Radiocarbon dates and late-Quaternary stratigraphy from Mamontova Gora,unglaciated central Yakutia,Siberia, U.S.S.R.

A fine exposure of perennially frozen ice-rich silt and associated flora and vertebrate fauna of late-Quaternary age exists at Mamontova Gora along the Aldan River in central Yakutia, Siberia, U.S.S.R. The silt deposit caps a 50-m-high terrace and consists of three units. An upper layer 1–2 m thick overlies a 10–15-m-thick brownish to black silt layer. The lower silt layer is greenish to gray and about 15 m thick. All the silt is well sorted with 60% of the particles falling between 0.005 and 0.5 mm in diameter and is generally chemically and mineralogically homogeneous. The middle unit contains may extinct vertebrate mammal remains and ice wedges. The lower unit contains little vegetation and no ice wedges. The silt is widespread and exists as a loamy blanket on terraces at various elevations on both sides of the lower Aldan River. The origin of the silt blanket of late-Quaternary age in central Yakutia has long been controversial. Various hypotheses have been suggested, including lacustrine and alluvial, as well as frost-action origins. It is sometimes referred to as loess-like loam. Péwé believes the silt at Mamontova Gora is loess, some of which has been retransported very short distances by water. The silt probably was blown from wide, braided, unvegetated flood plains of rivers draining nearby glaciers. The silt deposits are late Quaternary in age and probably associated with the Maximum glaciation (Samarov) and Sartan and Syryan glaciations of Wisconsinan age. On the basis of biostratigraphy, 10 radiocarbon dates, and their relation to the nearby glacial record, it is felt that the upper unit at Mamontova Gora is Holocene and the middle unit is Wisconsinan. The youngest date available from the middle unit at this particular location is 26,000 years. Dates greater than 56,000 years were obtained in the lower part of the middle unit. The lower unit is definitely beyond the range of radiocarbon dating and probably is older than the last interglacial. The sediment, fauna, ice wedges, stratigraphy, and age of perennially frozen slit deposits in central Alaska are remarkably similar to those of the deposits exposed in central Yakutia. Both areas consist of unglaciated rolling lowlands and river terraces surrounded by high mountains that were extensively glaciated in Pleistocene time. The glaciers extended from the high mountains to the edges of the ranges. In both regions, extensively braided, silt-charged rivers drained the mountains and flowed through the lowlands on their way to the sea. It follows that there should be a similar late-Quaternary history.     

Platinum-group elements in rocks from the voikar-syninsky ophiolite complex,Polar Urals,U.S.S.R.

Analyses of platinum-group elements (PGE) in rocks collected from the Voikar-Syninsky ophiolite in the Polar Urals suggest that the distribution and geochemistry of PGE in this Paleozoic ophiolite are similar to those in Mesozoic ophiolites from elsewhere. Chondrite-normalized PGE patterns for chromitite, the tectonite unit, and ultramafic and mafic cumulate unit have negative slopes. These results are similar to those found for chromitites from other ophiolites; stratiform chromities show positive slopes. If the magmas that form both types of chromitite originate from similar mantle source material with respect to PGE content, the processes involved must be quite different. However, the distinct chondrite-normalized PGE patterns may reflect differing source materials.     

Hydrogeochemical exploration for barite, Ouachita Mountains, U.S.A.

Approximately 100 springs were sampled as part of a general geochemical survey in a 130 by 140 km multi-mineralized area of the Ouachita Mountains. The study area was subdivided into Area I and Area II based on differences in lithology and mineralization. Area I is composed primarily of the Paleozoic Stanley Shale and the Arkansas Novaculite Formation, and has considerable manganese (often present as psilomelane) and barite mineralization. The barite occurs primarily as replacement deposits in shale in Area I. Area II is composed of Paleozoic and Cretaceous sedimentary rocks, and Quaternary alluvium. Mercury, antimony, strontium and barite mineralization is present. The barite mineralization occurs as cement in the Cretaceous sandstone and gravel in this area.The widely prevalent barite cement in Area II is reflected by higher median and upper range values of barium concentration and also higher median and threshold % BaSO₄ saturation values. The presence of barite as cement in the sediments of Area II tends to mask the detection of the barite deposits in this area. Approximately 83% of the sites within 1.7 km of known barite mineralization in Area I were characterized by anomalous barium concentration, and 67% within 3.4 km. Anomalous % BaSO₄ saturation values and Ba/Sr ratios produced success rates generally similar to those of anomalous barium concentrations. Anomalous strontium concentrations did not prove effective in detecting barite mineralization.     

Igor S. Zektser,multifaceted Russian hydrogeologist

Hydrogeology Journal -     

Balance of S in a constructed wetland built to treat acid mine drainage, Idaho Springs, Colorado, U.S.A.

