Palynology and Alluvial Architecture in the Permian Umm Irna Formation, Dead Sea, Jordan

Home , Brazilea, Noeggerathiales, Seatearth

GeoArabia, 2013, v. 18, no. 3, p. 17-60 Gulf PetroLink, Bahrain

Palynology and alluvial architecture in the Permian Umm Irna Formation, Dead Sea, Jordan

Michael H. Stephenson and John H. Powell

ABSTRACT

A series of lithofacies associations are defined for the Permian Umm Irna Formation indicating deposition in a fluvial regime characterised by low-sinuosity channels with deposition on point bars, and as stacked small-scale braided channels. Umm Irna Formation floodplain interfluves were characterised by low-energy sheet- flood deposits, shallow lakes and ponds, and peaty mires. Floodplain sediments, where not waterlogged, are generally pedogenically altered red-beds with ferralitic palaeosols, indicating a fluctuating groundwater table and humid to semi-arid climate. The Dead Sea outcrop provides a field analogue for similar fluvial and paralic depositional environments described for the upper Gharif Formation alluvial plain ‘Type Environment P2’ in the subsurface in Oman and the upper the basal clastics of the Khuff Formation at outcrop and in the subsurface in Central Saudi Arabia. Coarse-grained clasts within channel sandstones are mineralogically immature; their palaeocurrent directions and new evidence of glaciogenic sediments from Central Saudi Arabia suggests derivation from Pennsylvanian–Early Permian glaciofluvial outwash sandstones located to the east-southeast.

The palynology of the Umm Irna Formation is remarkably varied. Samples from argillaceous beds of fluvial origin appear to contain a palynomorph representation of the wider hinterland of the drainage basin of the river including floodplain plants and more distant communities. In restricted water bodies like oxbow lakes or other impermanent stagnant floodplain ponds and peaty mires (immature coals), a higher proportion of purely local palynomorphs appear to be preserved in associated sediments. One of the assemblages representing local plant communities displays a Cathaysian palaeophytographic affinity, while others from similar levels within the Umm Irna Formation present a Gondwanan affinity. This indicates the risk of generalisation from single borehole or limited outcrop studies.

The presence of Protohaploxypinus uttingii suggests an age range of Wordian– Capitanian to early Wuchiapingian (Middle to early Late Permian) for the Umm Irna Formation. The quantitative character of the Umm Irna Formation assemblages is very close to those of the basal Khuff clastics in the Central Saudi Arabian wells Dilam-1, Nuayyim-2 and Haradh-51. The lithological character and palynology of the transition between the Sa’ad and Arqov formations in the West Bank, west of the Dead Sea are similar to those of the transition between the Umm Irna Formation and overlying Ma’in Formation in Jordan.

INTRODUCTION

The predominantly siliciclastic succession unconformably overlying Cambrian sandstones along the northern margins of the Dead Sea, Jordan, was first assigned a Triassic age by Cox (1924, 1932). The biostratigraphy of these rocks was later refined by Huckriede and Stoppel (in Bender, 1968, 1974) who recognised Scythian conodonts within the Triassic sequence. A Late Permian age was assigned to the lower part of this succession by Bandel and Khoury (1981) who formalised the lithostratigraphy and further refined the biostratigraphy. The sedimentology and structure of the lower part of the Permian– Triassic sequence (Umm Irna Formation) was studied in detail by Makhlouf (1987), Makhlouf et al. (1990, 1991) and Powell and Moh’d (1993). More recent work has focussed on the remarkably well- preserved plant fossils in the Umm Irna Formation and their depositional environments (Kerp et al., 2006; Uhl et al., 2007; Abu Hamad et al., 2008; Dill et al., 2010).

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In this paper we describe well-preserved and diverse palynomorph assemblages within these alluvial sediments, which further refines the biostratigraphy and palaeoenvironments of this formation, and better enables correlation across the Arabian Platform (e.g. Saudi Arabia, Oman, Turkey), which was located at the southern margin of the Neo-Tethys Ocean (Stampfli and Borel, 2002). Through detailed sedimentological lithofacies analyses of fluvial, paralic and red-bed palaeosol lithofacies we ascribe palynological assemblages to localised palaeoenvironmental niches on the alluvial plain. Three-dimensional analyses of these sequences at outcrop provide an insight into the depositional environments and sand-body stacking patterns of the extensive, broadly coeval upper parts of the Gharif Formation and the basal Khuff clastics proved in the subsurface in Oman and Saudi Arabia, respectively, where they are hydrocarbon reservoir rocks. We relate the sedimentary sequences and alluvial architecture in the Umm Irna Formation to major sequence stratigraphical events (depositional sequences) across the Arabian Platform in the Middle Permian.

Organic-rich shales and immature coals in the Umm Irna Formation succession may provide suitable hydrocarbon source rocks in the subsurface basins of the Arabian Platform. Furthermore, the presence of fluvial sand-bodies, interbedded with these source rocks, present hydrocarbon reservoirs within extensionally faulted pre-Cretaceous half-grabens (Powell and Moh’d, 1993).

GEOLOGICAL SETTING

Earlier workers (Wetzel and Morton, 1959; Bender, 1974) noted that the Permian–Triassic sequence thins southward below the overstepping, unconformable Lower Cretaceous Kurnub Sandstone along the Dead Sea shore and, furthermore, that the sequence was intruded by dolerite dykes and sills that do not cut the overlying Cretaceous rocks. It was also recognised that the Permian–Triassic and Jurassic sequence becomes more complete when traced northwards along the outcrop, below the Cretaceous unconformity. Bandel and Khoury (1981) and Powell and Moh’d (1993) suggested that the relative completeness of the early Mesozoic sequence in north Jordan, as compared to the Dead Sea area (this study), was due to the general step-like, northerly down-faulting of the sequence in pre- Cretaceous times (probably latest Jurassic) rather than a result of northward tilting and subsequent erosion of the sequence prior to deposition of the fluvial Kurnub Sandstone in the Late Cretaceous.

This paper focuses on the type area (including the type section in Wadi Himara) of the Umm Irna Formation, where it unconformably overlies Cambrian sandstones (Umm Ishrin Sandstone Formation; Powell, 1989) along the northeastern shore of the Dead Sea, and in adjacent ephemeral wadis that drain into the lake (Figure 1). The Umm Irna Formation is generally overlain by the Ma’in Formation.

The type section of the Umm Irna Formation was defined by Bandel and Khoury (1981) in Wadi Himara, located about 2 km east of the Dead Sea (Figure 1, Locality 1; N 31°38’24.2’’; E 35°35’05’’) where it is about 68 m thick. They sub-divided the formation into six informal units (upward- fining cycles) comprising pebbly, coarse-grained sandstone, siltstone and claystone with irregularly developed ferruginous glaebule horizons.

Some of the plant fossil-rich carbonaceous siltstones near the base of the formation yielded palynomorphs indicating a ‘Late Permian’ age according to Brugman (in Bandel and Khoury, 1981); this age was supported in similar studies of samples from higher in the Umm Irna Formation (Armstrong, in Makhlouf, 1987). Makhlouf et al. (1991) recognised an informal Lower Member (Facies 1), about 10 m thick, consisting of sandstones and silty shales in upward-fining sequences, which they attributed to a distal braidplain setting. Their Upper Member (Facies 2) comprises five fining-upward cycles with elements of both braided and meandering stream deposits, with silty beds deposited in abandoned channels. Palaeosols with ferruginous glaebules are developed in the middle and upper part of the formation (Makhlouf et al., 1991; Powell and Moh’d, 1993).

Organic-rich lenses and beds comprising both dispersed mega-flora and disseminated finely comminuted plant fossil material, charcoalified wood and immature coals are present, especially in the Lower Member (Uhl et al., 2007; Abu Hamad et al., 2008; Dill et al., 2010), but as we show here – also throughout the formation. The plant material occurs in grey to brownish-black claystone

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and siltstone as in-situ palaeosol coals and as drifted material within grey claystone and dark grey organic-rich siltstones in abandoned channel lenses and within laterally accreted point-bar units. The plant macrofossils are more common and better preserved in the latter depositional setting.

Permian rocks (Hudayb Group; Andrews, 1992) have also been proven in hydrocarbon exploration wells in north and northeast Jordan (North Highlands-2 and Ajlun-1 in Andrews, 1992). An Early to Mid–Late Permian age was assigned to these rocks in north Jordan in the sub-surface, constrained in some of the wells to Kungurian (late Early Permian) to Kazanian (Middle Permian; Keegan in Andrews, 1992). The lowermost unit (the Anjara Formation of Andrews) comprises terrestrial, interbedded sandstone and dark siltstone. It is overlain by a middle carbonate unit, the Huwayra Formation, and an upper siliciclastic unit, the Buwayda Formation, that contains lignite and woody

35°30'E 35º 40'

31°45'N

N 0 5 Localities 2 and 9 : Panorama Road km

Locality 1: Wadi Himara,

t south

Dead Sea Faul

Dead Sea Wadi Zerqa Ma’in Locality 3: Roadside south of Wadi Zerqa Ma’in Locality 4: Side wadi south of Wadi Zerqa Ma’in

Locality 5: Roadside section

36°E 34°N 34° SYRIA Locality 6: Wadi Autun IRAQ Wadi ad Dab

32° Localities 7 and 8: Dyke Plateau Dead Sea Figure 9

JORDAN 30° 30° Al Mamalih N 0 100

SAUDI ARABIA km 28° 28° 36° 38° Umm Irna Formation outcrop 31°30' Figure 1: Location of the Umm Irna Formation outcrops, based on Powell and Moh’d (1993) and Shawabakeh (1997).

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plant material (Andrews, 1992), clean, fine- to medium-grained sandstone (probably channel-fill deposits) and red-brown, ferruginous and lignitic fine-grained sandstone interbedded with black to dark grey siltstone (probably coaly mire and red-bed pedogenic floodplain deposits). Based on the similarity of its lithology and gamma-log response, the Buwayda Formation is interpreted as equivalent to the Umm Irna Formation at outcrop. Since the latter rests unconformably on the Cambrian Ram Sandstone Group along the Dead Sea shore it seems likely that the middle (Huwayra) and lower (Anjara) formations in the subsurface in north Jordan are absent at outcrop.

Abu Hamad et al. (2008) and Kerp et al. (2006) regard the upper boundary of the Umm Irna Formation as unconformable with the overlying Ma’in Formation (Himara Member). Low diversity palynological assemblages from approximately 10 m above the unconformity were dated as Early Triassic (Abu Hamad, 2004; Kerp et al., 2006), and higher parts of the formation are dated as ‘mid to late Scythian’ (probably Induan to Olenekian) based on bivalve determinations by Cox (1932), and on conodonts (Huckriede and Stoppel in Bender, 1968, 1974). West of the Dead Sea, Permian sediments were deposited in a shallow-marine environment with inter-fingering fluvial siliciclastics representing the palaeoshoreline in the Negev area (Eshet and Cousminer, 1986; Eshet, 1990).

During the deposition of the Umm Irna Formation (Figures 2a, b), Jordan lay about 15 to 20 degrees south of the palaeo-equator at the northern margin of the Arabian Platform in a continental to marginal-marine setting with the Neo-Tethys Ocean located to the north (Stampfli and Borel, 2002). The palaeogeographical location, together with the diverse and abundant macro- and microfloras, and ferralitic palaeosols described from this formation indicate a humid-tropical climate. During relative high sea level, marine transgressions advanced to the south and southeast.

MATERIALS AND METHODS

Measured sections were logged in detail at nine localities in the Umm Irna Formation adjacent to the Dead Sea (Figures 1 and 2a). These were recorded with a high-resolution digital camera and GPS. Palaeocurrent measurements were taken from trough cross-bedded, ‘rib and furrow’ channel- fill sandstones where these are exposed in three dimensions to maximise accuracy of palaeocurrent azimuth measurements. A total of 25 samples were taken at various localities for palynological analysis. Palynological samples were extracted by deep excavation of the claystone, siltstone and coaly beds using a pick-axe to avoid near-surface contamination or the present-day oxidation of palynomorphs. In addition, samples were taken, where possible, from shaded north-facing exposures to avoid as far as possible, oxidized areas. The preparation of strew mounts for palynological analysis comprised crushing, followed by hydrochloric and hydrofluoric acid treatments (Wood et al., 1996). The post-hydrofluoric acid organic residues were oxidized using Schulze’s solution and dilute nitric acid. The palynological slides bear the British Geological Survey code prefix ‘MPA’ and are curated in the BGS collections in Keyworth, Nottingham. Plant fossils were also collected from organic-rich siltstones and claystones in abandoned channel lithofacies.

SEDIMENTOLOGY OF THE UMM IRNA FORMATION

Stratigraphical and sedimentological studies of the Umm Irna and Ma’in formations (Bandel and Khoury, 1981; Makhlouf, 1987; Makhlouf et al., 1990, 1991; Powell and Moh’d, 1993; Dill et al., 2010) have demonstrated depositional environments typified by predominantly fluvial, braided to low-sinuosity sandstone channels together with finer grained, red-bed interfluve sandstone and siltstone with intermittent ferruginous palaeosol horizons. Organic-rich siltstones and thin immature coals (some with seatearths) are occasionally present. The main sampled localities, lithofacies and depositional environments are summarised here, together with new data from the current study that provide a framework for the palynological analysis described in the next section.

Locality 1: Wadi Himara South Side This composite 9 m section (Figures 2 and 3; Plate 1), which includes the lower part of the Umm Irna Formation and its unconformable boundary with the Cambrian Umm Ishrin Formation, represents the type area and the type section described by previous authors (Bandel and Khoury, 1981; Makhlouf

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(a) et al., 1991; Abu Hamad et al., 2008). Relative sea It is located along the southern level curve branch of Wadi Himara, upstream Low High Ma’in Formation from a major waterfall, where a Localities 7 and 8: Dyke Plateau small side wadi bifurcates from this branch. The location is N31°38’24.2’’ and E35°35’05.8’’. The section Locality 5: Roadside section is dominated by thick, lensoid trough cross-bedded sandstone Locality 6: Wadi Autun units with erosional bases. Foresets are lined by small pebbles and Locality 4: Side wadi south of granules of quartz, with some Wadi Zerqa Ma’in sub-rounded, pink alkali-feldspar Locality 3: Roadside south of clasts. Carbonaceous siltstone Wadi Zerqa Ma’in laminae also drape some of the foresets. The lowermost sandstone Claystone and is colour-mottled mauve-grey with siltstone vertical and subvertical vertisols 10 m Pebbly sandstone Sandstone which include yellow-brown Trough cross limonite-goethite glaebules. Some Umm Irna Formatio n bedding of the sandstone beds are capped Localities 2 and 9: c = clay s = silt by thin carbonaceous lamina Panorama Road f = ﬁne sand with downward penetrating m = medium sand vertical plant rootlets. The relative c = coarse sand p = pebbles proportion of yellow fluvial channel c = cobbles sandstone lithofacies compared Locality 1: Wadi Himara to red-bed alluvial floodplain sediments in the Umm Irna Formation is illustrated in Plates Unconformity (Cambrian) Umm Ishrin 1 and 2, the latter plate showing Sandstone Formation an inaccessible vertical face on the opposite, northern side of the wadi. csf m cpc (b)

SE ASIA SIBERIA

LAURUSSIA EUROPE 10° TOR EQUA Neo- Tethys 30°

NORTH Cimmeria Dead Sea AMERICA ? Umm Irna outcrops KSA OM SR WEST GONDWANA INDIA AFRICA EAST GONDWANA SOUTH AMERICA AUSTRALIA

Figure 2: (a) Generalised composite Umm Irna Formation section showing a guide to the approximate positions of the sampled sections. Generalised relative sea-level curve also shown. (b) Middle Permian (Roadian–Wordian) continental configuration. OM— Oman, SR— Salt Range, KSA - Saudi Arabia (Modified after Angiolini, 2001). Dashed black arrow indicates approximate palaeoflow for Umm Irna Formation.

