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ABSTRACT

Diverse and well-preserved acritarchs have been recovered from Qalibah Formation of Llandovery-Ludlow age, from well Kahf-1 drilled in northwestern Saudi Arabia. One new genus and 8 new species are described and illustrated: Baltisphaeridium qusaibaense sp. nov., Dictyotidium callum sp. nov., Duvernaysphaera siderea sp. nov., Eupoikilofusa tenua sp. nov., Geron ludlovensis sp. nov., Membranites minutus gen. et sp. nov., Muraticavea irregularis sp. nov., Proteolobus cylindrus sp. nov., and Veryhachium? owensii sp. nov. Two new combinations are proposed: Eupoikilofusa punctalirella comb. nov. and Eupoikilofusa rhikne comb. nov. Ludlow age acritarchs were encountered from the uppermost Sharawra Member. Unlike in the reference sections, the palynofacies and lithofacies of the Sharawra Member indicate an offshore environment. The presence of fresh-water algae with marine palynomorphs in the upper Sharawra Member indicates a fresh-water influx into the marine system.

INTRODUCTION

Acritarchs are acid-resistant, organic-walled marine microfossils that can be recovered in abundance from core chips and ditch cuttings. They have useful biostratigraphic and palynofacies applications, especially for the Early Palaeozoic where they reached their maximum diversity and abundance. Diverse and well-preserved acritarchs, including many new taxa have been recovered from well Kahf-1 (Figure 1) drilled in northwestern Saudi Arabia.

Figure 1:

Palaeozoic outcrops on the Arabian Peninsula, and the location of the Kahf-1 well discussed in this study.

Figure 1:

Palaeozoic outcrops on the Arabian Peninsula, and the location of the Kahf-1 well discussed in this study.

The Silurian of Saudi Arabia is represented by the Qalibah Formation and the lower part of the Tawil Formation. Only the former is considered in this study. The Qalibah Formation as defined by Mahmoud et al. (1992) is composed of two members: the older Qusaiba Member, composed of offshore shale and the younger Sharawra Member consisting of pro-deltaic siltstone and sandstone. In the studied section in well Kahf-1, there is a facies change in the Sharawra Member to more offshore shale deposition.

The aim of this paper is to document and formally describe one new genus and 8 new species from the many new taxa encountered in this well. The biostratigraphy and palaeoecology of the Sharawra Member is briefly discussed.

SYSTEMATIC PALYNOLOGY

Group Acritarcha Evitt, 1963
Genus Baltisphaeridium Eisenack, 1958 ex Eisenack, 1959 emend Eisenack, 1969 

Type species: Baltisphaeridium longispinosum (Eisenack, 1931 ex O. Wetzel, 1933) Eisenack, 1969.

Baltisphaeridium qusaibaense sp. nov. (Plate 1: a)

Holotype: Kahf-1 well, 5,450.0 ft, slide 300A1, Q39/4 (Plate 1: a).

Locus typicus and stratum typicum: Kahf-1 well, 5,450.0 ft, Telychian, Qusaiba Member of the Qalibah Formation.

Derivation of name: After the Qusaiba Member of the Qalibah Formation, type horizon of this species.

Description: The vesicle is spherical to sub-spherical, 30-35 μm in diameter, thick-walled, smooth to micro-granulate and bearing five to twelve long processes. The processes are heteromorphic and thin-walled, except proximally where a long and thick plug prevents communication with the vesicle interior. They range from 16 to 33 μm in length, and the proximal plug ranges from 6 to 12 μm in length. Distally they are mostly simple and at least one is branched. The method of excystment is not apparent. Measurements are based on 5 specimens.

Remarks: This species is distinguished by a long proximal plug, up to one-third of the process length. It differs from Baltisphaeridium diabolicumLe Hérissé et al., 1995, in having more processes and more importantly in lacking the spinose ornamentation.

Genus DictyotidiumEisenack, 1955 emend Staplin, 1961 

Type species: Dictyotidium dictyotum (Eisenack) Eisenack, 1955.

