A semi-analytical theory of coastal upwelling and jet

The general forms of the conservation of momentum, temperature and potential vorticity of coastal ocean are obtained in the x-z plane for the nonlinear ocean circulation of Boussinesq fluid, and a elliptic type partial differential equations of second order are derived. Solution of the partial differential equations are obtained under the conditions that the fluid moves along the topography. The numerical results show that there exist both upwelling and downwelling along coastline that mainly depends on the large scale ocean condition. Numerically results of the upwelling (downwelling), coastal jet and temperature front zone are favorable to the observations.

Effect of Stokes drift on upper ocean mixing

Stokes drift is the main source of vertical vorticity in the ocean mixed layer. In the ways of Coriolis - Stokes forcing and Langmuir circulations, Stokes drift can substantially affect the whole mixed layer. A modified Mellor-Yamada 2.5 level turbulence closure model is used to parameterize its effect on upper ocean mixing conventionally. Results show that comparing surface heating with wave breaking, Stokes drift plays the most important role in the entire ocean mixed layer, especially in the subsurface layer. As expected, Stokes drift elevates both the dissipation rate and the turbulence energy in the upper ocean mixing. Also, influence of the surface heating, wave breaking and wind speed on Stokes drift is investigated respectively. Research shows that it is significant and important to assessing the Stokes drift into ocean mixed layer studying. The laboratory observations are supporting numerical experiments quantitatively.

Density-dependent effects on seston dynamics and rates of filtering and biodeposition of the suspension-cultured scallop Chlamys farreri in a eutrophic bay (northern China): An experimental study in semi-in situ flow-through systems

Effects of stocking density on seston dynamics and filtering and biodeposition by the suspension-cultured Zhikong scallop Chlamys farreri Jones et Preston in a eutrophic bay (Sishili Bay, northern China), were determined in a 3-month semi-field experiment with continuous flow-through seawater from the bay. Results showed that the presence of the scallops could strongly decrease seston and chlorophyll a concentrations in the water column. Moreover, in a limited water column, increasing scallop density could cause seston depletion due to scallop's filtering and biodeposition process, and impair scallop growth. Both filtration rate and biodeposition rate of C. farreri showed significant negative correlation with their density and positive relationship with seston concentration. Calculation predicts that the daily removal of suspended matter from water column by the scallops in Sishili Bay ecosystem can be as high as 45% of the total suspended matter; and the daily production of biodeposits by the scallops in early summer in farming zone may amount to 7.78 g m(-2), with daily C, N and P biodeposition rates of 3.06 x 10(-1), 3.86 x 10(-2) and 9.80 x 10(-3) g m(-2), respectively. The filtering and biodeposition by suspension-cultured scallops could substantially enhance the deposition of total suspended particulate material, suppress accumulation of particulate organic matter in water column, and increase the flux of C, N and P to benthos, strongly enhancing pelagic-benthic coupling. It was suggested that the filtering-biodeposition process by intensively suspension-cultured bivalve filter-feeders could exert strong top-down control on phytoplankton biomass and other suspended particulate material in coastal ecosystems. This study also indicated that commercially suspension-cultured bivalves may simultaneously and potentially aid in mitigating eutrophication pressures on coastal ecosystems subject to anthropogenic N and P loadings, serving as a eutrophic-environment bioremediator. The ecological services (e.g. filtering capacity, top-down control, and benthic-pelagic coupling) functioned by extractive bivalve aquaculture should be emphasized in coastal ecosystems. (c) 2005 Elsevier B.V. All rights reserved.

GEO-ECOLOGICAL TRANSECT STUDIES IN NORTHEAST TIBET (QINGHAI, CHINA) REVEAL HUMAN-MADE MID-HOLOCENE ENVIRONMENTAL CHANGES IN THE UPPER YELLOW RIVER CATCHMENT CHANGING FOREST TO GRASSLAND

Geo-ecological transect studies in the pastures of the upper catchment of the HuangHe (99 degrees 30'-100 degrees 00'E/35 degrees 30'-35 degrees 40'N'; 3,000-4,000 in a.s.l., Qinghai province, China) revealed evidence that pastures replace forests. Plot-based vegetation records and fenced grazing exclosure experiments enabled the identification of grazing indicator plants for the first time. The mapping of vegetation patterns of pastures with isolated juniper and Spruce forests raise questions as to the origin of the grasslands, which arc widely classified as "natural" at present. Soil investigations and charcoal fragments of Juniperus (8,153 +/- 63 uncal BP) and Picea (6,665 +/- 59 uncal BP) provide evidence of the wider presence of forests. As temperatures and rainfall records undoubtedly represent a forest climate, it is assumed that the present pastures have replaced forests. Circumstantial evidence arising from investigations into the environmental history of the Holocene effectively substantiates this theory.

Genetic diversity of the subterranean Gansu zokor in a semi-natural landscape

We studied the relationship between genetic diversity of the subterranean Gansu zokor Myospalax cansus and habitat variability in the Loess Plateau, Qinghai Province, China. We used a combination of geographic information systems and molecular techniques to assess the impact of habitat composition and human activities on the genetic diversity of zokor populations in this semi-natural landscape. Although they occurred relatively infrequently in the landscape, woodland and high-coverage grassland habitats were the main positive contributors to the genetic diversity of zokor populations. Rural residential land, plain agricultural land and low-coverage grassland had a negative effect on genetic diversity. Hilly agricultural land and middle-coverage grassland had little impact on zokor genetic diversity. There were also interactions between some habitat types, that is, habitat types with relatively better quality together promoted conservation of genetic diversity, while the interaction between (among) bad habitat types made situations worse. Finally, habitat diversity, measured as patch richness and Shannon's diversity index, was positively correlated with the genetic diversity. These results demonstrated that: (1) different habitat types had different effects on the genetic diversity of zokor populations and (2) habitat quality and habitat heterogeneity were important in maintaining genetic diversity. Habitat composition was closely related to land use thus emphasizing the importance of human activities on the genetic diversity of subterranean rodent populations in this semi-natural landscape. Although the Gansu zokor was considered to be a pest species in the Loess Plateau, our study provides insights for the management and conservation of other subterranean rodent species.

