scholarly journals Changes in detrital sediment supply to the central Yellow Sea since the Last Glacial Maximum

2020 ◽  
Author(s):  
Hyo Jin Koo ◽  
Hyen Goo Cho
Keyword(s):  
Last Glacial Maximum ◽  
Yellow Sea ◽  
Clay Mineralogy ◽  
Glacial Maximum ◽  
Sediment Supply ◽  
Last Glacial ◽  
Sea Mud ◽  
Detrital Sediment ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Abstract. The sediment supply to the central Yellow Sea since the Last Glacial Maximum was uncovered through clay mineralogy and geochemical analysis of core 11YS-PCL14 in the Central Yellow Sea mud (CYSM). The core can be divided into four units: Unit 4 (700–520 cm; 15.5–14.8 ka), Unit 3 (520–280 cm; 14.8–12.1 ka), Unit 2 (280–130 cm; 12.1–8.8 ka), and Unit 1 (130–0 cm;

Freshwater control of ice-rafted debris in the last glacial period at Mono Lake, California, USA

2011 ◽  
Vol 76 (2) ◽  
pp. 264-271 ◽  
Author(s):  
Susan R. H. Zimmerman ◽  
Crystal Pearl ◽  
Sidney R. Hemming ◽  
Kathryn Tamulonis ◽  
N. Gary Hemming ◽  
...  
Keyword(s):  
Last Glacial Maximum ◽  
Warm Season ◽  
Glacial Maximum ◽  
Sediment Supply ◽  
Mono Lake ◽  
Last Glacial ◽  
Type Section ◽  
High Lake Level ◽  
The Last Glacial Maximum ◽  
The Last Glacial

AbstractThe type section silts of the late Pleistocene Wilson Creek Formation at Mono Lake contain outsized clasts, dominantly well-rounded pebbles and cobbles of Sierran lithologies. Lithic grains > 425 μm show a similar pattern of variability as the > 10 mm clasts visible in the type section, with decreasing absolute abundance in southern and eastern outcrops. The largest concentrations of ice-rafted debris (IRD) occur at 67–57 ka and 46–32 ka, with strong millennial-scale variability, while little IRD is found during the last glacial maximum and deglaciation.Stratigraphic evidence for high lake level during high IRD intervals, and a lack of geomorphic evidence for coincidence of lake and glaciers, strongly suggests that rafting was by shore ice rather than icebergs. Correspondence of carbonate flux and IRD implies that both were mainly controlled by freshwater input, rather than disparate non-climatic controls. Conversely, the lack of IRD during the last glacial maximum and deglacial highstands may relate to secondary controls such as perennial ice cover or sediment supply. High IRD at Mono Lake corresponds to low glacial flour flux in Owens Lake, both correlative to high warm-season insolation. High-resolution, extra-basinal correlation of the millennial peaks awaits greatly improved age models for both records.

scholarly journals A late Quaternary paleoenvironmental record in sand dunes of the northern Atacama Desert, Chile

2018 ◽  
Vol 90 (1) ◽  
pp. 127-138 ◽  
Author(s):  
Kari M. Finstad ◽  
Marco Pfeiffer ◽  
Gavin McNicol ◽  
Michael Tuite ◽  
Kenneth Williford ◽  
...  
Keyword(s):  
Last Glacial Maximum ◽  
Late Quaternary ◽  
Sand Dunes ◽  
Atacama Desert ◽  
Glacial Maximum ◽  
Sediment Supply ◽  
Steady Increase ◽  
Last Glacial ◽  
The Last Glacial Maximum ◽  
The Last Glacial

AbstractThis paper reports a previously unidentified paleoenvironmental record found in sand dunes of the Atacama Desert, Chile. Long-term aeolian deflation by prevailing onshore winds has resulted in the deposition of sand on the irregular surface of a Miocene-aged anhydrite outcrop. Two deposits ~25 km apart, along the prevailing wind trajectory, were hand excavated then analyzed for vertical (and temporal) changes in physical and chemical composition. Radiocarbon ages of organic matter embedded within the deposits show that rapid accumulation of sediment began at the last glacial maximum and slowed considerably after the Pacific Ocean attained its present post-glacial level. Over this time period, grain sizes are seen to increase while accumulation rates simultaneously decrease, suggesting greater wind speeds and/or a change or decrease in sediment supply. Changes in δ34S values of sulfate in the sediment beginning ~10 ka indicate an increase in marine sources. Similarly, δ2H values from palmitic acid show a steady increase at ~10 ka, likely resulting from aridification of the region during the Holocene. Due to the extreme aridity in the region, these sand dunes retain a well-preserved chemical record that reflects changes in elevation and coastal proximity after the last glacial maximum.

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.

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