Magmatic and tectonic processes can contribute to discontinuous crustal accretion and play an important role in hydrothermal circulation at ultraslow-spreading ridges, however, it is difficult to accurately describe the processes without an age framework to constrain crustal evolution. Here we report on a multi-scale magnetic survey that provides constraints on the fine-scale evolution of a detachment faulting system that hosts hydrothermal activity at 49.7°E on the Southwest Indian Ridge. Reconstruction of the multi-stage detachment faulting history shows a previous episode of detachment faulting took place 0.76~1.48 My BP, while the present fault has been active for the past ~0.33 My and is just in the prime of life. This fault sustains hydrothermal circulation that has the potential for developing a large sulfide deposit. High resolution multiscale magnetics allows us to constrain the relative balance between periods of detachment faulting and magmatism to better describe accretionary processes on an ultraslow spreading ridge.

岩浆和构造过程可以促成不连续的地壳增生，并在超慢扩张脊的热液循环中发挥重要作用，但是，如果没有限制地壳演化的年龄框架，很难准确描述这些过程。在这里，我们报告了一项多尺度磁力测量，该测量对在西南印度洋脊上 49.7°E 进行热液活动的拆离断层系统的精细尺度演化提供了限制。多期拆离断裂历史重建显示，前一期拆离断裂发生在0.76~1.48 My BP，而现在的断层在过去~0.33 My BP一直活动，正处于盛年。该断层维持着热液循环，具有开发大型硫化物矿床的潜力。