Deformed microbial mat structures in a semiarid temperate coastal setting

Cuadrado, Diana Graciela; Pan, Jerónimo; Gómez, Eduardo A.; Maisano, Lucía

doi:10.1016/j.sedgeo.2015.06.001

Cited by 18 publications

(8 citation statements)

References 36 publications

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“…We documented several enlarged MISS in a supratidal flat at Paso Seco (Argentina) where high dimensions are the most conspicuous feature, especially in microbial rollups, mat folds and gas domes. The environment is an elongated evaporitic-siliciclastic system, where recently hydrodynamic measurements enhance a previous study (Cuadrado et al, 2015) and provide more new evidence about mechanical explanations for their formation. The aim of the paper is to describe the interaction of biostabilized microbial mats with hydraulics, recognizing the mechanisms of formation and emphasizing the geomorphologic control as an important factor to take into consideration.…”

Section: Accepted Manuscriptmentioning

confidence: 52%

Processes of MISS-formation in a modern siliciclastic tidal flat, Patagonia (Argentina)

Maisano

Cuadrado

Gómez

2019

Sedimentary Geology

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The study focus on the description of several MISS as erosional pockets and remnants, flipped-over edges, and large microbial deformation structures as roll-ups, folds and gas domes, in the context of sediment composition, hydraulics, and geomorphology. The aim of the paper is to recognize the mechanisms of formation of MISS by analyses on hydrodynamics under the influence of the geomorphology. The study was conducted in an elongated inactive tidal channel colonized by microbial mats (2.5 x 0.3 km) in a progradation environment. To continuously record the water

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Section: Accepted Manuscriptmentioning

confidence: 52%

Processes of MISS-formation in a modern siliciclastic tidal flat, Patagonia (Argentina)

Maisano

Cuadrado

Gómez

2019

Sedimentary Geology

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“…Paso Seco's saline-like behavior during summer is found outside the subtropical highpressure belts where most marginal marine evaporitic environments are usually found (Babel and Schreiber, 2014). Similar to the Mediterranean sabkhas (Warren, 2016a), Paso Seco is a periodically flooded coastal flat, with little vegetation (Cuadrado et al, 2015). Salinity of the pore water in St. 3 when the flat is subaerially exposed is within the same range as the pore water of the saline zone (between 95 and 160 g L -1 ) in sabkhas located between Sulaymaniya lagoon and Sharm Obhur (Bahafzullah et al, 1993), and the Al-Kharrar sabkha (Aref and Taj, 2017), among others.…”

Section: Discussionmentioning

confidence: 98%

“…Geomorphologically, the study area comprises a sizeable closed basin (about 2.5 × 0.3 km), colonized by microbial mats and choked by a 1.8 kmwide sand spit formed by NE longshore sediment transport. Whenever strong winds combine with the effect of the spring tides or storms, seawater is pushed through the sand spit to enter the water into the basin, resulting in the flooding of the study area (Cuadrado et al, 2015). Sediment of the flat is predominantly sandy, and most of the surface of the flat is covered by microbial mats.…”

Section: Study Site and Water Sampling Periodmentioning

confidence: 99%

Microbial mat contribution to the formation of an evaporitic environment in a temperate-latitude ecosystem

Perillo

Maisano

Martínez

et al. 2019

Journal of Hydrology

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An evaporitic environment is characterized by having high salinity, climatic, and hydrological factors that promote a negative water balance; however, biological factors may also influence their development. Modern coastal flat Paso Seco (40°33′S; 62°14′W) is located in a semi-arid region with low precipitation and dry winds coming mainly from the NW. The site is an old tidal channel, which nowadays behaves like a shallow coastal saline-like basin, separated from the sea by a sand barrier, which the sea periodically overcomes, flooding the flat with eventual water evaporation. Microbial mats of up to 1 cm thick colonize the sandy sediments of this evaporitic environment. Water samples were taken during five field trips (2017-2018) from interstitial water of the flat, a tidal creek that crosses the flat, and two shallow tidal depressions (TDs) within the flat with different degrees of evaporation. In comparison to the sea, the maximum salinity values measured in Austral spring (September 2017) in the tidal creek were doubled, tripled in interstitial water, and 5.9 to 8 times higher in TDs. Ionic concentration denotes that evaporite chemical divides are followed as water evaporates, corresponding to the presence of CaCO 3 , gypsum and halite found in TDs. On-site permeability of microbial mat-covered surfaces presented semi-pervious properties. Microbial mat presence is condition for CaCO 3 , gypsum, and halite precipitation as they allow for water retention and its consequent evaporation due to the impermeability they confer to the sedimentary surface. Thus, microbial mats are a biological factor affecting the development of an evaporitic environment.

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“…The narrowing produces a current amplification and the water column reaches a maximum of 78 cm over the colonized flat. The fast flood currents are the primary factor in developing large microbial deformation structures such as roll-ups and folds, several metres in size (Cuadrado et al, 2015;Maisano et al, 2019). These huge structures form simultaneously with ripples during a storm.…”

Section: Study Areamentioning

confidence: 99%

Geobiological model of ripple genesis and preservation in a heterolithic sedimentary sequence for a supratidal area

Cuadrado

2020

Sedimentology

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This study documents the processes involved in forming flaser and wavy bedding governed by microbial activity in sediments. It focuses on a modern marginal‐tidal system providing evidence of the role that biofilms play in the stabilization of ripples and their potential preservation. A combination of detailed field work, analysis of water level records and microscopic petrographic inspection were used to reply to the question: how fine‐grained and coarse‐grained sediments can sequentially be deposited and preserved in a coastal environment. The hydraulic energy was measured by water level sensors recording flooding events that inundate the colonized tidal flat. Changing surface morphologies were monitored after storms, revealing the importance of biological processes in the preservation of ripples. A mud drape over ripples was observed several days after the undulated surface formation, known as a sinoidal sedimentary structure, which is a thin biofilm covering the ripples, caused by the presence of a microbial mat. Because bedforms are essential predictors of palaeoenvironmental reconstruction, interpretation in the geological record should take into consideration the important effect that colonized sediments have on the preservation of ripples. A geobiological model explains the flaser sedimentation, common in depositional coastal environments, suggesting that the hydrodynamic conditions may not be directly reflected by the grain size at the time of deposition. The study reveals that flaser sedimentation involves an interaction with benthic organisms, reflected by the sequence of microbial mats with sand ripple marks. A detailed description of heterolithic sequences shows that the presence of microbial activity can drive ripple preservation. This suggests that hydraulic interpretation of the sedimentary record based only on physical processes might be erroneous.

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Deformed microbial mat structures in a semiarid temperate coastal setting

Cited by 18 publications

References 36 publications

Processes of MISS-formation in a modern siliciclastic tidal flat, Patagonia (Argentina)

Processes of MISS-formation in a modern siliciclastic tidal flat, Patagonia (Argentina)

Microbial mat contribution to the formation of an evaporitic environment in a temperate-latitude ecosystem

Geobiological model of ripple genesis and preservation in a heterolithic sedimentary sequence for a supratidal area

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