| Autor: |
Hook, B. A., Halfar, J., Gedalof, Z., Bollmann, J., Schulze, D. |
| Předmět: |
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| Zdroj: |
Biogeosciences Discussions; 2014, Vol. 11 Issue 11, p16269-16308, 40p, 4 Charts, 6 Graphs, 1 Map |
| Abstrakt: |
The recent discovery of well-preserved mummified wood buried within a subarctic kimberlite diamond mine prompted a paleoclimatic study of the early Eocene "hothouse" (ca. 53.3Ma). At the time of kimberlite eruption, the Subarctic and Artic were warm and humid producing a temperate rainforest biome well north of the Arctic Circle. Previous studies have estimated mean annual temperatures in this region were 4-20 °C in the early Eocene, using a variety of proxies including leaf margin analysis, and stable isotopes (δ18O) of fossil cellulose. Here, we examine stable isotopes of tree-ring cellulose at subannual to annual scale resolution, using the oldest viable cellulose found to date. We use mechanistic models and transfer functions to estimate earliest Eocene temperatures using mummified cellulose, which was well preserved in the kimberlite. Multiple samples of Piceoxylon wood within the kimberlite were crossdated by tree-ring width. Multiple proxies are used in combination to tease apart likely environmental factors influencing the tree physiology and growth in the unique extinct ecosystem of the Polar rainforest. Calculations of interannual variation in temperature over a multi-decadal time-slice in the early Eocene are presented, with a mean temperature estimate of 11.4 °C (1 σ = 1.8 °C) based on δ18O. Dual-isotope spectral analysis suggests that multidecadal climate cycles similar to the modern Pacific Decadal Oscillation likely drove temperature and cloudiness trends on 20-30 year timescales. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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