EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Towards a morphology diagram for terrestrial carbonates: Evaluating the impact of carbonate supersaturation and alginic acid in calcite precipitate morphology

Mike Rogerson1, Ramon Mercedes-Martín2, Timothy Prior3, Alexander Brasier4, John Reijmer5, Ian Billing6, Anna Matthews7, Tracy Love7, Scott Lepley7, and Martyn Pedley3
Mike Rogerson et al.
  • 1Northumbria University, Newcastle NE1 8ST, UK (
  • 2SZALAI Grup S.L, P.O Box 1005, Caimari 07314, Spain
  • 3University of Hull, Cottingham Road, Hull HU6 7RX4, UK
  • 4University of Aberdeen, Old Aberdeen, Scotland AB24 3UE, UK
  • 5Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands
  • 6University of Derby, Kedleston Road, Derby DE22 1GB, UK
  • 7BP Exploration, 25, Chertsey Road, Sunbury on Thames TW16 7LN 26, UK

Ancient and recent terrestrial carbonate-precipitating systems are characterised by a heterogeneous array of deposits volumetrically dominated by calcite. In these environments, calcite precipitates display an extraordinary morphological diversity, from single crystal rhombohedral prisms, to blocky crystalline encrustations, or spherulitic to dendritic aggregates. Despite many decades of thorough descriptive and interpretative work on these fabrics, relating calcite micro-morphology with sedimentary hydrogeochemical conditions remains a challenge. Environmental interpretations have been hampered by the fact that calcite morphogenesis results from the complex interaction between different physico-chemical parameters which often act simultaneously (e.g., carbonate mineral supersaturation, Mg/Ca ratio of the parental fluid, organic and inorganic additives). To try to experimentally address the sedimentological causes of calcite morphogenesis, an experimental approach yielding a first attempt at a calcite growth-form phase diagram is presented here. The initial aim was to account for the carbonate products experimentally nucleated in alkaline, saline lake settings. These are the result of at least two competing calcite precipitation ‘driving forces’ that affect morphogenesis: the calcite supersaturation level of the parental fluid, and the concentration of microbial-derived organic molecules (alginic acid). A key finding of this study is that common naturally-occurring calcite products such as calcite floating rafts, rhombohedral prismatic forms, di-pyramid calcite crystals, spherulitic calcite grains, or vertically stacked spheroidal calcite aggregates, can be related to specific hydrogeochemical contexts, and their physical transitions pinpointed in a phase diagram. By exploring binary or ternary responses to forcing in morphological phase-space, links between calcite growth forms and (palaeo)environmental conditions can be determined. This provides a truly process-oriented means of navigating questions around carbonate precipitate morphogenesis for the future.

How to cite: Rogerson, M., Mercedes-Martín, R., Prior, T., Brasier, A., Reijmer, J., Billing, I., Matthews, A., Love, T., Lepley, S., and Pedley, M.: Towards a morphology diagram for terrestrial carbonates: Evaluating the impact of carbonate supersaturation and alginic acid in calcite precipitate morphology, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4342,, 2022.