藏东及滇东南新生代钾质岩浆作用及其深部制约

The dissertation focuses on the petrology, geochemistry of the volcanic rocks in east Tibet and southeast Yunnan. It lucubrates the Magmatic process, forming mechanism and the possible tectonic settings of the volcanic rocks. The volcanic rocks of Nangqen basin in east Tibet, Qinghai province are mainly Cenozoic intermediate-acid shoshonites. The rocks are LREE enriched and the LREE/HREE = 3～34; (La/Yb)_N = 18.17-53.59, and ΣREE 222～1260μg/g. There are no Eu anomaly, and Nb, Ta, Zr, Hf, Ti are markedly depleted. The isotopic composition is ~(87)Sr/~(86)Sr = 0.70497～0.70614, ~(206)Pb/~(204)Pb = 18.622～18.974, ~(208)Pb/~(204)Pb = 38.431～38.996, ~(207)Pb/~(204)Pb = 15.511～15.613, respectively. K-Ar age of the whole rocks and the single mineral are between 32.0-36.5Ma. Based on the trace elements and isotopic elements, we get the conclusion that the partial melting is one of the dominated forming mechanisms for the volcanic rocks in Naneqen basin. The magma did not experience the crustal contamination en route to the surface; however, the complex mixture took place in the upper mantle before the melt was formed. There are at least two kinds of mixed sources that can be identified. The basalt in southeast Yunnan province is studied. They are distributed in Maguan, Tongguan, and Pingbian County, which is located on the both sides of the Red River belt, and the ultrabasic xenolith are cursory introduced. The volcanic rocks belongs to the alkali series, which can be subdivided into trachybasalt and basanite(Ol normal molecule >5). The volcanic rocks are characteristics by high Ti and low Mg#. According to the magma calculation model, the original rocks of the basalt in southeast Yunnan province are Spinel Lherzolite in Tongguan, Garnet Lherzolite in Pingbian and Maguan, while Togguan undergoes 2-5 percent and percent of partial melting, whereas volcanism in Maguan and Pingbian was so complex to calculate. The fractional crystallization took place during the magma evoltion in southeast Yunnan. The basalt is enriched in LREE with LREE/HREE=9.23-20.19. All of the trace elements display weak Nb, Ta peak, and the depletion of Zr, Hf and Ti in Maguan and pingbian represent the presence of Garnet in the source. The composition of the isotope ratio are ~(87)Sr/~(86)Sr = 0.70333-0.70427, ~(143)Nd/~(144)Nd = 0.512769-0.512940, ~(206)Pb/~(204)Pb = 18.104-18.424, ~(207)Pb/~(204)Pb = 15.483 -15.527; ~(208)Pb/~(204)Pb = 37.938-38.560, respectively, which shows the characteristics of the HIMU type OIB. The volcanic rocks of the southwest Yunnan are derived from the enriched, OIB type mantle sources by synthesizing all the data from trace and isotope elements. It is similar to that of the volcanic rocks in Hawaii, a typical kind of the mixtures of the recycled oceanic crust plume and depleted asthenosphere. To sum up, the volcanic rocks in southeast Yunnan are formed by the intraplate hotpot volcanism.

新第三纪红河盆地特征及红河断裂活动对其形成与发育的控制

Based on geodynamic analysis of sedimentary basins, combined sedimentology with structural geology and other methods, the author studied the Honghe basin located in Yunnan province of Southwestern China. Sandstone slice grain size analysis, combined with field geology and indoors study indicate that a set of inland alluvial fan diposits, fluvial deposites, delta deposits and some lacustrine sediments are in Honghe basin. Studying on shape of the Honghe basin, sedimentary and structural characteristic and distribution of different kinds of conglomerate and its structural significance, we hold the idea that the formation and evolution of Honghe basin are controlled by the activity of Red River faut. Correlation of lithostratic cross section in Honghe basin and studying on activity of Red River fault indicate that Honghe basin was formed in two stages. It is a complex basin constitutes of the first-stage trans-releasing basin and the second-stage trans-downfaulted basin. Due to the uplift of Qinghai-Xizang plateau and deformation of orogeny, the western Yunnan and adjacent area move to SE direction as a result of Tectonic Escape. Right lateral strike slip occurred along Red River fault, trans-releasing basin formed at the bend part of the fault due to stress relexation. As the block escaping, it moves away from the other block of the Red River fault, the upper block move down obliquely and trans-downfaulted basin formed. Combined the age of phytolite and regional structural events, we think the first-stage transreleasing basin was formed in late Miocene, on the other words, the dextral strike slip of Red River fault may began in late Miocene (10-7Ma). The second-stage trans-downfaulted basin may be formed in early stage of Pliocene (about 4.7Ma). Subsequently, the bilateral faults dipping to the inside of the plateau and thrusting outwards occurred in the marginal region of Qinghai-Xizang plateau during its uplifting as a fan-shaped mountain body, this results in the uplift of the strata to the east of Red River fault and supply large quantity of provenance for the Honghe basin. In last Pliocene (about 3Ma), strong uplift of Qinghai-Xizang plateau leads to massive clastic sediment entered Honghe basin and causes its closure. As a kind of trans-tentional basin, trans-releasing basin is different to pull-apart basin. The author compared the Mosha trans-releasing basin with Jinggu pull-apart basin in SW Yunan, China, and described their character correspondingly. Otherwise, the author combined the predecessors' studding with conclusion of own study, discussed the kinematics of Ailaoshan-Red River belt in Cenozoic, and the relationship between the formation of Honghe basin and uplifting of Qinghai-Xizang plateau.

