Lu-Hf同位素的MC-ICP-MS实验方法及其在华北克拉通典型火山岩研究中的应用

Over past ten years, a great development has been made in the Lu-Hf isotopic system with the advent of MC-ICP-MS. Based on a comprehensive review of available references in the related field, a novel analytical protocol of three exchange chromatographies after one mixed acid attacking geological samples was developed in this work, which not only avoids common multiple sample treatments for natural inhomegeneous samples, but also is useful for Rb-Sr, Sm-Nd and Lu-Hf isotopic system simultaneously, especially for the garnet- and apatite-bearing rocks for the Sm-Nd and Lu-Hf geochronology. An analytical procedure for the Lu and Hf concentration in geological samples determined by by ID-MC-ICP-MS was detailedly investigated. The Hf yield is > 90 % and total procedural blank is less than. 50 pg for Hf and 10 pg for Lu, respectively. The developed method was successfully applied to the determination of Lu and Hf concentrations for USGS geological materials. A one-column procedure for Hf purification in geological samples using common anion exchange chromatography and its isotopic analyses by MC-ICP-MS were also established. Multiple analyses of Standard Reference Materials demonstrate that this method was simple, time-saving, cheap and efficient, especially suitable for the Hf isotopic compositions of young samples. Finally, the measurements of Sr and Nd isotopic compositions using Neptune MC-ICP-MS were described briefly, which indicates that Neptune MC-ICP-MS can precisely measure Sr and Nd isotopic compositions as the TIMS does, even more efficient and less time-consuming than the TIMS method. The Hf isotopic characteristics of typical volcanic rocks (Cenozoic Changle-Linqu basalts, Mesozoic Fangcheng basalts, Mesozoic Jianguo basalts, Mesozoic Wulahada high-Mg andesite, Cenozoic Fanshi, Zuoquan and Xiyang-Pingding basalts of the Taihang Mountains, Paleozoic diamondiferous Menyin and Fuxian Kimblites) from the North China Craton were firstly studied in this work. Coupled with Nd isotopic compositions, it shows that the Hf isotopes could be a better tracer for mantle sources than the Nd isotopes. Individual kimberlite fields from both the Mengyin and Fuxian regions have quite uniform Hf isotopic compositions, similar to the situation for the Nd isotopes.

渤海湾盆地前第三系构造演化与煤成气成藏研究

The disequilibrium between supply and demand the east part of North China accelerated natural gas exploration in Bohai bay basin. Exploration practice showed that coal-derived gas is important resource. In searching of big to middle scaled coal derived gas field, and realize successive gas supply, the paper carried out integrated study on structural evolution of Pre-Tertiary and evaluation of reservoir forming condition of coal-derived gas. Study work of the paper was based on the following condition: available achievement in this field at present, good understanding of multiphase of tectonic movement. Study work was focused on geological evolution, source rock evaluation and dissection key factors controlling reservoir forming. Based on analysis of seismic data, drilling data, tectonic style of Pre-Tertiary was subdivided, with different tectonic style representing different tectonic process. By means of state of the art, such as analysis of balanced cross section, and erosion restoration, the paper reestablished tectonic history and analyzed basin property during different tectonic phase. Dynamic mechanism for tectonic movement and influence of tectonic evolution on tectonic style were discussed. Study made it clear that tectonic movement is intensive since Mesozoic including 2 phase of compressional movement (at the end of Indo-China movement, and Yanshan movement), 2 phase of extensional movement (middle Yanshan movement, and Himalayan movement), 2 phase of strike slip movement, as well as 2 phase of reversal movement (early Yanshan movement, and early Himalayan movement). As a result, three tectonic provinces with different remnant of strata and different tectonic style took shape. Based on afore mentioned study, the paper pointed out that evolution of Bohai bay basin experienced the following steps: basin of rift valley type (Pt2+3)-craton basin at passive continental margin (∈1－2)-craton basin at active continental margin (∈3- O)-convergent craton basin (C-T1+2)-intracontinental basin (J＋K). Superposition of basins in different stage was discussed. Aimed at tectonic feature of multiple phases, the paper put forward concept model of superposition of tectonic unit, and analyzed its significance on reservoir forming. On basis of the difference among 3 tectonic movements in Mesozoic and Cenozoic, superposition of tectonic unit was classified into the following 3 categories and 6 types: continuous subsidence type (I), subsidence in Mesozoic and uplift for erosion in Cenozoic (II1), repeated subsidence and uplift in Mesozoic and subsidence in Cenozoic (II2), repeated subsidence and uplift in Mesozoic and uplift for erosion in Cenozoic (II3), uplift for erosion in Mesozoic and subsidence in Cenozoic (II4), and continuous uplift (III). Take the organic facies analysis as link, the paper established relationship between sedimentary environment and organic facies, as well as organic facies and organic matter abundance. Combined information of sedimentary environment and logging data, the paper estimated distribution of organic matter abundance. Combined with simulation of secondary hydrocarbon generation, dynamic mechanism of hydrocarbon generation, and thermal history, the paper made static and dynamic evaluation of effective source rock, i.e. Taiyuan formation and Shanxi formation. It is also pointed out that superposition of tectonic unit of type II2, type II4, and type I were the most favorable hydrocarbon generation units. Based on dissection of typical primary coal-derived gas reservoir, including reservoir forming condition and reservoir forming process, the paper pointed out key factors controlling reservoir forming for Carboniferous and Permian System: a. remnant thickness and source rock property were precondition; b. secondary hydrocarbon generation during Himalayan period was key factor; c. tectonic evolution history controlling thermal evolution of source rock was main factor that determine reservoir forming; d. inherited positive structural unit was favorable accumulation direction; e. fault activity and regional caprock determined hydrocarbon accumulation horizon. In the end, the paper established reservoir forming model for different superposition of tectonic units, and pointed out promising exploration belts with 11 of the first class, 5 of the second class and 6 of the third class.

