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REE patterns of Brown, Red and Gray sandstones (a), Mineralized and high mineralized and oxidized and Khaje sandstones(b) Relationship between Cu (ppm) and ∑REE (ppm) contents in the M 2 mg unit(n = 28)(c).
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Chol‐qeshlaghi altered area lies in the northwestern part of the post‐collisional Urumieh‐Dokhtar magmatic arc, NW Iran. Pervasive silicic, argillic, phyllic and propylitic altered zones appears to be intimately affiliated to the fluids derivative of upper Oligocene Khankandi granodiorite. This paper is dedicated to the identification of geochemica...
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... Much of this information is found in geological reports prepared by government and university services and in publications of scientific researches. An important portion of our understanding of the regional geology of the area also derives from GSI that have focused on the same Upper Red Formation (Qom formation) sediments as those hosting the deposit and Cheshmehkonan, Nazkhatun and Nahand stratiform copper deposits (Sadati et al. 2014). ...
The Sorkheh deposit in northwestern Iran exhibits several readily visible general characteristics of sediment-hosted stratiform copper (SSC) mineralization. It consists of fine-grained disseminated base-metal sulfides within gray sandstones (gray beds, the basal whitish Miocene sandstone and shallow-water) that overlie a thick sequence of red beds (Miocene Upper Red Formation). The host gray beds are the basal sandstone and are intercalated with red bed sandstones, which are shown from textural studies to be carbonaceous and to have initially contained very fine-grained, disseminated, syndiagenetic pyrite. The sediment-hosted stratiform copper deposit of the Sorkheh area formed in a location where basinal fluids passed through a series of highly oxidized rocks and could obtained copper, which was then precipitated as the fluids encountered a reductant that destabilized the complexing ability of the fluid. According to the proposed model, the Sorkheh deposit appeared to have begun formation during diagenesis when mineralizing fluids became focused into constrained areas by stratigraphic and/or structural architecture. To form the Sorkheh sediment-hosted stratiform copper deposit, a number of major features must be present: abundant, highly oxidized metal source rocks, highly reduced strata in a position favoring interaction with significant amounts of fluid that previously passed through the oxidized strata package, and significant thicknesses of evaporates capping the reduced strata to serve as a hydrologic seal and a source of high-salinity (and possibly sulfur-rich) brines. Ore-stage sulfides are zoned vertically and obliquely through the mineralized zones, from cupriferous sulfides at low stratigraphic levels to copper-rich mineralization above, with unreplaced pyrite remaining within the upper Miocene. The zoned sulfides and their replacement textures, configuration of the mineralized zones, and the position of ore stage mineralization adjacent to a stratigraphically defined redox transition from red beds upward into graybeds indicate an overprint of copper (and accompanying ore-stage metals) on originally pyritic gray beds. The influx of ore-stage metals, presumably in an oxidized low-temperature brine, terminated with a silicification event that effectively sealed the host sandstones. Consequently, these observations and the overall genetic interpretation are consistent with the general deposit-scale genetic model for early diagenetic SSC mineralization. The regional geologic context is also consistent with its classification as a SSC deposit and is hosted by sediments that were formed in association with evaporates at a low latitude in a Sabkha environment. Source of Sorkheh deposition has been indicated as a sedimentary arid type. Sandstones of the Sorkheh area tectonic settings are obtained in a passive continental margin.
The mineralization and geochemical features of the Tolparovo ore occurrence are studied to reveal the contribution of diagenetic and epigenetic processes in the formation of copper miner-alization in redbed deposits. The methods of electron microscopy, ICP MS, X-ray fluorescence, X-ray phase, atomic absorption, thermogravimetric analyses, and C and O isotopic composition were used. The ore is confined to the fault zone and feathering dolomite-calcite veins, having formed at temperatures of ~330-200 °C and pressures of 0.8-0.2 kbar. Similar to other copper redbed occurrences of the Bashkirian uplift, the Tolparovo copper ore occurrence is confined to basal Neoprote-rozoic deposits. Siliciclastic and carbonate deposits of this level were accumulated at low paleoe-quator latitudes in arid climates of continental and coastal-marine environments close to evaporite ones. Rocks of this stratigraphic interval demonstrate increased background concentrations of copper (~2-5 times exceeding the clark), which explains the stratification of redbed copper ore occurrences , indicating a predominantly sedimentary copper source. However, most of the redbed copper ore occurrences of the Bashkirian uplift are located in tectonic zones and are associated with the dikes of the Inzer gabbrodolerite complex. This connects the generation of ore occurrences with the formation of the Southern Urals Arsha Large Igneous Province (707-732 Ma) and the activity of postmagmatic fluids. Magmatic processes were presumably activated due to the collapse of the Rodinia supercontinent. It is shown that copper mineralization in stratiform deposits may result from a joint manifestation of dia-and epigenesis processes.
The municipality of Caçapava do Sul, in southernmost Brazil, is a future candidate for the certification as a UNESCO Global Geopark (the Caçapava Aspiring Geopark). Proving the international, scientific value of geoheritage in any given territory is a fundamental pre-requisite to be fulfilled for this certification. Representativeness, rarity, integrity, geodiversity of elements and processes, limitations for use, relevance as key locality, and available/published scientific knowledge are the criteria usually applied to evaluate the scientific value of geosites. Thus, in the first place, this paper reviews, demonstrates, and discusses the relevance of the most outstanding geological context of the Caçapava territory: the ‘Camaquã basin’ sedimentary, volcanic, and associated sulphide ore deposits, as a unique stratigraphic record on a Brazilian, South American and Gondwanan scale. Moreover, the relevance of three individual geosites (the Guaritas, Serra do Segredo, and Minas do Camaquã geosites) for international science in the fields of Gondwana tectonics, copper mining, and cavernous weathering research is also demonstrated. Besides their geoscience importance, those geosites share cultural, ecological, aesthetic, functional, and educational values. This paper, based on a comprehensive and thorough literature review, is also an attempt to fill the gap between the context-, theme-, age- or unit-based approach of traditional geology and the site-based and territory-based strategies adopted in geoheritage research, geoconservation, and geoparks.
