内蒙古东部喀喇沁地区早中生代底侵作用

Mafic granulite xenoliths have been extensively concerned over the recent years because they are critical not only to studies of composition and evolution of the deep parts of continental crust but to understanding of the crust-mantle interaction. Detailed petrology, geochemistry and isotope geochronology of the Early Mesozoic mafic-ultramafic cumulate xenoliths and mafic granulite xenoliths and their host diorites from Harqin area, eastern Inner-Mongolia have been studied here. Systematic Rb-Sr isochron, ~(40)Ar-~(39)Ar and K-Ar datings for mafic-ultramafic cumulate xenoliths give ages ranging from 237Ma to 221Ma. Geochemical research and forming temperature and pressure estimates suggest that cumulates are products of the Early Mesozoic mantle-derived magmatic underplating and they formed in the magmatic ponds at the lowermost of the continental crust and are later enclaved by the dioritic magma. Detailed study on the first-discovered mafic granulite xenoliths reveals that their modal composition, mineral chemistry and metamorphic P-T conditions are all different from those of the Precambrian granulite exposed on the earth surface of the North China craton. High-resolution zircon U-Pb dating suggests that the granulite facies metamorphism may take place in 253 ～ 236Ma. Hypersthene single mineral K-Ar dating gives an age of 229Ma, which is believed to represent a cooling age of the granulite. As the host rock of the cumulate and granulite xenoliths, diorites intruded into Archean metamorphic rocks and Permian granite. They are mainly composed of grandodiorite, tonalite and monzogranite and show metaluminous and calc-alkaline features. Whole rock and single mineral K-Ar dating yields age of 221 ～ 223Ma, suggesting a rapid uplift in the forming process of the diorites. Detailed field investigation and geochemical characteristics indicate that these diorites with different rock types are comagmatic rocks, and they have no genetic correlation with cumulate and granulite xenoliths. Geochemical model simulating demonstrates that these diorites in different lithologies are products of highly partial melting of Archean amphibolite. It is considered that the Early Mesozoic underplating induced the intrusion of diorites, and it reflects an extensional geotectonic setting. Compression wave velocity V_P have been measured on 10 representative rock samples from the Early Mesozoic granulite and mafic-ultramafic cumulate xenoliths population as an aid to interpret in-situ seismic velocity data and investigating velocity variation with depth in a mafic lower crust. The experiments have been carried out at constant confining pressures up to 1000MPa and temperatures ranging from 20 ℃ to around 1300 ℃, using the ultrasonic transmission technique. After corrections for estimated in situ crustal pressures and temperatures, elastic wave velocities range from 6.5 ～ 7.4 km s~(-1). On the basis of these experimental data, the Early-Mesozoic continental compression velocity profile has also been reestablished and compared with those of the present and of the different tectonic environments in the world. The result shows that it is similar to the velocity structure of the extensional tectonic area, providing new constraints on the Early Mesozoic continental structure and tectonic evolution of the North-China craton. Combining with some newly advancements about the regional geology, the thesis further proposes some constraints on the Mesozoic geotectonic evolution history, especially the features of deep geology of the North China craton.

扬子板块西部大陆地幔地球化学特征及壳幔演化－有关基性岩超基性岩的地球化学研究

The continental mantle geochemical characteristics and crust-mantle evolution in the west of Yangtze Plate was discussed through the study of some within-plate basic-ultrabasic rocks from Lower Proterozoic to Later Paleozoic in this paper. In the Lower Proterozoic, the plate subduction between the pre-Tethys Proterozoic Ocean Plate and paleo-Yangtze Plate induced some basic volcanic formed in the island arc-back arc surrounding, which were represented by Ailaoshan Group-Dibadu Formation-Dahongshan Group, and there existed EM I component in the mantle source. The Middle Proterozoic Caiziyuan peridotite was formed in the epicontinental basin at the ocean-land boundary or within-continent rift basin. Its mantle source could be metasomatized by the dehydration fluid of subducted plate, and much initial radioactive ~(143)Nd was added to the source. In the Later Proterozoic, some rifts at the epicontinent or within-continent was formed due to the pre-Tethys oceanic plate subduction, and within-plate hot-spot Dahongshan diabase came into being. The whole-rock isochronal age of diabase is 1066±110Ma, and its mantle source was enriched Nd isotope and trace element which was related to the primary volatile component from asthenosphere and mantle plume. Its mantle source was included "FOZO" component representing mantle plume. The layer ultramafic rocks located at the Panxi Rift in the Middle-Later Paleozoic were resulted from different period and source. The early ultramafic indicated the incipient action of Panxi Rift, which is residue of continental lithospheric partial melting. Its mantle source involved subducted material and had distinct EM II component. The Emeishan basalt in the Later Paleozoic was typical continental flood basalt and its source also contained EM II component. The subduction of paleo-Tethys Ocean Plate provided essential dynamic condition for the large-scale opening of Panxi Rift, while the mantle plume supplied much material for Emeishan basalt. However, the plume was contaminated by the metasomatized continental mantle lithosphere in its upwelling process, which resulted in the Sr isotopic and incompatible elemental enrichment, and the Nd isotope kept down the weak-depleted character of mantle plume. The magmatic history in the west of Yangtze Plate is the tectonic process between pre-Tethys, paleo-Tethys Oceanic Plate and Yangtze Plate in a long history. Due to the subduction of oceanic plate, the crustal source material took part in the crust-mantle evolution widely. the continental mantle lithosphere in the west of Yangtze Plate was metasomatized by the fluid released by the subducted plate and the primary volatile from deeper mantle, and the mantle source include obvious enriched component.

北祁连与块状硫化物矿床有关的早古生代火山岩的地球化学研究

Different conclusions from previous work are made from the geochemical study for the early Paleozoic volcanic rocks hosting massive sulfide deposits in the north Qilian Orogen. The main points are: (1)The geochemical characteristics of the basalts and rhyolites from the Baiyin deposit are not consistent with that of the volcanic rocks in the continental rift setting, but show the relationship with subduction. The basalts and rhyolites from the Baiyin deposit are probably individual tectonic slice piled by subduction, and there is no bimodal volcanic rock suite occurred in the Baiyin deposit. Zircon U-Pb dating constrains the magmatic emplacement of basalts and rhyolites at 475±10Ma and 453±12Ma, respectively. The basalts are characterized by enriched Th and Sr, and depleted Nb, Ta and Ti. They have relatively high Th/Nb ratios between 0.9 and 1.3. Their εNd(T) values vary from -1.2 to +3.4. The chemical and isotopic compositions display a typical subduction-related signature, and they suggest that an enriched component with the isotopic composition of EMII might have contributed to the generation of the Baiyin basalts. The basalts were likely formed in a mature island-arc or a volcanic arc built on comparatively young or thin continental crust in an active continental margin. The rhyoIites have low concentrations of LILE compared to the basalts. They do not seen to have a relationship with the basalts, because of their significantly higher εNd(T) values (+4.3～+7.7). The high and positive εNd(T) values also rule out their derivation from anatexis of the continental crust. A modeling study suggests that the source.of the Zhe-Huo and Xiaotieshan rhyolites is similar to boninite and IAT (island-arc tholeiite), and hence indicating an intra-oceanic arc environment. (2) The formation of the Shangliugou volcanic rocks from .Qilian area is also related to subduction. The basaltic andesite have low TiO_2(0.45～0.63%) and P_2O_5(0.04～0.09) content, and high Th/Nb ratios (0.3～0.6). They show flat REE patterns. Their εNd(T) values vary in a narrow range from +4.8 to +6.4. The chemical and isotopic compositions indicate that they are derived from a slightly depleted mantle source and are fromed in intra-island arc setting. The rhyolites show calc-alkaline trend. They show enriched LREE and fiat HREE patterns with obvious negative Eu anomaly. They have high Th/Ta ratios (5.0 ～ 11.7) and large negative εNd(T) values (-2.6 ～ -8.4). The rhyolites are formed in active continental margin and result from a mixed process of two endmembers, or crust assimilation. (3) The metal elements of the volcanic-hosted massive sulfide deposit have two sources, the copper and zinc are derived from rhyolitic magmas whereas the lead are probably related to old sediments overlying the rhyolites. (4) It is suggested here that the volcanic rocks hosting massive sulfide deposit in the north Qilian orogen, which are previously considered as a bimodal suite of Neo-proterozoic to middle Cambrian age in a continental rift, are virtually related to subduction magmatism in Ordovician age, and there might have no continental rift magmatism of Neo-proterozoic to middle Cambrian in the north Qilian.

