Effects of retrograde-zoning of garnet on Sm-Nd isotopic dating of eclogite and oxygen isotopic disequilibrium between eclogitic minerals

The compositional zoning of the garnet in a strongly deformed eclogite from Raobazhaifoliated peridotite has been recognized. The CaO concentrations of the garnet are decreased fromthe core to the rim, while its MnO concentrations are increased, suggesting the retrograde origin ofsuch CaO-MnO zoning. The tie line of garnet+omphacite from this eclogite gives a Sm-Nd ageof (187±5) Ma, which is less significant than the Sm-Nd ages of (221±5)-(228±3) Ma and (210±6)-(214±6) Ma for ultrahigh-pressure eclogites in the southern Dabie zone and in the northernDabie zone, respectively. This younger Sm-Nd age could result from the ~(143)Nd/~(144)Nd ratio decreaseof the retrograde zone in the garnet. The δ~(80)O values of the garnet and omphacite show that theirfractionation values are less than the equilibrium fractionation value between the garnet and om-phacite at 500-900℃, which suggests an oxygen isotopic disequilibrium between them.     

Chronology and origin of Au-Cu deposits related to Paleozoic intracontinental rifting in West Tianshan Mountains, NW China

Located between the Tarim platform and Junggar massif, the West Tianshan intraconti-nental rift abuts against the China-Kazakhstan boundary in the west part, borders on the Yilianha-bierga late Paleozoic relic ocean basin and the South Tianshan late Paleozoic ocean basin re-spectively in the northeast separated by the Aibi Lake fault and in the southeast by the fault alongthe southern margin of the Yili massif. During the development and after the close of the WestTianshan intracontinental rifting in the Carboniferous-Permian period, a series of nonferrous andprecious metal mineralizations occurred with the Au-Cu deposits being the most important. Isotopicchronologic study of representative deposits of different types shows that gold-copper mineraliza-tion in the West Tianshan intracontinental rift zone mainly happened during the middle-late Her-cynian Period, among which the Axi volcanic hydrothermal type gold deposit was formed duringthe Carboniferous with a fluid inclusion Rb-Sr isochron age of (339 ± 28) Ma; the Qiabukanzhuotaquartzolite type gold deposit has a Rb-Sr isochron age of (312 ± 46) Ma; the Tawuerbieke por-phyry type gold deposit has a Rb-Sr isochron age of (295 ± 16) Ma; the Jingbulak magmatic liqua-tion Cu-Ni deposit and the Musizaote porphyry type Cu deposit have the forming ages of 300 Ma ±and 250 Ma±, respectively. Analyses of crustal evolution and metallogenetic geological back-grounds of Au-Cu mineralizations in the studied area shows a close correlation with the rifting.     

TECTONIC FRAMEWORK OF THE CONTINENTAL BASEMENT OF SOUTHEAST CHINA

The chronology and tectonic evolution model of the continental basement in southeast China margin is an important debatable geological subject. The Cathaysia is shown in this paper to be in accordance with many geological facts and also with the age data obtained by multi-dating method. Its age has been determined to range from 900 to 2000 Ma. The age of the unconformity plane in the Cathaysia is 1400 Ma. The collision and suture between the Jiangnan oldland and the Cathaysia took place during the early Jinning Period. Toward Jiangxi, Hunan, Guangdong and Guangxi, these two continents gradually opened to form a residual oceanic basin. The sedimentation centre of the basin continuously migrated southwestward from the Jinning through the Caledonian Period, and finally closed in the Guangxi Movement and Dongwu Movement. The drift-rotation of the Cathaysia after the Jinning Period has been inferred.     

