Sedimentological implications of microbial mats, gypsum, and halite in Dhahban solar saltwork, Red Sea coast, Saudi Arabia

Aref, Mahmoud A.; Taj, Rushdi J.; Mannaa, Ammar A.

doi:10.1007/s10347-020-0594-z

Cited by 11 publications

(2 citation statements)

References 54 publications

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“…The formation of stromatolites has been the subject of intense debate 5,7−9 that is still open because of a) the diversity of potentially organo-sedimentary structures (microbialites, stromatolites, thrombolites, etc. ), b) the plausibility of producing them by abiotic mechanisms claimed both in eld studies 10,11 and by numerical simulations 12,13 , and c) because, despite the predominance of calcium carbonate stromatolites [14][15][16] , similar structures made of silica [17][18][19][20][21][22] or gypsum [23][24][25][26][27][28][29][30][31] have also been reported. The proper use of these structures as a proxy to past environments depends critically on our knowledge of the processes shaping stromatolites or structures looking like stromatolites.…”

Section: Introductionmentioning

confidence: 99%

Mechanisms shaping the gypsum stromatolite-like structures in the Llamara Salar

Criado-Reyes

Otálora

Canals

et al. 2022

Preprint

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The explanation of the origin of microbialites and specifically stromatolitic structures is a problem of large relevance for decoding past sedimentary environments and deciphering the biogenicity of the oldest plausible remnants of life. We have investigated the morphogenesis of gypsum mushroom-shaped stromatolitic-like structures currently growing into shallow ponds (puquíos) in the Salar de Llamara (Atacama Desert, North Chile). The crystal size, aspect ratio, and orientation distributions of gypsum crystals within the structures have been quantified showing the existence of episodic nucleation and competitive growth of millimetric to centimetric selenite crystals into a radial, branched, loosely cemented aggregate. The morphogenetical process is explained by the existence of a vertical salinity stable gradient in the ponds. Due to the nonlinear dependency of gypsum solubility as a function of sodium chloride concentration, the density gradient produces undersaturated solutions dissolving gypsum crystals depth, narrowing the lower part of the structures, and producing their mushroom morphology. This novel mechanism is tested experimentally, showing the effective dissolution of gypsum crystals in stratified ponds, thus providing a purely abiotic mechanism for these stromatolitic-like structures.

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Section: Introductionmentioning

confidence: 99%

Mechanisms shaping the gypsum stromatolite-like structures in the Llamara Salar

Criado-Reyes

Otálora

Canals

et al. 2022

Preprint

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show abstract

“…These structures, more frequent in the past than nowadays, are commonly used as evidence of ancient microbial life and as environmental markers for the study of ancient shallow-water environments, especially in Archean and Proterozoic deposits, where they appear as one of the first forms of life on Earth 6 . The formation of stromatolites has been the subject of intense debate 5,[7][8][9] that is still open because: (a) the diversity of potentially organo-sedimentary structures (for instance, microbialites, stromatolites, or thrombolites), (b) the plausibility of producing them by abiotic mechanisms is claimed both in field studies 10,11 and by numerical simulations 12,13 , and (c) despite the predominance of calcium carbonate stromatolites [14][15][16] , similar structures made of silica [17][18][19][20][21][22] or gypsum [23][24][25][26][27][28][29][30][31] have also been reported. The proper use of these structures as a proxy to past environments depends critically on our knowledge of the processes that shape stromatolites or structures that resemble them.…”

mentioning

confidence: 99%

Mechanisms shaping the gypsum stromatolite-like structures in the Salar de Llamara (Atacama Desert, Chile)

Criado-Reyes

Otálora

Canals

et al. 2023

Sci Rep

View full text Add to dashboard Cite

The explanation of the origin of microbialites and specifically stromatolitic structures is a problem of high relevance for decoding past sedimentary environments and deciphering the biogenicity of the oldest plausible remnants of life. We have investigated the morphogenesis of gypsum stromatolite-like structures currently growing in shallow ponds (puquíos) in the Salar de Llamara (Atacama Desert, Northern Chile). The crystal size, aspect ratio, and orientation distributions of gypsum crystals within the structures have been quantified and show indications for episodic nucleation and competitive growth of millimetric to centimetric selenite crystals into a radial, branched, and loosely cemented aggregate. The morphogenetical process is explained by the existence of a stable vertical salinity gradient in the ponds. Due to the non-linear dependency of gypsum solubility as a function of sodium chloride concentration, the salinity gradient produces undersaturated solutions, which dissolve gypsum crystals. This dissolution happens at a certain depth, narrowing the lower part of the structures, and producing their stromatolite-like morphology. We have tested this novel mechanism experimentally, simulating the effective dissolution of gypsum crystals in stratified ponds, thus providing a purely abiotic mechanism for these stromatolite-like structures.

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Microbial mats and evaporite facies variation in a supralittoral, ephemeral lake, Red Sea coast, Saudi Arabia

Mannaa

Aref

2021

Facies

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Sedimentological implications of microbial mats, gypsum, and halite in Dhahban solar saltwork, Red Sea coast, Saudi Arabia

Cited by 11 publications

References 54 publications

Mechanisms shaping the gypsum stromatolite-like structures in the Llamara Salar

Mechanisms shaping the gypsum stromatolite-like structures in the Llamara Salar

Mechanisms shaping the gypsum stromatolite-like structures in the Salar de Llamara (Atacama Desert, Chile)

Microbial mats and evaporite facies variation in a supralittoral, ephemeral lake, Red Sea coast, Saudi Arabia

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