山东平度大庄子金矿床地质地球化学特征及成因——兼论层间滑动角砾岩型金矿成矿模式

The author selected the geological and geochemical characteristics and the genesis of the Dazhuangzi gold deposit in the Pingdu City as the central content of the study. The author summarized geological features of the other gold deposits formed within the same geological setting along the margin of the Jiaolai pull-apart basin and compared these gold deposits with the Dazhuangzi gold deposit. On the basis of the first-hand data obtained from field investigation and from mining production reports, ore-controlling structures, geological characteristics and mineralization regularities of the Dazhuangzi gold deposit are studied in detail. According to the analyzing results of petrochemistry, trace element, rare earth element and fluid inclusion etc., the geochemical characteristics, the genesis and the ore-forming material source of the Dazhuangzi gold deposit and that of the other similar gold deposits along the margin of the Jiaolai Basin are proposed. The study results suggest that the Dazhuangzi gold deposit belongs to the typical interstratified glide breccia type gold deposit, which is controlled by the interstratified glide fault structure located along the margin of the Mesozoic pull-apart Jiaolai basin. The interstratified glide fault structure is in the outer part of unconformity belt between the overlying strata and the basement of the pull-apart basin, being along the marble strata of the Jingshan group. The formation of the ore-controlling structure is related closely with the evolution of the Jiaolai Basin in the Mesozoic. The ore-controlling structure underwent the structural stress changes from compressive to tensional and then to compressive stress with strike slipping features sequentially, which were coincided with the regional tectonic stress evolution. The interstratified glide breccia type gold mineralization mainly occurs in the siliceous-marble breccias and cataclastic rocks within the interstratified glide fault structure. The gold minerogenetic epoch is later than 120Ma when the ore-controlling structure was tensioning and strike-slipping. The occurrences of the ore controlling structure and the gold ore bodies are the same as that of the unconformity belt. The geological and geochemical studies show that the source of the ore-forming material is alike with that of the volcanic rocks of the Qingshan formation, which is widespread in the Jiaolai Basin. Both of them came from the deep crust or even the upper mantle. Based on the geological characteristics and the minerogenetic regularities of the Dazhuangzi gold deposit, a genetic model of the deposit is constructed. In addition, the author used the remote sensing image and exploration results of geochemical and geophysical methods to point out several prospecting areas for further exploration. Through comprehensive study on the interstratified glide fault structure and on the interstratified glide breccia type gold deposits along the Jiaolai pull-apart basin, three types of interstratified glide structures and related gold mineralization are set up according to evolution and distribution of main fault as well as related secondary faults in time and space. They are named as Penjiakuang type, Dazhuangzi type and Fayunkuang type. The author summarized up the minerogenetic characteristics and regularities controlled by these three different types of interstratified glide structures respectively, and set up a general minerogenetic model of the interstratified glide breccia type gold deposit.

新疆东昆仑蛇绿岩岩石学、地球化学特征及其大地构造意义

The East Kunlun area of Xinjiang (briefly EKAX) is the western part of broadly speaking East Kunlun orogenic zone. The absence of geological data (especially ophiolites) on this area has constrained our recognition to its geology since many years. Fund by National 305 Item (96-915-06-03), this paper, by choosing the two ophiolite zones (Muztag and Southwestern Margin of Aqikekule Lake ophiolite zones) exposed at EKAX as the studied objects and by the analysis of thin section, electron probe, XRF, ICP-MS, SEM and Sm-Nd isotope, totally and sys ematically dealt with the field geological, petrological, minerological, petrochemical and geochemical characteristics (including trace, rare earth element and Sm-Nd isotope) and the tectonic setting indicated by them for each ophilite zone. Especially, this paper discussed the trace and rare earth element patterns for metamorphic peridotites, their implications and related them to the other components of ophiolite in order to totally disclose ophiolite origins. Besides, this paper also studied the petrological, geochemical and paleobiological characteristics for the cherts coexsisted with the Muztag ophiolite and the tectonic setting indicated by them. Based on these, the author discussed the tectonic evolution from Proterozoic to Permian for this area. For Muztag ophiolite, their field geological, petrological, minerological, petrochemical and geochemical characteristics show that: ① outcropped along the Muztag-Jingyuhu fault with west-to-east strike, the ophiolite is composed of such three components as metamorphic peridotites, cumulates and volcanic rocks; ② metamophic peridotites consist of such types as lherzolites, serpentinized lherzolites and serpentinites, only pyroxenites is seen of cumulates and volcanic rocks include basalts, basaltic andesites and andesites; ③ mineralogical data on this ophiolite suggest it formed in supra-subduction zone (SSZ)environment, and its mantle wedge is heterogeneous; ④ whole-rock TiO_2 and Al_2O_3 of metamorphic peridotites indicate their original environment with the MORB and SSZ characteristics; ⑤ metamorphic peridotites have depleted LREE and flat REE patterns and volcanic rocks have enriched LREE patterns; ⑥ trace element characteristics of metamorphic peridotites imply that they had undergone Nb and Ta enrichment event after partial melting; ⑦ trace element characteristics of volcanic rocks and their tectonic diagrams show they are formed in the spreading and developed island arc environment with back-arc basin, such as rifted island arc, which is supported by the ε_(Nd)(t) -2.11～+3.44. In summary, the above evidence implies that Muztag ophiolite is formed in SSZ environment, where heterogeneous mantle wedge was metasomatised by the silica-enriched melt from subducted sediments and/or oceanic crust, which makes the mantle wedge enriched again, and this enriched mantle wedge later partially melted to form the volcanic rocks. For Southwestern Margin of Aqikekule Lake ophiolite, their field geological, petrological, minerological, petrochemical and geochemical characteristics show that: ① it outcropped as tectonic slices along the near west-to-east strike Kunzhong fault and is composed of metamorphic perodotties, cumulates and volcanic rocks, in which, chromites are distributed in the upper part of metamorphic peridotites as pods, or in the lower part of cumulates as near-strata; ② metamorphic peridotites include serpentinites, chromite-bearing serpentinites, thlorite-epidote schists and chromitites, of which, chromitites have nodular and orbicular structure, and cumulates include pyroxenits, serpentinites, chromite-bearing serpentinites, chromites and metamorphically mafic rocks and only basalts are seen in volcanic rocks; ③ Cr# of chromites suggest that they formed in the SSZ and Al_2O_3 and TiO_2 of metamorphic peridotites also suggest SSZ environment; ④metamorphic peridotites have V type and enriched LREE patterns, cumulates have from strongly depleted LREE, flat REE to enriched LREE patterns with universally striking positive Eu anomalies and basalts show flat REE or slight enriched LREE patterns with no Eu anomalies; ⑤ trace element and Sm-Nd isotope characteristics of metamorphic peridotites imply their strikingly heterogeneous mantle character(ε_(Nd)(t)+4.39～+26.20) and later Nb, Ta fertilization; ⑥ trace element characteristics of basalts and their tectonic diagrams show they probably formed in the rifted island arc or back-arc basin enviromnent. In summary, the above evidence shows that this ophiolite formed in the SSZ environment and melts from subudcted plate are joined during its formation. Rare earth element, whole-rock and sedimentary characteristics of cherts with the Muztag ophiolite show that they formed in the continental margin environment with developed back-arc basin, and radiolarias in the cherts indicate that the upper age of Muztag ophiolite is early carboniferous. Based on the accreted wedge models of Professor Li Jiliang for Kunlunshan Mountain and combined with study on the two typical ophiolite profiles of EKAX, the author discussed the tectonic evolution of EKAX from Proterzoic to Permian.