THE NUCLEAR TRACK DEPTH PROFILE OF THE JILIN METEORITE

Using 43 documented drill core samples of the H_5-chondrite "Jilin" the depth profile of GCR-and fission track densities was established. The track profile essentially reflects the GCR-track record of the second (4π-) irradiation stage of "Jilin". Relics of the track record of the first (2π-) exposure are indicated by a deviation from the theoretical depth profile of the 4π-exposure. No Pu-244 fission is observed ia the fission track background near the meteorite center. The atmospheric ablation thickness of the two drill cores A and B normal and parallel to the assumed surface of the "Jilin" parent body was found to be 11±4 cm, respectively. A minimum shielding depth of the "top" part of core A during the 2π-exposure is estimated to be～30 cm. Near surface deviations of the experimental track data from theory are ascribed to a short-term moderate heating event (equivalent to 24h,～370℃) no more than 0.4 Ma ago. The resulting partial track annealing in a surface layer of ～15—20 cm thickness of t     

Unroofing around Qaidam Basin of northern Tibet at 30 Ma: constraints from ~(40)Ar/~(39)Ar and FT thermochronology on granitoids

An ~(40)Ar/~(39)Ar and fission track thermochronological study has been carried out on threesuites of granitoids collected along the northern and southern edges of the Qaidam Basin to betterconstrain the mechanisms accommodating the India-Asia collision around the Qaidam Basin(northern Tibet), in order to understand the evolution of the entire deformation area. Mica andK-feldspar have been analyzed and the cooling histories of the latter have been modeled. Thecooling histories based upon K-feldspar modeling and fission track ages show that samples simul-taneously recorded an important cooling event (7.5-10.7℃/Ma) around 30 Ma, which is thoughtto reflect an increase of denudation rate related to the tectonic activity in this area associated withuplift suggesting significant crustal thickening starting around 30 Ma in this area. The estimatedsedimentation rate in the Qaidam Basin, the propagation rate along the Altyn Tagh fault and fieldobservations support this deduction.     

FISSION TRACK AGES AND UPLIFT RATES OF THE SOUTH XIZANG (TIBET) REGION

The geological ages of Lhasa, Kangmar and Gaowu rock bodies of Xizang (Tibet) have been determined by fission track method. The results are: 25.5—27.2, 10.7—11.5, 8.06—9.19 Ma respectively. It is found that the fission track (FT) age of apatite increases with the elevation of sample. Calculated by the ages-topographic altitude method, the uplift rates of the above three rock bodies are 0.25, 0.45, and 0.49 mm/a respectively. On the basis of the fission track age and the published isotopic age data, the uplift rates of other regions have been calculated by the mineral pair-blocking temperatures method. The lowest is 0.08 mm/a and the highest 2.4 mm/a. We found that the uplift rates of different regions in the same period are distinet, and the uplift rates of different geological times in the same region also are not alike. This situation shows that the Xizang region has a complex geological and unroofing history due to the collision of the India and Eurasian plates.     

Fossil Sm-Nd Isotopic Dating of the Precambrian-Cambrian Boundary in the Meishucun Section, Jinning, Yunnan, China

It was for the first time that the fossil Sm-Nd isochron method was used to date the Precambrian-Cambrian boundary. The samples were collected from the Zhongyicun Member in the Meishucun section of Jinning County,Yunnan Province, southern China. The date of 562.8±7.9Ma B.P. was obtained from four hyolithid fossil samples; another date of 562.1±5.7Ma B.P. was provided by four hyolithid fossil samples and two collophanite samples. These figures suggest that the Precambrian-Cambrian boundary reference point A, which is slightly below the Zhongyicun Member, might be about 570Ma old, and the reference point B, which is near the top of the Zhongyicun Member, could be approximately 560Ma in age. This result contributed valuable reference to precise calibration of the base of the Cambrian System in the global geological time scale.     

THE SYNTHETIC ATTEMPT OF(±)-MALABARIC ACID AND(±)-ANISOMELOL——SYNTHE S IS OF PRECURSORS FOR(+)-MALABARIC ACID AND(±)-ANIOSMELOL

The precursors I(R′=CH_2OTHP,or CO_2Et)for(±)-Malabaric acid(1)and(±)-Anisomelol(2)were synthesized from geraniol 3 and homogeranyl iodide 5(2,6-dimetyl-9-iodo-2,6E-nonadiene)via Wadsworth-Emmons condensation and allylic regioselective chlorination.     

