摘要
黑龙江省依兰地区出露了一套经高压变质形成的蓝片岩、云母片岩、长英质糜棱岩和少量超基性岩及大理岩并经历了强变形作用改造,一直被认为是佳木斯地块与其西侧松嫩地块碰撞拼贴所形成的缝合带产物。本次研究,通过岩相学与矿物化学分析,根据矿物组合的不同,识别出研究区内三种不同类型的蓝片岩;并获得了绿帘蓝闪石片岩（T=350～550℃,P=10～14kbar）、蓝闪霓辉石片岩（T=350～550℃,P=10～14kbar）和石榴石冻蓝闪石片岩（T=500～540℃,P=10～12kbar）的峰期变质温压条件。结合前人发表的地质年代学数据,建立了变质演化P-T-t轨迹。其中,绿帘蓝闪石片岩具＂发卡式＂变质演化P-T-t轨迹;而蓝闪霓辉石片岩与石榴石冻蓝闪石片岩具顺时针的演化轨迹。我们推测其成因可能为不同类型的蓝片岩形成于不同的俯冲阶段,由动力学机制的变化所造成。该研究成果为进一步探索佳木斯地块与松嫩地块碰撞拼贴的构造演化过程提供重要的依据。
The high-pressure metamorphic rocks exposed in the Yilan area,Heilongjiang Province,are characterized by alternating of blueschists,mica schists and felsic mylonites,with small amounts of ultramafic rocks and marbles that were tectonically interleaved mélange,representing the rock associates derived from the suture zone between the Jiamusi and Songnen massifs. In this paper,the petrographical and mineral chemical investigations have been carried out on the blueschists from the Yilan area. Three types of blueschists are classified on the basis of the mineral assemblages,i. e. epidote-glaucophane schist,glaucophane aegirine-augite schist and garnet-barroisite schist. Their peak metamorphic conditions are estimated to be T = 350 ～ 550℃,P = 10 ～ 14 kbar for epidoteglaucophane schist,T = 350 ～ 550℃,P = 10 ～ 14 kbar for glaucophane aegirine-augite schist,and T = 500 ～ 540℃,P = 10 ～ 12 kbar for garnet-barroisite schist,respectively. Combining with the previously reported age data,the P-T-t paths of the blueschists are constructed. The epidote-glaucophane schist is characterized by the ‘hair-pin＇type P-T-t path,whereas,the glaucophane aegirineaugite schist and garnet-barroisite schist are represented by the typical clockwise P-T-t paths. We therefore propose that the different paths obtained are due to the various geodynamic mechanisms during the subduction processes on the basis of formation ages of the blueschists. The result presented here will contribute toward consideration of tectonic evolution between the Jiamusi and Songnen massifs.
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
2014年第10期3085-3099,共15页
Acta Petrologica Sinica
基金
科技部973项目(2013CB429802)
国家自然科学青年基金项目(41302175
41102140)
博士点基金项目(20120061120063)
国家自然科学重点基金项目(40739905)联合资助
