zones and orebodies. (3) The mechanical property of compression-shear ductile deformation determines that the main kind of gold mineralization is the al-tered mylonite type and main alteration is metasomatic. (4) Ore-bearing fracture systems are mainly P-type one and secondarily D-type and R-type ones, in adition R'-type and T-type one in one or two cases. (5) Dynamic differentiation and dynamic metamorphic hydrothermal solution resulting from ductile deformation is one of the sources of gold ore-forming fluids. And this is consistent with the idea drawn from the feature of fluid inclusion and geochemical characteristics of the deposit, i. e. ore-forming material resources are mainly from metamorphic rocks and ore-forming fluids are mainly composed of metamorphic water. (6) There is a negative correlation be-tween the gold abundance and susceptibility anisotropy (P) of the altered mylonite samples from the deposits, which shows that the gold mineralization is a little later than the structural deformation. All above further ex-pound the ore-forming model of the ductile shear zone type gold deposits.

Abstract:The CO2-rich fluid inclusion is often seen in the hypometamorphic mineral. Based on the systematical freezing and heating stage observation of fluid inclusions yet, we reveal that the primary fluid inclusion of the main ore-forming stage in the Jinding and periphery deposits are CO2-rich and hydrocarbon-bearing by laser Ro-manor microprobe researches, and the composition variation is evident. The CO2 vs hydrocarbon and CO2 vs H2O are negative-relation in the ore-forming fluid, respectively, and the hydrocarbon vs H2O is positive-rela-tion, and the composition of oxygen- and carbon-isotopes have been analyzed. It is suggested that the partial CO2 was from the mantle and the other from the decomposition of the carbonate rock and the organic matter within the strata, and the water and the hydrocarbon in the ore-forming fluid were mainly from meteorological basin brine and the stratum organic matter. The CO2-rich and hydrocarbon-bearing inclusion formed by selec tion trap of the mineral in the brine of CO2-hydrocarbon that did not dissolve each other completely. The mantle source CO2 may make a remarkable contribution on the transportation of the ore-forming metal from the mant-le , and the hydrocarbon played an important role on the metal precipitation. The ore-forming fluid is character-ized by the mixing of mantle source fluid (CO2- and metal-rich) and crust source fluid (the basin fluid is rich in hydrocarbon and water) , and it may suggest that the mixing of two types of fluids was a basic way of mineral-ization.

Abstract:In this paper an advanced fluid inclusion analysis technique was used to study the geochemical characteris-tics of hydrocarbon inclusions in the Yancheng depression. The results indicate that the source inputs come from lower aquatic algae and higher plants. The sedimentary environment was reducing and the salinity of the water medium was high. The hydrocarbons had been mature before they entered into the reservoirs. The petroleum filling history shows that at least two filling processes have occurred and the latter one was most significant. The filling periods were 55-12 Ma and 32-34 Ma, respectively. The hydrocarbons of the Yancheng depres-sion mainly came from Palaeozoic marine sapropelic materials, partly from the Taizhou or Pukou formation. Ex-tensional faults are the effective migration paths.

Abstract:通过调查藏北高原腹地盐湖——洞错的Ⅰ级阶地湖相化学沉积,首次发现硼砂及赋存5层纯芒硝层的完整沉积剖面,依据韵律层的沉积特征研究和~(14)C测年,针对剖面中出现的冷相盐类矿物——芒硝,应用比较盐湖学的理论和方法,指出洞错在全新世早、中期经历了潮湿温暖期(>8470 a BP,可能至10500 a BP±)→寒冷干旱期(8470～8170 a BP)→潮湿温暖期(8170～7590 a BP)→气候频繁波动期(7590～7400 a BP,寒冷大背景下三干三湿的气候演替)→寒冷干旱期(7400～6940 a BP)→潮湿温和期(6940～6620 a BP)→寒冷干旱期(6620～6410a BP)→温暖湿润期(6410 a BP以后)的演变序列。

Abstract:In the latest study of a section of the well core from the interior of the Qinghai-Xizang(Tibet) Plateau,the authors found the last 32 ka paleoclimatic change from the record of lake sediments of the Goulong Co in the Hoh Xil area by using the sequence stratigraphic and chronostratigraphic approaches, combined with the cli-matostratigraphic approach and recognized three climatic oscillation event of the Dryas period atdepths of 3. 32 to 1. 98 m of a well core, i. e. (1) the Oldest Dryas event (at well depths of 3. 32 to 2. 62 m), (2) the Older Dryas event (at 2. 62 to 2. 43 m) , and (3) the Younger Dryas event (at 2. 43 to 1. 98 m). All the three climat-ic oscillation events started with the dry and cold interval and ended with the cold and humid interval. The cold and dry interval became longer in the later part of the period, while the dry and humid stage shows a tendency of isochronic change. The variations of organic carbon, organic nitrogen, magnetic susceptibility and geochemi-cal element contents in core sediments all well coincide with the climatic change in the Dryas period. The re-sponse of the climate in the Dryas period in lake sediments is first discovered in the environmental evolution of the Qinghai-Tibet Plateau. This provides new information for the study of the climatic change since the deglaciation of the last glacial stage of the Quaternary.

Abstract:A lot of potholes are observed in the lower reaches of the Yellow River. According to their geneses, the potholes may be divided into six types; (1) flow-erosion; (2) wind-erosion; (3) circular boulder moulding; (4) ice-pressing; (5) ice-melt-water-erosion; (6)air-discharging erosion. The potholes formed by flow erosion are greatly varied in size: the small ones have a diameter of ten-odd centimetres and a depth of a few centimetre-s; and the large ones have a diameter of a few metres and a depth about one metre. Wind-erosion potholes are commonly small in size with their diameters no more than twenty to thirty centimetres, and their depths gener-ally below ten centimetres, and their walls gently plunged like a pot or dish. The potholes formed by casting of circular boulders are small in size, with a diameter below ten to twenty centimetres and sharply plunged walls. The Potholes formed by ice pressing are also small, with diameters ranging from ten to about thirty centimetres and depths less than ten centimetres, and have a relatively simple form. The potholes formed by ice melt water erosion have very complicated forms and variable sizes. They assume either dish-like forms with gently tilted walls or cylinder forms with almost vertical walls and their diameters ranging from several centimetres to thirty-forty centimetres. Secondary structures may often be found on their edges, walls and bottoms. There are four formation mechanisms of the ice-melt-water-erosion potholes. The potholes formed by air discharging erosion also have very complicated forms, which are considerably round to nearly round or other complicated forms. Their walls are gently or steeply plunged, with diameters from several to several tens of centimetres and depths from several millimetres to twenty-thirty centimetres, and commonly associated with secondary structures on edges and walls. They appear individually or in groups or gather like honeycombs. This type of potholes have a very unusual genesis, which is mainly related to the discharging air trapped by the riverbed during the Yellow River's zero flow period.