Operculina Complanata Research Articles

On the occurrence of Neoplanorbulinella Matsumaru, 1976 (Foraminifera) from the late Oligocene of Central Iran (Qom Formation): Palaeobiogeographic implications

The shallow marine carbonates of the upper Oligocene Qom Formation yielded several occurrences of the foraminiferan genus Neoplanorbulinella Matsumaru. Neoplanorbulinella saipanensis Matsumaru has so far been recorded from the late Eocene–early Miocene of Japan and late Oligocene of NE Italy whereas N. malatyaensis Gedik is only reported from the Oligocene from its type locality in the Malatya Basin, eastern Turkey. The new records reported here from the Qom Formation indicate that both species occur in the Dobaradar section, ca. 10 km south of the city of Qom in North–Central Iran. The palaeogeographic distribution of these two species therefore has to be extended as far as the palaeolongitude of current Central Iran. The accompanying larger benthic foraminifers, including Miogypsinoides complanatus (Schlumberger), M. formosensis Yabe and Hanzawa, Spiroclypeus margaritatus (Schlumberger), Operculina complanata (Defrance), and Risananeiza pustulosa Boukhary et al., indicate the upper Chattian SBZ 23 Zone. The co-existence of the N. saipanensis and N. malatyaensis points to suitable palaeobiogeographic conditions of Central Iran to host Western and Eastern Tethyan taxa.

Foraminiferal distribution and biostratigraphy of the Lower Miocene Qom formation, north of Bijar, NW Iran

This study is based on larger benthic foraminifera that dominate the Lower Miocene shelf carbonates of the Qamcheqai section, NW Iran. During the time of deposition, the investigated area was positioned on the Eurasian side of the Tethyan Seaway between the Eastern and Western Tethys. Seven porcelaneous and hyaline perforated species were determined, including Praebullalveolina curdica, Peneroplis evolutus, Androsina cf. diyarbakirensis, Sivasina egribucakensis, Miogypsina cf. intermedia, Operculina complanata, and Amphistegina bohdanowiczi. The presence of Miogypsina cf. intermedia, and Praebullalveolina curdica allowed to correlate the assemblage with SBZ 25 Zone, indicating a Burdigalian age. The results of this study extend the paleogeographic distribution of the endemic taxa Androsina and Sivasina eastwards as far as Central Iran.

Postmiogypsinella intermedia Sirel and Gedik 2011 from the upper Oligocene of Central Iran (Qom Formation): Paleogeography and paleoenvironmental implications

Postmiogypsinella intermedia Sirel and Gedik, 2011 is reported for the first time from the shallow-marine limestones of the upper Chattian Qom Formation, Central Iran. This miogypsinid species has so far only been recorded from the upper Oligocene of Malatya (type locality) and Sivas (Central Anatolia) in eastern Turkey and from the upper Oligocene of the Prebetic Domain, SE Spain. The new record from Central Iran, paleobiogeographically located at the Eurasian margin of the Tethyan Seaway between the Western and Eastern Tethys realms, indicates that the paleogeographic distribution of this species has to be extended eastwards as far as Central Iran. This observation is not unexpected, since miogypsinid foraminifers with eccentric embryonic–nepionic apparatus (e.g., Miogypsinella, Miogypsinoides, Miogypsina) are usually widely distributed. The accompanying larger benthic foraminifera, including Miogypsinoides complanatus (Schlumberger), Miogypsinoides formosensis Yabe and Hanzawa, Spiroclypeus margaritatus (Schlumberger), Operculina complanata (Defrance), and Risananeiza pustulosa Boukhary et al., indicate the late Chattian age (corresponding to SBZ 23 Biozone). Postmiogypsinellaintermedia is indicative of a shallow-marine middle ramp environment with oligotrophic conditions and inhabited the relatively deeper part of the photic zone.

