Relative roles of source composition, fractional crystallization and crustal contamination in the petrogenesis of Andean volcanic rocks
Relative roles of source composition, fractional crystallization and crustal contamination in the petrogenesis of Andean volcanic rocks
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DOI：
10.1098/rsta.1984.0014
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发表时间：
1984-04
期刊：
影响因子：
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通讯作者：
R. Thorpe;Peter Francis;L. O'callaghan
中科院分区：
文献类型：
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作者：
R. Thorpe;Peter Francis;L. O'callaghan
北方钙碱性玄武岩-安山岩-英安岩-流纹岩组合的化学和同位素特征存在明显差异，中央的和南部火山带（s.v.z.）南美洲的安第斯山脉。碱性玄武岩-粗面岩组合的火山岩出现在这些活火山带的内部和东部。n.v.z.的化学和同位素特征。玄武安山岩和安山岩以及s.v.z.玄武岩、玄武安山岩和安山岩与玄武质母岩浆的分离结晶相一致，玄武质母岩浆是由含有俯冲洋壳岩石圈成分的软流圈地幔楔部分熔融形成的。相反，碱性熔岩来自于具有“板内”特征的地幔形成的玄武质母岩浆。从Cerro Galan火山中心到c.v.z.东南部的近代玄武安山岩来自于地幔，同时含有俯冲带和板内组分，并经历了同化和分离结晶（a.f.c.）在大陆地壳的上升过程中cvz玄武安山岩来源于地幔，含俯冲带成分，可能伴有a.f.c.在大陆地壳中。一些CV熔岩和火山碎屑岩显示了岩浆混合的岩石学和地球化学证据。CVZ的岩石成因。因此，熔岩是一个复杂的过程，在这个过程中，来自非均匀地幔的岩浆在上升穿过大陆地壳的过程中经历了同化、分离结晶和岩浆混合。
There are well established differences in the chemical and isotopic characteristics of the calc-alkaline basalt—andesite-dacite-rhyolite association of the northern (n.v.z.), central (c.v.z.) and southern volcanic zones (s.v.z.) of the South American Andes. Volcanic rocks of the alkaline basalt-trachyte association occur within and to the east of these active volcanic zones. The chemical and isotopic characteristics of the n.v.z. basaltic andesites and andesites and the s.v.z. basalts, basaltic andesites and andesites are consistent with derivation by fractional crystallization of basaltic parent magmas formed by partial melting of the asthenospheric mantle wedge containing components from subducted oceanic lithosphere. Conversely, the alkaline lavas are derived from basaltic parent magmas formed from mantle of ‘within-plate’ character. Recent basaltic andesites from the Cerro Galan volcanic centre to the SE of the c.v.z. are derived from mantle containing both subduction zone and within-plate components, and have experienced assimilation and fractional crystallization (a.f.c.) during uprise through the continental crust. The c.v.z. basaltic andesites are derived from mantle containing subduction-zone components, probably accompanied by a.f.c. within the continental crust. Some c.v.z. lavas and pyroclastic rocks show petrological and geochemical evidence for magma mixing. The petrogenesis of the c.v.z. lavas is therefore a complex process in which magmas derived from heterogeneous mantle experience assimilation, fractional crystallization, and magma mixing during uprise through the continental crust.