Quantative analysis and paleoecology of Middle to Upper Eocene Ostracods from Jebel Jebil, central Tunisia

+Model REVMIC-294; No. of Pages 16

ARTICLE IN PRESS Disponible en ligne sur

ScienceDirect www.sciencedirect.com Revue de micropaléontologie xxx (2016) xxx–xxx

Original article

Quantative analysis and paleoecology of Middle to Upper Eocene Ostracods from Jebel Jebil, central Tunisia Analyse quantitative et paléoécologie des Ostracodes de l’Éocène moyen et supérieur de Jebel Jébil, Tunisie centrale Aïda Amami-Hamdi a,∗ , Ferid Dhahri b , Dhouha Jomaa-Salmouna a , Kmar Ben Ismail-Lattrache a , Najeh Ben Chaabane a a

b

Department of Geology, El Manar II, University of Tunis El Manar, Faculty of Sciences of Tunis, 2092 Tunis, Tunisia Department of Earth Sciences, Sidi Ahmed Zarroug, University of Gafsa, Faculty of Sciences of Gafsa, 2112 Gafsa, Tunisia

Abstract One hundred and seventy collected samples from Jebil section have been carefully studied for their ostracod content and referred to 41 species belonging to 20 genera. Their vertical distribution allowed to distinguish five successive associations of ostracod assemblages; two of which are correlated with the Early Lutetian, one with the Late Lutetian, another association with the Bartonian and the last one with the Priabonian. Community structure of the collected ostracod fauna has been studied; three indices have been calculated for each sample: Shannon (diversity), Margalef (richness) and Equitability indexes. In the lower and the middle part of the Formation, they indicate a stable environment supporting high diversity ostracod communities; whereas in the upper portion the environmental conditions were unstable characterized by low diversity. The results of a multivariate statistical method, using the cluster analysis and the Detrended Correspondence Analysis of the 41 ostracod species and the 170 samples, have led to conclude that the most effective environmental factor in the study area is the paleodepth and of less importance oxygenation and salinity. Thus, it allowed to distinguish four palaeoenvironmental intervals within the Cherahil Formation: the first one represented by taxa that are known from the shallower parts of the shelf; the second interval includes the majority of the encountered species of inner neritic shelf with normal salinity; the third one, corresponding to an outer neritic domain; and the last interval refers to a circalittoral environment, is comprised mainly of Cytherella angulata and of Soudanella laciniosa triangulata. © 2016 Elsevier Masson SAS. All rights reserved. Keywords: Ostracods; Middle to Late Eocene; Central Tunisia; Community structure; Multivariate statistical analysis; Palaeoenvironmental intervals

Résumé Cent soixante-dix échantillons prélevés de la section Jebil ont été soigneusement étudiés pour leur contenu en ostracodes ; la faune est composée de 41 espèces appartenant à 20 genres. La distribution verticale de ces espèces a permis de distinguer cinq associations successives d’ostracodes, dont deux sont corrélées avec le Lutétien inférieur, une avec le Lutétien supérieur, une autre avec le Bartonien et la dernière avec le Priabonien. La structure communautaire de la faune à ostracodes recueillie a été étudiée, trois indices ont été calculés pour chaque échantillon : indice de Shannon Waever (diversité), de Margalef (richesse) et d’Équitabilité. Dans la partie inférieure de la Formation, ils indiquent un environnement stable soutenant des communautés d’ostracodes à valeurs élevées de diversité ; tandis que dans la partie supérieure, les conditions environnementales ont été instables caractérisées par une faible diversité. Les résultats de l’analyse de cluster et de l’analyse détendancée de correspondances des 41 espèces d’ostracodes et des 170 échantillons ont permis de conclure que, dans la zone d’étude, le facteur environnemental déterminant est la paléoprofondeur et de moindre importance l’oxygénation et la salinité. Ainsi, cette étude a permis de distinguer quatre intervalles paléoenvironnementaux le long de la Formation Chérahil : le premier est souligné par des taxons connus dans les parties très peu profondes de la plateforme interne ; le

∗

Corresponding author. E-mail addresses: [email protected] (A. Amami-Hamdi), [email protected] (F. Dhahri), [email protected] (D. Jomaa-Salmouna), [email protected] (K. Ben Ismail-Lattrache), [email protected] (N. Ben Chaabane). http://dx.doi.org/10.1016/j.revmic.2016.10.001 0035-1598/© 2016 Elsevier Masson SAS. All rights reserved.

Please cite this article in press as: Amami-Hamdi, A., et al., Quantative analysis and paleoecology of Middle to Upper Eocene Ostracods from Jebel Jebil, central Tunisia. Revue de micropaléontologie (2016), http://dx.doi.org/10.1016/j.revmic.2016.10.001

+Model REVMIC-294; No. of Pages 16 2

ARTICLE IN PRESS A. Amami-Hamdi et al. / Revue de micropaléontologie xxx (2016) xxx–xxx

second comprend la majorité des espèces rencontrées aux environnements à salinité normale de la plateforme interne ; le troisième correspond au domaine de plateforme externe et le dernier intervalle traduit un environnement circalittoral, composé principalement de Cytherella angulata et de Soudanella laciniosa triangulata. © 2016 Elsevier Masson SAS. Tous droits r´eserv´es. Mots clés : Ostracodes ; Éocène moyen à supérieur ; Tunisie centrale ; Structure communautaire ; Analyse statistique multivariée ; Intervalles paléoenvironnementaux

1. Introduction Several micropalaeontological (Oertli, 1976; Bismuth et al., 1978; Said-Benzarti, 1978; Bismuth, 1981; Mechmeche, 1981; Ben Ismail-Lattrache and Bobier, 1996; Ben Ismail-Lattrache, 2000; Trabelsi et al., 2015) and petroleum studies (Said-Benzarti and Kharbachi, 1995) have been realized on ostracods from Tunisia. However, rare are the studies that attempted a paleoecological analysis of Eocene ostracod assemblages from Tunisia. As to other countries from North and West Africa, there exist several studies related to the paleoecology and paleogeography of Eocene ostracods (Elewa et al., 1999; Elewa, 2002; Elewa, 2004; Elewa, 2005; Shahin, 2005; Elewa, 2007; Shahin, 2008; AmamiHamdi and Ben Ismail-Lattrache, 2013; Amami-Hamdi et al., 2014). In Libya, El Waer (1992) used the ostracod morphology and carapace nature of Eocene ostracods for paleoenvironmental reconstructions. In West Africa, Sarr (1995 and 1999) studied the migration of ostracods during the Middle Eocene and their relation with the paleoenvironmental evolution of the western senegalian deposits; the same author (2012) illustrated a link between changes in ostracod faunas and the paleogeographic evolution of the Senegalese basin. Elewa et al. (2001) focused his study on the reconstruction and interpretation of the paleoenvironmental conditions that prevailed during the deposition of the Middle Eocene succession of Northern Somalia by means of ostracod assemblages. In Egypt, Elewa (2004) realized a paleoecological study of the Eocene series in the region of Cairo, based on the quantitative analysis of ostracod assemblages. Mixed methods integrating quantitative and qualitative data collection and analysis were explored in recent studies (Gliozzi and Grossi, 2004; Mazzini, 2004, 2005; Elewa, 2004, 2005; Guasti, 2005; Van Itterbeeck, 2007, Gliozzi and Grossi, 2008; Grossi and Gennari, 2008; Sarr, 2012; Amami-Hamdi and Ben Ismail-Lattrache, 2013 and Amami-Hamdi et al., 2014). They were applied to Middle and Upper Eocene deposits, which are rich in pelagic microfauna. We have sampled and studied in detail the Middle and Upper Eocene succession of the Jebil outcrop in order to obtain a detailed report of its ostracod assemblages. 2. Stratigraphy The Jebil section is located in central Tunisia, near the Khit El-Oued village (18◦ 10 N and 3◦ 71 E); the area is covered by the geological map of Haffouz (1:50,000 scale) (Fig. 1). The Middle and Upper Eocene marine deposits are 200 m thick and well exposed in Jebel Jebil. They present