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Carbonaceous clayston e Siltston e Pebbly sandstone Sandston Trough cross beddin Rootlets Carbonaceous laminae Glaebules Plant debris Vertical mottling (palaeosol)

Retusotriletes spp. Retusotriletes

a cancellos Playfordiaspora

Cyclogranisporites spp. Cyclogranisporites

Alisporites spp. Alisporites

Alisporites indarraensis Alisporites

. sp ?Brazilea

Thymospora cf. opaqua cf. Thymospora

Punctatisporites spp. Punctatisporites

Pretricolpipollenites bharadwaji Pretricolpipollenites

Platysaccus spp. Platysaccus

i queensland Platysaccus

R sp. Nuskoisporites

. indet Monosaccate

Leiosphaeridia spp. Leiosphaeridia

Laevigatosporites spp. Laevigatosporites

Falcisporites stabilis Falcisporites

s priscu Cedripites

Cannanoropollis spp. Cannanoropollis

. indet Bisaccate Alisporites nuthallensis Alisporites

Stratigraphic Range Retusotriletes spp. Retusotriletes

a cancellos Playfordiaspora

1 Cyclogranisporites spp. Cyclogranisporites

1 Alisporites spp. Alisporites

1 Alisporites indarraensis Alisporites

1 Palynology

. sp ?Brazilea

1 Thymospora cf. opaqua cf. Thymospora

1 3 Punctatisporites spp. Punctatisporites

5 1 Pretricolpipollenites bharadwaji Pretricolpipollenites

1 Platysaccus spp. Platysaccus

i queensland Platysaccus

R sp. Nuskoisporites

5 1

Monosaccate indet Monosaccate 7 5 Leiosphaeridia spp. Leiosphaeridia

2 Laevigatosporites spp. Laevigatosporites

3 Falcisporites stabilis Falcisporites

10 10

s priscu Cedripites

1 Locality 1. Wadi Himara South Side Cannanoropollis spp. Cannanoropollis 1 30

14 . indet Bisaccate Alisporites nuthallensis Alisporites Figure 3: Sedimentological log and palynology for Wadi Himara (Locality 1) . Absolute abundance, counts shown 4 1

) (metres Samples 4.00 4.25 6226 6226 Is Is Cf s Cf s Or m Cors Is/Fp s c Lithofacie s Unconformity Associations Fm. (Cambrian) Umm Ishrin Sst. cp m y f cs

Litholog Metres 0 1 3 2 4 7 9 8 6 5

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Ma’in Formation

Umm Irna Formation

Major channel sandstone thinning west Organic-rich mudstones Thin channel sandstone Thin channel Red-beds Red-beds sandstone

1.8 m Red-beds

ca. 4 m above base Organic-rich of Umm Irna Formation mudstones Plate 1: Umm Irna Formation in Wadi Himara, south (Locality 1) showing organic-rich mudstone sample points (inset photograph), major channel sandstones and pedogenic red-beds. View southwards. The base of the formation is approximately 4 m below the side wadi. Geologist for scale.

Ma’in Formation (Triassic) Disconformity Cliff edge Red beds SB

Ch 6 Umm Irna Formation ca. 68 m

Ch 5 Ch 4 Ch 3 Red ﬂoodplain sediments

Ch 2 Ch 2 Red ﬂoodplain sediments Unconformity Talus in foreground Umm Ishrin Formation (Cambrian)

Plate 2: Umm Irna Formation on north side of Wadi Himara, showing the unconformity (pale band) with the Cambrian Umm Ishrin Sandstone Formation and the disconformity with the Triassic Ma’in Formation. Note the distribution of major (‘winged’) channel sandstones (numbered Ch 1–6) and the interbedded, reddened (oxidized) ﬂoodplain sediments, with palaeosols. SB denotes the sequence boundary marking the base of paralic/marine sedimentation seen also in Plates 6 to 8 and 10. Height of cliff approximately 100 m, photo looking northeast.

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A few thin carbonaceous siltstone and claystone beds are present about 4.5 m above the base of the formation (Plate 1): an upper bed with plant macrofossils and a lower one split by a thin sandstone lamina.

Locality 2: Panorama Road (East) This section is on the eastern side of the road cutting of the recently constructed Panorama Road (Plate 3a). The section is between points N31°39’11.5’’, E35°34’41.9’’ and N31°39’08.9’’, E35°34’43’’, and includes four separate productive palynological sample points (Figure 4). The section lies within a faulted block, so its exact stratigraphical position is uncertain, although we believe it to lie within the lower part of the formation on account of its lithofacies being closely comparable with the lower part of the Umm Irna Formation in the type locality at Wadi Himara, located 1.5 km to the southeast. Locality 9 (see below; Plate 3b), located on the opposite (western) side of the road cutting, did not yield palynomorphs. The lowermost bed at Locality 2 (represented by palynological sample MPA 62244) comprises dark grey claystone and siltstone with plant macrofossils, and is overlain by pale grey siltstone. This is overlain by a thin dark grey siltstone with disseminated plant fragments (represented by sample MPA 62243), with laminae which are oxidised to pale brown colour. The overlying beds comprise pale grey and red siltstone with ca. 1.5 m thick beds of trough cross-bedded sandstone. The uppermost palynological sample points were within two thin dark grey claystone beds (MPA 62242 and 62241), again with disseminated plant fragments, underlying a thin yellow channel sandstone (Figure 3).

Locality 3: Wadi Zerqa Ma’in South This roadside section located (N31°36’46.1’’, E35°33’57.5’’) south of Wadi Zerqa Ma’in is approximately 5 m thick, and is dominated by claystone and siltstone with several thin trough cross-bedded, medium grained sandstone beds, pebbly in part (Figure 5; Plate 4). Some sandstone beds are penetrated by

e Talus Sandston Organic-rich mudstone on sandston Red mudstone Sandstone Grey mudstone with Sample organic-rich laminae point Sample point

Channel sandstone

Coaly mudstone Plate 3: (a) Panorama Road, east (Locality 2) showing Leached seatearth sample locations and the grey/red-bed lithologies; sandstone with rootlets (b) west of the road (Locality 9), thin coaly mudstone overlying white leached quartzitic seatearth sandstone with plant rootlets.

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Permian Umm Irna Formation, Jordan

Triquitrites spp. Triquitrites

Retusotriletes spp. Retusotriletes

Punctatisporites spp. Punctatisporites

a cancellos cf. Playfordiaspora

Pilasporites calculus Pilasporites

Leiotriletes spp. Leiotriletes Plant debris

Leiosphaeridia spp. Leiosphaeridia

Kendosporites spp. Kendosporites

Indotriradites spp. Indotriradites

?Vittatina spp. ?Vittatina

?Dictyotriletes aules ?Dictyotriletes

Vittatina spp. Vittatina

Taeniate bisaccate indet bisaccate Taeniate

Platysaccus spp. Platysaccus

Maculatasporites lignin type lignin Maculatasporites

Lundbladispora spp. Lundbladispora Distriatites insolitus Distriatites

Carbonaceous laminae Convolutispora spp. Convolutispora

Cannanoropollis spp. Cannanoropollis

Camptotriletes spp. Camptotriletes

s indarraensi Alisporites

i queensland Platysaccus

g Laevigatosporites spp. Laevigatosporites

Dictyotriletes spp. Dictyotriletes

s warchianu Camptotriletes

. sp ?Densipollenites

s chalastu Reduviasporonites

. indet Monosaccate Falcisporites stabilis Falcisporites

Trough cross beddin

. indet Bisaccate

s Stratigraphic Range nuthallensi Alisporites Triquitrites spp. Triquitrites

1 Retusotriletes spp. Retusotriletes

1 Punctatisporites spp. Punctatisporites

2 a cancellos cf. Playfordiaspora

1 s Pilasporitescalculu

Palynology 1

Leiotriletes spp. Leiotriletes

Sandstone Leiosphaeridia spp. Leiosphaeridia

13 Kendosporites spp. Kendosporites

1 Indotriradites spp. Indotriradites

1 ?Vittatina spp. ?Vittatina ?Dictyotriletes aules ?Dictyotriletes

11 Vittatina spp. Vittatina

1 Taeniate bisaccate indet bisaccate Taeniate Platysaccus spp. Platysaccus

11 1 Maculatasporites lignin type lignin Maculatasporites

Lundbladispora spp. Lundbladispora Pebbly sandstone

Locality 2. Panorama Road Section

Distriatites insolitus Distriatites

Convolutispora spp. Convolutispora Cannanoropollis spp. Cannanoropollis

1121 Camptotriletes spp. Camptotriletes

s indarraensi Alisporites

22 i queensland Platysaccus

Laevigatosporites spp. Laevigatosporites Siltston e

Dictyotriletes spp. Dictyotriletes

s warchianu Camptotriletes

2 . sp ?Densipollenites

11211 s chalastu Reduviasporonites

. Monosaccate indet Monosaccate Figure 4: Sedimentological log and palynology for Panorama Road (Locality 2). 15 1 2

24 Falcisporites stabilis Falcisporites 2 31 86 79

32 28

. indet Bisaccate

27 24

s Alisporites nuthallensi Alisporites Carbonaceous claystone Absolute abundance, counts shown 6 3

1 2 3 4 Samples (metres) Samples 8.10 1.35 1.60 9.80

6224 6224 6224 6224

Associations

s Lithofacie Is Is Is Is Is Cf s Cf s Cors Cors Cors c

cp y Litholog m f

cs Metres 0 1 2 3 4 5 6 7 8 9 10

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Carbonaceous claystone Siltston e Pebbly sandstone Sandstone Trough cross beddin Rootlets Carbonaceous laminae Glaebules Plant debris Vertical mottling (palaeosol) Lateral accretion Burrows (horizontal)

Leiotriletes spp. Leiotriletes

Alisporites cf. nuthallensis cf. Alisporites

. indet bisaccate Taeniate

Indotriradites spp. Indotriradites

Punctatisporites spp. Punctatisporites

Protohaploxypinus uttingii Protohaploxypinus

Peroaletes khuffensis Peroaletes

Monosaccate indet. Monosaccate

Lundbladispora spp. Lundbladispora

Leiosphaeridia spp. Leiosphaeridia

Laevigatosporites spp. Laevigatosporites

Laevigatosporites cf. callosus cf. Laevigatosporites

Falcisporites stabilis Falcisporites

Distriatites insolitus Distriatites

Cristatisporites spp. Cristatisporites

Camptotriletes spp. Camptotriletes

. indet Bisaccate

s nuthallensi Alisporites

Stratigraphic Range indarraensis Alisporites

Leiotriletes spp. Leiotriletes Alisporites cf. nuthallensis cf. Alisporites

22 . indet bisaccate Taeniate

1 1 Indotriradites spp. Indotriradites

1 Punctatisporites spp. Punctatisporites

3 Protohaploxypinus uttingii Protohaploxypinus

1 Peroaletes khuffensis Peroaletes

Palynology Monosaccate indet. Monosaccate

5 Lundbladispora spp. Lundbladispora

21 21 Leiosphaeridia spp. Leiosphaeridia Laevigatosporites spp. Laevigatosporites

25 Laevigatosporites cf. callosus cf. Laevigatosporites Falcisporites stabilis Falcisporites

41 51 Distriatites insolitus Distriatites Cristatisporites spp. Cristatisporites

13 Camptotriletes spp. Camptotriletes 1 66

Locality 3. Wadi Zerqa Ma’in South

. indet Bisaccate

11 s nuthallensi Alisporites

6 Alisporites indarraensis Alisporites Absolute abundance, counts shown 47

9 0 1 Samples (metres) Samples

2.00 3.00 3.25 3.80 6224

6225 6225 62252

Associations

s Lithofacie Figure 5: Sedimentological log and palynology for Wadi Zerqa Ma’in south (Locality 3). Is Is c Cf s Cf s Te s Te s Cors Cors Is/Cor s p c y fm cs

Litholog Metres 0 1 2 3 4 5

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Mega-ripples

Tidal bundles Horizontal burrow network

Organic-rich Plate 4: Wadi Zerqa Ma’in south (Locality 3) illustrating laminae interbedded thin sandstones with mega-ripples (crevasse splay ﬂoodplain) and sampled organic-rich mudstones. Note the thin pale yellow bioturbated sandstone bed with a horizontal burrow network; burrows penetrate into the underlying mudstone (inset photograph).

vertical and sub-vertical plant rootlets to a depth of up to 25 cm below overlying thin carbonaceous siltstone laminae. The uppermost sandstone (1.7 m thick) shows repeated plant colonisation at three levels, indicating periods of low fluvial flow-regime. A distinctive pale grey medium-grained sandstone bed, 0.20 m thick, present about 1.5 m above the base of the section, contains a network of circular, horizontal burrows (Plate 4). Thin, low-angle laterally-accreted sandstone units with carbonaceous claystone drapes are present between sample levels MPA 62249 and MPA 62250. Dark grey carbonaceous siltstone beds above and below the burrowed horizon yielded a diverse assemblage of palynomorphs (MPA 62249). Samples from the carbonaceous claystone higher in the section (MPA 62250) and from siltstones (MPA 62251 and 62252) also yielded diverse assemblages.

Locality 4: Side Wadi South of Wadi Zerqa Ma’in This north-facing section (N31°36’44.4’’, E35°33’56.2’’) represents part of the upper Umm Irna Formation, and is exposed in a small unnamed wadi, south of Wadi Zerqa Ma’in, and about 800 m south of Locality 3. The 3 m thick section comprises, yellow-grey trough cross-bedded sandstone with thin carbonaceous siltstone lenses with plant macrofossils and rootlets; the upper part of the sandstone has rootlets penetrating to 60 cm (Figure 6). The upper part of the section comprises 2 m of siltstone intercalated with thin yellow and pale red sandstone beds. Lower and upper claystones provided samples MPA 62253 and MPA 62254, which yielded diverse and well-preserved assemblages (Figure 6). A thin sandstone bed, about 2 m above the base of the section contains a network of horizontal circular burrows similar to those seen nearby at Locality 3.