Larger benthic foraminifera and biostratigraphy of the lower Oligocene Asmari Formation: offshore and onshore southern Iran (Zagros belt)

A relatively diverse assemblage of larger benthic foraminifera from the Asmari Formation is described based on the recovered samples from two subsurface sections, offshore and onshore, southern Iran. Due to its position in the Tethyan Seaway between the Mediterranean and Indo-Pacific, the Zagros belt as a part of theMiddle East has high significance in palaeobiogeography. The fauna is dominated by both hyaline perforated and porcelaneous forms. Eight species of larger benthic foraminifera are described, including Nummulites fichteli, N. vascus, Operculina complanata, Archaias operculiniformis, Praerhapydionina delicata, Austrotrillina striata, Peneroplis thomasi, and P. evolutus. The presence of N. fichteli and N. vascus in the absence of lepidocyclinids indicates the SBZ 21 Zone referring to a short time span restricted to early Rupelian.

Oligocene larger benthic foraminifera and sedimentation of the Burdur Basin, SW Anatolia, Turkey

This study focuses on the Oligocene successions that contain predominantly siliciclastic, limestones with larger benthic foraminifera in the Burdur Basin of southwest Anatolia, Turkey. The Burdur-1 and Burdur-2 sections in the Oligocene deposits are described sedimentologically and were sampled for lithology, biostratigraphy, microfacies analysis and fossil content. Larger benthic foraminifera were mainly recovered from limestones in the upper part of the Burdur-2 section. Thin-section analysis of the larger benthic foraminiferal assemblage reveals that the upper part of the Burdur-2 section includes Nummulites fichteliMichelotti, 1841, Operculina complanata (Defrance, 1822), Nephrolepidina praemarginata (Douvillé, 1908), Eulepidina sp., Planorbulina sp., Amphistegina sp., and Asterigerina sp. This foraminiferal association represents the Shallow Benthic Foraminifera Zone 22 (SBZ 22) of Rupelian-early Chattian age. Sedimentological analysis in the Burdur-1 and Burdur-2 sections has revealed an association of massive-unorganized conglomerate, parallel-bedded sandstone, massive mudstone, graded-massive conglomerate, graded-massive sandstone, well-sorted organized conglomerate, well-sorted parallel-bedded sandstone and microfossil-bearing parallel-bedded limestone facies. Alluvial fan /river, fan-delta, beach and shallow shelf carbonate facies communities were identified by lateral and vertical correlation of facies. It is concluded that the large Burdur Fan developed in a graben basin that opened and was flooded by a branch of the Tethyan Ocean that invaded southwest Anatolia during the Oligocene.

Stratigraphy and Microfacies Analyses of The Al Faidiyah and Benghazi Formations at Al Fatiah, Al Huarry and Al Abyar Quarries, NE Libya

Three quarries named Al Fatiah Cement, Al Huarry Cement, and Al Abyar are located in the northeastern part of Libya and consist of carbonate rocks of Miocene age. The main objectives of this study based on microfacies analyses are to construct the depositional environment with a comprehensive stratigraphical correlation of the study areas. The Al Fatiah Quarry has been divided into three microfacies which are operculinid packstone microfacies, algal packstone microfacies, and moluskan packstone grading to grainstone microfacies, one species of large benthic foraminifera is found to be abundant (Operculina complanata). Accordingly, the Al Faidiyah Formation was deposited in a continental shelf (outer to middle neritic zones) environment. Al Huarry Cement Quarry has been divided into five microfacies which are algal boundstone microfacies, amphisteginid - algae packstone microfacies, amphisteginid grainstone microfacies, algal - bryozan packstone microfacies and amphisteginiid - bryozoan - algal boundstone microfacies, one species of large benthic foraminifera is found to be abundant and well preserved (Amphestegina cf. lessonii). Accordingly, the Benghazi Formation was deposited in an inner self to open a marine shelf environment. On the other hand, the Al Abyar Quarry has been divided into two microfacies which are pelloidal packstone microfacies and miliolid wackestone–packstone microfacies, suggesting that the sedimentation was of low energy under very shallow marine to the restricted environment.

