Trace Element Characteristics of Ultramafic Xenoliths in Basaltic Rocks from Penghu Islands, Taiwan
The trace and rare earth elements of ultramafic xenoliths from Peiliao area and combined with major elements proposed by Yang et al. (1987) in order to understand the origin of these ultramafic xenoliths and the geochemical characteristics of the upper mantle. Spinel lherzolite mainly composed of olivine, orthopyroxene, clinopyroxene and spinel is the major rock type of ultramafic xenoliths found in Peiliao area, Penghu Islands, Taiwan. Based on major elements of ultramafic xenoliths analyzed in the present study (Yang et al., 1987), we suggest that these xenoliths belong to the residual upper mantle after different degrees of partial melting. The ultramafic xenoliths have higher MgO content, but lower Al2O3, TiO2 and Na2O contents than primitive mantle proposed by Sun and McDonough (1989), indicating that they represent residues formed by different degrees of partial melting from the upper mantle. Incompatible elements and LREEs tend to decrease with increasing MgO/ΣFeO ratios which may be related to the partial melting of the mantle source. These correlations mentioned above indicate that the ultramafic xenoliths from Peiliao area represent the residual materials after the primitive mantle had undergone partial melting. The spidergrams and the chondrite-normalized REE patterns reveal that ultramafic xenoliths from Peiliao area are depleted which indicate that the mantle beneath the study area had undergone relatively smaller degree of partial melting.
KeywordsPartial Melting Mantle Plume Incompatible Element Basaltic Rock Primitive Mantle
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- 1.Yang, H.J., Chen, J.C., Yang, H.Y.: Geochemistry of ultramafic nodules in basaltic rocks from Peiliao, Penghu Island and Liutsu, Northern Taiwan. Proc. Geol. Soc. China 30, 40–56 (1987)Google Scholar
- 3.Juang, W.S., Chen, J.C.: The nature and origin of Penghu basalts: a review. Bulletin of The Central Geological Survey (12), 147–200 (1999)Google Scholar
- 5.Yang, H.Y., Chen, C.H., Tsai, C.L.: Ultramafic xenoliths in the basaltic rocks on Penghu Islands. Acta Geol. Taiwanica 21, 68–80 (1982)Google Scholar
- 6.Wang, K.L., O’Reilly, S.Y., Honda, M., Matsumoto, T., Griffin, W.L., Pearson, N.J., Zhang, M.: Co-rich sulfides in mantle periodtites from Penghu Islands, Taiwan: Footprints of Proterozoic mantle plumes under the Cathaysia Block. Journal of Asian Earth Sciences 37, 229–245 (2010)CrossRefGoogle Scholar
- 9.Smith, S.D.: The geodynamic significance of the DUPAL anomaly in Asia. In: Flower, M.F.J., Chung, S.L., Lo, C.H., Lee, T.T. (eds.) Mantle Dynamics and Plate Interactions in East Asia. Geodynamics Series, vol. 29, pp. 89–105. American Geophysical Union (1998)Google Scholar
- 14.Ho, K.S., Chen, J.C.: Petrology and chemistry of ultramafic nodules in kimberlite from South Aferica. Bulletin of the National Museum of Natural Science 1, 111–128 (1989)Google Scholar