【摘要】 湘东长沙 -澧陵 -浏阳一带中晚元古宇的冷家溪群及板溪群遭受了区域甚低级变质作用。在本地区所采的 <2μm的样品中 ,冷家溪群伊利石结晶度的 Kübler指数为 0 .18～ 0 .2 6°△ 2θ,板溪群为 0 .2 1～ 0 .2 8°△ 2θ(Kisch国际标样校正 )。从而可把本地区冷家溪群的区域变质划归浅变质带和近变质带上部 ,温度大约为 2 80～ 40 0℃。板溪群划归近变质带上部 ,温度大约为 2 5 0～ 30 0℃。并未普遍达到目前人们认为的绿片岩相或者是低绿片岩相。样品中冷家溪群伊利石 (白云母 ) b0 值的范围在0 .8999～ 0 .90 42 nm ,板溪群为 0 .90 18～ 0 .90 42 nm。由冷家溪群 b0 频率累积曲线图 ,得出本区冷家溪群处于较典型的中压区更多还原

【Abstract】 The Lengjiaxi and Banxi Groups of the Middle Upper Proterozoic around the area of Changsha Liling Liuyang of the eastern Hunan Province, China underwent very low grade metamorphism. Illite crystallinity (IC) data of the <2μm fractions vary from 0.18 to 0.26°△2θ in the Lengjiaxi Group and from 0.21 to 0.28°△2θ in the Banxi Group (Kübler index, corrected with Kisch IC set, 1991). This indicates that the metamorphic grade of the Lengjiaxi Group is in the epizone and upper anchizone whilst the Banxi Group in the upper anchizone around the area investigated. The evaluated metamorphic temperature of the Lengjiaxi Group is 280~400℃ and that of the Banxi Group is 250~300℃. This result does not agree with the greenschist or subgreenschist facies of which most previous researchers thought. The range of b 0 values of illites varies from 0.8999 to 0.9042 (nm) in the Lengjiaxi Group and from 0.9018 to 0.9042 (nm) in the Banxi Group. Based on the cumulative frequency curves of illite (muscovite) b 0, the metamorphic pressure of the Lengjiaxi Group in the area was in a typical intermediate type.更多还原