Agglutinated Middle-Upper Eocene foraminifera in Jabal Hafit, Al ...

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18 H. S. ANAN III. STRATIGRAPHY The disappearance of the Middle Eocene spinose planktic foraminiferal genera (Truncorotaloides, Morozovella, Acarinina) is taken by many authors (i.e. TOUMARKINE & LUTERBACHER, 1985) to mark the Middle/Upper Eocene boundary and drawn between the Truncorotaloides rohri Zone (P14) and the Globigerinatheka semiinvoluta Zone (P15). The codified zones of BLOW (1969) are used here. The Late Eocene Turborotalia pseudoampliapertura Zone was introduced by HAGGAG (1990) to separate the Truncorotaloides rohri Zone (P14) from the Globigerinatheka semiinvoluta Zone (P15). STROUGO (1992) proposed to draw the base of the Upper Eocene at the base of the G. semiinvoluta Zone thus relegating the T. pseudoampliapertura Zone to the latest Middle Eocene (the latter zone is marked here by the proposed coded no. P14/15). This stratigraphical opinion was adopted by ANAN et al. (1992), ANAN (1994b, 2003) and this study. The section under investigation (the Tle5 succession) is represented by four planktic foraminiferal biozones, from base to top : the upper part of the Middle Eocene Truncorotaloides rohri Zone (P14) and Turborotalia pseudoampliapertura Zone (P14/15) and the Late Eocene : Globigerinatheka semiinvoluta Zone (P15) and Cribrohantkenina inflata Zone (P16). The phosphatic limestone bed (bed no.9, Fig. 2 ; about 25 m thick) represents the passage interval between the Middle and Upper Eocene succession in the study section. IV. TAXONOMY Fifteen diagnostic and well-preserved small agglutinated foraminiferal species are identified in the study section. Ten of them are illustrated here (Plate I), while another three species Orbulinelloides arabicus, Marssonella hafitensis and Plectina emiratensis were recently illustrated in ANAN (2003) as new species. The stratigraphic ranges of the identified species are shown in Fig. 3. Order Foraminiferida EICHWALD, 1830 Suborder Textulariina DELAGE & HEROUARD, 1896 Superfamily Astrorhizacea BRADY, 1881 Family Bathysiphonidae AVNIMELECH, 1952 Genus Bathysiphon SARS, 1872 Type species : Bathysiphon filiformis SARS, 1872 Bathysiphon eocenicus CUSHMAN & HANNA, 1927 Pl. I, fig. 1 1927. Bathysiphon eocenica CUSHMAN & HANNA ,p. 210, p1. 13, figs 2, 3. 1951. Bathysiphon eocenica CUSHMAN & HANNA. - CUSHMAN & STAINFORTH, p. 142, p1. 25, fig. 4. 1975. Bathysiphon eocenicus CUSHMAN & HANNA. - BRAGA & GRÜNIG, p. 102, fig. 5. 1994. Bathysiphon eocenicus CUSHMAN & HANNA. - BOLLI et al., p. 65, fig. 18.3. 1996. Bathysiphon eocenica CUSHMAN & HANNA.- ANAN, p. 149, fig. 3.1. Fig. 2 : Schematic diagram of the study section, Tle5 (the lower part of Mazyad Member, Dammam Formation), eastern limb of Jabal Hafit.
Agglutinated Middle-Upper Eocene foraminifera in Jabal Hafit, Al Ain area 19 Fig. 3 : The stratigraphic ranges of the identified M/U Eocene agglutinated foraminiferal species. 1997. Bathysiphon eocenica CUSHMAN & HANNA. - HUSSEIN, p. 108, fig. 3.1. 2000. Bathysiphon sp. 2 - ABUL-NASR, p. 72, fig. 16.5. The species was originally described from the Eocene of California, USA. It is also recorded from the Eocene of Ecuador (CUSHMAN & STAINFORTH, 1951), Italy (BRAGA & GRÜNIG, 1975), Trinidad (BOLLI et al., 1994) and Egypt (ANAN, 1994b ; HUSSEIN, 1997). This species was recorded in the Early Eocene (P9) of Jabal Hafit by ANAN (1996). It occurs also in the Middle and Upper Eocene (P14-P16) of Jabal Hafit in the study section. Bathysiphon eocenicus has a cosmopolitan geographic distribution. Bathysiphon saidi (ANAN, 1994) Pl. I, fig. 2 1994b. Rhabdammina saidi ANAN, p. 218, fig. 8.1 1997. Bathysiphon abbassi HUSSEIN, p. 109, fig. 3.2. 2000. Bathysiphon sp.1 - ABUL-NASR, p. 72, fig. 16.4. The species is regarded here to belong to the genus Bathysiphon due to its straight unbranched elongate tube and wider stratigraphic range (Up. Triassic-Holocene) than the restricted Holocene time of the genus Rhabdammina SARS, 1869 (LOEBLICH & TAPPAN, 1988, p. 24). Bathysiphon saidi differs from B. eocenicus in having rough agglutinated surface with cemented coarse fragmented sand grains. On the other hand, the coarsely agglutinated sand grains B. abbassi of HUSSEIN (1997) and also B. sp.1 of ABUL-NASR (2000) closely conspecific with B. saidi (ANAN, 1994b). Bathysiphon saidi was originally described from the top Middle - Upper Eocene of Egypt, while it is recorded only from the top Middle Eocene (P 14) of Jabal Hafit. Family Saccamminidae BARDY, 1884 Subfamily Thurammininae A. D. MIKLUKHO-MAKLAY, 1963 Genus Orbulinelloides SAIDOVA, 1975 Type species : Orbulinoides agglutinatus SAIDOVA, 1970 Orbulinelloides arabicus ANAN, 2003 2003. Orbulinelloides arabicus ANAN, p. 531, fig. 4.1. This species is characterized by its spherical to subspherical coarsely agglutinated test. It occurs in the top Middle Eocene (P14) to middle Late Eocene (P16) of Jabal Hafit. Superfamily Rzehakinacea CUSHMAN, 1933 Family Rzehakinidae CUSHMAN, 1933 Genus Miliammina HERON-ALLEN & EARLAND, 1930 Type species : Miliolina oblonga (MONTAGU) var. arenacea CHAPMAN, 1916 Miliammina kenawyi ANAN, 1994 Pl. I, fig. 3 1994b. Miliammina kenawyi ANAN, p. 218, fig. 8.2. The species is characterized by its fine agglutinated smooth wall in loose quinqueloculine arrangement with half coil chambers. It was originally described from the top Middle Eocene (P14) to early Late Eocene (P15) of Egypt. This species is recorded only in the top Middle Eocene (P14/15) of Jabal Hafit.
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