Multiple varve chronologies for the last 2000 years from the sediments of Lake Żabińskie (northeastern Poland) - comparison of strategies for varve counting and uncertainty estimations
PBN-AR
Instytucja
Wydział Oceanografii i Geografii (Uniwersytet Gdański)
Informacje podstawowe
Główny język publikacji
en
Czasopismo
Quaternary Geochronology (40pkt w roku publikacji)
ISSN
1871-1014
EISSN
Wydawca
DOI
URL
Rok publikacji
2018
Numer zeszytu
Strony od-do
107-119
Numer tomu
47
Identyfikator DOI
Liczba arkuszy
0.6
Autorzy
(liczba autorów: 3)
Pozostali autorzy
+ 1
Słowa kluczowe
en
lake sediments
varves
sediment chronology
age-depth model
varve counting
Streszczenia
Język
en
Treść
This study compares different methods to count biogenic varves in Lake Żabińskie in northeastern Poland. To perform this comparison, we used 2000 years-long varved sediment record from this lake because of the well-preserved laminations as well as the independent age controls, i.e. 29 AMS14C dates, 137Cs activity peaks and volcanic glass shards (1875 AD Askja cryptotephra). Microscopic investigations of thin sections allowed us to identify six major varve microfacies along the sediment profile. Using these microfacies, we tested three counting methods and different approaches of counting uncertainty estimation. These methods provided comparable numbers of varves (1943 ± 30, 2034 ± 34, 2028 +34/-53) and similar shapes in the age-depth relations. However, in two methods, we found possible disadvantages in arbitrary assumptions and subjective decisions in the process of chronology building, procedures leading to age underestimation as well as problems with reliable and objective estimations of counting uncertainty. Based on these results, we propose the counting method which include analyses of major varve microfacies and three independent countings without the need for varve-by-varve microscopic investigations. This method provided acceptable results (<5% uncertainty) and was more objective and less time-consuming. Semi-automatic counting using μXRF Ca record in the sediments was also tested and provided results that can serve as a first approximation of the number of varves. Our study also indicates that different counting strategies may lead to different uncertainty estimations, which may be important in the reliable interpretation of proxy data.
Inne
System-identifier
UOG82295f8d76c44c629c965293420ad8bc
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