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Upper Carboniferous deposits of the Rod El-Hamal Formation are well exposed at Wadi Araba, north Eastern Desert, Egypt. The upper part of the Formation includes late Moscovian (Middle Pennsylvanian) mounds formed by filamentous microbes and phylloid algae. Phylloid algae are loosely accumulated and supported by micritic encrustations that were formed by filamentous microbes. The filamentous microbes growing perpendicularly to the phylloid algal surfaces produced concentrated areas of peloids-A (peloid-A aggregations). The spaces between the phylloid algal-microbial frameworks were filled with concentrated areas of peloids-B (peloid-B aggregations) oriented perpendicular to the phylloid algae surfaces. Microbial communities as well as phylloid algae constitute significant components in the late Moscovian buildups in the study area. Below and above the mound facies, the non-reefs carbonates of Unit (IV) of the Rod El-Hamal Formation are composed of molluscan wackestone, ferruginous-molluscan packstone, and bioclastic rudstone facies, reflecting shallow subtidal depositional environment. Pennsylvanian phylloid algal-bearing buildups were divided into Tethyan and Pangean buildups. The Tethyan buildups are widely distributed in the circum-equatorial tropical paleolatitudes. The Egyptian buildups exhibit similarity in the building organisms to those of the Tethyan, but with a higher proportion of microbialites. Therefore, the subtropical Egyptian buildups are regarded as a sub-type of the tropical Tethyan buildups.

Carbonate microfacies analysis was conducted on the exposed sediments of Dukul Formation from Yola Sub-basin of the Northern Benue Trough with an objective to reconstruct the paleodepositional environment. The study revealed four (4) major microfacies; oyster wackestone, ostracod oyster wackestone-packestone, bioclastic wackestone and bioclastic packestone microfacies. The microfacies assemblages indicate and affirm that the Dukul Formation sediments were deposited in shallow marine (mid-inner ramp) environment under suboxic to relatively anoxic conditions due to sea-level drop. This is further supported owing to the occurence of corals, brachiopods, bivalves and ostracods immediately below the mean fair-weather wave base (FWWB)

The aim of this study is to investigate the sedimentation environments and diagenetic processes of the Ibrahim Formation (Oligocene-early Miocene) in Zurbatiya, eastern Iraq. The Ibrahim Formation is comprised mostly of clayey micrite and skeletal grains composed of planktonic foraminifera, calcispheres, radiolaria, and benthic foraminifera. Glauconite and pyrite were documented in some restricted zones of this formation; they reflect quiet and reducing conditions. Radiolaria were identified in Late-Oligocene which was not known previously at this age regionally in carbonate formations of the Arabian Plate (AP). Mudstone, wackestone, and planktonic foraminiferal wackepackstone are the main microfacies that are affected by dissolution, cementation (granular), and replacement covering the age of the latest Eocene-Oligocene to the early-middle Miocene. Microfacies analysis indicates a basinal environment with a hemipelagic character of the deep shelf, toe-of-slope, and lower slope. Oligocene-Miocene outcrops have not been known previously in eastern Iraq although they have 160 m thick was first recorded in this study, whereas it was estimated as 56 m in the type section (well-1). Hence, the studied section is therefore suggested to be considered as a type section of the Ibrahim Formation. The Oligo-Miocene boundary is marked by restricted shallow-marine facies at the middle part of the formation indicating a short-term sea-level regression.

The Qamchuqa Formation was studied in Chwarqauran section, Sulaimanyia, Kurdistan region, Northeastern Iraq. The lithology of the formation contains limestone throughout the whole section except for one bed of dolomite at the Middle part. Twenty-four slides were prepared from 24 rock samples that were taken from this section to discriminate the petrography and fossil content. The petrographic study shows four main microfacies including lime mudstone, wackestone, packstone, and floatstone. Additionally, there are four sub microfacies: bioclast wackestone, miliolid wackestone, bioclast packstone and orbitolinid packstone. However, the fossil content shows the abundance of benthic foraminifera against the planktonic. All the microfacies indicate facies zone 7, 8 and 9A which reflect deposition in the platform interior between the tidal flat to the mid ramp and back reef environment

The Early Eocene succession of the Salt Range from base to top comprises the Nammal Formation, Sakesar Limestone and Chor Gali Formation. The Nammal Formation of Ypresian age is well exposed throughout the Salt Range. Detailed sedimentological and palaeontological analyses of the Nammal Formation were carried out, based on six stratigraphically important measured sections in the Salt Range. Lithologically, the formation is predominantly composed of interbedded nodular limestone, marl and shale. Wackestone, packstone, wackestone to packstone, dolomitic limestone and grainstone facies dominate the Nammal Formation in a fine-grained bioclastic matrix with abundant grains of larger benthic foraminifera. The diagnostic larger benthic foraminifera are recorded, which includes Nummulites mamillatus, Assilina spinosa, Assilina subspinosa, Assilina granulosa, Assilina laminosa, Discocyclina dispansa, Alveolina dolioliformis, Alveolina pasticillata, Alveolina globula, Lockhartia tipperi, and Lockhartia conditi. Stable carbon and oxygen isotopic signatures of the Nammal Formation designate shallow marine depositional environment. During Eocene a carbonate sequence developed in the Salt Range, lower boundary of which is marked as SB-II at the base of the Nammal Formation overlying the Palaeocene Patala Formation. The Nammal Formation presents the retrogradational facies suggesting the transgressive system tracts. The Sakesar Limestone shows agradational to progradational pattern of facies, which developed in highstand system tracts. The Chor Gali Formation possesses shallowing-upward trend by forming progradational shift of facies, and represents the falling stage system tracts. Early Eocene carbonate sequence is terminated by a regional sub-aerial unconformity SB-I marked between marine carbonate sequence of the Chor Gali Formation and the overlying non-marine clastic Miocene Kamlial Formation. Overall, the Nammal Formation presents shallow water neritic carbonate deposits containing larger benthic foraminifers.

The Hartha Formation is one of the important formations deposited during Late Campanian age. The present study deals with four boreholes (EB-53, 54, 55 and 56) within the East Baghdad oil field to diagnoses the microfacies and interpret the depositional environments. Six major microfacies were recognized in the succession of the Hartha Formation. Their characteristic grain types and depositional texture enabled the recognition of paleoenvironment. There are Orbitoides wackestone-packstone , Orbitoides - miliolid wackestone, Peloidal and Pellets - echinoderm wackestone to packstone, Peloidal wackestone to packstone, Pelletal wackestone to packstone, and Planktonic foraminifera wackestone-packstone. Four associations’ facies were recognized in this succession, which are shallow open marine, deep open marine, semi-resricted, and restricted. The distribution of these associations led to the recognition of three major depositional stages in the studied succession. The first stage is represented by the semi-restricted facies within the lower part of the Hartha Formation, which is characterized by Orbitoides - miliolid wackestone to the northwest direction and developed to shallow open marine and deep marine to the southeast direction. In the second stage, the sea level was rising to deposit the deep open marine facies represented by planktonic foraminifera wackestone-packstone microfacies above the semi-restricted facies ,where the succession became characterized by Peloidal and Pellets - echinoderm wackestone to packstone microfacies of restricted association. The third stage is represented by the continuation of sea level rise. This caused the building of carbonate ramp of Shiranish Formation above the shallow open marine of Hartha Formation with conformable surface.

This paper studies the microfacies, fossil contents, and the depositional environment of Wadi As Sir Limestone Formation exposed in the Al-tayyar area Zarqa Governorate, Northeastern Jordan. A total number of 35 samples were collected from a 30 m thick quarry section and used to prepare 35 thin sections. Some samples were washed over a 63 μm sieve, oven-dried at 50°C, sieved, and picked for benthic foraminifera analysis. Microscope analysis used to describe the microfacies and fossil contents. Four microfacies types and four lithological units are distinguished and described from the bottom to the top; the chalky unit (Unit-1) composed of bioclastic wackestone and biomicrite microfacies, and the dolomitic unit (Unit-2) immediately is existed above unit 1 composed dominantly of bioclastic mudstone and biomicrite microfacies. Marly limestone (Unit-3) is the following upwardly unit composed of bioclastic packestone and biosparite Microfacies, and the uppermost unit is limestone (Unit-4) consisted of bioclastic grainstone and biosparite microfacies. The fossil contents that were recognized in the studied thin sections and samples; bivalves, gastropods, pelecypods, cephalopods echinoderms, radiolarian, stromatoporoids, bone fragments, Saccaminopsis sp., Cibicidoides sp., Cibicides sp., Cyclammina sp., calcareous algae (Koninckopora and gymnocodiaceans), worm tubes, serpulids, and plentiful ostracods. The current study indicates that the Wadi As Sir Limestone Formation has deposited in a restricted circulation shallow shelf with low energy conditions most probably lagoonal environment.

