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.

攀西地区红格、新街岩体的岩石地球化学特征

The mafic-ultramafic layered intrusions in the Panxi, China contain large V-Ti-magnetite deposits. These layered intrusions are related with the Emeishan continental flood basalts in space and time. Two layered intrusions, Hongge and Xinjie have clear PGE mineralization at the base of the intrusions. Thus the detailed investigations of these two intrusions not only have a geological but also have an economic significance. This thesis aims to characterize the elemental and Sr-Nd isotopic features of diverse rock zones within the intrusion on the basis of systematic studies of the major, trace element and isotope ratios, therefore to constrain the petrogenesis, mantle source and evolution of the Hongge and Xinjie intrusions. Generally, both Hongge and Xinjie intrusions show the same Fe-Ti-rich and Si-M-poor characteristics. They are also enriched in rare-earth elements (REE) and large-ion lithophile elements (LILE) as well as in Sr-Nd isotope ratios (Hongge: initial Sr = 0.7056-0.7076, ε_(Nd)(t) and (Nd/Sm)_N-ε_(Nd)(t) plots, the Hongge intrusion has a similar elemental and isotopic features to the Emeishan low-Ti (LT) basalts, whereas the Xinjie intrusion was close to the Emeishan high-Ti (HT) basalt. Therefore, the Hongge intrusion may be co-genetic with the LT basalt, formed by the partial melting of the spinel-garnet transition mantle that had a slight enriched isotope character. In contrast, the Xinjie intrusion and the HT basalts are probably derived from the garnet-phases mantle with a primitive isotope character. The involvement of the components of mantle wedge into the source is considered to be the major reason of the REE and LILE enrichment and Nd isotope depletion in the Xinjie intrusion. In contrast with the systematic variations in TiO_2 content, Mg#, transition elements (Ni, Cu, Co), REE concentrations, and La/Yb, La/Sm ratios from the lower zone to upper zone, the different rock zones of the Hongge intrusion have no clear Sr-Nd isotope variations. This suggests that the Hongge intrusions were formed by the crystal fractionation from the same magma source. The rhythm may be formed by slow injection of the co-genetic magma during the crystal fractionation. The increase in K_2O and Al_2O_3 contents, REE abundance, and the degree of the REE fractionation in the base of the intrusion, together with the relatively low ε_(Nd)(t) value, may imply that the base of the Hongge intrusion was contaminated with the local crust rocks. Xinjie intrusion shows the clearly elemental and isotopic differences in diverse cumulus cycles. The observation of the systematic variations in TiO_2 content, Mg# value, transition elements (Ni, Cu, Co), REE concentrations, and La/Yb, La/Sm ratios in first cycle was not occurred in second cumulus cycle. In addition, the ε_(Nd)(t) value in second cumulus cycle is apparently higher than that of the first one. Thus the abruptly elemental and isotopic changes at the base of second cycle demonstrate that there is considerable new and depleted magma addition to the residue magma after the crystallization of the first cycle. These features are very similar to those of the well-known PGE-rich Bushveld and Stillwater layered intrusions. The PGE mineralization in Xinjie intrusion is much better than in Hongge intrusion. Therefore, the layered intrusion similar to the Xinjie in Panxi area posses the better prospects for the PGE deposits.

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.

东天山地区金矿床成矿流体地球化学及其成矿机制

The mechanism of gold ore formation in the eastern Tianshan Mountains, Xinjiang Uygur Autonomous Region, that has been dealt with from various aspects, remains unclear. On the basis of investigations of regional geology, ore deposit geology, and microscopic observations of ores and related rocks of the Jinwozi, the 210, and the Mazhuangshan gold ore deposits, this thesis made a systematic research on the microthermometry of gangue quartz-hosted fluid inclusions, gas, liquid ion and rare earth element compositions and hydrogen, oxygen isotope compositions of sulfide- and quartz-hosted fluid inclusions, and sulfur and lead isotope compositions of sulfide ore minerals from the major ores in the three deposits. On the basis of the above synthetic studies, sources of ore-forming fluids and metals, and mechanism of gold ore formation in the region were discussed. Gas compositions of pyrite- and sphalerite-hosted fluid inclusions were first analyzed in this thesis. Compared with gangue quartz-hosted fluid inclusions, the sulfide-hosted ones are richer in gaseous species CO2, CO, and CH4 etc. Both gas and liquid CO2 are commonly observed in fluid inclusions, whereas halite daughter minerals rarely occur. Ore-forming fluids for the three gold ore deposits are characteristically of medium to low temperatures, medium to low salinities, are rich in CO2 and Na+, K+, Cl" ions. Gas covariation diagrams exhibit linear trends that are interpreted as reflecting mixing between the magamtic fluid and meteoric-derived groundwater. Regarding rare earth element compositions, the Jinwozi and the 210 deposits show moderate to strong LREE/HREE fractionations with negative Eu anomalies. However, the Mazhuangshan deposit shows little LREE/HREE fractionation with positive Eu anomalies. Hydrogen and oxygen isotope compositions of pyrite-hosted fluid inclusions that were first analyzed in this thesis indicate the presence of magmatic water. Hydrogen and oxygen isotope compositions of pyrite- and quartz-hosted fluid inclusions suggest mixing between magmatic water and meteoric-derived groundwater. Sulfur and lead isotope compositions of sulfide ore minerals indicate multi-sources for the metallogenetic materials that range from the crust to the mantle. On the basis of the above synthetic studies, genesis of the gold ore deposits in the eastern Tianshan Mountains was approached. From the Middle-Late Hercynian to Early Indosinian, geodynamic regime of the region was changing from the collisional compression to the post-collisional extension. During the period, magmas were derived from the crust and the mantle and carried metallogenetic materials. Magma intrusion in the upper crust released the magmatic fluids, and drove circulation of groundwater. Mixing of magmatic fluid with groundwater, and extraction of metallogenetic materials from the country rocks are the mechanism for the gold ore formation in the eastern Tianshan Mountains.

