RECONSIDERATION OF THE LOWER CAMBRIAN EXTENSION IN … · (Ediacarian or NP3) and Paleozoic to the present day (Yazidi and al., 2016). Also, no tectonic unconformity separates the

http://www.iaeme.com/IJCIET/index.asp 910 [email protected]

International Journal of Civil Engineering and Technology (IJCIET)

Volume 10, Issue 05, May 2019, pp. 910-929, Article ID: IJCIET_10_05_092

Available online at http://www.iaeme.com/ijciet/issues.asp?JType=IJCIET&VType=10&IType=5

ISSN Print: 0976-6308 and ISSN Online: 0976-6316

© IAEME Publication

RECONSIDERATION OF THE LOWER

CAMBRIAN EXTENSION IN THE ANTI-ATLAS

BELT, MOROCCO

* Mohamed Yazidi, Khadija Kaid Rassou and Bouchra Razoki

Natural Resources Geosciences Laboratory (NRGL), Department of Geology, Faculty of

Sciences, Ibn Tofail University. Kenitra, Morocco

Geoscience and Geodidactics Team (GGT), Department of Life and Earth Sciences, Regional

Centre for Education and Training Professions (CRMEF Marrakech). Morocco

Fouad Benziane and Abdelaziz Yazidi

Laboratory of Geology; The National School of Mines of Rabat (ENIM), Rabat, Morocco

Saïd Chakiri, Zohra Bejjaji and Mohamed Allouza

Natural Resources Geosciences Laboratory (NRGL), Department of Geology, Faculty of

Sciences, Ibn Tofail University. Kenitra, Morocco

Hassan El Hadi

Laboratory of Applied Geology, Geomatics and Environment, Faculty of Sciences Ben

M‟Sik, University Hassan II, Casablanca, Morocco

Said Ettazarini

Laboratory of Remote sensing and geomatics. Multidisciplinary faculty Taza. University Sidi

Mohamed Ben Abdellah. Morocco

*Corresponding Author

ABSTRACT

The Anti-Atlas belt, which is located in the western part of the West African

Craton, is the result of Eburnean, Pan African and Variscan successive orogenies,

during the Paleoproterozoic, the Neoproterozoic and the Paleozoic. The subsequent

crustal accretions enlarged the craton, forming a series of belts in form of crowns.

In the Anti-Atlas, the Cambrian can be defined by paleontological or radiometric

dating. In the first case, the definition of its chronological lower limit can fluctuate

according to new results. In the second case, the intercalated volcanic levels are

younger and younger. In this study, we have grouped Adoudounian and Taliwinian in

a large lower Cambrian and not in any terminal Neoproterozoic.

The volcano-sedimentary and sedimentary formations of the Adoudounian and the

Taliwinian cover the Precambrian formations of the different domes.

Reconsideration of the Lower Cambrian Extension in the Anti-Atlas Belt, Morocco


Key words: Anti-Atlas, West African Craton, orogenies, lower Cambrian, Adoudounian and

Taliwinian.

Cite this Article: Mohamed Yazidi, Khadija Kaid Rassou, Bouchra Razoki, Fouad

Benziane, Abdelaziz Yazidi, Saïd Chakiri, Zohra Bejjaji, Mohamed Allouza, Hassan

El Hadi, Said Ettazarini, Reconsideration of the Lower Cambrian Extension in the

Anti-Atlas Belt, Morocco, International Journal of Civil Engineering and Technology

10(5), 2019, pp. 910-929.

http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=10&IType=5

1. INTRODUCTION

The interest of stratigraphic series of the Moroccan Anti-Atlas is very important for several

reasons. The most important is that outcrops are continuous and well exposed. Indeed, the

transition from the Upper Neoproterozoic to the Cambrian is still the subject of much debate

(Choubert and Faure-Muret 1962; Landing et al., 1998; Benziane, 2007; Alvaro et al., 2008,

Alvaro et al., 2014; Geyer and Landing, 2016; Yazidi et al 2016; Pouclet et al., 2018). Indeed,

the importance of stratigraphic series is essential for the understanding of the Neoproterozoic

- Lower Cambrian boundary. Many previous works have focused on the description and

characterization of the stratigraphic boundary separating Upper Ediacaran and Lower

Cambrian in the Anti-Atlas (Geyer and Landing, 1995, 2004 and 2006, Maloof et al., 2005

and 2010; Alvaro et al., 2014; Landing et al., 2018).

The present work aims at a revised description of the Lower Cambrian based on

geological mapping research data carried out in recent years in the Anti-Atlas (Yazidi et al.,

2002, 2008 and 2016; Benziane et al., 2002, 2007, 2008 and 2016; Harrison and al., 2008,

Walsh et al., 2002 and 2008), supplemented by data available in the literature such as those of

: Ducrot and Lancelot, 1977; Boudda et al., 1979; Bertrand-Sarfati, 1981; Benziane et al.,

1983, Destombes et al., 1985; Buggisch et al., 1988; Geyer; 1989, 1990a, b and 1995;

Soulaimani et al., 2003 and 2013; Gasquet et al., 2005; Soulaimani et al., 2014; Alvaro et al.,

2008 and Alvaro et al., 2014. The available dating data in Benziane et al., (2016) is also used

to discuss the redefinition of the "Lower Cambrian" subperiod and its extension.

2. GEOGRAPHIC CONTEXT

Numerous studies on the Anti-Atlas and more particularly those of Choubert (1963) and

Choubert and Faure-Muret (1970 and 1983) allow subdividing this region into three structural

domains (Choubert and al., 1980) (Figures 1 and 2):

The western part, which contains the Siroua, Tagragra of Tata and Ifni inliers;

The central part which includes the Bou Azzer, Zenaga and Siroua inliers;

The eastern part, which contains the Saghro and Ougnat inliers.

Meanwhile, according to Leblanc (1975), the Anti-Atlas is subdivided into two major

structural domains separated by the Major Fault of the Anti-Atlas (Figures 1 and 2):

An old (Eburnean) south-western domain;

A recent (pan-African) north-eastern domain.

The studies carried out in each field by numerous authors allow establishing chrono-

lithostratigraphic successions that may be different from one author to another. Therefore, the

correlation of formations by considering two or three domains in the Anti-Atlas becomes very

difficult.

Mohamed Yazidi, Khadija Kaid Rassou, Bouchra Razoki, Fouad Benziane, Abdelaziz Yazidi,

Saïd Chakiri, Zohra Bejjaji, Mohamed Allouza, Hassan El Hadi, Said Ettazarini


This study will present the Lower Cambrian series on the basis of subdivisions derived

from previous geological mapping work covering many areas of the Anti-Atlas (Benziane et

al., 2002, 2007, 2008 and 2016; Walsh et al., 2008 and Yazidi et al., 2002, 2008 and 2016).

Figure 1 General map of West African Craton. According to Dallmeyer and Lécorché (1991) cited in

Piqué (2001).

3. GEOLOGY OVERVIEW OF THE ANTI-ATLAS

The chain of the Anti-Atlas is located on the northern edge of West African Craton (figure 1).