intercalations of bioclastic limestone (oyster rich) and marls rich in foraminifers and ostracods. These deposits correspond to the Cherahil Formation (Comte and Dufaure, 1973), which is subdivided into three units, which are as follows from base to top: the Lower Cherahil, the Siouf and the Upper Cherahil Members (Fig. 2). 2.1. Lower Cherahil Member This member can be divided into three main units: • the lower unit (J1–J48) is 46 m thick and comprised of laminated green clays with crystallized calcite interbedded with thin argillaceous limestones and a lumachellic limestone bed; • the middle unit (J48–J88) is 40 m thick and comprised of yellowish sandy clays, sometimes gypsiferous and slightly phosphatic with ferruginous concretions and flint nodules. These levels are interbedded with centimetric dolomite beds rich in nummulites; • the upper unit (J88–J122) is 35 m thick and composed of laminated gray-green clays intercalated with fossiliferous argillaceous limestones containing ferruginous concretions. 2.2. Siouf Member It is 5 m thick and composed of lumachellic gray sandy limestones. This level is rich in large benthic foraminifera: Nummulites gizehensis, Discocyclina roberti, Discocyclina sella, Operculina sp. and Alveolina sp. 2.3. Upper Cherahil Member This member can be divided into two units: • the lower unit (J129–J149) is 20 m thick and represented by green laminated claystones, rich in iron oxides and gypsum, and intercalated with centimetric dolomite beds; • the upper unit (J149–J184) is 35 m thick, comprised of fine greenish sandy clays and interbedded with metric lumachellic limestones, rich in Ostrea lamellosa. These limestones are represented by biomicritic grainstone texture with bryozoans, bivalves and algae. 3. Materials and methods Many authors have analyzed different aspects of the Jebil section. Ben Ismail-Lattrache (2000) has been the first to study the planktic and benthic foraminifera, as well as the

Please cite this article in press as: Amami-Hamdi, A., et al., Quantative analysis and paleoecology of Middle to Upper Eocene Ostracods from Jebel Jebil, central Tunisia. Revue de micropaléontologie (2016), http://dx.doi.org/10.1016/j.revmic.2016.10.001

+Model REVMIC-294; No. of Pages 16

ARTICLE IN PRESS A. Amami-Hamdi et al. / Revue de micropaléontologie xxx (2016) xxx–xxx

Fig. 1. Geological map of the study area (after Dhahri and Boukadi, 2010).

Please cite this article in press as: Amami-Hamdi, A., et al., Quantative analysis and paleoecology of Middle to Upper Eocene Ostracods from Jebel Jebil, central Tunisia. Revue de micropaléontologie (2016), http://dx.doi.org/10.1016/j.revmic.2016.10.001

3

+Model REVMIC-294; No. of Pages 16 4

ARTICLE IN PRESS A. Amami-Hamdi et al. / Revue de micropaléontologie xxx (2016) xxx–xxx

Fig. 2. Lithostratigraphy and description of microfacies observed in the Jebil section.

Please cite this article in press as: Amami-Hamdi, A., et al., Quantative analysis and paleoecology of Middle to Upper Eocene Ostracods from Jebel Jebil, central Tunisia. Revue de micropaléontologie (2016), http://dx.doi.org/10.1016/j.revmic.2016.10.001

+Model REVMIC-294; No. of Pages 16

ARTICLE IN PRESS A. Amami-Hamdi et al. / Revue de micropaléontologie xxx (2016) xxx–xxx

ostracod fauna. Subsequent studies have covered structural aspects (Rigane et al., 1994; Rabhi, 1999; Dhahri and Boukadi, 2010). One hundred and seventy samples were collected for this study; they were washed after treatment with diluted H2 O2 . The dried residues were divided into three grain-size fractions (after they were collected with sieves of 250, 100 and 63 ␮m, in mesh). Then they were dried in an oven at 50 ◦ C. The picked ostracods and planktic foraminifers were identified with the help of a stereoscopic binocular. The Middle and Upper Eocene deposits have delivered a rich microfauna characterized by abundant ostracods and foraminifers. The preservation of the planktic foraminifers and ostracods is in general good. Taxonomic analysis and species identification of ostracods was completed with reference to previous works (Bassiouni 1969, 1971; Oertli, 1976; Bismuth, 1981; Mechmeche, 1981 and El Waer, 1992). The species abundance and richness were calculated and normalized to 10 g of each dried and sieved sample. An analysis of the community structure (i.e., species richness, Shannon, Margalef and Equitability indexes; Dodd and Stanton, 1990) and multivariate analysis (i.e., cluster analysis and detrended correspondence analysis), were performed on our ostracod dataset with the help of the PAST software-PAleontology STatistics: 1.52 v (Hammer et al., 2001). 4. Results 4.1. Biostratigraphy Collected from the Upper and Middle Eocene deposits of the Jebel Jebil, the ostracod assemblages comprise more than 41 species belonging to 20 genera. The zonation of these ostracods, used in this paper (Oertli, 1976; Bismuth et al., 1978; Mechmeche, 1981; El Waer, 1992), is calibrated with the coeval local planktic foraminifera biozonal scheme (Ben Ismail-Lattrache, 2000). A correlation between these zones with their regional and worldwide equivalents has been realized. From base to top, we distinguish (Fig. 3): Loculicytheretta semipunctata interval zone: it constitutes the range zone of the marker species L. semipunctata, correlated with the Turborotalia frontosa planktonic foraminiferal zone Berggren and Pearson (2005) of earliest Lutetian age. This biozone is recognized in Tunisia by Oertli (1976), Bismuth et al. (1978), Mechmeche (1981), Said-Benzarti and Kharbachi (1995), Ben Ismail-Lattrache (2000), Amami-Hamdi and Ben Ismail-Lattrache (2013) and Amami-Hamdi et al. (2014) within the base of the Lower Cherahil marls. It is characterized by the abundance of Loculicytheretta harshae, Buntonia ramosa Bassiouni, 1969; Argilloecia ghalilae El Waer, 1992; Costa libyaensis El Waer, 1992; Acanthocythereis salahii Bassiouni, 1969; Acanthocythereis tarabulusensis El Waer, 1992; Paleocosta mokattamensis Bassiouni, 1969. In Libya and according to El Waer (1992), this biozone is homologous to the Heptaloculites harshae zone of Early Lutetian age. In Algeria,

