Holocene climatic and environmental change on the western Tibetan Plateau revealed by glycerol dialkyl glycerol tetraethers and leaf wax deuterium-to-hydrogen ratios at Aweng Co

2017 ◽  
Vol 87 (3) ◽  
pp. 455-467 ◽  
Author(s):  
Xiumei Li ◽  
Mingda Wang ◽  
Yuzhi Zhang ◽  
Li Lei ◽  
Juzhi Hou
Keyword(s):  
Tibetan Plateau ◽  
Hydrogen Isotope ◽  
Late Holocene ◽  
Indian Monsoon ◽  
The Holocene ◽  
Middle Holocene ◽  
Leaf Wax ◽  
Western Tibetan Plateau ◽  
Hydrogen Isotope Ratios ◽  
Winter Insolation

AbstractMean annual air temperature (MAAT) and precipitation isotope records for the Holocene were obtained from the analysis of the relative distribution of branched glycerol dialkyl glycerol tetraethers and compound-specific hydrogen isotope ratios of leaf waxes from a sediment core from Aweng Co on the western Tibetan Plateau (WTP). Our results indicate that the Indian monsoon mainly influenced Aweng Co during the Holocene. During the early Holocene, when summer insolation was at a maximum, the monsoonal influence was strong and the climate was warm and wet. Both the summer and winter insolation were relatively weak, and Aweng Co was cool and dry during the middle Holocene (6–3 ka), indicating a weakening of the Indian monsoon. The southward displacement of the Intertropical Convergence Zone and relatively low atmospheric methane content may have contributed to the middle Holocene cooling on the WTP. During the late Holocene, with a further increase in winter insolation and decrease in summer insolation, the summer monsoon weakened and the MAAT on the WTP gradually increased. Depleted leaf wax hydrogen isotope ratios during the late Holocene can be attributed to accelerated glacier melting because of the elevated MAAT.

scholarly journals Three distinct Holocene intervals of stalagmite deposition and nondeposition revealed in NW Madagascar, and their paleoclimate implications

2017 ◽  
Vol 13 (12) ◽  
pp. 1771-1790 ◽  
Author(s):  
Ny Riavo Gilbertinie Voarintsoa ◽  
Loren Bruce Railsback ◽  
George Albert Brook ◽  
Lixin Wang ◽  
Gayatri Kathayat ◽  
...  
Keyword(s):  
Stable Isotopes ◽  
High Resolution ◽  
Late Holocene ◽  
Intertropical Convergence Zone ◽  
Convergence Zone ◽  
High Resolution Data ◽  
The Holocene ◽  
Middle Holocene ◽  
Resolution Data

Abstract. Petrographic features, mineralogy, and stable isotopes from two stalagmites, ANJB-2 and MAJ-5, respectively from Anjohibe and Anjokipoty caves, allow distinction of three intervals of the Holocene in NW Madagascar. The Malagasy early Holocene (between ca. 9.8 and 7.8 ka) and late Holocene (after ca. 1.6 ka) intervals (MEHI and MLHI, respectively) record evidence of stalagmite deposition. The Malagasy middle Holocene interval (MMHI, between ca. 7.8 and 1.6 ka) is marked by a depositional hiatus of ca. 6500 years. Deposition of these stalagmites indicates that the two caves were sufficiently supplied with water to allow stalagmite formation. This suggests that the MEHI and MLHI intervals may have been comparatively wet in NW Madagascar. In contrast, the long-term depositional hiatus during the MMHI implies it was relatively drier than the MEHI and the MLHI. The alternating wet–dry–wet conditions during the Holocene may have been linked to the long-term migrations of the Intertropical Convergence Zone (ITCZ). When the ITCZ's mean position is farther south, NW Madagascar experiences wetter conditions, such as during the MEHI and MLHI, and when it moves north, NW Madagascar climate becomes drier, such as during the MMHI. A similar wet–dry–wet succession during the Holocene has been reported in neighboring locations, such as southeastern Africa. Beyond these three subdivisions, the records also suggest wet conditions around the cold 8.2 ka event, suggesting a causal relationship. However, additional Southern Hemisphere high-resolution data will be needed to confirm this.

scholarly journals The Holocene dynamics of Ryder Glacier and ice tongue in north Greenland

