Whole Earth Systems During Neoproterozoic Animal Evolution

Descripción del proyecto

La tectónica impulsa la evolución de todo el sistema terrestre en el pasado lejano

La era neoproterozoica (hace 1 000-541 millones de años) marca el momento de transición de una vida microbiana simple a una vida animal grande y compleja. La última glaciación global, en la que todo el planeta o la mayor parte del mismo se cubrió de hielo sólido durante unos diez millones de años, también marcó el final de esa era. El aumento del oxígeno atmosférico, unas alteraciones significativas del ciclo del carbono y la glaciación global se han vinculado con levantamientos tectónicos. Sin embargo, hasta hace poco no se disponía de modelos de la evolución de los bordes de las placas y de las placas tectónicas durante este período crítico. El proyecto NEOEARTH, financiado con fondos europeos, está desarrollando un modelo que vincula la tectónica, la biogeoquímica y el clima aplicando avances recientes en la modelización de la tectónica de placas. El nuevo modelo debería permitir evaluar el impacto de los motores tectónicos sobre los ciclos del oxígeno y del carbono, así como sobre el clima.

Objetivo

The late Neoproterozoic Era marks some of the most important changes in the biogeochemical evolution of our planet. During the late Cryogenian,Ediacaran and Early Cambrian Periods (ca. 650–520 Ma), our planet was marked by a global icehouse event (‘Snowball Earth’), a rapid rise in oxygen content of the atmosphere, evolution of animals and complex life forms and the amalgamation of the Gondwanian supercontinent, which formed the earliest ‘modern’ style mountain belts with the deep burial of continental crust resulting from massive continental-continental collisions. So far, biogeochemical modelling, geochemical analysis and general circulation climate models (GCMs) have linked all these key events to plate tectonic processes. However, there is yet to be a fully complete linked tectonic-biogeochemical-climate model, where geologically grounded parameters are passed directly into both biogeochemical and GCMs, principally because there is no full tectonic model of this time. Recent advancements in plate tectonic modelling have produced models that map the explicit kinematic evolution of plate boundaries and tectonic plates back to 1 Ga. Using this model as a foundation, I propose to construct secondary tectonic parameters (palaeobathymetry, palaeotopography, carbon flux) of the world between 650 and 520 Ma in order to act as a series of boundary conditions for a GCM and biogeochemical model. The GCM is constructed using the surface conditions from the tectonic parameters (palaeobathymetry, palaeotopography, continental positions) to produce surface temperature and hydrological estimates at key time intervals. These estimates, along with carbon flux estimates—calculated using the same plate model—are used to derive self-consistent biogeochemical cycles (e.g. O2, CO2, P cycles) which can then be evaluated against independent proxies from the geological record, allowing us to independently evaluate the impact of tectonic drivers on these pronounced global events.