Mesozoic Hamrat Duru Group, Hawasina Complex, Oman

GeoArabia, Vol. 9, No. 2, 2004 Gulf Petrolink, Bahrain

Stratigraphic architecture of the northern Oman continental margin - Mesozoic Hamrat Duru Group, Hawasina complex, Oman

Ingo Blechschmidt, Paulian Dumitrica, Albert Ma�er, Leopold Krystyn and Tjerk Peters

ABSTRACT

The Triassic to Late Cretaceous deep-marine sediments of the Hamrat Duru Group, Oman Mountains, represent a subunit of the Hawasina nappe-complex which was deposited in a deep marine basin. During the Late Cretaceous SSW-directed obduction of the Semail Ophiolite, the Hawasina complex was emplaced onto the autochthonous cover of the Arabian basement, while the original configuration of the basin was destroyed.

New lithostratigraphic results and high-resolution radiolarian and conodont biostratigraphy lead to a revised stratigraphic scheme of the Hamrat Duru Group which conforms with the standard stratigraphical nomenclature. The Hamrat Duru Group is divided into six formations: (1) The Early Triassic (Olenekian) to Late Triassic (Upper Norian) Zulla Formation (Limestone and Shale Member, Sandstone and Shale Member, Radiolarian Chert Member and Halobia Limestone Member); (2) The Late Triassic (late Norian to Rhaetian) Al Ayn Formation; (3) The Early Jurassic (late Pliensbachian) to Middle Jurassic (early Callovian) Guwayza Formation (Tawi Sadh Member and Oolitic Limestone Member); (4) Middle Jurassic (Callovian) to Late Cretaceous (Cenomanian?) Sid’r Formation (Lower Member, Upper Member); (5) Late Cretaceous (Cenomanian? to Santonian?) Nayid Formation; and (6) Late Jurassic (early Callovian) to Early (Late?) Cretaceous Wahrah Formation. Most of the lithostratigraphic units (formations and members) show isochronous boundaries between the different outcrop areas.

The stratigraphic architecture of the Hamrat Duru Group megasequence is controlled by alternating siliciclastic and carbonate sedimentation possibly related to the second-order sea-level variations. The sediments accumulated on the continental rise of the Arabian margin mostly by submarine sediment-gravity flows and hemipelagic to pelagic rainout. A close relationship of the evolution of the Arabian Platform and the adjoining slope and basinal environments is evident. Changes in carbonate supply, oceanographic circulation and/or variations in silica productivity resulted in two distinct phases of radiolarian sedimentation. The first phase corresponds to the Triassic late Anisian-early Norian time interval; the second started in the Early Jurassic late Pliensbachian and lasted, with some interruptions, up to the Late Cretaceous Coniacian. The litho- and biostratigraphic similarities between the Mesozoic Hamrat Duru Basin of the northern/ central Oman Mountains and the Mesozoic Batain Basin of northeastern Oman are seen as related to Neo-Tethys-wide palaeoceanographic changes and suggest a strong interdependence of the two basins with the evolution of the Arabian Platform.

INTRODUCTION AND PREVIOUS WORK

Regional Geotectonic Framework

During the last decades of geological research it has been generally accepted that the allochthonous cover of the northeastern Arabian Plate originated from the southern margin of the Neo-Tethys Ocean (Figure 1a). The Late Permian and Mesozoic Hawasina sediments were deposited in the Hawasina Basin which consisted of at least two sub-basins (Figure 1b), before being emplaced in a SSW direction onto the autochthonous cover of the Arabian Platform, coeval with the late Coniacian to Campanian (84-80 Ma) obduction of the Semail Ophiolite (Allemann and Peters, 1972; Glennie

Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/9/2/81/4564638/blechschmidt.pdf by guest on 30 September 2021 Blechschmidt et al. Stratigraphic architecture of Hamrat Duru Group, Oman

IRANIAN TERRANES Palaeo-Tethys Ocean

Neo-Tethys Ocean 20

New Passive Margin

AFGHAN TURKEY B TERRANES Misfar Platform TIBET 0 Broad carbonate Early Jurassic evaporite shelf rifting in eastern Hamrat Duru Basin Mediterranean A Batain Basin ARABIAN PLATE

AFRICAN INDIA-PAKISTAN PLATE PLATE

A Arabian Platform

Continental Slope Hawasina Basin Hamrat Duru Basin Al Aridh Misfah Trough? Platform

Umar Basin Spreading Ridge B

Figure 1: (a) Opening of the Neo-Tethys, northern extension and passive margin post-ri� thermal subsidence (Middle Permian to Early Jurassic, 255-182 Ma; modified a�er Sharland et al., 2001). Note the positions of the Hamrat Duru and the Batain Basin. (b) Mesozoic pre-emplacement Hawasina Basin configuration (modified a�er Cooper, 1990; Le Métour et al., 1995; and Pillevuit et al., 1997).

Figure 2 (facing page): Geological map of the central and eastern Oman Mountains (simplified a�er Glennie et al., 1974; Pillevuit et al., 1997) showing the main outcrop areas and studied sections. Key to sections: 1 - Wadi Zulla (=Wadi Dil), 2 - Qabil, 3 - Qusayd-Shulayshil, 4 - Al Jil, 5 - Al Ayn, 6 - Tawi Shu’ah, 7 - Tawi Shannah, 8 - Wadi Musallah, 9 - Wadi Yail, 10 - Wadi Saal, 11 - Wadi Sid’r, 12 - Wadi Sid’r North, 13 - Wadi Nayid, 14 - Al Dhaby, 15 - Mudaybi, 16 - Kathmah, 17 - Firq, 18 - Wadi Mu’aydin, 19 - Zukayt, 20 - Al Sawad, 21 - Jabal Safra, 22 - Kadrah Bani Dafa’a, 23 - Al Khashbah, 24 - Al Hammah Range, 25 - Dawwah, 26 - Wadi Bani Khalid, and 27 - Khabbah. Structural section across the central Oman Mountains and tectono-stratigraphic organisation of the present-day Oman Mountains are also shown (modified a�er Glennie et al., 1973, 1974).

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et al., 1973; Béchennec, 1987; Bernoulli et al., 1990; Cooper, 1988). The Hamrat Duru sedimentary rocks represent a base of slope and abyssal plain sedimentary facies of a distinct sub-basin of the Hawasina Basin along the Arabian Platform. The sedimentation in the Hamrat Duru Basin was mostly characterised by submarine sediment-gravity flows such as turbidity currents and debris flows, as well as hemipelagic rain out and radiolarian productivity (Glennie et al., 1974; Murris, 1981; Cooper, 1986).

The first comprehensive study of the Oman Mountains was presented by Glennie et al. (1973, 1974) who recognised five main structural units (Figure 2). From bo�om to top, these are:

1. Autochthonous A (folded Proterozoic to Palaeozoic rocks) and B (Permian to Cretaceous carbonates and deeper marine sediments), representing the lowermost outcropping tectonic units, 2. Sumeini Nappes, characterized by Neo-Tethyan slope deposits of Permian to Cretaceous age, 3. Hawasina Nappes, subdivided into several groups comprising Permian to Cretaceous basinal sediments, 4. Semail Ophiolite, sequence of Cretaceous oceanic crust, and 5. Neoautochthonous, sedimentary platform sequence ranging in age from the Late Cretaceous to Miocene, which unconformably overlies all older units.

Gulf of Oman

0 N 25 Hawasina Window 1 Muscat km

Jabal Wahrah Saih Hatat 4 Wadi Al Ayn 2 5 6 7 Ibri

3 Jabal Akhdar

17 20 8 18 Nizwa 27 19 Hamrat Ad Duru R. 22 9 A 13 14 21 15 10 Ibra 12 Jabal 23 11 Hammah Jabal 25 16 Safra 24 26 Al Hammah R.

1 - 27 Studied sections

Gulf of Oman Southwest Northeast Muscat UAE J. AKHDAR A HAMRAT AD DURU B

0 25 SAUDI ARABIA km Neoautochthonous OMAN Semail Ophiolite

Arabian Sea Hawasina Nappes

Sumeini Nappes

N 0 150 B km Autoch- thonous A

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Previous Stratigraphic Work and Palinspastic Reconstructions

Glennie et al. (1973, 1974) interpreted the Hawasina Complex as a stack of nappes with sediments deposited in an oceanic basin along the northern Arabian passive continental margin. Mainly based on lithostratigraphic criteria, they subdivided the Hawasina sediments into the Hamrat Duru Group and into several formations such as Halfa Formation, Haliw Formation, Wahrah Formation, Al Ayn Formation, Ibra Formation, Al Aridh Formation, and the Oman Exotics. Glennie’s et al. (1974) first palinspastic reconstruction of the Hawasina Basin assumed Permian to Late Triassic-Early Jurassic ri�ing and simple in-sequence thrusting during emplacement. Later workers (see below) correlated the facies between the tectonic units to set up regional stratigraphic schemes, grouping similar sediment types of similar age throughout the area as a whole.

Béchennec (1987) synthesised the stratigraphic work of the BRGM (Bureau de Recherches Géologiques et Minières) which was carried out during regional mapping of the Central Oman Mountains. The geological studies carried out between 1984 and 1993 by the BRGM resulted in the publication of geological maps at different scales of the entire Oman territory (e.g. Béchennec et al., 1993; Le Métour et al., 1995; Michel, 1993). New palaeontological data allowed more accurate dating of many stratigraphic sequences (Béchennec et al., 1993; Béchennec et al., 1990; De Wever et al., 1988). Most of the formations established by Glennie et al. (1974) were abandoned or were redefined by the BRGM geologists (Figure 3). This has led to considerable confusion with respect to the Hamrat Duru lithostratigraphy, especially as Béchennec and co-workers modified their stratigraphic scheme repeatedly as their mapping project progressed (Figure 3). The problems related to this approach are discussed in Robertson et al. (1990). According to the BRGM, the evolution of the South Tethyan Oman continental margin started in the Early to Middle Permian with a phase of extension. This ri�ing led to the formation of the Hamrat Duru Basin, separating the Arabian Platform in the south from the Baid Platform in the north. During the Middle Triassic, desintegration of the Baid Platform caused the development of new palaeogeographic realms, i.e. the Al Aridh Trough, the Misfah Platform and the Umar Basin (Figure 1b; Baud et al., 1993; Béchennec et al., 1990; Béchennec et al., 1988; Pillevuit, 1993; Pillevuit et al., 1997). The palinspastic reconstruction of Béchennec et al. (1988) is, as that of Glennie et al. (1974), based on the assumption of simple in-sequence thrusting during emplacement.

Cooper (1987) carried out the first comprehensive sedimentological study of the deep-water sediments of the Hamrat Duru Group, from the Dibba Zone (Musandam) in the northwest to the Semail Gap in the southeast. He extended the stratigraphic scheme of Glennie et al. (1974) by correlating sediments between different tectonic units and grouped sediments of similar facies and age throughout the area as a whole (Figure 3). Cooper (1987) further subdivided the Triassic Zulla Formation into four informal units (Figure 3). Cooper’s reconstruction of the Mesozoic Hawasina Basin was supported by numerous measured sections and led him to differentiate two individual deep-water basins (the shale-rich Al Ayn Basin and the Duru Basin) separated by a submarine high (Al Ayn Basin ridge; Cooper, 1987, 1990).

Bernoulli and Weissert (1987) and Bernoulli et al. (1990) dated the Radiolarian Chert Member of the Triassic Zulla Formation using radiolarians and also discussed the age of the other members of the formation. Previously, the Zulla Formation was regarded as a long-ranging very distal unit consisting mainly of chert with shale interbeds (Glennie et al., 1974); whereas it is now seen as only the Triassic part of a relatively proximal succession. Bernoulli and Weissert (1987) and Bernoulli et al. (1990) also analysed the Triassic palaeoenvironmental changes in the source areas and discussed basin-wide palaeoceanic fluctuations. Finally, the finding that the sequence of thrusting is complex (including in-sequence and out-of-sequence thrusting) led to a new palinspastic reconstruction of the Hawasina Basin which represented a significant improvement of Glennie et al.’s (1973, 1974) reconstructions (Bernoulli and Weissert, 1987; Bernoulli et al., 1990).

Recent studies in the Batain Plain, eastern Oman Mountains revealed that latest Carboniferous to Early Permian break-up of Gondwana led to the formation of two separate basins, the Batain Basin and the younger Hawasina Basin (Figure 1a, Immenhauser et al., 2000).

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Béchennec et al. Béchennec (1987) (1992, 1993) Béchennec Wyns et al. (1992) Glennie et al. Cooper Bernoulli BRGM et al. (1990) Stage (1974) (1987, 1990) et al. (1990) (1984) 1:250,000

BRGM (1984-1993) geological maps This study Stage

Series Hamrat 1:100,000 System 1:1,000.000 Duru Gp. geological maps geological maps Maastrichtian M Campanian C Santonian S Riyamah Mbr Late Coniacian (Muti Fm) C Turonian Nayid Fm Nayid Fm T Nayid Fm Nayid Fm Cenomanian (Kna) C Nayid Si 2 C ? ACEOUS Albian A Fm ion ? Aptian Si2 Upper A Nayid Si2 Upper Mbr Mbr Barremian Formation B CRET

Early Hauterivian H

Valanginian Sid'r Si1 Si1 V

Wahrah Formation Wahrah (JKsi)

Sid'r Fm Sid'r Sid'r Formation Sid'r Fm Formation Sid'r

Berriasian Radiolarian B Formation Wahrah Formation Lower Mbr Wahrah Format Tithonian Lower Member Chert T Mbr

Kimmeridgian WaC) (WaL, K Sid'r Formation Sid'r Late Guwayza V. Mudst. Oxfordian Formation Halfa O Fm Mbr Callovian Guwayza Guwayza Fm C Fm (Jgw) Bathonian Oolitic Limestone B ? Member Bajocian Formation Wahrah B

Middle Member

Aalenian Limestone A Tawi Sadh Toarcian Member T JURASSIC Pliensbachian Mb2 Upper Mbr P Mb (Jmb ) Sinemurian 2 2 Sabt Fm Sabt S Guwayza Fm Sabt

Early Al Ayn Sandstone Sandstone Guwayza Fm Hettangian Guwayza Formation ? H Formation Rhaetian R

Matbat Formation Matbat Al Ayn Fm Halobia Mb Mb Member 1 1

Unit 4 Fm Matbat Al Ayn Formation Ayn Al Norian Formation Matbat N Sandstone Limestone Halobia Limestone Mbr Late Lower Member Carnian C (TRmb 1 ) Unit 3 Radiolarian Radiolarian Chert Ladinian Chert Member L

Aj2 Aj2 Member

Middle Anisian Sandstone & Shale A Zulla Formation Zulla TRIASSIC

Zulla Fm Zulla Member Unit 2 Formation Zulla Olenekian Sandstones Limestone & Shale Mbr O & Shales

1 Zulla Formation Zulla Early Induan (PTRaj ) ? I (PTRaj b ) Unit 1 Aj1

Tatarian Turbiditic sh T

Al Jil Formation Jil Al Al Jil Formation Jil Al Al Jil Formation Jil Al Aj1 Member (Paj ) Calcarenites v Late Kazanian ? & Shales ? (Paj ) K PERM. Figure 3: Previous stratigraphic nomenclatures for the Hamrat Duru Group. The scheme to the right is based on the new (bio-) stratigraphic results as documented in this paper.

Rationale of this Study

As laid out before, the different stratigraphic concepts proposed led to considerable confusion regarding the Hamrat Duru stratigraphy (Figure 3). The situation is even more complicated because the same name for a formal stratigraphic unit (e.g. Sid’r and Nayid formations) commonly refers to different lithologies and/or time periods. Moreover, the present biostratigraphy ofthe Hamrat Duru succession, based largely on reworked platform and slope-derived biogenic material remains inaccurate and incomplete. Therefore, it is necessary to improve the time control and the understanding of the stratigraphic architecture of the Hamrat Duru Group in order to gain a be�er understanding of the evolution of the Hawasina Basin in time and space.

In this paper we present a stratigraphic architecture that gives evidence for the development of a passive continental margin from the ri�ing phase up to the closure of the Neo-Tethys Ocean. We provide new lithostratigraphic data, radiolarian and conodont biostratigraphies in order to: (1) develop a coherent and comprehensive stratigraphic scheme for the Hamra Duru Group; (2) determine the basinwide time-lithofacies relationships; and (3) discuss the tectono-stratigraphic evolution of the Hamrat Duru Basin from the Triassic to the Late Cretaceous.

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METHODS

This study is based on 27 measured sections, located in the Oman Mountains between the Hawasina Window and the Wadi Bani Khalid (Figure 2). Locations of the individual sections are given in Universal Transverse Mercator (UTM) grid data using the World Geodetic System (WGS) 84. Sections were measured to a resolution of about 10 cm and their total length is 5,800 m. Grain size was estimated directly in the field, either with a ruler for coarse to very coarse-grained sediments, or using a grain-size comparison chart for sand-sized sediments. Bed thickness is described using the descriptive classification a�er Ingram (1954) in Bla� et al. (1980). Thin sections were studied with standard petrographic techniques.

The classification of sandstones used is that presented by Pe�ĳohn et al. (1987). The scheme used for the limestones divides them on the basis of grain size a�er Tucker (1991). The classification of hybrid sandstones which contain a non-clastic component is also based on Tucker (1991). Palaeocurrent observations were made on flute casts and ripple/dune cross-bedding and corrected, where necessary, for plunge and folding (Blechschmidt, 2002).

In this paper simplified logs are shown that emphasize lithology, grain size and schematic bed thickness (Legend, Figure 4). These logs include important biostratigraphic data (B: general rock samples, BR: radiolarian samples, BC: conodont samples) and basic lithologic informations. Because of lateral facies changes and due to some incomplete sections, most of the formations are documented by at least two overlapping sections providing in total a complete succession and/or local variations between these two sections. The sections described in the text are numbered 1 through 27 and section numbers are shown in bold type (e.g. Figure 2: 1).

The biostratigraphy is mainly based on radiolarians extracted from about 700 samples of siliceous Triassic to Late Cretaceous sedimentary rocks. The radiolarian sample numbers together with the determined ages are shown on the logs. However, due to limited space and high species diversity usually only the assemblages of bo�om and top samples of each member/formation are listed in the Appendix. Extracting the radiolarians from siliceous limestones and cherts was possible with the etching technique developed by Dumitrica (1970) and first described by Pessagno and Newport (1972). Conodont data were obtained from 20 limestone samples and supplement the Triassic radiolarian ages. Those samples shown on the logs or discussed in the text are listed in the Appendix. Benthic foraminifers were determined by R. Martini and L. Zanine�i in thin sections and were helpful in dating Middle Jurassic to Early Cretaceous carbonates. These new biostratigraphic data allow an accurate chronostratigraphic dating of the lithostratigraphic units and their regional correlation between the different outcrop areas of the Hamrat Duru Group.

The new stratigraphic scheme presented here follows the rules of the North American Commission on Stratigraphic Nomenclature (Nomenclature, 1983) and the guidelines for stratigraphic classification, terminology and procedure defined by Hedberg (1976), Holland et al. (1978) and Salvador (1994).

REVISED STRATIGRAPHY OF THE HAMRAT DURU GROUP

The Late Permian to Late Cretaceous Hamrat Duru Group is named a�er the Hamrat ad Duru Range in the southwestern foreland of the Oman Mountains and was first introduced by Haremboure and Horstink (1967). The main exposure belts of the Hamrat Duru Group are in the southern mountains (Hamrat ad Duru Range, Jabal Hammah, Jabal Safra, Jabal Wahrah, Hubat antiform, Al Hammah Range and Birkat al Mawz area) and in the central and northern Oman Mountains (Wadi Al Ayn, Hawasina Window) (Figure 2). Throughout the fore-mentioned regions, no sedimentary record older than Early Triassic is known. Deep-water sediments and volcanics of Permian age are scarce and occur in tectonically isolated outcrop areas. They are strongly deformed and no complete succession from the Permian into the Triassic of the Hamrat Duru Group was reported until now. Therefore the relation of the Permian successions to the Hamrat Duru Group is controversial. Glennie et al. (1974) and Béchennec et al. (1990) suggested that the Permian lies at the base of the Hamrat Duru Group; whereas its base is the Triassic Zulla Formation according to Cooper (1987). The Permian is not further discussed in this paper.

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Halobia 100 150 200 50 m Beyrichi M. Zulla, Al Ayn, Guwayza, Sid’r, Nayid, Sid’r, Guwayza, Ayn, Al Zulla, green shale calcilutite, Calcarenite, calcilutite silicified marl, radiolarian chert, Green shaleand green shale stone and quartz sand- Green/brownish shale ribbon chert, radiolarian Red andgreen calcarenite shale and radiolarians, bivalves and taining pelagi Calcilutite con- calcilutite grey/yellowish (>70%), Green shale marl green shale, sublitharenite, Quartz arenite, Thrust fault zone fault Thrust Thick (>1m) Thick c 8 7

Zulla Formation Fm Stratigraphic architecture ofHamratDuruGroup, Oman Limestone and Sandstone and Halobia Shale Member Shale Member Radiolarian Chert Member L. Mbr Mbr M./L. Carnian E. Olenekian L.Carnian/ BR908/909 BR903/907 BR925/930 BR916/917 BR891/898 BR899/902 E. Ladinian BR910/915 BR918/923 L. Ladinian L. Carnian/ M. Carnian Large boulders Large Shale, cherty shale cherty Shale, Silt- and sandston and Silt- Limestone Chert nodule Chert E. Carnian L. Carnian WADI BANIKHALID(26) Sample L. Anisian E. Norian E. Norian BC1137 UTM 706511/2496352 BR924 Norian B1010 Clay Sand Pebble and Grain Size e Wahrah 100 50 m Halobia Silicified limestone Silicified Manganese Not exposed Not Radiolarian chert Radiolarian Beyrichi M. . The Wahrah The . calcilutite shale, silicified radiolarian chert Green andred calcilutite larian-bearing shale, radio- Red andgreen marl shale and lutite, green Yellowish calci bivalves taining pelagi Calcilutite con- c - Blechschmidt et al. Stratigraphic architecture of Hamrat Duru Group, Oman

Formation of Glennie et al. (1974) has been included within the Hamrat Duru Group by Bernoulli and Weissert (1987) a�er its recognition as a synonym of the Guwayza Sandstone (Figure 3). Based on a careful revision of the Guwayza Sandstone, this unit is now divided in two parts of which the lower one is revived as Al Ayn Sandstone in a new sense. The upper part is introduced as the new Tawi Sadh Member of the Guwayza Formation proper. The Al Jil and Matbat formations sensu BRGM (Béchennec, 1988) are considered as synonyms of well established members of the Zulla Formation and their use cannot be further supported.