渤海湾地区末次冰期古环境

The loess-paleosol sequence in China is one of the best archives for studying paleoenvironmental and paleoclimatic processes. The loess deposits in the coast of the Bohai Sea are suitable for the study of aridification in the northern China during glacial periods (fig.2-1). In this paper, stratigraphy was correlated by using magnetic susceptibility, grain size, and thermoluminence (TL) and accelerater mass spectrometer (AMS) ~(14)C ages. Based on the loess records, an interpretation has been made for paleoenvironmental changes on the coast of the Bohai Sea during the last glacials. The results of magnetic susceptibility, grain size, biostratigraphy, TL and ~(14)C dating, suggest that the loess-paleosol sequence in the coast of the Bohai Sea is discontinuous. The loess deposits correlated with the marine δ~(18)O stage 2 are usually absent in some profiles. Also, the thickness of the loess deposits in the same period varied significantly in different sections. In the coast of the Bohai Sea, the higher magnetic susceptibility corresponds to the finer grain size, consistent with the results of the Loess Plateau. It is indicated that the changes in magnetic susceptibility and grain size may record the paleoclimatic fluctuations of the last glacial. Although the loess deposits during the last glacial have been slightly altered by slope runoff, they have still remained main characters as the representative loess deposits of the Loess Plateau. During the last glacial, the less accumulation rate in the coast of the Bohai Sea is similar to that of the desert-loess transition zone in the northwestern Loess Plateau, and the all section contain high concentrations of sand (>60μm), indicate that the aridification in the Bohai Sea occurred during the glacial. But the changes in sand content of loess deposits along a north-south transect of the Bohai Sea and the changes of magnetic susceptibility implicate that desertification might not occur in the shelf of the Bohai Sea during the last glacial. The frequent fluctuations of summer monsoon during the marine δ~(18)O stage 4 are demonstrated by magnetic susceptibility, frequency-dependent susceptibility and the abundance of foraminifera. 46 genera, 71 species of foraminifera were identified from 138 loess samples. Almost all of the foraminifera are present in the last glacial loess, but the distribution patterns of foraminifera show significant temporal changes. The results of magnetic susceptibility, grain size and XRD indicate that not only sea-level changes had influences on foraminifera abundance, but also variations in sediment flux by rivers when sea-level drops might control the abundance of foraminifera. In addition, the diversity and exquitability of the foraminifera suggest that the frequent fluctuations of foraminifera fossil abundance during the marine δ~(18)O stages could be partly attributed to leaching. In summary, the changes in foraminifera of abundance related to the paleoclimatic variations, and the aridification extends to the coast of the eastern China during the last glacial.

油气运聚动力学的模拟分析——以准噶尔盆地为例

The petroleum migration, happening in the geologic past, is the very important and complex dynamic processes in the petroleum systems. It plays a linking role among all static factors in a system. The accumulation is in fact the result of the petroleum migration. For the petroleum geology, the dynamics research of the petroleum migration refers to the mechanism and process research, as well as the use of the quantitative methods. In this thesis, combining with the qualitative analysis and quantitative modeling, the author manages to discuss theoretically some key problems dealing with migration processes, which have not been solved yet, and to apply the studied results in petroleum system analysis in actual basins. The basin analysis offers the base of the numerical modeling for geological phenomena occurring in sedimentary basins, that consists of the sedimentary facies analysis, the section reconstructing technique, eroded thickness estimating, etc. The methods to construct the geologic model, which is needed in the research of oil and gas migration and accumulation, are discussed. The basin analysis offers also the possibility for the latter modeling works to get and select the parameters, such as stratum's thickness, age, stratigraphy etc. Modeling works were done by using two basin modeling softwares: Basin_Mod and TPC_Mod. The role of compaction during the secondary migration and the heterogeneity of migrating paths within the clastic carrier are modeled. And the conclusions were applied in the migration studies in the Jungaer Basin, lying on the Northwest part of the China. To construct a reliable migration model, the author studied the characteristics of the sedimentation, the pore fluid pressure evolution, as well as the distribution and the evolution of fluid potential, following the tectonic evolution of the Jungaer Basin. The geochemical prospecting results were used to evidence and to calibrate the migration processes: the oil-source correlation, the distribution of the properties of oil, gas and water. Finally, two important petroleum systems, Permian one and Jurassic one were studied and identified, according, principally, to the studies on the petroleum migration within the Jungaer Basin. Since the oil, as well as the gas, moves mainly in separate phase during the secondary migration, their migrating behaviors would be determined by the dynamics conditions of migration, including the driving forces and pathways. Based on such a consideration, the further understandings may be acquired: the roles played by permeable carriers and low-permeable source rock would be very different in compaction, overpressure generation, petroleum migration, and so on. With the numerical method, the effect of the compaction on the secondary migration was analyzed and the results show that the pressure gradient and the flux resulted from compaction are so small that could be neglected by comparing to the buoyancy of oil. The main secondary migration driving forces are therefore buoyancy and capillary within a hydrostatic system. Modeling with the commercial software-Basin_Mod, the migration pathways of petroleum in clastic carriers seem to be inhomogeneous, controlled by heterogeneity of the driving force, which in turn resulted from the topography of seals, the fabrics and the capillary pressure of the clastic carriers. Furthermore, the direct and indirect methods to study fault-sealing properties in the course of migration were systemically summarized. They may be characterized directly by lithological juxtaposition, clay smear and diagenesis, and indirectly the comparing the pressures and fluid properties in the walls at two apartments of a fault. In Jungaer Basin, the abnormal pressures are found in the formations beneath Badaowan or Baijantan Formation. The occurrence of the overpressure seems controlled by the stratigraphy. The rapid sedimentation, tectonic pressuring, clay sealing, chemical diagensis were considered as the principal pressuring mechanisms. The evolution of fluid pressure is influenced differently at different parts of the basin by the tectonic stresses. So the basin appears different pressure evolution cycles from each part to another during the geological history. By coupling the results of thermal evolution, pressure evolution and organic matter maturation, the area and the period of primary migration were acquired and used to determine the secondary migration time and range. The primary migration in Fengcheng Formation happened from latter Triassic to early Jurassic in the main depressions. The main period of lower-Wuerhe Formation was at latter Jurassic in Changji, Shawan and Pen-1-jing-xi Depression, and at the end of early Cretaceous in Mahu Depression. The primary migration in Badaowan and Sangonghe Formation is at the end of early-Cretaceous in Changji Depression. After then, the fluid potential of oil is calculated at the key time determined from area and time of the primary migration. Generally, fluid potential of oil is high in the depressions and low at the uplifts. Synthetically, it is recognized that the petroleum migration in the Jungaer Basin is very complex, that leads us to classify the evolution of petroleum systems in Northwestern China as a primary stage and a reformed one. The remigration of accumulated petroleum, caused by the reformation of the basin, results in the generation of multiple petroleum systems. The faults and unconformities are usually the linkers among the original petroleum systems. The Permian petroleum system in Jungaer Basin is such a multiple petroleum system. However, the Jurassic petroleum system stays still in its primary stage, thought the strong influences of the new tectonic activities.

