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首页> 外文期刊>Lithos: An International Journal of Mineralogy, Petrology, and Geochemistry >Petrology and geochemistry of Alkaline Basalts and Gabbroic xenoliths from Utila Island (Bay Islands, Honduras): Insights into back - Arc processes in the Central American Volcanic Arc
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Petrology and geochemistry of Alkaline Basalts and Gabbroic xenoliths from Utila Island (Bay Islands, Honduras): Insights into back - Arc processes in the Central American Volcanic Arc

机译:来自Utila Island(海湾岛,洪都拉斯)碱性玄武岩和Gabbroco的地球化学和Gabbroicals):中美洲火山弧中的回弧过程见解

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摘要

The island of Utila (Bay islands, Honduras), is situated in a back-arc environment, behind the Central American Volcanic Arc (CAVA). The Utila Volcanic Center (UVC) is Quaternary in age, based on geologic and stratigraphic relations with underlying carbonate rocks and is made up of three distinct, volcanic units: palagonite lapilli tuff, main lava flow and vent fades (in stratigraphic order). The UVC contains gabbroic xenoliths up to 5 cm in size embedded in lapilli and ash tuff. Alkaline basaltic (trachybasalt) flows are porphyritic extrusive rocks with phenocrysts composed of olivine, clinopyroxene, plagioclase and rare kaersutite. Gabbros are composed of amphibole, plagioclase, clinopyroxene, olivine, and Fe-Ti oxides. Primitive mantle normalized trace element patterns show enrichment in Ba, Nb, Ta and light rare earth elements (LREEs) similar to ocean island basalts (OIB) and share trace and major element characteristics similar to high-Nb basalt (HNB). Both basalts and gabbros Sr, Nd and Pb isotopes are distinct from OIB mantle sources in the Central American-Southern Caribbean region but similar to the Pacific MORB (Cocos Plate). A combination of OIB-like trace element characteristics and mid-ocean ridge basalt (MORB) -like isotopic ratios suggest that the UVC basalts originate from an enriched mantle source created by the hybridization of a depleted sub-arc mantle wedge in an earlier subduction stage of the CAVA. (C) 2019 Elsevier B.V. All rights reserved.
机译:伊利亚岛(湾群岛,洪都拉斯),位于中美洲火山弧(Cava)后面的后弧环境。 Uthera火山中心(UVC)是根据与碳酸盐岩石的地质和地层关系的第四纪,由三个不同的火山单位组成:Paloganite Lapilli Tuff,主要的熔岩流和鼻孔(在地层顺序中)。 UVC含有嵌入Lapilli和Ash Tuff的尺寸高达5厘米的咯咯型Xenoliths。碱性玄武岩(Trachybasalt)流量是卟啉肌岩,其具有由橄榄石,临床,普发基酶和罕见的观光蛋白组成的PhenCrysts。 Gabbros由锥形,普拉基酶,临床,橄榄石和Fe-Ti氧化物组成。原始地幔标准化痕量元素模式显示Ba,Nb,Ta和轻稀土元素(Lrees)的富集,类似于海洋岛屿基础(OIB),并与高NB玄武岩(HNB)共享痕量和主要元素特性。玄武岩和Gabbros SR,Nd和Pb同位素都与中美洲 - 南加勒比地区的Oib Mantle来源不同,但与太平洋Morb(Cocos Plate)类似。 oib样痕量元素特征和中海脊玄武岩(Morb)的组合表明,UVC基础源自富含富含耗尽的亚弧地幔楔形的富含富抗体源的富集的地幔源在早期的俯冲阶段豚鼠。 (c)2019年Elsevier B.V.保留所有权利。

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