BECAS
FERREYRA Camila
artículos
Título:
Fossil bubble structure related to microbial activity coeval with the middle Ediacaran Oceanic Oxygenation Event in the Tandilia System
Autor/es:
MARIA JULIA ARROUY; LUCIA GÓMEZ PERAL; VICTORIA PENZO; CAMILA FERREYRA; DANIEL POIRÉ
Revista:
Latin American Journal of SEdimentology and Basin Analysis
Editorial:
Asociacion Argentina de Sedimentología
Referencias:
Lugar: La Plata; Año: 2021 vol. 28 p. 1 - 39
ISSN:
1851-4979
Resumen:
The well-preserved limestone succession, Loma Negra Formation (~40 m), in theTandilia System was deposited in a shallow carbonate ramp under low energyconditions. The evolution in the depositional settings of the unit was indicatedas deepening upwards varying from shallow-middle to outer ramp environment.The limestone fabric is assumed as the product of biologically controlledprecipitation of micrite, where the terrigenous supply was limited. From detailedmeso- and microscopic descriptions it is possible to recognize microbially inducedsedimentary structures MISS represented by typical microtextures related tomicrobial activity that appear represented throughout the entire formation. Inaddition, micro-stromatolites are observed in the unit associated with the microbialmats showing micro-columnar conical to domical morphologies.In the basal and middle Loma Negra Formation, hemispherical structures arerecognized in the bed-tops and interpreted as bubbles-like and gas escape featuresassociated with the microbial mat interaction. Their morphology is compared withoxygen bubbles produced by modern experimental modelling with photosyntheticcyanobacteria microbial mats. Moreover, hemispherical structures are associatedwith increasing gas pressure lifting grains and the organic components to thesurface.This paper provides evidence to understand the possible causal relationshipbetween microbial activity and seawater oxygenation. The high oxygen productionrevealed by geochemistry proxies and here proposed as probably associated withphotosynthetic microbial activity might be a plausible explanation for the recordof the documented Middle Ediacaran Oceanic Oxygenation Event in the LomaNegra Formation.