Locality 5: Roadside Section South of Wadi Zerqa Ma’in This short 6 m thick section (Figure 7) is preserved in a small gully (N31°36’31.0’’, E35°33’49.2’’) a few metres immediately east of the Dead Sea road. The section represents the upper part of the Umm Irna Formation and is dominated by yellow and grey, medium-grained, trough cross-bedded sandstone with a thin claystone bed and siltstone bed about 2 m above the base of the section. Carbonaceous plant rootlets penetrate up to 75 cm from the claystone to the lower sandstone. Two samples of the siltstone yielded well-preserved diverse assemblages (MPA 62255 and 62256).

Locality 6: Wadi Autun The upper part of the Umm Irna Formation is exposed to the east of the Dead Sea road in the narrow Wadi Autun (N31°32‘40.1’’, E35°33’31.7’’). The north-facing, measured section (6 m thick) lies about 15 m below the top of the formation (Figure 8; Plate 5). It consists of intercalated yellow, pink and grey medium-grained sandstone and grey siltstones with black carbonaceous laminae. A lower

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Punctatisporites spp. Punctatisporites

r mino forma gretensis Punctatisporites

Cannanoropollis spp. Cannanoropollis

Alisporites cf. nuthallensis cf. Alisporites

. indet bisaccate Taeniate

Protohaploxypinus uttingii Protohaploxypinus

Potonieisporites spp. Potonieisporites

Platysaccus queenslandi Platysaccus Burrows (horizontal)

Peroaletes khuffensis Peroaletes

. indet Monosaccate

Leiosphaeridia spp. Leiosphaeridia

Falcisporites stabilis Falcisporites

Distriatites insolitus Distriatites

Cyclogranisporites spp. Cyclogranisporites

Botryococcus spp. Botryococcus

Plant debris

. indet Bisaccate

Alisporites nuthallensis Alisporites

Alisporites indarraensis Alisporites

Stratigraphic Range Punctatisporites spp. Punctatisporites

4 r mino forma gretensis Punctatisporites

1 Cannanoropollis spp. Cannanoropollis

Rootlets

1 Alisporites cf. nuthallensis cf. Alisporites

. indet bisaccate Taeniate 31 31

Palynology

Protohaploxypinus uttingii Protohaploxypinus Potonieisporites spp. Potonieisporites

4 15 Platysaccus queenslandi Platysaccus

81 Peroaletes khuffensis Peroaletes Carbonaceous laminae

. indet Monosaccate 31

19 Leiosphaeridia spp. Leiosphaeridia g 22

17 Falcisporites stabilis Falcisporites

Locality 4. Side Wadi South of Zerqa Ma’in Distriatites insolitus Distriatites

13 Cyclogranisporites spp. Cyclogranisporites Botryococcus spp. Botryococcus 11 Trough cross beddin 31

. indet Bisaccate

Alisporites nuthallensis Alisporites 04 Alisporites indarraensis Alisporites

Absolute abundance, counts shown

16 31 e

) (metres Samples 0.50 1.50 62254 62253

Pebbly sandstone Sandston Associations

c s Lithofacie Figure 6: Sedimentological log and palynology for side wadi south of Wadi Zerqa Ma’in (Locality 4) . Cf s Tes Is/Cor s Is/Cor s cp m f y cs

Carbonaceous clayston e Siltston e

Litholog Metres 0 1 2 3

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Permian Umm Irna Formation, Jordan

. indet bisaccate Taeniate

Protohaploxypinus spp. Protohaploxypinus

Protohaploxypinus limpidus Protohaploxypinus Peroaletes khuffensis Peroaletes

Rootlets Nuskoisporites spp. Nuskoisporites

Lundbladispora spp. Lundbladispora

Leiosphaeridia spp. Leiosphaeridia

Laevigatosporites spp. Laevigatosporites

Laevigatosporites cf. callosus cf. Laevigatosporites

Granulatisporites spp. Granulatisporites

Distriatites insolitus Distriatites

Dibolisporites spp. Dibolisporites

Botryococcus spp. Botryococcus

?Guttulapollenites hannonicus ?Guttulapollenites

Thymospora cf. opaqua cf. Thymospora

a opaqu Thymospora

Carbonaceous laminae

s chalastu Reduviasporonites

Platysaccus queenslandi Platysaccus

. indet Monosaccate

Falcisporites stabilis Falcisporites

s priscu Cedripites

. indet Bisaccate

Alisporites nuthallensis Alisporites

?Lueckisporites virkkiae ?Lueckisporites

Stratigraphic Range sp ?Brazilea

. indet bisaccate Taeniate

Protohaploxypinus spp. Protohaploxypinus Protohaploxypinus limpidus Protohaploxypinus

Trough cross beddin 111 Peroaletes khuffensis Peroaletes

3 Nuskoisporites spp. Nuskoisporites Lundbladispora spp. Lundbladispora

Leiosphaeridia spp. Leiosphaeridia 11 e Laevigatosporites spp. Laevigatosporites

Palynology callosus cf. Laevigatosporites

2 Granulatisporites spp. Granulatisporites

Sandston

Distriatites insolitus Distriatites Dibolisporites spp. Dibolisporites

111 Botryococcus spp. Botryococcus

1 ?Guttulapollenites hannonicus ?Guttulapollenites

Thymospora cf. opaqua cf. Thymospora

a opaqu Thymospora

21 41

s chalastu Reduviasporonites

2 Platysaccus queenslandi Platysaccus Siltston e

12 . indet Monosaccate 2

19 Locality 5. Roadside Upper Umm Irna stabilis Falcisporites

15 s priscu Cedripites 64 54

Pebbly sandstone

Figure 7: Sedimentological log and palynology for road side section (Locality 5).

. indet Bisaccate

Alisporites nuthallensis Alisporites 8

?Lueckisporites virkkiae ?Lueckisporites

. sp ?Brazilea Absolute abundance, counts shown 28 11

5 6 Samples (metres) Samples Carbonaceous clayston e 3.70 3.80 6225 6225 c p Cf s Cf s c Is/Cor s Lithofacie s Associations fm y cs

Litholog Metres 0 1 3 2 4 6 5

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Torispora-Thymospora complex Torispora-Thymospora

a opaqu cf. Thymospora

Punctatisporites spp. Punctatisporites

Potonieisporites spp. Potonieisporites Rootlets

a cancellos Playfordiaspora

. indet Monosaccate

Florinites spp. Florinites

Cyclogranisporites spp. Cyclogranisporites

s indarraensi Alisporites

Pretricolpipollenites bharadwaji Pretricolpipollenites

Lundbladispora spp. Lundbladispora

Leiosphaeridia spp. Leiosphaeridia

s stabili Falcisporites Cedripites spp. Cedripites

Carbonaceous laminae

Cedripites priscus Cedripites

. indet Bisaccate Stratigraphic Range nuthallensis Alisporites 5 g Trough cross beddin di Autun (Locality 6).

e Torispora-Thymospora complex Torispora-Thymospora

a opaqu cf. Thymospora Punctatisporites spp. Punctatisporites

Palynology Sandston Potonieisporites spp. Potonieisporites

11 18 a cancellos Playfordiaspora

. indet Monosaccate

41 Florinites spp. Florinites Cyclogranisporites spp. Cyclogranisporites

11 s indarraensi Alisporites Siltston e 45

Locality 6. Wadi Autun

Pretricolpipollenites bharadwaji Pretricolpipollenites Lundbladispora spp. Lundbladispora y 1

14 Leiosphaeridia spp. Leiosphaeridia Pebbl sandstone

s stabili Falcisporites

10 Cedripites spp. Cedripites

4 Cedripites priscus Cedripites 2

14 . indet Bisaccate

31 Alisporites nuthallensis Alisporites Absolute abundance, numbers shown 1

8 7 Carbonaceous clayston e Figure 8: Sedimentological log and palynology for Wa ) (metres Samples

5.40 1.05 6225 6225

Associations

s Lithofacie Is c Cf s Cf s Cf s Is/Cor s Is/Cor s p c y fm cs

Litholog Metres 0 1 2 3 4 5

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Red-beds: trough cross-bedded sandstone

Organic-rich mudstone in base of channels

Trough cross-bedded sandstone

Plate 5: Wadi Autun (Locality 6) showing sampled upper and lower organic-rich mudstone beds. Height of pictured scene approximately 3 m.

sample (MPA 62257) was taken from a grey siltstone overlain by black carbonaceous, almost coaly, siltstone that is overlain by trough cross-bedded sandstone with an erosive base (Figure 8). The upper sample (MPA 62258) was from a carbonaceous siltstone overlying a claystone- and siltstone-filled abandoned channel, but is itself overlain by sandstone with an erosional base. The two samples yielded moderately well preserved assemblages which are quite distinct from each other (despite their stratigraphic proximity), and from other assemblages recovered from the Umm Irna Formation (see Palynology section).

Localities 7 and 8: Dyke Plateau Locality 7 is 1.65 km south of Wadi ad Dab (Figure 1). The upper part of the Umm Irna Formation and its boundary with the overlying Ma’in Formation is well exposed along a cliff marking a former cliff line of the Dead Sea and in a number of east-draining side wadis, above a wave-cut platform (Figure 9). The beds are mostly horizontal, but dip gently to the north in the northern part of the section. The well-exposed section is cut by a sub-vertical dolerite dyke, which may be coeval with the Tayasir Volcanics in Galilee, the base of which gives a probable late Jurassic to early Cretaceous age (144 ± 5 and 148 ± 7 Ma); see Lang and Mimran (1985) and Powell and Moh’d (1993) for discussion. The section, illustrated in the panoramic photographs (Plates 6, 7 and 8) extends from N31°32’13.0’’, E35°33’27.2’’ where the boundary with the overlying Ma’in Formation is exposed, southwards to N31°31’56.5’’, E35°33’25.6’’ and includes a small westward-orientated side wadi, Locality 8 (N31°38’24.2’’, E35°35’05.8’’; Figure 9).

The cliff section includes a laterally accreted channel sandstone-siltstone-claystone complex with evolved palaeosols, which was previously figured by Powell and Moh’d (1993, Figure 8). The northern part of the cliff section is dominated by an erosively-based, fluvial sandstone channel which is exposed in three dimensions at N31°32’09.2’’, E35°33’26.4’’. The overall channel is low-sinuosity and comprises stacked channel-fill sandstones with lower, middle and upper sections. Palaeocurrent measurements (100 in total) on “rib and furrow” trough cross-beds indicate an overall palaeocurrent direction to the west-northwest to west-southwest (Figure 9). However, the lower section of the channel is generally unidirectional to the north-northwest. A feature of the lower section is deep scouring of the channel into the surrounding pedogenetically-altered level-bedded floodplain deposits. The basal channel-

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0° Sandstone channel (north)

N = 14 270° 90° Maximum = 2.5 0 200 Dip direction (10° classes) m

180° Outcrop of large channel in upper Umm Irna Formation 0° Dead Sea

Sandstone channel Approximate Dead Sea Route 65 (middle) trend of dyke Samples

N = 39 270° 90° 62259-62261 Maximum = 5.0 Dip direction (10° classes)

180° Edge of cliffDyke Plateau

0° Sandstone channel (south) combined Sample 62263 N N = 14 270° 90° Maximum = 4.5 Dip direction (10° classes) Figure 9: Map of Dyke Plateau area with palaeocurrent data 180° for the major channel.

fill shows an upward change from pebble-to granule-size clasts comprising reworked brown and black limonitic and goethitic palaeosol clasts derived from the proximal floodplain, along with sub- rounded granules of pink feldspar and quartz, from a more distant source (Plate 9). The middle and upper sections of the channel have more divergent palaeocurrent directions, dominantly to the west-southwest, but with considerable divergence in the uppermost sinuous channel (Figure 9). The waning flow regime in the upper section is also illustrated by the presence of claystone and organic- rich siltstone drapes on foresets (Plate 7).

To the south of the sandstone channel axis, a number of well-exposed, laterally accreted sandstone- siltstone-claystone units form multi-stacked, lensoid sand-bodies (Plates 6, 7 and 8). These first-order units are internally structured by second-order laterally accreted units (Plate 8). Many of the low- angle lateral accretion surfaces are draped by thin beds and laminae of grey claystone and black organic-rich siltstone. In places, penecontemporaneous slumped beds and microfaults can be seen at channel margins. The grey claystone beds include well-preserved drifted plant macrofossils (Abu Hamad et al., 2008; Mustafa, 2003) and coalified logs. Black organic-rich siltstones were sampled (Plate 7; MPA 62259 to MPA 62261) and yielded diverse assemblages.

As the section is traced southwards, the laterally-accreted channel thins and wedges out to be replaced by level-bedded, floodplain red-beds comprising red to red-brown fine-grained sandstone and siltstone with occasional rippled surfaces and faint surface burrows (Plate 10). At some levels desiccation cracks are present and there are deep vertisol palaeosol horizons. The latter are characterised by red, mauve, yellow, and brown colour-mottling and the presence of granule to pebble-size limonite and goethite soil glaebules. Some of the highly evolved palaeosol horizons are over 3 m thick, often located within abandoned, clay-filled channels (Plate 11).

Locality 8 lies in a small east-west side wadi that exposes the upper part of the Umm Irna Formation succession (see Sample 62263 locality, Figure 9). Here, evolved palaeosol beds are overlain by a series of stacked, laterally accreted channel sandstones. The upper channel overlies an abandoned channel infilled with grey to black organic-rich siltstone and claystone (Plate 11), which provided samples MPA 62262 to 62264. Sample MPA 62263 yielded a diverse assemblage.

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Sequence boundary

Palaeosol

Laterally accreted, grey, red and yellow channel sandstone

2.0 m Laterally accreted, grey sandstone with palynomorphs and macro-fauna

Claystone with Reddened laterally coaliﬁed log accreted unit Plant fragments in claystone

Grey organic-rich 2.0 m laterally accreted unit

Plate 7: Dyke Plateau cliff (Locality 7) showing laterally accreted, grey organic-rich claystone and mudstone with plant fragments, coaliﬁed drifted wood and palynomorphs (see inset photographs) overlain by reddened, laterally accreted sandstone and palaeosol; hammer length 0.33 m. Red rectangle shows area of Plate 8.

