Water Contents in Peridotite Xenoliths from Subei Basin, Eastern China

• 责任者：Lei Nengzhong (Department of City Construction and Environmental Science ; West Anhui University ; Liu’an 237012 ; China) ; Xia Qunke
• 刊名：Earth Science
• 出版年：2009
• 卷期：34(1)
• 关键词：橄榄岩 ; peridotites ; 结构水 ; constitutional water ; 苏北盆地 ; Subei Basin
• 页码：p.75-88
• 图表：6 illus., 8 tables, 44 refs.
• 分类号：0801
• issnNo：ISSN1000-2383
• isbnNo：CN42-1233/P

Nominally anhydrous minerals, clinopyroxene (Cpx), orthopyroxene (Opx) and olivine (O1), in peridotite xenoliths hosted by Cenozoic basalts from Panshishan, Lianshan and Fangshan of the Subei basin, eastern China have been investigated by Micro-FTIR for their water contents. All Cpx and Opx grains contain a certain amount of “water” as hydroxyl defect in the crystal structure. Based on the new results from the Suhei basin and the data reported in literatures, the partition coefficient of H₂O between Cpx and Opx in the continental lithosphere mantle is estimated to be 2.2+0.4. This difference is probably induced by the thermal erosion of asthenosphere during Mesozoic-Cenozoic period in the North China block. If this explanation is correct, the present lithosphere mantle in the North China block is mainly the relict after the Mesozoic lithospheric thinning, rather than the new accreted mantle.