Lower Cretaceous Sulaiy Formation in Outcrops of Central Saudi Arabia

GeoArabia, 2015, v. 20, no. 4, p. 67-122 Gulf PetroLink, Bahrain

Facies analysis and sequence stratigraphy of the uppermost Jurassic– Lower Cretaceous Sulaiy Formation in outcrops of central Saudi Arabia

Philipp Wolpert, Martin Bartenbach, Peter Suess, Randolf Rausch, Thomas Aigner and Yves-Michel Le Nindre

ABSTRACT

Uppermost Jurassic–Lower Cretaceous carbonates of the Sulaiy Formation are well exposed at the type locality Dahal Hit, and along the entire natural escarpment near Ar Riyad, the capital of the Kingdom of Saudi Arabia. This study provides a facies and sequence-stratigraphic analysis based on detailed sedimentological and gamma-ray logging of 12 outcrop sections. The sections represent the Sulaiy Formation along a 60 km-long outcrop belt, including the Hith-Sulaiy transition in a large solution cavity named Dahal Hit, situated south of Ar Riyad. The latter section is studied in detail because it is the only locality in Saudi Arabia where the Hith Anhyrite (Hith Formation in this study) to the Sulaiy Formation transition crops out.

Ten lithofacies types were identiﬁed for the Sulaiy Formation including potential reservoirs such as oolitic cross-bedded grainstones, biostromal boundstones, and bioclast-rich, graded pack-to-grainstones. Lithofacies types are grouped into ﬁve facies associations: (1) offshoal, (2) transition zone, (3) foreshoal, (4) shoal margin, and (5) shoal, distributed along a carbonate ramp. Their vertical stacking pattern revealed a systematic hierarchy of cyclicity consisting of small-scale cycles, medium-scale cycle sets and two large-scale sequences for the Sulaiy Formation. Four cycle motifs, with an average thickness of 2–4 m, are present: (1) offshoal to transition zone cycle motif, (2) offshoal to foreshoal cycle motif, (3) transition zone to shoal margin cycle motif, and (4) foreshoal to shoal margin cycle motif.

A total of 15 cycle sets, ranging between 8 and 12 m in thickness each, were interpreted. They were correlated, where possible, across the study area. Three types of medium-scale cycle sets are observed: (1) offshoal to shoal cycle set motif, (2) offshoal to foreshoal cycle set motif, and (3) shoal margin to offshoal cycle set motif. The Lower Sulaiy Sequence consists of twelve cycle sets and is interpreted to contain two Arabian Plate maximum ﬂooding surfaces (MFS): (1) Upper Tithonian MFS J110 (147 Ma) in its lowermost part, which is interpreted to be the time-equivalent of the Manifa reservoir in subsurface Arabia. (2) Lower Berriasian MFS K10 (144 Ma) in the seventh-up cycle set. The Upper Sulaiy Sequence is only represented in the Wadi Nisah Section and is believed to be incomplete because the Sulaiy/Yamama Formation boundary was not included in our study. It is presumed to contain Upper Berriasian MFS K20 (141 Ma).

INTRODUCTION

The Upper Tithonian–Berriasian Sulaiy Formation crops out in a broad crescent-shaped belt parallel to the Arabian Shield in central Saudi Arabia (Powers et al., 1966). It consists of a massive limestone, more than 100 m thick, that marks the return to an open-marine setting following the deposition of the Late Jurassic Hith Anhydrite (hereafter Hith Formation) evaporites across the interior of the Arabian Plate (Murris, 1980; Al-Husseini, 1997; Sharland et al., 2001). The Sulaiy Formation is an important formation for several reasons as explained below.

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Firstly, the Sulaiy Formation is water-bearing in the weathered subsurface zone or below the alluvium overburden. The weathered zone can apparently extend to 20–30 m below the top of the limestone. Due to the removal of anhydrite beds from the underlying Arab-Hith sequence by solution caused by meteoric water, the Sulaiy Formation is commonly fractured, brecciated, foliated and contains numerous cavities, vugs and openings. The Sulaiy limestone aquifer is mainly used in Ad Dilam. The limestone is more like a karst-type medium than a conventional porous medium because the water circulates in channels and cavities and not in the interstices of a granular medium. Although the normal water circulation relationship cannot strictly be applied in the usual way, this limestone can nevertheless be considered to approximately constitute a large-scale porous medium so that the concept of permeability can be applied if a sufficiently large aquifer volume is taken into consideration. In practice, the transmissibility and storage coefficient may be determined by pumping tests when the duration and flow are sufficient to affect a fairly large volume of the aquifer.

Secondly, together with its lateral equivalents in other countries, it is a major source rock in the eastern Arabian Plate (Ayres et al., 1982; Sharland et al., 2001). Thirdly, below the Sulaiy Formation, the upper part of the Hith Formation contains oil in the 20–30 m-thick Manifa reservoir in several ﬁelds in Saudi Arabia (Powers, 1968) and the United Arab Emirates (Grötsch et al., 2003). However, the depositional setting and sequence-stratigraphic relationship between the Manifa reservoir and the transition between the Hith evaporites and Sulaiy limestones remains unresolved at outcrop and in the subsurface (Grötsch et al., 2003; Warren, 2006; Hughes and Naji, 2009). Therefore understanding the Sulaiy Formation stratigraphy at outcrop offers important insights for characterizing the petroleum geology of the interval spanning the Jurassic/Cretaceous boundary in the Middle East.

In addition to the Manifa reservoir, Powers (1968) reported that the upper part of the Sulaiy Formation consists of an interval of porous calcarenite, about 60 m thick, at Haradh, Ma'aqala, El Haba, Hafar al-Batin and extends to the east and northeast at least as far as Manifa and Abu Sa'fah ﬁelds. In the discovery Manifa-1 Well, this interval is oil-saturated and corresponds to the Lower Ratawi reservoir.

This paper presents the ﬁrst high-resolution stratigraphic study of the formation in a region near Ar Riyad, the capital of the Kingdom of Saudi Arabia. The study area is situated along the natural Cretaceous escarpment, which is interrupted by the Wadi Nisah in its center (Figures 1 and 2). The geological map of the Ar Riyad Quadrangle (Figure 2; Vaslet et al., 1991) shows the location of the 12 litho-sedimentologic sections that were logged for the study.

The paper starts by presenting the stratigraphic framework of the Sulaiy and its bounding formations, including the likely positions of the Arabian Plate maximum ﬂooding surfaces (MFS, Sharland et al., 2001) as revised by Le Nindre et al. (2008, this paper; Figure 3). In particular this opening section discusses the transition between Sulaiy and underlying Hith Formation at Dahal Hit, the only locality where the two formations are exposed in one section (Figures 4 and 5).

Next the paper documents the 12 sections that were logged and their properties in Figures 4 to 14; these include thickness, lithology, texture (Dunham, 1962; Embry and Klovan, 1971), grain size, components, sedimentary structures, degree of bioturbation and sequences. The logged sections were digitized with the software WellCAD. The location of each section and sample points (latitude, longitude and UTM coordinates) were recorded with a hand-held GPS. Natural gamma ray was recorded at 20 cm intervals with a hand-held spectral Gamma Ray with a bismuth germanium detector. Over 300 rock samples were taken for further microfacies analysis.

Figures 15 to 28 characterize the lithofacies types (LFT) of the Sulaiy and Hith formations. They are grouped together into lithofacies associations (LFA) and placed into depositional environments. The ﬁnal parts of the paper identify characteristic cycles, cycle sets and sequences, and correlate the resulting sequence-stratigraphic framework between the studied sections.

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34°E 38° 42° 46° 50° 54° 58° 38°N TURKEY Caspian 38° 46°50'E47° 47°10' Sea Ar Riyad CYPRUS SYRIA 34° LEBANON IRAN 34° HL Med IRAQ N EH Sea 0 300 JORDAN 24°30'N 24°30' 30° km 30° Gulf KUWAIT of Dahal Hit (DH) Suez BAHRAIN 26° 26° SAUDI ARABIA QATAR KW EGYPT UAE Arabian Study Area 22° Shield OMAN

SUDAN Red Sea 18° 18° KP Arabian Sea ERITREA YEMEN 14° 14° SOCOTRA AH ETHIOPIA Gulf of Aden 34° 38° 42° 46° 50° 54° 58°

24°20' 47°20' 47°30'

Wadi Nisah (NG)

24°10' 24°10'

Al-Kharj

24° Ad Dilam 24°

Al-Kharj Industrial City

N 0 20

23°50' SI km 23°50' FI To Al Hawtah 46°50'47° 47°10' 47°20' 47°30'

Figure 1: Satellite image of central Saudi Arabia with Ar Riyad in the northwest, Al-Kharj in the east, and Ad Dilam and Al-Kharj industrial city further to the south. A natural escarpment east of the highway between Ar Riyad and Al-Kharj and further south to Ad Dilam, provides excellent outcrops of the Sulaiy Formation. Especially at Dahal Hit, approximately 8 km south of Ar Riyad, the type locality of the Sulaiy and Hith formations are present. The escarpment is interrupted by the Wadi Nisah in the center of the study area.

STRATIGRAPHIC FRAMEWORK

Authors and Nomenclature

The framework that is described in this section is based on a detailed review of earlier studies by the ﬁnal coauthor, Y.-M. Le Nindre, with additional contributions by G.W. Hughes and M.I. Al-Husseini (personal communications, 2014, 2015), as well as the ﬁeld observations of the other authors (Figure 3).

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The type sections of the Hith Anhydrite (“Hith Formation” in this paper) and the Sulaiy Formation are located at Dahal Hit (24°29’18’’N, 47°00’06’’E), southeast of Ar Riyad. According to Powers et al. (1966) and Powers (1968), the Hith Formation was ﬁrst described in an unpublished Aramco report by R.A. Bramkamp and T.C. Barger in 1938, published by Steineke et al. (1958), and amended in an unpublished Aramco report by R.W. Powers et al. in 1964. The Hith Formation is accessible in a dissolution cavity at the foot of the Jabal Hit (Figures 1 and 2). This is the only place where the lower contact of the Sulaiy Formation with the Hith Formation can be observed (see Hith-Sulaiy Transition, below, Figures 4 and 5).

The Sulaiy Formation is named after the Wadi as Silay, a gravel-filled channel at the foot of the Hit Escarpment. Powers et al. (1966) and Powers (1968) reported that the formation was first defined in an unpublished Aramco report by R.A. Bramkamp and T.C. Barger in 1938, and its upper and lower contacts were revised in unpublished Aramco reports by C.D. Redmond (1962) and R.W. Powers (1964), respectively.

46°50'E 46°55' 47°00' 47°05' 47°10'47°15' 47°20' 47°25' 47°30' 47°35' 24°40'N 24°40'

24°35' 24°35'

EH HL 24°30' 24°30' Dahal Hit (DH) KW

24°25' KP 24°25' AH

24°20' 24°20'

24°15' Wadi Nisah (NG) 24°15'

24°10' 24°10' N 0 20

km 24°05' 24°05' Studied outcrop section FI & SI Note: Sections FI and SI are located 25.8 km south of the city Na'ajan, following46°50' the road 46°55'to Ad Dilam 47°00' 47°05' 47°15' 47°20' 47°25' 47°30' 47°35'

Figure 2: Geological map of the Ar Riyad Quadrangle, Kingdom of Saudi Arabia (Vaslet et al., 1991; reproduced by courtesy of the Saudi Geological Survey) showing the location of the type locality Dahal Hit and additional studied outcrop sections. The Sulaiy Formation was subdivided into the informal sedimentologic units S1 and S2, separated by a reworked surface interpreted as a sequence boundary. Note: Le Nindre et al. (2008, 2010) proposed raising the Huraysan member and Sallah member (subsurface Shu'aiba Formation) to formation status, and renaming the Dughum member as the Biyadh Sandstone. See facing page for legend.

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Thickness

According to Powers et al. (1966) and Powers (1968), the type section of the Sulaiy Formation measured in the hill above Dahal Hit has a thickness of 170.2 m. Vaslet et al. (1991) measured a revised type section between Dahal Hit and Wadi al Haniyah with a total thickness of 115 m, as consistent with our study.