Depression of net ecosystem CO2 exchange in semi-arid Leymus chinensis steppe and alpine shrub

Uptake and release of carbon in grassland ecosystems is very critical to the global carbon balance and carbon storage. In this study, the dynamics of net ecosystem CO2 exchange (FNEE) of two grassland ecosystems were observed continuously using the eddy covariance technique during the growing season of 2003. One is the alpine shrub on the Tibet Plateau, and the other is the sem-arid Leymus chinensis steppe in Inner Mongolia of China. It was found that the FNEE of both ecosystems was significantly depressed under high solar radiation. Comprehensive analysis indicates that the depression of FNEE in the L. chinensis steppe was the results of decreased plant photosynthesis and increased ecosystem respiration (R-eco) under high temperature. Soil water stress in addition to the high atmospheric demand under the strong radiation was the primary factor limiting the stomatal conductance. In contrast, the depression of FNEE in the alpine shrub was closely related to the effects of temperature on both photosynthesis and ecosystem respiration, coupled with the reduction of plant photosynthesis due to partial stomatal closure under high temperature at mid-day. The R,c of the alpine shrub was sensitive to soil temperature during high turbulence (u* > 0.2 m s(-1)) but its FNEE decreased markedly when the temperature was higher than the optimal value of about 12 degrees C. Such low optimal temperature contrasted the optimal value (about 20 degrees C) for the steppe, and was likely due to the acclimation of most alpine plants to the long-term low temperature on the Tibet Plateau. We inferred that water stress was the primary factor causing depression of the FNEE in the semi-arid steppe ecosystem, while relative high temperature under strong solar radiation was the main reason for the decrease of FNEE in the alpine shrub. This study implies that different grassland ecosystems may respond differently to climate change in the future. (c) 2006 Elsevier B.V All rights reserved.

Meat characteristics of Qinghai yak and semi-wild yak

Six domestic yaks aged 6 years, comprising three culling male and three culling female yaks, from the Qinghai Lake area and three male semi-wild yaks aged 6 months from Datong Yak Farm were used to detect the levels of amino acids, mineral elements, residual heavy metals and pesticides in yak meat. The results showed that there was little difference in amino acid levels for different types of yak by age and sex. The meat of the adult male yak was 7.35 mg/kg higher in calcium (P < 0.05) and 124 mg/kg higher in phosphorus (P < 0.01) than that of the adult female yak. There was an obvious difference in zinc content, and there was also a significant difference for copper and sulfur between adult male and female yaks (P < 0.01). Iron was 8.85 mg/kg higher in semi-wild yaks than in domestic yaks, but there were no differences for other minerals. The levels of residual heavy metals and residual pesticides were well within those allowed by the National Standard of China. Furthermore, the data showed that introducing wild yak's blood did not result in a quality change in the domestic yak meat. Yak meat from Qinghai Plateau has the characteristics of being non-polluted and rich in amino acids in comparison with local yellow cattle meat.

高邮凹陷陈堡及陈堡东地区油气成藏规律研究

With the development of petroleum exploration in Gaoyou Depression, both old and new areas have been the active exploration targets, so the study of petroleum accumulation is significant to the petroleum exploration in the study area and the integrated oil and gas accumulation theory. Based on hydrocarbon accumulation theory and systematical research methods and combined with the structural characteristics of Gaoyou Depression, Chenbao and East of Chenbao were selected as the study areas in this dissertation, oil and gas migration pathways, accumulation periods, as well as accumulation models were studied, and favorable exploration targets were proposed. There develop three sets source rocks, which are Tai-2 Member, Fu-2 Member and Fu-4 Member respectively. Tai-2 Member is the predominant source rock in the eastern part. Fu-2 Member mainly occurs in the northern slope, while Fu-4 Member develops in the deep depression. In the study area, oil mainly comes from Fu-2 Member of Liuwushe subsag. The lower limit of TOC is 0.4%, and active source rock mostly distributed in the south fault-step zone. The source rock in Liuwushe subsag began to generate hydrocarbon in the late of Dainan depositional stage and the threshold was 2300m. The macro and micro characteristics of reservoirs and the reservoir heterogeneity characteristics of the Fu-1 Member were studied systematicly. The results show that Fu-1 Member, which has better reservoir properties, are medium porosity-medium permeability reservoir. The reservoir permeability has good correlation with porosity connectivity. The reservoirs have strong dissolution, pores are mainly thin to medium throat, and throat radii are distributed concentratedly, the sorting is good and pore structures are homogeneous. Sandstone reservoirs whether in the plan view, interlayer or in layers have a certain degree of heterogeneity, in particular, the heterogeneity in layers directly affect and control the oil and gas migration and accumulation. By analyzing the lithology correlation of the fault walls, shale smear, cross section stress, the configuration of fracture active periods and hydrocarbon generation and expulsion periods and fuzzy comprehensive evaluation, the main faults sealing were evaluated. The results show that the faults in Chenbao and East of Chenbao had poor sealing properties in Sanduo period and could be used as the migration pathways at that time. After Sanduo period, the tectonic stress fields in the area changed largely, and, consequently, the fault properties converted from tensional shear to compressive shear, the faults changed progressively from close to open, so the faults sealing became better and were conducive to the preservation of oil and gas reservoirs. According to the seismic event suspension modes and profile configurations above and under the unconformities, combined with tectonic evolutions of the study areas, the unconformity types can be classified into truncation unconformity, overlapped unconformity and parallel unconformity and the distribution characteristics of unconformities in the plan view was also studied. The unconformity structure was divided into basal conglomerate, weathered clay and semi-weathered layer vertically in the study area and this kind of structure make unconformities to be effective oil and gas migration pathways and is significant to hydrocarbon accumulation in a parts of areas. With the analyses of typical oil and gas reservoirs in the study area, combined with the research results of pathway systems, hydrocarbon accumulation models were established and the oil and gas accumulation laws in Chenbao and East of Chenbao analyzed. The oil and gas came from Liuwushe subsag and Liuliushe subsag. The oil and gas from Liuwushe subsag mainly migrated from the structural high parts into the fault-step zone along strata in northeast direction, a part of them migrated upward into the fault-step zone and the Wubao low uplift along Wu-1 Fault in northeast direction. The oil and gas from Liuliushe subsag mainly migrated into the upper reservoirs through Wu-2 fault, and lesser oil and gas migrated into the fault-step zone because of the controls of cross-section orientation, depression center and the hydrocarbon formation tendency. The favorable exploration targets in Chenbao and East of Chenbao have been concluded: the southern fault-step zone is a favorable oil and gas accumulation zone of Liuwushe subsag, and they are fault block reservoirs where fault acted as the barriers, the main target intervals are Fu-1 Member and Fu-3 Member in palaeocene; Oil and gas in the middle and northern fault-step zone mainly laterally migrated from the south areas, and the main target interval is Fu-3 Member in palaeocene; Fu-1 Member and the reserviors above the Wubao subsag are still the focuses in future explorations. The results of this study have important guiding significance for the future oil and gas exploration.

