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庐枞早白垩世火山岩的地球化学特征及其源区意义
  • ISSN号:1006-7493
  • 期刊名称:《高校地质学报》
  • 时间:0
  • 分类:P588.1[天文地球—岩石学;天文地球—地质学]
  • 作者机构:[1]中国科学技术大学地球和空间科学学院,中国科学院壳幔物质与环境重点实验室,合肥230026
  • 相关基金:自然科学基金项目(40673008)和国家自然科学基金青年基金项目(40203004)
中文摘要:

从中生代到新生代,华北东部岩石圈地幔发生了减薄以及地球化学性质置换,而扬子地块东部中生代岩石圈地幔也表现出类似的过程,对中生代火山岩的地球化学研究有助于了解这一变化过程以及发生置换时的时空关系.庐枞火山岩出露于扬子地块东部,为一套包括粗玄岩-玄武粗安岩-粗面岩的富碱橄榄安粗岩系.研究了双庙组基性火山岩,这些岩石富集Rb,K,Sr,Th和轻稀土元素,亏损高场强元素.(^87Sr/^86Sr)i=0.7060~0.7063,εNd(t)=-3.9~-6.2,(^206Pb/^204Pb)i=17.788~18.125,(^207Pb/^204Pb)i=15.511~15.546,(^208Pb/^204Pb)i=37.735~38.184.在喷出地表过程中,火山岩没有受到明显的地壳物质混染,因此元素和同位素组成反映了地幔源区的地球化学特征.其地幔源区具有同位素富集特征,表明火山岩源区曾受到地壳物质的影响,是富集地幔部分熔融的产物,并经历明显的结晶分异作用.庐枞火山岩的岩浆成分和源区特征反映该地区在晚中生代岩石圈地幔的伸展和软流圈地幔上涌的演化过程.

英文摘要:

The sub-continental lithospheric mantle (SCLM) under the eastern part of North China was thinned and the geochemical characteristics were replaced during Mesozoic and Cenozoic. The Mesozoic SCLM under eastern Yangtze block shows the similar procedure as that in North China craton. This paper reports the geochemical characteristics of Mesozoic volcanics, which will be helpful for understanding the characteristics of Yangtze SCLM and the time-space relationship of the replacement characteristics from Mesozoic to Cenozoic. The Luzhong volcanics, occurring in eastern part of China and belonging to Yangtze block, are a set of Late-Mesozoic alkali-rich shoshonitic rocks, which include traehybasalts-basaltic traehyandesite-traehyte. The Suangmiao group, part of the Luzhong set, was studied in detail in this paper. The volcanics were slightly contaminated by crust materials during the formation, and the elemental and isotopic compositions can well reflect their mantle source. The basaltic rocks are characterized by enriched Rb, K, Sr, Th and LREE, and depleted HFSEs. They also have enriched Sr-Nd isotopic compositions with (^87Sr/^86Sr)i = 0.7060~0.7063, εNd(t) = -3.9~-6.2, (^206pb/^204Pb)i = 17.788~18.125, (^207pb/^204Pb)i = 15.511~5.546, (^208Pb/^204Pb)i = 37.735~38.184. These data suggest that the magma was partially melted from enriched mantle source, which was effected by lower crust materials within the source, and followed by crystal fractionation. The magma composition and mantle source characteristics of Luzhong volcanics imply the extension of lithospheric mantle and asthenosphere upwelling in the Late Mesozoic.

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期刊信息
  • 《高校地质学报》
  • 中国科技核心期刊
  • 主管单位:教育部
  • 主办单位:南京大学
  • 主编:王汝成
  • 地址:南京市栖霞区仙林大道号南京大学共山楼
  • 邮编:210023
  • 邮箱:gxdzh@nju.edu.cn
  • 电话:025-83594340
  • 国际标准刊号:ISSN:1006-7493
  • 国内统一刊号:ISSN:32-1440/P
  • 邮发代号:
  • 获奖情况:
  • 1)2011年获中国高校期刊研究会颁发的“首届中国...,2)2012年“学术讨论与争鸣”栏目获江苏省科学技...,3)2012年被中国学术期刊(光盘版)电子杂志社,...,4)2013年被中国学术期刊(光盘版)电子杂志社,...,5)2014年获中国高校期刊研究会颁
  • 国内外数据库收录:
  • 美国化学文摘(网络版),美国地质文献预评数据库,日本日本科学技术振兴机构数据库,中国中国科技核心期刊,中国北大核心期刊(2004版),中国北大核心期刊(2008版),中国北大核心期刊(2011版),中国北大核心期刊(2014版)
  • 被引量:12035