青藏高原壳幔形变与层圈耦合数值模拟

Based on multi-principle (such as structures, tectonics and kinematics) exploratory data and related results of continental dynamics in the Tibetan plateau, the author reconstructed the geological-geophysical model of lithospherical structure and tectonic deformation, and the kinetics boundary conditions for the model. Then, the author used the numerical scheme of Fast Lagrangian Analysis of Continua (FLAC), to stimulate the possible process of the stress field and deformational field in the Tibetan plateau and its adjacent area, since the convergence-collision between the Indian continent and Eurasia continent about 50Ma ago. With the above-mentioned results, the author discussed the relationship between crustal movement in shallow layer and the deformational process in interior layers, and its possible dynamic constraints in deep. At the end of the paper, an integrative model has been put forward to explain the outline images of crust-mantle deformation and coupling in the Tibetan Plateau. (1) The characteristics of crust-mantle structure of the Tibetan plateau have been shown to be very complex, and vertical and horizontal difference is significant. The general characteristics of crust-mantle of the Tibetan plateau may be that it's layering in depth direction, and shows blocking from south to north and belting from east to west, mainly according to the results of about 20 seismic sections, such as wide-angle seismic profiles, CMP, seismic tomography and so on. (2) The crust had shortened about 2200km, while the shortening is different for different block from south to north in the Tibetan plateau. It is about 11.5mm/a in Himalayan block, about 9.0mm/a in Lhas-Gangdese block, about 7.0mm/a in Qiangtang block and Songpan-Ganzi-Kekexili block, about 8.0mm/a in Kunlun-Qaidam, and about ll.Omm/a in Qilian block, since the convergence-collision between the Indian continent and Eurasia continent about 50Ma ago. Which - in demonstrates the shortening rate decreases from south to north, but this rate increases near the north edge of the Tibetan plateau. The crust thickening rate is about 0.4mm/a in the whole Tibetan plateau; and this rate is about 0.5mm/a in Himalayan block, about 0.4mm/a in Lhas-Gangdese block, about 0.3mm/a in Qiangtang block, about 0.2mm/a in Songpan-Ganzi-Kekexili block and about O.lmm/a in Kunlun-Qaidam-Qilian block, since the convergence-collision between the Indian continent and Eurasia continent about 50Ma ago. This implies that the thickening rate decreases in the blocks of the Tibetan plateau. From south to north, the displacement of eastern boundary in the Tibetan plateau is about 37mm/a in Himalayan block, about 45mm/a in Lhas-Gangdese block, about 47mm/a in Qiangtang block, about 43mm/a in Songpan-Ganzi-Kekexili block, and about 35mm/a in Kunlun-Qaidam-Qilian block, since the collision-matching between the Indian continent and Eurasia continent had happened about 50Ma ago. This implies that the rate of eastward displacement is biggest in the middle of plateau, and decreases to both sides. The transition of S-N compression stress field in Tibetan Plateau, since about 28Ma+ ago, may be caused by two reasons: On one hand, the movement direction of Eurasia continent changed from northward to southward about 28Ma± ago in the northern plateau. On the other hand, the front belt that is located between India continent's and Eurasia continent's convergence-collision, had moved southward to high Himalayan from Indus-Brahmaputra suture almost at the same time in southern plateau. Affected by the stress field, the earlier tectonics rotated clockwise, NE and NW conjugate strike-slip faults developed, and the SN rift formed. This indicated that the EW movement started. The ratio between upper crust and lower crust of different blocks from south to north in the Tibetan plateau during the process of deformation are as following: about 3.5~5:1 in Himalayan block, about 1~5: 3-4 (which is about 1:3o--4 in south and about 4~5:3 in north) in Lhas-Gangdese block, about 1:3~447mm/a in these blocks: Which is located to the north of Banggong-nujiang suture.

