Ordovician–Carboniferous Palynology of El-Waha-1 Borehole, Western Desert, Egypt
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Indian Journal of Geo-Marine Sciences Vol. 43(8), August 2014, pp. 1484-1499 Ordovician–carboniferous palynology of el-waha-1 borehole, western desert, Egypt Moustafa, T.F1, Gamal M. A. Lashin,2 Hosny A.M.3& El-Shamma A. A1 1Egyptian Petroleum Research institute Zagazig University, Egypt 2Botany Department, Faculty of Sciences, Zagazig University, Egypt 3Geology Department, Faculty of Sciences, El -Azhar University, Egypt (E-mail: [email protected]) Received 9 September 2012; revised 25 February 2014 Diverse acritarchs, chitinozoa, and miospore assemblages were recovered from the Paleozoic sequence in El-Waha -1 well, north western part of the Western Desert. Assemblages have many previously described forms known from the Paleozoic strata in north Gondwana and other parts in the world. The study revealed that the sedimentation was repeatedly interrupted , as is confirmed by stratigraphic breaks. It revealed also that the Ordovician assemblage as well as the lower part of the Silurian are composed mainly of acritarchs, less chitinozoans and no miospores have been recorded. Real sporomorphs are recorded only at the upper part of the Silurian with smooth spores (Retusotriletes, Ambietisporites, Archaeozonotriletes), verrucates ones, and Emphanisporites with poorly defined ribs. Early Devonian is characterized by zonate – camerate, pseudosaccate, a relatively simple spore types and verrucate ones, that is beside a considerable increase in diversity of the phytoplankton. Middle Devonian shows the first incoming of small sculptured camerate spores with thick exospores wall and large spinate forms related to genera Hystrichospora, Grandisporites and Ancyrosporites. Early Carboniferous is dominated by vascular plant taxa (Ferns) including laevigate, cingulizonate and cavate forms. No saccate pollen grains (Gymnosperms) have been recorded in the studied interval. [Keywords: Carboniferous –Ordovician- El-Waha-1-Palynology, Western Desert, Egypt.] Introduction from three wells in the Western Desert. Present study Whilst the Mesozoic and Cenozoic rocks of Egypt may consider a continuous trial to shed light about the have been studied in detail because of their economic palynological characteristics of this mistrial significance, the Paleozoic rocks have received little succession through the data available from El-Waha-1 attention and therefore, the least understood sequence well located in the north western part of the Western in the area. These rocks have sporadic faunal Desert. assemblage which are not useful in age dating, that is The regional distribution of the Paleozoic strata in why palynology became urgent useful in dating and Egypt shows that there is a thick sequence of strata in solving the correlation problem for this part of the north west Egypt and a thinner sequence in the Gulf Western Desert. The earlier palynological studies in of Suez, Sinai area and south west Egypt. Until Egypt have been initiated on the Gulf of Suez and recently, the Paleozoic strata of southwest Egypt were Sinai and have concentrated in the Carboniferous undifferentiated due to insufficient stratigraphical rocks1. In the Western Desert, only few previous evidence. Ordovician strata are identified in Karkor works on the subsurface Paleozoic palynology were Talh in the northeastern part of Gebel Oweinat and carried out. The work of1 may consider the most the Egyptian–Sudan border. This consists of shallow extensive one. They established 15 biozones based on marine sandstone directly above Precambrian palynomorph assemblage ranging in age from Middle basement7. It is unconformably overlain by sandstone Cambrian to Early Permian.2 identified three of Silurian age. The Silurian is reported from the assemblages belonging to Silurian, Givetian and subsurface of the north Western Desert by8,3. As in Visean from Foram-1 well3,4. recognized five broad- Ordovician time, Egypt was during the Silurian near based palynological units ranging in age from Early the eastern edge of the sea which covered a large area Visean to Early Permian in two wells (NWD - 302-1 of north Africa and reached its maximum extension and Faghur-1) located in the north Western Desert5 during Llandoverian time. This sea seems to have established 10 assemblage zones ranging in age from transgressed into the south west, west and northwest the Lower Devonian to the lowermost Carboniferous Egypt. Devonian subsurface strata in northwest Egypt MOUSTAFA et al: EL-WAHA-1 BORE HOLE WESTERN DESERT, EGYPT 1485 were recorded by8,4. through the palynological works. A-Siwa Group (Early –Mid. Cambrian–Late Silurian) Environment is at least partly marine with a 1-Shifah Formation (Mid. Cambrian–Mid. southward increase of