Zulla Formation

Type section The stratotype sequence was established by Glennie et al. (1974) in Wadi Zulla (=Wadi Dil) in the Hawasina Window (Figure 2: 1) and later slightly modified by Cooper (1987) at the same locality.

Lithologically identical sections were measured by Bernoulli et al. (1990) in the Wadi Al Ayn area, some 50 km to the southeast (Figure 2). This is also the type region of the Al Jil and Matbat formations of Béchennec (1987) which are regarded fully, or partly, as synonyms of the Zulla Formation. Cooper (1987) and Bernoulli et al. (1990) recognised four lithostratigraphic units in the Zulla Formation. This subdivision is retained, but the basal ‘Turbiditic Calcarenites and Shales’ member of Bernoulli et al. (1990) is replaced by the ‘Limestone and Shale Member’ to avoid the genetic connotation (Figure 3).

The Zulla Formation in the type area is tightly folded and shows a low-grade metamorphic overprint that destroyed a major part of the microfaunal content, except conodonts. In the Wadi Al Ayn area (Figure 2) the formation is only slightly deformed and has produced stratigraphically relevant radiolarian faunas. The sections in this area (Figure 2: 4 and 5) are well exposed and show a complete succession of all lithostratigraphic units. They are thus used for the litho- and biostratigraphic subdivision of the Zulla Formation as described below, and the section in Wadi Al Ayn (Figure 4: 5, and Figure 5a) is proposed as a hypostratotype.

Boundaries The Zulla Formation is thrust over the Sumeini Group in the Hawasina Window and over the duplexes of the Hamrat Duru Group in the Wadi Al Ayn area (Cooper, 1987). Therefore, its base is always tectonic, whereas the upper boundary is undisturbed and transitional to the overlying Al Ayn Formation.

Age According to previous studies (Cooper, 1987; Bernoulli et al., 1990; Béchennec, 1987; Béchennec et al., 1990, 1993) and new data shown in Figure 4, the Zulla Formation extends from the Early Triassic (Olenekian) to the Late Triassic (late Norian; Figure 3). There is no indication for a Permian age of the base of the Zulla Formation in the investigated areas.

Synonymy The four members of the Zulla Formation described in this paper are identical to the Zulla I to IV units of Cooper (1987) and Bernoulli et al. (1990) (Figure 3). The Limestone and Shale Member, the Sandstone and Shale Member, and the Radiolarian Chert Member correspond to the Al Jil Formation of Béchennec et al. (1988). The Halobia Limestone Member represents the Lower Member of the

Matbat Formation (Mb1) of Béchennec et al. (1988).

Zulla Formation - Limestone and Shale Member

Lithology and sedimentary features The measured thickness is about 25 m (Figure 4: 5) but the base of the unit is strongly deformed. The succession consists of partially calcareous grey-green shale with intercalations of 10-30 cm thick peloidal mudstone and calcarenite and thinly bedded platy calcilutite in the basal part. The rare calcarenite beds contain transported and redeposited shallow-water carbonate material (e.g. ooids, pellets).

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ca. 60m C b B A

A B

0 2 cm

Figure 5: Outcrop photographs of the Zulla Formation: (a) Overview of the Al Jil section showing the four members and the contact to the Al Ayn Formation: Limestone and Shale Member (only upper part exposed) (A), Sandstone and Shale Member (B), Radiolarian Chert Member (C), Halobia Limestone Member (D) and Al Ayn Formation (lower part) (E). Note the greenish colour of Radiolarian Chert Member. (b) Large-scale linguoid ripples in thinly-bedded calcarenite facies of the Limestone and Shale Member (arrow c. 40 cm), current from upper le� to lower right (Wadi Bani Khalid). (c) Sandstone and Shale Member (A): decimetre- to metre-bedded, fine- grained greenish quartz arenite and sublitharenite interbedded in a shale-dominated succession; Radiolarian Chert Member (B): decimetre-bedded, red radiolarian ribbon chert with interbedded siliceous shale (Wadi Al Ayn, person for scale). (d) Halobia Limestone Member: folded brown weathering calcilutite and calcarenite (A) with interbedded shale (B) (hammer for scale). Inset: top of limestone bed showing thin shelled pelagic bivalves of Halobia beyrichi Mojs. (Wadi Bani Khalid). The bivalve shells are generally aligned parallel to bedding.

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The sediments are characterised by: (1) normal-grading, parallel lamination and/or ripple cross- bedding mainly from large-scale linguoid ripples (calcarenites, Figure 5b); (2) non-graded massive to platy calcilutite; and (3) structureless massive to platy shale. Starved ripples are also common. Cross- bedding indicates transport of the sediment from south to north and from southwest to northeast (Blechschmidt, 2002).

Boundaries The base of the Limestone and Shale Member is always tectonic and characterised by thrusts and associated folding. The contact to the overlying Sandstone and Shale Member is gradational and is arbitrarily set to the first appearance of dolomitic layers and silty shale.

Age The conodont assemblages (Figure 2: 4 - Appendix: BC353, Figure 4: 5, BC769, BC355) reveal an early Olenekian (Smithian) to early Middle Triassic (late Olenekian-Anisian) age for the member.

Zulla Formation - Sandstone and Shale Member

Lithology and sedimentary features The lower part of the succession is dominated by shale and beige dolomitic calcilutite and marked by a fining- and thinning-upward trend. The upper part consists of thinly to thickly bedded, well-sorted silty to sandy greenish quartz arenite and sublitharenite interbedded in a shale-dominated succession (Figure 5c). The sandstone beds are composed mainly of quartz (up to 95%) and lesser amounts of feldspar and lithic grains (up to 25%). They generally show normal-grading followed by parallel lamination and topmost cross-bedding passing upwards into structureless shales. Towards the top of the member a slight thickening of beds can be observed. Flute casts and cross-bedding indicate transport of the sediment from southwest to northeast (Blechschmidt, 2002). This unit reaches a stratigraphic thickness of about 30 m (Figure 4: 5).

Boundaries The lower boundary of this member is set at the first appearance of prominent shale beds with rare dolomitic interlayers. The contact to the overlying Radiolarian Chert Member is also gradational and characterised by a shale-dominated level with rare intercalations of radiolarian chert and siltstone.

Age The age of the Sandstone and Shale Member is bracketed by the conodont data of the underlying Limestone and Shale Member and the radiolarian data of the overlying Radiolarian Chert Member and corresponds, accordingly, to the late Olenekian (early Spathian) to middle/late Anisian.

Zulla Formation - Radiolarian Chert Member

Lithology and sedimentary features This member consists of an approximately 50-70-m-thick sequence of thinly-bedded, red and/or green radiolarian ribbon chert with interbedded siliceous shale (Figure 5c). The upper part of the member is marked by an interval of brown weathering, fine-grained, redeposited calcarenite to calcilutite up to 3 m thick. The top of this member is dominated by green shale, green radiolarian chert and silicified marl.

The sediments are characterised by: (1) non-graded massive to platy radiolarian chert beds; or (2) radiolarian chert beds with graded radiolarian layers, parallel lamination and/or flaser bedding; and (3) platy, structureless intercalated shale. The chert beds can be laterally traced for several tens of metres before they wedge out. Some individual layers are characterised by chert nodules or lenses. The minor internal primary structures of the chert beds are sometimes destroyed by bioturbation (e.g. Chondrites and other unidentified ichnofossils).

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Boundaries The lower boundary was established at the level where the percentage of chert exceeds that of the shale and siltstone. The upper boundary is marked by the transition to the limestone and shale of the Halobia Limestone Member and it is set above the uppermost chert bed. Both lower and upper boundaries are gradational.

Age The radiolarian assemblages indicate a late Anisian (Illyrian) age for the base of the Radiolarian Chert Member and an early Norian (early Lacian) for its top. Since radiolarians from the stratotype are poorly preserved the age of this member is based on assemblages extracted from the hypostratotype (Figure 4: 5 and Appendix) and from other sections such as the one in Wadi Bani Khalid (Figure 4: 26 and Appendix), one of the best sections for radiolarian biostratigraphy in the study area. The oldest radiolarian assemblage of the hypostratotype (Figure 4: 5 - BR419, Appendix) contains a radiolarian assemblage indicative of the late Anisian (middle-late Illyrian) Tiborella florida subzone of Kozur (1995). The same subzone is indicated by this radiolarian assemblage in all the other sections proving that radiolarian productivity started practically simultaneously throughout the Hamrat Duru Basin.

The radiolarian assemblage from the top of the hypostratotype of the Radiolarian Chert Member (Figure 4: 5 – BR437-BR438, see Appendix) contains a fauna with Capnodoce spp., Capnuchosphaera tricornis De Wever, Capnuchosphaera spp., Corum spp., Mostlericyrtium sitepesiformis Tekin, Selenella triassica Tekin, Xiphotheca rugosa Bragin, and a few other species described by Tekin (1999) from the early Norian (E. abneptis conodont Zone) of Turkey. A much richer assemblage at the same stratigraphic level was found at the top of this member in the Wadi Bani Khalid section (Figure 4: 26 - BR929, Appendix). In both sections this radiolarian assemblage is at a few metres below the level with Halobia beyrichi Moj. (Figure 4: 5: B345, 26: B1010) indicative of the early Norian.

Between the late Anisian and the early Norian almost all radiolarian zones established in Europe (Kozur and Mostler, 1994) and Japan (Sugiyama, 1997) can be recognized in the succession of the Radiolarian Chert Member. A detailed radiolarian biozonation of the stratigraphic interval recorded in this member as well as a taxonomic study of the radiolarians will be presented separately.

Zulla Formation - Halobia Limestone Member

Lithology and sedimentary features The total stratigraphic thickness of the Halobia Limestone Member measured in the Wadi Al Ayn (Figure 4: 5) and Hawasina Window (Figure 2) is about 60 m thick. The lower part of the sequence is dominated by partially silicified grey-green shale, thinly-bedded radiolarian-bearing calcilutite and layers packed with filaments, thinly-shelled pelagic bivalves of the Halobia type (Figure 5d). The bivalve shells are generally aligned parallel to the bedding. The base of the Halobia Limestone Member contains both, in the Wadi Al Ayn outcrop area (Figure 4: 5) and in the Wadi Bani Khalid (Figure 4: 26), a marker horizon with Halobia beyrichi Mojsisovics (Figure 5d). Up-section, medium-bedded calcarenites consisting of redeposited platform material, such as ooids, echinoderm and mollusc fragments increase in abundance, associated with a higher input of siliciclastic detritus (quartz and feldspar grains and shale clasts). The o�en-folded, respectively tectonically truncated, upper part of this member consists of up to 20 m of shales alternating with calciturbidites and rare sand- and siltstones (Figure 4: 5 and 26). This interval is rarely well exposed and until now has been variously incorporated in the lower Guwayza Formation, the Al Ayn Formation or the lower Matbat Formation (Glennie et al., 1974; Béchennec, 1986; Figure 3). This is not consistent with our new data, which indicate a stratigraphic gap and the main depositional sequence boundary above and not below this interval.

The sediments are characterised by: (1) non-graded massive to platy calcilutite; (2) normally-graded, parallel laminated and/or ripple cross-bedded calcarenites; and (3) structureless shale. Cross-bedding indicates transport of the sediment from west to east and from southwest to northeast (Blechschmidt, 2002). The primary sedimentary structures in the basal part of the sequence are o�en disturbed by bioturbation (e.g., Chondrites, Ophiomorpha, Bergaueria, Imponoglyphus torquendus, Nereites, Thalassinoides, Halymenites, Helminthopsis, Archeozostera, A. Wetzel, wri�en communication, 2002).

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Boundaries The lower boundary of this member is gradational. The contact to the overlying Al Ayn Formation is drawn at the appearance of massive sandstone beds with no or only thin shale intercalations (Figure 4: 5).

Age Based on the age of the top of the Radiolarian Chert Member and on the conodonts and pelagic bivalves species, the Halobia Limestone Member is early to late Norian in age (sections in the Wadi Al Ayn area: Al Jil, Figure 2: 4 - Appendix: BC349, BC351; Al Ayn, Figure 4: 5 - B345 - Halobia beyrichi Mojsisovics, BC767; Tawi Shannah section, Figure 4: 7 - Appendix: BC347; and from Wadi Bani Khalid, Figure 3: 26 - B1010 - Halobia beyrichi Mojsisovics).

Regional variations The Zulla Formation in the Wadi Al Ayn and in the Hawasina Window shows no significant lateral variations in thickness and facies. Further to the southeast, in the Zukayt area (Figure 2: 19), carbonate beds increase in abundance and the Sandstone and Shale Member is devoid of sandstone beds. In the Wadi Bani Khalid outcrop area (Figure 2 and 4: 26), the succession shows a reduced thickness of both the Radiolarian Chert Member (c. 40 m) and the Halobia Limestone Member (c. 35 m). The sandstone facies of the Sandstone and Shale Member is absent once more and the member is dominated by shale with minor radiolarian-bearing calcilutite in the upper part.

Al Ayn Formation

Type section The type locality of the Al Ayn Formation is situated in Wadi Al Ayn close to the village of Tawi Shannah (Figure 2: 7). In this area of the central Oman Mountains this formation is well exposed, but very poor in relevant index fossils. The Wadi Saal area in the southern Hamrat Ad Duru Range (Figure 2: 10), in contrast, shows an almost complete succession with well exposed conglomerates containing stratigraphically relevant faunas of reworked sponges, corals and foraminifers. Therefore, the Wadi Saal section is proposed as a hypostratotype of the Al Ayn Formation.

Lithology and sedimentary features The Tawi Shannah section (Figure 6: 7, Figure 7a) shows one of the most complete successions of the Al Ayn Formation in the Wadi Al Ayn area. Its stratigraphic contact to the underlying Zulla Formation and the overlying Guwayza Formation is well exposed. The sequence consists of 140 m of thinly- to thickly-bedded quartz arenite and interbedded shale. At the type locality a 10 m thick transition interval with thinly-bedded limestone, cherty shale and siltstone is found between the Zulla and Al Ayn formations. This interval is overlain by a 30-m-thick alternation of greyish-green shale and siltstone with a pronounced coarsening- and thickening-upward trend grading into brown- weathered, decimetre- to metre-bedded, medium- to coarse-grained quartz arenites and interbedded shales comprising the middle part of the formation (c. 90 m). The uppermost c. 25 m of the formation show a general fining- and thinning-upward trend grading into a shale facies with subordinated thinly-bedded sandstone and siltstone.

The sediments of Al Ayn Formation are characterised by: (1) normally-graded, parallel laminated and/ or rippled sandstones with common convolute bedding (Figure 7a); and (2) interbedded structureless shales and laminated silty shales. In the middle part of the sequence, thickly-bedded, amalgamated beds are common. In the lower and upper parts of the succession thickening-upward small-scale cycles are well developed, whereas in the middle part fining-upward small-scale cycles are partially observed. Flute casts and current ripples indicate mainly north and east directed sediment supply.

A well-preserved ichnofauna including Palaeodictyon, Desmograpton, Desmograptus pamiricus, Circulichnus, Thalassinoides, Helminthopsis, Palaeophycus, Imponoglyphus, Glockerichnus, Protopalaeodiction, Nereites, Nereites labyrinthica, Rhabdoglyphus, Phycosyphon, Megagrapton can be observed at the base of many beds (A. Wetzel, wri�en communication, 2002).

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WADI SAAL (10) TAWI SHANNAH (7) UTM 489020/2524022 UTM 498805/2568647 UTM 490011/2523209 Grain Size Grain Size Pebble Pebble Sample Sand Sample Sand Fm Fm Mbr Mbr Clay Clay

BR131 150 White chert, E. Toarcian silicified

Ool. L. limestone, BR117 cherty marl Thickly-bedded L. Pliensba- grey ooid-dominated chian/ calcarenite, E. Toarcian Guwayza Formation

Guwayza green shale, thinly- Formation ?

bedded siltsone Tawi Sadh Mbr

? T. Sadh Mbr 200

100 Green shale and B320/2 thinly bedded silt- L. Norian/ and sandstone E. Raethian (quartz arenite) B317/2, 318/2 L. Norian/ Massive, green and E. Raethian white/brown quartz arenite, calcarena- B313/2 ceous sandstones, L. Norian/ calcirudite E. Raethian (sponges, corals) and shale 150

50 Al Ayn Formation

Massive, green and brownish quartz arenite, B309/2, 310/2 partially conglom- L. Norian/ eratic, red and E. Raethian green shale 100 B309 L. Norian/ Al Ayn Formation E. Raethian 0 m

Figure 6: Measured sections through the Al Ayn Formation: section Tawi Shannah (7) and section Wadi Saal (10) including the lower portions of Green shale and thinly bedded silt the Guwayza Formation and the upper portions and sandstone 50 m (quartz arenite) of the Zulla Formation. Note, samples B309 to B320 contain corals, sponge spiculae and ? foraminifera. See Figure 4 for key.

Thinly bedded calcilutite calca- BC347 renite cherty shale Member M. Norian and siltstone Zulla Formation Halobia Limestone

Boundaries In most of the studied areas, the lower part of the formation is tectonically truncated, except in the Hawasina Window and the Wadi Al Ayn area where the formation conformably overlies the Zulla Formation. The boundary to the overlying Guwayza Formation is marked by an abrupt change to a shale-dominated facies including poorly exposed silicified lime- and mudstone.

Age Due to the lack of index fossils, the age of the Al Ayn Formation in most of the outcrop areas can only be determined indirectly. Based on conodont data from the underlying top Zulla Formation and the radiolarian data from the overlying Tawi Sadh Member, a Latest Triassic (Rhaetian) age is assumed for the Al Ayn Formation. Common conglomerates in the middle and upper part of the succession in

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coarsening/thickening-upward fining/thinning-upward

ca. 90 m

B A

Oolitic Limestone Member ca. 220m

Tawi Sadh Member

Al Ayn Formation B

Figure 7: Outcrop photographs of the Al Ayn Formation and Guwayza Formation: (a) Al Ayn Formation: section Tawi Shannah showing coarsening- and thickening-upward trend from a shale-dominated lower part (A) into brown-weathered, decimetre- to metre-bedded alternation of quartz arenites and shale (B). Up-section, the formation shows a general fining- and thinning- upward trend grading into a shale-dominated facies with subordinate thinly-bedded sandstone and siltstone. Arrows mark symmetrical sequence. Inset: well developed base-cut-out Bouma

sequence (TBC(D)) (lens cap for scale). (b) Al Ayn Formation and Guwayza Formation (Wadi Saal): almost complete succession of the Guwayza Formation (Tawi Sadh Member and Oolitic Limestone Member). Note the three major sequences. Base of the Al Ayn Formation is tectonic. Inset: normally-graded, parallel laminated calcarenaceous sandstone (A), erosive channel, filled with bioclastic calcirudite consisting of reworked reef talus with abundant sponges and corals (B) (pen for scale).

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the Wadi Saal (Figure 6: 10) and Jabal Safra (Figure 2: 21) contain reworked reef talus with abundant sponges and corals (Figure 6: 10 - B309/2, B310/2, B313/2, B317/2, B318/2 and B320/2 - Disjectopora sp. and Spongiomorpha sp., M. Bernecker, wri�en communication, 2002, Figure 7b) and foraminifers such as Galeanella sp. (Figure 6: 10 - B309; R. Martini and L. Zanine�i, wri�en communication, 2001) which prove a Late Triassic (Norian to Rhaetian) age close to the top of the Al Ayn Formation. No indication for a Jurassic age was found.

Synonymy The Al Ayn Formation incorporates part of the Sandstone Member of the Guwayza Formation and the Al Ayn Sandstone (Al Ayn Formation) as defined by Glennie et al. (1974), the Guwayza Sandstone Formation established by Cooper (1987) and the siliciclastic part of the Upper Member of the Matbat

Formation (Mb2 – ‘russet sandstone’) as defined by Béchennec et al. (1986) and Béchennec (1987).

Regional variations Besides lateral variations in thickness, the Al Ayn Formation shows a large variability in composition. In contrast to the northwestern outcrop areas (Figure 2: 1, 4 to 7), which are dominated by a quartz arenite lithofacies (quartz > 90%), the southern and southeastern outcrop areas of the Oman Mountains (Figure 2: 10, 18, 20, 21 and 22, Figure 7b) are characterised by a more mixed carbonate/ siliciclastic lithofacies (calcarenaceous sandstone and quartz-bearing calcarenite) with common limestone conglomerates as described above. However, the variability in thickness and in facies of the Al Ayn Formation is difficult to quantify because most of the successions are incomplete due to thrust-contacts to under- or overlying tectonic units.

