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3 Methods

The fieldwork included several types of data collection. Because this project focuses on describing the
Favignana bioclastic sands from a reservoir point of view, a combination of stratigraphical sections and
samples have been used. The methods of data collection and data treatment will be described in this
section.

3.1 Stratigraphic description

East Favignana houses an extensive system of quarries, providing good outcrop quality. Some strati-
graphical sections provide excellent outcrop accessibility and a good potential to create stratigraphic logs.
Others are more remote or out of reach, and those have been evaluated by using photo panels.
The location of every pseudo-well is measured using a GPS device, which is usually horizontally accurate
to five metres. Because the GPS elevation is less accurate because of locally high quarry walls — in
the order of multiple metres off — elevation is extracted from a digital model of the Favignana surface.
This model was available in AutoCAD format, and was then converted to data readable by the Petrel
modelling software. The workflow used in this process is described in appendix E.2. Each section is
documented with photos, if possible including a large scale five metre long ruler. This device is also used
to keep track of thickness and depth.
The calcarenite deposits consist of a large variety of calcareous remains of living material. Very few
siliceous or clay-type minerals are present in the matrix. Texture depends on the type of skeletons and the
amount of reworking. The base of the Favignana system shows a major clay unit, differing considerably
in composition and texture. The amount of transport and the related energy determines the degree of
fragmentation. This has consequences for the grain size. Grain-size analysis is performed by examining
thin sections, however microscope magnifications are generally too high to capture a representative area
of such coarse-grained material. Instead of using a microscope, a standard mirror reflex camera with high
resolution was used in order to capture the entire thin section instead of only a small portion.
Sedimentary structures are a good indication of the processes that were active during deposition. The
structures observed in the quarries and outcrops on Favignana will be used to describe the conceptual

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