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首页> 外文期刊>Earth and Planetary Science Letters: A Letter Journal Devoted to the Development in Time of the Earth and Planetary System >Focused volcanism and growth of a slow spreading segment (Mid-Atlantic Ridge, 35°N)
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Focused volcanism and growth of a slow spreading segment (Mid-Atlantic Ridge, 35°N)

机译：集中的火山活动和缓慢扩展的部分的增长（中大西洋海脊，北纬35°）

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摘要

Using off axis bathymetry, gravity and magnetic data, we studied the formation of a prominent seamount chain across segment OH1 (Mid-Atlantic Ridge, 35°N), and its relation to the past segmentation of the area. We also studied the size and shape of the seamounts to understand the processes leading to their formation. The chain is elongated in the spreading direction, and extends from the present day segment center to ～6 Ma on both flanks. It coincides with a pronounced low in the residual mantle Bouguer gravity anomaly, suggesting thicker crust and thus more abundant magmatism than in surrounding areas. Magnetic anomalies are well defined over the seamount chain, consistent with formation on or near the axis. The seamounts within the chain are larger on average than those from other areas of the Mid-Atlantic Ridge, reflecting higher magma volumes and fluxes during eruptions. The distribution of seamounts suggests a focused magmatic source, located beneath the eastern side of the ridge axis, at a constant distance (～45 km) from the Oceanographer transform fault. A V-shaped trend defines the southern end of OH1 and indicates that the segment propagated rapidly southwards, increasing in length from 50 to 90 km. The onset of propagation at ～6 Ma coincided with the initiation of the volcanic chain, suggesting that magma supply at that time was focused at the end of the segment rather than at its center, as is typical for Mid-Atlantic Ridge segments. We propose that this unusual configuration is a consequence of the cold edge effect of the Oceanographer fracture zone. We also propose that enhanced and focused magmatism beneath the seamount chain may have caused the rapid southward propagation of OH1 over the past ～6 Ma.
机译：利用离轴测深法，重力和磁学数据，我们研究了横跨段OH1（大西洋中脊，35°N）的一条重要海山链的形成，及其与该地区过去的分割的关系。我们还研究了海山的大小和形状，以了解导致其形成的过程。链条在传播方向上拉长，并从今天的链段中心延伸到两侧的〜6 Ma。它与剩余地幔布格重力异常明显偏低相符，表明地壳较厚，因此岩浆比周围地区丰富。在海山链上已很好地定义了磁异常，这与轴上或附近的地层一致。平均而言，链条中的海山要比大西洋中脊其他地区的海山要大，这反映出喷发期间的岩浆量和通量较高。海山的分布表明，一个集中的岩浆源位于海脊轴线的东侧下方，与海洋学家转换断层保持恒定距离（〜45 km）。 V形趋势定义了OH1的南端，表明该段迅速向南传播，长度从50 km增加到90 km。 〜6 Ma的传播开始与火山链的开始相吻合，表明当时的岩浆供应集中在该段的末端而不是中心，这是大西洋中脊段的典型现象。我们认为这种异常的构造是海洋学家断裂带冷边缘效应的结果。我们还提出，海山链下的增强的和集中的岩浆作用可能导致了过去〜6 Ma OH1的快速向南传播。

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