Age of Sulaiy Formation

The Sulaiy Formation contains macro and microfauna, which guide its age determination, but few species were found to have chronostratigraphic signiﬁcance. In Saudi Arabia, foraminifer associations (Hughes and Naji, 2009) and macrofauna, in particular gastropod Pterocera fauna, may indicate a Tithonian age in the lower part of the formation (Vaslet et al., 1991). Tithonian coccoliths, including the species Conusphaera mexicana minor, have been recovered from the lower Sulaiy Formation, and in the absence of Cretaceous species (Osman Varol, personal communication, in Hughes and Naji, 2009).

Thamama Group (see note in caption) Age Sequence Stage Formation Huraysa Formation (Ma) Stratigraphy Group White conglomeratic (quartz gravel) to coarse-grained sandstone; Period beige medium- to fine-grained cross-stratified sandstone; beige to mauve pedogenetic bioturbated (roots) claystone, ferruginized Hauterivian Biyadh MFS sandstone in upper part. Formation K40 (132 Ma) Sallah Formation 132.9 Ma Gray to green or red calcareous and gypsiferous claystone; yellow to ocher pelletoidal limestone; bioclastic sandy limestone; yellowish 134.0 Late Valanginian medium- to coarse-grained sandstone. Unconformity Biyadh Sandstone White to brown fine- to coarse-grained cross-bedded sandstone containing conglomeratic layers of quartz gravel, in places cemented by silica (quartzite); white to red pedogenetic silty Valanginian Buwaib claystone in the upper part. Formation Buwaib Formation MFS Yellowish to blueish-gray locally silty claystone; ocher bioclastic and 138.0 lithoclastic calcarenite with lumachelle layers (bivalves); brown to K30 (138) white fine-grained sandstone; brown algal sparry dolomite in the Yamama upper part.

CRETACEOUS Formation Yamama Formation 139.8 Ma Alternation of white, gray, or yellow bioturbated clayey limestone MFS and brown bioclastic and pelletoidal calcarenite, locally intraclastic and rich in bivalves; cherty limestone in the south of the quadrangle. K20 (141) Sulaiy Formation 142.0 Upper part (unit S2) comprising beige bioclastic bioturbated Berriasian limestone and clayey limestone, interspersed with thin layers of bioclastic calcarenite; ocher oolitic bioclastic and lithoclastic Sulaiy calcarenite at the base. Lower part (unit S1) comprising beige to MFS gray pelletoidal and bioclastic limestone. Formation K10 (144) a – Dislocated limestone beds collapsed into very coarse solution breccias (blocks several meters wide) of Arab Formation and Hith 145.0 Ma Anhydrite. Disconformity 146.0 MFS Shaqra Group J110 (147) Arab Formation and Hith Anhydrite Upper breccia complex (Ja + Jha) – solution breccia comprising carbonate facies of Arab-B and Arab-A members, mixed together Tithonian with collapsed blocks from overlying Sulaiy Formation after solution Hith of evaporitic (anhydrite) facies of Arab-C and Arab-B members and Formation Hith Anhydrite. 150.0 Hith Anhydrite (Jha) - massive blueish-gray translucent anhydrite at Dahal Hit. JURASSIC MFS J100 (152.5) 152.8 Ma Shaqra GroupArab Thamama Group S2 KJs Sulaiy Kimmeridgian Formation Formation

Figure 3: Stratigraphic column of the Arab S1 Ja + Jha upper breccia complex Disconformity Formation to Biyadh Sandstone interval by Y.-M. Le Nindre (2014, personal communi-

Jac Arab-C Mbr, carb. facies (Hith Anhydrite) cation, modified after Vaslet et al., 1991; and Jad + Jac lower breccia complex Arab Formation Sharland et al., 2001; Haq and Al-Qahtani, Jad Arab-D Mbr, carb. facies 2005). The age of the Sulaiy Formation is Figure 2 (continued): mid-Late Tithonian to Late Berriasian.

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A possible Berriasian age is indicated in the upper part of the formation, south of Al Kharj, where a rare nannoﬂora, including Watznaueria barnesae Perch Nielsen 1968 and Haqius circumradius Perch Nielsen 1968, has been discovered (Monique Bonnemaison, written communication in Vaslet et al., 1991). Hughes and Naji (2009) note that the Sulaiy Formation is considered the lateral equivalent of the Cretaceous Makhul Formation in Kuwait based on coccoliths (Al-Fares et al., 1998). It is correlated to the Rayda Formation in Oman based on uppermost Tithonian ammonites and Berriasian calpionellids (Granier, 2006, 2008). These arguments suggest that the Jurassic/Cretaceous boundary in Saudi Arabia occurs within the lower part of the Sulaiy Formation.

Upper Jurassic–Lower Cretaceous Stratigraphy

The stratigraphic chart extending from the Arab Formation to the Biyadh Sandstone interval was proposed by Y.-M. Le Nindre (2014, this paper, Figure 3, modiﬁed after Vaslet et al., 1991; Sharland et al., 2001; Haq and Al-Qahtani, 2005). Vaslet et al. (1991) subdivided the Sulaiy Formation into two informal sedimentologic units, S1 and S2, separated by a reworked surface, which they interpreted as a sequence boundary. In the present paper we do not attempt to tie these units to our sequence- stratigraphic framework.

In Figure 3, the age of the Biyadh Sandstone is shown as Hauterivian, above the “Late Valanginian Unconformity” (Le Nindre et al., 2008, 2013). This assignment revises the Berriasian–Hauterivian stratigraphy in Saudi Arabia as shown in several publications (Sharland et al., 2001, 2004; Haq and Al-Qahtani, 2005; Droste, 2013).

The column also shows the revised positions of the Arabian Plate maximum ﬂooding surfaces (MFS) following Le Nindre et al. (2008). The Sulaiy Formation is interpreted to contain Upper Tithonian MFS J110 (147 Ma), Lower Barriasian MFS K10 (144 Ma) and Upper Berriasian MFS K20 (141 Ma). The ﬁrst two MFSs are interpreted in the present paper. Lower Valanginian MFS K30 (139 Ma) and Hauterivian MFS K40 (132 Ma) are adopted from Le Nindre et al. (2008, 2013).

Hith-Sulaiy Transition Interval

The transition between the Hith and Sulaiy formations at Dahal Hit is shown in detail in Figure 5. In ascending order the transition interval above the lower laminated main anhydrite of the Hith Formation consists of Breccia 1, a thin anhydrite bed, Breccia 2, and a thicker, deformed anhydrite bed. These intervals are assigned to the Hith Formation and are followed by evenly-bedded limestone of the Sulaiy Formation (Powers et al., 1966; Powers, 1968).

Steineke et al. (1958) positioned the Hith/Sulaiy Formation boundary between the massive anhydrite below, and breccia limestone above, and interpreted the contact as an unconformity surface, only visible at this section. However, according to Powers et al. (1966) and Powers (1968), this contact is not a disconformity or unconformity in the subsurface. They consider the breccia intervals at Dahal Hit to be due to the dissolution of the intercalated anhydrites – a solution- collapse type breccia. Vaslet et al. (1991, p. 15) consider “the top of the Hith Anhydrite is truncated by the basal beds of the Sulaiy Formation”, and in the caption of their ﬁgure 8 interpret the contact as disconformable.

Hughes and Naji (2009) consider the Hith/Sulaiy Formation boundary to be a possible disconformity. They described the Sulaiy-Hith transition in the offshore Manifa Field, Saudi Arabia, situated approximately 500 km northeast of Ar Riyad. They subdivided the Hith Formation (144 m thick) into three informal members (Table 1):

(1) lower “anhydrite“ member (92 m thick); (2) middle “transitional“ anhydrite-carbonate member (21 m thick) consisting of interbedded anhydrite and carbonate units, each approximately 3–4.5 m thick, forming two depositional cycles (1B and 1C); (3) upper “carbonate“ member” (31 m thick). The upper carbonate consists of four depositional

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cycles (2A to 2D) and its upper part hosts the Manifa reservoir (Powers, 1968), or informal “Manifa member” (Wilson, 1985).

Hughes and Naji (2009) discussed several depositional models for the Sulaiy-Hith transition including the possibility that the Manifa member represents the basal, early transgressive component of the Sulaiy Formation.

Table 1 Hith-Sulaiy Transition

Dahal Hit Outcrop Manifa Field Sulaiy Formation Sulaiy Formation cycle 2D “carbonate member” cycle 2C Sulaiy Formation evenly-bedded Hith Formation limestone (144 m) or “Manifa member” (31 m) cycle 2B cycle 2A deformed anhydrite beds anhydrite 1C Breccia 2 “transitional member” carbonate 1C (21 m) Hith Formation anhydrite beds anhydrite 1B (90.3 m) Breccia 1 carbonate 1B laminated anhydrite (70–80 m) “anhydrite member” (92 m) anhydrite 1A (92 m) Arab Formation Arab A Member Arab Formation Arab A Member Arab A Member

The proposed correlation in Table 1 suggests that the subsurface Manifa member is time-correlative to the lowermost Sulaiy Formation at Dahal Hit. This correlation is further supported by the description of the Hith-Sulaiy transition at Abu Jifan Field, situated 60 km east of Ar Riyad and approximately 550 km southwest of Manifa Field. In an Abu Jifan borehole, Vaslet et al. (1991) reported that the Hith Formation is 132 m thick, and mainly composed of white to gray anhydrite, with intercalations of halite, calcarenetic limestone, and dolomitic layers (Table 2). The uppermost 20 m contain abundant oolitic and pelletoidal calcarenite layers, known as the Manifa reservoir. It is remarkable that the Hith Formation in the Manifa and Abu Jifan ﬁelds, below the Manifa member, have essentially the same thickness (112–113 m) and that it is comparable to the thickness in Dahal Hit (90.3 m).

Table 2 Hith Formation and Manifa Member Abu Jifan Field Manifa Field Dahal Hit Outcrop (Vaslet et al., 1991) (Hughes and Naji, 2009) 1. Sulaiy Formation 1. Manifa member (20 m) 1. Manifa member (31 m) 2. Breccia Zone between surfaces 1 and 5 (10 m, this study) 2. Transition (21 m) 2. Main Anhydrite (112 m) 3. Main Anhydrite (70–80 m) Powers et al. (1966) 3. Main Anhydrite (92 m) Total: 2 + 3 = 90.3 m 112 m Total: 2 + 3 = 113 m

The comparable thickness of the Hith Formation evaporites supports the interpretation that they were deposited subaqueously in a shallow hypersaline restricted basin that extended across the Arabian Plate (Azer and Peebles, 1998; Warren, 2006; Hughes and Naji, 2009). The geographic extent of this evaporitic platform continues with comparable depositional sequences and environments northwards into the Gotnia Basin in Iraq and Kuwait, and is manifested in Morocco (High Atlas Tithonian).

Maximum Flooding Surfaces

Sharland et al. (2001) discussed three options for the position of Upper Tithonian maximum ﬂooding surface MFS J110 (147 Ma) in subsurface Saudi Arabia: “probably not deposited”, or “possibly within intra-Hith Formation”, or “possibly near base of Manifa reservoir”. Haq and Al-

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DAHAL HIT SECTION (DH) (a) Bio- LFA turbation Components Intensity (m) Gamma- Dunham Stratigraphy Ray Texture Carbonate (API) Grain Size Thickness Intermediate Lithology Ooids Peloids Shells Coated grains Bioclasts Intraclasts Oysters Corals Gastropods Echinoderms BGR P WM Sequence Cycle Set Cycle Sparce Intense

15 75 Lu Si fA mA cA fR mR cR 0 SCS 5 12

10 SCS 11 15

SCS 20 10

25 SCS 9 30 SCS 8 35

MFI 40 (39.8 m) SCS 7 45

SCS 55 6 Sulaiy Formation

Lower Sulaiy Sequence 60 SCS 65 5 ? ? 70 SCS 4 75

80 SCS 3 85

90 SCS 2

Tithonian95 Berriasian JURASSIC CRETACEOUS SCS 1 100 Sulaiy SB 105 Hith Fm 110

115 Figure 4a: Logged properties, lithofacies types (LFT) and associations (LFA), and sequence stratigraphy of the Hith and Sulaiy formations at Dahal Hit (see Enclosure I for explanation of symbols). The contact of the Sulaiy Formation with the overlying Yamama Formation is not exposed at this locality. See facing page for continuation.