Dictyotidium callum sp. nov. (Plate 1: b, c)

Holotype: Kahf-1 well, 4,926.7 ft, slide 167A2, F41/1 (Plate 1: b, c).

Locus typicus and stratum typicum: Kahf-1 well, 4,926.7 ft, Aeronian-Telychian, Qusaiba Member of the Qalibah Formation.

Derivation of name: From the Latin, callum, thick in reference to the thick wall.

Description: The vesicle is spherical to sub-spherical, 25-35 μm in diameter. The wall is relatively thick and often folded. The surface of the vesicle is reticulate, divided by low ridges into numerous indistinct polygons, 3-5 μm across. The method of excystment is not apparent. Measurements are based on 15 specimens.

Remarks: This species is distinguished by its small size and indistinct polygons. It is similar to Dictyotidium amydrum (Tappan and Loeblich, 1971) Eisenack et al., 1979, in regard to the commonly folded vesicle and in having small and relatively indistinct polygons. However, the latter differs in having rather smaller polygons, 2-3 μm, a larger vesicle diameter, 45-71 μm and a simple rupture of the vesicle as a method of excystment. Dictyotidium dictyotum (Eisenack) Eisenack, 1955, has a greater diameter, 60-100 μm and distinct ridges and Dictyotidium perlucidumLe Hérissé, 1989, falls within the size range of this species but it has a very thin wall.

Genus DuvernaysphaeraStaplin, 1961 emend Deunff, 1964 

Type species: Duvernaysphaera tenuicingulataStaplin, 1961.

Duvernaysphaera siderea sp. nov. (Plate 1: d)

Holotype: Kahf-1 well, 5,240.0 ft, slide 266A5, N39/4 (Plate 1: d).

Locus typicus and stratum typicum: Kahf-1 well, 5,240.0 ft, Telychian, Qusaiba Member of the Qalibah Formation.

Derivation of name: From the Latin name sidereus, star-like.

Description: Duvernaysphaera species with polygonal to star-like outline formed by several processes. Processes are conical with acuminate distal termination, hollow, widening proximally to form a poorly defined vesicle. The vesicle is hollow, communicates freely with processes and ranges from 40-60 μm in diameter. The proximal width of the processes ranges from 5-10 μm and the length ranges from 7-15 μm. A very thin membrane is irregularly surrounding the processes and extending beyond the distal ends of the processes. The surface of the vesicle, processes and membrane is smooth to wrinkled. Although it has the tendency to follow the polygonal vesicle, the overall outline is uneven due to the irregular membrane. The method of excystment is not apparent. Measurements are based on 7 specimens.

Remarks: This species differs from the polygonal forms of Duvernaysphaera angelaeDeunff, 1964, in having longer processes and the membrane extends beyond their distal ends.

Genus EupoikilofusaCramer, 1970 

Type species: Eupoikilofusa striatifera (Cramer, 1964) Cramer, 1970.

Remarks: The genus Eupoikilofusa can be distinguished from other fusiform acritarchs in being ornamented with striate elements that are parallel to the longitudinal axis. The following species have this type of ornamentation and are transferred: Eupoikilofusa punctalirella comb. nov. (Basionym: Leiofusa punctalirellaLoeblich, 1970, p. 725, figures 19 A-D) and Eupoikilofusa rhikne comb. nov. (Basionym: Leiofusa rhikneLoeblich, 1970, p. 726, figures 19 E-I).

Eupoikilofusa tenua sp. nov. (Plate 2: b, c)

Holotype: Kahf-1 well, 3,373.6 ft, slide 127A4, V31/0 (Plate 2: b).

Locus typicus and stratum typicum: Kahf-1 well, 3373.6 ft, Wenlock, Sharawra Member of the Qalibah Formation.

Derivation of name: From the Latin name tenuis, thin, slim in reference to the overall shape.

