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    30 September 1992, Volume 4 Issue 3 Previous Issue    Next Issue

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    INSPIRATION FROM STUDY OF ANTARCTIC METEORITES I: PETROLOGIC AND COMPOSITIONAL EVIDENCES FOR EARLY CONTINUOUS CHEMICAL FRACTIONATION OF THE SOLAR NEBULA
    1992, 4 (3):  1-15. 
    Abstract ( 1407 )   PDF (651KB) ( 1459 )  

    Bulk concentrations of Ir,Os,Co and the other siderophile elements of metal phase in chondrites increase significantly with degree of oxidation,Which,together with Co-Content of kamacite and Fa-content of olivine,reveal a continuous trend of variation of redox among chondrites.Intermediate groups of E/H,H/L,L/LL,and LL/C,lying between E and H,H and L,L and LL,LL and C,respectively,are proposed based on Co-content of kamacite,Fa-content of olivine,Fs-content of low Ca pyroxene,bulk concentrations of Ir,Os and Co of the metal phase and other criteria of classification.The discovery of intermediate groups increases the number of groups of chondrites from 9 to 13.Both the variation of redox among chondrites and the existence of intermediate groups of chondrites suggest a continuous chemical fractionation in the primordial solar nebula.

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    EVIDENCES OF SM-ND AND RB-SR ISOTOPES AND TRACE ELEMENT FOR LATE CRETACEOUS VOLCANIC ROCKS FROM DEPLETED MANTLE SOURCE IN KING GEORGE ISLAND,ANTARCTICA
    1992, 4 (3):  16-30. 
    Abstract ( 1713 )   PDF (675KB) ( 1444 )  

    Twelve tuffite samples dealt with in the present paper were collected by the 4th Chinese Antarctic Expedition(1987-1988) from Upper Cretaceous Half Point Formation on the southeast edge of Fildes Peninsula,King George Island(Shen,1991,1992)(Fig.1). The samples were decomposed in Teflon bombs.Rb, Sr and REE were separated from major elements with cation column. Total chemical blanks for Nd and Sr are <5-7×10 -11 g/g and < 2×10 -9 g/g respectively. The isotopes of Rb, Sm and Nd were measured through the VG354 mass specrtometer in Modern Analytical Center. Nd and Sr isotopic ratios take 146 Nd/ 142 Nd=0.636151 and 86 Sr/ 88 Sr =0.1194 as the normalized values respectively. The 87 Sr/ 86 Sr ratio determined in the center is 0.71022±4(2δ). 143 Nd/ 144 Nd ration determined by USGSBCR-1 is 0.51187. 87 Sr/ 86 Sr ratio determined by NBS 607 is 1.20014+10(2δ). The isotopic analysis of Rb, Sr, Sm and Nd leads to the results as shown in Table 1,2, The Rb-Sr isochron of 12 whole rock samples gives t=71.3±0.3 Ma, I=0.70314 and R=0.99998(Fig.2).The ε Sr (T) and ε Nd (T) values range from -17.9 to -18.2 and +6.04 to +6.66 respectively; the f Rb/Sr and f Sm/Nd from-0.76 to +9.59 and -0.265 to -0.303; the ε Sr (0) and ε Nd (0) from -6.64 to -18.9 and +5.53 to +6.15 respectively. The Sm-Nd model age (T Nd DM ) range from 409.3Ma to 471.1Ma. A good linearity (R) of Rb-Sr isotopic isochron revealed as figure 2 and the identity of ( 87 Sr/ 86 Sr) i values shown in table 3 of these sampkes reflect the homogenization of Sr isotope of the source region. Thus, the value of 71.33±0.3Ma by Rb-Sr whoke-rock isochron is adopted as the crystallization age of the rocks or as the age of the volcanic eruption. As shown in the figure 6,the samples have higher 143 Nd/ 144 Nd (0.512922-0.512954),lower 87 Sr/ 86 Sr (0.70318-0.703320) and slight negative 143 Nd/ 144 Nd- 87 Sr/ 86 Sr relations which fall in the typical range of oceanic island basalts or in the vicinity of the boundary between MORB and other oceanic island basalts. Covariance of Al 2O 3/ TFe 2O 3 ratio, TiO 2(wt%) content and Th(ppm) content with 87 Sr/ 86 Sr suggest that these volcanic rocks were contaminated by a litte or no crustal components.The low ( 87 Sr/ 86 Sr) i ration are not attributed to the result of seawater rock interaction and indicate that the samples belong to the continental origin tather than the marine facies ones. The average T Nd DM of the samples is 444.3±20.6Ma, obviously older than Rb-Sr age, which reflects crust-mantle mixed or the crustal preserved age and indicated the possibilities of the existence of lower Palaeozoic basement.The high content of the Al 2O 3 in the rocks may be closely related to the degrees of lipuation of the mantle. MgO has a positive correlation with some incmpatible elements and has as Pb,Sr,Li,Nb and Hf a negative correlation with Y, Th, Ta, U, Zr and Br reflecting the relation of the continued evolution of the magmas. The different geochemical features and the diagrams to determine the structural environment indicat that the samples consist mainly of calc-alkaline basalts (CAB) which belong to the volcanic are basalts erupting from the convergent plate margin. Therefore, the volcanic rocks of the Half Three Point Formation were formed from the mantle-derived magmas during the island are volcanic activities.

