雁荡山世界地质公园火山作用研究  

Volcanism of the Yandang Mountain World Geopark

作　　者：余明刚[1] 邢光福[1] 沈加林[1] 陈荣[1] 周宇章[1] 隗合明[2] 陶奎元[1] 

机构地区：[1]南京地质矿产研究所,江苏南京210016 [2]长安大学地球科学系,陕西西安710054

出　　处：《岩石矿物学杂志》2008年第2期101-112,共12页Acta Petrologica et Mineralogica

基　　金：国土资源部国土资源大调查项目(1212010610611);国土资源部“百人计划”第三批资助项目

摘　　要：雁荡山世界地质公园位于浙江省东南部,主体为一白垩纪火山岩浆活动形成的复活破火山,由4个火山岩性段和1个中央侵入体构成,经历了4期喷发、2次塌陷、1次侵入、现代地貌形成等共8个演化阶段。火山岩为以流纹质和粗面英安质为主的高钾钙碱性系列岩石组合,中央侵入体为橄榄安粗岩系列石英正长斑岩,它们的A/CNK值集中在0.9~1.2之间,为铝饱和或铝过饱和类型。岩石富集轻稀土元素和大离子亲石元素,相对亏损高场强元素;δEu值为0.11~0.32,表明岩浆经历了以斜长石为主的强烈结晶分异作用;火山岩(87Sr/86Sr)i为0.7079~0.7161,εNd(t)为-6.90^-7.70,中央侵入体石英正长斑岩(87Sr/86Sr)i为0.7086~0.7098,εNd(t)为-7.10^-7.68,表明它们是同源岩浆不同阶段分异演化的产物,物质来源主要为陆壳,但也有地幔物质参与。它们形成的大地构造背景,不是典型的岛弧或安第斯型活动大陆边缘,而是活动大陆边缘靠板内的环境。The Yandang Mountain World Geopark situated in southeastern Zhejiang Province is mainly a Cretaceous resurgent caldera composed of four volcanic rock sections and one central intrusive body. It has undergone four stages of eruption, two collapses, one intrusion and the formation of modern landscape, comprising totally eight evolution phases. Volcanic rocks are of the high-K calc-alkaline series rock association, composed mainly of ryholitic and trachytic dacitic rocks, and the central intrusive body is olivine-andesite-trachytic quartz syenitic porphyrite. They have A/CNK values of 0.9-- 1.2, suggesting aluminum saturation or oversaturation, and are enriched in LREE and LILEs and depleted in HFSEs. Their δEu values are 0.11--0.32, evidently indicating plagioclase fractional crystallization. （S7Sr/S6Sr）i ratios and εNd（ t ） values are 0. 707 9--0. 716 1 and - 6.90-- -7.70 for volcanic rocks, and 0. 708 6--0. 709 8 and - 7.10- - 7.68 for quartz syenitic porphyrite, respectively, implying that all the igneous rocks from the Yandang Mountain were evolutional products of co-magmas, and derived mainly from the crust, mixed however with mantle components. The tectonic setting is an active continental margin close to the inner continent instead of a typical island arc or an Andean-type active continental margin.

关 键 词：构造背景 岩浆成因 破火山 雁荡山世界地质公园 

分 类 号：P588.14[天文地球—岩石学] P511.3[天文地球—地质学]