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Palaeogeography, Palaeoclimatology, Palaeoecology 252 (2007) 270 – 280 www.elsevier.com/locate/palaeo

Facies architecture of an isolated carbonate platform in the Hawasina Basin: The Late Triassic Jebel Kawr of Oman Michaela Bernecker Institute of Paleontology, University Erlangen, Loewenichstrasse 28, D-91054 Erlangen, Germany Accepted 30 November 2006

Abstract In the oceanic realm of the southern Tethys, carbonate production of isolated platforms ceased after the end-Permian mass extinction and did not recover until the Late Triassic. The Misfah Formation (MF) at Jebel Kawr in the Oman Mountains is interpreted as a relic of such an isolated Late Triassic platform of the Hawasina Ocean, a part of the Neo-Tethys. Correlation of three sections at Jebel Kawr points to a sequence architecture with four third-order sequences (MF1–MF4). The maximum flooding surface (mfs) of MF3 can be correlated to the attached Arabian platform. The shallow-water carbonates of Jebel Kawr comprise a platform rim reef facies and bedded inner-platform facies characterized by stacked high-frequency cycles with subtidal to intertidal carbonate sequences. The depositional profile of this Late Triassic isolated platform evolved during Carnian and Norian time from a low-relief carbonate bank to a high-relief platform rimmed by reefs. The onset of the carbonate sedimentation is characterized by an initial phase with volcaniclastic interruptions, followed by a carbonate bank stage with a shallow subtidal to peritidal interior and marginal oolite shoals. In the Norian vertical accumulation caused an increase of the platform height and developed a relief along the margins that progressively increased through the aggrading reef stage. The possibility that a reef rim existed and was later removed by erosion is suggested by the Sint reef and olistoliths of similar reef limestones in the surrounding areas. © 2007 Elsevier B.V. All rights reserved. Keywords: Late Triassic; Isolated platform; Reef development; Neo-Tethys; Oman Mountains

1. Introduction The recovery period of marine ecosystems following the Permian mass extinctions was extraordinarily prolonged. For metazoan reefs it extended from the end of Lopingian to early Middle Triassic (Flügel, 2002; Flügel and Kiessling, 2002; Weidlich, 2002a,b). The impact of extinctions on biodiversity has been analysed in detail (Erwin et al., 2002) but the influence on carbonate

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platforms have rarely been reviewed (e.g., South China, Lehrmann et al., 2001, 2003). On the Arabian plate, tropical carbonate production collapsed after the end-Permian mass extinction and was replaced by microbialites and sea-floor cements during the earliest Triassic. Tropical shallow-water carbonate production resumed in the Middle Triassic (Weidlich and Bernecker, 2007). Absence of shallow-water limestone from the Hawasina basin suggests that carbonate production of isolated platforms ceased here for about 30 million years and Neo-Tethyan isolated platforms did not recover before the Late Triassic.

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The aim of this paper is to analyse the facies architecture of such an isolated Late Triassic carbonate platform from the southern Tethys (Hawasina Ocean) based on integrated facies analyses with biostratigraphic and sequence stratigraphic data. The main objectives of this study are (i) to describe the reef and platform deposits preserved as relics in the Hawasina nappes of the Oman Mountains, (ii) to document changes in architectural style of the Kawr platform, and (iii) to reconstruct the evolution of this isolated platform in the Neo-Tethys.

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2. Geological setting and study area Triassic shelf deposits crop out along the eastern rim of the Arabian Shield. Tectonic nappes of the Oman Mountains containing relics of Middle-Permian to LateTriassic carbonate platforms include the Arabian plate (Saiq and Mahil Formations) and Hawasina basin (NeoTethys: Bai'id and Misfah Formations). According to palinspastic reconstructions, the isolated Permian Ba'id and Triassic Kawr platforms of the Hawasina basin were situated north to northeast of Arabian plate in Neo-Tethys

Fig. 1. (1) Location map of the southeastern part of the Arabian Peninsula. (2) Simplified geological map of the Oman Mountains. (3) Location of measured sections at Jebel Kawr, the isolated platform of the Neo-Tethys. Section Sint (23°09′50ʺN, 57°03′10ʺE), section Ala (23°05′30ʺN, 57°07′30ʺ), and section Amqah (23°04′30ʺN, 57°07′30ʺE).

