大兴安岭北段晚中生代火山岩地球化学特征及其地质意义

This thesis mainly concentrates on the geochronology, prtrology, elemental geochemistry and Sr-Nd-Pb-Hf isotopic geochemistry of the volcanic rocks in north Da’Hinggan Mountain. By analyzing the data obtained in this study and data from other people, this thesis explored the age distribution, petrology and mineralogy and geochemistry characteristics of the volcanic rocks in north Da’Hinggan Mountain. Furthermore, this thesis speculated upon the source characteristics of these volcanic rocks and their implications for the tectonic evolution and crust accretion. According to the twenty Ar-Ar ages, four zircon U-Pb SHRIMP ages and two Zircon U-Pb LA-ICP-MS ages, the duration of the eruption of the Late Mesozoic volcanic rocks in north Da’Hing Mountain was about 160Ma-106Ma. Most of these volcanic rocks belong to early Cretaceous and the late Jurassic volcanic rocks are only restricted in Manzhouli. The bulk of the late Mesozoic volcanic rocks are high-K calc-alkaline rocks. Only a small portion of these volcanic rocks are shoshonites. These rocks are mainly intermediate or acid and the basic rocks usually have higher alkaline contents. Rock types are very complex in this region. These volcanic rocks have a large TiO2 variation and the Al2O3 and alkaline contents are high. From the point of mineralogy, the plagioclases in these volcanic rocks are oligoclases, andesines and labradorites, and the labradorites are more common. Most pyroxenes in these volcanic rocks are augites which belong to clinopyroxene. The source of the Late Mesozoic volcanic rocks was an enriched lithospheric mantle. When the magma en route to the surface it was contaminated by crust material slightly and had some fractional crystallization. These rocks which mainly belong to high-K calc-alkaline series were one of the results of postorogenic tectonic-magmatic activities. The upwelling in late Mesozoic supplied heat to melt the enriched lithospheric mantle which was resulted from the subduction of paleo-Asian Ocean and/or Mengol-Okhotsk ocean. These late Mesozoic volcanic rocks are also important to the upper crustal accretion of north Da’Hinggan Mountain since the late Mesozoic. These volcanics and the contemporary emplacement of granites and the basaltic underplating in combination fulfilled the crust accretion history in north Da’Hinggan Mountain in Late Mesozoic.

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.

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.