THE ATOMIC WEIGHT OF ANTIMONY

With enriched antimony isotopes of 99.224 atom% ~(121)Sb and 99.528 atom% ~(123)Sb, twotracer solutions were prepared, whose antimony content was ascertained by the isotopicdilution analysis utilizing an accurately assayed laboratory standard. Mass spectrometricmeasurements were made on a Finnigan MAT- 261 instrument to find the ratio of masses121 and 123. Five synthetic mixtures formed from the tracers served to determine thecorrection factor of mass discrimination. The isotopic abundances thus found for the anti-mony in the mineral stibnite together with the known nuclidic masses yield an accurateatomic weight of antimony as 121 .7575± 0 .0009.     

THE CRYSTAL STRUCTURE OF THE ADDITION COMPOUND OF SODIUM TETRAHYDROGEN DECAVANADATE AND HEXAMETHYLENETETRAMINE

The title compound crystallizes in the space group C_i~1-Pī with cell constants a=9.589, b=10.486, c=11.139, α=103.27° β=98.20° and γ=103.16°. After deriving the position parameters of all V atoms by Patterson method, the coordiuates of all the non-hydrogen and hydrogen atoms were obtained from successive Fourier and difference syntheses, and the leastsquares refinement for all atoms gave a final discrepancy factor R=0.0279. The chemical content within a unit cell has been identified definitely as (Na~+)_2·(H_2V_(10)O_(28)~(4-))·2((CH_2)_6N_3N-H~+)·8H_2O.     

STRATIGRAPHIC AND GEOCHRONOLOGIC ANALYSES OF THE QUATERNARY DEPOSITS IN THE THREE-LAKE REGION OF QAIDAM BASIN

The Qaidam Basin is a larger sedimentary basin in western China where the thickness of the Quaternary deposits is in the range of 2000-3000 m at its subsiding center. This paper first dates palaeomagnetically the cores obtained from the five continuously sampled intervals and those from a typical profile, determineds the age of the index fossil zones, and calculates the deposition rates for the varve deposits based on the sedimentological analysis. As a result, we can calculate the ages of the various characteristic beds (including fossil zones, seismic reflection beds, and marker layers of electrical properties) for any given borehole-section when it was divided into facies, and check the validity of the chronology. According to all those studies, the stratigraphic and geochronologic analysis program of the Quaternary deposits in the Qaidam Basin has permitted a detailed discussion to be made in this paper.     

EVALUATING THE WATER RESOURCE IMPACTS OF CLIMATIC WARMING IN COLD ALPINE REGIONS BY THE WATER BALANCE MODEL: MODELING THE URUMQI RIVER BASIN

In view of the tendency of global climatic warming, the water balance model is employed to estimate the runoff changes in the Urumqi River Basin, Xinjiang Region, China, under ten climate change scenarios, which are combinations of temperature increases by 2K and 4K with precipitation change of 0, ±10% and ±20%, respectively, as the atmospheric concentration of carbon dioxide increases. The results suggest that runoff changes mainly depend on the precipitation change in the glacier-free or less glacierized basins in cold alpine regions. Effect of temperature on runoff becomes marked gradually with the increase in precipitation. Runoff from glacierized areas, however, is much more sensitive to the temperature change.     