STRATIGRAPHY OF THE LOWER OLIGOCENE NUMMULITIC LIMESTONES, NORTH OF SONQOR (NW IRAN)

The lower Oligocene hyaline and porcellaneous larger foraminifera of a carbonate platform setting, north of Sonqor, were studied for high-resolution biostratigraphy in the context of European standard zonation (Shallow Benthic Zones). According to the geological map of Kermanshah, these beds were previously ascribed to the Miocene. The identified larger foraminifera include Nummulites fichteli Michelotti, Nummulites vascus Joly & Leymerie, Operculina complanata (Defrance), Asterigerina rotula (Kaufmann), Planorbulina bronnimanni Bignot & Decrouez, Discogypsina discus (Goes), Gypsina mastelensis Bursch, Halkyardia maxima Cimerman, Stomatorbina concentrica (Parker & Jones), Praerhapydionina delicata Henson, Penarchaias glynnjonesi (Henson), Austrotrillina aff. paucialveolata Grimsdale, and Haddonia heissigi Hagn, associated with the coralline alga Subterraniphyllum thomasii Elliott. The foraminiferal association characterises the SBZ 21 Zone (early Rupelian).

LATE CHATTIAN LARGER FORAMINIFERA FROM THE PREBETIC DOMAIN (SE SPAIN): NEW DATA ON SHALLOW BENTHIC ZONE 23

This study focuses on an Oligocene succession dominated by larger foraminifera and coralline algae in the Benitatxell Range (Prebetic Domain, southeastern Iberian Peninsula). The foraminiferal assemblage, studied in thin sections, and interpreted as Shallow Benthic Zone 23, late Chattian, includes: Austrotrillina asmariensis , Nephrolepidina spp., Eulepidina dilatata , E. elephantina , E. raulini , Amphistegina bohdanowiczi , A. mammilla , Operculina complanata , Nummulites cf. vascus , N. aff . kecskemetii , Heterostegina assilinoides , Spiroclypeus blanckenhorni , Cycloclypeus mediterraneus , Miogypsinoides formosensis , Postmiogypsinella aff. intermedia , Neorotalia viennoti , Risananeiza pustulosa , and Victoriella conoidea. The Rebaldi section, a succession of late Oligocene limestones 3 km north of the Benitatxell section, shows a similar association with Peneroplis thomasi , A. asmariensis , M. complanatus , Neorotalia viennoti , N. lithothamnica , Heterostegina aff. assilinoides , Spiroclypeus blanckenhorni , Cycloclypeus mediterraneus , A. bohdanowiczi , and Risananeiza pustulosa ; it is interpreted as the early part of SBZ 23. This section also contains Praebullalveolina aff. oligocenica , described from the early Rupelian of Turkey, and Schlumbergerina alveoliniformis , previously interpreted as Burdigalian-Recent. Prior to this work, Cycloclypeus mediterraneus was considered to go extinct and be replaced by C. eidae at the SBZ 22B-23 boundary. However, its presence in the Benitatxell and Rebaldi sections extends its range to the late Chattian in the Eastern Betics and indicates an asynchronous extinction in the Tethys. The presence of Amphistegina mammilla Fichtel and Moll 1798 in late Chattian deposits from the western Tethys contradicts the currently accepted hypothesis that places its origin in the Indo-Pacific province in the early Miocene, from where it would have migrated into the Parathethys during the middle Miocene. In addition, the biogeographic range of P. thomasi , A. asmariensis , and P. oligocenica is extended to the westernmost part of the Tethys.

Paleontological study of Messen, Suza and Olympic stratigraphic sections in Qeshm and Kish Islands, Persian Gulf, Iran

The micropaleontological studies in Qeshm and Kish Islands have been carried out on the following formations: Aghajari, Qeshm limestone, and Kish coral limestone. The studied section in Qeshm Island included: Messen and Suza stratigraphic sections in the south of island. Messen section consists of Aghajari and Qeshm limestone formations. Suza section is composed of Qeshm limestone formation. Also, Olympic stratigraphic section in the north of Kish Island was analyzed. This section records a Pliocene–Pleistocene age and consists of Aghajari and coral limestone formations. The foraminifera identified in the aforementioned stratigraphic sections are Ammonia beccarii (linne), Rotalia viennoti Greiget.Vars, Elphidium sp. Linnaeus, Pyrgo sp. Schwager, Quinqueloculina sp. d’Orbigny, Textularia sp. Defrance, Triloculina trigonula Schwager, Spiroloculina sp. (d’Orbigny), Triloculina tricarinata Schwager, Operculina complanata d’Orbigny.