Guwayza Formation

Type section The Guwayza Formation (including the Sandstone Member and the Limestone Member) established by Glennie et al. (1974) is named a�er the Wadi Guwayza in the eastern Hamrat Ad Duru Range (Figure 2). The Guwayza Formation was subdivided into the Matbat Formation and overlying Guwayza Formation sensu stricto and redefined several times by the BRGM team (Figure 3). Based on lithological arguments, the Guwayza Formation is herein revised and divided into two formal, mappable lithostratigraphic members that are from base to the top: the Tawi Sadh Member and the Oolitic Limestone Member (Figure 3).

Guwayza Formation - Tawi Sadh Member

Type section The newly introduced Tawi Sadh Member is named a�er the nearby small village of Tawi Sadh, located in Wadi Mu’aydin (Figure 2 and 8: 18) at the southern extension of Jabal Akhdar. Other sections have been measured in the Wadi Muti (Figure 2 and 8: 20, Figure 9a) and in the Jabal Safra area (Figure 2: 21).

Lithology and sedimentary features The lithological properties of the Tawi Sadh Member are highly variable, and in places the member dies out altogether. At the type locality (Figure 8: section Wadi Mu’aydin, 18) the whole member is characterised by greenish to dark-grey shale. The lowermost part consists of more than 45 m of grey-green, thinly-bedded radiolarian chert and strongly silicified limestone up to 10 cm thick and interbedded dark shale and marl. Up-section the number of radiolarian chert beds decreases and up to 20 cm thick strata of brown-coloured calcarenite appear.

The upper part of the member is an approximately 100 m thick yellow-brown weathered, mixed carbonate/siliciclastic sequence (Figure 8: 18 and 20). Oolitic and pelletal calcarenites with a variable content of sand-sized quartz and limestone lithoclasts are the dominant lithologies in this interval. Minor cherty beds are also common. The detrital quartz content in the uppermost part of the Tawi Sadh Member commonly exceeds 50% of the grains (calcarenaceous sandstone). Up to 4 m thick

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sandstone beds are common. Coarse-grained sandstones and conglomerates with floating boulders of intraclasts are locally developed (Figure 9a). At the top of this sequence, a fast transition into the Oolitic Limestone Member is observed with decreasing content of siliciclastic detritus. The total thickness of the type section is 150 m.

The sediments are characterised by: (1) normally-graded, parallel laminated and/or rippled calcarenite and sandstone; (2) minor non-graded massive sandstone (partially with floating sandstone/limestone boulders); and (3) interbedded structureless shales. The radiolarian cherts and silicified limestones at the base of the member show minor parallel lamination and/or flaser structures. The thickness of single sandstone and calcarenite beds is laterally highly variable. Erosive contacts and slump structures are common, particularly in the upper part of the sequence. Flute casts indicate transport of the sediment from south to northwest/northeast.

Well-preserved ichnofossils (e.g. Halymenites, Chondrites, Protovirgularia, A. Wetzel, wri�en communication, 2002) can be observed on the bases of fine-grained, thinly-bedded calcarenite beds in the middle part of the succession.

Boundaries The base of the Tawi Sadh Member is generally poorly exposed or a tectonic contact characterised by thrusts and associated isoclinal folds. However, good exposures in Wadi Saal (Figure 6: 10) reveal a hitherto undetected paraconformity beween the sandstone facies of the Al Ayn Formation and the so� shales forming the base of the Tawi Sadh Member. A comparable succession is developed in the Tawi Shannah section (Figure 6: 7). The contact to the overlying Oolitic Limestone Member is gradational and is arbitrarily set at the base of the lowest massive oolitic limestone beds.

Age Radiolarian assemblages from the studied sections reveal a late Pliensbachian? - early Toarcian age for the lower part of the member and an early or middle Bajocian age for its top. The base of the member, however is poorly constrained due to insufficient exposure conditions and because many successions are incomplete due to thrust contacts to underlying tectonic units. The occurrence of late Pliensbachian radiolarians closely above the base and the presence of Triassic fossils in the top of the underlying Al Ayn Formation, is seen as a clear indicator of a stratigraphic gap encompassing He�angian and Sinemurian-early Pliensbachian. The radiolarian fauna from the base of the member is comparable with the late Pliensbachian to early Toarcian faunas from Oregon studied by Yeh (1987), containing, among other species, Bistarkum bifurcum Yeh, Canoptum anulatum Pessagno and Poisson, Napora relica Yeh, Pleesus aptus Yeh, Pseudoristola obesa Yeh. This fauna is the most frequently found in the sections described here. Late Toarcian and Aalenian radiolarians, otherwise, are comparably rare either because of facies or tectonics. One of the best sections regarding the radiolarian fauna of this time interval is located in the Jabal Safra area (Figure 2: 21) whereas the Aalenian fauna found in the Al Sawad section (Figure 8: 20 - BR560-590) is poorly preserved. The top of the Tawi Sadh Member was dated in the type locality (Figure 8: 18 - BR1131) as well as in several sections, as for instance in the southeastern part of Jabal Safra (Figure 2: 21 - Appendix: BR828) and in the section Kadrah Bani Dafa’a (Figure 2: 22 - Appendix: BR454, BR457) where the radiolarian assemblages indicate either an early or a middle Bajocian age.

Synonymy The radiolarian chert level at the lower part of the member in the Wadi Mu’aydin area (Figure 2: 17, 18 and 20) was alternatively mapped as the upper unit of the Al Jil Formation or as the upper part of the Upper Member of the Matbat Formation (Béchennec et al., 1992; Hutin et al., 1986; Figure 3). The upper part of the Tawi Sadh Member (dominated by lithoclastic sediments) incorporates the

Upper Matbat Member (Mb2) of Hutin et al. (1986). Glennie et al. (1974) and equally Cooper (1987) did not distinguish the differences between the Triassic sandstone sequence (Al Ayn Formation) and the Jurassic sandstone sequence (Tawi Sadh Member). In contrast, Al Sulaimani et al. (1991) pointed out that a separate level of at least 40 m in thickness is present consisting of yellow-brown weathered, partially quartz-bearing, lithoclastic limestone and green chert at the base of the oolite-dominated facies of the Guwayza Formation in the central Hamrat Ad Duru Range.

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AL SAWAD (20) WADI MU'AYDIN (18) UTM 578108/2544420 UTM 569514/2538712 Grain Size Grain Size Pebble Pebble Sample Sand Sample Sand Fm Fm Mbr Clay Mbr Clay Oolitic

LimestoneOo. Member Thickly-bedded grey ooid-dominated Thickly-bedded, grey calcarenite ooid-dominated calcarenite

200 Partially silicified oolitic calcarenite BR1094/2 200 L. Bajocian/ E. Bathonian

Oolitic Limestone Member Yellowish-brown ? quartz-bearing cal- BR1091 carenite, green shale Bajocian/ and green radiolarian Callovian chert Partially silicified, quartz-bearing oolitic Guwayza Formation calcarenite, sandstone 150 Silicified ooid- bearing calcarenite and white chert 150

Massive quartz and calcarenaceous sandstone, quartz- bearing oolitic and

pelletal calcarenite, Guwayza Formation shale and siltstone Massive quartz and 100 calcarenaceous sandstone, quartz- bearing oolitic and pelletal calcarenite, 100 green shale/siltstone

Tawi Sadh Member BR1131 Aalenian?/ Tawi Sadh Member E. Bajocian BR1130 BR590/591 L. Aalenian?/ Aalenian/ E. Bajocian Bajocian? BR1129 50 m BR583/587 Aalenian Aalenian BR1128 L. Toarcian/ 50 m Aalenian Grey/black chert BR1123 and shale, quartz- L. Pliensba- bearing calcarenite chian/ and calcilutite E. Toarcian BR1120/1122 L. Pliensba- chian/ E.Toarcian Grey/greenish chert, BR560/562 shale and brown Aalenian weathering calcarenite

Figure 8: Measured sections through the Tawi Sadh Member and lowermost part of the Oolitic Limestone Member of the Guwayza Formation: section Wadi Mu’aydin (18) and section Al Sawad (20). Only the radiolarian assemblages of bo�om and top samples of each member/formation are included in the text or appendix. See Figure 4 for key.

Regional variations The largest variability in thickness and lithofacies of all units of the Hamrat Duru sediments is observed in the Tawi Sadh Member of the Guwayza Formation. The thickness decreases from more than 150 m in the Wadi Mu’aydin area to about 100 m in the Hamrat Ad Duru Range (Figure 2: 9 and 10, ca. 100 m, Figure 9b) and less than 50 m in the Jabal Safra area (Figure 2: 21). This change is accompanied by a diminishing amount of detrital quartz (Figure 9c). In the Jabal Safra (Figure 2: 21), Jabal Wahrah (Figure 2: 2), Wadi Al Ayn (Figure 4: 7) and Jabal Hammah area (Figure 1: 14), chert and sandstone are rare and the Tawi Sadh Member is represented by a high amount of shale and partially

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A B B A

A A

Figure 9: Outcrop photographs showing the bedding pa�erns of the Tawi Sadh Member (Guwayza Formation): (a) Thickly-bedded, massive sandstone bed in Wadi Mu’aydin section (A) with oversized floating limestone intraclasts (B) (lens cap for scale). (b) Greenish/white radiolarian chert and marl (A) and brown weathered calcarenite interbeds (B) in Wadi Saal section (hammer for scale). (c) Greenish radiolarian chert (A) and thinly-bedded, normally-graded, parallel laminated fine-grained calcarenaceous sandstone (B) in Jabal Safra section (hammer for scale). (d) Brown weathered calcarenite with well-preserved clastic dyke (A) in Jabal Safra section (hammer for scale).

silicified limestone. In some of the outcrop areas it is therefore difficult to identify the Tawi Sadh Member because the characteristic lithofacies types are either missing or are represented by a thin level of less than 20 m of dark grey shale and minor silicified limestone layers.

Guwayza Formation - Oolitic Limestone Member

Type section The Oolitic Limestone Member was first defined by Glennie et al. (1974) in the Wadi Guwayza, eastern Hamrat Ad Duru Range, as an informal Limestone Member of the Guwayza Formation. Here, the basal part of the Limestone Member sensu Glennie et al. (1974) is included in the newly introduced Tawi Sadh Member. Other localities exposing a well developed Oolitic Limestone Member lie in the south and southwest of the Jabal Akhdar area (see also Hutin et al., 1986). The sections described below are shown in Figures 8 and 10.

Lithology and sedimentary features The successions in the Wadi Mu’aydin and Wadi Muti are rather thick and exceptionally well-exposed (Figure 8: 18 and 20 and Figure 10: 20, Figure 11a). There, the Oolitic Limestone Member is comprised of a more than 300-m-thick sequence consisting mainly of light grey-weathered, amalgamated metre- bedded, coarse-grained calcarenite dominated by resedimented ooids and carbonate lithoclasts such

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AL SAWAD (20) WADI SAAL (10) UTM 578108/2544420 UTM 489020/2524022 Grain Size Grain Size Pebble Pebble Sample Sand Sample Sand Fm Fm Mbr Mbr Clay Clay

Silicified limestone, Silicified calcarenite white and green BR52 and calcilutite, radiolarian chert Oxfordian white chert L. Mbr Sid'r Fm Sid'r Fm Lower Mbr Calcirudite with 250 large boulders of reefal and Ooid-dominated lagoonal calcarenite carbonate (partially strongly silicified), calcirudite and 300 shale

Thickly-bedded, grey ooid- Thickly-bedded dominated oolitic and 200 calcarenite and lithoclast calcilutite dominated calcarenite

250 Calcarenite, calcilutite and shale

Calcilutite, calcarenite and calcirudite with large 150 boulders of reefal and lagoonal carbonate

200 Thickly-bedded,

grey ooid- Oolitic Limestone Member No dominated calcarenite Grey ooid- samples dominated

Oolitic Limestone Member taken calcarenite and calcilutite BR715 100 Calcarenite and Bajocian calcilutite Guwayza Formation

Guwayza Formation 150

BR706/2 L. Bajocian Thickly-bedded, grey ooid- 50 m dominated calcarenite and BR704 L. Bajocian/ calcilutite Thickly-bedded, E. Bathonian grey ooid- BR138 dominated E./M. Bajocian 100 calcarenite Yellowish-brown quartz-bearing calcarenite, silicified limestone and chert Tawi Sadh Mbr

Figure 10: Measured sections through the Oolitic Limestone Member of the Guwayza Partially silicified 50 m oolitic-calcarenite Formation: section Wadi Saal (10) and section Al Sawad (20) including the lowermost part of the Sid’r Formation and the uppermost part of the Tawi Sadh Member. Only the radiolarian Partially silicified, assemblages of bo�om and top samples of each quartz-bearing oolitic-calcarenite, member/formation are included in the text or sandstone Tawi Sadh Member appendix. See Figure 4 for key.

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C A

A B ca. 70m A B A B

strike-slip fault

TB Figure 11: Outcrop views of the Oolitic Limestone Member (Guwayza Formation): (a) Well-exposed Oolitic Limestone Member showing three sequences of grey-weathered, amalgamated metre- bedded, coarse-grained calcarenite (A) separated by calcilutite intervals (B), section Al Sawad. (b) Close-up view of calcilutite interval with alternating calcilutite (A) and subordinate calcarenite beds (B) and rare oversized clasts of fawn dolomite (C). Note dune formset of calcarenite bed (B) (hammer for scale), section Al Sawad. (c) Thickly-bedded, clast to matrix-supported calcirudite with oversized clasts (hammer for scale), section Firq. (d) Succession dominated by ooid bearing calcarenite and calcilutite without calcirudites; younging towards le�. Note differences between the proximal section in (a) and distal section in (d) of the Oolitic Limestone Member (2 m trees for scale). Inset showing well-developed base-cut-out Bouma sequence.

as fawn dolomite and dark coloured recrystallized limestone (Figure 11a). This coarse-grained facies forms three major intervals, each up to tens of metres in thickness (Figure 10: 20 and 10). These intervals are separated by predominantly calcilutite packages and subordinate calcarenite, radiolarian chert and shale (Figure 11b, Figure 7b). Common calcirudites in the middle and uppermost part are made up of thickly bedded carbonate conglomerates with boulders of mostly Triassic reefal and lagoonal limestones (Figure 11c) measuring up to several metres in diametre. These boulder to pebble-sized clasts are sub-rounded to rounded. The calcirudites are mostly clast-supported with an oolitic matrix. The near sheet-like conglomerate bodies can be traced for more than 25 km along the southern footwall of the Jabal Akhdar (Rathmayr, 2000). The clast composition of the uppermost conglomerate level is dominated by lagoonal dolomites (Triassic?), recrystallized dark bioclastic limestones (Liassic?) and intraclasts.

Generally, the sediments are characterised by: (1) normally-graded, parallel laminated and/or rippled calcarenite; (2) massive calcarenite partially with floating granules, ra�ed intraclasts and carbonate lithoclasts; (3) massive, mostly structureless calcilutite; (4) stratified, normally- or inversely- to normally-graded calcirudite; and (5) disorganised to normally-graded calcirudite (Figure 11c). Thick beds frequently containing oversized clasts are commonly amalgamated. Flute casts and large scale

100 101

FIRQ (17) ZUKAYT (19) UTM 565130/2536004 UTM 576289/2531795 Grain Size Grain Size Pebble Pebble Sample Sand Sample Sand Fm Fm Mbr Clay Mbr Clay

Silicified lime- B68/82 stone and chert Silicified limestone E.Barremian and white chert Nayid

Fm L. Ceno- ? Nayid manian? Thickly-bedded, oolitic-calcarenite BR159 and calcirudite L. Hauterivian 100 Thickly-bedded BR158 calcarenite and E./M. calcirudite Up. Mbr Hauterivian 200 BR157 L. Valanginian/ Fine-grained cal- E.Hauterivian carenite, calcilutite and micro- BR155/156 White chert and Berriasian/

Upper Member conglomerate pinky-orange E. Valanginian coloured silicified BR151/154 limestone, ooid- Berriasian bearing calcarenite BR147/149 50 Sid'r Formation L. Tithonian Radiolarian-bearing Sid'r Formation

Lower Member BR146 calcilutite, silicified Tithonian calcarenite Red/white-grey radiolarian chert, BR499 150 BR145 Hauterivian M/L. Oxfordian shale and silicified limestone BR498 BR144 L. Valanginian Oxfordian BR497 BR143 Massive, fine- E. Valanginian M?/L Oxfordian grained oolite dominated- BR142 Oolitic Thin to medium L. Mbr calcarenite bedded calcarenite Guw. Fm E/M. Oxfordian (partially silicified) 0 m BR496a and calcilutite, white BR141 Berriasian chert, shale and Callovian?/ microconglomerate/ Oxfordian breccia BR140 100 L. Bathonian/ E. Callovian BR139 Bathonian/ E. Callovian

Lower Member BR492 L. Tithonian/ Berriasian Figure 12: Measured sections through the Sid’r Formation: section Firq (17) and section Zukayt BR490 Callovian/ (19) including the lowermost level of the Nayid Oxfordian Calcarenite and Formation and the uppermost part from the BR489 calcirudite (partially Callovian/ 50 m strongly silicified) Guwayza Formation. See Figure 4 for key. Oxfordian and chert

? Thickly-bedded, grey oolite dominated calcarenite B49 (partially silicified) M./L.?/Jurassic and calcirudite Guw. Fm

Oo. L. Mbr

cross-bedding generally indicate sediment transport from south to north in the proximal facies and from northwest to the southeast in the most distal facies. At the base of fine-grained calcarenite beds ichnofossils are common (e.g. Thalassinoides, Helminthopsis, Palaeodictyon, A. Wetzel, wri�en communication, 2002).

Boundaries The lower boundary of the Oolitic Limestone Member is marked by the transition from quartz- bearing lithoclastic limestone and shale of the Tawi Sadh Member into ooid-dominated calcarenites. The lower boundary is arbitrarily set at the lowermost thickly bedded oolitic limestone. The top is characterised by a rapid transition or an abrupt contact to the silicified limestones, radiolarian cherts and spiculites of the overlying Sid’r Formation. A thin level of radiolarian-bearing green chert commonly marks the top of the member.

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Age Based on the age of the uppermost part of the underlying Tawi Sadh Member and some radiolarian faunas from a green radiolarian chert bed directly beneath the lowermost thickly-bedded oolitic limestone at the base of the Oolitic Limestone Member, the base of the la�er is dated as middle Bajocian. Such green radiolarian chert beds were observed in Wadi Saal (Figure 2: 10 - Appendix: BR138) and Wadi Yail (Figure 2: 9 - Appendix: BR107) in a similar stratigraphic position. The age of the top of the Oolitic Limestone Member is again established on the basis of radiolarian faunas extracted from green radiolarian chert beds intercalated between the uppermost oolitic limestone beds in the Zukayt section (Figure 12: 19 - BR139) and in the Qusayd-Shulayshil section (Figure 2: 3 - Appendix: BR942). These faunas, although poorly-preserved, indicate a middle/late Bathonian to early Callovian age (UAZ 5-7 of Baumgartner et al., 1995). Reworked shallow water foraminifera (B49, B168, B175, B292, B300, B337, B367/C - Protopeneroplis, Trochammina, Trocholina, Endothyridae, Miliolidae, Textulariidae) in the oolitic facies of Wadi Saal (Figure 6: 10), Wadi Yail (Figure 2: 9), Jabal Safra (Figure 2: 21), Firq (Figure 12: 17) and Kadrah Bani Dafa’a (Figure 2: 22) also suggest a Middle to Late(?) Jurassic age (R. Martini and L. Zanine�i, wri�en communication, 2001).

Synonymy The Oolitic Limestone Member corresponds closely to the informal Limestone Member of Glennie et al. (1973), the Guwayza Limestone Formation of Cooper (1987), the Guwayza Formation in Hutin et al. (1986) and Béchennec (1987) (Figure 3). The Oolitic Limestone Member also incorporates the Lower Limestone Member of the Wahrah Formation sensu Glennie et al. (1973).

Regional variations The Oolitic Limestone Member is represented by a large number of complete successions. These are marked by strong variations in the measured thickness with a distinct decrease in grain size and bed thickness from more proximal (17, 18 and 20: thickness > 300 m) to distal sequences (2: thickness < 70 m; 3: thickness < 100 m; 14: thickness < 100 m; 24: thickness < 70 m). The most proximal sequences are characterised by the occurrence of calcirudites and slump horizons with oversized blocks within the sequences. In all successions, the calcarenites are dominated by reworked ooids, in contrast to the calcirudites which consist mainly of platform-derived exoclasts of Permian and Triassic age.

In contrast to the outcrop areas discussed above, the uppermost part of age-equivalent successions in the Jabal Safra area (21), in the Wadi Sid’r (11), in Kadrah Bani Dafa’a (22) and in the south of the Hamrat ad Duru Range (10 and 11) is marked by particularly well-exposed metre-sized exotic carbonate olistoliths, associated with contorted strata produced by slumping. The olistoliths comprise Triassic limestone in Hallsta� facies, Permian reefal limestone (Hutin et al., 1986; Tozer and Calon, 1990) and limestone with Late Permian fusulinids (D. Vachard, oral communication, 2001). Since the Triassic in Hallsta� facies is not known from the autochthonous of the Arabian Platform, the source of these olistoliths was, according to Tozer and Calon (1990), not the Arabian Platform edge as assumed previously (Béchennec, 1988; Robertson, 1987; Searle and Graham, 1982), but oceanic build- ups such as seamounts or isolated oceanic platforms.

