Mineralium Deposita (v.10, #3)

Within the pre-alpidic consolidated Serbo-Macedonian Massif several paleogene hydrothermally altered porphyritic stocks have been found and investigated. The subvolcanic activity was ascertained to be confined to three main centers. Hydrothermal alterations within the stocks and as haloes in the surrounding country rock are widespread, the phyllic and the propylitic alteration facies being predominant, whereas the potassic facies seems to be lacking. Geochemical investigations in the Krousia Mountains and in the Eastern Chalkidiki traced in some of the altered stocks and alteration haloes a sulfide mineralization of porphyry copper type with pyrite, chalcopyrite, galena, sphalerite and some gold. The economic value of this metallogenic province is not yet fully established.

Sulphide mineralisation in the Middle Old Red Sandstone fluviatile and lacustrine sediments of Orkney is ascribed to depositional and early diagenetic events. The cations involved are considered to have been introduced in the suspended load of the rivers. Deposition of aragonite led to co-precipitation and concentration of lead. Degradation of algal material produced the organometallic complexes which enabled transport of lead, zinc, and copper. Expulsion of pore water during compaction of the sediments is regarded as the main cause of fluid migration. Deposition of sulphides occurred in the presence of sulphate-reducing bacteria when the organic complexes became unstable.

We studied carbonates of mainly postmagmatic origin. As a result of extensive measurements of the absorption spectra, light of λ=253 nm of a Xenon lamp was used for excitation. The emitted luminescence was measured by a photometer. Luminescence of considerable intensity is exhibited by calcites, aragonites, smithsonites, strontianites as well as by witherites and cerussites. Calcites have the most strongly differentiated spectrum. Each of their five different luminescence types is caused by a special activation. Particularly characteristic are calcites, whose luminescence is activated (a) by lattice defects and/or Zn-contents (broad emission band with maximum at about 420 nm), (b) by Mn/Pb-substitution (maxima at 325 and 420 nm), (c) by REE (maxima at 340–360, 480, 545, 575, 623 and 670 nm). The other, also luminescing carbonates, show a close relationship to the calcite of the ‘fundamental type’ (a) but with varying position of their emission maxima. Also most of the phosphorescing samples of calcite are of this type (a). The majority of these calcites originate from telethermal, surface-near formation regions and from resolutions, respectively. Fe, Ni, and in the case of smithsonite also Cu, are ‘killing elements’, which are less efficient by REE-activation than by Mn/Pb-activation. In particular phosphorescence and activation by lattice defects will be disturbed. The luminescence analysis represents a possibility for mineral identification. Furthermore it gives criteria for chemical homogenity of minerals, and locates concentrations of certain elements in inhomogeneous samples. For the most important activators it is a tool for qualitative element detection, especially in the case of REE.

The mercury in sulfide deposits emplaced in volcanic suites by N. A. Ozerova; V. L. Rusinov; Y. K. Ozerov (228-233).
Massive sulfide deposits in the Pacific and Ural provinces have varying mercury contents. The latter is lower in metamorphosed ores than in unmetamorphosed or in young ones. Two varieties of cenozoic sulfide ores are distinguished: 1) products of subcontinental solfataric action with high mercury content in pyrites, accompanied by cinnabar, 2) products of postvolcanic activity in submarine suites with low mercury content in sulfides (Kurokotype). A distribution of mercury between coexisting sulfides (in descending rank) corresponds to the sequence: sphalerite-chalcopyrite-pyrite. During metamorphism, sulfides loose their mercury (pyrite in higher degree than chalcopyrite). It is possible that mercury vaporised from sulfides has some influence on the formation of mercury ores at some distance from metamorphosed sulfide bodies within the same region.

Lagoonal sediments of the upper part of the Wetterstein-limestone (Ladinian/Carnian, Alpine Triassic) of the lead-zinc deposit of Bleiberg-Kreuth were examined. They are influenced by cyclic successions, which show emersion periods. These emersions can also be found in similar rocks of the same age. The cyclothems are attributed to eustatic fluctuations. In the rocks, underlying the unconformity, karstic cavities were formed. The lead-zinc ores are thought to be mainly intra-karstic sediments, detrital and chemical deposits. The metal-concentration in the cavities seems to have originated from a directly preceding enrichment in the evaporitic phase, as well as from the erosion of this and other neighboured sediments.

In the volcanic region of Gleichenberg, Styria, Younger Tertiary latite and trachyte are altered by solfataric solutions to kaolinite, alunite and a mineral assemblage of low-cristobalite and alunite, which is mined as trass. The behaviour of the elements K, Rb, Sr, Ba, Fe, Zn, V and Cr is shown during the different alteration processes. As a result the following idea is proposed about the process of these events: initially kaolinization of latite took place by strongly acid solutions, lateron trachyte was altered to alunite by weakly acid solutions. In the last stage trass was formed by solutions that have become alkaline by reacting with the country rock.

The problem of the paucity of post-Hercynian mineralization in the Alps compared with the rich mineral endowment of other young fold mountain belts of the same world wide system has for long been an unsolved puzzle. It is suggested that the key to this problem can be found in relating the Alpine geosyncline to the plate tectonic framework within which it evolved. Hsü's suggestion that the Alpine geosyncline did not develop at a convergent juncture, but occupied part of the region where the African and European plates were moving laterally past each other leads on to the inference that subduction of oceanic crust did not take place on any significant scale during the evolution of the geosyncline or its subsequent deformation. This accounts for the relative absence of porphyry copper deposits and Cyprus-type massive sulphide deposits. Consideration of the possible history of the Alpine geosyncline in the light of plate tectonic theory accounts not only for the absence of these oretypes but also provides an explanation for the presence of some of the few major metalliferous deposits of this orogen. This in turn suggests the consideration of certain genetic models for the origin of these deposits and has important overtones with regard to mineral exploration in the Alps.

Particles of definite skeletal and faecal origin, oncolites and stromatolitic structures from Mussoorie phosphorite, occurring in the Kumaon Lower Himalaya, have been illustrated in the present note with the purpose of providing more evidence in favour of the biochemical mode of origin of these phosphorites.

Personal news (266-266).

Obituary by Paul Ramdohr (266-266).

Book reviews by A. Maucher (267-268).

Announcements (267-267).