| 北山地区辉长岩类的地球化学特征及其深部信息 |
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| 关键词:trace elements geo-settings gabbro Beishan area |
| 基金项目:本文由科技部国际合作重点项目（编号：2002CB714004 )资助。 |
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| Geochemical Characteristics of Gabbros in Beishan Area and Their Deep Setting Implications |
| Being the main type of mafic and ultramafic rocks in Beishan area, the gabbros can be divided into three groups according to the rare earth element patterns. The first group has high concentration of total REE, with the enrichment and obvious fractionation of LREE. The second group with the lower total REE content than the first group has a smooth REE pattern. The third group is slightly depleted in LREE and has the low total REE concentration. The gabbros from Beishan area are obviously enriched in LILE such as Cs, U and Pb and depleted in HFSE like Nb (some samples are depleted in Ta, Ti and Zr)，which implies that gabbros are somewhat subduction-related. BothεNd (0) aridεNd (t) are positive, suggesting that the primary magma was derived from sources of depleted mantle. The obvious linear correlation between ratios of Th/Sm and Th/Nb shows continental hybrid processes. Geochemical characteristics indicate that gabbros were farmed at different sub-settings along the active continental margin. The primary magma assimilated the continental wall rock during its migration to the present site, which changed the composition of the primary magma The gabbros resulted from the evolution of the hybrid magma. The Sm-Nd model age of the depleted mantle (tDM) can not represent the chronological age of the gabbros. |
| FAN Yuxin,BAI Yunlai,CHEN Fahu.2005.Geochemical Characteristics of Gabbros in Beishan Area and Their Deep Setting Implications[J].Acta Geoscientica Sinica,26(z1):61-66. |
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