Data associated with Diagenesis of fossil gar fish scales with implications for applications in thermochronology and paleoenvironmental reconstruction

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By John Fink1, Marissa M Tremblay1, Thomas S Tobin2, Lisa D Stockli3, Daniel F Stockli4, Ryan B Ickert5

1. Purdue University 2. Department of Geological Sciences, University of Alabama 3. University of Texas 4. Department of Geological Sciences, University of Texas at Austin 5. Department of Earth, Atmospheric, and Planetary Sciences, Purdue University

Data associated with the manuscript, "Diagenesis of fossil gar fish scales with implications for applications in thermochronology and paleoenvironmental reconstruction" by Fink et al., which has been submitted for peer review.

Version 1.0 - published on 24 Oct 2023 doi:10.4231/0MJV-CR59 - cite this Archived on 10 Nov 2023

Licensed under Attribution 4.0 International (CC BY 4.0)

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This repository contains supporting data and information for the manuscript submitted for peer review entitled Diagenesis of fossil gar fish scales with implications for geochronology and paleoenvironmental applications by John Fink, Marissa M. Tremblay, Thomas S. Tobin, Lisa D. Stockli, Daniel F. Stockli, and Ryan B. Ickert. In this manuscript, we examined microscopic textural characteristics, spatially resolved trace element patterns, and apparent gar scale ages using the (U-Th)/He and U-Th-Pb systems, in modern scales as well as fossil scales from Cretaceous to Paleogene age strata in the North American Williston and San Juan Basins, with the broader goal of evaluating the potential of fossil gar scales to be used as geochemical archives. 

We found that trace element concentrations in fossil bone are at least an order of magnitude higher than in ganoine and can be spatially heterogeneous, indicative of a complex and prolonged diagenetic history. Trace element concentrations in fossil ganoine often decrease systematically with distance from the ganoine surface. However, (U-Th)/He dates of ganoine are substantially younger than expected based on basin thermal histories and compared to conventional detrital apatite (U-Th)/He dates from the same localities. The ganoine (U-Th)/He dates also exhibit an inverse relationship with effective uranium concentrations. We interpret the young (U-Th)/He dates and the age-effective uranium relationship to indicate either protracted or late-stage addition of trace elements. The latter interpretation is supported by the U-Th-Pb systematics of ganoine, which require addition of U and Th at a time significantly later than the depositional age.

This repository includes:

  • A file named Gar Scale Sample Information.xlsx, which provides metadata about the fossil gar scales used in this study, including museum IDs, sample names, sample localities, stratigraphic information, and information about which type of analyses were carried out on which gar scales. This file also includes the contact information for the museums where these fossil gar scales are curated.
  • A folder called XRD Data, which contains X-ray diffraction (XRD) data from modern and fossil gar scale ganoine and bone. These XRD data can be used to make inferences about relative differences in crystallite size and orientation as well as mineral composition between the different gar scales and gar scale components analyzed. A readme file with more information about the data formats is provided within the folder.
  • A folder called LA-ICPMS Data, which contains spatially-resolved trace element concentrations in gar scales measured by laser ablation- inductively coupled plasma mass spectrometry (LA-ICPMS). Data were obtained both as spot transects in gar scales that were mounted in epoxy and polished as well as in unmounted gar scales as depth profiles into the ganoine component of the scale. Scanning electron microscope (SEM) images of ablation spots are also provided for spatial context where available. For additional details about how the LA-ICPMS data are reported, please see the readme file within the folder. 
  • A file named U-Th-He data.xlsx, which contains (U-Th)/He analytical data of fossil gar scale fragments and detrital apatite grains measured at the University of Colorado Boulder Thermochronology Research and Instrumentation Lab (TRaIL). Information to interpret the data reported in this file are provided as footnotes to the individual column headings.  
  • U-Th-Pb analytical data of fossil gar scale ganoine fragments measured by thermal ionization mass spectrometry (TIMS) at Purdue University. Information to interpret the data reported in this file are provided as footnotes to the individual column headings.  

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Version 1.0 was released to be concurrent with the initiation of peer review of the associated manuscript.

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