Inferring paleotemperature from the D/ H ratio of lacustrine organic matter

Abstract

Linking the D/ H ( δD) records of the kerogen from bulk organic matter in lake sediments to known temperature– δD of precipitation relationships may offer new possibilities in paleoclimate studies. Here, we examine the hydrogen isotope ratio obtained from a radiocarbon-dated lake core from Wisconsin situated in the Midwestern part of the United States, to infer paleo-surface temperatures. Paleotemperatures were estimated by converting the δD values of the organic fraction to the δD values of the lake water and by implication to that of local precipitation. The temperature estimates show that the middle Holocene from 7000 to 5000 years before present (BP) was warmer by about 3 °C, in general agreement with speleothem data from the Midwestern United States. Our study shows the usefulness of the D/ H rations of kerogen from bulk sediment as a climate proxy that can compliment compound specific hydrogen isotope studies.