254-5 Fluorescence Spectroscopy of Amber of Different Botanical Origins

Session: Recent Advances in Fossil Imaging

Presenting Author:

Victoria McCoy

Authors:

McCoy, Victoria E¹, Stoneman, Michael R², Bober, Katherine Mae Maxine³, Delclòs, Xavier⁴, Peñalver, Enrique⁵, Gee, Carole T⁶, Raicu, Valerică⁷

(1) Department of Geosciences, University of Wisconsin-Milwaukee, Milwaukee, WI, USA, (2) Department of Physics, University of Wisconsin-Milwaukee, Milwaukee, WI, USA, (3) Department of Geology&Geophysics, Texas A&M University, College Station, TX, USA, (4) Departament de Dinàmica de la Terra i de l'Oceà, Facultat de Ciències de la Terra, Universitat de Barcelona, Barcelona, Spain, (5) Instituto Geológico y Minero de España (IGME), Consejo Superior de Investigaciones Científicas, Valencia, Spain, (6) Division of Paleontology, Bonn Institute of Organismic Biology, Bonn, Germany, (7) Department of Physics, University of Wisconsin-Milwaukee, Milwaukee, WI, USA,

Abstract:

We present a novel two-photon fluorescence micro-spectroscopy method for the chemotaxonomic characterization of Recent and fossil resins. While numerous techniques exist for chemically characterizing resin, which can provide information on its original chemical composition, fossilization process, and botanical origin, our method complements these by offering a non-destructive, fluorescence-based alternative that captures spatial and spectral variation at high resolution. Fluorescence images were acquired for each sample across six excitation wavelengths, and a full emission spectrum was collected for each. The resulting fluorescence profiles were deconvolved using multi-Gaussian fitting, with each spectrum accurately modeled as a linear combination of four Gaussian components. Importantly, the mean emission wavelengths of these Gaussian components remained consistent across excitation wavelengths for a given sample but varied systematically between different resin types.  We applied this method to a variety of samples: Cretaceous amber from Lebanon, Spain, and France; Eocene Baltic amber; Pleistocene Araucariaceae copal from New Zealand; and Recent Araucariaceae resin from the Huntington Botanical Gardens in the USA. These differences in Gaussian means between the samples allowed us to separate them into five groups. Cross-referencing these groupings with prior geochemical and paleobotanical studies allowed us to infer likely botanic origins. The groups corresponded broadly to ambers from distinct conifer families, including Araucariaceae (groups 1 and 2 associated with the genera Wollemia and Araucaria; group 3 associated with the genus Agathis), Cupressaceae (group 4), and Baltic amber (group 5) with unresolved taxonomic affinity. These results demonstrate that fluorescence micro-spectroscopy is a novel and useful approach for characterizing fossil resin in a reproducible and non-destructive manner, and, in particular, may provide an additional line of evidence for inferring its botanic origin.  

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-9900

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