5

Apostolescu and Magné (1956) is attributed to the same zone of this interval. In Egypt, Shama and Helal (1993) assigned the Costa praetricostata praetricostata zone to the Early Lutetian. Loculicytheretta semirugosa interval zone: this zone comprises the interval between two last occurrence (LO) events, the LO of L. semipunctata (Apostolescu and Magné, 1956) at the base and the LO of L. semirugosa at the top. It occurs within the middle part of the Lower Cherahil member. In Tunisia, Bismuth et al. (1978) assigned a late Early Lower Lutetian age to this zone, characterized by abundant ostracods, characteristic of the Early Lutetian: Loculicytheretta prima Bismuth and Oertli, 1978; Soudanella tarabulusensis El Waer, 1992; Paracypris eskeri Bassiouni and Morsi (2000); Paracypris buisae Morsi, 2003 and Leguminocythereis sadeki Bassiouni, 1969. This interval zone is attributed to the Lutetian in Algeria (Apostolescu and Magné, 1956) and to the Middle Lutetian (El Waer, 1992) in Libya. Loculicytheretta minuta interval zone: this zone is characterized by the extinction of both L. semirugosa at its base and the markers species at its top. It occurs within the upper part of the Lower Cherahil marls of Late Lutetian age. This assemblage zone is characterized by the presence of abundant ostracods (Loxoconcha tarabulusensis El Waer, 1992; C. angulata El Waer, 1992; Bairdia samdunae El Waer, 1992 and Soudanella laciniosa triangulata Apostolescu, 1961) associated with larger benthic foraminifers such as Nummulites gizehensis (Forskal, 1775) (A and B forms) and N. discorbinus Schlotheim (1820). In central Tunisia, Mechmeche (1981) described this zone in the Middle Eocene deposits. In Libya, El Waer (1992) assigned a Late Lutetian to this zone. Loculicytheretta cavernosa interval zone: this zone of Bartonian age, is restricted between two LO respectively those of L. minuta at the base and L. cavernosa (Oertli, 1976) at the top. It occurs within the lower part of the Upper Cherahil marls. It is correlated with the Middle Eocene Heptaloculites cavernosa zone recognized by El Waer, 1992 in Libya. In Egypt, this zone is correlated with the Lutetian Digmocythere ismaili–Uromuellerina saidi zone (Shahin et al., 2008). Loculicytheretta aff. gortanii interval zone: this zone is characterized by the LO of both L. cavernosa at its base and the marker species at its top. The co-occurrence of the nominate taxon with the Priabonian taxon Loculicytheretta tunetana (Oertli, 1978), Propontocypris tarabulusensis El Waer, 1992 and Hermanites libyaensis El Waer, 1992 and with the planktic foraminiferal marker species Turborotalia cerroazulensis Cole, 1928 (Wade and Pearson, 2008) allows to correlate this interval with the Priabonian. In Tunisia, Oertli (1976), Bismuth et al. (1978), Mechmeche (1981), Said-Benzarti and Kharbachi (1995), Ben Ismail-Lattrache (2000) and AmamiHamdi and Ben Ismail-Lattrache (2013) described this zone in the Priabonian deposits. In Libya, this zone is correlated with the Priabonian Heptaloculites aff. gortanii zone (El Waer, 1992).

Please cite this article in press as: Amami-Hamdi, A., et al., Quantative analysis and paleoecology of Middle to Upper Eocene Ostracods from Jebel Jebil, central Tunisia. Revue de micropaléontologie (2016), http://dx.doi.org/10.1016/j.revmic.2016.10.001

+Model REVMIC-294; No. of Pages 16 6

ARTICLE IN PRESS A. Amami-Hamdi et al. / Revue de micropaléontologie xxx (2016) xxx–xxx

Fig. 3. Stratigraphic distribution of ostracofauna in the Middle and Upper Eocene lithostratigraphical units of the Jebel Jebil.

Please cite this article in press as: Amami-Hamdi, A., et al., Quantative analysis and paleoecology of Middle to Upper Eocene Ostracods from Jebel Jebil, central Tunisia. Revue de micropaléontologie (2016), http://dx.doi.org/10.1016/j.revmic.2016.10.001

+Model REVMIC-294; No. of Pages 16

ARTICLE IN PRESS A. Amami-Hamdi et al. / Revue de micropaléontologie xxx (2016) xxx–xxx

7

Fig. 4. Diagrams of the community structure indices of 41 ostracod taxa samples recorded from the Middle and Upper Eocene intervals of the Jebil section.

4.2. Paleobioecology 4.2.1. Community structure analyses- diversity indices Community structure analyses have been performed on the ostracod assemblages collected from the Cherahil Formation, in the Jebil section. Diversity takes into account not only the number of species, but also the distribution of individuals in these species. Three assemblage structure indexes were calculated for each sample: Shannon (diversity), Margalef (richness) and Equitability indexes (Fig. 4). In the lower part of the Cherahil Formation, samples display a rather medium diversity and Equitability (which may reach the value of 1), coupled with high richness up to a maximum value of 4 (Samples J2, J10, J56 and J59), indicating a stable environment able to support a mature assemblage. Within the middle part of the Cherahil Formation (J112 to J152), samples display a high diversity and richness with maximum values of Shannon (1.6) and Margalef indexes (up to 5 in sample J129), coupled with a peak of Equitability around 1.6. These parameters reflect a relatively stable environment, leading to the establishment of several mature communities of ostracods. The top of the Upper Cherahil Member (J152 to J184), displays very low values for the Shannon and Equitability indexes, coupled with low species richness (with a Margalef index value below 1), indicating an unstable environment with low

diversity communities dominated by the taxa Loculicytheretta aff. gortanii. 4.2.2. Multivariate analysis 4.2.2.1. Cluster analysis. In order to depict the detailed paleoenvironmental evolution of the Middle to Upper Eocene succession at the Jebil section, a multivariate statistical approach was carried out based on the analysis of ostracod assemblages. Cluster analysis based on the similarity coefficient (Jaccard coefficient) using the paired-group method was applied to the data matrix. Hence, four distinct biofacies can be discerned (Fig. 5), which are often characteristic of a specific paleoenvironment: Biofacies A: is represented by A. salahii, P. mokattamensis, C. libyaensis and Isobuntonia pseudotuberata. This ostracofauna was encountered at the base of the Lower Cherahil Member. This biofacies has a low P/B ratio (8%). Biofacies B: which includes species that are increasingly abundant in the L. semipunctata and L. semirugosa zones. The majority of these species are recognized in the Lower Cherahil Member. This biofacies has a low P/B ratio (5%). Biofacies C is the most visible cluster in the dendrogram and regroups species that are more common in the upper part of the Lower Cherahil Member and the lower part of the Upper Cherahil Member, and are dominant in the L. minuta and L. cavernosa zones. The P/B ratio increases to reach a maximum at 20%.

