scholarly journals Comment on: Cosmogenic nuclide chronology of pre-last glacial maximum moraines at Lago Buenos Aires, 46°S, Argentina (Quaternary Research 63/3, 2005, 301–315)

2006 ◽  
Vol 66 (2) ◽  
pp. 364-366 ◽  
Author(s):  
Gerd Wenzens
Keyword(s):  
Last Glacial Maximum ◽  
Buenos Aires ◽  
Glacial Maximum ◽  
Last Glacial ◽  
Cosmogenic Nuclide

scholarly journals New Last Glacial Maximum ice thickness constraints for the Weddell Sea Embayment, Antarctica

2019 ◽  
Vol 13 (11) ◽  
pp. 2935-2951 ◽  
Author(s):  
Keir A. Nichols ◽  
Brent M. Goehring ◽  
Greg Balco ◽  
Joanne S. Johnson ◽  
Andrew S. Hein ◽  
...  
Keyword(s):  
Sea Level ◽  
Last Glacial Maximum ◽  
Glacial Maximum ◽  
Weddell Sea ◽  
Ice Thickness ◽  
Last Glacial ◽  
Cosmogenic Nuclide ◽  
Ice Stream ◽  
Exposure Ages

Abstract. We describe new Last Glacial Maximum (LGM) ice thickness constraints for three locations spanning the Weddell Sea Embayment (WSE) of Antarctica. Samples collected from the Shackleton Range, Pensacola Mountains, and the Lassiter Coast constrain the LGM thickness of the Slessor Glacier, Foundation Ice Stream, and grounded ice proximal to the modern Ronne Ice Shelf edge on the Antarctic Peninsula, respectively. Previous attempts to reconstruct LGM-to-present ice thickness changes around the WSE used measurements of long-lived cosmogenic nuclides, primarily 10Be. An absence of post-LGM apparent exposure ages at many sites led to LGM thickness reconstructions that were spatially highly variable and inconsistent with flow line modelling. Estimates for the contribution of the ice sheet occupying the WSE at the LGM to global sea level since deglaciation vary by an order of magnitude, from 1.4 to 14.1 m of sea level equivalent. Here we use a short-lived cosmogenic nuclide, in situ-produced 14C, which is less susceptible to inheritance problems than 10Be and other long-lived nuclides. We use in situ 14C to evaluate the possibility that sites with no post-LGM exposure ages are biased by cosmogenic nuclide inheritance due to surface preservation by cold-based ice and non-deposition of LGM-aged drift. Our measurements show that the Slessor Glacier was between 310 and up to 655 m thicker than present at the LGM. The Foundation Ice Stream was at least 800 m thicker, and ice on the Lassiter Coast was at least 385 m thicker than present at the LGM. With evidence for LGM thickening at all of our study sites, our in situ 14C measurements indicate that the long-lived nuclide measurements of previous studies were influenced by cosmogenic nuclide inheritance. Our inferred LGM configuration, which is primarily based on minimum ice thickness constraints and thus does not constrain an upper limit, indicates a relatively modest contribution to sea level rise since the LGM of < 4.6 m, and possibly as little as < 1.5 m.

scholarly journals Cosmogenic nuclide ages for Last Glacial Maximum moraine at Schnells Ridge, Southwest Tasmania

2004 ◽  
Vol 61 (3) ◽  
pp. 335-338 ◽  
Author(s):  
Kevin Kiernan ◽  
L. Keith Fifield ◽  
John Chappell
Keyword(s):  
Last Glacial Maximum ◽  
Glacial Maximum ◽  
Last Glacial ◽  
Cosmogenic Nuclide ◽  
Southeast Australia ◽  
Exposure Ages

Moraines on Schnells Ridge, southwest Tasmania, have been dated using in situ 10Be. An age of 19,400 ± 600 yr is indicated for the well-preserved innermost moraine from consistent measurements on four large quartzite boulders. This corresponds closely with exposure ages reported by T.T. Barrows et al. (2002, Quaternary Science Reviews 21, 159–173) for Last Glacial Maximum glacial features farther north in Tasmania and southeast Australia. In contrast, ages between 39,000 and 141,000 yr were obtained from a series of boulders on a more extensive outer moraine, indicating that this has had a more complex history.

scholarly journals New Last Glacial Maximum Ice Thickness constraints for the Weddell Sea sector, Antarctica

2019 ◽  
Author(s):  
Keir A. Nichols ◽  
Brent M. Goehring ◽  
Greg Balco ◽  
Joanne S. Johnson ◽  
Andrew A. Hein ◽  
...  
Keyword(s):  
Sea Level ◽  
Last Glacial Maximum ◽  
Glacial Maximum ◽  
Weddell Sea ◽  
Ice Thickness ◽  
Last Glacial ◽  
Cosmogenic Nuclide ◽  
Global Sea Level ◽  
Exposure Ages

