Was there a glacial outburst flood in the Torngat Mountains during Marine Isotope Stage 3?

We report previously unpublished evidence for a Marine Isotope Stage 3 (MIS 3; 60–26 ka) glacial outburst flood in the Torngat Mountains (northern Quebec/Labrador, Canada). We present 10Be cosmogenic exposure ages from legacy fieldwork for a glacial lake shoreline with evidence for outburst flooding in the Torngat Mountains, with a minimum age of 36 ± 3 ka (we consider the most likely age, corrected for burial, to be ~56 ± 3 ka). This shoreline position and age can potentially constrain the Laurentide Ice Sheet margin in the Torngat Mountains. This region, considered a site of glacial inception, has no published dated geologic constraints for high-elevation MIS 3 ice margins. We estimate the freshwater flux associated with the inferred glacial outburst flood using high-resolution digital elevation maps corrected for glacial isostatic adjustment. Using assumptions about the ice-dammed locations we find that a freshwater flood volume of 1.14 × 1012 m3 could have entered the Hudson Strait. This glacial outburst flood volume could have contributed to surface ocean freshening to cause a measurable meltwater signal in δ18O records, but would not necessarily have been associated with substantial ice rafted debris. Future work is required to refine estimates of the size and timing of such a glacial outburst flood. Nevertheless, we outline testable hypotheses about the Laurentide Ice Sheet and glacial outburst floods, including possible implications for Heinrich events and glacial inception in North America, that can be assessed with additional fieldwork and cosmogenic measurements.

Chapter 5.5 Gaussberg: volcanology and petrology

Gaussberg is a nunatak composed of lamproite pillow lava situated on the coast of East Antarctica. It is the most isolated Quaternary volcanic centre in Antarctica but it is important palaeoenvironmentally and petrologically out of all proportion to its small size. The edifice has a likely low, shield-like, morphology c. 1200 m high and possibly up to 10 km wide, which is unusually large for a lamproite construct. Gaussberg was erupted subglacially at 56 ± 5 ka, which places it late in the last glacial, close to the peak of marine isotope stage 3. The coeval ice sheet was c. 1300 m thick, and c. 420 m has been removed from the ice surface since Gaussberg erupted. Lamproite is a rare ultrapotassic mantle-derived magma, and Gaussberg is one of two type examples worldwide. Although traditionally considered as related in some way to the Kerguelen plume, it is more likely that the Gaussberg magma is a product of a separate magmatic event. It is ascribed to the storage and long-term (Gy) isolation of sediment emplaced by subduction in the Transition Zone of the deep mantle, followed by entrainment and subsequent melting in a plume.

Examining Neanderthal and carnivore occupations of Teixoneres Cave (Moià, Barcelona, Spain) using archaeostratigraphic and intra-site spatial analysis

Teixoneres Cave (Moià, Barcelona, Spain) is a reference site for Middle Palaeolithic studies of the Iberian Peninsula. The cave preserves an extensive stratigraphic sequence made up of eight units, which is presented in depth in this work. The main goal of this study is to undertake an initial spatial examination of Unit III, formed during Marine Isotope Stage 3, with the aim of understanding spatial organization and past activities developed by Neanderthals and carnivores (bears, hyenas and smaller carnivores). The total sample analysed includes 38,244 archaeological items and 5888 limestone blocks. The application of GIS tools allows us to clearly distinguish three geologically-defined stratigraphic subunits. Unit III has been previously interpreted as a palimpsest resulting from alternating occupation of the cave by human groups and carnivores. The distribution study shows that faunal specimens, lithic artefacts, hearths and charcoal fragments are significantly concentrated at the entrance of the cave where, it is inferred, hominins carried out different activities, while carnivores preferred the sheltered zones in the inner areas of the cave. The results obtained reveal a spatial pattern characterized by fire use related zones, and show that the site was occupied by Neanderthals in a similar and consistent way throughout the ˃ 7000 years range covered by the analysed subunits. This spatial pattern is interpreted as resulting from repeated short-term human occupations.

On Making of Micoquian Bifacial Backed Tools at Pietraszyn 49a, SW Poland

This paper attempts to show that manufacture of Micoquian bifacial backed tools was structured. Data for this study were collected using a comprehensive analysis of artefacts from the site Pietraszyn 49a, Poland, which is dated to the beginning of Marine Isotope Stage 3. Based on the whole data set, it was possible to distinguish four stages of the manufacturing process. During manufacturing, both mineral hammer and organic hammer were used. The tools were usually shaped due to distinct hierarchization of faces. The study has also shown that the shape of bifacial tools from Pietraszyn 49a is very similar to the other Micoquian examples from central Europe. The ways of shaping of some tools are finding their counterparts also in the Early Upper Palaeolithic inventories, but the similarities are rather limited to the narrow range of preparation of bifacial form.

Millennial-scale oceanic CO2 release during marine isotope stage 3

<p>During the last glacial period atmospheric CO<sub>2</sub> and temperature in Antarctica varied together on millennial timescales, with CO<sub>2</sub> abruptly increasing by 10-20 ppm in <1000 years in some cases. The exact causes of these rapid CO<sub>2</sub> changes during a cold glacial climate remain unclear. Here we examine the role of ocean carbon storage and atmospheric exchange by applying the boron isotope-pH (CO<sub>2</sub>) proxy to Globigerina bulloides from core site TAN110628 located in the Pacific Sector of the Southern Ocean.  By reconstructing the surface carbonate system at TAN110628 at high temporal resolution (1 sample every 1 kyr) from 30 to 64 kyr we are able to fully constrain the nature of carbon leakage from the Sub Antarctic Zone of the Southern Pacific Ocean associated with these millennial-scale changes in atmospheric CO<sub>2</sub>.  This provides unique insights into the causes of abrupt changes in atmospheric CO<sub>2</sub> during Marine Isotope Stage 3 and the last termination. </p>