子洲—清涧地区上古生界储层综合研究

The exploration and study in recent years shows that the upper Paleozoic in the east of Ordos Basin possesses major exploration potential, so it is necessary to have a comprehensive and synthetic research in this area. Following the guideline of T.A. Cross’s high resolution sequences stratigraphy and combined with sedimentology, the strata and sequence in the research area are divided and correlated. This paper emphasizes on the reservoir in this area and its major fruits are: Firstly, form the framework of the high sequence stratigraphy through mainly studying on the data of core, well drilling and field section combining. Then, think that the best reservoir formation mainly appears in the middle or lower part of long arising semi-cycle, and focus on A type and C1 middle sequence cycle that contributes to the development of formation. Next, think the sedimentary source mainly comes from the epimetamorphic crystalline basement in the north of the Ordoes Basin through analyzing depositional background, researching on sandstone petrography, distribution characteristics of the sedimentary system as well as researching on heavy mineral combination characteristics. Fourthly, give priority to Zizhou-Qingjian area for the first time and gain seven lithofacies paleography maps in the No.2 member of Shanxi and the No.8 member of Shihezi through using the method of isochronal lithofacies paleogeography mapping, then bring forth that Sh2 is mainly developed a type I sequence under the margin of ramp lake-basin background. Fifthly, through researching on the characteristics of reservoir petrography and diagenesis, think that all researched areas experienced compaction and cementation, and there is different types of rocks, only little of the primary pores that are made up of litharenite and lithoclastic quartz sandstone is left, while in lithoclastic quartz sandstone, there are still many primary pores Sixthly, through studying on pore types, microstructure, as well as physical property on the key formation, think that the researched area mostly appears typical low pore, low porosity and permeability, which mainly result from sedimentary and diagenesis. Lastly, through researching on classified evaluation in the key formation, productivity analysis, and combing with reservoir distribution, the researched area is divided into three parts, and think that exploration should be emphasized on formation I and II. The characteristics of sandstones distribution in Sh23 member, gas formation distribution and open flow capacity of exploitation well are all consistent properly with the results of reservoir comprehensive evaluation in this thesis proved by the gas production development in 2006.