CHEMILUMINESCENCE STUDY OF THE BEAM-GAS REACTIONS Ba(~3D),Ba(~1S) Cl_2,I_2 UNDER THE SINGLE COLLISION CONDITIONS

The chemiluminescence (GL) reactions of metastable and ground state Ba atoms (Ba(~3D),Ba(~1S)) with Cl_2,I_2 have been studied under single collision conditions. It is found that thereaction Ba(~3D) Cl_2 does not produce the emission continuum from BaCl_2 but enhances theemission from BaCl, especially the emission from BaCl C~2Πstate. The total collision crosssections for Ba atom removal by Cl_2 are determined to be 65±5A_2 for Ba(~1S) atom and 105±5A_2 for Ba (~3D) atom, respectively. This result is in agreement with the result calculatedby electron harpooning model. The higher resolution CL spectrum of Pal (C_2Π_(3/2)-X~2∑~ )△v =0 band produced by Ba(~3D) I_2 reaction is also obtained. From an approximate calculation,it is found that the vibrational population of the BaI (C~2Π_(3/2)) state has a non-statistical dis-tribution. By the extended harpooning model, the experimental results have qualitatively beenexplained.     

Magmatism and deformation times of the Xidatan rock series, East Kunlun Mountains

The Xidatan rock series consist of mylonite, gneiss and granite. The U-Pb age showsthat the granite was formed at 206 Ma, and the ~(40)Ar/~(39)Ar ages of the biotite display that the my-lonite was formed at 145 Ma when the Xidatan ductile shear zone occurred. At about 110-100 Mathe Xidatan Fault reactivated again. As a result, the biotite and muscovite of Xidatan rock seriesopened their argon isotope system.     

DETERMINATION OF SOLUBILITY OF Fe_2O_3 IN DILUTE AQUEOUS SOLUTIONS AT 300℃ AND 10 MPa——APPENDING A DISCUSSION ABOUT THE TRANSPORTING FORM OF IRON IN HYDROTHERMAL SOLUTIONS

The solubility of Fe_2O_3 in dilute KOH and HClO_4 aqueous solutions was determined at 300℃ and 10 MPa. The analysis of the solubility data indicated that in neutral and alkaline hydrothermal solutions iron mostly existed as Fe(OH)_3~0 and Fe(OH)_4~-, and it was calculated that △G_(Fe(OH)_3~0)~0=-561.9±3.3kJ/mol, and △G_(Fe(OH)_4~0)~0=-662.7±5.0 kJ/mol at 300℃. According to the analysis on the previous experimental studies about the transporting form of iron, the existing form of iron in hydrothermal solutions is discussed in this paper.     

NUCLEAR TRANSPLANTATION IN TELEOSTS——HYBRID FISH FROM THE NUCLEUS OF CRUCIAN AND THE CYTOPLASM OF CARP

Hybrid fish are obtained from the combination of nucleus and cytoplasm from two generaof fresh-water teleosts using the technique of nuelear transplantation (i.e. the combination ofthe nucleus of erueian (Carassius auratus) and the cytoplasm of carp (Cyprinus carpio)). Morphological characteristics of these hybrid fish that have been examined so far indicatethat some features such as barbs, pharyngeal teeth, the number of scales along the lateral line,and the number of vertebrae are similar to those of crucian. Some of the hybrid fish growto normal adult fish.     

STUDIES ON THE STRUCTURE OF FORKED CONJUGATIVE SYSTEMS——THE CRYSTAL STRUCTURE AND CONFORMATION OF 2-BENZOYLTHIOPHENE

The crystal structure and the conformational properties of the title compound have been investigated by means of X-ray single diffraction and the PCILO methods. C_(11)H_8OS belongs to the orthorhombic system, the space group is P2_12_12_1, a=11.945(4), b 10.236(7), c=7.649(4), Z=4, D_c-1.37g/cm~3. The molecule is not planar structure because of steric hindrance. The thiophene ring and the phenyl ring make dihedral angles of 21°(θ_1) and 32°(θ_2) with the carbonyl frame plane, respectively. The lowestenergy conformation obtained by PCILO calculation is in agreement with the crystallinestatc conformation. In this paper, the molecular structure, the influence of steric hindrance and the groups' abilities to conjugate upon the conformation and the variations of the potential energy of the isolated molecule in the whole conformational space are discussed.     