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(Béchennec et al., 1990). Biostratigraphic and sequence stratigraphic correlation between the attached Arabian platform and the isolated platforms allowed to reconstruct

the large scale stratigraphic architecture and regional sealevel curve (Weidlich and Bernecker, 2003). The nappes of the Hawasina complex (Fig. 1) document the evolution

Fig. 2. Stratigraphic logs of Kawr platform with lithofacies, biota and sequence stratigraphy of the Misfah Formation. Section Sint (1) represents the rim of the isolated Kawr platform, section Ala (2) and Amqah (3) the inner platform.

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of Neo-Tethys. Relics of Middle and Late Triassic shallow-water carbonates have been preserved as breccias or enormous mega-blocks attaining a size of several kilometers are exposed at Jibal Kawr, Misht, Misfah, and Ghul (Kawr Group: Misfah Formation: Beurrier et al., 1986; Minoux and Janjou, 1986). The Subayb Formation of Jebel Misfah comprises a succession of mafic volcanics and dark nodular limestones dated as Ladinian and Carnian (Pillevuit, 1993; Pillevuit et al., 1997). It is the precursor of the Misfah Formation and is regarded as the lowermost unit of this Neo-Tethyan isolated carbonate platform. The Misfah Formation, exposed at Jibal Misfah, Misht, and Kawr (Beurrier et al., 1986, ‘Oman Exotics’ sensu Glennie et al., 1974) consists of 700–900 m bedded shallow-water platform carbonates of Late Triassic age. The termination of shallow-water platform sedimentation at Jebel Kawr is indicated by platform drowning during the Lower Jurassic (Fatah Formation, section Ma'Wa; Pillevuit, 1993). Misfah Formation exposures at Jebel Misfah, Misht, and Kawr (Fig. 1) are 700–900 m thick and located in the Western Oman Mountains in the area SW of Jebel Akhdar (Beurrier et al., 1986; Minoux and Janjou, 1986). Three sections (Fig. 2) from Jebel Kawr were studied and cover positions of the Misfah Formation extending from Carnian to Rhaetian. The size of the Kawr platform is about 15 × 20 km (300 km2). Section Sint (Fig. 3) represents the rim of the platform, section Ala (Fig. 4) and Amqah the platform interior. 3. Facies description and depositional environments The base of the Misfah Formation at Jebel Kawr represents the onset of shallow-water carbonate deposition in the Carnian. Volcaniclastic extraclasts prove perturbations caused by volcanic activity. The upper part of the Misfah Formation at Jebel Kawr consists of shallow-water carbonates up to 800 m thick and represents the development of the Kawr platform with reefs during the Norian/Rhaetian. 3.1. Facies types of the base of the Misfah Formation at Jebel Kawr Bedded wackestone facies with peloids and bioclasts (porostromates, dasycladacean algae and foraminifera) dominate in the interior, oolithic grainstones at the margin (Fig. 2(1), base of section Sint). 3.1.1. Mudstone, locally bioturbated This light grey monotonous facies type forms beds 20 to 50 cm thick. The mudstone contains only a few

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components (pellets, bioclasts, intraclasts and locally porostromate algae). Distinct mottling due to bioturbation can be observed in some beds. 3.1.2. Bioclastic and peloidal wackestone to grainstone Banks of this grey facies type are 20 to 40 cm thick and contain varying amounts of bioclasts and peloids. The microflora and fauna, consisting of dasycladacean algae (Clypeina besici, Poikiloporella duplicata) and foraminifera (e.g. Aulotortus praegaschei), are age diagnostic for the Carnian. 3.1.3. Volcanoclastic wackestone The reddish to yellow medium thick-bedded (ca. 30 cm) volcanoclastic wackestone is located in the basal part of the sequence. The mudstone and wackestone contain elongated millimeter-size volcanic extraclasts. These extraclasts are indicators of ongoing volcanic eruptions in the Hawasina basin, which may have hampered carbonate production on the isolated platform at the beginning of its development. 3.1.4. Oolitic grainstone The light grey thick-bedded medium-sorted oolitic grainstone occurs in the sequence prior to reef growth. The marine ooids with a partly micritized tangential microfabric probably formed in high-energy shoals. 3.1.5. Crinoid floatstone and rudstone This grey massive to thick-bedded bioclastic floatstone and rudstone is composed largely of crinoid ossicles. The fabric varies from loose and disperse packing to grain-support fabric. The crinoid stems are disarticulated, but the ossicles show no signs of significant lateral transportation or abrasion. Some crinoids exhibit syntaxial cement rims. Only a Carnian-to-Norian age can be assigned to this facies types, as fossils of biostratigraphic relevance are absent. 3.2. Facies types of the upper part of the Misfah Formation at Jebel Kawr The main part of the isolated Kawr platform includes reef facies (section Sint, 59–113 m), inferred to represent the platform rim as well as bedded inner platform facies (Fig. 2), section Ala and Amqah. 3.2.1. Coral bafflestone with solenoporacean algae and/or chaetetid sponges The light grey massive bafflestone consists of dendroid coral colonies together with large solenoporacean algae (diameter 2–5 cm) forming bioherms up to 20 m thick.

