Lang Trang Cave (Northern Vietnam): Pleistocene Mammalian Locality with Gigantopithecus Finds

Doklady Earth Sciences - Speleological, geological and paleontological characteristics of the Lang Trang cave in northern Vietnam are presented. Primates Gigantopithecus blacki von Koenigswald,...     

Wet deposition of excess sulfate at Macquarie Island, 54° S

Annual wet deposition of excess sulfate at Macquarie Island has been estimated from 5 months of rainwater composition data covering the Austral summer of 1985/86. The resulting figure of 2.1±0.6 mmol/m²/yr is at the low end of previous estimates of maritime excess sulfate deposition by precipitation. Within estimated uncertainty limits this figure is consistent with the DMS emission flux which would be predicted for latitude 50°–60° S, based solely on available Northern Hemispheric DMS measurements.Temporarily at the International Meteorological Institute, Stockholm University, S-106 91, Stockholm, Sweden.     

The Benagerie Shear Zone: 1100 Myr of reactivation history and control over continental lithospheric deformation

A newly identified northwest–southeast oriented, deeply-rooted, steep to vertical, large-scale structural system within the Proterozoic Curnamona Province, Australia, which we term the “Benagerie Shear Zone”, is imaged in regional magnetic and gravity datasets. In this study, we use a combination of field analysis and quantitative geophysical methods, to establish a 1100 Myr history of activity along the Benagerie Shear Zone during which the location of younger geological structures are influenced by the pre-existing shear zone. This deformational system is interpreted to have 1) aided ascent and emplacement of the ca. 1600 Ma Ninnerie (magmatic) Supersuite; 2) controlled the loci of nucleation of normal faults during rifting and continental breakup at ca. 800 Ma; and 3) influenced the development of fold structures as well as acting as a plane co-linear to the rotation axis of pre-existing normal faults such that they were steepened and reactivated as strike slip structures during the ca. 500 Ma Delamerian Orogeny. We interpret that the Benagerie Shear Zone has not undergone uni-directional propagation during its evolution but rather through reactivation was a primary influence on controlling the nucleation of Neoproterozoic rift faults, thereby playing a major role in accommodating strain over a significant period of the evolution of the Curnamona Province. This study demonstrates that crustal-scale shear zones can evolve over hundreds of millions of years, have strike-lengths of hundreds to thousands of kilometers, and have vastly different surface expressions along strike.     

Similarity of rivers and their systems

Similarity criteria of rivers and river systems are studied. Zonal and azonal indicators of their similarity are established. The role of river system patterns in the changes of hydrographic and hydrologic characteristic of rivers in the passage from river heads to mouths is considered. The efficiency of applying fractal and indication analyses to river systems is examined. The extent and the scale effect of changes in various characteristics of the flow-channel systems are shown to depend on changes in river orders. The fractal dimension and the scale effects of their changes are correlated. A universal relationship between river orders, on the one hand, and river drainage area and river network density, on the other hand, was established. The root-mean-square error of the obtained formula, evaluated based on data on 274 watersheds, was 0.27, enabling it to be used in hydrological calculations under various landscape conditions.     

Carbon isotopic fractionation between CO2 vapour,silicate and carbonate melts: an experimental study to 30 kbar

The carbon isotopic fractionation between CO₂ vapour and sodamelilite (NaCaAlSi₂O₇) melt over a range of pressures and temperatures has been investigated using solid-media piston-cylinder high pressure apparatus. Ag₂C₂O₄ was the source of CO₂ and experimental oxygen fugacity was buffered at hematite-magnetite by the double capsule technique. The abundance and isotopic composition of carbon dissolved in sodamelilite (SM) glass were determined by stepped heating and the ¹³C of coexisting vapour was determined directly by capsule piercing. CO₂ solubility in SM displays a complex behavior with temperature. At pressures up to 10 kbars CO₂ dissolves in SM to form carbonate ion complexes and the solubility data suggest slight negative temperature dependence. Above 20 kbars CO₂ reacts with SM to form immiscible Na-rich silicate and Ca-rich carbonate melts and CO₂ solubility in Na-enriched silicate melt rises with increasing temperature above the liquidus. Measured values for carbon isotopic fractionation between CO₂ vapour and carbonate ions dissoived in sodamelilite melt at 1200°–1400° C and 5–30 kbars average 2.4±0.2, favouring¹³C enrichment in CO₂ vapour. The results are maxima and are independent of pressure and temperature. Similar values of 2 are obtained for the carbon isotopic fractionation between CO₂ vapour and carbonate melts at 1300°–1400° C and 20–30 kbars.