Η περιοχή μελέτης καλύπτει ένα μέρος των ανθρακικών αποθέσεων της ζώνης Παξών στο νησί της Κεφαλονιάς το οποίο ανήκει στις Εξωτερικές Ελληνίδες και δομείται από δύο διαφορετικές γεωτεκτονικές ζώνες, την Προαπούλια ή ζώνη Παξών στα δυτικά και την Ιόνια ζώνη στα ανατολικά η οποία και επωθείται στην προηγούμενη. Πιο συγκεκριμένα, η περιοχή μελέτης τοποθετείται στις Ανατολικές περιοχές του Αίνου, Δυτικά της περιοχής της Σάμης, με γεωγραφικές συντεταγμένες της [ x , y ] σε προβολικό σύστημα κατά ΕΓΣΑ ‘ 87x:0205125 y:4235904. Η παρούσα διδακτορική διατριβή έχει ως αντικείμενο μελέτης τον προσδιορισμό του περιβάλλοντος απόθεσης, της ενέργειας του εκάστοτε περιβάλλοντος καθώς και της παλαιογεωγραφίας και της χωροχρονικής εξέλιξη της συγκεκριμένης ανθρακικής ακολουθίας με τη βοήθεια της Μικροφασικής ανάλυσης. Για λόγους ευκολίας η ανθρακική ακολουθία μελετήθηκε τμηματικά σε συνολικά 7 θέσεις, από οποίες και συλλέχθηκαν 300 περίπου δείγματα πετρωμάτων. Από τα δείγματα που συλέχθηκαν κόπηκαν συνολικά 300 λεπτές τομές με σκοπό την μικροφασική τους ανάλυση. Οι λεπτές τομές μελετήθηκαν σε πολωτικό μικροσκόπιο και ταξινομήθηκαν κατά τα ταξινομικά σχήματα των Dunham (1962) και Folk (1959) και στη συνέχεια πραγματοποιήθηκε λεπτομερής μικροφασική ανάλυση σύμφωνα με τους Flügel (2004), Wilson (1975) και Embry & Klovan (1971). Επιπλέον ο προσδιορισμός της ηλικίας της ανθρακικής ακολουθίας πραγματοποιήθηκε με τη βοήθεια των πλαγκτονικών και βενθονικών τρηματοφόρων καθώς και με τον προσδιορισμό ασβεστολιθικών ναννοαπολιθωμάτων όπου ήταν εφικτό. Τέλος, ολοκληρώνουμε με τη μελέτη του ολικού οργανικού άνθρακα και των ισοτόπων του οξυγόνου και του άνθρακα με σκοπό την αναγνώριση πιθανών Ανοξικών Επεισοδίων και παλαιοκλιματολογικών συνθηκών. Η λεπτομερής μικροφασική ανάλυση των ιζηματογενών δομών και των πρώιμων διαγενετικών χαρακτήρων οδήγησε στην αναγνώριση έντεκα λιθοφάσεων/μικροφάσεων (φάσεις απόθεσης και διαγενετικές φάσεις) στην περιοχή μελέτης. Αυτές μπορούν να ομαδοποιηθούν σε τέσσερεις ενότητες (βαθειά υποπαλιρροιακή ενότητα, υποπαλιρροιακή, μεσοπαλιρροιακή και επιπαλιρροιακή), και αντιπροσωπεύουν τα αντίστοιχα περιβάλλοντα απόθεσης/Φασικές ζώνες:ΦΖ 9/ Eβαπορίτες πλατφόρμας, συνθήκες ξηρού κλίματος και αυξημένη αλατότηταςΠεριβάλλον απόθεσης: Ανοιχτή πλατφόρμα, παλιρροιακή ζώνη, επιφανειακό αβαθές παράκτιο περιβάλλον απόθεσης.Μικροφάσεις: ΜΦΤ-19 Λεπτοστρωσιγενή wackestone που κατά περίπτωση εξελίσσεται σε πελσπαρίτη με παραθυροειδείς δομές με ελάχιστα απολιθώματα, ΜΦΤ-20 Στρωματολιθικός wackestone-bindstone με φύκη και ΜΦΤ-21 Μη απολιθωματοφόρο δολομικρίτης.ΦΖ 8/ Περιορισμένη πλατφόρμα Περιβάλλον απόθεσης: Αποτελεί ένα σχετικά ήρεμο περιβάλλον περιορισμένης πλατφόρμας. Μικροφάσεις: ΜΦΤ-16 Packstone με πελοειδή, κατά θέσεις ογκοειδή και βενθονικά τρηματοφόρα, και ΜΦΤ-18 Grainstone με βενθονικά τρηματοφόρα. ΦΖ 7/ Ανοιχτή πλατφόρμα χαμηλής ενέργειας υδάτωνΠεριβάλλον απόθεσης: Ανοικτή λιμνοθάλασσα, κόλποι και στενά πίσω από το άκρο της εξωτερικής πλατφόρμας, βάθους κυμαινόμενου από λίγα μέτρα έως δεκάδες μέτρα, όπου η κυκλοφορία των υδάτων είναι πολύ μέτρια. Μικροφάσεις: ΜΦΤ-8 Βιομικρίτης τύπου Wackestone με βενθονικά τρηματοφόρα, οστρακώδη και Thaumatoporella, ΜΦΤ-9 Floatstone με ολόκληρα θραύσματα ρουδιστών και φυκών σε μικριτική μάζα και ΜΦΤ-10 Βιοκλαστικός ασβεστόλιθος τύπου Wackestone με θραύσματα διαφόρων σκελετικών κόκκων όπως βενθονικά τρηματοφόρα, ρουδιστές και φύκη.ΦΖ 7/ Υφαλογενής σχηματισμό στα περιθώρια της πλατφόρμαςΜικροφάσεις: ΜΦΤ-7 Βιολιθίτες ρουδιστώνΦΖ 3/ 4 Όριο υφαλοκρηπίδαςΠεριβάλλον απόθεσης: ‘Όριο βαθειάς υφαλοκρηπίδας.Μικροφάσεις: ΜΦΤ-3 Πελαγικό wackestone, μικριτική ιλύς η οποία περιέχει διάσπαρτα globogerinids και ραδιολάρια.Ολοκληρώνοντας θα πρέπει να προσθέσουμε πως με βάση τα αποτελέσματα των δΟ18, σε συνδυασμό με την παρουσία των βενθονικών τρηματοφόρων, η θερμοκρασία της περιοχής μελέτης την συγκεκριμένη χρονική περίοδο Ανώτερο Τουρόνιο-Κατώτερο Μαιστρίχτιο είναι περίπου 25οC. Στη περιοχή μελέτης όλα τα δείγματα που μελετήθηκαν έχουν περιεκτικότητα σε οργανικό υλικό μέχρι 0,05 % το οποίο είναι πολύ χαμηλότερο από το ελάχιστο απαιτούμενο 0,7 % για να είναι πιθανή ή γένεση υδρογονανθράκων. Στη βάση όσων έχουν προαναφερθεί και σύμφωνα με τα δεδομένα που προέκυψαν ύστερα από τη μικροφασική και μικροπαλαιοντολογική ανάλυση της περιοχής μελέτης, καταλήξαμε στο γεγονός ότι η συγκεκριμένη ανθρακική ακολουθία αποτελεί ανθρακική απόθεση εσωτερικής περιορισμένης πλατφόρμας με περιθώριο (rimmed platform) ή πλατφόρμα τύπου ράμπα καθώς οι Μικροφασικοί τύποι που προσδιορίστηκαν και η κυκλική οργάνωση ταιριάζουν και στις δύο περιπτώσεις, ηλικίας Κονιάσιο (UC10) έως Μαιστρίχτιο (UC 15d-17) του Ανώτερου Κρητιδικού .

The Cauvery Basin at the southeastern tip of the Indian plate was an Albian to Danian marine embayment. The Dalmiapuram Formation is composed of bioclastic wackestone and coral boundstone. Benthic foraminifera and calcareous algae are relatively common in the Dalmiapuram Formation. The fossils support an age range of upper Albian to Cenomanian, which complements previously reported nannofossils that suggest an early Albian to Turonian age. The low diversity assemblage of foraminifera and calcareous algae and other organisms in the Dalmiapuram Formation is characteristic of a near-shore carbonate shelf or ramp. The low diversity and abundance of planktic species with coral and coral-algal buildups suggests more offshore conditions, probably within storm wave-base. The δ13C and δ18O values vary greatly. The absence of correlation between Mn and Sr indicates that these limestones retain their primary isotopic signatures. Gray shale/limestone unit has positive carbon isotope excursion (CIE) of ~ 0.8 to 1.0‰ that correlate with OAE 1c event. Similarly, significant positive CIE noticed in the lower part of the coral algal limestone is attributed to OAE 1d event. This suggests that oceanic conditions that created deep-water low oxygen conditions affected the shallow-water photic zone.

espanolThe Valles-San Luis Potosi Platform is part of an extensive carbonate platform system that rimmed the ancestral Gulf of Mexico during the middle (Albian) through Upper Cretaceous. The El Abra Formation consists of a shallow-water deposit; it contains a benthic foraminiferal assemblage that includes 18 species, which are described and illustrated in this paper. The studied successions from the upper part of the El Abra Formation were dated as mid-late Cenomanian. On the basis of these findings, two zones are proposed Pseudolituonella reicheli Assemblage Zone and Nezzazatinella picardi Interval Zone. The first Assemblage Zone is characterized by an abundant benthic foraminiferal association. It is overlain by the Nezzazatinella picardi Interval Zone where the species richness of the fora-miniferal assemblage is reduced and later disappears. The benthic foraminiferal demise is coincident with major sea-level changes and an increase in siliciclastic input from the hemipelagic deposit of the Soyatal Formation, which contains abundant pithonellids and r and r-k strategist planktic foraminifera (Whiteinella archaeo-cretacea Partial Range Zone). Two stratigraphically correlative facies have been recognized in the El Abra Formation: the Taninul and the El Abra Facies. A warm, shallow-water, open marine platform deposit (Taninul Facies) is inferred. It includes peloidal-foraminiferal packstone, packstone-grainstone, and packstone- wackestone. A restricted environment (El Abra Facies) can be deduced from the abundant miliolids and ostreids. The texture is a wackestone-packstone. Another microfacies (Soyatal Formation) consists of wackestone-packstone with an acme of pithonellids and the occurrence of r and r-k strategist planktic foraminifers deposited during the platform drowning. EnglishLa Plataforma Valles-San Luis Potosi es parte de un sistema de plataformas extenso que se encontraba bordeando el antiguo Golfo de Mexico en el Albiano hasta el Cretacico Superior. La caliza El Abra es un deposito de aguas poco profundas; esta contiene un conjunto de foraminiferos bentonicos que incluye 18 especies, que se describen e ilustran en este documento. Las sucesiones estudiadas de la parte superior de la Formacion de El Abra fueron datadas como del Cenomaniano medio- tardio; se proponen dos zonas (Zona de Conjunto Pseudolituonella reicheli y Zona de Intervalo Nezzazatinella picardi). La primera Zona de Conjunto se caracteriza por una asociacion abundante de foraminiferos bentonicos. Esta sobreyacida por la Zona de Intervalo Nezzazatinella picardi donde se reduce la riqueza de especies de las asociaciones de foraminiferos y luego desaparece. La desaparicion de foraminiferos bentonicos es coincidente con grandes cambios de nivel del mar y un aumento en el aporte de sedimentos desde el deposito hemipelagico de la Formacion Soyatal que contiene abundantes pithonelidos y foraminiferos planctonicos de estrategia r y r-k (Zona de Alcance Parcial (Whiteinella archaeocretacea)). Dos facies estratigraficamente correlacionables han sidoreconocidas en la Formacion El Abra: la Facies Taninul y la Facies El Abra. Se infiere un deposito de plataforma marina abierta de aguas calidas someras (Facies Taninul). Esta incluye un packstone peloidal con foraminiferos, packstone y packstone-wackestone. Un ambiente restringido (Facies El Abra) puede deducirse por los abundantes miliolidos y ostreidos. La textura de la roca es un wackestone-packstone. Otra microfacies consiste de un wackestone-packstone con un auge de pithonelidos y la presencia de foraminiferos de estrategia r y r-k depositados durante la inundacion de la plataforma (Formacion Soyatal).

