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TitleA ~14 000-year record of environmental change from Lake Simcoe, Canada
AuthorDoyle, R MORCID logo; Bumstead, N; Lewis, C F MORCID logo; Longstaffe, F JORCID logo
SourceQuaternary Science Reviews vol. 292, 107667, 2022 p. 1-15, Open Access logo Open Access
Alt SeriesNatural Resources Canada, Contribution Series 20210624
Mediapaper; on-line; digital
RelatedThis publication is related to ~14 000 years of geochemical and isotopic data from Lake Simcoe, Canada
File formatpdf
NTS31D/05; 31D/06; 31D/11; 31D/12
AreaLake Simcoe; Great Lakes; Lake Algonquin
Lat/Long WENS -80.0000 -79.0000 44.7500 44.2500
Subjectsenvironmental geology; sedimentology; Nature and Environment; History and Archaeology; geochronology; Holocene; Pleistocene; lake sediment geochemistry; lake water geochemistry; lake sediments; lakes; oxygen isotopes; paleoenvironment; Quaternary
Illustrationslocation maps; models; graphs; tables
Released2022 08 13
AbstractWhile the evolution of the Laurentian Great Lakes has been researched intensively, fewer studies have focused on reconstructing the history of Lake Simcoe, the fourth largest lake in southern Ontario. This study uses proxy data, including ostracod valves, contained in lake sediments to reconstruct a ~14 000-year history of paleoenvironmental change in the Lake Simcoe basin. First, oxygen-isotope compositions of ostracod valves (d18Ovalve) are used to estimate the oxygen-isotope composition of ancient lake water, d18Olake water. This d18Olake water record demonstrates that Lake Simcoe stopped receiving meltwater from Lake Algonquin at ~12 050 cal BP, substantiating the findings of previous research. This study also reveals that d18Olake water in Lake Simcoe is insensitive to changes in lake level but sensitive to changes in temperature, capturing periods such as early Holocene warming. Next, stable carbon-isotope compositions of ostracod valves (d13Cvalve) are used to estimate the stable carbon-isotope composition of dissolved inorganic carbon (d13CDIC) in Lake Simcoe. These data, combined with ostracod assemblages, grain size, magnetic susceptibility (MS) and sediment mineralogy, support our interpretation of temperature-sensitive variation in d18Olake water and provide further insights into in-lake conditions. A pronounced increase in sediment accumulation rate, and subtler increases in grain size and calcite contents, occur between ~7700 and ~8200 cal BP. These changes may reflect the abrupt transition from cold and dry to wet and warm conditions resulting from collapse of the Laurentide Ice Sheet at ~8200 cal BP. In summary, this study corroborates the previously reported date of hydrologic closure of Lake Simcoe based on geophysical evidence and provides a holistic picture of environmental change over the last ~14 000 years.
Summary(Plain Language Summary, not published)
A sediment core and the analysis of its contained ostracods and their Oxygen and Carbon isotopes along with other sediment properties and published information reveal the history of Lake Simcoe in southern Ontario, located between Georgian Bay of Lake Huron and Lake Ontario. The data show that the Lake Simcoe basin received meltwater from glacial Lake Algonquin from about 14,000 to 12,050 years ago. Some additional water possibly overflowed the Lake Simcoe sill during short-lived high-level episodes of Lake Mattawa in the Huron basin until about 9000 years ago. Subsequent temperature and aridity changes in Lake Simcoe reflect collapse of the Laurentide Ice Sheet and changes in the regional atmospheric environment.

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