班公湖带多不杂超大型富金斑岩铜矿床的成岩成矿年代学、岩石学及高氧化岩浆¬流体-成矿作用

Duobuza copper deposit, newly discovered typical gold-rich porphyry copper deposit with superlarge potential, is located in the Tiegelong Mesozoic tectonic -magmatic arc of the southern edge of Qiangtang block and the northern margin of Bangonghu-Nujiang suture. Quartz diorite porphyrite and grandiorite porphyry, occurred in stock, are the main ore-bearing porphyries. As the emplacement of porphyry stock, a wide range of hydrothermal alteration has developed. Within the framework of the ore district, abundant hydrothermal magnetite developed, and the relationship between precipitation of copper and gold and hydrothermal magnetite seems much close. Correspondingly, a series of veinlets and network veinlets occurred in all alteration zones. Therefore, systematic research on such a superlarge high-grade Duobuza gold-rich porphyry copper deposit can fully revealed the metallogenic characteristics of gold-rich porphyry copper deposits in this region, establish metallogenetic model and prospecting criteria, and has important practical significance on the promotion of regional exploration. In addition, this research on it can enrich metallogenic theory of strong oxidation magma-fluid to gold-rich porphyry copper deposit, and will be helpful to understand the metallogenic characteristics in early of subduction of Gangdese arc stages and its entire evolution history of the Qinghai-Tibet Plateau, the temporal and spatial distribution of ore deposits and their geodynamics settings. Northern ore body of Duobuza copper deposit have been controlled with width (north-south) about 100 ~ 400 m, length (east-west) about 1400 m, dip of 200 °, angle of dip 65 °~ 80 °. And controlled resource amount is of 2.7 million tons Cu with grade 0.94% and 13 tons Au with 0.21g/tAu. Overall features of ore body are large scale, higher grade copper, gold-rich. Ore occurred in the body of granodiotite porphyry and quartz diorite porphyrite and its contact zone with wall rock. Through the detailed mapping and field work studies, some typies of alteration are identificated as follows: albitization, biotititation, sericitization, silication, epidotization, chloritization, carbonatization, illitization, kaolinization and so on. The range of alteration is more than 10km2. Wall alteration zone can be divided into potassic alteration, moderate argillization alteration, argillization, illite-hydromuscovite or propylitization from ore-bearing porphyry center outwards, but phyllic alteration has not well developed and only sericite-quartz veins occurred in local area. Moreover, micro-fracture is development in ore district , and correspondingly a series of veinlets are development as follows: biotite vein (EB type), K-feldspar-biotite-chalcopyrite-quartz vein, magnetite-antinolite-K-feldspar vein, quartz-chalcopyrite-magnetite veins (A-type), quartz-magnetite-biotite-K-feldspar vein, chalcopyrite veinlets in potassic alteration zone; (2) chalcopyrite occurring in the center vein–quartz vein (B type), chalcopyrite veinlets, chalcopyrite-gypsum vein in intermediate argillization alteration; (3) chalcopyrite- pyrite-quartz vein, pyrite-quartz vein, chalcopyrite-gypsum veins, quartz-gypsum- molybdenite-chalcopyrite vein in argillization alteration; (4) gypsum veins, quartz-(molybdenite)-chalcopyrite vein, quartz-pyrite vein, gypsum- chalcopyrite vein, potassium feldspar veinlets, Carbonate veins, quartz-magnetite veins in the wall rock. In short, various veins are very abundant within the framework of the ore district. The results of electronic probe microscopy analysis (EMPA) indicate that Albite (Ab 91.5~99.7%) occurred along the rim of plagioclase phenocryst and fracture, and respresents the earliest stages of alteration. K-feldspar (Or 75.1~96.9%) altered plagioclase phenocryst and matrix or formed secondary potassium feldspar veinlets. Secondary biotite occurred mainly in phenocryst, matrix and veinlets, belong to magnesium-rich biotite formed under the conditions of high-oxidation magma- hydrothermal. Chloritization developed in all alteration zones and alterd iron- magnesium minerals such as biotite and hornblende and then formed chlorite veinlets. As the temperature rises, Si in the tetrahedral site of chlorite decreased, and chlorite component evolved from diabantite to ripiolite. The consistent 280℃~360℃ of formation temperature hinted that chlorite formed on the same temperature range in all alteration zones. However, formation temperature range of chlorite from the gypsum-carbonate-chlorite vein was 190℃~220℃, and it may be the product of the latest stage of hydrothermal activity. The closely relationship between biotite and rutile indicate that most of rutiles are precipitated in the process of biotite alteration and recrystallization. In addition, the V2O3 concentration of rutile from ore body in Duobuza gold-rich porphyry copper deposit is >0.4％, indicate that V concentration in rutile has important significance on marking main ore body of porphyry copper deposit. Apatites from Duobuza deposit all are F-rich. And apatite in the wall rock contained low MnO content and relatively high FeO content, which may due to the basaltic composition of the wall rocks. The MnO in apatite from altered porphyry show a strong positive correlation with FeO. In addition, Cl/F ratio of apatite from wall rock was highest, followed by the potassic alteration zone and potassic alteration zone overprinted by moderate argillization alteration was the lowest. SO2 in Apatite are in the scope of 0 to 0.66%, biotite in the apatite has the highest SO2, followed by the potassic alteration zone, potassic alteration zone overprinted by moderate argillization alteration, and the lowest in the