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| Titel |
The SCOPSCO Deep Drilling Project: a 1.3 million-year palaeoenvironmental reconstruction from Lake Ohrid using stable isotopes |
| VerfasserIn |
Jack Lacey, Melanie Leng, Alexander Francke, Hendrik Vogel, Giovanni Zanchetta, Bernd Wagner |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250146243
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| Publikation (Nr.) |
 EGU/EGU2017-10258.pdf |
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| Zusammenfassung |
| Lake Ohrid is a large, ancient lake situated on the Balkan Peninsula in the central northern
Mediterranean region. The lake hosts a world-class degree of endemic biodiversity and
an extensive sedimentary archive. In 2013, an extremely successful International
Continental scientific Drilling Program deep drilling campaign was conducted as part
of the transdisciplinary Scientific Collaboration on Past Speciation Conditions in
Lake Ohrid (SCOPSCO) project and recovered over 2100 m of sediment from the
lake. The main target site in the central basin provided a 584-m composite record
covering at least 1.3 million years. Here, we present new oxygen and carbon isotope
data (δ18O and δ13C) from carbonate for the entire lacustrine sequence (upper 430
m) of the SCOPSCO cores spanning Marine Isotope Stages (MIS) 41-1, based on
chronological information derived from tephrostratigraphy, palaeomagnetic analyses, and
orbital tuning of biogeochemical proxies. Contemporary monitoring data suggest
variations in δ18O are primarily a function of changes in regional water balance.
This is confirmed through the Holocene where the isotope dataset shows a stable
transition from wetter conditions in the Early Holocene to a drier climate in the Late
Holocene, which is consistent with a regional pattern of aridification. At the onset of
deep-water lacustrine conditions around 1.3 Ma, very low δ18O are comparable to
measured values for surface inflow today and infer that Lake Ohrid had a greatly
reduced residence time and volume. Multiple rapid shifts to higher values in long-term
average δ18O are observed in the early lake history, most likely associated with
lake ontogeny and the progressive deepening of Lake Ohrid. After MIS 10, the
observed variability between glacial and interglacial δ18O increases dramatically
concomitant with a lower reconstructed lake level, suggesting a more pronounced
sensitivity to hydroclimate change. A trend to higher interglacial δ18O through this time
frame traces the development of a warmer and drier Mediterranean climate regime.
Low-frequency δ18O oscillations are characterised by an orbital pacing dependent
on the phase of eccentricity, where transitions between zones of maximum and
minimum eccentricity (400 ka cycle) are associated with tipping points defined
by major shifts in δ18O. This sequence represents one of the most extensive and
highly-resolved terrestrial isotope records available, and highlights Lake Ohrid sediments as a
valuable archive of Quaternary palaeoclimate and palaeoenvironmental information. |
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