东太平洋中国多金属结核开辟区东区构造地貌特征

Tectonic geomorphology characteristics in the east China Pioneer Area of the eastern Pacific Ocean

研究区位于东太平洋克拉里昂-克里帕顿断裂带之间的中国多金属结核开辟区东区。根据多波束水深以及单道地震资料,对研究区地形、构造地貌特征进行了分析。研究结果表明区内水深在3800—5700m之间,平均水深5100m,等深线呈NNW—SSE走向。研究区主要构造地貌类型为断裂型线状海丘地貌和岩浆活动型海山地貌两种。断裂型线状海丘地貌可进一步划分为东部丘陵区和西部丘陵区两个次级构造地貌单元。岩浆活动型海山地貌总体上呈长轴形展布,根据组合特征可分为A、B、C共3个分区。结合区域地质构造,认为断裂型线状海丘地貌主要与太平洋扩张所形成的张应力以及板块热沉降过程中所形成的NNW向断裂密切相关。岩浆活动型海山地貌与深部岩浆活动相关。岩浆喷发方式、规模和期次的差异可形成形态各异的海山。文章旨在探讨大洋地貌形成及演化机制,对深入了解大洋板块内部构造特征及形成演化规律等有指导意义。

The study area is located in the east China Pioneer Area of the eastern Pacific Ocean. Detailed analysis of the topography and tectonic geomorphology was carried out based on the multi-beam water depth data and single-channel seismic profiles combined with the geological setting in the Pacific Ocean. The water depth of the study area ranges between 5700 and 3800 m. The main tectonic geomorphology units in the study area are linear faulted hills and magma-type sea mountains. Linear faulted hills can be divided into west and east parts. Its size is controlled by the NNW-trending faults, and is supposed to be the result of the thermal subsidence of oceanic crust. Magma-type sea mountains, including three sub-zones, were formed by the eruption or incursion of magma deep beneath the oceanic crust. There are different sizes and shapes of sea mountains in the study area, including single peak and multi-peak mountains. The formation and evolution mechanism of oceanic morphology is discussed in this paper, and the results may contribute to the study of oceanic geomorphology and the associated dynamics.