Description: The vesicle is elongate, fusiform in outline. The total length, including processes, ranges from 250-340 μm, width ranges from 15-22 μm. The wall of the body is ornamented with fine striations parallel to the longitudinal axis which decrease towards the poles without a distinct point of transition. At each pole there is a simple, hollow, laevigate process, not delineated from the body. The longitudinal axis is usually straight. The method of excystment is not apparent. Measurements are based on 5 specimens.

Remarks: Eupoikilofusa tenua sp. nov. differs from other Eupoikilofusa species in being much longer. The nearest species to be compared with however, is E. rhikne comb. nov. which has a maximum length of 242 μm. Moreover, E. striatifera var. striatifera (Cramer and Diez, 1972) Fensome et al., 1990, usually has a curved axis. The long varieties of E. striatifera and E. missurensis Cramer and Diez, 1972, have well delineated processes from the vesicle body.

Plate 1:

Figured material is housed in the Palaeontological Collections of the Natural History Museum, London. Well names and sample depths are followed by slide numbers, England Finder co-ordinates and Museum Collection Number.

  • (a) Baltisphaeridium qusaibaense sp. nov., holotype, Kahf-1 well, 5,450.0 ft, slide 300A1, Q39/4, FA 106.

  • (b) Dictyotidium callum sp. nov., holotype, Kahf-1 well, 4,926.7 ft, slide 167A2, F41/1, FA 107.

  • (c) Dictyotidium callum sp. nov., Kahf-1 well, 4,926.7 ft, slide 167A2, FA 108.

  • (d) Duvernaysphaera siderea sp. nov., holotype, Kahf-1 well, 5,240.0 ft, slide 266A5, N39/4, FA 109.

  • (e) Geron ludlovense sp. nov., holotype, Kahf-1 well, 2,485.5 ft, slide 118A2, S33/4, FA 110.

  • (f) Muraticavea irregularis sp. nov., holotype, Kahf-1 well, 2,690.0 ft, slide 262A2, S43/0, FA 111.

Plate 1:

Figured material is housed in the Palaeontological Collections of the Natural History Museum, London. Well names and sample depths are followed by slide numbers, England Finder co-ordinates and Museum Collection Number.

  • (a) Baltisphaeridium qusaibaense sp. nov., holotype, Kahf-1 well, 5,450.0 ft, slide 300A1, Q39/4, FA 106.

  • (b) Dictyotidium callum sp. nov., holotype, Kahf-1 well, 4,926.7 ft, slide 167A2, F41/1, FA 107.

  • (c) Dictyotidium callum sp. nov., Kahf-1 well, 4,926.7 ft, slide 167A2, FA 108.

  • (d) Duvernaysphaera siderea sp. nov., holotype, Kahf-1 well, 5,240.0 ft, slide 266A5, N39/4, FA 109.

  • (e) Geron ludlovense sp. nov., holotype, Kahf-1 well, 2,485.5 ft, slide 118A2, S33/4, FA 110.

  • (f) Muraticavea irregularis sp. nov., holotype, Kahf-1 well, 2,690.0 ft, slide 262A2, S43/0, FA 111.

Genus GeronCramer, 1967 ex Cramer, 1969

Type species: Geron guerillerusCramer, 1967.

Geron ludlovense sp. nov. (Plate 1: e)

Holotype: Kahf-1 well, 2,485.5 ft, slide 118 A2, S33/4 (Plate 1: e).

Locus typicus and stratum typicum: Kahf-1 well, 2,485.5 ft, Ludlow, Sharawra Member of the Qalibah Formation.

Derivation of name: From the Ludlow in reference to the age of the species.

Description: The vesicle is spherical to sub-spherical, ranges in size from 20-25 μm, enveloped by a thin outer wall. The outer wall is smooth, folded or wrinkled and drawn out into a short, 3-6 μm, horn at one pole and to a skirt, 15-20 μm wide at the other. The latter terminates in 3-6 slender processes. The overall size ranges from 55-70 μm. Measurements are based on 5 specimens.