西秦岭新生代火山岩中的地幔捕虏体和捕虏晶研究

Western Qinling, a conjunction region of the North China Craton, the Yangtze Craton and the Tibetan Plateau, has very complicated history of geologic and tectonic evolution. Previous studies mainly focus on tectonics and petrology of volcanic rocks in the western Qinling. Therefore, little is known about the Cenozoic lithospheric mantle beneath the western Qinling. Mafic, ultramafic and/or alkaline volcanic rocks and their entrained mantle peridotitic xenoliths and xenocrysts are known as samples directly from the lithospheric mantle. Their petrological and geochemical characteristics can reflect the nature and deep processes of the lithospheric mantle. Cenozoic volcanic rocks in the western Qinling contain abundant mantle xenoliths and xenocrysts, which provide us an opportunity to probe the lithospheric mantle beneath this region and a new dimension to insight into geologic evolution. Cenozoic volcanic rocks (7-23 Ma) from the western Qinling are sparsely distributed in the Lixian-Dangchang-Xihe Counties, Gansu Province, China. Volcanic rocks contain plenty of mantle-derived xenoliths, including spinel lherzolites with subordinate wehrlite, dunite, olivine websterite, clinopyroxenite and garnet lherzolite, and few olivine, clinopyroxene and spinel xenocrysts. These peridotitic xenoliths show clear deformed textures and their major minerals show excellent orientation. Thus, these peridotites are typical deformed peridotites. Olivine xenocrysts have clearly-zoned textures. The peridotitic xenoliths can be divided into two groups based on their compositions, namely, the H-type and L-type. The H-type peridotites are characterized by high Fo (>90) in olivines in which fine-grained ones have higher Fo than the coarse grains, low CaO (<20 %) in clinopyroxenes, high Cr# (>40) in spinels and high equilibration temperatures. They may represent the refractory lithospheric mantle. In contrast, the L-type peridotites contain low Fo (<90) olivines (with lower Fo in fine-grained olivines), high CaO (>20 %) clinopyroxenes, low Cr# (<20) spinels and low equilibration temperatures. They experienced low degree of partial melting. The Cenozoic lithospheric mantle beneath the western Qinling was refractory in major element compositions based on the mineral compositions of xenoliths and xenocrysts and experienced complicated deep processes. The lithospheric mantle was modified by shear deformation due to the diapirism of asthenosphere and strong tectonic movements including the collision between North China Craton and Yangze Craton and the uplift of Tibetan Plateau, and then underwent metasomatism with a hydrous, Na, Ti and Cr enriched melt.

华北克拉通孔玆岩系中石榴子石花岗岩的成因：熔体与残留相混合机制的研究

The most widespread rock associations in the Western Block of North China Craton are khondalites distributed mainly in Jining, Liangcheng and Datong. A large quantitiy of garnet-bearing granites are contained in the khondalites. A great deal of research has been carried out on them by previous researchers. Studies of these garnet-bearing granites consist essentially of structural characteristics, petrography and geochemistry, and finally geochronological determinations. Summing up these researches, it will not be difficult to see that all of these authors have regarded these large numbers of garnets (up to 20%) contained in granites as crystallized products from magmas, but they have not proved this from petrological perspective. Theoretically, there are possibly three kinds of petrogenesis as to these garnets. The first one is that they have been transferred to the granites from khondalites by melt when anatexis happened to khondalites, and they, in essence, are residual metamorphic garnets; The second one is that when the khondalites were being melted, these garnets were produced from biotite dehydration melting, and the newly formed garnets intruded together with the melt and eventually molded the garnet-bearing granites. Garnets of this possible kind either showed independent crystals, or garnets from khondalites took place secondary growth under favorable temperature and pressure conditions for their crystallization; The last possibility is that these garnets were crystallized from magmas in which suitable pressure, temperature and composition were available. These garnets, generally, should be fine-grained. The aim of this study is, through examining the mineral chemistry of the garnets and the whole rock chemistry, to ascertain under which kind of mechanism, in the world, did these garnets form? Besides, we try to calculate the temperatures under which khondalites began melting and reactions of the garnets and the cooled melts happened by garnet-biotite thermometry. The whole rock chemistry analyses of the garnet-bearing granites tell us that all the samples are strongly peraluminous (A/CNK greater than 1.1) on the A/NK vs. A/CNK plot. On the SiO2-K2O plot, the granites are mainly constrained to be high-K calc-alkaline and calc-alkaline series, consistent with previous researches. On the ACF（（Al2O3-Na2O-K2O）-FeO(T)-CaO） discrimination plot, all the six garnet-bearing granite samples drop into the area of S-type granites. The relationship between CaO/Na2O and SiO2 shows that the overwhelming majority of garnet-bearing granites have a CaO/Na2O value over 0.3, revealing that they probably come from metagreywacke precursors or mediate-felsic orthogeneisses compositionally similar to them. Detailed EPMA analyses conducted on the garnets contained in the garnet-bearing granites show that all the garnets are dominated by almandine and pyrope, which occupy 92-96% (Weight Percentage) of each garnet analyzed, typical of granulite facies. Their chemical composition is entirely different from those crystallized in magmas, but extremely similar to those of typical granulite facies metapelites in khondalites and typical granulites, indicating all the garnets to be metamorphogenic. In addition, REEs distribution patterns of the garnets are totally different from typical biotite granites and peraluminous granites. In other words, both LREE and HREE of our garnets are evidently lower than those from these two kinds of rocks. Moreover, compared to the REE pattern of the garnets from typical amphibolites, LREE content of our garnets is obviously higher and HREE content is a little lower. However, REE patterns of our garnets are completely in harmony with those of garnets from typical granulites. So, the REE patterns of garnets, again, prove that all the garnets we studied are metamorphogenic. Biotites appear in two forms, being as inclusions in the garnet and as selvages immediately adjacent to the garnet, respectively. Two reactions and their corresponding temperatures, with the help of petrography and Garnet-Biotite geothermometers, could be obtained, which are Bt+ Pl+ Qtz→Kfs+ Opx+ Grt+ melt as positive reaction and Kfs+ Grt+ melt→Bt+ Pl+ Qtz as reverse reaction, respectively. Summing up the discussion above, we declare that the garnet-bearing granites distributed in the Western Block of North China Craton are the mixture of melts and restites resulted from biotite dehydration melting. The garnets contained in the restites are the products from biotite dehydration melting and restites from the khondalites, respectively.