Its general shape is a large anticline where the inliers constitute the heart. The Anti-Atlas

range covers an area of approximately 750 km long and 250 km wide, oriented SW-NE, from

the Atlantic Ocean in the west to Algeria in the east. The Anti-Atlas is limited to the north by

the major South Atlas fault (figure 2).

Figure 2 Schematic geological map of the Moroccan Anti-Atlas.



The Precambrian consists of Proterozoic rocks that crop out in inliers after erosion under a

Paleozoic cover. Paleozoic formations surround the Precambrian formations and correspond

to platform deposits in a shallow sea environment, in regular subsidence (Robert-Charrue,

2006). Their deformation during the Variscan Orogeny influenced the current shape of the

Anti-Atlas. The Paleozoic series are more than 10,000 m thick in the western Anti-Atlas, and

do not exceed 6,000 m in the eastern Anti-Atlas. They begin with platform carbonate deposits

of the Lower Cambrian (Boudda et al., 1979, Geyer and Landing, 1995).

The Paleozoic of the Anti-Atlas domain begins with lower Cambrian series lying with

concordance on the upper Ediacaran alkaline basalts and only separates them from an erosion

unconformity. Early Paleozoic cover rocks deposited in a shallow marine platform

environment.

The Cambrian formations crop out largely in the field. In this study, we will adopt on the

one hand the international stratigraphic scale for the terms and the chronological limits and on

the other hand the subdivision of the Anti-Atlas into three practical domains for the

understanding of the pan-African orogenesis.

In the Anti-Atlas, one distinguishes the outcroppings attributed to the Cambrian,

according to their palaeontological content, and those dated by the radiometric methods.

The "paleontological" Lower Cambrian begins with a new transgression with deposits of a

limestone and clay series where trilobites and Archaeocyata will proliferate;

The "radiometric" Cambrian where the interbedded volcanic levels in the sediments of the

Adoudou Formation gave radiometric ages between 532 ± 12 Ma (Pouclet et al., 2008) and

517 ± 1.5 Ma (Landing et al., 1998). The Cambrian cycle began at an age of less than 541.0 ±

1.0 Ma (Cohen et al., 2018).

4. LITHOSTRATIGRAPHIC EVOLUTION OF THE CAMBRIAN

BELOW THE ANTI-ATLAS

The geological history of the Anti-Atlas inliers began in the Paleoproterozoic and continued

during the Middle Neoproterozoic (Cryogenian or NP2) and Upper Neoproterozoic

(Ediacarian or NP3) and Paleozoic to the present day (Yazidi and al., 2016). Also, no tectonic

unconformity separates the lower Cambrian from the upper Ediacaran (Benziane et al., 2016).

Indeed, the main feature of the Anti-Atlas is the considerable development of lower

Cambrian limestones that can reach 5000 meters thick in the northwest of the Western Anti-

Atlas. These limestones crop out in the western Anti-Atlas and in the southern part of the

central Atlas (Choubert and Marçais, 1952). Lower Cambrian limestones of the Eastern Anti-

Atlas are less thick (figure 3).

These observations suggest that after the volcanic and plutonic phase of the Upper

Ediacaran (NP3s), the northern edge of the West African Craton performed as a passive

margin. A marine transgression from the NW in the Western Anti-Atlas deposited platform

formations, carbonates and silts.




Figure 3 Lower Cambrian deposits in the Anti-Atlas. According to Choubert, in Benziane and al.

(1983) and Cornea, 1989.

The Paleozoic volcano-sedimentary cover is conformable with the magmatic formations

of the Upper Ediacarian.

The first volcano-sedimentary and sedimentary formations of the Lower Cambrian are of

Adoudounian age (Choubert, 1952 classification). They cover the Precambrian formations of

the Anti-Atlas inliers. The absence of paleontological witnesses in the Adoudou Formation

allows us to attribute it to an early Cambrian or Infracambrian Cambrian (Yazidi et al., 2007).

We will start the "palaeontological" Cambrian with the Taliwine Formation and the

Cambrian "radiometric" with the Adoudounian as confirm the radiometric ages obtained in

the Bou Azzer inlier (Benziane et al., 2007) on the interbedded volcanic rocks (Figure 4).

Also, according to our different recent studies (Yazidi et al., 2016, Benziane et al., 2016) on

the Anti-Atlas area, we have gathered the formations from the Adoudounian to the ultimate

sandstone series (“Grès Terminaux”) in lower Cambrian (sl).

Figure 4 Northern border of the Bou Azzer inlier: the dark horizons correspond to trachytes in

interbedded flows in the adoudounian dolomites.



The Paleozoic sedimentary cycle begins in the Lower Cambrian (s.l.). The latter includes

the Taroudant Group (Adoudou Formation and Taliwine Formation) followed by the Tata or

Lower Cambrian Group, in the strict sense of the term (s.s.). Thus, the formations of the

lower Cambrian (s.l.) ranging from the Adoudounian to the paleontological Cambrian,

constitute the cover of the Precambrian formations of the different inliers of the Anti-Atlas.

4.1. Taroudant Group (Figure 5)

At the end of the magmatic cycle (ultimate Proterozoic), a subsidence of the pan-African

margin leads to widespread floods. The marine transgression begins in the Anti-Atlas by the

Group of Taroudant. The latter consists of the Adoudou and Taliwine Formations. This pan-

African cover sequence is dominated mainly by carbonate rocks. It lies on the volcanic and

volcano-detrital rocks NP3s (Ediacaran) through the Adoudou Formation. Only the

easternmost part of the Anti-Atlas emerged, the sea invaded this part of Anti-Atlas in the

Middle Cambrian, depositing Paradoxides sandstones and siltstones (Robert-Charrue, 2006).

The Taroudant Group has been of particular interest to many researchers. The oldest

works are those of Choubert (1952) and Hupé (1952). They assumed that the Precambrian-

Cambrian boundary is located there.

In some areas of the Anti-Atlas, the transition from one formation to another is

progressive which makes their distinction on the field very difficult especially in the cover of

Ifni inlier, unlike the eastern part of Kerdous inlier where the terranes of the two formations

are very different.

Lithofacies associations are very interesting in the Taroudant group. The first deposits are

those of the Adoudou Formation, developed on a shallow carbonate platform. The deposits

above form the Taliwinian Formation (“Série Lie de Vin”), consisting mainly of carbonate

schists.

Figure 5 Aït Sbouya. Log of Taroudant Group (Ifni inlier).




4.1.1. The Adoudou Formation (Figure 5)

At the end of the Ediacaran time, a transgression from the Northwest, first invaded the

Western Anti-Atlas and progressed eastward to reach an area between Ouarzazate and

Tazzarine (Benziane et al., 2002). The transgression began in the Anti-Atlas by the deposit of

the Adoudou Formation, relative to Oued Adoudou in the Western Anti-Atlas. According to

Choubert (1952), this Formation includes the "Basal Series" (“Série de Base”) and the "Lower

Limestones" (“Calcaires Inférieurs”).

