Loading...

Archive

    30 June 1997, Volume 9 Issue 2 Previous Issue    Next Issue

    Contents
    For Selected: Toggle Thumbnails
    Contents
    CHEMICAL CHARACTERISTICS OF SUMMER PRECIPITATION AT POINT BARROW,ARCTIC ALASKA
    1997, 9 (2):  4-11. 
    Abstract ( 1239 )   PDF (413KB) ( 1208 )  

    Over 20 precipitation samples at Point Barrow,Alaska in Aug. and Sep. of 1994 was analysised.The pH value is between 4.76-6.26,of which higher in summer than in winter.The electic conductivities in precipitation is rather low,varing between 4.9-102.0 μS/cm,and the abnormal high values are concerned with the sea salt.The chemical composition of precipitation at Point Barrow,Alaska have equal level to that at the other Arctic regions and on the Qinghai Xizang Plateau.The extremely low value of exSO 2- 4 indicates that the anthropogenic effect on this region is small.Point Barrow is one of the most suitable places for studying the Arctic environment conditions.

    Related Articles | Metrics
    SURFACE TEXTURES OF QUARTZ GRAINS FROM A CORE OF THE ANTARCTIC PRYDZ BAY
    1997, 9 (2):  12-25. 
    Abstract ( 1275 )   PDF (2027KB) ( 1434 )  

    Aquantitatively statistical analysis about the shapes and surface textures of quartz grains from 13 level samples of a core (NP951) collected from a continental slope in the Antarctic Prydz Bay were made in this study.The quartz grains show surface textures resulted from a strong glacial movement and a weaker chemical erosion precipitation,indicating the sediments are mainly glacial drifts under a lower energy marine environment.The obtainted quantitatively statistical results of the assemblages of the quartz grain surface textures formed by the chemical erosion precipitation are well correlated to the analytical results of mineral X ray diffraction and micropaleontology and can better explain the changes of sedimentary environment and paleoclimate which the marine zone concerned underwent.

    Related Articles | Metrics
    SILICA OXYGEN ISOTOPE OF DIATOM FROM CORE PC 10 IN THE BRANSFIELD STRAIT,ANTARCTICA
    1997, 9 (2):  26-32. 
    Abstract ( 1441 )   PDF (185KB) ( 1402 )  

    Fiftyone diatom samples taken from the piston core PC10 in the Bransfield Strait of West Antarctica were engaged in oxygen isotope analysis. Among them 49 samples yielded relatively good results and 2 samples showed unsatisfied results due to insufficient diatom for analysis need.The δ 18 O values of 49 samples range from 35.32 to 24.30‰(SMOW).Not only the values are systematically lower,but also the spread in δ 18 O is larger than those for late Quaterary diatom reported by other researchers. It is most likely that they were caused by a slightly higher zeolite,quartz and albite in parts of sample identified by X ray diffraction analysis. However the comprehensive study on sedimentary proxies,especially on the correlation analysis between δ 18 O values and diatom (amorphous) contents show evidentially that the impurities within samples have not changed essentially the information of ecological environment reflected by δ 18 O values. The diatom based recults reveal that the 753cm long sediments of core PC10 printed the deposition of this area during the last 112.5 kaB.P.,representing oxygen isotope stages 1-5 and including one incomplete glacial/interglacial cycle and postglacial period. The sedimentary rate in interglacials seem a little higher than that in glacial,owing to the more terrigenous supply by ice rafting during the interglacial stages.

    Related Articles | Metrics
    A PRELIMINARY STUDY ON THE ELEMENT STRATA AND PALAEOENVIRONMENT OF CORE NP95 FROM THE PRYDZ BAY,ANTARCTICA
    1997, 9 (2):  33-39. 
    Abstract ( 1310 )   PDF (369KB) ( 1241 )  

    This paper deals with the characteristics of element geochemistry of core NP951 from the Prydz Bay,Antarctica and its implications to palaeoenvironment. The results show that the sediments in this area were greatly affected by dissipation of ice cover,gush of freshwater and terrigenous materials in the process of deposition,and the elements such as SiO 2、Al 2O 3、Fe 2O 3、CaO、MgO、P、S、C org in sediments have well recorded the changes of material source resulted by variations of palaeoclimate and the distribution patterns of these elements correspond to the palaeosedimentary environment of ocean and the variations of palaeoclimate; The climate can be roughly divided into five periods such as warm,cold,high temperature,cold tendency and warm tendency since the late Epipleistocene; The turning points of temperature,which indicated the changes of climate,occurred at 145cm(14.4ka B.P.),85cm(10.3ka B.P.) and 25cm(6.3ka B.P.) of core NP951,and the sudden change of element content at 85cm of the core where corresponds to the Gothenburg geomagnetic excursion indicated occurrence of extremely event and marks the beginning of Holocene.