Remarks: This species is distinguished from other Geron species by the horn-like shape of the outer wall at one pole.

Membranites Al-Ruwaili gen. nov.

Type species: Membranites minutus gen. et sp. nov.

Derivation of name: From the Latin membrana, membrane.

Diagnosis: The vesicle is spherical. A thin membrane arises from near the equator and partially envelops the vesicle. The membrane may be folded. The method of excystment is not apparent.

Remarks: The thin membrane that originates from near the equator covering one pole and rounded distally characterises this genus. The part of the vesicle that is covered by the membrane appears darker in colour than the rest of the body. The size and surface sculpture of the vesicle may serve later as a basis for further differentiation at the species level. ChuttecloskaLoeblich and Wicander, 1976, has a membrane that covers the entire vesicle in close contact at one pole and a skirt-like on the other. DivietipellisWicander, 1974, has an outer wall that is enveloping the inner vesicle.

Membranites minutus gen. et sp. nov. (Plate 2: d)

Holotype: Kahf-1 well, 4,926.7 ft, slide 167A2, F33/1 (Plate 2: d).

Locus typicus and stratum typicum: Kahf-1 well, 4,926.7 ft, Telychian, Qusaiba Member of the Qalibah Formation.

Derivation of name: Latin, minute, small in reference to the vesicle size.

Description: The vesicle is spherical, smooth to microgranulate, ranging in size from 12-17 μm. A thin, folded or wrinkled membrane arises from near the equator and partially envelops the vesicle. The membrane starts wider than the vesicle diameter then gently tapers to a rounded end equal to or narrower than the vesicle diameter. The maximum width of the membrane is 20 μm. The method of excystment is not apparent. Measurements are based on 5 specimens.

Genus MuraticaveaWicander, 1974 

Type species: Muraticavea enteichiaWicander, 1974.

Muraticavea irregularis sp. nov. (Plate 1: f)

Holotype: Kahf-1 well, 2,690.0 ft, slide 262A2, S43/0 (Plate 1: f).

Locus typicus and stratum typicum: Kahf-1 well, 2,690.0 ft, Ludlow, Sharawra Member of the Qalibah Formation.

Derivation of name: in reference to the irregular polygonal fields.

Description: The vesicle is sub-polygonal to sub-circular in outline. The surface is smooth and divided into 5-8 irregular polygonal fields that are formed by the folding of the vesicle wall. The fields are up to 25 μm across, 2-10 μm in height. No distinct central field is observed. The overall diameter ranges from 30-33 μm. The method of excystment is not apparent. Measurements based on 10 specimens.

Plate 2:

Figured material is housed in the Palaeontological Collections of the Natural History Museum, London. Well names and sample depths are followed by slide numbers, England Finder co-ordinates and Museum Collection Number.

  • (a) Veryhachium? owensii sp. nov., holotype, Kahf-1 well, 4,926.7 ft, slide 167A2, D31/0, FA 112.

  • (b) Eupoikilofusa tenua sp. nov., holotype, Kahf-1 well, 3,373.6 ft, slide 127A4, V31/0, FA 113.

  • (c) Eupoikilofusa tenua sp. nov., Kahf-1 well, 3,373.6 ft, slide 127A4, G 35/0, FA 114.

  • (d) Membranites minutus gen. et sp. nov., holotype, Kahf-1 well, 4,926.7 ft, slide 167A2, F33/1, FA 115.

  • (e) Proteolobus cylindrus sp. nov., holotype, Kahf-1 well, 2,485.5 ft, slide 118A2, H48/0, FA 116.

  • (f) Proteolobus cylindrus sp. nov., Kahf-1 well, 2,485.5 ft, slide 118A2, FA 117.

Plate 2:

Figured material is housed in the Palaeontological Collections of the Natural History Museum, London. Well names and sample depths are followed by slide numbers, England Finder co-ordinates and Museum Collection Number.

  • (a) Veryhachium? owensii sp. nov., holotype, Kahf-1 well, 4,926.7 ft, slide 167A2, D31/0, FA 112.

