Noble gas isotopes in corundum and peridotite xenoliths from the eastern North China Craton: Implication for comprehensive refertilization of lithospheric mantle

• Published in: Physics of the earth and planetary interiors Vol. 189; no. 3; pp. 185 - 191
• Main Authors: He, Huaiyu, Zhu, Rixiang, Saxton, John
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.12.2011
• Subjects: Corundum; Helium isotope; North China Craton; Peridotite xenoliths; Titanomagnetite megacrystal; Corundum; North China Craton; Titanomagnetite megacrystal; Helium isotope; Peridotite xenoliths
• ISSN: 0031-9201; 1872-7395
• DOI: 10.1016/j.pepi.2011.09.001

Noble gas isotopic ratios provide unique and important constraints for the evolution of the subcontinental mantle. We present one-step crushing noble gas isotope data from corundum and co-existing mantle xenoliths and megacrystals from the Changle volcanic fields in the middle part of the Tan-Lu Fault Zone, eastern North China Craton. The 3He/ 4He ratio is 7.6–8.3 times the atmospheric ratio (Ra) in corundum, indicating contributions of fluids from convective asthenosphere. The 3He/ 4He ratio in titanomagnetite megacrystals ranges from 5.8 to 6.5 Ra, suggesting possible U–Th contamination in the crystal lattice, with the 3He/ 4He ratio of host magma being higher than 6.5 Ra. The olivine and opx in lherzolite show high helium contents and homogeneous isotopic helium ratios (6.9–7.0 Ra). The cpx in wehrlite show significantly higher helium contents and slightly higher helium ratio (7.6 Ra) than co-existing olivine (7.0–7.5 Ra). Combined with isotope correlation diagrams, the systematic difference in 4He abundance, the 3He/ 4He and 4He/ 40Ar ∗ ratios of cpx, opx and olivine in pyroxenite, lherzolite and wehrlite suggest comprehensive refertilization of lithospheric mantle in the eastern North China Craton.