surrounding rocks, which may be caused by the decrease of oxygen fugacity of hydrothermal fluid and S exhaust by sulfide precipitation in potassic alteration. Magnetite in the wall rock have higher Cr2O3 and lower Al2O3 features compared with altered porphyry, this may be due to basalt wall rock generally has high Cr content. And magnetites have higher TiO2 content in potassic alteration than moderate argillization alteration overprinted by potassic alteration, argillization and wall rock, suggested that its formation temperature in potassic alteration was the highest among them. The ore minerals mainly are chalcopyrite and bornite, and Au contents of chalcopyrite, bornite, and pyrite are similar with chalcopyrite slightly higher. The Eu* negative anomaly of disseminated chalcopyrite was relatively lower than chalcopyrite in veinlets. Within a drill hole, the Eu* negative anomaly of disseminated chalcopyrite was gradually larger from bottom to top. Magnetite has the same distribution model, with obvious negative Eu* abnormal, and ΣREE in great changes. The gypsum has the highest ΣREE content and the obvious negative anomaly, and biotite obviously has the Eu* abnormal. Based on the petrographic and geochemical characteristics, five series of magmatic rocks can be broadly classified; they are volcanic rocks of the normal island arc, high-Nb basaltic rocks, adakites, altered porphyry and diorite. The Sr, Nd, Hf isotopes and geochemistry of various series of magmatic rock show that they may be the result of mixing between basic magma and various degrees of acid magma coming from lower crust melted by high temperature basic underplating from partial melting of the subduction sediment melt metasomatic mantle wedge. Furthermore S isotope and Pb isotope of the sulfide, ore-bearing porphyries and volcanic rocks indicated ore-forming source is the mantle wedge metasomatied by subduction sediment melt. Oxygen fugacity of magma estimated by Fe2O3/FeO of whole rock and zircon Ce4+/Ce3+ indicated that the oxidation of basalt-andesitic rocks is higher than ore-forming porphyry, and might imply high-oxidation characteristics of underplated basic magma. Its high oxidative mechanism is likely mantle sources metasomatied by subduction sediment magma, including water and Fe3+. And such high oxidation of basaltic magma is conducive to the mantle of sulfides in the effective access to melt. And the An component of dark part within plagioclase phenocryst zoning belong to bytownite (An 74%), and its may be a result of magma composition changes refreshment by basaltic magma injection. SHRIMP zircon U-Pb and LA-ICP-MS zircon U-Pb geochronology study showed that the intrusions and volcanic rocks from Duobuza porphyry copper deposit belong to early Cretaceous magma series (126~105Ma). The magma evolution series are as follows: the earliest diorite and diorite porphyrite → ore-bearing porphyry and barren grandiorite porphyry →basaltic andesite → diorite porphyrite → andesite → basaltic andesite, and magma component shows a evolution trend from intermediate to intermediate-acid to basic. Based on the field evidences, the formation age of high-Nb basalt may be the latest. The Ar-Ar geochronology of altered secondary biotite, K-feldspar and sericite shows that the main mineralization lasting a interval of about 4 Ma, the duration limit of whole magma-hydrothermal evolution of about 6 Ma, and possibly such a long duration limit may result in the formation of Duobuza super-large copper deposit. Moreover, tectonic diagram and trace element geochemistry of volcanic rocks and diorite from Duobuza porphyry copper deposit confirm that it formed in a continental margin arc environment. Zircon U-Pb age of volcanic rocks and porphyry fall in the range of 105~121Ma, and Duobuza porphyry copper deposit locating in the north of the Bangonghu- Nujiang suture zone, suggested that Neo-Tethys ocean still subducted northward at least early Cretaceous, and its closure time should be later than 105 Ma. Three major inclusion types and ten subtypes are distinguished from quartz phenocrysts and various quartz veins. Vapor generally coexisting with brine inclusions, suggest that fluid boiling may be the main ore-forming mechanism. Raman spectrums of fluid inclusions display that the content of vapor and liquid inclusion mainly contain water, and vapor occasionally contain a little CO2. In addition, the component of liquid inclusions mainly include Cl-, SO42-, Na+, K+, a small amount of Ca2+, F-; and Cl- and Na+ show good correlation. Vapor mainly contains water, a small amount of CO2, CH4 and C2H6 and so on. The daughter minerals identified by Laman spectroscopy and SEM include gypsum, chalcopyrite, halite, sylvite, rutile, potassium feldspar, Fe-Mn-chloride and other minerals, and ore-forming fluid belong to a complex hydrothermal system containing H2O-NaCl-KClFeCl2CaCl2. H and O isotopic analysis of quartz phenocryst, vein quartz, magnetite, chlorite and gypsum from all alteration zones show that the ore-forming fluid of Duobuza gold-rich porphyry copper deposit consisted mainly of magmatic water, without addition of meteric water. Duobuza gold-rich porphyry copper deposit formed by the primary magmatic fluid (600-950C), which has high oxidation, ultra-high salinity and metallogenic element-rich, exsolution direct from the magma, and it is representative of the typical orthomagmatic end member of the porphyry continuum. Moreover, the fluid evolution model of Duobuza gold-rich porphyry copper deposit has been established. Furthermore, two key factors for formation of large Au-rich porphyry copper deposit have been summed up, which are ore-forming fluids earlier separated from magma and high oxidation magma-mineralization fluid system.