According to the work of Blein et al., (2013), the Adoudou Formation is the most basal

lithostratigraphic unit of the Late Neoproterozoic-Lower Cambrian cycle. It unconformably

overlies the continental volcano-sedimentary rocks of the Ouarzazate Group. This formation

fossilizes a phase of uplift and erosion recorded at the end of the volcano-sedimentary episode

of Ediacaran or "Precambrian III" or Ouarzazate Group.

Our recent mapping work in the Anti-Atlas (Yazidi et al., 2016, Benziane et al., 2016) has

defined the main series of the Adoudounian formation. At the base the conglomeratic lower

limb (ЄiAd1c) and detrital member corresponding to "the Basal Series of Adoudounian"

(ЄiAd1). The two members are only separated by an erosion unconformity. Above comes the

Adoudou Formation s.s. (ЄiAd2), composed of the member of Tamjout or "Dolomite of

Tamjout" (ЄiAd2a) and the upper limb or "Lower Limestones" (ЄiAd2b).

4.1.1.1. Lower limb or “Basal Series” of the Adoudou Formation (ЄiAd1c)

At the end of the Ediacaran magmatic cycle, the deposit of the Adoudou Formation began, no

tectonic unconfirmity separates it from the upper Ediacaran (Figure 6). These sedimentary

layers are the result of a transgression in the Anti-Atlas. It is the Conglomerate of the base of

the Adoudou Formation (ЄiAd1c). This conglomerate was deposited in channels, hence its

discontinuity under the “Basal Series” at the edge of the Ifni inlier (south of Ait Sbouya)

(Figure 7).

Figure 6 Mirleft. Log of formation (Ifni inlier).



Figure 7 Ait Sbouya - South Moulkinz. View showing: intercalation of ЄiAd1c between basalts of

Ediacarien and ЄiAd1 formations.

4.1.1.2. “Basal Series” of the Adoudou Formation (ЄiAd1)

It is a detrital sedimentation that starts with siltstone deposits and pink to white marl with

interbedded sandstone. The sandstone facies gradually appears and characterizes the higher

levels of the series.

4.1.1.3. Member of Tamjout or Dolomite of Tamjout (ЄiAd2a)

After the terrigenous character of the “Basal Series”, the Adoudounian sedimentation (ЄiAd2)

is predominantly dolomitic. It began with a shallow detrital deposit then, it became dolomitic.

These dolomitic deposits are to thick beds, white color and to layers of chert or flint, it is the

“Dolomite of Tamjout”. These dolomites constitute the wall of the upper limb corresponding

to the "Lower Limestones" (“Calcaires Inférieurs”).

4.1.1.4. Upper limb or ''Lower Limestones'' (ЄiAd2b)

The “Lower Limestones” consist, from the bottom to the top, of gray-blue dolomites with

clay-silty joints followed by pink dolomitic limestones with interbedded light marl. Dolomite

often has laminites and stromatolites. Ashes and volcanic flows are interbedded locally in the

Adoudou dolomites. They were discovered in the Bou-Azzer inlier (Figure 4). The source of

these ashes is spectacularly preserved under the name of "Volcano of Alougoum" in the

eastern massif of El Graara (Choubert, 1952; Choubert et al., 1980, Boudda et al., 1979).

These volcanic events correspond to reorganizations of the basins (Geyer and Landing, 2006).

4.1.2. The Taliwine Formation

A regression of the sea began at the upper Adoudounian. It allows the deposit of sandstones

and purplish siltstones between Kerdous and Ouarzazate. These formations are awarded to the

Taliwinian ("Série Lie-de-vin"). The naming "Série Lie-de-Vin" (Choubert, 1942) refers to

the typical purple or burgundy color of shales in the unit and not to a geographical section.

This formation was defined by Choubert (1952) in the Tata zone and named "Taliwinian".

However, the sea persisted in the Ifni zone (Western Anti-Atlas) where marine carbonate

deposits continued. This situation explains the lateral variation of the Facies of the Taliwin

Formation essentially formed of three parts (Figure 8): the lower Taliwinian (ЄiTw1), the

middle Taliwinian (ЄiTw2) and the upper Taliwinian (ЄiTw3). The lower and upper

Taliwinian deposits are volcano-detrital in nature, while the Middle Taliwinian is

characterized by massive beds of dolomite and commonly known as “Tata Bar” (“Barre de

Tata”).




Figure 8 Tata inlier. Section in the right bank of Oued Tata. Ad2: Adoudounian, Ki1: Lower

Cambrian (Єi1), Tw1, Tw2 and Tw3: Taliwinian.

From west to east, the main lithological variations observed in the Taliwine Formation

are:

In the west, the "Série Lie-de-Vin" is of marine facies. This is the case in the eastern and

southern border of the Ifni inlier, where it is represented by dolomitic limestones with white

marly interbeds. The thickness of the "Série Lie-de-Vin" can reach 600 m. The marine facies

gradually changes to continental or lagoon facies;

In the east, it is composed of sandstone and pink to red shales, sometimes green where is

inserted a dolomite bed, the "Bar of Tata";

Much further east and northeast (Eastern Anti-Atlas), it is impossible to separate the Middle

Taliwinian from the Upper Taliwinian (ЄiTw2-3) where the Tata Bar disappears. They only

remain there sandstones with red clay joints. The Upper-Middle Taliwinian (ЄiTw2-3) is thus

called: "Tikirt Sandstone" or "Tikirt Formation" (Figure 9) (Gentil, 1912, Benziane and

Yazidi, 1982; Yazidi et al., 2008, Walsh et al., 2008).

Figure 9 Saghro inlier. Cliff of the Tikirt sandstone (ЄTw2-3) above the Zouzmitane granite.



The boundary between the Taliwine Formation and the "Lower Limestones" at the top of

the Adoudou Formation is difficult to distinguish in the field due to the continuity of

dolomitic and marly deposits. But, on satellite imagery, the two formations can be

distinguished by different tones.

The distribution of trilobites (Huppé, 1952) allowed the first biostratigraphic subdivisions

of the Lower Cambrian. Following recent paleontological discoveries (Sdzuy, 1978; Schmitt,

1978; Debrenne, 1978; Monninger, 1979; Sdzuy and Geyer, 1988; Geyer, 1990), the

Precambrian-Cambrian boundary is located within the Tata dolomitic bar or Middle

Taliwinian (ЄiTw2). The upper part of the formation in the Western Anti-Atlas has complex

metazoal traces such as Diplocraterion (Latham and Riding, 1990), which are best interpreted

as indicating a Cambrian age. The transgressive sequence was attributed to the ultimate

Proterozoic (Blein et al., 2013).

4.2. Tata Group or lower Cambrian (s.s.) (Figure 10)

The Tata Group (Geyer, 1989) corresponds to the so-called "palaeontological" Cambrian

inferior or lower Cambrian (s.s.). It was deposited following a new transgression larger than

the first Adoudounian. It is a limestone and clay series where trilobites and Archaeocyaths

will proliferate.

The outcrops of the Tata Group cover large areas and are visible in the well developed

sections of the Western Anti-Atlas. Only the easternmost part of the Anti-Atlas remains

emerged, it is invaded by the sea only in Middle Cambrian.

