冀西北万全地区大麻坪地幔岩包体高温高压弹性波研究及其地质意义  

Measurements of elastic wave velocities in mantle rocks at high temperatures and high pressures from Damaping area, Wanquan, northwestern Hebei, China, and its geological significance.

作　　者：韦延光[1] 王多君[2] 易丽[3] 邓军[1] 王建国[1] 谢鸿森[3] 

机构地区：[1]中国地质大学"岩石圈构造,深部过程及探测技术"教育部重点实验室,北京100083 [2]中国地震局地质研究所,北京100029 [3]中国科学院地球化学研究所,贵州贵阳550002

出　　处：《地质通报》2005年第6期524-527,共4页Geological Bulletin of China

基　　金：国家自然科学基金重大项目(10299040);中国科学院知识创新工程项目(KJCX2-SW-No.3);国家自然科学基金项目(No.40172036);教育部科学技术研究重点项目(No.01037)资助。

摘　　要：对河北大麻坪碱性玄武岩及其内的辉石岩和二辉橄榄岩包体进行了不同温压条件下的弹性波速测定。结果表明,岩石波速与压力正相关,与温度负相关;相同条件下二辉橄榄岩的弹性波速最大,辉石岩次之,玄武岩最小。在1.4GPa压力下获得二辉橄榄岩和辉石岩的弹性波速分别为7.87km/s和7.47km/s,最接近壳幔过渡带的弹性波速。而现代地球物理资料显示该地区莫霍面深度为32km,认为26Ma以来,该地区发生了大规模的岩石圈减薄地质事件。Measurements of elastic wave velocities at different high temperatures and high pressures were made on alkali basalt and xenoliths of pyroxenite and lherzolite from Damaping, Hebei. The experimental results indicate that vP increases with pressure increasing, whereas vP decreases with temperature increasing. Results indicate that the rock wave velocity vP has a positive correlation with pressure and a negative correlation with temperature. Under the same conditions, vP of lherzolite is highest, that of pyroxenite comes next and that of basalt is lowest. The vP values of lherzolite and pyroxenite obtained at 1.4 GPa are 7.87 km/s and 7.47 km/s respectively. These values are closest to that of rocks from the crust-mantle transition zone. Geophysical data indicate that the Moho depth of the area is ～32 km. The authors think that large-scale lithospheric thinning took place in the area since 26 Ma.

关 键 词：冀西北 地幔岩包体 弹性波速 高温高压 岩石圈减薄 

分 类 号：P588.146[天文地球—岩石学] P631.5[天文地球—地质学]