Diagenetic History of Fossil Wood from the Paleocene Chickaloon Formation, Matanuska Valley, Alaska
The Paleocene-Eocene transition was a fascinating period of geologic time in which the polar regions of the Earth were much warmer. This warmth allowed peat-generating swamp forests to grow and become fossilized at much higher latitudes than the present day. The mechanism behind the preservation of these pieces of wood is little understood, along with the implications that the permineralizing phase may have for unraveling the environmental conditions at the time. This study recreates the permineralization history of samples of permineralized wood, and takes and adapts models of carbonate nodule formation in order to interpret the meaning that differential carbonate permineralization and deformation between fossil woods of various strata provide. These results can be taken and applied to fossil woods of other swampy and coastal regions in the interpretation of their paleoenvironments as well. It was found that the hydrologic conditions in these swamps were influenced by brackish water input; this altered the dominant permineralizing carbonate phase from siderite to ferroan calcite and dolomite over time, causing a shift in bulk chemistry from 42 wt% iron to 6 wt% iron within the permineralizing carbonates. Anatomical distortions in the fossilized trees are also examined, and it was further found that the force of crystallization from authigenic crystal volume increase caused a variety of distortions, some of which are important for the proper interpretation of paleoecolocigal reconstructions. Examination of relict carbonate textures and the quality of organic preservation in both carbonate and silica phases, argues for a late stage recrystallization of the carbonates, and calls into question the validity of isotope data taken from those carbonates.
Franklin and Marshall College Archives, Undergraduate Honors Thesis 2009
- F&M Theses Collection