The passive margin and ocean crust of the Enderby Basin, East Antarctica preserves a record of the breakup of East Gondwana. Using a suite of public domain geophysical data, we have examined and described the crustal morphology of the basin. Based on our geophysical observations, we divide the Enderby Basin into three distinct morphologic domains. The Eastern Domain demonstrates the most volcanic morphology of the basin, with abundant seaward dipping reflector packages and anomalously thick oceanic crust. These features suggest an early influence by the Kerguelen Hotspot on continental breakup within the domain. The Central Domain is characterized by two regions of oceanic crust of varying morphology segregated by a high amplitude magnetic anomaly. Geophysical observations suggest that the basement directly inboard of this magnetic anomaly is composed of thin, rugged, and poorly structured, proto-oceanic crust, similar in morphology to oceanic crust formed at ultraslow/slow mid-ocean ridged. Outboard of this anomaly, oceanic crust appears to be well-structured and of normal thickness. We offer three, non-exclusive, explanations for the observed change in ocean crustal structure: (1) melt production was initially low at the time of continental breakup, and the progressive decompression of the mantle led to a gradual increase in melt production and ocean crust thickness, (2) melt production was initially low to due lower extension rates and that melt production increased following a change in spreading rate, (3) a change in spreading ridge geometry led to more effective seafloor spreading rate and concurrent increase in melt production. The Western Domain of the Enderby Basin is characterized by abundant fracture zones and anomalously thin oceanic crust. We believe these features arose as a geometric consequence of the originally oblique orientation of continental rifting relative to the extension direction within the domain. Together these observations suggest that the breakup of East Gondwana was highly variable, with notable along-strike differences in crustal deformation and seafloor spreading processes.

中文翻译：

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南极东部恩德比盆地地壳结构

南极东部恩德比盆地的被动边缘和洋壳保留了东冈瓦纳破裂的记录。利用一套公共领域的地球物理数据，我们检查并描述了该盆地的地壳形态。根据我们的地球物理观测，我们将恩德比盆地分为三个不同的形态学区域。东部地区表现出该盆地最火山的形态，具有丰富的向海浸入式反射器包裹和异常厚的洋壳。这些特征表明Kerguelen热点地区对该区域内的大陆破裂有早期影响。中央区域的特征是由高振幅磁异常分隔的两个形态各异的洋壳区域。地球物理观测表明，该磁异常内部的直接基底由薄的，坚固的，结构不良的原始洋壳组成，其形态与超慢/慢洋中脊形成的洋壳相似。在这种异常的外侧，洋壳似乎结构良好且厚度正常。对于观察到的海洋地壳结构变化，我们提供了三种非排他性的解释：（1）在大陆破裂时，熔体产量最初较低，地幔逐渐减压导致熔体产量和海洋逐渐增加地壳厚度；（2）由于延伸率降低，熔体产量最初较低，并且随着铺展速率的变化，熔体产量增加，（3）扩散脊几何形状的变化导致更有效的海底扩散速率和熔体产量的同时增加。恩德比盆地西域的特征是大量的断裂带和异常稀薄的大洋地壳。我们认为，这些特征是由于大陆裂谷相对于域内延伸方向的最初倾斜方向的几何结果而产生的。这些观察结果共同表明，东冈瓦纳的破裂是高度可变的，在地壳形变和海底扩散过程中沿走动存在明显差异。我们认为，这些特征是由于大陆裂谷相对于域内延伸方向的最初倾斜方向的几何结果而产生的。这些观察结果共同表明，东冈瓦纳的破裂是高度可变的，在地壳形变和海底扩散过程中沿走动存在明显差异。我们认为，这些特征是由于大陆裂谷相对于域内延伸方向的最初倾斜方向的几何结果而产生的。这些观察结果共同表明，东冈瓦纳的破裂是高度可变的，在地壳形变和海底扩散过程中沿走动存在明显差异。