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地幔底部异常区域的形成和存活的物化机理分析

Keywords: 地幔底部,横向组分不均匀性,异常区域,相分离,粘性,幔对流

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Abstract:

解读地幔内部的横向不均匀结构中所反映出它的物理化学性质的变化信息是人们探究地幔精细构造的关键.依据地幔矿物物理学的理论和一些地球物理观测结果(δlnρ>0,δlnV>0,δlnVs0),估计了在太平洋中部以及非洲大陆下靠近地幔底部的异常区域内铁和硅的含量变化的比值范围.结果表明,在那些异常区域内铁和硅的含量同时增加,它可能与方镁铁矿在地幔底部温压条件下发生相分离相关.实验证实在那些条件下方镁铁矿(Mg,Fe)O能分解为一个较轻的富含镁相和一个较重的富含铁相,并且较轻的富含镁相可以随地幔上

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