Figure 13 (facing page): Photographs showing the bedding pa�ern of the Sid’r, Nayid and Wahrah Formations: (a) Well-exposed boundary between the uppermost part of the Guwayza Formation (Oolitic Limestone Member) and the Lower Member of the Sid’r Formation, section Al Sawad (4 m tree for scale). Inset: nodular to layered silicified limestone and radiolarian chert showing characteristic pinky-orange colour of the Lower Member of the Sid’r Formation. (b) Centimetre- to metre-bedded, medium- to coarse-grained, light grey-weathered calcarenite and small erosive channels of the Upper Member of the Sidr Formation (Jabal Safra, hammer for scale). (c) Flaggy to decimetre-bedded, fine- to medium-grained, pale light brown weathering calcarenite of the Nayid Formation. Note well-developed base-cut-out Bouma sequence (Jabal Safra, pencil for scale). (d) Centimetre- to decimetre-bedded, red-brown radiolarian chert layers alternating with red, siliceous shale interbeds of the Wahrah Formation (Red Bedded Chert Member, Jabal Hammah, hammer for scale). Note the structureless chert bed (inset A) and the partially normally graded, parallel laminated and partially bioturbated chert bed (inset B).

102 103

Lower Mbr (Sid'r Fm)

Oolitic Limestone Mbr (Guwayza Fm)

0 2 cm A

0 2 cm B

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Sid’r Formation

Type section The Sid’r Formation was established by Glennie et al. (1974) in the Wadi Sid’r in the southeastern Hamrat Ad Duru Range (Figure 2: 11) and later redefined by Béchennec et al. (1986) and Béchennec (1987) in Wadi Nayid, in the northwest of the Hamrat Ad Duru Range (Figure 2: 13). Béchennec et

al. (1986) recognised three lithostratigraphic units in the Sid’r Formation, a Lower Member (Sid’r1), a

Middle Member (Sid’r2) and an Upper Member (Si2C). The Upper Member (Si2C), a radiolarian chert and silicified limestone-dominated unit, was later included in the basal part of the Nayid Formation (Béchennec et al., 1992). Thus the Sid’r Formation remained with only two members: Lower and Upper Members. Characteristic sections are shown in Figure 12 (17 and 19).

Boundaries The lower boundary of the Sid’r Formation is in most sections marked by an abrupt or a gradual increase in silicification and a decreasing amount of redeposited carbonate material (Béchennec, 1987; Béchennec et al., 1986; Cooper, 1990, Figure 13a). The top of the Sid’r Formation is characterised by a rapid transition or by a sharp contact to strongly silicified fine-grained limestones and cherts of the overlying Nayid Formation.

Synonymy The Lower Member sensu Béchennec et al. (1986, 1992) incorporates the Sid’r Formation of Glennie et al. (1973) and Cooper (1987). The Upper Member sensu Béchennec et al. (1992) represents the lower part of the Nayid Formation of Glennie et al. (1974) and the Nayid Formation of Cooper (1987).

Sid’r Formation - Lower Member

Lithology and sedimentary features The Lower Member generally comprises partially to completely silicified, thinly- to medium-bedded calcarenite and calcilutite, radiolarian chert and minor shale; microbreccias are also common. The calcarenites and microbreccias in the Wadi Mu’aydin area (Figure 12: 17 and 19) contain a high amount of carbonate lithoclasts such as fawn dolomite and dark-grey coloured limestone. A characteristic feature of the Lower Member is the presence of nodular or layered cherts and silicified limestone and a pinky-orange colour (Figure 13a). The thickness of the member is highly variable, reaching more than 100 m (section Firq, Figure 12: 17). In section Firq, the Lower Member constitutes a fining-upward succession which grades into the silicified limestone, chert and radiolarian-bearing, calcilutite-dominated upper part of the member (Figure 12: 17). In section Zukayt (Figure 12: 19) the lower 20 m of the section are dominated by red and light-grey radiolarian chert, followed by about 40 m pinky-orange, silicified limestone.

Normal-grading, parallel lamination and/or cross-bedding and flaser-bedding are common, particularly in the coarser-grained sediments. In the most proximal successions, flute casts and cross- bedding indicate a sediment transport from south to north or from northwest to southeast in the distal sections. The tops and bases of the beds commonly show various ichnofossils (e.g., Chondrites, Thalassinoides, Helminthoida, Cosmoharphe, Phycosiphon, A. Wetzel, wri�en communication, 2002).

Age There are difficulties in precisely dating the base of the Lower Member because this several metres thick interval of green or grey shale contains none-to insufficiently-preserved radiolarian fauna. In the Zukayt section, the oldest datable sample (Figure 12: 19 - BR140) has a fauna assignable to the UAZ 7 of Baumgartner et al. (1995) corresponding to late Bathonian-early Callovian. Therefore, the base of the member practically coincides with the Bathonian/Callovian boundary, which is in agreement with the age of the top of the underlying Guwayza Formation. However, due to poorly- preserved radiolarian assemblages at the base of the Lower Member in many other sections the oldest sample with a datable radiolarian fauna reveals Oxfordian (Figure 2: 8 - Appendix: BR627; Figure 10: 10 - BR52; Figure 12: 17 - BR490), or even late Tithonian-earliest Berriasian such as in the

104 105

Jabal Safra (Figure 2: 21) and the Kadrah Bani Dafa’a section (Figure 2: 22). In the last two sections the Lower Member of the Sid’r Formation is represented by cherty limestones in Maiolica facies with radiolarians preserved only in chert nodules or in their incompletely silicified margins (Figure 2: 21 - Appendix: BR536-552, 22 - Appendix: BR464-465). The Lower Member in radiolarian-bearing Maiolica facies was also recorded in Wadi Sid’r (Figure 2: 11 - Appendix: BR68-81) and in Wadi Nayid (Figure 14: 13 - BR84-97) where this facies reaches up to the Hauterivian as indicated by the youngest radiolarian found in the Lower Member.

Boundaries The basal boundary of the Lower Member in section Zukayt (Figure 12: 19) is marked by an abrupt increase in silicification and a decreasing amount of clastic material, whereas in section Firq (Figure 12: 17) the Guwayza Formation grades into the Sid’r Formation with a fining- and thinning- upward of the beds, accompanied by an increase in silicification. In both sections the boundary to the overlying Upper Member is set at the distinct change from strongly silicified fine-grained radiolarian- bearing limestones and cherts to non-silicified calcarenites.

Sid’r Formation - Upper Member

Lithology and sedimentary features The Upper Member, measuring approximately 70 m in the Firq section (Figure 12: 17), is characterised by a distinct reduction in silicification and the appearance of centimetre-to-metre-bedded, medium- grained to coarse-grained, light grey-weathered calcarenite. The calcarenites contain a high amount of reworked ooids and carbonate lithoclasts such as fawn dolomite and dark-grey coloured limestone. Common calcirudites consist of boulders of Permian(?)/Triassic reefal and lagoonal limestones, and of intraclasts (cherts, calcarenite and calcilutite). In section Zukayt (Figure 12: 19) the sequence is dominated by about 25 m of thickly bedded calcarenites and calcirudites.

The sediments generally show normal-grading, parallel lamination and/or ripple cross-bedding. Small, metre-sized erosive channels are common. Thalassinoides and Berganeria ichnofossils are frequently observed at the base of the beds (A. Wetzel, wri�en communication, 2002).

Age Biostratigraphic dating of the Upper Member is difficult because radiolarians are commonly missing. One sample in the section Kathmah (Figure 2: 16 - Appendix: BR727) and another in the section Musallah (Figure 2: 8 - Appendix: BR637) indicate a late Albian to early Cenomanian age. Taking into account the dating of the Lower Member and of the overlying Nayid Formation, the age of the Upper Member is considered to be Barremian to Cenomanian. The common foraminifers in the section Zukayt (Orbitolinidae, Textulariidae and large Miliolidae - Figure 12: 19 - B68, B82) also suggest an early Barremian to Cenomanian age for the Upper Member (R. Martini and L. Zanine�i, wri�en communication, 2001).

Boundaries In both sections (Figure 12: 17 and 19), the lower boundary of the Upper Member is marked by a distinct change from pervasively silicified limestones and radiolarian cherts to non-silicified calcarenites. The boundary to the overlying Nayid Formation is characterised by a decreasing amount of carbonate lithoclasts, accompanied by a rapid increase in silicification.

Regional variations In most of the studied sections, the two members of the Sid’r Formation with their characteristic lithofacies are present (Figure 2: 8, 13, 16, 17, 19, 21 and 22). Typically, the Lower Member is marked by major variations in thickness, degree in silicification and amount of calcarenite/calcirudite from proximal (Figure 2: 17, 18 and 20, ≅ 100 m; 10 and 11, > 150 m) to more distal se�ings (Figure 2: 16 and 19, < 65 m; 8 and 21, < 55 m). Successions representing more distal facies show a fast transition from the underlying calcarenites of the Oolitic Limestone Member into a radiolarian chert, silicified mudstone- and limestone-dominated facies with shale intercalations. The more proximal facies

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FIRQ (17) WADI NAYID (13) UTM 565130/2536004 UTM 519340/2511690 Grain Size Grain Size Pebble Pebble Sample Sand Sample Sand Fm Fm Mbr Clay Mbr Clay

BR655 Exotic block and L. Norian/ red chert Silicified calcarenite Rhaetian

Oman Exotic and sponge spicule- BR654 bearing calcilutite L. Turonian/ 50 m E. Coniacian Silicified limestone and radiolarian chert

Pale light brown weathering calcarenite (subordinate 200 microconglomeratic and calcilutite Pale light brown Nayid Formation B104/B109 weathering calcarenite Nayid Formation Albian/ (subordinate Santonian microconglomeratic) and calcilutite

~ 90 m composite section!

Silicified limestone and chert 150 Silicified calcarenite B100a and radiolarian- Fm. Coniacian/

Nayid bearing calcilutite E. Santonian ? Thickly-bedded, grey calcarenite

U. Grey, massive

Mbr and calcirudite Sid'r calcarenite (partially microconglomeratic) Figure 14: Measured sections through the Nayid Formation: section Wadi Nayid (13) and section Grey, massive litho- Firq (17) including the uppermost level of the clastic calcarenite, partially micro- Sid’r Formation. See Figure 4 for key. 100 conglomeratic Upper Member shows a fining- and thinning-upward trend from the coarse-grained top of the Oolitic Limestone Member into the Lower Member. In Lithosclatic calcarenite and calcilutite, these sections, a gradual increase in silification BR97 partially strong Valanginian silicified and the occurrence of radiolarian chert can be Sid'r Formation BR95 observed. Conglomerate and/or breccia beds E. Valanginian 50 m are still common in the basal part but disappear BR93/94 L. Berriasian/ completely up-section. The successions of the E. Valanginian BR91/92 Upper Member show the same proximal to distal Berriasian/ Silicified lithoclastic E. Valanginian? calcarenite and white trend in thickness and lithofacies as the Lower radiolarian chert Member of the Sid’r Formation. The thickness Lower Member BR88/BR90 Berriasian of the Upper Member varies from less than 40 m BR84/87 (Figure 2: 8, 13, 16, 19 and 21) to more than 80 m L. Tithonian (Figure 8: 18, Figure 12: 17). The most proximal facies is found south of Jabal Akhdar (17 and 18), where it is characterised by a less pronounced silicification and conspicuous coarse pebble to fine-boulder-grade conglomerate and breccia, with oversized blocks in the uppermost part of the member. The calcarenites in all sections are dominated by lithoclastic material (Figure 13b), whereas the conglomerates and breccias contain mainly reworked platform detritus of Triassic/Permian? age and diverse intraclasts.

Nayid Formation

Type section The Nayid Formation, first established by Glennie et al. (1974) in Wadi Nayid in the northwest Hamrat Ad Duru Range (Figure 2: 13), was later redefined by Béchennec (1987) and Béchennec et al. (1986, 1992) in the same area. A typical section from Wadi Nayid (13) is shown in Figure 14, exposing the contact to the underlying Sid’r Formation.

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Lithology and sedimentary features The base of the Nayid Formation is generally marked by a 10-to-15 m thick level of pinky-orange ‘fine-grained’ silicified calcarenite and radiolarian-bearing calcilutite and chert (Béchennec etal., 1993). Up-section follow c. 90 m of thinly- to medium-bedded, fine-to medium-grained, pale light brown weathering calcarenite and subordinate microconglomerate (Figure 13c). The succession is well-bedded and characterised by normally-graded, parallel laminated and/or rippled beds and partially well-preserved convolute bedding (Figure 13c). Primary structures in the upper part of the beds are commonly blurred by burrowing, mostly by Zoophycos and Chondrites (A. Wetzel, wri�en communication, 2002).

Boundaries The basal boundary of the Nayid Formation is characterised by the appearance of strongly silicified limestones, cherts and fine-grained calcarenites (Béchennec, 1987; Béchennec et al., 1986; Cooper, 1990; Glennie et al., 1974). The top of the Nayid Formation is generally a tectonic contact to an overlying thrust slice.

Age Most cherts of this formation are spiculites. Tests of Radiolaria or planktonic foraminifera are scarce. However, one sample (BR654) from a radiolarian chert in section Firq (Figure 12: 17) indicates a late Turonian - early Coniacian age, and a second sample (BR100a) from the Wadi Nayid section (Figure 14: 13) reveals a Coniacian - early Santonian age. Therefore, a tentative Cenomanian-Coniacian - ?Santonian age can be assumed.

Synonymy The Nayid Formation sensu Béchennec et al. (1992, 1993) equals to the upper part of the Nayid Formation in Glennie et al. (1974) and to the Riyamah Member (Muti Formation) of Cooper (1987).

Regional variations The Nayid Formation is observed in a few outcrop areas only (Figure 2: 8, 13, 17, 19 and 21) and it is always incomplete, with the top missing due to tectonic contacts to overlying thrust slices. The maximum thickness of the Nayid Formation occurs at the southern end of the Jabal Akhdar (Figure 14: 17, ≅ 150 m) and in Wadi Nayid (Figure 14: 13, ≅ 100 m). The studied sections show no significant regional variations in lithofacies.

Wahrah Formation

Type section The type section was established by Glennie et al. (1973) in the Jabal Wahrah area (Figure 2), north of the Hamrat Ad Duru Range, where the formation was subdivided into five informal members. Later workers modified the lithostratigraphic terminology of the Wahrah Formation (Figure 15). The Wahrah Formation is divided into a basal Variegated Mudstone Member and a Red Bedded Chert Member, both defined by Kickmaier and Peters (1990) and later also described by Biaggi and Steinmann (1995), and Kickmaier (1995). The ‘Lower Limestone’ of Glennie et al. (1973) has been a�ributed to the Guwayza Limestone Formation by Béchennec et al. (1993) and is no longer part of the Wahrah Formation (Figure 9). The ‘Upper Limestone’ or ‘Upper Member’ (Figure 15) of previous workers was not found during our investigations and should be abandoned. Typical sections in the Jabal Wahrah and Jabal Hammah are shown in Figure 16 (2 and 14).

Boundaries The boundary between the Guwayza and Wahrah formations is characterised by an abrupt decrease in grain size and an increase in silicification. The tops of the measured sections are always thrust- controlled and characterised by strong folding respectively thrusting.

Age Radiolarian assemblages of three intensively studied sections, namely Al Dhaby (Figure 16: 14 - BR23, 29 and BR36-51a), Qabil (Figure 16: 2 - BR387 and BR388-415), and Al Hammah Range (Figure 2: 24-

106 107

Upper

Limestone Mbr

Figure 15: Relationship between the alternative stratigraphic nomenclatures for the Wahrah Formation compared to the new scheme used in this study.

Appendix: BR832-851 and BR852-862), reveal a Callovian to Kimmeridgian age for the Variegated Mudstone Member and a Tithonian to late Barremian/early Aptian age for the Red Bedded Chert Member. Because of the truncated top the first (14) and the last (24) of the above-mentioned sections end up tectonically in the Berriasian, and the middle (2) in the late Barremian/early Aptian (Aurisaturnalis carinatus perforatus subzone of Dumitrica et al., 1997).

Wahrah Formation - Variegated Mudstone Member

Lithology and sedimentary features The Variegated Mudstone Member contains up to 30 m of lilac to brownish, thinly-bedded, siliceous mudstone, radiolarian-bearing calcilutite and some radiolarian chert and silicified limestone (Figure 16: 2 and 14). Calcarenites are also common (Figure 16: 2). Up-section, beige/orange coloured, centimetre-bedded, strongly silicified lime- and mudstone and chert dominate the sequence. The sediments are characterised by parallel lamination and/or rare cross-bedding and flaser structures. Primary sedimentary structures are partially modified by bioturbation.

Boundaries The contact between the Variegated Mudstone Member and Red Bedded Chert Member is gradational and is arbitrarily set at the level with mainly well-bedded red radiolarian chert.

Synonymy The Variegated Mudstone Member corresponds to the Mudstone Member established by Glennie et al. (1973) and to the lowermost part of the Wahrah Chert respectively of the Lower Member established by Béchennec (1987) and Béchennec et al. (1990) as shown in Figure 15.

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QABIL (2) AL DHABY (14) UTM 463868/2573077 UTM 526238/2515183 Grain Size Grain Size Pebble Pebble Sample Sand Sample Sand Fm Fm Mbr Mbr Clay Clay

BR414/415 Manganese L. Barremian Red-brown radiolarian BR40/51a BR409/413 Berriasian E./?L. Barre- chert and red shale Red-brown radiolarian mian (ribbon chert) chert and red shale BR407/408 (ribbon chert) E. Barremian BR36/39 L. Tithonian BR406 Silicified calcarenite L. Hauterivian/ 100 E. Barremian BR404/405 150 L. Hauterivian BR403 M./L. Haute- Red-brown radiolarian Red Bedded Chert Member BR29 rivian chert and red shale Wahrah Formation E. Kimme- (ribbon chert) BR402 ridgian

Red Bedded Chert Member E. Hauterivian BR23 Radiolarian-bearing BR401 E./M. Oxfordian calcilutite and sili- Wahrah Formation L. Valanginian fied calcarenite and Member Var. Mud. redish chert and BR400 red shale E. Valanginian 50 m BR393/399 Radiolarian-bearing E. Berriasian calcilutite and cal- 100 carenite (partially BR391/392 silicified) and BR20 Member L. Tithonian/ white chert E. Berriasian L. Bajocian/

Var. Mudst. E. Bathonian BR388/390 Grey, ooid-dominated L. Tithonian calcarenite, calcilutite and green shale BR387 Grey, ooid-domina- Kimmeridgian ted calcarenite and

Oo. L. BR386 calcilutite Member (partially silicified) Guwayza Formation Bathonian/ Kimmeridgian BR383 L. Bajocian/ composite section! 50 m Bathonian

Grey, ooid-domina- Guwayza Formation ted calcarenite and green shale Oolitic Limestone Member Oo. L.

Grey calcarenite, Grey, lithoclastic and shale, chert and ooid-bearing calcare- siltstone nite chert, shale and ? BR956 quartz bearing BR648 calcarenite Bajocian Mbr L. Aalenian/ T.S. E. Bajocian 50 m BR954/955 Figure 16: Measured sections through the L. Pliensba- chian/ Wahrah Formation and Guwayza Formation: E. Toarcian section Qabil (2) and section Al Dhaby (14). BR416/417 Guwayza Formation L. Pliensba- Note that only the upper part of the Tawi Sadh chian/ Grey lithoclast and Tawi Sadh Member ooid-bearing calca- Member is shown. See Figure 4 for key. E. Toarcian renite, calcilutite, green shale and green chert

Wahrah Formation - Red Bedded Chert Member

Lithology and sedimentary features This member consists of characteristic ribbon cherts with thinly-bedded, red-brown radiolarian chert layers alternating with red, siliceous shale beds (Figure 13d). In the Qabil section (Figure 16: 2) a c. 5-10-m-thick succession of strongly silicified calcarenite is observed in the middle part ofthe member. Up-section, manganese is enriched and forms up to 60 cm thick black coloured levels (Figure 16: 14). Most of the chert beds can be traced laterally over several tens of metres before they wedge out. Some individual layers are characterised by large chert nodules or lenses. Parallel to wavy lamination and flaser structures are common. The chert beds are commonly strongly bioturbated by Chondrites and other unidentified sediment dwelling organisms.

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Synonymy The Red Bedded Chert Member corresponds to the ‘Upper Chert’ of Glennie et al. (1973), the ‘Wahrah Chert’ of Béchennec (1987) and Béchennec et al. (1990) and the Lower Member of Béchennec et al. (1993) as shown in Figure 15.

Regional variations The Wahrah Formation represents the most distal Late Jurassic to Early Cretaceous lithofacies of the Hamrat Duru Basin and is coeval to the Sid’r Formation (Figure 3). The top of the succession is always marked by a tectonic contact to the overlying thrust slice, therefore the measured sections are never complete. Lateral variations, mainly restricted to the Variegated Mudstone Member, comprise differences in the degree of silification and marked changes in thickness from e.g. 25 m in section 2 to ca. 15 m in section 14 (Figure 16). It appears that the mangenese enrichments get more important from the western to the eastern outcrop areas.