富硫流体的成因与硫酸盐还原作用研究

Origins of H_2S, thiols, thiophenes in natural gases and sulphur-enriched oils are complicated and thus some debates exist on them. The post-doctoral research is based upon oil- and gas-field data. Cases for study include Triassic Jianglingjiang Formation natural gases, Wolonghe Field, Sichuan Basin, Paleozoic oils and bitumen, Central Tarim, gases reserviored nearby Carboniferious - Ordovician unconformity, Hetianhe Field, Tarim Basin and sulphur-enriched oils in Tertiary reserviors in Jinxian Sag, Bohai Bay Basin. We have carried out analyses on the oils and gases for chemistry, δ~(13)C, δ~(34)S, and molecular composition of biomarkers, analyzed authigenetic pyrite forδ~(34)S, formation water for chemistry and δD and δ~(18)O along with petroleum system and burial history analyses, The aims are to assess the origins of the H2S and authigenetic pyrite, to discuss the possibility of reduced sulphur incorporation into hydrocarbons and to determine the mechanisms of hydrocarbon secondary alteration in the above four cases by comparison. The research shows that the reduced sulphur in the four cases is the result of thermochemical and biological sulphate reduction., TSR and BSR, respectively. No evidence indicates an origin of decomposition of organic matter or mantle - derived H2S in the cases. Elevated H_2S contents (up to 32%) in the Triassic Jialingjiang Formation are considered to result from TSR while relatively low H_2S (up to 2000ppm) in the Hetianhe Field resulted from BSR. However, it is not the case for the Central Tarim where relatively low H2S but abundant authigenetic pyrite occurr. Part of the H_2S in the Central Tarim reservoirs has reacted with iron released from clay minerals to precipitate pyrite. Thus, reduced sulphur δ~(34)S and reservoir temperatures rather than the H2S amount are reliable parameters to distinguish between TSR and BSR. TSR in Sichuan Basin Triassic Jialingjiang Formation and Central Tarim Paleozoic reservoirs are showed to take place at more than 125℃. the H2S and authigenetic pyrite have δ~(34)S close to parent anhydrite. In contrast, BSR in the reservoirs near the Carboniferous - Ordovician unconformity in the Hetianhe Field and in the Tertiary in the Jinxian Sag took place at temperatures less than 80℃with sulphide δ~(34)S as light as -24.9‰ and -12.5‰, anhydrite δ~(34)S as heavy as +26‰and +3 5-+40‰, respectively. Chemistry and isotopic composition of the natural gases change as the result of sulphate reduction. It has been observed that relative composition of light hydrocarbon gases is changed along with a rise in H_2S and CO_2. TSR in the Triassic Jialingjiang Formation and BSR in the Hetianhe Field result in a greater degree of preferential depletion of methane than larger molecular hydrocarbon gases. As TSR or BSR proceeds, hydrocarbon gases evolved to heavier carbon isotope as the result of kinetic isotopic fractionation, i.e., selective anaerobic oxidation of ~(12)C. Using the model of residual methane (Whiticar, 1999) to describe the relationship among the proportion of methane oxidation, isotopic shift and fraction factor, about 30% methane is calculated to have been oxidized during BSR in the western part of the Hetianhe Field. From the above, it can be concluded that in the area where H_2S is abundant, empiricalδ~(13)C -Ro relationships do not work. Sulphate reduction results in a rise in sulphur content, gravity and viscosity of an oil as well as changes in δ~(13)C and δ~(34)S. On special conditions, the reduced sulphur from sulphates might be incorporated into oils, i.e., the increasing sulphur is derived from secondarily reduced sulphur. A positive correlative relationship exists between sulphur content and δ~(34)S in the oils in Paleozoic reservoirs in Central Tarim, indicating that enhanced sulphur is ~(34)S-enriched, originated from TSR. The Jinxian oil with the highest sulphur content has the lightest δ~(34)S, suggesting part of the sulphur in the oil is ~(34)S-depleted, originated from BSR. In the Jinxian oil with increasing sulphur content, asphaltenes shows higher content and more negative δ~(13)C, and saturates shows evidence of biodegradetion and a decreasing content and a positive δ~(13)C shift. Thus, asphaltenes have δ~(13)C values closer to saturates. All the above indicate that the reduced sulphur has been incorporated into biodegradated saturates to generate new asphaltenes with relatively light δ~(13)C of saturates. Thiols and thiophenes in natural gases in the Triassic Jialingjiang Formation may result from reaction of H_2S with hydrocarbon. In the Jialingjiang Formation hydrocarbon gases are dominated by methane thus have a high dryness coefficient and thiols are showed to be positively related to H_2S content, suggesting that the thiols may result from H_2S reaction with short chain hydrocarbons. In contrast, high thiophenes occur in wet gases in Jurassic reservoirs with their source rock from sulphur - depleted type I kerogen, indicating that thiophenes may be a product of reaction of H2S with longer chain hydrocarbons.