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    THE ELEMENTAL GEOCHEMICAL CHARACTERISTICS OF LATE QUATERNARY OF YANWO LAKE CORE FROM THE GREAT WALL STATION,KING GEORGE ISLAND,ANTARCTICA
    1992, 4 (3):  31-37. 
    Abstract ( 1345 )   PDF (178KB) ( 1161 )  

    The Yanwo Lake,situated in King George Island at 62°13′14″S and 58°57′38″W .It is important to study the elemental and environmntal geochemistry of this region. Reported in this paper are the contents, distribution,statical values,relative rich coefficients,interrelated matrix of elements in the late Quaternart sediments of Yanwo Lake Core from the Great Wall Station, King George Island. The results show that the sediments in Yanwo Lake Core:the lam (clayey soil) is highly rich in Cs,As Ba,and poor in Cr, Hf; the sand is highly rich in Ni, Zn,Au,Sr and poor in Ta, Zn, E; the gravel is highly rich in Rb and poor Fe, Cs, Yh, As, Ba. The relative rich coefficients of the elements in Yanwo Lake core with earth crust, sedimentary rock and loess are show that the K, Rb, Cs, Ya, Hf, U, Th, Zn, Sr, Ba have great movable ability; Na, Fe, Co, Zr, Sc, As have medial movable ability; Ni, Mo, Au, have weak movable ability. The interrelated matrix of elements in sediments of Yanwo Lake Core is show that between Na and Zn; Mo and Cr, As;Co and Sc, Mo, AS; Sc and Cs, Mo, AS; Fe and Co, SC, Mo, AS are extremely clear relations, and between Na and As; Rb andFe, Co, Sc, Mo are negatively clear relative.

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    RESEARCH ON THE BENTHIC ECOLOGY ENVIRONMENT,ANT- ARCTIC OCEAN:I.MAXWELL BAY AND ADMIRALTY BAY
    1992, 4 (3):  38-45. 
    Abstract ( 1492 )   PDF (389KB) ( 1138 )  

    The information on benthic organisms and the geochemical environment obtained from the Chinese First Exploration on Antarctic Ocean and its succeeded analytic works.The results shows that in the circumstances of the studied area in which the bottom water is plentiful in dissolved oxygen and the surface sediments is in weak oxidation(manganese oxides as dominated oxident) ,benthic organisms grow well while the prosperity of the animals are limited below5-1 0 cm of the profiles in which the environment is controlled by sulfate reducing reaction. It is the result of evolution for the characteristics of the main benthic organisms under the special circumstance in studied area.On the condition of low temperature of the Antarctic Ocean,the solubility of carbonates is higher than that in otherocean's,but the concentration of calcium in overlying water and porewater is not higher than that in other ocean,which may results in the difficulty forthe crustacean and molluscs to obtain sufficient calcium to form their solid crust.Furthermore,there is a certain relation between the amount of sedentary polychaetes and the temperature in overlying waters. That might demonstrate that the animals had still not quite adjusted to the extremly cool of the Antarctic Ocean,however it should be left for furtherwork.Besides,the research proposed thatthe number of the microorganisms is controlled by the amountof active organic matters in the sediments.