  • (b) Eupoikilofusa tenua sp. nov., holotype, Kahf-1 well, 3,373.6 ft, slide 127A4, V31/0, FA 113.

  • (c) Eupoikilofusa tenua sp. nov., Kahf-1 well, 3,373.6 ft, slide 127A4, G 35/0, FA 114.

  • (d) Membranites minutus gen. et sp. nov., holotype, Kahf-1 well, 4,926.7 ft, slide 167A2, F33/1, FA 115.

  • (e) Proteolobus cylindrus sp. nov., holotype, Kahf-1 well, 2,485.5 ft, slide 118A2, H48/0, FA 116.

  • (f) Proteolobus cylindrus sp. nov., Kahf-1 well, 2,485.5 ft, slide 118A2, FA 117.

Remarks: Muraticavea wenlockiaDorning, 1981a, differs from this species in having a greater overall diameter, 50-90 μm. Muraticavea enteichiaWicander, 1974, and M. munificus Wicander and Wood, 1981, both have a central pentagonal field and have a larger vesicle.

Genus VeryhachiumDeunff, 1954 ex Downie, 1959 emend Turner, 1984 

Type species: Veryhachium trisulcum (Deunff, 1951) Deunff, 1954 ex Downie, 1959.

Veryhachium? owensii sp. nov. (Plate 2: a)

Holotype: Kahf-1 well, 4,926.7 ft, slide 167A2, D31/0 (Plate 2: a).

Locus typicus and stratum typicum: Kahf-1 well, 4,926.7 ft, Telychian, Qusaiba Member of the Qalibah Formation.

Derivation of name: This species is named in honour of Professor Bernard Owens for his contribution to the study of the palynology of Saudi Arabia.

Description: The vesicle is triangular to sub-triangular in outline, single-layered, smooth and ranging in size from 22-33 μm. Two simple processes are projected from two angles and no process projected from the third angle that may have a thickening. The processes range in size from 20-30 μm and taper distally. Excystment method is by partial rupture between the two processes. Measurements are based on 10 specimens.

Remarks: The absence of the third process characterises this species and differentiates it from all published Veryhachium species. This would exclude the species from Veryhachium if the definition were to be applied strictly. Nevertheless, Le Hérissé (written communication) has observed an epityche type of excystment which is characteristic of Veryhachium. Therefore, it has been assigned to Veryhachium with uncertainty. It cannot be placed in Onondagella Cramer, 1966, emend Playford, 1977, which has a third process that is different from the other two.

Algae incertae sedis
Genus ProteolobusWood, 1997 

Type species: Proteolobus walliiWood, 1997.

Remarks: ProteolobusWood, 1997, is tentatively placed by its author in the fresh-water algal family, Hydrodictyaceae Dumortier, 1829, and will remain as such until further evidence is obtained.

Proteolobus cylindrus sp. nov. (Plate 2: e, f)

Holotype: Kahf-1 well, 2,485.5 ft, slide 118A2, H48/0 (Plate 2: e, f).

Locus typicus and stratum typicum: Kahf-1 well, 2,485.5 ft, Ludlow, Sharawra Member of the Qalibah Formation.

Derivation of name: From the Latin cylindrus, cylinder in reference to the shape of the processes.

Description: The vesicle is composed of three to eight hollow, smooth, cylindrical processes that are radiating from a common point without a central body. The wall is single-layered, thin and sometimes folded. The width of the processes is uniform except at their distal ends. The distal tips usually vary on a single specimen and they are rounded, acuminate or bifid. The length of the processes is always constant within the same specimen and ranges from 20-52 μm and the width ranges from 10-12 μm. The method of excystment is not apparent. Measurements are based on 20 specimens.

Remarks: Four-process forms are more abundant than the others. Proteolobus walliiWood, 1997, from the Devonian, differs from this species in having the processes tapering proximally and in always having rounded tips not bifurcated.