WOS: 000471294100010, Ilerdian (early Eocene) carbonates in the northwestern Tosya region, northern Turkey, are characterized by porcellaneous larger benthic foraminifera; Glomalveolina, Alveolina, Orbitolites, Opertorbitolites and Cyclopertorbitolites are common in the southeastern Kastamonu region, in facies deposited on a low-gradient carbonate ramp. The inner ramp comprises of Miliolid-soritid wackestone, Soritid wackestone, Alveolinid-soritid wackestone-packstone, Alveolinid wackestone, Alveolinid-Nummulitid wackestone-packstone, algal wackestone, and Coralline algal pack-grainstone microfacies. The middle ramp deposits are composed of Alveolinid-nummulitid wackestone-packstone and Nummulitid wackestone-packstone microfacies. Overall, the succession reflects a long term deepening trend.

The carbonate platform deposits of the Angostura Formation are widely distributed in the central and eastern part of the Sierra de Chiapas, SE Mexico. The Angostura Formation contains a rich assemblage of foraminifera associated with mollusks (rudists, gastropods), corals, and dasycladacean green algae. A detailed foraminiferal study was carried out on samples from the El Coyol section of the Angostura succession. The studied section crops out in the El Coyol Hacienda located north of the Angostura dam, SE of the city of Tuxtla Gutierrez in Central Chiapas. The foraminiferal assemblage consists mostly of benthic larger foraminifera but minor pelagic influence is represented by the presence of a number of planktic foraminifera. The benthic foraminiferal association is taxonomically diverse, being composed of Chubbina jamaicensis Robinson, Chubbina macgillavry Robinson, Caribealveolina michaudi Pecheux, C. fourcadei Vicedo, Caus and Frijia, C. obesa (Fourcade and Fleury), Praechubbina breviclaustra Fourcade and Fleury, Omphalocyclus macroporus (Lamarck), Asterorbis rooki Vaughan and Cole, Vaughanina cubensis (Palmer), V. barkeri, Bronnimann, Sulcoperculina dickersoni (Palmer), S. globosa de Cizancourt, S. vermunti (Thiadens), Lepidorbitoides minima Douville, Orbitoides cf. O. apiculata Schlumberger, Planorbulina cretae (Marsson), Smoutina cruysi Drooger, and Nezzazatinella sp. In addition, the occurrence of Fleuryana adriatica De Castro, Drobne and Gusic, Rhapydionina cf. R. liburnica Stache, Cuneolina ketini Inan, Valvulina cf. V. triangularis d'Orbigny and Minouxia sp. is documented for the first time from the Angostura Formation. The planktic foraminifera are Rugoglobigerina macrocephala Bronnimann, R. cf. R. hexacamerata Bronnimann, R. rugosa (Plummer), Kuglerina rotundata (Bronnimmann), Muricohedbergella monmouthensis (Olson), Planoglobulina cf. P. carseyae (Plummer), Globotruncanita stuarti (de Lapparent), Globotruncanita pettersi (Gandolfi), Planoheterohelix globulosa (Ehrenberg), Pseudoguembelina sp., Macroglobigerinelloides prairielillensis (Pessagno) and the pithonellids Pithonella ovalis (Kaufmann) and P. sphaerica (Kaufmann). The age of the Angostura Formation in the studied section is late to latest Maastrichtian. A Chubbina jamaicensis Taxon Range Zone is proposed on the basis of the occurrence of the nominal taxon and foraminiferal association. The lithological and faunal evidence enable the paleoenvironment to be reconstructed. The microfacies (wackestone–packstone, wackestone–floatstone, wackestone, grainstone and packstone) as well as the foraminiferal assemblage suggest that the deposit was developed in a shallow water marine setting with low to moderate energy, with sporadic intercropping of an open platform deposit characterized by planktic foraminifera and pithonellids. The paleobiogeographical distribution of the foraminiferal association from the Angostura Formation contains cosmopolitan genera as well as endemic forms of the Caribbean Province from the Tethys Realm.

The municipality of the town of Ulldecona (Catalonia) is notable for extensive quarrying activities, which exploit limestone, popularly named Stone from Ulldecona, for ornamental and building purposes. The Stone from Ulldecona, commercially known as Senia stone, is one of the most important ornamental and building stones quarried in Catalonia, and is used worldwide in all kinds of public and private buildings. Little is known about the geological nature of this stratigraphic interval of commercial value. Therefore, this study explores the geology of the Stone from Ulldecona in open pit quarries and natural outcrops. The Stone from Ulldecona consists of limestones of upper lower Aptian age, including wackestone, packstone and grainstone textures containing peloids, miliolids, Palorbitolina lenticularis, Orbitolinopsis simplex, Paracoskinolina maynci, Lithocodium aggregatum, Choffatella decipiens, Salpingoporella muehlbergi, Chondrodonta, Toucasia carinata, Polyconites sp. and Mathesia darderi. These platform carbonates rich in orbitolinids and rudists belong to the Villarroya de los Pinares Formation of the Maestrat Basin. Locally, the limestones are highly bioturbated and/or dolomitized. Dolomitic limestones, calcitic dolostones and dolostones are stratabound tabular geobodies with thicknesses of up to 60 m. Dolomitic limestones and calcitic dolostones corresponding to initial and intermediate stages of dolomitization mainly exhibit isolated euhedral dolomite crystals or idiotopic mosaics. Dolostones (advanced dolomitization stages) are sucrose, exhibit vacuolar and cave porosities, and are characterized by idiotopic and hypidiotopic mosaics, which indicate temperatures lower than 50-60 °C during dolomitization. Dolomite textures are mainly fabric-destructive and pervasive, but locally retentive and/or selective fabrics also occur. The limestones of the Villarroya de los Pinares Formation, the underlying marls of the Forcall Formation and the overlying marls and platform carbonates of the Benassal Formation examined can be arranged into two high-rank, low-frequency transgressive-regressive sequences. Similar coeval long-term transgressive-regressive trends have been reported from other basins, indicating that eustatism largely controlled accommodation of the Aptian succession studied in Ulldecona.

The Lower Cretaceous limestone of the Qamchuqa Formation (QF) in the studied area is located in the northeastern limb of Piramagroon Anticline, Sulaymaniyah Governorate, northeastern Iraq. A section is sampled and 103 samples are collected. From these samples, 106 thin sections are prepared for petrographic analysis under binocular and polarizer microscopes. Qamchuqa Formation is usually mostly dolomitized and microfossils are totally or partially destroyed, but fortunately, the studied section is affected by dolomitization only in the upper part, the lower and middle parts are not dolomitized and are rich in well-preserved microfossils of benthic foraminifera with some algae and corals. The purpose of this study is to determine the microfacies, depositional settings, microfossil assemblages, and age. Based on the petrographic studies of the thin sections, seven main types of microfacies are identified, which are represented by grainstone, packstone, wackestone, bindstone, boundstone, rudstone, and mudstone with other six subtypes. Analysis of these microfacies indicates that the Qamchuqa Formation is deposited in shallow water to open marine environments including intertidal, subtidal, lagoon, shoal, and middle ramp. Very rich benthic foraminiferal assemblages are studied and analyzed in thin sections. Twenty-four species of benthic foraminifers belonging to eighteen genera and one species of algae are recognized, of which sixteen species of benthic foraminifera are discovered for the first time. These fauna assemblages indicate the age of Early Hauterivian to Late Cenomanian.

Oil shale deposits of the mid-Eocene Wadi Shallala Formation in northern Jordan consist of organic-rich limestones and chalks. These organic-rich deposits are exposed at the surface near Wadi Ash Shajara, in a 12-m-thick outcrop. For this study, a total of 21 oil shale samples were analysed for bulk elemental geochemistry, inorganic geochemistry, organic geochemistry and microfacies analysis. Three microfacies types were recognised: pelagic mudstone/wackestone, foraminiferal packstone and bioclastic packstone/wackestone. The observed cyclicity of these microfacies in the study area indicates fluctuations in depositional conditions in Neo-Tethys during the mid-Eocene. A shallow-water, calm, restricted marine environment with limited water circulation and low energy currents evolved into a deeper-water environment with open circulation at or just below the wave base. Wadi Shallala Formation in Wadi Ash Shajara composes mainly of chalk (CaCO3 = ~92 wt%) with a TOC of up to 5 wt % and comprises abundant calcareous nannofossils, foraminifera and ostracods as well as non-clastic components like calcitic fragments. The sulphur content of the analysed samples is significant (1.24 wt %) and is associated with the organic matter. Redox-sensitive elements (Fe, Ni, Zn, S and Zr) are enriched in the oil shale samples, indicating an anoxic depositional environment fluctuating between euxinic and sub-euxinic. These fluctuations in depositional conditions of the basin are a result of many factors such as climate, and tectonisms affected deposition of oil shales during Middle Eocene time.

Anoxic sinkholes are unique geomorphological features of modern reef systems and in terms of “lake-like” sediment successions very special marine depositional environments. This study presents results of a sedimentological survey, which focuses on the “Great Blue Hole”, a circular Pleistocene karst cavity, situated in the shallow eastern lagoon of Lighthouse Reef Atoll (Belize, Central America). The investigated Blue Hole is located within the tropical cyclone belt and acts as consequence of its unique geomorphology as a giant sediment trap for both fair weather and storm sedimentation. As an important innovation step, we applied a multi-proxy approach based on textural, compositional and geochemical data to ensure a more reliable differentiation between sediments with fair weather and storm condition affiliation. Sediments having formed under both conditions were texturally categorized by determination of classical sedimentary parameters such as mean grain size and sorting. Sediment composition has been quantified in thin sections based on 40 samples discretely taken along a core from the bottom of the 125 m deep and 320 m wide cavern. Classification of sedimentary facies follows a modified scheme for unconsolidated carbonate sediments based on the Dunham nomenclature. Fair-weather sediments are generally finer than 20 μm and consist on average of 81% carbonate fine material, 12% Halimeda platelets, 3% coral fragments, 2% organic material, 1% mollusc shells, 1% foraminifer tests, and minor portions of coralline red algae and echinoderm plates (0–1%). Intercalated event bed sediments are coarse-silt to sand-sized (> 20 μm) and differ in terms of generally lower fine carbonate material amounts (50%) and increased abundances of over-washed Halimeda platelets (28%) and coral fragments (6%). Combined analyses of this study have revealed four primary sedimentary facies with affiliation either to the background (mudstone) or cyclonic event sedimentation (Halimeda wackestone, algae-rich packstone, coralgal rudstone) as well as a transitional sub-facies indicating storm-induced background overprinting (background wackestone). The striking compositional and textural differences of the Halimeda wackestone, algae-rich packstone and coralgal rudstone facies are considered to be another helpful (semi)-quantitative proxy to identify event beds of tropical cyclones in unconsolidated sinkhole sediment successions.

