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

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22 H. S. ANAN The species was recorded from the Paleocene to Middle Eocene of Italy (PROTO DECIMA & de BIASE, 1975) and from the Lower Eocene of Norwegian Sea, DSDP Site 338 (HULSBOS et al., 1989). It occurs in the top Middle Eocene (P14 and P14/15) of Jabal Hafit. V. TEMPORAL DISTRIBUTION AROUND M/U EOCENE BOUNDARY According to many authors (ex. VAIL et al., 1977 ; HAQ et al., 1987) a marked fall in the eustatic sea level took place at the end of the Middle Eocene (39-40 Ma). This global regression may also has taken place in the Al Ain area. It may caused the deposition of the phosphatic limestone bed (bed no. 9, Fig. 2 ; about 25 m thick), which represents the passage interval between the Middle and Upper Eocene succession in the study section. Previously, ABUL-NASR & THUNELL (1987) noted that the concentration of clastic phosphatic sediment being a function of reworking during times of lowered sea level. The temporal distribution of the fifteen identified species in the Middle-Upper Eocene succession of the study section is shown in Fig. 3. The following remarks are presented : 1. The diversity of the identified species gradually decreases upward throughout the M/U Eocene succession. About 87 % of the identified species (13/15 species) are recorded in the Middle Eocene compared to 53 % (8/15 species) in the Late Eocene. It is interesting to note that the M/U Eocene boundary in Egypt (ANAN, 1994b) is also marked by a sudden fall in abundance and/or diversity of the foraminiferal assemblage. 2. Seven out of the identified species are recorded only from the Middle Eocene zones (P14 and P14/15). These species are : Ammobaculites cubensis, Bathysiphon saidi, Haplophragmoides walteri, Miliammina kenawyi, Plectina emiratensis and Textularia plummerae, T. communis. 3. Two species Tritaxia alpina and Vulvulina jarvisi are restricted to the Late Eocene (P15 and P16). 4. Six out of thirteen Middle Eocene species continue into the Late Eocene (P15 and P16). These are : Bathysiphon eocenicus, Dorothia nacataensis, Marssonella hafitensis, Orbulinelloides arabicus, Spiroplectinella nuttalli and Vulvulina haeringensis. 5. Four species B. eocenicus, O. arabicus, M. hafitensis and D. nacataensis, among other species, have a long ranged throughout the M/U Eocene horizon, and represent the Tle5 succession. VI. PALEOBIOGEOGRAPHY AND PALEOECOLOGY The paleogeographic reconstruction maps of MOORE et al. (1978) and ZACHOS et al. (1993) for the Middle-Late Eocene show that the Tethyan realm extended to the southeast and had been connected with the Indo-Pacific realm via a seaway separating Arabia from Iran-India region. At that time, the North America and South America were separated and the Atlantic and Pacific realms connected by another seaway. On the other hand, CHERIF & EL DEEB (1984) noted that close to the end of the Middle Eocene the previously arid climates became markedly wetter and seems also to have been accompanied by a cooling of the water temperature. They also suggested that the climatic changes inferred from the Hafit area seem to have been widespread, at least in parts of the Middle East. KELLER et al. (1987) noted that the Middle/Late Eocene boundary is marked by expansion of cooler water assemblages and a major extinction event among warmer water species involving 80 % of the individuals of the population, or 23 % of the species population. Table I shows the identified fifteen agglutinated foraminiferal species in the Middle-Upper Eocene succession from Jabal Hafit, as well as, the other recorded species from Egypt, Italy, Caribbean region and Ecuador by different authors. The following remarks can be presented : 1. The study section yields 15 agglutinated foraminiferal species around the M/U Eocene boundary, compared to 13 species from Egypt, 19 from Italy, 17 from Caribbean region and 13 species from Ecuador (Pacific realm). 2. Seven species : Ammobaculites cubensis, Bathysiphon eocenicus, B. saidi, Haplophragmoides walteri, Miliammina kenawyi, Spiroplectinella nuttalli and Textularia communis are recorded from both Jabal Hafit (UAE) and Egypt in one hand, while only four species Ammobaculites cubensis, A. subglabra, Bathysiphon eocenicus and Textularia recta are recorded from both Egypt and Italy (Tethyan realm) in the other hand. 3. Eleven species Dorothia colei, D. nipeenis, Gaudryina pseudocollins, Haplophragmoides emaciatus, Karreriella hantkeniana, K. subcylindrica, Lituotuba navetensis, Martinottiella petrosa, Plectina dalmatina, Pseudoclavulina trinitatensis and Spiroplectammina trinitatensis are endemic to Caribbean region. 4. Three species Ammobaculites cubensis, Bathysiphon eocenicus and Haplophragmoides emaciatus are recorded in both the Tethyan and Caribbean regions. 5. Two species Ammodiscus incertus and Bathysiphon eocenicus are recorded from both the Caribbean region and Ecuador. 6. Only one species Spiroplectinella nuttalli is recorded in UAE, Egypt and Ecuador.
