Abiogenic aragonite crystal habit – Novel archive of precipitation environment?
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Authors | Adrian Immenhauser, Yisi Zhong, Lokier, S., Dominik Hennhoefer, Chelsea L. Pederson and Mathias Mueller |
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Abstract | Marine calcite cement's crystal habit is often considered a function of the fluid Mg/Ca ratio. In contrast, marine aragonite fabrics are commonly described as acicular (needle) cement with pointed terminations and width-to-length ratios in the order of 1:10. Similarly, botryoidal or spherulitic aragonite cements are well-known from Mesozoic (and older) reefal and slope depositional environments but are less common in Recent depositional environments. Here, we explore a wide range of abiogenic aragonite cement habits (morphologies) in caves and coastal marine depositional environments. We propose that the cement habit represents a novel (and underexplored) archive of diagenetic environment, fluid chemistry and precipitation kinetics. Based on SEM imaging, we find the often-described acicular and fibrous fabrics but also a plethora of less well-known morphotypes such as columnar (often pseudo-hexagonal prisms) and lath, tabular and sheet-like (prismatic single crystals) forms. Twinning of (flat) needle aragonite is observed and might point to precursor phases. Based on the data available, the common needle-type aragonite cement typifies normal marine diagenetic (porewater) environments. Increasingly complex habits (polysynthetic twins, flat needles, pseudo-prismatic and prismatic sheet-like) aragonite crystals) are present under increasing levels of restriction and precipitate from high-salinity porewaters. Intriguingly, pseudo-prismatic aragonite crystals are also present in meteoric, gravity-defying cave carbonates, specifically helictites. Aragonite cement habits are documented and placed into context with their depositional and diagenetic environment, and preliminary interpretations are presented. |
Keywords | Marine calcite ; marine aragonite fabrics ; depositional environments |
Year | 2023 |
Publisher | European Geosciences Union |
Digital Object Identifier (DOI) | https://doi.org/10.5194/egusphere-egu23-1149 |
Web address (URL) | https://doi.org/10.5194/egusphere-egu23-1149 |
Output status | Published |
Publication dates | 22 Feb 2023 |
Publication process dates | |
Deposited | 02 Mar 2023 |
https://repository.derby.ac.uk/item/9x6x3/abiogenic-aragonite-crystal-habit-novel-archive-of-precipitation-environment
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