Modern reefs are considered important hot spots of biodiversity, but the analysis of the distribution of the invertebrate fauna across different reefal domains in ancient ecosystems can be challenging, because the fossil record is usually affected by strong taphonomic biases. The lower Eocene coral reef in the well-exposed outcrops of Ramals (Tremp-Graus Basin, southern Pyrenees, northeast Spain), preserve a high diversity of invertebrate groups, including decapod crustaceans. In Ramals the reefal facies belt is formed by a 100–200 m width E–W trending facies belt, including a set of closely spaced reef mounds up to five meters high, surrounded by the skeletal-rich (packstones, rudstones) inter-reef facies. These outcrops also allow the analysis of the fossil-association present in the inner and outer fore-reef facies, which are dominated by skeletal packstones with molluscs, foraminifera, corals, bryozoans, decapod crustaceans, echinoderms and vertebrate fragments (fishes and crocodiles). The reef framework consists of framestones with bioclastic wackestone to packstone matrix, including abundant colonial corals, as well as crustose red algae, encrusting foraminifera (Solenomeris), solitary corals and bryozoans. These reef mounds developed within the mesophotic zone, disturbed by the episodic activity of storm-induced waves. The distribution of decapod crustaceans across the different reefal domains was subjected to extensive paleontological and statistical analyses. The 911 specimens of decapod crustaceans include 41 species belonging to 21 families. Most crustaceans were concentrated in the periphery of the mound reefs and suggest that the core of the reef hosted the highest diversity and abundance of decapod crustaceans. Carpilioids were the most abundant group within the reefal facies belt, Ctenocheles sp. dominated the inner fore-reef areas, and Litoricola macrodactylus pyrenaicus showed preferences for outer fore-reef environments. Decapod crustaceans and associated faunas lived in close association with coral reefs but disappeared from the area after the demise of the reefs due to the increase of the depositional depth and fine terrigenous sedimentary input, illustrating how diversity changes at local scale due to extrinsic factors.

In the central-eastern Sirt Basin, enigmatic Intisar domal structures host significant hydrocarbon accumulations. These structures have been commonly interpreted as pinnacle reefs/bioherms occurring in the open-marine basinal environment. Generally, pinnacle reefs/bioherms are mainly characterized by in situ carbonates. The current study challenges the Intisar pinnacle reef/bioherm model by examining one of the domal structures in terms of biostratigraphy, microfacies and depositional environment. These structures were dated using larger benthic foraminifera, which yielded a Middle to Late Paleocene age (Selandian–Early Thanetian). Thirteen microfacies types representing different carbonate ramp environments ranging from outer ramp to inner ramp, were defined. Outer ramp deposits have been observed adjacent to the domal structure, represented mainly by wackestone with small benthic and planktonic foraminifera. The outer ramp deposits are most likely isochronous to the domal structures. The lower part of the domal structures is composed mainly of foraminiferal–algal–echinodermal packstones. The upper part is characterized by foraminiferal–algal–echinodermal packstones with intercalated microbialite–coral boundstones. The euphotic inner ramp deposits are preserved on the crest of the domal structure, consisting of grainstone and packstone rich in Glomalveolina. As a result of this study, the Intisar domal structures are seen as erosional relics of a carbonate ramp and no evidence for pinnacle reef/bioherm model was found.

The Miocene Pirabas Formation is of strategic importance for the hydrocarbon industry since it represents the onshore portion of larger offshore basins of Northern Brazil, including the Foz de Amazonas, the Para-Maranhao, Barreirinhas, Ceara, and the Potiguar basins of the equatorial margin of South America. The Pirabas Formation from the Aricuru outcrop (Para State) is a shallow-water mixed siliciclastic-carbonate deposit, comprising highly bioturbated wackestone and packstone. However, the impact of these biogenic structures on the reservoir quality of this formation has been overlooked. Here, our results show that pervasive Thalassinoides penetrating the rock matrix, result in remarkably improved porosity and permeability, thus, turning the Pirabas Formation in extremely favorable strata for fluid flow and storage. Since these bioturbated layers are likely to be common in the sub-surface counterparts of this formation, the hydrocarbon potential of these deposits is probably higher than previously expected. Also, considering that the offshore basins of Northern Brazil are directly related to the breakup of the African and American plates during Aptian-Albian, the exploratory interest in the correlated Guinea Gulf (Jubilee play) and French Guiana-Suriname Basin (Zaedyus play) need to be reconsidered. Overall, the results of this research highlight the importance of integrating ichnological datasets with reservoir characterization studies for more accurate reservoir quality assessments.

Campanian planktonic foraminifera and calcareous nannofossil biostratigraphy in the Degala segment positioned in the Bina Bawi anticline in the Kurdistan region, NE Iraq, have been described in detail. The study is concentrated on the Kometan and Shiranish formational boundary which has not been defined formerly. The top of the Kometan Formation is pronounced by sharp variations in lithology from the replication of well-bedded hemipelagic limestone to glauconitic chalky limestone, blue-colored marlstone, and argillaceous limestone of the superimposing Shiranish Formation. The Tethyan standardization of biostratigraphy based on calcareous nannofossil and planktonic foraminifera can be applied to the scrutinized sequences and categorized it into three planktonic foraminiferal (Globotruncanita elevata, Globotruncana ventricosa, and Globotruncana falsostuarti) biozones which are utterly equivalent to two calcareous nannofossil (CC20 and upper part of CC22) biozones. The consecutive Radotruncana calcarata planktonic foraminiferal biozone which locally might be equal to the Uniplanarius sissinghii (CC21) and lower part of the Uniplanarius trifidus (CC22) calcareous nannofossil biozones are lacking. It refers to absences of early Late Campanian which signify the Arabian Plate distinct tectonics and obduction of ophiolite across the northeastern border of Iraq. Moreover, four different microfacies were recognized that include foraminiferal mudstone, foraminiferal wackestone, glauconitic foraminiferal wackestone, and ferruginous foraminiferal mudstone which represent the deposition in open marine environment to submarine disconformity or diastems.

Summary The succession of the Eocene at the subsurface of october field (offshore Gulf of suez, Egypt) provides new data and contribution for the evolution of carbonate platform in the Eocene. Sidewall core samples that was obtained from Eocene carbonate sediments so far ascribed to the Thebes formation in the October hydrocarbon field in the Gulf of Suez (Egypt) was studied in terms of sedimentology, paleontology and depositional environment. The study of the Eocene carbonate facies in the October field revealed that 1) The succession is composed of pelagic foraminiferal limestone of varied color, containing abundant planktonic foraminifers and minor traces of chert. 2) Three microfacies are distinguished including wackestone of smaller planktonic foraminifera (53%), wackestone-packstone of planktonic foraminifera (39%) and packstone of planktonic foraminifera, 4) Nannoplankton and Foraminifers indicate that the studied succession is of early Eocene to middle Eocene age, 6) Lithology, fossil content and microfacies indicate a pelagic (basinal) depositional environment in an intraplatform basin at water depths of a few hundred meters. Finally, investigation of this Eocene succession showed that the studied section differs from the typical Thebes Formation concerning lithology, fossil content and facies, so a new Formation name has been introduced (Radwan Formation).

The role of microfacies and diagenesis was focused to assess the hydrocarbon potential of Eocene carbonate strata exposed in Sulaiman–Hazara mountain ranges. Thin- to thick-bedded Eocene limestone exhibits wackestone, packstone, mudstone, and grainstone texture and comprises larger benthic forams such as Nummulite, Assilina, Lockhartia, Discocyclina, Orbitolites and Operculina. The accumulation of the strata occurred in lagoon, inner to deeper shelf. The microfacies and textural variations revealed stable shallow shelf conditions in early Eocene. The marine sedimentation ceased in Hazara and Salt ranges, but Kohat and Sulaiman regions remained under water during middle Eocene. The deposition of Habib Rahi Formation in deeper shelf attests to local scale normal faulting due to the northward movement of the Indian Plate. The Eocene reservoir zones were sourced by Patala and Ghazij Formations and capped by thick cover of fluvial shale, establishing favourable conditions for stratigraphic traps. Thick limestone packages of foraminiferal wackestone/packstone and dolomitized/dolomitic wackestone microfacies are regarded as estimable targets for hydrocarbons exploration in the region. Several diagenetic processes were observed in the studied limestone which includes: micritization, dolomitization, neomorphism, cementation, mechanical and chemical compaction, fracturing and dissolution which were caused in marine, meteoric and burial diagenetic environments. Compaction was the main factor for the destruction of primary porosity along with cementation effect. The porosity in the limestone was significantly enhanced by late stage dissolution, fractures enclosed by calcite cement and dolomitization.

A more than 300 m thick succession of thick-bedded pink to grey limestone of the Norian – Rhaetian Khodz Group in the NW Caucasus serves to document the development of a temperate carbonate ramp during the final stages of the Cimmerian orogeny. Limestone samples were collected on the west side of Mt. Kolokolnia. The lower part of the Khodz Group contains bioclastic packstone microfacies composed largely of heterotrophic organisms: bryozoans, brachiopods, echinoderms, bivalves, small benthic foraminifers, juvenile ammonoids, agglutinated worm tubes, gastropods, ostracods and sponges. The upper part is comprised of layers of wackestone with frequent evidences of short episodes of emersion. Sponge spicules locally predominate; very few coral fragments also occur. Foraminiferal assemblages of the Khodz Group contain a high proportion of involutinids, including Licispirella violae (Blau), L. iranica (Senowbari-Daryan, Rashidi & Torabi), Coronaserra deminuta (Blau), Coronipora sp., ?Kristantollmanna bicarinata (Blau), Frentzenella perforata Rigaud, Blau, Martini & Rettori, ?Involutina turgida Kristan, ?Trocholina turris Frentzen, and T. ex gr. intermedia/umbo Frentzen, together with porcelaneous foraminifers such as Galeanella tollmanni (Kristan), and Decapoalina schaeferae (Zaninetti, Altiner, Dager & Ducret), which are typical reef dwellers in tropical platforms. Such faunal and foraminiferal association points to a shallow (photic zone) marine depositional environment. Trocholinids are among the most successful survivors of the end-Triassic crisis. The rich occurrence of diversified trocholinids in temperate Triassic seas at high latitudes within the western Eastern Laurasia palaeobiogeographic province suggests that: 1) temperate areas may have played an important role as refugia for marine life during this major biotic event, and 2) the importance of ocean acidification in the selective extinction of marine organisms is overestimated.