晚中新世以来中国北方风成沉积的磁性地层学和沉积学研究

The past two decades have witnessed an unprecedented growth of interest in the palaeoenvironmental significance of the Pleistocene loess deposits in northern China. However, it is only several years ago that the Tertiary red clay sequence underlying Pleistocene loess attracted much attention. One of the major advances in recent studies of eolian deposits on the Loess Plateau is the verification of the eolian origin for the Tertiary red clay sediments. The evidence of the eolian origin for the red clay is mainly from geochemical and sedimentological studies. However, sedimentological studies of the red clay deposits are still few compared with those of the overlying loess sediments. To date, the red clay sections located near Xifeng, Baoji, Lantian, Jiaxian, and Lingtai have been studied, with an emphasis on magnetostratigraphy. These sections have a basal age ranging from ～4.3 Ma to ～7.0 Ma. The thickness of the sections varies significantly, depending perhaps on the development of local geomorphological conditions and the drainage system. Although the stratigraphy of the red clay sections has been recorded in some detail, correlation of the red clay sequences has not yet been undertaken. Geological records (Sun J. et al., 1998) have shown that during glacial periods of the Quaternary the deserts in northem China were greatly expanded compared with modern desert distribution. During interglacial periods, desert areas contracted and retreated mostly to northwestern China because of the increase in inland penetration of monsoonal precipitation. According to pedogenic characteristics of the red clay deposits, the climatic conditions of the Loess Plateau is warmer and wetter generally in the Neogene than in the late Pleistocene. Panicle analyses show that grain size distribution of the red clay sequence is similar to that of the paleosols in the Pleistocene loess record, thus implying a relatively remote provenance of the red clay materials. However, the quantitative or semiquantitative estimates of the distance from the source region to the Loess Plateau during the red clay development remains to be investigated. In this study, magnetostratigraphic and sedimentological studies are conducted at two thick red clay sequences-Jingchuan and Lingtai section. The objectives of these studies are focused on further sedimentological evidence for the eolian origin of the red clay, correlation of red clay sequences, provenance of the red clay, and the palaeoclimate reconstruction in the Neogene. Paleomagnetic studies show that the Jingchuan red clay has a basal age of 8.0 Ma, which is 1 million years older than the previously studied Lingtai section. The Lingtai red clay sequence was divided into five units on the basis of pedogenica characteristics (Ding et al., 1999a). The Jingchuan red clay sequence, however, can be lithologically divided into six units according to field observations. The upper five units of the Jingchuan red clay can generally correlate well with the five units of the Lingtai red clay. Comparison of magnetic susceptibility and color reflectance records of four red clay sections suggests that the Lingtai red clay sequence can be the type-section of the Neogene red clay deposits in northern China. Pleistocene loess and modem dust deposits have a unimodal grain-size distribution. The red clay sediments at Jingchuan and Lingtai also have a unimodal grain-size distribution especially similar to the paleosols in the Pleistocene loess record. Sedimentological studies of a north-south transect of loess deposits above S2 on the Loess Plateau show that loess deposits had distinct temporal and spatial sedimentary differentiation. The characteristics of such sedimentary differentiation can be well presented in a triangular diagram of normalized median grain size, normalized skewness, and normalized kurtosis. The triangular diagrams of the red clay-loess sequence at Lingtai and Jingchuan indicate that loess-paleosol-red clay may be transported and sorted by the same agent wind, thus extending the eolian record in the Loess Plateau from 2.6 Ma back to about 8.0 Ma. It has been recognized that during the last glacial maximum (LGM) the deserts in northern China had a distribution similar to the present, whereas during the Holocene Optimum the deserts retreated to the area west of the Helan Mountains. Advance-retreat cycles of the deserts will lead to changes in the distance of the Loess Plateau to the dust source regions, thereby controlling changes in grain size of the loess deposited in a specific site. To observe spatial changes in sedimentological characteristics of loess during the last glacial-interglacial cycle, the texture of loess was measured along the north-south transect of the Loess Plateau. Since the southern margin of the Mu Us desert during the LGM is already known, several models of grain size parameters versus the minimum distance from the source region to depositional areas were developed. According to these semiquantitative models, the minimum distance from the source region to Lingtai and Jingchuan areas is about 600 km during the Neogene. Therefore the estimated provenance of the Tertiary red clay deposits is the areas now occupied by the Badain Jaran desert and arid regions west of it. The ratio of the free iron to total iron concentration attests to being a good proxy indicator for the summer monsoon evolution. The Lingtai Fe_20_3 ratio record shows high values over three time intervals: 4.8-4.1 Ma, 3.4-2.6 Ma, and during the interglacial periods of the past 0.5 Ma. The increase in summer monsoon intensity over the three intervals also coincides with the well-developed soil characteristics. It is therefore concluded that the East-Asia summer monsoon has experienced a non-linear evolution since the late Miocene. In general, the East Asia summer monsoon was stronger in Neogene than in Quaternary and the strongest East Asia summer monsoon may occur between 4.1 and 4.8 Ma. The relatively small ice volume and high global temperature may be responsible for the strong summer monsoon during the early Pliocene.