Please cite this article in press as: Amami-Hamdi, A., et al., Quantative analysis and paleoecology of Middle to Upper Eocene Ostracods from Jebel Jebil, central Tunisia. Revue de micropaléontologie (2016), http://dx.doi.org/10.1016/j.revmic.2016.10.001

+Model REVMIC-294; No. of Pages 16 8

ARTICLE IN PRESS A. Amami-Hamdi et al. / Revue de micropaléontologie xxx (2016) xxx–xxx

Fig. 5. R mode clustering (taxa) based on Jaccard coefficient applied to 41 ostracod species. The Pelagic index is also provided.

Biofacies D is represented by species which dominate the ostracod record in the Loculicytheretta aff. gortanii zone. This biofacies is mainly present in the top of the Upper Cherahil Member. The Pelagic index is relatively high (42%). As shown in Fig. 5, biofacies D is characterized by several reticulated ostracod fauna. It is worth noting the coincidence of community analyses results and cluster analysis results.

4.2.2.2. Detrended Correspondence Analysis (DCA). In the studied section, detrended correspondence analysis performed on the 170 samples was used to analyze the ostracod assemblages. The resulting DCA species plot shows two axes (with positive values greater than 1) that account respectively 51 and 16% (Fig. 6). The maximum information is provided by Axis 1 (51%); the first two axes represent 67% of the total information about the correlations between variables. The graphic tests with axis 3 to 7 do not provide additional information, giving a less clear picture of the distribution of variables. However, the graph relating the Axis 1 and Axis 2 was used to confirm the ostracod clusters distinguished by the dendrogram. The distribution of the ostracod species of Jebil section on the first two axis allows to distinguish four clusters according to Axis 1 (the first one represents negative values: < −0.5 and the three other ones represent positive values: > 0.25, that match the four clusters previously recognized:

Group I: same as Biofacies D, is represented mainly by opportunistic species of high frequency (Loculicytheretta aff. gortanii); Group II: similar as Biofacies C includes the species of ostracods L. minuta, L. tunetana, L. cavernosa, C. angulata, L. tarabulusensis, Soudanella laciniosa triangulata, B. samdunae, Asymmetricythere yousefi and Brachycythere omarai; Group III: the same as Biofacies B, are characterized by the presence of species L. semipunctata, L. semirugosa, Loxoconcha vetustopunctatella, Reticulina proteros, P. eskeri, L. sadeki, Costa aff. bassiouni, Costa aff. saidi and A. ghalilae; Group IV: similar as Biofacies A includes C. libyaensis, I. pseudotuberata, P. mokattamensis and A. salahii species. Species Leguminocythereis cirtaensis and Leguminocythereis africana, occupying a position at the same distance of Groups II and III, with low frequencies, are present in almost all the analyzed samples. In general, the positions of the samples in the diagram appear to be strongly influenced by the microfaunal frequency and diversity. Nevertheless for both Groups I and IV, they appear to be only characterized by low frequency of ostracods rather than taxonomic composition. There are several palaeoecological data on the Eocene ostracods of North and West Africa (Babinot, 1973; Bismuth et al., 1978; Colin and Carbonel, 1982; Donze et al., 1982; Peypouquet et al., 1983; Carbonnel and Johnson, 1989; Bassiouni and Luger, 1990; El Waer, 1992; Keen et al., 1994; Elewa and Ishizaki,

Please cite this article in press as: Amami-Hamdi, A., et al., Quantative analysis and paleoecology of Middle to Upper Eocene Ostracods from Jebel Jebil, central Tunisia. Revue de micropaléontologie (2016), http://dx.doi.org/10.1016/j.revmic.2016.10.001

+Model REVMIC-294; No. of Pages 16

ARTICLE IN PRESS A. Amami-Hamdi et al. / Revue de micropaléontologie xxx (2016) xxx–xxx

9

Fig. 6. Scatter plot of 41 ostracod species recovered from 170 samples coming from the Middle and Upper Eocene intervals of the Jebil section according to Detrended Correspondence Analysis taken along two Axes.

1994; Elewa et al., 1998; Elewa, 1999; Elewa et al., 1999; Elewa, 2004; Elewa and Morsi, 2004; Elewa, 2005; Elewa, 2007; Sarr, 2012; Amami-Hamdi and Ben Ismail-Lattrache, 2013 and Amami-Hamdi et al., 2014), which afford a possible synecological characterization of ostracod assemblages. Group II dominated by rather deep taxa like C. angulata, B. samdunae and Soudanella laciniosa triangulata, which reflect an outer platform domain (Bassiouni and Luger, 1990). While, the ostracode fauna recorded in Group III are dominated by taxa (Reticulina proteros and P. eskeri) known from the deeper parts of the shelf: outer shelf (Bassiouni and Luger, 1990) and reflecting reduced dissolved oxygen level (Babinot, 1973; Colin and Carbonel, 1982; Whatley and Coles, 1991). The ostracod assemblage of Group IV specifically proliferates in an inner environment (Peypouquet et al., 1983). In fact, at the presence of sighted species with eye tubercle such as Acanthocythereis typical of infralittoral environment of 0–150 m depth (Keen et al., 1994) where minimum oxygen zone is low and the deep ocean circulation is sufficient (Donze et al., 1982), confirms this attribution. Else, the abundance of a high ornamented form (P. mokattamensis and Costa spp.), which tolerate a high pH and Mg++/Ca++ ratio (Peypouquet et al., 1980 in Carbonel, 1988), may indicate deposition at inner shelf depth.

Thus, the Axis 1 which accounts 51% of the total variance could represent the ecological parameter “depth”. The interpretation of ostracod cluster distribution along this axis reflects significant sensitivity to paleodepth fluctuations. However, the Axis 2 which accounts 16% of the total variance might represent the ecological parameters salinity or oxygenation.

5. Paleoecological implications The result of quantitative analyzes (community analyses, cluster analysis and DCA) of 41 species of ostracods and qualitative analysis of the associated planktic foraminifers allowed to give important information that distinguish several palaeoenvironmental intervals within the Cherahil Formation (Fig. 7). Interval 1- Biofacies A–B and Group III–IV (samples J1–J88); ostracod association reveals a rather medium diversity and a high richness with the occurrence of significant species of middle to outer platform environment with the abundance of inner neritic taxa with normal salinity (Whatley, 1983). However, the low P/B ratio indicates a shallow water depth. The relationship between environmental variables and species suggests a preference of these species to oxygenated conditions and relatively diversified ecosystem.