BIOSTRATIGRAPHY

The assignment of a Llandovery age to the Qusaiba Member on the evidence from graptolites and palynomorphs has been documented by many authors (e.g., Helal, 1964; McClure, 1978, 1988; Aoudeh and Al-Hajri, 1995; Le Hérissé et al., 1995; Paris and Al-Hajri, 1995; Paris et al., 1995). On the contrary, the

Sharawra Member used to be dated based on its stratigraphic position in the section until age diagnostic palynomorphs were recovered from the member by Le Hérissé et al. (1995) and Al-Hajri and Paris (1998). The former assigned late Wenlock to late Ludlow and the latter restricted it to the Wenlock age. Although detailed age investigation is beyond the scope of this paper, it is emphasised here that at least the uppermost Sharawra Member in Kahf-1 well is of Ludlow age based on acritarchs evidence.

Among the acritarchs that were recovered from core 1, interval 2,470.0-2,497.0 ft, are Perforella perforataDiez and Cramer, 1976, and Geron fundulariusDiez and Cramer, 1976, which were reported from the Ludlow of Spain (Diez and Cramer, 1976). The latter was also reported from the type Ludlow of England by Dorning (1981a). Arpylorus antiquus Calandra, 1964, Triangulina alargadaCramer, 1964, and Deflandrastum spp. which are restricted to Ludlow or younger sediments from North Africa have been encountered from this interval as well. The presence of Late Silurian sediments in this well is consistent with the decreasing time span of the Late Silurian hiatus northward in the Arabian Plate recorded by Mahmoud et al. (1992). Cryptospores and miospores are also present that will lead, in addition to the detailed acritarchs investigation, to a precise age for this cored interval in the near future.

PALAEOECOLOGY

The depositional environment of the Qusaiba Member being offshore shale is similar to what has been previously adequately documented (Mahmoud et al., 1992; Aoudeh and Al-Hajri, 1995; Stump et al., 1995).

Sharawra Member, unlike the reference sections, is dominated by shale indicating a more distal environment in this well. This is supported by the palynofacies where diverse marine acritarchs have been recovered with rare terrestrial spores, cryptospores and phytodebris. This type of palynofacies indicates an offshore environment (Dorning, 1981b and Tyson, 1995). The rare land-derived taxa are decreasing down-hole indicating an increasing distal environment downwards. Previous reports (Le Hérissé et al., 1995; Al-Hajri and Paris, 1998) indicate the possibility of fresh-water influx into the marine system. This is further supported by the presence of fresh-water algae in the uppermost beds of Sharawra Member. The genus DeflandrastrumCombaz, 1962, was attributed to the fresh-water algae, Family Hydrodictyaceae, by Colbath and Grenfell (1995) and Batten (1996). The genus KahfiaLe Hérissé et al., 1995, and with less confidence ProteolobusWood, 1997, are now considered to belong to the same family by Wood and Miller (1997). Although the Lower Palaeozoic members of this family are recorded from marine rocks only, many authors (e.g. Colbath and Grenfell, 1995 and Batten, 1996) argued that they are exclusively fresh-water algae but transported and deposited in marine environments. The presence of these three genera in core 1 indicates a fresh-water influx into the marine system.

CONCLUSION

Some of the new forms described in this paper have a relatively short vertical distribution which may be significant in local correlation. However, a regional correlation is needed to demonstrate the biostratigraphic value of the new taxa that may lead to an acritarch biozonation scheme.

ACKNOWLEDGEMENT

I express my gratitude to Professor Bernard Owens, Dr. Alain Le Hérissé, Dr. Stewart Molyneux and Mr. Sa’id Al-Hajri for reviewing the manuscript and offering valuable comments. Part of this work was undertaken while doing a post-graduate study in the University of Sheffield. Mr. Ken Dorning was the supervisor and he is thanked for his assistance during that period. I would like to acknowledge the Saudi Arabian Ministry of Petroleum and Mineral Resources and Saudi Arabian Oil Company for approval to publish this study.