Mechanism and process of construction of tubes of the trace fossil Schaubcylindrichnus coronus Frey and Howard, 1981

Schaubcylindrichnus coronus is a common trace fossil occurring in post-Cretaceous shallow marine deposits. It consists of a sheaf or bundle of thickly lined tubes, with the tube linings usually composed of colorless minerals (“mineral-lined” type). Recently, many peculiar specimens of S. coronus, whose tube linings are composed mainly of tests of the larger benthic foraminifer Operculina complanata japonica (“Operculina-lined” type), have been found in the inner shelf deposits of the late Miocene Kaichigo Formation in the Miyazaki Group, southwestern Japan. The “Operculina-lined” specimens occur in association with funnel-shaped concentrations of Operculina tests. In some specimens, the end of the tube directly connects to the concentration. We consider these concentrations to be the product of feeding funnels filled with Operculina tests that were delivered from shallower marine settings in association with storm currents. Considering the fact that no Operculina tests are found in the host rocks that bear Operculina-lined tubes, the Operculina tests that line the tubes appear to have originated from Operculina test concentrations. In other words, during feeding, the animal producing S. coronus apparently selected the tests in its feeding funnel by their specific gravity and utilized them for tube construction. This manner of tube construction is highly consistent with that of modern funnel-feeding polychaete worms.

English

Miocene larger benthic foraminifera have been discovered from a limestone unit of the Kalumpang Formation. The limestone is exposed at the Teck Guan Quarry, Tawau, southeast Sabah. The Kalumpang Formation consists predominantly of interbedded mudstone and sandstone (graywacke), conglomerate, limestone, marl, chert and volcanic rocks. Five limestone samples have been collected and processed for petrographic analysis and identification of larger benthic foraminifera. The limestone is classified as packstone and mudstone. A total of seventeen species of larger benthic foraminifera have been identified. The foraminifera are divided into two assemblages namely Assemblage I and Assemblage II. Assemblage I is characterized by the presence of Lepidocyclina (Nephrolepidina) parva, Operculina sp. and Lepidocyclina (Eulepidina) formosa. This assemblage is an indicative of Aquitanian to Burdigalian in age (Early Miocene). Assembalge II comprises of Lepidocyclina (Nephrolepidina) sumatrensis, Lepidocyclina (Nephrolepidina) angulosa, Lepidocyclina (Nephrolepidina) ferreroi Lepidocyclina sp., Miogypsina sp., Katacycloclypeus annulatus, Katacyloclypeus martini, Cycloclypeus carpenteri, Cycloclypeus indopacificus, Cycloclypeus sp., Flosculinella bontangensis, Operculina complanata, Amphistegina bowdenensis and Amphistegina sp. This assemblage is an indicative of Langhian to Serravallian age (Middle Miocene). The foraminiferal assemblages suggest that the depositional environment was a warm tropical shallow-marine at the fore-reef shelf zone.

Benthic foraminifera as biostratigraphical and paleoecological indicators: An example from Oligo-Miocene deposits in the SW of Zagros basin, Iran

