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, Northern Territory, and Western Australia, as well as southern Africa and regions of South America south of similar to 37 degrees 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 ThandaLake 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. (C) 2020 Elsevier Ltd. All rights reserved.

We undertook geomorphological mapping in conjunction with Be-10 surface-exposure dating in a previously unstudied sector of the left-lateral moraine sequence of the ice-age Pukaki glacier in the Southern Alps of New Zealand. The mapping and dating approach enabled the identification of six distinct moraine belts that were formed during maxima of glacier extent during the last glaciation. The chronology implies that ice recession occurred during Northern Hemisphere Heinrich stadials, while expansion occurred between Heinrich stadials. The ages of the moraine belts identified here are 44,000 +/- 1000 yrs; 41,800 +/- 1100 yrs; 36,450 +/- 940 yrs 26,730 +/- 740 yrs; 20,030 +/- 460 yrs; and 18,000 400 yrs. This moraine chronology is consistent with previous dating results from other sectors of the Pukaki moraine sequence, except that the c. 44,000 yr old moraine belt has not previously been detected elsewhere in the Pukaki moraines. Collectively with previously published Be-10 chronologies from the Pukaki glacier, and the adjacent Ohau glacier valley, the results demonstrate that there were several millennial-scale episodes of ice advance to full-glacial extent, and subsequent ice recession, during Marine Isotope Stages 3 and 2. This millennial-scale pulsebeat of oscillations of the Pukaki and Ohau glaciers in sympathy with the North Atlantic Heinrich episodes is further emphasized by rapid ice recession in the Southern Alps early in the last glacial termination, coeval with the onset of Heinrich stadial 1 (HS 1) in the Northern Hemisphere. That this pattern is widespread in mid-latitudes of the Southern Hemisphere is highlighted by similar chronologies of glacier variation for Andean ice lobes in the Chilean Lake District of South America. (C) 2019 Elsevier Ltd. All rights reserved.

Cosmogenic in situ C-14 in quartz is rapidly becoming a widely used geochronological tool for studying earth surface processes over the last 30,000 years. The Lamont-Doherty Earth Observatory houses one of the longest continuously-operating cosmogenic in situ C-14 laboratories; in this contribution, we provide an update on the status of the laboratory following Goehring et al. (2014). From 2010 to the present, our long-term average blank value is 119,000 +/- 37,000 C-14 atoms, with no statistically significant trend over the last nine years. While our average measured C-14 concentration of the CRONUS-A inter-laboratory comparison standard is in line with data published from other laboratories, we note a step increase between 2013 and 2015 that is still under investigation. Additionally, we report our first procedural blanks and CRONUS-A values analyzed on the gas source of the ANMICADAS at CEREGE, France. Many of the > 75 samples analyzed at Lamont for in situ C-14 from the Arctic, Antarctic, New Zealand, and the Alps have been paired with Be-10 analyses contributing to the increasing density of burial dating data covering the last 20,000 years. Currently we are working on increasing sample throughput, streamlining the C-14 extraction procedure, and considerably decreasing blank levels.

Interhemispheric differences in the timing of pauses or reversals in the temperature rise at the end of the last ice age can help to clarify the mechanisms that influence glacial terminations. Our beryllium-10 (Be-10) surface-exposure chronology for the moraines of the upper Rakaia valley of New Zealand's Southern Alps, combined with glaciological modeling, show that late-glacial temperature change in the atmosphere over the Southern Alps exhibited an Antarctic-like pattern. During the Antarctic Cold Reversal, the upper Rakaia glacier built two well-defined, closely-spaced moraines on Reischek knob at 13,900 +/- 120 [1 sigma; +/- 310 yrs when including a 2.1% production-rate (PR) uncertainty] and 13,140 +/- 250 (370) yrs ago, in positions consistent with mean annual temperature approximately 2 degrees C cooler than modern values. The formation of distinct, widely-spaced moraines at 12,140 +/- 200 (320) and 11,620 +/- 160 (+/- 290) yrs ago on Meins Knob, 2 km up-valley from the Reischek knob moraines, indicates that the glacier thinned by similar to 250 m during Heinrich Stadial 0 (HS 0, coeval with the Younger Dryas 12,900 to 11,600 yrs ago). The glacier-inferred temperature rise in the upper Rakaia valley during HS 0 was about 1 degrees C. Because a similar pattern is documented by well-dated glacial geomorphologic records from the Andes of South America, the implication is that this late-glacial atmospheric climate signal extended from 79 degrees S north to at least 36 degrees S, and thus was a major feature of Southern Hemisphere paleoclimate during the last glacial termination. (C) 2017 Elsevier Ltd. All rights reserved.

