中国大陆科学钻探CCSD-PP3钻孔地幔岩的尖晶石相部分熔融证据

Evidence of spinel facies partial melting of the mantle rocks from the CCSD-PP3 drilling cores.

CCSD PP3超镁铁岩表现为高 Mg 和 Cr,低 Ca 和 Al 特征,是中国东部和超高压变质带上极其罕见的亏损地幔岩,通过地球化学和矿物学和 Re-Os 同位素研究发现岩石来自古元古代岩石圈地幔,并在地幔浅部尖晶石相条件下发生部分熔融,最近一次部分熔融作用发生在中-晚元古代,后经岩石圈厚度加大、拆沉或深俯冲过程,岩石转变为石榴石橄榄岩。

The mantle rocks from the CCSD PP3 drilling cores in the Sulu UHPM belt are characterized by high contents of Mg and low Al and Ca, suggesting a much highly depleted mantle rocks than those in the east of China. Geochemical, mineralogical and Re-Os isotope data indicate that the mantle rocks in PP3 were originated from early Proterozoic lithospheric mantle and partial melted at shallow depth under spinel facies during medium-late Proterozoic time. The spinel facies peridotites were transformed into garnet facies peridotites, due to the deep subduction during the collision between the Yangtze and the North China blocks.