The Asmari Formation is a predominantly carbonate lithostratigraphic unit that outcrops in the Zagros Basin. Micropaleontological studies of the Asmari Formation in the Dehdasht area led to the identification of 51 species of foraminifera taxa. Among the foraminifera, Nummulites cf. vascus, Operculin sp., Operculina complanata, Eulepidina dilatata, Eulepidina elephantine, Ditrupa sp., Miogypsina sp., Elphidium sp. 14, and Borelis melo curdica are the most important. The Lepidocyclina-Operculina-Ditrupa assemblage zone represents the Rupelian–Chattian age. The Aquitanian age is also defined by co-occurrence of Miogypsina sp. and Elphidium sp. 14, and finally, the first occurrence of Borelis melo curdica represents the Burdigalian. Based on faunal assemblages, the following paleoenvironmental settings are determined for the deposition of the study section: (1) the deep, offshore settings in the aphotic zone dominated by pelagic and small benthic foraminifera; (2) the low energy, turbid and low light parts of the oligophotic zone characterized by large and flat lepidocyclinids (Eulepidina) and Nummulitidae; (3) the low turbidity, deeper part of the inner ramp dominated by Miogypsinoides, Neorotalia, Lepidocyclina, Operculina and Archias; (4) the shallow, marginal marine environment exposed to salinity fluctuations (short-term salinity fluctuations or fully marine conditions) dominated by small benthic Foraminifera (Ammonia and Elphidium); (5) highly translucent, shallowest part of the inner ramp dominated by representatives of Borelis, Meandropsina and Peneroplis. The biotic assemblages represent warm tropical waters with oligotrophic to slightly mesotrophic conditions.

Micropalaeontology and palaeoenvironments of the Miocene Wadi Waqb carbonate of the northern Saudi Arabian Red Sea

ABSTRACTThe Saudi Arabian Red Sea stratigraphy consists of a variety of lithologies that range from evaporites, deep- and shallow-marine siliciclastics and carbonates, biostratigraphically constrained to range from the Late Cretaceous, Campanian, to Late Pliocene. The succession consists of pre-rift Mesozoic and Palaeogene sediments, and syn-rift and post-rift late Palaeogene and Neogene sediments. Three main episodes of shallow-marine carbonate deposition can be determined, including those of the earliest Early Miocene Musayr Formation of the Tayran Group later Early Miocene Wadi Waqb Member of the Jabal Kibrit Formation and of the Pliocene Badr Formation of the Lisan Group. The Midyan area of the northern Red Sea offers a unique window into the Cretaceous and Miocene succession that is otherwise only present in the deep subsurface. The sediments are of hydrocarbon interest because of the presence of source rocks, siliciclastic and carbonate reservoirs. The Wadi Waqb reservoir is hosted within the Wadi Waqb Member of the Jabal Kibrit Formation, and is of latest Early Miocene to possibly earliest Middle Miocene age. It is considered to have formed a fringing reef complex that formed a steep, fault-influenced margin to a narrow platform, similar to Recent coralgal reefs of the Red Sea.The Wadi Waqb Member is exposed on the east and west flanks of the Ifal Plain. The bioclasts are considered to have traveled as a submarine carbonate debris flow 25 km from their presumed source to the east and possibly the west, and consist mostly of rhodoliths, echinoid and coral fragments together with the benthonic larger foraminifera Operculinella venosa, Operculina complanata, Heterostegina depressa and Borelis melo. The planktonic foraminifera include species of Globigerina, Globigerinoides and Praeorbulina; no specimens of the Middle Miocene planktonic foraminiferal genus Orbulina have yet been encountered in the thin sections. The presence of Borelis melo melo, and of B. melo curdica within the region, indicates a latest Early Miocene age. No specimens of the age-equivalent larger benthonic foraminiferal genera Miogypsina or Lepidocyclina have been observed, and this is consistent with evidence from the Wadi Waqb equivalent carbonates elsewhere in the Red Sea and Gulf of Suez.In the east, the Wadi Waqb is represented by discontinuous fringing rhodolith and coral reefs that are welded to steep cliffs of granitic basement. In Wadi Waqb, located in hills that form the western margin to the Ifal Plain, the Wadi Waqb carbonates consist of packstones containing autochthonous planktonic foraminifera and abundant shallow-marine microfossils that are considered to have been derived from the basement-founded rhodolith and coral reefs in the east. The Wadi Waqb reservoir is located beneath the central part of the Ifal Plain, approximately midway down a ramp between the in situ rhodolith-coral reefs and the mixed allochthonous and autochthonous facies at Wadi Waqb. The reservoir contains biofacies similar to those exposed in Wadi Waqb, and indicative of a deep-marine environment, in excess of 50 m water depth. The Wadi Waqb carbonates display sedimentological and petrographic features that closely resemble those described from stratigraphically equivalent carbonates from the localities along the west coast of the Gulf of Suez, including Abu Shaar, where three depositional facies have been defined. It is apparent that these shallow-marine carbonates were established along the west and east rift margins of the Red Sea-Gulf of Suez rift complex prior to their dislocation during the Late Miocene and Pliocene by the left-lateral Aqaba faulting.

