refereed scientific journal ۲٠۱٨ ، لﻭﻷا ﺩﻠﺟﻣﻟا volume 1,...

Africa Journal of GeosciencesAfrica Journal of GeosciencesVolume 1, 2018

مجلة افريقيا لعلوم األرضمجلة افريقيا لعلوم األرض۲٠۱٨المجلد األول ،

Indimi Faculty of Minerals and PetroleumInternational University of Africa

كلية انديمي للمعادن والنفطجامعة افريقيا العالمية

Refereed scientific journalمجلة علمية محكمة

ISSN: 1858-8913 (online), 1858-8905 (hard copy), http://www.iua.edu.sdISSN: 1858-8913 (online), 1858-8905 (hard copy), http://www.iua.edu.sd

98

Africa Journal of Geosciences (AJG) Volume 1, 2018

ISSN: 1858-8913 (online), 1858-8905 (hard copy), http://www.iua.edu.sd

Palynological Evidence of a Campanian-Maastrichtian age of Shendi

Formation, Central Sudan

Eisawi, A.A.M.

Faculty of Petroleum and Minerals, Al Neelain University, P.O. Box 12702, Khartoum, Sudan.

Email: [email protected].

Received: 15 November 2018/ revised: 10 December 2018 / accepted: 13 December 2018

Abstract

This paper presents for the first time, palynological results from the subsurface part of the Shendi Formation, in central Sudan. The study

is based on eight samples of grey mudstones collected from three shallow water wells drilled in Shendi Formation. The recovered

material is characterized by well preserved and fairly diversified miospores in which angiosperm pollen form the major constituent;

gymnosperms and bryophyte/ptridophyte spores are relatively fewer. The coexistence of marker species such as Monocolpopollenites

spheroidites Zlivisporis blanensis, Longapertites sp. 3, Proteacidites sigalii, Echitriporites trianguliformis, Syncolporites schrankii,

Retidiporites magdalenensis indicates a Campanian-Maastrichtian age for the subsurface part of the Shendi Formation. The palynomorph

assemblage encountered herein, is characteristic of the Senonian Palmae province.

Keywords: Palynostratigraphy; spore/pollen; Campanian-Maastrichtian; Shendi Formation; Central Sudan.

1. Introduction

The study area lies within Shendi Basin in the River Nile State,

it covers a strip that extends along the eastern side of the Nile

between Shendi and Umm Ali village (Fig. 1). The Shendi-

Atbara Basin is now considered as an important target for

hydrocarbon exploration in central Sudan. In the last decades,

the increasing demand for energy resources boosts the search for

additional hydrocarbon reserves in intra-cratonic basins. Among

other tools needed to achieve this goal, palynology has been

proved indispensable for age determination and correlation of

subsurface units. Moreover, important conclusions on

paleoecologic and paleoclimatic developments can be drawn

using sporomorph taxa that can be compared to extant plants of

known botanical affinity. Such information is essential for the

prediction of depositional environment and source rock

potentiality.

Although several geological studies have been carried out in the

study area (e.g. Khairalla, 1966; Whiteman, 1971; Bussert,

1993; Wycisk, 1990) the stratigraphic position of Shendi

Formation remains debatable. Hitherto the Shendi Formation is

correlated with the Albian-Cenomanian Omdurman and Wadi

Milk Formations (Wycisk, 1990; Bussert, 1993). This

correlation was primarily based on lithological similarities and

on few, long-range macroflora elements from the outcrops. The

presumed Albian-Cenomanian age of the Wadi Milk Formation

was made based on spores/pollen assemblages recovered from a

number of wells between Wadi Muqadam and Dongola area

(Schrank, 1990). Therefore, the present study aims at providing

a more reliable and accurate age assignment for Shendi

Formation using palynology.

http://www.iua.edu.sd/

mailto:[email protected]

Eisawi /Africa Journal of Geosciences, 01 (2018), 100-104

99

Fig. 1. The location of the studied wells.

2. Material and palynological methods

In this study, eight cutting samples from three shallow water

wells, north of Shendi town have been analyzed for their

palynological content (Fig. 1). The studied successions are

dominated by mudstones of variable colours and thin sandstone

interbeds indicating lacustrine to fluvio-lacustrine depositional

settings.

A routine palynological preparation scheme, which involves

washing of sample, treatment with hydrochloric acid (35%) and

hydrofluoric acid (40%), was followed. Oxidation was not

employed for any of the analyzed material. A target of 150

specimens count has been set, but most of the samples were

proved practically far less productive, therefore, absolute count

has to be made. Processing of palynological samples was carried

out at the Petroleum Laboratories, Researches and Studies

(PLRS) in Khartoum.

