Lacustrine and Palustrine Geochemical Sediments

The evolution of Palaeolake Flixton and the environmental context of Star Carr: an oxygen and carbon isotopic record of environmental change for the early Holocene

“…Only at the location of site B does freshwater sedimentation persist in a palustrine ("paludal") environment. (Diefendorf et al, 2006;2008), Haweswater (Marshall et al, 2002;2007), Star Carr (this study), Lundin Tower (Whittington et al, 1996), Lake Tibetanus (Hammarlund et al, 2002). The chronological precision on these records is highly variable.…”

“…A review of the literature indicates that the pattern of δ 18 O values seen at Flixton, is also seen at Loch Inchquin (west coast of Ireland (Diefendorf et al, 2006;2008)), Haweswater (the English Lake District (Marshall et al, 2002;2007)), Lundin Tower (southeast Scotland (Whittington et al, 1996)) and Lake Tibetanus (northern Sweden ((Hammarlund et al, 2002) (Figure 7). It should be highlighted that the chronology of many of these sites is of low resolution, there is, therefore, no implication that the timing of these peaks are synchronous or that the onset of the depletion trend is uniform across the British Isles.…”

“…During periods of minimal allogenic input into the lake basin, carbonate accumulation can dominate lacustrine sedimentation leading to the deposition of relatively thick beds of authigenic carbonate, or marl (Platt and Wright, 1991;Verrechia, 2007). In recent years the analysis of the oxygen and carbon isotopic values of marl sequences has provided important records of abrupt climate change in the British Isles during the Lateglacial and the early Holocene (Marshall et al, 2002;2007;Leng and Marshall, 2004;Leng et al, 2005;van Asch et al, 2012). In such studies it is variations in the δ 18 O value of the marl sediment that provides the most important palaeoclimatic indicator acting, as it does, as a record of changes in the δ 18 O value of meteoric water which is primarily controlled by prevailing air temperature (see Leng and Marshall, 2004;Andrews, 2006;Candy et al, 2011).…”

“…An oxygen and carbon isotopic record from this sequence would, consequently, provide a palaeoenvironmental context to this important archaeological sequence. Secondly, the two key Lateglacial/early Holocene lacustrine isotope records in the British Isles occur on the west coast of Britain (Marshall et al, 2002;2007) and Ireland (van Asch et al, 2012). An early Holocene isotope record from Palaeolake Flixton, located on the eastern side of Britain, would increase the spatial coverage of such records and begin to allow regional variations in isotopic response during this time interval to be understood.…”

Sedimentology, diagenesis and ichnology of Cretaceous and Palaeogene calcretes and palustrine carbonates from Uruguay

“…Although sometimes the massive and homogeneous appearance of these limestones seems to indicate bioturbation in shallow lake areas (Gierlowski-Kordesch, 2010), no evidence of strong bioturbation that might have totally destroyed the original fabric of the sediment is seen. The massive appearance might be due either to an increase in the sedimentation rate (Verrecchia, 2007) (Wright et aL, 1997). The preservation of many of the original morphologies of the bioclasts supports the idea of reduced bioturbation and preservation of most of the initial textural features of the sediments.…”