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Lake Tennyson's basin and sedimentary record were assessed for multiple branches of paleoenvironmental research. A geophysical investigation of the lake depositional setting was supported by physical and chemical analysis of multiple sediment cores. The basin reaches 60 m depth and several subaerial landforms identified were likely deposited from seismic activity. Deformed sediments and turbidites in gravity cores are attributed to one or more large (pre)historic earthquakes, and episodic grain size changes in sediment cores are related to either seismic and/or climatic/meteorological processes. A hummocky slump deposit located on the western lake bed margin is linked to widespread sediment deformation that was likely caused by movement of the Awatere Fault. Radiocarbon dating constrains the most recent major deformation event between the late thirteenth century CE and mid-twentieth Century. Folded turbidites in the stratigraphy suggest multiple sedimentary deformation episodes occurred during the last millennium. Micro-XRF elemental signatures suggest proxies of past water column mixing (windiness proxy) can be reconstructed via identification of changing redox conditions. Records from Lake Tennyson show potential for several palaeoenvironmental research applications, and combining them with basin morphostratigraphy and land-based palaeoclimate and palaeoseismic evidence can enhance understanding of environmental change in the northern South Island. [ABSTRACT FROM AUTHOR]

We show that climate and topography control the spatial distribution of stable isotope values on the South Island of New Zealand, based on a spatially dense (n = 193) river isotopic survey. Our data show a δ18O minimum in isotope values east of the Southern Alps that demonstrates topographically driven continentality associated with the Southern Alps, which intersect the prevailing, moisture‐laden westerlies. Our data define a South Island surface water line of δ2H = 8.17 (±0.26) × δ18O + 10.57 (±2.04), which is identical within 95% confidence intervals to the global and New Zealand meteoric water lines established from monthly precipitation samples. The observed river δ18O values are strongly correlated with annual temperature range and winter temperature. Strongest correlations are between δ18O and mean minimum winter temperatures (r > 0.7 for June, July, August), with gradients of 0.58–0.66‰ /°C. Based on a multiple regression analysis of δ18O against climate data, we present a river δ18O model and isoscape that demonstrate the control of continentality and moisture source on New Zealand surface water isotope spatial patterns. Model validation against previously published river samples shows skill in predicting river δ18O values (root‐mean‐square error = 0.83), confirming that the spatial variations in river δ18O (and δ2H) are robust to sampling period and reflect continental, precipitation source and temperature effects. Our data suggest that oxygen or hydrogen isotope paleoclimate proxies derived from rivers or open‐system lakes on the South Island should be sensitive to winter temperature. Plain Language Summary: We investigated the spatial variations in oxygen and hydrogen stable isotopes in rivers on the South Island of New Zealand and show that they are strongly controlled by the presence of the Southern Alps. Indicators of continental climates, such as seasonal temperature range and temperature of the coldest months are strongly related to measured oxygen isotope values of river waters. We show that winter temperature and continentality are the dominant control on New Zealand South Island river oxygen isotope values, and they result in minimum values in the lee of the highest portion of the Southern Alps. We also show that river deuterium excess values are controlled by Pacific Ocean versus Tasman Sea moisture sources. Key Points: Survey of spatial river δ18O values on New Zealand's South Island shows strong correlations to winter temperature and continentalityLowest river δ18O values are present in the most continental locations in the lee of the high Southern AlpsData are useful for interpreting isotopic paleoclimate proxy records related to surface waters [ABSTRACT FROM AUTHOR]