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Eisenack
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, Plates 1-5.
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J.M.
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.
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.
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.
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.,
H.
Al-Tayyar
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J.G.L.A.
Van der Eem
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.
Stratigraphic and paleogeographical significance of Silurian acritarchs from Saudi Arabia
.
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, p.
49
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.
Loeblich
,
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, Jr.
,
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.
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.
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,
Chicago
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, Jr.
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Organic-walled microplankton from the Lower Devonian Late Gedinnian Haragan and Bois d’Arc Formations of Oklahoma, U.S.A., Part 1
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.
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McClure
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.
Review of Palaeobotany and Palynology
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41
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60
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Paris
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F
. and
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.
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, p.
311
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328
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.
Review of Palaeobotany and Palynology
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89
, nos.
1-2
, p.
75
-
90
.
Staplin
,
F.L
.
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.
Reef-controlled distribution of Devonian microplankton in Alberta
.
Palaeontology
 , v.
4
, no.
3
, p.
392
-
424
, Plates 48-51.
Stump
T
.,
S.
Al-Hajri
and
J.G.L.A.
Van der Eem
1995
.
Geology and palynostratigraphy of the Late Pre-Cambrian to Paleozoic sediments of Saudi Arabia
.
Review of Palaeobotany and Palynology
 , v.
89
, nos.
1-2
, p.
5
-
17
.
Turner
,
R.E
.
1984
.
Acritarchs from the type area of the Ordovician Caradoc Series, Shorpshire, England
.
Palaeontographica, Abt. B
 , v.
190
, nos.
4-6
, p.
87
-
157
, Plates 1-14.
Tyson
,
R.V
.
1995
. Sedimentary Organic Matter; organic facies and palynofacies.
Chapman & Hall
,
615
p.
Wicander
,
E.R
.
1974
.
Upper Devonian-Lower Mississippian acritarchs and prasinophycean algae from Ohio, U.S.A
.
Palaeontographica, Abt. B
 , v.
148
, nos.
1-3
, p.
9
-
43
, Plates 5-19.
Wood
.
G.D
.
1997
.
The acritarch Proteolobus wallii gen. et sp. nov. from the Devonian Iquiri Formation of Bolivia: a possible coenobial alga
.
Micropaleontology
 , v.
43
, no.
3
, p.
325
-
331
, Plates 1-2.
Wood
.
G.D
. and
M.A.
Miller
1997
. Pre-Carboniferous Chlorophyta: new reports of Hydrodictyaceae, Scenedesmaceae and Zygnemataceae. In
O.
Fatka
and
T.
Servais
(Eds.),
Acritarcha in Praha 1996
.
Acta Universitatis Carolinae
.
Geologica
 
40
, p.
703
-
717
.

ABOUT THE AUTHOR

Mansour H. Al-Ruwaili obtained his first degree in Geology from King Fahd University of Petroleum and Minerals in 1987. He worked for Saudi Aramco in the Area Exploration Department until 1993 when he joined the University of Sheffield for post-graduate work in the field of Early Palaeozoic palynology. In 1997 Mansour joined the Geological Research and Development Department in Saudi Aramco and he is presently working on Early Palaeozoic palynostratigraphy.

Figures & Tables

Figure 1:

Palaeozoic outcrops on the Arabian Peninsula, and the location of the Kahf-1 well discussed in this study.

Figure 1:

Palaeozoic outcrops on the Arabian Peninsula, and the location of the Kahf-1 well discussed in this study.

