In this research, the Turonian-early Campanian sedimentary succession of the Abderaz Formation with 510 mthick (comprising: light grey shale and marls) was studied in the type section in eastern Kopeh-Dagh basin. The ...In this research, the Turonian-early Campanian sedimentary succession of the Abderaz Formation with 510 mthick (comprising: light grey shale and marls) was studied in the type section in eastern Kopeh-Dagh basin. The statistical analysis of the morphotype groups of the identified planktonic foraminifers shows that most of them are shallow water forms (SWF) and deep water forms (DWF). The high planktonic to benthic ratio indicates particular oligotrophic conditions and sedimentation in relatively deeper zones of a marine environment. The salinity of sea water during Coniacian was in the minimum level, whereas it reached maximum in Coniacian-Santonian boundary. Comparing Planktonic assemblages from the study formation with those from the Cretaceous biogeographical provinces reflects a close relationship between the identified species and the planktonic forms of the Tethyan provinces.展开更多
The low diversity agglutinated foraminifers are recovered from the Qihulin Formation of the Longzhaogou Group in eastern Heilongjiang, China. The foraminiferal fauna consists of 9 species of 5 genera. The common membe...The low diversity agglutinated foraminifers are recovered from the Qihulin Formation of the Longzhaogou Group in eastern Heilongjiang, China. The foraminiferal fauna consists of 9 species of 5 genera. The common members are Cribrostomoides nonioninoides (Reuss), Haplophragmoides concavus (Chapman), H. gigas minor Nauss. Although the diagnostic zonal taxa are absent in the agglutinated fauna, according to the global stratigraphic distribution of the above-mentioned species, and the associated Pseudohaploceras ammonite fauna, the foraminiferal fauna may be of a Barremian-Aptian (Early Cretaceous) age.展开更多
The northern flank of the Tindouf Syncline in southern Morocco exhibits a continuous, well exposed Carboniferous succession with limestones of Late Asbian to Early Bashkirian age containing rich and diverse foraminife...The northern flank of the Tindouf Syncline in southern Morocco exhibits a continuous, well exposed Carboniferous succession with limestones of Late Asbian to Early Bashkirian age containing rich and diverse foraminiferal and rugose coral assemblages. Analysis of these assemblages provides new data on the relatively poorly known Saharan basins. The palaeobiogeographical relationship of the Tindouf Basin with other Palaeotethyan basins is complex. Although there is a predominance of cosmopolitan taxa for the Palaeotethys, it is recognized that there was an influence of basins from NW Europe, such as the UK and Ireland. Some taxa are recorded in both NW Europe and Tindouf without any characteristic contributions from intermediate basins in northern Morocco. The neighbouring Béchar Basin in Algeria presents distinct assemblages. The bulk of the data analyzed suggest that this sector of the western Palaeotethys can be subdivided into four palaeobiogeographical subprovinces: the Atlantic Subprovince (UK, Ireland, N France and Belgium), the Mediterranean Subprovince (Pyrenees, Montagne Noire, Betic Cordillera, Rif (N Morocco) and Balearic Islands), and the Saharan Subprovince (Béchar, Reggan, Ahnet-Mouydir and Tindouf). In between, mobile belts of mixed faunal assemblage characteristics are observed (e.g., SW Spain and Central Meseta) forming the West peri-Gondwanan Subprovince.Analysis of the Tindouf Basin faunas shows that, as in other Saharan basins, there is a high diversity and abundance of foraminiferal taxa, with a higher proportion of survivors and longer stratigraphic ranges; these features also are mirrored by rugose corals. This emphasizes the longevity of the carbonate platform in a tropical setting, where periodic transgressions introduced new assemblages, and oceanic currents are interpreted as one of the main controlling factors for the distribution of the taxa in these subprovinces. Moreover, not only were water temperatures on the platform higher, but also tectonic stability greater. It is considered that the effects of the first phases of the Gond-wanan glaciation were minimal on the Tindouf faunas.展开更多
Boron isotopic compositions in marine planktonic foraminifers can record changes in seawater pH and hence provide a new tool to reconstruct the changes of paleo-atmospheric PCO2.Here a comparative study was done on bo...Boron isotopic compositions in marine planktonic foraminifers can record changes in seawater pH and hence provide a new tool to reconstruct the changes of paleo-atmospheric PCO2.Here a comparative study was done on boron isotopes and trace element abundances of planktonic foraminifers,Globigerinoides sacculifer and Globigerinoides ruber from three tropical ODP sites,Site 806B,Site 664C and Site 999A.It is demonstrated here that G.ruber is a better species to be used for downcore boron isotope analyses on glacial-interglacial scales,particularly since G.sacculifer is prone to dissolution causing unexpectedly light boron isotopes during glacial times.It has been shown that the trace elements composition of foraminifers (i.e.,Mg/Ca,U/Ca,B/Ca,and Li/Ca) can reflect the variations of seawater temperature and/or [CO3 2-].However,all of these systems are highly species de-pendent and affected by other vital effects,and it is therefore important to perform necessary calibrations when applying them to the downcore analyses.展开更多
