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埃达克岩(adakite)最初是指由消减板片玄武岩物质熔融形成的富硅、富钠、高Sr/Y和La/Yb比值的弧火山熔岩。它通常产在会聚带,这个部位的年轻的、因而仍然是热的大洋板片正在发生俯冲消减。富铌的岛弧玄武岩则是中等到高碱的镁铁质熔岩,它们相对于正常的岛弧玄武岩含有较多的高场强元素(HFSE)。这些玄武岩通常与埃达克岩共生,而这一组合一直被用于论证他们的高HFSE含量是因为他们的地幔源区受到板片来源的熔体的交代。先前的区域研究表明,南菲律宾是埃达克岩和富铌岛弧玄武岩的一个典型产地。然而最近的详细研究显示,尽管该地区的一些岛弧火山岩是类埃达克岩的,但是它们很可能是来自地幔楔的母岩浆的分异作用的产物,而这里的地幔楔主要是受沉积来源的成分交代的,此外,菲律宾南部最典型的富铌熔岩中HFSE的富集,也很有可能是起因于似乎是西太平洋边缘特有的富集地幔组分的熔融。这些结果提出了如下问题:南菲律宾是否存在真正的板片来源的熔体?这里的富铌岛弧熔岩是否起因于地幔楔被这种熔体交代?
Adakite was originally defined as a silicon-rich, sodium-rich, high Sr / Y and La / Yb ratio arc volcanic lava formed by the subtractive plate-basalt melting. It is usually produced in convergent zones, where the young, and thus still hot, oceanic patches are undergoing subduction abates. The niobium-rich island arc basalts are medium to high alkali mafic lavas that contain more HFSE than normal island arc basalts. These basalts are usually symbiotic with adakites and this combination has been used to demonstrate their high HFSE content because their mantle sources are interpreted by plate-sourced melts. Previous regional studies have shown that the southern Philippines is a typical source of adakite and Fu Niu island arc basalts. However, recent detailed studies have shown that although some of the island arc volcanic rocks in the area are adderitic-like rocks, they are most probably the result of the differentiation of parent magma from mantle wedges, where mantle wedges are predominantly deposited In addition, the enrichment of HFSE in the most typical lava niobites in the southern Philippines is most likely due to melting of the mantle enriched components that appear to be characteristic of the western Pacific margins. These results raise the question of whether there is a real sheet-derived melt in the South Philippines, and whether the niobium-rich arc lava here is due to mantle wedge accretion by this melt?