Loess up to 10 m thick covers marine terraces, old river aggradation terraces, and gentle hill country slopes in Wairarapa, New Zealand. In the drier eastern and southern parts of Wairarapa, the loess is subject to dry summer and autumn and wet winter and spring in most years. Under these conditions, and in association with strongly seasonal evapotranspiration, the loess has formed Pallic Soils. The objective of this study is to define physical and geotechnical properties to explain the field behaviour of the loess in order to support applications in agriculture and engineering works. From the outset, Wairarapa loess may have been already more rich in clay than many other deposits around the world, because of the Mesozoic greywacke-argillite parent rock from which it was derived. Wairarapa loess is characterized by being very compacted, with subsoil fragipans with densities up to 1.8 Mg m-3. In winter, water perches on the impermeable fragipan, saturating the soil above, often to the surface. Wetting and drying in this zone promotes weathering, clay formation and translocation. Ohakean and Ratan loess deposits are more silty than the underlying clay-rich Porewan loess. Whereas the former loesses blew from extensive low angle aggrading fans, at least some of the Porewan loess was derived from lacustrine deposits on the floor of Wairarapa Valley. Textures of all Wairarapa loess, and particularly the Porewan loess, are clay-rich. The weathering regime and textures result in extremely low hydraulic conductivity for the loess. Atterberg limit tests indicate that the loesses, particularly the Porewan loess and underlying lacustrine clays, are poor to very poor construction materials. Atterberg limits also help to understand the behaviour of wet Pallic Soils under stocking and traffic. Pallic Soils compact readily when moist and are very weak when saturated, acting as liquids when disturbed, resulting in extreme pugging, dispersion, and soil loss. Pallic Soils in Wairarapa are prone to shallow landslides, even on gentle slopes because of their loss of strength when saturated.
Late Cenozoic strata of the northern Canterbury Basin record uplift and erosion of mountain ranges adjacent to the transition from oblique subduction to strike-slip on the Australian-Pacific plate boundary. Using the provenance of conglomerate clasts and sandstone samples, we reconstruct sediment transport pathways and, by inference, exhumation and reverse faulting during plate boundary development in the northeastern South Island. In the Middle-Late Miocene, isolated topographic highs within the modern Marlborough Fault System are interpreted to have supplied sediment into the northern Canterbury Basin, with sediment transported towards the southwest and southeast. By the Late Pliocene-Early Pleistocene, the provenance signature can be explained using sediment transport pathways similar to modern rivers, with sediment being supplied into the northern Canterbury Basin towards the southeast from exhumation adjacent to the Alpine Fault. A drainage reorganisation prior to the Late Pliocene was possibly driven by a southwestward transfer of exhumation onto the Alpine Fault. Our study also suggests the existence of a northeast-flowing longshore current from at least the Middle Miocene to the present. A minor volume of sand-sized grains has been recycled from the underlying cover stratigraphy but is considered unlikely to alter our provenance interpretations.
This study presents the first application of a dual‐band satellite thermal monitoring technique in New Zealand and Tonga, using the 2019 eruption of Whakaari/White Island and the persistently active Lofia crater on Tofua volcano as case studies. At Whakaari/White Island, near‐synchronous Landsat‐8 and Sentinel‐2A data (16 min interval) were analysed using the Thermal Eruption Index (TEI) to constrain analyses to hotspot pixels with the strongest thermal signatures. Single‐band SWIR brightness temperatures (BT) produced peak values of 237–262 °C (Landsat‐8) and 244–287 °C (Sentinel‐2A). The dual‐band method significantly improved these estimates, producing temperatures of 418.7–477 °C (Landsat‐8 SWIR + TIRS) and 432.3 –540.8 °C (Sentinel‐2A SWIR + Landsat‐8 TIRS). Notably, Sentinel‐2A dual‐band results align more closely with airborne FLIR measurements collected 9 days earlier, which recorded maximum vent temperatures in the range of 410.2–589.2 °C. This improved agreement reflects the importance of finer 20 m SWIR spatial resolution of Sentinel‐2 in better resolving small, high‐temperature heat sources compared to Landsat‐8's 30 m resolution. At Tofua volcano (Tonga), three Landsat‐8 scenes spanning contrasting levels of thermal activity were analysed. For the non‐saturated May 2020 acquisitions, the maximum dual‐band temperature increased from 968.8 °C on 11 May 2020 to 1102.7 °C on 27 May 2020 following an eruptive episode, demonstrating the method's sensitivity to temporal changes in eruptive intensity. The September 2021 scene was characterised by SWIR‐band saturation within the central lava‐lake pixel, preventing direct retrieval of its brightness temperature; however, dual‐band estimates for the adjacent pixel reached up to 1187.3 °C, consistent with upper‐range basaltic lava lake temperatures. Overall, the dual‐band approach enhances quantification of sub‐pixel volcanic heat sources and demonstrates strong potential for operational thermal monitoring.
The 196 invertebrate holotypes held in the University of Otago Department of Geology are catalogued in detail. A short history of the Geology Museum, notable contributors to the invertebrate collection, highlights of the collection and notes on the information provided are followed by a list of the holotypes under eight phyla: Porifera, Cnidaria, Mollusca, Brachiopoda, Bryozoa, Echinodermata, Arthropoda and Hemichordata. Where name changes have occurred, the original name and latest name are given, the specimens are briefly described, and locality, geological age and lithology information are provided.
Strong westerly winds over Patagonia deliver substantial aeolian dust to the South Atlantic Ocean. While previous research indicates potential nutrient enrichment for primary producers, direct evidence of its impacts on the microbial food web remains scarce. Here, an in situ experiment was conducted aboard the R/V Puerto Deseado in November 2017 to investigate the effects of aeolian dust deposition on nitrogen uptake by primary producers and the microbial food web. Seawater was collected, pre-filtered (200 & micro;m) and divided into treatments with and without dust addition and incubated for 3 days. Macronutrient availability, humic substances (HS), chromophoric dissolved organic matter (CDOM) (0, 48 h) and microbial cell counts (0, 48, 72 h) were analysed. Nitrogen uptake was assessed over 0-24 h and 48-72 h periods. Dust addition doubled nitrate and ammonium concentrations. Surprisingly, a 50% reduction in primary productivity was observed. Microbial biomass exhibited an initial negative response during the first 48 h, followed by a slight recovery. This study provides the first direct measurements of the impacts of aeolian dust on nitrogen uptake and microbial communities in the Southwest Atlantic Ocean. The observed inhibitory effects on primary producers highlight the need for future studies to identify the underlying mechanisms, including toxic metal effects, reduced iron bioavailability due to adsorption or stimulation of specific prokaryotic or viral pathogens.