大别山硬玉石英岩带中的水

The Dabie Mountains is a collisional orogenic belt between the North China and Yantze Continental plates. It is the eastern elongation of the Tongbai and Qingling orogen, and is truncated at its east end by the Tan-Lu fault. Jadeite-quartzite belt occurs in the eastern margin of UHPMB from the Dabie Mountains. Geochemical features indicate that the protoliths of the jadeite-quartzite and associated eclogite to be supracrustal rocks. The occurrence of micro-inclusions of coesite in jadeite and garnet confirmed that the continental crust can be subducted to great depth (8 0-100km) and then exhumed rapidly with its UHP mineral signature fairly preserved. Therefore, study of UHP jadeite-quartzite provides important information on subduction of continental crustal rocks and their exhumation histories, as well as the dynamics of plate tectonic processes at convergent margins. The purpose of this paper is to investigate the presence of hydrous component in the jadeite-quartzite belt, significant natural variations in the hydrous component content of UHP minerals and to discuss the role of water in petrology, geochemistry and micro-tectonic. On the basis of our previous studies, some new geological evidences have been found in the jadeite-quartzite belt by researches on petrography, mineralogy, micro-tectonic, hydrous component content of UHP minerals and combined with the study on rheology of materials using microprob, ER, TEM. By research and analysis of these phenomenona, the results obtained are as follows: 1. The existence of fluid during ultra-high pressure metamorphic process. Jadeites, omphacite, garnet, rutile, coesite and quartz from the jadeite-quartzite belt have been investigated by Fourier transform infrared spectrometer and TEM. Results show that all of these minerals contain trace amount of water which occur as hydroxyl and free-water in these minerals. The two-type hydrous components in UHP minerals are indicated stable in the mantle-depth. The results demonstrated that these ultra-high pressure metamorphic minerals, which were derived from continental crust protoliths, they could bring water into the mantle depth during the ultra-high pressure metamorphism. The clusters of water molecules within garnet are very important evidence of the existence of fluid during ultra-high pressure metamorphic process. It indicated that the metamorphic system was not "dry"during the ultra-high pressure stage. 2.The distribution of hydrous component in UHP minerals of jadeite-quartzite. The systematic distribution of hydrous components in UHP minerals are a strong indication that water in these minerals, are controlled by some factors and that the observed variations are not of a random nature. The distribution and concentration of hydrous component is not only correlated with composition of minerals, but also a function of geological environment. Therefore, the hydrous component in the minerals can not only take important part in the UHP metamorphic fluid during subduction of continental crustal rocks, but also their hydroxyl transported water molecules with decreasing pressure during their exhumation. And these water molecules can not only promote the deformation of jadeite through hydrolytic weakening, but also may be the part of the retrograde metamorphic fluid. 3.The role of water in the deformed UHP minerals. The jadeite, omphacite, garnet are strong elongated deformation in the jadeite-quartzite from the Dabie Mountains. They are (1) they are developed strong plastic deformation; (2) developed dislocation loop, dislocation wall; (3) the existence of clusters of water molecular in the garnet; and (4) the evolution of micero-tectonic from clusters of water molecular-dislocation loop in omphacite. That indicated that the water weakening controlled the mechanism of deformed minerals. Because the data presented here are not only the existence of clusters of water molecular in the garnet, but also developed strong elongation, high density of dislocation and high aspect ratios, adding microprobe data demonstrate the studied garnet crystals no compositional zoning. Therefore, this indicates that the diffusion process of the grain boundary mobility did not take place in these garnets. On the basis of above features, we consider that it can only be explained by plastic deformation of the garnets. The clusters of water molecules present in garnet was directly associated with mechanical weakening and inducing in plastic deformation of garnet by glissile dislocations. Investigate of LPO, strain analysis, TEM indicated that these clinopyroxenes developed strong elongation, high aspect ratios, and developed dislocation loop, dislocation wall and free dislocations. These indicated that the deformation mechanism of the clinopyroxenes plastically from the Dabie Mountains is dominant dislocation creep under the condition of the UHP metamorphic conditions. There are some bubbles with dislocation loops attached to them in the omphacite crystal. The bubbles attached to the dislocation loops sometimes form a string of bubble beads and some loops are often connected to one another via a common bubble. The water present in omphacite was directly associated with hydrolitic weakening and inducing in plastic deformation of omphacite by dislocations. The role of water in brittle deformation. Using microscopy, deformation has been identified as plastic deformation and brittle deformation in UHP minerals from the Dabie Mountains. The study of micro-tectonic on these minerals shows that the brittle deformation within UHP minerals was related to local stresses. The brittle deformation is interpreted as being caused by an interaction of high fluid pressure, volume changes. The hydroxyl within UHP minerals transported water molecules with decreasing pressure due to their exhumation. However, under eclogite facies conditions, the litho-static pressure is extreme, but a high fluid pressure will reduce the effective stress and make brittle deformation possible. The role of water in prograde metamorphism. Geochemical research on jadeite-quartzite and associated eclogite show that the protoliths of these rocks are supracrustal rocks. With increasing of temperature and pressure, the chlorite, biotite, muscovite was dehydrous reaction and released hydrous component during the subduction of continental lithosphere. The supracrustal rocks were transformed UHP rocks and formed UHP facies assemblage promotely by water introduction, and was retained in UHP minerals as hydrous component. The water within UHP minerals may be one of the retrograde metamorphic fluids. Petrological research on UHP rocks of jadeite-quartzite belt shows that there was existence of local fluids during early retrograde metamorphism. That are: (1) coronal textures and symplectite around relict UHP minerls crystals formed from UHP minerls by hydration reactions; (2) coronal textures of albite around ruitle; and (3) micro-fractures in jadeite or garnet were filled symplectite of Amp + PI + Mt. That indicated that the reactions of early retrograde metamorphism dependent on fluid introduction. These fluids not only promoted retrograde reaction of UHP minerals, but also were facilitate to diffuse intergranular and promote growth in minerals. Therefore, the hydrous component in the UHP minerals can not only take important part in the UHP metamorphic fluid during subduction of continental crustal rocks, but also their hydroxyl transport water molecules with decreasing pressure and may take part in the retrograde metamorphic fluid during their exhumation. 7. The role of water in geochemistry of UHP jadeite-quartzite. Geochemical research show that there are major, trace and rare earth element geochemical variations in the jadeite-quartzite from the Changpu district of Dabie Mountains, during retrograde metamorphic processes from the jadeite-quartzite--gneiss. The elements such as SiO_2、FeO、Ba、Zr、Ga、La、Ce、PTN Nd% Sm and Eu increase gradually from the jadeite-quartzite to retrograded jadeite-quartzite and to gneiss, whilst TiO_2. Na_2CK Fe2O_3、Rb、Y、Nb、Gd、Tb、Dy、Ho、Er、Tm、Yb decrease gradually. And its fO_2 keep nearly unchanged during early retrograde metamorphism, but decreased obviously during later retrograde metamorphism. These indicate that such changes are not only controlled by element transformation between mineralogical phases, but also closely relative to fluid-rock interaction in the decompression retrograde metamorphic processes.

内蒙古黄岗矿集区与锡矿化有关的花岗岩成因研究

Muanggang-Dajing area located in the south end of Dahinggan Mts is the only discovered tin-polymetallic minerzalization belt and the only tectonic magmaism zone with middle-upper grade tin-ore deposites in North China. Tin mineralization in this area is believed tn related to Yanshannian granites which is different from those in South China tin belt. Through geochemical study of these granites on the base of fieldworks , thin section observation, major and trace elements as well as isotopic composision determination, the isochronic sequence and petrogenetic series for the granites have been determined. Hi light ing on the petrogenesis of earlier Yanshannian of MOmarh granites, two groups granites with different Neodymium isotopic features have been distinguished. Both belonging to hi-K calc-alkalinic series, their nature of source rocks and.magma processing were restricted, we argue for that the two groups have get the isotopic differences from their sources-middle and later proterozoic juvenial crustal via mantle underplating. From then on , there is a pre-enrichment of tin in this area. The partial melting from a F rich soruses can dissolve and carry more tin from the same some due to the de-connection of melt, which supply the mineralization fluids after a thoroughly evolement.