STRATIGRAPHIC ARCHITECTURE

The new biostratigraphic framework allows for a correlation of time-equivalent facies throughout the Hamrat Duru Basin. The correlation of the described sections and their lateral and vertical facies relationships record the complex stratigraphic evolution of a passive margin through time and space (Figure 17). The Hamrat Duru Group represents a vertically mixed carbonate/siliciclastic system punctuated by two phases of high radiolarian productivity and siliceous sedimentation. The six formations of the Hamrat Duru Group are in most cases separated from each other by rapid vertical changes in lithofacies. With the exception of the paraconformal Al Ayn - Guwayza Formation boundary, the vertical contacts between the lithostratigraphic units are conformable and most of the boundaries are variously sharp or gradual. Within the limits of biostratigraphic resolution the formations and members of the Hamrat Duru Group are isochronous with the exception of the base of the Nayid Formation which is time-trangressive (Figure 17).

Independent from tectonically induced local variations, the thickness of most units decreases markedly from proximal to distal se�ings for most of the units within one continuous outcrop area (Figure 17). For example, the Guwayza Formation and the Upper Member of the Sid’r Formation show a general thinning from southwest to northeast, as shown in Figure 17. Furthermore, the Lower Member of the Sid’r Formation shows increasing silicification of the limestones and greater abundance of radiolarian chert and again a general thinning from southwest to northeast towards more distal positions, where radiolarian cherts become volumetrically important (Figure 17: serial section B and C).

DISCUSSION

Depositional Environment

The sedimentary rocks of the Hamrat Duru Group represent base-of-slope to abyssal plain sedimentary facies that accumulated in the Hamrat Duru sub-basin (Glennie et al., 1974; Murris, 1981; Cooper, 1986; Wa�s and Blome, 1990). Generally, the sedimentological features show that the whole succession is mainly represented by mass flow deposits such as turbidites and debris flows which originated from the nearby Arabian Platform and/or platform margin, and from the platform hinterland, by shedding of reworked carbonate and terrigenous clastic material.

Depositional Systems

Three different types of depositional systems are developed in the Hamrat Duru Basin: (1) siliciclastic submarine fan system; (2) a carbonate submarine fan system; and (3) a radiolarian chert system. The siliciclastic and carbonate submarine fan systems show different fan geometries as described below. In the proximal facies, flute casts and current ripples indicate northerly sediment transport, whereas in the distal se�ings the transport direction is towards the east or southeast. These trends in the palaeocurrent directions together with the lithofacies pa�ern shown in Figure 17 suggest a NW- orientated basin axis, particularly from the Middle Jurassic to the Early Cretaceous. Sediment supply

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and dispersal mechanisms in the siliciclastic and carbonate systems were controlled by submarine sediment-gravity flows. The carbonates are dominated by reworked shallow-water material such as ooids, peloids, bioclasts and carbonate lithoclasts from the adjacent Arabian Platform. The Triassic and Jurassic terrigenous clastics were derived from metamorphic and/or sedimentary basement rocks in the hinterland of the carbonate producing areas. In addition, oceanic build-ups such as seamounts and/or isolated platforms related to the faulted continental margin also shed material, representing an exotic carbonate facies (e.g. Permian reef limestone, Triassic Hallsta� facies; Hutin et al., 1986; Tozer and Calon, 1990) into the Hamrat Duru Basin. The petrographic composition of the siliciclastic sandstones reflects detritus derived from sediments generated from a stable continental basement and transported to a passive continental margin (craton interior and transitional continental a�er Dickinson, 1985; or TE-composition a�er Yerino and Maynard, 1984). Successions dominated by siliceous sedimentation such as radiolarian chert and silicified limestone are a�ributed to raised calcite compensation depths associated with high sea-levels, decreased clastic input and high radiolarian productivity.

The siliciclastic deep-sea fan system is well documented in the Al Ayn Formation. It is quartz sand- dominated in at least two local areas (Hawasina Window and Wadi Al Ayn area, Figure 2) separated by regions with mixed carbonate/siliciclastic deposits. This regional facies distribution and the sand/shale ratios suggest a canyon-fed point source in each case. It can be described by the classical submarine fan model with turbidite successions (Mu�i and Ricci Lucchi, 1972). The detritus that built up the siliciclastic fans bypassed the shelf, whereas mixing of siliclastic and carbonate components occurred on the carbonate platform or ramp prior to their deposition on a mixed fan system (Figure 18a). In the proximal fan areas, channelled and amalgamated sandstones and conglomerates are found (e.g. southern Hamrat ad Duru Range, section 10). Coarsening-up sandstone lobe sequences of the middle fan pass vertically and laterally into a shale/siltstone alternation of the basin plain.

The carbonate deep-sea fan system is best represented by the Oolitic Limestone Member of the Guwayza Formation. In the proximal outcrops it is developed in a calcarenite-rich facies with massive amalgamated, laterally continuous, sheet-like high density turbidite beds and debrites, alternating with a calcilutite-rich facies. Major channel systems are not developed. Both facies are interrupted by massive laterally extensive mega-conglomeratic debrites that are thought to have been generated by tsunami waves (Blechschmidt, 2002). The more distal facies of the carbonate deep-sea fan system is characterised by a distinct decrease in grain size and bed thickness compared to the proximal sequences. This facies shows coarsening-up calciturbidite and calcilutite lobe sequences which pass vertically into a mudstone/chert alternation of the basin plain.

Generally, the proximal to distal decrease in bed thickness and grain size combined with the orientation of palaeocurrents indicate numerous sediment sources along the platform edge located to the south and southwest of the Hamrat Duru depocentre (Cooper, 1989). The carbonate deep-marine fan system is controlled by sediment gravity flows which bypassed the upper slope to form sheet-like sediment aprons passing basinward into elongated fan complexes (Figure18b) (Eberli, 1991; Stow, 1992). This is supported by the palaeocurrent directions indicating transport mainly to the north in the proximal apron facies and turning to the southeast in the distal facies following the basin axis.

The radiolarian chert system is represented by two distinct depositional phases of dominantly siliceous sediments. The older one corresponds to the late Anisian-early Norian, the younger started in the late Pliensbachian or early Toarcian and lasted, with some interruptions, until the Coniacian.

The late Anisian-early Norian phase corresponds to the Radiolarian Chert Member of the Zulla Formation and represents an interval of practically uninterrupted pelagic siliceous sedimentation. Its onset was gradational and started as short productive intervals during a predominantly shaly phase in the upper part of the Sandstone and Shale Member of the Zulla Formation. With time these high productivity intervals became more and more frequent during the late Anisian and dominated the sedimentation pa�ern at the beginning of the Ladinian. In the Ladinian and early - middle Carnian the colour of the radiolarian cherts is usually red and silicification complete. The colour of the radiolarian cherts and shales gradually changes to grey-green in the middle Carnian to early Norian part as the degree of silicification decreases. In Wadi Al Ayn (e.g. Figure 2:4, 5) the red colour

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OUTCROP AREA A OUTCROP AREA B Southwest Northeast Southwest Northeast Stratigraphy

65.0 proximal distal proximal distal Maastrichtian Maastrichtian 71.3 Campanian Campanian 83.5 Santonian Santonian 85.8 W. Saal W. Yail (9), Late Coniacian Coniacian (10), W. Nayid (13) 89.0 Turonian Nayid Formation Turonian W. Sid'r 93.5 (11) Cenomanian Cenomanian 98.9 Albian Albian 112.2 Aptian Aptian 121.0

CRETACEOUS Barremian Barremian 127.0 Hauterivian Hauterivian Early 132.0 W. Valanginian Qabil (2) Wahrah Formation Valanginian Musallah Al Dhaby 137.0 (8) (14) Berriasian Qusayd- Berriasian 144.2 Shulayshil Tithonian (3) Tithonian 150.7 Kimmeridgian Kimmeridgian

Late 154.1

Oxfordian Sid'r Formation Al Ayn (5) Oxfordian 159.4 T. Shannah (7) Callovian Callovian 164.4 Bathonian Bathonian 169.2 Bajocian Bajocian Middle 176.5 Aalenian Aalenian Oolitic Limestone 180.1 Member JURASSIC Toarcian Al Ayn Toarcian 189.6 Al Jil (4) Formation Pliensbachian Pliensbachian 195.3 Dil (1) Early Sinemurian Sinemurian Guwayza 201.9 T. Shu'ah (6) Hettangian Hettangian Formation 205.7 Rhaetian Rhaetian 209.6 220.7 Norian Norian Late Carnian Halobia Carnian 227.4 Radiolarian Limestone Tawi Sadh Ladinian Chert Mbr Mbr Ladinian Member

M. 234.3

TRIASSIC Anisian Anisian 241.7 Sst. and Shale Mbr

E. "Scythian" Lmst. and Shale Mbr "Scythian" 248.2 Ma

Zulla Formation Vertical Scale 100

m 0 Mixed Lithology: shale, Siltstone/Sandstone Radiolarian chert and shale Lime/Sandstone

Limestone (pelagic Silicified Limestone bivalves, ooids)

Fm/ Mbr internal time line Fm/ Mbr heterochronous boundary

Fm/ Mbr isochronous boundary Not exposed or tectonic contact (incomplete succession) Presumed Fm/ Mbr boundary

Figure 17: Stratigraphic correlation showing 20 well-dated sections across the Hamrat Duru Basin. The relationships between the different lithostratigraphic units are established by correlating the strata from one area to another based on lithologic similarities and stratigraphic positions. Lithologic similarities include the gross lithology (e.g. limestone, sandstone, shale and chert), distinctive clast or mineral assemblages and colour. Variations in the thicknesses (non- decompacted) are also shown. Simplified distal to proximal relationships across the Hamrat Duru Basin are shown in four cross-sections (A, B, C and D). The relative positions of the sections within proximal to distal transects are based on facies interpretations. The palinspastic reconstructions of the stratigraphic columns do not necessarily correspond to their present geographic position because of complex in-sequence and out-of-sequence thrusting (Bernoulli and Weissert, 1987; Cooper, 1988; Searle, 1985). Individual sections are part of a defined thrust slice.

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OUTCROP AREA C OUTCROP AREA D Southwest Northeast Southwest Northeast

proximal distal proximal distal Maastrichtian Maastrichtian Firq (17), Campanian W. Mu'aydin (18) Campanian Santonian Santonian Coniacian Coniacian Turonian Turonian Cenomanian Cenomanian Albian Nayid Albian Upper Formation Aptian Member Aptian Al Hammah Barremian Barremian range (24) Hauterivian Hauterivian Jabal Safra Kathmah (21) Valanginian (16) Zukayt (19) Valanginian Kadrah Berriasian Berriasian Bani Dafa'a (22) Tithonian Al Sawad Tithonian Lower (20) Kimmeridgian Member Kimmeridgian Oxfordian Sid'r Formation Oxfordian Callovian Callovian Bathonian Bathonian Bajocian Bajocian Aalenian Aalenian Oolitic Toarcian Limestone Toarcian Member Pliensbachian Pliensbachian Sinemurian Sinemurian Hettangian Hettangian Rhaetian Rhaetian Norian Norian Carnian Guwayza Carnian Formation Ladinian Ladinian Anisian Anisian "Scythian" "Scythian" Tawi Sadh Member

Vertical Scale 100

m 0

Zulla Formation

Gulf of Oman Hawasina Window Muscat N Neoautochthonous 0 25 1 km

4 2 5 Autochthonous A Autochthonous B Ibri 6 7 Semail Ophiolite 3 J. Akhdar Saih Hatat

17 20 8 Nizwa 18 19 B 22 9 13 14 C 21 10 Ibra D 11 24 16 Hawasina Local arrangement Nappes of the cross-sections and the profiles.

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of the rocks has almost disappeared in favour of green. In Wadi Bani Khalid (Figure 2: 26), however, red-coloured radiolarites and shales reappear at some intervals in the Carnian.

The transition to the overlying Halobia Limestone Member is gradational. It is marked by an increasing percentage of limestone beds or calcium carbonate in the silicified beds, a decrease of the preservation of the radiolarian tests, and a decreasing number of recognizable radiolarian tests. This suggests a decrease in radiolarian productivity and upwelling activity, and a drop of the calcite compensation depth (CCD).

The practically synchronous onset and disappearance of the radiolarian sedimentation in the Zulla Formation and the almost general change in colour in the entire study area suggest deposition of the Radiolarian Chert Member in a rather uniform basin with similar palaeoceanographic conditions. The exceptions in the general trend from red to green colours mentioned above (sections: 5, 24) might be related to submarine currents; since red-bedded cherts were sedimented in oxic conditions with stronger bo�om currents, and green or grey cherts in relatively stagnant conditions with weak bo�om currents (Douzen and Ishiga, 1993) colour reflects primarily the palaeoenvironment and is of only limited biostratigraphic value. The development of the radiolarian chert facies is most probably related to an intense upwelling activity (De Wever, 1988; De Wever and Thiébault, 1981; De Wever et al., 1995) and a reduced carbonate supply. During the Triassic the Hawasina Basin was part of the Neo-Tethys Ocean which was open towards the east. This general geometry is assumed to have resulted in a clockwise oceanic gyre like the one present today in the North Pacific, and promoted a strong upwelling activity (De Wever and Thiébault, 1981).

Hemipelagic siliceous productivity in the whole Hawasina Basin ceased between the early Norian and late Pliensbachian. The carbonate and subsequently the siliciclastic deposits of this interval suggest a shallowing of the basin and changes in the circulation pa�erns related to a much wider Neo-Tethys Ocean at that time (Stampfli et al., 2001). The siliceous beds occurring in this interval are represented only by spiculites with large sponge spicules, typical for a still deep but more proximal se�ing and indicating reworking by submarine currents.

Siliceous hemipelagic sedimentation and the upwelling activity started again in the late Pliensbachian when the Hamrat Duru Basin deepened again. In agreement with the global context, the sea floor was commonly poorly oxygenated during the Early and Middle Jurassic. As a result, almost all radiolarian rocks deposited during this time interval are green or grey in colour. There are only two local occurrences of red cherts, one in the late Pliensbachian-early Toracian of Qabil (2) and another one in the Bajocian of the Jabal Safra (21).

The hemipelagic sedimentation was temporarily interrupted by the input of mostly reworked shallow-water carbonate material during the deposition of the Oolitic Limestone Member. Carbonate input decreased rapidly or ceased during the Callovian with the reinstallation of upwelling conditions suggested by the lithology and biogenic contents of the Wahrah and Sid’r formations.

The Red Bedded Chert Member of the Wahrah Formation contains abundant radiolarians and few, small sponge spicules which is typical for a distal, pelagic facies. In contrast, the cherty limestone of the Lower Member of the Sid’r Formation usually contains abundant, large sponge spicules and radiolarians. This assemblage is characteristic of shallower waters, for example plateau sediments or sediments deposited on the continental slope. The facies of the Lower Member of the Sid’r Formation and the preservation of radiolarians in slightly silicified layers or in chert nodules strongly resemble the Maiolica limestone from the Southern Alps in northern Italy (Lombardian Basin) and from many other parts of the Neo-Tethys Ocean (Wieczorek, 1988). This implies similar palaeoceanographic conditions throughout the Neo-Tethys Ocean.

Taking into account the abundance of radiolarians and the frequency of chert beds, the climax of upwelling occurred in the late Tithonian-Berriasian. This is the time interval of maximum development of the red radiolarian cherts of the Wahrah Formation and of the silicified Maiolica- type limestones of the Lower Member of the Sid’r Formation representing resedimented periplatform oozes which possibly form small turbidite fans (Figure 18c). The radiolarian cherts and shales of the

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Siliciclastic depositional system Limestone Late Triassic Al Ayn Formation Mixed carb. /silicic. Silt- and sandstone Silicified limestone "Jabal Akhdar" Radiolarian chert Arabian Platform Sea Level Shale, cherty shale

"Saih Hatat"

Continental Crust

Hamrat Du 0 100 ru Basin Northwest km

Carbonate depositional system Middle Jurassic Oolitic Limestone Member of the Guwayza Formation

"Jabal Akhdar" Sea Leve l "Saih Hatat"

0 100 Northwest km

Radiolarian chert depositional system Late Jurassic/Early Cretaceous Lower Member of the Sid'r Formation and Wahrah Formation

"J. Akhdar" Sea Leve l

"Saih Hatat"

0 100 Northwest km Figures 18: Schematic scenarios illustrating the three main depositional systems of the Hamrat Duru Basin in their palaeogeographic context. (a) Late Triassic siliciclastic depositional system showing a siliciclastic and a mixed siliciclastic/carbonate fan system (Al Ayn Formation). (b) Carbonate depositional system of the Middle Jurassic Oolitic Limestone Member of the Guwayza Formation. (c) Radiolarian chert depositional system of the Late Jurassic Upper Member of the Sid’r and Wahrah formations. The scenarios are based on the facies associations discussed in Blechschmidt (2002). Arrows indicate dominant palaeocurrent directions.

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Wahrah Formation are true pelagites with minor evidence of currents. The radiolarian sedimentation in the Hamrat Duru Basin continued into the Barremian when another maximum of radiolarian productivity occurred. During the remaining time of the early Cretaceous and during the late Cretaceous, radiolarian productivity was less pronounced and was restricted to some short intervals, recorded in thin radiolarian-bearing silicified beds. In the Nayid Formation, the most frequent if not exclusive siliceous components are large sponge spicules suggesting a rather proximal environment and strong transport currents.

TECTONOSTRATIGRAPHIC AND BATHYMETRIC INTERPRETATION

Cooper (1986, 1990) concluded that the sedimentary characteristics of the Hamrat Duru successions reflect relative sea-level fluctuations, with significant carbonate input in the deep-marine basin during periods of platform flooding and high carbonate production on the stable platforms. Changes from high to low stands of relative sea level were accompanied by a significant reduction in carbonate production and increased input of siliciclastic sediments. Raised calcite compensation depths associated with high sea levels resulted in the deposition of siliceous sediments. During periods of low sea level, terrigenous clastics prograded across or by-passed the platform into the Hamrat Duru Basin.

A simplified comparison of the Mesozoic Arabian Plate sequence and the deep-marine sequences of the Hamrat Duru Basin and Batain Basin with the proposed standard curve (Haq et al., 1987; Vail et al., 1977, 1991) is shown in Figure 19. At this scale, a broad relationship between the long-term, sea-level cycles (second order: 3-50 My, Vail et al., 1991) and the evolutionary trends of the Mesozoic megasequences of the Arabian Platform and the Hamrat Duru Basin is clearly recognisable. The similar evolution of the successions of the Hamrat Duru Group in different outcrop belts points to a eustatic control of facies pa�erns.

Triassic Evolution (Zulla Formation, Al Ayn Formation)

The Early Triassic (Olenekian) dominance of carbonate material in the Hamrat Duru Basin (Limestone and Shale Member) is related to the presence of a coeval Arabian carbonate shelf which was already established by the Late Permian (Murris, 1980; Le Métour et al., 1995). Carbonate sedimentation ended and was replaced by the deposition of siliciclastics in the late Olenekian (Sandstone and Shale Member). The nearly coeval turnover (within biostratigraphic resolution) in different outcrop belts (Figure 2: Hawasina Window, Wadi Al Ayn, Wadi Bani Khalid) indicates an external control factor such as eustatic variation. The relatively small volume of mostly fine-grained, well-sorted sandstone can be related to a prograding delta complex during a period of rising sea-level and hinterland upli�. According to Bernoulli et al. (1990), the supply of siliciclastics might be connected to an Anisian sea-level drop during a third-order cycle (Figure 19). In the latest Anisian to earliest Norian interval, a continuous relative sea-level rise led to a deepening of the basin, reflected by the deposition of the Radiolarian Chert Member (Figure 19). The return to carbonate deposition (Halobia Limestone Member) during the early to middle Norian signals a deepening of the CCD related to a change in phyto- and zooplankton productivity and/or an increased supply of periplatform material (Bernoulli et al., 1990).