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Qahtani (2005) in their Jurassic–Neogene Chart positioned MFS J110 (147 Ma) in the lower part of the Sulaiy Formation but above the Manifa reservoir. Their chart indicates that MFS J110 may occur in a potential source rock interval but they did not discuss these interpretations in their paper. Neither Sharland et al. (2001) nor Haq and Al-Qahtani (2005) indicated a position for MFS J110 in Dahal Hit.

The lateral lithological continuity and comparable thicknesses of the Hith Formation from NE Saudi Arabia to Dahal Hit suggests that the Manifa member represents the earliest transgressive deposit of the Sulaiy Formation, which may have ﬂooded the majority of the Arabian Plate (Tables 1 and 2). We therefore suggest the Upper Tithonian MFS J110 occurs in the subsurface Manifa member and lowermost Sulaiy Formation at Dahal Hit. We interpret the contact between the Sulaiy and Hith formations at Dahal Hit as the “Sulaiy Sequence Boundary” or “Sulaiy SB”, and the evenly-bedded Sulaiy limestones to represent the start of the transgression in Dahal Hit (Figure 5). We therefore favor correlating the subsurface Manifa member to the most basal part of the Sulaiy Formation at Dahal Hit and to position MFS J110 (147 Ma) in them. North Outcrop South b STUDIED SECTIONS

The Yamama Formation conformably overlies the Sulaiy Formation (Vaslet et al., 1991). In the 12 studied sections the upper part of the Sulaiy Formation and its upper boundary were not studied (Figures 2 and 3). In this part of the paper, the logged sections are Dominated by documented graphically with a brief bioturbation sedimentological description and interpretation. For sections KW (South Dahal Hit), KP and KH, the description and interpretations are shown next to c Figures 6, 7 and 8, respectively. Biostromal marker zone Section DH (Dahal Hit)

Section DH (24°29'9.71"N, 46°59'49.47"E; UTM: X = 702381, Y = 2709500; Figures 1

Figure 4b: Beds that are interpreted as d tempestite storm deposits show increasing amounts of rudstones and bioclast-rich packstones towards the top.

Dominated by Figure 4c: The maximum flooding interval tempestites (MFI) is interpreted in Sulaiy Cycle Set Figure 5 SCS 7 and correlated to Lower Berriasian Sulaiy SB MFS K10. The photo shows an interval of biostromes, which occurs approximately 8 Breccia (Hith Fm) m below the MFI.

Anhydrites Figure 4d: Photo showing bedded (Hith Fm) bioclast-rich packstones that are interpreted as tempestite storm deposits and oolitic grainstones up to 2–5 dm-thick.

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Evenly-bedded limestones Sulaiy SB 5 Figure 5: At the Dahal Hit locality the Deformed anhydrite beds "Laminated Anhydrite" of the Hith Formation is eroded at "Surface 1". The 4 overlying Hith Breccia consists of two depositional sequences of limestone Breccia 2 ("Breccia 1" and the thicker "Breccia 2") and 3 evaporite (lower “Anhydrite beds” and

Hith Fm Sulaiy Fm Anhydrite beds 2 upper “Deformed anhydrite beds”). The Breccia 1 1 “Evenly-bedded limestones” of the Sulaiy Formation are interpreted as the oldest Laminated anhydrite deposits of the Sulaiy transgression, with 2 m the Sulaiy Sequence boundary at their base (Surface 5).

and 2) has a thickness of 116.2 m and is characterized, above the Hith Formation, by a transgressive- regressive sequence, the Lower Sulaiy Sequence (Figures 4 and 5). As discussed above (see Hith- Sulaiy Transition), the Sulaiy Sequence Boundary (SB) is positioned at the base of the evenly- bedded Sulaiy Formation.

The transgressive part is dominated by bedded bioclast-rich packstones, interpreted as tempestite storm deposits and up to 2–5 dm-thick oolitic grainstones (Figure 4d). A prominent interval of biostromes can be observed approximately 8 m below the assumed maximum flooding interval (MFI) containing Lower Berriasian MFS K10 (Figure 4c). This interval occurs in all studied sections and acts as an important marker. Maximum flooding is interpreted in an interval dominated by mud- and wackestones. Bioturbation constantly increases towards the MFI associated with destratification leading to a nodular appearance. The regressive part of the sequence consists of tempestites with increasing amounts of rudstones and bioclast-rich packstones towards the top. This succession indicates an increase of water energy. The stratigraphic contact to the overlying Yamama Formation could not be found at this locality but is exposed some 20 km in the hinterland of the Dahal Hit area.

Section NG (Wadi Nisah)

Wadi Nisah Section NG (24°13'35.70"N, 46°59'6.00"E; UTM: X = 706310, Y = 2680513; Figures 1 and 2) is located 28.76 km south of the type locality Dahal Hit and about 22 km SW of Section AH. Section NG has a thickness of 79 m and is characterized by the regressive hemi-sequence (Figure 9). Its lower part consists of bioclastic pack- and wackestones, interpreted as tempestite sheets. This lower part of the Sulaiy Formation correlates very well with the cycle sets of the other studied sections.

The upper part is completely dolomitized. Using cathodoluminescence microscopy ooid ghosts could be identiﬁed (Figure 10). The transition from limestone to dolomite shows very high gamma- ray values. The upper part of the regressive sequence shows a shallowing-upward trend, with the succession from foreshoal-associated tempestites to a more proximal shoal margin facies and ﬁnally to a shoal facies, which is dominated by oolitic grainstones with high-angle cross-bedding. The contact with the overlying Yamama Formation could not be detected in the Wadi Nisah area.

Wadi Nisah is the only section where dolomitization is observed and Sulaiy Cycle Set SCS 12 is the ﬁrst of three dolomitized cycle sets. Between SCS 12 and 13 a major change in depositional environment occurs (from foreshoal to shoal) suggesting their contact may be a sequence boundary. The uppermost part of the Sulaiy Formation is not completely studied as the contact with the overlying Yamama Formation could not be detected in the Wadi Nisah area. It might be possible that the Arabian Plate Upper Berriasian MFS K20 (141 Ma) is part of the younger, incomplete Upper Sulaiy Sequence.

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Section FI (Khafs Daghrah)

Khafs Daghrah Section FI (23°50'17.20"N, 47°11'51.30"E; UTM: X = 723834, Y = 2638038; Figures 1 and 2) is the southernmost section of the study area. It is located 74.5 km south of the type locality DH and 47.75 km SE of Section NG and has a thickness of 70 m (Figure 11). The lower transgressive part is mainly dominated by bioclastic wackestones and packstones. Crinoids are present in the lower part, also scattered corals can be observed 8 m below the MFI. Mud- and wackestones are dominant around the MFI and show intense bioturbation. The upper part shows an increase of high water-energy associated facies types and is interpreted as a regressive shallowing-upward trend. In the uppermost part of the section, bioturbated tempestites within a foreshoal setting turn into proximal tempestites (e.g. rudstones) and scattered corals of a shoal margin setting. The top of the section is marked by high-angle, cross-bedded oolitic-peloidal grainstones associated with a high-energy shoal environment.

Section EH (north Dahal Hit)

North Dahal Hit Section EH (24°29'49.20"N, 46°59'27.63"E; UTM: X = 701785, Y = 2638770; Figures 1 and 2) is located 1.5 km north of the Sulaiy and Hith type locality Dahal Hit and is 16.80 m thick (Figure 12). The lower, transgressive part consists at its base of bioclastic rud- and bioclastic pack- to-grainstones. The MFI is built by wacke- and mudstones. The regressive part above the MFI shows a gradual change in lithology to pack- and grainstones. Especially within the bioclastic packstones, grading can be observed which hints to an origin as tempestite deposits within a foreshoal setting.

Sections HL 1 to HL 4

Sections HL 1 to HL 4 are located 13 km north of the Sulaiy and Hith type locality Dahal Hit (24°30'17.51"N, 47°02'58.21"E; Figures 1 and 2). The thicknesses and UTM coordinates of the studied sections listed in Table 3. The studied sections have lateral distances to each others of 40, 140 and 120 m (Figure 13). The close spacing between the studied sections has the overall aim to focus on the lateral extent of the shoal geobodies. Each section shows a shallowing-upward trend, which is very similar to the trend observed in Section FI where high energy associated facies types like proximal tempestites, rud- and grainstones Table 3 Thickness increase upwards. The base of the shallowing- Section X-Coordinate Y-Coordinate upward trend is represented by bioturbated (m) tempestites, interpreted as foreshoal setting, HL 1 6.6 7547432 3342247 followed by proximal tempestites (e.g. HL 2 11.0 7547427 3342193 rudstones) and scattered corals. This succession grades into high-angle, cross-bedded oolitic- HL 3 10.7 7547365 3342040 peloidal grainstones, interpreted as high- HL 4 5.7 7547237 3341970 energy shoal environment.

Section SI

Section SI (23°50'11.3"N, 47°12'15.0"E; UTM: X: 724552, Y: 2635036; Figure 14) is located in the hinterland, southeast of Section FI and represents parts of its vertical succession. SI has a thickness of only 2.8 m and is therefore the thinnest of all studied sections. This is caused by lower outcrop quality due to intense weathering processes; nevertheless it shows very well the transition from a foreshoal setting into high-energy shoals. The characteristic transition starts with bioclastic and bioturbated wacke- and packstones, which are interpreted as tempestite deposits within a foreshoal environment. Bioclastic rudstones with erosive bases and scattered corals follow in the vertical succession grading into high-angle cross-bedded oolitic-peloidal grainstones, interpreted as high- energy shoal environment. A characteristic step-wise weathering proﬁle of the landscape led to the interpretation of at least three following shallowing-upward cycles.

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SOUTH DAHAL HIT SECTION (KW) (a) Bio- LFA turbation Components Intensity (m) Gamma- Dunham Stratigraphy Ray Texture Carbonate (API) Grain Size Thickness Intermediate Lithology Ooids Peloids Shells Coated grains Bioclaﬆs Intraclaﬆs Oyﬆers Corals Gaﬆropods Echinoderms BGR P WM Sequence Cycle Set Cycle Sparce Intense

15 60 Lu Si fA mA cA fR mR cR 0

SCS 5 12

SCS 11 15

20 SCS 10 25

SCS 30 9

SCS 35 8

40 MFI (42.4 m) 45 SCS 7

50 Sulaiy Formation Lower Sulaiy Sequence 55

SCS 60 6

SCS 70 5 ? ?

75 SCS 4

85 SCS Tithonian Berriasian 3 JURASSIC CRETACEOUS

Figure 6a: Logged properties, lithofacies types (LFT) and associations (LFA), and sequence stratigraphy of the Sulaiy Formation at South Dahal Hit (Section KW; see Enclosure I for explanation of symbols). The contacts of the Sulaiy Formation with the underlying Hith Formation and overlying Yamama Formation are not exposed at this locality. See facing page for continuation.

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North Outcrop South Section KW c (South Dahal Hit)

Section KW (24°28'25.30"N, 47°00'14.00"E; UTM: X = 702970, Y = 2708580; Figures 1 and 2) is located 2.5 km south of the type locality Dahal Hit. It is 90 m thick and consists of part of the Lower Sulaiy Sequence (Figure 6). Bedded SCS tempestites, primarily built of 10 bioclast-rich packstones and occasional rudstones dominate the transgressive part. Similar to Section DH, biostromes occur SCS below the MFI. The MFI shows 9 increasing bioturbation associated with destratification. The mud- and wackestones around the MFI are less resistant to weathering, which leads to recessive units. The regressive part of the sequence is composed mainly of bioclast-rich pack- and wacke-to-packstones. b Bioturbation is very intense, resulting in a nodular appearance. Maximum ﬂooding interval A 15 cm thick brachiopod-rich bed can be found 3.7 m below the top of Section KW. The contact with the overlying Yamama Formation could not be found in Section KW.

