G. Friedrich

The distribution of rare earth and minor elements in manganese nodules and sediments from the equatorial and S.W. Pacific

Abstract 62 manganese nodules and 17 associated sediments from the equatorial and S.W. Pacific have been analyzed for a number of elements, including the rare earth elements (REE), by instrumental neutron activation. Sc, Co, As, Hf, Th and REE occur in higher concentrations in S.W. Pacific than in equatorial Pacific nodules, reflecting the higher iron content of the S.W. Pacific nodules. These elements are probably incorporated nondiscriminantly into the iron oxyhydroxide structure by direct sorption from seawater because they are too large to be incorporated into the manganese oxide structure. The highest Ce La ratios are also found in the S.W. Pacific nodules. This may result from the fact that these nodules lie beneath the path of the fast flowing, well-oxygenated Antarctic Bottom Water (AABW) which facilitates oxidation of Ce to the tetravalent state. If so, this supports the idea that the Ce La ratio of manganese nodules is an important redox indicator. Negative cerium anomalies were noted for nodules from Areas F and G can be interpreted on the same model. The REE contents in equatorial Pacific siliceous oozes and S.W. Pacific red clays are similar on a carbonate-free basis. The Ce La ratio of the S.W. Pacific red clays is, however, much higher than that of the equatorial Pacific sediments, possibly reflecting the preferential oxidation of Ce to the tetravalent state beneath the AABW. There appears to be no systematic relationship between the REE abundance in the nodules and their associated sediments, although absolute REE abundances are higher in nodules than in their associated sediments. Nodules with the highest Ce La ratios are, however, found on sediments with the highest Ce La ratios. The principal difference in the REE distribution pattern of the nodules and sediments lies in the well-known cerium anomaly which is positive to slightly negative for nodules and always negative for sediments.

Geology and metallogeny of copper deposits

I Deposits in Mafic and Ultramafic Complexes.- The Physical and Petrologie Setting and Textural and Compositional Characteristics of Sulfides from the South Kawishiwi Intrusion, Duluth Complex, Minnesota, USA.- Application of Stable Isotopic Studies to Problems of Magmatic Sulfide Ore Genesis with Special Reference to the Duluth Complex, Minnesota.- Controls on the Formation of Komatiite-Associated Nickel-Copper Sulfide Deposits.- Depositional Environments of Volcanic Peridotite-Associated Nickel Sulphide Deposits with Special Reference to the Kambalda Dome.- Geochemistry of the Sudbury Igneous Complex: A Model for the Complex and Its Ores.- Sulfide Petrology and Genesis of Copper-Nickel Ore Deposits.- Types and Distinctive Features of Ore-Bearing Formations of Copper-Nickel Deposits.- On the Role of Metamorphism in the Formation of Nickel-Copper Sulfide Deposits in the Kola Peninsula.- The Gabbro-Wehrlite Association in the Eastern Part of the Baltic Shield.- Peridotitic Komatiites and the Origin of Ores (Southeastern Part of the Baltic Shield).- Geologic Setting of Selected Chromium and Nickel Deposits of China.- II Porphyry Deposits.- Recent Advances in Porphyry Base Metal Deposit Research.- The Geochemical Behaviour of Copper and Molybdenum in Ore-Forming Processes.- Batholith-Volcano Coupling in the Metallogeny of Porphyry Copper Deposits.- Space-Time Distribution, Crustal Setting and Cu/Mo Ratios of Central Andean Porphyry Copper Deposits: Metallogenic Implications.- Metallogenic Zoning of Volcano-Plutonic Belts and Porphyry-Copper Mineralization.- Geological and Structural Conditions of Localization of the High-Grade Ores of Porphyry Copper Deposits.- Elements Determining in the Geological-Structural Model of the Erdenetuin-Obo Copper-Molybdenum Ore Field, Mongolia.- Genetic Aspects of the Recsk Mineralized Complex, Hungary.- Ore-Magmatic Systems of Copper-Molybdenum Deposits.- III Deposits of Volcanic-Hydrothermal Association.- Base Metal Deposits in the Iberian Pyrite Belt.- Copper-Pyrite and Pyrite Base Metal Deposits of the Caucasian Region.- The Hidden Mineralogical and Geochemical Zoning and the Ore-Forming Conditions of Copper and Copper- Lead-Zinc Massive Sulfide Deposits.- Zoning of Massive Sulphide Deposits and their Origin.- Physico-Chemical Conditions of Base Metal Sulphide Ore Formation.- On the Genesis of Barite Associated with Volcanogenic Massive Sulfides, Fukazawa Mine, Hokuroku District, Japan.- IV Sediment-Hosted Deposits.- Diagenetic Features at White Pine (Michigan), Redstone (N. W. Territories, Canada) and Kamoto (Zaire). Sequence of Mineralization in Sediment-Hosted Copper Deposits (Part 1).- Diagenetic Sulphide Mineralization Within the Stratiform Copper-Cobalt Deposit of West Kambove (Shaba- Zaire). Sequence of Mineralization in Sediment-Hosted Copper Deposits (Part 2).- Geochemical Aspects of Stratiform and Red-Bed Copper Deposits in the Catskill Formation (Pennsylvania, USA) and Redstone Area (Canada). Sequence of Mineralization in Sediment-Hosted Copper Deposits (Part 3).- Stratabound Copper Deposits in East South-Central Alaska: Their Characteristics and Origin.- Major Element Geochemistry of the Host Rocks in Some Sediment-Hosted Copper Deposits.- Zechstein Copper-Bearing Shales in Poland. Lagoonal Environments and the Sapropel Model of Genesis.- Formation Conditions of Copper Sandstone and Copper-Shale Deposits.- Major Types of Copper-Bearing Zones in the Soviet Union.- Red-Colored Terrigenous Sediments - Specific Copper- Forming Systems.- Cupriferous Sandstones and Shales of the Siberian Platform.- Genetic Types of Copper Mineralization in the Igarka Area, West of the Siberian Platform.- The Diverse Styles of Sediment-Hosted Copper Deposits in Australia.- Mineral Zoning in Sediment-Hosted Copper-Iron Sulfide Deposits - A Quantitative Kinetic Approach.- Results of Recent Exploration for Copper-Silver Deposits in the Kupferschiefer of West Germany.

