scholarly journals Ages of Charcoal Samples of Geomorphologic Interest in Northeast Hungary

Radiocarbon ◽  
1980 ◽  
Vol 22 (3) ◽  
pp. 774-777 ◽  
Author(s):  
Eva Csongor ◽  
Zoltán Borsy ◽  
Ilona Szabô

There are extended wind-blown sand territories in the northeastern part of the Great Hungarian Plain. Wind-blown sand migration periods were distineuished by means of radiocarbon age determination of charcoal samples found in the same type of a thin soil layer of chernozem character in different sand dune exposures. The ages of the samples were determined by proportional counter, and are around 12 000 years BP. This thin fossil soil layer, which is regionally spread in the northeast Hungarian wind-blown sand areas, presents a chronological mark between the blown sand forms evolved in the last glacial period and in the Holocene.

2020 ◽  
Vol 532 ◽  
pp. 116012 ◽  
Author(s):  
Jessica B. Volz ◽  
Bo Liu ◽  
Male Köster ◽  
Susann Henkel ◽  
Andrea Koschinsky ◽  
...  

2017 ◽  
Vol 13 (4) ◽  
pp. 345-358 ◽  
Author(s):  
Marília C. Campos ◽  
Cristiano M. Chiessi ◽  
Ines Voigt ◽  
Alberto R. Piola ◽  
Henning Kuhnert ◽  
...  

Abstract. Abrupt millennial-scale climate change events of the last deglaciation (i.e. Heinrich Stadial 1 and the Younger Dryas) were accompanied by marked increases in atmospheric CO2 (CO2atm) and decreases in its stable carbon isotopic ratios (δ13C), i.e. δ13CO2atm, presumably due to outgassing from the ocean. However, information on the preceding Heinrich Stadials during the last glacial period is scarce. Here we present δ13C records from two species of planktonic foraminifera from the western South Atlantic that reveal major decreases (up to 1 ‰) during Heinrich Stadials 3 and 2. These δ13C decreases are most likely related to millennial-scale periods of weakening of the Atlantic meridional overturning circulation and the consequent increase (decrease) in CO2atm (δ13CO2atm). We hypothesise two mechanisms that could account for the decreases observed in our records, namely strengthening of Southern Ocean deep-water ventilation and weakening of the biological pump. Additionally, we suggest that air–sea gas exchange could have contributed to the observed δ13C decreases. Together with other lines of evidence, our data are consistent with the hypothesis that the CO2 added to the atmosphere during abrupt millennial-scale climate change events of the last glacial period also originated in the ocean and reached the atmosphere by outgassing. The temporal evolution of δ13C during Heinrich Stadials 3 and 2 in our records is characterized by two relative minima separated by a relative maximum. This w structure is also found in North Atlantic and South American records, further suggesting that such a structure is a pervasive feature of Heinrich Stadial 2 and, possibly, also Heinrich Stadial 3.


2013 ◽  
Vol 160 (5) ◽  
pp. 1285-1296 ◽  
Author(s):  
D. W. Foltz ◽  
S. D. Fatland ◽  
M. Eléaume ◽  
K. Markello ◽  
K. L. Howell ◽  
...  

2021 ◽  
Author(s):  
Mohamed M. Ezat ◽  
Tine L. Rasmussen ◽  
Mathis P. Hain ◽  
Mervyn Greaves ◽  
James W B Rae ◽  
...  

1992 ◽  
Vol 70 (11) ◽  
pp. 2247-2259 ◽  
Author(s):  
Nicholas E. Mandrak ◽  
E. J. Crossman

The present-day distributions of 117 native freshwater fishes in Ontario have been shaped by processes active following the Wisconsinan glacial period, 80 000–10 000 years before present. During this glacial period, these species survived in unglaciated réfugia. To understand the processes that resulted in the recolonization of Ontario by fishes following the last glacial period, the refugial areas occupied by each species were determined using a refugial index, and glacial water bodies used as dispersal routes were identified. The refugial origins of the Ontario populations of 91 species were resolved. Seventy-two species resided in the Mississippian refugium, 13 species in the Atlantic Coastal refugium, 4 species in dual Atlantic Coastal – Mississippian refugia, 1 species in a Missourian refugium, and 1 species in Atlantic Coastal, Mississippian, and Missourian refugia. These conclusions differed significantly from those of other studies. Five general patterns were identified from the distributions of 104 species. In addition, there are 13 species that do not fit any of the general patterns. Most species with similar distributions in Ontario shared the same refugia and dispersal routes in eastern North America, therefore it is hypothesized that historical processes were important in shaping the present-day distributions of Ontario freshwater fishes.


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