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标题：Geochemistry of the volcanic rocks from Bioko Island (“Cameroon Hot Line”): Evidence for plume-lithosphere interaction
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作者：Fadimatou Ngounouno Yamgouot ; Fadimatou Ngounouno Yamgouot ; Bernard Déruelle 等
期刊名称：Geoscience Frontiers
印刷版ISSN：1674-9871
出版年度：2016
卷号：7
期号：5
页码：743-757
DOI：10.1016/j.gsf.2015.06.003
语种：English
出版社：Elsevier
摘要：Abstract Bioko Island (3008 m a.s.l) is located in the presently more active volcanic zone of the Cameroon Line and composed essentially of alkaline basalts and hawaiites, and lesser mugearites. The rocks show microlitic porphyritic texture with phenocrysts of olivine (83% < Fo < 87%) and clinopyroxene in a matrix of plagioclase, clinopyroxene and oxides. Hawaiites and mugearites also include phenocrysts of plagioclase (An62-67Ab35-32Or3-1). Major element variation diagrams show an increase in SiO2, Al2O3, Na2O and K2O with increasing MgO for the studied rock groups. The rocks are characterized by low (86Sr/87Sr) i ratios (0.70320–0.70406), high ɛ Nd(t) values (2.56–4.33) and high (206Pb/204Pb) i ratios (20.032–20.035) values. Basalts are enriched in LILE and LREE, and have (Hf/Sm)N = 0.57–1.16. These geochemical signatures are similar to those of the Mount Cameroon rocks, and might be attributed to low degrees of partial melting from a garnet-amphibole-bearing mantle source. The trace elements and isotopic compositions suggest that the parental magma source might have involved HIMU- and EM1-components. Graphical abstract Display Omitted Highlights • Bioko Island is composed essentially of alkaline basaltic rocks. • The geochemical signatures might be attributed to low degrees of partial melting. • The parental magma source might have involved HIMU- and EM1- components.
关键词：Geochemistry; HIMU-EM1; Volcanic rocks; Bioko; Cameroon Hot Line;