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A multi-proxy reconstruction of paleolimnology and paleoclimatic variability using authigenic lake carbonates from Cleland Lake, British Columbia
Mihindukulasooriya, Lorita Nivanthi

2014, PHD, Kent State University, College of Arts and Sciences / Department of Geology.
In small closed-basin lakes in semi-arid regions, variations in precipitation/evaporation (P/E) balance affect the physical, biological, and chemical composition of the lake water and sediment. This study presents visible derivative spectroscopy (VDS), XRF-derived elemental concentrations, sedimentological compositions, and d18O values of carbonates (d18Ocarb) in sediment cores from Cleland Lake, British Columbia. The data provides insight into paleolimnological variations during the past 14000 years, based on three sediment cores from shallow, intermediate and deep parts of the lake, and can be used as an analogue to understand future climatic changes and associated changes to aquatic ecosystems. VDS-based principal components (PCs) derived two PCs that correlate with illite/sphalerite and smectite/chlorite that indicate paleohydrology and lake sedimentary composition, respectively. Four of the PCs correlate with the standard reflectance curves of dinoflagellate algae, diatoms and cyanobacteria, and were used as paleoproductivity proxy. Lake productivity is limited to early successional cyanobacteria during deglaciation (14000 to 11500 cal yr BP). Rapid rise in dinoflagellates and a second cyanobacteria community suggest lower lake levels from 11600 to 8600 cal yr BP. Laminated to massive carbonate mud, rich in Ca, Sr, and calcium carbonate (LOI derived) provide additional evidence for a shallow lake. Conditions promoting cyanobacteria shifted toward those favoring diatoms around 9400 and lasted until 170 cal yr BP. A climate transition to wet conditions is suggested by rapid drops in percent CaCO3 and Ca levels and facies changes to well-laminated, organic-matter-rich sediment between 8700 and 8600 cal yr BP. A rapid decline in diatoms, cyanobacteria and dinoflagellate algae is recorded from 8500 to 7700 cal yr BP, simultaneous with the global-cooling event centered on 8200 cal yr BP. Lake sediment and phytoplankton abundance reflect rapid changes after the deposition of Mazama tephra around 7700 cal yr BP. Late Holocene levels of diatoms, carbonates, and illite suggest frequent changes in moisture levels at century scale, possibly associated with ocean-atmosphere tele-connection to the changes in solar irradiance. In contrast, early-Holocene lake level changes are associated with long-term climate forcing, like solar insolation, and reveal a much longer periodicity of around 5000 years. This research points out that natural forcing mechanisms affecting the sea surface temperature of the Pacific Ocean, similar to the solar insolation, solar irradiance and glacial melt water fluxes can affect the regional climate and the lake productivity by affecting the moisture transport to the region.
Joseph Ortiz (Advisor)
Alison Smith (Committee Member)
Neil Wells (Committee Member)
Darren Bade (Committee Member)
Laura Leff (Committee Member)
203 p.

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Mihindukulasooriya, L. (2014). A multi-proxy reconstruction of paleolimnology and paleoclimatic variability using authigenic lake carbonates from Cleland Lake, British Columbia. (Electronic Thesis or Dissertation). Retrieved from https://etd.ohiolink.edu/

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Mihindukulasooriya, Lorita. "A multi-proxy reconstruction of paleolimnology and paleoclimatic variability using authigenic lake carbonates from Cleland Lake, British Columbia." Electronic Thesis or Dissertation. Kent State University, 2014. OhioLINK Electronic Theses and Dissertations Center. 17 Jul 2018.

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Mihindukulasooriya, Lorita "A multi-proxy reconstruction of paleolimnology and paleoclimatic variability using authigenic lake carbonates from Cleland Lake, British Columbia." Electronic Thesis or Dissertation. Kent State University, 2014. https://etd.ohiolink.edu/

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