54-8 Global Coal Ball Stable Isotope Analysis to Define Permineralizing Environments

Session: New Approaches to Old Fossil Collections

Presenting Author:

Hannah Beddow

Authors:

Beddow, Hannah¹, Anderson, Thomas F.², Christie, Max³, Punyasena, Surangi W.⁴, Elrick, Scott⁵, Johnson, Thomas M.⁶, Conroy, Jessica L.⁷

(1) University of Missouri, Columbia, Missouri, USA; University of Illinois, Urbana, Illinois, USA, (2) University of Illinois, Urbana, IL, USA, (3) University of Illinois, Urbana, IL, USA, (4) University of Illinois, Urbana, IL, USA, (5) Illinois State Geo. Survey, Champaign, IL, USA, (6) Univ. of Illinois - Urbana Champaign, Dept of Geology- 3081 NHB, Urbana, IL, USA, (7) University of Illinois Urbana-Champaig, Department of Geology, Urbana, IL, USA,

Abstract:

Coal balls are permineralized calcareous remains of plant material from peat swamps of the late Carboniferous and early Permian, formed under conditions unique to the time period by processes that are still not fully understood. While multiple pathways have been proposed for the formation of coal balls, there is currently no consensus. Geochemical, petrological, and cyclostratigraphic results from previous studies have provided conflicting evidence suggesting that meteoric water or marine water is the source of the calcium carbonate ions responsible for permineralizing areas of the peat swamp. Similarly, there is a lack of consensus regarding the specific triggering mechanism by which calcite begins to precipitate within the peat. We aimed to establish a comprehensive global geochemical dataset of stable isotope values, with the goal of characterizing the environments and conditions necessary for the formation of coal balls. Our δ¹³C, δ¹⁸O, and ⁸⁷Sr/⁸⁶Sr measurements were within the range of a meteoric water source with a small number of outliers that suggested a marine water source. We interpret these results as indicating that coal balls formed in a predominantly meteoric water environment, with occasional inputs of marine water into the peat swamp. 

 

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

doi: 10.1130/abs/2025AM-10183

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