High Oxygen Fugacity and Slab Melting Linked to Cu Mineralization: Evidence from Dexing Porphyry Copper Deposits, Southeastern China

Adakitic rocks associated with the Shilu copper–molybdenum deposit in the Yangchun Basin, South China, and their tectonic implications

“…The mixing lines with circle symbols are for Sr = 400 ppm, and the mixing lines with cross symbols are for Sr = 1000 ppm. The fields of Sr-Nd isotope compositions for Dexing adakites, LYRB adakites, and Dabie adakites are modified from Zhang et al (2013), where LYRB Lower Yangtze River Belt age, molybdenite Re-Os dating defined an age of 102.2 ± 2.9 Ma in this study, which is consistent with previous findings (Zhao et al 2012) and identical to the youngest zircon U-Pb age within error, indicating a genetic relationship with Cu-Mo mineralization.…”

Qian'echong low-F porphyry Mo deposits in the Dabie Mountains, central China

“…Amphibole decomposes earlier than phengite, therefore Cl is released earlier than F. The chlorine content of apatite from the Qian'echong porphyry is less than 0.25%, similar to the Yulong deposit (Liang et al, 2006;Zhang et al, 2014;Zhang et al, 2013), which is consistent with their continental tectonic setting. The backscatter image of the analyzed apatite shows a smooth surface, which indicates that fluid activities were not severe.…”

The genetic association between magnetite–hematite and porphyry copper deposits: Reply to Pokrovski

“…It has long been recognized that magmas with high oxygen fugacity favors porphyry Cu mineralization (Ballard et al, 2002;Mungall, 2002;Liang et al, 2006Liang et al, , 2009Sillitoe, 1997Sillitoe, , 2010Sun et al, 2010Sun et al, , 2011Sun et al, , 2012aZhang et al, 2013). Elements that exist in variable oxidation states and present in sufficient abundances to affect the redox state of the porphyry mineralization system, e.g., C, H and S, all establish oxygen fugacity lower than the HM buffer under standard conditions ( Fig.…”

“…Sun et al (2013) presented only several combined important reaction equations in order to make the paper more straightforward. Our response to Pokrovski's comment provides us with an opportunity to better explain the controlling factors and reactions of porphyry mineralization.…”

“…It must always be considered that reactions proposed may not mimic geological observations. Hematite-magnetite intergrowths are common in essentially all large porphyry Cu-Au deposits (Sillitoe, 2010;Sun et al, 2013). This has puzzled us for a while, because the ferrous/ferric ratio of magmas are usually much higher than that of magnetite, therefore the crystallization of magnetite would further increase the ferrous/ferric ratio and correspondingly tend to lower the oxidation fugacity of the parental magmas, under the same physical-chemical conditions (Sun et al, 2004;Liang et al, 2009;Jenner et al, 2010).…”