|Northeastern Section - 49th Annual Meeting (23–25 March)|
|Paper No. 17-3|
|Presentation Time: 2:15 PM-2:35 PM|
DECAY AND EARLY DIAGENESIS OF METASEQUOIA LEAVES: IMPLICATIONS FOR THREE-DIMENSIONAL PRESERVATION AND BULK ISOTOPE SIGNALS IN PLANT FOSSIL LAGERSTäTTEN
WITKOWSKI, Caitlyn1, LENG, Qin1, BLAIS, Brian1, FENG, Liang2, REID, Christopher1, WANG, Hongmei2, and YANG, Hong1, (1) Department of Science and Technology, Bryant University, 1150 Douglas Pike, Smithfield, RI 02917, email@example.com, (2) Department of Microbiology, China University of Geosciences, 388 Lumo Rd, Hongshan, Wuhan, 430072, China|
Plant remains from fossil lagerstätten have played a significant role in paleobotanical and paleoenvironmental studies, partly due to their remarkable preservation. While the mechanism for these exceptional preservations is still poorly understood, polysaccharides potentially offer insight, as they are more abundant in anatomically well-preserved plant fossils. In order to examine the role of polysaccharides in maintaining three-dimensional (3D) leaf structures and the impact of polysaccharide decay on bulk carbon isotope signals of leaf fossils, we investigated natural and laboratory decay of modern Metasequoia leaves, an important taxon in Cenozoic plant fossil lagerstätten, to mimic the early stages of diagenesis in leaf fossilization. Pyrolysis-gas chromatography-mass spectrometry, 3-methyl-2-benzothiazolinone hydrazine hydrochloride assay, and nuclear magnetic resonance analyses captured polysaccharide molecular abundances, while scanning electron microscopy qualitatively and a new Python-based method quantitatively revealed stages of morphological degradation. Our results show that polysaccharides do play a significant role in maintaining 3D structures of Metasequoia leaves; the lignin-strengthened tracheids and fiber cell walls in the xylem have remained almost intact throughout laboratory decay, whereas the cellulose-dominant phloem cell walls have gradually collapsed. Although bulk carbon measured by isotope ratio-mass spectrometry remain constant throughout the closed-system laboratory decay, the open-system natural decay showed a negative shift of ~1‰ in samples buried in pond sediment, suggesting that decomposition in the open aqueous environment led to carbon isotopic fractionations after partial removal of polysaccharides. Our morphological, molecular, and isotopic data from the natural and laboratory decay series provide benchmarks for estimating the degree stage of preservation in plant fossil lagerstätten that provide critical clues for ancient environments.
Northeastern Section - 49th Annual Meeting (23–25 March)
General Information for this Meeting
|Session No. 17|
An Interdisciplinary Approach to Taphonomy: The Impact of Morphological, Molecular, and Isotopic Changes on Environmental Proxies
Lancaster Marriott at Penn Square: Heritage Salon E
1:30 PM-4:10 PM, Sunday, 23 March 2014
© Copyright 2014 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.