Forward numerical modelling of carbonate basins: an ecological approach

This thesis presents a new stratigraphic forward numerical model to simulate the carbonate production of marine sedimentary basin through ecological model which is implemented in the SIMSAFADIM-CLASTIC program. This ecological model is based on the Generalized Lotka Voltera equations that model the population evolution of species. These populations are controlled by biological factors (growth rate, carrying capacity and interaction among species), and by the environmental conditions (light, energy of the medium, nutrients, bottom slope and concentration of clastic sediments in suspension) which are combined forming a unique environmental factor that downscale the intrinsic rate of growth. The algorithm to apply in the code uses an explicit Runge-Kutta numerical method of order (4)5 to solve the differential equations formulated in the ecological model. Finally, a 3D visualization output files for the interpretation and analysis are generated using the VTK format. The obtained code has been applied in three sample experiments in order to discuss the possibilities and the limitations of the code. The first example is the model of a theoretical basin. The results are compared with real cases. The second example is an actual basin sited in western Mediterranean Sea. The results are discussed to show the applicability and the limitations of the model. The third example applies several configurations to the Aptian Galve sub-basin (Maestrat Basin, E Iberia), allowing to define the environmental conditions

Process-based forward numerical ecological modeling for carbonate sedimentary basins

Nowadays, numerical modeling is a common tool used in the study of sedimentary basins, since it allows to quantify the processes simulated and to determine interactions among them. One of such programs is SIMSAFADIM-CLASTIC, a 3D forward-model process-based code to simulate the sedimentation in a marine basin at a geological time scale. It models the fluid flow, siliciclastic transport and sedimentation, and carbonate production. In this article, we present the last improvements in the carbonate production model, in particular about the usage of Generalized Lotka-Volterra equations that include logistic growth and interaction among species. Logistic growth is constrained by environmental parameters such as water depth, energy of the medium, and depositional profile. The environmental parameters are converted to factors and combined into one single environmental value to model the evolution of species. The interaction among species is quantified using the community matrix that captures the beneficial or detrimental effects of the presence of each species on the other. A theoretical example of a carbonate ramp is computed to show the interaction among carbonate and siliciclastic sediment, the effect of environmental parameters to the modeled species associations, and the interaction among these species associations. The distribution of the modeled species associations in the theoretical example presented is compared with the carbonate Oligocene-Miocene Asmari Formation in Iran and the Miocene Ragusa Platform in Italy

Forward numerical modelling constraining environmental parameters (Aptian carbonate system, E Iberia)

The facies distribution in time and space of sedimentary successions is controlled by a complex interplay between physical, chemical and biological processes, which are nowadays difficult to construe from the geological record. Numerical models constitute a valuable tool to identify and quantify such controlling factors permitting a reliable 3D extrapolation and prediction of stratigraphic and facies architectures beyond outcropping rock strata. This study assesses the roles of three controlling parameters being carbonate production rate, relative sea-level changes and terrigenous clastic sediment supply, on the evolution of an Aptian carbonate system. The SIMSAFADIM-CLASTIC, a 3D process-based sedimentary-stratigraphic forward model, was used for this evaluation. The carbonate succession modelled crops out in the western Maestrat Basin (E Iberia), and corresponded to a platform-to-basin transition comprising three depositional environment-related facies assemblages: platform top, slope and basin. Testing of geological parameters in forward modelling results in a wide range of possible 3D geological scenarios. The documented distribution of facies and sequence-stratigraphic framework combined with a virtual outcrop model were used as a reference to perform geometric (quantitative) and architectural and stacking pattern (qualitative) research by model-data comparison. The time interval modelled spans 1450 ky. The best-fit simulation run characterizes and quantifies (1) relative sea-level fluctuations recording five different genetic types of deposit (systems tracts) belonging to two depositional sequences as expected from field-data analysis, (2) a rate of terrigenous clastic sediment input ranging between 0.5 and 2.5 gr/s, and (3) a mean autochthonous carbonate production maximum rate of 0.08 m/ky. Furthermore, the quantitative and qualitative sensitivity tests carried out highlight that the fluctuation of relative sea level exerted the main control on the resulting stratigraphic and facies architectures, whereas the effect of inflowing terrigenous clastic sediment is less pronounced. Facies assemblages show different sensitivities to each parameter, being the slope carbonates more sensitive than the platform top facies to inflowing fine terrigenous sediments. On slope depositional settings, siliciclastic input also controls stratal stacking patterns and the dimensions of the carbonate bodies formed. The final 3D model allows to spot architectural features such as stacking patterns that can be misinterpreted by looking at the resulting record in the outcrop or by using other 2D approaches, and facilitates the comprehension of reservoir connectivity highlighting the occurrence of initial disconnected regressive platforms, which were later connected during a transgressive stag

Modelación numérica de sedimentación subacuática sintectónica: efecto de la presencia de fallas normales y zonas de relevo en la distribución de sedimento.