东天山后碰撞镁铁-超镁铁岩镍铜硫化物矿床PGE地球化学示踪与富集规律研究

Eastern Tianshan area, a Paleozoic complex trench-arc-basin system, experienced multi-period sudbuction and collision in geological history. A large number of Early Permian mafic-ultramafic intrusions emplaced along deep faults in post-collision extension tectonic stage and hosted a series of magmatic Cu-Ni sulfide deposits. This paper sets newly-discovered Tianyu magmatic Cu-Ni sulfide deposit related to small intrusion as an example. On basis of the study of ore-forming mechanism of Cu-Ni deposit, we compared PGE content and discussed enrichment mechanism and regularity of mafic-ultramafic rocks and ores in Jueluotage tectonic belt and Central Tianshan Massif. PGE and Cu, Ni, S contents correlate with each other. PGE is mainly controlled by S content.Samilar PGE distribution patterns of mafic-ultramafic show that complex originated from the same parental magma; Pd/Ir and Ni/Cu ratios indicate that high-Mg basaltic magma and deep sulfide segregation happened during magma evolution process. PGE and Cu-Ni ores are enriched in liquid sulfide and only individual samples completely control by monosulfide solid solution. Comparison of all control factors, early segregation of sulfide and quality of supply of magma may be the key factors leading to the Eastern Tianshan magmatic copper-nickel sulfide deposits don’t reach PGE grade, but we do not rule out the possibility of occurrence continuous mafic-ultramafic rocks and PGE-rich layer in deep.

