Stable Isotope Analyses from McCammon Pond, Idaho: a Limnologic Approach to Late Holocene Climate in Southeast Idaho
Additional Funding Sources
The project described was supported by the Career Path Internship Program of Idaho State University and the ISU Stable Isotope Laboratory of the Center for Archaeology, Materials, and Applied Spectroscopy (CAMAS).
Presentation Date
7-2018
Abstract
Analysis of lacustrine sediments from McCammon Pond, Idaho, was used to reconstruct climate and environmental change over the past ~3,500 years. The shallow carbonate-producing lake is contained in a ~14.5 thousand year-old (ka) Bonneville-Flood scour depression atop a ~430 ka basalt flow. Constrained by radiocarbon dates and tephrochronology, stable isotope analyses of nitrogen, oxygen, and carbon are used to interpret changes in lake productivity and climate. Analyses of oxygen isotopes from authigenic carbonate reveals a relatively arid period from ~3465 to 2500 calibrated years before present (BP), followed by a period of increasing moisture until about 1750 BP. Since that time, conditions have generally become more arid towards the present. High values of δ15N generally occur during wet periods, suggesting greater N availability. Likewise, organic δ13C is generally higher during wet periods and may reflect higher productivity and related changes in organic source material. Isotope data from McCammon Pond includes evidence for locally significant climate anomalies related to broader hemispheric patterns, such as the Medieval Warm Period and Little Ice Age. These findings provide a multi-decadal to centennial perspective of Late Holocene aridity and ecosystem response within the Marsh Valley corridor of the Basin and Range province.
Stable Isotope Analyses from McCammon Pond, Idaho: a Limnologic Approach to Late Holocene Climate in Southeast Idaho
Analysis of lacustrine sediments from McCammon Pond, Idaho, was used to reconstruct climate and environmental change over the past ~3,500 years. The shallow carbonate-producing lake is contained in a ~14.5 thousand year-old (ka) Bonneville-Flood scour depression atop a ~430 ka basalt flow. Constrained by radiocarbon dates and tephrochronology, stable isotope analyses of nitrogen, oxygen, and carbon are used to interpret changes in lake productivity and climate. Analyses of oxygen isotopes from authigenic carbonate reveals a relatively arid period from ~3465 to 2500 calibrated years before present (BP), followed by a period of increasing moisture until about 1750 BP. Since that time, conditions have generally become more arid towards the present. High values of δ15N generally occur during wet periods, suggesting greater N availability. Likewise, organic δ13C is generally higher during wet periods and may reflect higher productivity and related changes in organic source material. Isotope data from McCammon Pond includes evidence for locally significant climate anomalies related to broader hemispheric patterns, such as the Medieval Warm Period and Little Ice Age. These findings provide a multi-decadal to centennial perspective of Late Holocene aridity and ecosystem response within the Marsh Valley corridor of the Basin and Range province.
Comments
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