    Related Articles | Metrics
    CHARACTERISTICS OF MINERAL PHASE CONSTITUENTS AND THEIR ENVIRONMENTAL IMPLICATION OF LACUSTRINE DEPOSITS FROM THE FILDES PENINSULA OF KING GEORGE ISLAND,ANTARCTICA
    1997, 9 (2):  40-48. 
    Abstract ( 1327 )   PDF (393KB) ( 1263 )  

    Mineral phase constituents of lacustrine deposits from the Fildes Peninsula of King George Island,Antarctica,are quite similar each other,but different in their contents. The outstanding feature of deposits is of great proportion of non crystalline matter and less in the species of crystalline minerals. Plagioclass (labradorite) is main phase in primary minerals of source rock with less quartz. Secondary minerals are mostly the clay minerals. K bearing minerals are completely lack in deposits. Obviously,all these can be assigned to being the mineralogical characteristics of meta basic rock source and show close genetic and inherited relationship in mineral phase constituents between lacustrine deposits and meta basic volcanic rock spreaded broadly at the peninsula. Among clay minerals,montmorillonite is dominant and kaolinite is less. There is a little difference in chemical compositions between lacustrine deposits and volcanic rock. The constituents of mineral phases change less with grain size. All these clearly prove that physical weathering of the parent rock is much stronger than the chemical weathering. The lacustrine deposit layer and glacial drift layer can be distinguished by the relation curves between the contents of kaolinite or calcite and ages,and their boundary ages are basically consistent with corresponding measured ages.

    Related Articles | Metrics
    A PHYSIOLOGICAL STUDY OF ANTARCTIC KIDDERIA SUBQUADRATUM
    1997, 9 (2):  49-54. 
    Abstract ( 1154 )   PDF (386KB) ( 1162 )  

    The ingestion,oxygen consumption and ammonia excretion of Kidderia subquadratum have been studied under the experimental conditions in the Great Wall Station of Antarctica during the austral summer of 1993-1994.The study of the grazing rate was conducted using chlorophyll pigment analysis of gut content. With the increasing body size and weight,the rates of grazing and oxygen consumption and ammonia excretion increased per individual. But the rates decreased per unit weight. On the average,the bivalve grazed chlorophyll 19.700 μg·ind. -1 ·d -1 and consumed oxygen 9.407 μg·ind. -1 ·d -1 and produced ammonia 0.489 μg·ind. -1 ·d -1 . The O/N ratio was between 9.8~16.3,which indicated the protein was the main metabolic substrate used by K.subquadratrum.

    Related Articles | Metrics
    COMPREHENSIVE RECORDS OF GLOBAL CHANGE FROM POLAR ICE CORES,LOESS PROFILES AND DEEP SEA CORES FOR LAST 150 000 YEARS
    1997, 9 (2):  55-65. 
    Abstract ( 1499 )   PDF (365KB) ( 1393 )  

    Comparison among records from polar ice cores,middle latitude loess profiles and deep sea cores indicates that,the general framework of global change for last 150 000 years is:The last interglacial,beginning in 140 000 years BP and arriving at a period with great prosperity around 125 000 years BP,can be divided into 5 stages,which are three warm stages with two cold stages in polar ice core records,three paleosoils within two loess layers in loess profiles,and three high sea levels between two low sea levels in deep sea core records. The last glacial,from 80 000 years BP to 10,000 years BP,can be divided into three stages,i.e.,early and later glacial stages and interglacial in the middle. The degrees of cold in early and later glacial stages are almost equivalent,but the duration of lowest temperature in later glacial stage was longer than in the early,so the sea level drops lower in the later than in the early. The interglacial can be divided into 7 terms at least,they were 4 warm terms (4 weak paleosoils) with 3 cold terms. Comparing with last interglacial,the climate change in Holocene is more gently. In this framework,a lot of short term and high frequent events in last glacial have been found recently. In these events,the temperature fluctuation is up to 7℃ in years or decades,the environmental change corresponding may be faster. By now the reason of these rapid changes are still unclear,and needs further studies.

    Related Articles | Metrics
    MARINE MAGNETIC ANOMALIES AND DEEP GEOLOGY OF THE BRANSFIELD STRAIT,ANTARCTICA
    1997, 9 (2):  66-72. 
    Abstract ( 1282 )   PDF (422KB) ( 1441 )  

    The expression of ΔT in the Southern Hemisphere presented in this paper. The survey area is located in 63°S ,so where it is characterized by positive anomaly, and negative anomaly in the south. Data processed by reducing to pole and matched filtering, the deep and shallow source anomalies are obtained. Three deep source anomaly belts are related to South Shetland Islands, the Bransfield Strait and Antarctic Peninsula, the north and south belts are positive and negative one in the middle. The two shallow source anomaly belts are related to two faults in north and south edge of the Bransfield Strait. The deep source anomalies are referred to relief of the magnetic basement, because of subduction of the Pacific plate in the South Shetland Islands, where deep background is characterized by high basic composition and the value of deep and shallow source anomalies are higher than that in the south. The faults which are vertical to the trending of the Bransfield Strait are recognized by shallow source anomalies. According to the results of the research on the landform, rock ages and seismic velocity distribution, westward drift of the Antarctic Peninsula had probably happened in history.

    Related Articles | Metrics
    null
    1997, 9 (2):  73-78. 
    Abstract ( 1436 )   PDF (351KB) ( 1341 )  
    null
    References | Related Articles | Metrics
    THE DISTRIBUTION OF CO 2 AND ITS AIR SEA FLUX IN THE PRYDZ BAY OF ANTARCTICA AND ITS ADJACENT WATERS
    1997, 9 (2):  79-83. 
    Abstract ( 1412 )   PDF (356KB) ( 1603 )  

    The partial pressure of carbon dioxide in surface water and atmosphere in the Prydz Bay and its adjacent waters was determined by using infrared analysis from December 1991 to January 1992. The results showed that the distribution of P CO 2 in surface water appeared to be lower in the coastal sea than the open sea,and its distribution was principally controlled by biological activity. The CO 2 flux was estimated by using the flux model, the mean CO 2 air-sea flux in the research area was about -71.9 g/(m 2·a),its potential flux uncertainties might result from the wind dependent exchange coefficient.

    Related Articles | Metrics