山东莱州金城金矿床构造-流体成矿特征

This paper studied the metallotectonics, altered rocks, altered minerals and fluid inclusions. The conclusions are: (1)The gold deposits in Jiaodong district were formed quickly uplifted tectonic setting which was induced by the Mantle doming in Mesozoic era. (2)Both Jiaojia-type and Linglong-type gold mineralizations were formed in the same tectonic-fluid system. (3) The Ar-Ar age of the earlier stage of the gold mineralization is 114～116Ma. (4)The development of the plaiting ore-control tectonic system underwent four stagesrcounterclockwise ductile compresso-shearing, clockwise brittle tenso-shearing and counterclockwise brittle compresso-shearing and brittle normal faulting after mineralization. (5)The mineralization has five stages: quartz and k-feldspar stage, quartz and ferro-carbonate and pyrite stage, quartz and chalcopyrite stage, pyrite and sericite and quartz stage and carbonate stage, and they make up four ore-types: red ore, vein ore, mottled ore and grey ore. (6) The features of mineralizations and ore-forming fluids in different stages are different. But the ore-forming fluids are rich in Si, Fe, P_2O_5, H_2O, CO_2, SO_4~(2-), K~+, Na~+, Ca~(2+) and Cl~- in general and their salinities are from 4 to 18 NaClwt%. (7) The ore-forming fluids came mainly from the Mantle in early stage, then mainly from magma, and mainly from meteoric water in the last stage. (8) Au in the ore-forming fluid was mainly carried in the form of complex of Au and S. (9)The temperature of ore-forming fluid is from 350℃ to 120℃and its pressure is from 20MPa to 38MPa. (10)The gold vein composed by quartz, ferro-carbonate, chalcopyrite and pyrite (vein ore) was filled in the tensional fracture in the top of the magma dome. The disseminated ore bodies composed by pyrite, sericite and quartz (grey ore) was metasomatized in the shearing fault which developed along the contact zone between Linglong intrusive body and Jiaodong Group, which is placed in the flank top of magma dome. In the joint and fracture induced by the shearing fault which developed along the contact zone between Linglong intrusive body and Jiaodong Group, veiniet and stockwork ore (red ore) and veinlet-disseminated ore (mottled ore) composed by quartz and pyrite was formed. (ll)Fluid boiling maybe one of the form of the ore-forming substances precipitation.

河北寿王坟铜矿成矿定年及同位素地球化学特征

Samples from carbonate wall-rocks, skarn, ore of skarn type, later calcite vein, and ore of porphyry type in Shouwangfen copper deposit district were collected. Systematic study was carried out on carbon, oxygen, rubidium, strontium and sulfur isotope compositions of carbonates and sulfides in these samples. The first Isochron dating by the Rb-Sr isotopes in chalcopyrite of ore sub-sample was done as well. The following conclusions were obtained. The age (113.6±4.3Ma), obtained by Rb-Sr isotope isochron dating of chalcopyrite and pyrite from sub-sample of skarn ores, probably represents the true mineralization age of skarn ores. That demonstrates the genetic relationship between granodiorite in Shouwangfen complex and skarn copper ores. On the other hand, the Rb-Sr isochron age (73±15Ma) of chalcopyrite from porphyry ores is a little incredible because of bad synthesizing evaluation. But combined with other age data of igneous rocks, it implies the possibility of hydrothermal mineralization in connection with magma activity during the fourth period of Yanshanian in Hebei Province, even in the whole northern edge of Huabei continental block. Together from structure analysis of sulfide sub-samples, from pretreating preccedure of Rb-Sr isotope isochron and its' valuating, we found out that Rb-Sr isotope isochron of sulfide sub-samples is influenced by the crystal structure of sulfides. That is, sulfide ores with very big crystals are not suitable for sub-sample isochron. Carbon, oxygen, sulfur and strontium compositions, of different minerals in these two kinds of ores, imply that the ore-forming hydrothermal fluids were probably derived from magma deep under the crust. The calcite ~(87)Sr/~(86)Sr ratios from the porphyry are consistent to the initial 87Sr/86Sr ratio of the Rb-Sr isochron of chalcopyrite and pyrite in the skarn ore, indicating that these two kinds of ores have the same source characteristic, although the porphyry deposit was formed probably 40 million years later than the skarn one according to our dating results. Skarn and skarn ores are usually considered as interaction product between carbonate wall-rocks and magmatic fluids, but the carbon of the sedimentary carbonate seems not involved in the skarn ores. Considering the connection of magmatic processes and hydrothermal ore formation in the Shouwangfen district, particularly, the spatial distribution of skarn-type and porphyry-type ores, it is possible that the Shouwangfen ore district corresponds to a hydrothermal ore-forming system, which was promoted by high-intruding magmatic rocks. Systematic stable isotopic research can help to reveal the upper part of this hydrothermal ore-forming system, which mainly related to heated and circulating meteoric water, and the lower part principally related to ascending magmatic fluids. Both skarn and porphyry ore-bodies are formed by up-intruding magmatic fluids (even more deep mantle-derived fluids).