Red-bed ﬂoodplain sandstones (ripples and desiccation cracks)

Sequence boundary

Bruniﬁed palaeosol

ﬁrst-order lateral accretion surfaces

second-order lateral accretionLow-sinuosity surfaces channel sandstone (point-bar) with carbonaceous mudstone lenses (plant macro-fossils and palynomorphs)

Plate 8: Dyke Plateau cliff (Locality 7) showing ﬁrst- and second-order lateral accretion surfaces in red and grey sandstones overlying grey organic-rich claystones, mudstones and ﬁne-grained sandstones. See Plates 6a and 7 for orientation.

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Locality 9: Panorama Road (West) This locality (N31°39’08.8’’, E35°34’43.3’’) is opposite Locality 2 on the western side of the new Panorama Road (Figure 1). Two thin carbonaceous siltstones overlie leached grey white fine-grained quartz sandstone, with rootlet traces (Plate 3b). The underlying sandstones represent leached evolved, seatearth palaeosols. The carbonaceous siltstones were sampled but no palynomorphs were recovered.

a Quartz and feldspar granules Floodplain palaeosol rip-up clasts Palaeoﬂow WSW

Trough cross-bedded channel-fill

Base of channel Pebbly channel-ﬁll

1 m Ferralitic palaeosol Base of channel Plate 9: Major channel sandstone at northern end of Dyke Plateau cliff (see Figure 9 for location). (a) Base of channel is cut in to pedogenically altered sandstone; channel-fill is composed of sub-rounded pebbles of quartz and pink feldspar with more angular, poorly sorted, rip-up clasts of reddened floodplain sediments including goethite/haematite nodules. The upper part of the channel-fill comprises yellow, trough cross-bedded, medium-grained sandstone (see Figure 9 for palaeoflow).

Surface

Trough cross-bedded channel-ﬁll: rib and furrow

Organic-rich laminae on foresets

Pebbly channel-ﬁll: quartz and feldspar granules

(b) Detail of upper channel-ﬁll with organic-rich lamina at base; insets show basal pebbly sandstone channel ﬁll, and rib and furrow structure on bedding surfaces. Hammer length 0.33 m.

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UMM IRNA FORMATION LITHOFACIES ASSOCIATIONS

The principal lithofacies associations in the Umm Irna Formation are described below and summarised in Table 1.

Channel-fill Sandstone (Cfs) Channel-fill sandstones are composed predominantly of medium- to coarse-grained, feldspathic sandstone with granules and small pebbles of quartz and pink feldspar. The sandstones comprise upward-fining units with channelised, scoured basal contacts (Plate 9). Medium- to large-scale, trough cross-bedding with graded foresets is the most common bedform within the channelised units (Plate 9). In the lower part of the formation in the Al Mamalih area (Powell and Moh’d, 1993) that represents the southernmost outcrop (Figure 1), and in the northern outcrops (Makhlouf et al., 1991) the palaeocurrent trend within channels is predominantly to the northwest. However, 100 palaeocurrent measurements taken from trough cross-bedding on multiple, present-day erosion surfaces within a major channel in the upper part of the formation (Dyke Plateau Locality 7; Figure 9) reveal a predominantly unimodal west-northwest to west-southwest palaeoflow depending on the position of the channel branch and stacking level within the main channel complex. This sediment dispersal pattern is in broad agreement with the WSW trend of the major channels in the upper part of the formation of the northern outcrops recorded by Makhlouf et al. (1991). The stacked channel sandbodies at Locality 7 show increasingly divergent palaeoflow directions in the upper part of the channel (Figure 9; Plates 6 and 9); these sandstones are fine- to medium-grained, in contrast

Table 1: Summary characteristics of Umm Irna Formation lithofacies associations.

Lithofacies Dominant Lithologies Dominant bedform Colour Palaeoenvironment Association

Channel-ﬁll Sandstone, medium- to Trough cross-bedding; Yellow, grey and white Low-sinuosity to braided sandstone coarse-grained; pebbly in scoured erosive channel ﬂuvial channels (Cfs) part (quartz, feldspar and bases reworked goethite–limonite nodules). Thin carbonaceous laminae, on foresets

Laterally accreted Sandstone, fine- to Laterally accreted units Yellow, grey and white Laterally accreted point channels; medium-grained; drifted with ripple cross-laminated (abandoned channel-fill bars in low-sinuosity river point bars wood and plant fragments; fine-grained sandstone mudstones may be channels (Lac) siltstone and claystone red-mauve- yellow lenses and abandoned palaeosols) channel plugs

Interfluve Sandstone, fine- to Ripple cross-lamination; Red and mauve Floodplains, interfluves (floodplain) medium-grained; siltstone desiccation cracks; (brunified) soils (poorly and shallow lakes sediments (ls) and claystone small-scale cross-lamina- evolved palaeosols) tion Ferralitic Parent sediments of Palaeosol horizons ranging Red, mauve yellow, Emergent floodplains and palaeosols (Fps) sandstone, fine- to from early reddening to the brown and white interfluves subjected to a medium-grained, mudstone development of secondary range of oxidative soil with ferruginous goethite- iron glaebules; desiccation processes resulting from limonite glaebules cracks and vertical cracks fluctuating groundwater table

Coals and Poorly developed silty coals Fissile but with occasional Black and dark grey Peaty mires and shallow organic-rich and organic-rich siltstones; leached seatearths with ponds developed in the soils (Cors) occasional leached vertical rootlets waterlogged parts of the seatearth sandstones, ﬂoodplain (generally close below to the main ﬂuvial channels)

Organic-rich Siltstone and claystone with Fissile Grey and pale grey Thin lag deposits within mudstones well preserved plant laterally accreted point bars (Orm) macrofauna units (waning current) and ponded-up abandoned channels or ox-bow lakes Tidal estuarine Siltstone and ﬁne-grained Horizontally bedded with Red, grey and yellow Tidal and estuarine to marine sediments (Tes) sandstone wave ripples, tidal bundles embayments and horizontal burrows

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to the underlying coarse-grained, granule-rich sandstone, and include grey claystones with plant macrofossils and dark grey organic-rich siltstones deposited as channel lag drapes on trough cross- bed foresets. These fine-grained siltstone beds are also common in point-bar lithofacies association (see below).

The major ‘winged’ channels are up to 35 m wide and up to 7 m in height (Plates 1 and 2). They pass laterally into small-scale, trough cross-bedded units at channel margins. Channel bases are often incised up to 3 m depth into surrounding floodplain sediments and often contain a basal conglomerate (channel-lag) composed of rounded and sub-rounded rip-up clasts such as pedogenic ferralitic iron glaebules derived from the erosion of local red-bed palaeosols (Plate 9; see below). These locally sourced clasts pass up, by contrast, to sub-rounded granules and pebbles of quartz and pink feldspar derived from a more distant source (Plate 9). Individual channel sand-bodies are vertically stacked and show low-sinuosity with minor deviation of the principal channel axes (Figure 9).

Laterally Accreted Channels (Point Bars) (Lac) Near the Dead Sea foreshore (Localities 7 and 8, Dyke Plateau; Locality 3; Plates 6 to 9) laterally accreted, fine- to medium-grained sandstones with grey, macroplant-rich claystones and dark grey organic-rich siltstones and immature coals infill broad, shallow channels cut into the overbank/ floodplain red sandstone and siltstones (Plates 6b and c). Lateral point-bar migration is shown by multiple-stacked, low-angle laterally accreted units (Allen, 1965; Miall, 1977). The plant-rich and organic-rich siltstones and claystones were deposited during low flow regime conditions, and the exceptional preservation of much of the macroflora (Plate 11) indicates settlement from suspension in abandoned minor channels within the point-bar complex. Similar laterally accreted channel fills often associated with well-preserved, drifted plant beds within point-bar units (c.f. Dyke Plateau; Plate 7) have been described from the broadly coeval Unayzah Formation at outcrop in Central Saudi Arabia (El-Khayal and Wagner, 1985; Senalp and Al-Duaiji, 1995), and in the Gharif plant beds in the Gharif Formation, Oman (Broutin et al., 1995). In places, the upper part of the Umm Irna Formation shows evidence of horizontal sand-filled burrow networks (Plate 4). This suggests estuarine or brackish conditions within estuarine embayment during periods of relative high sea-level stands.

Interfluve Sediments (Is) Sediments between, and adjacent to, the major channel sandstones consist of red-mauve, planar- laminated to ripple cross-laminated siltstone and fine-grained sandstone, with occasional silty mudstone, ranging in colour from red to red-mauve to yellow-grey (Plates 1, 2 and 6). The intense red coloration is a result of oxidation and brunification of these well-drained, flood-plain sediments in a seasonal humid climate (Besly and Fielding, 1989; Glover and Powell, 1996). Occasional desiccation cracks and indeterminate surface burrows are present in the red siltstones (Plate 11) indicating periodic emergence of the floodplain. These sediments make up the bulk of the Umm Irna Formation and are interpreted as heterolithic overbank sheet-flood deposits with localised shallow lakes and peaty mires (see Coals and Organic-rich Soils (Cors), below). Secondary pedogenesis is common in these sediments.

Ferralitic Palaeosols (Fps) Red silty claystone and siltstone sediments that make up the bulk of the floodplain interfluve sediments between the yellow-grey channel sandstones contain pedogenic ferralitic palaeosol horizons (Duchafour, 1982; Wright, 1986; Retallack, 1988). These are present throughout the formation, but are more common in the upper part. They comprise yellow-brown, ferruginous (goethite-haematite) soil glaebules ranging in diameter from a few millimetres to a few centimetres within vari-coloured (red, yellow, mauve and grey) siltstone (Plates 10 and 11). Some of the palaeosol beds are associated with polygonal desiccation cracks, penetrating up to 0.20 m deep, with a yellow-brown weathered zone up to 0.01 m either side of the crack. Palaeosol horizons range in thickness from about 0.20 to 0.40 m in the lower part of the formation to deep, highly evolved palaeosols including vertisols up to 1.5 m thick in the upper part of the formation (Plate 11).

The palaeosols are interpreted as having formed diagenetically within the vadose zone of fine-grained, interfluvial floodplain deposits, in a tropical savanna climate, characterised by alternating wet and dry seasons, and strong leaching of iron (Makhlouf, 1987; Makhlouf et al., 1991; Powell and Moh’d, 1993).

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Faint surface burrows

Level-bedded sandstone with faint surface burrows

Channelised sandstone

c Palaeosol 1.0 m

Reddened sandstone with wave ripples, desiccation cracks and faint surface burrows

Plate 10: Uppermost Umm Irna Formation, Dyke Plateau (see Figure 9 for location, above major channel sandstone). Reddened ﬁne-grained sandstone with wave ripples (inset a) and desiccation cracks (inset b), overlain by a palaeosol and channel sandstone. The sequence boundary (SB) marks the base of the increasingly more marine/estuarine environments with faint surface burrow traces (inset c).

The presence of deep polygonal desiccation cracks in some of the palaeosol horizons suggests that the climate was seasonally arid. Iron glaebules are characteristic of ferralitic palaeosols (Duchafour, 1982) in which concentric haematite (or in some cases goethite and/or limonite) forms as a result of intense cycles of wetting and drying in the ‘B’ horizon of well-drained oxidised soils (Retallack, 1988; Besly and Fielding, 1989; Glover and Powell, 1996). Although ferralitic soils commonly form in equatorial and humid tropical climates with a very short dry season, they also form in drier climatic zones, even savannas (Mohr et al., 1972). Haematite forms in preference to goethite in dry climates when organic matter is present in only small amounts (Duchafour, 1982; Wright, 1986).

Caliche soil horizons, which typically develop in semi-arid and arid climates with fluctuating groundwater levels, are not present in the Umm Irna Formation, but have been described in the broadly co-eval upper part of the Unayzah Formation of Central Saudi Arabia (Senalp and Al-Duaiji, 1995). Thick (deeper) palaeosol horizons in the Umm Irna Formation indicate a long residence time for palaeosol development on the floodplain, perhaps over hundreds or thousands of years, with low vertical sedimentation rates as compared to the thin poorly evolved palaeosol horizons in the lower

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part of the formation. Deep soil profiles showing red-brown to grey-yellow horizonation, together with both haematite glaebules and desiccation cracks indicate more evolved palaeosols similar to present-day lateritic soils, which develop in regions with seasonally fluctuating groundwater levels (Mohr et al., 1972).

Coals and Organic-rich Soils (Cors) Although much of the Umm Irna Formation comprises oxidised red-beds and associated palaeosol horizons, it also contains a variety of beds rich in organic-matter formed in anaerobic or dysaerobic conditions. These include in-situ, poorly developed thin coals (ca. 0.05 m thick) some with downward- penetrating carbonaceous rootlets (up to 0.5 m depth) and others underlain by hard, pale grey seatearth sandstone beds (Plate 3b) interpreted as leached siliceous soil horizons underlying the

a Channel sandstone overlying mudstone ﬁll with plant fragments

2.0 m

Abandoned channel mudstone with deeply developed palaeosol

b c Trough cross-bedded sandstone

Organic-rich mudstone drape in base of channel

Carbonised leaf fronds Erosive base

Grey mudstone Carbonised leaf fronds

Plate 11: (a) Upper Umm Irna Formation, Dyke Plateau south (see Plate 6c right) for location. (b) Close up view of mud-ﬁlled abandoned channel with pedogenetically altered mudstone, overlain by grey organic-rich mudstone with drifted plant debris at the base of the channel, in turn overlain by yellow channel sandstone with organic-rich mudstone drapes on foresets. (c) Close up of carbonised leaf fronds.

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peaty mire (Besly and Fielding, 1989; Glover and Powell, 1996). These thin coal beds developed as localised, short-lived peaty mires in the interfluves, and although they are more common in the lower part of the formation (Dill et al., 2010) (see Locality 1, type section Wadi Himara) they are also present in the upper part of the formation (Locality 6, Wadi Autun; Locality 8, Dyke Plateau), but here they are associated with, or in close proximity, to the larger fluvial channels. Samples of the plant debris- rich, coaly beds from Locality 9 (Plate 3b) proved to be barren of palynomorphs; this may be due to destruction of organic matter during pedogenesis.

Organic-rich Mudstones (Orm) These comprise grey, grey-black and black claystones and siltstones with a high proportion of organic-matter in the form of palynomorphs and drifted, disseminated plant fragments, including some exceptionally well-preserved plant fossil assemblages (Kerp et al., 2006; Abu Hamad et al., 2008; Plates 7 and 11). In contrast to the in-situ coals and organic-rich soils described above, these are most commonly found as thin lag deposits draping laterally accreted foresets within point bar units (Plates 6 and 7), and within ponded-up abandoned channels either within the point bar complex or in abandoned channels (ox-bow channels) (Plate 11).

