From ramp to platform: building a 3D model of depositional geometries and facies architectures in transitional carbonates in the Miocene, northern Sardinia

Abstract

The depositional geometry and facies distribution of an Early Miocene (Burdigalian) carbonate system in the Perfugas Basin (NW Sardinia) comprise a well-exposed example of a transition from a ramp to a steep-flanked platform. The carbonate succession (Sedini Limestone Unit) is composed of two depositional sequences separated by a major erosional unconformity. The lower (sequence 1) records a ramp dominated by heterozoan producers and the upper (sequence 2) is dominated by photozoan producers and displays a gradual steepening of the depositional profile into a steep-flanked platform. This paper shows the process of creating a digital outcrop model including a facies model. This process consists of combining field data sets, including 17 sedimentary logs, and a spatial dataset consisting of differential global positioning system data points measured along key stratigraphic surfaces and sedimentary logs, with the goal of locking traditional field observations into a 3D spatial model. Establishing a precise geometrical framework and visualizing the overall change in the platform geometry and the related vertical and lateral facies variations of the Sedini carbonate platform, allows us to better understand the sedimentary processes leading to the geometrical turn-over of the platform. Furthermore, a detailed facies modeling helps us to gain insight into the detailed depositional dynamics. The final model reproduces faithfully the depositional geometries observed in the outcrops and helps in understanding the relationships between facies and architectural framework at the basin scale. Moreover, it provides the basis to characterize semiquantitatively regional sedimentological features and to make further reservoir and subsurface analogue studies.

Capturing and modelling metre‐scale spatial facies heterogeneity in a Jurassic ramp setting (Central High Atlas, Morocco)

“…However, the combination of different GPS data sets, collected at different times or with different acquisition methods, may show an offset (vertical and/or horizontal) between one data set and another (Verwer et al. , 2007; Tomás et al. , 2010).…”

“…The last category mixes several modelling methodologies in their simulation workflow (Palermo et al. , 2010; Tomás et al. , 2010).…”

XI Ciclo de conferencias y seminarios, Doctorado en Geología : Curso 2018-2019

“…Diversos estudios en plataformas carbonatadas similares han puesto de manifiesto la compleja distribución que presentan las facies en este tipo de ambientes, consecuencia de la actuación de diversos procesos tanto internos como externos a la plataforma (e.g., Rankey, 2002;Strasser y Védrine, 2007). Asimismo, los componentes que definen un determinado cinturón de facies pueden variar lateralmente de manera significativa, e incluso desarrollarse mosaicos de facies en determinadas zonas de la plataforma (e.g., Bádenas et al, 2010;Tomás et al, 2010;Amour et al, 2013;San Miguel et al, 2017;Tomassetti et al, 2018). De cara a la obtención de modelos sedimentarios más precisos que reflejen el funcionamiento de estos sistemas carbonatados, el principal objetivo de este trabajo consiste en caracterizar en detalle la distribución de facies y evolución sedimentaria de las zonas someras de una rampa carbonatada de finales del Kimmeridgiense, representada en los materiales de la Fm.…”

Seismic characterization of switching platform geometries and dominant carbonate producers (Miocene, Las Negras, Spain)

“…Digital outcrop models (DOMs) help to better understand the geometries of complex carbonate depositional systems and their internal facies architecture (Bellian et al, 2005;Warrlich et al, 2005;Tom as et al, 2009;Verwer et al, 2009;Benson et al, 2014). Digital outcrop models can be integrated with field observations, laboratory data, high-detail photographs and GPS (global positioning system) data to create three-dimensional geological models.…”