Las fallas normales y las zonas de relevo son comunes en contextos extensivos y juegan un papel importante en la distribución de sedimento. Este control está bien estudiado en condiciones subaéreas, pero no es así en condiciones subacuáticas, donde los estudios son escasos. En estos casos, la modelación numérica puede ser una buena herramienta para entender y complementar la sedimentación sintectónica. En esta contribución, se presenta un nuevo modelo numérico (que combina deformación tectónica con sedimentación clástica) para estudiar el relleno sedimentario en una cuenca extensiva y, concretamente, en la zona de relevo entre fallas normales. Para este caso, se han definido diferentes configuraciones variando tres parámetros: (1) estructura; (2) tasa de desplazamiento de las fallas; y (3) localización del área fuente. La comparación entre los diferentes experimentos permite concluir que, la configuración estructural condiciona la sedimentación de los diferentes tipos de sedimento creando asimetrías en la distribución de sedimentos. Aún así, los correspondientes cinturones de facies (sedimento mayoritario) no reflejan esa asimetría y, por lo tanto, la posición de las fallas en profundidad. Además, la dirección de transporte condiciona el patrón de distribución llegando a obtener arquitecturas de depósito complejas con aparentes terminaciones estratigráficas que pueden inducir a errores interpretativos (terminaciones aparentes de estratos) en áreas sin información litológica

Forward numerical modelling of carbonate basins: an ecological approach

This thesis presents a new stratigraphic forward numerical model to simulate the carbonate production of marine sedimentary basin through ecological model which is implemented in the SIMSAFADIM-CLASTIC program. This ecological model is based on the Generalized Lotka Voltera equations that model the population evolution of species. These populations are controlled by biological factors (growth rate, carrying capacity and interaction among species), and by the environmental conditions (light, energy of the medium, nutrients, bottom slope and concentration of clastic sediments in suspension) which are combined forming a unique environmental factor that downscale the intrinsic rate of growth. The algorithm to apply in the code uses an explicit Runge-Kutta numerical method of order (4)5 to solve the differential equations formulated in the ecological model. Finally, a 3D visualization output files for the interpretation and analysis are generated using the VTK format. The obtained code has been applied in three sample experiments in order to discuss the possibilities and the limitations of the code. The first example is the model of a theoretical basin. The results are compared with real cases. The second example is an actual basin sited in western Mediterranean Sea. The results are discussed to show the applicability and the limitations of the model. The third example applies several configurations to the Aptian Galve sub-basin (Maestrat Basin, E Iberia), allowing to define the environmental conditions

Forward numerical modelling of carbonate basins: an ecological approach

This thesis presents a new stratigraphic forward numerical model to simulate the carbonate production of marine sedimentary basin through ecological model which is implemented in the SIMSAFADIM-CLASTIC program. This ecological model is based on the Generalized Lotka Voltera equations that model the population evolution of species. These populations are controlled by biological factors (growth rate, carrying capacity and interaction among species), and by the environmental conditions (light, energy of the medium, nutrients, bottom slope and concentration of clastic sediments in suspension) which are combined forming a unique environmental factor that downscale the intrinsic rate of growth. The algorithm to apply in the code uses an explicit Runge-Kutta numerical method of order (4)5 to solve the differential equations formulated in the ecological model. Finally, a 3D visualization output files for the interpretation and analysis are generated using the VTK format. The obtained code has been applied in three sample experiments in order to discuss the possibilities and the limitations of the code. The first example is the model of a theoretical basin. The results are compared with real cases. The second example is an actual basin sited in western Mediterranean Sea. The results are discussed to show the applicability and the limitations of the model. The third example applies several configurations to the Aptian Galve sub-basin (Maestrat Basin, E Iberia), allowing to define the environmental conditions

Modelling syntectonic sedimentation: combining a discrete element model of tectonic. Deformation and process-based sedimentary Model in 3D.

