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Title: Lago Grande di Monticchio : a palaeoenvironmental reconstruction from sediment geochemistry
Author: Robinson, Christian
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1993
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During 1990 a 51 metre core was recovered from Lago Grande di Monticchio, a maar lake in S Italy. This provides a high quality laminated sequence extending back into the Late Quaternary which is being examined by a multidisciplinary group. The project here is concerned with sediment geochemistry as a tool for reconstruction of palaeoenvironmental conditions at this locality. The core was analysed at 10cm resolution using techniques such as X-ray fluorescence (XRF). This has produced a highly detailed record of change reflecting either the last 70,000 or 220,000 years. Organic carbon and biogenic silica are believed to represent biogenic productivity and, in particular, nutrient status in the lake system. It is found that the Holocene is marked by very high concentrations of these components in contrast to the minerogenic glacial sediments. Possible earlier interglacials (e.g. the Eemian) contain significantly lower contents of biogenic matter, suggesting that nutrient conditions may have been somewhat poorer during these times. Alternatively, these periods could represent interstadials within the last glacial cycle. C/N ratios and Hydrogen Index values probably reflect both the source and degree of preservation of the organic matter, but should be interpreted cautiously. The δ13C record for bulk organic matter shows a significant shift to isotopically lighter values during the glacial-Holocene transition, but the profile is difficult to interpret due to the many possible factors involved. Indicators of terrigenous clastic material show that the late-glacial and Holocene sediments have received relatively base-rich clastic material probably derived from contemporary tephra inputs to the catchment. This is marked by ratios such as Na/Al and K/Al which increase in apparent association with increased tephra deposition and Zr/Rb which decreases. The effect of tephra blanketing of the catchment and subsequent release of nutrients is proposed as a cause for the much higher productivity during the Holocene interglacial.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available