Ar-Ar dating of adularia; a tool in understanding genetic relations between volcanism and mineralization; Baia Mare area (Gutii Mountains), northwestern Romania

Lang, B.; Edelstein, O.; Steinitz, G.; Kovacs, Marinel; Halga, Sorin

doi:10.2113/gsecongeo.89.1.174

Cited by 32 publications

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“…The Gutii Mountains, incorporating the Baia Mare orefields, contain long-established hydrothermal, polymetallic sulphide and Au deposits within an andesite dominated geology (Lang et al 1994). The Maramureş Mountains, situated in the east of Maramureş County near Baia Borşa, consist of sub-and infra-Bucovinian Nappes overlying Bucovinian Nappes (Cook 1998) and contain the Neogene ToroiagaTiganul sub-volcanic Massif, which hosts over 15 polymetallic, volcanogenic massive sulphide ore lenses superimposed by epigenetic hydrothermal vein mineralization (Cook 1995).…”

Section: Maramureş Countymentioning

confidence: 99%

Heavy metals in potable groundwater of mining-affected river catchments, northwestern Romania

Bird¹,

Macklin²,

Brewer³

et al. 2009

Environ Geochem Health

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Groundwater, accessed using wells and municipal springs, represents the major source of potable water for the human population outside of major urban areas in northwestern Romania, a region with a long history of metal mining and metallurgy. The magnitude and spatial distribution of metal contamination in private-supply groundwater was investigated in four mining-affected river catchments in Maramureş and Satu Mare Counties through the collection of 144 groundwater samples. Bedrock geology, pH and Eh were found to be important controls on the solubility of metals in groundwater. Peak metal concentrations were found to occur in the Lapuş catchment, where metal levels exceed Dutch target and intervention values in up to 49% and 14% of samples, respectively. A 700 m wide corridor in the Lapuş catchment on either side of the main river channel was identified in which peak Cd (31 μg l(-1)), Cu (50 μg l(-1)), Pb (50 μg l(-1)) and Zn (3,000 μg l(-1)) concentrations were found to occur. Given the generally similar bedrock geologies, lower metal levels in other catchments are believed to reflect differences in the magnitude of metal loading to the local environment from both metal mining and other industrial and municipal sources. Sampling of groundwater in northwestern Romania has indicated areas of potential concern for human health, where heavy metal concentrations exceed accepted environmental quality guidelines. The presence of elevated metal levels in groundwater also has implications for the implementation of the EU Water Framework Directive (WFD) and achieving 'good' status for groundwater in this part of the Danube River Basin District (RBD).

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Section: Maramureş Countymentioning

confidence: 99%

Heavy metals in potable groundwater of mining-affected river catchments, northwestern Romania

Bird¹,

Macklin²,

Brewer³

et al. 2009

Environ Geochem Health

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“…The aims were to (1) back up previous K/Ar ages obtained on two samples from the Pillune and Sando Alcalde sectors (Cassard et al 2000), (2) compare the ages of the Apacheta, Sando Alcalde, and Paula veins, and (3) characterize the duration of the hydrothermal event by dating stages 1 and 2. Analyzing adularia appears, according to the literature (Lang et al 1994), to be particularly appropriate for precisely dating this kind of hydrothermal event. The analyses were performed at the Geochronology Laboratory of the University of Montpellier (France) using procedures along the lines of those described in Monié et al (1997) and Dimo-Lahitte et al (2001).…”

Section: Ar/ 39mentioning

confidence: 99%

Internal vein texture and vein evolution of the epithermal Shila-Paula district, southern Peru

et al. 2006

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The epithermal Shila-Paula Au-Ag district is characterized by numerous veins hosted in Tertiary volcanic rocks of the Western Cordillera (southern Peru). Field studies of the ore bodies reveal a systematic association of a main E-W vein with secondary N55-60°W veins-two directions that are also reflected by the orientation of fluid-inclusion planes in quartz crystals of the host rock. In areas where this pattern is not recognized, such as the Apacheta sector, vein emplacement seems to have been guided by regional N40°E and N40°W fractures. Two main vein-filling stages are identified. stage 1 is a quartz-adulariapyrite-galena-sphalerite-chalcopyrite-electrum-Mn silicate-carbonate assemblage that fills the main E-W veins. stage 2, which contains most of the precious-metal mineralization, is divided into pre-bonanza and bonanza substages. The pre-bonanza substage consists of a quartz-adularia-carbonate assemblage that is observed within the secondary N45-60°W veins, in veinlets that cut the stage 1 assemblage, and in final open-space fillings. The two latter structures are finally filled by the bonanza substage characterized by a Fe-poor sphalerite-chalcopyrite-pyrite-galena-tennantite-tetrahedrite-polybasite-pearceite-electrum assemblage. The ore in the main veins is systematically brecciated, whereas the ore in the secondary veins and geodes is characteristic of open-space crystallization. Microthermometric measurements on sphalerite from both stages and on quartz and calcite from stage 2 indicate a salinity range of 0 to 15.5 wt% NaCl equivalent and homogenization temperatures bracketed between 200 and 330°C. Secondary CO 2 -, N 2 -and H 2 S-bearing fluid inclusions are also identified. The age of vein emplacement, based on 40 Ar/ 39Ar ages obtained on adularia of different veins, is estimated at around 11 Ma, with some overlap between adularia of stage 1 (11.4±0.4 Ma) and of stage 2 (10.8±0.3 Ma). A three-phase tectonic model has been constructed to explain the vein formation. Phase 1 corresponds to the assumed development of E-W sinistral shear zones and associated N60°W cleavages under the effects of a NE-SW shortening direction that is recognized at Andean scale. These structures contain the stage 1 ore assemblage that was brecciated during ongoing deformation. Phase 2 is a reactivation of earlier structures under a NW-SE shortening direction that allowed the reopening of the preexisting schistosity and the formation of scarce N50°E-striking S2-cleavage planes filled by the stage 2 pre-bonanza minerals. Phase 3 coincides with the bonanza ore emplacement in the secondary N45-60°W veins and also in open-space in the core of the main E-W veins. Our combined tectonic, textural, mineralogical, fluid-inclusion, and geochronological study presents a complete model of vein formation in which the reactivation of previously formed tectonic structures plays a significant role in ore formation.