Abstract. This paper describes new Last Glacial Maximum (LGM) ice thickness constraints for three locations spanning the Weddell Sea Embayment (WSE) of Antarctica. Samples collected from the Shackleton Range, Pensacola Mountains, and the Lassiter Coast constrain the LGM thickness of the Slessor Glacier, Foundation Ice Stream, and grounded ice proximal to the modern Ronne Ice Shelf Edge on the Antarctic Peninsula, respectively. Previous attempts to reconstruct LGM-to-present ice thickness changes around the WSE used measurements of long-lived cosmogenic nuclides, primarily 10Be. An absence of post-LGM apparent exposure ages at many sites led to LGM thickness reconstructions that were spatially highly variable, and inconsistent with flowline modeling. Estimates for the contribution of the ice sheet occupying the WSE at the LGM to global sea level since deglaciation vary by an order of magnitude, from 1.4 to 14.1 m of sea level equivalent. Here we use a cosmogenic nuclide, in situ produced 14C, to evaluate the possibility that sites with no post-LGM exposure ages are biased by cosmogenic nuclide inheritance due to surface preservation by cold-based ice and nondeposition of LGM-aged drift. Our measurements show that the Slessor Glacier was between 310 and 650 m thicker than present at the LGM. The Foundation Ice Stream was at least 800 m thicker, and ice on the Lassiter Coast was at least 385 m thicker than present at the LGM. With evidence for LGM thickening at all of our study sites, our in situ 14C measurements indicate that the long-lived nuclide measurements of previous studies were influenced by cosmogenic nuclide inheritance. Our LGM thickness constraints point toward a modest contribution from the Weddell Sea Embayment to global sea-level since deglaciation, with an estimated range of 2.2 to 5.8 m.

Cosmogenic nuclide constraints on late Quaternary glacial chronology on the Dalijia Shan, northeastern Tibetan Plateau

2013 ◽  
Vol 79 (3) ◽  
pp. 439-451 ◽  
Author(s):  
Jie Wang ◽  
Christine Kassab ◽  
Jonathan M. Harbor ◽  
Marc W. Caffee ◽  
Hang Cui ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Last Glacial Maximum ◽  
Younger Dryas ◽  
Glacial Maximum ◽  
The Tibetan Plateau ◽  
Last Glacial ◽  
Cosmogenic Nuclide ◽  
Mis 3 ◽  
Northeastern Tibetan Plateau ◽  
Exposure Ages

AbstractCosmogenic nuclide (CN) apparent exposure dating has become a widely used method for determining the age of glacial landforms on the Tibetan Plateau with > 1200 published ages. We present the first 10Be exposure ages from the Dalijia Shan, the most northeastern formerly glaciated mountain range on the Tibetan Plateau. The moraine groups identified from field and remote sensing imagery mapping record four glacial events at 37.07 ± 3.70 to 52.96 ± 4.70 ka (MIS 3), 20.17 ± 1.79 to 26.99 ± 2.47 ka (MIS 2), 16.92 ± 1.49 to 18.76 ± 1.88 ka (MIS 2), and 11.56 ± 1.03 to 11.89 ± 1.06 ka (Younger Dryas). These ages indicate that glaciation in the northeastern Tibetan Plateau is much younger than previously thought. In addition, this record is consistent with many other regions on the Tibetan Plateau, with a local last glacial maximum during MIS 3 asynchronous with Northern Hemisphere last glacial maximum during MIS 2. The Dalijia Shan might also include an event of Younger Dryas age, but this needs to be tested in future studies.

The Local Last Glacial Maximum of the southern Scandinavian Ice Sheet front: Cosmogenic nuclide dating of erratics in northern Poland

2019 ◽  
Vol 219 ◽  
pp. 36-46 ◽  
Author(s):  
Karol Tylmann ◽  
Vincent R. Rinterknecht ◽  
Piotr P. Woźniak ◽  
Didier Bourlès ◽  
Irene Schimmelpfennig ◽  
...  
Keyword(s):  
Last Glacial Maximum ◽  
Ice Sheet ◽  
Glacial Maximum ◽  
Last Glacial ◽  
Cosmogenic Nuclide ◽  
Northern Poland ◽  
Scandinavian Ice Sheet ◽  
Cosmogenic Nuclide Dating

Reconstructions of the past distribution of Testudo graeca mitochondrial lineages in the Middle East and Transcaucasia support multiple refugia since the Last Glacial Maximum

2021 ◽  
pp. 10-17
Author(s):  
Oguz Turkozan
Keyword(s):  
Middle East ◽  
Last Glacial Maximum ◽  
Glacial Maximum ◽  
Testudo Graeca ◽  
Last Glacial ◽  
The Past ◽  
Precipitation Seasonality ◽  
Multiple Refugia ◽  
The Last Glacial Maximum ◽  
The Last Glacial

A cycle of glacial and interglacial periods in the Quaternary caused species’ ranges to expand and contract in response to climatic and environmental changes. During interglacial periods, many species expanded their distribution ranges from refugia into higher elevations and latitudes. In the present work, we projected the responses of the five lineages of Testudo graeca in the Middle East and Transcaucasia as the climate shifted from the Last Glacial Maximum (LGM, Mid – Holocene), to the present. Under the past LGM and Mid-Holocene bioclimatic conditions, models predicted relatively more suitable habitats for some of the lineages. The most significant bioclimatic variables in predicting the present and past potential distribution of clades are the precipitation of the warmest quarter for T. g. armeniaca (95.8 %), precipitation seasonality for T. g. buxtoni (85.0 %), minimum temperature of the coldest month for T. g. ibera (75.4 %), precipitation of the coldest quarter for T. g. terrestris (34.1 %), and the mean temperature of the driest quarter for T. g. zarudyni (88.8 %). Since the LGM, we hypothesise that the ranges of lineages have either expanded (T. g. ibera), contracted (T. g. zarudnyi) or remained stable (T. g. terrestris), and for other two taxa (T. g. armeniaca and T. g. buxtoni) the pattern remains unclear. Our analysis predicts multiple refugia for Testudo during the LGM and supports previous hypotheses about high lineage richness in Anatolia resulting from secondary contact.

Sign in / Sign up

Export Citation Format

Share Document