Tidal-estuarine Sediments (Tes) Sediments deposited in tidal and estuarine palaeoenvironments in the Umm Irna Formation are uncommon (Figures 5 and 6; Plates 4 and 10). They comprise thin beds of red, yellow and grey siltstone and fine-grained sandstone beds, generally horizontally bedded with small-scale bedforms such as wave ripples, tidal bundles, and networks of horizontal circular burrows (Plate 4) (the latter often destroying any original sedimentary fabric), and surface burrow traces (Plate 10). Marine macrofossils have not been identified in these beds, but the bedforms, ichnofossils and absence of large-scale cross-bedding indicates deposition in tidal or estuarine embayments, during periods of sea-level rise (Figures 2 and 10).

DEPOSITIONAL SETTING AND COMPARISON WITH THE GHARIF AND UNAYZAH FORMATIONS

The depositional environments of the Umm Irna Formation have been described previously (Makhlouf et al., 1991; Powell and Moh’d, 1993; Uhl et al., 2007; Abu Hamad et al., 2008; Dill et al., 2010). The general consensus, supported by the current study, suggests deposition in a fluvial regime characterised by low-sinuosity channels with deposition on point bars, and as stacked small-scale braided channels (Figure 10). The depositional environments are similar to those described for the Gharif Formation alluvial plain ‘Type Environment P2’ in the subsurface in Oman (Osterloff et al., 2004) and the upper part of the Unayzah Formation at outcrop and in the subsurface in Central Saudi Arabia (Senalp and Al-Duaiji, 1995).

Umm Irna Formation floodplain interfluves were characterised by low-energy sheet-flood deposits, shallow lakes and ponds. Where there was no standing water, the floodplain sediments underwent primary reddening (‘brunification’) in an oxidising humid climate to semi-arid climate characterised by seasonal ground-water fluctuation, which resulted in the development of poorly- to highly- evolved ferralitic palaeosols depending on the residence time of the soil horizon (Figure 10).

In areas adjacent to the main channel axes, organic matter was preserved in shallow ponds and small lakes as drifted plant remains. The large size and exceptional preservation of much of the plant fossil material suggests that the plant communities thrived in, or adjacent to, these wetter areas (in contrast to the more oxidising condition on the interfluves). Plant fragments commonly preserved in yellow- grey, thin claystone and siltstone beds are interpreted as representing localised hydromorphic, waterlogged conditions (ponds) on the flood-plain. During wetter climatic phases and in wetter ecological niches adjacent to the ephemeral river channels, plant communities thrived to produce thin peaty mires with a reasonably long residence time, sufficient to produce thin immature coals or organic-rich mudstones with underlying rootlets beds and, in places, leached seatearth sandstones. Climatic and/or local microclimate conditions on the floodplain were sufficiently waterlogged and anaerobic/dysaerobic at times to preserve the organic matter.

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Cors

s Cf Oxidised ﬂoodplain with ﬂuctuating groundwater-table

s Desiccation cracks

n sediments n Is

Brunified (red-bed) Brunified floodplai Desiccation cracks Iron glaebules Fps Fps Unconformity Fps Orm Is Ferralitic palaeosols with iron glaebules Carbonaceous mudstone with rootlets Abandond channel and ponds Sediment source area Lac Lac Orm Cors Cfs Cfs Laterally accreted channels Stacked sandstone channels Point bar Is Peaty mires Crevasse splay Lac Point bar Cors Low-sinuosity channels Cors Cors N Cfs Cambrian Sandstone mudstone rtical mottling Thin carbonaceous Desiccation cracks Rootlets Glaebules Ve (palaeosol) Point bar s Is Low gradient alluvial plain s Figure 10: Reconstruction of palaeoenvironments and alluvial architecture the Umm Irna Formation. Brunified (red-bed) floodplain sediments Fps ve ripples Wa and burrows ca. 50 cm Channel-fill sandstones Interfluve sediments Organic-rich mudstone Ferralitic palaesols Coals and organic-rich soils Laterally accreted channel ======Cfs Orm Iron glaebules in channel base Coaly laminae and grey mudstone with macro-flora draping foresets Orm Lac Cfs Is Cors Fps Estuarine embayment in abandoned channel

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There is evidence (see below) that the palynomorph communities were highly specialized and occupied ecological niches adjacent to the floodplain ponds (high abundance – low diversity communities). In other organic-rich claystone and siltstone beds the palynomorph and macroplant communities are more diverse, suggesting transport down-stream from a variety of plant community niches adjacent to the main river channels or in the broader river hinterland (Figure 10).

The fluvial red-bed sequences in the Umm Irna Formation (Jordan) and the upper Unayzah Formation at outcrop (Central Saudi Arabia) are similar, but there are notable differences in the development of palaeosol horizons in the interfluves. In addition to reddened (oxidised) palaeosol horizons in the outcrop upper Unayzah Formation (Delfour et al., 1982; El-Khayal and Wagner, 1985; Al-Laboun, 1987; Senalp and Al-Duaiji, 1995) the formation contains both caliche (calcrete) and nodular anhydrite/ gypsum attributed to deposition in an arid to semi-arid environment.

These carbonate and sulphate pedogenic phases are absent from the Umm Irna Formation in Jordan. By contrast, the pedogenic processes are dominated in Jordan by localised deep vertical leaching (varicoloured vertisols), and iron (limonite/goethite) glaebules, often developed below coaly and or plant-rich siltstone beds. We attribute these variations in palaeosol type to the Umm Irna Formation depositional area being located further north, closer to the palaeoequator (Stampfli and Borrel, 2002) in a more humid climatic regime than that of the upper Unayzah where evaporation of groundwater was less intense, so that caliche, gypsum and anhydrite were not precipitated in the soil profile. Vertisols, locally developed up to 3 m depth (Plate 11a), in the Umm Irna Formation also indicate a humid, tropical climate with relatively long residence times for palaeosols to develop. Similar variations in vertisol and caliche palaeosol development attributed to climatic change on Pennsylvanian to Early Permian floodplains were noted by Glover et al. (1993) and Glover and Powell (1996). These variations in palaeosol development and the presence of horizontal burrows at some horizons in the Umm Irna Formation (Plate 4) might, however, reflect a broad depositional setting, with the burrowed, coaly succession in the Jordan succession having been deposited in a coastal, low gradient alluvial plain and the Central Saudi Arabia succession representing a more upland area with a drier climate. The burrowed horizons are associated with thin tidal clinoforms (Figure 10) and thin carbonaceous claystones and siltstones with abundant palynomorphs (Localities 3 and 4; Figures 5 and 6). We interpret these sequences as representing high sea-level stands that resulted in shallow-marine or brackish incursions across the low-gradient alluvial plain, probably within lower relief areas of abandoned channels. There is evidence that peaty mires develop preferentially on the floodplain during sea-level highs as a result of marine flooding and raised groundwater levels during high stands (Wright and Marriott, 1993; Glover and Powell, 1996).

A significant sea-level rise, heralding the marine Ma’in Formation, is marked by a sequence boundary (SB in Plate 6) near the top of the Umm Irna Formation. Above this boundary, channel sandstones are absent, and furthermore, level-bedded red-beds show evidence of wave ripples, faint burrow traces and occasional desiccation cracks; these characteristics suggest brief episodes of estuarine or brackish marine flooding in a marginal-marine embayment. Rising sea-level had the effect of lowering the geomorphological gradient, thus inhibiting channel incision. The sequence boundary overlies the most extensive low-sinuosity channels (Locality 7, Dyke Plateau) rather than braided channels, again indicating increasing sinuosity of the rivers during rising sea level (Wright and Marriott, 1993).

PALAEOFLOW AND PROVENANCE OF THE UMN IRNA FORMATION SANDSTONES

Palaeocurrent azimuths taken from the channel sandstones during this study, combined with those from the Al Mamalih area to the south (Powell and Moh’d, 1993) and in the north of the outcrop (Makhlouf et al., 1991) indicate sediment dispersal to the northwest and west-northwest (see above). This indicates a variable sediment dispersal pattern throughout the formation with a spread of about 60 degrees (Figure 9). Previous studies (Makhlouf et al., 1991; Powell and Moh’d, 1993; Dill et al., 2010) suggested that the likely provenance is a granitoid, igneous source since the coarse-grained channel sandstones include fresh, sub-rounded, pink feldspar granules. The immature, unweathered nature of the feldspar clasts suggests that, (a) the source area was not distant, and (b) the climate in

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the source area was semi-arid or arid in contrast to the more humid depositional floodplain basin. Heavy mineral analysis (Dill et al., 2010) of the channel sandstones indicates a zircon- and thorium- enriched monazite suite that they correlated with the alkaline granite suite exposed about 200 km to the south in the Arabian-Nubian Shield (McCourt and Ibrahim, 1990). Dill et al. (2010) concluded that the preponderance of stable to ultrastable heavy mineral assemblages suggest a rather long transport or, in contrast, chemical disintegration of labile minerals. They favoured the decomposition of labile constituents (presumably under humid climatic conditions) rather than a very distal source of zircon. However, this hypothesis does not account for the very fresh, unaltered feldspar granules (Plate 9) in some of the Umm Irna Formation channel sandstones which must have been deposited rapidly and not far distant from the presumed granitoid source area.

Furthermore, during the Permian any ‘Precambrian’ granitoid terrain (i.e. potential source area) in central Jordan located to the east and southeast of the outcrop as indicated by the palaeocurrent flow, would be overlain by a thick succession of Lower Palaeozoic sandstones (Ram Group; Cambrian to Ordovician in age; Powell, 1989) of predominantly fluvial origin, and further to the southeast in the Tabuk Basin these, in turn, are overlain by Ordovician to Silurian marine and glaciogenic siliciclastic sediments (Khreim Group; Powell, 1989). Consequently, near the Jordan-Saudi Arabia border in the Wadi Sirhan area, the granitoid basement rocks are buried to more than 5,000 m below this siliciclastic sedimentary cover.

The unweathered nature of the coarse-grained detrital feldspars in the Umm Irna Formation channel sandstones, which are considered to have been deposited in low-sinuosity channels in a humid to semi-arid climatic regime, suggests that the Umm Irna Formation sediments were not secondarily derived from mature siliciclastic Lower Palaeozoic cover rocks. Dill et al., (2010) favoured a provenance of Umm Irna channel sands from the granitoid, cratonic shield rocks which extend from Aqaba, in south Jordan, (Aqaba Complex; Ibrahim and McCourt, 1995) to the Midyan (Nadj) Terrain of Saudi Arabia. Sedimentary cover rocks may have been absent from parts of these shield areas due to non-deposition, or more probably, as a result of rapid erosion of the isostatically-buoyant, Arabian-Nubian granitoid terrain in mid- to late Palaeozoic times. The present-day disposition of these granitoid basement rocks indicates fluvial transport of at least 200 km. If the climate had been equatorial humid (see evidence above), then the feldspars might be expected to be extensively altered by chemical weathering. Furthermore, the palaeocurrent measurements from this study (Figure 9) and earlier publications (Makhlouf et al., 1991; Powell and Moh’d, 1993) indicate a pronounced westward flow with a source area located somewhere to the east or southeast, in current-day Central Saudi Arabia rather than a source area located to the south i.e. the present-day Aqaba granitoid shield. The source area may have been the Neoproterozoic granitoid rocks exposed on the Ha’il Arch located to the east or southeast (Figure 2b).

An alternative hypothesis envisages the immature pebbly, coarse-grained channel sandstone clasts being secondarily derived from pre-existing, relatively unaltered Pennsylvanian-Early Permian glaciofluvial outwash sandstones (e.g. distal outwash sandur-plain sediments) located somewhere to the east-south east. Extensive glaciogenic and glaciofluvial siliciclastics of Early Permian age (lower part of the Unayzah Formation) have been described from Central Saudi Arabia (Melvin and Sprague, 2006). They describe quartzose sandstones from the Unayzah B member with well-rounded very coarse-grained quartz sand and granules and pebbles including granite, quartz and feldspar laid down on an extensive glaciofluvial outwash braidplain upon the pre-Unayzah unconformity, which were later overidden by morainic deposits deposited by advancing ice-sheets associated with the end-Carboniferous–Early Permian glaciation. Thus, a source area located to the east (in relative terms prior to Arabian Plate rotation) is a better fit for the predominantly westerly palaeocurrent data.

In Central Saudi Arabia similar quartz-rich pebble sandstones are present in the Unayzah Formation, again unconformably overlying Lower Palaeozoic sandstones that, in turn, overlie granitoid basement rocks of the Arabian Shield (Senalp and Al-Duaiji, 1995). Here, north and northeast palaeoflow indicates dispersal away from the Neoproterozoic Shield.

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PALYNOLOGY

Twenty-five samples were processed and of these only one was barren of palynomorphs. A few samples yielded less than ten palynomorphs, but generally samples yielded large populations of palynomorphs, which were moderately- to well-preserved (Plates 12 to 16). The assemblages are

a b c

e f

Scale bar for all 70µ

g h i j

k l m n

o p

Plate 12: Palynomorphs of the Umm Irna Formation. Slides are held in the collection of the British Geological Survey, Keyworth, Nottingham, NG12 5GG, UK. Specimen locations are given by England Finder code. (a and b) Camptotriletes warchianus, V56/4, MPA 62242; (c to e) Protohaploxypinus uttingii, D53/3, MPA 62253; (f) Distriatites insolitus, S50/1, MPA 62242; (g and h) Protohaploxypinus uttingii F51/4,MPA 62253; (i and j) Protohaploxypinus uttingii, F46/4, MPA 62253; (k and l) Protohaploxypinus uttingii, O52, MPA 62253; (m and n) Protohaploxypinus uttingii, N44/3, MPA 62253; (o and p) Falcisporites stabilis (lateral view), C46/4, MPA 62256.

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very variable but in general contain common non-taeniate bisaccate pollen (mainly fragmentary or too poorly preserved to be identified); those that are determinable include Falcisporites stabilis, Alisporites nuthallensis, A. indarraensis, and Cedripites priscus. The most common taeniate bisaccate pollen is Protohaploxypinus uttingii and P. limpidus. Monosaccate pollen is rare. The colpate pollen Pretricolpipollenites bharadwaji is common in a few samples. A group of ornamented monolete spores is very common in one sample.

Palynological Sample Descriptions

Palynological samples were taken from nine sections (Figures 1 and 2), the sedimentology of which is described above.

a b

c d

e f

Scale bar for all 50µ

g h

Plate 13: (a and b) Alisporites nuthallensis, S58, MPA 62256; (c and d) Falcisporites stabilis, F56/2, MPA 62256; (e and f) Falcisporites stabilis, N63/2, MPA 62256; (g and h) Alisporites nuthallensis H59/1, MPA 62256.

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Locality 1: Wadi Himara South Side Palynological samples from the lower claystone (Figure 3) yielded rather sparse assemblages dominated by indeterminate bisaccate pollen, Alisporites nuthallensis, Cedriptes priscus and Falcisporites stabilis. The assemblages also contain a few spores including the monolete spore taxa Laevigatosporites spp. and Thymospora cf. opaqua, and Playfordiaspora cancellosa. A single specimen of Pretricolpipollenites bharadwaji occurs in the lower sample.

