Isotopic Compositions of Mantle Xenoliths and Age of the Lithospheric Mantle in
详细信息
- 责任者：Zhou Qin (State Key Laboratory of Lithospheric Evolution ; Institute of Geology and Geophysics ; Chinese Academy of Sciences ; 100029 ; China) ; Wu Fuyuan
- 刊名：Acta Petrologica Sinica
- 出版年：2010
- 卷期：26(4)
- 关键词：橄榄岩 ; peridotites ; 岩石圈地幔 ; lithospheric mantle ; 吉林 ; Jilin Province
- 页码：p.1241-1264
- 图表：illus., 8 tables, 63 refs.
- 分类号：0801
- issnNo：ISSN1000-0569
- isbnNo：CN11-1922/P
摘要
Abundant peridotitic xenoliths have been discovered in the Dongxiaoshan basalts of Yitong, Jilin Province. Petrological and mineralogical evidence show that they consist mainly of spinel-bearing lherzolite, with minor harzbrugite and wehrlite. They display different textures, including protogranular, porphyroclastic, mylonitic and diablastic. Major elements and mineral modes indicate that most of these xenoliths are fertile and have experienced small degrees of partial melting. Clinopyroxene trace element compositions suggest that they have been modified by later metasomatism. Equilibrium temperature of the Dongxiaoshan mantle xenoliths have been calculated to range from 989～1 142℃. Based on the geotherm of eastern China, it can be constrained that they were derived from a depth of 40～70 km. Whole-rock Re-Os isotope indicates that the Hthospheric mantle beneath Yitong was mainly formed during Phanerozoic from depleted asthenosphere, as suggested by clinopyroxene Sr-Nd-Hf isotope data. Some xenoliths with Re depletion age of Middle Proterozoic might reflect the ancient mantle domains preserved in the asthenosphere, which have no genetic relation with the overlying crust.