New Zealand as a source of mineral dust to the atmosphere and ocean
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 se...
| Published in: | Quaternary Science Reviews |
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| Main Authors: | , , , , , , , , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
2021
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| Subjects: | |
| Online Access: | https://curis.ku.dk/portal/da/publications/new-zealand-as-a-source-of-mineral-dust-to-the-atmosphere-and-ocean(24dac821-7046-44bc-84a7-043795d1662d).html https://doi.org/10.1016/j.quascirev.2020.106659 https://curis.ku.dk/ws/files/333301627/1_s2.0_S0277379120306211_am.pdf |
| Summary: | 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 km(2), a nearly five-fold increase, while the Southland/southern Otago region may have extended southward to cover an additional similar to 45,000 km(2), an eight-fold increase of the coastal plain area. Considering NZ's extreme uplift and erosion rates (similar to 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 PunaAltiplano 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, ... |
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