Stromatoporoids were abundant components of reefs, reef complexes and associated facies for ca. 100 million years between Middle Ordovician and end-Devonian time. A lot of environmental information stored in their skeletons may be used to develop: a) understanding of stromatoporoid growth controls; and b) interpretations of sedimentary environments in which they lived. General patterns of stromatoporoid distribution are well known, but knowledge of detailed interactions between stromatoporoids and their environments is poorly developed and under-used, potentially of great value in analysis of facies and palaeoecology. From a pool of several thousand specimens examined over four decades, this study identifies four key attributes of stromatoporoids that may be applied to enhance broad-scale knowledge of these fossils and their environments: 1) Substrates: Most stromatoporoids grew directly on wackestone to packstone substrates comprising micrite, clay and bioclasts. Evidence from the relationship between stromatoporoids and sediments demonstrates they were able to grow on soft substrates, but also leads to interpretation of partial lithification of the sea floor (and/or stabilisation by microbial filaments that may not be preserved) in mid-Palaeozoic carbonate facies, with potential implications for models of oceanic carbonate cycling. 2) Growth interruption: Almost all stromatoporoids examined show growth interruption, mostly caused by sedimentation and movement. Stromatoporoids normally recovered quickly and completely from interruption, thus were resilient to interruption events; 3) Associated organisms: Stromatoporoids have abundant associated organisms in two groups: (i) epibiotic encrusters and borers; and (ii) endobiotic organisms embedded in their structure, alive as the stromatoporoids grew. Epibionts used stromatoporoid surfaces that are presumed dead in almost all cases; some are associated with interruption events, but in most cases those were overgrown by successive stromatoporoid growth. Endobionts (mostly corals, plus spirorbids and others) are common to abundant in many stromatoporoid taxa. Stromatoporoid growth was little affected by presence of endobionts but in many cases (commonly restricted to certain stromatoporoid taxa) there was a complex biological interaction valuable in understanding controls on stromatoporoid development. 4) Growth form and taxonomy: Stromatoporoid assemblages are low diversity in almost all cases, regardless of age and facies, with two or three taxa much more abundant than the others. Some stromatoporoid taxa are limited to certain growth forms, thus taxonomic information is very important for facies analysis and palaeobiological interpretations. Stromatoporoids occur commonly with rugose and tabulate corals, both of which could also live on unconsolidated fine-grained substrates, therefore sediment-tolerance cannot be the only reason for stromatoporoid ability to outgrow corals in reefs. Arguments in the literature for photosymbiosis in both stromatoporoids and Palaeozoic corals are currently inconclusive for both fossil groups. Nevertheless, the sum of evidence indicates stromatoporoids were fast-growing, resilient and flexible benthic organisms, in a range of water depths, capable of dealing with soft substrates and largely unaffected by presence of endobionts. These characteristics are interpreted to have made stromatoporoids successful during mid-Palaeozoic time and valuable as tools in facies analysis. Recognition of the four key attributes which encompass all aspects of stromatoporoid growth controls makes palaeobiological study of stromatoporoids, in palaeoenvironmental reconstructions where they occur, readily accessible to researchers.

The present paper focuses for the first time on the trace fossils present in carbonate tests of the famous Egyptian middle Eocene larger foraminifer Nummulites gizehensis group. Bioerosion is represented by a unique diversified assemblage of seven ichnospecies belonging to four ichnogenera. Diagnostic drilling holes of the ichnogenus Oichnus are represented by the three ichnospecies O. simplex, O. paraboloides and O. asperus. Rare spiral galleries of Trypanites helicus and sinuous tunnels of Maeandropolydora sulcans were identified. Simple U-shaped borings of Caulostrepsis taeniola and Caulostrepsis isp. were also recognized within the studied nummulites. The reported drilling holes are attributed essentially to the predation of gastropods, whereas the other recognized galleries are assigned mainly to boring activities of the polychaete worms. Well-preserved tests with rare bioerosion and encrustation indicate deposition under a high rate of sedimentation and no prolonged transportation. Conversely, taphonomic characteristics of the bioeroded and encrusted nummulites can be used as good palaeoecological indictors of a deposition under low to fair rate of sedimentation. Coexistence of non-bioeroded and bioeroded/encrusted tests, common thick-bedded nummulite wackestone and packestone, predominated larger and flat Nummulites spp., and non-preferred imbrications are taken altogether with the reported ichnological assemblage to suggest that the nummulites were accumulated in situ and/or under weak influence of physical processes (storm and waves) in a shallow-marine environment, possibly middle to inner carbonate ramps.

A detailed, rock-based investigation of three Upper Cretaceous Eagle Ford Group cores situated behind, at, and downdip of the Lower Cretaceous Stuart City paleoreef-shelf margin in south Texas was conducted to understand stratigraphic, sedimentological, and geochemical relationships across this buried shelf margin. An understanding of how the Eagle Ford Group lithofacies vary across the paleoreef-shelf margin is currently lacking. We therefore examined a dip section of three cores across the antecedent shelf margin and delineated seven Eagle Ford lithofacies: (1) massive argillaceous mudstone, (2) massive to laminated foraminiferal lime wackestone, (3) radiolarian and foraminiferal dolomitic to lime packstone, (4) massive to bioturbated skeletal lime wackestone, (5) laminated foraminiferal lime packstone, (6) laminated inoceramid and foraminiferal lime grainstone, and (7) massive to bioturbated claystone. A basinward decrease in calcite from 60% to 48% is accompanied by an increase in clay minerals from 12% to 20%. The low-relief raised rim of the older, buried Stuart City paleoshelf margin may have acted as a barrier, dividing the Eagle Ford Group into two sedimentological systems: (1) a restricted drowned shelf to the north, and (2) an open-marine basinal setting to the south. The lower to upper Cenomanian Eagle Ford strata on the drowned shelf are cyclic and enriched in molybdenum, suggesting anoxic to euxinic water masses. The anoxic, open-marine, basinward strata are less cyclical and have a lower molybdenum (compared with the drowned shelf) content. Ash beds and gravity-flow deposits are rare south of the margin. A depositional model was constructed of the lower and upper Eagle Ford formations.

The city of Santa Rosa de Viterbo, Sao Paulo State, Brazil, contains an important geological and paleontological site that is part of the Parana Basin and presents one of the most significant records of Permian microbial life of southwestern Gondwana: the giant stromatolite field, with structures reaching 3 m high and 6 m wide. This work proposes a new overview of the paleoenvironment, focusing on the growth and development of microbial mats and microbialites. The characterization and association of nine facies were performed: intraformational breccia with wackestone matrix, intraformational breccia with grainstone matrix, packstone, wackestone, microbial mats, peloidal wackestone, laminated peloidal wackestone, laminated peloidal packstone and stromatolites. Four lithologic logs were correlated and used to interpret the history of the establishment of microbial communities during the episode of the Irati Sea closure. Field studies were carried out, thin sections were analyzed, and techniques such as SEM/EDS and Raman spectroscopy were applied for compositional analysis and to aid in the identification of associated fossils. This moment in the Parana Basin's evolution was important due to the noteworthy increase in rates of organic matter deposition and the significant proliferation of microbial life brought about by the closure of the Irati Sea. One hypothesis is that there was more than one attempt to establish microbial communities during the paleoenvironmental evolution, and success was achieved only after a decrease in water depth and energy of the depositional system, as well as after an increase in salinity. As a result of a reconfiguration of paleogeography in the Gondwana supercontinent, the closure of the Irati Sea significantly affected the development and establishment of microbial communities, which gave rise to extensive microbialitic structures such as those at Santa Rosa de Viterbo.

Microfacial investigations of the Lower Paleogene sediments were based on four sections of the passive Indian (Ladakh, Tingri County, Gamba County and Yadong County) and one of the active Asian continental margin (Zhongba County). Eleven microfacies from the Tethyan Himalaya (prefixed with P for passive continental margin) and four from the Xigaze forearc basin (prefixed with A for active continental margin) were observed. The distribution of fossil assemblages in the environment ranges from the tidal flat and restricted lagoonal part of the inner carbonate ramp to the outer carbonate ramp: (P1) green algae pack-/grainstone with small miliolids, (P2) bioclast grainstone, (P3) Rotaliidae packstone, (P4) Miscellaneidae-Rotaliidae-Nummulitidae pack-/grainstone, (P5) laminated and bioturbated mud- and grainstone, (P6) Alveolina wacke-/packstone with Soritidae, (P7) Nummulites-Alveolina-Orbitolites pack-/floatstone, (P8) Discocyclinidae-Nummulitidae pack-/floatstone, (P9) Rhodolith wacke-/packstone, (P10) mudstone with anhydrite nodules, (P11) planktonic foraminiferal wackestone, (A1) molluskan float-/rudstone, (A2) Nummulitidae wacke-/packstone, (A3) rhodolith wacke-/packstone, (A4) Discocyclinidae-Nummulitidae float-/rudstone. The correlation of our observations provides a detailed overview of the paleoenvironmental development and the sedimentary history of the eastern Neo-Tethyan Ocean, showing a deepening trend in two stages from Lower Paleocene to Lower Eocene.

Alatoconchidae, a unique bivalve family from the Permian, are characterized by a giant body size (up to 100 cm long), and unusual shell form with wing-like flanges and coarse prismatic outer layer of the shell wall. Palaeogeographically, they are restricted to low-latitude Tethyan and Panthalassan regions. However, the clams have not been previously been reported from South China even though this is one of the main, eastern Palaeotethyan terranes. Here we show that these giant clams were in fact widely distributed in South China, but they have been previously misidentified as phylloid algae. The present study verifies their occurrence in the region using reconstruction of shell forms from a series of transverse sections, as well as their characteristic shell microstructure. The alatoconchids occur commonly as coquina beds. Over thirty occurrences, ranging from the early Kungurian to probably the latest Capitanian in time, have been found. Based on detailed lithological and microfacies observation at more than ten fossil localities, most alatoconchid-bearing horizons (ABH) are autochthonous deposits, confined to medium- to thick-bedded limestones (often wackestone) of shallow water carbonate platforms. Two occurrences from an intra-platform basin are allochthonous deposits shed from the nearby carbonate platform by gravity flows, and featured by completely disintegrated fragments. Autochthonous and condensed accumulation of the fossil materials with great lateral persistence imply a gregarious habit of the clam, although slightly reworking might be involved. Its absence from high energy conditions, as well as the completeness of shell preservation, suggests it was not a reef dweller. To obtain gigantism in the tropical oligotrophic environment, alatoconchids may have harboured photosymbionts like present-day tridacnids, facilitated by its transparent shell texture, although this notion is challenged by Asato et al. (2017). Their association with calcareous algae and corals in the ABH indicates that the optimum belt of the clams is likely within the euphotic zone, but below that of calcareous green algae judging from the lithological succession and skeletal grain association.