Figure 10 Stratigraphic log of the Lower Cambrian of Assaka (Ifni inlier).




The transgression to the Lower Cambrian (s.s.) gradually invaded the Anti-Atlas towards

the east and south with some emersions giving deposits of conglomerates to the Ordovician

and Devonian (Robert-Charrue, 2006).

The transition from the Taliwine Formation to the Tata Group is as progressive as the

passage from the Adoudou Formation to that of Taliwine.

The Lower Cambrian type series includes, according to Boudda et al. (1979) "Upper

limestones", "Schisto-limestone series", "Shale series" and "Terminal sandstone".

For this study, the Tata Group corresponds to the succession formed by: the "Igoudine"

Formation or the "Upper Limestones" (Єi1), the "Amouslek" Clay and Carbonate Formation

(Єi2), the "Issafene" Formation schist (Єi3) and the Formation of "Asrir" corresponding to

"Terminal Sandstone" (Єi4).

4.2.1. Igoudine Formation or "Upper limestones" (Calcaires Supérieurs )

The Tata Group begins with an essentially carbonate series called "Upper limestones"

(“Calcaires Supérieurs ») (Choubert, 1952, Boudda et al., 1979) and noted (Єi1). This is the

Igoudine Formation (Geyer, 1989 and 1990). This Formation consists of two members: the

Lower Member (Єi1a) and the Upper Member (Єi1b). In fact, the Tata Group begins with

dolomitic limestones lying in semi-metric and marly-wedge beds or clayey limestones (Єi1a).

The thickness varies regionally and reaches about 300m in the Ifni inlier. Detrital sandstone to

microconglomerate levels slipped in between. Then come deposits of well-defined whitish

dolomitic limestones (Єi1b) (30 to 50 m). The Igoudine Formation shows through the Anti-

Atlas a lateral variation of facies and thickness.

To the east, sandstone and clay occur between the dolomitic limestone beds, and in the

extreme east the detrital facies dominate. The thickness of the Igoudine Formation can reach

500 to 600 m to the west. On the other hand in the east, it is only 75m and disappears to the

east of Saghro.

The Igoudine Formation was deposited under shallow marine conditions. Among the

trilobite and archaeocyath a fauna found in these limestones (Schmitt and Monninger, 1977 ;

Sdzuy et al., 1988), mention may be made of Eofallotaspis, Hupetina, Bigotina, Afiacyathus,

Coscinocyathus, etc.

4.2.2. Amouslek Formation

The Amouslek Formation (Єi2) is known as "Série Schisto-limestone" described by Choubert

(1952), then named Amouslek Formation (Geyer, 1989 and 1990). The unit is widespread in

the Anti-Atlas and extends about 220 m thick in the Amouslek section about 40 m south of

Jbel Kissane. The transition from Igoudine to the Amouslek Formation is a sudden change

from massive carbonates to shale / slate-carbonate. In this study, four members make up the

Amouslek Formation:

The first member is called Member of Timoulay Oufella (Єi2a). It corresponds to massive

limestones in white metric beds. Fossiliferous levels to Archaeocyatha characterize the

Formation.

The second member is Member of Timoulay Isder (Єi2b) with more marlish facies.

Decimetric to metric beds of white limestone and marl alternate. Reddish or greenish gray

nodular limestones with marly interbeds characterize the top of this member.

The third member (Єi2c) consists of massive limestones in amalgamated metric beds, with

rare marly joints. The limestones are of varied color: bluish black, gray or white and contain

Archaeocyathidae.

The fourth member (Єi2d) outcrops in the Ifni inlier. Outcrops are located at "Foum Fast" on

both banks of N'Fast wadi (Ait Sbouya sheet). Other outcrops are located on the banks of



Oued Arksis downstream (Assaka sheet). This member is represented by massive dark cloddy

limestones and interbedded shaly marl. The Єi2d generally constitutes the last reliefs that

envelop the Ifni inlier to the east and south.

The Amouslek Formation is about 200 m thick. Shaly levels provided trilobite fauna

(Hupé 1952 and 1953; Geyer, 1996). Abundant shellfish fossils are generally indicative of

Fallotaspididae (Fallotaspis, Choubertella, Daguinaspis) and Neoredlichiidae (eg, Resserops,

Marsaisia). Stromatolites and horizons to low amount of cyanobactéria are present in the

upper carbonated half cycle in many places and have been discussed at Jbel Kissane

(Buggisch et al., 1978).

4.2.3. Formation of Issafene or "Shale series" («Série Schisteuse )

The Issafene Formation (Geyer, 1989) corresponds to Choubert's « Série Schisteuse » (Єi3)

(1952). In the Issafene section type, this Formation consists essentially in shales and easily

recognizable in the landscape by its purplish color. In some areas, shales load in floated micas

and their thickness decrease. Their color is green and they are soft or fairly resistant in the

presence of volcanic material. The thickness of the Formation is about 400m around

Timdghas (Jebel Saghro). The thickness varies in Tata between 150m in the west and 75m in

the east, but it is reduced to 50m in Bou-Azzer area. This Formation can also be characterized

by "scoriaceous limestones", such as those observed in the cover of Ifni's inlier. These

scoriaceous limestones have been interpreted as diagenetically altered layers of volcaniclastic

sediments and fine-grained volcanoclastic sediments and calcareous interlayers (De Koning,

1957; Hupé, 1959).

The paleontological studies of this Formation are very old. In fact, the first recorded

African archeocenes were discovered in 1925 in massive bluish limestones of the Sidi Moussa

d'Aglou Formation (Bourcart, 1927). Boudda et al. (1979) defined Issafenian by its

archaeocyathic bioherms. The archeoliths of the Issafen Formation have been studied by.

Debrenne et al., (1975 and 1992).

4.2.4. Formation of Asrir or "Ultimate Sandstones" (Grès Terminaux )

The Asrir Formation is formerly called « Grès Terminaux » by Choubert (1942 and 1952),

then the Asrir Formation by the same author (1963) and taken over by Hollard (in Destombes

and al., 1985). For Geyer (1989a and 1990b) it is the Tazlaft Formation. For Landing (2006),

the Tazlaft Formation is traditionally assigned to the top of the Asrir Formation, and is

therefore only the lower part of the "Ultimate Sandstones" (Landing et al., 2006).

The Asrir Formation (Єi4) appears gradually over the Issafene Formation. It is

characterized by sandstone deposit. In the section type of Asrir, it is an alternation of

sandstone and shale whose thickness reaches 300 to 400m. Elsewhere, it is mostly sandstone

with intercalations of conglomerates and fine shaly beds, but the thickness does not exceed

100m. The trilobite fauna found in the levels of the Asrir Formation contains: Myopsolenus

[magnus] (Hupé 1953) and Gentilaspis (Hupé 1960).