利用台阵面波资料研究华北克拉通北缘燕山褶皱带及其邻区的地壳与上地幔结构

The continent of eastern China, especially the North China Craton (NCC), has endured intensive tectonic renovation during Mesozoic and Cenozoic, with the presence of widespread magmatism, high heat flow and development of large sedimentary basins and mountain ranges. The cratonic lithosphere of the region has been destroyed remarkably, which is characterized by not only a significant reduction in thickness but also complex modifications in physical and chemical properties of the lithosphere. As for the tectonic regime controlling the evolution of the NCC, various models have been put forward, including the impingement of mantle plumes (“mushroom cloud” model), the collision of south China block and north China block, the subduction of the Pacific plate, etc. Lithosphere delamination and thermal erosion were proposed as the two end-member mechanisms of the lithospheric thinning. However, given the paucity of the data, deep structural evidence is currently still scarce for distinguishing and testifying these models. To better understand the deep structure of the NCC, from 2000 to the present, temporary seismic array observations have been conducted in the NCC by the Seismological Laboratory of the Institute of the Geology and Geophysics, Chinese Academy of Sciences under the North China Interior Structure Project (NCISP). Many arrays extend from the North China Craton and the off-craton regions, and traverse a lot of main tectonic boundaries. A total of more than 300 broadband seismic stations have been deployed along several profiles that traversed the major tectonic units within the craton’s interior, at the boundary areas and in the neighboring off-craton regions. These stations recorded abundant high-quality data, which provides an unprecedented opportunity for us to unravel the deep structural features of the NCC using seismological methods. Among all the seismological methods, the surface wave method appears to be an efficient and widely adopted technique in studying the crustal and upper mantle structures. In particular, it can provide the absolute values of S-wave velocity that are difficult to obtain with other methods. Benefiting from the deployment of dense seismic arrays, progresses have been made in improving the spatial resolution of surface wave imaging, which makes it possible to resolve the fine-scale velocity structures of the crust and upper mantle based on surface wave analysis. Meanwhile, the differences in the S-wave velocities derived from Rayleigh and Love wave data can provide information on the radial anisotropy beneath the seismic arrays. In this thesis, using the NCISP-III broadband data and based on phase velocity dispersion analysis and inversion of fundamental mode Rayleigh and Love waves, I investigated the lateral variations in the S-wave velocity structure of the crust and uppermost mantle beneath the Yanshan Belt and adjacent regions at the northeastern boundary of the NCC. Based on the constructed structural images, I discussed possible deep processes of the craton destruction in the study region.

陕北桥镇油田延长组长2、长1油层组沉积相及储层研究

The Ordos Basin is a large-scale craton superimposed basin locating on the west of the North China platform, which was the hotspot of interior basin exploration and development. Qiaozhen oil field located in the Ganquan region of south-central of Ordos Basin. The paper is based on the existing research data, combined with the new theory and progress of the sedimentology, sequence stratigraphy, reservoir sedimentology, petroleum geology, etc, and analyzes systematically the sedimentary and reservoir characteristics in the chang2 and chang1 oil-bearing strata group of Yanchang formation On the basis of stratigraphic classification and comparison study, the strata chang2 and chang1 were divided into five intervals. Appling the method of cartography with single factor and dominance aspect, we have drawn contour line map of sand thickness, contour line map of ratio between sand thickness and stratum thickness. We discussed distribution characteristics of reservoir sand body and evolution of sedimentary facies and microfacies. And combining the field type section , lithologic characteristics, sedimentary structures, the sedimentary facies of single oil well and particle size analysis and according to the features of different sequence, the study area was divided into one sedimentary facies、three parfacies and ten microfacies. The author chew over the characteristics of every facies, parfacies and microfacies and spatial and temporal distribution. Comprehensive research on petrologic characteristics of reservoir , diagenesis types, pore types, distribution of sand bodies, physical properties, oiliness, reservoir heterogeneities, characteristics of interlayer, eventually research on synthetic classifying evaluation of reservoir.The reservoir is classified four types: Ⅰ、Ⅱ、Ⅲ、Ⅳ and pore type, fracture-porosity type. Take reservoir's average thickness, porosity, permeability, oil saturation and shale content as parameters, by using clustering analysis and discriminant analysis, the reservoir is classified three groups. Based on the evaluation, synthetizing the reservoir quality, the sealing ability of cap rock, trap types, reservoir-forming model ,in order to analyze the disciplinarian of accumulation oil&gas. Ultimately, many favorable zones were examined for chang23，chang223，chang222，chang221，chang212，chang12，chang11 intervals. There are twenty two favorable zones in the research area. Meanwhile deploy the next disposition scheme.

