摘要
苏北-胶南构造混杂岩带中高压变质超镁铁质岩为石榴橄榄岩和石榴辉石岩,它们具残斑结构、糜棱结构和斑状变晶结构。橄榄石发育低密度自由位错和{110}[101]滑动条带,矿物(如贫铝辉石)的化学成分,矿物形成的平衡条件(P=3050～5130MPa,T=627～842℃),都反映岩石经历高压低温的变质历史。石榴橄榄岩中低含量贫铝辉石和高含量石榴石可能是在大于5000MPa条件下辉石-石榴石相转变的结果。
The ultramafic rocks, including garnet peridotite and garnet pyroxenite, are preserved within the tectonic melange in the northern Jiangsu-southern Shandong region. The data on mineral assemblages (Ol+Opx+Cpx+Gt and Ol+Opx+Cpx+Gt+Sp), microtextures (porphyroclastic, mylonitic and porphyroblastic), dislocation substructure of olivine and equilibrium conditions at low temperature (627～842℃) and high pressure (3050～5130MPa) presented here indicate that the ultramafic rocks have undergone high pressure metamorphism in the process of subduction. The low content of poor-A yroxene and high content of garnet in the garnet peridotite may be a result of the pyroxene-garnet transformation at higher than 5000 MPa beneath the upper mantle.
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
1992年第1期90-96,T001,共8页
Acta Petrologica Sinica
基金
国家自然科学基金(4880123)
关键词
超镁铁质岩
高压变质
辉石
石榴石
Ultramafic rocks
Pyroxene-garnet transformation
High pressure metamorphism
Northern Jiangsu-southern Shandong region
