Petrology, geochemistry and ReOs isotopes of peridotite xenoliths from Maguan, Yunnan Province: Implications for the Cenozoic mantle replacement in southwestern China

摘要: Abstract Petrology, geochemistry and Re Os isotopes of peridotite xenoliths from Maguan (Yunnan Province) are reported in this paper with the aims constraining age evolution lithospheric mantle beneath western margin Cathyasia block. The contain predominantly fertile lherzolites whole-rock Al2O3 contents 2.42–4.99 wt.%, subordinate clinopyroxene-poor 1.19–1.98 wt.%. Their CaO, Na2O decrease along increase MgO, following melt depletion trends. This suggests that represent residues after variable degrees partial melting. Clinopyroxenes display flat to depleted REE patterns, whereas those variably enriched LREE. Modeling results Y Yb clinopyroxenes suggest have experienced ~ 1–5% melting, contrast ~ 10–15% for lherzolites. Both similarly high equilibrium temperatures, i.e., 911–1120 °C versus 919–941 °C, respectively. 187Os/188Os ratios vary 0.11764 0.12506, which slightly lower than most (0.12272-0.12854). show no correlation 187Re/188Os or bulk-rock contents. rhenium ages (TRD) range 0.15 1.08 Ga, TRD 0.64–1.67 Ga. co-existence Phanerozoic Proterozoic Alternatively, whole was likely formed during Phanerozoic, given resemblance their isotopic abyssal peridotites. latter explanation is consistent fact all studied samples plot oceanic trend a olivine modes Fo We existed block Late Cretaceous Eocene–Oligocene has been replaced by juvenile mantle, probably occurred Cenozoic.