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Fig. 3. (1) Platform-rim facies at the northern escarpment of Jebel Kawr. Section Sint with sequences MF2 to 4. Reef-to-platform transition during MF4 indicates strong platform progradation. (2) Biostratigraphic important foraminifer Triassina hantkeni, Rhaetian, and (3) dasycladacean alga Poikiloporella duplicata, Carnian. Fauna of the Kawr reef. (4) Solenoporacean algae, (5) scleractinian corals: Gablonzeria and (6) Retiophyllia (scale bars 1 mm in 2 and 3; 1 cm in 4, 2 cm in 5 and 6).

Common coral taxa are Retiophyllia norica, Cyclophyllia cyclica, and Margarosmilia charlyana. The sediment between the colonies is a wackestone yielding bioclasts and small foraminifera. The reef organisms indicate a Norian age. Corals (R. norica) and chaetetid sponges (Blastochaetetes dolomiticus, Bauneia annosciai) also occur as isolated colonies in biostromal beds 30 to 50 cm thick. 3.2.2. Coral and sponge framestone The grey massive framestone contain cerioid and thamnasteroid coral colonies as dominant reef builders. Common corals are Gablonzeria profunda, Pamiroseris rectilamellosa, and Seriastrea multiphylla. Sponges such as Cryptocoelia siziliana, Cryptocoelia tenuparietalis, and Weltheria sp. are less abundant and build clusters within the reef framework. This framestone also includes encrusting organisms like Spongiostromata crusts, the microproblematicum Microtubus communis,

foraminifera (e.g. Alpinophragmium perforatum), and small sponges (Uvanella norica). These framestones yield a fauna of Norian age dated and described by Bernecker (1996, 2005). 3.2.3. Coral floatstone and rudstone The grey floatstone and rudstone up to 2 m thick contain angular to subangular reef derived bioclasts up to 10 cm in diameter. This facies occurs above the reef facies and represents erosion at the end of reef development. 3.2.4. Bioturbated mudstone and wackestone The beds of this light grey mudstone and wackestone with dark grey dots are 40 to 70 cm thick. Bioturbation is recorded by cylindrical tubes about 1 cm in diameter that differ in color and fabric from the surrounding mudstone. Burrow fill are wackestone containing recrystallized bioclasts, peloids, and fecal pellets of decapod crustaceans (Favreina).

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Fig. 4. (1) Inner-platform facies at the eastern escarpment of Jebel Kawr-section Ala. The breccia in front is a younger debris flow deposit. (2 and 3) Bedded platform facies with sequences of MF2 and MF3. (4) Subtidal facies with megalodontid bivalves (lens cap is 5.5 cm) and (5) intertidal facies with microbialites.

3.2.5. Bioclastic wackestone (and rare grainstone) The light grey wackestone has a varying bed thickness between 20 and 40 cm. The components are recrystallized bioclasts and peloids. Bioturbation is rare, but it is obvious from the grainstone texture of the burrow fills. 3.2.6. Megalodont floatstone The grey well-bedded floatstone has bed thicknesses between 80 and 150 cm. Bivalves (e.g. Megalodon, Neomegalodon) up to 60 cm in diameter occur in clusters or beds. The largest forms are common in the Norian. The sediment between the megalodont clams and other large bivalves is a mudstone or wackestone. Most of the abundant molds are of articulated bivalves in life position. Megalodontids lived on shallow muddy substrates in low-energy lagoonal environments. 3.2.7. Molluscan floatstone The dark grey molluscan floatstone forms beds 40 to 60 cm thick beds that show local horizontal orientation of

the shells. Single beds consist of several layers which differ with respect to packing density and shape of the shells. 3.2.8. Laminated bindstone The grey laminated bindstone forms beds varying from 5 to 20 cm thick. This facies is ‘loferite’ (Fischer, 1964) and consists microbialites locally with fenestral fabric. The microbialites are typically associated with fenestrae and desiccation cracks, and pointing to a suprato intertidal environment. The laminated sediment is partly reworked at the top of the bank. 3.2.9. Irregular unconformity surfaces Red or green argillaceous micrite, carbonate silt, or marl contain millimeter- to centimeter sized intraclasts of microbialites and scattered fenestral pores with geopetal fills. Redcoated grains and aggregates with Fe-oxide staining and cement are probably of pedogenic origin. The inner platform facies is characterized by subtidal megalodont-rich floatstone, shallow-subtidal to intertidal