Please cite this article in press as: Amami-Hamdi, A., et al., Quantative analysis and paleoecology of Middle to Upper Eocene Ostracods from Jebel Jebil, central Tunisia. Revue de micropaléontologie (2016), http://dx.doi.org/10.1016/j.revmic.2016.10.001

+Model REVMIC-294; No. of Pages 16 10

ARTICLE IN PRESS A. Amami-Hamdi et al. / Revue de micropaléontologie xxx (2016) xxx–xxx

Fig. 7. Paleoecological and palaeoenvironmental evolution (Paleodepth) of the Cherahil Formation in the Jebil core.

Please cite this article in press as: Amami-Hamdi, A., et al., Quantative analysis and paleoecology of Middle to Upper Eocene Ostracods from Jebel Jebil, central Tunisia. Revue de micropaléontologie (2016), http://dx.doi.org/10.1016/j.revmic.2016.10.001

+Model REVMIC-294; No. of Pages 16

ARTICLE IN PRESS A. Amami-Hamdi et al. / Revue de micropaléontologie xxx (2016) xxx–xxx

11

Fig. 8. Distribution of the Middle and Upper Eocene Ostracoda associations in Jebil section from the coastal line to the abyssal domain.

Interval 2- Biofacies C and Group II (samples J96–J149); the subsequent dominance of the taxa Soudanella laciniosa triangulata, C. angulata and B. samdunae that seem to have inhabited the shallow inner shelf as well as the deep outer shelf depths (Bassiouni and Luger, 1990; Whatley and Coles, 1991), together with high values of the diversity indexes indicates deepening trend during deposition of interval 2 from inner to outer neritic depths, and marks of environmental stability. These data coupled with a relative increase of pelagic index suggest an outer neritic domain with normal salinity.

Interval 3- Biofacies D and Group I (samples J152–J184); show a very low diversity and richness indexes coupled with a very high faunal dominance characterizing an association of opportunistic species: Loculicytheretta aff. gortanii, which tolerate spontaneous variations of depth and dissolved oxygen in the upper part of the section. The higher pelagic index suggests an increase of water depth from an outer neritic to a circalittoral environment, that was confirmed by the global sea trend marked in the Priabonian by Miller et al. (2005). It reflects semi pelagic within a circalittoral environment.

Please cite this article in press as: Amami-Hamdi, A., et al., Quantative analysis and paleoecology of Middle to Upper Eocene Ostracods from Jebel Jebil, central Tunisia. Revue de micropaléontologie (2016), http://dx.doi.org/10.1016/j.revmic.2016.10.001

+Model REVMIC-294; No. of Pages 16 12

ARTICLE IN PRESS A. Amami-Hamdi et al. / Revue de micropaléontologie xxx (2016) xxx–xxx

Plate 1. Examples of typical ostracod species collected from the studied section: 1, Acanthocythereis salahii Bassiouni, 1969 × 100, lateral view of right valve, Lower Lutetian (sample J10); 2: Loculicytheretta semipunctata (Apostolescu and Magné, 1956) × 150, carapace in ventral view, Lower Lutetian (sample J41); 3: Loculicytheretta semirugosa (Apostolescu and Magné, 1956) × 100, lateral view of right valve, Upper part of Lower Lutetian (sample J14); 4: Loculicytheretta minuta (Oertli, 1978) × 200, lateral view of right valve, Upper Lutetian (sample J122); 5, 6: Reticulina proteros Bassiouni, 1969 × 150, 5- carapace in dorsal view; 6- lateral view of left valve, Lower Lutetian (sample J58); 7: Loculicytheretta tunetana (Oertli, 1978) × 150, carapace in ventral view × 150, Bartonian (sample J145); 8: Loculicytheretta cavernosa (Apostolescu and Magné, 1956) × 150, carapace in ventral view, Upper Lutetian-Bartonian (sample J122); 9: Loculicytheretta aff. gortanii (Ruggieri, 1963) × 150, carapace in ventral view, Priabonian (sample J155); 10: Loculicytheretta harshae El Waer, 1992 × 100, carapace in ventral view, Lower Lutetian (sample J14); 11: Xestoleberis tarabulusensis El Waer, 1992 × 200; lateral view of right valve, Bartonian (sample J140); 12, 13: Ruggiera aff. glabella Bassiouni, 1969 × 100, 12- lateral view of right valve, 13- carapace in ventral view, Lower Lutetian (sample J1); 14: Brachycythere (Digmocythere) ismaili Bassiouni 1971 × 100, carapace right side, Lower Lutetian (sample J14).

Please cite this article in press as: Amami-Hamdi, A., et al., Quantative analysis and paleoecology of Middle to Upper Eocene Ostracods from Jebel Jebil, central Tunisia. Revue de micropaléontologie (2016), http://dx.doi.org/10.1016/j.revmic.2016.10.001

+Model REVMIC-294; No. of Pages 16

ARTICLE IN PRESS A. Amami-Hamdi et al. / Revue de micropaléontologie xxx (2016) xxx–xxx

13

Plate 2. Examples of typical ostracod species collected from the studied section: 1: Isobuntonia pseudotuberata (Apostolescu and Magné, 1956) × 150, lateral view of left valve, Lower Lutetian (sample J10); 2: Loxoconcha vetustopunctatella Bassiouni, Bou Khary, Shama and Blondeau, 1984 × 150, lateral view of right valve, Lutetian (sample J46); 3: Soudanella laciniosa triangulata Apostolscu, 1961 × 150, lateral view of right valve, Upper Lutetian (sample J122); 4: Acanthocythereis tarabulusensis El Waer, 1992 × 100, lateral view of left valve, Lower Lutetian (sample J2); 5, 6: Asymmetricythere yousefi Bassiouni, 1971 × 100, 5- lateral view of left valve, 6- carapace in dorsal view, Middle Lutetian (sample J129); 7: Soudanella tarabulusensis El Waer, 1992 × 150, lateral view of right valve, Lower Lutetian (sample J66); 8: Costa aff. bassiounii Cronin and Khalifa, 1979 × 100, lateral view of left valve, Lower Lutetian (sample J16); 9: Loxoconcha tarabulusensis El Waer, 1992 × 150, lateral view of right valve, Priabonian (sample J155); 10: Bairdia samdunae El Waer, 1992 × 75, lateral view of right valve, Upper Lutetian (sample J100); 11: Parcypris eskeri Bassiouni and Morsi, 2000 × 150, lateral view of right valve, Lower Lutetian (sample J52); 12: Argilloecia ghalilae El Waer, 1992 × 100, lateral view of right valve, Lower Lutetian (sample J41); 13: Cytherella angulata El Waer, 1992 × 150, lateral view of right valve, Upper Lutetian-Bartonian (sample J118).

