摘要
吉林辉南位于华北克拉通（NCC）东北部边缘,新生代玄武岩中含有大量的新鲜幔源包体。包体类型主要为尖晶石二辉橄榄岩。由包体矿物化学成分计算的平衡温度为：982~1085℃。氧化缀饰方法揭示了样品中橄榄石的显微特征,表明包体存在形态各异的位错样式：位错壁、亚颗粒、位错环、位错网等,指示样品可能经历了以位错蠕变为主的塑性变形。依据亚颗粒大小推算上地幔差异流动应力为：21.3~36.5 MPa。利用电子背散射衍射（EBSD）技术测定橄榄石的晶格学优选方位（LPOs）,表明橄榄石在本区总体上具有A型组构。其中,样品LQLW08-18的温度和组构类型及地震波各向异性上的差异,暗示了温度差异可能产生更倾向于作用在[100]晶轴上的一个效应。地震波各向异性与橄榄岩中矿物含量的研究,定量地说明了斜方辉石具有降低橄榄岩各向异性效果。橄榄岩包体的各种流变学参数与组构特征为该区上地幔进一步研究提供了基础信息和约束,说明了该区上地幔整体上的不均一性,为该区的破坏动力学机制可能主要为地幔置换作用（化学侵蚀作用）提供了流变学条件。
A large amount of mantle xenolith was found in the Cenozoic basalt in Huinan,Jilin province,which is located in the northeastern margin of North China Craton.Main type of mantle xenoliths is spinel lherzolite.Mineral chemical compositions show the equilibrium temperature within a range of 982~1085℃.As revealed by the oxidation decoration technique,the samples have underwent dislocation creep dominated plastic deformation,resulting in different kinds of dislocation structures.Differential stress,estimated from the size of subgrain,is within the range of 21.3~36.5 MPa.The LPOs of olivine,which was measured by the EBSD,generally show A-type olivine fabrics.The variation of temperature and fabric and seismic anisotropy of LQLW08-18 suggest that the temperature may have a effect in preference to the ／ crystal axis.According to the study of olivine and peridotite anisotropy and the mineral compositions in the peridotite,orthopyroxene can reduce the anisotropy of the bulk rock.Different kinds of rheological parameters and fabrics characteristics not only provide basic information and restrictions for further study of the upper mantle but also indicate mantle heterogeneity and the replacement（chemical erosion） may be the main dynamic mechanism of destruction in this area.
出处
《地质学报》
EI
CAS
CSCD
北大核心
2011年第4期491-504,共14页
Acta Geologica Sinica
基金
国家自然科学基金重大研究计划重点项目"华北克拉通破坏深部过程的高温高压实验研究"(编号90714005)资助成果
关键词
橄榄岩包体
流变学特征
晶格优选方位
地震波各向异性
辉南
lherzolite xenoliths
rheological characteristics
lattice preferred orientation
seismic anisotropy
Huinan
Jilin
