The role of volatile exsolution and sub-solidus fluid/rock interactions in producing high 56Fe/54Fe ratios in siliceous igneous rocks

Iron isotope tracing of mantle heterogeneity within the source regions of oceanic basalts

“…While this difference is qualitatively consistent with melting models, the overall range in δ 57 Fe displayed by MORB and OIB (Fig. 2) is over 0.2h and 0.4h, respectively, for a restricted range of MgO contents (see Figure caption for details), and is substantially greater than that predicted in our melting models and those of Dauphas et al (2009) and is much larger than can be explained by analytical uncertainty or processes such as fractional crystallization (Schuessler et al, 2009), olivine accumulation (Teng et al, 2008) and fluid exsolution (Heimann et al, 2008). A similar discrepancy also exists for melting residues as the δ 57 Fe variation displayed by fresh abyssal peridotites (Craddock et al, 2013), commonly thought to represent the residues of MORB-melt extraction, is 0.24h, far greater than that predicted by any model.…”

Multiple sulphur and iron isotope composition of detrital pyrite in Archaean sedimentary rocks: A new tool for provenance analysis

“…3b) This is supported by the absence of porous pyrites in our sample from this reef. Dominion Reef pyrite and chalcopyrite from underlying and overlying rocks display a relatively small range of δ 56 Fe values, which is within the range of igneous δ 56 Fe values in mantle-derived rocks, including bulk rocks and mineral separates (Poitrasson and Freydier, 2005;Heimann et al, 2008;Teng et al, 2008;Schoenberg et al, 2009). This range is also consistent with experimental studies of Fe isotope fractionation at magmatic temperatures (Shuessler et al, 2007;Shahar et al, 2008).…”

Iron isotope fractionation in planetary crusts

“…In the past decade, the development of high-resolution Multi-Collector InductivelyCoupled-Plasma Mass-Spectrometers (MC-ICP-MS) has allowed measurements of iron isotope composition at high precision (Belshaw et al, 2000;Zhu et al, 2001;Weyer and Schwieters, 2003;Dauphas et al, 2009b;Millet et al, 2012). Following this improvement, small yet resolvable iron isotopic variations in igneous rocks have been discovered (Poitrasson et al, 2004;Weyer et al, 2005;Schoenberg and von Blanckenburg, 2006;Weyer and Ionov, 2007;Heimann et al, 2008;Teng et al, 2008Teng et al, , 2011Dauphas et al, 2009a;Weyer and Seitz, 2012).…”