ausblenden:
Schlagwörter:
climate; human land use change; varved lake sediments; XRF core scanning
Zusammenfassung:
Lake sediments are ideal archives to evaluate the interactions between climatically driven environmental responses and human activity on seasonal to multi-decadal timescales. This study focuses on the unique sediments of Diss Mere, the only lake in England providing an annually laminated (varved) record for most of the Holocene. We combine microfacies analysis with X-ray core scanning data to explore the influence of natural and human-led changes on sediment deposition over the past 10 200 years and evaluate the sensitivity of the lake sediments to climate variability through time. Variability of titanium (Ti), calcium (Ca) and silica (Si) explain most of the lithological changes observed in the sediment and we identify three stages with low (10 290–2070 cal a bp), intermediate (2070–1040 cal a bp) and intensified (1040 cal a bp – present) human influence. During the first stage, where varved sediments are preserved, Ti is low due to the minimal detrital input into the lake. Ca and Si during this stage reveal high-amplitude variability responding to seasonal changes in sediment deposition. The termination of varved sediment preservation and increases in sedimentation rates coincide with a major rise in Ti after this first stage, marking the intensification of human activity around the lake. Ca is used here as an indicator of temperature-included calcite precipitation, and the long-term variability of the Ca profile resembles Holocene temperature evolution. This continues during periods of intensified human activity, suggesting that the Diss Mere sediments remain sensitive to climate through time.
