STABLE CARBON AND OXYGEN-ISOTOPE RECORDS FROM LAKE ERIE SEDIMENT CORES - MOLLUSK ARAGONITE 4600 BP 200 BP

We present the first delta(18)O and delta(13)C data from mollusc arago nite from Lake Erie for the 4.6-0.2 ka (4600 BP to 200 (BPC)-C-14 yrs) time interval and describe single and composite species isotope trend s. Composite species delta(18)O data show an almost 2.0 parts per thou sand increase from 3.3 to 3.0 ka followed by a nearly 2.5 parts per th ousand decrease at 2.8 ka. Oxygen isotope values then fluctuate by < 1 parts per thousand until 0.2 ka. This trend in oxygen values is also evident in single species analyses of Sphaerium striatinum. The most d ramatic changes in isotope values, which occur from 3.3-2.8 ka, may re flect a pattern of water level changes in Lake Erie which occurred dur ing the Nipissing flood and its lower water aftermath. Carbon isotope data (-0.57 parts per thousand). This trend may reflect the dilution o f isotopically light CO2 from the oxidation of organic matter due to r ising lake levels. The short-term increase in delta(18)O values is cou pled with a corresponding decrease in delta(13)C values. A similar pat tern for Lake Erie prior to 10.5 ka was also associated with a lowerin g of water levels in the lake.