Treatise on Geochemistry | Fantle Research Group at Penn State

Demystifying Diagenesis: The Future of Diagenetic Inquiry in the Geosciences
Fantle, M. S. and Lloyd, M. K. (2025)
In Treatise on Geochemistry (3rd ed.), Anbar, A. and Weis, D. [eds], v. 2, pp. 249-314, doi: 10.1016/B978-0-323-99762-1.00062-0

fantle and lloyd figure 1 [image]

The diagenetic realm, as depicted by Dunoyer de Segonzac (1968), between the sub-realms of weathering, sedimentation (deposition), and metamorphism. The boundaries between the diagenetic realm and the sub-realms are designated by Dunoyer de Segonzac (1968) as ‘frontiers’ for future research. For the marine sedimentary realm, schematic illustrations are provided that depict the types of environments pertinent to the discussion in this chapter, as well as the dominant processes of interest – organic carbon oxidation and 𝐶𝑎𝐶𝑂_3 dissolution/precipitation/recrystallization – and primary transport modes associated with the settings depicted.

Abstract — Diagenesis encompasses all physical, chemical, mineralogical changes that a sediment, rock, molecule, or mineral undergoes following deposition. Because the time that geologic materials spend in the diagenetic realm is substantial relative to the time spent in the formational environment, there is potential for primary materials to be altered diagenetically. Despite its importance, diagenesis is a difficult and complicated topic to discuss. In this contribution, we demonstrate the use of a range of quantitative tools, from mixing equations to reactive transport models, in order to facilitate discussions of diagenesis. We consider simple models of 𝐶𝑎𝐶𝑂₃ recrystallization and dolomitization that are applicable to both shallow and deep-sea marine sediments, highlight key controls on diagenetic trajectories, present a compilation of partition coefficients for 𝐶𝑎𝐶𝑂₃ and clays, and discuss model illustrations of the diagenetic generation/modification, of carbon, calcium, and lithium isotopic records in the marine sedimentary section.

Key Objectives

Discuss what is needed to move diagenetic research forward, including a more precise language, quantitative frameworks, and avenues for future research;
Derive simple quantitative approaches in a step-by-step manner to serve as a resource and to facilitate a deeper understanding of quantitative approaches;
Demonstrate quantitative approaches to addressing diagenetic processes such as partial dissolution, 𝐶𝑎𝐶𝑂₃ authigenesis, and recrystallization;
Provide model-based expectations for the impacts of diagenetic alteration of 𝐶𝑎𝐶𝑂₃ in single phase and multi-phase systems; and
Illustrate diagenetic influences on generating and modifying lithium, carbon, and calcium isotopic excursions.

Table 2

I cannot seem to get Elsevier to format Table 2 as submitted. The table below ist he submitted version, which I hope is more clear to folks:

Fantle and Lloyd (2025) Table 2

Supplementary Material

This chapter contains a range of supplementary material that is meant to enhance the impact of the chapter and promote the study of diagenesis. Please cite the chapter if you use material from the repository or results from the model interfaces.

The ScholarSphere repository contains model input files, code, and supplemental material referenced and/or utilized in the Treatise on Geochemistry chapter.
If there is anything that you would like added to this repository, please email mfantle at psu.edu with your request.

URL: https://scholarsphere.psu.edu/; search for Fantle and Lloyd

Along with the material in the ScholarSphere repository, there are a number of model interfaces that are hosted on the isee Exchange site. If you have any problems with the interfaces or requests for additional interfaces or functionality, please email me:

[1a] Carbonate (CaCO₃) recrystallization model presented in Section 2:

https://exchange.iseesystems.com/public/matthewfantle/fantle-and-lloyd-2024-carbonate-recrystallization-model

three-box model schematic [image]