continental influence. Ordovician) Devonian sediments of western Abu Ras Plateau and 2-Kohla Formation (Late -Llandoverian-Ludlovian) of northeast Gebel Oweinat are compared with the 3-Basur Formation (Mid–Late Ludlovian) Tadrat Sandstone Formation of Libya. It's certainly a B-Faghur Group (Early Devonian–Early Permian) fluviatile sediment deposited in the southern and eastern to southeastern foreland of one (or several) 1-Zeitun Formation ( Gedinnian–Late Devonian) Devonian transgressions. Carboniferous sediment 2-Desouqy Formation (Tournaisian–Visean) strata of Egypt differ in facies, and range from fully 3-Dhiffah Formation (Late Visean–Late Namurian) marine carbonate, shale and deep marine clastics, 4-Safi Formation (Late Namurian–Early Permian) deltaic and continental fluviatile sandstone to lacustrine and fluvio- glacial deposits. This may due Materials and Methods to the structural development of that time. Until late One hundred twelve (112) Ditch samples were Visean or Namurian, Egypt was at the southern edge obtained from El-Waha-1 well located in the of a more or less shallow sea which transgressed parts northwestern part of the Western Desert. Samples of the country7. At the same time northward draining cover the sequence spanning time interval from the rivers from surrounding areas in the south and Ordovician to Carboniferous (Fig. 1). Samples have southeast filled depressions with fluviatile sediments. been subjected to the standard technique of Most applicable lithostratigraphic subdivision for the preparation using HF, Hcl and Zn I2 as a heavy liquid 10 Paleozoic sequence in the Western Desert we use here separation . is that adopted by9. This classification seems to be acceptable by Egyptian General Petroleum Results And Discussion Corporation (EGPC) and Oil Companies and includes Palynostratigraphy two formal lithostratigraphical groups. They can also Palynomorphs taxa include (acritarchs, chitinozoan be readily subdivided into formations on the basis of and miospores) have been recorded and identified gross lithology: from all studied samples (Plates 1-5). This preliminary Fig. 1Location map (A) and stratigraphic log of EL-Waha-1 well (B). 1486 INDIAN J. MAR. SCI., VOL. 43, NO. 8, AUGUST 2014 PLATE IFig. 1: Rhabdosporites minutes (Balme) Playford. Fig. 2: Cymbosporites proteus McGregor & Camfield. Fig. 3: .verrucatus Richardson & Ioannides. Fig, 7: Archaeozonotriletes spﺍﻝﻑﻥﺍﻥﺓ ﺍﻝﻝﺏﻥﺍﻥﻱﺓ ﺭﺯﺍﻥ ﺍﻝﻡﻍﺭﺏﻱ .Stenozonotriletes simplex Naumova. Fig Fig. 8: Aneurospora sp. Fig. 9: Dibolisporites sp. Fig. 10: Retusotriletes cf. communis Naumova. Fig. 11: Dibolisporites eiflelinsis (Lanninger) McGregor. Fig. 12: Synorisporites Lybicus. Richardson & Ioannides. Fig.13: Apiculiretusisporites plicata (Allen) Streel. Fig. 14: Craspedispora sp. Fig. 15: Brockotriletes sp. Figs. 16, 22: Emphanisporites rotatus McGregor. Fig. 17: Emphanisporites erruticus Eisenack. Figs. 18, 19: Dictyotriletes emsiensis (Allen) McGregor. Fig. 20: Emphanisporites sp. Fig. 21: Emphanisporites annulatus McGregor. Figs. 23, 24: Emphanisporites spinaeformis Schultz. Fig. 25: Emphanisporites abscurus McGregor. Fig. 26: Verrucosisporites scurrus (Naumova) McGregor & Camfield. Fig. 27: Lophozonotriletes sp. MOUSTAFA et al: EL-WAHA-1 BORE HOLE WESTERN DESERT, EGYPT 1487 PLATE IIFig. 1: Brockotriletes hudsonii McGregor & Camfield. Fig. 2: Dictyotriletes emsiensis (Allen) McGregor. Fig. 3 Endosporites micromanifestus Hacquebard. Fig. 4: Hymenozonotriletes discors Chibrickova. Fig. 5: Comptozonotiletes caperatus McGregor. Fig. 6: Spelaeotriletes cf. crustatus Higgs. Fig. 7: Geminospora lemurata (Balme) Playford. Fig. 8: Verrucosisporites polygonalis Lanninger. Fig. 9: Apiculiretusisporites brandti Streel. Fig. 10: Grandispora protea (Naumova) Moreau Benoit. Fig. 11: Ancyrospora acutispinosa Chi & Hills. Fig. 12: Ancyrospora longispinosa Richardson. Fig. 13: Grandisporites libyensis Moreau Benoit. Fig. 14: Grandispora inculta Allen. Fig. 15: Camarozonotriletes sp. Fig. 16: Diatomozonotriletes sp. Fig. 17: Synoriporites papillensis McGregor. Fig. 18: Verrucosisporites premnus Richardson. Fig. 19: Aratrisporites sahariensis Loboziak & Alpern. Fig. 20: Rugospora flexuosa (Jushko) Streel. Fig. 21: Dipolisporites echinaceus (Eisenack) Richardson. Fig. 22: Verrucosisporites nitidus (Naumova) Playford. 1488 INDIAN J. MAR. SCI., VOL. 43, NO. 8, AUGUST 2014 PLATE IIIFig. 1: Spelaeotriletes owensi Loboziak & Alpern. Fig. 2: Vallatisporites agadesi Loboziak & Alpern. Fig. 3: Spelaeotriletes triangulus Neves & Owens. Fig. 4: Radiizonates genuinus Loboziak & Alpern. Fig. 5: Vallatisporites pusillites (kedo) Dolby & Neves. Fig. 6: Vallatisporites verrucosus Playford. Fig. 7: Spelaeotriletes benghaziensis Loboziak & Alpern. Fig. 8: Spelaeotriletes arenuceus Neves & Owens. Fig. 9: Umbonatisporites sp. Fig. 10: Retusotriletes