Contents

GeoRef

References

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133
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266
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Williams
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M.S.
Barss
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Freeman
and
J.M.
Hill
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.
Acritarchs and fossil prasinophytes; an index to genera, species and infraspecific taxa
.
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25
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771
.
Helal
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.
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.
Neues Jahrbuch fur Gelogie und Palaontologie, Monatshefte
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7
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414
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.
Palaeontographia Italica
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76
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57
-
302
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Le Hérissé
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A
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H.
Al-Tayyar
and
J.G.L.A.
Van der Eem
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Stratigraphic and paleogeographical significance of Silurian acritarchs from Saudi Arabia
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Review of Palaeobotany and Palynology
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89
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1-2
, p.
49
-
74
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Loeblich
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A.R.
, Jr.
,
1970
.
Morphology, ultrastucture and distribution of Paleozoic acritarchs
.
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,
Chicago
,
1969
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2
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-
788
.
Loeblich
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A.R.
, Jr.
, and
E.R.
Wicander
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.
Organic-walled microplankton from the Lower Devonian Late Gedinnian Haragan and Bois d’Arc Formations of Oklahoma, U.S.A., Part 1
.
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1-3
, p.
1
-
39
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Mahmoud
,
M.D
.,
D.
Vaslet
and
M.I.
Husseini
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.
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.
American Association of Petroleum Geologists Bulletin
 , v.
76
, no.
10
, p.
1491
-
1506
.
McClure
,
H.A
.
1978
.
Early Paleozoic glaciation in Arabia
.
Palaeogeography, Palaeoclimatology and Palaeoecology
 , v.
25
, p.
315
-
326
.
McClure
,
H.A
.
1988
.
Chitinozoan and Acritarch assemblages, stratigraphy and biostratigraphy of the early Palaeozoic of Northwest Arabia
.
Review of Palaeobotany and Palynology
 , v.
56
, p.
41
-
60
, Plates1-11.
Paris
,
F
. and
S.
Al-Hajri
1995
.
New chitinozoan species from the Llandovery of Saudi Arabia
.
Revue de Micropaleontologie
 , v.
38
, no.
4
, p.
311
-
328
.
Paris
F
.,
J.
Verniers
,
S.
Al-Hajri
and
H.
Al-Tayyar
1995
.
Biostratigraphy and paleogeographic affinities of Early Silurian chitinozoans from central Saudi Arabia
.
Review of Palaeobotany and Palynology
 , v.
89
, nos.
1-2
, p.
75
-
90
.
Staplin
,
F.L
.
1961
.
Reef-controlled distribution of Devonian microplankton in Alberta
.
Palaeontology
 , v.
4
, no.
3
, p.
392
-
424
, Plates 48-51.
Stump
T
.,
S.
Al-Hajri
and
J.G.L.A.
Van der Eem
1995
.
Geology and palynostratigraphy of the Late Pre-Cambrian to Paleozoic sediments of Saudi Arabia
.
Review of Palaeobotany and Palynology
 , v.
89
, nos.
1-2
, p.
5
-
17
.
Turner
,
R.E
.
1984
.
Acritarchs from the type area of the Ordovician Caradoc Series, Shorpshire, England
.
Palaeontographica, Abt. B
 , v.
190
, nos.
4-6
, p.
87
-
157
, Plates 1-14.
Tyson
,
R.V
.
1995
. Sedimentary Organic Matter; organic facies and palynofacies.
Chapman & Hall
,
615
p.
Wicander
,
E.R
.
1974
.
Upper Devonian-Lower Mississippian acritarchs and prasinophycean algae from Ohio, U.S.A
.
Palaeontographica, Abt. B
 , v.
148
, nos.
1-3
, p.
9
-
43
, Plates 5-19.
Wood
.
G.D
.
1997
.
The acritarch Proteolobus wallii gen. et sp. nov. from the Devonian Iquiri Formation of Bolivia: a possible coenobial alga
.
Micropaleontology
 , v.
43
, no.
3
, p.
325
-
331
, Plates 1-2.
Wood
.
G.D
. and
M.A.
Miller
1997
. Pre-Carboniferous Chlorophyta: new reports of Hydrodictyaceae, Scenedesmaceae and Zygnemataceae. In
O.
Fatka
and
T.
Servais
(Eds.),
Acritarcha in Praha 1996
.
Acta Universitatis Carolinae
.
Geologica
 
40
, p.
703
-
717
.

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