Please cite this article in press as: Amami-Hamdi, A., et al., Quantative analysis and paleoecology of Middle to Upper Eocene Ostracods from Jebel Jebil, central Tunisia. Revue de micropaléontologie (2016), http://dx.doi.org/10.1016/j.revmic.2016.10.001

+Model REVMIC-294; No. of Pages 16 14

ARTICLE IN PRESS A. Amami-Hamdi et al. / Revue de micropaléontologie xxx (2016) xxx–xxx

Paleoecological model The paleoecology of ostracods, typical of Southern Tethys, studied in Algeria (Faid, 1999), Libya (El Waer, 1992; Whatley and Arias, 1993) and Egypt (Elewa and Ishizaki, 1994; Elewa, 1997; Elewa et al., 1998; Elewa, 1999; Elewa et al., 1999; Elewa, 2002; Elewa, 2004; Elewa and Morsi, 2004; Elewa, 2005 and Elewa, 2007) is adopted for the reconstruction of the paleoecological model of Tunisian ostracods. The variations of ostracod associations obtained from the studied section and the resultant statistical analysis (Hierarchical and Correspondence detrended analysis) led to the reconstruction of a model showing the marine ostracod distribution depending on the depth, salinity and oxygen. In conclusion, this paleoecological model has permitted to distinguish different paleoenvironments according to the studied ostracod associations (Fig. 8): Association A- represented by Loculicytheretta aff. gortanii and H. libyaensis that are known from the shallower parts of the shelf: inner shelf. Association B- includes the taxa A. salahii, A. tarabulusensis, Costa aff. bassiouni and P. mokattamensis, specifically proliferates in an inner neritic environment. Association C- comprising of Reticulina proteros and P. eskeri that are known from the deeper parts of the shelf: outer shelf. Association D- dominated by Soudanella laciniosa triangulata, Cytherella angulata and B. samdunae that seem to have inhabited the shallow inner shelf as well as the deep outer shelf depths. The other ostracod species which have not been reported in all the studied cross-sections are not incorporated in this model. Their distribution is sporadic and has not allowed carrying out neither a qualitative nor a quantitative study for the understanding of paleoenvironmental changes (Plates 1 and 2). Accordingly, the paleoecology, based on quantitative and qualitative study of the ostracod fauna, highlighted four associations. The diversity indices calculated for each sample (Shannon Weaver index, Margalef and Equitability) allowed to assign an unstable environment of the Middle and Upper Eocene deposits. 6. Conclusion The Middle and Upper Eocene deposits of the Jebil outcrop located in central Tunisia are subdivided from base to top into two members: the Lower Cherahil and Upper Cherahil Members. These latter are separated by Siouf lumachellic limestones. According to the ostracod fauna, the recognition of 41 species has permitted to identify five interval zones: three zones are assigned to the Lutetian: L. semipunctata zone, L. semirugosa zone and L. minuta zone; one to the Bartonian: L. cavernosa zone, and another to the Priabonian: Loculicytheretta aff. gortanii zone. In order to bring precise details for the paleoecological study, two approaches have been used; the first one is based on the distribution and the relative abundance of ostracod species. It has permitted to recognize the modifications under gone by environmental parameters and to reconstruct the

paleoenvironmental evolution in space and in time. The second one is based on statistical approach (cluster and detrended correspondence analysis), considering different environmental variables such as paleodepth, paleosalinity and oxygenation. It has permitted to determine the possible relationship between the distribution of the Middle and Upper Eocene ostracods and the oceanographic characteristics of central Tunisia. These analyses revealed that the ostracod associations provided by the studied material are characteristic of a platform environment from inner shelf to circalittoral. Disclosure of interest The authors declare that they have no competing interest. Acknowledgments The authors are grateful to Taniel DANELIAN (Revue de Micropaléontologie Editor-in-Chief) and to the reviewers Ashraf M.T. ELEWA (Minia University, Al Miny¯a, Egypt) and Raphaël SARR (Cheikh Anta Diop University, Dakar) for thoughtful comments that improved the manuscript. References Amami-Hamdi, A., Ben Ismail-Lattrache, K., 2013. Les ostracodes et foraminifères associés des dépôts de l’Éocène moyen et supérieur de la coupe de Jebel Serj (Tunisie centrale). Intérêt biostratigraphique, paléoécologique et paléobiogéographique. Revue de Micropaléontologie 56 (4), 159–174. Amami-Hamdi, A., Dhahri, F., Saïd-Benzarti, R., 2014. Middle to Upper Eocene ostracofauna of central Tunisia and Pelagian Shelf: examples of Jebel Bargou and the Gabes Gulf. Arabian Journal of Geosciences 7 (4), 1587–1603. Babinot, J.F., 1973. Ostracodes turoniens de la région de Cassis-La Bedoule (Bouches du Rhone), France: associations et affinités paléogéographiques. Geobios 6 (1), 27–48. Bassiouni, M.A., 1969. Einige Buntonia und Soudanella Arten (Ostracoda Crustaea) aus dem Eozän von Jordanien. Paläontologische Zeitschrift 43 (3/4), 205–214. Bassiouni, M.A., 1971. Ostracoden aus dem Eozän von Agypten Die Unterfalien Brachycytherinae und Buntoniinae. Geologisches Jahrbuch 89, 169–192. Bassiouni, M.A., Luger, P., 1990. Maastrichtian to early Eocene ostracoda from southern Egypt. Paleontology, Paleoecology, Paleobiogeography and biostratigraphy Berliner Geowissenschaftliche Abhandlungen. Reihe (A): Geologie und Paläontologie 120, 755–928. Ben Ismail-Lattrache, K., 2000. Précision sur le passage Lutétien-Bartonien dans les dépôts éocènes moyens en Tunisie Centrale et Nord-orientale. Revue de Micropaléontologie 43 (1–2), 3–16. Ben Ismail-Lattrache, K., Bobier, C., 1996. Etude biostratigraphique et paléoécologique et paléobiogéographique des séries Eocènes de Tunisie Centrale. Géologie de l’Afrique et de l’Atlantique Sud. Actes Colloques Angers 1994, 563–583. Berggren, W.A., Pearson, P.N., 2005. A revised tropical and subtropical Paleogene planktonic foraminiferal zonation. Journal of Foraminiferal Research 35, 279–298. Bismuth, H., 1981. Principaux repères microfaunistiques dans les séries non pélagiques de l’Eocène moyen et supérieur de Tunisie. Résumé du 1ér Congrès National des Sciences de la Terre. SEREPT, Tunis, 1 p. Bismuth, H., Kelj, A.J., Oertli, H.J., Szczechura, J., 1978. The genus Loculicytheretta (Ostracoda). Bulletin Centre de Recherche, d’Exploration et de Production, Elf-Aquitaine 2 (2), 227–263.