During latest Devonian and early Carboniferous times,calcareous foraminifers were abundant,widely distributed,and showed the most rapid rate of evolution in the shallow?sea deposits.These factors,especially their fast...During latest Devonian and early Carboniferous times,calcareous foraminifers were abundant,widely distributed,and showed the most rapid rate of evolution in the shallow?sea deposits.These factors,especially their fast phylogenetic changes,make them an essen?tial element in biostratigraphic schemes of this time interval.However,the distribution patterns of calcareous foraminifers depend on a series of biological and non?biological factors,such as population sizes,dispersion,oceanic currents and temperatures,and substrate types,which are not always well?controlled when interpreting spatial and temporal distribution patterns.For this study,a dataset of calcareous foraminifers was compiled containing the tempo?ral distribution(biozone level)of 420 species belonging to 155 genera currently described from Strunian(latest Devonian)to basal Serpukhovian(Lower Carboniferous)key sections in southern China,and the presence of those species in eleven palaeobiogeographical units.The comparison of the regional Chinese diversity curve,which has a bell?shaped form with a dou?ble peak in the Ivorian,to a global curve shows the influence of local and regional factors.Mini?mum values in the Chinese Strunian,basal Tournaisian and early late Visean can be explained by the small number of studied outcrops,unfavourable facies and depositional gaps in these stratigraphic intervals in South China.This is especially obvious in the late Visean and Serpuk?hovian,which is a peak time of global diversity.The fall observed at that time interval in southern China is easily explained by the fact that this time peried is far less intensively studied and thus fewer data are present in the database.The opposite situation is seen around the TournaisianVisean boundary.Here,a peak is found in both regional and global curves,but that up to 87%of all known species are found in southern China seems to be unlikely,especially when the normal average value are 35%-40%.This anomalously high percentage is a consequence of the work undertaken on the Global Stratotype Section and Point(GSSP),and it shows that a species deficit may exist in the global curve.*Cluster,hierarchical cluster and Nonmetric multidimensienal Scalingel(NMDS)analyses have been calculated to study the palaeobiogeographical affinities of the southern Chinese calcareous foraminifers.The palaeobiogeographical patterns for the complete studied interval or parts of it(substages)are comparable on the genus and species level and stable throughtime.The assemblages found in southern China are well connected to other palaeo(bio)geo?graphical entities supporting the idea of relatively abundant widespread and cosmopolitan taxa in the studied interval.A cluster of South China,Europe and the Russian Platform is found in all analyses.This cluster often attached to the units Far-East Russia and Turkey rep?resents the northern Palaeotethyan Realm.The relatively close affinities between South China and North America cannot be well discussed yet.Chinese data for endemicity,geographical spread and biodiversity in the Tournaisian-Visean boundary interval can be roughly correlated to 3rd-order sea-level fluctuations.Migration patterns into and out of South China can only be suspected,but not yet quantified.展开更多
A rich foraminiferal assemblage,consisting of abundant Aulotortus sinuosus and A.tumidus in association with Lamelliconus multispirus,Endoteba ex gr.controversa,E.ex gr.badouxi,Endotebanella kocaeliensis,Endotriada ty...A rich foraminiferal assemblage,consisting of abundant Aulotortus sinuosus and A.tumidus in association with Lamelliconus multispirus,Endoteba ex gr.controversa,E.ex gr.badouxi,Endotebanella kocaeliensis,Endotriada tyrrhenica,Endotriadella wirzi,Malayspirina fontainei,Ammobaculites rhaeticus,Diplotremina astrofimbriata,Agathammina austroalpina,and others,was found in the Doi Long Formation of the Triassic Lampang Group,Northern Thailand.These foraminifers suggest that the formation is referable to the Carnian(early Late Triassic),which is consistent with the age estimated by ammonoids.In microfacies,peloidal grainstone,bioclastic grainstone,sponge-microbial boundstone,and oolitic grainstone were recognized in the Doi Long Formation.Based on microfacies,three depositional facies,the lagoon facies,reef facies,and shoal facies,are recognized in this formation.These lines of evidence are suggestive that the Doi Long Formation was deposited in a reef or bank setting rather than a ramp setting.展开更多
