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Detrital carbonate influences on bulk oxygen and carbon isotope composition of lacustrine sediments from the Mediterranean

journal contribution
posted on 2023-06-07, 16:50 authored by Melanie J Leng, Matthew D Jones, Mick FrogleyMick Frogley, Warren J Eastwood, Chris P Kendrick, C Neil Roberts
Detrital carbonate contamination is one of the principal problems with the integrity of stable isotope data from authigenic lake carbonates. Here we investigate the origin and climatic implications of stable isotope data from carbonate minerals deposited in two Mediterranean lakes: Golhisar Gl (SW Turkey) and Lake Pamvotis (NW Greece). In Golhisar Gl the bulk carbonate oxygen and carbon isotope composition has previously been interpreted in terms of significant climate variation related to the lake's hydrological balance. However, the origin of the carbonates was not investigated even though phases of high magnetic susceptibility suggest that there were several periods of increased soil erosion from the karstic catchment which could bring detrital limestone in to the lake. SEM evidence suggests that the carbonates in Golhisar Gl sediments of Holocene age are predominantly derived from forms of authigenic calcite (i.e. platelets, prismatic crystals), although periods of inwash clearly occurred which may have influenced parts of the isotope stratigraphy during the last two millennia. For comparison we also looked at data of Late Pleistocene to Holocene age from Lake Pamvotis. Here, there is an excellent correlation between the bulk carbonate oxygen isotope and magnetic susceptibility data, but no significant correlation between the bulk carbonate isotope data and ostracod isotope data from the same levels. SEM analyses confirmed the presence of detrital carbonates and the lack of significant authigenic carbonate. While the Glhisar record records aspects of climate in most of its isotope data, in the Pamvotis record only the ostracod data are likely to contain meaningful information.

History

Publication status

  • Published

Journal

Global and Planetary Change

ISSN

0921-8181

Issue

3-4

Volume

71

Page range

175-182

Pages

8.0

Department affiliated with

  • Geography Publications

Full text available

  • No

Peer reviewed?

  • Yes

Legacy Posted Date

2012-02-06

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