The Bereznjakovskoje gold trend, southern Urals, Russia   总被引：2，自引：0，他引：2  

B. Lehmann  J. Heinhorst  U. Hein  M. Neumann  J. D. Weisser  V. Fedesejev 《Mineralium Deposita》1999,34(3):241-249

The East Uralian Zone south of Cheljabinsk consists of a Silurian to Early Carboniferous volcanosedimentary sequence on Proterozoic basement, intruded by postorogenic Permian granitic rocks. The 7 by 1–2 km Bereznjakovskoje gold trend is hosted by dacitic to andesitic volcanic-subvolcanic units of Late Devonian age. Epithermal gold mineralization is of the sulfide-rich low-sulfidation (adularia-sericite) type with the metal spectrum of Au-Ag-As-Sb-Cu-Zn-Pb and a characteristic Te component. Silicic and sericitic alteration overprints barren propylitic pyrite-rich assemblages in stockworks and shear zones. Precious-metal mineralization is related to a fahlore-telluride stage overprinting earlier pyrite. Late stage redistribution and weathering liberates gold from telluride mineral phases with fixation of native gold (high fineness) on vugs and grain boundaries, and in intergrowth aggregates with supergene jarosite/limonite. Epithermal mineralization formed below the boiling level and is possibly related to a porphyry system at depth. Received: 23 February 1998 / Accepted: 12 July 1998  相似文献   

Pliocene clays from Aegina (Greece): Reference material for chemical provenance studies on bronze age pottery from the Island     

Anno Hein  Hans Mommsen  Guido Zender 《Geoarchaeology》2004,19(6):553-564

Normally, the use of clays as reference materials in chemical provenance studies of ancient ceramics is complicated due to the original clay paste processing. The primary mixing and/or refining of raw materials during pottery production makes a straightforward comparison of archaeological ceramics with extant geological materials difficult if not impossible in many cases. However, in the case of Pliocene clays from Aegina (Greece), which were examined chemically and mineralogically and compared with Bronze Age pottery produced on the island, a successful exception can be presented. The chemical composition of a large group of Aeginetan pottery resembles the chemical composition of clays from a deposit in close vicinity to the main Bronze Age settlement of the island. Clays from specific outcrops exhibit considerable chemical and mineralogical homogeneity, and the suitability of those clays for pottery production apparently made substantial clay paste processing unnecessary. © 2004 Wiley Periodicals, Inc.  相似文献   

雄安新区深部地热资源形成条件与有利区预测     

郭飒飒  朱传庆  邱楠生  唐博宁  崔悦 《地质学报》2020,94(7):2026-2035

热源、通道、储层、盖层、流体等是中低温对流型地热资源聚集的要素。本文从雄安新区深部地热资源的形成条件出发,分析了热源、储盖、通道的特征。在此基础上结合地温场的分布特点,确定了影响研究区地热资源的重要因素并进行了有利区的预测。结果表明,雄安新区新生界盖层与元古宇碳酸盐岩构成的储盖组合,凹凸相间的构造格局,流体活动等因素共同影响了深部地热资源的赋存。研究区地热资源易富集在断裂控制的凸起构造或者构造低凸起的元古宇热储中。大地热流高值区、具有高渗透储层和区域连续性盖层的凸起构造是地热开发的有利区。  相似文献   

Diagenesis of diatomite from the Kolubara Coal Basin,Baroševac,Serbia     

J. Obradović  James R. Hein  J. Djurdjević 《Geological Journal》1994,29(3):209-217

Diatomite associated with the Kolubara Coal Basin was studied to better understand early stage silica diagenesis of shallow water deposits. The Kolubara Basin consists of Neogene siliciclastic rocks, diatomite, marlstone and rare carbonates. Palaeozoic metamorphic and Mesozoic sedimentary and igneous basement rocks are transgressively overlain by Upper Miocene sandstone, siltstone, shale and mudstone. This Upper Miocene section is transgressively overlain by the Pontian section, which contains diatomite and coal beds. White and grey diatomite forms beds 0.7-2.2 m thick that are continuous over an area of about 2 km². Siliceous rocks vary in composition from diatomite (81-89 per cent SiO₂) to diatom-bearing shale (58-60 per cent SiO₂). Siliceous deposits are laminated in places, with the laminae defined by variations in clay minerals, organic matter and diatoms. Diatomite shows only incipient diagenesis characterized by the fragmentation of diatom frustules, the minor to moderate corrosion of frustules and the formation of minor amounts of opal-A' (X-ray amorphous inorganic opal) cement. The low degree of diagenesis results from the young age of the deposits, low burial temperatures and possibly also from the presence of abundant organic matter and the dissolution of kaolinite. The presence of only weak diagenesis is also reflected by the characteristically poor consolidation of the rocks and low rank of the associated coal.  相似文献