SCS 6

SCS 5

SCS 4

Figure 6c (photo on top): Sulaiy Cycle Sets SCS 9 to SCS 10 occur in the regressive part of the sequence and are mainly bioclast-rich pack- and wacke-to-packstones. SCS 3 Figure 6b: Sulaiy Cycle Sets SCS 3 to SCS 6 occur in the transgressive part of the Lower Sulaiy Sequence and are dominated by bioclast-rich packstones.

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Section KP

Section KP (24°24'6.40"N, 47°6'32.50"E; UTM: X = 713872, Y = 2700336; Figures 1, 2 and 7) has a thickness of 39.2 m, and represents a part of the Lower Sulaiy Sequence. The transgressive part of the

(a) Bio- LFA turbation Components Intensity (m) Gamma- Dunham Stratigraphy Ray Texture Carbonate (API) Grain Size Thickness Intermediate Lithology Ooids Peloids Shells Coated grains Bioclasts Intraclasts Oysters Corals Gastropods Echinoderms BGR P WM Sequence Cycle Set Cycle Sparce Intense

20 40 Lu Si fA mA cA fR mR cR 0

SCS 8 10

MFI

SCS 7 20 Sulaiy Formation Lower Sulaiy Sequence

SCS 6

? ? JURA CRETACEOUS Tithonian Berriasian Figure 7a: Logged properties, lithofacies types (LFT) and associations (LFA), and sequence stratigraphy of the Sulaiy Formation at Section KP (see Enclosure I for explanation of symbols). See facing page for continuation.

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sequence is formed by bioturbated bioclast-rich packstones that can be interpreted as tempestite deposits. Biostromes are present about 9 m below the MFI, which is characterized by a recessive unit formed by bioturbated mud- and wackestones. The regressive part of the sequence is formed by bioclast-rich packstones, which can be interpreted as storm bed deposits (tempestites). Towards the top of the section, bioturbation and destratification decreases.

North Outcrop South (b)

SCS 8

MFI

SCS 7

SCS 6

Figure 7b: Photo showing SCS 6–8 in outcrop. MFI is interpreted at SCS 7 and at the base of SCS 7 a biostromal marker bed with corals is present.

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Section AH

Section AH (24°22'55.90"N, 47°7'17.90"E; UTM: X = 715184, Y = 2698187; Figures 1, 2 and 8) has a thickness of 93 m. The transgressive part of the Lower Sulaiy Sequence is mainly formed by bioclast-rich packstones, which are interpreted as tempestites. Towards the MFI a biostromal interval

15 60 Lu Si fA mA cA fR mR cR 0

5 SCS 11 10

15 SCS 10 20

25 SCS 30 9

35 SCS 8 40

45 MFI SCS 50 7 Sulaiy Formation Lower Sulaiy Sequence 55

60 SCS 6 65

70 SCS 5 75 ? ?

80 SCS 4

85 Tithonian Berriasian JURASSIC CRETACEOUS 90

Figure 8a: Logged properties, lithofacies types (LFT) and associations (LFA), and sequence stratigraphy of the Sulaiy Formation at Section AH (see Enclosure I for explanation of symbols). See facing page for continuation.

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can be observed and destratification is caused by bioturbation. The regressive part of the sequence is dominated by bioclast-rich packstones and wacke-to-packstones, which are interpreted as bioturbated tempestites. In general, sections AH and KP show less rudstones and pack-to-grainstones or grainstones compared to sections DH and KW. It can be assumed that sections AH and KP were deposited in lower water-energy conditions in a slightly deeper water setting.

North Outcrop South (b)

SCS 9

SCS 8

MFI

SCS 7

SCS 6

SCS 5

Figure 8b: Photo showing SCS 5–9 in outcrop including interpreted maximum flooding interval (MFI) in SCS 7.

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WADI NISAH SECTION (NG) (a) Bio- LFA turbation Components Intensity (m) Gamma- Dunham Stratigraphy Ray Texture Carbonate (API) Grain Size Thickness Intermediate Lithology Ooids Peloids Shells Coated grains Bioclasts Intraclasts Oysters Corals Gastropods Echinoderms BGR P WM Sequence Cycle Set Cycle Sparce Intense

25 65 Lu Si fA mA cA fR mR cR 0

SCS 15 10

20 SCS 14 Upper Sulaiy Sequence 25

30 SCS 13

35 SB?

Berriasian SCS Sulaiy Formation

CRETACEOUS 12 45 Beginning of dolomitization

50 SCS 11

55 SCS 10 60 Lower Sulaiy Sequence 65 SCS 9

75 SCS 8

Figure 9a: Logged properties, lithofacies types (LFT) and associations (LFA), and sequence stratigraphy of the Sulaiy Formation at Wadi Nisah (see Enclosure I for explanation of symbols). The upper part of the Wadi Nisah Section is dolomitized from SCS 12 onwards. See facing page for continuation.

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(b) North South

SCS 14

SCS 13

SB?

SCS 12

Beginning of dolomitization tempesites Dominated by Figure 9b: Transition from tempestite dominated foreshoal deposits (below SCS 12) into oolitic shoal environment. Between SCS 12 and 13 a possible sequence boundary is present.

a b

500 μm 500 μm

Figure 10: Thin section from dolomitized, oolitic grainstones. (a) Light optical microscope, (b) Cathodoluminescence reveals ooid ghosts. Black arrows mark the cores of the ooids; white arrows show a concentric construction.

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SECTION KHAFS DAGHRAH (FI) (a) Bio- LFA turbation Components Intensity (m) Gamma- Dunham Stratigraphy Ray Texture Carbonate (API) Grain Size Thickness Intermediate Lithology Ooids Peloids Shells Coated grains Bioclasts Intraclasts Oysters Corals Gastropods Echinoderms Crinoids BGR P WM Sequence Cycle Set Cycle Sparce Intense

15 50 Lu Si fA mA cA fR mR cR 0

U Sulaiy Oolitic grainstones marker (shoals) Sequence 5

10 SCS 12

SCS 20 11

25 SCS 10

SCS 35 9 Sulaiy Formation 40 SCS 8 Lower Sulaiy Sequence

50 SCS MFI 7

SCS 6 65 ? ? Tith Berriasian JUR CRETACEOUS 70 Figure 11a: Logged properties, lithofacies types (LFT) and associations (LFA), and sequence stratigraphy of the Sulaiy Formation at Khafs Daghrah (see Enclosure I for explanation of symbols). The contact of the Sulaiy Formation with the overlying Yamama Formation is not exposed at this locality, but the transition into oolitic grainstones (shoals) and the base of the Upper Sulaiy Sequence can be seen. See facing page for continuation.

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North Outcrop South b

Oolitic grainstones (shoals)

Figure 11b: Oolitic grainstones with cross-bedding (interpreted as shoals) mark the beginning of the Upper Sulaiy Sequence.

Figure 11c: Interpreted cycles are shown (not SCS like the other sections). Outcrop Khafs Daghrah is more affected by weathering and has a “staircase” like appearance; hence only cycles are represented at Figures 11c and d.

Figure 11d: Cycle at the top of SCS 6 is shown in detail. Thicker and harder packstones (interpreted as tempestites) form the top of the cycle.

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Jurassic–Lower Cretaceous Sulaiy Formation, central Saudi Arabia

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LITHOFACIES ANALYSIS

Ten lithofacies types have been identiﬁed within the Sulaiy Formation and three from the underlying Hith Formation (Figure 15 and Table 4). For each type, biofacies, ichnofacies (Seilacher, 2007) and stratofacies have been deﬁned (Figures 16 to 28).

Figure 15 (facing page): Schematic depositional model (modiﬁed Ooids Tempestites after Tucker and Wright, 1990) used to interpret the setting of the 13 lithofacies types (LFT) along ramp proﬁle. Note that LFT 10 (breccia) Shell Cross bedding can occur in settings ranging from supratidal to shoal margin; in Biostromes Bioturbation contrast the other LFTs generally represent a unique setting.

Table 4 Overview of Lithofacies Types (LFT)

Physical Sedimentary Biogenic Sedimentary Lithofacies Type Lithology and Texture Structures Structures

LFT 1: Laminated/ Limestone, mudstone mm to cm scale lamination Bioturbation bioturbated mudstones table continued LFT 2: Graded wackestones Limestone, wackestones Fine grading, cm to dm thick Minor bioturbation layers

LFT 3: Bioturbated wacke/ Limestone, wackestones, Graded bedding, cm to dm Abundant bioturbation, wacke-to-packstones wacke-to-packstones thick layers destratiﬁcation

LFT 4: Biostromal Limestone, biogene - Biogene build-ups boundstones build-ups, boundstones

LFT 5: Bioturbated Limestone, packstones, Erosive bases, graded Abundant bioturbation, pack/pack-to-grainstones pack-to-grainstones bedding destratiﬁcation

LFT 6: Graded packstones/ Limestone, packstones, Erosive bases graded - grainstones grainstones bedding

LFT 7: Bioclastic Limestone, floatstones, Imbrication, amalgamated Bioturbation, partly floatstones/rudstones rudstones beds destratification

LFT 8: Well-sorted pack-to- Limestone, packstones, Low-angle cross-bedding Minor burrows grainstones pack-to-grainstones

LFT 9: Well-sorted, cross- Limestone, dolostone, High-angle cross-bedding Minor burrows bedded grainstones grainstones

LFT 10: Breccia Limestone, minor quartz, Breccia - breccia

LFT 11: Tepee-dominated Anhydrite Tepees, enterolithic folds - anhydrite

LFT 12: Laminated Anhydrite, dolostone Fine lamination (mm-cm) - anhydrite

LFT 13: Nodular anhydrites Anhydrite Chicken-wire structures - table continued

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DEPOSITIONAL ENVIRONMENT OF SULAIY FORMATION

Tidal Shoal Transition Supratidal ﬂat Backshoal Shoal margin Foreshoal zone Offshoal LFT 10 LFT 9, LFT 8, LFT 5 to LFT 10 LFT 10 LFT 3, LFT 4 LFT 1, LFT 2 to LFT 13 LFT 10 LFT 10 LFT 7 Back ramp Shallow ramp Deep ramp Sea level

Fair-weather wave base

Storm wave base

Wave Energy

Storm Energy Figure 15: See caption and legend on facing page.

Table 4 (continued)

Grain Size ComponentsPorosity Type Thickness Interpretation and Sorting

Lutite to siltite, Scattered very ﬁne shell None visible cm to dm thick Offshoal, low-energy very-well sorted debris units deposits (suspension)

Siltite to ﬁne arenite, Bivalves, shell debris, None visible cm to several Storm event deposits (distal moderate to poorly peloids bioclasts, rarely dm thick units tempestites) in a deep ramp, sorted planktonic foraminifers offshoal-setting

Siltite to ﬁne arenite, Bivalves, brachiopods, Interparticle cm to dm thick Bioturbated tempestites, poorly sorted gastropods, shell debris, (BP) units, rarely m deposited in the transition peloids, echinoderms thick zone

Fine to coarse rudite, Corals, gastropods, Moldic (MO) dm to m thick Growth of biogene build-ups poorly sorted bivalves, echinoderms, units; km’s in the transition zone bioclasts, peloids lateral extension

Siltite to ﬁne arenite, Bivalves, gastropods, Interparticle cm to dm thick Tempestite deposits in a moderate to poorly echinoderms, shell debris (BP) units foreshoal environment; sorted destratiﬁcation due to bioturbation

Fine to coarse arenite, Bivalves, gastropods, Interparticle cm to dm thick Proximal tempestite moderate to poorly echinoderms, shell debris, (BP) units deposits in a foreshoal sorted bioclasts, intraclasts environment

Medium arenite to ﬁne Bivalves, gastropods, Interparticle several dm thick High-energy events, very rudite (rarely medium echinoderms, shell debris, (BP) and Moldic units proximal tempestites in a rudite) bioclasts, intraclasts (MO) foreshoal setting

Fine to medium Shell debris, bioclasts, Interparticle dm thick units High-energy deposits in a arenite, well sorted echinoderm debris, (BP) shoal margin setting peloids, ooids, intraclasts

Fine arenite Ooids, peloids, minor shell Interparticle dm to m thick High-energy shoal deposits debris (BC) units

Lutite to boulder, Bioclast-rich packstones Interparticle dm to several m Exposure and reworking of poorly sorted and oolitic grainstones (BP), Moldic thick units sediment, supratidal to shoal (MO), vug (VUG) setting

- -None cm to several m Exposure and arid climate, thick units sabkha, supratidal setting

- Cm to dm thick dolomite None m to several m Subaquaous deposition in a banks with wave ripples as thick units salina environment with a result of marine water periodic ﬂooding (dolomite inﬂux stringers), supratidal setting

- Anhydrite nodules due to Nonem to several m Exposure and arid climate, intrasedimentary growth thick units sabkha, supratidal environment

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LFT1: LAMINATED AND BIOTURBATED MUDSTONES (a) Outcrop (b) Microfacies

5 mm 5 mm

Figure 16b: Photomicrographs include rare, very fine shell debris (Sd in left photo) and Figure 16a: Outcrop view from Section AH, 50 burrows filled with wackestones/packstones m depth, showing laminated and bioturbated (Bu in right photo), no porosity visible. mudstones (hammer for scale). The fine lamination is the result of sedimentation under very quiet, low-energy conditions. Some mudstones are bioturbated and show burrows that are filled with wackestones or packstones. (d) Stratofacies The environment of deposition of these laminated/bioturbated mudstones can be located in a very distal, offshoal setting.