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    DETERMINATION OF LOW MOLECULAR VOLATILE FATTY ACIDS BY PHLC IN COLD WATER ENVIRONMENT IN ANTARCTICA
    1992, 4 (3):  46-51. 
    Abstract ( 1301 )   PDF (325KB) ( 1218 )  

    A determinative method of low molecular volatioe fatty acids was been reported in this paper, It was shown that PHLC is applicable to measuring the concentrations of low molecular fatty scids in cold water environment in antarctica. This method has some specialitys such as accuracy; high sensitvity; easy and quicker with operation and a little samples are only required to used determination. The lowest limitation of determination for this method is 0.001μg/ml for acrylic acid and 0.1μg/ml for other volatile fatty acids. The results of determination shown that the concentration of acrylic acid is 0.004-0.042μg/ml through 60m depth in antarctic coast warter in 3 January 1989 and other volatile fatty acids are 0.1-1.0μg/ml.

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    OBSERVATION AND STUDY ON THE MICROCLIMATE OF THE MOSS VEGETATION IN THE KING GEORGE ISLAND
    1992, 4 (3):  52-57. 
    Abstract ( 1263 )   PDF (137KB) ( 1087 )  

    During the summer Fed.1-10,1989,in the Fildes Peninsula,King George Island, Antarctica,by using a primary observation date set of microclimate in the mossy area near the Great Wall Station(GWS).A number of microclimate observational facts in the mossy area were revealed. Some interesting results from the comparison of microclimate feature between the mossy area and the GWS were analysed.

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    MODERN INFORMATION TECHNOLOGY AND MODERN ANTARCTIC RESEARCH
    1992, 4 (3):  58-72. 
    Abstract ( 1408 )   PDF (478KB) ( 1086 )  

    The exploitation of Antarctic information is a meaningful research work. Since an environment supported by networks and open systems are prerequisite for the sharing of information resources, the powerful modern information technology is the only way which we can rely on to ensure the prompt communications among people, organizations and nations. This thesis surveyed the present and future of Antarctic research from the view of soft science and system science, using modern information technique, focusing on both the support to the former provided by the latter and the importance of omnibearing prospect with regards to grand science. A special field most relying on international cooperation , current Antarctic research will surely make use of modern information techniques systematicly to support it in taking part in the research of many large-scale issues concerning the world, while it works on the subjects of developing the scientific characteristics and global influence of Antarctica. At present, data bases on many subjects have been established and it has become an urgent problem which need to be solved that how to share efficiently the data in them to ensure the prompt international information transfer and exchange, and to promote the worldwide work to a more systemized extent with networking and operation under related international stardards. It is the requirement and tendency for developing the whole research work on Antarctica to exploit available information resources more in quantity, speed and quality and to set up an open environment that is synchronous with the development of international Antarctic research. The task of soft sciene in Antarctic research is to solve the problem of the coordination among components of a system. It should be developed with large-scale rime and space scopes such as development of science, social effect, tendency of development and plans for long-period opoeration of large system and so on, in order to probe the flexible combination of various aspects under a general principle. It needs not only interdisciplinary coordination but also the flexible combination of scientific research and management. Information processing depends on not large quantity but value of the information. The information exchange engages in not only simple data and bibliography exchange but also prompt sharing of information to make best choices. Therefore, it is necessary to establish a realistic information system which can quickly reflect the most recent dynamics in Antarctic research in order to react rapidly to the general trends concerning Antarctica in world science to adapt to the situation in various periods. Development of Antarctic information system is bound to the consideration of the utilization of information from other systems as well as offering others its own information. To establish a computerized Antarctic information system is a step necessary to implement scientific management and decision-making, to improve the ablity on Antarctic research and operations; it is essential for joining international Antarctic information networks; also it is an important step deepen modern Antarctic research. It need continuous effortswhich develop dynamically with optimization to implement this comprehensive system engineering project.

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