岩浆过程中铁同位素的地球化学行为

朱祥坤++孙剑++王跃



5结语
铁是主量元素和变价元素,在岩浆成因与演化、岩理学、构造岩石学、成矿作用等研究方面具有重要意义。查明岩浆过程中铁同位素的地球化学行为是正确运用铁同位素对相关地质问题进行制约的前提。目前人们对岩浆过程中的铁同位素基本行为已有了概略性了解,但许多问题仍待进一步研究。例如,在矿物方面,主要含铁矿物间铁同位素的平衡分馏顺序已基本建立,但其间同位素分馏大小及其与氧逸度、温度、压力等条件的关系还有待精确确定,同时,这方面的知识是运用同位素反演岩浆演化过程的基础。在基性岩浆体系方面,目前人们对铁同位素地球化学行为的认识主要来自于对富含氧化物的镁铁—超镁铁质层状岩体的调查,但对斜长岩杂岩体和富含硫化物岩体的铁同位素研究还几乎是空白,这些岩体可能由不同类型的岩浆演化而来,铁同位素在这些不同类型的岩浆演化过程中的行为有何差异?熔离是岩浆演化的重要过程之一,也是岩浆矿床形成的重要机制,可否运用铁同位素对岩浆是否发生过熔离进行制约?目前人们对熔离过程中的铁同位素地球化学行为仍然不清楚,不同的大地构造环境形成不同的岩浆岩岩石组合,铁同位素是否对岩石组合形成的大地构造背景具有指示意义也是值得进一步研究的重要问题。
岩浆过程的铁同位素研究不仅对于丰富和完善非传统稳定同位素地球化学理论体系具有重要意义,而且对于理解地球的岩浆作用和地幔作用过程、示踪岩浆型矿床的物质来源和成矿过程等方面具有重要潜力。可以预见,随着铁同位素测试技术的逐渐普及,人们对铁同位素的地球化学研究将会深入和广泛。
参考文献:
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