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Bulk concentrations of Ir, Os, Co and 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 variation of redox in 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, were proposed based on Co content in kamacite, Fa value of olivine, Fs value of low-Ca pyroxene, bulk concentrations of Ir, Os and Co of metal phase and other taxonomic parameters. The discovery of intermediate groups increases the number of chemical groups of chondrites from 9 to 13. Both variation of redox in chondrites and presence of the intermediate groups of chondrites suggest a continuous chemical fractionation in the primordial solar nebula.
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A new lithostratigraphic unit-Half Three Point Formation is determined on an inlet (62°13′40″S, 58°59′01″W) near Half Three Point of Fildes Peninsula of King George Island, South Shetland Islands. This formation consists of volcanic breccia, Sediment-tuff, tuffaceous siltstones and mudstones about 5.5m thick. The Palynomorph assemblage is of Late Cretaceous age (Campanian-Maastrichtian). Isotopic age of the tuffites by Rb-Sr whole rock method is 71.30 ± 0.3 Ma.
The calcite of sand-sized tuffites formed by calcitization during early diagenesis has very light δ18C value of -26.24%, PDB, and δ13C value of -5.130 to 5.631%,PDB. It suggests that the calcitization is related to thermal freshwater originally. The tuffaceous mudstone contains lower B content of 48.4 ppm, corresponding to that of lacustrine mudstones. Low 87Sr/86Sr ratio (0.703189-0.703320) indicates the tuffites of continental origin. Therefore, the formation may represent a lacustrine deposit under low energy and reducing environment. This is only known to define the late. Late Cretaceous lacustrine sediments in Antarctica.
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A new simulation method for solving dynamic equations for stationary katabatic wind is suggested by the assumption that the turbulent exchange coefficient is a function of height and the effect of the cold sloping surface is a multinomial function of height. Calculated wind profiles agree with observational data at Mizuho Station, Antarctica.
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Water samples were collected over
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The paleomagnctis m of 109 oriented samples collected from drill cores through 5 rock units of Late Cretaceous and Early Tertiary on Fildes Peninsula were systematically studied. According to the study, the paleomagnetic pole position of this area is different from the position of Australia during the 55 - 45 Ma period. This means that when the break - up of the Gondwanaland at 55 - 45 Ma ago, Australia was separated from the Gondwanaland, drifting southward 20°- 30° Lat. and rotating 70°- 80° westward and then gradually arriving at recent position. The paleoiatitudinal data indicate that it is not impossible that the area studied was covered with land glacier at that time. The apparent polar wander path of Antarctica through the geological time are also roughly worked out.
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Remobilization and accumulation mechanisms of iodine in marine sediments, which arc divided into several geochemical environment, are studied. The result shows that iodine is characteristically rich in organic fractions of the sediments on the bottom of bay and pelagic sediments. However, it may be associated with oxyhydroxide and adsorptive phase in a highter percentage at the continental shelf and hemipelagic sediments. The environmental characteristics of remobilization of iodine in surficial sediments are similar to that of iron, that is, it is remobilized on anoxic conditions and converted into solid phases when it is in oxic environments, though the iodine does not act as the electron acceptor. The processes of adsorption and oxidation are responsible for the value of It/Corg in excess of that of planktonic materials other than the organic fraction in surficial sediments. It is a comprehensive effect of organism decomposition, oxyhydroxide reduction, particulate adsorption and pore water diffusion on decrease of ratio of iodine to organic carbon with increasing depth in sedimentary column. The diffusive and depositional fluxes of iodine are of the same magnitude, which could be the cause for the poor iodine contents in sedimentary rocks. Based on the calculation and discussion, a new model for the remobilization and accumulation of iodine in marine sediments is set up.
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The ages of volcanic rocks from the Fildes Peninsula of King George Island, West Antarctica, have been determined with K - Ar, 39 Ar - 40Ar, Rb - Sr methods by the authors. The results show that: a. The volcanism on the Fildes Peninsula has been from later Paleocene to early Middle Miocene; b. The formation time of the volcanic rocks of Jasper Hill Member belongs to later Paleocene becarse of the isotope age being 54Ma and 55Ma determined with Rb - Sr and 39 Ar - 40 Ar methods, respectively, c. The volcanic rocks of Agate Beach Member are the products of the volcanic activities during Early Eocene according to K - Ar isochron(45 - 50Ma); d. The geological age of fossil Hill member is about Middle Eocene to Early Oligocene; e. the formation time of Block Hill member is probably early Middle Miocene.
These data combining with the geological adn palaeontological evidences strongly support to best understand the stratigraphical correlation adn reveal the volcanism in studied area.
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