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桐柏——大别造山带燕山晚期A型花岗岩的厘定
The Ascertainment of Late-Yanshanian A-type Granite in Tongbai-Dabie Orogenic Belt
  
中文关键词:A型花岗岩 高分异I型花岗岩 构造环境 桐柏—大别造山带
英文关键词:A-type granite,high fractionated I-type granite,tectonic environment,Tongbai-Dabie orogenic belt
基金项目:国家攀登计划预选(95 -预 - 2 5 ),国家重点基础研究发展规划 (G19990 432 0 2 ),广东省自然科学基金博士启动(9945 88),国家博
作者单位
王 强  
赵振华  
熊小林  
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中文摘要:
      本文通过岩石地球化学研究和讨论,认为桐柏—大别造山带燕山晚期存在过碱性(peralkaline)和铝质(aluminous)A型花岗岩。过碱性花岗岩的岩石类型为碱长花岗岩和石英正长岩,其ACNK=0.72~0.97,NKA=1.02。铝质A型花岗岩是本文研究的重点,岩石类型也为碱长花岗岩和石英正长岩;其SiO2含量为67.73%~77.60%,富碱(Na2O+K2O含量为7.97%~9.76%),ACNK=0.72~1.03, NKA=0.84~0.97,属于偏铝质-微过铝质岩石;轻稀土元素富集,负铕异常明显(δu=0.12~0.57),Zr、Nb、Ga、Y富集。与高分异的I型花岗岩相比,研究区高硅(SiO2>72%)的铝质A型花岗岩富Fe(FeOT>1.50%),高Zr+Nb+Ce+Y和Ga/Al,具有较高的Zr饱和温度(845~880℃)。研究区A型花岗岩形成于造山期后环境,标志着桐柏—大别造山带在晚白垩世进入了伸展塌陷阶段及碰撞-叠覆造山的结束。
英文摘要:
      The study and discussion of petrology and geochemistry have revealed that there exists two kinds of A-type granites in Tongbai-Dabie orogenic belt: peralkaline and aluminous granites.The peralkaline A-type granites include alkaline feldspar granite and quartz syenites, characterized by ACNK=0.72~0.97 and NKA=1.02. The aluminous A-type granites also include alkaline feldspar granite and quartz syenites, characterized by SiO2=67.73%~77.60%, rich alkali, Na2O+K2O=7.97%~9.60%, ACNK=0.72~1.03, NKA=0.84~0.97, rich REE,δEu=0.12~0.57 and rich Zr, Nb, Ga and Y. Compared with high fractionated I_type granites, the high Si(SiO2>72%) aluminous A-type granites show rich Fe (FeOT>1.50%),high Zr+Nb+Ce+Y and Ga/Al as well as high zircon saturation temperature (845~880℃).The A-type granites were formed in a post-orogenic environment. It is suggested that Tongbai-Dabie orogenic belt entered the phase of extension and collapse in Late Cretaceous, during which the orogenic movement ended.
王 强,赵振华,熊小林,2000,桐柏——大别造山带燕山晚期A型花岗岩的厘定[J].岩石矿物学杂志,19(4):297~306.
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