3. Palynostratigraphy

The analyzed material from Shendi Basin is dominated by

angiosperm pollen; gymnosperms and spores are relatively less

represented. Palynodebris are dominated by dark brown to black

woods, cuticles, membranous tissues and very little amorphous

matter. Characteristic elements of the Palmae province e. g.

Zlivisporis blanensis, Longapertites sp.3, Retidiporites

magdalenensis and Echitriporites trianguliformis form the bulk

of the recovered sporomorphs. The stratigraphic ranges of these

forms in relevant basins of Northern South America, North and

West Africa are depicted in Figure 2 and discussed in the

following paragraphs.

Previous records of Zlivisporis blanensis has been made from

the Coniacian-Maastrichtian of West Africa basins

(Boltenhagen, 1976; Jan du Chêne et al., 1978 and Salard-

Cheboldaeff, 1990). It has also been reported from the

Maastrichtian of Somalia (Schrank, 1994a), Late Cretaceous of

Nigeria (Beilstein, 1994) and from the Turonian to Early

Maastrichtian of the Sudan (Awad, 1994; Eisawi and Schrank,

2008). The first record of Longapertites sp.3 has been made from

the Campanian-Maastrichtian of Nigeria (Lawal and Moullade,

1986). Schrank (1994b) considered the coexistence of

Echitriporites, Retitriporites, and Longapertites sp.3 to indicate

a Campanian-Maastrichtian age for the sediments in northern

Kordofan, Sudan. Cristaecolpites echinaceus has been reported

for the first time from the Maastrichtian of Somalia and later

from the Campanian–Maastrichtian of the Sudan (Schrank,

1994a; Eisawi and Schrank, 2008). African records of

Foveomonocolpites bauchiensis range from the Maastrichtian of

Somalia and Sudan (Schrank, 1994a; Eisawi and Schrank, 2009)

to the Paleocene of West Africa (Adegoke et al., 1978; Salard-

Cheboldaeff, 1990) and Sudan (Stead and Awad, 2005; Eisawi

and Schrank, 2008). Previous African records of Monocolpites

marginatus range from the Campanian-Maastrichtian of Nigeria

and Sudan (Lawal and Moullade, 1986; Awad, 1994; Eisawi and

Schrank, 2009) to the Paleocene and Eocene of Nigeria

(Adegoke et al., 1978). Periretisyncolpites giganteus is known

from the Maastrichtian of Nigeria (Kieser and Jan Du Chêne,

1979; Edet and Nyong, 1994 and Somalia (Schrank, 1994a), the

Campanian-Maastrichtian of West Africa and Egypt (Salard-

Cheboldaeff, 199; Schrank, 1987) respectively and the

Campanian-Paleocene of Sudan (Kaska, 1989; Eisawi and

Schrank, 2008). The marker species Proteacidites sigalii was

originally described from the Senonian (Coniacian to


100

Maastrichtian) of Gabon (Boltenhagen, 1978) and later reported

from the Coniacian to Maastrichtian of a number of West African

basins (Salard-Cheboldaeff, 1990). Additional records are from

the Campanian–Maastrichtian of Egypt (El Beialy, 1995;

Mahmoud and Schrank, 2007) and the Maastrichtian of Nigeria

(Salard-Cheboldaeff, 1979; Lawal and Moullade, 1986), Egypt

(Sultan, 1985; Schrank, 1987) and Sudan (Awad, 1994; Eisawi

and Schrank, 2008; Eisawi and Schrank, 2009). Previous records

of Retidiporites magdalenensis are from the Maastrichtian of

Nigeria (Lawal and Moullade, 1986), Egypt and Somalia

(Schrank, 1987; Schrank, 1994a), respectively, the Maastrichtian

to Paleocene of Nigeria (Germeraad et al., 1968; Jan du Chêne

et al., 1978) and Sudan (Awad, 1994; Eisawi and Schrank, 2009)

and the interval Maastrichtian to Eocene of the Caribbean

(Germeraad et al., 1968), Colombia (Jaramillo et al., 2007) and

several West African basins (Salard-Cheboldaeff, 1990). The

species was also reported from the? Campanian-Maastrichtian

of Nigeria (Salami, 1990) and the late Campanian-Maastrichtian

of Sudan (Schrank, 1994b). Scabratriporites samoilovitchii was

recorded from the Coniacian-Maastrichtian (Senonian) of

Gabon (Boltenhagen, 1976) and the Maastrichtian of Nigeria

and Sudan (Beilstein, 1994; Eisawi and Schrank, 2009),

respectively. The most abundant and biostratigraphically

important among angiosperm taxa encountered herein is the

Echitriporites trianguliformis which is restricted to the

Campanian-Maastrichtian to Eocene of Sudan (Awad, 1994;

Eisawi and Schrank, 2008), Campanian-Maastrichtian of

Nigeria (Edet, 1992) and Egypt (Schrank, 1987). African records

of Ctenolophonidites costatus range from Maastrichtian of

Somalia (Schrank, 1994a) to the Eocene-Miocene of Cameron

(Salard-Cheboldaeff, 1979).