In comparison, the Triassic sequences of the Batain Basin (Sal Formation) (Immenhauser et al., 1998; Hauser, 2001; Hauser et al., 2001, 2002) and Hamrat Duru Basin (Zulla Formation) show a different lithostratigraphic development (Figure 19). The Sal Formation is subdivided inthree lithostratigraphic members including from base to top: the Mudstone Member (late Olenekian to middle Anisian), the Chert Member (late Anisian) and the Calcarenite Member (Ladinian to Norian). In contrast to the Zulla Formations, carbonates are more abundant in the Sal Formation and the Anisian sandstone facies is completely missing. However, cherts are also common in the Sal Formation and radiolarians extracted from these rocks reveal a late Anisian to middle Norian age (Hauser et al., 2001), representing the same time interval of radiolarite deposition in both, the Sal and Zulla formation. The general time-equivalent lithostratigraphic trends of both formations (i.e., Early Triassic limestone and mudstone sedimentation, late Anisian to early Norian occurrence of radiolarian chert, early Norian Halobia-bearing carbonate) therefore indicate a close relationship between the evolution of the Arabian Platform (Figure 19; Glennie et al., 1974; Le Métour et al., 1995) and slope (Maqam Formation of the Sumeini Group; Wa�s and Garrison, 1986) and its two adjacent

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ARABIAN PLATE DEEP MARINE BASIN Standard Schematic Lithology Schematic Lithology Schematic Lithology Schematic Lithology

a Curves After Arabian Plate Oman Subsurface Hamrat Duru Basin Batain Basin

Stage M Haq et al. (1987) (in general) Stratigraphy Stratigraphy Stratigraphy Group (Super) Series after Sharland H. Droste, (personal Hauser et al. (2001) System et al. (2001) communication, 2003) (Central Oman 200 50 0 M 150 100 West East Formation North Oman Formation Mountains) Formation North-Eastern Oman 65.0 Maastrichtian Simsima Fm 71.3 Campanian

83.5 Fiqa Fm Santonian Aruma Late 85.8

Coniacian Nayid 89.0 Turonian 93.5 12 Cenomanian 98.9 Natih Fm

Albian

Wasia Nahr Umr Fm ? 112.2 Aptian 9

CRETACEOUS Shu'aiba Fm

121.0 Wahrah Barremian Kharaib Fm Early 127.0 Lekhwair Fm Hauterivian 132.0 11

Habshan Fm Sid'r Valanginian Kahmah 137.0 Salil Fm Wahrah Berriasian Rayda Fm 144.2 8 Tithonian 117 150.7 Jubaila Fm Kimmeridgian

Late 154.1 Hanifa Fm Oxfordian 159.4 10 Callovian Tuwaiq Fm ? 164.4 Bathonian 7 Stratigraphic architecture ofHamratDuruGroup, Oman 169.2 Dhruma Fm Limestone Mbr Bajocian Sahtan Middle 176.5 Aalenian Upper Mafraq 180.1

JURASSIC Toarcian 6 189.6 Lower Mafraq Pliensbachian Guwayza 195.3 Guwayza Early Sinemurian 201.9 Hettangian ? ? 205.7 Rhaetian 5 Sandstone Mbr 209.6 Mahil Al (Minjur) Ayn ? Norian 4

Late 220.7 Carnian Calcarenite Mbr 3 227.4 Ladinian Jilh Fm Akhdar

234.3 Zulla

Sal Chert Mbr Mid. TRIASSIC Anisian 2 241.7 Sudair Fm Mudstone Mbr Olenekian 1

E. 244,8 Induan Khuff Fm 248.2 Figure 19: Standard curve a�er Haq et al. (1987) placed against the Arabian Platform lithostratigraphy (general and northern Oman subsurface), the Hamrat Duru Basin lithostratigraphy and the Batain Basin lithostratigraphy. Hamrat Duru Group: 1 - Limestone and Shale Member, 2 - Sandstone and Shale Member, 3 - Radiolarian Chert Member, 4 - Halobia Limestone Member, 5 - Al Ayn Formation, 6 - Tawi Sadh Member, 7 - Oolitic Limestone Member, 8 - Lower Member, 9 - Upper Member, 10 - Variegated Mudstone Member, 11 - Red Bedded Chert Member, 12 - Nayid Formation. Blechschmidt et al. Stratigraphic architecture of Hamrat Duru Group, Oman

deep-marine basins in Oman. These trends may be related to global features, including sea-level variations and circulation pa�erns in the southern Neo-Tethys.

The Al Ayn Formation, deposited during the latest Triassic, is possibly related to a global sea-level fall during a second order cycle (Figure 19) starting already during the deposition of the mixed siliciclastic/carbonate top portion of the Zulla Formation. This sea-level drop is also recorded by the occurrence of a coeval fluvial and coastal sandstone sequence on the Arabian Platform (Minjur Formation, Figure 19; Murris, 1980). A distinct stratigraphic gap of several million years in the early Liassic in the Wadi Saal section (Figure 6: 10) corresponds to a major sea-level lowstand around the Triassic-Jurassic boundary evident also in the carbonate platform of the northern Oman Mountains (Murris, 1980; Haq et al., 1987).

Jurassic and Cretaceous Evolution (Guwayza, Sid’r, Nayid formations)

The lithologic trend of the Early to Middle Jurassic Tawi Sadh Member of the Guwayza Formation is related to a gradual Jurassic sea-level rise mirrored by the stratigraphic evolution of the Arabian Platform (Figure 19). The shale and/or chert-dominated facies at the base of this member succeeded by a carbonate-producing system corresponds to the evolution of the Arabian shelf during flooding. This general trend is interrupted locally by the input of siliciclastics occurring in the upper part of this member below the Oolitic Limestone Member of the Guwayza Formation. This led to distinct lateral changes in facies and thickness of the Tawi Sadh Member. The highly variable amount of reworked platform material in this sandstone facies is a�ributed to prograding siliciclastics crossing the carbonate shelf. This resulted in mostly mixed sequences with either alternating siliciclastic and carbonate beds, or beds with mixed carbonate and siliciclastic components. In addition, the occurrence of slumping, massflows with large oversized intraclasts including oolitic calcarenite and calcilutite boulders in the most proximal sections and clastic dykes in the more distal sections, mark a tectonically active phase within the earliest Middle Jurassic passive margin history. The accumulation of the deep-marine Oolitic Limestone Member from the middle Bajocian to the early Callovian is directly related to the Jurassic sea-level rise and highstand system in a second-order cycle and corresponds to the growth of a stable Arabian carbonate shelf in Oman (Figure 19: Dhruma Formation, Murris, 1981; Sharland et al., 2001). The occurrence of mega-conglomerates, olistoliths and slump-controlled debris sheets in the proximal Hamrat Duru sections indicates tectonic activity leading to the collapse of the platform margin and/or fault-bounded highs in the basin (Tozer and Calon, 1990; Wa�s and Garrison, 1986). The Jurassic to Cretaceous slope deposits of the Mayhah Formation (Sumeini Group), which are also characterised by huge mass movements, reveal depositional conditions similar to those of the Oolitic Limestone Member of the Guwayza Formation (Wa�s and Blome, 1990). Strong tectonic activity during the Middle Jurassic led to a basin reorganisation recorded in the development of a distinctly NW-striking basin axis and a change in palaeocurrent directions from dominantly northwards to southeastwards in the distal facies. Occurrence of distinct internal cycles measuring up to several tens of metres in the Oolitic limestone Member (see also tripartite system by Cooper, 1989, 1990) are possibly related to relative sea-level variations of higher frequency (i.e., third order, 0.5 - 3 My, Vail et al., 1991). Furthermore, storm and/or tsunami controlled events also caused clastic inputs into the Hamrat Duru Basin during that time (Blechschmidt, 2002).

In the Batain Basin, the sedimentation of calcareous sandstone and terrigenous shale (Sandstone Member) during the latest Triassic and that of the sandy Guwayza Formation during the Early Jurassic indicates a similar evolution to that of the Al Ayn and Guwayza formations (Hauser, 2001; Hauser et al., 2001, Figure 19).

Thus, the sedimentary sequences record two main extensional tectonic phases (Le Métour et al., 1995): (1) the Permian phase which caused the break-up of northeastern Gondwana and the formation of the Arabian Platform and the Hamrat Duru Basin, and (2) the Late Triassic tectonic phase which caused major volcanic activity in the distal zones and the formation of new morphostructures including the Umar Basin. The Jurassic has been seen as a time of a relative stable, passive-margin phase without significant tectonic activity (Le Métour et al., 1995). According to these authors, sedimentation during the Jurassic was predominately controlled by eustatic changes with the development of a vast carbonate platform during the main Early Jurassic sea-level rise. The new data shown here, however,

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Southwest Northeast

Lower to Middle 10 3 2 Jurassic Guwayza Formation Base-of-slope Proximal to distal "turbidite" fan and Basin plain

Basin Axis

? Oceanic crust Arabian Plate

0 km 25 (vertical exaggeration approx. 3:1)

Section 10 Section 3 Section 2 Mid-Late Early Mid-Late Early Mid-Late Early Jurassic Jurassic Jurassic Triassic Creta. Triassic Creta. Triassic Creta. 0 0 0

100 100 100 Radiolarian Data 200 200 200

300 300 300

400 400 400

Thickness in metres 500 500 500

600 600 600

Cumulative 700 Tawi 700 Tawi 700 Tawi yn Formation yn Formation yn Formation

A Sadh Lower A Sadh Lower A Sadh Lower Nayid Formation Nayid Formation Nayid Formation Al Al Al Oolitic Limestone Member Oolitic Limestone Member Member Oolitic Limestone Member 800 Member Member 800 Member 800 Member Member Zulla Fm Guwayza Fm Sid'r Fm Zulla Fm Guwayza Fm Sid'r Fm Zulla Fm Guwayza Fm Sid'r Fm 900 900 900 240 220 200 180 160 140 120 240 220 200 180 160 140 120 240 220 200 180 160 140 120 Time (Ma) Time (Ma) Time (Ma) Figures 20: (a) Schematic cross-section of the Middle Jurassic northern Oman passive margin showing its block-faulted nature and the Hamrat Duru Basin. (b) Accumulation curves of three sections of the Oolitic Limestone Member of the Guwayza Formation (blue) representing a first approximation of subsidence rates. Curves are given without de-compaction (uncorrected). Note that subsidence/accumulation rates of the Oolitic Limestone Member are highest at the base of the slope associated with a basin axis parallel to the palaeomargin.

suggest that the “relatively stable“ evolution (Le Métour et al., 1995) of the Jurassic was interrupted by distinct phases of tectonic instability with upli� and erosion of the platform, block faulting and increased subsidence which caused deposition of conglomerates and olistoliths at the base of the slope (Figure 20). Furthermore, slope and platform instability during this time led to a reorganisation of the Hamrat Duru Basin geometry. Following the Middle Jurassic sea-level highstand the Callovian/ Oxfordian time is marked by a distinct drop in sea-level which resulted in reduced carbonate production on the Arabian Platform, locally marked by breaks in sedimentation (Figure 19 and Le Métour et al., 1995). In the Hamrat Duru Basin the Callovian/Oxfordian sea-level fall is recorded as an abrupt decrease of resedimented ooids, greater abundance of radialorian chert and spiculites as well as locally by the input of lithoclastic platform material (Sid’r and Wahrah formations).

In general, the Early to Middle Jurassic sediments of the Batain Basin reveal a similar evolution to that of the Hamrat Duru Basin with siliciclastic influx (uppermost Sal Formation/lower Guwayza Formation) and ooid-dominated upper Guwayza Formation with levels of radiolarian cherts of Middle Jurassic age (Hauser et al., 2001, 2002; Peters et al., 2001). Sea-level rise during the Late Jurassic-Early Cretaceous (Figure 19) and increased tectonic subsidence (Tithonian-Berriasian) led to a deepening of the Hamrat Duru Basin and also caused drowning of the Arabian Platform (Béchennec et al., 1990; Cooper, 1990; Le Métour et al., 1995). This resulted in decreased carbonate

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production and deposition of a Maiolica-facies on the Arabian Platform (Le Métour et al., 1995) and in the proximal Hamrat Duru Basin (Lower Member of Sid’r Formation) as well as in the formation of radiolarian chert in the distal part of the Hamrat Duru Basin (Wahrah Formation).

Both the Late Jurassic to Cretaceous radiolarian ribbon cherts of the Wahrah Formation of the Batain Group (Peters et al., 2001) and of the Wahrah Formation and Lower Member of the Sid’r Formation of the Hamrat Duru Group suggest an important palaeoceanographic turnover which led to a Tethyan-wide change from calcareous deposition to a radiolarian chert and/or silicified limestone- dominated facies. An Hauterivian-Barremian sea-level fall led to a re-establishment of the carbonate platform and/or ramp environments in the formerly drowned areas and increased the export of redeposited platform material (Upper Member of the Sid’r Formation) into the Hamrat Duru Basin (Le Métour et al., 1995). Similarly, on the continental slope, siliceous pelagic lithologies are overlain by calcarenite and calcirudite made of reworked Arabian Platform material deposited during this time span (Sumeini Group, Huwar Formation, Le Métour et al., 1995). A final steepening of the slope and increased basin subsidence resulted from the approach toward a north-dipping subduction zone (Robertson, 1987; Wa�s and Blome, 1990) possibly connected to an Albian-Cenomanian eustatic sea- level rise (Figure 19). This may have resulted in the accumulation of the mostly fine-grained, partially silicified limestone and chert at the base of the Nayid Formation. The high amount of large sponge spicules suggests a rather proximal slope environment for the Nayid Formation.

CONCLUSIONS

(1) The Mesozoic base-of-slope to basin plain deposits of the Hamrat Duru Group of the Oman Mountains are subdivided into six formations, separated from each other mostly by a rapid vertical change in lithofacies. New biostratigraphic data led to a more precise dating of these lithostratigraphic units of the Mesozoic Hamrat Duru sediments compared to previous studies. Moreover, the new biostratigraphic framework be�er discriminates time-equivalent facies belts throughout the Hamrat Duru Basin. This work forms the basis for forthcoming studies of the deposits of the southern Tethyan margin in Oman. A next step might be an improved time-stratigraphic correlation with the Arabian Platform sequence. (2) The Hamrat Duru Group represents a mixed carbonate/siliciclastic system punctuated by two distinct phases of high radiolarian productivity (late Anisian to early Norian and late Pliensbachian to Coniacian). Sedimentological features within the individual successions show that the dominating sedimentary processes were mass flows such as turbidity currents and debris flows originating from the nearby platform margin. The Hamrat Duru Basin was controlled by various types of submarine fan systems at the base-of-slope and the abyssal plain which are related to a complex passive margin evolution. (3) The Hamrat Duru megasequence also reflects sea-level changes relative to the Arabian Platform. A direct correlation between the proposed long-term cycles of global sea-level change (first order: 50+ My and second order: 3 - 50 My, Vail et al., 1991) on the evolution of the base-of-slope and abyssal plain deposits of the Hamrat Duru Basin is evident. (4) Increasing abundance of radiolarian chert and radiolarian-bearing silicified limestone records higher surface-water productivity that is possibly related to changes in palaeoceanographic circulation pa�erns. It is proposed that such changes in surface productivity caused basin internal lateral variations in shale and/or radiolarian chert distribution. (5) Besides the two main extensional phases (Permian and Late Triassic) which are extensively discussed in Le Métour et al. (1995), the Middle Jurassic of the Hamrat Duru Basin also records tectonic activity which finally led to the development of a distinctly NW-oriented basin axis and a change in palaeocurrent directions from dominantly northwards to southeastwards in the distal facies associated with the deposition of conglomerates, olistoliths and slumps. (6) The northern (Hamrat Duru Group) and eastern (Batain Group) Oman palaeomargins show a similar sedimentary evolution that is mainly related to Tethyan-wide palaeoceanographic changes and the processes acting on the Arabian Platform. Lithological differences between the Hamrat Duru and the Batain Group are restricted to the Triassic. During this time interval the Batain Group (Sal Formation) was dominated by carbonate deposition, and a sandstone facies is completely missing. In contrast, the coeval Zulla Formation of the Hamrat Duru Group is characterised by turbiditic sandstones, less carbonate and abundant radiolarian chert. From Late Triassic onward both basins show a comparable sedimentary evolution which continued up to the Early Cretaceous. Since the Late Jurassic the facies pa�ern of both basins was identical and reflects the climax of the oceanisation process of Oman´s passive palaeomargins.

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ACKNOWLEDGEMENTS

The present paper is a result of a geological research program of the University of Bern supported by the Swiss National Science Foundation (project No. 2000-050681). L. Krystyn was sponsored by the Austrian National Commi�ee for IGCP (proj. 467 Triassic Time). The authors thank the Ministry of Commerce and Industry, Sultanate of Oman, especially Dr. Hilal Al Azri, Director General of Minerals, for his hospitality and for logistic support during field work. Henk Droste and Adrian Immenhauser are thanked for helpful reviews that greatly improved the manuscript. The design and dra�ing of the final graphics was by Gulf Petrolink.

REFERENCES

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APPENDIX Overview of the radiolarian assemblages and their age mentioned in this contribution. A complete list may be ordered from the corresponding author.

Radiolarian assemblage E. sedecimporata (Rüst) Sample No. BR51a E. ultima Baumgartner and UTM Coordinates 526238/2515183 Sample No. BR20 Dumitrica Age: Berriasian UTM Coordinates 526238/2515183 Eucyrtidiellum ptyctum (Riedel and Acaeniotyle umbilicata (Rüst) Age : Late Bajocian-Early Sanfilippo) Acanthocircus furiosus Jud Bathonian Haliodictya (?) antiqua (Rüst) Alievium regulare (Wu and Li) Angulobracchia digitata Higumastra coronaria Ozvoldova Archaeodictyomitra apiarium (Rüst) Baumgartner H. aff.gratiosa Baumgartner A. excellens (Tan) Leugeo aff. parvispinatus Hull H. imbricata (Ozvoldova) A. minoensis (Mizutani) Levileugeo ordinarius Yang and Homoeoparonaella argolidensis A. tumandae Dumitrica Wang Baumgartner Archaeospongoprunum patricki Jud Palinandromeda depressa (De Wever Loopus aff.primitivus (Matsuoka Becus triangulocentrum Dumitrica and Miconnet) and Deviatus diamphidius (Foreman) Palinandromeda praecrassa Yao) Dicerosaturnalis dicranacanthos (Baumgartner) Mirifusus dianae (Karrer) (Squinabol) P. sognoensis Baumgartner Napora lospensis Pessagno D. longispinosus (Donofrio and Paronaella aff.kotura Baumgartner Palinandromeda cf. crassa Mostler) Parahsuum aff.natorense (El Kadiri) (Baumgartner) Ditrabs sansalvadorensis (Pessagno) Paronaella aff.mulleri Pessagno Paronaella kotura Baumgartner Emiluvia chica Foreman Podobursa aff.helvetica (Rüst) Paronaella mulleri Pessagno E. pessagnoi Foreman Teichertus aff.notus Hull Parvivacca blomei Pessagno and Hiscocapsa gru�erinki (Tan) Tetraditryma corralitosensis Yang Loopus yangi Dumitrica (Pessagno) Perispyridium ordinarium (Pessagno) Mirifusus dianae (Karrer) T. pseudoplena Baumgartner Podobursa polyacantha (Fischli) Obesacapsula bullata Steiger P. spinosa (Ozvoldova) Pantanellium aduncum (Parona) Sample No. BR23 Podocapsa aff.foremanae Yang P. squinaboli (Tan) UTM Coordinates 526238/2515183 Praeconosphaera cf. sphaeroconus P. tredecimporatum (Rüst) Age: Early-Middle Oxfordian (Rüst) Parapodocapsa furcata Steiger Angulobracchia biordinalis Protunuma costatus (Heitzer) Phalangites acus (Jud) Ozvoldova Ristola altissima (Rüst) Praecaneta cosmoconica (Foreman) Bistarkum femur (Li) Sethocapsa tripes Yang Pseudodictyomitra carpatica Cinguloturris carpatica Dumitrica Spongocapsula palmerae Pessagno (Lozynyak) Dicerosaturnalis angustus Svinitzium okamurai (Mizutani) Pseudoeucyrtis tenuis (Rüst) (Baumgartner) Syringocapsa spinellifera Pseudoxitus omanensis Dumitrica Emiluvia orea Baumgartner Baumgartner Sethocapsa leiostraca Foreman E. sedecimporata (Rüst) Teichertus catenarius (Ozvoldova) S. zweilii Jud Eucyrtidiellum takemurai Hull Tethyse�a mashitaensis (Mizutani) S. uterculus (Parona) Hexasaturnalis aff.suboblongus (Yao) Tetraditryma pseudoplena Spongosaturnalis breviaculeatus Higumastra inflata Baumgartner Baumgartner Donofrio and Mostler Homoeoparonaella argolidensis Tetratrabs zealis (Ozvoldova) Suna echiodes (Foreman) Baumgartner Triactoma blakei Pessagno Svinitzium depressum (Baumgartner) Obesacapsula morroensis Pessagno T. foremanae Muzavor Tethyse�a boesii (Parona) Pterotrabs arcubalista Dumitrica, Tetratrabs bulbosa Baumgartner T. mashitaensis (Mizutani) Baumgartner and Gorican Tritrabs casmaliaensis (Pessagno) Tritrabs ewingi (Pessagno) Ristola altissima (Rüst) T. exotica (Pessagno) Tethyse�a mashitaensis (Mizutani) Zhamoidellum ovum Dumitrica Sample No. BR52 Transhsuum brevicostatum UTM Coordinates 489020/2524022 (Ozvoldova) Sample No. BR36 Age: Oxfordian Triactoma blakei Pessagno UTM Coordinates 526238/2515183 Angulobracchia digitata Baumgartner Tritrabs casmaliaensis (Pessagno) Age: Late Tithonian Archaeospongoprunum imlayi T. ewingi (Pessagno) Archaeodictyomitra apiarium (Rüst) Pessagno Dicerosaturnalis dicranacanthos Emiluvia premyogii Baumgartner Sample No. BR29 (Squinabol) E. salensis Pessagno UTM Coordinates 526238/2515183 Emiluvia chica Foreman Eucyrtidiellum ptyctum (Riedel and Age: Early Kimmeridgian Eucyrtidiellum pyramis (Aita) Sanfilippo) Acastea cf. diaphorogona (Foreman) Loopus yangi Dumitrica Hexasaturnalis minor (Baumgartner) Angulobracchia biordinalis Mirifusus dianae (Karrer) H. aff. suboblongus (Yao) Ozvoldova Obesacapsula cetia (Foreman) Higumastra imbricata Ozvoldova Archaeodictyomitra minoensis O. morroensis Pessagno Mictyoditra decora (Rüst) (Mizutani) O. polyedra Steiger Napora deweveri Baumgartner Cinguloturris carpatica Dumitrica Podocapsa amphitreptera Foreman Podobursa helvetica (Rüst) Dicerosaturnalis angustus Protunuma costatus (Heitzer) P. rosea Hull (Baumgartner) Pseudodictyomitra leptoconica Pseudocrucella sanfilippoae D. trizonalis (Rüst) (Foreman) (Pessagno) Ditrabs sansalvadorensis (Pessagno) Pyramispongia barmsteinensis Pseudoeucyrtis firmus Hull Emiluvia chica Foreman (Steiger) Tetraditryma corralitosensis E. ordinaria Ozvoldova Ristola cretacea (Baumgartner) (Pessagno) E. pentaporata Steiger and Steiger Spongocapsula banala (Jud) Transhsuum brevicostatum E. salensis Pessagno Stichomitra doliolum Aita (Ozvoldova)

