A kimberlite crater in Canada, said to be 53 million years old, yielded exquisitely preserved unfossilized wood.

Miners were digging for diamonds and found unfossilized wood encased in the rock.  Diamonds are usually found in kimberlite dikes that erupt the gems rapidly from deep in the earth in “explosive phreatomagmatic events” (1/12/2012, 5/07/2007).  The discovery was reported on PLoS ONE by Wolfe et al. (“Pristine Early Eocene Wood Buried Deeply in Kimberlite from Northern Canada,” PLoS ONE 7(9): e45537. doi:10.1371/journal.pone.0045537):

We report exceptional preservation of fossil wood buried deeply in a kimberlite pipe that intruded northwestern Canada’s Slave Province 53.3±0.6 million years ago (Ma), revealed during excavation of diamond source rock. The wood originated from forest surrounding the eruption zone and collapsed into the diatreme before resettling in volcaniclastic kimberlite to depths >300 m, where it was mummified in a sterile environment. Anatomy of the unpermineralized wood permits conclusive identification to the genus Metasequoia(Cupressaceae). The wood yields genuine cellulose and occluded amber, both of which have been characterized spectroscopically and isotopically. From cellulose δ18O and δ2H measurements, we infer that Early Eocene paleoclimates in the western Canadian subarctic were 12–17°C warmer and four times wetter than present. Canadian kimberlites offer Lagerstätte-quality preservation of wood from a region with limited alternate sources of paleobotanical information.

The genus Metasequoia includes the dawn redwood, a “living fossil” rediscovered in China.  “Metasequoia was common in southern Alaska in the Late Paleocene and Early Eocene, producing a rich record of foliage and cones,” they said.  Fossils are rare in the discovery region due to extensive denudation and erosion by subsequent glaciers.  Finding warm-climate conifer wood in a glaciated environment indicates huge climatic changes over time, and periods that supported extensive forestation in spite of much higher relative temperatures….

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