陇西盆地晚第三纪风尘沉积的地层学研究

In Asia, the significant environment changes in Cenozoic include: uplift of Himalayas and Tibetan Plateau, formation Asian monsoon system, Aridification in Central Asia. One of major advances in recent studies of eolian deposit on the Loess Plateau is the verification of the eolian origin for the Late Tertiary Hipparion Red-Earth (also called red-Clay) underlying the Quaternary loess. Thus, the Late Tertiary eolian deposit, which has been proven a nearly continuous terrestrial record and sensitive to climate change, provides us an important archive to understand these above Cenozoic environment events. The deposit in eastern Loess Plateau has been extensively studied, while the property and age of deposit underlying the Quaternary loess in western plateau remains unclear. In this paper, detail investigations were made on the Sedimentology, geochemistry of Longxi section, a typical section in western Loess Plateau, to address its origin, and on micromammalian fossils and magnetostratigraphy to address its age. The main conclusions are presented as following: 1. The sedimentological and geochemical properties in Longxi section are highly similar to typical Quaternary eolian deposit in Loess Plateau. Nearly 100 paleosols are recognized in the field, and the grain size are very fine with the median grain size centered at 4～7μm. There is a good agreement of both major and trace element compositions between Longxi deposit and the Quaternary Loess. The REE distribution patterns of Longxi deposit and the Quaternary loess are remarkably similar in shape, with enrichment LREE and fairly flat HREE profiles and clear negative Eu anomaly. The mangnetic minerals in Longxi deposit are mainly magnetite, hematite and maghematite, which are similar to those of the Hipparion Red-Earth and Quaternary Loess. The major difference among them is that the samples from Longxi section contain more hematite. The characteristics of anisotropy of magnetic susceptibility (AMS) in Longxi deposit is highly consistent with that of Quaternary loess, while values of the major AMS parameters, e.g. anisotropy degree, magnetic foliation and lineation, are significantly lower than those of fluvial and lake deposits. These evidences indicate an eolian origin for the sediment. 2. An investigation of micromammalian fossils was firstly carried out for determining the approximate age of the sequence because of lack of materials for accurate isotope dating. Three fossil assemblages were obtained which indicate a chronological range from the Middle Miocene to Late Miocene. The magnetostratigraphical study suggests that it is a near continuous terrestrial record for the period from 13.23 to 6.23 MaB.P. The obtained chronology is highly consistent with fossils assemblages. This section is the oldest eolian deposit presently known in Loess Plateau. 3. The magnetic susceptibly value is high in paleosols than in surrounded weak-weathered layers, which suggests that it may be a climate index on orbital time scale. While it cannot be used as a proxy to address the long-term, change of climate on tectonic time scale, as content of the magnetic minerals is highly variable in different parts of the section. 4. The appearance of Middle Miocene eolian deposit in the Loess Plateau marks the strengthening of aridification of Central Asia. The high degree of similarity between the geochemical properties of Longxi eolian deposit, Hipparion Red-Earth and Quaternary loess a suggests that a rather similar source provenance. The dust accumulation rate (DAR) of Longxi section, which is widely used as a proxy to document the aridity in source areas in marine and terrestrial record studies, recorded the aridity condition in northwestern China over a period from Middle Miocene to Late Miocene. The DAR of the section shows that the continent aridity remains moderate and relative stable over that period.

地理信息系统支持下的滑坡灾害空间分析预测-以云南小江流域为例

As a typical geological and environmental hazard, landslide has been causing more and more property and life losses. However, to predict its accurate occurring time is very difficult or even impossible due to landslide's complex nature. It has been realized that it is not a good solution to spend a lot of money to treat with and prevent landslide. The research trend is to study landslide's spatial distribution and predict its potential hazard zone under certain region and certain conditions. GIS(Geographical Information System) is a power tools for data management, spatial analysis based on reasonable spatial models and visualization. It is new and potential study field to do landslide hazard analysis and prediction based on GIS. This paper systematically studies the theory and methods for GIS based landslide hazard analysis. On the basis of project "Mountainous hazard study-landslide and debris flows" supported by Chinese Academy of Sciences and the former study foundation, this paper carries out model research, application, verification and model result analysis. The occurrence of landslide has its triggering factors. Landslide has its special landform and topographical feature which can be identify from field work and remote sensing image (aerial photo). Historical record of landslide is the key to predict the future behaviors of landslide. These are bases for landslide spatial data base construction. Based on the plenty of literatures reviews, the concept framework of model integration and unit combinations is formed. Two types of model, CF multiple regression model and landslide stability and hydrological distribution coupled model are bought forward. CF multiple regression model comes form statistics and possibility theory based on data. Data itself contains the uncertainty and random nature of landslide hazard, so it can be seen as a good method to study and understand landslide's complex feature and mechanics. CF multiple regression model integrates CF (landslide Certainty Factor) and multiple regression prediction model. CF can easily treat with the problems of data quantifying and combination of heteroecious data types. The combination of CF can assist to determine key landslide triggering factors which are then inputted into multiple regression model. CF regression model can provide better prediction results than traditional model. The process of landslide can be described and modeled by suitable physical and mechanical model. Landslide stability and hydrological distribution coupled model is such a physical deterministic model that can be easily used for landslide hazard analysis and prediction. It couples the general limit equilibrium method and hydrological distribution model based on DEM, and can be used as a effective approach to predict the occurrence of landslide under different precipitation conditions as well as landslide mechanics research. It can not only explain pre-existed landslides, but also predict the potential hazard region with environmental conditions changes. Finally, this paper carries out landslide hazard analysis and prediction in Yunnan Xiaojiang watershed, including landslide hazard sensitivity analysis and regression prediction model based on selected key factors, determining the relationship between landslide occurrence possibility and triggering factors. The result of landslide hazard analysis and prediction by coupled model is discussed in details. On the basis of model verification and validation, the modeling results are showing high accuracy and good applying potential in landslide research.