Locality 2: Panorama Road (East) The two lower samples (Figure 4) yielded rather sparse assemblages dominated by indeterminate bisaccate pollen but with recognisable Alisporites nuthallensis and Falcisporites stabilis. The upper samples were more diverse with indeterminate bisaccate pollen, Alisporites nuthallensis and Falcisporites stabilis, but also with the coarsely ornamented triangular spore Camptotriletes warchianus and the distally-taeniate pollen Distriatites insolitus.

Locality 3: Wadi Zerqa Ma’in South The claystone and siltstone beds yielded four palynological samples (Figure 5), of which two yielded moderately well preserved diverse assemblages (at 3.0 and 3.8 m below the top of the section) containing Alisporites indarraensis, A. nuthallensis, bisaccate indeterminate pollen and Falcisporites stabilis. The lower of the two samples is the more diverse, containing Cristatisporites spp., Distriatites insolitus, Laevigatosporites cf. callosus and common Protohaploxypinus uttingii.

Locality 4: Side Wadi South of Wadi Zerqa Ma’in A 2 m thick siltstone yielded two diverse and well-preserved assemblages (Figure 6), which contain common indeterminate bisaccate pollen, Alisporites nuthallensis and Falcisporites stabilis. The upper sample was unusual in relation to the Umm Irna Formation in containing common monosaccate pollen which, were in general too poorly preserved to allow determination, but probably consisted mainly of the genera Cannanoropollis and Potonieisporites. The lower sample contains a rather unusual assemblage of common probable algal cysts and spores (Leiosphaeridia spp. and Peroaletes khuffensis) as well as very abundant Protohaploxypinus uttingii. Both samples contain the distally-taeniate pollen Distriatites insolitus.

Locality 5: Roadside Section South of Wadi Zerqa Ma’in A siltstone sampled twice (Figure 7) yielded well-preserved diverse assemblages dominated by indeterminate bisaccate pollen, Alisporites nuthallensis, Cedripites priscus and Falcisporites stabilis. The upper sample (at 3.7 m below the top of the section) contains common Leiosphaeridia spp., as well as the probable algal palynomorph Peroaletes khuffensis. The enigmatic, probable algal palynomorph Reduviasporonites chalastus occurs in small numbers in both samples, as does the monolete spore Thymospora opaqua.

Locality 6: Wadi Autun Two carbonaceous siltstone beds, separated by about 5 m of sandstone and siltstone (Figure 8), yielded moderately well-preserved assemblages, which are quite distinct from each other (despite their stratigraphical proximity), and from other assemblages recovered from the Umm Irna Formation. The lower sample yielded an assemblage containing common bisaccate pollen (Cedripites priscus and Falcisporites stablis) but also the probable algal palynomorph Leiosphaeridia, and the trisulcate pollen Pretricolpipollenites bharadwaji. The latter is very well preserved. The upper sample, 4.35 m above, is quite different in composition, and slightly more diverse, but contains no specimens of Pretricolpipollenites bharadwaji, and is dominated by well-preserved spores, tentatively assigned to the ‘Torispora-Thymospora complex’. This sample is the most spore-dominated of all the Umm Irna samples. Other spores in this assemblage include Punctatisporites spp. and the probable lycopsid spore Playfordiaspora cancellosa.

Localities 7 and 8: Dyke Plateau The cliff section (Locality 7; Figure 9) includes a laterally accreted channel sandstone-siltstone- claystone complex with evolved palaeosols. Low-angle lateral accretion surfaces in the complex are draped by thin beds and laminae of grey claystone and black organic-rich siltstone which contain well-

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a a b b c c d d e e f f m m n n o o p p q q r r

g g h h i i j j k k l l s s t t u u v v w w

Scale barScale for bar all 70forµ all 70µ x x y y z z

Plate 14. (a) – (b) Thymospora opaqua, J69/3, MPA 62256; (c) – (d) Torispora-Thymospora complex, C59/4, MPA 62258; (e) – (f) Torispora-Thymospora complex, C58, MPA 62258; (g) Torispora- Thymospora complex, C57/3, MPA 62258; (h) Torispora-Thymospora complex, C57/2, MPA 62258; (i) – (j) Torispora-Thymospora complex, C41/2, MPA 62258; (k) Torispora-Thymospora complex, D62/3, MPA 62258; (l)Torispora-Thymospora complex, D62/3, MPA 62258; See facing page for continuation.

preserved macrofossils and coalified logs. Black organic-rich mudstones were sampled (Plate 7; MPA 62259 to MPA 62261) which yielded diverse very similar assemblages dominated by indeterminate Scale barScale for bar all 70forµ all 70µ bisaccate pollen, Alisporites nuthallensis and Falcisporites stabilis. However these samples are amongst the most diverse of those recorded from the Umm Irna Formation and are interesting in that they derive essentially from the same horizon, being separated by approximately 5 m laterally along the cliff (Plate 6). Other taxa present include common Protohaploxypinus spp., and other indeterminate taeniate bisaccate pollen, Lueckisporites virkkiae and similar forms, Reduviasporonites chalastus, Potonieisporites spp., Thymospora opaqua and Playfordiaspora cancellosa. In all three samples, non-taeniate bisaccate indeterminate pollen make up more than 75% of the assemblages, and taeniate bisaccate pollen is dominant amongst the rest of the assemblages.

Locality 8 lies in a small east-west side wadi approximately 300 m south of Locality 7. Here, an abandoned channel infilled with grey to black organic-rich siltstone and mudstone (Figure 9) provided samples MPA 62262 to 62264. MPA 62262 and 62264 were very sparse, containing only a few poorly preserved bisaccate pollen but MPA 62263 yielded a diverse assemblage containing very common Cedripites priscus, Pretricolpipollenites bharadwaji and Reduviasporonites chalastus as well as the Torispora-Thymospora complex (as seen in the upper sample of Locality 6, Wadi Autun). Also present are Leiosphaeridia spp., Taeniaesporites spp., and Thymospora opaqua.

Variation in the Palynology of the Umm Irna Formation

The most common type of palynological assemblage in the Umm Irna Formation is one dominated by non-taeniate bisaccate pollen (usually indeterminate due to fragmentary preservation), as well as by Alisporites nuthallensis, A. indarraensis and Falcisporites stabilis. Five out of the 25 samples processed yielded this assemblage. However, surprising variation was also observed between samples separated by only a few metres stratigraphically and geographically. Taxa that might be considered

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g h i j k l s t u v w

Scale bar for all 70µ x y z

Scale bar for all 70µ

Plate 14 (continued): (m) – (n) Torispora-Thymospora complex, D59, MPA 62258; (o) Torispora- Thymospora complex, D59/3, MPA 62258; (p) Torispora-Thymospora complex, D55, MPA 62258; (q) – (r) Torispora-Thymospora complex, F52, MPA 62258; (s) – (t) Torispora-Thymospora complex, F46, 62258; (u) Torispora-Thymospora complex, H67/2, MPA 62258; (v) – (w) Torispora-Thymospora complex, G60/4, MPA 62258; (x) Falcisporites stabilis, G62/3, MPA 62259; (y) Falcisporites stabilis, W44/1, MPA 62259; (z) Lueckisporites virkkiae, M53, MPA 62260.

to be stratigraphically significant: Alisporites nuthallensis, Cedripites priscus, Distriatites insolitus, Falcisporites stabilis, Playfordiaspora cancellosa, Pretricolpipollenites bharadwaji, Protohaploxypinus uttingii, Reduviasporonites chalastus, and Thymospora opaqua, show no particular confinement to parts of the Umm Irna Formation (Table 2), and thus at present it seems futile to attempt a biozonation of the unit. However the variation that is present does require an explanation.

The 25 palynological samples were taken from thin (usually less than 2 m) often laterally impersistent argillaceous units in a sandstone-dominated sequence. Sandstones do not preserve palynological assemblages, thus the sequence of argillaceous units that preserved palynomorphs represents a series of snapshots of the evolving palaeoenvironments of a fluvial regime characterised by low- sinuosity channels with deposition on point bars, and in stacked small-scale braided channels, as well as localised peaty mires on the floodplain.

These snapshots show surprising variability. An example is that from Locality 7, Dyke Plateau, where two argillaceous units were sampled, both from close to the top of the Umm Irna Formation. Samples MPA 62259-62261 were from a single argillaceous horizon (Plate 7) containing abundant

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plant fossils, which is part of a laterally accreted channel sandstone- siltstone-mudstone complex. The unit, which is approximately 5 m wide and < 0.5 m thick, was deposited adjacent to the main channel axes, and the organic matter was preserved in shallow ponds and small lakes as drifted plant remains. Plant fragments commonly preserved in yellow-grey, thin claystone and mudstone beds are interpreted as representing localised hydromorphic, waterlogged conditions (ponds) on the

a b

c d

Scale bar for all 50µ

e g f

j h i k

Plate 15: (a) Falcisporites stabilis, G72/4, MPA 62259; (b) Falcisporites stabilis, P71, MPA 62260; (c) Playfordiaspora cancellosa, V57, MPA 62260; (d) Playfordiaspora cancellosa, D53, MPA 62261; (e) Cedripites priscus, H62/3, MPA 62263; (f and g) Cedripites priscus, Y62, 62263; (h and i) Cedripites priscus, C63, MPA 62263; (j) Cedripites priscus, E53, MPA 62263; (k) Cedripites priscus, E43, MPA 62263.

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floodplain. Assemblages from MPA 62259-62261 are almost identical in terms of the range of taxa and their relative abundances, as might be expected from samples taken a few metres apart at the same level in the same unit. However MPA 62263, from an argillaceous unit a few metres higher in the formation, and from 300 m to the south (Figure 9), yielded a very different assemblage containing very common Cedripites priscus, Pretricolpipollenites bharadwaji and Reduviasporonites chalastus.

a b c

d e f g

h i

j k

Scale bar for all 70µ

Plate 16: (a) spinose acritarch, Q55/4, MPA 62263; (b) Reduviasporonites chalastus, D48, MPA 62263; (c) Pretricolpipollenites bharadwaji, E51, MPA 62263. (d and e) Pretricolpipollenites bharadwaji, H60/4, 62263; (f and g) Pretricolpipollenites bharadwaji, P68, 62263; (h) Taeniaesporites spp. D48/2, MPA 62263; (i) Taeniaesporites spp., W58/1, 62263; (j) Taeniaesporites spp., W58/1, MPA 62263; (k) Laevigatosporites sp. Q48, MPA 62263.

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Table 2: Distribution of stratigraphically signiﬁcant taxa amongst the main localities.

F. A. R. C. P. T. P. D. P. stabilis nuthallensis chalastus priscus uttingii opaqua bharadwaji insolitus cancellosa

Locality 7 X X X X X X X X

Locality 5 X X X X X X

Locality 6 X X X X X X

Locality 4 X X X X X X X

Locality 3 X X X X

Locality 2 X X X X c.f

Locality 1 X X X X X X

A similar example of upsection variation between samples separated by only a few metres is shown in Locality 6, Wadi Autun, where two otherwise similar argillaceous units stratigraphically separated by 4.35 m yielded completely different palynological assemblages. The upper assemblage is made up almost entirely of ornamented monolete spores assigned here to the Torispora-Thymospora complex, the lower is dominated by Pretricolpipollenites bharadwaji. Similarly Locality 4 yielded two samples both from thin argillaceous horizons 1 m apart. The lower assemblage contains a rather unusual assemblage of common probable algal cysts and spores (Leiosphaeridia spp. and Peroaletes khuffensis) as well as very abundant Protohaploxypinus uttingii (a pollen grain recorded only sporadically from the other Umm Irna Formation samples, and rather rarely from Arabian and Pakistan sections (e.g. Stephenson and Filatoff, 2000; Jan et al., 2009); the upper contains a more conventional Umm Irna Formation assemblage with common Alisporites nuthallensis and Falcisporites stabilis.

Variation of this type could be a result of evolutionary or taphonomic processes and changing palaeoenvironment; or could relate to the way that sedimentary processes and local sedimentary environments reflect differing parts of the regional plant community. Variation due purely to evolutionary change is unlikely to be the cause because the time elapsed during and between the deposition of the argillaceous beds is likely to have been small. In addition most of the taxa concerned are known to range throughout the Mid- and Late Permian period and so their local appearances and disappearances need another explanation. The assemblages from Localities 4, 6 and 7 are also well preserved, without obvious signs of preservational bias. Rapid changes in palaeoenvironment are possible, and perhaps could have generated the observed variation. Kerp et al. (2006) considered that the lower part of the Umm Irna Formation had a Gondwanan affinity, because of its Dicroidium fossils, whereas the upper part may have a Cathaysian affinity (based on plant fossils described by Mustafa, 2003). However it seems unlikely that repeated radical palaeonvironmental changes could occur in a timescale consistent with the stratigraphic distribution of the argillaceous beds.

A more likely explanation for variation is sedimentary process and local sedimentary environment (Figure 10). It is known that rivers are the most important transporters of palynomorphs (see for example Muller, 1959). The diverse low-sinuosity channel, point bar, and small-scale braided channel environments of the Umm Irna Formation are likely to have been similarly diverse in terms of water and nutrient availability and substrate type, which may have led to numerous small and varied plant communities across the floodplain. Larger water flows in channels would likely contain a palynomorph representation of the wider hinterland of the drainage basin of the river including these floodplain plant communities and more distant communities, and sediments deposited with this assemblage of palynomorphs would reflect in their variety something of the variety of the full drainage basin. However where water is cut off from the river system as in water bodies like oxbow lakes or other impermanent stagnant floodplain ponds, a higher proportion of purely local palynomorphs would be preserved in associated sediments. These would be the spores and pollen of plants growing very close to the water body. Taking Locality 6, Wadi Autun, as an example, the lower sample is from a black carbonaceous, almost coaly siltstone that is overlain by trough cross-bedded sandstone with an erosive base (Figure 8). This unit may have been deposited in a stagnant environment isolated from

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water flow that encouraged the plant that produced the pollen Pretricolpipollenites bharadwaji, possibly a cycad. Thus its pollen is well represented in the sediment. The upper sample from a carbonaceous siltstone overlying a mudstone- and siltstone-filled abandoned channel, may represent a similarly restricted local environment perhaps surrounded by a stand of plants producing ornamented monolete spores, probably tree ferns.

Numerically the most important taxa reported from the assemblages are indeterminate bisaccate pollen, Falcisporites stabilis and Alisporites nuthallensis. The first category probably consists mainly of poorly preserved specimens of the latter two taxa. Falcisporites stabilis, the most common identifiable palynomorph in the assemblages, is considered by Kerp et al. (2006) to have been produced by the corystosperm Dicroidium, the most common plant fossil from the Wadi Himara macroflora (Kerp et al., 2006). The Wadi Himara macroflora as a whole was considered by Kerp et al. (2006) to be extrabasinal, but Abu Hamad (2004) considered that Dicroidium of Wadi Himara which are preserved often as large delicate frond fragments, were probably not transported far, and therefore grew in around the rivers and ponds of the floodplain.

