Laser ablation MC-ICP-MS was used to measure the Os-isotope compositions of single sulfide grains, including laurite (RuS₂) and pentlandite [(Fe,Ni)₉S₈], from two chromitite bodies and host lherzolites from ophiolites of North Andaman (Indo-Burma-Sumatra subduction zone). The results show isotopic heterogeneity in both laurite (n = 24) and pentlandite (n = 37), similar to that observed in other chromitites and peridotites from the mantle sections of ophiolites. Rhenium-depletion model ages (T_RD) of laurite and pentlandite reveal episodes of mantle magmatism and/or metasomatism in the Andaman mantle predating the formation of the ophiolite (and the host chromitites), mainly at ≈0.5, 1.2, 1.8, 2.1 and 2.5 Ga. These ages match well with the main tectonothermal events that are documented in the continental crustal rocks of South India, suggesting that the Andaman mantle (or its protolith) had a volume of lithospheric mantle once underlaying this southern Indian continental crust. As observed in other oceanic lithospheres, blocks of ancient subcontinental lithospheric mantle (SCLM) could have contributed to the development of the subduction-related Andaman–Java volcanic arc. Major- and trace-element compositions of chromite indicate crystallization from melts akin to high-Mg IAT and boninites during the initial stages of development of this intra-oceanic subduction system.

中文翻译：

---

印度安达曼蛇绿岩的辉绿岩和寄主锂铁矿中硫化物的Re-Os同位素体系。

激光烧蚀MC-ICP-MS用于测量单个硫化物晶粒的Os同位素组成，包括两个铬铁矿体中的月桂石（RuS ₂）和方铁矿[（Fe，Ni）₉ S ₈ ]以及来自蛇绿岩中的蛇绿石的主体锂铁矿。北安达曼（印度－缅甸－苏门答腊俯冲带）。结果表明，在月桂石（n = 24）和膨润土（n = 37）中，同位素异质性均与蛇绿岩地幔剖面中的其他铬铁矿和橄榄岩类似。耗尽模型年龄（T _RD的月桂石和方铁矿揭示了安达曼地幔中地幔岩浆作用和/或交代作用的发生，早于蛇绿岩（和主体铬铁矿）的形成，主要发生在≈0.5、1.2、1.8、2.1和2.5 Ga。这些年龄与印度南部大陆地壳岩石中记录的主要构造热事件，表明安达曼地幔（或其原岩）一旦覆盖了印度南部大陆地壳，便具有大量岩石圈地幔。正如在其他海洋岩石圈中所观察到的那样，古老的亚大陆岩石圈地幔（SCLM）块可能有助于俯冲相关的安达曼－爪哇火山弧的发展。