青藏高原东缘新生代富钾碱性岩的年龄与岩石地球化学特征

The Cenozoic high-Potassium alkaline magma rocks are widely distributed in the eastern margin of Qinghai-Xizang (Tibet) plateau, such as Mangkang, Deqin, Jianchuan, Haidong in the western Yunnan Province, Yanyuan, Muli in the western Sichuan province, including syenite, minette and trachyte and lamprophyres, which formaed a large alkaline-rich magmatic rock zone along the Jinshajiang-Ailaoshan fault. Here we present detailed Geochemical and Geochronology study for the Cenozoic high-K alkline magma rocks from Mangkang, Deqin, Jianchuan, Haidong and Muli, Yanyuan, Yanbian, Yaoan (western Yangtze craton). Rocks of our target area include syenite, minette and trachyte. Geochronologic dating and compilation of existing age data suggest magmatism occurred at 32-38Ma and distribute along the Jinsha suture, from Jinping, Daping, Zhenyuan to Haidong, Jianchuan, Deqin, Mangkang, Zaduo to Qiangtang Bandaohu, Zhentouya. They all share same geochemical features such as rich in potassium and alkaline, rich in LREE, slightly negative Eu anomalies, negative anomalies in Nb, Ta, Ti,. These indicate they come from EMU mantle. Geochronologic dating on western Yangtze craton minette surgest minette in Haidong, Yanyuan, Yanbian, Yaoan, Deqin ocurred at 30-37Ma, well minette in Muli ocurred at IMa. Need more detailed geology study to find differece of these two episode magmatism.

中国大陆及邻区地震活动背景、环境触发与地震预测研究

This dissertation that includes most of the P. PH.D research work during 2001~2002 covers the large-scale distribution of continental earthquakes in mainland China, the mechanism and statistic features of grouped strong earthquakes related to the tidal triggering, some results in earthquake prediction with correlativity analysis methods, and the flushes from the two strong continental earthquakes in South Asia in 2001. Mainland China is the only continental sub-plate that is compressed by collision boundaries at its two sides, within which earthquakes are dispersive and distributed as seismic belts with different widths. The control capability of the continental block boundaries on the strong earthquakes and seismic hazards is calculated and analyzed in this dissertation. By mapping the distribution of the 31282 ML:3s2,0 earthquakes, I found that the depth of continental earthquakes depend on the tectonic zonings. The events on the boundaries of relatively integrated blocks are deep and those on the new-developed ruptures are shallow. The average depth of earthquakes in the West of China is about 5km deeper than that in the east. The western and southwestern brim of Tarim Basin generated the deepest earthquakes in mainland China. The statistic results from correlation between the grouped M7 earthquakes and the tidal stress show that the strong events were modulated by tidal stress in active periods. Taking Taiwan area as an example, the dependence of moderate events on the moon phase angles (￡>) is analyzed, which shows that the number of the earthquakes in Taiwan when D is 50° ,50° +90° and 50° +180° is more than 2 times of standard deviation over the average frequency at each degree, corresponding to the 4th, 12th and 19th solar day after the new moon. The probability of earthquake attack to the densely populated Taiwan island on the 4th solar day is about 4 times of that on other solar days. On the practice of earthquake prediction, I calculated and analyzed the temporal correlation of the earthquakes in Xinjinag area, Qinghai-Tibet area, west Yunnan area, North China area and those in their adjacent areas, and predicted at the end of 2000 that it would be a special time interval from 2001 to 2003, within which moderate to strong earthquakes would be more active in the west of China. What happened in 2001 partly validated the prediction. Within 10 months, there were 2 great continental earthquakes in south Asia, i.e., the M7.8 event in India on Jan 26 and M8.1 event in China on Nov. 14, 2001, which are the largest earthquake in the past 50 years both for India and China. No records for two great earthquakes in Asia within so short time interval. We should speculate the following aspects from the two incidences: The influence of the fallacious deployment of seismic stations on the fine location and focal mechanism determination of strong earthquakes must be affronted. It is very important to introduce comparative seismology research to seismic hazard analysis and earthquake prediction research. The improvement or changes in real-time prediction of strong earthquakes with precursors is urged. Methods need to be refreshed to protect environment and historical relics in earthquake-prone areas.