This paper presents a new numerical program able to model syntectonic sedimentation. The new model combines a discrete element model of the tectonic deformation of a sedimentary cover and a process-based model of sedimentation in a single framework. The integration of these two methods allows us to include the simulation of both sedimentation and deformation processes in a single and more effective model. The paper describes briefly the antecedents of the program, Simsafadim-Clastic and a discrete element model, in order to introduce the methodology used to merge both programs to create the new code. To illustrate the operation and application of the program, analysis of the evolution of syntectonic geometries in an extensional environment and also associated with thrust fault propagation is undertaken. Using the new code, much more complex and realistic depositional structures can be simulated together with a more complex analysis of the evolution of the deformation within the sedimentary cover, which is seen to be affected by the presence of the new syntectonic sediments

Incorporating nutrients as a limiting factor in carbonate modelling

Nowadays, the use of process-based numerical models to predict facies distribution and stratal architecture constitutes an essential tool in sedimentary basin analysis. One of these models, the SIMSAFADIM-CLASTIC program, simulates clastic transport and sedimentation in three dimensions together with autochthonous marine carbonate production. In this code, carbonate modelling mainly follows predator-prey relationships among species associations based on Lotka-Volterra equations. The carbonate model also considers other environmental factors such as the presence of siliciclastic sediments and carbonate mud in suspension and water depth. Although these parameters are important, carbonate producers are largely conditioned by other variables, which have to be taken into account in order to obtain a more realistic approach. In this contribution, nutrient availability is added as a new limiting environmental parameter, which exerts control over carbonate producing organisms. A synthetic sample experiment is used to show that inclusion of nutrient availability is critical to reproduce carbonate lithofacies heterogeneity in a more accurate temporal and spatial disposition as a function of trophic resources

Streamflow trends of the Pyrenees using observations and multi-model approach (1980-2013)

18 Pags.- 12 Figs.- 3 Tabls. © 2023 The Authors. Published by Elsevier B. V. This is an open access article under the CCBY-NC-ND license.Study region The Pyrenees. Study focus The Pyrenees is sensitive to changes in climate (both natural and of anthropic origin) and changes in land use and cover (LULC). These changes can influence the water resources. The historical evolution (1980–2013) of the stream flows are studied using observed time series from non-influenced gauging stations and two models (SASER and SWAT). Their comparison helps to detect and analyze changes in flow rates and their trends (trends are computed using the Sen's slope estimator, the significance of which was evaluated using the Mann-Kendall test). Furthermore, it also allows to explore the question of attribution (these models do not simulate LULC change). New hydrological insights for the region A complex and diverse domain such as the Pyrenees gives large differences between modelled trends revealing a large uncertainty that has been observed thanks to the use of two models. For the study period, mostly there are no significant trends. When trends are present in the observations and are also simulated, they are attributed to the effects of climate (natural variability and human induced climate change). When the significant trends observed are not simulated by the models, they are mainly attributed to changes in LULC. In general, models have difficulties detecting observed trends, leading to their attribution to changes in LULCs rather than climate, but there are some notable exceptions.This work was supported by the project EFA210/16/PIRAGUA co-founded by the European Regional Development Fund (ERDF) through the Interreg V Spain-France-Andorre Programme (POCTEFA 2014-2020) of the European Union.Peer reviewe

Improvement of low flows simulation in the SASER hydrological modeling chain

The physically-based, spatially-distributed hydrometeorological model SASER, which is based on the SURFEX LSM, is used to model the hydrological cycle in several domains in Spain and southern France. In this study, the modeled streamflows are validated in a domain centered on the Pyrenees mountain range and which includes all the surrounding river basins, including the Ebro and the Adour-Garonne, with a spatial resolution of 2.5 km. Low flows were found to be poorly simulated by the model. We present an improvement of the SASER modeling chain, which introduces a conceptual reservoir, to enhance the representation of the slow component (drainage) in the hydrological response. The reservoir introduces two new empirical parameters. First, the parameters of the conceptual reservoir model were determined on a catchment-by-catchment basis, calibrating against daily observed data from 53 hydrological stations representing near-natural conditions (local calibration). The results show, on the median value, an improvement (ΔKGE of 0.11) with respect to the reference simulation. Furthermore, the relative bias of two low-flow indices were calculated and reported a clear improvement. Secondly, a regionalization approach was used, which links physiographic information with reservoir parameters through linear equations. A genetic algorithm was used to optimize the equation coefficients through the median daily KGE. Cross-validation was used to test the regionalization approach. The median KGE improved from 0.60 (default simulation) to 0.67 (ΔKGE = 0.07) after regionalization and execution of the routing scheme, and 79 % of independent catchments showed improvement. The model with regionalized parameters had a performance, in KGE terms, very close to that of the model with locally calibrated parameters. The key benefit if the regionalization is that allow us to determine the new empirical parameter of the conceptual reservoir in basins where calibration is not possible (ungauged or human-influenced basins)