Witwatersrand composite paleoplacers

Background. The Witwatersrand gold province located in South Africa is the richest in the world. The Witwatersrand deposits are composite, where osmirids and diamonds are mined along with gold, silver and uranium. The genesis of the Witwatersrand deposits is controversial. Most local geologists support the hypothesis of the presence of paleoplacer deposits with subsequent metamorphic transformation of ore-bearing conglomerates. In addition, there are aeolian, hydrothermal-sedimentary, hydrothermal-sedimentary-metamorphic and magmatic models of ore formation.Aim. To establish the genesis of the Witwatersrand deposits.Materials and methods. Analysis of published literature and factual data.Results. Osmirids and diamonds are mined along with gold, silver and uranium from the composite Witwatersrand deposits. Such a set of useful components is not known in any of the deposits of magmatic or hydrothermal genesis. Considering the confinement of useful components to conglomerates, the detrital nature of most of the gold grains and the presence of various accompanying minerals in the heavy fraction, characteristic of igneous rocks of felsic, basic and ultrabasic composition, the hypothesis of the primary alluvial nature of the deposits of the Witwatersrand province looks the most reasonable.Conclusions. The factual material indicates an alluvial origin of the Witwatersrand deposits with subsequent metamorphic transformation of ore-bearing reefs. The primary alluvial formation of ore-bearing conglomerates is indicated by the confinement of gold and uranium to channel facies with a tendency to accumulate in the basal horizons of the reefs, the presence of rounded gold particles bearing the traces of transportation in alluvial flows, as well as a set of minerals in the heavy fraction of concentrate, characteristic of placers.

Characteristics of Kaolin Clay on Alluvial Formation Subdistrict Mataraman Based on Physical Properties and Chemical Properties

The kaolin clay deposit is found in the Quarter AlluviumFormation (Qa) which is located in the Mataraman Subdistrict and aroundBanjar Regency, South Kalimantan Province, with a monoclinic geologicalstructure. The purpose of this study was to identify types of clay mineralsand physical and chemical characteristics. The analytical method used inthis study is the method of analysis of physical properties and chemicalproperties The study area clay has physical characteristics, elastic clay, easy to form with a mixture of sand and cricket such as quartzite andwhite. Based on the results of XRD analysis, the types of clay mineralsfound were Kaolinit, Mica and Quartz, the chemical requirements of theclay of the study area could be used as material for making ceramics and pottery.

Contribution of granulometric fractions in phosphorus distribution in old alluvial soil

Phosphorus content and balance in granulometric fractions of old alluvial soil developed from alluvial deposits od Vistula River in middle Poland was studied. The distribution of phosphorus in particular granulometric fractions of the studied soil showed high quantitative variability vertically in the profile. This resulted from the layered structure of the Vistulian old alluvial formation developed throughout the Holocene. The contribution of grain fractions in phosphorus accumulation increased with a decrease in their diameter, and in certain fractions with a decrease in their quantitative state. Eluviation of phosphorus down the soil profile concerned in particular grain fraction <0.02 mm. Fractions with a larger diameters were not subject to the process. Phosphorus resources calculated from the grain fraction balance in the analysed soil amounted to an average of 1.7 kg·m2 to a depth of 200 cm.

Transformation of a petroleum pollutant during soil bioremediation experiments

The experiment of ex situ soil bioremediation was performed at the locality of the Oil Refinery in Pancevo (alluvial formation of the Danube River, Serbia) polluted with an oil type pollutant. The experiments of biostimulation, bioventilation and reinoculation of an autochthonous microbial consortium were performed during the six-month period (May-November 2006). The changes in the quantity and composition of the pollutant, or the bioremediation effect, were monitored by analysis of the samples of the polluted soil taken in time spans of two weeks. In this way, from the beginning until the end of the experiment, 12 samples were collected and marked as P1-P12 (Pancevo 1-Pancevo 12). The results obtained showed that more significant changes in the composition of the oil pollutant occurred only during the last phases of the experiment (P8-P12). The activity of microorganisms was reflected in the increase of the quantity of polar oil fractions, mainly fatty acid fractions. In this way, the quantity of total eluate increased, and the quantity of the insoluble residue was reduced to a minimum, whereby the oil pollutant was transformed to a form that could be removed more efficiently and more completely from the soil, as a segment of the environment.

The very high alluvial formation of early Pleistocene age in the Creuse River Valley at Eguzon (Indre) : cryoturbation patterns, prehistoric occupation sites and absolute dating

Around twenty prehistoric sites of the very early Palaeolithic were discovered on the northern edge of the Massif Central, in the Creuse Valley between Crozant and the Paris Basin, and on the Aigurande crystalline plateau that borders it. Concentrated more particularly around Eguzon, the sites are all closely linked to fluviatile formations, whose study, despite difficult exploration conditions, revealed many remnants of alluvial deposits. Those of the very high formation, some up to 15 m thick, were the best preserved. The most significant site, at “Pont-de-Lavaud”, is in a thin bed of gravel made up mainly of quartz pebbles and debris with small, interbedded sand lenses. Tilted 6 to 7° in a small depression in the weathered foliated crystalline basement, the bed is at mid-slope of an interfluve between the Creuse River and one of its small tributaries. Excavation done between 1983 and 1995 uncovered many prehistoric artefacts carved out of quartz in the upper part of the sediment and, below this, various cryoturbation patterns (sorted circles, polygons, inclusions in the alluvium of alterite from the bedrock) and scattered, less abundant artefacts of the same type. Due to the outstanding state of conservation of these findings, they could be studied in a particularly detailed manner and, when coupled with the study of the alluvial formations, enabled us to : – place them at the base of the very high terrace, located 90–110 m above the river’s present-day low water level – attribute the unusual position of the outcrop to the tilting of a block of bedrock by new displacement of an old fault, thus confirming the role of recent tectonics in the regional morphology ; Absolute age dating by Electron Spin Resonance (ESR) of the best conserved outcrops of the very high alluvial formation gave an age of 1 to 1.2 million years, thus placing them at the end of the early Pleistocene. However, dating of alluvial remains near the site and of the site itself, gave ages between 0,9 and 1 million years. Differences are attributed to the role that greater erosion and pedogenic weathering might have played. Therefore, the “Pont-de-Lavaud” occupation sites are among the oldest presently known in Europe.