南极洲普里兹湾岩石圈各向异性:海底地震仪观测
Lithosphere Anisotropy of Prydz Bay, Antarctica: From Ocean Bottom Seismometer Long Term Observation

为了研究南极普里兹湾岩石圈深部应力场及其动力学,采用S波分裂旋转相关法,对中国第31次南极科学考察成功回收的3个站位海底地震仪数据(5个远震记录)进行了反演,获得了普里兹湾洋陆过渡带岩石圈各向异性特征.结果表明,台站所在区域各向异性显著,在较小的范围内存在明显的空间差异,快S波偏振方向变化范围是N40°E~N60°E,快慢波时间延迟变化范围为0.2~1.3s.洋盆的各向异性主要取决于海底扩张地幔流作用,大陆及附近的各向异性主要受上地幔顶部残留构造的影响,而中间过渡带各向异性层厚度较小集中在地壳内,它可能受海底扩张地幔流和残留构造共同作用.
In order to understand better the stress field and dynamics characteristic of the lithosphere at Prydz bay in the Antarctica, rotation-correlation shear wave splitting method is used to study 5 earthquakes recorded by three ocean bottom seismometers recovered at Prydz bay during the 31th Chinese Antarctic Research Expedition to obtain the anisotropy characteristics of the continent and ocean transition of Prydz bay in this paper. Our inversion results show strong anisotropy in the lithosphere of Prydz bay with spatial differences in small scale. The fast shear wave polarization directions are from N40°E to N60°E, fast and slow shear wave times delay are from 0.2s to 1.3s. We think that the anisotropy at the oceanic part is dominated by the mantle flow of mid-ocean ridge spreading, while the continental part is dominated by the relic structural fabric of the ancient lithosphere at the top of the upper mantle, and the middle zone with shallower and thinner anisotropy layer may be influenced by the both reasons above