内蒙古中部道郎和都格铜多金属矿的地质特征矿床类型及找矿模式研究

Daolangheduge copper polymetallic deposit is located on east edge of Ondor Sum-Bainaimiao metallogenic belt, which is a prospective area of porphyry copper deposit, in Xianghuangqi of central Inner Mongolia. Geotectonically, it occurred in the continental margin accretion belt along the north margin of North China Plate, south of the suture zone between North China Plate and Siberian Plate. The intrusive rocks in this area mainly consist of intermediate-acid magmatic rocks, and the quartz veins, tourmaline veins and the transitional phase are comparatively developed. According to our research, the ore-bearing rock body is mainly quartz diorite while the surrounding rock is mainly biotite granite. Besides, the wall rock alteration are mainly propylitization, pyritization and silicification, which consist of epidotization, actinolitization, chloritzation and so on. The metallic minerals are mainly chalcopyrite and pyrite. In addition, the primary ore is mainly of quartz-chalcopyrite-pyrite type. Above all, Daolangheduge copper polymetallic deposit is suggested to be categorized in the porphyry copper type. With isotopic dating and geochemical research on quartz diorite of ore-bearing rock body, the zircon LA-ICP-MS U-Pb dating of two samples yields an age of 266±2 Ma, falling into the range of late Permian Epoch. It is the first accurate age data in Xianghuangqi area, so it should play a key role in the research of deposit and magmatic rocks in this area. With the major elements and trace elements analysis of 14 samples, the quartz diorite should be among the calc-alkaline series, the geochemical characteristics show higher large-ion lithophile elements of Rb, Sr and LREE, low high-field strength elements of Nb, Ta and high transition elements of Cu, Cr . Also, the REE patterns have negative Eu anomalies. With the same analysis of 4 sample for the biotite granite, the geochemical characteristics show higher Rb, Th,, Zr, Hf and LREE, low Nb, Sm and HREE and Eu has no anomaly. It should be among the calc-alkaline series, over aluminum quality and has characteristics of Adakites. According to isotopic dating and geochemical characteristics of ore-bearing rock body, it is suggested that its materials mainly derived from upper mantle that had fractional crystallization and its magma source region may be affected by fluid metasomatism of paleo-asian ocean. It should be an extensional process of post-orogeny according to regional tectonic evolution. Consequently, because of the decrease of temperature and pressure, the ore forming fluid was raised to surface and mineralized accompanied by magmatic activity which might occur in south of the suture zone. By geological survey, further geophysical and geochemical work is needed. In this area, we have accomplished high precision magnetic prospecting, high density electrical survey, gravity prospecting, soil geochemical prospecting, X-ray fluorescence analyzer prospecting and so on. According to geophysical and geochemical abnormal and surface occurrence, 11 drills are arranged to verification. The type of ores are mainly quartz-chalcopyrite-pyrite ores within 3 drills by drill core logging. Although the grade as well as the scale of already-found Cu deposits are insufficient for industrial exploitation, the mineralization prospect in this region is supposed to be great and the potential in mineral exploration at depth is excellent.

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.

华北北缘斜长角闪岩的部分熔融实验及其地质意义

基性岩类的（脱水）部分熔融实验是研究地球内部中酸性岩浆（熔体）形成的重要实验方法，自二十世纪70年代以来越来越受到地质学家的高度重视。华北北缘广泛分布的中生代埃达克质岩石的成因，十几年来引起国内外学者的激烈争论，至今仍没有定论。近年来的研究表明张家口地区同时出露的古老太古宙中基性下地壳岩石、中生代中酸性埃达克质岩浆岩以及汉诺坝基性麻粒岩包体等可能反映了源岩和熔融产物的综合信息，这为我们运用实验岩石学手段研究华北北缘埃达克质岩石成因提供了非常理想的条件。 本文在1.5-2.0GPa，800-1000℃条件下，对采自华北北缘的斜长角闪岩同时进行了块状与粉末状两种样品的部分熔融实验研究，利用电子探针对各实验产物进行了主量元素分析以及利用LA-ICP-MS对部分熔体进行了微量元素测试，进而比较了相同条件下块状和粉末状样品的熔融特征，并对比了实验获得的熔体与华北北缘中生代埃达克质岩石的地球化学特征，同时也将实验获得的残留体与汉诺坝基性麻粒岩包体进行了比较。获得以下主要认识： （1）相同的温度、压力和恒温时间条件下块状样品的熔融温度比粉末样品的更低。在1.5-2.0GPa，800℃时块状斜长角闪岩样品已经发生部分融融，而相同条件下粉末样品中没有观察到熔体，粉末样品的部分熔融发生在850℃左右。在850-1000℃温度范围内，相同条件下块状样品的熔体含量比粉末样品的熔体含量高出5-17vol.％，即相同条件下块状样品比粉末样品的熔融程度更高，说明块状样品更容易达到可以分凝形成岩浆的临界熔体分数（CMF），这可能暗示着自然界中的岩浆形成可能比以往通过粉末实验结果推测的更容易发生。此外，在较高的温度条件下（950-1000℃），块状样品与粉末样品的熔体在主量和微量元素上都具有大致相同的地球化学特征，可以认为二者在在岩石学应用上是等效的。 （2）1.5GPa下实验获得的熔体为花岗质－花岗闪长质熔体，850-1000℃熔体的主-微量元素的地球化学特征与华北北缘中生代埃达克质岩石的整体特征具有很好的相似性，并与实验原岩产地张家口地区的三个典型中酸性埃达克质岩体的地球化学特征类似。可以认为实验的斜长角闪岩在1.5GPa下部分熔融能够形成华北北缘中生代埃达克质岩石。2.0GPa下的实验熔体为花岗质－奥长花岗质成分，其主量和微量元素特征均与华北北缘埃达克质岩石存在较大的差别，说明该压力下不能够形成华北北缘埃达克质岩石。 （3）实验残留相主要组成为Hb+Cpx+Gt±Pl，相当于麻粒岩相或榴辉岩相的矿物组合。与汉诺坝基性麻粒岩包体的典型矿物组合Cpx+Opx+Pl存在较大差别，在化学成分上，残留相比麻粒岩包体也整体上富Fe、Al，而贫Mg、Ca。综合来看汉诺坝基性麻粒岩包体可能是多种源岩在相对低压的条件下经过多期部分熔融综合作用的结果，本次实验的原岩及条件难以完全解释其复杂的成因。 另外，针对实验熔体和华北北缘埃达克质岩石之间的一些差异，不排除可能同时存在其他与之类似的源岩，成分上具有相对富Mg、Ca而贫Fe、Al，以及不同程度的Th、U、Zr、Hf富集等特征，与斜长角闪岩一起部分熔融，共同形成中生代华北北缘的中酸性埃达克质岩石。

