Geology Reference
In-Depth Information
5.1
The Geoheritage Tool-Kit Applied
to the AA to Identify Its Geological/
Geoheritage Essentials and to Assess
Their Significance
their scale, whether they are a geological ensemble or an
isolated feature, where the features is best developed for
geoconservation as a geopark, geosite, or SSSI, and rec-
ommended area for geoconservation and what type of
activity (strict geoconservation or geopark) is recommended
is presented in Table
1
. The key features of the geology of
the AA listed in Table
1
are ordered with respect to their age.
The grading of these essential geoheritage features with
respect to International, National and Regional signi
Morocco consists of a rich and diverse geology and geo-
heritage, however, an inventory in this regard is still in its
early stages, despite few localized attempts by research
groups from universities (El Hadi et al.
2011b
; Errami
2012
;
Errami et al.
2013a
). Numerous sites of outstanding geo-
heritage value are in need of preservation, e.g. speci
cance,
and the rationale for that assessment of these geological
features are also outlined in Table
1
. Because of their vari-
able size, the geological features, for purposes of geoheritage
and geoconservation, will be assigned either to geosites,
SSSI and/or to geoparks. Selected photos of geological
features are shown in Figs.
5
,
6
,
7
,
8
,
9
,
10
and
11
. Some
selected key features of the geology of the AA are described
in text form below.
c pal-
aeontological sites, notably those of the Palaeozoic of
southeast Morocco, such as in the Erfoud and Tazarine
areas, which are being over exploited either as ornamental
rocks or as rare specimens sold for private collections
(Errami et al.
2008
; El Hadi et al.
2011b
). These sites are at
risk of serious deterioration.
The key geological features of the Anti-Atlas are listed in
Table
1
and are important and distinctive to the region. We
have not included in this list geological features such as
Tertiary stratigraphy, Quaternary stratigraphy, arid-zone
landforms and other geomorphology, and active, modern
geological processes in the region, nor the wetlands. The
focus has been on Precambrian and Palaeozoic geology
involving their stratigraphy, stratigraphic relationships, tec-
tonism, magmatism, metamorphism, structural geology, and
the fossil and mineral content of the strata. Describing and
assessing the geoheritage of the younger strata and land-
forms are beyond the scope of this work. Morocco has
several type locations for lithostratigraphic sequences that
areof National and or international importance.
Due to its tectonic setting, Morocco has a globally distinct
and unique geology. Consequently, many of the mega-scale
features of geology of the AA stand in contrast to other geo-
logical and tectonic settings. These include the extensive and
well-preserved examples of plate-edge Precambrian rock
sequences (e.g., ophiolites), thick and well-preserved
sequences of Palaeozoic sedimentary sequences, and the tec-
tonic relationships between Precambrian rocks and younger
strata. This means that many of the mega-scale geological
features of the Anti-Atlas are globally unique and signi
5.1.1 Corridor of Precambrian Inliers
The Anti-Atlas contains a N
E trending corridor of Pre-
cambrian inliers (Fig.
5
b) surrounded by weakly-folded
Palaeozoic strata. It is an unusual structural array, and the
signi
-
cance of this corridor is that it preserves a style of
tectonics and folding existent in Palaeozoic times (and
probably founded on ancestral Precambrian structures), and
the contacts between Precambrian and Palaeozoic rocks, as
well as their contrasting tectonic, metamorphic, and struc-
tural history.
5.1.2 The Zenaga and Iguerda Inliers
The Zenaga Inlier and Iguerda Inlier occur within the
corridor of Precambrian inliers mentioned above and is a
well-exposed part of the corridor (Figs.
5
d and
6
). They
provide examples of the internal structure and lithology of
Precambrian inliers and their relationship to surrounding
Palaeozoic rocks. The Zenaga Inlier consists of granodi-
orites, syenogranites, and metamorphic rocks, with conju-
gate fractures and faults and ma
c dykes oriented north-
east, north-west, and east-west transecting the inlier (Ennih
et al.
2001b
). Zenaga is an example of a Palaeoproterozoic
inlier that has been subjected to Eburnean and Pan-African
orogenies and preserved didactic structural witnesses of
both orogenies. The main part of the Iguerda Inlier is
comprised of quartz diorites, granites, and metamorphic
rocks, with conjugate fractures and faults and ma
cant.
At the medium and smaller scales, because of the well-
preserved nature of the Palaeozoic strata in their tectonic
setting and in their expression in the present arid climate
setting, there is a plethora of biogenic and sedimentary
features, such as Palaeozoic carbonate mounds (weathered
out in relief) and biostromes, sedimentary (formational)
contacts such as unconformities, sedimentary structures, and
well-preserved fossils.
A description of the key aspects of these geoheritage
features, in terms of their geology, their signi
c dykes,
oriented north-east, north-west, and east-west transecting
the inlier (Fig.
5
d; El Aouli and Amaouain
2010
). There is
a strong structural control of
c dykes by the
fractures and faults. The margins of the inlier are sharply
and discordantly truncated by the surrounding Palaeozoic
rocks.
the ma
cance and