Figure 16c: Photomicro- graph on left shows main fossils are shells and fine shell debris. Ichnofossils in outcrop photo above 50 cm include burrows filled with wackestone/packstone from Figure 16d: The laminated/bioturbated overlying beds (Bu). Filled mudstones can be recognized in outcrops due burrows are often very well to its weak resistance to weathering. They are 5 mm preserved (hammer for present in all studied sections and associated scale). with deposition in low-energy conditions.

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LFT2: GRADED WACKESTONES (a) Outcrop (c) Biofacies

5 mm 5 mm

Figure 17c: Thin sections show the dominant fossils are bivalve shells and shell debris. A Figure 17a: Outcrop view from Section DH, 70.4 fining-up trend can be observed and m depth (hammer for scale). The wackestones interpreted as distal tempestite deposits. Lower contain mostly shell debris and show a fine photo shows abundant burrows filled with grading as shown in thin section (see Figure coarser material from an overlying tempestite 17b, left photo). The grain size and the (top view of bed). occurrence of planktonic foraminifers can be associated with deposition under low-energy conditions in an offshoal setting. The fine (d) Stratofacies grading of the wackestones can be interpreted as distal tempestites that were deposited in an offshoal setting.

Graded (b) Microfacies wackestones

Bc Bv

0.5 m Pd, Sd 5 mm 5 mm Figure 17d: Outcrop view from the Dahal Hit Figure 17b: Photomicrograph on left shows type locality. Graded wackestones are grading in wackestones. Bivalves (Bv), indicated. They represent a succession of distal bioclasts (Bc), peloids (Pd) and very fine shell tempestites which show erosive bases and a debris (Sd) are shown. fining-up towards the top.

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LFT3: BIOTURBATED WACKE-/WACKE-TO-PACKSTONES (a) Outcrop (c) Biofacies 1 5

6 3

5 mm

Figure 18a: Outcrop view from Section DH, 25 Figure 18c: Fossils include (1) gastropods, (2) m depth showing bioturbated wacke-/wacke- bivalves and (3) brachiopods dorsal view, (4) to-packstones (hammer for scale). This facies ventral view and (7) Terebratula. Ichnofacies type can be recognized by its very characteristic include (5) burrows filled with wackestone/ nodular appearance. It is the result of strong packstone and (6) bioturbation. bioturbation which led to destratification, even though some primary layers are still (d) Stratofacies observable. This facies type can be interpreted as tempestites that have been reworked by burrowing organisms after deposition. More resistant to weathering wacke-to-packstones (b) Microfacies

Wackestones

Bv G Bv

Figure 18d: Typical outcrop view of the bioturbated wacke-/wacke-to-packstones. The nodular appearance is the result of intensive 5 mm 5 mm bioturbation. In the lower photo the stair- Figure 18b: Photomicrographs showing shaped weathering profile shows that the bivalves (Bv), gastropods (G) and shell debris wacke-to-packstones are more resistant to (Sd). Yellow box in right photo indicates weathering and build the tops of the stairs oriented shell and echinoderm debris. (yellow arrows).

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LFT4: BIOSTROMAL BOUNDSTONES (a) Outcrop (b) Microfacies

Sd G

E C

5 mm Figure 19a: Outcrop view from Section DH, 48.80 m depth. Biostromal boundstones contain a very rich fauna which includes corals, bivalves, very big gastropods (up to 7 cm), echinoderms, shell debris and Bv bioclasts. They form a biostromal complex and can be recognized in the field by its big molds. Some biostromal boundstones are only 3–5 meters wide (shown in light blue overlay) but they occur in a certain zone that shows a lateral extension of several kms. The environment of Bv deposition can be located in the transition zone.

5 mm

Figure 19b: Photo- micrographs showing bivalves (Bv), 4 5 6 gastropods (G), corals (C), echinoderms (E) and peloids (Pd) in yellow box.

Figure 19c: Fossils include (1) corals, (2) solitary corals, (3) bivalves and (4) bivalve molds; (5) gastropods and (6) echinoderms.

(d) Stratofacies

Figure 19d: Biostrome that seems to have homogeneous lateral extension. A lateral discontinuity for single geobodies is shown in Figure 19a.

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LFT5: BIOTURBATED PACK-/PACK-TO-GRAINSTONES (a) Outcrop (b) Microfacies

Sd, Ed 5 mm

Bv G

Sd, Ed 15 cm 5 mm

Figure 20a: Outcrop view from Section DH, 69.50 m depth. Bioturbated Figure 20b: pack-/pack-to- grainstone facies can be recognized in outcrop by its Photomicrographs nodular appearance. However, it shows erosive bases and in some beds showing bivalves (Bv), grading is still visible. Shells and gastropods are abundant. Due to gastropods (G) and intensive bioturbation the layers are destratified. It can be interpreted shell- and echinoderm as tempestite deposits in a foreshoal setting that were afterwards debris (Sd, Ed, yellow intensively bioturbated. box).

Figure 20c: Shells and shell fragments (left photo) are major components of this facies type. Gastropods (right photo) are common and can reach remarkable sizes (hand lens for scale). See facing page for continuation.

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LFT5: (continued) (c) Biofacies (continued)

Figure 20c (continued): The typical shape of asterosomids are the result of a certain burrow technique. It is a combination of a burrow system in which the waste material produced by the animal was stowed away in a form of radial backfills. The material was deposited in the wall of the tunnel and then the animal pressed it radially out (Seilacher, 2007).

Rhizocorallium

Protrusive (limbs retrusive)

Figure 20c (continued): The Rhizocorallium ichnofacies is the result of a lithified backfill structure of an arthropod tunnel system (feeding burrow). It is characterized by a particular technique of burrow construction. The U-bend tunnel shows a typical spreite that consists of stacked lamellae of reworked sediment. It is a so-called protrusive structure, indicating that the U-bend tunnel became deeper at every stage. This tunnel system is most probably made by a crustacean. Rhizocorallium was a feeding burrow that was horizontal or slightly inclined to the bedding. The excessive length of the tube indicates a higher water energy that was necessary for flushing the tunnel system. In general, the Rhizocorallium ichnofacies can be found in softgrounds, usually in tempestites on the shelf (Seilacher, 2007). See next page for continuation.

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LFT5: (continued) (c) Biofacies (continued) fecal pellets

commensal crab shafs

turnarounds

gallery system Tunnel Systems Tunnel cork screw Callianassa seilacheri Thalassinoides Granularia Figure 20c (continued): The Thalassinoides tunnel system was made by a crustacean. Its burrows are quite deep and show a typical pattern. The crustacean first burrowed perpendicular into the sediment to form an air shaft, then created a horizontal and connected tunnel system as shown above. In the fossil record these horizontal turnarounds can be observed in the top view of a bed (upper photo on left), showing a typical star-shaped pattern (Seilacher, 2007). The typical star-shaped turning points in this tunnel system are marked in green (lower photo on left, hammer for scale).

Abyssal - Bathyal Intermediate Shelf facies-breaking (no even (turbidites) layers) (tempestites) Ichnogenera oscillation ripples

turbidite structures

Figure 20c (continued): The Cruziana ichnofacies consists of several trace fossils. During the Thalassinoides Jurassic and Cretaceous the most common ones are Arthropod tracks, Ophiomorpha (Thalassinoides), Rhizocorallium, Asteriacites, Actinian burrows, Lockeia, Curvolithus, Gyrochorte, Teichichnus, Diplocraterion and Asterosoma. In the Sulaiy outcrops Rhizocorallium Thalassinoides, Rhizocorallium and Asterosoma could be observed. The Cruziana facies is typical for softgrounds and a tempestitic shelf environment of deposition can be assumed (Seilacher, 2007). See facing page for continuation.

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LFT5: (continued) (d) Stratofacies 1 2 3

Figure 20d: Bioturbated tempestites are the major element of this facies type. The tempestites show a strong influence of bioturbation. Often, the burrows are filled with coarser material from the overlying tempestite as shown in photo 2. If the bioturbation is more abundant and more intensive, then destratification can be observed (photo 3). It destroys the primary sedimentary structures and can lead to a nodular appearance in the outcrops.

W E

n=20 S

25 cm

Figure 20d (continued): Wave ripples from Section FI. The orientation of the crests is shown in the diagram on the right. The wave direction is marked in gray and is usually perpendicular to the shoreline.

W E

n=11 S

Figure 20d (continued): These interference ripples are from Section FI. (Brunton compass for scale.)

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LFT6: GRADED PACKSTONES - GRAINSTONES (a) Outcrop (c) Biofacies

50 cm

Figure 21a: Outcrop view from Section KW, 20.5 m depth. The main characteristic of this facies 2 cm type is the graded bedding. The base consists of larger components (coarse arenite) like Figure 21c: Most common fossils are bivalves bivalve shells, gastropods, bioclasts and and shell debris as well as gastropods (top intraclasts while the top is dominated by shell photo). Occasionally bioturbation (bottom debris and peloids with a fine arenite grain photo) can be observed in the upper part of the size. The contact between the layers is erosive tempestites. and can be observed in thin section (see Figure 21b right photo). This facies type is interpreted (d) Stratofacies as proximal tempestites in a foreshoal setting with moderate energy.

(b) Microfacies

Sd, Ed Sd, Ed

I Bv Bv G Figure 21d: Gutter casts are filled isolated I erosional structures (Aigner and Futterer, 1978) and can be very important for the interpretation of storm deposits in deeper areas. During a storm event the 5 mm 5 mm offshore-oriented return current generates Figure 21b: Photomicrographs showing erosional structures that are filled with bivalves (Bv), gastropods (G), intraclasts (I) and sediment when the energy flow decreases at shell- and echinoderm debris (Sd, Ed, yellow the end of a storm. box). See facing page for continuation.

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LFT6: (continued) (d) Stratofacies N (continued) Gutter Figure 21d (continued): In Section Orientation Cast (FI) FI, five gutter casts could be 1 120° measured. Their orientation is illustrated in the left rose diagram. W E 2 135° The direction of the gutter casts is 3 140° almost perpendicular to the wave 4 130° ripples from Section FI (as 5 140° described in LFT 5) and therefore S perpendicular to the coastline.

Figure 21d (continued): Graded bedding is the most characteristic sedimentary structure of this facies type. They form cm- to dm-thick units, with an erosive base and a fining-up to the top. Abundant shells can be observed at the base.

LFT7: BIOCLASTIC FLOATSTONES - RUDSTONES (a) Outcrop (b) Microfacies

G I

5 mm 5 mm

Figure 22b: Photomicrographs showing bivalves (Bv), gastropods (G) and intraclasts (I).

