Climatic forcing of carbon-oxygen isotopic covariance in temperate-region marl lakes

Carbon and oxygen stable isotopic compositions of lacustrine carbonate from a southeastern Michigan marl lake display linear covariance over a range of 4.0% Peedee belemnite (PDB) in oxygen and 3.9% (PDB) in carbon. Mechanisms of delta 13 C-delta 18 O coupling conventionally attributed to lake closu...

Full description

Saved in:
Bibliographic Details
Published inGeology (Boulder) Vol. 23; no. 11; p. 1031
Main Authors Drummond, C N, Patterson, W P, Walker, J C
Format Journal Article
LanguageEnglish
Published United States 01.11.1995
Subjects
Carbon - analysis
Carbon Isotopes
Carbonates - analysis
Climate
Fresh Water - analysis
Fresh Water - chemistry
Geologic Sediments - analysis
Geologic Sediments - chemistry
Michigan
Oxygen - analysis
Oxygen Isotopes
Paleontology
Rain
Seasons
Michigan
NASA Discipline Number 52-30
NASA Discipline Exobiology
NASA Program Exobiology
Non-NASA Center
Online AccessGet more information

Cover

More Information
Summary:Carbon and oxygen stable isotopic compositions of lacustrine carbonate from a southeastern Michigan marl lake display linear covariance over a range of 4.0% Peedee belemnite (PDB) in oxygen and 3.9% (PDB) in carbon. Mechanisms of delta 13 C-delta 18 O coupling conventionally attributed to lake closure in arid-region basins are inapplicable to hydrologically open lake systems. Thus, an alternative explanation of isotopic covariance in temperate region dimictic marl lakes is required. We propose that isotopic covariance is a direct record of change in regional climate. In short-residence-time temperate-region lake basins, summer meteoric precipitation is enriched in 18O relative to winter values, and summer organic productivity enriches epilimnic dissolved inorganic carbon in 13C. Thus, climate change toward longer summers and/or shorter winters could result in greater proportions of warm-month meteoric precipitation, longer durations of warm-month productivity, and net long-term enrichment in carbonate 18O and 13C. Isotopic covariance observed in the Michigan marl lake cores is interpreted to reflect postglacial warming from 10 to 3 ka followed by cooler mean annual temperature, a shift toward greater proportions of seasonal summer precipitation, a shortening of the winter season, or some combination of these three factors.
ISSN:0091-7613
DOI:10.1130/0091-7613(1995)023<1031:CFOCOI>2.3.CO;2