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T. maxwelli (Pessagno) Phalangites acus (Jud) Dicerosaturnalis dicranacanthos Tripocyclia jonesi Pessagno Savaryella guexi Jud (Squinabol) Tritrabs casmaliaensis (Pessagno) Spongosaturnalis breviaculeatus D. major (Squinabol) Zanola cornuta (Baumgartner) (Donofrio and Mostler) Mictyoditra columbarium (Renz) S. aff.multidentatus (Squinabol) Pantanellium squinaboli (Tan) Sample No. BR68 Stichocapsa pulchella (Rüst) Spongosaturninus squinaboli UTM Coordinates 501605/2499923 Suna echiodes (Foreman) (Donofrio and Mostler) Age: Late Beriassian Syringocapsa aff.vicentina Suna echiodes (Foreman) Acanthocircus furiosus Jud (Squinabol) Angulobracchia portmanni Tetriastrum aff.tenue Yang Sample No. BR81 Baumgartner Triactoma luciae Jud UTM Coordinates 501605/2499923 Becus triangulocentrum Dumitrica Tritrabs ewingi (Pessagno) Age: Late Hauterivian Bistarkum irazuense (Aita) T. exotica (Pessagno) Acaeniotyle umbilicata (Rüst) Crolanium bipodium (Parona) Xitus robustus Wu A. florea Ozvoldova Cyclastrum rarum Squinabol Acastea diaphorogona (Foreman) Deviatus diamphidius (Foreman) Sample No. BR73 Archaeospongoprunum patricki Jud Dicerosaturnalis dicranacanthos UTM Coordinates 501605/2499923 Aurisaturnalis cf. variabilis (Squinabol) Age: Early Valanginian (Squinabol) D. longispinosus (Donofrio and Acanthocircus furiosus Jud Cecrops septemporatus (Parona) Mostler) Acastea diaphorogona (Foreman) Cyclastrum planum Jud Dicroa periosa Foreman Angulobracchia portmanni Hemicryptocapsa agolarium Ditrabs sansalvadorensis (Pessagno) Baumgartner (Foreman) Emiluvia chica Foreman Becus triangulocentrum Dumitrica Mirifusus chenodes (Renz) E. pessagnoi Foreman Dicerosaturnalis dicranacanthos Parvicingula (?) usotanensis Fluegellium symmetricum Steiger (Squinabol) Tumanda and Steiger Dicroa periosa Foreman Podocapsa (?) imperialis Jud Hsuum feliforme Jud Emiluvia chica Forema Praecaneta longa (Jud) Milax adrianae Jud Halesium palmatum Dumitrica Pseudodictyomitra nodosocostata Pantanellium squinaboli (Tan) Hemicryptocapsa capita Tan Dumitrica Paronaella tubulata Steiger Homoeoparonaella aff.peteri Jud Pseudoeucyrtis tenuis (Rüst) Podobursa aff.quadriaculeata Paronaella tubulata Steiger Sethocapsa orca Foreman (Steiger) Pseudoeucyrtis tenuis (Rüst) S. trachyostraca Foreman Podocapsa amphitreptera Foreman Triactoma luciae Jud Spongotripus (?) satoi Tumanda Pseudoaulophacus (?) pauliani Jud Stylodictya titirez Jud Pseudocrucella (?) elisabethae (Rüst) Sample No. BR75 Suna echiodes (Foreman) Pseudoeucyrtis sceptrum Jud UTM Coordinates 501605/2499923 Svinitzium columnarium (Jud) P. tenuis (Rüst) Age: Late Valanginian Thanarla lacrimula (Foreman) Spongosaturnalis minispineus Yang Acastea diaphorogona (Foreman) Spongosaturninus minimus Angulobracchia portmanni Sample No. BR84 (Squinabol) Baumgartner UTM Coordinates 519340/2511690 Svinitzium compressum Archaeodictyomitra conica (Aliev) Age: Late Tithonian (Baumgartner) A. elegans (Tan) Acanthocircus furiosus Jud Tritrabs ewingi (Pessagno) Cecrops septemporatus (Parona) Acastea diaphorogona (Foreman) T. exotica (Pessagno Deviatus diamphidius (Foreman) Dicerosaturnalis dicranacanthos Dicerosaturnalis dicranacanthos (Squinabol) Sample No. BR69 (Squinabol) Ditrabs sansalvadorensis (Pessagno) UTM Coordinates 501605/2499923 D. major (Squinabol) Emiluvia pessagnoi Foreman Age: Late Berriasian-early Ditrabs sansalvadorensis (Pessagno) Halesium irregulare Steiger Valanginian Halesium biscutum Jud Katroma milloti Schaaf Acaeniotyle umbilicata (Rüst) Pantanellium squinaboli (Tan) Obesacapsula cetia (Foreman) Acanthocircus furiosus Jud Paronaella trifoliacea Ozvoldova Pseudodictyomitra carpatica Acaseta diaphorogona (Foreman) Pseudodictyomitra carpatica (Lozyniak) Acastea (?) glebulosa (Foreman) (Lozyniak) Spongosaturnalis breviaculeatus Alievium regulare (Wu and Li) Pyramispongia aff.barmsteinensis (Donofrio and Mostler) Angulobracchia portmanni (Steiger) S. horridus (Squinabol) Baumgartner Saitoum elegans De Wever Triactoma luciae Jud Archaeotritrabs gracilis Steiger Savaryella guexi Jud T. tithoniana Rüst Crucella collina Jud Spongosaturninus minimus Tritrabs ewingi (Pessagno) Cyclastrum rarum Squinabol (Squinabol) C. trigonum (Rüst) Syringocapsa vicentina (Squinabol) Sample No. BR88 Deviatus diamphidius (Foreman) Tethyse�a boesii (Parona) UTM Coordinates 519340/2511690 Dicerosaturnalis dicranacanthos Triactoma luciae Jud Age: Berriasian (Squinabol) Alievium regulare (Wu and Li) Dicroa periosa Foreman Sample No. BR77 Angulobracchia portmanni Emiluvia chica Foreman UTM Coordinates 501605/2499923 Baumgartner E. pessagnoi Foreman Age: Early Hauterivian Archaeodictyomitra excellens (Tan) Fluegellium symmetricum Steiger Acanthocircus furiosus Jud Deviatus diamphidius (Foreman) and Steiger Archaeospongoprunum patricki Jud Dicerosaturnalis dicranacanthos Halesium biscutum Jud Archaeotritrabs gracilis Steiger (Squinabol) Homoeoparonaella peteri Jud Aurisaturnalis variabilis variabilis Emiluvia chica Foreman Hsuum arabicum Dumitrica (Squinabol) E. hopsoni Pessagno H. mclaughlini Pessagno and Blome Bistarkum irazuense (Aita) Pantanellium aduncum (Parona) Katroma milloti Schaaf Cecrops septemporatus (Parona) P. tredecimporatum (Rüst) Pantanellium squinaboli (Tan) Crucella lipmanae Jud, C. remanei Parapodocapsa furcata Steiger Paronaella trifoliacea Ozvoldova Jud Podobursa triacantha (Fischli) P. tubulata Steiger Cyclastrum rarum Squinabol Podocapsa amphitreptera Foreman

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Praecaneta cosmoconica (Foreman) Pantanellium squinaboli (Tan) P. turbo Matsouka Pyramispongia barmsteinensis Praecaneta cosmoconica (Foreman) Saitoum levium De Wever (Steiger) Sethocapsa trachyostraca Foreman Sethocapsa funatoensis Aita Sethocapsa (?) concentrica (Steiger) Triactoma tithonianum Rüst Striatojaponocapsa plicara (Yao) S. leiostraca Foreman Svinitzium kamoense (Mizutani and Triactoma tithonianum Rüst Sample No. BR100a Kido) Tritrabs ewingi (Pessagno) UTM Coordinates 519340/2511690 Age: Coniacian-Early Santonian Sample No. BR139 Sample No. BR94 Alievium gallowayi (White) UTM Coordinates 576289/2531795 UTM Coordinates 519340/2511690 Dictyomitra formosa (Squinabol) Age: Middle-Late Bathonian- Age: Latest Berriasian?-Earliest Patellulla planoconvexa (Pessagno) Early Callovian, UAZ6-7 Valanginian Praeconocaryomma universa Acaeniotylopsis variatus triacanthus Acaeniotyle umbilicata (Rüst) Pessagno Kito and De Wever Acastea diaphorogona (Foreman) Pseudoaulophacus floresensis Archaeospongoprunum imlayi Angulobracchia heteroporata Steiger Pessagno Pessagno A. media Steiger Pseudodictyomitra sp. Hexasaturnalis aff.suboblongus (Yao) A. portmanni Baumgartner Higumastra imbricata (Ozvoldova) Archaeodictyomitra aff. Sample No. BR107 Mirifusus guadalupensis Pessagno pseudomulticostata UTM Coordinates 482424/2535125 Palinandromeda cf. depressa (Tan) Age: Early-Middle Bajocian, (De Wever and Miconnet) Archaeospongoprunum patricki Jud UAZ3 Praewilliriedellum convexum (Yao) Archaeotritrabs gracilis Steiger Archaeodictyomitra exigua Blome Stichomitra (?) takanoensis Aita Becus triangulocentrum Dumitrica Canutus izeensis Pessagno and Svinitzium (?) kamoense (Mizutani Bistarkum irazuense (Aita) Blome and Cyclastrum rarum Squinabol Diacanthocapsa (?) operculi Yao Kido) Deviatus diamphidius (Foreman) Eoxitus baloghi Kozur Tetraditryma pseudoplena Dicerosaturnalis dicranacanthos E. hungaricus Kozur Baumgartner (Squinabol) Eucyrtidiellum unumaense (Yao) Transhsuum brevicostatum D. longispinosus (Donofrio and Japonocapsa fusiformis (Yao) (Ozvoldova) Mostler) Praewilliriedellum convexum (Yao) Tritrabs ewingi (Pessagno) Ditrabs sansalvadorensis (Pessagno) P. japonicum (Yao) Emiluvia chica Foreman Striatojaponocapsa plicara Sample No. BR140 E. pessagnoi Foreman (Matsuoka) UTM Coordinates 576289/2531795 Halesium biscutum Jud Svinitzium kamoense (Mizutani and Age: Late Bathonian-Early H. palmatum Dumitrica Kido) Callovian, Hsuum arabicum Dumitrica Transhsuum maxwelli (Pessagno) UAZ7 H. feliformis Jud T. hisuikyoense Isozaki and Matsuda Angulobracchia jasperensis Hull Katroma milloti Schaaf Unuma latusicostatus (Aita) Archaeospongoprunum imlayi Mictyoditra thiensis (Tan) Pessagno Paronaella trifoliacea Ozvoldova Sample No. BR117 Cinguloturris carpatica Dumitrica P. tubulata Steiger UTM Coordinates 489020/2524022 Emiluvia premyogii Baumgartner Phalangites acus (Jud) Age: Late Pliensbachian-Early Eucyrtidiellum ptyctum (Riedel and Podocapsa amphitreptera Foreman Toarcian Sanfilippo) Praecaneta longa (Jud) Canoptum sp., Canutus sp. E. unumaense (Yao) Pseudocrucella (?) elisabethae (Rüst) Pantanellium sp. Higumastra imbricata (Ozvoldova) Pseudoeucyrtis fusus Jud Praeconocaryomma immodica Mirifusus guadalupensis Pessagno P. tenuis (Rüst) Pessagno and Poisson Palinandromeda depressa (De Wever Pyramispongia barmsteinensis Praeconocaryomma spp. and Miconnet) (Steiger) Sontonaella sp. E. of Yeh (1987) Pseudoeucyrtis firmus Hull Saitoum elegans De Wever Sontonaella spp. Tetraditryma corralitosensis Savaryella guexi Jud Orbiculiforma aff.multifora Pessagno (Pessagno) S. spathulata Dumitrica and Poisson. Tritrabs casmaliaensis (Pessagno) Sethocapsa leiostraca Foreman Spongocapsula verbana (Parona) Sample No. BR131 Sample No. BR159 Spongosaturnalis multidentatus UTM Coordinates 489020/2524022 UTM Coordinates 576289/2531795 (Squinabol) Age: Early Toarcian Age: Late Hauterivian Spongosaturninus minimus Bistarkum rigidum Yeh Acastea diaphorogona (Foreman) (Squinabol) Broctus sp., Droltus sp. Alievium regulare (Wu and Li) Syringocapsa limatum Foreman Katroma megasphaera Yeh and Dicerosaturnalis dicranacanthos Tetratrabs radix Jud Cheng (Squinabol) Tritrabs aff.casmaliaensis (Pessagno) Pleesus aptus Yeh Pantanellium squinaboli (Tan) Xitus robustus Wu Podocapsa cf. abreojosensis Whalen Praexitus alievi (Foreman) and Pyramispongia barmsteinensis Sample No. BR97 Carter (Steiger) UTM Coordinates 519340/2511690 Pseudoristola obesa Yeh Sethocapsa orca Foreman Age: Valanginian Suna echiodes (Foreman) Angulobracchia aff.biordinale Sample No. BR138 Xitus normalis (Wu and Li) Ozvoldova UTM Coordinates 489020/2524022 Archaeodictyomitra apiarium (Rüst) Age: Bajocian, UAZ3-4 Sample No. BR383 A. tumandae Dumitrica Eoxitus hungaricus Kozur UTM Coordinates 463868/2573077 Dicerosaturnalis major (Squinabol) Eucyrtidiellum unumaense (Yao) Age: Late Bajocian-Bathonian D. trizonalis (Rüst) Japonocapsa fusiformis (Yao) Emiluvia lombardensis Baumgartner Emiluvia chica Foreman Praewilliriedellum robustum Eucyrtidiellum unumaense (Yao) Mirifusus dianae (Karrer) (Matsuoka) Parahsuum officerense (Pessagno and M. odoghertyi Jud Protunuma costatus (Heitzer) Whalen) Stichocapsa robusta Matsuoka

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Sample No. BR387 Samples No. BR416, BR417 Xiphostylus vallieri Pessagno and UTM Coordinates 463868/2573077 UTM Coordinates 463868/2573077 Yang Age: Kimmeridgian-Early Age: Late Pliensbachian-Early Zartus thayeri Pessagno and Blome Tithonian Toarcian Angulobracchia biordinalis Bagotum cf. maudense Pessagno and Sample No. BR457 Ozvoldova Whalen UTM Coordinates 603865/2525960 Archaeospongoprunum imlayi Bistarkum rigidum Yeh Age: Middle Bajocian Pessagno Canoptum anulatum Pessagno and Angulobracchia digitata Dicerosaturnalis minor Poisson Baumgartner (Baumgartner) Katroma bifurca Yeh Eucyrtidiellum unumaense (Yao) Emiluvia orea Baumgartner K. inflata Yeh Hsuum matsuokai Isozaki and E. pentaporata Steiger and Steiger Neowrangellium pessagnoi Yeh Matsuda Mirifusus chenodes (Renz) Orbiculiforma callosa Yeh Palinandromeda sognoensis Orbiculiforma lowreyensis Pessagno Pleesus aptus Yeh Baumgartner Paronaella centrodepressa Steiger and Pseudoristola obesa Yeh Parahsuum officerense (Pessagno and Steiger Stauromesosaturnalis deweveri Whalen) Podobursa spinosa Ozvoldova Kozur and Mostler Praewilliriedellum convexum (Yao) P. triacantha Fischli Stichocapsa robusta Matsuoka Ristola altissima (Rüst) Sample No. BR419 Stichomitra (?) takanoensis Aita Spongocapsula palmerae Pessagno UTM Coordinates 495050/2565965 Transhsuum brevicostatum Tripocyclia jonesi Pessagno Age: Late Anisian (Middle-Late (Ozvoldova) Tritrabs ewingi (Pessagno) Illyrian) T. hisuikyoense (Isozaki and T. imperfectas Hull Hindeosphaera spinulosa (Nakaseko Matsuda) and Nishimura) Sample No. BR388 Paroertlispongus multispinosus Sample No. BR464 UTM Coordinates 463868/2573077 Kozur and Mostler UTM Coordinates 603865/2525960 Age: Late Tithonian Pentactinorbis awaensis (Nakaseko Age: Late Tithonian?-Berriasian Archaeodictyomitra apiarium (Rüst) and Nishimura) Acanthocircus furiosus Jud A, excellens (Tan) Pseudoertlispongus mostleri Kozur Alievium picum Kiessling A. minoensis (Mizutani) Pseudostylosphaera japonica Archaeospongoprunum patricki Jud Artocapsa amphorella Jud (Nakaseko Becus triangulocentrum Dumitrica Cinguloturris cylindra Kemkin and and Nishimura) Dicerosaturnalis dicranacanthos Rudenko Tiborella florida (Nakaseko and (Squinabol) Deviatus diamphidius (Foreman) Nishimura) Katroma milloti Schaaf Dicerosaturnalis dicranacanthos Pantanellium aduncum (Rüst) (Squinabol) Samples No. BR437, BR438 Paronaella tubulata Steiger Ditrabs sansalvadorensis (Pessagno) UTM Coordinates 495050/2565965 Spongosaturnalis breviaculeatus Eucyrtidiellum pyramis (Aita) Age: Latest Carnian?-Early Norian Donofrio and Mostler Mirifusus dianae (Karrer) Canesium lentum Blome Obesacapsula cetia (Foreman) Capnodoce spp. Sample No. BR465 Paronaella tubulata Steiger Capnuchosphaera tricornis De Wever UTM Coordinates 603865/2525960 Podocapsa amphitreptera Foreman Capnuchosphaera spp. Age: Early Berriasian, UAZ5-8 of Protunuma costatus (Heitzer) Corum spp. Jud, Pseudodictyomitra cf. carpatica Mostlericyrtium sitepesiformis Tekin 1994 (Lozynyak) Paronaella sp. Acaeniotyle umbilicata (Rüst) Spongocapsula banala (Jud) Selenella triassica Tekin Alievium picum Kiessling Syringocapsa spinellifera Xiphotheca rugosa Bragin Dicerosaturnalis dicranacanthos Baumgartner (Squinabol) Tethyse�a boesii (Parona) Sample No. BR454 Emiluvia chica Foreman T. mashitaensis (Mizutani) UTM Coordinates 603865/2525960 E. ultima Baumgartner and Age: Middle Bajocian Dumitrica Sample No. BR415 Archaeohagiastrum longipes Mirifusus dianae (Karrer) UTM Coordinates 463868/2573077 Baumgartner Obesacapsula bullata Steiger Age: Late Barremian-Early Aptian, Ares cylindricus (Takemura) O. polyedra Steiger A. carinatus perforatus subzone Eospongosaturninus protoformis (Yao) Pantanellium squinaboli (Tan) Acaeniotyle umbilicata (Rüst) Hexasaturnalis hexagonus (Yao) Podocapsa amphitreptera Foreman Angulobracchia heteroporata Steiger H. suboblongus (Yao) Praecaneta cosmoconica (Foreman) Archaeodictyomitra lacrimula H. tetraspinus (Yao) Ristola cretacea (Baumgartner) (Foreman) Higumastra gratiosa Baumgartner Sethocapsa concentrica Steiger A. longovata Dumitrica Linaresia falloti (El Kadiri) S. leiostraca Foreman Archaeospongoprunum patricki Jud L. rifensis (El Kadiri) S. trachyostraca Foreman Aurisaturnalis carinatus perforatus Mirifusus praeguadalupensis Suna echiodes (Foreman) Dumitrica and Dumitrica-Jud Baumgartner Svinitzium columnarium (Jud) Cyclastrum infundibulum (Rüst) Palinandromeda depressa (De Wever Syringocapsa agolarium Foreman Dibolachras ty�hopora Foreman and Miconnet) Tethyse�a boesii (Parona) Dicerosaturnalis trizonalis (Rüst) P. sognoensis Baumgartner Thanarla praegu�a Dumitrica Mictyoditra columbarium (Renz) Pantanellium sincerum Pessagno and Tritrabs ewingi (Pessagno) Mirifusus chenodes (Renz) Blome Xitus robustus Wu Praeconosphaera sphaeroconus (Rüst) Parahsuum officerense (Pessagno and Pseudodictyomitra lanceloti Schaaf Whalen) Sample No. BR489 Sethocapsa orca Foreman Parasaturnalis diplocyclis (Yao) UTM Coordinates 565130/2536004 Suna hybum (Foreman) Praewilliriedellum convexum (Yao) Age: Callovian-Oxfordian Tethyse�a boesii (Parona) Saitoum levium De Wever Eucyrtidiellum takemurai Hull Spongosaturninus bispinus (Yao) Paronaella broenimanni Baumgartner Parvicingula dhimenaensis Baumgartner

