DataSheet1_Glacial history and depositional environments in little Storfjorden and Hambergbukta of Arctic Svalbard since the younger dryas.docx

Geophysical and lithological data provide crucial information for the understanding of glacial history in Arctic Svalbard. In this study, we reconstructed the glacier-induced depositional environments of Little Storfjorden and its tributary, Hambergbukta, over the last 13 ka to better understand the glacial history of southeastern Svalbard. The combined uses of swath-bathymetry, high-resolution seismic stratigraphy, and multiple-proxy measurements of sediment cores allowed us to define five steps of glacier-induced depositional environments: 1) deposition of massive, semi-consolidated gravelly sandy mud (Facies 1) during re-advance or still-stand of the marine-based glaciers/ice streams in Little Storfjorden during Younger Dryas (13–12 ka); 2) deposition of massive mud to gravelly sandy mud (Facies 2A and B) during glacial retreat until the earliest Holocene (12–10.1 ka); 3) sediment winnowing by enhanced bottom currents during the early to middle Holocene (10.1–3.7 ka); 4) deposition of bioturbated sandy mud (Facies 3) with high productivity under seasonal sea ice conditions during the late Holocene (3.7–0.7 ka); and 5) deposition of (slightly) bioturbated sandy to gravelly mud (Facies 4) affected by glacier surges since Little Ice Age (LIA) (Facies 4). In addition to seismic stratigraphy, depositional patterns of IRD in Little Storfjorden indicate that the glacier surges in Hambergbukta occurred only after ∼0.7 ka. This suggests that the terminal moraine complex (TMC) represents the maximum extent of the LIA surges, which argues against the recent inference for the TMC formation during pre-LIA. This study shows the importance of multiple parameters to better understand the current behavior of tidewater glaciers in the Svalbard fjords in response to rapid climate change.

地球物理与岩石学数据可为解析北极斯瓦尔巴群岛的冰川演化历史提供关键依据。本研究针对斯瓦尔巴群岛东南部的小斯托尔峡湾（Little Storfjorden）及其支流哈姆贝格湾（Hambergbukta），重建了过去13千年间冰川作用形成的沉积环境，以深入解析该区域的冰川演化历史。本研究结合条带测深、高分辨率地震地层学以及沉积物岩芯多代用指标测试数据，明确了该区域冰川作用沉积环境的五个演化阶段：1）新仙女木期（13–12 ka）期间，小斯托尔峡湾内海洋基冰川/冰流发生再前进或停滞阶段，沉积了块状半固结砾质砂质泥（岩相（Facies）1）；2）冰川退缩阶段直至早全新世（12–10.1 ka），沉积了块状泥岩至砾质砂质泥岩（岩相2A和2B）；3）早全新世至中全新世（10.1–3.7 ka）期间，增强的底流对沉积物进行了淘蚀分选；4）晚全新世（3.7–0.7 ka）期间，在季节性海冰覆盖且高生产力的环境下，沉积了受生物扰动的砂质泥岩（岩相3）；5）自小冰期（Little Ice Age, LIA）以来受冰川涌流影响，沉积了（轻微）受生物扰动的砂质至砾质泥岩（岩相4）。除地震地层学数据外，小斯托尔峡湾内冰筏碎屑（Ice Rafted Debris, IRD）的沉积模式也表明，哈姆贝格湾的冰川涌流仅发生在约0.7 ka之后。这表明终碛垄复合体（Terminal Moraine Complex, TMC）代表了小冰期冰川涌流的最大影响范围，与近期提出的“终碛垄复合体形成于小冰期前”的推论相悖。本研究证实了多参数分析的重要性，可为深入理解斯瓦尔巴群岛峡湾内潮汐冰川对快速气候变化的响应机制提供支撑。