Geochemical, Sr-Nd-Pb, and Zircon Hf-O Isotopic Compositions of Eocene-Oligocene Shoshonitic and Potassic Adakite-like Felsic Intrusions in Western Yunnan, SW China: Petrogenesis and Tectonic Implications

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

“…Previous research has indicated that zircons with δ 18 O values of b6.5‰ may not form from supracrustal melts, whereas zircons with δ 18 O values of N 6.5‰ are indicative of the significant involvement of supracrustal materials (e.g., Cavosie et al, 2005;Davidson et al, 2005;Valley et al, 2005;Hawkesworth and Kemp, 2006;Kemp et al, 2006;Fu et al, 2009;Hawkesworth et al, 2010;Lu et al, 2013). Although some of the PDL zircon δ 18 O values obtained in this study are higher than 6.5‰ (n = 28 of 159, Appendix C; Fig.…”

Tectonic Settings of Potassic Igneous Rocks

“…From Müller et al (1992a) within-plate settings are so distinct, arc potassic igneous rocks are discussed first. Despite the amount of literature published about high-K rocks, the petrogenetic processes producing the various types of potassic igneous rocks are still debated (Peccerillo 1992;Miller et al 1999;Srivastava et al 2009;Guo et al 2013;Lu et al 2013a;Tan et al 2013a;Bucholz Fig. 3.10 Discrimination diagrams for potassic igneous rocks from different tectonic settings, partly based on the more exotic trace elements.…”

“…However, average estimated maximum H 2 O contents of typical mantle material, such as garnet-lherzolite or eclogite, are generally <1.2 wt% (Leech 2001) and single-stage partial melting of such rocks would not produce the volatile-rich and fertile melts with sufficient H 2 O contents capable to produce porphyry copper-gold mineralization (i.e. up to 9 wt% H 2 O; Lu et al 2013a). Therefore, significant exogenous water (>3 wt%) must be added to the mantle source in order to produce the hydrous melts required .…”

“…The exogenous water, as well as the LILE, LREE and halogens, are mainly incorporated in hydrous phenocrysts such as phlogopite and/or amphibole (Aoki et al 1981;Fuge et al 1986;Righter et al 2002;Yang and Lentz 2005;Sarjoughian et al 2014;Teiber et al 2015). As a result, portions of the Earth's upper mantle rich in phlogopite ± clinopyroxene are considered to be important in the genesis of potassic melts (Edgar and Arima 1985;Foley 1992;Till et al 2012;Guo et al 2013;Lu et al 2013a). Meen (1987) considers that potassic igneous rocks form by low degrees of partial melting, under hydrous conditions in a low heat-flow environment, of upper mantle lherzolite that has been metasomatically enriched in such elements as LILE and LREE.…”

“…• Differing relative inputs from at least three identified source components (Wheller et al 1986;Vigouroux et al 2008;Till et al 2012;Lu et al 2013a;Aghazadeh et al 2015): 1. Subducted oceanic crust, characterized by high LILE/LREE ratios (e.g.…”