This Formation outcrops almost continuously on the eastern and southern slopes of

Saghro. In the Western Anti-Atlas (Palaeozoic cover of Ifni's inlier), the Formations of

Issafene and Asrir consist both of terrigenous deposits and it is difficult to distinguish

between them. Both of them are grouped under the name of the Asrir-Issafene Formation

(Єi3-4), consisting of sandstones and siltstones, dark green to red color and containing

volcanic elements. The sandstone layers are decimetric to metric thick with silty joints and

interbeds. The siltstones are thin-bedded and micaceous and sometimes show intercalated

sandstone layers. Sometimes layers of coarse sandstone are intercalated in the siltstones. The

siltites show an alternation of predominantly clay beds and predominantly sandstone beds.




The Formation of “Ultimate Sandstones” marks the end of the lower Cambrian cycle of

the Anti-Atlas.

5. GEOCHRONOLOGY OF EVENTS IN LOWER CAMBRIAN

The base of the Early Cambrian begins with the deposition of the Taroudant and Tata Groups

in conformity with the Precambrian rocks. The passage is marked only by a simple erosion

unconformity. The peritidal sedimentation, which shows the formations of Adoudou and

Taliwine, testifies to a beginning of opening which evolves towards the installation of a sea in

which proliferate trilobites and archaeocyatha. These are found in the deposits of the

Formations of Igoudine, Amouslek, Issafene and Asrir. The reef carbonate sedimentation also

testifies to a phase of global warming succeeding the Precambrian glaciation phase. In fact,

diamictites described in different regions of the Anti-Atlas have been interpreted as glaciation

witnesses (Vernhet et al., 2012, Letsch et al., 2018), two phases worth to be distinct.

The ancient dating of the Cambrian series concerns the lavas of Jbel Boho (Choubert,

1952, Boudda et al., 1979; Leblanc, 1973, 1975; Alvaro et al., 2006). These lavas are

intercalated in the "Lower Limestones". They were dated at 534 ± 10 Ma (Leblanc and

Lancelot, 1980). Among the ancient paleontological dating, we can mention the

paleontological discoveries of Buggisch and Flügel (1986) in the "Lower Limestones"

Recent stratigraphic and geochronological studies on the Anti-Atlas place the beginning of

the Adoudounian transgression around 545 Ma and place the upper age limit of this

transgression at 525-531 Ma (Gasquet et al., 2005, Maloof et al., 2005, Yazidi et al., 2016).

These age limits are based on dating volcanic flows in the dolomitic formations of

Adoudounian.

In the Bou-Azzer inlier, the trachytes of Aghbar have been dated to 531 ± 5 Ma by

Gasquet et al. (2005). While the Jebel Boho syenites are dated at 534 ± 10 Ma (Ducrot and

Lancelot, 1977). The syenite age is later recalculated to 529 ± 3 Ma (Gasquet et al., 2005).

We consider that the deposits in which the volcanic rocks are intercalated attest of an

extensive context (Figure 4).

The date of 534 ± 10 Ma on the Lower Adoudou Formation and revised interpretations of

chemostratigraphic data (Maloof et al., 2005) suggest that almost the entire Taroudant group

is Lower Cambrian.

Other datings (Yazidi et al., 2016 a, b) were made on the lower Cambrian formations of

the Ifni area. On the Talata Al Akhçaç Sheet, the detrital zircons of the Adounounian

sandstones (ЄiAd1) give an average age of less than 554 ± 3 Ma. On the Assaka sheet, the

sandstones of the Asrir-Issafene Formation (Єi3-4) dating of detrital zircons have yielded

minimum ages for the lower Cambrian 555 ± 8 Ma. The age of deposition of these units

containing reworked elements is decidedly newer.

Isotopic analyzes performed on volcanic tuffs and intercalations in Adoudounian and

Taliwinian (Ducrot and Lancelot, 1977; Compston et al., 1992; Landing et al., 1998; Gasquet

et al., 2005; Pouclet et al., 2008 ; Maloof et al., 2010) are of great importance. They confirm

our results on the study of the Lower Cambrian in the Anti-Atlas.

All these arguments confirm that it is from the Adoudounian and during the lower

Cambrian, the progressive occupation of the Anti-Atlas by the sea from the northwest took

place. This is an initial opening period. In addition, the formation of this basin was

accompanied by volcanic activities on its periphery and by a global warming favoring reef

carbonate sedimentation (Algouti et al. 2002).

The figure 11 represents a recapitulation of the correlations of the different parts of the

Lower Cambrian cover over the Precambrian formations of the Anti-Atlas. We have grouped



Adoudounian and Taliwinian into a lower Cambrian in the broad sense and not in any

terminal Neoproterozoic.

Figure 11 Summary Table and Correlation of Lower Cambrian Coverage Area.




6. CONCLUSION

In conclusion, the stratigraphic interest of the Anti-Atlas is confirmed by these large

lithostratigraphic successions of the Paleozoic series. It is a sedimentary basin deposited in a

platform environment. Further, palaeontological and radiometric arguments suggest that the

Lower Cambrian is a period of progressive marine transgression on the Anti-Atlas from the

northwest. The evolution of this epicontinental basin has been a result of transgressive and

regressive fluctuations.

The lower Paleozoic forms the cover of the anti-atlasic Precambrian inliers during a

"rifting" phase. This allowed the transgression of the Taroudant Group and the Tata Group of

the Lower Cambrian. During the initial opening (Adoudounian), the formation of this basin

was accompanied by volcanic activities on its periphery.

The events that took place during the Adoudounian and the Taliwinian are part of the

same geodynamic process of continuous opening that is proposed to be attributed to the lower

Cambrian in the broad sense (s.l.) and not in any terminal or ultimate Neoproterozoic.

REFERENCES

[1] Algouti Ab., Algouti Ah., Chbani B. Etzaimz M. (2002) - Sédimentation et volcanisme

synsédimentaire de la série de base de l‟adoudounien infra-cambrien à travers deux

exemples de I‟Anti-Atlas du Maroc. Journal of African Earth Scrences. Vol. 32, NO. 4,

PP. 541-556.

[2] Álvaro, J. J. & Clausen, S. (2006). Processus de condensation dans les bioaccumulations

cambriennes de la Brèche à Micmacca, Atlas marocain. In: Réunion Spécialisée de la

Société Géologique de France, « Histoire et dynamique des plates-formes cabonatées et de

leurs biotas durant les Phanérozoïque », 18 & 19 Mai 2006, Livret des Résumes des

communications scientifiques, Université de Provence: 7; Marseilles.

[3] Alvaro, J. J., Clausen, S. (2008) - Paleoenvironmental significance of Cambrian hiatal

shell accumulations in an aborted intra-cratonic rift, Atlas Mountains, Morocco. In: Pratt,

B.R., Holmden, C. (Eds.), Dynamics of Epeiric Seas. Geol. Ass. Canada, Spec. Pap. 48,

pp. 39–54.

[4] Alvaro, J. J., Benziane F., Thomas R., Walsh G. Yazidi A. (2014) - Neoproterozoic–

Cambrian stratigraphic framework of the Anti-Atlas and Ouzellagh promontory (High

Atlas), Morocco. Journal of African Earth Sciences · October 2014.

[5] Benziane F., Prost A.E., Yazidi A. (1983) - Le passage du Précambrien au Cambrien

précoce volcanique et sédimentaire de l‟Anti-Atlas oriental ; comparaisons avec l‟Anti-

Atlas occidental. Bull. Soc. Géol. France 4, 549-556.