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Pseudocrucella adriani Baumgartner Tetratrabs radix Jud Homoeoparonaella argolidensis Transhsuum brevicostatum Tritrabs ewingi (Pessagno) Baumgartner (Ozvoldova) Mirifusus guadalupensis Pessagno Tritrabs casmaliaensis (Pessagno) Sample No. BR560 Obesacapsula morroensis Pessagno UTM Coordinates 578108/2544420 Palinandromeda podbielensis Sample No. BR490 Age: Aalenian (Ozvoldova) UTM Coordinates 565130/2536004 Archaeohagiastrum cf. longipes Pterotrabs arcubalista Dumitrica, Age: Callovian-Oxfordian Baumgartner Baumgartner and Gorican Angulobracchia digitata Ares sp. Ristola procera (Pessagno) Baumgartner Elodium pessagnoi Yeh and Cheng Sethocapsa funatoensis Aita Bernoullius sp. Higumastra sp. Striatojaponocapsa conexa Crucella theoka�ensis Baumgartner Parahsuum (?) magnum Takemura (Matsuoka) Tritrabs casmaliaensis (Pessagno) Tripocyclia yaoi Yeh and Cheng Tetraditryma coldspringensis T. exotica (Pessagno) Triversus cf. spinifer Takemura Pessagno, Blome and Hull, Sample No. BR499 Sample No. BR591 Transhsuum brevicostatum UTM Coordinates 565130/2536004 UTM Coordinates 578108/2544420 (Ozvoldova) Age: Hauterivian Age: Aalenian-?Bajocian T. maxwelli (Pessagno) Angulobracchia portmanni Acaeniotylopsis variatus triacanthus Tripocyclia jonesi Pessagno Baumgartner Kito and De Wever Tritrabs casmaliaensis (Pessagno) Mirifusus dianae (Karrer) Archaeohagiastrum longipes Zanola cornuta (Baumgartner) Pyramispongia barmsteinensis Baumgartner (Steiger) Diacanthocapsa (?) cf. normalis Yao Sample No. BR637 Spongocapsula obesa Jud Dictyomitrella (?) kamoensis UTM Coordinates 504457/2537267 Syringocapsa limatum Foreman Mizutani and Kido Age: Late Albian-Cenomanian Williriedellum petersmi�ae Schaaf Hsuum matsuokai (Isozaki and Pseudodictyomitra Matsuda) pseudomacrocephala Sample No. BR536 H. primum Takemura (Squinabol) UTM Coordinates 581991/2513455 Hsuum (?) sp. 1 of Baumgartner et Rhoplaosyringium sp. Age: Late Tithonian-Berriasian al. 1995 Stichomitra communis Squinabol Alievium regulare (Wu and Li) Parahsuum officerense (Pessagno and Deviatus diamphidius (Foreman) Whalen) Sample No. BR648 Dicerosaturnalis dicranacanthos Transhsuum fukazawaense Sashida UTM Coordinates 526238/2515183 (Squinabol) Age: Bajocian Ditrabs sansalvadorensis (Pessagno) Sample No. BR597 Hexasaturnalis suboblongus (Yao) Pantanellium squinaboli (Tan) UTM Coordinates 503500/2571500 Parvicingula (?) dhimenaensis Triactoma tithonianum Rüst Age: Late Anisian Baumgartner Tritrabs ewingi (Pessagno) Paroertlispongus chinensis (Feng) Praevilliriedellum convexum (Yao) Spongocapsula cf. palmerae Pessagno Sample No. BR537 Sample No. BR598 Stichomitra (?) takanoensis Aita UTM Coordinates 581991/2513455 UTM Coordinates 503500/2571500 Age: Berriasian Age: Late Anisian Sample No. BR654 Acanthocircus breviaculeatus Paroertlispongus multispinosus UTM Coordinates 565130/2536004 Donofrio Kozur and Mostler Age: Late Turonian-Coniacian and Mostler P. rarispinosus Kozur and Mostler Alievium cf. praegallowayi Pessagno Acanthocircus furiosus Jud Pla�erium (?) contortum Dumitrica, Cryptamphorella conara (Foreman) Alievium picum Kiessling Kozur and Mostler Dictyomitra formosa Squinabol Archaeospongoprunum patricki Jud Pseudostylosphaera sp. sensu Bistarkum irazuense (Aita) Triassocampe spp. Pessagno Deviatus diamphidius (Foreman) Gongylothorax werbeeki (Tan) Emiluvia chica Foreman Sample No. BR616 Hemicryptocapsa polyhedra E. hopsoni Pessagno UTM Coordinates 503500/2571500 Dumitrica Katroma milloti Schaaf Age: Latest Carnian-Early Norian H. prepolyhedra Dumitrica Parapodocapsa furcata Steiger Capnuchosphaera lea De Wever Praeconocaryomma universa Saitoum elegans De Wever C. theloides De Wever Pessagno Tethyse�a boesii (Parona) C. tricornis De Wever Pseudodictyomitra tiara (Holmes) Mostlericyrtium sitepesiformis Tekin Squinabolum fossile (Squinabol) Sample No. BR552 Spongostylus carnicus Kozur and UTM Coordinates 581991/2513455 Mostler Sample No. BR655 Age: Berriasian Syringocapsa turgida Blome UTM Coordinates 565130/2536004 Acanthocircus furiosus Jud Xiphotheca karpenissionensis De Age: Late Norian-Rhaetian Angulobracchia portmanni Wever Paelospongia turgida Mostler Baumgartner Pentactinocarpus cf. sevaticus Kozur Archaeodictyomitra excellens (Tan) Sample No. BR627 and Mostler Dicerosaturnalis dicranacanthos UTM Coordinates 504457/2537267 (Squinabol) Age: Late Callovian?-Oxfordian Sample No. BR704 Emiluvia chica Foreman Acaeniotylopsis variatus triacanthus UTM Coordinates 489020/2524022 Praecaneta cosmoconica (Foreman) De Wever and Kito Age: Late Bajocian-Early Praeconosphaera sphaeroconus (Rüst) Cinguloturris carpatica Dumitrica Bathonian Pseudoeucyrtis fusus Jud Dicerosaturnalis angustus Archaeodictyomitra rigida Pessagno Pseudoeucyrtis tenuis (Rüst) (Baumgartner) Praewilliriedellum convexum (Yao) Suna echiodes (Foreman) Emiluvia orea Baumgartner Praewilliriedellum ? spinosum Kozur Svinitzium depressum (Baumgartner) E. salensis Pessagno Spongocapsula sp. Tethyse�a boesii (Parona) Eucyrtidiellum takemurai Hull Striatojaponicapsa plicarum (Yao) Hexasaturnalis minor (Baumgartner) Transhsuum maxwelli (Pessagno)

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Sample No. BR727 Spongocapsula palmerae Pessagno Dicerosaturnalis dicranacanthos UTM Coordinates 548585/2493300 Tetratrabs zealis (Ozvoldova) (Squinabol) Age: Late Albian-Early Transhsuum brevicostatum Ditrabs osteosa Jud Cenomanian (Ozvoldova) Emiluvia chica Foreman Rotaforma mirabilis Pessagno T. maxwelli (Pessagno) Mirifusus dianae (Karrer) Spongosaturnalis venetus (Squinabol) Tripocyclia cf. jonesi Pessagno Pantanellium cf. berriasianum Stichomitra communis Squinabol Tritrabs casmaliaensis (Pessagno) Baumgartner T. ewingi (Pessagno) P. cf. squinaboli (Tan) Sample No. BR828 Paronaella tubulata Steiger UTM Coordinates 586090/2512975 Sample No. BR850 Pseudodictyomitra cf. carpatica Age: Bajocian UTM Coordinates 621930/2494940 (Lozyniak) Elodium sp. Age: Kimmeridgian Sethocapsa praeuterculus Aita Hsuum exiguum Yeh and Cheng Angulobracchia biordinale Ozvoldova Spongocapsula banala (Jud) Linaresia chrafatensis El Kadiri Archaeodictyomitra minoensis Triactoma cf. tithonianum Rüst Mirifusus praeguadalupensis (Mizutani) Tritrabs ewingi (Pessagno) Baumgartner Archaeospongoprunum cf. patricki Transhsuum breviaculeatum Jud Sample No. BR854 (Ozvoldova) Cinguloturris carpatica Dumitrica UTM Coordinates 621930/2494940 T. medium Takemura Crucella theoka�ensis Baumgartner Age: Tithonian Deviatus hipposidericus (Foreman) Alievium picum Kiessling Sample No. BR832 Emiluvia ordinaria Ozvoldova Cinguloturris cylindra Kemkin and UTM Coordinates 621930/2494940 E. pentaporata Steiger and Steiger Rudenko Age: Late Bathonian?-Callovian Hexasaturnalis aff.suboblongus (Yao) Dicerosaturnalis dicranacanthos Archaeospongoprunum imlayi Mirifusus dianae (Karrer) (Squinabol) Pessagno Olanda olorina Hull Emiluvia pessagnoi Foreman Cinguloturris carpatica Dumitrica Paronaella centrodepressa Steiger and Loopus yangi Dumitrica Eucyrtidiellum takemurai Hull Steiger Mirifusus dianae (Karrer) Hexasaturnalis minor (Baumgartner) Paronaella mulleri Pessagno Obesacapsula bullata Steiger H. aff. suboblongus (Yao) Protunuma costatus (Heitzer) O. cetia Foreman Higumastra imbricata (Ozvoldova) Ristola altissima (Rüst) Pantanellium squinaboli (Tan) Leugeo ordinarius (Wu and Li) Spongocapsula dumitricai Widz and Podocapsa amphitreptera Foreman Mirifusus dianae (Karrer) De Wever Praecaneta longa Jud M. guadalupensis Pessagno Staurolonche spathulata Steiger and Protunuma costatus (Heitzer) Obesacapsula morroensis Pessagno Steiger Pyramispongia barmsteinensis Palinandromeda podbielensis Stichocapsa pulchella (Rüst) (Steiger) (Ozvoldova) Triactoma blakei (Pessagno) Sethocapsa leiostraca Foreman Spongocapsula palmerae Pessagno Triactoma paramericana Pessagno Tritrabs rhododactylus Baumgartner Transhsuum brevicostatum and Yang (Ozvoldova) Tritrabs casmaliaensis (Pessagno) Sample No. BR855 T. maxwelli (Pessagno) Triversus cf. fastigatus Hull UTM Coordinates 621930/2494940 Tritrabs casmaliaensis (Pessagno) Age: Tithonian Wilvemia whiskeyensis Pessagno, Sample No. BR851 Archaeodictyomitra excellens (Tan) Blome and Hull, UTM Coordinates 621930/2494940 A. minoensis (Mizutani) Age: Kimmeridgian Bistarkum brevilatum Jud Sample No. BR836 Angulobracchia biordinale Ozvoldova Cinguloturris cylindra Kemkin and UTM Coordinates 621930/2494940 A. zeissi Steiger and Steiger Rudenko Age: Oxfordian Archaeodictyomitra apiarium (Rüst) Emiluvia chica (Foreman) Archaeospongoprunum elegans Wu Archaeospongoprunum patricki Jud E. pessagnoi Foreman Bernoullius dicera (Baumgartner) Cinguloturris fusiforma Hori Eucyrtidiellum pyramis (Aita) Cinguloturris carpatica Dumitrica Emiluvia cf. chica Foreman Obesacapsula cetia Foreman Emiluvia cf. orea Baumgartner E. pentaporata Steiger and Steiger O. rusconensis umbriensis Jud Eucyrtidiellum takemurai Hull Eucyrtidiellum ptyctum (Riedel and Praecaneta cosmoconica (Foreman) Hexasaturnalis minor (Baumgartner) Sanfilippo) Svinitzium depressum (Baumgartner) Mirifusus guadalupensis Pessagno Hexasaturnalis minor (Baumgartner) Triactoma tithonianum Rüst Palinandromeda crassa Mirifusus dianae (Karrer) Tricolocapsa campana Kiessling (Baumgartner) Paronaella cf. mulleri Pessagno Palinandromeda podbielensis Podobursa kandrica (Kocher) Sample No. BR858 (Ozvoldova) Podocapsa foremanae Yang UTM Coordinates 621930/2494940 Paronaella mulleri Pessagno Protunuma costatus (Heitzer) Age: Latest Tithonian?-Berriasian Saitoum cf. elegans De Wever Spongocapsula dumitricai Widz and Alievium picum Kiessling Tethyse�a mashitaensis (Mizutani) De Wever Archaeodictyomitra minoensis S. palmerae Pessagno (Mizutani) Sample No. BR845 Suna echiodes (Foreman) Archaeospongoprunum patricki Jud UTM Coordinates 621930/2494940 Teichertus cf. cavernosus Hull Artocapsa (?) amphorella Jud Age: Middle-late Oxfordian Tetratrabs bulbosa Baumgartner Deviatus diamphidius (Foreman) Archaeodictyomitra rigida Pessagno Triactoma blakei (Pessagno) Dicerosaturnalis dicranacanthos Archaeospongoprunum imlayi Tricolocapsa cf. campana Kiessling (Squinabol) Pessagno Tripocyclia cf. jonesi Pessagno Emiluvia chica Foreman Bernoullius dicera (Baumgartner) Tritrabs casmaliaensis (Pessagno) Hiscocapsa gru�erinki (Tan) Cinguloturris carpatica Dumitrica T. exotica (Pessagno) Hsuum feliformis Jud Hexasaturnalis minor (Baumgartner) Loopus yangi Dumitrica H. aff. suboblongus (Yao) Sample No. BR852 Mirifusus dianae (Karrer) Mirifusus dianae (Karrer) UTM Coordinates 621930/2494940 Neorelumbra tippitae Kiessling Olanda olorina Hull Age: Tithonian Pantanellium squinaboli (Tan) Paronaella mulleri Pessagno Acanthocircus furiosus Jud Parapodocapsa furcata Steiger Podobursa spinosa Ozvoldova Archaeodictyomitra excellens (Tan) Paronaella tubulata Steiger

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Pseudodictyomitra carpatica Pseudoristola nova Yang and Wang Mirifusus guadalupensis Pessagno (Lozyniak) Stichomitra (?) takanoensis Aita Transhsuum hisuikyoense (Isozaki Saitoum elegans De Wever Transhsuum brevicostatum and Matsuda) Sethocapsa kitoi Jud (Ozvoldova) Spongosaturnalis breviaculeatus Sample No. BR956 (Donofrio and Mostler) Sample No. BR895 UTM Coordinates 463868/ Svinitzium depressum (Baumgartner) UTM Coordinates 706511/2496352 2573077 Tethyse�a boesii (Parona) Age: Late Anisian (Middle-Late Age: Late Aalenian-Early Triactoma cf. tithonianum Rüst Illyrian) Bajocian Xitus robustus Wu Hindeosphaera spinulosa Bistarkum sp. (Nakaseko and Nishimura) Tricolocapsa sp. Sample No. BR862 Paroertlispongus diacanthus UTM Coordinates 621930/2494940 (Sugiyama) Sample No. BR1094/2 Age: Berriasian P. multispinosus Kozur and Mostler UTM Coordinates 569514/ Acanthocircus furiosus Jud Spongosilicarmiger italicus Kozur 2538712 Alievium picum Kiessling and Mostler Age: Late Bajocian-Early Angulobracchia portmanni Tiborella florida austriaca Kozur, Bathonian Baumgartner Krainer and Mostler Linaresia chrafatensis El Kadiri Archaeodictyomitra apiarium (Rüst) Striatojaponocapsa plicara (Yao) Archaeotritrabs gracilis Steiger Sample No. BR929 Tetraditryma sp. Cinguloturris cylindra Kemkin and UTM Coordinates 706511/2496352 Tritrabs ewingi (Pessagno) Rudenko Age: Latest Carnian?-Early Norian Deviatus diamphidius (Foreman) Capnodoce anapetes De Wever Sample No. BR1120, BR1121 Dicerosaturnalis dicranacanthos C. sarisa De Wever UTM Coordinates 569514/ (Squinabol) Capnuchosphaera constricta (Kozur 2538712 Emiluvia chica Foreman and Mock) Age: Late Pliensbachian?-Early E. pessagnoi Foreman C. crassa Yeh Toarcian Eucyrtidiellum pyramis (Aita) C. tricornis De Wever Bagotum erraticum Pessagno and Hsuum raricostatum Jud Kahlerosphaera kemerensis adentata Whalen Loopus yangi Dumitrica Tekin Bistarkum bifurcum Yeh Mictyoditra thiensis (Tan) Mostlericyrtium sitepesiformis Tekin Jacus (?) anatiformis De Wever Mirifusus dianae (Karrer) M. striatum Tekin Canoptum anulatum Pessagno and Obesacapsula cetia (Foreman) Parentactinia globus (Sugiyama) Poisson Pantanellium squinaboli (Tan) Spongostylus tortilis Kozur and Formania sandilandensis Whalen Pseudodictyomitra carpatica Mostler and (Lozynyak) Trialatus robustus (Nakaseko and Carter Pyramispongia barmsteinensis Nishimura) Paracanoptum simplum Yao (Steiger) Tritrabs (?) trammeri (Kozur and Parasaturnalis diplocyclis (Yao) Ristola cretacea (Baumgartner) Mostler) Praeconocaryomma parvimamma Sethocapsa kitoi Jud Xiphotheca karpenissionensis De Pessagno and Poisson S. leiostraca Foreman Wever Pseudoristola obesa Yeh Spongosaturnalis breviaculeatus X. rugosa Bragin Trillus elkhornensis Pessagno and (Donofrio and Mostler) Blome Stichomitra doliolum Aita Sample No. BR942 Tricolocapsa (?) campana Kiessling UTM Coordinates 470315/2555220 Sample No. BR1131 Age: Latest Bathonian-Early UTM Coordinates 569514/ Sample No. BR876 Callovian 2538712 UTM Coordinates 462334/2558546 Angulobracchia cf. digitata Age: Aalenian?-Early Bajocian Age: Middle Bathonian-Early Baumgartner Acaeniotylopsis variatus triacanthus Callovian, UAZ6-7 Archaeospongoprunum imlayi Kito and De Wever, Archaeospongoprunum elegans Wu Pessagno Eucyrtidiellum unumaense (Yao) Cinguloturris carpatica Dumitrica Higumastra imbricata (Ozvoldova) Hsuum primum Takemura Gongylothorax sakawaensis Matsuoka Leugeo parvispinata Hull Hsuum sp.1 in Baumgartner et al., 1995

Overview of the conodont assemblages and their age mentioned in this contribution.

Conodont assemblage Sample No. BC351 Sample No. BC769 Sample No. B C347 UTM Coordinates 503500/2571500 UTM Coordinates 495050/2565965 UTM Coordinates 498805/2568647 Age: Early Norian Age: Middle Scythian (Olenekian/ Age: Middle Norian Epigondolella cf. quadrata Orchard Smithian) Epigondolella slovakensis (Kozur and Scythogondolella milleri (Müller) Mostler) Sample No. BC353 Neospathodus spathi Sweet UTM Coordinates 503500/2571500 Ellisonia triassica (Müller) Sample No. BC349 Age: Early-Middle Triassic Ellisonia sp. UTM Coordinates 503500/2571500 (Scythian- Age: Early Norian Anisian) Sample No. BC767 Epigondolella triangularis (Budurov Ellisonia sp. UTM Coordinates 495050/2565965 and Age: Early Norian Stefanov) Sample No. BC355 Epigondolella cf. triangularis UTM Coordinates 495050/2565965 (Budurov and Stefanov) Age: Early-Middle Triassic (Scythian-Anisian) Ellisonia teicherti Sweet

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ABOUT THE AUTHORS

Ingo Blechschmidt is a Research Scientist at the Institute of Geological Sciences at the University of Bern, Switzerland. He received an MSc in Geology from the University of Jena in 1998 and a PhD from the University of Bern in 2002. His main fields of interest are the sedimentological and structural evolution of mixed carbonate-siliciclastic deep-marine systems. For the past four years Ingo has been mainly involved in basin analysis research including 3-D reconstructions of facies patterns and the stratigraphic architecture of the allochtonous sedimentary units from the Hawasina Complex, Oman Mountains. [email protected]

Paulian Dumitrica is a Consulting Micropalaeontologist specialising in the taxonomy and biostratigraphy of siliceous microfossils (radiolarians, silicoflagellates and ebridians), and Associate Researcher at the University of Lausanne. He previously worked as a Micropalaeontologist at the Geological Institute of Romania in Bucharest until 1993. Paulian holds a PhD in Miocene Silicoflagellates from the University of Bucharest. Since 1994, in collaboration with the University of Bern, he has been deeply involved in the biostratigraphy of the Mesozoic formations from Oman. [email protected]

Albert Matter is Professor Emeritus at the University of Bern from where he received his PhD in Geology in 1964. His areas of interest include sedimentology, groundwater hydrogeochemistry and clastic diagenesis. Since 1967 Albert has been working in Oman, partly in cooperation with Petroleum Development Oman. Currently he is involved in sedimentological studies in Oman and in a palaeoclimate project which aims to develop palaeoclimate records of variation in Monsoon rainfall in Oman, Yemen and Saudi Arabia during the Pleistocene and Holocene. albert.ma�[email protected]

Leopold Krystyn is Professor of Palaeontology at Vienna University. He is a specialist in Mesozoic ammonoids and in Triassic conodonts with special emphasis on the refinement of the Triassic time scale. Other research interests are the Triassic magnetobiochronology and the palaeo (bio) geography of the early Neo-Tethys as well as the sedimentary history of its margins. He is a member of the Subcommission on Triassic Stratigraphy, chairman of the Norian-Rhaetian boundary working group and co-leader of IGCP project 467. [email protected]

Tjerk Peters is Emeritus Professor at the University of Bern, from which he received a PhD in 1963. Since 1968 he has worked in the Oman Mountains. Tjerk’s research projects on the regional geology of the allochthonous magmatic, sedimentary and metamorphic rocks on the northern and eastern edge of the Arabian continental margin are aimed at the tectonic-magmatic evolution of the Southern Tethys and Western Indian Ocean. [email protected]

For additional information about the authors see, Geoscientist Directory at www.gulfpetrolink.com

Manuscript Received March 22, 2003 Revised August 31, 2003 Accepted September 3, 2003 Press Version Proofread by Authors April 18, 2004 132

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