化德群和土门群沉积岩碎屑锆石研究：对华北克拉通基底及元古宙盆地演化的指示意义

The Huade Group, consisting of low-grade and un-metamorphosed sedimentary rocks with no volcanic interlayer, is located at the northern margin of the North China craton and adjoining the south part of the Central Asian Orogenic Belt. It is east to the Paleo- to Meso-Proterozoic Bayan Obo and Zhaertai-Langshan rifts and northwest to the Paleo- to Neo-proterozoic Yanshan aulacogen, in which the typical Changcheng, Jixian and Qingbaikou systems are developed. The Huade Group are mainly composed of pebbly sandstones, sandstones, greywackes，shales，calc-silicate rocks and limestones, partly undergoing low-grade metamorphism and being changed to meta-sandstones, schists, phyllites, slates and crystalline limestones or marbles. The stratigraphic sequences show several cycles of deposition. Each of them developed coarse clastic rocks – interbedded fine clastic rocks and pelites from bottom upward or from coarse clastic rocks to interbedded fine clastic rocks and pelites to carbonate rocks. The Tumen Group outcrop sporadically around or west to the Tanlu faults in western Shandong. They are mainly composed of pebbly sandstones, sandstones, shales and limestones. This thesis deals with the characteristics of petrology, geochemistry and sedimentary of the Huade Group and the Tumen Group, and discusses the LA-ICP-MS and SIMS U-Pb ages, Hf isotope and trace element composition of the detrital zircons from 5 meta-sandstone samples of the Huade Group and 3 sandstone samples of the Tumen Group. The age populations of the detrital zircons from the Huade Group are mainly ~2.5 Ga and ~1.85 Ga, and there are also minor peaks at ~2.0 Ga, ~1.92 Ga and ~1.73 Ga. Most of the detrital zircon grains of 2.47-2.57 Ga and a few of 1.63-2.03 Ga have Hf crust model ages of 2.7-3.0 Ga, and most of the detrital zircon grains of 1.63-2.03 Ga have Hf crust model ages of 2.35-2.7 Ga, with a peak at 2.54 Ga. The main age peaks of the detrital zircons from the Tumen Group are ~2.5 Ga、~1.85 Ga, 1.57 Ga, 1.5 Ga, 1.33 Ga and 1.2 Ga. Different samples from the Tumen Group have distinct Hf isotopic characteristics. Detrital zircon grains of ~2.52 Ga from one sandstone sample have 2.7-3.2 Ga Hf crust model ages, whereas zircon grains of 1.73-2.02 Ga and 2.31-2.68 Ga from another sample have Hf crust model ages of 2.95-3.55 Ga. Detrital zircon grains of Mesoproterozoic ages have Paleoproterozoic (1.7-2.25 Ga) crust model ages. Through detailed analyses of the detrital zircons from the Huade and Tumen Group and comparison with those from the sedimentary rocks of similar sedimentary ages, the thesis mainly reaches the following conclusions: 1. The youngest age peaks of the detrital zircons of 1.73 Ga constrains the sedimentary time of the Huade Group from late Paleoproterozoic to Mesoproterozoic. 2. The age peaks of detrital zircons of the Huade Group correspond to the significant Precambrian tectonic-thermal events of the North China craton. The basement of the North China craton is the main provenance of the Huade Group, of which the intermediate to high grade metamorphic sedimentary rocks are dominant and provide mainly 1.85-1.92 Ga sediments. 3. The Huade basin belongs to the North China craton and it is suggested that the northern boundary of the North China craton should be north to the Huade basin. 4. The stratigraphic characteristics indicate the Huade Group formed in a stable shallow-hypabyssal sedimentary basin. The rock association and sedimentary time of the Huade Group are similar to those of the Banyan Obo Group and the Zhaertai Group, and they commonly constitute late Paleoproterozoic to Mesoproterozoic continental margin basins along the northern margin of the North China craton. 5. The continental margin basins would have initiated coeval with the Yanshan and Xiong’er aulacogens. 6. The ages of the detrital zircons from the Tumen Group and the Penglai Group at Shandong peninsula and the Yushulazi Group at south Liaoning are similar, so their sedimentary time is suggested to be Neoproterozoic，coeval with the Qingbaikou system. The detrital zircon ages of 1.0-1.2 Ga from the Tumen Group, the Penglai Group and the Yushulazi Group indicate that there have being 1.0-1.2 Ga magmatic activities at the eastern margin of the North China craton. 7. The U-Pb age populations of the detrital zircons from the late Paleoproterozoic to Neoproterozoic sedimentary rocks suggest that the main Precambrian tectonic-thermal events of the North China craton happened at ~2.5 Ga and ~1.85 Ga. But the events at 2.7 Ga and 1.2 Ga are also of great significance. Hf isotope characteristics indicate that the significant crust growth periods of the North China craton are 2.7-3.0 Ga and ~2.5 Ga.