The combined stratigraphic ranges of the aforementioned

palynomorphs in Africa and northern South America (Fig. 2) and

the absence of earliest Late Cretaceous forms such as

Droseridites senonicus Cretacaeiporites spp., Foveotricolpites

spp., support a Campanian-Maastrichtian age for the subsurface

part of the Shendi Formation.

Fig. 2. The stratigraphic ranges of selected marker species outside the study area.

Age Cretaceous Paleogene

Paleocene Eocene Oligocene

Taxa Turonian ConiacianSantonianCampanianMaastrichtian

Cristaecolpites echinaceous

Echitriporites trianguliformis

Longapertites sp.3

Monocolpite marginatus

Periretisyncolpites giganteus

Proteacidites sigalii

Retidiporites magdalenensis

Ctenolophonidites costatus

Scabratriporite samoilovitchii

Syncolporites schrankii

Zlivisporis blanensis

Late Cretaceous


101

4. Comparison of Shendi material with

neighboring areas

The spores/pollen assemblages encountered herein are

comparable with those recovered from the Maastrichtian

Gedaref Formation (Eisawi and Schrank, 2009) and the youngest

zone (Campanian-Maastrichtian) of North Kordofan (Schrank,

1994b). They are all dominated by angiosperm pollen of the

palmae group. However, some older forms such as

Longapertites sp. 3, which is indicative of the Campanian are

lacking in the Gedaref Formation but are reported in the North

Kordofan material. The pre Campanian form Droseridites

senonicus, characteristic of the Turonian-Santonian (Coniacian)

of Kosti Basin Awad (1994) has not been encountered herein.

5. Conclusions

Well preserved and fairly diversified miospores from the

subsurface strata of Shendi Formation have been encountered in

two shallow wells. The assemblage is dominated by angiosperm

pollen, with minor representatives of gymnosperm pollen and

spores.

Age determination of the studied interval has been made by

comparison of the stratigraphic ranges of the recovered taxa with

their previous records in contemporaneous African and north

South American basins. Accordingly, a Campanian-

Maastrichtian age has been assigned for the subsurface part of

the Shendi Formation. The central Sudan was part of the

Senonian Palmae province as indicated by the occurrence of

characteristic taxa such as Longapertites, Retidiporites,

Echitriporites, Proteacidites within the studied material.

Acknowledgements

The author wishes to thank Al Neelain University for providing

logistics for the field trip. The Petroleum Laboratories,

Researches and Studies (PLRS) in Khartoum is thanked for

preparation of palynological samples.

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103

Plate 1.

Campanian-Maastrichtian Spores and pollen

Fig. 1. Zlivisporis blanensis Pacltova 1961.

Well No. 1, sample 2

Fig. 2. Foveomonocolpites bauchiensis Adegoke & Jan du Chêne 1979.


Fig. 3. Monocolpopollenites spheroidites Jardiné & Magloire 1965

sensu Awad 1994.


Fig. 4. Retimonocolpites retifossulatus Lorente 1986.


Fig. 5. Spinizonocolpites kostinensis Awad 1994.


Fig. 6. Spinizonocolpites baculatus Muller 1968.


Fig. 7. Tubistephanocolpites cylindricus Salami 1984.


Figs. 8 and 22. Proteacidites sigalii Boltenhagen 1978 sensu Kaska

1989.



Fig. 9. Scabratriporites Samoilovtichii Boltenhagen 1976.


Fig. 10. Proxapertites operculatus Van der Hammen 1956.


Fig. 11. Retidiporites magdalenensis Van Der Hammen & Garcia De

Mutis 1966.


Fig. 12. Ladakhipollenites lehmanii (Boltenhagen) Schrank 1994a.


Fig. 13. Gemmatricolpites cf. pergemmatus Muller 1968.


Fig. 14. Gabonisporis vigourouxii Boltenhagen 1967.


Fig. 15. Periretisyncolpites cf.giganteus Kieser & Jan du Chêne 1979.


Fig. 16. Cristaecolpites echinaceus Schrank 1994.


Fig. 17. Monocolpites marginatus Van der Hammen 1954.


Fig. 18. Echitriporites trianguliformis Van Hoeken-Klinkenberg 1964.


Fig. 19. Syncolporites schrankii Awad 1994.


Fig. 21. Gliecheniidites senonicus Ross 1949.


Fig. 23. Longapertites microfoveolatus Jan Du Chêne and Adegoke in

Adegoke et al. 1978.

Well No. 3, sample 3.

Fig. 24. Ctenolophonidites coststus (Van Hocken-Klinkenberg1964)

Van Hocken-Klinkenberg1966.


Fig. 25. Longapertites sp.3.



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