The 420-m thick stratigraphic section of the Mural Formation that is exposed in the Cerro Pimas area of northern Sonora, Mexico, is composed of limestone lithofacies ranging from bioclastic wackestone to boundstone, whose biota is characterized by low diversity. Prominent age-diagnostic fossils are benthic foraminifera and long-ranging calcareous algae that indicate the Aptian/Albian boundary is close to the base of the Los Coyotes Member. The carbonates of this formation have negative to positive δ13C values (−4.63 to +2.6‰) and highly depleted δ18O values that range from −12.74 to −8.34‰. The absence of correlation between δ13C and δ18O values supports a primary marine origin for the δ13C values of these limestones. The carbon-isotopic curve of the Cerro Pimas stratigraphic section has well-defined δ13C segments (C8 – C15) that compare with published curves of similar age. In the lower part of the early Albian Los Coyotes Member, the presence of OAE 1b is indicated by an increase followed by a decrease in δ13C values, suggesting correlation with the Kilian Event. The middle part of the Los Coyotes Member has a significant negative carbon-isotope excursion correlated with the globally recognizable early Albian Paquier event. Moreover, another significant negative carbon-isotope shift is observed in the upper part of the Los Coyotes Member, which can be correlated with the Leenhardt Event. The occurrence of the Kilian, Paquier and Leenhardt Events (OAE 1b cluster) in the Cerro Pimas stratigraphy confirms the global nature of these early Albian disturbances of the carbon cycle.

A section from the lower part of the Taraises Formation located in the central-east part of Durango State, northern Mexico was studied. The succession consists of a grey and reddish limestone interstratified with marl levels. The calcareous strata provide a microfossil assemblage that consists of calpionellids, planktonic and benthonic foraminifera, and radiolarians. Based on the first appearance of Calpionellites darderi the Berriasian–Valanginian boundary was defined for the first time from the Taraises Formation. Also, the zones and subzones of this interval were described, the Calpionellopsis Zone, Oblonga Subzone and Praecalpionellites murgeanui Subzone for the late Berriasian and the Calpionellites Zone, Darderi and Major Subzones for the early Valanginian. The paleoenvironmental changes in the studied section are documented from the microfaunal association and mineralogical composition. The abundant occurrence of radiolarians in the early Valanginian might suggest an increase in nutrient input. In addition, the presence of tiny barite crystals, ankerite, siderite and dolomite rhombs confirms high fertility, implying oxygen-depleted conditions that could be considered a prelude of the mid-Valanginian Weissert Event. The predominant wackestone texture along with the occurrence of calpionellids and planktonic foraminifera indicate a pelagic basin environment. The microfaunal association is characteristic of the Tethys Realm.

In order to determine the accurate paleoenvironmental conditions of Qom Formation, one stratigraphic section was studied in the Urumieh-Dokhtar Zone (West of Ashtian). 60 thin sections of the Qom Formation, 71 m thick, were prepared and the distribution of benthic foraminifera was analyzed. On the basis of the recognized foraminifera, the age of Qom Formation in the studied section is assigned to the Late Oligocene (Chattian). In this study, sex different biofacies and two lithofacies types have been recognized, that can be grouped into two depositional environments, back ramp (alluvium channel, lagoon and shoal) and the ramp (inner, middle and outer ramp). The alluvium channel is characterized by Gms (gravel with massive layering and abundant matrix). The shoal is represented by fine to medium sandstone: calcite cemented submature litharenite. The lagoon is dominated by the presence of bioclastic bryozoan corallinacea wackestone- packstone and bioclastic foraminifera corallinacean wackstone to packstone. The inner ramp is characterized by bioclastic benthic foraminifera (perforate and imperforate) wackestone-packstone and the middle ramp represented by bioclastic perforate foraminifera wackstone-packstone and bioclastic Operculina packstone. Outer ramp is characterized by bioclast benthic and planktonic foraminifera mudstone.

Four sedimentary facies may be delineated based on quantitative analysis of texture and composition of modern surface sediments on the Dry Tortugas carbonate platform. These include (1) mollusk- Halimeda wackestone, (2) mollusk packstone-to-grainstone, (3) coralgal- Halimeda grainstone, and (4) coralgal grainstone. Even though the Tortugas platform is characterized by an open circulation due to deep, broad marginal channels and a lack of a continuous surface-breaking marginal reef, facies are not distributed at random and show bathymetrical zonation. Also, facies appear to cover wide belts rather than forming a mosaic. Mollusk- Halimeda wackestone occurs in protected platform interior areas ca. 10–18 m deep. Mollusk packstone-to-grainstone occurs in more open platform interior settings adjacent to channels and in deeper outer reef areas of 14–25 m water depth. Coralgal- Halimeda grainstone is found on shallow marginal shoals (1–11 m deep), and coralgal grainstone on the somewhat deeper (3–16 m), seaward edges of these shoals. However, there is bathymetrical overlap of facies in intermediate depths of ca. 5–17 m. This limitation has implications for the interpretation of the fossil record, because changes in water depth are commonly thought to be reflected in facies changes, e.g., in sequence stratigraphy. Comparison with previous sediment studies of the 1930s, 1960s, and 1970s in the area exhibit a decrease in coral fragments and increases in coralline algal and mollusk shell fragments. These observations might be a result of environmental changes such as coral decline and die-outs during temperature events, disease, and the increase in macroalgae (due to the ecological extinction of the echinoid Diadema ). The results suggest that more long-term studies are needed that further explore the influence of environmental change on reef sediment composition. Dry Tortugas surface sediments consist of lower portions of Halimeda plates and mollusk shell fragments and higher percentages of coralline algal fragments as compared to sediments of the adjacent Florida Reef Tract, possibly as a consequence of differences in platform morphology and exposure to waves and currents.

In this work we try to clarify, and correlate between two Maastrichtian aged units, namely Digma and Safra Units from selected sections in western desert of Iraq. Taking in consideration the stratigraphic code of NASCENT (2005), and the results of previous studies, nine criteria have been used for the correlation, as follow: 1- From lithostratigraphic point of view, Digma Formation (Fm.) mostly composed of dark grey to blackish gray, uniform Carbonates-dominated facies, while Safra unit is characterized by light yellowish brown mixed phosphatic- siliceous-siliciclastics and carbonates facies. 2- Digma Fm. is characterized by Benthonic foraminifera assemblages (Bulimmina sp., Siphogerinoides sp. & Bolivinoides sp. ), while Safra phosphatic unit is flourished by macrofossils assemblages and vertebrates (Oyster, fish teeth’s and bones). 3- The upper and lower boundaries of the Digma Fm. are conformable, and vice versa for Safra Unit. 4- Illite/Semctite mixed layers-Illite clays assemblage and Glauconitic are predominates in Digma Fm., while Sepiolite-palygorskite-Montmorillonite, are common in Safra Unit, without any Glauconitic mineralization. 5- Digma Fm. slightly influenced by neomorphism and micritization. On other hand, Safra facies extremely influenced by phosphatization, silicification, dolomitization, and neomorphism and carbonate-silica replacement of the original evaporate minerals. 6- The predominated foraminiferal wackestone and mudstone microfacies, within Digma facies associations, mostly indicate deep trough marine condition (Anah Graben). The mixed phosphatic-carbonates (Oyster coquina band) and siliciclastics facies, (occasionally cross laminated), mostly deposited in shallower water depth, on the Arabian platform and distal steepened ramp towards Rutba flanks. 7- Sequence boundary of type one and three is bounded the Safra Unit respectively from upper and lower parts. 8- Continuously deposited Sequence was detected from the parasequences of the Safra facies, and across Maastrichtian/Danian boundary (Trafawi Unit). 9- The paleo-configuration of the basin almost influenced by the reactivity of the Anah basement faults started in the Late Campanian, and combined by shallowing upwards sequences. The conclusion is that, Digma facies can be considered as local facial changes of the Shiranish Formation, while Safra unit can be considered as a lower Member of (L. Maastrichtian-Danian) Jeed Formation, which is coincides with the whole stratigraphic frame work of the Mediterranean segments of the Tethyan phosphatic realm.

Marine cavities harbouring cryptic organisms have been ubiquitous throughout the Phanerozoic. However, our knowledge of early cryptic communities is as yet insufficient, and how metazoans began to utilize such habitats remains unknown. In this study, we document demosponge remains within intraskeletal cavities embedded in the micritic succession of a shallow carbonate platform in the Upper Ordovician (Katian) Xiazhen Formation of South China. Molluscs (gastropods, bivalves, and nautiloids) and corals (the solitary rugosan Tryplasma and colonial agetolitids) within the succession commonly contain patches of “spicular” demosponge remains (11%; n = 45/415), mainly occupying intraskeletal spaces with areas of 1–30 mm2 in thin-section. Sponge occurrence varies according to sedimentary facies: within lime mudstone facies, sponges commonly occur both inside and outside intraskeletal cavities, suggesting that sponges would have inhabited and become preserved within any available space in this environment. In contrast, when other sessile organisms co-occur in wackestone to packstone facies, there are fewer sponge occurrences both inside and outside cavities, possibly due to competition in open habitats and/or their poorer preservation in such environments. Overall, this result suggests that sponges would have exploited cryptic habitats by normal expansion of the open-surface biota. In addition, compared with coeval reef and hardground crypts, the Xiazhen intraskeletal cryptic biota is monotonous in composition, suggesting “decoupled” occupation of cryptic habitats in different environments.

The Aptian stratigraphic record of the Alicante region consists of: a rudist and coral-rich carbonate platform of earliest Aptian age (Llopis Formation), with a discontinuous siliciclastic member at its top; followed by late Early, to Late Aptian hemipelagic marls and marlstones (Almadich Formation); and then by renewed carbonate platform development of Late Aptian to earliest Albian age (Seguilí Formation). In the Llopis Formation, SW-dipping, massive clinoform beds of bioclastic debris are succeeded by flat-lying platform-top beds. The latter show a cyclically regressive stacking of biofacies, with rudist-dominated floatstone in their lower parts passing upwards to finer-grained, more sparsely fossiliferous bed tops with burrow mottling. Caprinid rudists, with originally almost wholly aragonitic shells, dominate the external platform-top facies, while more internal facies contain a mix of monopleurid, polyconitid and requieniid rudists, all with relatively slightly thicker development of the calcitic outer shell layer, together with caprinids. Biostratigraphic and carbon-isotope data link the termination of the Llopis platform with the onset of OAE1a. The carbonate platform of the Seguilí Formation again contains tabular platform-top beds showing repeated cyclic regression, with dense rudist and/or chondrodont floatstones overlain by sparser floatstones with wackestone matrix and secondarily filled burrows. But caprinids are now absent, while requieniids and polyconitids, some of large size, as well as radiolitids, all with thickened calcitic outer shell layers, accompany the tubular monopleurid, Mathesia, together with a greater development of Chondrodonta biofacies. The same overall pattern of biotic turnover from the Early, to the Late Aptian is confirmed in other parts of Iberia and contiguous regions. Moreover, Iberian platforms of late Early Aptian age outside the present study area reveal a transitional phase with an increasing proportion of polyconitids in the outer platform-top to upper slope facies at the expense of caprinids. The siliciclastic influx at the top of the Llopis Formation implies a climatic shift from arid, to relatively more humid/pluvial conditions through the mid-Early Aptian, as seen in several other Iberian sections. This climatic change was probably forced by the intensified greenhouse conditions at the onset of OAE1a. By contrast with these Iberian platforms, caprinids continued to dominate the outer platform-top zones of some central to southern Tethyan platforms until the close of the Early Aptian. This broad palaeolatitudinal differentiation of rudist associations within the Tethyan belt implies a climatic influence, whether exerted through thermal modulation of seawater pH and/or aragonite saturation, variation in nutrient flux, or any combination of these.

