南极布兰斯菲尔德海峡的地球物理场特征与构造发育史

THE CHARACTERISTICS OF GEOPHYSICAL FIELD AND TECTONICAL EVOLUTION IN THE BRANSFIELD STRAIT

本文分析了“海洋四号”船１９９１年在南极布兰斯菲尔德海峡所采集的地球物理资料。这里的地形地貌、重力异常和磁异常沿东方向呈条带状分布。海峡中的新生代沉积可分为两组沉积系：第一张裂沉积系和第二张裂沉积系。在布兰斯菲尔德海峡西北部，基底发生了断裂，基底断块沿断面下滑，因而在海峡中部形成基底半地堑。通过横穿南设得兰群岛、布兰斯菲尔德海峡和南极半岛的地壳剖面，我们用分层剪切模式解释了在张性应力作用下的岩石圈变形特征。

There we analysised the data were collected using our survey ship-Ocean Ⅳin the Bransfield Strait in 1991. We recognized that the geomorphology、gravity and magnetic anomalies trend NE direction as bandings. The sediments in the Bransfield Strait are subdivided into two sequences:first rifting sequence and second rifting sequence. The basement was faulted into a half graben faulting in northwest side of the Bransfield trough. Considered the crustal structure crossing the South Shetland Islands、Bransfield Strait and Antarctic Peninsula,we proposal a two phase rifting tectonical evolution model and layered shear model for the lithospheric deformation under extensional stress field.