Figure 22a: Outcrop view from Section AH, 59.70 m depth (hammer for scale). Bioclastic floatstones - rudstones is a component-rich facies type that is characterized by large grain sizes and sorting. Interparticle porosity and large bivalves or gastropods were dissolved leading to moldic porosity. Imbrication of intraclasts and other components can be observed and are an indicator of higher energy. The deposition of bioclastic floatstones - rudstones is interpreted within a foreshoal setting. See next page for continuation.

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LFT7: (continued) (c) Biofacies

2 cm

Figure 22c: The most common fossils are bivalves. They can reach up to 5 cm (left photo). Bioturbation can be observed as well (photo on right). It can lead to destratification (hammer for scale).

(d) Stratofacies Tempestite Orientation N

W E

n=15 S

Number of Intraclast Intraclasts Orientation Figure 22d: Imbrication can be observed in several bioclastic rudstones (photo above). The 6 NNE size of the clasts (up to 8 cm) indicate 2NE high-energy events with a unidirectional 5N current indicative of proximal tempestites. 2 NNW Figure 22d (continued): The orientation of the clasts can be useful to understand a general trend of the tempestite orientation. The diagram above gives the direction (sample rate n=15).

Figure 22d (continued): Photo on the left is showing a succession of bioclastic tempestites with a sharp erosive base and a fining-upward sequence. The fining-upward sequence can show bioturbation as well.

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LFT8: WELL SORTED PACK-TO-GRAINSTONES (a) Outcrop (b) Microfacies

Sd, Pd Sd, Pd

5 mm 5 mm

Figure 23b: Photomicrographs showing bivalves (Bv); intraclasts (I); and peloids (Pd) and shell debris (Sd) (yellow boxes).

Figure 23a: Outcrop view from Section AH, 59.70 m depth. This facies type is represented by packstones and pack-to-grainstones that consist basically of well sorted shell debris. A low-angle cross bedding can be observed in the field as well as in the thin sections (e.g. AH 1). The good sorting of the components and the low-angle cross bedding are typical for environments of higher water energy. The environment of deposition is interpreted to be in a shoal margin setting.

Figure 23c: Major components are shells and shell debris (left photo, DH 37). Well sorted pack-to- grainstone with

1 cm 2.5 cm burrows (right photo, AH 1).

(d) Stratofacies

Right photo

Figure 23d: Low-angle cross bedding as seen in outcrop and marked in yellow in the enlargement (right photo, hammer for scale).

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LFT9: WELL SORTED/CROSS-BEDDED GRAINSTONES (a) Outcrop (b) Microfacies

Pd Figure 24b: Photomicrograph showing shells (S), ooids (O) and peloids 5 mm (Pd).

(d) Stratofacies

Figure 24a: Outcrop view from Section FI, 72 m depth, showing well sorted/cross-bedded grainstones which consist mainly of ooids and peloids (hammer for scale). The sorting is very good and high-angle cross bedding can be observed. Moldic porosity due to leached components is present and can lead to good reservoir properties. In section NG, ooids and peloids were diagenetically altered to dolomite. The environment of deposition can be associated with a high-energy shoal environment.

Figure 24d: Outcrop view of an oolitic shoal 250 μm complex, from section NG (top photo, hammer for scale). Cross-bedded oolitic grainstones (bottom photo). Cross bedding is marked in black.

Figure 24c: Biofacies include brachiopods, bivalves, ooids, peloids (see Figure 24b) and coated grains (top photo). Outcrop photo shows burrows in cross-bedded grainstones (bottom photo, hammer for scale).

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LFT10: BRECCIA (a) Outcrop (b) Microfacies

Pv V

5 mm 5 mm

Figure 25b: Photomicrographs showing ooids (O), peloids (Pd), shells (S) and coated grains (Cg). Moldy porosity (M) and vuggy porosity (V) are present and indicated by blue impregnation.

Figure 25a: The breccia can be observed at the Dahal Hit type locality (hammer for scale). The components of the breccia are usually cm- to dm-thick and bioclast-rich packstones or oolitic grainstones. A mudstone matrix can be observed, which contains quartz grains. The oolitic grainstones show abundant moldic porosity due to the dissolution of the ooids. Vuggy porosity can be observed in the mudstone matrix. The prominent breccia horizon probably results due to exposure.

500 nm 500 nm

2 3b

500 nm 500 nm 500 nm

Figure 25c: Photomicrographs from the mudstone matrix of the breccia. No components could be observed (photo 1). Vuggy porosity is visible (photo 2). Quartz grains (Q) are present in some samples of the mudstone matrix from the breccia (photo 3a, plane polarized light; photos 3b and 4, crossed nicols and lambda quarter-wave blade). See next page for continuation.

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LFT10: (continued) (c) Biofacies (continued)

S Br Cg

Gr M O O M Pd Pd Pd

500 nm 500 nm 250 nm

Pd Gr

Pd O Pd

O M

500 nm 125 nm 250 nm

Figure 25c (continued): Figure 25c (continued): Photomicrgraphs from DH 10 show ooids (O), peloids (Pd), shells (S), molds (M), gastropods (G), grapes (Gr), brachiopods (Br) and coated grains (Cg).

Figure 25c (continued): Photo- Pd micrographs from DH 9 can be described as an oolitic-peloidal Gr O grainstone. Ooids and peloids O are the major components Gr S M G along with shells. They are indicators for high energy with M a constant water movement. Pd Ooids and other components as S well as grapestone fabrics are 250 nm 500 nm marked. Grapestones are formed by microbial activity, usually during a time of very M low water movement. The O grapes can be turned around Gr and transported during high-energy events. The Gr porosity is marked in blue. Moldic porosity is very O abundant due to the fact that Pd especially ooids can be easily dissolved. Also shells and peloids show moldic porosity. 250 nm 250 nm See Figures 4d and 5 for Breccia Stratofacies.

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LFT11: TEPEE DOMINATED ANHYDRITE (a) Outcrop

50 cm 1 m

Figure 26a: The finely laminated anhydrites show prominent horizons dominated by tepee structures and enterolithic folds. The tepee structures are indicators for exposure and show a range in size from cm to dm in thickness. Enterolithic folds as a result of displacive intrasedimentary growth can be observed as well.

(b) Stratofacies

Figure 26b: Photo on the left shows a detailed view of an enterolithic fold (pencil for scale). Photo on the right shows a detailed view of a tepee structure (pen for scale). Tepees and enterolithic folds can range in size between 5 cm up to several dm.

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LFT12: LAMINATED ANHYDRITE (a) Outcrop

1 m 1 m

Figure 27a: The finely laminated anhydrites have a thickness of several dm up to 10s of meters and dominate the upper part of the Hith Formation. The lamination itself is very fine with a variation from several mm to cm. The fine lamination shows a high lateral extend which is an indicator for a very flat relief. A salina environment can be assumed for the laminated anhydrites.

(b) Stratofacies

Figure 27b: Detailed view of a laminated anhydrite. The lamination is very regular with a thickness of several mm up to a cm for each layer (hammer for scale).

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LFT13: NODULAR ANHYDRITE (a) Outcrop

Figure 28a: Outcrop view of nodular anhydrites from Dahal Hit cave. This facies type is characterized by the nodular appearance of the anhydrites. Two subtypes can be observed, depending on the size of the anhydrite nodules ranging from 2–5 cm and 5–10 cm. They build a so-called chicken-wire structure, which is the result of intrasedimentary growth, due to high evaporation and an upward movement of porewater. Chicken-wire anhydrites usually form in a sabkha environment.

(b) Stratofacies

25 cm

Figure 28b: Outcrop view of the nodular anhydrites (left photo). Photo on right shows a detailed view of chicken-wire anhydrite (pen for scale).

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SEQUENCE-STRATIGRAPHIC ANALYSIS

Cycles

Lithofacies types within the Sulaiy Formation are commonly arranged in regular, cyclic patterns. A clear hierarchy of cyclicity can be observed, which is described below following the terminology of Kerans and Tinker (1997). The smallest cyclic units are usually meter-scale and are termed "cycles". They usually consist of a lower transgressive hemi-cycle, a maximum ﬂooding interval, and an upper, regressive hemi-cycle. The cycles are grouped into the following "cycle motifs".

Offshoal to Transition Zone Cycle Motif Description: This symmetrical cycle motif is usually 3–4 m thick (Figure 29). Offshoal and transition zone associated facies types such as laminated and bioturbated mudstones (LFT1), graded wackestones (LFT2) and bioturbated wacke-to-packstones (LFT3) dominate. The lower part of the cycle consists mainly of wackestones, which are inter-bedded with 5–10 cm-thick, graded pack- and wacke-to-packstone units. The wacke- and packstones contain shells, shell debris and gastropods and show intense bioturbation, which can lead to destratiﬁcation. In some cases the burrows are ﬁlled-up with coarser material of the overlying packstones (tubular tempestites). Mudstones (LFT1) occur in the middle part of the cycle motif followed upwards by the succession of graded wackestones (LFT 2) and bioturbated wacke-to-packstones (LFT3).

Interpretation: Graded wackestones (LFT2) and bioturbated wacke-to-packstones (LFT3) mark the base of this cycle type. They can be interpreted as bioclast-rich distal tempestites, which were deposited under low-energy conditions, representing the transgressive hemi-cycle, following mudstones containing minor amounts of very ﬁne shell debris. The mudstones were deposited under low-energy conditions and interpreted as the MFI. In the ﬁeld the mudstone section can

OFFSHOAL TO TRANSITION ZONE CYCLE MOTIF Close up North Outcrop South Dunham Texture Thickness (m)

BGR P WM LFA Cycle 4

15 cm 3

2 cm 0 Figure 29: Outcrop appearance at Section AH, 43–47 m depth, close up and simplified sedimentological log of offshoal to transition zone cycle motif from section AH.

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often be recognized by its lower resistance to weathering. The regressive hemi-cycle shows the same succession of facies types like the transgressive hemi-cycle but in a reversed order. The wackestones are harder and therefore more resistive to weathering processes.

Offshoal to Foreshoal Cycle Motif Description: The offshoal to foreshoal cycle type has an average thickness of 4 m and shows a symmetrical pattern (Figure 30). The base of the cycle is dominated by packstones that contain shells and shell debris as well as peloids and show graded bedding with erosive bases (LFT6). They form amalgamated 5–10 cm thick layers. In some sections strong bioturbation can be observed which results in destratification (LFT5). These burrows are often filled-up with packstones. Wackestones with strong bioturbation follow in the vertical facies succession (LFT3). Mudstones (LFT1) with minor amounts of very fine shell debris mark the turning point of the cycle. The upper part of the cycle motif is represented through LFT3, LFT5 and LFT6. In the field, this cycle type can be easily recognized by its characteristic weathering profile where the mudstones build recessive units.

OFFSHOAL TO FORESHOAL CYCLE MOTIF Close up North Outcrop South Dunham Texture Thickness (m)

BGR P WM LFA Cycle 4

15 cm 3

10 cm 0

LFA Offshoal Foreshoal Figure 30 Transition zone Shoal margin Figure 29 Key Bioclasts Regressive hemi-cycle Peloids Transgressive hemi-cycle Erosive bases Ooids Bioturbation Corals Gastropods

Figure 30: Outcrop appearance at Section NG, 76–72 m depth, close up and simplified sedimentological log of offshoal to foreshoal cycle motif from Section NG.

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TRANSITION ZONE TO SHOAL MARGIN CYCLE MOTIF Close up North Outcrop South Dunham Texture Thickness (m)

BGR P WM LFA Cycle 5

1.5 cm

0 Figure 31: Outcrop appearance at Section DH, 53–48 m depth, close up and simplified sedimentological log of transition zone to shoal margin cycle motif from Section DH.

Interpretation: The basal graded packstones (LFT6) most likely represent tempestite deposits in a foreshoal environment. The packstones, together with upward-following lower-energy wackestones (LFT3) with abundant bioturbation and a decrease in grain size, are interpreted as the transgressive hemi-cycle. The MFI is assumed to be represented by bioturbated mudstones (LFT1). The regressive hemi-cycle shows the same facies stacking pattern as the transgressive hemi-cycle but in a reversed order.

