Variation of melting processes and magma sources of the early Deccan flood basalts, Malwa Plateau, India
Variation of melting processes and magma sources of the early Deccan flood basalts, Malwa Plateau, India
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DOI：
10.1016/j.epsl.2019.115711
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发表时间：
2019-10-15
影响因子：
5.3
通讯作者：
de Wall, H.
中科院分区：
文献类型：
--
作者：
Haase, K. M.;Regelous, M.;de Wall, H.
德干洪水玄武岩覆盖了印度的大部分地区，是地球上最大的火山省份之一。我们提供了马尔瓦高原德干北部磁性定义的熔岩地层剖面的地球化学和同位素数据，其年龄类似于67.5 Ma。因此，这些是一些最古老的德干熔岩，在更南边的主要德干熔岩单元之前喷发。尽管年轻的马尔瓦高原熔岩遭受了至少两种不同地壳成分的显著地壳污染，但较老的、碱性较强的熔岩受到的污染较少，其同位素和微量元素组成与留尼汪洋板内玄武岩相似。因此，我们的数据为留尼汪岛热点对德干早期洪泛玄武岩的形成做出了贡献提供了地球化学证据。大多数熔岩反映了不到10%的地壳熔体的分离结晶和同化作用，但具有最高二氧化硅和锶同位素组成的样品遭受了更严重的地壳污染。马尔瓦高原受污染程度最低的玄武岩的成分表明，从底部到顶部，部分熔融程度显着增加。马尔瓦高原大部分玄武岩岩浆是由
The Deccan flood basalts cover large parts of India and represent one of the largest volcanic provinces on Earth. We present geochemical and isotopic data on a magnetically defined stratigraphic section of lavas from the northern portion of the Deccan, the Malwa Plateau, which are dated at similar to 67.5 Ma. These are therefore some of the oldest Deccan lavas, erupted before the Main Deccan units further to the south. Although the younger Malwa Plateau lavas have undergone significant crustal contamination by at least two distinct crustal components, the older, more alkalic lavas are less contaminated and have similar isotope and trace element compositions to Reunion oceanic intraplate basalts. Our data therefore provide geochemical evidence for a contribution of the Reunion hotspot to the generation of the early Deccan flood basalts. Most lavas reflect fractional crystallization and assimilation of less than 10% of a crustal melt but samples with the highest SiO2 and Sr isotope compositions underwent more extreme crustal contamination. The composition of the least contaminated basalts from the Malwa Plateau suggests that the degree of partial melting increased significantly from the base to the top of the section. Most Malwa Plateau basaltic magmas formed by