急倾斜金属矿体开采岩体移动规律与变形趋势预测研究

Rockmass movement due to mining steep metallic ore body is a considerable question in the surface movement and deformation issue caused by underground mining. Research on coal mining induced rockmass movement and its prediction problem have been performed for a long-term, and have achieved great progress at home and abroad. However, the rockmass movement caused by mining steep metal mine is distinctivly different from coal seam mining.. Existing surface movement laws and deformation prediction methods are not applicable to the rockmass movement caused by mining steep metal mine. So far the home and abroad research to this theory is presently at an early stage, and there isn’t mature theory or practical prediction method, which made a great impact on production. In this paper, the research object—Jinchuan nickel mine, which is typical steep metal mine, characterized by complex geological conditions, developed faults, cracked rockmass, high geostress, and prominent engineering stability problems. In addition, backfill mining method is used in the mine, the features of rockmass movement caused by this mining method are also different from other mining methods. In this paper, the laws of rock mass movement, deformation and destroy mechanism, and its prediction were analyzed based on the collection of data, detailed in-sit engineering geology survey, ground movement monitoring by GPS, theoretical analysis and numerical simulation. According to the GPS monitoring of ground surface movement, ground subsidence basin with apparent asymmetry is developing, the influence scope is larger in the upper faulted block than in the lower faulted block, and the center of ground movement is moving along the upper faulted block direction with increasing depth of mining. During the past half and seven years, the largest settlement has amounted to 1287.5mm, and corresponding horizontal displacement has amounted to 664.6mm. On the ground surface, two fissure belts show a fast-growing trend of closure. To sum up, mining steep metal mine with backfill method also exist the same serious problem of rockmass movement hazards. Fault, as a low intensity zone in rockmass, when it located within the region of mining influence, the change of potential energy mainly consumed in fault deformation associated with rockmass structure surface friction, which is the essence of displacement and stress barrier effects characterized by fault rupture zone. when steep fault located in the tensile deformation region incurred by underground excavation, no matter excavation in hangingwall or in footwall of the fault, there will be additional tensile stress on the vertical fault plane and decrease in the shear strength, and always showing characteristics of normal fault slip, which is the main reason of fault escarpment appeared on the ground surface. The No.14 shaft deformation and failure is triggered by fault activation, which showed with sidewall move, rupture, and break down features as the main form of a concentrated expression of fault effects. The size and orientation of principal stress in surrounding rock changed regularly with mining; therefore, roadway deformation and damage at different stages have different characteristics and distribution models. During the process of mining, low-intensity weak structures surface always showed the most obvious reaction, accompany with surface normal stress decrease and shear strength bring down, to some extent, occurred with relative slide and deformation. Meanwhile, the impact of mining is a relatively long process, making the structure surface effect of roadway deformation and damage more prominent than others under the influence of mining. Roadway surrounding rockmass deformation caused by the change of strain energy density field after excavation mainly belongs to elastic deformation, and the correspondented damage mainly belongs to brittle rupture, in this circumstance, surrounding rockmass will not appear large deformation. The large deformation of surrounding rockmass can only be the deformation associated with structure surface friction or the plastic deformation of itself, which mainly caused by the permanent self-weigh volume force，and long-term effect of mining led to the durability of this deformation Good pitting fill effect and supporting effect of backfill, as well as the friction of rockmass structure surface lead to obvious macro-rockmass movement with long-lag characteristics. In addition, the loss of original intensity and new structure surface arisen increased flexibility in rockmass and fill deformation in structure surface, which made the time required for rockmass potential energy translate into deformation work associated with plastic deformation and structure surface friction consumed much, and to a large extent, eliminated the time needed to do those plastic work during repeated mining, all of which are the fundamental reason of rockmass movement aftereffect more significant than before. Mining steep deposits in high tectonic stress area and in gravity stress area have different movement laws and deformation mechanism. The steep deposit, when the vertical size of the mining areas is smaller than the horizontal size of the orebody, no matter mining in gravity stress area or in high tectonic stress area, they have similar features of ground movement with mining horizontal orebody; contrarily, there will appear double settlement centers on the ground surface under the condition of mining in high tectonic stress area, while there will always be a single center under the other condition. Meanwhile the ground movement lever, scale of mining influence area and macro features of ground movement, deformation and fracture are also different from mining in gravity stress area, and the fundamental reason lies in the impact of orientation of the maximum principal stress on rock movement features in in-site rock stress field. When mining thick and steep deposit, the ground surface movement and deformation characteristic curves are significantly different from excavating the horizontal ore bed and thin steep deposit. According to the features of rockmass movement rate, the development process of mining-induced rockmass movement is divided into three stages: raising stage, steadily stage and gradually decay stage. Considering the actual exploitation situation, GPS monitoring results and macro-characteristics of surface movement, the current subsidence pattern of Jinchuan No.2 mine is in the early stage of development. Based on analysis of surface movement rate, surface subsidence rate increase rapidly when mining in double lever at the same time, and reach its peak until the exploitation model ended. When double lever mining translate into single, production decreased, surface subsidence rate suddenly start to reduce and maintain a relatively low value, and the largest subsidence center will slowly move along with the hangingwall ore body direction with increasing depth of mining, at the same time, the scope and extent of subsidence in footwall ore body will begin magnify, and a sub-settlement center will appear on ground surface, accompanied with the development and closure trend of ground fissure, the surrounding rockmass of shaft and roadway will be confronted to more frequent and severe deformation and failure, and which will have a negative impact on the overall stability of No.2 mine mining. On the premise of continuity of rockmass movement, gray system model can be used in ground rockmass movement prediction for good results. Under the condition of backfill mining step by step, the loose effect of compact status of the hard, broken rockmass led to lower energy release rate, although surrounding rockmass has high elastic energy, loose and damage occurred in the horizontal ore body, which made the mining process safety without any large geological hazards. During the period of mining the horizontal ore body to end, in view of its special “residual support role”, there will be no large scale rockmass movement hazards. Since ground surface movement mainly related to the intensity of mining speed and backfill effect, on the premise of constant mining speed, during the period of mining the horizontal ore body to end, the rate of ground surface rockmass movement and deformation won’t have sudden change.

