Rb–Sr dating of sphalerites from Tennessee and the genesis of Mississippi Valley type ore deposits

Paleomagnetic dating of Upper Mississippi Valley zinc–lead mineralisation, WI, USA

“…Elsewhere, the 87 Rb -86 Sr sphalerite method has produced more controversial results. For the MVT deposits of East Tennessee, Nakai et al (1990Nakai et al ( , 1993 have reported 87 Rb -86 Sr sphalerite ages 377 F 29 and 347 F 20 Ma that span most of the Devonian andMississippian, that are significantly different at >95% confidence, and that disagree with other radiometric and paleomagnetic ages (Symons and Stratakos, 2002). At Pine Point in northern Canada, the 87 Rb -86 Sr sphalerite method has given replicate ages of 361 F 13 and 374 F 21 Ma (Nakai et al, 1993;J.C.…”

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

“…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).…”

Concordant ages for the giant Kipushi base metal deposit (DR Congo) from direct Rb–Sr and Re–Os dating of sulfides

“…Like molybdenite, these sulfides may have extremely low concentrations of highly radiogenic Os, for which they have been termed LLHR (low-level, highly radiogenic) minerals by Stein et al (2000). The pioneering work of Nakai et al (1990) has demonstrated the suitability of sphalerite as a Rb-Sr geochronometer. Since then, the age of many carbonate-hosted base metal deposits has been successfully determined by direct Rb-Sr dating of sphalerite which has significantly advanced the genetic understanding of this mineralization style (see Christensen et al 1996, and references therein).…”