Abstract The variations in faulting style at the Southwest Indian Ridge (SWIR) 46°–53.5°E segment, correspond to different patterns of crustal accretion under different magma supply in an ultraslow-spreading ridge. We use multi-beam and filtered bathymetry to identify the fault characteristics and measure the fraction of magmatic accretion M and axial valley depth D. Four styles of faulting, namely, mode-C, mode-E, one-side detachment, and flip-flop detachment faults, are identified in the study area. The heave of these four faulting styles tends to increase gradually, and these faults can be progressive evolve in order from symmetrical to asymmetrical spreading. The reducing M significantly affects the faulting styles from mode-C to mode-E faults by largening fault heave, resulting in a deeper D at mode-E faults. However, there was no significant difference in M and D from mode-E to one-side detachment faults with the increase of heave. We consider that more magma may preferentially intrude into the asthenosphere at one-side detachment faults. Moreover, the flip-flop detachment faults are developed at the amagmatic segments, constrained by the extreme low M, talc- serpentinization, and dense transform faults.

中文翻译：

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西南印度洋脊（46°-53.5°E）断层样式的变化：对超慢扩张脊地壳增生过程的影响

摘要 西南印度洋脊（SWIR）46°～53.5°E段断层样式的变化，对应于超慢扩张脊内不同岩浆供给下的不同地壳增生模式。我们使用多波束和滤波测深法来识别断层特征并测量岩浆吸积的比例 M 和轴向谷深 D。 四种断层类型，即模式 C、模式 E、一侧脱离和翻转在研究区确定了触发器脱离断层。这四种断层类型的隆起有逐渐增大的趋势，这些断层可以由对称向不对称扩展的顺序渐进演化。减小 M 通过增大断层隆起显着影响从模式 C 到模式 E 断层的断层样式，导致模式 E 断层处的 D 更深。然而，随着垂荡的增加，从模式E到一侧脱离断层的M和D没有显着差异。我们认为更多的岩浆可能会优先侵入一侧脱离断层的软流圈。此外，触发器拆离断层发育在岩浆段，受极低 M、滑石化和致密变换断层的限制。