大别－苏鲁造山带与华北陆块东部岩石层三维速度结构

The 3-D velocity images of the crest and upper mantle beneath the region of 112° -124°E, 28°-39°N including the Dabie-Sulu orogenic belt are reconstructed by using 36405 P-wave arrivals of 3437 regional and 670 distant earthquakes during the period from 1981 to 1996, and gridding the area of 0.5° * 0.5°. The results of tomography demonstrate that: 1. The results of tomographic imaging show a broad heterogeneity in P wave velocity structure for the lithosphere beneath the Dabie-Sulu orogenic belt. 2. In the Dabie orogenic belt, the velocity patterns in the crust are different among various tectonic units. The Dabie and Qinling orogenic belts are remarkable in the tomographic images, and in mm the Hongan and Dabie blocks in the Dabie orogenic belt are also imaged very distinguishably. 3. A velocity (about 5.9～6.0 km/s) layer exists in the Dabie block at depth between 15～25 km, which is coincident with the low-resistance layer at the depth of 12-23 km, being inferred to be the tectonic detachment zone and suggesting that the extension detachment structure was formed in the middle crust. Beneath the southern and northerm Dabie tectonic units, the north-dipping high-velocity (at level of 6.5 ～ 6.6 km/s) block was developed in the crust, which might be correlated with the UHP rockswith low content of the meta-ultramafic rocks. This result is in agreement with the geological observation on the surface. 4. The velocity image at 40 km depth reveals the features at the top of mantle and the configuration of the Moho discontinuity. The depth of the Moho changes slightly along the trend of the orogenic belt. It in Hongan block is less than 40 km, but it is different in the western and eastern parts of the Dabie block, the former is more than 40 km, and the latter less than or equal to 40 km. The remnant of the mountain root exists between the Shangcheng-Macheng fault and the line of Huoshan-Yuexi-Yingshan in the Dabie orogenic belt, and beneath the southern and northern Dabie tectonic units. However, the thickness of the Moho is about 40 km and there is no obvious changes, which suggest that the Dabie orogenic belt has been experienced quite in the gravity equilibration. The Moho's depth in the Sulu is less than 40 km. 5. There is a dipping slab-like high-velocity body in the uppermost mantle. It is sandwiched by slow velocities and exists beneath the Dabie-Sulu orogenic belt in the range of depths between the Moho discontinuity and 110 km at least. This high-velocity body outlines a picture of the slab interpreted as the remnant of the Triassic subducted YZ. 6. The Sulu orogenic belt displays "crocodilian" velocity structure, the upper crust of the Yangtze thrusted over the Huabei crest, and the Huabei crust indented into the Yangtze crust, where the ancient subduction zone of the Yangtze lithosphere located. Based on the previous geological data, this structure is not related with the collision between the Yangtze and Sino-Korean Blocks, but caused by the sinistral offset of the Tan-Lu Fault. Studied on the velocity structure of the eastern Huabei lithosphere indicates: 1. The 'present-day' lithosphere of the eastern Huabei is between 40-100 km thick with greatly thinned lithosphere around the Bohai Sea. Generally, thickness of the lithosphere in this region decreased eastwards. 2. The attenuation of the lithosphere is attributed to the strongly uplift of the asthenosphere. In the area between the Taihang Mountains and the Tan-Lu Fault, there is a 'lever' with red low velocity belt, it is clearly defined, transverse continuity, depth between 100-150 km, local variations visible, and an upwards trend towards the Bohai Sea. Generally, the velocity structure in the mantle beneath the lithosphere displays irregular column-shape consisting of alternating high and low velocities, and when cold high velocity ancient lithosphere connects with the hot low velocity mantle materials forming precipitous compact structure. More heat pathways from the mantle occur towards the Tan-Lu Fault. 3. The strongly irregular characteristics of the contact between the asthenosphere and the lithosphere is induced by the long-term hot, chemical erosion and alteration on the contact. 4. There are still preserved high velocity lithosphedc root beneath Huabei with 'block-shape' distribution and surrounded by hot materials. Results of our studies indicate that the evolution models of the eastern China mantle are characterized by the direct contact between the uplifted lithosphere and the Huabei Craton accompanying the upwelling of the deep mantle materials. At the contact betwen the lithosphere and the asthenosphere, the upwelled mantle materials replaced and altered the lower lithosphere forming the metasome through the hot and chemical modifications impacted on the Craton lithosphere, and changed it into the lithosphere gradually, resulting in the lithospheric thinning. Thus, the lithospheric thinning is the result of the upwelling of the asthenosphere.