Anthropogenic impact on Andaman coast monitoring with benthic foraminifera, Andaman Sea, India

The concept of anthropogenic impact is extremely important to be considered while analysing the ecology of coast and shelf zones. For centuries, these zones have been the epicentres for various human activities, including urbanisation, construction of sea ports and harbours, development of natural reservoirs (including oil production and fishing), marine aquaculture, shipping, recreation and many others. Many of the activities in progress on both sides of the shoreline provide 50% or more of the gross State/UT (Union Tertiary) product for surrounding states. The data shows that land-based and atmospheric sources account for about two-thirds of the total contamination found in the marine environment, constituting 44 and 33%, respectively. The greatest anthropogenic pollution pressure undoubtedly falls on the shelf zones and coastal areas. To prove this theory, a total of 25 bottom sediment samples were collected within the depth zone of 5 fathoms from the South Andaman coastal fringe for sediment geochemistry studies and foraminiferal analysis. The samples were further analysed for heavy metal pollutants like Co, Cu, Mn, Pb and Zn. The study yielded 20 benthic foraminiferal species. Of these, five benthic species were living including Ammonia beccarii, Calcarine calcar, Elphidium crispum, Operculina complanata and Nonion deppresula. The presence of deformed specimens and the domination of Ammonia spp. are indications of a polluted environment. Sampled coral reefs had high abundances of Operculina spp. The highest counts of benthic microbiota were found in finer sediment. Species diversity is very limited along the coastal fringe of South Andaman Island in comparison with fauna from the coast of India. This first report of benthic foraminifera from South Andaman Island will allow us to assess future impacts of marine pollution because foraminiferal deformations are positively correlated to the concentrations of heavy metals (Cr, Cu, Mn, Pb and Zn).

FIRST RECORD OF THE CO-OCCURRENCE OF WESTERN TETHYAN AND INDO-PACIFIC LARGER FORAMINIFERA IN THE BURDIGALIAN OF THE MEDITERRANEAN PROVINCE

A revision of (early) Burdigalian hyaline larger foraminifera based on the biometric study of miogypsinids, lepidocyclinids, and nummulitids from eastern Turkey provides new insights into their taxonomy and paleo-biogeography in the Tethys region. Data from the Adilcevaz Formation show a strong similarity to occurrences from Southeast Asia in that they include Cycloclypeus , Eulepidina , and “ribbed” Nephrolepidina , an assemblage not previously recorded from age-equivalent deposits in the circum-Mediterranean region. The association and the occurrences of these taxa in Lower Miocene deposits from the Indo–West Pacific areas have been widely reported. The species designation of Nephrolepidina and Eulepidina , in the absence of well-demonstrated comparable biometric and conflicting stratigraphic data from the Indo–West Pacific areas, is usually problematic. The Turkish taxa bear a close resemblance to N. sumatrensis and E. formosa , whilst Cycloclypeus is represented by C. eidae , which is widespread in the Indo-Pacific Early Miocene. These taxa are accompanied by Miolepidocyclina burdigalensis , a well-documented side branch of the main Miogypsina lineage in the circum-Mediterranean region; Miogypsina globulina , a worldwide tropical species common to both provinces; and Operculina complanata . Our data provide the first foraminiferal evidence from Turkey suggesting a main westward migration of several important groups from Southeast Asia to the eastern Mediterranean during the (early) Burdigalian. This faunal incursion is the most significant compared to other Late Oligocene–Early Miocene foraminiferal events in Turkey.