Formation of ore minerals in metamorphic rocks of the German continental deep drilling site (KTB)

The German Continental Deep Drilling Program (KTB) drilled a 9.1 km deep profile through amphibolite facies metamorphic rocks and reached in situ temperatures of 265°C. Each lithologic unit is characterized by typical ore mineral assemblages related to the regional metamorphic conditions. Paragneisses contain pyrrhotite + rutile + ilmenite ± graphite, metabasic units bear ilmenite + rutile + pyrrhotite ± pyrite, and additionally, the so-called variegated units yield pyrrhotite + titanite assemblages. In the latter unit, magnetite + ilmenite + rutile + titanite assemblages related to the lower amphibolite facies breakdown of ilmenite-hematite solid solution also occur locally. Retrograde hydrothermal mineralization which commenced during Upper Carboniferous times is characterized by the following geochemical conditions: (1) low saline Na-K-Mg-Cl fluids with sulfur and oxygen fugacities at the pyrite-pyrrhotite buffer and temperatures of 400–500°C, (2) fluids with CO2, CH4±N2, andpH, Eh, sulfur, and oxygen fugacity in the stability field of graphite + pyrite at temperatures of 280–350° and (3) moderate to high saline Ca-Na-Cl fluids with CH4+ N2; sulfur and oxygen fugacity are in the stability field of pyrrhotite at temperatures <300°C. The latter environment is confirmed by in situ conditions found at the bottom of the deep drilling. Monoclinic, ferrimagnetic pyrrhotite is the main carrier of magnetization which disappears below about 8.6 km, corresponding to in situ temperatures of about 250°C. Below this depth, hexagonal antiferromagnetic pyrrhotite with a Curie temperature of 260°C is the stable phase. Temperature-dependent transformation of pyrrhotite and the reaching of its Curie isotherm within the Earth crust are one of the striking results of the KTB deep drilling project.

Manganese nodule formation in the Pacific Ocean: a general theory

An attempt is made to outline a satisfactory general theory for the formation of Pacific deep-sea manganese nodules based on a consideration of the time of initiation of formation of the nodules, a mechanism of maintenance of the nodules at the sediment surface and the role of biological productivity of the surface waters in influencing nodule characteristics. Using this model, the principal physical, chemical and distributional features of the nodules and reasons for their differences on a regional scale in the Pacific can be interpreted.

Hydrocarbon-bearing fluid inclusions in calcite-filled horizontal fractures from mature Posidonia Shale (Hils Syncline, NW Germany)

Abstract Hydrocarbon-bearing fluid inclusions in calcite-filled horizontal fractures from mature Posidonia Shale (0.88% R o ) were investigated by microscopic, microthermometric and chemical methods. The fluid inclusions predominantly contain both a liquid hydrocarbon phase, which shows bright UV-fluorescence colours (yellow, brownish, light blue) and a non-fluorescent hydrocarbon gas phase. The different UV-fluorescence colours probably reflect the different gross chemical compositions of the trapped liquid hydrocarbons. The saturated hydrocarbon fraction of the fluid inclusions (mostly secondary inclusions) predominantly consists of low-molecular-weight n -alkanes (C 9 C 12 ), while C 12 C 22 - n -alkanes are more abundant in the adjacent rock matrix. The molecular composition of the fluid inclusions appears to reflect a mobile hydrocarbon phase, which was entrapped within the calcitic fill of the horizontal fractures. Pressure-corrected trapping temperatures were estimated for primary fluid inclusions (123°–162°C). This temperature range is in agreement with the results from numerical simulation studies, which indicate a maximum temperature of 148°C coinciding with the period of fracture formation, calcite filling, and entrapment of primary fluid inclusions.