东海陆架盆地西南部烟囱构造与油气运聚关系研究

In recent years, chimney structure has been proved one of important indicators and a useful guide to major petroleum fields exploration through their exploration history both at home and abroad. Chimney structure, which has been called "gas chimney" or "seismic chimney", is the special fluid-filled fracture swarm, which results from the boiling of active thermal fluid caused by abruptly decreasing of high pressure and high temperature in sedimentary layers of upper lithosphere. Chimney structure is well developed in continental shelf basin of East China Sea, which indicates the great perspectives of petroleum resources there. However, the chimney structure also complicated the petroleum accumulation. So the study of chimney structure on its formation, its effect on occurrence and distribution of petroleum fields is very important not only on theoretical, but also on its applied research. It is for the first time to make a clear definition of chimney structure in this paper, and the existence and practical meaning of chimney structure are illustrated. Firstly, on the viewpoint of exploration, this will amplify exploration area or field, not only in marine, but also on continent. Secondly, this is very important to step-by-step exploration and development of petroleum fields with overpressure. Thirdly, this will provide reference for the study on complex petroleum system with multi-sources, commingled sources and accumulation, multi-stage accumulations, and multi-suits petroleum system in the overlay basin. Fourthly, when the thermal fluid enters the oceanic shallow layer, it can help form gas hydrate under favorable low-temperature and high-pressure conditions. Meanwhile, the thermal fluid with its particular component and thermal content will affect the physical, chemical and ecological environments, which will help solving the problem of global resources and environment. Beginning from the regional tectonic evolution characteristics, this paper discussed the tectonic evolution history of the Taibei depression, then made an dynamical analysis of the tectonic-sedimentary evolution during the Mesozoic and Cenozoic for the East China Sea basin. A numerical model of the tectonic-thermal evolution of the basin via the Basin-Mod technique was carried out and the subsidence-buried history and thermal history of the Taibei depression were inverse calculated: it had undergone a early rapid rift and sag, then three times of uplift and erosion, and finally depressed and been buried. The Taibei depression contains a huge thick clastic sedimentary rock of marine facies, transitional facies and continental facies on the complex basement of ante-Jurassic. It is a part of the back-arc rifting basins occurred during the Mesozoic and Cenozoic. The author analyzed the diagenesis and thermal fluid evolution of this area via the observation of cathodoluminescence, scanning electron microscope and thin section, taking advantage of the evidences of magma activities, paleo-geothermics and structural movement, the author concluded that there were at least three tectonic-thermal events and three epochs of thermal-fluid activities; and the three epochs of thermal-fluid activities were directly relative to the first two tectonic-thermal events and were controlled by the generation and expulsion of hydrocarbon in the source rock simultaneously. Based on these, this paper established the corresponding model between the tectonic-thermal events and the thermal-fluid evolution of the Taibei Depression, which becomes the base for the study on the chimney structures. According to the analyses of the gas-isotope, LAM spectrum component of fluid inclusion, geneses of CO_2 components and geneses of hydrocarbon gases, the author preliminarily verified four sources of the thermal fluid in the Taibei Depression: ① dehydration of mud shale compaction, ② expulsion of hydrocarbon in the source rock; ③ CO_2 gas hydro-thermal decomposition of carbonatite; ④magma-derived thermal fluid including the mantle magma water and volatile components (such as H_2O, CO_2, H_2S, SO_2, N_2 and He etc.). On the basis of the vitrinite reflectance (Ro), homogenization temperature of fluid inclusion, interval transit time of major well-logging, mud density of the wells, measured pressure data and the results of previous studies, this paper analyzed the characteristics of the geothermal fields and geo-pressure fields for the various parts in this area, and discussed the transversal distribution of fluid pressure. The Taibei depression on the whole underwent a temperature-loss process from hot basin to cold basin; and locally high thermal anomalies occurred on the regional background of moderate thermal structure. The seal was primarily formed during the middle and late Paleocene. The overpressured system was formed during the middle and late Eocene. The formation of overpressured system in Lishui Sag underwent such an evolutionary process as "form-weaken-strengthen-weaken". Namely, it was formed during the middle and late Eocene, then was weakened in the Oligocene, even partly broken, then strengthened after the Miocene, and finally weakened. The existence of the thermal fluid rich in volatile gas is a physical foundation for the boiling of the fluid, and sharply pressure depletion was the major cause for the boiling of the fluid, which suggests that there exists the condition for thermal fluid to boil. According to the results of the photoelastic simulation and similarity physical experiments, the geological condition and the formation mechanism of chimnestructures are summarized: well compartment is the prerequisite for chimney formation; the boiling of active thermal fluid is the original physical condition for chimney formation; The local place with low stress by tension fault is easy for chimney formation; The way that thermal fluid migrates is one of the important factors which control the types of chimney structures. Based on where the thermal fluid come from and geometrical characteristics of the chimney structures, this paper classified the genetic types of chimney structures, and concluded that there existed three types and six subtypes chimney structures: organic chimney structures generated by the hydrocarbon-bearing thermal fluid in middle-shallow layers, inorganic and commingling-genetic chimney structures generated by thermal fluid in middle-deep layers. According to the seismic profiles interpretations, well logging response analysis and mineralogical and petrological characteristics in the study area, the author summarized the comprehensive identification marks for chimney structures. Especially the horizon velocity analysis method that is established in this paper and takes advantage of interval velocity anomaly is a semi-quantitative and reliable method of chimney structure s identification. It was pointed out in this paper that the occurrence of the chimney structures in the Taibei depression made the mechanism of accumulation complicated. The author provided proof of episodic accumulation of hydrocarbon in this area: The organic component in the boiling inclusion is the trail of petroleum migration, showing the causality between the boiling of thermal fluid and the chimney structures, meanwhile showing the paroxysmal accumulation is an important petroleum accumulation model. Based on the evolutionary characteristics of various types of chimney structures, this paper discussed their relationships with the migration-accumulation of petroleum respectively. At the same time, the author summarized the accumulating-dynamical models associated with chimney structures. The author analyzed such accumulation mechanisms as the facies state, direction, power of petroleum migration, the conditions of trap, the accumulation, leakage and reservation of petroleum, and the distribution rule of petroleum. The author also provides explanation for such practical problems the existence of a lot of mantle-derived CO_2, and its heterogeneous distribution on plane. By study on and recognition for chimney structure, the existence and distribution of much mantle-derived CO_2 found in this area are explained. Caused by tectonic thermal activities, the deep magma with much CO_2-bearing thermal fluid migrate upward along deep fault and chimney structures, which makes two wells within relatively short distance different gas composition, such as in well LF-1 and well LS36-1-1. Meanwhile, the author predicted the distribution of petroleum accumulation belt in middle-shallow layer for this area, pointed out the three favorable exploration areas in future, and provided the scientific and deciding references for future study on the commingling-genetic accumulation of petroleum in middle-deep layer and the new energy-gas hydrate.

