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

澳大利亚-南极不协调带是大洋中脊系统的一个独特而神秘的测深和地质特征，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协调带。综合地球化学调查与SeaMARC II侧扫声纳调查以及详细的磁场和重力分析相结合，将提供一个独特的数据集，将重点关注两个具有根本意义的问题，无论是在全球范围内还是在不协调本身的性质和起源方面：(1)全球洋中脊系统中最明显的地球化学和测深不连续——不协调东边界的地球物理和地球化学性质；(2)轴向深度、轴向形态、脊段分割和沿轴岩石学变化之间的相互关系，这些变化都是异常变化的；在不和谐的内部和外部。次要目标包括不协调带内异常、粗糙地形的性质，目前向不协调带聚集的扩展裂缝的形态构造特征，洋脊在遥远的热点地区传播的地球化学效应，深海熔岩组成与高振幅磁异常的关系，洋脊分割与不协调区内主要地壳厚度变化的可能关系，以及岩浆或软流圈向（或进入）不协调带的亚轴流的可能性

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