摘要
皖西太古代霍邱群含铁建造(BIF)是一套中深变质岩系。在Al_2O_2过饱和的片岩与斜长片麻岩中,十字石,蓝晶石及矽线石等普遍共生,人工重砂中并见有红柱石,可形成Al_2SiO_5多形体的共生,这种共生组合在自然界实属少见,本文对其形成的温压进行了计算,对其成因作了讨论,同时提出了研究这种共生的地质意义。
In BIF of late Archaean Huoqiu Group in western Anhui Province Stauroite, kyanite and Sillimanite are widely Paragenous. Andalusite is also seen in heavy fractions of the rocks Paragenetic temperature and pressure arc calculated to be 750±50℃ and 6—8kb respectively.The three phase point of Al_2SiO_5 pleomorphism is actually a variable area on the phases equilibrium diagram. According to Newton's experiment (1966) , when the temperature and the pressure rise up to 750℃ and 6.6kb, andalusite becomes kyanite.However, in this particular case,Al_2SiO_5 pleomorphs contain Fe_2O_3, which might make andalusite much more stable under the same P—T.In addition, andalusite may also be formed under shearing condition.
The conventional Barrovian-type metamorphism is reconsidered.
出处
《矿物岩石》
CAS
CSCD
1989年第1期40-49,共10页
Mineralogy and Petrology
