Time scales of melt extraction revealed by distribution of lava composition across a ridge axis
Time scales of melt extraction revealed by distribution of lava composition across a ridge axis
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通过山脊轴上熔岩成分的分布揭示了熔体提取的时间尺度
DOI：
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发表时间：
2010
期刊：
影响因子：
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通讯作者：
M. Kitazawa
中科院分区：
文献类型：
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作者：
C. Cordier;M. Benoit;C. Hemond;J. Dyment;Bernard Le Gall;A. Briais;M. Kitazawa
对缓慢扩张的中印度海脊过去800KYR期间岩浆作用的时间波动进行了研究。这些波动是通过横跨山脊的40公里长的剖面上熔岩化学的变化来记录的。利用磁性微异常准确地恢复了玄武岩的时间关系。我们报道了富含不相容元素的古代熔岩的产出，而轴上的样品则是典型的正常大洋中脊玄武岩。富集型熔岩对称分布在海脊两侧，表明富集型熔体以大约150-200KYR的间隔到达海底。这种周期性被认为是非均质地幔来源产生的熔体聚集过程中的一个特征时间尺度。大洋中脊玄武岩的地球化学变化可能主要反映了这种周期性过程，而不是地幔非均质性的空间分布。
Temporal fluctuations of magmatic processes during the last 800 kyr have been investigated for the slow spreading Central Indian Ridge. The fluctuations are recorded by variations in lava chemistry along a 40 km long profile across the ridge. The temporal relations of the basalts were accurately restored using magnetic microanomalies. We report on the occurrence of ancient lavas enriched in incompatible elements whereas on‐axis samples are typical normal mid‐ocean ridge basalts. The enriched lavas are symmetrically distributed on either side of the ridge, implying that enriched melts reached the seafloor at intervals of about 150–200 kyr. This periodicity is viewed as a characteristic time scale in the aggregation processes of the melts produced from a heterogeneous mantle source. Geochemical variations of zero‐age mid‐ocean ridge basalts may primarily reflect such periodic processes rather than the spatial distribution of mantle heterogeneities.