[6] Benziane, F., Yazidi, A., Walsh, G.J., Armstrong, T.R., Kouhen, M.A., Yazidi, M., El

Khamlichi, M.A., Aleinikoff, J.M. (2002) - Carte géologique du Maroc au 1/50 000,

feuille Afouzar. Notes et Mém. Serv. Géol. n° 422 bis, 1–72.

[7] Benziane, F. (2007) - Lithostratigraphie et évolution géodynamique de l‟Anti-Atlas

(Maroc) du Paléoprotérozoïque au Néoprotérozoïque: exemples de la boutonnière de

Tagragra de Tata et du Jbel Saghro. PhD. Univ. Savoie, France.

[8] Benziane F., Yazidi A., Yazidi M ; Saadane A., Walsh J.C. (2008) - Carte géologique du

Maroc, feuille au 1/50 000 QAL‟AT MGOUNA. Notes et Mémoires du Service

Géologique du Maroc n° 468.

[9] Benziane, F., Yazidi, A., Saadane, A., Yazidi, M., El Fahssi, A., Stone, B.D., Walsh, G.J.,

Burton, W.C., Aleinikoff, J.N., Ejjaouani, H., Kalai, M. (2008) - Carte géologique au1/50

000, Feuille Qal‟at Mgouna. Notes et Mémoires du Service Géologique du Maroc n° 468,

1–139.



[10] Benziane F., Yazidi A., Schulte B., Boger S., Stockhammer S., Lehmann A., Saadane A.,

Yazidi M. (2016) - Carte géologique du Maroc, feuille au 1/50 000 Tlata Al Akhçaç.

Notes et Mém. Serv. Géol. Maroc- Rabat n° 543bis.

[11] Bertrand-Sarfati, J. (1981) - Problème de la limite Précambrien –Cambrien: la section de

Tiout (Maroc); les stromatolites et leur biostratigraphie (Schmitt, 1979): critiques et

observations. Newsl. Stratigr. 10, 20–26.

[12] Blein O., Razin P., Baudin T., Chevermont P., Gasquet D., Soulaimani A., Admou H.,

Youbi N., Bouabdelli M., Anzar C. (2013) - Notice de la carte géologique du Maroc au

1/50 000 feuille Alougoum. Notes et mémoires du service géologique n°534 bis.

[13] Boudda A. Choubert G., Faure–Muret A. (1979) - Essai de stratigraphie de la couverture

sédimentaire de l‟Anti-Atlas : Adoudounien – Cambrien inferieur. Notes et Mém. Serv.

Géol. Maroc, N°271.

[14] Bourcart, J. (1927). Découverte du Cambrien à Archaeocyathus dans l‟Anti-Atlas

marocain. Comptes Rendus sommaire, Société géologique de France 1927 (1-2): 10–11,

Paris.

[15] Buggisch, W., Marzela C. & Hügel, P. (1978). Die fazielle und paläogeographische

Entwicklung der infrakambrischen bis ordovizischen Sedimente im Mittleren Antiatlas um

Agdz (S-Marokko). Geologische Rundschau 68 (1): 195–224, Stutt-gart.

[16] Buggisch W. & Flügel E. (1986). The Precambrian/Cambrian boundary in the Anti-Atlas

(Morocco). Discussion and new results. In: V. .JACOBSHAGEN Ed., The atlas system

of Morocco , Springer-Ver-lag, 81-90.

[17] Buggisch, W., Flugel, E. (1988) - The Precambrian/Cambrian boundary in the Anti-Atlas

(Morocco). Discussions and new results. In: Jacobshagen, V.H. (Ed.), The Atlas System

of Morocco. Studies on its Geodynamic Evolution. Lect. Not. Earth Sci. 15, pp. 81–90.

[18] Choubert G. (1942) - Signification tectonique du seuil du Siroua et du bloc oriental du

massif central du Haut-Atlas: Bulletin de la Société des Sciences Naturelles du Maroc, 22,

pp. 126-136.

[19] Choubert G. 1952. Histoire géologique du domaine de l‟AntiAtlas. Notes et Mém. Serv.

géol. Maroc, 100, 77 p.

[20] Choubert G., Marçais J. (1952) - Aperçu structural In: Géologie du Maroc Notes et Mém.

Serv. Géol. Maroc, 100, fasc 1, partie 1 –et : 19ème Congr. Géol. Int, Alger 1952, Monogr

région, 3ème série Maroc, 6, pp 9 – 73.

[21] Choubert, G., Faure Muret, A. (1962) - Evolution du domaine atlasique marocain depuis

les temps paléozoïques, Livre à la mémoire du Professeur Paul Fallot. Société géologique

de France, Paris, pp. 447-527.

[22] Choubert G. (1963) - Histoire Géologique du Précambrien de l'Anti-Atlas. Notes et Mém.

Serv. Géol. Maroc, N°162, 352p.

[23] Choubert G., Faure Muret A. (1970) - Colloque international sur les corrélations du

Précambrien, Agadir-Rabat, 3-23 mai 1970 et livret guide de l‟excursion : Anti-Atlas

occidental et central. Notes et Mém. Serv. Géol. Maroc. 229, 259p.

[24] Choubert, G., Destombes, J., Gauthier, H., Hindermeyer, J. (1980) - Carte géologique du

Maroc, feuille Jbel Saghro-Dadès (Haut Atlas central, sillon Sud-Atlasique et Anti-Atlas

oriental) au 1/200 000ème.

[25] Choubert G., Faure-Muret, A. (1983) - Anti-Atlas. In: Fabre, J. (Ed.), Afrique de l‟Ouest.

Introduction géologique et termes stratigraphiques. Pergamon, Oxford, pp. 80– 95.

[26] Cohen K.M., Finneys C., Gibbard P.L. (2018) - International Commission on

Stratigraphy.




[27] Compston W., Williams I.S., Kirshvink J.L, Zhichao, Zhang, Guogan, Ma. (1992): Zircon

U–Pb ages from the Early Cambrian timescale. J. Géol. Soc. London, 149, 171-184.

[28] Cornée A. (1989).- Communautés benthiques à cyanobactéries des milieux hypersales :

Intérêt Géologique. Bull. Soc. Bot. Fr., 136, Actual. Bot., (1), p. 131-145.

[29] Dallmeyer, R.D., Lecorche, J.P. (EDS.) (1991) - The West African Orogens and Circum-

Atlantic Correlatives. IGCP Projet233.ix+405pp.

[30] Debrenne, F. et Debrenne, M. (1975). Age des premières et dernières faunes

d‟Archaeocyates du Cambrien inférieur du Maroc. Réunion de la Groupe Trav. Limite

Précambrien - Cambrien, Maroc, 23. Ok t.–2. Nov. 1975, 7 p., Rabat.

[31] Debrenne, F. et Debrenne, M. (1978). Archaeocyathid fauna of the lowest fossiliferous

levels of Tiout (Lower Cambrian –Southern Morocco). Geological Magazine 115 (2):

1101–119, London.

