摘要
通过对比华北太行山重力梯度带两侧新生代玄武岩及其中幔源包体的成分,发现:(1)华北东、西部新生代玄武岩具有相反的演化趋势,说明新生代以来西部岩石圈逐渐减薄,而东部岩石圈逐渐加厚;(2)西部岩石圈地幔组成相对复杂,年龄多为晚太古代-元古代;而东部岩石圈地幔组成相对单一,年龄多为现代值,少数为元古代;(3)西部壳幔过渡带较厚而东部较薄,反映两地不同的岩浆底侵作用程度．华北岩石圈组成的空间不均一性可能与岩石圈减薄过程的时空差异有关．岩相古地理分析说明太行山重力梯度带的雏形形成于早白垩世,与华北中生代岩浆活动的高峰相吻合．由于岩浆作用与岩石圈减薄作用密切相关,因此认为华北岩石圈减薄的时空不均一性是形成太行山重力梯度带的重要机制．
The comparison of Cenozoic basalts and their mantle xenoliths from both sides of the Taihangshan gravity lineament reveals that： （1） Cenozoic basalts from western and eastern North China display opposite temporal trends, suggesting lithospheric thinning in western North China during the Cenozoic and lithospheric thickening in eastern North China; （2） The lithospheric mantle in the west is mostly Late-Archean to Proterozoic in age, whereas that in the east has a modern age with minor Proterozoic age; （3） The crust-mantle transition in the west is considerably thicker than in the east, probably due to different extents of magmatic underplating. The spatial heterogeneity of the lithospheric mantle beneath North China may have resulted from the diachronous thinning processes. Paleogeographic data suggest the first occurrence of the Taihangshan gravity lineament was initially formed during the Early Cretaceous, which is coeval with the peak of Mesozoic magmatism in this region. Given the fact that Mesozoic magmatism was closely related to the lithospheric thinning, it is proposed that the diachronous lithospheric thinning is the main mechanism by which the Taihangshan gravity lineament was formed.
出处
《地球科学（中国地质大学学报）》
EI
CAS
CSCD
北大核心
2006年第1期14-22,共9页
Earth Science-Journal of China University of Geosciences
基金
中国科学院"百人计划"项目国家自然科学基金项目(Nos.49925308
40234046)
关键词
重力梯度带
岩石圈减薄
华北克拉通
gravity lineament
lithospheric thinning
North China craton