Transition Zone to Shoal Margin Cycle Motif Description: The transition zone to shoal margin cycle type has an average thickness of 5 m and shows an asymmetric pattern. At its base pack-to-grainstones (LFT8) with shell debris and peloids can be observed, followed by grain-, pack- and wackestones (Figure 31). Grading can be observed and the major components are shells, shell debris, bioclasts and peloids (LFT3, LFT5 and LFT6). The most open-marine part of this cycle is represented by biostromes with corals, gastropods, bivalves, echinoderm etc. Wacke- and packstones interbedded with minor 5 cm thick pack-to-grainstones layers (LFT3, LFT5 and LFT6) build the upper part of the cycle. The shoal margin associated facies is not as dominant as in the lower part of the cycle.

Interpretation: The transgressive hemi-cycle consists of basal well-sorted pack-to-grainstones (LFT8) with low-angle, cross-bedding, interpreted to be deposited in a shoal margin setting, followed by bioturbated wacke-to-packstones (LFT3), pack-to-grainstones (LFT5) and graded packstones/grainstones (LFT6), interpreted as tempestite deposits during high-energy events within a foreshoal environment. An MFI can be recognized by prominent biostromes. The regressive hemi-cycle is signiﬁcantly thinner than the transgressive hemi-cycle and consists of LFT3, LFT5 and LFT6.

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FORESHOAL TO SHOAL MARGIN CYCLE MOTIF Close up North Outcrop South Thickness (m)

BGR P WM LFA Cycle 2

15 cm

3 cm

15 cm 0

LFA Offshoal Foreshoal Figure 32 Transition zone Shoal margin Figure 31 Key Bioclasts Regressive hemi-cycle Peloids Transgressive hemi-cycle Erosive bases Ooids Bioturbation Corals Gastropods

Figure 32: Outcrop appearance at Section DH, 78–80 m depth, close up and simplified sedimentological log of foreshoal to shoal margin cycle motif from Section DH.

Foreshoal to Shoal Margin Cycle Motif Description: The foreshoal to shoal cycle type is the most proximal cycle motif that could be observed within this study (Figure 32). The thickness of this asymmetric cycle type ranges between 2–3 m. The base of the cycle consists of 5–20 cm-thick, well-sorted, ﬁne-to-medium arenite pack-to- grainstones and grainstones with well-developed erosive bases (LFT8). Shell debris, shells, small intraclasts, peloids and ooids are the major components. Low-angle, cross-bedding can be observed in the outcrop as well as in thin sections. This is followed by a rudstone (LFT7) with shells, gastropods, bioclasts, peloids and intraclasts. The upper part of the cycle is built-up by well-sorted grainstones with bed thicknesses of 10–20 cm. Some of these grainstone units are interbedded with thin mudstone units.

Interpretation: The foreshoal to shoal margin cycle motif is clearly dominated by the regressive hemi-cycle. The thin, basal pack-to-grainstones represent a shoal margin environment (LFT8). Bioclast-rich rudstones represent the MFI. These several dm-thick rudstones (LFT7) can be interpreted as proximal tempestites within a foreshoal setting. The dominating regressive hemi- cycle consists of well-sorted grainstones (LFT8).

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Cycle Sets

Cycles are commonly stacked into cycle sets. In this study cycle sets are named as SCS, which stands for “Sulaiy Cycle Set” and are numbered from 1–15. Several motifs of cycle sets could be recognized as follows.

Offshoal to Shoal Cycle Set Motif Description: The offshoal to shoal cycle set shows an asymmetric pattern with a dominating regressive hemi-cycle set. It has an average thickness of 10–12 m, and is usually built by up to 4 cycles (Figure 33). This cycle set represents the complete succession of observed facies types. Due to erosion, the offshoal to shoal cycle set is only present in the sections FI, NG and the hinterland of DH.

Interpretation: The transgressive hemi-cycle is interpreted as a sea-level rise with the MFI marked by bioturbated mudstones. The dominating regressive hemi-cycle shows a shallowing-upward trend associated with an increase of water energy, sorting and the deposition of oolitic grainstones with high-angle cross-bedding.

Offshoal to Foreshoal Cycle Set Motif The offshoal to foreshoal cycle set is the most common one in the Sulaiy Formation. It can be found in both, the transgressive and regressive part of the composite sequence. There is a signiﬁcant difference in the appearance and it can be subdivided into two subtypes.

Subtype 1: Within the Transgressive Part of the Composite Sequence Description: Stacks of up to 4 cycles form the cycle set with an average thickness of 8–10 m (Figure 34). This cycle set can be observed in all studied sections of the Sulaiy Formation. Subtype 1 is present in the transgressive part of the composite sequence, which divides the Sulaiy Formation into two parts. It can be recognized by amalgamated tempestite beds. Bioturbation is present but

OFFSHOAL TO SHOAL CYCLE SET Outcrop Dunham Texture Thickness (m)

BGR P WM LFA Cycle Cycle Set 12

SCS 6 12 10 cm 5

3 Figure 33: Outcrop appearance and simplified 2 sedimentological log of 1 offshoal to shoal cycle set from Section FI. 0

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has only a minor effect in terms of destratiﬁcation. Another difference is the occurrence of thin (5– 10 cm), but high water-energy event sheets (e.g. bioclast-rich rudstones or pack-to-grainstones).

Interpretation: The transgressive part of the cycle set is characterized by tempestites and can be interpreted as a sea-level rise. The occurrence of mudstones and bioturbated wackestones is interpreted as the MFI. A shallowing-upward trend can be observed in the dominating regressive part of the cycle set with a rise of water energy and increase of grain size associated with the deposition of tempestites.

Subtype 2: Within the Regressive Part of the Composite Sequence Description: The offshoal to foreshoal cycle set that is typical for the regressive part of the composite sequence is formed by usually 3 cycles (Figure 35). Similar to Subtype 1, it is also formed by tempestites but the appearance in ﬁeld sections is different. The amalgamated tempestite beds show intensive bioturbation, which partly results in destratiﬁcation leading to a more nodular appearance.

OFFSHOAL TO FORESHOAL CYCLE SET Outcrop Dunham Texture Thickness (m)

BGR P WM LFA Cycle Cycle Set 8

30 cm 5

SCS 4 6

20 cm 0

LFA Offshoal Foreshoal Shoal Figure 34 Transition zone Shoal margin Figure 33 Key Bioclasts Regressive hemi-cycle Peloids Transgressive hemi-cycle Ooids Erosive bases Corals Bioturbation Gastropods Cross-bedding

Figure 34: Outcrop appearance and simplified sedimentological log of offshoal to foreshoal cycle set (subtype 1) from Section DH.

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OFFSHOAL TO FORESHOAL CYCLE SET Outcrop Dunham Texture Thickness (m)

BGR P WM LFA Cycle Cycle Set 10

15 cm 7

SCS 5 10 30 cm 4

Figure 35: Outcrop appearance 2 and simplified sedimentological log of offshoal to foreshoal 1 cycle set (subtype 2) from 20 cm Section DH. 0

Interpretation: The transgressive part of the cycle set is dominated by destratiﬁed tempestites and is interpreted as a sea-level rise. Bioturbated mudstones and bioturbated wackestones mark the MFI. A shallowing-upward trend is present in the dominating regressive part of the cycle set indicated by bioturbated tempestites with minor destratiﬁcation.

Shoal Margin to Offshoal Cycle Set Motif Description: The shoal margin to offshoal cycle set usually consists of 2 cycles and has a typical thickness of 8 m (Figure 36). The transgressive part of the cycle set is characterized by the presence of oolitic grainstones with thin mudstone units on their tops. The regressive part of the cycle set is formed by tempestites, which are represented by oolitic pack-to-grainstones and bioclast-rich packstones and wackestones.

Interpretation: The transgressive part of the cycle set is interpreted as a sea-level rise associated with the creation of accommodation space, which results in the deposition of oolitic-peloidal grainstones. The MFI is marked by mudstones and wackestones, which can be interpreted as distal tempestites. A rise of water energy associated with increased grain size led to the deposition of more proximal tempestites during the regressive part of the cycle set.

Lower and Upper Sulaiy Sequences

The sequence shown in Enclosure I is a composite of sections DH and FI (after correlation). The typical oolitic-peloidal grainstones, which are characteristic for the top of the Sulaiy Formation, are not preserved at the Dahal Hit type locality. The Lower Sulaiy Sequence has a thickness of at least 135 m, composed of 12 cycle sets (SCS 1 to SCS 12). The lower sequence boundary of the Lower Sulaiy Sequence, the Sulaiy SB, is positioned at 101.0 m at the Dahal Hit type locality (Figure 4), and starts with the ﬁrst evenly-bedded limestones above the breccia from the Upper Jurassic Hith Formation. The transgressive part of the Lower Sulaiy Sequence consists at its base of bedded tempestites. Towards the MFI biostromes can be observed, as well as a constant increase in bioturbation and a decline in component/grain size. The MFI is represented by intensive bioturbated mudstones. The MFI of the Lower Sulaiy Sequence contains Lower Berriasian MFS K10 at 39.8 m.

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SHOAL MARGIN TO OFFSHOAL CYCLE SET Outcrop Dunham Texture Thickness (m)

BGR P WM LFA Cycle Cycle Set 8

SCS 4 2

3 30 cm

50 cm 0 LFA

Offshoal Foreshoal Figure 35 Figure 36 Transition zone Shoal margin Key Bioclasts Regressive hemi-cycle Peloids Transgressive hemi-cycle Ooids Erosive bases Corals Bioturbation

Figure 36: Outcrop appearance and simplified sedimentological log of shoal margin to offshoal cycle set from Section DH.

The lower part of the regressive part of the Lower Sulaiy Sequence is marked by nodular, partly destratiﬁed and bioturbated tempestites. In the upper part, the tempestites are composed of coarser material interpreted as deposition in a higher-energy, more proximal setting. Imbrication of up to 3–5 cm large clasts can be observed. The uppermost part is represented by an oolitic-peloidal shoal complex that can be observed in sections NG, FI, SI and the hinterland of DH. The shoal complex is insufﬁciently sampled for regional correlation and it may represent the lower part of a younger Upper Sulaiy Sequence (see below section titled “Correlation”).

Anatomies of Cycle Sets

The transgressive hemi-cycle is illustrated by Sulaiy Cycle Set 4 (SCS 4, Enclosure I) from sections DH, KW and AH. In Section DH, a higher amount of oolitic grainstones and little bioturbation is present. This can be related to deposition in a shallower-water environment compared to the sections KW and AH. These sections have consistently less ooids and more bioturbation, which leads to the slightly more nodular appearance of the bedding. It can be interpreted as deposition in a more distal setting compared to Section DH.

Within the MFI, Sulaiy Cycle Set 7 (SCS 7) shows an asymmetrical pattern, which is dominated by the transgressive part of the cycle set (Enclosure I). A cycle pinch-out can be observed and is

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highlighted in pink. The pinch out of the cycle reﬂects the proximal-distal trend from DH to AH, as sedimentation rates decline with increasing water depth.

Sulaiy Cycle Set 11 (SCS 11) shows an asymmetrical pattern, which is dominated by the regressive part of the cycle set (Enclosure I). SCS 11 in Section AH is thicker, which is probably related to a more distal position and therefore greater available accommodation space. SCS 11 shows a lateral facies change as biostromal boundstones occur only in sections DH and KW. These biostromes contain fossil assemblages that suggest a more proximal setting in a shallower and higher-energy environment.

CORRELATION

Correlations based on the observed cyclicity are the key to assemble all the studied sections into a sequence-stratigraphic framework (Aigner, 1985; Aigner and Schauer, 1998; Homewood et al., 2000). Cycle-sets were chosen to correlate the studied sections (Traverse A–A', Enclosure II). The aim of 2-D correlations is to recognize the geometry and facies distribution of the original stratigraphic framework prior to compaction, dissolution or tectonic overprint (Kerans and Tinker, 1997). The maximum ﬂooding surface has been chosen as datum.

