Episodic intrusion, internal differentiation, and hydrothermal alteration of the Miocene Tatoosh intrusive suite south of Mount Rainier, Washington

Petrogenesis of Ordovician Magmatism in the Pyrenees (Albera and Canigó Massifs) Determined on the Basis of Zircon Minor and Trace Element Composition

“…The variability of hafnium concentration against Eu anomaly between zircon from the same sample can be regarded as a reliable fractionation index (du Bray et al 2011). The systematic variation and the negative correlation observed in figure 6A suggest that hafnium concentration increases while plagioclase fractionation occurs in the magma, indicating that the zircon composition corresponds to a real variation in the melt composition.…”

“…The mantle-derived samples (CG-07-2, CG-07-3, and CG-07-5) reveal differences. On the one hand, samples CG-07-3 and CG-07-5 (Casemí orthogneisses) present intermediate europium anomalies that become deeper as the Hf content increases, suggesting that Hf can be regarded as a good frac-tionation index even in rocks with mantle affinity (du Bray et al 2011). On the other hand, the europium anomaly is subdued in sample CG-07-2, resulting in a subhorizontal trend ( fig.…”

“…These investigators also interpreted the opposite correlation as resulting from a recharge in the magma chamber and entrainment of zircon in a less fractionated melt. More recently, du Bray et al (2011) suggested that the reliability of hafnium as a fractionation index could be assessed by comparing its concentration with the europium anomaly. Claiborne et al (2010b) proposed additional differentiation indexes for felsic magmatic systems (Th/U and Yb/Gd ratios).…”

Oxygen isotope and trace element geochemistry of zircons from porphyry copper system: Implications for Late Triassic metallogenesis within the Yidun Terrane, southeastern Tibetan Plateau

“…The negligible Eu anomalies present within the PDL zircons are consistent with hydrous parental melts, as evidenced by the presence of hydrous phenocryst phases such as amphibole and biotite within bulk rock samples, a factor that probably suppressed the early crystallization of plagioclase (Blatter and Carmichael, 1998;Moore and Carmichael, 1998;Müntener et al, 2001) and resulted in weak or absent Eu anomalies. Hafnium can be used to monitor magmatic differentiation, as higher Hf concentrations are indicative of zircons generated from more evolved melts from which the early crystallized zircons have already been removed (e.g., Claiborne et al, 2006Claiborne et al, , 2010Castiñeiras et al, 2011;du Bray et al, 2011). Comparing hafnium concentrations with Eu anomalies in zircons from the same sample can therefore be used as an index of plagioclase fractionation (Castiñeiras et al, 2011;du Bray et al, 2011).…”

“…Hafnium can be used to monitor magmatic differentiation, as higher Hf concentrations are indicative of zircons generated from more evolved melts from which the early crystallized zircons have already been removed (e.g., Claiborne et al, 2006Claiborne et al, , 2010Castiñeiras et al, 2011;du Bray et al, 2011). Comparing hafnium concentrations with Eu anomalies in zircons from the same sample can therefore be used as an index of plagioclase fractionation (Castiñeiras et al, 2011;du Bray et al, 2011). In the present study, the absence of negative correlation between zircon Eu/Eu* values and Hf concentrations suggests that the latter increased while only limited plagioclase fractionation from the parental magma of PDL zircons, which is in contrast with the negative correlation observed for the RL and XWC zircons (Fig.…”