The glacial-interglacial siliceous productivity in the Sub-Antarctic Zone (SAZ) of the Southern Ocean (SO) has been proposed to respond to higher dust-bearing iron fluxes and/or basin-wide increased nutrient supply to surface waters. However, long records of diatom productivity are mainly obtained from the Atlantic and Pacific sectors of the SO. We present a new diatom productivity record from the SAZ of the western Indian sector of the SO, where the Antarctic Circumpolar Current strongly interacts with bottom topography to create a productivity hotspot, during the last four glacial-interglacial cycles. Our results show that regional changes in diatom productivity did not follow a glacial-interglacial pattern. It was highest during the Marine Isotope stage (MIS) 6 and MIS4, lowest during MIS10-MIS8 and MIS3-MIS1, whereas intermediate diatom productivity was found during MIS7 and MIS5. Multi-millennial events of high diatom productivity were scattered throughout both the glacial and interglacial periods. Both long-term and rapid diatom productivity changes in the region were disconnected from dust flux changes, but might relate to frontal migrations and SO upwelling intensity changes which have both mediated the silica and iron availability for diatoms. Importantly, our data suggest that front migrations were not homogenous in the SO, especially where these fronts interact with bottom topography. The peculiarity of these productivity hotspots must be considered when drawing SO-wide carbon balance in the past.

南大洋 (SO) 的亚南极带 (SAZ) 的冰期-间冰期硅质生产力已被提议用于响应更高的含尘铁通量和/或全流域增加的地表水养分供应。然而，硅藻生产力的长期记录主要来自 SO 的大西洋和太平洋地区。我们展示了 SO 西印度部分 SAZ 的新硅藻生产力记录，其中南极绕极流与底部地形强烈相互作用在最后四个冰川-间冰期周期中创造一个生产力热点。我们的结果表明，硅藻生产力的区域变化并不遵循冰期-间冰期模式。它在海洋同位素阶段 (MIS) 6 和 MIS4 期间最高，在 MIS10-MIS8 和 MIS3-MIS1 期间最低，而在 MIS7 和 MIS5 期间发现中间硅藻生产力。硅藻高产的千年事件分散在整个冰川期和间冰期。该地区的长期和快速硅藻生产力变化与尘埃通量变化无关，但可能与锋面迁移和 SO 上升流强度变化有关，这两者都调节了硅藻的二氧化硅和铁可用性。重要的是，我们的数据表明前迁移在 SO 中不是同质的，特别是在这些锋面与底部地形相互作用的地方。在绘制 SO-wide 时必须考虑这些生产力热点的特殊性过去的碳平衡。