东营凹陷辛镇复杂断块油藏形成机制和剩余油分布规律研究

In this paper, the complex faulted-block oil reservoir of Xinzhen area in Dongying depression is systematically studied from basic conditions forming faulted-block oil and gas reservoir integrating geology, seismic, logging and reservoir engineering information and computer; guided by petroleum geology, geomechanics, structural geology and geophysics and other theories. Based on analysis of background condition such as regional strata, structure and petroleum geology, structural research on geometry, kinemaitcs and dynamics, oil-controlling fault research on the seal features, sealing mechanism and sealing pattern, and research on enrichment rules and controlling factors of complex faulted-block oil reservoir are carried out to give out the formation mechanics of oil reservoir of Xinzhen complex faulted-block oil reservoir. As a result, the reservoir formation pattern is established. At the same time, through dissecting the characteristics and hydrocarbon enrichment law of complex faulted-block oil reservoir, and studying its distribution law of remaining oil after entering extra high water-cut period, a set of technologies are formed to predict complex faulted-block oil reservoir and its remaining oil distribution and to enhance oil recovery (EOR). Based on the time relationship between migration of hydrocarbon and trap formation, accumulating period of Xinzhen oil reservoir is determined. The formation of Xinzhen anticlinal trap was prior to the primary migration. This is favorable to formation of Xinzhen anticlinal hydrocarbon reservoir. Meanwhile, because anticline top caving isn't at the sane time as that of moving or faulted-trap forming inner anticline, oil and gas migrated many times and Xinzhen complex faulted-block oil reservoir formed from ES_3~(upper) to EG. Accumulating law and controlling factors of complex faulted-block reservoir are analyzed from many aspects such as regional structure background controlling hydrocarbon accumulating, plastic arch-open structure controlling oil-bearing series and reservoir types, sealing-opening of fault controlling hydrocarbon distribution and structure pattern controlling enriched trap types. Also, we established the structure pattern in Xinzhen a'ea: the arch-open of underlying strata cause expanding fracture. The main block groups developed here are shovel-like normal fault block group in the north area of Xinzhen and its associated graben block group. Block groups dominate the formation and distribution of reservoirs. We studied qualitatively and quantitatively the sealing characteristics, sealing history and sealing mechanism of faults, too. And, the sealing characteristics are evaluated and the distribution pattern of hydrocarbon controlled by faults is researched. Due to movement intensity of big faults, deep falling of downthrown block, high degree of repture and development of fracture, shallow layers close to the downthrown block of secondary faults are unfavorable to hydrocarbon accumulation. This is confirmed by the exploration practice in Xinzhen anticline. In terms of the downthrown blocks of sencondary contemporaneous faults lied in the south and north area of Xinzhen, hydrocarbon is poor close to fracture belt, while it is relatively abundant in tertiary companion faults. Because of long-term movement of faults that control hydrocarbon, fi'om ES3 to EG, six set of oil-bearing series formed. And their opening causes the inhomogeneity in hydrocarbon abundance among each block--in two flanks of anticline reservoirs are abundant while in the axial area, oil and gas are sporadic. There the sealing characteristics control oil-bearing area of oil/gas accumulation and the height of oil reservoir. Longitudinally, oil and gas are enriched in dip-flat areas in mid-plane of faults. It is established that there are four types of accumulating patterns in complex faulted-block oil reservoirs in Xinzhen. The first is accumulating pattern of lithologic oil reservoirs in E~S_3~(mid-lowwer), that is, self-generating-self-reserving-self-covering lithologic trap pattern. The second is drag-anticline accumulating pattern in Xinzhen. The structure traps are drag anticlines formed by the contemporaneous faults of the second basement in the north of Xinzhen, and the multiple source rocks involve Ek_2, Es_4, Es_3 and Es_1 members. The reservoirs are fluvial-delta sandstones of the upper member of Shahejie formation and Guantao formation, covered by regional thick mudstone of the upper member of Guantao formation and MingHuazhen formation. The third is the accumulating pattern of reverse listric fault, the third-degree fault of Xinzhen anticline limb and the reservoirs form reservoir screened by reverse listric faults. The forth is accumulating pattern of crossing faults which form closing or semi-closing faulted-blocks that accumulate hydrocarbon. The technologies of predicting remaining oil in complex faulted-block reservoir during the mid and late development stage is formed. Remaining oil in simple large faulted-blocks enriches in structural high, structural middle, structural low of thick bottom water reservoirs, points near bent edge-fault oftertiary faults and part the fourth ones with big falling displacement, microstructure high place of oil-sandbodies and areas where local well pattern isn't perfect. While that in small complex faulted-blocks enriches near small nose, small high point, angle of small faults, small oil-bearing faulted-blocks without well and areas with non-perfect well pattern. The technologies of enhancing recovery factor in complex faulted-block reservoir during the mid and late development stage is formed as follows: fine reservoir description, drilling adjust wells, designing directional wells, sub-dividing layer series of development, improving flooding pattern, changing water-injection direction and enhancing swept volume, cyclic waterflooding and gas-injection, etc. Here, directional wells include directional deflecting wells, lateral-drilling wells, lateral-drilling horizontal wells and horizontal wells. The results of this paper have been used in exploration and development of Shengli oilfield, and have achieved great social and economic profit, especially in predicting distribution of complex faulted-block reservoir, remaining oil distribution during middle and late stage of development, and in EOR. Applying the achievement of fault-closure research, new hydrocarbon-bearing blocks are discovered in flanks of Dongying central uplift and in complex blocks with proved reserves 15 million tons. With the study of remaining oil distribution law in complex faulted-block reservoirs, recovery factors are increased greatly in Dongxin, Xianhe and Linpan complex faulted-block reservoirs and accumulated oil production increment is 3 million tons.