The Eocene-Oligocene Transition is a key interval in the evolution of the modern climate, representing the last greenhouse-icehouse transition faced by the Earth. Shallow-water carbonate systems hold essential information of the global changes related to the E-O Transition. In this work, we focus on the Majella Mountain carbonate ramp to identify the shallow-water sedimentary expression of the oceanographic and sea-level changes related to the E-O Transition, and to compare it with the deep-marine records and the coeval shallow-water successions. Field observations, coupled with the study of thin sections to identify textural characters, and of the larger benthic foraminiferal associations for biostratigraphic purposes, allowed reconstructing the depositional model and the stratigraphic distribution of the examined ramp. The lower Rupelian ramp outcropping in the Majella Mountain is characterized by seagrass meadows in the euphotic inner ramp. Corals developed in the middle ramp, building mounded cluster reefs in the mesophotic zone, below wave base, in high hydrodynamic conditions produced by rip-currents induced by storm events or by the breaker zone of internal-waves. The outer ramp consists of alternating bioturbated wackestone rich in planktonic foraminifera, bioclastic packstone and skeletal rudstone to floatstone. The depositional model of the Oligocene ramps is the result of the major changes that occurred during the greenhouse-icehouse transition. In the Majella platform, the E-O Transition corresponds to an unconformity developed on the Priabonian substrate, where the cluster reefs grew and expanded. The unconformity results from the sea level drop of tens of meters, recorded also in the outer ramp, related to the Oi-1 event. The cluster reefs started to develop when the Priabonian ramp was flooded and continued to grow during the following highstands, forming an extensive coral unit that prograded basinwards, interfingering with the outer ramp deposits.

Volcanic atolls host exceptionally important marine ecosystems in the modern oceans. Yet, due to limited exposures, fossil atolls are poorly constrained. Multiple drowned Cretaceous volcanic atolls have been reported in the Pacific, but less information exists regarding those in the Tethys. Here we report on two early Cenomanian age volcanic atolls outcropping in Mt. Carmel (northern Israel), along the eastern Levant margin. These atolls are a few kilometers in diameter and differ significantly in facies from their surroundings, which are dominated by chalky calcareous mudstone and wackestone. The atolls are composed of grainstone, floatstone, rudstone and bafflestone facies, which are dominated by molluscans, notably gastropods, rudists, oysters and other bivalves. Corals and green algae are absent throughout these atolls. The studied sections of these atolls display a full succession, beginning with aggradation and ending with drowning. Age constraints for the volcanic phases suggest that deposition occurred within a relatively short time interval (

Mid to late Cambrian thrombolites and maze-like maceriate reefs from the western North China Platform, Wuhai, Inner Mongolia, northwestern China, occur in the middle of a succession dominated by thin-bedded lime mudstone-shale/marlstone alternations, and are laterally surrounded by limestone conglomerate and/or grainstone. Thrombolite, characterized by meter-scale lenticular mounds composed of millimeter- to centimeter-scale mesoclots and wackestone matrix, occurs in the lower middle part of the sequence. Thrombolite mesoclots are composed of microstromatolites with alternating dark gray and light gray micritic laminae. The maze-like maceriate reefs occur in the middle to the upper part of the sequence, commonly forming lenticular mounds up to 1 m thick. They are characterized by centimeter- to decimeter-scale branched maze-like structures, whose biogenic portions (maceria) are selectively dolomitized. The maceriae are composed of poorly preserved microstromatolites and siliceous sponges. Inter-macerial sediments consist of lime mud and scattered bioclasts. These Wuhai reefs are generally similar to but older than various other Cambrian reefs previously reported from the Shandong region, northeastern China.

The Actinocrinitidae were among the most abundant crinoids worldwide during the Lower Mississippian. Recent systematic revisions of the family allow a revised genus- and species-level understanding of these crinoids globally and a more precise means by which to understand the temporal and facies distribution of genera and species in this important Mississippian family. Two genera with a total of five species of Actinocrinitidae (and five additional forms left in open nomenclature) are recognized from the Fort Payne Formation, including Actinocrinites jugosus (Hall, 1859), Actinocrinites spp. indeterminate, Thinocrinus gibsoni (Miller and Gurley, 1893), Thinocrinus lowei (Hall, 1858), Thinocrinus probolos (Ausich and Kammer, 1991), Thinocrinus akanthos new species, Thinocrinus sp. aff. T. gibsoni, Thinocrinus spp. indeterminate, and two taxa recognized as only Actinocrinitidae genus and species indeterminate. Actinocrinites tripus Ehlers and Kesling, 1963 is recognized as a junior synonym of Thinocrinus gibsoni. Thinocrinus, rather than Actinocrinites as previously thought, is the dominant Fort Payne Formation actinocrinitid. Fort Payne Formation carbonate buildup facies (wackestone buildups and crinoidal packstone buildups) each have characteristic species of Thinocrinus. Actinocrinites is relatively rare in the Fort Payne Formation, but occurs preferentially in crinoidal packstone buildups.

The basal unit of the succession in the Illela borehole belongs to the Dange Formation comprising thick calcareous and variably coloured dark-greyish shale of 36.30 m thick which is overlain by a 31.44 m thick limestone of Kalambaina Formation with 1.7 m thick shaly-limestone inclusive. The uppermost part of the section belongs to the Gwandu Formation which has intercalation of silty-clay, muddy siltstones with well lithified ironstone capping the borehole section. The limestone/carbonate microfacie as deduced from their salient lithologic, sedimentologic and paleontologic features are comparable to standard microfacie (SMF) types 9 and 10, i.e. bioclastic wackestone/bioclastic micrite and packstone-wackestone respectively. Diagenetically, syndepositional and early diagenesis have taken place particularly cementation and replacement in the carbonate rocks and these have greatly affected the reservoir potential negatively. The matrix/grain relationships indicate a shallow marine environment of deposition. The borehole section is delineated into upper foraminifera and lower ostracod biostratigraphic units as no formal biostratigraphic zonation could be attempted due to low diversity of both benthic foraminifera, marine ostracods and the absence of planktonic foraminifera. The similarity of the ostracod assemblages between this study area, Illela borehole, West Africa, North Africa (Libya), Mali and Niger Republic) and South-Western Nigeria (West Africa) suggests that a marine connection exists between the Gulf of Guinea and the Sokoto Basin via the area occupied by the River Niger during the Paleocene.

The rise and demise of warm-temperate Permian reefs and biostromes reflect the complex geologic history of this dynamic period. Environments suitable for reef-builders were devastated by the Guadalupian/Lopingian crisis, and Lopingian reefs have only been recorded at a small number of localities. The uppermost Permian limestones of the Bellerophon Formation, on the Vojsko Plateau (Slovenia), contain small, lenticular biostromes within a bioclastic wackestone/packstone lithofacies. The major biostrome builders are medium-sized coralline sponges (Demospongea and Calcarea), encrusted by smaller sponges, tube worms, sessile foraminifera, calcareous algae (Archaeolithoporella) and Shamovella (i.e., Tubiphytes), all of which are typically covered by microbial crusts. The biostromes are characteristically composed of bafflestone and bindstone, incorporating sporadic framestone. Narrow belts of floatstone surround the buildups, and sponge debris is also present in lenses within the mud matrix between metazoan bafflestones. The fossils are generally well- preserved, although the fine skeletal microstructure has been partially recrystallized. Sponges are heavily calcified, and ontogenic thickening of the skeleton can be observed in some encrusters. Framboidal pyrite, forming thin films on the inner walls of sponge chambers, suggests the presence of sulphate- reducing bacteria. These microbial symbionts may have enabled the sponges to survive in the anoxic marine environments of the uppermost Permian. The Changshingian sponge biostromes of the Vojsko Plateau represent the westernmost known occurrence of contemporary metazoan boundstones in the Palaeotethys.

The geological features and distribution regularity of the grain shoal reservoirs of the Cretaceous Mishrif Formation in Halfaya Oilfield and their main controlling factors were analyzed based on cored data, 302 pieces of thin sections and 2507 experiment data points. Various types and multiple phases of grain shoal reservoirs are developed in Mishrif Formation, which are dominated by grainstone, followed by wackestone packstone. The formation and distribution of grain shoal reservoirs are mainly controlled by relative sea level change, paleogeomorpholoy and contemporaneous-penecontemporaneous dissolution. Relative sea level change controls the types and development phases of grain shoals. When the sea level falls, rudists, coquina, arene and pelletoids are extensively deposited, among which, rudists clastic shoal and coquina shoal that are deposited at the lowest sea level have the best reservoir properties, with a maximum porosity of 33.94%, maximum permeability of 764.571×10−3 μm2 and an average permeability of 45.81×10−3 μm2. Paleogeomorpholoy controls high-energy facies belt and the dissolution of meteoric water. The submarine paleohigh controls the formation and distribution of high-energy facies belt during depositional period. However, during uplifting and denudation period, the reservoirs in paleohigh are intensively dissolved and represent good reservoir properties, with an average porosity of 14.78% and permeability of 7.849×10−3 μm2. Contemporaneous-penecontemporaneous dissolution results in the formation of most effective pores, which is the key factor for the formation of grain shoal reservoirs in the study area. Key words: grain shoal reservoirs, main controlling factor, relative sea level change, paleogeomorpholoy, dissolution, Mishrif Formation, Halfaya Oilfield, Mesopotamia basin

