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A区热液喷口(37.78°S,49.65°E)是在西南印度洋中脊(SWIR)上发现的第一个活动热液喷口.热源及水循环通道是形成热液喷口的两个必要条件.沿SWIR49.3°~51.2°E区域,重力反演的地壳厚度最厚超过9.0 km,远超过全球平均海洋地壳厚度,表明此区域存在丰富热源,可能受到了热点的影响.大尺度的地幔布格重力异常(RMBA)揭示了A区所在一级洋中脊段(Indomed-Gallieni转换断层,46.0°~52.0°E)和Marion-Del Cano-Crozet区域之间的重力低值带,推断为热点-洋中脊相互作用的路径.去除正常热模型后的层析成像资料表明,与此路径对应的低速带在垂直距离上可以到达岩石圈底部.A区热液喷口区域扩张脊两侧地形和地壳厚度明显不对称.在扩张脊南侧,高地形对应着减薄的地壳厚度.剩余均衡地形异常显示A区处于明显的非均衡状态,与转换断层内角的特征极为类似.磁力剖面的正演表明,A区南侧磁性减薄区域与OBS揭示的隆起高速异常区相对应,推断为拆离断层的构造减薄作用.A区强烈的构造活动可以为热液喷口提供充分的水循环通道,可能形成较大的热液硫化物矿床.
Zone A hydrothermal vents (37.78 ° S, 49.65 ° E) are the first active hydrothermal vents found on the Southwest Indian Ridge (SWIR) .Heat sources and water circulation channels are two prerequisites for hydrothermal vents In SWIR 49.3 ° ~ 51.2 ° E, the thickness of the crust retrieved by gravity is more than 9.0 km, far exceeding the global mean crustal thickness, indicating that there are abundant heat sources in this region and may be affected by hotspots. Large-scale mantle cloth The gravity anomaly (RMBA) reveals the low gravity band between the first-stage mid-oceanic ridges (Indomed-Gallieni transition fault, 46.0 ° -52.0 ° E) and Marion-Del Cano-Crozet region, And the mid-ocean ridge interaction.The tomographic data after removal of the normal thermal model show that the low-velocity zone corresponding to this path can reach the bottom of the lithosphere at a vertical distance.A topography and crust The thickness is obviously asymmetric.At the south of extension ridge, the high terrain corresponds to the thinned crustal thickness.The remaining anomalous topographic anomalies show that area A is obviously imbalanced, which is very similar to the characteristics of the transitional façade.The forward of magnetic section shows , A area south of the magnetic thinning The region corresponds to the uplifted high-velocity anomalous region revealed by OBS, which is inferred to be the tectonic thinning of the detachment fault.A strong tectonic activity in area A may provide sufficient water circulation channels for hydrothermal vents and may form a large hydrothermal sulfide deposit .