生物－热催化过渡带沉积成岩演化及其成烃作用研究

The biothermocatalytic transitional zone gas is a new type of natural gas genetic theory, and also an clean, effective and high quality energy with shallow burial depth, wide distribution and few investment. Meanwhile, this puts biothermocatalytic transitional zone gas in important position to the energy resource and it is a challenging front study project. This paper introduces the concept, the present situation of study and developmental trend about biothermocatalytic transitional zone gas in detail. Then by using heat simulating of source rocks and catalysis mechanism analysis in the laboratory and studying structural evolution, sedimentation, diagenesis and the conditions of accumulation formation and so on, this paper also discusses catalytic mechanism and evolutionary model of the biothermocatalytic transitional zone gas formation, and establishes the methods of appraisal parameter and resources prediction about the biothermocatalytic transitional zone gas. At last, it shows that geochemical characteristics and differentiated mark of the biothermocatalytic transitional zone gas, and perfect natural gas genetic theory, and points out the conditions of accumulation formation, distribution characteristics and potential distribution region on the biothermocatalytic transitional zone gas m China. The paper mainly focuses on the formation mechanism and the resources potential about the biothermocatalytic transitional zone gas. Based on filed work, it is attached importance to a combination of macroscopic and microcosmic analysis, and the firsthand data are obtained to build up framework and model of the study by applying geologic theory. Based on sedimentary structure, it is expounded that structural actions have an effect on filling space and developmental cource of sediments and evolution of source rocks. Carried out sedimentary environment, sequence stratigraphy, sedimentary system and diagenesis and so on, it is concluded that diagenesis influences developmental evolution of source rocks, and basic geologic conditions of the biothermocatalytic transitional zone gas. Applying experiment simulating and catalytic simulating as well as chemical analysis, catalytic mechanism of clay minerals is discussed. Combined diagenecic dynamics with isotope fractionation dynamics, it is established that basis and method of resource appraisal about the biothermocatalytic transitional zone gas. All these results effectively assess and predict oil&gas resources about the biothermocatalytic transitional zone gas-bearing typical basin in China. I read more than 170 volumes on the biothermocatalytic transitional zone gas and complete the dissertation' summary with some 2.4 ten thousand words, draw up study contents in some detail and set up feasible experimental method and technologic course. 160 pieces of samples are obtained in oilfield such as Liaohe, Shengli, Dagang and Subei and so on, some 86 natural gas samples and more than 30 crude oil samples. Core profiles about 12 wells were observed and some 300 geologic photos were taken. Six papers were published in the center academic journal at home and abroad. Collected samples were analysised more than 1000 times, at last I complete this dissertation with more than 8 ten thousand words, and with 40 figures and 4 plates. According to these studies, it is concluded the following results and understandings. 1. The study indicates structural evolution and action of sedimentary basin influence and control the formation and accumulation the biothermocatalytic transitional zone gas. Then, the structural action can not only control accommodation space of sediments and the origin, migration and accumulation of hydrocarbon matters, but also can supply the origin of energy for hygrocarbon matters foramtion. 2. Sedimentary environments of the biothermocatalytic transitional zone gas are lake, river and swamp delta- alluvial fan sedimentary systems, having a warm, hot and humid climate. Fluctuation of lake level is from low to high., frequency, and piling rate of sedimentary center is high, which reflect a stable depression and rapidly filling sedimentary course, then resulting in source rocks with organic matter. 3. The paper perfects the natural gas genetic theory which is compound and continuous. It expounds the biothermocatalytic transitional zone gas is a special gas formation stage in continuous evolutionary sequence of organic matter, whose exogenic force is temperture and catalysis of clay minerals, at the same time, having decarbxylation, deamination and so on. 4. The methodology is established which is a combination of SEM, TEM and Engery spectrum analysis to identify microstructure of crystal morphology about clay minerals. Using differential thermal-chromatographic analysis, it can understand that hydrocarbon formation potential of different typies kerogens and catalytic method of all kinds of mineral matrix, and improve the surface acidity technology of clay minerals measured by the pyridine analytic method. 5. The experiments confirm catalysis of clay minerals to organic matter hygrocarbon formation. At low temperature (<300 ℃), there is mainly catalysis of montmorillonite, which can improve 2-3 times about produced gas of organic matters and the pyrolyzed temperature decreased 50 ℃; while at the high temperature, there is mainly catalysis of illite which can improve more than 2 times about produced gas of organic matters. 6. It is established the function relationship between organic matter (reactant) concentration and temperature, pressure, time, water and so on, that is C=f (D, t). Using Rali isotope fractionation effect to get methane isotope fractionation formula. According to the relationship between isotope fractionation of diagenesis and depth, and combined with sedimentary rate of the region, it is estimated that relict gas of the biothermocatalytic transitional zone gas in the representative basin. 7. It is revealed that hydrocarbon formation mechanism of the biothermocatalytic transitional zone gas is mainly from montmorillonite to mixed minerals during diagenesis. In interlayer, a lot of Al~(3+) substitute for Si~(4+), resulting in a imbalance between surface charge and interlayer charge of clay minerals and the occurrence of the Lewis and Bronsted acid sites, which promote to form the carbon cation. The cation can form alkene or small carbon cation. 8. It is addressed the comprehensive identification mark of the biothermo - catalytic transitional zone gas. In the temproal-spatial' distribution, its source rocks is mainly Palaeogene, secondly Cretaceous and Jurassic of Mesozoic, Triassic, having mudy rocks and coal-rich, their organic carbon being 0.2% and 0.4% respectively. The vitrinite reflection factor in source rocks Ro is 0.3-0.65%, a few up to 0.2%. The burial depth is 1000-3000m, being characterized by emerge of itself, reservoir of itself, shallow burial depth. In the transitional zone, from shallow to deep, contents of montmorillonites are progressively reduced while contents of illites increasing. Under SEM, it is observed that montmorillonites change into illite.s, firstly being mixed illite/ montmorillonite with burr-like, then itlite with silk-like. Carbon isotope of methane in the biothermocatatytic transitional zone gas , namely δ~(13)C_1-45‰- -60 ‰. 9. From the evolutionary sequence of time, distribution of the biothermocatalytic transitional zone gas is mainly oil&gas bearing basin in the Mesozoic-Neozoic Era. From the distribution region, it is mainly eastern stuctural active region and three large depressions in Bohaiwang basin. But most of them are located in evolutionary stage of the transitional zone, having the better relationship between produced, reservoir and seal layers, which is favorable about forming the biothermocatalytic transitional zone gas reservoir, and finding large gas (oil) field.