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“…The Ilba-Nistru base metal metallogenetic field from the south-western part of the Gutâi Mts shows an 11.9-11.4 Ma time interval for K-Ar ages for the intrusive rocks, an 11.6-10.7 Ma time interval for the K-Ar ages of adularia and illite (Lang et al 1994;Kovacs et al 1997b) and 10.6 Ma for the Ar-Ar age of adularia (Lang et al 1994). The comparative K-Ar and Ar-Ar ages of the intrusions, lava flows and hydrothermal mineralizations from the Gutâi Mts are exhibited in Figure 12.…”

Section: Resultsmentioning

confidence: 95%

“…The radiometric datings of adularia and illite related to the hydrothermal mineralizations, performed using conventional K-Ar and Ar-Ar step degassing techniques (Lang et al 1994;Kovacs et al 1997b) indicate that the mineralizations are younger than the emplacement of the intrusions in all the metallogenetic fields of the OG (Figs. 3b, 11 and 12).…”

Section: Resultsmentioning

confidence: 99%

“…Most of the hydrothermal mineralizations from the OG (Baia Mare metallogenetic district) are genetically related to the intrusive magmatism and classified accordingly as "intrusion-related" epithermal systems (Kovacs & Fülöp 2010). The hydrothermal activity in the OG is dated 11.5-7.9 Ma (Lang et al 1994;Kovacs et al 1997b), corresponding to the Pannonian.…”

Section: Introductionmentioning

confidence: 99%

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Geochronology of the Neogene intrusive magmatism of the Oaș—Gutâi Mountains, Eastern Carpathians (NW Romania)

Kovacs¹,

Pécskay²,

Fülöp³

et al. 2013

Geologica Carpathica

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Earlier geological work in the Oa -Gutâi Mts (OG), Eastern Carpathians, has revealed the extensive presence of shallow subvolcanic intrusive bodies, both exposed on the surface and covered by Paleogene-Neogene sedimentary sequences and Neogene volcanic formations. This study is based on detailed mapping and sampling of the OG Neogene intrusive magmatic rocks. Thirty seven representative intrusions (sills, dykes, microlaccoliths, etc.) were selected for radiometric dating. These intrusions show a wide variety of petrographic rock-types: from microgabbros to microgranodiorites and from basalts to andesites. However, the intrusions consist of typical calc-alkaline, medium-K rocks, similar to the volcanic rocks which outcrop in the same areas. The K-Ar age determinations on whole-rock samples of intrusions yielded ages between 11.9 Ma and 7.0 Ma (from Late Sarmatian to Middle Pannonian). The results are in good agreement with the common assumption, based on the biostratigraphic and geological data, that large volumes of intrusions have formed during the paroxysm of the intermediate volcanic activity in the OG. Except for the Firiza basalt intrusive complex of the Gutâi Mts (8.1-7.0 Ma), the OG intrusions show similar K-Ar ages as the intrusions of the "Subvolcanic Zone" and Călimani Mts from Eastern Carpathians. The timing of the OG intrusive magmatism partially overlaps with the timing of the intrusive magmatic activity in the Eastern Moravia and Pieniny Mts. The systematic radiometric datings in the whole OG give clear evidence that the hydrothermal activity related to the epithermal systems always postdates intrusion emplacement.

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Ar-Ar dating of adularia; a tool in understanding genetic relations between volcanism and mineralization; Baia Mare area (Gutii Mountains), northwestern Romania

Cited by 32 publications

References 0 publications

Heavy metals in potable groundwater of mining-affected river catchments, northwestern Romania

Heavy metals in potable groundwater of mining-affected river catchments, northwestern Romania

Internal vein texture and vein evolution of the epithermal Shila-Paula district, southern Peru

Geochronology of the Neogene intrusive magmatism of the Oaș—Gutâi Mountains, Eastern Carpathians (NW Romania)

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