Please cite this article in press as: Amami-Hamdi, A., et al., Quantative analysis and paleoecology of Middle to Upper Eocene Ostracods from Jebel Jebil, central Tunisia. Revue de micropaléontologie (2016), http://dx.doi.org/10.1016/j.revmic.2016.10.001

+Model REVMIC-294; No. of Pages 16

ARTICLE IN PRESS A. Amami-Hamdi et al. / Revue de micropaléontologie xxx (2016) xxx–xxx

Carbonel, P., 1988. Ostracods and the transition between fresh and saline waters. In: De Deckker, P., Volin, J.P., Peypouquet, J.P. (Eds.), Ostracoda in the Earth Sciences. Elsevier XII, pp. 157–173. Carbonnel, G., Johnson, A., 1989. Les Ostracodes Paléogènes du Togo: taxonomie, biostratigraphie, apports dans l’organisation et l’évolution du basin. Géobios 22, 409–443. Colin, J.P., Carbonel, P., 1982. Inventaire des ostracodes fossiles de la Réserve Naturelle Géologique de Saucats - La Brède. Bulletin de la Société Linnéenne de Bordeaux t. 21, fasc. 1, 3–35. Comte, D., Dufaure, P., 1973. Quelques précisions sur la stratigraphie et la paléontologie Tertiaire en Tunisie Centrale et Centro-Oriental, du Cap Bon au Mazzouna. Livre Jubilaire M. Solignac. Annale des Mines de la Géologie 16, 97–115. Dhahri, F., Boukadi, N., 2010. The evolution of pre-existing structures during the tectonic inversion process of the Atlas chain of Tunisia. Journal of African Earth Sciences 56, 139–149. Dodd, J.R., Stanton, R.J., 1990. Paleoecology. Concepts and applications. WileyInterscience Publication, Wiley & Sons (Edit.), New York, 502 p. Donze, P., Colin, J.P., Damotte, R., Oertli, H., Peypouquet, J.P., Said, R., 1982. Les Ostracodes du Campanien Terminal à l’Éocène inférieur de la coupe de Kef, Tunisie Nord-Occidental. Bulletin du Centre de Recherche, ElfAquitaine 6, 273–355. El Waer, A.A., 1992. Tertiary and Upper Cretaceous Ostracoda from NW offshore Libya. Their Taxonomy, Biostratigraphy and Correlation with adjacent. Earth Sciences Society Libya (Edit.), Tripoli, 445 p. Elewa, A.M.T., 1999. The use of allochthonus microfossils in determining palaeoenvironments: A case study using Middle Eocene ostracods from Wadi El Rayan, Fayoum, Egypt. Bulletin Faculty of Sciences Assiute University (Egypt) 28 (2), 33–52. Elewa, A.M.T., 2002. Paleobiogeography of Maastrichtian to Early Eocene Ostracoda of North and West Africa and the Middle East. Micropaleontology 48 (4), 391–398. Elewa, A.M.T., 2004. Quantitative analysis and palaeoecology of Eocene Ostracoda and benthonic foraminifera from Gebel Mokattam, Cairo, Egypt. Palaeogeogr., Palaeoclimat., Palaeoecol., Elsevier, The Netherlands 211 (3–4), 309–323. Elewa, A.M.T., 2005. Paleoecology and Paleogeography of Eocene Ostracod Faunas from the Nile Valley between Minia and Maghagha, Upper Egypt. In: Elewa, A.M.T. (Ed.), Migration in Organisms: Climate, Geography, Ecology. Springer-Verlag Publishers, Heidelberg, Germany, pp. 25–70. Elewa, A.M.T., 2007. Predation due to changes in environment: Ostracod provinciality at the Paleocene-Eocene thermal maximum in North and West Africa and the Middle East. In: Elewa, A.M.T. (Ed.), Predation in Organisms A Distinct Phenomenon. Springer–Verlag Publ, Heidelberg, Germany, pp. 7–26. Elewa, A.M.T., Bassiouni, M.A., Luger, P., 1999. Multivariate data analysis as a tool for reconstructing paleoenvironments: The Maastrichtian to Early Eocene Ostracoda of southern Egypt. Bulletin Faculty of Sciences Minia University (Egypt) 12 (2), 1–20. Elewa, A.M.T., Ishizaki, K., 1994. Ostracodes from Eocene rocks of the El Sheikh Fadl-Ras Gharib stretch, the Eastern Desert, Egypt (Biostratigraphy and paleoenvironments). Earth Science (Chikyu Kagaku, Tokyo) 48 (2), 143–157. Elewa, A.M.T., Luger, P., Bassiouni, M.A., 2001. Middle Eocene Ostracoda from Northern Somalia (paleoenvironmental appraisal). Revue de Micropaléontologie 44 (1), 279–289. Elewa, A.M.T., Morsi, A.A., 2004. Palaeobiotope analysis and palaeoenvironmental reconstruction of the Paleocene-early Eocene ostracodes from east-central Sinai, Egypt. In: Beaudoin, A.B., Head, M.J. (Eds.), The Palynology and Micropalaeontology of Boundaries. The Geological Society, London, pp. 293–308. Elewa, A.M.T., Omar, A.A., Dakrory, A.M., 1998. Biostratigraphical and paleoenvironmental studies on some Eocene ostracodes and foraminifers from the Fayoum depression, Western Desert, Egypt. Egyptian Journal of Geology 42 (2), 439–469. Faid, N., 1999. Ostracodes de l’Eocènes inférieur moyen de l’Atlas saharien (Algérie) : Interprétation environnementale et paléogéographique. Géobios 32 (3), 459–481.