稀土对红细胞及带3蛋白胞质片段结构和生理功能的影响

稀土在农业和医学中的广泛应用使人们日益关心稀土的安全性问题。本论文以红细胞为研究对象，围绕稀土对红细胞形态的影响，稀土能否进入红细胞以及稀土对红细胞带3蛋白胞质片段结构和功能的影响三方面开展研究工作，主要研究成果如下：首先，在宏观上通过超高倍光学显微镜观察了稀土阳离子及其络阴离子对正常人红细胞形态的影响。结果表明当红细胞与硝酸悯作用后其体积发生膨胀，表面出现棘状凸起，细胞间发生聚集。而以往被人们认为毒性较小的柠檬酸悯则使红细胞呈现囊泡状凸起，随着与稀土作用时间的延长多数囊泡状结构可脱落。EDTA的加入可使部分在低浓度（10~(-7)M）稀土离子条件下变形的红细胞恢复原状，说明细胞形态变化主要是由环境中稀土的存在引起的。其次，根据稀土离子跨膜研究中存在的一些问题，在总结前人工作的基础上，建立一种方法测定了体外温育和静脉注射条件下红细胞中稀土含量。进一步证实文献报道含有络合剂的洗涤缓冲液能够将进入细胞内部的稀土带出，影响测定结果的准确性。本论文中应用不含络合剂的洗涤缓冲液洗涤与稀土温育后的红细胞，在10mMTris-HCl印H7.0）低渗缓冲液中溶胀，ICP-MS测定结果显示无论是稀土阳离子还是稀土络阴离子均可以跨膜，且稀土络阴离子跨膜速度较快。耳静脉注射稀土后仅在兔血浆及红细胞膜上检测到稀土，说明在短期静脉注射条件下存在于血浆中的稀土不能进入兔红细胞。最后，应用基因工程技术克隆、表达、纯化了带3蛋白胞质片段及其融合蛋白。计算机结构模拟、荧光光谱以及生物活性的测定证实重组带3蛋白胞质片段与天然蛋白具有相似的空间结构和生物活性。稀土离子对醛缩酶、醛缩酶与带3蛋白胞质片段相互作用的影响表现为：0-10μMLa~(3+) 对醛缩酶活性有促进作用，当体系中L~(3+)浓度达到6μM时，带3蛋白胞质片段基本完全失去对醛缩酶活性的抑制作用。蛋白质内源荧光和同步荧光光谱研究结果表明，La~(3+)对带3蛋白胞质片段与醛缩酶结构均具有一定影响。本论文实验结果表明，低浓度稀土可导致调节细胞内糖酵解速率的带3蛋白胞质片段失去活性，使糖酵解速率无序增强。由于红细胞主要碳源来自于血糖，糖酵解速率的加快很可能会引起生物体血糖浓度的降低。

