Abstract The chemical and isotopic compositions of sediments and dust can be used to trace their provenance, providing insights into many Earth surface processes. During past glacial climates, much of the New Zealand (NZ) South Island was blanketed by erosive glacier systems that produced large volumes of sediment. We estimate the expansion of glacial outwash plains based on a sea level lowering of 130 m at the Last Glacial Maximum (LGM), and find that the Canterbury Plains in the central South Island likely expanded by 30,000 km2, a nearly five-fold increase, while the Southland/southern Otago region may have extended southward to cover an additional ∼45,000 km2, an eight-fold increase of the coastal plain area. Considering NZ’s extreme uplift and erosion rates (∼10 m kyr−1), the South Island, though limited in extent compared to larger Southern Hemisphere landmasses, may serve as an important dust source to the high-latitude atmosphere and ocean. To facilitate accurate tracing of the extent of aeolian and oceanic transport of NZ dust, this study presents major/trace element and Sr-Nd-Pb isotope ratios on sediments from the major present-day dust and sediment producing regions of the South Island. The sediment compositions strongly reflect the regional geology. For example, compared to the central South Island, Nd isotope ratios in the southern South Island are more variable and show younger crustal residence ages. The combined Sr-Nd-Pb isotopic ratios show that the central NZ South Island can be distinguished geochemically from many other Southern Hemisphere dust sources. Although isotopic similarities between the central NZ South Island and more northerly regions of South America, including Central Western Argentina and the Puna-Altiplano Plateau, and Kati Thanda-Lake Eyre in Australia (based on new data in this study) hinder downstream source attribution, a key finding is that these isotopes successfully discriminate NZ from other locations in Australia, such as the Murray-Darling Basin, Northern Territory, and Western Australia, as well as southern Africa and regions of South America south of ∼37°S (Patagonia and Tierra del Fuego). A comparison of the NZ data with East Antarctic ice core dust samples indicates that NZ was not a significant dust supplier to East Antarctica; rather, the East Antarctic dust compositions can be explained by dust supplied by Patagonia, Tierra del Fuego, and Central Western Argentina in South America, and West Antarctic Rift System volcanism. In contrast, the compositions of marine sediments in the Pacific sector of the Southern Ocean are compatible with mixing of South and North Island NZ dust sources, consistent with NZ’s role as an active dust supplier to the Southern Ocean. New data from Kati Thanda-Lake Eyre in Australia show that it may also be a contributor, if dust from this region is able to reach the Pacific sector independent of other Australian sources.

中文翻译：

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新西兰是大气和海洋矿物粉尘的来源

摘要 沉积物和尘埃的化学和同位素组成可用于追踪它们的来源，从而深入了解许多地球表面过程。在过去的冰川气候中，新西兰 (NZ) 南岛的大部分地区都被侵蚀性冰川系统覆盖，产生了大量沉积物。我们根据末次盛冰期 (LGM) 时海平面下降 130 m 来估计冰川外冲平原的扩张，发现南岛中部的坎特伯雷平原可能扩张了 30,000 平方公里，增加了近五倍，而南地/南奥塔哥地区可能已经向南延伸，覆盖了额外的约 45,000 平方公里，沿海平原面积增加了八倍。考虑到新西兰的极端抬升和侵蚀速率 (∼10 m kyr−1)，南岛，尽管与较大的南半球陆地相比，其范围有限，但可能是高纬度大气和海洋的重要尘埃源。为便于准确追踪新西兰灰尘的风成和海洋传输范围，本研究提供了南岛现今主要灰尘和沉积物产区沉积物的主要/微量元素和 Sr-Nd-Pb 同位素比率。沉积物成分强烈地反映了区域地质。例如，与南岛中部相比，南岛南部的 Nd 同位素比率变化更大，显示出更年轻的地壳居住年龄。综合 Sr-Nd-Pb 同位素比表明，新西兰南岛中部可以从地球化学上与许多其他南半球尘埃源区分开来。尽管新西兰南岛中部与南美洲更北部地区（包括阿根廷中西部和普纳-高原高原以及澳大利亚的卡蒂坦达-艾尔湖）之间的同位素相似性（基于本研究的新数据）阻碍了下游来源的归因，一个关键发现是，这些同位素成功地将新西兰与澳大利亚的其他地方区分开来，例如墨累-达令盆地、北领地和西澳大利亚，以及南部非洲和南美洲约 37°S 以南的地区（巴塔哥尼亚和火地岛）。新西兰数据与南极东部冰芯尘埃样本的比较表明，新西兰不是南极东部的重要尘埃供应国；相反，南极东部的尘埃成分可以用巴塔哥尼亚、火地岛、和南美洲的中西部阿根廷，以及西南极裂谷系统火山活动。相比之下，南大洋太平洋部分海洋沉积物的成分与新西兰南岛和北岛尘埃源的混合相容，这与新西兰作为南大洋活跃尘埃供应者的角色一致。来自澳大利亚 Kati Thanda-Lake Eyre 的新数据表明，如果该地区的灰尘能够独立于其他澳大利亚来源到达太平洋地区，它也可能是一个贡献者。