华北克拉通新生代玄武岩携带的地幔橄榄岩Fe同位素地球化学及含金云母地幔岩岩石学研究

In recent years, thanks to the improvement of analytical methods and the use of MC-ICP-MS, Fe isotope can be measured precisely. Fe isotope shows considerable variation both in biological and inorganic processes (from low T to high T) in nature, Therefore, Fe isotope has become one of the exciting frontier sciences and has favorable prospects of the application to the geosciences and life sciences. Based on a comprehensive review of available references in the related field, this study focuses on the development of techniques for high-precision measurement of iron isotope using MC-ICP-MS, and application of the techniques developed to study the Fe isotopes as well as major and trace element compositions of minerals (Ol, Opx, Cpx and Sp) from spinel peridotitic xenoliths from Cenozoic alkaline basalts to investigate Fe isotopic features of the lithospheric mantle beneath the North China Craton. The minerals from these xenoliths are similar to those off-cratonic peridotites world-wide, but are remarkably different from those on-cratonic peridotites and clinopyroxenes from these spinel lherzolites exhibit two types of chondrite-normalized REE patterns i.e. LREE-depleted and flat or spoon-shaped. It is noted that total abundances of REE in clinopyroxenes from these peridotites show a broad negative correlation with Cr# numbers of Cpx and Sp. The Fe isotope results show that the spinel peridotitic xenoliths have small but distinguishable Fe isotopic variations in minerals (generally Ol < Opx < Cpx) and samples, and the isotopic range in spinel is relatively large. Positive linear relationship with the ε57Fecpx/ε57Feopx ratio close to one unit has been observed between Fe isotopes of coexistent Opx and Cpx, indicating that the Cpx and Opx have generally reached Fe isotopic equilibrium. However, Fe isotopes between the Ol and Sp show apparent disequilibrium. The broadly negative correlation between mineral Fe isotopes and oxygen fugacity (fo2), metasomatic indexes such as spinel Cr#, (La/Yb) N and (La/Sm) N ratios of clinopyroxenes suggest that Fe isotopic variations in different minerals and peridotites were probably produced by melt-peridotite interaction. This study further confirms the previous observation that the lithospheric mantle has distinguishable and heterogeneous Fe isotopic variations at a scale of xenoliths. Mantle metasomatism that induces the interaction of the lithospheric mantle peridotite with metasomatic agent is a most potential mechanism for the Fe isotope fractionation in mantle peridotites. Therefore, Fe isotope could be a new and powerful tool to probe the evolution of the lithospheric mantle. We also report mineral compositions, clinopyroxene trace element concentrations and Sr-Nd isotopes for newly-discovered phlogopite-bearing spinel lherzolite and olivine clinopyroxenite xenoliths from three different localities （Hannuoba, Hebei Province; Jining Sangyitang, Inner Mongolia; Hebi, Henan Province）of the North China Craton. Systematic comparisons with phlogopite-free spinel lherzolite xenolith from the same locality reveals that the phlogopite-bearing peridotitic xenoliths have relatively higher Al2O3, CaO, Na2O, K2O, TiO2 contents and lower MgO contents than those phogopite-free counterparts. The former also has higher LREE concentrations, but relatively less radiogenic Sr-Nd isotopic ratios. This demonstrates that mantle metasomatism can not only enrich the basaltic components and trace element concentrations, but also make a decrease in Mg# of the peridotites and olivines and a relative depletion in Sr-Nd isotopes. 87Rb/86Sr-87Sr/86Sr isochrons of the phlogopite-bearing xenoliths indicate that mantle metasomatism happened in the Mesozoic and/or Cenozoic time. The metasomatic agent was derived from the asthenosphere. The result also manifests that the widespread similarity of the geochemical features such as major and trace elements and isotopic compositions in the Cenozoic lithospheric mantle beneath the North China Craton to those “oceanic” lithospheric mantle could be as a result of the ubiquitous presence of the interaction between the old refractory peridotites and the infiltrated asthenospheric melt, rather than the actually newly-accreted lithospheric mantle.

内蒙古白云鄂博地区元古宙构造-岩浆演化史与超大型REE-Nb-Fe矿床成因

Bayan Obo giant REE-Nb-Fe deposit in the northen margin of the North China Craton (NCC) is well known in the world for its abundant rare earth element resources. There is nearly one hundred year of studying history in substance component, chronology and geochemistry of the ore deposit, since the main ore body was found in 1927. However, there still exist remarkable divergences in genesis, mineralized age and material origin. Especially the REE enrichment mechanism leaves us a secret. Recent research shows that the Bayan Obo ore deposit likely resulted from the carbonatite magma activity, which is a favorable factor for REE accumulation. Based on the analysis of tectonic evolution history of north margin of NCC this thesis mainly discussed the formation background of cratonic margined rifts in Bayan Obo, and presented the analytical results of formation environment, intrusion age and deep origin of Proterozoic carbonatite magma. These research results can provide evidence for ore genesis. LA ICP-MS U-Pb dating on zircon shows that the Neoarchean basement was mainly composed of calc-alkaline TTG gneisses (2588±16Ma). The collision orogeny movement of the northen margin of the NCC between 2.0 Ga to 1.9 Ga brought the swarm of diorite-granodiotite magma (2023±16Ma) and intense regional metamorphism event (1906.3±7.7 Ma to 1892.7±6.7 Ma). In the sequent super continent break up background, intense metamorphic and deformed basement complex was uplifted to the surface suffered denudation, forming Mesoproterozoic Bayan Obo group in the contemporary continental margin rifts. The uplift of basement complex and formation of continental rifts were likely related with mantle plume activity. Evidence from petrological and geochemical data suggests that abundant alkaline-basic magma resulted from enhancement of continental breakup activity, that separated into carbonatite veins and mafic dykes by melt immiscibility mechanism, intruded in Bayan Obo margin rifts at the late stage of extension movement. Carbonatite veins can be divided into three main types by mineral composition: dolomite carbonatite, dolomite-calcite coexistent carbonatite and calcite carbonatite. Intrusion relationship between different types of carbonatite veins show that the calcite carbonatite veins were formed latter than the dolomite type as well as the coexistent type. Moreover, geochemical data also reveals successive and evolutive character between them. The content of REE increases together with the calcite minerals component. That is to say that REE gradually accumulated as the evolution of carbonatite magma. High precision Sm-Nd isochron data shows that the intrusion age of carbonatite veins was at 1319±48Ma. Moreover, the REE mineralization age in calcite carbonatite veins was around 1275±87Ma that is consistent with the intrusion age in error range. According to these data the abundant REE already existed in the carbonatite magma before intrusion and result in the earlier ore mineralization. The average age of mineralized dolomite was at 1353±100Ma, and the mineralization age of apatite in coarse grain dolomite was around 1329±150Ma. These data is consistent with carbonatite. Considering the coincident rare, trace element and isochron composition between them, it is presumed that mineralized dolomite was also the carbonatite intrusion and was the mainly factor for huge REE enrichment.

