title: Pacific climate reflected in Waipuna Cave drip water hydrochemistry

authors: Nava-Fernandez, Cinthya

abstract: Cave microclimate and geochemical monitoring is vitally important for correct interpretations of proxy time series from speleothems with regard to past climatic and environmental dynamics. We present results of a comprehensive cave-monitoring programme in Waipuna Cave in the North Island of New Zealand, a region that is strongly influenced by the Southern Westerlies and the El Niño–Southern Oscillation (ENSO). This study aims to characterise the response of the Waipuna Cave hydrological system to atmospheric circulation dynamics in the southwestern Pacific region in order to assure the quality of ongoing palaeo-environmental reconstructions from this cave. Drip water from 10 drip sites was collected at roughly monthly intervals for a period of ca. 3 years for isotopic (δ18O, δD, d-excess parameter, δ17O, and 17Oexcess) and elemental (Mg∕Ca and Sr∕Ca) analysis. The monitoring included spot measurements of drip rates and cave air CO2 concentration. Cave air temperature and drip rates were also continuously recorded by automatic loggers. These datasets were compared to surface air temperature, rainfall, and potential evaporation from nearby meteorological stations to test the degree of signal transfer and expression of surface environmental conditions in Waipuna Cave hydrochemistry. Based on the drip response dynamics to rainfall and other characteristics, we identified three types of discharge associated with hydrological routing in Waipuna Cave: (i) type 1 – diffuse flow, (ii) type 2 – fracture flow, and (iii) type 3 – combined flow. Drip water isotopes do not reflect seasonal variability but show higher values during severe drought. Drip water δ18O values are characterised by small variability and reflect the mean isotopic signature of precipitation, testifying to rapid and thorough homogenisation in the epikarst. Mg∕Ca and Sr∕Ca ratios in drip waters are predominantly controlled by prior calcite precipitation (PCP). Prior calcite precipitation is strongest during austral summer (December–February), reflecting drier conditions and a lack of effective infiltration, and is weakest during the wet austral winter (July–September). The Sr∕Ca ratio is particularly sensitive to ENSO conditions due to the interplay of congruent or incongruent host rock dissolution, which manifests itself in lower Sr∕Ca in above-average warmer and wetter (La Niña-like) conditions. Our microclimatic observations at Waipuna Cave provide a valuable baseline for the rigorous interpretation of speleothem proxy records aiming at reconstructing the past expression of Pacific climate modes.

text: Pacific climate reflected in Waipuna Cave drip water hydrochemistry Cave microclimate and geochemical monitoring is vitally important for correct interpretations of proxy time series from speleothems with regard to past climatic and environmental dynamics. We present results of a comprehensive cave-monitoring programme in Waipuna Cave in the North Island of New Zealand, a region that is strongly influenced by the Southern Westerlies and the El Niño–Southern Oscillation (ENSO). This study aims to characterise the response of the Waipuna Cave hydrological system to atmospheric circulation dynamics in the southwestern Pacific region in order to assure the quality of ongoing palaeo-environmental reconstructions from this cave. Drip water from 10 drip sites was collected at roughly monthly intervals for a period of ca. 3 years for isotopic (δ18O, δD, d-excess parameter, δ17O, and 17Oexcess) and elemental (Mg∕Ca and Sr∕Ca) analysis. The monitoring included spot measurements of drip rates and cave air CO2 concentration. Cave air temperature and drip rates were also continuously recorded by automatic loggers. These datasets were compared to surface air temperature, rainfall, and potential evaporation from nearby meteorological stations to test the degree of signal transfer and expression of surface environmental conditions in Waipuna Cave hydrochemistry. Based on the drip response dynamics to rainfall and other characteristics, we identified three types of discharge associated with hydrological routing in Waipuna Cave: (i) type 1 – diffuse flow, (ii) type 2 – fracture flow, and (iii) type 3 – combined flow. Drip water isotopes do not reflect seasonal variability but show higher values during severe drought. Drip water δ18O values are characterised by small variability and reflect the mean isotopic signature of precipitation, testifying to rapid and thorough homogenisation in the epikarst. Mg∕Ca and Sr∕Ca ratios in drip waters are predominantly controlled by prior calcite precipitation (PCP). Prior calcite precipitation is strongest during austral summer (December–February), reflecting drier conditions and a lack of effective infiltration, and is weakest during the wet austral winter (July–September). The Sr∕Ca ratio is particularly sensitive to ENSO conditions due to the interplay of congruent or incongruent host rock dissolution, which manifests itself in lower Sr∕Ca in above-average warmer and wetter (La Niña-like) conditions. Our microclimatic observations at Waipuna Cave provide a valuable baseline for the rigorous interpretation of speleothem proxy records aiming at reconstructing the past expression of Pacific climate modes.

year: 2020

title: Spaces of relocation and trauma: affect and proximity after the Christchurch earthquakes, Aotearoa New Zealand

authors: Hutcheson, Gail Yvonne

subjects: Disasters; Relocation; Emotion; Affect; Trauma

abstract: This project combines established areas of geographical thought on disasters and natural hazards with emerging work on emotion and affect.

text: Spaces of relocation and trauma: affect and proximity after the Christchurch earthquakes, Aotearoa New Zealand This project combines established areas of geographical thought on disasters and natural hazards with emerging work on emotion and affect.

year: 2014

title: Dendroarchaeology in New Zealand: extending the range of archaeologically useful species beyond kauri (Agathis australis)

authors: Boswijk, Gretel

abstract: Accurately establishing calendar dates for Māori wooden objects would place them in a secure temporal context and enable aspects of manufacturing and use to be explored within and between sites, and across time. Dendrochronology has the potential to produce accurate and precise calendar dates for wooden artefacts but in New Zealand application of this technique to Māori cultural material is limited as there is almost no overlap between wood species found in archaeological contexts and tree-species with proven suitability for tree-ring dating. Here we identify five archaeologically-useful species – kahikatea (Dacrycarpus dacrydioides), matai (Prumnopitys taxifolia), miro (Prumnopitys ferruginea), rimu (Dacrydium cupressinum) and totara (Podocarpus totara) – and assess their potential for dendrochronology. Of these, matai, miro and totara are identified as species that should be the subject of further comprehensive dendrochronological investigation.

text: Dendroarchaeology in New Zealand: extending the range of archaeologically useful species beyond kauri (Agathis australis) Accurately establishing calendar dates for Māori wooden objects would place them in a secure temporal context and enable aspects of manufacturing and use to be explored within and between sites, and across time. Dendrochronology has the potential to produce accurate and precise calendar dates for wooden artefacts but in New Zealand application of this technique to Māori cultural material is limited as there is almost no overlap between wood species found in archaeological contexts and tree-species with proven suitability for tree-ring dating. Here we identify five archaeologically-useful species – kahikatea (Dacrycarpus dacrydioides), matai (Prumnopitys taxifolia), miro (Prumnopitys ferruginea), rimu (Dacrydium cupressinum) and totara (Podocarpus totara) – and assess their potential for dendrochronology. Of these, matai, miro and totara are identified as species that should be the subject of further comprehensive dendrochronological investigation.

year: 2019