山东莱芜中生代高镁侵入岩及其超镁铁质岩捕掳体的成因研究

In order to know better about the Phanerozoic lithosphere thinning process of Sino-Korea Plate, four Cretaceous intrusion complexes and their ultramafic xenoliths are investigated by this thesis, which are located in Laiwu, Shandong Province, Eastern China, a region far away from plate margin. The four complexes, Kuanshan, Jiaoyu, Jingniushan and Tietonggou, intruded into Archaeozoic granite gneiss and Paleozoic carbonate rocks with scam iron ore at their contact zone. The four complexes can be divided into two magma series, abyssal rocks for the early and hypabyssal rocks for the later. K-Ar dating show that the abyssal rocks intrusion began with 120 ±2 Ma and the hypabyssal rocks intruded about 113 Ma. Abyssal rocks, mainly made up of augite diorites, amphibole diorites and gabbros for the lesser, are chemically characterized with high-Mg (Mg#>0.5) high-K calcalklic rock, which are depleted with Nb, Ta and Ti related to LILE and extremely enriched with Sr and Pb. Comparatively, augite diorites are the most LREE enriched in abyssal rocks, and they show no Eu abnorrnity or weak positive Eu abnormity. Gabbros show the least LREE enrichment with a strong Eu abnormity relatively. In (~(87)Sr/~(86)Sr)_1 -ε Nd(T) diagram, the abyssal rocks show a mixing trend , a rapid change in ε Nd(T) with a relatively small change in (~(87)Sr/~(86)Sr)_1. Low radiogenic Sr and Pb composition with high radiogeic Nd composition indicate that the mixing processes happened in lower crust Melt-rock interactions in lower crust might be the most possible processes to produce these high-Mg and high-K calcalklic magmas. Hypabyssal rocks, mainly made up of granite porphyry and dioritic porphrite, show much higher ε Nd(T) than abyssal rocks. Granite porphyry are distinct with an adakite geochemical characteristics, high (La/Yb)_N, Sr/Y and low Rb/Sr ratio. The adakitic granite porphyry indicates a new lower crust produced by underplating within plate. Ultramafic xenoliths had been found only in augite diorites and amphibole diorites. Field investigations show that ultramafic xenoliths in augite diorites had been inherited from amphibole diorites, so ultramafic xenoliths had been only entrained by hydrous dioritic magma. Ultramafic xenoliths are mainly made up of dunite and harzburgite, orthopyroxenite and bistangite are the lessor. Coarse olivines in dunite often show many chromite exsolution lamellae. Opx in orthopyroxenite often show dense chromite exsolution lamellae. The presence of exsolution minerals indicates that ultramafic xenoliths had cooled before entraining. Metasomatism phenomenons are popular in dunite and harzburgite xenoliths, including two kinds of assemblage, cpx+phlogapite and opx+pl. The first metasomatism assemblage indicates an ancient enrichment. Rb-Sr dating of xenoliths shows that the ancient enrichment happened in 223 ± 7Ma. The second metasomatism assemblage indicates a recent, relatively not deep melt-rock interaction, which might be related with the genesis of the high-Mg high-K calcalklic rocks. Mineralogy and geochemistry indicate that these ultramafic xenoliths might sample the crust-mante transition zone (or the base of lower crust, moho). Investigation of high-Mg intrusions and their ultramafic xenoliths in Laiwu indicate that the thinning processes of Sino-Korea Plate can be divided into two stages. The first stage is lithosphere mantle thinning with crust thickening by underplating in lower crust. The second stage is that the thickened lower crust delaminated into the underlying mantle.

塔里木盆地奥陶系不整合面岩溶作用特征与油气储层研究

Based on the principle and methods of carbonate sedimentology and reservoir geology, and guided by the theories of carbonate reservoir geology, the palaeokarst of Ordovician carbonate rocks in Tarim Basin has been comprehensively studied with multiple methods from different branches of geology. It is indicated that the features and distribution of palaeokarstification have developed in Ordovician carbonates. The controlling of karstification to Ordovician carbonate reservoirs has been discussed. Regional distribution of carbonate reservoirs controlled by karstification has been predicted within this basin. The main consents and conclusions of the this dissertation is as follows: Nine key indicators to the recognition of palaeokarst are proposed in terms of careful observation upon the well cores, lithological and geochemical analyses, and drilling and logging responses to the karst caves and fractures. The time and environment of cave filling are documented from careful research of lithofacies, mineralogy, and geochemistry of the physical and chemical fillings within karst caves. The caves in Ordovician carbonates were filled in Early Carboniferous in Lunnan area. The muddy filling in upper caves was deposited under subaerial fresh-water setting, while the muddy filling in lower caves was formed in the mixed water body of fresh-water and dominated sea water. Although most chemical fillings are suggested being precipated in the burial diagenetic environment after karstification but mineralogic and geochemical characteristics of some chemical fillings indicates they formed in meteoric environment during the karstification. It is obvious that the palaeokarst has been zoned in vertical profile. It can be divided into four units from top to bottom: surface karst, vadose karst, phreatic and tranquil flow zones. Between two types of limestone karst and dolostone karst are firstly differentiated in Tarim Basin, based on the comparison of features of each karst zone in limestone and dolostone regions. In Tabei area, the lowest depth of karstification is approximately 300 m below the Upper Ordovician unconformity interface, while the bottom depth of karstification in Tazhong area ranges commonly from 300 to 400 m, in rare cases may be up to 750 m below the upper Ordovician unconformity interface. In Lunnan and Tazhong areas, the palaeokarst morphology and the surface hydrosystem are firstly reconstructed based on the top of carboniferous "Shuangfeng limestone bed (Double-Peaks limestone)" as basal. According to the palaeomorphologic feature, karst topography can be divided into three units: karst upland, karst slope, and karst valley. Vadose zone was well developed in karst upland, and it can be found in a quite depth. Both vadose and phreatic zones were well developed in karst slope and upstream valley. In downstream valley, the karstification is not strong, the vadose and phreatic zones are thin in thickness. In Tazhong and Yingmaili areas, karstification is also developed in relict carbonate palaeo-hills which existed as isolated blocks admits clastic strata.