[32] Debrenne, F., Debrenne, M. & Faure-Muret A. (1992). Faune d‟Archéocyathes de l‟Anti-

Atlas occidental (bordures Nord et Sud) et du Haut Atlas occidental. Cambrien inférieur,

Maroc. Géologie Méditerranéenne XVII [for 1990] (3-4): 177–211, Aix-en-Provence.

[33] Destombes, J., Hollard, H., Willefert, S. (1985) - Lower Palaeozoic rocks of Morocco. In:

Holland, C.H. (Ed.), Lower Palaeozoic Rocks of the World. Lower Palaeozoic of North-

Western and West Central Africa, vol. 4. John Wiley and Sons, Chichester, pp. 57–184.

[34] De Koning, G. (1957). Géologie des Ida ou Zal (Maroc). Stratigraphie, pétrographie et

tectonique de la partie SW du bloc occidental du Massif ancien du Haut Atlas. Ph. D.

dissertation, Univ. Leiden, 209 p., Leiden.

[35] Ducrot J., Lancelot J. R. (1977) - Problème de la limite Précambrien-Cambrien : Etude

radiochronologique par la méthode U-Pb sur zircons du volcan du Jbel Boho (Anti-Atlas

marocain). Can. J. Earth. Sci. 14, p. 2771-3777.

[36] Gasquet D., Levresse G., Cheilletz A., Azizi Samir M.R., Mouttaqi A. (2005) -

Contribution to the geodynamic reconstitution of the Anti6atlas (Morocco) during

Panafrican times with the emphasis on inversion tectonics and metallogenic activity at the

Precambrian-Cambrian transition. Precambrian researth 2587 1-26.

[37] Gentil, L. (1912). Le Maroc physique. Paris, librairie f. Alcan, 313 pp., cartes.

[38] Geyer, G., (1989) - Late Precambrian to early Middle Cambrian lithostratigraphy of

southern Morocco. Beringeria 1, 115–143.

[39] Geyer, G. (1990 a) - Proposal of formal lithostratigraphical units for the Terminal

Proterozoic to early Middle Cambrian of southern Morocco. Newsl. Stratigr. 22, 87–109.

[40] Geyer, G. (1990 b) - Revised Lower to lower Middle Cambrian biostratigraphy of

Morocco. Newsl. Stratigr. 22, 53–70.

[41] Geyer, G. (1996). The Moroccan fallotaspidid trilobites revisited. Beringeria 18: 89–199,

Würzburg.

[42] Geyer, G., & Landing, E. (1995). The Cambrian of the Moroccan Atlas regions. In: Geyer,

G. & Landing, E. (eds.). Morocco „95 - the Lower–Middle Cambrian standard of western

Gondwana. Beringeria Special Issue 2: 7–46, Würzburg.

[43] Geyer, G. & Landing. E. (2004) - A unified Lower–Middle Cambrian chronostratigraphy

for West Gondwana. Acta Geologica Polonica 54: 197–218, Warsaw.

[44] Geyer, G., Landing, E. (EDS.). (2006) - Morocco 2006. Ediacaran–Cambrian depositional

environments and stratigraphy of the western Atlas regions. Explanatory description and

field excursion guide Special Issue 6.UCL Maghreb Petroleum Research Group (MPRG)

Infracambrian/Early Palaeozoic Field Guide Series No. 1.



[45] Geyer, G., Landing, E., (2016) - The Precambrian–Phanerozoic and Ediacaran–Cambrian

boundaries: a historical approach to a dilemma. In: Brasier, A.T., McIlroy, D.,

McLoughlin, N. (Eds.), Earth System Evolution and Early Life: A Celebration of the

Work of Martin Brasier. Geological Society, London, Special Publications, pp.

448.doi.org/10.1144/SP448.10.

[46] Harrison, R.W., Yazidi, A., Benziane, F., Quick, J.E., El Fahssi, A., Stone, B.D., Yazidi,

M., Saadane, A., Walsh, G.J., Aleinikoff, J.N., Ejjaouani, H., Kalai, M., (2008) - Carte

géologique au 1/50 000, Feuille Tizgui. Notes et Mémoires Service Géologique Maroc. N°

470, 1–131.

[47] Hupé P. (1952) - contribution à l‟étude du Cambrien inferieur et du Précambrien III de

l‟Anti-Atlas marocain. Notes et Mém. Serv. Géol. du Maroc. N°103.

[48] Hupé, P. (1953). Contribution a l‟étude du Cambrien inférieur et du Précambrien iii de

l‟Anti-Atlas marocain. Notes et mémoires du service géologique du Maroc 103, 402 p.,

Bagnolet, seine (1952).

[49] Hupé, P. (1959). Nouvelle contribution à l‟étude du Cambrien marocain. Thèse

Scientifique, Faculté des Sciences, Université de Paris, 447 p., Paris.

[50] Hupé, P. 1960. Sur le Cambrien inférieur du Maroc. Reports of the XXIth International

Geological Congress, Norden 1960, 8, 8. Late Pre-Cambrian and Cambrian stratigraphy:

75–85, Copenhagen.

[51] Landing E., Bowring S.A., Davidek K.L., Westrop S.R., Geyer G., Heldmaier W. (1998) -

Duration of the early cambrian: U–Pb ages of volcanic ashes from Avalon and Gondwana.

Canadien Journal of Earth Science 35, 329–338.

[52] Landing, E., Geyer, G. & Heldmaier, W. (2006). Distinguishing eustatic and epeirogenic

controls on Lower–Middle Cambrian boundary successions in West Gondwana (Morocco

and Iberia). Sedimentology: 53: 899–918, London.

[53] Landing Ed., Antcliffeb J. B., Geyerc G., Kouchinskyd A., Bowsere S., Andrease A.

(2018) - Early evolution of colonial animals (Ediacaran Evolutionary Radiation–Cambrian

Evolutionary Radiation–Great Ordovician Biodiversification Interval). Earth-Science

Reviews 178 (2018) 105–135.

[54] Latham, A. & Riding, R. (1990). Fossil evidence for the location of the

Precambrian/Cambrian boundary in Morocco. Nature 344 (6268): 752–754, London.

[55] Leblanc M. (1973) - Les formations infracambriennes de Bou-Azzer (Anti-Atlas, Maroc):

lithostratigraphie, tectonique et position structurale. Notes et Mém. Serv. Géol. Maroc,

t.34, n° 254, pp. 7-14.

[56] Leblanc, M. (1975) - Ophiolites Précambriennes et gîtes arseniés de cobalt (Bou Azzer,

Maroc). Centre Géologique et Géophysique Montpellier, Mém. Hors - Serie, 329 p.

[57] Leblanc, M. & Lancelot, J. R. (1980). Interprétation géodynamique du domaine

panafricain (Précambrien terminal) de l‟Anti-Atlas (Maroc) à partir de données

géologiques et éochronologiques. Canadian Journal of Earth Sciences 17: 142–155,

Ottawa.

[58] Letsch D., El Houicha M., Von Quadt A. and Wilfried Winkler W. (2018) A missing link

in the peri-Gondwanan terrane collage: the Precambrian basement of the Moroccan

Meseta and its lower Paleozoic cover.

