The Relations Between Carbon Isotope Composition and Apparent Age of Freshwater Tufaceous Sediments

Abstract

ABSTRACT. This paper presents a synthetic approach to 14C dating of calcareous tufa, based on statistical analysis of correlations betwen lithologic type of tufaceous sediment, carbon isotope composition, and apparent age. Experimental data on several profiles from southern Poland and the United Kingdom reveal either constant or systematically changing values of apparent age. Constant value of apparent age in a profile can be attributed to calcareous muds precipitated from stagnant or low-energy water, and to tufas precipitated from turbulent water (oncoids, stromatolites, moss travertines) which are characterized by lack of significant correlation between 513C and 14C age of tufa carbonate. It was found that the relation between the apparent age of tufaceous sediment and 5'3C value of tufa carbonate depends on lithologic type of tufa. Phenomenological equations describing the dependence of apparent age upon S13C are given, and applied to estimate true ages of tufas from Gliczarow (southern Poland) and Folkestone (United Kingdom).

Experimental Determination of the 14C Initial Activity of Calcareous Deposits

“…3) and 76.1 pMC for Lake Kozjak. Constant b13C and b180 values throughout the profiles (Srdoc et al 1986b) indicate stable environmental conditions during the sedimentation period and hence, the constant Ao value (Pazdur 1988). …”

“…In an early study of groundwater dating, Geyh (1973) ranged values according to the geology of the catchment area. Other studies of the initial activity of calcareous deposits (Thorpe, Otlet & Sweeting 1980;Srdoc et al 1983Srdoc et al ,1986aPazdur 1988;Pazdur, Pazdur & Szulc 1988; Horvatincic et al 1989;Pentecost et al 1990) showed that the Ao depends on geological setting, geochemical processes, vegetation and climate, which are, in principle, site-specific. A temporal change of Ao is not very likely over a period of stable environmental conditions, as demonstrated by our data for Holocene samples.…”

Progress in the holocene chrono-climatostratigraphy of Polish territory

“…(11 samples) and Lublin Upland (63 samples). Tufas were deposited in the stream channels, and also within cupola spring mires characteristic for part of the Lublin Upland (Dobrowolski et al, 1999;Pazdur 1988;Pazdur et al, 2002a and2002b). CaCO 3 precipitated in conditions of relatively higher temperature.…”

Further Investigations on 14C Dating of Calcareous Tufa

“…In earlier studies of tufa profiles from southern Poland (Pazdur, Pazdur & Szulc 1988;Pazdur 1988) we found highly different values of the reservoir correction factor TR of the carbonate fraction of tufa samples, ranging from 900-11,000 yr. Observed values of TR are related to the lithologic type of tufa.…”