中国东部新生代玄武岩熔体结构与地球物理场的关系

中国东部新生代玄武岩被划分为拉斑玄武岩套、白榴玄武岩套和碱性玄武岩套,其中后者又分为内、中、外3个带。本文通过计算各岩套及岩带的NBO/T等熔体结构特征值,并结合地球物理场特征综合研究,认为各岩套及岩带熔体结构特征不仅有着明显差异,而且与地球物理场特征密切关联,其中NBO/T值与重力异常值呈负相关,与重力异常梯度和地壳厚度呈正相关。并且,产于深断裂带的玄武岩,其NBO/T值较大,而产于地台、地块的玄武岩,其NBO/T值较小。

RELATIONSHIP BETWEEN THE MELT STRUCTURE OF CENOZOIC BASALTS AND THE GEOPHYSICAL FIELD IN EASTERN CHINA

The Cenozoic basalts in eastern China are divided into tholeiite basalt suite, leucite basalt suite and alkali basalt suite. According to the calculating results, the author consid- ered that the characteristics of the melt structure of the suites not only are of evident dif- ference but also have close relationship with the geophysical field. The NBO/T value cor- related negatively to the gravity anomaly value and positively to both the gravity anomaly gradient and the crustal thickness. The NBO/T value of basalts occurring in deep-frac- ture-zone is comparatively high, but low in platform or landmass.