Intensive Variables in Kimberlite Magmas, Lac de Gras, Canada and Implications for Diamond Survival

The evolution of calcite-bearing kimberlites by melt-rock reaction: evidence from polymineralic inclusions within clinopyroxene and garnet megacrysts from Lac de Gras kimberlites, Canada

“…Its kimberlite pipes define a 100-km by 200-km northwest-trending zone (Lockhart et al 2004). The generally small pipes (2-12 ha surface area) intrude into metamorphosed Archean basement rock and are overlain by Quaternary glacial deposits (Fedortchouk and Canil 2004;Nowicki et al 2004). For a detailed description of Diavik and Ekati kimberlites, the reader is referred to Moss et al (2008) and Nowicki et al (2004), respectively.…”

“…The LDG kimberlitic olivine data can be divided into two main trends: (1) cores with high NiO (and low CaO) at variable Mg/(Mg + Fe) (Mg#) and (2) rims with decreasing NiO (and increasing CaO) at relatively constant Mg# (arrow in Fig. 5a) (e.g., Fedortchouk and Canil 2004;Brett et al 2009;Bussweiler et al 2015).…”

Diamond resorption features as a new method for examining conditions of kimberlite emplacement

“…However, there are important mineralogical differences between these three pipes and some transitional features to higher CO 2 /H 2 O ratio in Misery East kimberlite (Armstrong et al 2004). Crystallization T calculated from olivine-spinel geothermometry is similar for the three pipes: 1020-1120 °C (median 1078 °C, n = 13) for Grizzly and 1050-1140 °C (median 1112 °C, n = 11) for Misery (Fedortchouk and Canil 2004;Fedortchouk et al 2005). Our earlier study of resorption morphology of diamonds from both volcaniclastic and coherent kimberlites from Ekati Mine used only optical microscope and SEM and found that all studied resorption morphologies resembled the products of H 2 O experiments indicating predominantly aqueous fluid (Fedortchouk et al 2010).…”

Geochemistry of the Abulangdang intrusion: Cumulates of high-Ti picritic magmas in the Emeishan large igneous province, SW China

“…Several studies indicate that low-Ca olivine can form from many different types of primitive mantle-derived magmas, such as carbonatite, kimberlite and low-Ca boninite varieties (e.g., Crawford, 1980;Walker and Cameron, 1983;Fedortchouk and Canil, 2004;Kamenetsky et al, 2006). Low-Ca olivine grains are in fact common in the mafic-ultramafic intrusions of the ELIP, such as those in the Ni-Cu-(PGE) sulfidebearing Jinbaoshan, Limahe and Nantianwan intrusions and the Fe-Ti oxide-bearing Panzhihua and Hongge intrusions Pang et al, 2008a;Tao et al, 2008;Pang et al, 2009;Wang et al, 2012) and mafic dikes in the Funing region (Wang et al, 2011).…”