新疆阿尔泰造山带低压变质作用相平衡研究  

Phase equilibrium of low-pressure metamorphism in the Altaides,Xinjiang

作　　者：张翠光[1] 魏春景[2] 侯荣玖 后立胜[4] 卜小平[5] 

机构地区：[1]中国地质调查局发展研究中心,北京100037 [2]北京大学地球与空间科学学院,北京100871 [3]中油测井技术服务有限责任公司,北京100043 [4]中国地质调查局,北京100011 [5]国土资源部油气资源战略研究中心,北京100034

出　　处：《中国地质》2007年第1期34-41,共8页Geology in China

基　　金：国家自然科学基金项目(40525006)

摘　　要：通过对阿尔泰造山带低压型变质序列中典型泥质岩石进行详细的岩相学及相平衡研究,获得黑云母带变质作用的温度为445～550℃和压力为0.2～0.6 GPa;石榴石带为480～566℃、0.54±0.22 GPa;十字石带601±20℃、0.8±0.25GPa;十字石-红柱石带540±20℃、0.32±0.05 GPa,而632.4℃、0.785 GPa这个值不是红柱石的稳定范围,这可能是其早期中压变质作用条件;矽线石带为640℃、0.43 GPa左右,由于石榴石中有蓝晶石包体,因此其早期也可能经历中压条件的变质;堇青石-矽线石带740～800℃、0.4～0.7 GPa。阿尔泰造山带低压变质序列不是一个正常的变质序列,其野外变质梯度呈现“Z”字型特征。阿尔泰造山带低压变质作用可能形成于早期中压变质岩的挤压抬升和以此相关的大量花岗岩侵入的构造环境中。Study of the petrography and phase equilibria of typical metapelites from the low-pressure metamorphic sequence in the Air,ides indicates that the P-T conditions are 445-550℃ and 0.2-0.6 GPa for the biotite zone, 480-566℃ and 0.54±0.22 GPa for the garnet zone, 601 ±20℃ and 0.8 ±0.25 GPa for the staurolite zone, 540 ±20℃ and 0.32±0.05 GPa for the staurolite-andalusite zone, 640℃ and 0.43 GPa for the sillimanite zone and 740-800℃ and 0.4-0.7 GPa for the cordierite-sillimanite zone. However, 632.4℃ and 0.785 GPa are not in the stable range of the andalusite but probably the medium-pressure metamorphic conditions of the orogenic belt in the early stage. For the 640℃ and 0.43 GPa of the sillimanite zone, as the garnet in the zone contains kyanite inclusions, it may also have undergone medium-pressure metamorphism. The low-pressure metamorphic sequence of the Altaides is not a normal metamorphic sequence and its field metamorphic gradient shows the ＂Z＂-shaped character. The low-pressure metamorphism in the Altaides may have formed by compressional uplift of the medium-pressure metamorphic rocks at the early stage in a tectonic environment of extensive intrusion of collision-related granites.

关 键 词：低压变质作用 相平衡 阿尔泰造山带 新疆 

分 类 号：P542[天文地球—构造地质学]