山东西部中生代碳酸岩和火山岩的地球化学特征及其成因研究

On account of some very peculiar features, such as extremely high Sr and Nd contents which can buffer their primary isotopic signatures against crustal contamination, deep-seated origin within mantle, and quick ascent in lithosphere, carbonatites are very suitable for deciphering the nature of sub-continental lithospheric mantle(SCLM) and receiving widespread attentions all around the world. The Mesozoic carbonatites located in western Shandong was comprehensively investigated in this dissertation. The extremely high REE concentrations, similar spider diagrams to most other carbonatites around the world and high Sr. low Mn contents of apatite from carbonatites confirm their igneous origin. The K depletion of carbonatites from this studies reflect the co-existing of carbonatite melts with pargasite+phlogopite lherzolite rather than phlogopite lherzolite. Geological characteristics and their occumng without associated silicate rocks argue against their origin of fractionation of or liquid immisibility with carbonated silicate melts. In contrast to the low S7Sr/86Sr and high l43Nd/l44Nd of other carbonatites in the world, carbonatites of this studies show EMU features with high S7Sr/86Sr and low l4jNd/144Nd ratios, which imply that this enriched nature was formed through metasomatism of enriched mantle preexisted beneath the Sino-korean craton by partial melts of subducted middle-lower crust of Yangtze craton. In addition to carbonatites, the coeval Mesozoic volcanic rocks from western Shandong were also studied in this dissertation. Mengyin and Pingyi volcanic rocks, which located in the south parts of western Shandong are shoshonite geochemically. while volcanic rocks cropped out in other places are high-K calc-alkaline series. All these volcanic rocks enriched in LREE and LILE. depleted in HFSE, and show TNT(strong negative anomalies in Ta, Nb. Ti) patterns in spider diagrams which are common phenomena in arc-related volcanic rocks. The Sr-Nd-Pb isotopic systematics reveal that the volcanic rocks decrease gradually in 87Sr/86Sr, 206Pb/204Pb, 20SPb/204Pb and increase in TDM from south to north, suggesting the distinction of SCLM beneath Shandong in Mesozoic is more explicit in south-north trending than in east-west trending. The variable features of SCLM can be attributed to the subduction of Yangtze craton beneath Sino-Korean craton, and subsequent metasomatism of SCLM by partial melts of Yangtze lower crust in different extent.

胶北晚中生代煌斑岩的岩石地球化学特征及其成因研究

胶北煌斑岩分别采自龙口、烟台和威海地区，包括拉辉煌斑岩、斜闪正煌岩和角闪煌斑岩，煌斑岩K—Ar全岩年龄变化于89．3～169．5Ma，为晚中生代岩浆活动的产物。在岩石化学组成上，SiO2=42．02％～54．95％，以钙碱性系列为主．岩石以富集大离子亲石元素（LILE）（Ba，U，K，Th）和LREE，亏损高场强元素（HFSE）（Nb，Ta和Ti）为特征，Mg^#=33．9～53．9，Eu／Eu^＊=0．71～0．89，^87Sr／^86Sr初始比值0．707642～0．709791，εNd（t）为-17．6～-10．4，^206Pb／^204Pb=37．588～38．431，^207Pb／^204Pb=15．423～15．531，^206Pb／^204Pb=17．204～18．179。表明煌斑岩源自俯冲陆壳（扬子下地壳）在地幔源区发生交代作用时形成的富集型地幔的部分熔融体．考虑到煌斑岩具有大陆边缘弧玄武岩的特征，我们认为煌斑岩在成因上同样与古大洋板块的俯冲作用有关，为碰撞后弧岩浆作用形成的脉岩。