2021 ◽  
Vol 15 (8) ◽  
pp. 4073-4097
Author(s):  
Matt O'Regan ◽  
Thomas M. Cronin ◽  
Brendan Reilly ◽  
Aage Kristian Olsen Alstrup ◽  
Laura Gemery ◽  
...  
Keyword(s):  
Climate Change ◽  
Late Holocene ◽  
Sediment Cores ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Sedimentary Facies ◽  
Climate Forcing ◽  
The Holocene ◽  
Middle Holocene ◽  
Vulnerability To Climate Change

Abstract. The northern sector of the Greenland Ice Sheet is considered to be particularly susceptible to ice mass loss arising from increased glacier discharge in the coming decades. However, the past extent and dynamics of outlet glaciers in this region, and hence their vulnerability to climate change, are poorly documented. In the summer of 2019, the Swedish icebreaker Oden entered the previously unchartered waters of Sherard Osborn Fjord, where Ryder Glacier drains approximately 2 % of Greenland's ice sheet into the Lincoln Sea. Here we reconstruct the Holocene dynamics of Ryder Glacier and its ice tongue by combining radiocarbon dating with sedimentary facies analyses along a 45 km transect of marine sediment cores collected between the modern ice tongue margin and the mouth of the fjord. The results illustrate that Ryder Glacier retreated from a grounded position at the fjord mouth during the Early Holocene (> 10.7±0.4 ka cal BP) and receded more than 120 km to the end of Sherard Osborn Fjord by the Middle Holocene (6.3±0.3 ka cal BP), likely becoming completely land-based. A re-advance of Ryder Glacier occurred in the Late Holocene, becoming marine-based around 3.9±0.4 ka cal BP. An ice tongue, similar in extent to its current position was established in the Late Holocene (between 3.6±0.4 and 2.9±0.4 ka cal BP) and extended to its maximum historical position near the fjord mouth around 0.9±0.3 ka cal BP. Laminated, clast-poor sediments were deposited during the entire retreat and regrowth phases, suggesting the persistence of an ice tongue that only collapsed when the glacier retreated behind a prominent topographic high at the landward end of the fjord. Sherard Osborn Fjord narrows inland, is constrained by steep-sided cliffs, contains a number of bathymetric pinning points that also shield the modern ice tongue and grounding zone from warm Atlantic waters, and has a shallowing inland sub-ice topography. These features are conducive to glacier stability and can explain the persistence of Ryder's ice tongue while the glacier remained marine-based. However, the physiography of the fjord did not halt the dramatic retreat of Ryder Glacier under the relatively mild changes in climate forcing during the Holocene. Presently, Ryder Glacier is grounded more than 40 km seaward of its inferred position during the Middle Holocene, highlighting the potential for substantial retreat in response to ongoing climate change.

Stable source of Holocene spring precipitation recorded in leaf wax hydrogen-isotope ratios from two New York lakes

2020 ◽  
Vol 240 ◽  
pp. 106357 ◽  
Author(s):  
Anna K. Schartman ◽  
Aaron F. Diefendorf ◽  
Thomas V. Lowell ◽  
Erika J. Freimuth ◽  
Alexander K. Stewart ◽  
...  
Keyword(s):  
New York ◽  
Hydrogen Isotope ◽  
Isotope Ratios ◽  
Spring Precipitation ◽  
Leaf Wax ◽  
Hydrogen Isotope Ratios ◽  
Stable Source

Baltic Sea Alkenones: Novel Insights into Distribution Changes and Hydrogen Isotope Ratios During the Holocene

2019 ◽  
Author(s):  
G. Weiss ◽  
B. Massalska ◽  
R. Hennekam ◽  
G-J. Reichart ◽  
J.S. Sinninghe Damsté ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Hydrogen Isotope ◽  
Isotope Ratios ◽  
The Holocene ◽  
Hydrogen Isotope Ratios

scholarly journals Sedimentary archives of climate and sea-level changes during the Holocene in the Rhône prodelta (NW Mediterranean Sea)

