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，为调查西南罗斯海地区构造发育的研究提供资金。长期以来，人们根据全球板块环路、明显的热点运动、海底磁异常的解释、古地磁学和地质理由，提出了南极洲东西部之间的位移。这种运动需要穿越南极洲的板块边界，但这些边界从未被明确定义。该项目将尝试描绘新生代晚期——沿着罗斯海西部恐怖裂谷的东南极洲和西南极洲之间的活跃边界，在那里已经确定了年轻的结构，可以建立活跃延伸和大陆内结构之间的连续性，并且通过船舶可到达的地方将允许获取新的关键数据集。我们将使用多源海洋和机载地球物理数据来绘制恐怖裂谷东缘的断层模式和火山结构图。将使用多波束测深技术绘制海底火山裂缝的方向和海山排列。火山排列将显示恐怖裂谷的区域延伸或剪切方向以及相关地壳应力的方向。条带测深和单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界限。 新构造断层模式的描绘将证明恐怖裂谷的东缘是否形成连续的边界，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。综合结果将检验以下命题：恐怖裂谷的东部边界构成了穿过罗斯海的主要晚新生代活动构造的界限，以及恐怖裂谷运动学涉及与北部右旋走滑断层相关的右旋张量。这些结果将有助于限制西南极裂谷系统和南大洋结构之间的运动学和动力学联系，以及东西南极洲之间的任何相关运动。 第一年，将对恐怖裂谷现有的多道和单道地震剖面以及航磁数据进行协作结构分析。将确定海底火山口或裂缝以及任何断层陡坡的位置，并对恐怖裂谷的年龄和变形运动学进行初步解释。第二年末，在 RVIB N.B. 进行为期一个月的巡游。帕尔默将对恐怖裂谷海底的选定部分进行多波束测深和侧扫声纳测绘。重力、磁力、地震反射和 Bathy2000 3.5 kHz 地下剖面数据也将在裂谷处收集。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层的范围和几何形状。该项目将：1）完成恐怖裂谷的新构造断层和火山结构地图； 2）解释结构模式以获得与裂谷发展相关的运动和应力； 3) 将恐怖裂谷结构与横贯南极山脉绘制的断层和轮廓进行比较，以改善结构的年龄限制； 4）将西罗斯海的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.