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fenestral mudstone, and laminated stromatolite. 5 to 20 m cycles occur in inner platform sections with internal facies successions similar to the Lofer cyclothems (e.g. Fischer, 1964, 1975; Goldhammer et al., 1990; Satterley, 1996; Enos and Samankassou, 1998). 4. Sequence architecture of the isolated platform The sequence stratigraphic interpretation follows classic concepts (e.g., Haq et al., 1988; Van Wagoner et al., 1988; Vail et al., 1991; Handford and Loucks, 1993) with emphasis on carbonate systems. Long-term transgressive–regressive cycles developed over periods of approximately 5–20 my and represent second-order supersequences. They are composed of stacked composite third-order sequences with a duration of 0.5–5 my (Sarg et al., 1999). High frequency cycles (4th order and higher) were observed but not correlated in detail. The sequence stratigraphic interpretation of the carbonate platforms is based on the (1) investigation of key sections with bed-bybed analysis and description of representative samples/ thin-sections with respect to facies and depositional environment, (2) determination of depositional sequences using photomosaics, (3) identification of sequence boundaries and maximum flooding surfaces (mfs) for correlation within the Arabian platform supersequences (Sharland et al., 2001). The maximum flooding surfaces provide a framework of timelines, which allow the disparate lithostratigraphic units across the plate to be placed within a unifying chronostratigraphic framework. Maximum flooding surfaces, or better maximum flooding zones (Lehrmann and Goldhammer, 1999), were recognized either by a change from monotonous, light grey carbonates to thin-bedded, dark-colored limestones or (more frequently) by diverse, fully marine faunas (e.g., the occurrence of corals, bivalves and aulotortid foraminifera within a thick sequence of monotonous carbonates). Permian and Triassic carbonate platforms of the Arabian Peninsula and Neo-Tethys are characterized by distinctive second order supersequences (P1–4 and Tr1–4, duration 5–20 million years) and composite third order sequences (duration 0.5–5 my) (Weidlich and Bernecker, 2003). Triassic supersequence Tr4 can be correlated from the attached Arabian platform to the isolated Kawr platform. Composite sequences of the Misfah Formation (designated MF) are represented at Jebel Kawr. 4.1. Facies and variation of transgressive systems tract (TST) Patterns and lithologies of TST facies at the platform margin can be best described using the data of the Sint

section (Fig. 3). Composite sequence MF1 is not exposed near Sint, but dominance of stromatolites of the inner platform facies (see sections Ala and Amqah, Fig. 4 (5)) suggests moderate lateral depth gradients during this phase. During MF2-TST, the inner-platform facies of Jebel Kawr passes laterally from subtidal megalodont floatstone near the rim into bioturbated bioclastic wackestone, bivalve floatstone, and rare grainstone with dasycladacean algae or oncoids. MF3-TST, dominated by crinoid floatand rudstone, differs in its biotic composition significantly from MF2-TST. Crinoid ossicles are increasingly disarticulated toward the top, but are not transported. These crinoid-rich sediments correlate with a dark coral/chaetetid floatstone of the platform interior. This coral biostrome facies yields chaetetids (B. dolomiticus) and corals (R. norica) and is unique in its composition throughout the isolated Kawr platform. This facies represents the only occurrence of coral/chaetetid level-bottom communities on the inner platform and is conspicuously dark and bituminous. It is the maximum flooding surface of the platform and can be correlated with a similar zone of the Mahil Formation of the Gondwana shelf (Weidlich and Bernecker, 2003). MF4-TST is characterized by fully marine, bedded platform-interior facies with megalodonts (Fig. 4(4)). As in composite sequence MF1, a differentiation between TST and HST would be arbitrary, owing to the absence of significant facies changes, and is therefore not practiced. Tempestites are a ubiquitous phenomenon of Jebel Kawr platform and are striking in the prograding platform facies above the coral reef (section Sint). 4.2. Facies variation of highstand systems tract (HST) and platform drowning The inner platform facies of the highstand systems tracts is dominated by bedded Lofer cyclothems in which sub- to intertidal algal stromatolite as well as mudstone are more common than subtidal megalodont-rich floatstone. Subaerial exposure horizons are common. The greatest facies variation of the isolated Kawr platform occurs at the platform rim (Fig. 3). The HST commenced with coral reef facies evolving from boundstone to floatstone and finally to lithoclastic rudstone due to decreasing water depth and increasing turbulence. Composite sequence MF3 is terminated by prograding platform facies with heterogeneous composition including abundant bivalve floatstones, oolites, and wacke/packstone. Several subaerial exposure horizons point to short-lived, punctuated sea-level lowstands as a result of decreasing accommodation space.

