The Petrology and Geochemistry of Volcanic Rocks on Jeju Island: Plume Magmatism along the Asian Continental Margin
The Petrology and Geochemistry of Volcanic Rocks on Jeju Island: Plume Magmatism along the Asian Continental Margin
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DOI：
10.1093/petrology/egh087
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发表时间：
2004-11
影响因子：
3.9
通讯作者：
Y. Tatsumi;H. Shukuno;M. Yoshikawa;Q. Chang;Keiko Sato;Moontaek Lee
中科院分区：
文献类型：
--
作者：
Y. Tatsumi;H. Shukuno;M. Yoshikawa;Q. Chang;Keiko Sato;Moontaek Lee
济州岛火山岩的不相容元素特征与典型的板内岩浆一致。这些火山岩的来源可能是地幔柱，位于西南日本弧的后面。济州地幔柱岩浆可分为三个系列，主要和微量元素丰度的基础上：高铝碱性，低铝碱性，亚碱性。质量平衡计算表明，每个岩浆系列内的成分变化在很大程度上是由三个化学性质不同的母岩浆的分离结晶。这些系列的原生岩浆的成分，推断残留地幔橄榄石组合物，表明低铝碱性和亚碱性岩浆产生在最深和最浅的深度，分别由最低和最高程度的熔融。这些估计，再加上系统的微量元素和同位素组成的差异，表明济州岛下的上地幔的特点是增加的交代程度和变化的主要交代含水矿物角闪石金云母与深度减少。原始地幔柱物质具有相当贫化的地球化学特征，夹带较浅的交代的上地幔物质，并分离出最不富集的低铝碱性、中等富集的高铝碱性和高度富集的亚碱性岩浆，深度逐渐减小。
The incompatible element signatures of volcanic rocks forming Jeju Island, located at the eastern margin of the Asian continent, are identical to those of typical intraplate magmas. The source of these volcanic rocks may be a mantle plume, located immediately behind the SW Japan arc. Jeju plume magmas can be divided into three series, based on major and trace element abundances: high-alumina alkalic, low-alumina alkalic, and sub-alkalic. Mass-balance calculations indicate that the compositional variations within each magma series are largely governed by fractional crystallization of three chemically distinct parental magmas. The compositions of primary magmas for these series, using inferred residual mantle olivine compositions, suggest that the low-alumina alkalic and subalkalic magmas are generated at the deepest and shallowest depths by lowest and highest degrees of melting, respectively. These estimates, together with systematic differences in trace element and isotopic compositions, indicate that the upper mantle beneath Jeju Island is characterized by an increased degree of metasomatism and a change in major metasomatic hydrous minerals from amphibole to phlogopite with decreasing depth. The original plume material, having rather depleted geochemical characteristics, entrained shallower metasomatized uppermost mantle material, and segregated least-enriched low-alumina alkalic, moderately enriched high-alumina alkalic, and highly enriched sub-alkalic magmas, with decreasing depth.