Petrology and Tectonics of the Australian-Antarctic Discordance and Adjacent Ridges

澳大利亚-南极不一致是大洋中脊系统独特而神秘的水深和地质特征，其起源尚不清楚。我们提出了一个综合的地球物理和地球化学方案来研究不整合带。综合地球化学调查与SeaMARC II侧扫声纳调查以及详细的磁力和重力分析相结合，将提供一个独特的数据集，该数据集将侧重于两个具有根本意义的问题，在全球范围内，就不整合本身的性质和来源而言：(1)不整合东部边界的地球物理和地球化学性质，不整合是全球大洋中脊系统中最显著的地球化学和测深不连续之一；(2)轴向深度、轴向形态、海脊分段、以及沿轴线的岩石学变化，所有这些都是异常可变的，无论是在不整合内部还是外部。次要目标包括不协调内异常、粗糙地形的性质，目前向不整合面汇聚的扩展裂谷的地貌构造特征，远离热点地区海脊传播的地球化学效应，深海熔岩成分与高幅度磁异常之间的关系，与不整合面内主要地壳厚度变化有关的可能的山脊分段，岩浆或软流圈向(并进入？)的亚轴向流动的可能性。不和谐

The Australian-Antarctic Discordance is a unique and enigmatic bathymetric and geologic feature of the mid-ocean ridge system whose origin is poorly understood. We propose an integrated geophysical and geochemical program to study the Discordance zone. The combination of a comprehensive geochemical investigation with a SeaMARC II side-scan sonar survey and detailed magnetic and gravity analyses will provide a unique data set which will focus on two problems which are of fundamental significance, both on a global scale and with respect to the nature and origin of the Discordance itself: (1) the geophysical and geochemical nature of the eastern boundary of the Discordance which is one of the most pronounced geochemical and bathymetric discontinuities in the global mid- ocean ridge system, and (2) the interrelationships among axial depth, axial morphology, ridge segmentation, and along axis petrologic variations, all of which are unusually variable, both within and outside the Discordance. %%% Secondary objectives include the nature of the anomalous, rough topography within the Discordance, the morphotectonic signature of the propagating rifts presently converging toward the Discordance, the geochemical effects of ridge propagation in a region remote form hotspots, the relationship between abyssal lava compositions and high amplitude magnetic anomalies, possible ridge segmentation related major crustal thickness variation within the Discordance, and the possibility of subaxial flow of magma or asthenosphere towards (and into?) the Discordance