中国华北和美国加州地区地震层析成像研究

In recent years seismic tomography has become a powerful tool for studying the three-dimensional crust and mantle structure. In this study, we collected a large number of regional and teleseismic travel-time data and used seismic tomography method to study the relationship between earthquake occurrence and crustal heterogeneity for the 1992 Landers earthquake, heterogeneity and evolution of lithosphere under North China Craton and Southern California, and deep structure and origin of the Changbai intraplate volcano in Northeast China. Our results show a correlation between the seismic rupture zone and crustal heterogeneity. The distribution of the Landers aftershocks is cluster-like and separated or terminated in areas where low-velocity anomalies exist．Most of the large earthquakes with magnitudes >4.0 occurred in or around areas with high P-wave velocity．The possibility is that high-velocity areas are brittle and strong parts which can sustain seismogenic stress，and so can generate earthquakes. Our tomographic images show a very heterogeneous structure in the crust and upper mantle beneath Southern California. Three major anomalies in the upper mantle are revealed clearly beneath the southern Sierra Nevada, Transverse Ranges and Salton Trough. We consider that the high-velocity anomaly beneath the Transverse Ranges was formed through asymmetrical two-side convergence of subcrustal lithosphere and sinking to asthenosphere. Formation of the dense crust root and “drip structure” caused the high-velocity anomaly under the southern Sierra Nevada. The Salton Trough low is the response to the lithospheric extension when the Pacific plate was rifted away from the North American Plate. The tomograpic images beneath the North China Craton show that there exist different lithospheric structures under the different blocks. Complex, prominent low-velocity and high-velocity anomalies are imaged beneath the North China Basin, Trans-North China Orogen (TNCO), and Ordos Block which correspond to rifted, orogenic and cratonic lithospheres, respectively. The thickness of the three-type lithospheres is about 70, 90 and >250 km, respectively. Our results suggest that lithospheric thinning under the eastern part of North China Craton is due to long-term replacement and chemical and thermal erosion of the ancient lithosphere by the hot asthenosphere. The remains of ancient lithosphere exist either in the present upper mantle or have sunk into the mantle transition zone. Our tomographic result of the Changbai volcanic area suggests that the origin of the Changbai volcano is related to the deep dehydration of the subducted Pacific slab and corner flow in the big mantle wedge (BMW) above the stagnant Pacific slab.

安塞油田三叠系延长组长10油层组沉积相研究

Ordos basin is a large-scale craton overlapping basin, which locates in western North China platform and possesses abundant hydrocarbon resources. Ansai area in 2007 to extend the head of Chang10 of Yangchang Formation has made breakthrough progress in the region, long a high of Gao52 was Chang10 industrial oil flow, for oil exploration Ansai Oil Field opened a new chapter. in 2008, high of Gao52, Wang519, Gao34 producing wells area of building and found the existence of Chang10 great potential for the discovery of Chang10 Reservoir, Ansai Oil Field for a new direction, showing a good exploration development prospects.The study of occurrence and distribution features of hydrocarbon should be made by new theories and evolutions of sedimentology, sequence stratigraphy, reservoir sedimentology and petroleum geology form different angles on the base of regional geology background. Ansai Oil Field is in mid Shanbei Slope, which is a considerable producing zone of Ordos basin. Chang10 of Yangchang Formation is an important oil-bearing series, which sedimentary formation was formed in Indosinian orogeny, Late Triassic, sedimentary background is a momentary uplifting in Ordos basin, and exploration and exploitation of hydrocarbon in this area is very important. To further descripte disciplinarian of accumulation hydrocarbon, carefully study on sedimentary facies, reservoir type and disciplinarian of accumulation hydrocarbon of Chang10 of Yangchang Formation in study area is needed. By collecting date of field profile, outcrop, core and many other geological, through sedimentary and oil geological analysis, sedimentary facies types were identified, distributing of sedimentary facies and extension of sand body were analyzed too. Finally, the main controlling factors of hydrocarbon and the favorable areas were found out by deeply studying sedimentary system and disciplinarian of accumulation oil&gas in Chang10 of Yangchang Formation, Late Triassic in Ansai Oil Field. Chang10 of Yangchang Formation is main study formation, which is divided into three members (Chang101, Chang102 and Chang103), Chang101 is subdivided into three (Chang1011, Chang1012and Chang1013) reservoirs. By defining Layered borderline between every member and detailed describing rock and electro characteristic, member zonation become more reasonable and accurate also sedimentary facies and disciplinarian of accumulation oil&gas in study area are confirmed Through researching sedimentary facies, reservoir sand and hydrocarbon migration, accumulation, distribution, hydrocarbon accumulation models of Chang10 of Yangchang Formation in study area is pointed out, which is lithologic hydrocarbon reservoir and tectonic-lithologic hydrocarbon reservoir. Different play is formed by different processes and factors. Through analysis of reservoir property, trap type and accumulation model, several favorable exploration areas can be found out in Chang 10 reservoirs （Chang1011, Chang1012and Chang1013） of the Ansai Oil Field.