Alisporites, still less A. nuthallensis, is more difficult to relate to a single plant genus or even family, but like Dicroidium it was probably gymnospermous and may have occupied a similar palaeoenvironment. Mustafa (2003) recorded Lobatannularia, Gigantonoclea and Pecopteris from the upper Umm Irna Formation. Balme (1995) does not list the plant-palynomorph relationships of Lobatannularia and Gigantonoclea, but it is likely that at least a few species of Pecopteris produced monolete spores. Taken as a whole the varied and rich Umm Irna Formation palynomorph assemblages could have been produced by a range of plants including Glossopteris (which produced taeniate bisaccate pollen, see Playford, 1990), Cyclodendron (which produced Indotriradites, see Beeston, 1990), and Walchia (Potonieisporites, see Balme, 1995). A tentative reconstruction of the palaeoevironments and plant communities is shown in Figure 10.

On plant fossil evidence Kerp et al. (2006) considered that the lower part of the Umm Irna Formation has a Gondwanan affinity, while the upper part is of Cathaysian affinity. The present study has also shown this variation of affinity in palynological assemblages. For instance, the upper palynological sample of Locality 6, Wadi Autun, which represents the upper part of the Umm Irna Formation is dominated by monolete spores and therefore might be considered to have a Cathaysian affinity (e.g. Gao, 1985), while the lower Wadi Autun sample containing common Pretricolpipollenites bharadwaji is of unknown affinity. Other assemblages of the upper part of the Umm Irna Formation from Dyke Plateau are Gondwanan in aspect (following Kerp et al., 2006). This serves to indicate the dangers of theorizing widely from core or single outcrop studies.

The phenomenon of sedimentary setting influencing palynological assemblages has also been identified in Oman. Stephenson (2011) identified similarly distinct assemblages in sequences of Subunit B of the Upper Member of the Gharif Formation of similar age and depositional environment to the Umm Irna Formation. The palaeoenvironment of Subunit B in Oman consisted of a system of coalescent and sandy estuarine point-bars (Berthelin et al., 2006), on which a rich flora of Gondwanan glossopterids and lycopsids, Euramerican conifers, and Cathaysian gigantopterids, lycopsids and Noeggerathiales grew. The argillaceous parts of Subunit B were considered by Broutin et al. (1995) to represent ‘swamp claystone’ and crevasse splay deposits suggesting impersistent and stagnant water bodies. These contain unusual assemblages of spores as well as freshwater non-haptotypic palynomorphs (probably the zygospores of zygnemataceaen alga) quite unlike more typical Upper Gharif Member assemblages (see Stephenson, 2011). This may be because the ‘swamp claystones’ were formed in impersistent and stagnant water bodies more likely to represent a local flora than a regional flora.

CORRELATION

The assemblages contain the following distinctive taxa that have been recorded from well-dated sections and allow possibilities for correlation within the region and with the standard Permian stages: Distriatites insolitus, Lueckisporites virkkiae, Playfordiaspora cancellosa, Protohaploxypinus uttingii

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and Thymospora opaqua. Of these the most important is the distinctive bitaeniate bisaccate pollen Lueckisporites virkkiae, which occurs first in the lower part of the Kazanian (Wordian) in its type area in the Russian Platform (Utting et al., 1997).

In Europe, where independent palaeontological evidence is available, its last occurrence is close to the equivalent of the Permian/Triassic Boundary (Visscher and Brugman, 1986). Independent confirmation of a Wordian first occurrence for Lueckisporites virkkiae in the Gondwana palaeophytogeographic province comes from radioisotopic dating of the Argentinian Striatites Biozone (Archangelsky and Vergel, 1996), at the base of which that taxon makes its first appearance. Melchor (2000) reported a radioisotopic date of 266.3 ± 0.8 Ma (Wordian) for the base of the Striatites Biozone.

The presence of Distriatites insolitus, Playfordiaspora cancellosa and Thymospora opaqua allows correlation with the Arabian Oman and Saudi Arabia Palynological Zones (OSPZ) biozones because all three first appear at the base of OSPZ5 (Stephenson et al., 2003; Stephenson, 2006, 2008), however Florinites? balmei, the zone indicator for the succeeding OSPZ6 biozone does not occur in the samples, suggesting either that the Umm Irna Formation assemblages correlate with OSPZ5 which is Roadian–Wordian in age, or that Florinites? balmei is absent for some reason. However, the sometimes abundant presence of the multitaeniate pollen Protohaploxypinus uttingii suggests that the assemblages probably extend in age above the Roadian–Wordian. Protohaploxypinus uttingii occurs first in OSPZ6 (Stephenson et al., 2003; Stephenson, 2006). It is entirely absent from the Gharif Formation in Oman, occurring only in the overlying Khuff Formation (unpublished Petroleum Development Oman reports). In Central Saudi Arabia, the taxon is sometimes common, and is very distinctive, being the smallest multi-taeniate pollen in the Arabian Permian sequence with a characteristically shrunken intexinal body (see Plate 12). It occurs in the Central Saudi Arabian Dilam-1, Nuayyim-2 and Haradh-51 wells in the basal Khuff clastics (Stephenson and Filatoff, 2000). Extensive subsurface studies in Saudi Arabia have established the upper limit of the range of Protohaploxypinus uttingii as immediately above the Middle Khuff Anhydrite unit (Khuff D Anhydrite) (personal communication, Nigel Hooker, 2012), which suggests an age range for Protohaploxypinus uttingii of Wordian–Capitanian to early Wuchiapingian (Mid- to early Late Permian). This suggests a similar total age range for the Umm Irna Formation.

The assemblages of the Dilam-1, Nuayyim-2 and Haradh-51 wells are also similar in quantitative and qualitative terms to those of the Umm Irna Formation. Non-taeniate bisaccate pollen is the most common form in all the sections, and Alisporites nuthallensis, Lueckisporites virkkiae, Distriatites insolitus, Playfordiaspora cancellosa, Thymospora opaqua and Reduviasporonites chalastus occur in Dilam-1 and Nuayyim-2 (Stephenson and Filatoff, 2000). Haradh-51 contains all but Playfordiaspora cancellosa and Thymospora opaqua. Quantitative data for key taxa in Dilam-1 are shown in Figure 11.

The geographically closest sequences to those of the Umm Irna Formation studied in detail for palynology are from boreholes in the eastern and southern West Bank, west of the Dead Sea. Eshet and Cousminer (1986) and Eshet (1990) studied assemblages from eleven boreholes including the Makhtesh Qatan-1 Well, from which the only Permian core material came (Eshet and Cousminer, 1986). The Makhtesh Qatan-1 Well is situated approximately 100 km southwest of the southern limit of the Dead Sea, but the restored position before movement of the Dead Sea Fault would put the well rather close to the Umm Irna Formation outcrop on the east shore of the Dead Sea. Eshet and Cousminer (1986) processed samples from cores 10 to 19 within what they regarded as the Permian sequence. These cores span the Sa’ad and Arqov formations. According to Eshet (1990), the Sa’ad Formation in Makhtesh Qatan-1 Well consists of 80 m of sandstones, coaly shales with plant remains, and rare limestone and dolostone. The Arqov Formation consists of 194 m of sandstone, shale and carbonate units interpreted to have been deposited in a near-shore marine environment.

Within the lower part of the section in Makhtesh Qatan-1 Well, Eshet and Cousminer (1986) give palynological details only of cores 14 and 15 just above the top of the Sa’ad Formation. Cores 16 to 19 from within the Sa’ad Formation appear to have been barren or contained no notable palynomorphs (see Eshet and Cousminer, 1986; their text-figure 3). Within the upper part of the Arqov Formation two levels appear to have yielded palynomorphs (at depths of 2,099 m and 2,084 m). Cores 14 and 15 yielded amongst others Potonieisporites novicus, Falcisporites (Alisporites) nuthallensis, Hamiapollenites

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(Distriatites) insolitus, Vittatina spp., Lueckisporites virkkiae and Falcisporites stabilis, suggesting that this level in the lowest Arqov Formation is palynologically similar to the Umm Irna Formation. Wireline log and lithological interpretations by Eshet and Cousminer (1986; their text-figure 2) further suggest close similarity between the transition between the Sa’ad and Arqov formations in the West Bank and the transition between the Umm Irna and Ma’in formations in Jordan.

Correlations with the Salt Range sequence in Pakistan are hampered by the lack of coverage through the sequence due to the great thickness of limestone (which is inimical to the preservation of palynomorphs). Balme (1970) mainly documented samples from the Changhsingian (latest Permian) Chhidru Formation, and the underlying Wargal and Amb formations (Wuchiapingian and Wordian respectively, see Wardlaw and Pogue, 1995), were represented by only five samples. Similarly Hermann et al. (2012) documented samples only from the Chhidru Formation. Jan et al. (2009) documented ?Wordian assemblages from the Sardhai Formation underlying the Amb Formation in the Salt and Khisor ranges and correlated the formation with the Oman basal Khuff clastics and with part of the Saudi Arabian basal Khuff clastics, suggesting also that the basal Khuff clastics was diachronous, younging to the north through the Arabian Plate (see Al-Jallal, 1995; Jan et al., 2009; Figure 5; Le Nindre and Lasseur, 2012).

The assemblages of the Sardhai Formation are similar to those of the Umm Irna Formation in containing common non-taeniate bisaccate pollen and taxa such as Alisporites indarraensis, A. nuthallensis, Camptotriletes warchianus, Distriatites spp., Lueckisporites virkkiae, Protohaploxypinus uttingii and Thymospora opaqua; however Florinites? balmei, which is common in the Sardhai Formation does not occur in the Umm Irna Formation. The converse is true of Falcisporites stabilis. The variation in quantitative character seen in parts of the Umm Irna Formation seems also to be present in the Sardhai Formation with taxa such as Florinites? balmei and Protohaploxypinus uttingii being particularly variable in number.

DILAM-1 Absolute abundance shown a i s a s

Samples Depth (feet) Reduviasporonites chalastus Lueckisporites virkkiae Thymospora opaqu Peroaletes khuffensis Playfordiaspora cancellos Cedripites priscu Alisporites indarraensi Alisporites nuthallensis Distriatites insolitus Protohaploxypinus uttingi

39 7,811.20 2 14 11

7,821.30 35 11 14 449 1 7,824.30 11 13 125 7,827.90 1 36 4 2 17 7,833.80 17 127 7,837.20 18 17 5 7,841.40 24 12 7,843.80 13 5 112 1 7,846.40 12 12 1 11 3 7,852.20 30 6 2 1

7,866.80 8132

36 7,889.00 2 12 1

Figure 11: Quantitative character of selected taxa from Dilam-1, Saudi Arabia, from Stephenson and Filatoff (2000).

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Palynological determinations (Keegan, unpublished reports quoted in Andrews, 1992) reported a late Early to Mid-Permian age (Kungurian to Kazanian) for the Buwayda Formation proved in Well ER-1-A in north Jordan. It was not possible to obtain these unpublished reports; however another unpublished NRA report (Gupta, 1986) indicates the presence of Lueckisporites virkkiae, taxa similar to Thymospora opaqua, Alisporites nuthallensis and Camptotriletes warchianus; as well as Laevigatosporites spp. and Taeniaesporites spp. in the same well. This suggests that the Permian rocks of ER-1-A are of similar age to the Umm Irna Formation. The paralic, siliciclastic Buwayda Formation, overlain unconformably by Lower Triassic rocks is therefore considered to be broadly coeval with the Umm Irna Formation at outcrop. If this correlation is correct, the Early Permian marine and siliciclastic formations underlying the Buwayda Formation in north Jordan are absent along the Dead Sea outcrops. Tentative relationships between formations within Jordan and the wider Tethyan area are shown in Figure 12.

Palynological Central Saudi Chronostratigraphy West Bank Jordan Oman Pakistan biozonation Arabia

Olenekian Arqov Ma’in

Induan Earl y Formation Formation Triassi c (in part) (in part) Changhsingian Chidru Formation

Lat e ? Wuchiapingian Permian Khuff Khuff Formation Formation (in part) (in part) Wargal Formation Capitanian Sa’ad Umm Irna ?? Amb OSPZ6 Formation Formation Formation Basal Khuff clastics sensu Stephenson Khuff transition Sardhei Formation and Filatoff, 2000 section Wordian ? ? ? Middle Permian Upper Gharif OSPZ5 Member ? Roadian

Warchha ? Formation ? Kungurian ? Middle (part) OSPZ4 Gharif Unayzah A Member Artinskian Early Permian Member

Figure 12: Relationships of Umm Irna Formation with Pakistan (Salt Range), Oman, Central Saudi Arabia and the West Bank, partly based on Stephenson (2006) and Jan et al. (2009). The red dashed rectangle indicates the total possible age range of the Umm Irna Formation. Blue colour indicates predominantly carbonate lithology.

CONCLUSIONS

The Permian Umm Irna Formation of the eastern Dead Sea margin represents a northerly extension of the hydrocarbon-bearing Unayzah and Khuff formation sequences of the Arabian Plate. Until now this formation has not been studied in the context of the better known sequences of Central and southern Arabia, which are constrained by a comprehensive and rigorously-tested biostratigraphical framework. Sedimentological field studies and subsequent palynological analysis of the Umm Irna Formation has defined a series of lithofacies associations and confirmed the suggestion of previous

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authors that the formation represents deposition in a fluvial regime stacked small-scale braided channels (lower part) and by low-sinuosity channels with deposition on point bars. We interpret the upward gradational transition from low- to high-sinuosity channels and the higher proportion of laterally accreted channels with drifted plant beds and clay-filled abandoned channels, as a response to increasing accommodation space on the low-gradient alluvial plain, during Late Permian sea-level rise.

The dimensions and internal architecture of Umm Irna Formation channel-sands and their overall depositional environments are similar to those described for the Gharif Formation alluvial plain ‘Type Environment P2’ in the subsurface in Oman and the Unayzah Formation at outcrop in Central Saudi Arabia. Umm Irna Formation floodplain interfluves were characterised by low-energy sheet-flood and crevasse splay deposits with shallow lakes and ponds. Where there was no standing water, the floodplain sediments underwent primary reddening (‘brunification’) in an oxidising humid to semi- arid climate characterised by seasonal ground-water fluctuation, which resulted in the development of ferralitic palaeosols.

The presence of immature pebbly, coarse-grained channel sandstone clasts was previously explained by erosion of Neoproterozoic granitoid hinterlands (e.g. Dill et al., 2010). However palaeocurrent directions and new evidence from Central Saudi Arabia (Melvin and Sprague, 2006) suggests the possibility of secondary derivation from pre-existing, relatively unaltered Pennsylvanian–Early Permian glaciofluvial outwash sandstones located to the east-southeast.

