摘要
大别山太湖地区曾被作为“冷”、“热”榴辉岩带的交界处所在,我们对大别山太湖地区的进行了1:10000地质填图,并详细研究了该地区榴辉岩的岩相学和矿物成分变化,以及K_D值、峰期变质P-T条件。研究表明榴辉岩自南向北可分为三类:①朱家冲型榴辉岩;②大坝型榴辉岩;③金河桥型榴辉岩。其中朱家冲型榴辉岩和金河桥型榴辉岩显示出明显的温度、压力差异,它们形成的P-T条件分别为:P=2.14GPa、T=563℃和P=3.76GPa、T=791℃。大坝型榴辉岩的峰期变质P-T条件差别较大,在柯石英-石英相变线附近徘徊,变质环境相当于高压-超高压过渡环境。朱家冲型榴辉岩与大坝型榴辉岩分别对应于前人所划分的“冷”、“热”榴辉岩,并且两者在峰期,变质温、压条件上是连续变化的,没有明显的温、压间断。因此,我们认为本区所谓的“冷”、“热”榴辉岩带界线是不存在的。
The Taihu area in the Dabie Mountains had been identified as the conjugate area between the 'cold' and 'hot' eclogites, we have carried on geological mapping in the Tailm area of the Dabie Mountains, and investigated on petrography characterists, variance of mineral composition, K-D-value and the peak metamorphic P-T conditions of the eclogites in detail. This study has shown that the eclogites in Taihu area can be divided into three types from south to north: 1 Zhujiachong-type eclogite; 2 Daba-type eclogtie; 3 Jinheqiao-type eclogite. An obvious gap of the peak metamorphic P-T conditions appears between the Zhujiachong and Jinheqiao-types, with the average values of P-T conditions of the Zhujiachong-type eclogite being P = 2.14GPa and T = 563degreesC, and that of the Jinheqiao-type eclogite being P = 3.76GPa and T = 791degreesC. The Daba-type eclogties are distributed around quartz/coesite phase transition in P-T conditions, which, tectonically, is equal to high-ultrahigh pressure transition belt. The Zhujiachong and Daba-type eclogties correspond to the 'cold' and 'hot' eclogites separately. They show a good continuity in the respect of the peak metamorphic conditions and no obvious pressure gap. Hence, we consider that the boundary line of the 'cold' and 'hot' eclogites does not exist.
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
2004年第3期609-620,共12页
Acta Petrologica Sinica
基金
国家973项目"大陆深俯冲的动力学机制"(TG1999075511)资助
关键词
大别山太湖地区
榴辉岩
KD值
峰期变质P-T条件
Taihu area in Dabie mountains
eclogite
K-D-value
the peak metamorphic P-T conditions