碎屑锆石年龄和Nd-Hf同位素组成对扬子基底演化的制约

The South China craton was formed by the collision of the Yangtze and Cathaysia blocks during the Neoproterozoic Jiangnan orogeny (also termed as the Jingnin or Sibao orogeny in Chinese literature). Basement rocks within the Yangtze block consist mainly of Proterozoic sediments of the Lengjiaxi and Banxi Groups. U-Pb ages of detrital zircons obtained by the LA-ICP-MS dating technique imply that the deposition of the Lengjiaxi Group continued until the Neoproterozoic. The youngest detrital zircons suggest a maximum deposition age of ~830 Ma for the Lengjiaxi Group, consistent with the initiation time of the deposition of the overlying Banxi Group, likely indicating continuous deposition of these two groups and a short temporal hiatus (~10 Ma) between the Neoproterozoic sedimentary rocks distributed in the South China craton. Detrital zircons from both the Lengjiaxi and Banxi Groups have a wide range of εHf(t) values from -12 to 14.2 and a continuous Nd and Hf model age spectrum from ~820 Ma to 2200 Ma. Some grains have model ages ranging up to ca. 2.9-3.5 Ga, indicating that both juvenile mantle material and ancient crust provided sedimentary detritus. This is also consistent with the Nd isotopic signature of sedimentary rocks recorded in the Lengjiaxi Group, suggesting a back-arc tectonic setting. The Banxi Group has slightly enriched Nd isotopic signatures relative to the Lengjiaxi Group, implying a higher percentage of old continental material in the sedimentary source. Combined with previously published data, new results can help us to reconstruct the Neoproterozoic tectonic evolution of the South China craton. The age spectrum of detrital zircons and Nd-Hf isotopic composition suggests a two-stage collision: Between 1000 Ma to 870 Ma, a continental magmatic arc was build up along the eastern margin of the Yangtze block. Convergence led to continent-based back-arc extension, subsidence and formation of a back-arc basin. Detritus originating from arc-related magmatic and old basement rocks was transported into this back-arc basin resulting in formation of the Lengjiaxi Group and its equivalents. At around 870 Ma, a second (oceanic) arc was formed by extension of an inter-arc basin, subduction subsequently led to the first collision and the emplacement of the blueschist mélange. Accretion of the magmatic arc lasted until the closure of an oceanic basin between the Yangtze and Cathaysia blocks at about 830 Ma. Shortly after the collision, subsequent uplift, further extension of the former back-arc basin and post-collisional granitoid magmatism caused a tilting of the Lengjiaxi sediments. Between 830 Ma and 820 Ma, subsequent closure of the oceanic back-arc basin and formation of the Jiangnan orogen took place, leaving a regional unconformity above the Lengjiaxi Group. Above this unconformity the Banxi Group was immediately deposited during the post-tectonic stage.

中国大陆地区远震体波接收函数与岩石圈厚度的研究

Movements of separation and convergence between the continental plates, as well as the interaction beween the lithosphere and asthenosphere is the dominant factor in plate evolution. Moreover, those phenomena, the formation, enrichment and storage of energy and mineral strorage, as well as intraplate earthquakes are all relate to plate movement and evolution. Therefore, the study of continental lithosphere, is not only helpful to analysing the dynamic model between lithosphere and asthenoshere as well as different plates, but also important to the nation's economy and the people's livelihood. And the lithospheric thickness or Lithosphere-Asthenosphere Boundary (LAB) is one of the most important parameters in study of continental lithospheric formation and evolution. Chinese continent composed by many small plates, possesses diverse type of lithospheric structure. But our knowledge ahout Chinese continental lithosphere, especially the regional research, is almost based on the low-resolution results of surface wave dispersion analysis and seismic wave tomography. Howere, recently a technique employing S-to-P converted body waves (the S receiver function technique) has been developed that can be used to identify the LAB with a higher resolution. This thesis has collected waveform data of 232 broadband seismic stations that are located in China and neighboring regions. Using teleseismic S-wave and P-wave receiver functions have studied the Chinese continental lithospheric structure. The results of this study indicate that, the thickness of Chinese continental lithosphere become thinner from west to east, and obvious difference exists between different blocks. Four types of lithosphere have been detected: (1) Convergence thicking lithosphere in Tibetan Plateau; (2) Stable lithosphere in Tarim basin and upper Yangtze craton; (4) Active lithosphere in Orogenic belts; (4) Break-up thinning lithosphere in east China craton