The early Eocene Naredi Formation in the southwestern Kutch represents the initial marine sedimentation in Kutch area during Tertiary period. The 22 m thick succession of Naredi Formation, exposed along cliffs (N 23°34′36.8″, E 68°38′38.1″ and N 23°34′3.1″, E 68°39′7.8″) of the tributary of the Kakdi River in and around Nareda village, is dominantly composed of argillaceous member (also known as gypseous shale member) in the lower part and dominantly biochemically precipitated carbonate member, including newly identified algal and coral reef facies, in the upper part. A total of eight lithofacies have been identified based on sedimentological and micropaleontological attributes; those are alternate green- and brown shale facies, comprising the argillaceous member followed by bioclastic wackestone, Assilina packstone, organically bounded framestone (bioherm), clayey limestone, bioclastic packstone–wackestone alternation and ferruginous coralline limestone in ascending order, which constitute the upper carbonate member. The green as well as brown shale facies are splintery in nature and show horizontal interlamination with gypsum layers. Both these facies contain glauconites with circular to elliptical outline and radial fractures, thus suggesting deposition on a mid- to outer-shelf or restricted lagoonal depositional setting. The overlying horizontally bedded wackestone facies and sparitic packstone facies containing fossil shells of larger benthonic foraminifera, including Assilina spinosa, Assilina and Nummulites burdigalensis with some planktonic forms such as Globigerina and Globorotalia in association to rotalids, ostracods, bivalve and gastropod shells, whose presence depict their deposition in mid- to inner-shelf marine realm under normal seawater salinity. The abundance of peloids, calcispheres and limestone fragments are the major non-biogenic allochems in these facies. Replacement of the ostracods, bivalve and gastropod shells by sparry calcite is also the common feature. The overlying organically bounded algal framestone (bioherm) is characterized by slightly undulatory tabular form in the lower part to concentric undulatory mounds in the upper part showing reef growth at outcrop section whereas framework of curvi-radial concentric growth of carbonate layers under thin section indicates reef formation on shallow marine depositional setting in warm and clear tropical water under normal seawater salinity. The thinly bedded brownish white clayey limestone indicates deposition during deepening of the lagoon. The overlying bioclastic packstone–wackestone alternation facies studded with fragments of algal reef and stromatolitic limestone along with various fossil shells like bivalves, echinoids and gastropods, most of them are micritized, resembles its deposition under back-reef lagoonal environments during storm condition which is overlain by an intertidal coralline limestone deposit showing colonial growth and partial to complete replacement of some of the coral shells by ferruginous mineral along with secondary precipitation of the same within the pores during shallowing of the sea and/or due to late diagenetic changes. Based on shale-carbonate wackestone-packstone-reefal-coralline facies association along with the presence of some key minerals such as glauconite, pyrite, siderite and anhydrite and their genetic link to characteristic depositional milieu, authors have proposed fluctuating depositional environments from lagoonal-barrier ridge to lagoonal-tidal flat for the Naredi Formation.

Four measured sections along the northern escarpment of the Dahar Plateau in southern Tunisia provide details of Cretaceous (Coniacian-Campanian) stratigraphy in this region of North Africa. These sections reveal various units of limestone with cross-stratification, limestone with in situ rudists, mud-supported limestone (carbonate mudstone, wackestone), argillaceous limestone, and limestone with stromatolites. These units are arranged vertically into several sequences of finer-grained limestone (mud-supported limestone, argillaceous limestone) overlain by coarser-grained limestone (limestone with cross-stratification, rudists, and/or stromatolites). Each sequence is interpreted as a shallowing upwards progression on a carbonate platform. Furthermore, cross-strqtified carbonate and beds with in situ rudists are more common in the lower parts of the measured sections, whereas units with stromatolites, argillaceous limestone, and finer-grained limestone are more common in the upper parts of the measured sections. The overall transition from the coarser-grained (higher energy) strata to the overlying finer-grained (lower energy) argillaceous strata is interpreted as having been caused by a relative fall in sea level that brought argillaceous sediment into the area. It is possible that the arrival of argillaceous sediments and the relative fall in sea level may have caused the demise of the rudist reefs. The lower interval (in which cross-stratified carbonates and in situ rudists are more common) is assigned to the Berressef Formation, whereas the upper interval (in which stromatolites, argillaceous limestone, and other fine-grained strata are more common) is assigned to the Toual Formation. Previous work suggests that the Berressef Formation is of Coniacian? to Santonian age, whereas the Toual Formation is of Campanian age. A regional cross section correlates these Cretaceous units on the Dahar Plateau with (1) rudist-bearing strata that are mapped in north–central Tunisia as the Merfeg Formation, and (2) argillaceous and marly limestone that is mapped in central Tunisia as the middle and lower Berda Formation and the middle Abiod Formation.

In order to document the microfacies and diagenesis of the reefal limestone in the uppermost part of the Callovian Tuwaiq Mountain Limestone Formation at Khashm Al-Qaddiyah area, central Saudi Arabia, scleractinian corals and rock samples were collected and thin sections were prepared. Coral framestone, coral floatstone, pelloidal packstone, bioclastic packstone, bioclastic wacke/packstone, algal wackestone and bioclastic foraminiferal wacke/packstone were the recorded microfacies types. Cementation, recrystallization, silicification and dolomitization are the main diagenetic alterations affected the aragonitic skeletons of scleractinian corals. All coral skeletons were recrystallized, while some ones were dolomitized and silicified. Microfacies types, as well as the fossil content of sclearctinian corals, bivalves, gastropods, brachiopods and foraminifera indicated a deposition in environments ranging from shelf lagoon with open circulation in quiet water below wave base to shallow reef flank and organic build up for the uppermost reefal part of the Tuwaiq Formation in the study area.

Paleozoic echinoids are exceptionally rare, and little is known of their paleoenvironmental distribution. The echinoid fauna of the Fort Payne Formation (Late Osagean, Early Viséan) of south-central Kentucky is documented. Four genera, ?Archaeocidaris, Lepidocidaris, ?Lepidesthes, and an unidentified lepidocentrid, were recovered and represent three different families. This fauna, and their associated paleoenvironments, give important new insights into the facies distribution of Paleozoic echinoids and the taphonomic biases that affect this distribution. Lepidocidaris is known from the green shale facies, which comprises the core of Fort Payne’s carbonate buildups. ?Archaeocidaris and the lepidocentrid are known from the wackestone buildups and crinoidal packstone buildups. ?Lepidesthes is also known from crinoidal packstone and wackestone buildups, which argues against a semi-infaunal life mode for this taxon. All relatively semiarticulated echinoids were known from autochthonous facies, whereas the only echinoids from the allochthonous facies were disarticulated hemipyramids. Furthermore, deeper-water carbonate buildups were apparently capable of supporting diverse echinoid faunas during the Viséan.

A middle Ludlow biostrome at Katri, western Estonia, the richest accumulation of corals and stromatoporoids in Estonia, is partly exposed in a coastal section ca. 1 m high, 150 m long. The fully marine biostrome consists of 5 layers of skeletal carbonate, grouped into Facies 1 (grainstone-packstone, layers 1, 3 & 5) and Facies 2 (wackestone, interbedded layers 2 & 4). Pressure solution degraded original sedimentary relationships and morphologies of stromatoporoids, tabulates and rugosans which constructed the biostrome, but the two facies have major faunal differences. Facies 1 is rich in stromatoporoids “Stromatopora” bekkeri and Plectostroma scaniense (low to high domical up to ca. 30 cm basal length); and tabulate Favosites forbesi (bulbous to high domical up to ca. 25 cm wide). In Facies 2, all three taxa are less common and much smaller. Instead, the most abundant stromatoporoid is laminar Syringostromella borealis up to 30 cm basal length; the most abundant coral is erect branching Laceripora cribrosa, as scattered fragments up to 24 cm long. Neither occurs in Facies 1. Six other stromatoporoid taxa, 5 other tabulate and 5 rugosan taxa occur uncommonly in the biostrome, mostly in both facies. The Katri biostrome is slightly younger than, but similar facies to, biostromes in the middle Ludlow Hemse Group on Gotland ca. 250 km WSW, with well-known stromatoporoid faunas. Corals are abundant in Hemse biostromes, but taxonomy awaits full study. Several key stromatoporoids occur in both the Hemse biostromes and Katri, but two abundant taxa in Hemse biostromes are absent in Katri and two tabulate corals abundant in Katri are missing in Hemse biostromes. Thus there was wide distribution of such biostromes in the central Baltic large shallow marine carbonate platform, but with previously unreported variable assemblages presumed due to facies features not recognised in the sediments.

The Larger Foraminifera made a major contribution to Paleocene and Eocene biota. The microfacies and diagenetic setting of the Paleocene Lockhart Formation were analyzed in Shah Alla Ditta area, Islamabad. The Lockhart Formation is highly fossiliferous, comprising of thin nodular limestone with interbedded shale/marl. The lower contact is unconformable with Jurassic Samansuk formation while the upper contact is conformable with Margalla Hill Limestone. Rock samples were collected from the field and thin sections were prepared and analyzed under the microscope and on the basis of detailed petrographic study three types of microfacies were identified and interpreted based on Dunham’s textural classification, allochem type, fossil content and sedimentary structures. The microfacies include: LH-MF 1: Foraminiferal Wackestone/Biomicrite Microfacies, LH-MF 2: Algal Foraminiferal Wackestone Microfacies, LH-MF 3: Mixed Bioclastic Mudstone Microfacies. A number of larger benthic foraminifera, and the lack of Planktonic foraminifera in the Lockhart Limestone, indicate shallow to deep water of restricted inner to middle shelf environment of deposition. Larger foraminifera and dasycladacena algae are the two major fossil contents present in the Lockhart Formation. Larger foraminiferal species like Lockhartia hameii and Lockhartia conditi present in the formation confirm the age of Lockhart Limestone as Paleocene. The main diagenetic fabric recognized in the limestone reveals mechanical and chemical compaction, deep burial water pressure, pressure solution and tectonics-related fracturing. The nodularity in the limestone is credited to pressure solution.

Periplatform carbonate ooze records a composite signal reflecting both the regional oceanographic state and the development of the adjacent carbonate platform. Deconvolving these signals offers the possibility to obtain a holistic perspective on the factors governing the evolution of the platform, especially when the platform itself is not accessible. Here, we examine a case study from periplatform deposition in Site U1468 on the margins of the Kardiva Platform, Maldives. This site has a well-constrained record with seismic control of the geometric evolution of adjacent carbonate platforms. Here we integrate geochemistry, sedimentology and external constraints to address the relationship between local (platform evolution), regional (nutrient regime) and global (temperature, sea level) effects. The lower to middle Miocene succession at Site U1468 is comprised of a wackestone to packstone sequence that hosts foraminifera and other bioclastic grains, derived from neritic and pelagic sources, as well as biogenic siliceous material such as sponge spicules. The sequence records an increase in neritic supply to the periplatform from the late Burdigalian to the early Serravallian as recorded in Sr/Ca and δ13C values. The increase in neritic material coincided with a stepwise intensification of the regional Oxygen Minimum Zone (OMZ) recorded by Mn/Ca ratios. During these trends, short-lived oscillations in local carbonate production and OMZ intensity were superimposed on the larger trend. The expansion of the OMZ was driven by periods of cooling while the increase in neritic production was driven by warming and sea-level rise. These results reinforce existing models of the evolution of the Kardiva Platform with respect to sea level and add to it a refined understanding of the relation to regional nutrient patterns.