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Diatom microfossils from cretaceous and eocene sediments contain native silica precipitating long‐chain polyamines
Author(s) -
Bridoux M. C.,
Ingalls A. E.
Publication year - 2013
Publication title -
geobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.859
H-Index - 72
eISSN - 1472-4669
pISSN - 1472-4677
DOI - 10.1111/gbi.12028
Subject(s) - diatom , biogenic silica , frustule , carbon fibers , biomolecule , geology , limiting , nitrogen , paleontology , chemistry , oceanography , materials science , organic chemistry , biochemistry , composite number , composite material , mechanical engineering , engineering
Organic molecules from known biological sources (biomarkers) that are preserved over geological time are critical tools in the study of past conditions and events on earth. Polar molecules are typically recycled rapidly in marine environments and do not survive burial within aquatic sediments in unambiguously recognizable form. As such, geological biomarkers are formed almost exclusively from precursor biomolecules that have been altered, limiting their utility as paleoproxies. Here, we report that nitrogen‐rich aliphatic long‐chain polyamines ( LCPA s), biosynthesized by diatoms in species‐specific assemblages for the precipitation of nanopatterned siliceous cell walls (frustules), are preserved unaltered in the oldest available diatom fossils dating to the L ower C retaceous (early A lbian, 115–110 Ma). We further show that the cumulative LCPA pool accounts for 60% of the total C and 80% of the total N preserved in the C retaceous age sediments. We suggest that silica glass formation by diatoms constitutes an important preservation mechanism for source‐specific, polar biomolecules, protecting them indefinitely by encapsulation within the silicified frustule. LCPA s are a unique, source‐specific carbon and nitrogen archive of diatom biomass, offering a promising tool for reconstruction of global cycles of carbon and nitrogen over geological timescales.