The wetland constructed at the Big Five Tunnel in Idaho Springs, Colorado was designed to remove, passively, heavy metals from acid mine drainage. In optimizing the design of such a wetland, an improved understanding of the chemical processes operating there was required, particularly SO₄²⁻ reduction and sulfide precipitation. For this purpose, field and laboratory data were collected to study the balance of S in the system. Field data collected included water analyses of the mine drainage and wetland effluents and measurements of H₂S gas emissions from the wetland. The concentration of sulfide in the wetland effluent ranged from 10⁻⁴ to 10⁻³ mol/l. The average rates of H₂S emission from the surface of the substrate were 150 nmol/cm²/d in the summer and 0.17 and 0.35 nmol/cm²/d in the winter. This maximum estimated loss of sulfide was not significant in reducing the amount of sulfide available for precipitation with metals. Sequential extraction experiments for S on wetland substrates showed that acid volatile sulfides (AVS) increased with time in the wetland substrate. A serum bottle experiment was conducted to study the S balance in the Big Five wetland by quantitatively measuring the amount of S in different phases as microbial SO₄²⁻ reduction progressed. The increase in AVS reasonably balanced the decrease in SO₄²⁻ concentration in the experiment, suggesting that the decrease in SO₄²⁻ concentration represented the amount of SO₄²⁻ reduced and that nearly all of the sulfide produced was precipitated as AVS. Sulfide precipitation was determined to be the primary metal removal process in the wetland system and amorphous FeS is the primary iron sulfide formed in the substrate.     

The Tungmuling Cassiterite-bearing Pegmatite,Nankang,S.Kiangsi

正 INTRODUCTION The Tungmuling, well known for its cassiterite deposits, is situated in the northern part of the Nankang district, S Kiangsi. It lies about 15 km SW of Shati, a station about 30 km NNW of the Kanhsien City along the Kanhsien-Chian Highway. The tin mine may be reached by following this     

Geochemical examination of lake sapropels used as fertilizers and fodder additives,U.S.S.R.

In recent years sapropels have been increasingly used as fertilizers and fodder additives in Byelorussia and in other regions of the Soviet Union. Thorough geochemical investigations are required to elucidate the essential differences in the composition of lake sapropels. At the same time, a rather wide range of element concentrations permits the selection of lakes and deposits with the most valuable proproties for these uses. The agrochemical effectiveness of sapropels is determined by the content of N, P, K, a number of trace elements, the silty fraction, the amount of biologically active substances, and the level of exchange acidity. It is also important to know the content of harmful components, e.g. pesticides, benzopyrine, a number of heavy metals (such as Pb, Hg and Cd) and the presence of pathogenic microorganisms.The content of mobile forms of elements, which the authors investigated by the method of successive extractions and isolation of humic and fulvic acids, is very essential for the utilization of sapropels as fertilizers and fodder additives.Three limno-geochemical provinces, differing in the types of deposits and ion the chamical composition of sapropels, were defined in Byelorussia. This led to more efficient prospecting and identification of the occurrence of sapropels with specific properties.     

Hydrogeochemical exploration for Mississippi valley-type deposits, Arkansas, U.S.A.

Three areas located in northern Arkansas, U.S.A., representing differing host rock and mineralization, were selected to investigate the usefulness of hydrogeochemical exploration for Mississippi Valley-type Pb-Zn mineralization. Despite the geologic differences among the areas, there were no great differences in groundwater chemistry and threshold values. Anomalous Pb concentrations, and also anomalous Zn concentrations to a lesser extent, are useful in detecting the Pb-Zn mineralized areas; however, specific deposits could not be located. Because of the low threshold values (about 20 μg/1) for Pb and Zn, spring water must be utilized in order to avoid plumbing contamination.     

Compaction of wyodak coal,powder river basin,wyoming, U.S.A.

Precise measurements of 54 deformed tree trunks within the subbituminous Wyodak coal seem in northeastern Wyoming were made at eight locations in surface mines along the outcrop north and south of Gillette. Theory of elasticity applied to the individual measurements gives ratios of peat thickness to coal thickness which range from 1.7:1 to 31:1 and average 7.1:1. This result is similar to those previously determined by other methods in other locations. Statistical analysis establishes to a high degree of confidence, however, that the ratios for each mine site vary widely and cannot be considered to be constant or to vary uniformly within the study area.     

Deinocephalians of the U.S.S.R.

The deinocephalian pelvic girdle, of general pelycosaurian structure, is useful in systematic diagnosis. In primitive Russian deinocephalians, two contrasting pelvic patterns are recognized, one light, thin-walled, narrow, and of V-shaped cross-section, and the other massive, thick-walled, wide, and of U-shaped cross-section. The former is characteristic of two families of lightly- built, mobile land carnivores, the Eotitanosuchidae and the Brithopodidae. The Eotitanosuchidae are more primitive and pelycosaur-like, while the Brithopodidae show more variation, and specializations of large size, shallower acetabulum (related to mobility?), and re-enforcement of a weak pubic symphysis by additional processes. The massive type of pelvis characterizes large, heavily built herbivorous animals of the family Estemmenosuchidae. In general pelvic structure, the Estemmenosuchidae resemble the South African anteosaurs and tapinocephalians and the Russian tapinocephalians. In detail, however, they show a more primitive stage of evolution, overlaid by characteristic specializations which relate them more closely to the advanced Russian forms than to those of South Africa. Three new genera are erected, Biarmosaurus, fam. Eotitanosuchidae; Chthomaloporus, fam. Brithopodidae; and Molybdopygus, fam. Estemmenosuchidae. One specimen formerly referred to Deuterosaurus Yefremov 1954, and five formerly included in the type of Brithopus Yefremov 1954 are referred to Molybdopygus. The more primitive deinocephalians are from Yezhovo in the Ocher District, Perm Province, while more advanced forms are from Isheyevo, in Tataria, where-therocephalians and other South African elements are also found. It is therefore concluded that the Ochersk beds are older than those of Isheyevo and must be dated to zone I of Yefremov's system. — N. Hotton III.