Single-crystal 40Ar-39Ar dating of pyrite: No fool's clock

Smith, Peter; Evensen, N. M.; York, Derek; Szatmári, Péter; Oliveira, Diógenes Custódio de

doi:10.1130/0091-7613(2001)029<0403:scaado>2.0.co;2

Cited by 54 publications

(27 citation statements)

References 13 publications

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“…Single-crystal Ar±Ar analyses of sanidine crystals dated the KPT at 161 ka (Smith et al 1996). On the basis of chemical composition, refractive index and mineral assemblage, the KPT has been correlated with the W3 deep-sea ash layer (Federman and Carey 1980;Keller 1981;Stadlbauer 1988;Vinci 1985), which is widespread in the eastern Mediterranean south and east of Kos.…”

Section: Regional Setting and The Kpt Eruptionmentioning

confidence: 99%

Transport of pyroclastic flows across the sea during the explosive, rhyolitic eruption of the Kos Plateau Tuff, Greece

Allen

Fernand

2001

Bull Volcanol

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The Kos Plateau Tuff (KPT) is dominated by a sequence of nonwelded rhyolitic ignimbrites, some of which were deposited more than 60 km from source on islands in the eastern Aegean sea, Greece. Palaeo-shoreline reconstruction at the time of the KPT eruption (161 ka) suggests that northward-directed pyroclastic flows travelled over an extensive landmass, although the proximal zone may have been sea. In comparison, flows directed to the southeast and east most likely crossed wide expanses of sea, depositing ignimbrite on islands and peninsulas. The ignimbrites include basal coarse lithic-rich breccias overlain by thick, massive pumiceous zones and generally have low abundances of fine ash. They are interpreted to have been deposited from pyroclastic flows that were relatively dilute and stratified, with lower, denser, lithic-rich zones and upper, expanded, pumicerich zones. High-velocity inherited from the intensity of the eruption, combined with turbulence and low bulk density, favoured transport across water. The pyroclastic flows remained hot even after crossing 35 km of the sea. Heat capacity equations indicate that a depth of~1 cm of water ingested over the outflow path would have cooled the flows by only a few degrees. The ignimbrites deposited prior to the eruption climax have distributions restricted by 300-m-high topographic barriers and they thicken in topographic depressions. These ignimbrites show significant decreases in grain size, proportion of lithic clasts and thickness with distance from source. In comparison, during the eruption climax, the coarsest, most voluminous and widespread KPT ignimbrite was deposited. This ignimbrite has relatively even thickness and uniform componentry and texture regardless of topographic relief or distance from source. Textural analysis indicates that crossing 35 km water to the southeast had little effect on the pyroclastic flow generated during the eruption climax, except for the loss of the coarsest (>20 cm) vent-and conduit-derived lithic clasts. Preferential loss of lithic clasts is related to the mechanism by which they were transported. On land, large, dense clasts could be saltated over the ground surface at the base of the pyroclastic flow. In the case of transport over water, these large, dense clasts sank and were permanently removed from the transport system. Outflow across water had a greater effect on the pre-climax pyroclastic flows. The ignimbrites formed at this stage are significantly thinner and slightly finer grained, and lack basal lithic breccias and lithic clasts >5 cm where the pyroclastic flows crossed the sea, reflecting the lower velocities of the flows. All KPT ignimbrites to the east of the source were deposited from pyroclastic flows that crossed >25 km of water. Ignimbrites in this sector are markedly finer grained, possibly as a result of blocking of coarser pyroclasts by a topographic barrier close to source.

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Section: Regional Setting and The Kpt Eruptionmentioning

confidence: 99%

Transport of pyroclastic flows across the sea during the explosive, rhyolitic eruption of the Kos Plateau Tuff, Greece

Allen

Fernand

2001

Bull Volcanol

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“…However, direct dating of hydrothermal phases via solid or fluid inclusions has enabled several previously problematic classes of ore deposit to be dated. Variably successful dating methods include: Ar-Ar quartz (Kelley et al, 1986;Turner and Bannon, 1992;McKee et al, 1993;Qiu, 1996;Kendrick et al, 2001a;Qiu et al, 2002), Ar-Ar pyrite (York et al, 1982;Smith et al, 2001;Phillips and Miller, 2006), Rb-Sr sphalerite (Nakai et al, 1990(Nakai et al, , 1993Brannon et al, 1992), Rb-Sr quartz (Shepherd and Darbyshire, 1981;Darbyshire and Shepherd, 1985;Pettke and Diamond, 1995) and U/ThPb Calcite (Coveney et al, 2000).…”

Section: Introductionmentioning

confidence: 99%

Part II. Evaluation of 40Ar–39Ar quartz ages: Implications for fluid inclusion retentivity and determination of initial 40Ar/36Ar values in Proterozoic samples

Kendrick¹,

Miller²,

Phillips³

2006

Geochimica et Cosmochimica Acta

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“…Измеренные концентрации 4 He на несколько порядков больше концентраций гелия, содержащегося во флюидных включениях современных "чёрных курильщиков" (10 -8 -10 -10 см 3 /г) [10 и др.]. Если предположить, что древние "чёрные курильщики" захватывали газы в такой же пропорции, то при расчёте U-Th-He-возраста вкладом захваченного гелия можно пренебречь.…”

Section: результаты и обсуждениеunclassified

“…При температуре выше 500 °C в бескислородных условиях, соответствующих отжигу в камере масс-спектрометра, пирит становится неустойчивым и превращается в пирротин [7]. Резкое выделение гелия в этом интервале температур свидетельствует о том, что 4 He до нагревания находился в кристаллической решётке пирита, и, следовательно, его концентрация должна отражать возраст этого минерала.…”

Section: результаты и обсуждениеunclassified

U-Th-He dating of pyrite from the Uzelga Copper-Zinc massive sulfide deposit (South Urals, Russia): first application of a new geochronometer

Yakubovich¹,

Vikentyev²,

Zarubina³

et al. 2019

Доклады Академии наук

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Based on a study of pyrite from the Uzelga Cu-Zn volcanogenic massive sulfide (VMS) deposit (South Urals) the age of ore mineralization was first determined with the direct age-dating method, based on the fraction of radiogenic helium, incorporated into the pyrite crystal lattice from submicron inclusions of U and Th minerals. Taking into account the measurement errors, the obtained age of 377 ± 8 Ma (MSWD = 1.2) is quite consistent with the independent age dates available for the ore mineralization (Late Eifelian-Early Givetian, 385-390 Ma).

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Single-crystal 40Ar-39Ar dating of pyrite: No fool's clock

Cited by 54 publications

References 13 publications

Transport of pyroclastic flows across the sea during the explosive, rhyolitic eruption of the Kos Plateau Tuff, Greece

Transport of pyroclastic flows across the sea during the explosive, rhyolitic eruption of the Kos Plateau Tuff, Greece

Part II. Evaluation of 40Ar–39Ar quartz ages: Implications for fluid inclusion retentivity and determination of initial 40Ar/36Ar values in Proterozoic samples

U-Th-He dating of pyrite from the Uzelga Copper-Zinc massive sulfide deposit (South Urals, Russia): first application of a new geochronometer

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