Annually resolved temperature reconstructions from a late Pliocene-early Pleistocene polar forest on Bylot Island, Canada

作者：Csank Adam Z^*; Fortier Daniel; Leavitt Steven W

来源：Palaeogeography, Palaeoclimatology, Palaeoecology, 2013, 369: 313-322.

DOI：10.1016/j.palaeo.2012.10.040

• Arctic
• Pliocene climate
• Stable isotopes
• Temperature
• Tree rings

Here we use delta O-18 ratios measured in tree rings of crossdated sub-fossil wood to reconstruct an annually resolved record of temperature and delta O-18 of meteoric water for an interglacial late Pliocene-early Pleistocene fossil forest found on Bylot Island, Nunavut, Canada. Our record represents the first crossdated record of Pliocene wood. Mean annual temperatures determined in this study average -3.4 +/- 3.8 degrees C, which is 11.4 +/- 4.4 degrees C warmer than present-day Bylot Island (-14.8 +/- 2.2 degrees C). June-July temperatures average 13.5 +/- 1.1 degrees C, approximately 12.6 +/- 1.6 degrees C warmer than present-day. Meteoric water delta O-18 values average -15.5 +/- 2.9 parts per thousand, similar to 2-6 parts per thousand more enriched than present values of precipitation delta O-18. Our temperatures are comparable to mid-Pliocene modeled temperatures for the Arctic (3-5 degrees C warmer than present), suggesting that interglacial warm periods in the late Pliocene-early Pleistocene may have been as warm as the mid-Pliocene warm period. That both the Bylot Island forest deposit and the Rap Kobenhavn deposit represent the remains of northern tree-line vegetation that lived during warm interglacial periods within the overall cool Plio-Pleistocene suggests that forest deposits in the Arctic capture a snapshot of interglacial conditions during the Plio-Pleistocene rather than the average Pliocene climate and may not be suitable records to study Pliocene cooling.

• 出版日期2013-1-1