吐哈盆地砂岩型铀矿含矿主岩沉积体系及地球化学特征

吐哈盆地位于哈萨克斯坦板块的东端，与邻国盛产可地浸砂岩型铀矿的中新生代盆地处于统一类型的板块，同属中亚构造－成矿域。吐哈盆地也是我国可地浸砂岩型铀矿的第二个勘查基地。对吐哈盆地砂岩型铀矿的主要含矿建造－中下侏罗统水西沟群沉积体系类型的研究，将有助于区内对砂岩型铀矿成矿和容矿的主要沉积建造的地质认识。而对含矿主岩的地质地球化学研究，则能为区内砂岩型铀矿的成矿作用研究提供依据。在对吐哈盆地形成演化历史分析的基础上，通过对早中侏罗世盆地沉积建造的资料综合、野外调查和室内研究，针对可地浸砂岩型铀矿的地质特征、形成条件等，围绕建造-构造、构造-改造、改造-成矿作用的关系等问题，从区域地质构造背景、沉积体系类型分析和构造变形特征等宏观研究入手，到对钻孔岩芯的微观分析研究，特别是在对十红滩铀矿区的重点解剖的基础上，结合光谱信息提取与增强技术的应用，甄别含矿建造的地质特征及其时空分布格局，对吐哈盆地砂岩型铀矿主含矿岩系的沉积体系类型及其地球化学特征的研究得到以下认识： 1. 吐哈盆地中下侏罗统水西沟群的沉积体系类型包括：冲积扇沉积、辫状河沉积、辫状三角洲沉积系和湖泊沉积。而吐哈盆地十红滩铀矿区砂岩型铀矿的含矿主岩的沉积体系类型则为源自南部觉罗塔格山的辫状三角洲沉积体系。 吐哈盆地十红滩铀矿区砂岩型铀矿的含矿主岩是在盆地短轴方向上的局部性水动力条件和沉积环境下形成的一套以近源短距离搬运形成的粗碎屑沉积建造。这套建造及其沉积体系类型与整个湖盆地的泛湖沉积作用在时间和空间上发生叠置。正是因为不同沉积体系类型在时间和空间上发生叠置，从而导致中下侏罗统的地层总体走向与砂砾岩等粗碎屑沉积体的整体走向有显著的差异。沉积建造的这种空间展布格局对砂岩型铀矿的形成具有重要的控制作用。总体上，这一特点决定了与砂岩型铀矿成矿作用有关的含铀流体的运移方向、规模和铀成矿作用的区域分布和空间展布。 2. 鉴于吐哈盆地中下侏罗统不同沉积体系类型的区域分布和空间展布特征，以及内陆沉积盆地的沉积作用具有相似的沉积格局，建议在查明有利于砂岩型铀矿成矿的砂体所属沉积体系类型的基础上，按沉积体系类型划分沉积单元进行地层的划分与对比，将这一方法运用于内陆沉积盆地的地层划分对比，便于对砂岩型铀矿成矿的最基本控制因素“砂体”的宏观控制，从而为砂岩铀矿成矿作用分析、区域成矿预测和资源勘查提供直接依据。因此，正确区分泛湖水动力体系的区域性沉积系统及其沉积体系和局部性水动力体系的局域性沉积系统及其沉积体系，不仅具有地层学上的意义，更具有实际应用价值。 3. 吐哈盆地艾丁湖斜坡带中下侏罗统的构造变形特征存在明显的空间差异。主要表现为：在横向上，沿艾丁湖斜坡带由东往西不同地段构造形迹不同；在纵向上，不同层位的变形特点各异。总体表现为：以十红滩铀矿区为中心，往东以水西沟群上部第三岩性段（J2x3）的构造反转、逆冲而出现断裂构造为主。中部十红滩一带以水西沟群下部第一层位（J2x1）的宽缓褶皱为主。往西以西山窑组中部第二岩性段（J2x2）较为强烈的地层褶皱为特征。说明中下侏罗统形成之后，遭受过区域性的构造改造。 4. 对钻孔砂岩样品的岩石学研究和显微构造观察表明，十红滩铀矿区含矿砂体最为常见的碎屑有石英、长石（钾长石为主，少量斜长石）、云母以及花岗质岩屑、变质岩岩屑、少量火山岩岩屑，偶见沉积岩岩屑；砂岩中的填隙物主要有高岭石、水云母、绿泥石以及碳酸盐类矿物和少量铁质矿物。胶结物通常为碳酸盐、硅质及一些铁质物质。胶结类型主要有基底式胶结、孔隙式胶结和压嵌式三种类型。且砂岩中存在多期次构造－流体改造的迹象。在整体上，含矿砂体与无矿砂体构造－流体改造的类型相近，但其改造程度各不相同。含矿砂体主要表现为微构造裂隙发育，并有多期次硅质、碳酸盐充填和交代、溶蚀现象。含有石英、高岭石、绿泥石等新生矿物；不含矿砂体则以绿泥石化普遍，碳酸盐化作用强为主要特征。 样品中的蚀变矿物出现微晶黑云母、绿泥石－绿帘石－石英共生矿物组合，出现脆韧性显微构造变形等，预示这套含矿建造曾经遭受过一定程度的构造热变质作用。 5. 钻孔岩芯砂岩样品的稀土、微量元素地球化学特征表明，十红滩铀矿区的砂岩具有统一的物质来源。其稀土配分型式与蚀源区花岗质岩石的稀土配分型式相似。区域氧化作用造成砂体矿物蚀变的同时，也造成砂岩中稀土元素的分馏，且氧化蚀变越强，稀土元素的分馏作用也越明显。与晚元古代黑色页岩平均值相比，十红滩铀矿床钻孔中砂岩Zr和Hf的含量普遍偏高，特别是Hf，大部分样品中的Hf含量均高于晚元古代黑色页岩平均值。 zk32-11-2、zk96-4、zk96-7、zk80-6四个钻孔岩芯的砂岩样品稀土元素特征值δEu，在不同深度的各砂岩中变化较大。无论是单孔还是在钻孔之间，δEu值都表现为跳跃式的变化，且整体上分流河道砂岩中δEu值偏低。相对于δEu值，δCe和TE（1，3）值似乎表现出一定的变化规律。总体上表现为在与泥岩、泥质粉砂岩呈互层产出的三角洲前缘砂岩中，具有较为相近的δCe和TE（1，3）值。而分流河道砂体的δCe和TE（1，3）值相对变化较大，且整体上数值偏小。这些样品稀土元素特征值δEu、δCe和TE（1，3）所表现出的特点与砂体的沉积体系类型分析以及相应的岩石学特点基本吻合。说明不同沉积系统的各类沉积体系，不仅在时空展布上存在差异，砂体的结构及物质组成也存在一定的差异。 6. 根据中下侏罗统不同沉积体系类型在吐哈盆地全域范围的时空配置以及遥感地学的区域氧化还原条件分析，并与十红滩铀矿区相比较，吐哈盆地西部阿拉沟口、柯尔碱一带和了敦隆起西缘的鄯善－小草湖一带，具有和十红滩铀矿区类似的沉积历史、建造特征和区域氧化－还原条件，可以作为进一步开展砂岩型铀矿成矿预测和资源勘查的地段。 7．吐哈盆地的砂岩型铀矿与中亚各国重要的可地浸砂岩型铀矿在盆地类型、含矿主岩的沉积体系、含矿主岩的时代等方面有一定的差异，而其盆地类型及含矿主岩的沉积体系与美国怀俄明地区的可地浸砂岩型铀矿，特别是温得河盆地的砂岩型铀矿的特点较为相似。 8. 遥感信息提取和地学分析，可以提供区域性氧化－还原环境的区域分布信息，甚至可以为寻找潜在有利含矿砂体的空间展布提供依据；借助GIS平台，充分利用3S技术的集成与应用，可望为北方干旱地区可地浸砂岩型铀矿成矿条件分析、远景预测和找矿靶区的快速圈定乃至进行资源勘查的实际工作部署提供新的可操作技术平台。 在取得这些认识的同时，也深感还有不少问题需要进一步补充工作和深入探讨。特别是有关砂岩型铀矿的矿物学和地球化学方面尚有许多现象目前还不能给予很好的解释；对于存在的多次构造－流体的改造作用机理、多期次构造－流体活动之间的相互联系及其与铀矿化的关系；对流体的性质、来源和流体与砂体之间的相互作用关系等还有大量工作需要补充和深入。虽然已获得大量有关砂岩的稀土、微量元素的数据，但对这些数据的处理方法有限，对于其反映的与区内砂岩型铀矿成矿作用有关的信息有待进一步挖掘。另外，由于未能采集到砂岩铀矿的矿石样品，针对铀矿床方面的工作未能开展。

湖泊沉积物中有机磷的地球化学特征及其富营养化效应——以太湖、红枫湖、百花湖和洱海为例

磷是水生生态系统初级生产力的主要限制因子，也是造成湖泊富营养化的关键营养元素。湖泊富营养化现已成为世界性的环境问题，它不但制约了湖泊资源的可利用性,而且直接影响着人类的健康生存与社会经济的可持续发展。沉积物内源磷的释放是决定湖泊水体营养水平、影响湖泊富营养化治理成效的重要因素。因此，研究沉积物中磷的组成形态、含量分布及迁移转化等对于全面了解湖泊生态系统中磷的生物地球化学循环，有效控制和管理湖泊富营养化具有重要的意义。然而目前对沉积物中的无机磷(Pi)及其生物可利用性进行了大量的研究，有机磷(Po)作为沉积物中的重要化学成分，它的地球化学特征及其对湖泊富营养化的作用却了解甚少。 长江中下游地区和云贵高原地区是我国淡水湖泊的主要分布区，也是我国湖泊富营养化最为严重的地区。本论文工作选取两地区具不同流域特征、水文状况、生态结构、污染程度的代表性湖泊(太湖梅梁湾、鼋头渚、贡湖、东太湖, 红枫湖, 百花湖和洱海)为研究对象，结合传统的化学连续提取手段和最新的液体磷核磁共振(31P NMR)波谱分析，研究了这些湖泊沉积物中Po的形态、组成以及剖面分布特征，揭示了Po对湖泊富营养化的重要作用；并运用高效体积排阻色谱法、分子荧光光谱法探讨了它们与沉积物中有机质的关系。主要研究结果如下： 1. 采用改进的土壤Po分级体系研究湖泊沉积物中Po的赋存形态，沉积物中Po的回收率可达94.3－101.1%，平均为98.5±2.2%，说明了该方法基本上包括了沉积物中全部Po。这是因为本方法对活性Po和腐殖质磷萃取的时间更长，提取更为完全；对富里酸磷和胡敏酸磷的区分更加明确；还特别增加了残渣态有机磷(Residual Po)的测定，使得Po的形态分析更为周密和准确。沉积物中Residual Po的含量占总Po的29.9－57.2%，进一步表明了此方法的可取性，这将为以后开展湖泊沉积物中Po的形态研究奠定了基础。 2. 湖泊沉积物中磷形态的不同分布特征可能与两地区不同的湖泊类型、有机质降解过程的差异以及各种磷形态之间的相互转化有关。Po形态在不同污染程度沉积物中的含量与分布也充分说明了沉积物是水体富营养化的主要内源，Po对湖泊富养化的作用不容忽视。 3.太湖梅梁湾、鼋头渚和贡湖沉积物不同提取液中有机质的分子量分布特征可能表明了其中有机质和Po组成的差异，而沉积物中有机C/N和C/P比值分析和三维荧光光谱特征的相似形可能反映了太湖(浅水湖泊)沉积物中有机质与磷的地球化学特性及其相互关系。 4. 31P NMR的测定结果显示，湖泊沉积物中磷主要由正磷酸盐(Ortho-P)、磷酸单酯(Monoester-P)与二酯(Diester-P)组成，焦磷酸盐(Pyro-P)和膦酸盐(Phosphonate)的含量非常低。Ortho-P在重富营养化和浅水湖泊沉积物中的相对含量高于富营养化、中富营养化和深水湖泊沉积物，Monoester-P的分布特征正好相反，表明了这些磷化合物在不同湖泊生态系统磷的循环中的差异。此外，Monoester-P中肌糖磷酸的大量存在，也同时证实了前面Po化学连续提取中高含量的Residual Po。 5. 梅梁湾和洱海沉积物中总磷(TP)、Pi、Ortho-P、Monoester-P、总有机碳(TOC)和总氮(TN)表现出不同的剖面分布特征，说明了有机质和磷在不同湖泊环境中的分解转化规律，可能解释了内源磷的释放对两湖富营养化的影响。此外，Diester-P中DNA-P的剖面变化和前人报道的沉积物中DNA的分布特征正好吻合，表明了DNA-P主要来源于沉积物中细菌和微生物的DNA。

