El Kef, Conservatory of the Memory of Earth and Humans in Tunisia: A Geodiversity to Discover and a Heritage to Protect - From Geoheritage to Geoparks - page 131

3.2 Section of Hammam Mellegue Track: The

Cretaceous/Tertiary Boundary (G2, Fig. 2 )

This section was selected as a reference type section (Global
Stratotype Section and Point GSSP) for the Cretaceous-
Tertiary boundary (K/Pg) in the Tethyan region (Dalbiez
1956 ; Donze 1979 ; Keller 1988a , b ; Rocchia et al. 1992 ,
1995 ; Cowie et al. 1989 ). At the top of the upper member of
the Abiod Formation (Upper Campanian-Lower Maestrich-
tian), there is dark grey, brown laminated clay and marl with
a few thin intercalations of limestone in the lower and
middle parts. This section is the El Har a Formation

(Maestrichtian to Upper Paleocene). Marl deposits yield
microfauna of the Globotruncana falsostuarti and Aba-
thomphalus mayaroensis zone which indicates the upper-
most Maastrichtian. There are also some intercalations of
limestones with ammonites ( Desmophyllites sp.).
The exact boundary between the Cretaceous and Tertiary
(Fig. 3 ) corresponds to a millimetric thin layer of reddish
clay, rich in iron oxide and extraterrestrial materials (iridium
and nickel magnetites and spinels (Robin et al. 1998 ). This
layer records the effect of the great cosmic event that
occurred 65 Ma ago (Keller and Lindinger 1989 ). Experts
consider this section as the most comprehensive type section
across the Cretaceous-Tertiary boundary because it records
quiet and continued sedimentation in a deep marine envi-
ronment. The section shows the effect of a meteorite impact

í

Fig. 2 Inventory geosites in El Kef area (Tunisia)

Table 1 Chosen geosites
Geosites Interest of the site

Triassic formations of
Koudiat El Mrira

The oldest deposits of Mesozoic age in the
region

Hammam Mellege track
section

Showing reference type section (global
stratotype section and point GSSP) for
the Cretaceous-Tertiary (K/Pg)
boundary in the Tethyan region

Dyr El Kef An Eocene syncline

Lower Palaeolithic of
Sidi Zin

Archaeological and historical interest

Neolithic Sidi Mansour
caves

Archaeological and historical interest

Table of Jugurtha An Eocene syncline with historical

interest

Oued Mellegue dam Hydraulic reservoir, the rst dam in

Tunisia

Jebel Jerissa mine The most important area in mineral

exploitation in Tunisia

Myophoria goldfussi , Lopha montiscaprilis , Gervillea sp.
indicating a Ladinian and Carnian middle Triassic age
(Burollet and Sainfeld 1956 ). This site exposes the oldest
deposit (of Mesozoic age) in the region. It shows beautiful
cross-sections of Triassic formations packed in gypsum and
its contacts are rich in needles of black tourmaline and small
crystals of quartz.

Fig. 3 Cretaceous/Tertiary boundary at the Hammam Mellegue track
section