Table I : Middle/Upper Eocene agglutinated foraminiferal species in Jabal Hafit (UAE), Egypt, Italy, Caribbean region and Ecuador. sp. no. Agglutinated Middle-Upper Eocene foraminifera in Jabal Hafit, Al Ain area 23 AGGLUTINATED FORAMINIFERAL SPECIES AROUND THE M/U EOCENE BOUNDARY IN JABAL HAFIT(UAE) AND OTHER LOCALITIES (1) (2) (3) (4) (5) 1 Ammobculites cubensis CUSHMAN & BERMUDEZ, 1937 x x x x - 2 subglabra (GÜMBEL, 1898) - x x - - 3 Ammodiscus glabratus CUSHMAN & JARVIS, 1928 - - x - - 4 incertus (dʼORBIGNY, 1839) - - - x x 5 Ammospirata mexicana (CUSHMAN, 1933) - - - - x 6 Ammovertella retrorsa CUSHMAN & STAINFORTH, 1945 7 Bathysiphon eocenicus CUSHMAN & HANNA, 1927 x x x x x 8 saidi (ANAN, 1994) x x - - - 9 samanica (BERRY, 1928) - - - - x 10 Cyclamina acutidorsata (HANTKEN, 1975) - - x - - 11 cf. pacifica BECK, 1943 - - - - x 12 Cylindroclavulina colomi HANG,1956 - - x - - 13 Dorothia colei (NUTTALL, 1932) - - - x - 14 fallax HANG,1954 - - x - - 15 nacataensis (WHITE, 1929) x - - - - 16 nipeensis KEIJZER, 1945 - - - x - 17 traubi HANG, 1956 - - x - - 18 Gaudryina jacksonensis CUSHMAN, 1926 - - - x - 19 pseudocollins CUSHMAN & STAINFORTH, 1945 - - - x - 20 Glomospira charoidescorona CUSHMAN & JARVIES,1928 - - x - - 21 Haplophragmoides carinatum CUSHMAN & RENZ, 1941 - - x - x 22 emaciatus BRADY, 1908 - x - x - 23 cf. hetha BERRY, 1932 - - - - x 24 subglobosus SARS, 1868 - x - - - 25 walteri (GRZYBOWSKI, 1868) x - - - - 26 Karreriella hantkeniana CUSHMAN, 1936 - - - x - 27 subcylindrica (NUTTALL, 1928) - - - x - 28 Lituotuba navetensis CUSHMAN, & RENZ, 1948 - - - x - 29 Marssonella hafitensis ANAN, 2003 x - - - - 30 Martinottiella petrosa (CUSHMAN & BERMUDEZ, 1937) - - - x - 31 Miliammina kenawyi ANAN, 1994 x x - - - 32 Orbulinelloides arabicus ANAN, 2003 x - - - - 33 Plectina dalmatina (SCHBERT, 1911) - - x - - 34 emiratensis ANAN, 2003 x - - - - 35 nuttalli CUSHMAN & STAINFORTH, 1951 - - - - x 36 trinitatensis CUSHMAN & RENZ, 1948 - - - x - 37 Psammosphaera eocenica CUSHMAN & STAINFORTH, 1951 - - - - x 38 Pseudoclavulina trinitatensis CUSHMAN & RENZ, 1948 - - - x - 39 Spiroplectammina eocenica (CUSHMAN & BARKSDALE, 1930) - - - - x 40 trinitatensis CUHSMAN & RENZ,1948 - - - x - 41 Spiroplectinella nuttalli (LALICKER, 1935) x x - x x 42 Techanitella archaeonitida STAINFORTH & STEVENSON, 1964 - - - - x 43 Textularia communis (dʼORBIGNY, 1926) x x - - - 44 concava KARRER, 1884 - x - - - 45 fahmyi ANAN, 1994 - x - - -
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