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The youngest platform sediments have been eroded and platform termination remains therefore enigmatic. Matrix-rich debris-flow deposits with onlapping geometries at section Ala (Fig. 4(1)) point either to a lowstand wedge with long-lasting platform exposure at the end of Triassic or to a rifting event related to extension of the Neo-Tethys (e.g., Glennie et al., 1974; Robertson and Searle, 1990; Loosveld et al., 1996). The youngest carbonates of the isolated Kawr platform are thinbedded deep-water limestones, which record platform drowning subsequent to erosion. 4.3. Interpretation Correlation of three measured sections of the Misfah Formation from Jebel Kawr points to a platform architecture with composite sequences MF1–MF4 (Fig. 5). Basal sequence MF1 is exposed only at Wadi Amqah and lacks biostratigraphic microfossils. The occurrence of P. duplicata (Fig. 3(3)), C. besici (both calcareous algae), and A. praegaschei (foraminifer) at the base of sequence MF2 at Sint section points to a Carnian age. Sequence MF4 at the top of Wadi Ala yields Triassina hantkeni (foraminifer) (Fig. 3(2)) indicative of a Rhaetian age. The termination of Jebel Kawr shallowwater platform sedimentation is indicated by platform drowning during the Lower Jurassic. A debris flow deposit at section Ala is separated from the bedded facies by normal faults (Fig. 4(1)). It is obviously younger than the bedded facies of the Misfah Formation because the breccia contains clasts of the Misfah Formation and older than post-drowning sediments, which are not represented in the debris flows. Summarizing these data, a Carnian-toRhaetian age for platform development is indicated by my biostratigraphic determinations. A Ladinian-to-EarlyJurassic age has been postulated in the literature (Pillevuit, 1993; Baud et al., 2001) and cannot be ruled out. All sequences MF1 to MF4 are characterized by variations of internal architecture. Differentiation of TST and HST units is only possible near the platform rim (section Sint) due to a pronounced facies differentiation in ooid shoal, reef, and bedded platform facies. In addition, only MF3 can be correlated on a platform-wide scale, owing to a significant facies changes in other sequences (Weidlich and Bernecker, 2003). The other TSTs and HSTs platform sequences are indistinct and, therefore, their differentiation would be too arbitrary. An apparent change in the architectural style from a low-relief bank to a platform rimmed by reefs took place during MF2. Until MF2-TST, the depositional system corresponds to a low-relief bank with indistinct lateral gradients. Facies differentiation is obvious during MF2-