地震波场延拓+菲涅尔体叠加方法及成像效果

In the increasingly enlarged exploration target, deep target layer(especially for the reservoir of lava) is a potential exploration area. As well known, the reflective energy becomes weak because the seismic signals of reflection in deep layer are absorbed and attenuate by upper layer. Caustics and multi-values traveltime in wavefield are aroused by the complexity of stratum. The ratio of signal to noise is not high and the fold numbers are finite(no more than 30). All the factors above affect the validity of conventional processing methods. So the high S/N section of stack can't always be got with the conventional stack methods even if the prestack depth migration is used. So it is inevitable to develop another kind of stack method instead. In the last a few years, the differential solution of wave equation was hold up by the condition of computation. Kirchhoff integral method rose in the initial stages of the ninetieth decade of last century. But there exist severe problems in it, which is are too difficult to resolve, so new method of stack is required for the oil and gas exploration. It is natural to think about upgrading the traditionally physic base of seismic exploration methods and improving those widely used techniques of stack. On the other hand, great progress is depended on the improvement in the wave differential equation prestack depth migration. The algorithm of wavefield continuation in it is utilized. In combination with the wavefield extrapolation and the Fresnel zone stack, new stack method is carried out It is well known that the seismic wavefield observed on surface comes from Fresnel zone physically, and doesn't comes from the same reflection points only. As to the more complex reflection in deep layer, it is difficult to describe the relationship between the reflective interface and the travel time. Extrapolation is used to eliminate caustic and simplify the expression of travel time. So the image quality is enhanced by Fresnel zone stack in target. Based on wave equation, high-frequency ray solution and its character are given to clarify theoretical foundation of the method. The hyperbolic and parabolic travel time of the reflection in layer media are presented in expression of matrix with paraxial ray theory. Because the reflective wave field mainly comes from the Fresnel Zone, thereby the conception of Fresnel Zone is explained. The matrix expression of Fresnel zone and projected Fresnel zone are given in sequence. With geometrical optics, the relationship between object point in model and image point in image space is built for the complex subsurface. The travel time formula of reflective point in the nonuniform media is deduced. Also the formula of reflective segment of zero-offset and nonzero offset section is provided. For convenient application, the interface model of subsurface and curve surface derived from conventional stacks DMO stack and prestack depth migration are analyzed, and the problem of these methods was pointed out in aspects of using data. Arc was put forward to describe the subsurface, thereby the amount of data to stack enlarged in Fresnel Zone. Based on the formula of hyperbolic travel time, the steps of implementation and the flow of Fresnel Zone stack were provided. The computation of three model data shows that the method of Fresnel Zone stack can enhance the signal energy and the ratio of signal to noise effectively. Practical data in Xui Jia Wei Zhi, a area in Daqing oilfield, was processed with this method. The processing results showed that the ability in increasing S/N ratio and enhancing the continuity of weak events as well as confirming the deep configuration of volcanic reservoir is better than others. In deeper target layer, there exists caustic caused by the complex media overburden and the great variation of velocity. Travel time of reflection can't be exactly described by the formula of travel time. Extrapolation is bring forward to resolve the questions above. With the combination of the phase operator and differential operator, extrapolating operator adaptable to the variation of lateral velocity is provided. With this method, seismic records were extrapolated from surface to any different deptlis below. Wave aberration and caustic caused by the inhomogenous layer overburden were eliminated and multi-value curve was transformed into the curve.of single value. The computation of Marmousi shows that it is feasible. Wave field continuation extends the Fresnel Zone stack's application.

中国南方热带地区田洋玛珥湖24万年以来的气候变化及湖泊演变

A continuous long (224m) and high-resolution core TY2 was recovered from paleo-maar-lake Tianyang, tropical South China. Based on the diatom records of the upper 130-m core, this paper focuses on exploring climate change and the lake evolution history in tropical South China during the past 240ka. The most typical and unique characteristics of the diatom assemblages is that, Aulacoseira granulata was dominant or absolutely dominant species (80-90%) during most parts of the 130-m core, while Cyclotella stelligera var. tenuis and Fragilaria construens var. venter were subdominant species in only limited parts of the lower and upper core, respectively. Time scale is always the biggest problem for the study of TY2 core, so although diatom is seldom used for establishing time scale, here we attempt this by correlating the diatom-reconstructed temperature sequence with the time scale of ODP core 806B from Equatorial Western Pacific. Verified by the few most reliable ages from TY2 core and the parallel core TYl, a rather reasonable and reliable time scale was established. 01S 7/6 falls at the depth of 100m (ca. 194kaBP), OIS 6/5 at 75m (ca. 132kaBP), OIS 5/4 at 46m (ca. 75kaBP), OIS 4-3 at 35m (ca. 60kaBP). Qualitative and quantitative environmental reconstructions are made on the basis of diatom assemblage ecotype and EDDI dataset. Correlation of diatom-reconstructed temperature and moisture changes of Core TY2 with pollen-reconstructed temperature and rainfall sequence of Core TYl proves that the results are quite consistent in most periods. Thus the reconstruction results from diatom are quite reliable, and probably have a much higher resolution than pollen results. Combined with lithological and magnetic susceptibility variations, the diatom analysis reveals that, the general climate in tropical South China during the past 240ka was warm and wet. On the time scale of glacial-interglacial, warm and wet, cool and dry are not always synchronous. It was relatively warm-wet during the penultimate interglacial, cool-dry during the penultimate glacial, warm-dry during the last interglacial, and cooler-drier during the last glacial. In contrast, on the time scale of subglacial-subinterglacial scales, warm and dry, cool and wet corresponds very obviously, showing very clear 21-23 ka precession cycle. Analysis also shows that, the water of Tianyang paleo-maar-lake was generally warm, turbulent, turbid, meso-trophic, slightly alkaline, low conductivity and fresh during the past 240 kaBP, with small variations in some parts. Tianyang paleolake experienced shallow to semi-deep lake in OIS7d, open shallow lake in OIS7c-OIS5b, shallow coastal lake in OIS5a-OIS4c, swamp in OIS4b, and then completely dried up in OIS3c. The lake evolution was mainly controlled by temperature and precipitation changes in tropical China. While temperature and precipitation changes were probably controlled by the migrations of monsoon rainband and the evaporation rate, which was in turn controlled by the evolution of East Asian monsoon. Therefore, when the summer monsoon was strongest the climate was warm-dry, when stronger the climate was warm-wet; when the winter monsoon was strongest the climate was cool-dry, stronger cool-wet. This mechanism caused the warm-dry sub interglacial and cool-wet subglacial climate in the tropical South China.