RECONSTRUCTING HOLOCENE SEA-LEVEL CHANGE FOR THE CENTRAL GREAT BARRIER REEF (AUSTRALIA) USING SUBTIDAL FORAMINIFERA

We assessed the utility of subtidal foraminifera to reconstruct Holocene relative sea levels from the central Great Barrier Reef shelf, Australia. We collected contemporary foraminiferal samples from Cleveland Bay and Bowling Green Bay, with water depths from 24.2 m to 248.0 m Australian Height Datum (AHD). The subtidal foraminiferal assemblages were divided into two distinct foraminiferal zones: an inner shelf zone occupied by Elphidium hispidulum, Pararotalia venusta, Planispirinella exigua, Quinqueloculina venusta and Triloculina oblonga; and a middle shelf zone dominated by Amphistegina lessonii, Dendritina striata and Operculina complanata. The zonations of the study areas and relative abundances of individual species indicate that the distributions of subtidal foraminifera are related to water depth. We used the subtidal data to develop a transfer function capable of inferring past water depths of sediment samples from their foraminiferal content. The results indicated a robust performance of the transfer function (r 2 jack 5 0.90). We produced ten sea-level index points, which revealed an upward trend of Holocene relative sea level from 28.86 6 4.5 m AHD at 9.3–8.6 cal kyr BP to a mid-Holocene high stand of +1.72 6 3.9 m AHD at 6.9–6.4 cal kyr BP. Sea level subsequently fell from the highstand to the present-day. The sea-level reconstructions are consistent with geophysical models and previous published data.

Decapod crustaceans from the Oligocene of the Ligure Piemontese Basin, northern Italy

Lithologically, the decapod-bearing levels of Rupelian (Oligocene) age in the Ligure Piemontese Basin, are characterized by an alternation of greyish blue marls with nodular elements and silt-rich, occasionally sandy, marls. The fossil studied for the present note have been collected mainly from pebbles or nodules which were eroded out of the higher levels exposed of this sedimentary complex, referred to as the ‘Formazione di Molare’. These levels overli the ‘Formazioni continentali delle Brecce di Costa Cravara e Pianfolco’, studied by Charrier et al. (1964) and dated as Early Rupelian. The levels yielding brachyuran fossils were attributed by Allasinaz (1987) to the transition between the ‘Formazione di Molare’ and the overlying ‘Marne di Rigoroso’, and by Bianco (1985) and Balossino & Bianco (1986) to the biozone of the foraminifer Operculina complanata (Defrance).

Lower Miocene stratigraphy of the Gebel Shabrawet area, north Eastern desert Egypt

The Lower Miocene carbonate/siliciclastic sequence of the Shabrawet area, comprises a complex alternation of autochthonous and allogenic sediments. The sequence can be subdivided into two lithostratigraphic units. The lower unit (unit I) is equivalent to the Gharra Formation. It is mainly clastic and composed of sandstones, siltstones and shales with minor limestone intercalations. These sediments are rich in Clypeaster spp., Scutella spp., Miogypsina intermedia, Operculina complanata, and smaller foraminifera. The upper unit (unit II) was considered by previous workers as being equivalent to the Marmarica Formation. It consists mainly of non-clastic rocks, dominated by sandy and chalky limestones rich in larger foraminifera (miogypsinids and nummulitids). This unit is topped by a highly fossiliferous ( Heterostegina, Operculina and Planostegina) sandy limestone. The present study places both units in the Gharra Formation and reports for the first time M. intermedia from the Miocene sequence of the Shabrawet area.

