Geological Magazine, 2010, 147(2): 161-170

Zoned olivine xenocrysts in a late Mesozoic gabbro from the southern Taihang Mountains: implications for old lithospheric mantle beneath the central North China Craton

JI-FENG YING*, HONG-FU ZHANG, and YAN-JIE TANG

Abstract

Zoned olivine grains are abundant in the late Mesozoic Shatuogabbro (southern Taihang Mountains, central North China Craton).Olivine cores are rich in MgO and NiO, rims are rich in FeOand MnO, and both cores and rims have very low CaO contents.The cores invariably have a high Mg no. (92–94), similarto olivine xenocrysts from Palaeozoic kimberlites in easternChina. The compositional features of these olivines imply thatthey are xenocrysts rather than phenocrysts, namely, disaggregatesof mantle peridotites at the time of intrusion. The compositionalsimilarity of olivine cores to xenocrysts from Palaeozoic kimberlitessuggests that the lithospheric mantle beneath the central NorthChina Craton is ancient and refractory in nature, and quitedifferent from eastern China, where the mantle is mainly composedof newly accreted materials resulting from large-scale lithosphericremoval and replacement. The contrasting features of the lithosphericmantle beneath the eastern and central North China Craton implythat the large-scale lithospheric removal in Phanerozoic timeswas mainly confined to the eastern North China Craton.

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