Evaluation and application of micro-sampling system for inductively coupled plasma mass spectrometry

Two Meinhard microconcentric nebulizers, model AR30-07-FM02 and AR 30-07-FM005, were employed as a self-installed micro-sampling system for inductively coupled plasma-mass spectrometry (ICP-MS). The FM02 nebulizer at 22 muL/min of solution uptake rate gave the relative standard deviations of 7.6%, 3.0%, 2.7%, 1.8% for determinations (n = 10) of 20 mug/L Be, Co, In and Bi, respectively, and the detection limits (3s) of 0.14, 0.10, 0.02 and 0.01 mug/L for Be, Co In and Bi, respectively. The mass intensity of In-115 obtained by this micro-sampling system was 60% of that by conventional pneumatic nebulizer system at 1.3 mL/min. The analytical results for La, Ce, Pr and Nd in 20 muL Wistar rat amniotic fluid obtained by the present micro-sampling system were precisely in good agreement with those obtained using conventional pneumatic nebulization system.

Species of rare earth in rat liver

The metabolic accumulation and species of rare earth in rat liver were investigated by ICP-MS and chromatography after the rats were fed by a low dose of mixed rare earth for a long time or the administration of a high dose of lanthanum for a short time. It was found that the content of rare earth in the liver increased with the arising of dose of drug delivery. Their accumulation rate was different, for example, La>Ce>Nd>Pr. The protein which could combine,with rare earth specially were not gotten through chromatography. It was suggested that rare earth could bind to many proteins voluntarily, such as some important enzymes and it might be separated from the combined proteins under certain conditions.

电感耦合等离子体质谱的微量进样系统分析性能评价及其应用

用2种微量雾化器组装成微量进样系统与常规气动雾化方式的ICP MS的分析性能作了详细比较。FM0 2雾化器在22μL min低提升率下,20μg L的Be、Co、In和Bi进行10次平行测定的RSD分别为7.6%、30%、2.7%和1.8%;检出限分别为0.14、0.10、0.02和0.01μg L;115In的信号强度达到常规气动雾化器1.3mL min提升速率下的60%,显示了良好的分析性能。对20μLWistar鼠的羊水样品中La、Ce、Pr和Nd4种元素的测定结果与常规进样系统的结果完全吻合

稀土在鼠肝中的物种分布

采用 ICP-MS、微量蛋白层析分离技术 ,研究了长时间、低剂量混合稀土及短时间、高剂量硝酸镧分别对大鼠及小鼠作用后 ,稀土在鼠肝中的代谢累积及其物种分布 .结果表明 ,鼠肝中各稀土含量随给药剂量的增加而增大 ,其累积速度大小顺序为 La>Ce>Nd>Pr;经柱层析分离未得到与稀土特异结合的鼠肝蛋白 ;稀土可与多种鼠肝蛋白 (包括多种重要的酶 )结合 ,在一定条件下 ,稀土与其结合蛋白可发生解离

Species of lanthanum in Wistar rat liver

The metabolic accumulation and species of lanthanum in Wistar rat liver were investigated by ICP-MS, gel exclusion chromatography and ultrafiltration after the rats were fed by low dose of lanthanum for a long time. It was found that the content of La in the liver increased regularly with arise of dose and time of drug delivery. After the administration was stopped for a certain time a part of lanthanum in the liver Tvas metabolized, but;the metabolic rate was very slow, The lanthanum in rat liver was distributed in the soluble protein with molecular weight: of more than 60000 mostly. Rare Earth existed in the six elution peaks separated by Sephacryl S-200. The amount of lanthanum in the first elution fraction is the largest, which was 88 percent in the whole content of lanthanum in proteins with molecular weight more than 60000.

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.