接收函数方法与中国及邻区上地幔间断面的研究

The receiver function method applied in researching the discontinuities in upper mantle was systematically studied in this paper. Using the theoretical receiver functions, the characteristics of P410S and P660S phases were analyzed, and the influencing factors for detection of these phases were discussed. The stability of receiver function was studied, and a new computational method of receiver function, RFSSMS (Receiver Function of Stack and Smooth of Multi seismic-records at a Single station), was put forward. We built initial reference velocity model for the media beneath each of 18 seismic stations respectively; then estimated the buried depths of 410-km and 660-km discontinuities(simply marked as '410' and '660') under the stations by using the arrive time differences of P410S and P660S with P. We developed a new receiver function inversion method -PGARFI (Peeling-Genetic Algorithm of Receiver Function Inversion), to obtain the whole crust and upper mantle velocity structure and the depths of discontinuities beneath a station. The major works and results could be summarized as follows: (1) By analysis of the theoretical receiver functions with different velocity models and different ray parameters, we obtain the knowledge: The amplitudes of P410S and P660S phases are decreasing with the increasing of epicentral distance A , and the arrival time differences of these phases with P are shorter as A is longer. The multiple refracted and/or reflected waves yielded on Moho and the discontinuities in the crust interfere the identification of P410S. If existing LVZ under the lithosphere, some multiple waves caused by LVZ will interfere the identification of P410S. The multiple waves produced by discontinuity lied near 120km depth will mix with P410s phase in some range of epicentral distance; and the multiple waves concerned with the discontinuity lied near 210km depth will interfere the identification of P660S. The epicentral distance for P4i0s identification is limited, the upper limit is 80° . The identification of P660S is not restricted by the epicenter distance obviously. The identification of P410S and P6gos in the theoretical receiver functions is interfered weakly from the seismic wave attenuation caused by the media absorption if the Q value in a reasonable range. (2) The stability of receiver function was studied by using synthetic seismograms with different kind of noise. The results show that on the condition of high signal-noise-ratio of seismic records, the high frequency background noise and the low frequency microseism noise do not influence the calculating result of receiver function. But the media "scattering noise" influence the stability of receiver function. When the scattering effect reach some level, the identification of P4iOs and P66os is difficult in single receiver function which is yielded from only one seismic record. We provided a new method to calculate receiver function, that is, with a group of earthquake records, stacking the R and Z components respectively in the frequency domain, and weighted smooth the stacked Z component, then compute the complex spectrum ratio of R to Z. This method can improve the stability of receiver function and protrude the P4i0s and P66os in the receiver function curves. (3) 263 receiver functions were provided from 1364 three component broadband seismograms recorded at 18 stations in China and adjacent areas for the tele-earthquakes. The observed arrival time differences of P410S and P660S with P were obtained in these receiver functions. The initial velocity model for every station was built according to the prior research results. The buried depths of '410' and '660' under a station were acquired by the way of adjusting the depths of these two discontinuities in the initial velocity model until the theoretical arrival time differences of P410S and P660S with P well conformed to the observed. The results show an obvious lateral heterogeneity of buried depths of ' 410' and (660' . The depth of '410' is shallower beneath BJI, XAN, LZH and ENH, but deeper under QIZ and CHTO, and the average is 403km . The average depth of '660' is 663km, deeper under MDJ and MAJO, but shallower under QIZ and HYB. (4) For inversing the whole crust and upper mantle velocity structure, a new inversion method -PGARFI (Peeling-Genetic Algorithm of Receiver Function Inversion) has- been developed here. The media beneath a station is divided into segments, then the velocity structure is inversed from receiver function from surface to deep successively. Using PGARFI, the multi reflection / refraction phases of shallower discontinuities are isolated from the first order refraction transform phase of deep discontinuity. The genetic algorithm with floating-point coding was used hi the inversion of every segment, and arithmetical crossover and non-uniform mutation technologies were employed in the genetic optimization. 10 independent inversions are completed for every segment, and 50 most excellent velocity models are selected according to the priority of fitness from all models produced in the inversion process. The final velocity structure of every segment is obtained from the weighted average of these 50 models. Before inversion, a wide range of velocity variation with depth and depth range of the main discontinuities are given according to priori knowledge. PGARFI was verified with numerical test and applied in the inversion of the velocity structure beneath HIA station down to 700km depth.

鲁西临朐地区中生代铁寨杂岩体的岩石化学与地球化学特征及其成因研究

The Tiezhai intrusive complex is located in the north of the Luxi block, Shandong province, eastern China. It lies ～30 km west of the Tanlu fault, and is at the cross of the Wujing and Jiushan faults. The Tiezhai complex was formed about 120～130 Ma, when large-scale magmatism was active in eastern part of North China. This paper carries out petrochemical and geochemical study on the Tiezhai intrusive complex, and discusses its genesis in detail. The Tiezhai intrusive complex can be subdivided into three rock series. The first is the gabbro-diorite series formed in early stage. Its composition variation shows 01 and Cpx fractional crystallization trend. The second is the porphyritic diorite and monzonite series, showing dominating Hb fractional differentiation. Their composition variation shows Hb fractional crystallization trend. The third is the porphyritic quartz monzonite with K-feldspar megacrysts, showing weakly Hb and Bi fractional crystallization trend. All types of rocks in the Tiezhai complex are belonging to the high-K cac-alkaline series. They have elevated Sr (450-1660 ppm), Ba (210-1780 ppm) and relatively low Rb (30-100 ppm). For the gabbro-dioritic rocks in the early stage, the abundances of Ni (20-250 ppm), Cr (50-350 ppm), V(l30-250 ppm) and Co (20-40 ppm) are high, indicating a mantle origin. All rocks have negative anormalies of Nb, Ta, Ti and P, and enriched LREE and strong differentiated REE patterns. The porphyritic monzonites and quartz monzonites have very low HREE, Yb and Y contents and positive Eu anormalies, similar to adakite. Most rocks have lowε_(Nd)(t) of-1.5～-10.9, and high (~(87)Sr/~(86)Sr)_i of 0.704～0.709. The data have characters of enriched lithosphere mantle (EMI). In summary, the Tiezhai intrusive complex was inferred to be generated by a mantle derived magma through fractional crystallization. When the primary magma gathered in some place between crust and mantle, the crystallization started and causing magma evolution. The remaining / evolved magma ascended and emplaced again and again in the upper crust in Tiezhai area. Then Tiezhai complex formed. The porphyritic monzonites and quartz monzonites have major and trace element characters of typical adakite, but they are likely to be generated by Hb fractional crystallization.