浙江省矾山明矾石矿床地球化学特征兼论中生代成矿体系

矾山明矾石矿床位于江山－绍兴深断裂南东侧，海西印支褶皱带的南东侧，中国板块东南构造区与太平洋板块的交接处，属于中国板块东南构造区。该矿床产在矾山破火山口内，是一个超大型明矾石矿床，同时矿床中的钒、镓含量也达到了综合利用的品位。该矿床研究程度低，缺少地球化学特征研究。因此，本次工作系统研究了该矿床常量元素、微量元素、稀土元素、硫和铅同位素地球化学特征。本次对明矾石矿床的研究获得以下几点初步认识： 1：成矿物质来源于火山岩。矿区火山岩中的K、Al、Na等矿石元素含量明显比其他地区高，并且从围岩→矿化围岩→矿石呈明显的富集趋势。稀土资料和铅同位素资料也都表明成矿物质来源于中生代火山岩。 2：V、Ga含量达到了综合利用的品位。微量元素资料表明，矿石中V平均含量为211.6ppm，Ga平均含量为16.78ppm，都大于地壳丰度，尤其是V远大于地壳丰度；同时发现，成矿时V以V¬5＋形式通过与Al3＋发生类质同像进入明矾石晶格，而矿石中Ga含量除与Al3＋外还与Fe3＋含量有关。 3：明矾石的稀土元素地球化学特征比较复杂。根据δEu值不同可分为三类： Eu弱负异常型，Eu弱正异常型和Eu强正异常型。影响稀土元素分布的因素主要为成矿原岩中富含碱性长石和成矿时的氧逸度和温度，另外矿石结构（如孔隙度）对稀土元素分布也有影响。研究表明，矿石稀土配分模式为轻稀土富集型，与火山岩基本一致。 4：硫同位素研究发现，黄铁矿的δ34S值为1.9～3.2‰，明矾石的δ34S值为13.62～16.02‰，后者明显大于前者。本次研究认为黄铁矿的δ34S值代表当时的岩浆源硫，而明矾石较大的δ34S值为岩浆硫经过同位素分馏的结果。铅同位素研究发现，明矾石矿石的206Pb/204Pb＝17.963～18.606，207Pb/204Pb＝15.439～15.672，208Pb/204Pb＝38.405～38.796。通过与中生代火山岩和基底变质岩的对比，本次研究认为明矾石的铅源为中生代火山岩来源，与基底变质岩并无直接的来源关系。 5：通过明矾石矿床的地球化学特征研究，结合实际地质特征和前人研究成果，本次研究提出了以下矿床成因：明矾石矿床形成环境为浅成低温氧化环境；成矿物质来源于围岩，成矿所需的硫源为分馏的岩浆硫；矿床形成时期为73～95Ma，比围岩晚10～20Ma；矿床成因为火山热液交代成因。 浙江省中生代火山岩成矿体系主要指受浙江省中生代火山构造、岩浆活动控制的一系列不同类型的矿床组合。成矿体系主要受江绍深断裂带和中生代陆相火山岩控制。前人对成矿体系中的单一矿床研究较多，但是缺少横向对比研究。本次工作主要通过对成矿体系中的两类矿床（金属矿床和非金属矿床）进行对比研究，结合中生代火山岩演化过程，初步探索成矿体系中各类矿床间的联系以及成矿体系与火山岩演变的关系。本次工作取得以下几点初步认识： 1：成矿体系中各类矿床的整体分布受江绍深断裂、温州－镇海大断裂等一些深大断裂控制。各矿床的具体控（容）矿构造都为次级压－压扭性断裂和破火山口构造，其中破火山口构造在成矿过程中占非常重要的作用。 2：成矿体系中各类矿床的成矿温度低，深度浅，为典型的浅成低温矿床。 3：铅同位素资料表明，矿床的铅源为中生代火山岩来源，与基底并无直接联系。氢氧同位素资料表明，各类矿床的成矿流体以中生代大气降水为主，岩浆水占很少部分或并无参与成矿。 4：成矿体系存在明显的成矿成岩时差，金属矿床在12.44～45.6Ma，萤石矿床为25～75Ma，其他非金属矿床为10～20Ma；铅锌（银）金等金属矿床为具有明显的两期成矿特征。

