SEISMOLOGY AND GEOLOGY ›› 2014, Vol. 36 ›› Issue (4): 991-1008.DOI: 10.3969/j.issn.0253-4967.2014.04.005

• CONTENTS • Previous Articles     Next Articles

THE MAGMA SOURCE PROPERTIES AND EVOLUTION OF HOLOCENE VOLCANOES IN TENGCHONG, YUNNAN PROVINCE, SW CHINA

LI Xin1, LIU Jia-qi2, SUN Chun-qing2, DU De-dao1, Wang Shi1   

  1. 1. Research Institute of Petroleum Exploration &|Development, Standardization Research Institute of Petroleum Industry, PetroChina, Beijing 100083, China;
    2. Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
  • Received:2014-04-17 Online:2014-12-30 Published:2015-01-07

云南腾冲全新世火山源区性质及其岩浆演化

李欣1, 刘嘉麒2, 孙春青2, 杜德道1, 王石1   

  1. 1. 中国石油勘探开发研究院, 石油工业标准化研究所, 北京 100083;
    2. 中国科学院地质与地球物理研究所, 新生代地质与环境研究室, 北京 100029
  • 通讯作者: 刘嘉麒,院士,E-mail:liujq@mail.iggcas.ac.cn
  • 作者简介:李欣,女,1982年生,2012年在中国科学院地质与地球物理研究所获得博士学位,现为中国石油勘探开发研究院博士后,主要从事矿物学、岩石学、矿床学方面的工作,E-mail:xinxin@163.com.
  • 基金资助:

    国家自然科学基金(41020124002)和国土资源部项目"深部探测技术与实验研究"(201011060)共同资助.

Abstract:

This paper focuses on the characteristics of petrology, geochemistry, magma source and magma evolution characteristics of three Holocene volcanoes (Heikongshan, Dayingshan, Maanshan) from the Tengchong volcanic eruption field, with the aim of ascertaining the characteristics of the volcanic eruption and the relationship between these three magma chambers. Studies of the major element and trace element compositions of the Holocene volcanic rocks from the Tengchong volcanic eruptive field indicate that they are high potassium calc-alkaline series rocks including trachybasalt, basaltic trachyandesite, trachyandensite, and dacite. These rocks are rich in LILE and LREE, and depleted of Nb-Ta-Ti in mantle-normalized incompatible trace element patterns which show the chemical characteristic of arc volcanics. The volcano eruptions since Cenozoic are not controlled by plate subducting and volcanic arc but by faults within the basin. Trace elements' partial melting modeling shows that the Holocene volcanic rocks in Tengchong volcanic eruption field have been derived by large-scale partial melting of a garnet lherzolite in low pressure condition. They are from intra-plate background but with island arc volcanics' geochemical characteristics which suggest tectonic settings of island arcs or active continental margins. The magma source of these rocks is from the mantle which was enriched by palaeo-oceanic crust subduction. The enrichment happened before partial melting. The K-rich mineral in the source is rutile not amphibole. The magma of Heikongshan, Dayingshan and Maanshan experienced crust contamination and crystal fractionation of phosphorite, pyroxene, olivine, limenite, and plagioclase at the chamber stage.

Key words: petrogeochemistry, volcanic source properties, magmatic evolution, Tengchong, Yunnan

摘要:

在对腾冲火山区进行野外考察的基础上, 重点对区内3座全新世火山(黑空山、打莺山和马鞍山)的岩石学及地球化学特征、岩浆源区性质及其演化进行研究.对主量元素和微量元素研究表明, 这套岩石属于高钾钙碱性系列, 包括粗面玄武岩、玄武粗安岩、粗面安山岩和英安岩, 从基性岩到酸性岩都有分布.这套火山岩富集大离子亲石元素和轻稀土元素, 亏损Nb-Ta-Ti不相容元素, 具有岛弧火山岩特征.通过微量数据模拟认为, 腾冲全新世火山岩为石榴石相地幔橄榄岩在低压条件下大比例部分熔融的产物.源区富钾矿物为金云母, 不含角闪石.腾冲及其邻区新生代以来的火山喷发主要受盆地内断裂控制, 不受板块俯冲或者火山弧作用的控制.其活动产物为板内火山岩, 表现出的岛弧火山岩特征是由于地幔源区受到古洋壳的俯冲板片的富集作用, 富集作用发生在部分熔融作用之前.富集地幔部分熔融形成的富钾岩浆沿断裂上升进入地壳形成岩浆房, 在岩浆房阶段经历了分离结晶作用和地壳混染作用, 有钛铁氧化物、磷灰石、橄榄石、单斜辉石和斜长石的结晶分离.

关键词: 岩石地球化学, 火山源区性质, 岩浆演化, 云南腾冲

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