黄土高原22万年来的黑碳记录和古火灾害历史重建

The term black carbon is used to describe a relatively inert and ubiquitous form of carbon, comprising a range of materials from char and charcoal to element or graphite carbon produced by the incomplete combustion of fossil fuels and biomass. Due to its inertness, the BC in soils, lacustrine and marine sediments and ice can persist over a long period of time. So BC signatures in geological deposits can be used as evidence of natural fires happened in their surroundings. To study the temporal and spatial changes in paleofires over the Chinese Loess Plateau, black carbon concentrations were analyzed on the loess-paleosol samples from three sections including Lijiayuan, Lingtai and Weinan along a north-south transect. Using the orbitally-tuned time-scales of the sections, the black carbon sedimentation rates (BCSR) were calculated. Meanwhile, with objective to document fine resolution fire history during late Pleistocene and Holocene periods, we measured BC concentrations of loess-paleosol samples at dense sampling intervals since 28 ka BP. in Lijiayuan section. The BCSR of the samples were also calculated. In addition, we also conducted observation on black carbon morphologies to examine their sources. Based on the results, the following remarks can be concluded: 1. In the last two glacial cycles, the BCSR values in glacial periods are 2-3 times higher than in interglacial periods, and the BCSR variability has a relatively strong precession-associated 23 kyr period, suggesting that the glacial cold-dry climate conditions were apt to induce natural fires over the Loess Plateau, 2. Comparison of the BCSR records among the three loess sections demonstrates that natural fire occurrence was much more intensive and frequent in the northern and interglacial periods. 3. Pollen records and carbon isotope analyses of organic matter have shown that the Loess Plateau was covered by an Artemisia-dominated grassland vegetation both during glacial and interglacial periods, So grassland fires were the dominant fire types in the Plateau, which is also corroborated by the observation of black carbon morphology. In addition, statistics and comparison of BC particle sizes among the sections demonstrated that BC records probably reflected local fires. 4. According to previous studies about the effect of fires on vegetation changes, we considered that the fires might play an important role in the expansion of grassland during glacial periods, besides the control of climate changes. 5. The high resolution black carbon record in Lijiayuan section has shown that the BCSR series well documented Younger dryas (YD) and Heinrich (HI和H2) events, suggesting that natural fires in the northwestern part of Chinese Loess Plateau could regularly respond to the millennial scale climate oscillation.

宁夏固原寺口子剖面磁性地层与孢粉植物群初步研究

In Asia continent, several significant environmental events happened during the Cenozoic era, such as uplift of the Tibet Plateau, formation of the Asian Monsoon system, aridification of the temperate inland region in Central Asia. To investigate the history of long-term palaeoclimate evolution during the late Cenozoic, a lacustrine sequence located at Sikouzi, Guyuan county, Ningxia-Hui Autonomous Region, was studied. The Sikouzi section is about 2880 m in thickness and has a general continuous nature according to field observation. Thus this thick lacustrine record is an important archive to further understand those environmental events. In this study, detailed field measurement, layer-after-layer description and sampling, and magnetostratigraphy and palynoflora investigations are conducted at the Sikouzi section and some preliminary results have been achieved as follows. Based on Hipparion fauna, pollen data and long distinctive patterns of the local magnetozones, the confident correlation of the Sikouzi magnetostratigraphic polarity to the GPTS (CK95) is best established, indicating that the top boundary of the Sikouzi formation is dated back to -19.8 Ma B.P. and consequently no Oligocene sediments deposited locally. On the other hand, both the field observation and the correlation to GPTS indicate a nearly continuous nature for the whole sequence. The palynological results show that the grassland has been a dominant vegetation in the Sikouzi area since ~19.8 Ma B.P, although some trees/shrubs were present sparsely during the intervals of relatively warm and wet climatic conditions. This implies that the onset of the aridification in northwestern China is dated back to at least 19.8 Ma B.P. ago. The Neogene Global Climatic Optimum (-16.0 Ma B.P.) occurring between the late Early Miocene and the early Middle Miocene is well documented in the Shanwang formation, Shandong Province. However, such event was not found in the Sikouzi record, and neither in the Guide and the Hualong basins, Qinghai province. This may lead us to the conclusion that the East-Asian Summer Monsoon system remained weak during the period of the Miocene Climatic Optimum although the onset of it was traced back to the Early Oligocene. In the Sikouzi area, it was warm between the latest Miocene and the early Pliocene and then became cool in the late Pliocene. This pattern is consistent with the palaeoclimate record of the Pliocene from other areas in the world.

亚洲地形和海陆分布变化对东亚环境格局形成演化的作用：数值模拟与地质记录对比

Earlier studies on the distribution of geological environmental indicators in China revealed drastic changes from a zonal climate pattern (planetary-wave-dominant pattern) in the Paleogene to a monsoon-dominant one in the Neogene, which suggested an inception of the initial East-Asian summer monsoon. However, there are different views about the time and causes of the changes.Here, we attempt to compile a series of paleoenvironmental maps based on newly collected climate indicators from the literatures and chronologically constrained evidence of geological maps in order to re-examine the temporal and spatial evolution of climate belts in China during the Cenozoic with special emphasis on the changes of the arid belt. These indicators include mammalian fauna, coal, carbonate concretions, jarosite, salt, gypsum deposits and pollen assemblages etc, with chronological controls that we believe reliable. Pollen assemblages and mammalian fauna have been classified into three categories (arid, semi-arid/sub-humid, humid) to reflect the intensity of aridity/humidity. Salt, jarosite and gypsum deposits are classified as the arid indicators. Carbonate concretions and coal are classified into the semi-arid/sub-humid and humid one respectively. Paleoenvironmental maps at 8 time slices have been reconstructed. They are the Paleocene, Eocene, Oligocene, Miocene, Early Miocene, Middle Miocene, Late Miocene and Pliocene.And furthermore, we attempt to use IAP^AGCM to simulate the evolution of climate belts in emphasizing on the changes of the rain band, and compare the results with the paleoenvironmental maps in order to examine the causes of the drastic paleoenvironmental changes near the Oligocene/Miocene boundary. 36 sensitive numerical experiments are carried out using the IAP__AGCM to analyze the impacts of the uplift of the Himalayan-Tibetan complex, shrinkage of the Paratethys Sea, expansion of the South China Sea and the development of the polar ice sheets on rain band in China.The main conclusions are as follows:The obtained results essentially confirm the earlier conclusions about a zonal climate pattern in the Paleogene and a different pattern in the Neogene, and illustrate that a monsoon-dominant environmental pattern with inland aridity formed by the Early Miocene, which is temporally consist with the onset of eolian deposits in China.Cenozoic cooling and the formation of polar ice sheets are unlikely the main causes to the changes of environmental patterns mentioned above in China. But northern hemispheric cooling and the ice-sheets can intensify the Siberian High Pressure, and strengthen the winter monsoon circulations and enhance the aridity in the west part of China. These results support the earlier studies.Shrinkage of the Paratethys Sea and uplift of the Himalayan-Tibetan complex played important roles in strengthening the East Asian monsoon and induceing the above changes of environmental pattern, which is consistent with the earlier studies. Furthermore, "the monsoon-dominant pattern" appears when the Himalayan-Tibetan complex reaches to about 1000-2000 meters high and the Paratethys Sea retreats to the Turan Plate.4) Expansion of the South China Sea is another significant factor that drives the evolution of environmental patterns. We believe that the above three factors co-act and drive the change of the environmental patterns from a planetary-wave-dominant one to a monsoon-dominant one. However, the impacts of each factor vary by regions. The uplift mainly increases the humidity in Southwestern China and the aridity in northwestern country. The shrinkage mainly increases the humidity in Northern China and also enhances the aridity in the northwestern country. The expansion greatly increases the humidity in the south part of China.