Rare earth elements in manganese nodules from the South Atlantic Ocean as indicators of oceanic bottom water flow

Abstract The mineralogy and geochemistry of a suite of nine manganese nodules from the South Atlantic have been determined. The Ce/La ratios of the nodules were investigated to see if they could be used as redox indicators to trace the oxygen content of the ambient water mass and the flow path of the Antarctic Bottom Water as has previously been successfully carried out in the Pacific Ocean. The Ce/La ratios of the nodules decrease in the sequence Lazarev Sea, Weddell Sea (10.4 and 9.7)>East Georgia Basin (6.5 and 7.1)>Argentine Basin (5.0), but then increase in the Brazil Basin (6.2) and Angola Basin (9.8 and 15.1). A further decrease was observed in the Cape Basin (7.6). An extremely high Ce/La ratio of 24.4 had already been determined for nodules sampled north of the Nares Abyssal Plain in the western North Atlantic. These data reflect the more complicated pattern of bottom water flow in the South Atlantic than in the South Pacific. The penetration of more oxygenated North Atlantic Deep Water into the South Atlantic accounts for the higher Ce/La ratios in the nodules from the Angola and Brazil basins. Based on this study, the flow path of the Antarctic Bottom Water could only be traced as far north as the Argentine Basin. The unique geochemistry of nodules from the central Angola Basin (high Mn/Fe and Ce/La ratios, high contents of Ni, Cu, Zn and Mo) appears to be a function of the nature of the overlying water mass and of the multiple diagenetic sources of metals to the nodules.

Platinum-Group Element Mineralization in the Ultramafic Sequence of the Acoje Ophiolite Block, Zambales, Philippines

Platinum-group minerals (PGM) are related to the ultramafic sequence of the Acoje ophiolite block, which was recently mined for metallurgical chromite.

Mercury and mercury compounds in surface air, soil gas, soils and rocks

ABSTRACT Kromer, E., Friedrich, G. and Wallner, P., 1981. Mercury and mercury compounds in surface air, soil gas, soils and rocks. In: A.W. Rose and H. Gundlach (Editors), Geochemical Exploration 1980. J. Geochem. Explor., 15: 51–62. Secondary mercury dispersion haloes were detected and defined above sulphide mineralization by in-situ mercury in soil gas measurements. The meteorological factors controlling the concentration of mercury in soil gas were investigated by long-term experiments. Different mercury compounds in soils and rocks have been determined by a thermal destruction technique. In areas with sulphide mineralization, adsorbed mercury, HgCl 2 , HgS, HgSO 4 and organically fixed mercury are the most important mercury compounds. The concentrations, transport and secondary formation of mercury and its compounds is controlled by: (1) the content of organic matter, Fe-oxides/hydroxides and clay minerals of the soils; and (2) the composition of the underlying rocks. The occurrence of mercury-sulphur compounds indicates the topographic influence on down-slope dispersion and the direction of inclination of the ore body. HgS and HgSO 4 are the dominant mercury compounds in the ore; in the bedrock, mercury occurs mainly as adsorbed mercury.

Erzmikroskopische und mikroanalytische Untersuchungen an Manganerzkonkretionen aus dem pazifischen Ozean

The distribution of iron, manganese, copper and nickel has been determinted in different zones of manganese nodules by electron probe analysis. A single nodule is characterized by the inhomogeneous distribution of these elements, and the correlation of Mn with Cu and Ni within certain zones. Concentrations of Mn, Cu and Ni of 41, 1.0 and 2.0 percent, respectively, have been found in layers containing 2.0 percent Fe only. On the other Land iron-rich layers are characterized by low contents of Mn, Cu and Ni. There is no considerable variation in the ratios of these elements with distance from the centre of an individual nodule. The correlation of reflectivity and chemical composition is emphasised.ZusammenfassungDie Verteilung von Eisen, Mangan, Kupfer und Nickel in Manganerzkonkretionen wurde mit Hilfe der Elektronenstrahl-Mikroanalyse untersucht. Die einzelnen Manganknollen zeigen einen inhomogenen Aufbau aus Mn- und Fe-reichen Zonen, die sich erzmikroskopisch unterscheiden lassen. Auffallend sind die Korrelationen zwischen Mangan, Kupfer und Nickel auch im Mikronbereich. Die Zusammenhänge zwischen den spektralen Reflexionsfunktionen und der chemischen Zusammensetzung der Manganerzkonkretionen werden diskutiert.

Geologic Setting and Genesis of Kupferschiefer Mineralization in West Germany

Three principle types of Kupferschiefer mineralization can be distinguished, characterized by different geologic setting, lithological features, geochemical pattern, and paragenesis.