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HST comprising ooid shoals at the platform rim and megalodont mudstones within the platform. At the end of MF3-HST, coral reefs aggraded to near sea level, but show no evidence for subaerial exposure. When the reefs approached sea level, percentages of floatstone and rudstone increased and platform aggradation becomes dominant. Reef development therefore reflects shallowing with changes in biotic composition and preservation of framework. The debris flow deposit at section Ala may indicate either subaerial exposure of the isolated platform prior to drowning or drowning of the platform related to rifting and opening of the Neo-Tethys. Drowning of carbonate platform may be associated with debris flows (Zempolich, 1993) and it is known from the southeast Bahamas that platform drowning may be caused by downfaulting and platform collapse (Mullins et al., 1991). At present, subaerial exposure as control mechanism is favored. A karst erosion surface, where the cavities are filled by a breccia with a red-brown matrix (e.g., Bernecker et al., 1999), is described by Beurrier et al. (1986) from the top of the Misfah Formation at Jebel Ghul. Subaerial exposure is also supported by evidence for long-lasting exposure of the Arabian platform during the Rhaetian (Weidlich and Bernecker, 2003). 5. Conclusion and discussion Jebel Kawr of Oman is interpreted as an isolated Late Triassic platform, composed of four third-order sequences (MF1–MF4). The maximum flooding surface (mfs) of MF3 can be correlated to the attached Arabic platform. The shallow-water carbonates of Jebel Kawr belong to the Misfah Formation and comprise platform-rim as well as bedded inner-platform facies. Although platform-rim facies has been found only in the section near Sint, a margin with varying amounts of reef and cross-bedded oolite is preserved analogous to other Triassic isolated platforms known from the Dolomites (e.g., Gaetani et al., 1981; Bosellini, 1984; Blendinger, 1986; Blendinger and Blendinger, 1989; Harris, 1993, 1994). The inner platform is characterized by stacked high-frequency cycles with subtidal to intertidal carbonate sequences (e.g., Fischer, 1964; Goldhammer et al., 1990; Enos and Samankassou, 1998; Haas, 2004). Two stages of development are postulated for Jebel Kawr (Fig. 5) reflecting changes in the depositional profile of this Late Triassic isolated platform from low relief to high relief. Carbonate deposition commenced on a bank based on the following observations: (1) The lack of depositional relief is indicated by the absence of talus breccias close to the margin of the bank. (2) Oolites and

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Fig. 5. Model for the isolated platform development in the Neo-Tethys: depositional architecture, sea-level reconstruction, and stratigraphic log correlation for Jebel Kawr, Oman Mountains.

crinoid floatstone, interpreted as rim of the bank, lack the capability to create a high-relief slope. (3) Published studies show that new carbonate depositional systems

generally evolve from a low-relief bank to a rimmed platform (Cenozoic: Bahama Bank, Betzler et al., 1999; Triassic: Great Bank of Guizhou, Lehrmann et al., 1998;

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Late Paleozoic: Capitan Reef Complex, southwestern US, Saller et al., 1999). Shallow-water sedimentation at Jebel Kawr started with a phase of carbonate production interrupted by volcanic episodes. The bank consisted of a shallow subtidal to peritidal interior and oolite shoals at the margin. The change in architectural style to a rimmed platform occurred during Carnian and Norian as evidenced by the presence of a reef at the margin. In the Norian vertical accumulation caused an increase of the platform height and developed a relief along the margins that progressively increased through the aggrading reef stage. The possibility that a reef rim existed and was later removed by erosion is suggested by the (1) Sint reef and (2) breccia intervals with clasts of reef limestone and (3) olistoliths of similar reef limestones in the surrounding areas. The reef clasts contain a diverse fauna of scleractinian corals, sponges, and several different encrusting organisms forming a boundstone fabric. These boundstone clasts could have been derived from diverse platform margin reefs that were partly eroded from the margin and preserved only in the Sint reef. Acknowledgements This study was funded by the German Research Foundation (Fl 42/62) and supported by Erik Flügel, Erlangen University, Germany. The help of the Director General of Minerals, Dr. Hilal Al-Azri, for several visits to the Sultanate of Oman is gratefully acknowledged. I thank my colleague Oliver Weidlich (Royal Holloway University, UK) for joint fieldwork and helpful discussions. Paul Enos and Mark Harris are gratefully acknowledged for comments and suggestions that substantially improved the manuscript. References Baud, A., Béchennec, F., Cordey, F., Krystyn, L., Le Métour, J., Marcoux, J., Maury, R., Richoz, S., 2001. Permo-Triassic deposits: from the platform to the basin and seamounts. International Conference Geology of Oman, Excursion A01, p. 56. Béchennec, F., Le Metour, J., Rabu, D., Bourdillon-De-Grissac, C., De Wever, P., Beurrier, M., Villey, M., 1990. The Hawasina Nappes: stratigraphy, palaeogeography and structural evolution of a fragment of the south-Tethyan passive continental margin. In: Robertson, A.H.F., Searle, M.P., Ries, A.C. (Eds.), The Geology and Tectonics of the Oman. Geological Society London Spec. Pub., vol. 49, pp. 213–223. Bernecker, M., 1996. Upper Triassic reefs of the Oman Mountains: data from the South Tethyan margin. Facies 34, 41–76. Bernecker, M., 2005. Late Triassic reefs from the Northwest and South Tethys: distribution, setting, and biotic composition. Facies 51, 457–468. Bernecker, M., Weidlich, O., Flügel, E., 1999. Response of Triassic reef coral communities to sea-level fluctuations, storms and sedimen-

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