[59] Maloof, A.C., Schrag, D.P., Crowley, J.L. and Bowring, S.A. (2005) - An expanded

record of Early Cambrian carbon cycling from the Anti-Atlas Margin, Morocco, Canadian

Journal of Earth Sciences , 42 pp. 2195-2216.




[60] Maloof A.C., Ramezani J., Bowring S.A., Fike D.A., Porter S.M., Mazouad M. (2010) -

Constraints on early Cambrian carbon cycling from the duration of the Nemalit-

Daldynian–Tommotian boundary d13C shift, Morocco. Geology, 38, 623–626.

[61] Monninger, W. (1979). The section of Tiout (Precambrian/Cambrian boundary beds, Anti-

Atlas, Morocco): An environmental model. Arbeiten aus dem Paläontologischen Institut

Würzburg 1: 289 p., Würzburg.

[62] Pique, A. (2001) - Geology of Northwest Africa. Regional en Geologie der Erde, Vol. 29.

Translated by M. S. N. Carpenter. 310 pp. Berlin, Stuttgart.

[63] Pouclet A., Ouazzani H., Fekkak A. (2008) - The Cambrian volcanosedimentary

formations of the westernmost High Atlas (Morocco) : their place in the geodynamic

evolution of the West African Palaeo-Gondwana northern margin. In: Ennih, N., Liegeois,

J.P. (Eds.), The Boundaries of the West African Craton.Geol. Soc., 297. Spec. Publ.,

London, pp. 303–327.

[64] Pouclet A., El Hadi H., Álvaro J.J., Bardintze J.-M., Benharref M., Fekkak A. (2018) -

Review of the Cambrian volcanic activity in Morocco: geochemical fingerprints and

geotectonic implications for the rifting of West Gondwana. International Journal of Earth

Sciences.

[65] Robert-Charrue C. (2006) - Géologie structurale de l'Anti-Atlas oriental, Maroc. Thèse de

doctorat Université de Neuchâtel.

[66] Schmitt, M., Monninger, W., (1977) - Stromatolites and thrombolites in

Precambrian/Cambrian boundary beds of the Anti-Atlas, Morocco: preliminary results. In:

Flugel, E. (Ed.), Fossil Algae. Springer, Berlin, pp. 80–85.

[67] Schmitt, M. 1978. Stromatolites from the Tiout section, Precambrian–Cambrian boundary

beds, Anti-Atlas, Morocco. Geological Magazine Special issue 115 (2): 95–99,

Cambridge.

[68] Sdzuy K. (1978) : The Precambrian-cambrian boundary beds in Morocco (Preliminary

Report). Geol. Mag., 115 (2), 83-94.

[69] Sdzuy, K. & Geyer, G. (1988). The base of the Cambrian in Mo-rocco. In: Jacobshagen,

V. H. (ed.). The Atlas System of Morocco. Studies on its Geodynamic Evolution. Lecture

Notes in Earth Sciences 15: 91–106, Berlin, Heidelberg, New York, London, Paris, Tokyo

(Springer).

[70] Soulaimani A., Bouabdelli M. (2003) - L'extension continentale au Néo-Protérozoïque

supérieur-Cambrien inférieur dans l'Anti-Atlas (Maroc). Bull. Soc. géol. Fr. no1.

[71] Soulaimani A., Blein O., Chevremont Ph., Ouanaimi H., Hafid A., Admou H., Baudin T.,

Bouabdelli M., Razin Ph., Abia E.H., Beni Akhy R. (2013) - Carte géologique du Maroc

au 1/50 000 Feuille Agadir Melloul. Notes et Mémoires du Service Géologique du Maroc

N°549bis.

[72] Soulaimani, A., Michard A., Baidder L., Ouanaimi H., Raddi Y. (2014) - Ediacaran-

Cambrian structures and their reactivation during the Variscan and Alpine cycles in the

Anti-Atlas (Morocco). J. Afr. Earth Sci.

[73] Vernhet E., Youbi N., Chellai E.H., Villeneuve M., El Archi A. (2012) - The Bou-Azzer

glaciation: Evidence for an Ediacaran glaciation on the West African Craton (Anti-Atlas,

Morocco). Precambrian Research 196– 197 (2012) 106– 112.

[74] Walsh, G.J., Aleinikoff, J.N., Benziane, F., Yazidi, A., Armstrong, T.R. (2002) - U–Pb

zircon geochronology of the Paleoproterozic Tagragra de Tata inlier and its

Neoproterozoic cover, western Anti-Atlas, Morocco. Precambr. Res. 117, 1–20.

https://www.researchgate.net/journal/1437-3254_International_Journal_of_Earth_Sciences

https://www.researchgate.net/journal/1437-3254_International_Journal_of_Earth_Sciences

https://www.researchgate.net/profile/Charles_Robert-Charrue

https://www.researchgate.net/profile/Soulaimani_Abderrahmane

https://www.researchgate.net/profile/Mohamed_Bouabdelli2



[75] Walsh G.J., Yazidi A., Benziane F., Burton W.C, Yazidi M., Saadane A. (2008) - Carte

géologique du Maroc, feuille au 1/50 000 Timdghas. Notes et Mémoires Serv. Géol.

Maroc 468.

[76] Walsh G.J., Benziane F., Yazidi A., Burton W.C, Yazidi M., Saadane A. (2008) - Carte

géologique du Maroc, feuille au 1/50 000 Bouskour. Notes et Mémoires Serv. Géol.

Maroc 469.

[77] Yazidi, A., Benziane, F., Walsh, J., Harrison, R.W., Saadane, A., Yazidi, M., Quick, J.E.,

El Fashssi, A., Stone, B.D., Aleinikoff, J.N., Ejjaouani, H., Kalai, M. (2002) - Carte

géologique du Maroc (1/50 000), feuille Zawyat Si Nisser. Not. Mém. Serv. Géol. Maroc.

423, 69.

[78] Yazidi A., Benziane F., Quick J.E., Yazidi M., Saadane A., Walsh G.J. (2008) - Carte

géologique du Maroc, feuille au 1/50 000 Ait Semgane. Notes et Mém. Serv. Géol.

Maroc- Rabat n° 472.

[79] Yazidi A., Benziane F., Schulte B., Boger S., Stockhammer S., Lehmann A., Saadane A.,

Yazidi M. (2016) - Carte géologique du Maroc, feuille au 1/50 000 Assaka. Notes et

Mém. Serv. Géol. Maroc- Rabat n° 544bis.

[80] Yazidi A., Benziane F., Schulte B., Boger S., Stockhammer S., Lehmann A., Saadane A.,

Yazidi M. (2016) - Carte géologique du Maroc, feuille au 1/50 000 Aït Sbouya. Notes et

Mém. Serv. Géol. Maroc- Rabat n° 545bis.

Documents

RECONSIDERATION OF THE LOWER CAMBRIAN EXTENSION IN … · (Ediacarian or NP3) and Paleozoic to the present day (Yazidi and al., 2016). Also, no tectonic unconformity separates the