The incidence of microscopic charcoal in late glacial deposits

2000 ◽  
Vol 164 (1-4) ◽  
pp. 247-262 ◽  
Author(s):  
Kevin J. Edwards ◽  
Graeme Whittington ◽  
Richard Tipping
Keyword(s):  
Late Glacial ◽  
Glacial Deposits ◽  
Microscopic Charcoal

scholarly journals Greenhouse gas production in degrading ice-rich permafrost deposits in northeast Siberia

2018 ◽  
Author(s):  
Josefine Walz ◽  
Christian Knoblauch ◽  
Ronja Tigges ◽  
Thomas Opel ◽  
Lutz Schirrmeister ◽  
...  
Keyword(s):  
Greenhouse Gases ◽  
Greenhouse Gas ◽  
Late Glacial ◽  
Gas Production ◽  
Depositional Environments ◽  
Co2 Production ◽  
Glacial Deposits ◽  
Ch4 Production ◽  
Carbon Dioxide Co2

Abstract. Permafrost deposits have been a sink for atmospheric carbon for millennia. Thaw-erosional processes, however, can lead to rapid degradation of ice-rich permafrost and the release of substantial amounts of organic carbon (OC). The amount of the OC stored in these deposits and their potential to be microbially decomposed to the greenhouse gases carbon dioxide (CO2) and methane (CH4) depends on climatic and environmental conditions during deposition and the decomposition history before incorporation into the permafrost. Here, we examine potential greenhouse gas production in degrading ice-rich permafrost deposits from three locations in the northeast Siberian Laptev Sea region. The deposits span a period of about 55 kyr and include deposits from the last glacial and Holocene interglacial periods. Samples from all three locations were aerobically and anaerobically incubated for 134 days at 4 °C. Greenhouse gas production was generally higher in glacial than Holocene deposits. In permafrost deposits from the Holocene and the late glacial transition, only 0.1–4.0 % of the initially available OC could be decomposed to CO2, while 0.2–6.1 % could be decomposed in glacial deposits. Within the glacial deposits from the Kargin interstadial period (Marine Isotope Stage 3), local depositional environments, especially soil moisture, also affected the preservation of OC. Sediments deposited under wet conditions contained more labile OC and thus produced more greenhouse gases than sediments deposited under drier conditions. To assess the long-term production potentials, deposits from two locations were incubated for a total of 785 days. However, more than 50 % of the aerobically produced and more than 80 % of anaerobically produced CO2 after 785 days of incubation were already produced within the first 134 days, highlighting the quantitative importance of the slowly decomposing OC pool in permafrost. CH4 production was generally observed in active layer samples but only sporadically in permafrost samples and was several orders of magnitude smaller than CO2 production.

scholarly journals Cover of last glaciation deposits at the Eastern Barents Sea: originality of composition, thicknesses distribution, grandiosity and singularity of structure forms

2019 ◽  
Vol 487 (5) ◽  
pp. 547-550
Author(s):  
O. G. Epshtein ◽  
A. G. Dlugach ◽  
A. V. Starovoytov
Keyword(s):  
Barents Sea ◽  
Late Glacial ◽  
The Other ◽  
Specific Character ◽  
Glacial Deposits ◽  
Last Glaciation ◽  
Giant Form

Analysis of the data of seismoacoustic investigation and geotechnical drilling in the Eastern Barents Sea has shown the following. The Upper Weichselian glacial deposits cover spread regionally. It represents seismostratigraphic complex (SSC) SSC III, unconformity occurs on the Mezozoic deposits, partly - on the Lower Weichselian moraine (SSC V) and is overlain unconformity by the Late Glacial glaciomarine (SSC II) - Holocene marine (SSC I) sediments. SSC III consists of two seismofacies (SF). Predominant SSF III-C are formed by the ordinary moraine almost solely, and SF III-T - by the M-moraine. The presence of these moraines determines SSC III thicknesses distribution nearly completely. The ordinary moraine thickness fluctuates from < 10 m to 10-25 m. The M-moraine forms huge in plan, positive accumulation bodies in which its thickness > 25 m and arrives at 50-75 m. The Upper Weichselian deposit cover has also the other grandiosity structure-morphological elements: end moraines (the giant form was discovered) and powerful subglacial cuts, which represent unique unburied analog of the known so-called tunnel valleys. Structure, composition, thicknesses particularities of SSC III deposits cover are determinated by specific character of the development of the Last Glaciation in the region.

RAGWEEDS, AMBROSIA SPECIES, IN CANADA AND THEIR HISTORY IN POSTGLACIAL TIME

1962 ◽  
Vol 40 (1) ◽  
pp. 141-150 ◽  
Author(s):  
I. J. Bassett ◽  
J. Terasmae
Keyword(s):  
Size Range ◽  
Late Glacial ◽  
Ambrosia Artemisiifolia ◽  
Ragweed Pollen ◽  
Western Canada ◽  
Eastern Canada ◽  
Glacial Deposits ◽  
Ambrosia Pollen ◽  
Surface Samples ◽  
Fossil Assemblages

Specific differences of Ambrosia artemisiifolia, A. trifida, and A. coronopifolia are described and their present Canadian distributions are reported in detail. Ambrosia pollens, identified in fossil assemblages as either A. artemisiifolia or A. trifida with a few in the size range of A. coronopifolia, were somewhat more abundant in late-glacial deposits than in younger postglacial sediments except the subrecent ones. It is only within the last 200 years that ragweeds have again become abundant in eastern Canada. The migration and spread of the three ragweed species in eastern and western Canada through postglacial time are discussed. There is evidence through pollen profiles that Ambrosia species existed further northward in Ontario than they do at the present time. In studying the presence and abundance of Ambrosia pollen in surface samples, the authors showed that ragweed pollen can be transported through the atmosphere at least 375 miles from any known source.

Postglacial tilting of Akpatok Island, Northwest Territories

1978 ◽  
Vol 15 (10) ◽  
pp. 1547-1553 ◽  
Author(s):  
Olav H. Løken
Keyword(s):  
Northwest Territories ◽  
Late Glacial ◽  
Sea Surface ◽  
Glacial Deposits ◽  
Glacial Chronology

Late glacial deposits on Akpatok Island are described. They include a major moraine system and numerous raised shore features. A survey of the marine limit at several locations shows that subsequent to its formation the island has been tilted up towards the southwest. The isobases trend 313° true and the former sea surface rises to the southwest at a rate of 0.62 m/km. The late glacial chronology is vague due to the absence of C-14 dates with clear chronological significance. The moraine system is tentatively correlated to the Kangalaksiorvik Phase of northernmost Labrador.

Late-glacial marine overlap in western Newfoundland

1969 ◽  
Vol 6 (6) ◽  
pp. 1397-1404 ◽  
Author(s):  
Ian A. Brookes
Keyword(s):  
Late Glacial ◽  
Quaternary Deposits ◽  
Glacial Deposits

In western Newfoundland Quaternary deposits comprise a glacio-marine sequence sandwiched between tills and associated glacial deposits derived from glaciers that moved westwards from highland centers of outflow. The upper marine limit, at 30.5 m – 50 m in the area, was registered when ice of the earlier of the two glacial episodes represented wasted inland from the present shoreline. The dates herein reported indicate that in St. George's and Port au Port Bays this event was in progress 13 200 – 13 700 years ago, and that in fjord sites in the Bay of Islands it was delayed by about 1000 years. The diachronous nature of marine overlap in the area complicates the reconstruction of isobases on raised marine features.

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