The natural escarpment of the Sulaiy Formation is NW–orientated and represents in general the paleo-strike direction (Traverse B–B', Enclosure II). This is in accordance with the paleofacies map from Ziegler (2001). Six cycle sets (SCS 6–11) can be correlated between sections DH to FI, a distance of 75 km, showing no major facies changes and a "layer-cake"-like appearance. The interpretation also includes the major facies types that are not exposed in all sections, like the Hith Formation anhydrites, the contact breccia from Section DH and furthermore shoal and shoal-margin facies that are only exposed in sections NG, FI, SI and HL 1 to HL 4.

As a transgression marks the beginning of the Sulaiy Formation, the flat relief of the Hith anhydrites was flooded leading to proximal tempestite deposits. Oolitic grainstones occur as well, but are not sufficiently thick to be considered as shoal or shoal-margin facies, but rather they can be interpreted as separate sheets. This succession is followed by tempestites with a decreasing grain size towards the MFI and increasing bioturbation. Below the MFI, biostromes occur in all the studied sections. The MFI is mud-dominated and appears as a recessive unit in the outcrop. The regressive part of the Sulaiy Sequence consists in large parts of bioturbated tempestites. Bioclastic rudstones and smaller biostromes indicate the transition into grain-dominated shoal margin and shoal facies.

To obtain information about geometries and facies changes it is important to create a cross- section oriented in a paleo-dip direction. A correlation between sections NG and AH would represent an orientation in the overall dip direction over a distance of 22 km. However, due to the outcrop conditions and a missing overlap no correlation between sections NG and AH could be established. As an alternative sections DH, KW and AH were chosen because they are oriented in an approximate dip direction (Traverse C–C', Enclosure II). Seven cycle sets can be correlated (SCS 4–10). No significant lateral facies changes can be observed between sections DH and KW as they are only 1.5 km apart. In comparison to Section AH, significant differences occur in SCS 4, 5 and 6. While these cycle sets contain dm-thick pack-, grain- and rudstones in sections DH and KW, Section AH is dominated by wacke- and packstones. In general, Section AH shows smaller grain sizes, no grainstones, only very few thin rudstones and few high-energy event deposits compared to sections DH and KW. This observation leads to the assumption that Section AH was deposited in a more distal environment. This interpretation indicates a facies change in the lower section (SCS 2–3). Proximal tempestites, marked in yellow, disappear towards Section AH and grade into finer wacke- and packstones. It is observed that the proportion of facies types (more distal) associated with the transition increases towards Section AH within the transgressive part of the Lower Sulaiy Sequence.

Detailed correlations of the shoal interval (SCS 13 and above) is more difﬁcult. This is caused by observations of grainstones in this uppermost part of the Sulaiy Formation to be restricted to

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the sections HL, NG, FI and its vertical succession SI. Detailed facies correlations should not be based on this sparse information since the observed shoal facies might simply reﬂect less regional shallow-water sandy highs caused by landscape variations. Alternatively, these cycle sets may represent the lower part of the Upper Sulaiy Sequence. High-resolution correlation attempts are therefore affected by major uncertainties. The overall observation of the existence of high-energy, shallow-water facies in the uppermost Sulaiy Formation remains unaffected.

CONCLUSIONS

Our analysis of the outcrops of the Upper Tithonian–Lower Berriasian Sulaiy Formation in central Saudi Arabia indicated that this formation contains 10 lithofacies types (LFT). They are grouped into lithofacies associations (LFA) forming a carbonate ramp depositional system. The most abundant facies types are associated with a foreshoal setting. Three facies types that may contain reservoir properties are: (1) oolitic cross-bedded grainstones (LFT 9) with moldic and inter-particle porosity; (2) biostromal boundstones (LFT4) with moldic porosity; and (3) bioclast-rich packstones and pack-to-grainstones (LFT6) with inter-particle porosity. The facies distribution is controlled by the geometry of a shallow-marine carbonate ramp.

At Dahal Hit, we documented the transition between the Sulaiy Formation and underlying Tithonian Hith Formation. This is the only locality where the transition is exposed and we identiﬁed 3 lithofacies types in the Hith Formation. We suggest that the lowermost part of the Sulaiy Formation at Dahal Hit was deposited at the same time as the Manifa reservoir in eastern Arabia as part of a regional Late Tithonian transgression containing maximum ﬂooding surface MFS J110 (147 Ma).

Three orders of cycle hierarchy were identiﬁed: x Cycles: offshoal to transition zone, offshoal to foreshoal, transition zone to shoal margin and foreshoal to shoal margin ranging from 2–5 m in thickness. x Cycle sets (Sulaiy Cycle Sets = SCS): offshoal to shoal cycle set, offshoal to foreshoal cycle set and shoal margin to offshoal cycle set ranging from 8–12 m in thickness. x Sequences: a transgressive-regressive Lower Sulaiy Sequence containing Lower Berriasian MFS K10, and possibly the lower part of an Upper Sulaiy Sequence.

The cycles can be correlated where the studied sections are in close vicinity (< km). Cycle sets can be correlated between the studied sections at distances of several kilometers. Lateral facies changes between sections DH, KW and AH indicate a deepening trend in a dip direction towards the east. Biostromal boundstones occur in SCS 7 below the MFI (MFS K10) and are therefore a useful marker for correlation purposes. SCS 12–15 are difﬁcult to correlate; they can only be found as a complete succession in Section NG, whereas sections FI and HL 1–4 only show partial exposures.

ACKNOWLEDGEMENTS

The authors gratefully thank GIZ International Services/Dornier Consulting in Riyad for their help and support to make the ﬁeld work in Saudi Arabia possible, especially with logistics, technical equipment and their geological experience and recommendations. We also thankfully acknowledge Wintershall for their support with this study. Per Jeisecke (University of Tübingen) is thanked for thin section preparation and the whole Sedimentary Geology Research Group (University of Tübingen) for technical discussion and ideas for this paper. Access to WellCAD was kindly provided by ALT (Luxemburg). Two anonymous referees are thanked for their important comments that have signiﬁcantly improved the manuscript. GeoArabia Editor, Yves-Michel Le Nindre, is thanked for contributing his vast geological knowledge, as well as that of Denis Vaslet and Patrick Andreieff, and for accepting the invitation by the other authors to be a coauthor. We also thank Wyn Hughes for helpful discussion of the Sulaiy-Hith transition. GeoArabia’s Editor-in- Chief, Moujahed Al-Husseini, and Assistant Editor, Kathy Breining, are thanked for editing and proof-reading the manuscript, and working with Production Co-manager, Arnold Egdane, who designed the paper for press. We much appreciate the huge efforts of the outstanding GeoArabia team, and in particular that of Moujahed Al-Husseini to bring this paper into its present shape.

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ABOUT THE AUTHORS

Philipp Wolpert studied Geology at the University of Tuebingen (Germany) and at the University de los Andes (Venezuela), with focus on Sedimentology. He received his Diploma in 2010 about the Lower Cretaceous Sulaiy Formation in Saudi Arabia. After graduation he joined Fronterra Integrated Geosciences in Aberdeen, Scotland, where he worked two years intensively with borehole images and well logs on conventional and unconventional reservoir studies. In 2013 he started to work for Shell P&T in Rijswijk, the Netherlands, and now founded his own company where he works as an independent consultant. Philipp is also a member of EAGE, PESGB, AAPG and an instructor at EAGE’s geology bootcamp. [email protected]

Martin Bartenbach studied Geology at the University of Karlsruhe and at the University of Tuebingen (Germany). His Diploma Thesis (2008) was about facies analysis and 3-D modeling of Upper Jurassic carbonates and its resource- and reservoir geology implications in the Blaubeuren area in SW Germany. In his PhD Thesis, in collaboration with Wintershall Holding GmbH, he developed a systematic, multi-scale workﬂow for carbonate reservoir characterisation based on the Lower Cretaceous Sulaiy carbonates of the Middle East. In 2013 Martin joined Statoil ASA where he is currently working as a Senior Reservoir Geologist. [email protected]

Michael-Peter Suess (Peter) studied Geology at the University of Bonn and Clausthal-Zellerfeld (Germany), with focus on Applied Geophysics and Structural Geology. He received his Diploma in 1992 with a thesis about the Blue Road Geotraverse, a crustal transect in Fennscandia. After graduation Peter continued at the University of Bonn in the Sedimentology group and received his PhD on the sequence- stratigraphic development of the Ruhr Basin (Germany) in 1996. After two more years as Post-Doc in Bonn, he worked for two years as Research Fellow and Associated Researcher at the Structural Geology group at Harvard (USA). In 2000 he joined the University of Tuebingen (Germany) as Assistant Professor and received the degree of Privatdozent (PD) in 2005. Since 2006, Peter works for Wintershall, Germany’s largest E&P company in Kassel. He currently heads an applied integrated subsurface R&D team. [email protected]; [email protected]

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Randolf Rausch studied Geology and Hydrogeology at the University of Stuttgart and the University of Tuebingen (Germany), where he received his PhD in 1982. After working for a consulting company he joined the Geological Survey of Baden- Württemberg, Germany, where he was involved in many consulting and research projects. From 2003 to 2004 he headed the project “Groundwater Resources Management” at the Ministry of Water & Irrigation in Jordan, commissioned by the German Federal Institute for Geosciences and Natural Resources (BGR). From 2004 to 2014 he was Technical Director for the project “Water Resources Studies“ in the Kingdom of Saudi Arabia, carried out by Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH for the Ministry of Water & Electricity. The project’s main focus was the investigation of the groundwater resources on the Arabian Platform. Since 2015 Randolf is a Professor at Technische Universität Darmstadt, Germany. He has developed many computer programs related to groundwater flow and solute transport modeling, and has authored 5 books on the subject. His current field of research is the hydrogeology of arid environments. In 1990 Randolf was awarded the “German University Software-Prize” from the Federal Minister of Research for the best simulation program in the field of engineering science. He received the “Abraham-Gottlob Werner Medal” in 2009 from the German Society of Geosciences for his achievements in groundwater sciences and was awarded the “Medal of Economics” in 2013 from the state of Baden-Württemberg for outstanding achievements in the field of economy. [email protected]

Thomas Aigner studied Geology and Paleontology at the Universities of Stuttgart, Tuebingen/Germany and Reading/UK. For his PhD dissertation on storm depositional systems (1985) he worked at the Senckenberg-Institute of Marine Geology in Wilhelmshaven (Germany) and spent one year at the University of Miami in Florida (USA). He then became an Exploration Geologist at Shell Research in Rijswijk/ Holland and Houston/Texas focussing on basin analysis and modelling (1985–1990). Since 1991 Tom has been a Professor and Head of the Sedimentary Geology Group at the University of Tuebingen. In 1996 he was a “European Distinguished Lecturer” for the AAPG. His current projects focus is on sequence stratigraphy and reservoir characterisation/ modelling in outcrop and subsurface. [email protected]

Yves-Michel Le Nindre has been contributing to Middle East geology since 1979, particularly in Saudi Arabia. After his PhD in marine Biology and Sedimentology in 1971, he received his Doctorate of Sciences from the University of Paris (France) in 1987 with a dissertation on the ‘Sedimentation and geodynamics of Central Arabia from the Permian to the Cretaceous’. Yves-Michel joined the Bureau de Recherches Géologiques et Minières (BRGM) in 1973. He was involved in many research and consulting projects in France and abroad (Saudi Arabia, Oman, Kuwait, U.A.E. Jordan, Iran, Tunisia, Morocco, Bolivia, Ethiopia, India, Russia), for sedimentary basin analysis and modeling, especially in hydrogeology. As a Sedimentologist, Yves-Michel worked in France on present-day littoral integrated management. Since 2000, he has been involved in international projects for CO2 storage, working with EU state members and CSLF countries (Russia, China, Saudi Arabia) as Expert or Project Manager and directed two PhD theses. Since July 2012, Yves-Michel is retired from BRGM, notwithstanding still continuing a scientiﬁc and consulting activity in his preferred domains of expertise. He is a member of the EAGE, ASF and of the GeoArabia Editorial Board. Yves-Michel is so far author or co-author of 63 publications related to Saudi Arabia. [email protected]

Manuscript submitted August 19, 2014

Revised April 19, 2015

Accepted May 2, 2015

122

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