Elemental and Sr-Nd isotope geochemistry of microgranular enclaves from peralkaline A-type granitic plutons of the Emeishan large igneous province, SW China

Microgranular enclaves are common within intermediate to felsic granitic rocks that have I- and S-type affinity however they are rare within alkaline anorogenic granitoids of A-type affinity The Permian (similar to 260 Ma) Emeishan large igneous province (ELIP) of southwest China contains two peralkaline silica saturated A-type granitic plutons that host microgranular enclaves. The enclaves from the Baima pluton are intermediate in composition and have lower SiO(2) and higher TiO(2), CaO and Mg# (SiO(2)= 57.2 to 63.0 wt.%, TiO(2)= 0.8 to 1 8 wt.%, CaO= 1 7 to 33 wt.%, Mg# 28 to 44) than their host (SiO(2)= 626 to 67.8 wt %, TiO(2) = 0.5 to 1 4 wt.%; CaO= 04 to 1 8 wt.%; Mg# = 15 to 31). The enclaves from the Taihe pluton are more felsic (SiO(2)= 63.8 to 71 3 wt %. TiO(2)= 0.3 to 06 wt %, CaO= 06 to 2.3 wt %, Mg# = 8 to 22) but are still less evolved than their host (SiO(2)= 698 to 75 1 wt.%, TiO(2)= 0.2 to 06 wt %, CaO= 04 to 0.8 wt %, Mg# =3 to 12). In both cases, the enclaves have very similar epsilon Nd((T)) values (Baima epsilon Nd((T))= +2 8 to + 3.2, Taihe epsilon Nd((T)) = +1.0 to +2.0) as their hosts (Baima epsilon Nd((T)) = +3 0 to +3 2, Taihe epsilon Nd((T)) = + 1.5 to + 1 9). The major and trace element trends of the enclave-host pairs suggest that fractional crystallization occurred and that element diffusion was likely minimal The enclaves are Interpreted as entrained accumulations of early formed crystals of a silicic magma which was originally produced by fractional crystallization of a mafic magma (C) 2010 Elsevier B.V. All rights reserved.