Ice-shelf grounding lines off the coast of Antarctica have retreated over the past 20,000 years. Precise dating of moraines suggests the timing of retreat in the Ross Sea was controlled by the interplay between accumulation and ocean forcing.

The amplitude and timing of past glacier culminations are sensitive recorders of key climate events on a regional scale. Precisely dating young moraines using cosmogenic nuclides to investigate Holocene glacier chronologies has proven challenging, but progress in the high-sensitivity 10Be technique has recently been shown to enable the precise dating of moraines as young as a few hundred years. In this study we use 10Be moraine dating to reconstruct culminations of the Steingletscher, a small mountain glacier in the central Swiss Alps, throughout the Holocene. The outermost-recorded positions of Steingletscher most likely occurred in the Early Holocene and appear nearly synchronous with glacier culminations reported from other regions in the Alps. A Late-Holocene position corroborates the evidence for a significant glacier advance of similar extent to that of the Little Ice Age (LIA) ∼3kyr ago. Finally, fourteen boulders from different moraines yield 10Be ages between 580 and 140 years with analytical precisions mostly <10%, dating Steingletscher advances during the LIA. Because these LIA 10Be ages are in stratigraphic order, we tentatively distinguish four LIA glacier culminations: about 1470 CE, 1650 CE, 1750 CE and 1820 CE, which are in good agreement with existing independent records during the LIA in the Swiss Alps. These findings illustrate the high potential of the 10Be moraine dating method to directly link paleo-glacier-chronologies to historical records and thus present-day glacier evolution.

The termination of the last ice age featured a major reconfiguration of Earth's climate and cryosphere, yet the underlying causes of these massive changes continue to be debated. Documenting the spatial and temporal variations of atmospheric temperature during deglaciation can help discriminate among potential drivers. Here, we present a Be-10 surface-exposure chronology and glaciological reconstruction of ice recession following the Last Glacial Maximum (LGM) in the Rakaia valley, Southern Alps of New Zealand. Innermost LGM moraines at Big Ben have an age of 17,840 +/- 240 yrs, whereas ice-marginal moraines or ice-molded bedrock surfaces at distances up-valley from Big Ben of 12.5 km (Lake Coleridge), similar to 25 km (Castle Hill), similar to 28 km (Double Hill), similar to 43 km (Prospect Hill), and similar to 58 km (Reischek knob) have ages of 17,020 +/- 70 yrs, 17,100 +/- 110 yrs, 16,960 +/- 370 yrs, 16,250 +/- 340 yrs, and 15,660 +/- 160 yrs, respectively. These results indicate extensive recession of the Rakaia glacier, which we attribute primarily to the effects of climatic warming. In conjunction with geomorphological maps and a glaciological reconstruction for the Rakaia valley, we use our chronology to infer timing and magnitude of past atmospheric temperature changes. Compared to an overall temperature rise of similar to 4.65 degrees C between the end of the LGM and the start of the Holocene, the glacier recession between similar to 17,840 and similar to 15,660 yrs ago is attributable to a net temperature increase of similar to 4.0 degrees C (from -6.25 to -2.25 degrees C), accounting for similar to 86% of the overall warming. Approximately 3.75 degrees C (similar to 70%) of the warming occurred between similar to 17,840 and similar to 16,250 yrs ago, with a further 0.75 degrees C (similar to 16%) increase between similar to 16,250 and similar to 15,660 yrs ago. A sustained southward shift of the Subtropical Front (STF) south of Australia between similar to 17,800 and similar to 16,000 yrs ago coincides with the warming over the Rakaia valley, and suggests a close link between Southern Ocean frontal boundary positions and southern mid-latitude climate. Most of the deglacial warming in the Southern Alps occurred during the early part of Heinrich Stadial 1 (HS1) of the North Atlantic region. Because the STF is associated with the position of the westerly wind belt, our findings support the concept that a southward shift of Earth's wind belts accompanied the early part of HS1 cooling in the North Atlantic, leading to warming and deglaciation in southern middle latitudes. (C) 2013 Elsevier B.V. All rights reserved.