贵阳市不同土地利用方式土壤有机碳地球化学研究

本研究根据贵阳市区域内不同土地利用方式，选择了自然土壤、农业土壤和城市土壤为主要研究对象。对表层土壤实行多样点的统计分析、以及典型剖面有机碳迁移过程分析，同时结合同位素地球化学示踪原理，探讨了贵阳市区域内土地利用方式变化对土壤有机碳的影响，以及不同土地利用方式间土壤有机碳的来源和降解过程的差异。主要结论如下： (1) 自然土壤转化为农业土壤后，表层(0～10cm) SOC有较为明显的降低趋势。其中，相对于自然土壤(黄壤) 表层SOC(平均值)而言，玉米地、水田、果园下降了40%左右，菜地下降了15%左右。然而，不同菜地土壤间耕种强度存在较大差异，其SOC变异程度高于其它几类农业土壤(CV＝57.07%)。与之相反，农业土壤表层DOC(18.86～48.20mg•L-1)接近或超过自然土壤(10.74～36.30 mg•L-1)，且ƒDOC占SOC的比例明显大于自然土壤。其中，玉米地DOC最高(平均值：48.20mg•L-1)，菜地次之(平均值：30.00mg•L-1)，果园第三(平均值：29.87mg•L-1)，水田最低(平均值：18.86mg•L-1)，但水田由于干湿交替的影响，DOC的变异程度最大(CV＝128.57%)。据此推断，在相同气候条件下，自然土壤转化为农业土壤后，由于表层DOC数量和比例的增加，提高了SOC的迁移性，进而加速了碳素在土壤中的迁移转化进程。 (2) 自然土壤转化为农业土壤后，剖面内部(>10cm)多数层次SOC相对于黄壤和黄色石灰土有明显的增加趋势。且通过对不同类型农业土壤人为干扰强度的调查表明：人为干扰强度越强，剖面中一定深度内SOC增加幅度越大。即：离城市较近的菜地2增长最为突出，果园其次，水田和玉米地相当。离城市较远的菜地1由于受人为干扰层次较浅，且出现了犁底层，剖面内SOC的含量水平与黄色石灰土相当。 (3) 原始土壤经搬运重组后形成城市公路绿化带土壤，表层SOC和DOC变幅较宽、离散程度较大，且没有随时间或植被类型等因素的变化而呈现明显的变化趋势。其中，SOC变异程度依次为新成公路绿化带2(CV＝58.0％)、老成公路绿化带(CV＝55.5％)、新成公路绿化带1(CV＝34.1％)。DOC变异程度依次为新成公路绿化带1(CV＝93.8％)、新成公路绿化带2(CV＝85.7％)、老成公路绿化带(CV＝78.0％)。 (4) 在自然土壤、农业土壤和城市绿化带土壤表层中，DOC与SOC、N、C/N、NO3-、NH4-，以及粘粒含量等的相关性均未达到显著水平。另据方差分析显示：果园、水田、菜地和玉米地表层土壤间DOC、SOC含量均无显著差异，说明农业土壤利用方式不是决定土壤表层SOC和DOC含量的绝对因素；新成公路绿化带1，2和老成公路绿化带表层土壤间DOC、SOC含量均无显著差异，说明植被类别和形成时间不是决定土壤表层SOC和DOC含量的绝对因素。 (5) 自然土壤中，枯枝落叶转化为表层(0～5cm)土壤有机质后，δ13CSOC值升高了1~4‰。通过不同碳源间δ13Corg相互关系的判断，在具备枯枝落叶覆盖的表层土壤中，DOC主要来源于枯枝落叶；而在土壤剖面内，随土壤剖面深度的增加，来自于土壤腐殖类物质的DOC占土壤DOC总量的比例呈增加趋势。在黄壤和黄色石灰土中(>5cm土层)，土壤剖面中大多数层次DOC比SOC更富13C。 (6) 大多数农业土壤有机碳δ13C值显示其有机肥源中存在C4-C源。且农业土壤中受碳源多样性的影响，菜地、果园、水田和玉米地表层土壤中δ13CSOC与δ13CDOC的相关性均未达到显著水平。其次，除玉米地土壤剖面外，其它供试农业土壤剖面大多数层次δ13CDOC值比δ13CSOC偏负，说明菜地、果园、水田土壤DOC主要为外源的加入。 (7) C3植被转化为C4植被(林-农生态系统转化)后，玉米地剖面中SOC有2.55％～20.80％源于C4-C，随剖面层次的加深有降低趋势，但表现为“之”字形反复；DOC中C4-C的比例在剖面0～40cm处较为相近(25.94％～34.54％)，40cm以下则急剧下降(3.18％～15.65％)。说明玉米地剖面 DOC主要来源于土壤腐殖类物质的转化。与林-农生态系统转变过程中的变化趋势相反，洼地农业土壤退耕弃荒一段时间(林-农-林生态系统转化)后，土壤剖面内C4-C占SOC的比例随土壤层次的加深逐渐增加，变化范围在5.77～26.76％。 (8) 在C3植被转向C4植被(林-农生态系统转化)后，玉米地δ13CSOC值与C4-C、C3-C相关系数(r)分别为0.372和-0.102，δ13CDOC值与C4-C、C3-C相关系数分别为0.131和-0.339，其相关性均未达到显著水平。而再从C4植被转回C3植被后，土壤δ13CSOC与C3-C之间呈显著相关性（r=0.88，n＝7），说明退耕弃荒后新加入的C3-C对土壤δ13CSOC值影响较大。其SOC的主要来源于洼地周边坡面土壤的侵蚀堆积物和新生草本植被残体。结合当前SOC降解过程的研究成果，本研究认为：洼地土壤退耕弃荒后一段时间里，土壤SOC可能处于累积大于损失状态。这有利于土壤性状向良性方向发展。 (9) 根据同位素值的相互关系和有机碳的来源调查，判断公路绿化带土壤中C4-C为原始土壤所带来。大气颗粒物和雨水中的DOC是表层土壤DOC的主要来源。公路绿化带土壤剖面中，随着时间的增加，土壤腐殖类物质与DOC的相互转化逐渐加强。 上述结论可为人类认识城市区域(特别是有强烈酸性沉降历史的喀斯特城市区域)土地利用方式改变对土壤碳循环的影响，以及不同土地利用方式间土壤有机碳迁移转化过程提供科学依据，也可为正确评估城市区域土壤与其他圈层间碳循环的源、汇关系提供基础资料。

蒙古北部Gun Nuur湖泊沉积物的地球化学特征及其古环境意义

了解过去是认识现在和预测未来的基础。全新世是距离现今最近的时代，对全新世环境变化的研究是探究人类与环境相互关系的主要内容。蒙古高原位于气候敏感区域，是全球能量传输的重要通道，同时受到3个气候子系统的共同影响（冬季风、夏季风、西风带），决定了此地区高分辨的记录将可为全新世全球气候变化提供重要的区域证据。但是受研究条件所限，目前蒙古高原的研究多限于在其南部的中国境内，很少涉及蒙古国内的古环境研究。 鉴于此，本文选取蒙古北部Gun Nuur湖泊沉积为研究对象，系统探讨了该湖芯沉积物中碳酸盐含量、碳酸盐碳、氧同位素、有机质含量、有机质碳同位素等地球化学指标在高分辨率气候变化重建中的重要应用价值，得出主要结论和认识如下： 1. Gun Nuur湖心沉积物中碳酸盐含量主要受夏季温度的影响，温度升高，碳酸钙和CO2的水中溶解度减小，进而碳酸盐更容易沉淀。 2. Gun Nuur碳酸盐氧同位素与反映湖区降水/蒸发比的湖泊水位有较明确的关系，即降水/蒸发比降低，水位下降，碳酸盐氧同位素值上升。 3. 温度以及由温度引起的蒸发速率的变化，和生物过程共同影响着湖泊碳酸盐碳同位素的组成，使得Gun Nuur湖心碳酸盐δ13C值气候信息不够敏感。 4. Gun Nuur沉积物有机质δ13C含量主要反映湖泊古生产力的变化，湖泊生产力高时，δ13C值偏正，湖泊生产力低时，δ13C偏负。 5. 由于Gun Nuur湖心沉积物有机质含量反映了历史时期该地区冬季的温度和冬季持续时间的长短，所以这可以作为东亚冬季风的一个良好的指标，并据此重建了过去8000年以来东亚冬季风的变化。