云南兰坪金顶超大型铅锌矿区镉的环境地球化学研究

矿产资源开采利用过程中导致的重金属环境污染问题日益严重。我国铅锌矿资源丰富，其开采利用过程中镉的环境污染也日益突出。本文通过对云南兰坪金顶Pb-Zn矿区矿床开采利用过程中镉等重金属元素的环境地球化学行为及矿区生态环境的研究，得出如下主要结论。 1. 矿石淋滤实验表明矿区部分氧化铅锌矿石可以很快被再次氧化或者被溶解并释放出大量镉等有害元素，滤出元素可以迅速发生沉淀或被沉淀物包裹，其释放能力表现为Zn>Pb>Cd。铅锌氧化矿石中菱锌矿组分含量是影响镉淋失的主要因素。在开放体系的水-岩作用下，矿区岩石、矿物的自然风化极易造成当地水系统中镉污染。 2. 矿区不同岩（矿）石中镉含量分布差异比较大，围岩中镉含量为50-650 ppm，平均310 ppm，原生矿中镉含量为14-2800 ppm，平均767 ppm，氧化矿中镉含量为110-8200 ppm，平均1661 ppm，其平均值最高。Zn、Cd地球化学性质的差异导致了二者在原生矿和氧化矿中的不同地球化学分配特点，原生矿Zn/Cd高于氧化矿Zn/Cd，表明氧化环境中镉更容易在氧化矿中富集，而锌更容易被氧化析出到环境中。氧化矿中Cd与Ca呈负相关，这表明Cd的富集和Ca的氧化淋失是同时进行的，并且还可能有Cd对Ca的类质同像代替存在。 3. 矿区上游对照区土壤中的高含量Cd浓度是因土壤母质层重金属高背景值造成的，而非人为污染。矿区中心区土壤受到严重Cd污染，可能与选厂、采场废石堆、尾矿库和露采矿山大范围暴露有关。矿区沿沘江下游两岸土壤中Cd含量远远超出上游土壤背景值和金顶全区土壤背景值，这可能是与污水灌溉有关。通过加权综合污染指数评价法发现矿区土壤污染的主要因子是Cd，其次是Zn和Pb，矿区土壤重金属污染贡献顺序为：Cd>Zn>Pb。矿区土壤污染主要表现为：矿区土壤污染有从中心区向沘江下游扩散区土壤中蔓延的趋势。 4. 矿区水体中出现较高含量的镉，高出天然河流中镉含量的50-100倍。矿区架崖山、北厂和跑马坪等采矿区水体中镉浓度范围在15-30 µg/L之间。矿区水体中镉含量水平表现为：矿山浅层地下水>矿山溪流水>沘江河水。研究结果表明，矿区沘江下游河段水体明显受镉污染，其中水体中镉的平均含量为15.7 µg/L，悬浮物中镉含量为49.3 mg/kg，沉积物中镉含量为203.7 mg/kg。矿区载镉岩石和矿物的自然风化是造成矿区水环境中镉污染的直接原因。 5. 跑马坪采场的废弃石具有较低的Cd含量，而北厂、架崖山采场的废弃石具有较高的Cd浓度，可能与废弃矿石类型本身差异有关。尾矿剖面中的Cd含量，在表层中随剖面深度呈递减趋势，在中层随剖面深度变化不明显，而在底层中明显富集。尾矿库表层尾矿样品中弱酸提取态和可还原态Cd高于底层尾矿样品，相比之下，表层尾矿中Cd等重金属元素易于释放到环境中，对环境的潜在危害大。老尾矿库尾矿砂中Cd金属总量高于新尾矿库尾矿砂，可能还是因为选矿工艺、技术的差异造成的。 6. 矿区污染段水体中硫同位素值较低，远远低于上游非污染区硫同位素值。矿区水体中δ34S值保持了金顶铅锌矿山源区矿山物质硫同位素的特征，显示了矿山来源物质的影响。根据水体硫酸盐中硫同位素稀释原理，研究发现沘江下游水体SO42-中85 %的硫来源于矿山物质。 7. 从矿区筛选出Cd、Zn、Pb的超富集植物共有4种：其中Cd超富集植物有2种，分别是本地生条裂萎陵菜（Potentilla lancinata Card. In Lecomte）和辣子草（Galinsoga parviflora Cav.）；Zn超富集植物仅发现有1种植物，为节节草（Equisetum ramosissmum Desf.）；Pb超富集植物发现了1种植物，为毛莲菜（Picris hieracioides L.）。这些植物均具备了超富集植物的基本特征，在污染土壤治理与修复方面具有一定的实践意义。 8. 建立了金顶铅锌矿山（床）地质环境模型。Cd的释放、迁移扩散模式为：雨水淋滤时，矿山固体废弃物产生富Cd的酸性或弱酸性矿山排水，通过下渗淋滤发生测向和垂向迁移，进入周边水体和土壤，然后被水系沉积物中针铁矿、方解石等吸附，并在沉降物中沉淀富集，导致矿区主要河流沘江水体的自净能力下降，加速水体的进一步恶化，破坏生物生存环境。矿区受污染水体、土壤和大气中的有害物质通过生物链进入动植物体内，进而危害人类健康。