KINETIC STUDIES OF HAEMOPOIETIC PROGENITOR CELLS (CFU-C) AND T-LYMPHOCYTES IN THE LIVER OF HUMAN FOETUS

In the development of human foetus. liver is an important haemopoietic organ. Wehave determined the liver weight and total hepatic nucleated cells from 24 foetuses on the onehand, and CFU-C yield, total number of CFU-C and T-lymphocytes in liver from 22 foetuses ofdifferent ages on the other. From the kinetic observations through the early developmental period of the foetuses. themaximum yield of CFU-C or the total numer of CFU-C in the liver occurs at 4--5 months ofgestation; during the first 5 months of gestation the percentage of T-lymphocytes in the liveris about 1--2%.     

MICROENVIRONMENTAL EFFECTS OF THE HELICAL CONFORMATIONS OF AMYLOSE AND ITS DERIVATIVES——THE FORMATION OF INCLUSION COMPLEXES WITH A SUBSTRATE BY AMYLOSE IN THE DMSO-H_2O MIXED-SOLVENT SYSTEM

The conformational behavior of amylose and the formation of helical inclusion complexesof amylose with a substrate, N-ethyl-4-hexadecyloxycarbonyl pyridinium iodide (1) -- asolvent-polarity probe, have been investigated in the DMSO--H_2O mixed-solvent system bymeans of surface tension, viscosity, UV, electrical conductance and ORD measurements. Thedecrease of the volume-fraction of DMSO, Φ_(DMSO) of the mixed-solvent system inducesconformational changes of the amylose from tight helices to loose and extended helicesinterrupted by short disordered regions. Such a transition is accompanied by abrupt changesof the viscosity and ORD curves. The mechanism of interaction between amylose and the substrate 1 also depends on thesolvent composition. When Φ_(DMSO) is larger than 0.70, the interaction of amylose with 1is apparently similar to those cases in which superhelices are formed between a macromo-lecule and some azo dyes; the latter are known to be bound exteriorly around the macro-molecular helices by oriented association. However, when Φ_(DMSO) begins to drop below0.70, the substrate molecules start to be bound in the helical cavities of the host and thussupramolecular inclusion complexes are formed. At Φ_(DMSO)<0.70, ORD shows a new nega-tive Cotton peak at a wavelength which coincides with the λ_(max) of 1 (276 nm). This implicatesinduced asymmetry for the achiral substrate 1 in a chiral microenvironment. Intrinsicdissociation constants (K_(d~*)) for the inclusion complexes can be obtained from the surface ten-sion- substrate concentration (σ-[1]) curves and the largest number of binding sites isfound to be below 30. The K_(d~*) values decrease with decreasing Φ_(DMSO), apparently inagreement with the results from conductance measurements. Presumably, the driving forcefor the transfer of the substrate molecules from the solvent-mixture bulk phase to the non-polar cavities of the host molecules comes from hydrophobic-lipophilic interactions.     

利用络合物形成曲线设计金属络合物体系模型及优化络合物稳定常数

In this paper the Bi(Ⅲ)-ligand(pyridine-2-carboxylic acid) system was studied by direct current sampled polarography (DC_TAST) at a fixed ratio of total-ligand to total-metal concentration and changing pH. The po-larographic experimental complex formation curve (ECFC) and the theoretical complex formation curve (TCFC) were used for modelling the metal-ligand system and optimizing stability constants. The ECFC， in which experi-mental parameters of polarography are included (a shift in a half-wave potential and a variation in a diffusion controlled limiting current)， appears to be a characteristic function for a particular metal-ligand system. The TCFC is a theoretical curve calculated for the designed metal-ligand model from mass-balance equation. Five bismuth complexes MHL， ML， ML₂， ML₃ and ML₃(OH) with their stability constants as logβ 7.54±0.10， 7.50±0.02， 13.91±0.04， 18.15±0.03 and 26.75±0.02， respectively， are reported.