Comparative Geochemical Study of the Tertiary and Quaternary Lavas of Western Senegal and the Cape Verde Islands: Geodynamic Implications

作     者：Diomaye Yatte Dinna Pathé Diallo Ibrahima Sagna 

作者机构：Département de Géologie Université Cheikh Anta Diop Dakar Sénégal Institut Fondamental d’Afrique Noire (IFAN) Université Cheikh Anta Diop Dakar Sénégal 

出 版 物：《International Journal of Geosciences》 (地球科学国际期刊（英文）)

年 卷 期：2015年第6卷第11期

页      面：1193-1213页

学科分类：0709[理学-地质学] 081803[工学-地质工程] 07[理学] 08[工学] 0818[工学-地质资源与地质工程] 

主　　题：Western Senegal Basalts Tertiary Quaternary Cape Verde 

摘      要：The western area of Senegal was the site of a basic volcanism in the Tertiary and Quaternary. That volcanism had caused the formation of alkaline olivine basalts, basanites and nephelinites from microlitic and porphyritic texture to dolerite texture. The geochemistry of major elements shows that the Quaternary basalts are more aluminous and more siliceous, but they contain less magnesium, less iron and less calcium than the Tertiary basalts. Two types of basalt occur here, based on the characteristics of the major elements in the Tertiary lavas: the highly undersaturated basalts of the Cape Verde Peninsula and the slightly undersaturated basalts of the Thiès Plateau. The characteristics of the trace elements reveal shallow interactions due to the contamination and/or assimilation, and to the fractional crystallization, but not due to the heterogeneity of the source. The strong enrichment in light rare earth elements (LREE) and the slight enrichment in heavy rare earth elements (HREE), the anomalies which are negative in K and Pb and positive in Nb, Ta and Eu of the Tertiary and Quaternary basalts of Western Senegal and similar anomalies of the same elements (Pb not analyzed) described in the Cape Verde islands, allow us to establish links between the petrogenetic mechanisms that had caused the formation of the basalts of this Islands and Western Senegal. Moreover, the volcanic activity in Western Senegal (of continental lntraplate type) and that of the Cape Verde Islands (oceanic intraplate type) are probably related to the hot spot located on the vertical of the Cape Verde.