The palynology of the Umm Irna Formation is remarkably varied, and this may reflect depositional processes and the varied palaeocommunity patterns on the floodplain. Samples from argillaceous beds associated with flowing water (laterally accreted point bars and channel sands) appear to contain a palynomorph representation of the wider hinterland of the drainage basin of the river including drifted, floodplain plants and more distant communities. However, where water is cut off from the river system as in standing water bodies such as oxbow lakes or other impermanent stagnant floodplain ponds, where peaty mires developed, a higher proportion of purely local palynomorphs appear to be preserved in associated sediments.

The abundant and well-preserved palynomorphs allow improved correlation and dating of the Umm Irna Formation. The presence of Protohaploxypinus uttingii suggests a total age range of Wordian– Capitanian to early Wuchiapingian (Mid- to early Late Permian) for the Umm Irna Formation. The quantitative character of the Umm Irna Formation assemblages is very close to those of the basal Khuff clastics in the Central Saudi Arabian wells Dilam-1, Nuayyim-2 and Haradh-51. The lithological character and palynology of the transition between the Sa’ad and Arqov formations in the West Bank, west of the Dead Sea are similar to those of the transition between the Umm Irna Formation and overlying Ma’in Formation in Jordan.

ACKNOWLEDGEMENTS

We would like to thank Issa Makhlouf, Basem Kahlil Moh’d and Ahmed Smaadi for their help and companionship in the field. We are grateful to Bassam Tarawneh, Natural Resources Authority (NRA) for making available unpublished reports of the NRA. Palynological samples were prepared by Jane Flint of BGS. Thanks go to Robert Knox and Colin Waters (BGS) for their comments on an early version of the text, and to three anonymous reviewers. The authors thank GeoArabia’s Production comanager Nestor “Nino” Buhay IV for designing the manuscript for press. Mike Stephenson and John Powell publish with the permission of the Executive Director of the British Geological Survey (NERC).

REFERENCES

Abu Hamad, A. 2004. Palaeobotany and palynostratigraphy of the Permo-Triassic in Jordan. PhD Thesis, University Hamburg, 330 p. http://www.sub.uni- hamburg.de/opus/volltexte/2005/2309/pdf/ dissertation.pdf.

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Eshet, Y. and H.L. Cousminer 1986. Palynozonation and correlation of the Permo-Triassic succession in the Negev, Israel. Micropaleontology, v. 32, p. 193-214. Gao, L. 1985. Carboniferous and Early Permian spore assemblages of North China region and the boundary of the Carboniferous and Permian. Dixième Congrès International de Stratigraphie et de Géologie Carbonifére, Madrid, 1983. Compte Rendu, v. 2, p. 409-424. Glover, B.W. and J.H. Powell 1996. Interaction of climate and tectonics upon alluvial architecture: Late Carboniferous-Early Permian sequences at the southern margin of the Pennine Basin, UK. Palaeogeography, Palaeoclimatology, Palaeoecology, v. 121, p. 13-34. Glover, B.W., J.H Powell and C.N. Waters 1993. Etruria Formation (Westphalian C) palaeoenvironments and volcanicity on the southern margins of the Pennine Basin, South Staffordshire, England. Journal of the Geological Society, London, v. 150, p. 737-750. Gupta, S. 1986. Additional palynological analyses of the ER-1-A well (interval 1345-1754 m) and its correlation with the Ramtha S-90. Report no. 38. Unpublished NRA report. Hermann, E., P.A. Hochuli, H. Bucher and G. Roohi 2012. Uppermost Permian to Middle Triassic palynology of the Salt Range and Surghar Range, Pakistan. Review of Palaeobotany and Palynology, v. 169, p. 61-95. Ibrahim, K. and W.J. McCourt 1995. Neoproterozoic granitic magamatism and tectonic evolution of the northern Arabian Shield: Evidence from southwest Jordan. Journal of African Earth Sciences, v. 20, p. 103-118. Jan, I.U., M.H. Stephenson, and F.R Khan 2009. Palynostratigraphic correlation of the Sardhai Formation (Permian) of Pakistan. Review of Palaeobotany and Palynology, v. 158, p. 72-82. Kerp, H., A. Abu Hamad, B. Vörding and K. Bandel 2006. Typical Triassic Gondwana floral elements in the Upper Permian of the paleotropics. Geology, v. 34, p. 265-268. Lang, B. and Y. Mimran 1985. An early Cretaceous volcanic sequence in central Israel and its significance to the absolute date of the base of the Cretaceous. Journal of Geology, v. 93, p. 179-184. Le Nindre, Y.-M. and E. Lasseur 2012. Uncertainties on basal Khuff clastics in outcrop in Saudi Arabia. In the Permo-Triassic Sequence of the Arabian Plate, Abstracts of the EAGE’s Third Arabian Plate Geology Workshop, Kuwait. Abstract, GeoArabia, v. 17, no. 1, p. 220-223. Makhlouf, I.M. 1987. The stratigraphy and sedimentation of Upper Cambrian, Permo-Triassic and Lower Triassic rocks along the northeastern margin of the Dead Sea basin, Jordan. Unpublished PhD thesis, University of Newcastle upon Tyne, U.K. Makhlouf, I.M., B.R. Turner and A.M. Abed 1990. Depositional facies and environments in the lower Triassic Ma’in Formation, Dead Sea area, Jordan. Dirasat, Series B (Pure and Applied Sciences), v. 17, p. 7-26. Makhlouf, I.M., B.R. Turner and A.M. Abed 1991. Depositional facies and environments in the Permian Umm Irna Formation, Dead Sea area, Jordan. Sedimentary Geology, v. 73, p. 117-139. McCourt, W.J. and K. Ibrahim 1990. The geology, geochemistry and tectonic setting of the granitic and associated rocks in the Aqaba and Araba complexes of southwest Jordan. Geological Mapping Division Bulletin 10, Geology Directorate, Natural Resources Authority, Amman. Melchor, R.N. 2000. Stratigraphic and biostratigraphic consequences of a new 40Ar/39Ar date for the base of the Cochicó Group (Permian), eastern Permian basin, San Raphael, Argentina. Ameghiniana, v. 37, p. 271-282. Melvin, J. and R.A. Sprague 2006. Advances in Arabian stratigraphy: Origin and stratigraphic architecture of glaciogenic sediments in Permian-Carboniferous lower Unayzah sandstones, eastern central Saudi Arabia. GeoArabia, v. 11, no. 4, p. 105-152. Miall, A.D. 1977. A review of the braided-river depositional environment. EarthScience Reviews, v. 13, p. 1-62. Mohr, E.J.C., F.A. van Baren, and J. van Schuylenborgh 1972. Tropical Soils: A comprehensive study of their genesis. Mouton-Ichtiar Baru-Van Hoeve, The Hague, 481 p. Muller, J. 1959. Palynology of Recent Orinoco delta and shelf sediments: Reports of the Orinoco shelf expedition. Micropalaeontology, v. 5, p. 1-32. Mustafa, H. 2003. A Late Permian Cathaysia flora from the Dead Sea area, Jordan, Neues Jahrbuch für Geologie und Paläontologie Monatshefte, p. 35-39. Osterloff, P., A. Al-Harthy, R. Penney, P. Spaak, G. Williams, F. Al-Zadjali, R. Knox, M. Stephenson, G. Oliver and M.I. Al-Husseini 2004. Depositional sequence of the Gharif and Khuff formations, subsurface Interior Oman. In M.I. Al-Husseini (Ed.), Carboniferous, Permian and Early Triassic Arabian Stratigraphy. GeoArabia Special Publication 3, Gulf PetroLink, Bahrain, p. 83-147.

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APPENDIX 1 LIST OF PALYNOMORPH TAXA RECORDED

?Brazilea sp. Lundbladispora spp. ?Densipollenites sp. Indeterminate monosaccate pollen ?Vittatina spp. Nuskoisporites sp. R (of Stephenson unpublished ?Laevigatosporites spp. PhD thesis) ?Limatulasporites spp. Nuskoisporites spp. ?Kingiacolpites subcircularis Tiwari & Moiz 1971 Peroaletes khuffensis Stephenson and Filatoff 2000 ?Punctatisporites spp. Pilasporites calculus Balme & Hennelly 1956 Alisporites cf. nuthallensis Clarke 1965 Platysaccus queenslandi de Jersey 1962 Alisporites indarraensis Segroves 1969 Platysaccus spp. Alisporites nuthallensis Clarke 1965 Playfordiaspora cf. cancellosa (Playford & Dettmann) Alisporites spp. Maheshwari & Banerji 1975 Indeterminate bisaccate pollen Playfordiaspora cancellosa (Playford & Dettmann) Botryococcus spp. Maheshwari & Banerji 1975 Camptotriletes spp. Plicatipollenites malabarensis (Potonié & Sah) Foster Camptotriletes warchianus Balme 1970 1975 Cannanoropollis spp. Plicatipollenites spp. Cedripites priscus Balme 1970 Potonieisporites spp. Cedripites spp. Potonieisporites novicus Bharadwaj 1954 Columinisporites spp. Protohaploxypinus uttingii Stephenson and Filatoff Convolutispora spp. 2000 Cristatisporites spp. Protohaploxypinus amplus (Balme & Hennelly) Hart Cyclogranisporites spp. 1964 Densipollenites indicus Bharadwaj 1962 Protohaploxypinus microcorpus (Schaarschmidt) Dibolisporites spp. Clarke 1965 ?Dictyotriletes aules Rigby 1977 Protohaploxypinus limpidus (Balme & Hennelly) Dictyotriletes spp. Balme & Playford, 1967 Distriatites insolitus Bharadwaj & Salujah 1964 Protohaploxypinus spp. Distriatites spp. Punctatisporites gretensis forma minor Hart 1965 Divarisaccus spp. Punctatisporites spp. Falcisporites stabilis Balme 1970 Reduviasporonites chalastus (Foster) Elsik, 1999 Florinites spp. Reduviasporonites sp. B (of internal Petroleum Granulatisporites spp. Development Oman reports) ?Guttulapollenites hannonicus Goubin 1965 Retusotriletes spp. Indotriradites spp. Spinose acritarch species Kendosporites spp. Taeniaesporites pellucidus (Goubin) Balme 1970 Laevigatosporites cf. callosus Balme 1970 Taeniaesporites spp. Laevigatosporites spp. Indeterminate taeniate bisaccate pollen Leiosphaeridia spp. Thymospora cf. opaqua Singh 1964 Leiotriletes spp. Thymospora opaqua Singh 1964 Limitisporites sp. Pretricolpipollenites bharadwaji Balme 1970 Lueckisporites virkkiae Potonié & Klaus emend. Triquitrites spp. Clarke 1965 Vittatina spp. Lueckisporites cf. virkkiae Potonié & Klaus emend. Clarke 1965

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ABOUT THE AUTHORS

Mike Stephenson is Head of Science (Energy) at the British Geological Survey (BGS), Nottingham, United Kingdom. His education has included a BSc, MSc and PhD from Imperial College and University of Sheffield (UK), and various postgraduate teaching qualifications. Mike is an expert on the stratigraphy of the Middle East, and he has published around 30 papers on this region as well as working extensively as a consultant for oil companies in the area. He is a Fellow of the Geological Society, sits on the Petroleum Group Committee of the Geological Society and is a member of the Petroleum Exploration Society of Great Britain (PESGB). He was Secretary-General of the Commission Internationale de Microflore du Paléozoique (CIMP) between 2002 and 2008, and is presently Editor- in-Chief of the Elsevier science journal Review of Palaeobotany and Palynology. Mike Stephenson is an Honorary Professor at the universities of Nottingham and Leicester. [email protected]

John H. Powell was formerly Chief Geologist, England, with the British Geological Survey (BGS). He gained his BSc and PhD at the University of Newcastle upon Tyne, UK. John has over 30 years professional experience in sedimentology, applied geology and geological mapping in the UK and internationally. He has worked with the Natural Resources Authority, Jordan, on mapping, sedimentology and basin analysis of the Phanerozoic succession, especially the Lower Palaeozoic and Cretaceous – Eocene sequences. John was BGS Regional Geologist for the Middle East and Africa from 1998 to 2000, and has worked in Syria, Morocco, Mauritania and Mozambique. He serves on the Geological Society of London Accreditation Committee and GSL Stratigraphy Commission. He was recently awarded the John Phillips Medal by the Yorkshire Geological Society for stratigraphic research. [email protected]

Manuscript submitted October 2, 2012

Revised December 6, 2012

Accepted December 12, 2012

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/18/3/17/4567630/stephenson.pdf by guest on 26 September 2021 a Red ﬁne–grained sandstone with ripple Palynology Palynology assemblage 62260 marks, desiccation cracks and surface Sequence boundary SB Dolerite dyke burrow traces assemblage 62259 Palynology assemblage 62261

Trough-cross-bedded sandstone, pebbly at base

Sandstone channel axis: palaeoﬂow WSW (red arrow)

2.0 m

1st-order lateral accretion Level-bedded ﬂoodplain overbank surfaces, oblique to channel sandstone with bruniﬁed palaeosols

Plate 6: Dyke Plateau; upper Umm Irna Formation (Locality 7; see Figure 9 for orientation from channel sandstone, left, to side wadi, right); (a) Composite wide-angle photograph illustrating lateral accretion units (first- and second-order) and organic-rich mudstone beds (sampled); the main channel is located to the left (north). Note the lateral passage (right) to red-bed floodplain sandstones and mudstones with palaeosols. SB marks the sequence boundary above which red, fine-grained sandstones with wave ripples and faint burrows are common. Red box is the area of Plate 7.

b Dolerite dyke

Sequence boundary SB Sandstone channel axis: palaeoﬂow WSW

1st-order lateral accretion surfaces, oblique to channel 2.0 m Level-bedded ﬂoodplain overbank sandstone and mudstone with bruniﬁed palaeosols

(b) Composite wide-angle photograph to the right (south) of 6a; note the position of the dolerite dyke. The main cliff consists of stacked, horizontal-bedded crevasse splay and ﬂoodplain sandstones and siltstones with palaeosol horizons.

Sequence boundary SB

Thin crevasse-splay sandstones

Level-bedded ﬂoodplain overbank sandstone with bruniﬁed palaeosols Sandstone channel overlying plant-rich mudstone and 2.0 m palaeosol (See plate 11 for details)

(c) Composite wide-angle photograph to the south (east) of 6b, showing stacked, level-bedded bruniﬁed palaeosols, and thin crevasse-splay sandstones, passing right (southeast) to an abandoned mudstone-ﬁlled channel (pedogenetically altered) overlain by plant-rich mudstone and sandstone channel (see Plate 11 for details).

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