大陆岩石圈地幔形成与演化研究的新进展

New Progress of the Formation and Evolution of Sub-Continental Lithospheric Mantle

研究大陆岩石圈地幔形成与演化的主要途径是利用岩石 地球化学探针研究幔源橄榄岩的年龄、组成及其演化 .目前多将岩石圈地幔划分为大洋型和克拉通型 ,并认识到 ,岩石圈地幔的矿物相、成分、年龄在垂向上具有分层性 ;根据研究资料 ,目前已提出了以熔体抽取为岩石圈地幔形成的主要方式 ,并通过交代、拆沉等过程使岩石圈地幔遭受改造 .中国东部岩石圈地幔的成分主体上是饱满的 ,与其上的太古代地壳并不协调 ,一些研究者提出了岩石圈拆沉和地幔置换两种具有代表性的模型来解释岩石圈地幔成分的这种特点 .人们对中国东部岩石圈地幔作了大量的研究工作 ,然而 ,若要形成较为合理的解释 ,还需应用新技术 (如 ,Re/Os同位素技术 )做进一步的工作 .

The main way for detecting the formation and evolution of sub-continental lithospheric mantle (SCLM) is to research the age, composition and evolution of mantle-derived peridotite xenoliths by petrological-geochemical probe. Up to now it is generally accepted that the SCLM can be divided into two types: oceanic and cratonic lithospheric mantles. Furthermore, the SCLM exhibits vertical stratification in mineral phases, chemical compositions and ages. It is proposed that the SCLM was formed by the melt extraction and could be modified by metasomatism and delamination afterward. The SCLM beneath Eastern China is generally fertile, which is not consistent with the overlying Archaean crust. Therefore, it is proposed that delamination or replacement should be responsible for such decoupling. Although a great deal of work were carried out, some new technology (such as Re/Os isotopic systematics ) are necessary before a reasonable explanation is obtained for the SCLM beneath Eastern China.