Foraminifera from the Bay of Jakarta, Java

Foraminifera from the North coast of Java have been described by MILLET (1898-1904); by KEIJZER (1935). The Siboga Expedition did not sample on the Java coast; most of the species described by Millet were also collected elsewhere in the Indonesian Archipelago. Keijzer did not have the intention to describe the faunas he gathered, but he mentions the occurrence of many species at the coast at Rembang, East of Soerabaia and the Strait of Madoera. The list of species described by him is as follows: Cornuspira involvens (Reuss); not found in the Bay of Jakarta. Biloculina vespertilio Schlumberger; idem. Triloculina tricarinata d’Orbigny; found in the Bay of Jakarta. Triloculina trigonula (Lamarck); not found in the B. of J. Triloculina rupertiana (Brady); found in the B. of J. Triloculina fichteliana d’Orbigny; found in the B. of J.; now known as Flintina bradyana Cushman. Spiroloculina planissima (Lamarck); not found in B. of J. Spiroloculina depressa d’Orbigny; not found in B. of J. Spiroloculina grateloupi d’Orbigny; found in B. of J.; given here as S. communis Spiroloculina nitida d’Orbigny; not found in B. of J. Quinqueloculina venusta Karrer; not found in B. of J. Quinqueloculina kerimbatica (Heron-Allen and Earland); found in B. of J. Quinqueloculina seminulum (Linne); found in B. of J.; it is in reality Quinqueloculina bicostata d’Orbigny. Massilina agglutinans Keijzer; not found in B. of J.; this was not a new species, as Keijzer believed, but Pseudomassilina australis Cushman, 1932, as the inner structure proves. Discorbis globularis (d’Orbigny); not found in B. of J. Operculina complanata (Defrance); found in the B. of J. Textularia gramen d’Orbigny; found in the B. of J.; this is Textularia kerimbaensis Said. Textularia agglutinans d’Orbigny; found in the B. of J.; this is Valvotextularia foliacea (Heron-Allen and Earland). Rotalia papillosa Brady; found in B. of J.; this is Rotalidium concinnum (Millet). Rotalia schroeterania Parker and Jones; found in B. of J.; now known as Pseudorotalia. The material studied here was originally collected by the Laboratory for Investigation of the Sea at Batavia, in 1937 and later years (textfig. 1). It was gathered for the study of the molluscs, but the finer residues contained many Foraminifera. As will be seen from the chart, Foraminifera were found mainly in the western part of the Bay of Jakarta; from the Eastern and coastal stations no Foraminifera were collected; this may be a consequence of the low salinity of these parts. The richer faunas were found in the northwestern part; the direction of the current is from west to east, so in this part the salinity will have been high, as well as the concentration of 02. In the eastern part, the salinity must have been low, and much detritus must have been found there from rivers and sewage. From north-west to south-east the samples contain less and less species of Foraminifera, till in the Stations H4,F3,G3, E2 the samples mainly contain many specimens of Pseudorotalia schroeteriana, Asterorotalia pulchella and Elphidium batavum.

On the Microbiostratigraphy of the Yatsuo Group in the Yatsuo District of Toyama Prefecture

The microbiostratigraphy and size distribution of the sedimentary rocks by mechanical analysis of the Yatsuo Group in the type area in Toyama Prefecture is presented., The middle Neogene Yatsuo Group consists of four formations, namely, Nirehara, Iwaine, Kurosedani and Joyama in ascending order., Some of these formations are subdivided into members., The stratigraphy of the said group has already been described elsewhere (TSUDA 1952, NAKASEKO 1952)., The fossil foraminifers were collected from three standard sections along the Jinzu, Kubusu and Yamada Rivers where are developed the Kurosedani and Joyama formations of the upper part of the Yatsuo Group., Five types of sedimentary rocks are classified by size distribution and the characteristic of each type is given in Figure 1., From the distribution of the foraminifers predominant species were recognized in each section by which the establishment of faunules was possible., By these faunules the upperpart of the Yatsuo Group was divided into four zonules, as follows: Martinottiella cf., communis-Uvigerina farinosa Zonule Buliminella cf., elegantissima-Nonion japonicum Zonule Operculina complanata japonica-Nonion japonicum Zonule Rotalia papillosa-Operculina complanata japonica-Nonion japonicum Zonule The relationship of the faunules to the above mentioned four zonules is shown in Table 3., Compared with the subdivision by IKEBE and NAKASEKO in western "Toyama Basin", the uppermost seems to belong to their Nodosaria insecta Zone and the lower three to their Miogypsina kotoi Zone.,