Petrogenetic modelling of Quaternary post-collisional volcanism: a case study of central and eastern Anatolia
Petrogenetic modelling of Quaternary post-collisional volcanism: a case study of central and eastern Anatolia
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第四纪碰撞后火山作用的岩石成因模型：安纳托利亚中部和东部的案例研究
作者：
P. Şen;A. Temel;A. Gourgaud
在新近纪-第四纪期间，土耳其发生了广泛的与大陆碰撞有关的火山活动。在安纳托利亚中部，钙碱性至碱性火山活动开始于中新世中晚期。在这里，我们报告微量元素和同位素数据从第四纪样品从中部和东部安纳托利亚。来自安纳托利亚中部的大多数镁铁质熔岩是玄武岩和玄武安山岩，少量的玄武粗安岩和安山岩。所有岩浆类型都表现出富集大离子亲石元素（Sr、Rb、Ba和Pb）相对于高场强元素（Nb、Ta）的特征。微量元素模式具有高Ba/Nb和Th/Nb比值的陆缘火山作用特征。安纳托利亚中部熔岩的87 Sr/86 Sr和143 Nd/144 Nd同位素比值分别为0.704105-0.705619和0.512604-0.512849。安纳托利亚东部第四纪碱性火山活动与阿拉伯板块和欧亚板块的碰撞密切相关。Karacadadaiti火山岩和Tendürek火山岩分别以碱性玄武岩和玄武粗安岩为代表。正如从其碱性性质所预期的那样，它们含有高丰度的LIL元素，但Tendürek熔岩也显示出Nb和Ta的亏损，表明地壳污染在这些岩浆演化中的作用。卡拉卡达火山熔岩的87 Sr/86 Sr和143 Nd/144 Nd比值分别为0.703512 ~ 0.704466、0.512742 ~ 0.512883和0.705743 ~ 0.705889和0.512676。岩石成因模型已被用来限制源特性的中部和东部安纳托利亚火山岩。微量元素比值图和稀土元素模型表明，中部安纳托利亚火山活动是从岩石圈地幔源，记录了以前的俯冲事件之间的非洲-阿拉伯和欧亚板块在始新世至中新世的时间。相反，阿拉伯前陆的卡拉卡达基碱性玄武质火山作用来自类似OIB的地幔源区，地壳混染有限。Tendürek火山作用位于Bitlis冲断带以北的加厚地壳上，通过小程度（1.5%）的部分熔融来自岩石圈地幔。
Extensive continental collision-related volcanism occurred in Turkey during Neogene–Quaternary times. In central Anatolia, calc-alkaline to alkaline volcanism began in the Middle–Late Miocene. Here we report trace elemental and isotopic data from Quaternary age samples from central and eastern Anatolia. Most mafic lavas from central Anatolia are basalt and basaltic andesite, with lesser amounts of basaltic trachyandesite and andesite. All magma types exhibit enrichment in LILE (Sr, Rb, Ba and Pb) relative to HFSE (Nb, Ta). Trace element patterns are characteristic of continental margin volcanism with high Ba/Nb and Th/Nb ratios. 87Sr/86Sr and 143Nd/144Nd isotopic ratios of central Anatolian lavas range between 0.704105–0.705619 and 0.512604–0.512849, respectively. The Quaternary alkaline volcanism of eastern Anatolia has been closely linked to the collision between the Arabian and Eurasian plates. Karacadaǧ and Tendürek volcanic rocks are represented by alkali basalts and basaltic trachyandesites, respectively. As expected from their alkaline nature, they contain high abundances of LIL elements, but Tendürek lavas also show depletion in Nb and Ta, indicating the role of crustal contamination in the evolution of these magmas. 87Sr/86Sr and 143Nd/144Nd ratios of the Karacadaǧ and Tendürek lavas range from 0.703512 to 0.704466; 0.512742 to 0.512883 and 0.705743 to 0.705889 and 0.512676, respectively. Petrogenetic modelling has been used to constrain source characteristics for the central and eastern Anatolian volcanic rocks. Trace element ratio plots and REE modelling indicate that the central Anatolian volcanism was generated from a lithospheric mantle source that recorded the previous subduction events between Afro-Arabian and Eurasian plates during Eocene to Miocene times. In contrast, The Karacadaǧ alkaline basaltic volcanism on the Arabian foreland is derived from an OIB-like mantle source with limited crustal contamination. Tendürek volcanism, located on thickened crust, north of the Bitlis thrust zone, derived from the lithospheric mantle via small degrees (1.5 %) of partial melting.