新增生岩石圈与软流圈的相互作用：来自地幔橄榄岩捕虏体的证据

The petrology and geochemistry of peridotites entrained in Beiyan Cenozoic alkaline basalts within the middle segment of Tan-Lu fault zone and clinopyroxene megacrysts in the late Mesozoic and Cenozoic alkaline basaltic rocks from the North China Craton, have been systematically investigated. The main conclusions are obtained as follows. The peridotites entrained in alkaline basalts at Beiyan, Shandong Province, China are comprised of dominantly spinel lherzolites and spinel wehrlites with porphyroclastic, granuloblastic textures to resorption textures. The xenoliths are fertile in major element compositions (High CaO, TiO2, Low MgO, Cr2O3). The olivine Fo (= 100×Mg / (Mg+Fe) possesses a low and very large range of 81.0 to 91.0. The peridotites contain high percentages (Lherzolites: 10 - 19% in volume; Wehrlites: 24 - 28% in volume) of clinopyroxene with spongy textures. The Sr and Nd isotopic ratios of clinopyroxene separates from peridotites and pyroxenite xenoliths have a depleted and small range fall within the area of MORB, similar to newly-accreted lithospheric mantle. However, the appearance of many wehrlites and highly enriched LREE pattern suggest that this newly-accreted lithospheric mantle was considerably modified and reconstructed recently through the peridotite-asthenospheric melt interaction. The upwelling of asthenosphere from late Cretaceous to Eogene and upper mantle shearing of the Tan-Lu fault played an important role in the modification and reconstruction of the newly-accreted lithospheric mantle. The clinopyroxene megacrysts in the late Mesozoic and Cenozoic alkaline basaltic rocks from the eatern North China Craton are different in aspects of major elements, trace elements and isotopic composition. The characteristics of texture, mineral compositions and geochemistry as well as the Fe-Mg partitioning between the crystal and the melt indicates that the Al-augites in the Cenozoic basalts represent high-pressure crystallization products of alkaline basaltic melts. Thus, both of clinopyroxene megacrysts and host basalts could be derived from a same primitive magma. However, the Al-augites in the late Mesozoic basaltic rocks represent accidentally-included xenocrysts of basaltic components which had crystallized in the depth from a previously melting episode. The more depleted Sr-Nd isotopic compositions of Cenozoic megacrysts compared with those of host alkaline basalts and tholeiites demonstrate that even the alkali basalts could not completely represent primitive magma initiating in asthenosphere. That is to say, the Cenozoic alkaline basalts were more or less modified by some enriched Sr-Nd isotopic components during their eruption. Meanwhile, the tholeiites were not the products formed only by fractional crystallization of alkaline basaltic magma or different degrees of partial melting. It may result from the contribution of lithospheric mantle materials or crust contamination in magma chamber to alkali basaltic magmas.

特提斯喜马拉雅带晚白垩世-始新世沉积源区分析及其构造意义

Tethyan Himalayan Sequence (THS) is located at the frontier of the India-Asia collision zone, which can preserve critical information about collision. This paper reports detailed petrology, geochemistry, spinels electron microprobe data, and in situ U-Pb ages and Lu-Hf isotopic data on detrital zircons from the late Cretaceous to early Eocene strata in Gyantze and Gamba area, south Tibet that provide important constraints on the early tectonic evolution of the India-Asia collision. In Gyantze, the lithic arkose in Zongzhuo mélange is characterized by, SiO2 =80.4%, Al2O3=8.6%, Na2O=1.6%, K2O=1.1%, LaN/YbN=8.90, and εNd (0) =-10.27. Spinels compositions are characterized by low TiO2 (generally <0.1%) and a Cr number mainly between 70 and 80. The largest population of detrital zircons is within the 73-169Ma range with high εHf (t) and > 500 Ma with complex εHf (t) values. The lithic arkose in Rilang conglomerate is characterized by, SiO2 =56.5%, Al2O3=15.6%, Na2O=4.7%, K2O=0.6%, LaN/YbN=5.00-5.29, and εNd (0) =1.92. Spinels of 2006T98 display high TiO2 (generally >0.2%) and a Cr number mainly between 70 and 85, other spinels are characterized by low TiO2 (generally <0.2%) and a Cr number mainly between 60 and 90. The largest population of detrital zircons is within 90-146 Ma range with high εHf (t). The lithic arkose in Jiachala formation is characterized by, SiO2 =64.6%, Al2O3=12.1%, Na2O=1.9%, K2O=1.8%, LaN/YbN=7.73-9.13, and εNd (0) =-5.52~-8.43. Spinels in the Jiachala formation have low TiO2 (generally <0.2%) and a Cr number between 39 and 88. Detrital zircons have a wide range of age distribution of 82-3165Ma with complex εHf (t). In Gamba, The quartze sandstone in Jidula formation is characterized by, SiO2=97.4%, Al2O3=0.9%, Na2O=0.03%, K2O=0.18%, LaN/YbN=18.70-21.684, and εNd (0) between -13.1~-7.4. While the lithic arkose in Zhepure formation is characterized by, SiO2=68.4%, Al2O3=7.3%, Na2O=1.15%, K2O=0.52%, LaN/YbN=6.09-8.99, and εNd(0)=-5.8~-6.3. Based on our geochemical analysis, spinles electron microprobe data, U–Pb ages and Hf isotope data for detrital zircons of the late Cretaceous-Eocene strata in Gyantze and Gamba, southern Tibet, the following major conclusions can be drawn: 1. In Gyantze, the Zongzhuo mélange was mainly derived from accretionary prism/THS of continental slop and Gangdese arc. Rilang conglomerate was totally from Gangdese arc. The Jiachala formation was derived from THS, suture zone and Gangdese arc. 2. In Gamba, the Jidula formation was from India craton, while the Zhepure formation was derived from THS, suture zone and Gangdese arc. 3. The deposite of Zongzhuo mélange and Rilang conglomerate (73-55Ma) marks the collision between India and Asia. 4. Late Paleocene-Eocene tectonic evolution is consistent with foreland basin system.