Collaborative Research: Neotectonic Structure of Terror Rift, Western Ross Sea

该奖项由极地项目办公室的南极地质和地球物理项目提供，为罗斯海西南部地区构造发育的研究提供资金。根据全球板块电路、明显热点运动、对海底磁异常的解释、古地磁和地质基础，早就提出了东西南极洲之间的位移。这样的运动需要穿越南极洲的板块边界，然而这些边界从来没有明确定义过。该项目将尝试沿着罗斯海西部的Terror裂谷圈定东、西南极洲的晚新生代活动边界，在那里已经确定了年轻的构造，可以建立活跃伸展和大陆内构造之间的连续性，并且通过船舶可达性将获得新的关键数据集。我们将使用多源海洋和航空地球物理数据来绘制恐怖裂谷东部边缘的断层模式和火山结构。火山裂缝的方向和海底海山的排列将使用多波束测深技术绘制。火山排列将显示横跨恐怖裂谷的区域伸展或剪切方向以及相关的地应力方向。带状测深和单通道地震数据将用于记录新构造断层模式和近期断层的东部边界。新构造断层模式的描绘将证明恐怖裂谷东部边缘是否形成一个连续的边界，以及裂谷本身是否可以与罗斯海西北部假定的走滑断层联系起来。该项目的海底发现将与周围火山岛和横贯南极山脉的断层运动学和应力场测定相结合。综合结果将验证恐怖裂谷的东部边界是主要的晚新生代活动构造通过罗斯海的边界，以及恐怖裂谷的运动学涉及与北部右侧走滑断裂相联系的右旋张拉。这些结果将有助于约束南极西部裂谷系统与南大洋构造之间的运动学和动力学联系，以及南极东部和西部之间的任何相关运动。在第一年，将对恐怖裂谷上现有的多通道和单通道地震剖面和航磁数据进行协作结构分析。火山喷口或裂缝的位置以及海底的断层峭壁将被确定，并对恐怖裂谷的年龄和变形的运动学进行初步解释。第二年晚些时候，在RVIB N.B. Palmer上进行为期一个月的巡航，将对恐怖裂谷选定的海底部分进行多波束测深和侧扫描声纳测绘。重力、磁力、地震反射和Bathy2000 3.5 kHz海底剖面数据也将收集到整个裂谷。在第三年，我们将使用这些多源数据来绘制火山体的方向和形式，以及与恐怖裂谷相关的新构造断裂的范围和几何形状。该项目将：1)完成恐怖裂谷新构造断层和火山构造图；2)解释构造模式，推导出与裂谷发育相关的运动和应力；3)将恐怖裂谷构造与横贯南极山脉的断层和构造进行对比，完善构造的年龄约束；4)将西罗斯海晚新生代构造解释与南大洋板块边界运动学相结合。

This award, provided by the Antarctic Geology and Geophysics Program of the Office of Polar Programs, provides funds for a study to investigate the tectonic development of the southwestern Ross Sea region. Displacements between East and West Antarctica have long been proposed based on global plate circuits, apparent hot spot motions, interpretations of seafloor magnetic anomalies, paleomagnetism, and on geologic grounds. Such motions require plate boundaries crossing Antarctica, yet these boundaries have never been explicitly defined. This project will attempt to delineate the late Cenozoic - active boundary between East and West Antarctica along the Terror Rift in the western Ross Sea, where young structures have been identified, continuity between active extension and intracontinental structures can be established, and where accessibility via ship will allow new key data sets to be acquired. We will use multi-source marine and airborne geophysical data to map the fault patterns and volcanic structure along the eastern margin of the Terror Rift. The orientations of volcanic fissures and seamount alignments on the seafloor will be mapped using multibeam bathymetry. The volcanic alignments will show the regional extension or shear directions across the Terror Rift and the orientations of associated crustal stresses. Swath bathymetry and single channel seismic data will be used to document neotectonic fault patterns and the eastern limit of recent faulting. Delineation of neotectonic fault patterns will demonstrate whether the eastern margin of the Terror Rift forms a continuous boundary and whether the rift itself can be linked with postulated strike-slip faults in the northwestern Ross Sea. Seafloor findings from this project will be combined with fault kinematic and stress field determinations from the surrounding volcanic islands and the Transantarctic Mountains. The integrated results will test the propositions that the eastern boundary of the Terror Rift forms the limit of the major, late Cenozoic -active structures through the Ross Sea and that Terror Rift kinematics involve dextral transtension linked to the right-lateral strike-slip faulting to the north. These results will help constrain the kinematic and dynamic links between the West Antarctic rift system and Southern Ocean structures and any related motions between East and West Antarctica. In the first year, a collaborative structural analysis of existing multichannel and single channel seismic profiles and aeromagnetic data over the Terror Rift will be conducted. The location of volcanic vents or fissures and any fault scarps on the sea floor will be identified and a preliminary interpretation of the age and kinematics of deformation in the Terror Rift will be produced. Late in the second year, a one-month cruise on RVIB N.B. Palmer will carry out multibeam bathymetric and sidescan sonar mapping of selected portions of the seafloor of Terror Rift. Gravity, magnetics, seismic reflection and Bathy2000 3.5 kHz sub-bottom profile data will also be collected across the rift. In the third year, we will use these multisource data to map the orientations and forms of volcanic bodies and the extent and geometry of neotectonic faulting associated with the Terror Rift. The project will: 1) complete a map of neotectonic faults and volcanic structures in the Terror Rift; 2) interpret the structural pattern to derive the motions and stresses associated with development of the rift; 3) compare Terror Rift structures with faults and lineaments mapped in the Transantarctic Mountains to improve age constraints on the structures; and 4) integrate the late Cenozoic structural interpretations from the western Ross Sea with Southern Ocean plate boundary kinematics.