大兴安岭南段中生代火山-侵入杂岩带的双层叠置构造体制兼论滇中武定、易门碳酸质火山岩年代、来源及矿库与找矿研究

These are two parts included in this report. In the first part, the zonation of the complexes in its series, lithofacies, the depth of magma source and chambers is discussed in detailed for the first time based on the new data of petrol-chemistry, isotopes, tectono-magma activity of Mesozoic volcano-plutonic complexes in the southern Great Hinggan Mts. Then, the genetic model of the zonality, double overlapped layer system, is proposed. The main conclusions are presented as follows: The Mesozoic volcanic-plutonic complexes in the southern Great Hinggan were formed by four stages of magma activity on the base of the subduction system formed in late Paleozoic. The Mesozoic magmatic activity began in Meso-Jurassic Epoch, flourished in late Jurassic Epoch, and declined in early Cretaceous Epoch. The complexes consist dominantly of acidic rocks with substantial intermediate rocks and a few mefic ones include the series of calc alkaline, high potassium calc alkaline, shoshonite, and a few alkaline. Most of those rocks are characterized by high potassium. The volcano-plutonic complexes is characterized by zonality, and can be divided mainly into there zones. The west zone, located in northwestern side of gneiss zone in Great Xinggan mountains, are dominated of high potassium basalts and basaltic andesite. The middle zone lies on the southeast side of the Proterozoic gneiss zone, and its southeast margin is along Huangganliang, Wushijiazi, and Baitazi. It composed of dominatly calc-alkaline, high potassium calc-alkaline rocks, deep granite and extrusive rhyolite. The east zone, occurring along Kesheketong Qi-Balinyou Qi-Balinzuo Qi, is dominated of shoshonite. In generally, southeastward from the Proterozoic gneiss zone, the Mesozoic plutons show the zones-mica granitites zone, hornblende-mica granitite zone, mica-hornblende granitite zone; the volcanic rocks also display the zones of calc alkaline-high potassium calc alkaline and shoshonites. In the same space, the late Paleozoic plutons also display the same zonality, which zones are combined of binary granite, granodiorite, quartz diorite and diorite southeast wards from the gneiss. Meso-Jurassic Epoch granite plutons almost distribute in the middle zone on the whole. Whereas late Jurassic Epoch volcanic rocks distribute in the west and east zone. This distribution of the volcano-plutonic complexes reveals that the middle zone was uplifted more intensively then the other zones in Meso-Jurassic and late Jurassic Epoches. Whole rock Rb-Sr isochron ages of the high potassium calc-alkaline volcanic rocks in the west zone, the calc-alkaline and high potassium calc-alkaline granite the middle zone, shoshonite in the east zone are 136Ma, 175Ma and 154Ma, respectively. The alkaline rocks close to the shoshonite zone is 143Ma and 126Ma. The isochron ages are comparable well with the K-Ar ages of the rocks obtained previously by other researchers. The compositions of Sr ans Nd isotopes suggest that the source of Mesozoic volcanic-plutonic complexes in Great Hinggan Mts. is mostly Paleo-Asia oceanic volcanic-sedimentary rocks, which probably was mixed by antiquated gneiss. The tectonic setting for Mesozoic magmatism was subductive continental margin. But this it was not directly formed by present west Pacific subduction. It actully was the re-working of the Paleozoic subduction system( which was formed during the Paleo-Asia ocean shortening) controlled by west Pacific subduction. For this reason, Although Great Hinggan Mts. is far away from west Pacific subduction zone, its volcanic arc still occurred echoing to the volcanic activities of east China, it, but the variation trend of potassium content in volcano-plutonic complexes of Great Hinggan is just reverse to ones of west Pacific. The primitive magmas occurred in the southern Great Hinggan Mts. Include high-potassium calc-alkaline basalt, high potassium calc-alkaline rhyolite, high potassium rhyolite, non-Eu negative anomaly trachy-rhyolite et al. Therefore, all of primitive magmas are either mafic or acid, and most of intermediate rocks occurring in the area are the products of Mesozoic acid magma contaminated by the Paleozoic volcanic- sedimentary rocks. The depth of those primitive magma sources and chambers gradually increase from northwest to southeast. This suggests that Paleozoic subduction still controlled the Mesozoic magmatism. In summary, the lithosphere tectonic system of the southern Great Hinggan Mts. controlling Mesozoic magmatism is a double overlapped layer system developing from Paleozoic subduction system. For this reason, the depth of crust of the southern Great Hinggan Mts. is thicker than that of its two sides, and consequently it causes regional negative gravity abnormity. The second part of this report shows the prolongation of the research work carried on in my doctor's period. Author presents new data about Rb-Sr and Sm-Nd isotopic compositions and ages, geochamical features, genesis mineralogy and ore deposit geology of the volcanic rocks in Kunyang rift. On the base of the substantial work, author presents a prospect of copper bearing magnetite ore deposit. The most important conclusions are as follows: 1. It is proved that all of these carbonatites controlled by a ringing structure system in Wuding-Lufeng basin in the central Yunnan were formed in the Mesoproterozoic period. Two stages could be identified as follows: in the first stage, carbonatitic volcanic rocks, such as lavas(Sm-Nd, 1685Ma), basaltic porphyrite dykes(Sm-Nd, 1645Ma), pyroclastic rocks and volcaniclastic sedimentary rocks, formed in the outer ring; in the second stage, carbonatitic breccias and dykes(Rb-Sr, 1048 Ma) did in the middle ring. The metamorphic age of the carbonatitic lavas (Rb-Sr, 893 Ma) in the outer ring was determined. The magma of carbonatitic volcanic rocks derived mainly form enriched mantle whose basement is depleted mantle that had been metasomated by mantle fluid and contaminated by Archaean lower crust. Carbonatitic spheres were discovered in ore bearing layers in Lishi copper mining in Yimen recently, which formed in calcite carbonatitic magma extrusion. This discovery indicates that the formation of copper ore deposit genesis relates to carbonatitic volcanic activity. The iron and copper ore deposits occurring in carbonatitic volcanic- sedimentary rocks in Kunyang rift results from carbonatitic magmatism. Author calls this kind of ore deposits as subaqueous carbonatitic iron-copper deposit. The magnetic anomaly area in the north of Lishi copper mining in Yimen was a depression more lower than its circumference. Iron and copper ores occurrig on the margin of the magnetic anomaly are volcanic hydrothermal deposit. The magnetic body causing the magnetic anomaly must be magnetite ore. Because the anomaly area is wide, it can be sure that there is a large insidious ore deposit embedding there.

