Immiscible iron- and silica-rich melts in basalt petrogenesis documented in the Skaergaard intrusion

Trace element compositions of apatite from the middle zone of the Panzhihua layered intrusion, SW China: Insights into the differentiation of a P- and Si-rich melt

“…8a). If a Fe-rich melt contains 40 wt.% SiO 2 and 10.5 wt.% CaO (Charlier and Grove, 2012;Jakobsen et al, 2005;Philpotts, 1982), the P 2 O 5 content in the Fe-rich melt at the saturation of apatite is 9.0 wt.% at 1050°C and 10.4 wt.% at 1070°C (Fig. 8b), indicating that P could be highly under-saturated in the Fe-rich melt at high temperature.…”

Experiments on liquid immiscibility along tholeiitic liquid lines of descent

“…Compositional evolution in natural systems, usually considered to result from fractional crystallization, will produce suites of liquids more likely to develop immiscibility. This is illustrated by the Skaergaard case: immiscibility has been thoughtfully described in natural rocks (McBirney 1975;Jakobsen et al 2005Jakobsen et al , 2011Holness et al 2011;Humphreys 2011) but not reproduced during experiments on the parental magma composition (Toplis and Carroll 1995;Thy et al 2006). …”

Mesoproterozoic high Fe–Ti mafic magmatism in western Shandong, North China Craton: Petrogenesis and implications for the final breakup of the Columbia supercontinent

“…Silicate liquid immiscibility has been experimentally confirmed (Roedder, 1951;Freestone, 1978;Visser and Koster Van Groos, 1979;Philpotts, 1982;Naslund, 1983;Veksler et al, 2006) and widely invoked to interpret the origin of components in Fe-Tienriched layered intrusions and basalts worldwide, such as the Bushveld Complex, South Africa (VanTongeren and Mathez, 2012 and references therein), the Sept Iles intrusions in Canada , the Skaergaard intrusion in Greenland (Jakobsen et al, 2005(Jakobsen et al, , 2011Holness et al, 2011;Humphreys, 2011), and the Panzhihua intrusion in SW China (Zhou et al, , 2008a. Nonetheless, the resultant rock association from such a mechanism is prevalently composed of two rock types with contrasting chemical compositions, including low-Si, Fe-Ti-rich basic rocks and overlying coeval Si-rich felsic rocks.…”

“…7b) is inconsistent with this view. Indeed, like the cumulate oceanic gabbros and several well-known layered intrusions with Fe-Ti-rich trends in the world (i.e., the Skaergaard Intrusion in East Greenland, Nielsen, 2004;Jakobsen et al, 2005Jakobsen et al, , 2011; the Sept Iles layered intrusion in Canada, Namur et al, 2011; the Bushveld Complex in South Africa, VanTongeren and Mathez, 2012; the Panzhihua intrusion complex, Zhou et al, 2005Zhou et al, , 2008a,b and the Damiao complex in the NCC, Zhao et al, 2009), they are generally sub-alkaline in composition, and exhibit positive Eu and Sr anomalies. Moreover, structurally, they commonly show cryptic layering.…”

“…Moreover, most of the Fe-Ti-rich compositions are found in plutonic environments and only rare cases are known for erupted rocks (Clague et al, 1981;Perfit and Fornari, 1983;Sinton et al, 1983;Hunter and Sparks, 1987;Pearce et al, 1994;Hooper, 2000;Harper, 2003;Zhang et al, 2012). Some of these intrusions host world class Fe-Ti oxide deposits, such as the Skaergaard Intrusion in East Greenland (e.g., Nielsen, 2004;Jakobsen et al, 2005Jakobsen et al, , 2011, the Sept Iles layered intrusion in Canada (e.g., Namur et al, 2011), the Bushveld Complex in South Africa (e.g., VanTongeren and Mathez, 2012), the Panzhihua intrusive complex in southwestern China (e.g., Zhou et al, 2005Zhou et al, , 2008a and the Damiao complex in North China (e.g., Zhao et al, 2009). However, the mechanism by which they achieved their enrichment in Fe-Ti contents, especially for those developed in a continental regime, remains controversial.…”