滇东南南温河花岗岩年代学和地球化学初步研究

南温河花岗岩分布于中-越接壤处的云南省马关县、麻栗坡县老君山地区穹隆状变形-变质岩系的内核部位，大地构造位置位于华南褶皱带西端与上扬子地块、哀牢山褶皱带和印支地块的接合部位，是研究华南大陆形成与演化及特提斯构造域时空发展的关键地区。前人对本地区花岗岩的研究，更多的集中在燕山期老君山花岗岩的研究上，而对南温河花岗岩的研究还没有引起足够的重视，还停留在初步的岩石学和地球化学阶段。 本文对滇东南老君山地区南温河花岗岩进行了U-Pb、Rb-Sr同位素年代学和主微量、Sr-Nd同位素地球化学的系统研究，取得了以下主要认识： 1、通过对南温河花岗岩 SHRIMP锆石U-Pb、TIMS锆石U-Pb年代学和全岩Rb-Sr年代学的研究，确定了南温河花岗岩主体的结晶年龄为440Ma左右，少量结晶为420Ma左右， 属于广西运动产物。在同位素年代学和岩石学研究基础上，重新对南温河花岗岩进行了岩石单元划分，归并为猛洞河单元和南加河单元两个单元。南捞片麻岩并非如1：50000麻栗坡县幅、都龙幅所认为的新元古代岩浆岩，也同属加里东期岩浆岩，应归属于猛洞河单元。 2、南温河序列花岗岩成分来源主要为上部地壳的泥质岩、粉砂岩、杂砂岩的部分熔融，可能还有少量地幔物质和下部地壳物质的加入。成因上主要属于S型花岗岩，少量属于 I型花岗岩。 形成的构造环境上，主要为同碰撞环境，少部分为造山后环境。 继承锆石年龄和Sr-Nd同位素地球化学特征显示，源区存在古元古代的古老地壳。 3、结合SHRIMP和TIMS锆石U-Pb年代学两种测年方法的差异，确定了后期的主变质年龄为 230Ma左右，提出了确定后期中-浅变质作用年龄的一种新思路。 4、通过南温河花岗岩热年代史反演，恢复了本区加里东期以来的构造历史，并初步探讨了本区加里东期的大地构造环境。

云南中甸普朗斑岩铜矿矿床地球化学

中甸格咱地区是在晚三叠世甘孜-理塘洋盆向西俯冲过程中所形成的中甸弧的主弧带，区内岛弧火山活动和岩浆侵入活动均非常强烈，广泛分布有印支期斑岩体，同时发育有众多的与其有关的斑岩型和矽卡岩型矿床或矿点。普朗斑岩铜矿就是近年来在该区发现的一个大型乃至超大型矿床，目前已圈定5个矿化体，7个工业矿体，其中，主矿体探明铜资源量436.5万吨。 本论文主要从区域地质背景、矿床地质特征、元素地球化学、同位素地球化学、流体包裹体地球化学、矿床年代学及成矿机理等角度对普朗斑岩铜矿进行了较为系统的研究，主要获得如下认识： 普朗复式岩体具明显的多次脉动侵入特征，可分为三期：第一期为大面积分布的石英闪长玢岩（部分为二长闪长玢岩），第二期为岩体中心的石英二长斑岩和花岗闪长斑岩，第三期为岩脉状闪长玢岩。岩体具有典型的斑岩铜矿蚀变分带特征，由内向外依次为强硅化带（局部）→钾化硅化带→绢英岩化带→青磐岩化带。 矿化石英二长斑岩的锆石离子探针U-Pb年龄约为226～228Ma；钾化硅化带中黑云母的40Ar-39Ar坪年龄约为210～216Ma；含矿石英脉中辉钼矿Re-Os等时线年龄约为214Ma。 普朗岩体总体显示I型花岗岩类特征，属典型的钙碱性系列岩石。锶、钕、铅同位素特征显示其岩浆源区具有幔源物质（占主要地位）与壳源物质较为均匀混合的特征。金属硫化物的硫、铅同位素特征显示成矿元素与岩体具有密切的亲缘关系。脉石矿物的氢、氧、碳同位素特征和流体包裹体特征显示成矿流体自钾化阶段至网脉状矿化阶段均具岩浆流体特征。 根据不同期次的含矿石英脉中的流体包裹体特征，主要发现有四种流体：高盐度岩浆流体（盐度：34～54wt%NaCl）、含CO2低盐度流体（盐度：2.7～6.4wt%NaCl，XCO2：0.04～0.25）、中等盐度流体（盐度：19～25wt%NaCl）以及低盐度水溶液（盐度：＜10wt%NaCl）。这些流体可能主要是原始岩浆流体演化至不同阶段的产物。 原始岩浆流体可能有两种来源：其一是斑岩侵入过程中自身分异的流体，其二是岩浆房中分异的流体。其中，岩浆房来源的岩浆流体对普朗岩体的蚀变及矿化作用起到了主导性作用。主成矿期金属硫化物的沉淀主要与流体系统开放后因其物理化学条件的变化而产生的流体相分离作用及流体对围岩的蚀变作用有关。