2016 ◽  
Vol 12 (12) ◽  
pp. 2161-2179 ◽  
Author(s):  
Anne-Sophie Fanget ◽  
Maria-Angela Bassetti ◽  
Christophe Fontanier ◽  
Alina Tudryn ◽  
Serge Berné
Keyword(s):  
Sea Level ◽  
Water Depth ◽  
Late Holocene ◽  
Sea Level Changes ◽  
The Holocene ◽  
Middle Holocene ◽  
The Core ◽  
Condensed Section ◽  
Core Site ◽  
Nw Mediterranean

Abstract. A 7.38 m long sediment core was collected from the eastern section of the Rhône prodelta (NW Mediterranean) at 67 m water depth. A multi-proxy study (including sedimentary facies, benthic foraminifera, ostracods, and clay mineralogy) provides a multi-decadal to century-scale record of climate and sea-level changes during the Holocene. The early Holocene is marked by alternative silt and clay layers interpreted as distal tempestites deposited in a context of rising sea level. This interval contains shallow infra-littoral benthic meiofauna (e.g., Pontocythere elongata, Elphidium spp., Quinqueloculina lata) and formed between ca. 20 and 50 m water depth. The middle Holocene (ca. 8.3 to 4.5 ka cal. BP) is characterized, at the core site, by a period of sediment starvation (accumulation rate of ca. 0.01 cm yr−1) resulting from the maximum landward shift of the shoreline and the Rhône outlet(s). From a sequence stratigraphic point of view, this condensed section, about 35 cm thick, can be identified on seismic profiles as a maximum flooding surface that marks the transition between delta retrogradation and delta progradation. The transition between the early Holocene deposits and the middle Holocene condensed section is marked by a gradual change in all proxy records. Following the stabilization of sea level at a global scale, the late Holocene is marked by the establishment of prodeltaic conditions at the core site, as shown by the lithofacies and by the presence of benthic meiofauna typical of the modern Rhône prodelta (e.g., Valvulineria bradyana, Cassidulina carinata, Bulimina marginata). Several periods of increased fluvial discharge are also emphasized by the presence of species commonly found in brackish and shallow-water environments (e.g., Leptocythere spp.). Some of these periods correspond to the multi-decadal to centennial late Holocene humid periods recognized in Europe (i.e., the 2.8 ka event and the Little Ice Age). Two other periods of increased runoffs at ca. 1.3 and 1.1 ka cal. BP are recognized, which are likely to reflect periods of regional climate deterioration that are observed in the Rhône watershed. Conversely, the Migration Period Cooling (ca. 1.4 ka cal. BP) and the Medieval Climate Anomaly (ca. AD 950–1250) correspond locally to periods of increased dryness.

Diachronic variability in prehistoric land use in Oregon’s Warner Valley

2016 ◽  
Vol 38 (2) ◽  
pp. 183-206 ◽  
Author(s):  
Geoffrey M Smith ◽  
Donald D Pattee ◽  
Madeline Ware van der Voort
Keyword(s):  
Land Use ◽  
Recent Work ◽  
Late Holocene ◽  
The Holocene ◽  
Middle Holocene ◽  
Pedestrian Survey ◽  
Warner Valley

Pedestrian survey in northern Warner Valley, Oregon, has provided data capable of contributing to reconstructions of prehistoric land use. Such information is complementary to data generated by recent work at the stratified LSP-1 rockshelter situated in the Northern Warner Valley Study Area (NWVSA). Here, we present results of our survey and focus on when the area was visited, how it was used, and from where visitors to the area originated and/or obtained toolstone. Our results indicate that the NWVSA saw heavy use by Paleoindians before being largely abandoned during the Middle Holocene. During the Late Holocene, groups likely operating from residential bases further south in the better-watered parts of Warner Valley returned to the NWVSA. Compared to other nearby areas, the NWVSA was utilized less intensively during much of the Holocene.

The Holocene Indian monsoon variability over the southern Tibetan Plateau and its teleconnections

2012 ◽  
Vol 335-336 ◽  
pp. 135-144 ◽  
Author(s):  
Yanjun Cai ◽  
Haiwei Zhang ◽  
Hai Cheng ◽  
Zhisheng An ◽  
R. Lawrence Edwards ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Indian Monsoon ◽  
The Holocene ◽  
Monsoon Variability ◽  
Southern Tibetan Plateau
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