Descripción del proyecto
Avances en la identificación de microfósiles
Las pruebas más convincentes de la vida en la Tierra hace miles de millones de años y su posterior evolución proceden de los registros fósiles conservados en capas de rocas sedimentarias. Los océanos también conservaron células microbianas en depósitos de ópalo debido a su naturaleza rica en sílice. Sin embargo, distinguir los microorganismos de las estructuras no biológicas es difícil por la falta de complejidad morfológica y debido a una degradación generalizada. En el proyecto TRACES, financiado por el Consejo Europeo de Investigación, se pretende investigar el efecto de la silicatación artificial y la alteración térmica en las estructuras de los microorganismos. Sus investigadores compararán los resultados con la vida fosilizada para desarrollar un modelo dinámico que permita comprender la conservación de los microfósiles y diferenciarlos de los artefactos no biológicos.
Objetivo
Reconstructing the nature and habitat of early life is a difficult task that strongly depends on the study of rare microfossils in the ancient rock record. The preservation of such organic structures critically depends on rapid entombment in a mineral matrix. Throughout most of Earth’s history the oceans were silica-supersaturated, leading to precipitation of opal deposits that incorporated superbly preserved microbial cells. As we trace this record of life back in deep time, however, three important obstacles are encountered; 1) microorganisms lack sufficient morphologic complexity to be easily distinguished from each other and from certain abiologic microstructures, 2) the ancient rock record has been subjected to increased pressures and temperatures causing variable degradation of different types of microorganism, and 3) early habitats of life were dominated by hydrothermal processes that can generate abiologic organic microstructures. TRACES will study the critical transformations that occur when representative groups of microorganisms are subjected to artificial silicification and thermal alteration. At incremental steps during these experiments the (sub)micron-scale changes in structure and composition of organic cell walls are monitored. This will be compared with fossilized life in diagenetic hot spring sinters and metamorphosed Precambrian chert deposits. The combined work will lead to a dynamic model for microfossil transformation in progressively altered silica-matrices. The critical question will be answered whether certain types of microorganisms are more likely to be preserved than others. In addition, the critical nano-scale structural differences will be determined between abiologic artefacts – such as carbon coatings on botryoidal quartz or adsorbed carbon on silica biomorphs – and true microfossils in hydrothermal cherts. This will provide a solid scientific basis for tracing life in the oldest, most altered part of the rock record.
Ámbito científico
Programa(s)
Régimen de financiación
ERC-COG - Consolidator GrantInstitución de acogida
75238 Paris
Francia