15

Gliozzi, E., Grossi, F., 2004. Ostracode assemblages and palaeoenvironmental evolution of the Latest Messinian lago-mare event at Perticara (Montefeltro, Northern Apennines, Italy). Revista Espa˜nola de Micropaleontología 36 (1), 157–169. Gliozzi, E., Grossi, F., 2008. Late Messinian lago-mare ostracod palaeoecology: A correspondence analysis approach. Palaeogeography, Palaeoclimatology, Palaeoecology 264, 288–295. Grossi, F., Gennari, R., 2008. Palaeoenvironmental reconstruction across the messinian/zanclean boundary by means of ostracods and foraminifers: the Montepetra borehole (Northern Apennine, Italy). Atti del museo civico di storia naturale di Trieste 53, 67–88. Guasti, E., 2005. Early Paleogene environmental turnover in the Southern Tethys as recorded by foraminiferal and organic-walled dinoflagellate cysts assemblages. Berichte aus dem Fachbereich Geowissenschaften der Universität Bremen 241, 1–203. Hammer, Ø., Harper, D.A.T., Ryan, P.D., 2001. PAST: Paleontological Statistics software package for education and data analysis. Palaeontologia Electronica 4 (1), 9 p. Keen, M.C., Al Sheikhly, S.S.J., El Sogher, A., Gammudi, A.M., 1994. Tertiary ostracods of North Africa and the Middle East. In: Simmons, E.D. (Ed.), Micropaleontology and Hydrocarbon Exploration in the Middle East. Chapman & Hall, London, pp. 371–388. Mazzini, I., 2004. Quaternary benthic Ostracoda from the Tasman Sea: distribution patterns within circumpolar deep-waters. Bollettino della Società Paleontologica Italiana 43, 217–224. Mazzini, I., 2005. Taxonomy, biogeography and ecology of Quaternary benthic Ostracoda (Crustacea) from circumpolar deepwater of the Emerald Basin (Southern Ocean) and the S Tasman Rise (Tasman Sea). Senckenbergiana Maritima 35, 1–119. Mechmeche, R., 1981. La Formation Souar (Éocène moyen et supérieur) dans le secteur Maktar-Siliana, Bou-Arada (Tunisie du Centre-Nord): Etude lithostratigraphique, biostratigraphique et paléontologique. Université Lyon (Thèse 3e cycle), 165 p. Miller, K.G., Kominz, M.A., Browning, J.V., Wright, J.D., Mountain, G.S., Katz, M.E., Sugarman, P.J., Cramer, B.S., Christie-Blick, N., Pekar, S.F., 2005. The Phanerozoic record of global sea-level change. Science 312, 1293–1298. Oertli, H.J., 1976. The evolution of Loculicytheretta in the Eocene. Abhandlungen und Verhandlungen der Naturwissenschaftlichen Vereins in Hamburg. NF 18/19 (Supplement), 153–160. Peypouquet, J.P., Carbonel, P., Taieb, M., Tiercelin, J.J., Perinet, G., 1983. The ostracodes and evolution of the past hydrologic environment in the Hadar Formation (the Afar depression, Ethiopia). In: Maddocks, R.F. (Ed.), Applications of Ostracoda. Proceedings of the 8th International Symposium on Ostracoda. University of Houston, pp. 277–285. Peypouquet, J.P., Ducasse, O., Gayet, J., Pratviel, L., 1980. Agradation et dégradation» des tests d’ostracodes. Intérêt pour la connaissance de l’évolution paléohydrologique des domaines margino-littoraux carbonatés , Congrès : « Cristallisation-Déformation-Dissolution des carbonates », Bordeaux, pp. 357–369. Rabhi, M., 1999. Contribution à l’étude stratigraphique et analyse de l’évolution géodynamique de l’axe Nord-Sud et des structures avoisinantes (Tunisie Centrale). Université de Tunis II, Faculté des Sciences, Tunis, 206 p. Rigane, A., Gourmelen, C., Broquet, P., Truillet, R., 1994. Originalité des phénomènes tectoniques syn-sédimentaires fini-yprésiens en Tunisie centroseptentrionale (région de Kairouan). Bulletin de la Société géologique de France 165 (1), 27–35. Said-Benzarti, R., 1978. Etude stratigraphique et micropaléontologique du passage Crétacé-Tertiaire du Synclinal d’Ellès (Région Siliana-Sers) Tunisie Centrale. Thèse de doctorat, 3e Cycle, Université Pierre et Marie Curie, Paris VI, 275 p. Said-Benzarti, R., Kharbachi, S., 1995. Eocene Ostracode and foraminifera layering in Ashtart Field-Ostracoda and Biostratigraphy. 12th International Symposium on Ostracoda, Prague 1994, 193–202. Sarr, R., 1995. Étude biostratigraphique et paléoenvironnementale des séries d’âge Crétacé terminal à Eocène moyen du Sénégal occidental. Systématique et migration des Ostracodes. Thèse de doctorat (inédite), Université Dakar, 335 p (unpublished).

Please cite this article in press as: Amami-Hamdi, A., et al., Quantative analysis and paleoecology of Middle to Upper Eocene Ostracods from Jebel Jebil, central Tunisia. Revue de micropaléontologie (2016), http://dx.doi.org/10.1016/j.revmic.2016.10.001

+Model REVMIC-294; No. of Pages 16 16

ARTICLE IN PRESS A. Amami-Hamdi et al. / Revue de micropaléontologie xxx (2016) xxx–xxx

Sarr, R., 1999. Le Paléogène de la région de Mbour-Joal (Sénégal occidental): biostratigraphie, étude systématique des ostracodes, paléoenvironnement. Revue de Paléobiologie, Genève 18 (1), 1–29. Sarr, R., 2012. Biozonation et paléoenvironnement des ostracodes du Paléogène du Sénégal occidental (Afrique de l’Ouest). Revue de Paléobiologie 31 (1), 145–158. Shahin, A., 2005. Maastrichtian to Middle Eocene ostracodes from Sinai, Egypt: systematics, biostratigraphy and paleobiogeography. Revue de Paléobiologie 24, 749–779. Shahin, A., El Halaby, O., El Baz, S., 2008. Middle Eocene ostracodes of the Qattamiya area, northwest Eastern Desert, Egypt: Systematics, biostratigraphy and paleobiogeography. Revue de Paléobiologie 27 (1), 123–157. Shama, K., Helal, S., 1993. Stratigraphy of the Eocene sediments at Shabrawet area, Suez Canal Environs, Egypt. Egyptian Journal of Geology 37 (2), 275–298. Trabelsi, K., Sames, B., Salmouna, A., Piovesan, E.K., Ben Rouina, S., Houla, Y., Touir, J., Soussi, M., 2015. Ostracods from the marginal

coastal Lower Cretaceous (Aptian) of the Central Tunisian Atlas (North Africa): paleoenvironment, biostratigraphy and paleobiogeography. Revue de Micropaléontologie 59, 309–331. Van Itterbeeck, J., 2007. Danian/Selandian boundary stratigraphy, paleoenvironment and Ostracoda from Sidi Nasseur, Tunisia. Marine Micropaleontology 62, 211–234. Wade, B.S., Pearson, P.N., 2008. Planktonic foraminiferal turnover, diversity fluctuations and geochemical signals across the Eocene/Oligocene boundary in Tanzania. Marine Micropaleontology 68, 244–255. Whatley, R.C., 1983. The application of Ostracoda to paleoenvironmental analysis. In: Maddocks, R.F. (Ed.), Applications of Ostracoda. University of Houston Geoscience, Houston, pp. 51–77. Whatley, R., Arias, F.C., 1993. Paleogene Ostracoda from the Tripoli basin Libya. Revista Espanola de Micropaleontologia 25 (2), 125–154. Whatley, R.C., Coles, G.P., 1991. Global change and the biostratigraphy of North Atlantic Cainozoic deep water ostracoda. Journal of Micropaleontology 9, 119–132.

Please cite this article in press as: Amami-Hamdi, A., et al., Quantative analysis and paleoecology of Middle to Upper Eocene Ostracods from Jebel Jebil, central Tunisia. Revue de micropaléontologie (2016), http://dx.doi.org/10.1016/j.revmic.2016.10.001