青藏高原东部电性结构特征及地球动力学意义

As the largest and highest plateau on the Earth, the Tibetan Plateau has been a key location for understanding the processes of mountain building and plateau formation during India-Asia continent-continent collision. As the front-end of the collision, the geological structure of eastern Tibetan Plateau is very complex. It is ideal as a natural laboratory for investigating the formation and evolution of the Tibetan Plateau. Institute of Geophysics, Chinese Academy of Sciences (CAS) carried out MT survey from XiaZayii to Qingshuihe in the east part of the plateau in 1998. After error analysis and distortion analysis, the Non-linear Conjugate Gradient inversion(NLCG), Rapid Relaxation Inversin (RRI) and 2D OCCAM Inversion algorithms were used to invert the data. The three models obtained from 3 algorithms provided similar electrical structure and the NLCG model fit the observed data better than the other two models. According to the analysis of skin depth, the exploration depth of MT in Tibet is much more shallow than in stable continent. For example, the Schmucker depth at period 100s is less than 50km in Tibet, but more than 100km in Canadian Shield. There is a high conductivity layer at the depth of several kilometers beneath middle Qiangtang terrane, and almost 30 kilometers beneath northern Qiangtang terrane. The sensitivity analysis of the data predicates that the depth and resistivity of the crustal high conductivity layer are reliable. The MT results provide a high conductivity layer at 20~40km depth, where the seismic data show a low velocity zone. The experiments show that the rock will dehydrate and partially melt in the relative temperature and pressure. Fluids originated from dehydration and partial melting will seriously change rheological characteristics of rock. Therefore, This layer with low velocity and high conductivity layer in the crust is a weak layer. There is a low velocity path at the depth of 90-110 km beneath southeastern Tibetan Plateau and adjacent areas from seismology results. The analysis on the temperature and rheological property of the lithosphere show that the low velocity path is also weak. GPS measurements and the numerical simulation of the crust-mantle deformation show that the movement rate is different for different terranes. The regional strike derived from decomposition analysis for different frequency band and seismic anisotropy indicate that the crust and upper mantle move separately instead of as a whole. There are material flow in the eastern and southeastern Tibetan Plateau. Therefore, the faults, the crustal and upper mantle weak layers are three different boundaries for relatively movement. Those results support the "two layer wedge plates" geodynamic model on Tibetan formation and evolution.

商都盆地二氧化碳气成藏条件研究

The bedding sequences, based on the results from others, have been constructed by geological researches. Furthermore, the reservoir, gas-bearing characteristics and reservoir-blanket association have been increasingly understudied by the geological and seismic studies as well as the log data. The deep dynamics for the formation and development of Shangdu basin resulted from complicated fault system and its continued action have been obtained. The studies on the reservoir condition reveal that the mantle-derived magmatism provided the materials for the CO_2 gas reservoir after Paleogene Period and the huge regional fault not only control the evolution of basin and sedimentary but also pay a role as a passage of the CO_2. The sandstone of river course formed in Paleogene System, with very good reservoir condition, are widely developed in the study area. The blanket with good condition is composed by the basalt in Hannuoba Formation and lake facies shale of Shangdou Formation. Local structures and good encirclement are resulted from the different sedimentary environment and later differential sagging. All statements above demonstrate that there is a very good pool-forming condition for the CO_2. In addition, the high abundance of H_2 recognized during drill exploration are also of significance.More than 30 inorganic CO_2 gas reservoirs have been determined during the exploration for the oil-bearing basins in the eastern China, which are developed along the two sides of Tanlu Fault or within it. In which the CO_2 gas reservoir in Shangdou basin is an inorganic gas reservoir far away from Tanlu Fault. Thus the determination of the CO_2 gas reservoir in Shangdou basin is significant for sciences due to the first exploration for the inorganic CO_2 gas reservoir in our country. The geophysical exploration carried on the CO_2 gas reservoir is benefited for the research of prospecting techniques of CO_2 reservoir.