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Shark tooth
In one occasion, the calcarenite contained a tooth, which was later interpreted as most likely originating
from a shark (figure 4.5c). Because the sedimentary facies (scour infill, see later) of the sediment containing
this remain, the tooth could have been transported over significant distances.

4.2.3 Diagenesis

Diagenesis is defined as any chemical, physical or biological change that a sediment faces at elevated
temperature and pressure after it was deposited (Tucker & Wright, 1990). In carbonates, the two most
important diagenetical features are dissolution and cementation, mainly because they have huge impact
on the reservoir quality of such rocks. Figures 4.3e and 4.3f show typical parts of a thin section made from
the Favignana calcarenite. The cement is clearly visible, and analysis indicated that this is a syntaxial
rim type of cementation (X. Marquez, personal communication). It forms a rather small layer of constant
thickness around the grains. Syntaxial rim cement is typically created by marine processes, giving more
indications regarding the depositional environment. Cementation is not extensive, and did not clog pores
or pore throats. Because of the poor quality of the thin sections. they most likely do not represent the real
distribution of grains. However, it is not likely that cementation influences pore geometry significantly,
given the high porosity, grain size and small cement thickness.
Bioturbation is technically not a form of diagenesis, however since it involves sediment reworking as
well, so the phenomenon is introduced here. In figures 4.5e and 4.5f some burrows as observed in Cala
Azzurra are shown. This micro- and macrofacies analysis describes the bioturbation as a macrofacies
effect, therefore it will de discussed in more detail in the next section.

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