A compiled selected literature on some groups of microfossils of the Mesozoic and Cenozoic of the James Ross Basin,eastern Antarctic Peninsula,is presented here,in order to show how the microbiota has been modified ov...A compiled selected literature on some groups of microfossils of the Mesozoic and Cenozoic of the James Ross Basin,eastern Antarctic Peninsula,is presented here,in order to show how the microbiota has been modified over time,triggered by environmental changes.The analyzed microfossils consist of palynomorphs(mostly pollen grains,spores,and dinoflagellate cysts),foraminifers and bryozoans.Dinoflagellate cysts and pollen-spores have been recorded in Jurassic to Pleistocene sedimentary outcrops.Dinoflagellate cysts proved to be good indicators for productivity and/or nutrient availability,surface water temperature and chemistry,the position of ancient shorelines and paleoceanographic trends.Pollen and spores allowed reconstruction of floral community and thus characterization of the climate that prevailed on the continent.Foraminifera,recovered from the Lower Cretaceous to the Pleistocene sedimentary rocks,provided information about the bathymetry,showing different marine settings(e.g.,coastal,inner neritic,outer neritic,upper bathyal)in different localities.The bryozoan record is restricted to the Cenozoic.Their colonial growth-forms reflect several environmental conditions such as shallow waters with a low rate of sedimentation,hard substrate and moderate or strong current action for the analyzed localities.The study of the Antarctic ecosystems based on the fossil microbiota and their response to the climate and the continental configuration changes,allowed understanding of the composition and dynamics of the polar environments,which have an important role in the Earth climate.展开更多
Foraminifer is a very useful microorganism to perform biostratigraphical zonation of the Upper Jurassic. Foraminiferal biozones are calibrated by the ammonite standard zones and can be used for intra- and interregiona...Foraminifer is a very useful microorganism to perform biostratigraphical zonation of the Upper Jurassic. Foraminiferal biozones are calibrated by the ammonite standard zones and can be used for intra- and interregional correlations. Furthermore, the fossil record of foraminiferal faunas is well known among basins of the Northern Eurasia and is also used for accurate palaeoenvironmental, palaeobiogeographical, or biofacial reconstructions. It allows identifying a complex set of biotic and abiotic events which may be used to propose a more general palaeoecoloecological and palaeoceanographical reconstruction of the Subboreal, Boreal, and Arctic seas. Then, the late Kimmeridgian Northern Eurasian seas formed a network of well-connected palaeobasins during the sea-level rise and resulted in rather similar palaeoenvironmental conditions.展开更多
The Pagoda Formation is a lithologically and biologically distinctive unit among the Upper Ordovician. The strata are characterized by a nodular limestone, which yields fossil assemblages of high diversity. Conodonts ...The Pagoda Formation is a lithologically and biologically distinctive unit among the Upper Ordovician. The strata are characterized by a nodular limestone, which yields fossil assemblages of high diversity. Conodonts of 14 genera 20 species （6 undetermined species） and ostracods of 14 genera 26 species （16 undetermined species） are identified. In addition, spherical radiolarians and minute-walled foraminifers were first reported from this formation in South China. The conodont assemblage is attributed to the Hamarous europaeus Zone, which indicates the Early Katian Age. The conodont HDS biofacies, along with thin-shelled ostracods, spherical radiolarians and foraminifers, suggest relatively deep and quiet water depositional environment. Accordingly, these fossil materials not only enrich the diversity of the Pagoda biota, but also provide evidence for discussions of deposi- tional environments and stratigraphic correlations for the Pagoda Formation.展开更多
In the present study, over 3000 m of Upper Cretaceous sediments （Tarbur Formation） in seven stratigraphic, columnar sections were studied. The area is located in the Zagros mountain ranges of southwestern Iran, attr...In the present study, over 3000 m of Upper Cretaceous sediments （Tarbur Formation） in seven stratigraphic, columnar sections were studied. The area is located in the Zagros mountain ranges of southwestern Iran, attributed to the converging continental Arabian Shield, and is interpreted as the result of subduction and collision. Based on foraminiferal studies of the Tarbur Formation in the sections, we have established many new biozones in the stratigraphic sections. However, investigations of the biozones indicate that there is no lithostratigraphic variation between the Upper Cretaceous and Lower Paleocene sediments in some of the studied sections. The concept of widespread formations and lithologic correlations is not applicable in this area, probably as a result of the tectonic unrest at that time. The biostratigraphic boundary between the Cretaceous and the Lower Paleocene is nevertheless well defined by the intraformational boundary in the sections.展开更多
Cycloclypeus carpenteri is the largest extant benthic foraminifer,dwelling in the deep euphotic zone(a water depth between 60 and 130 m)of the warm oligotrophic Indo-West Pacific.This foraminifer harbors diatom endosy...Cycloclypeus carpenteri is the largest extant benthic foraminifer,dwelling in the deep euphotic zone(a water depth between 60 and 130 m)of the warm oligotrophic Indo-West Pacific.This foraminifer harbors diatom endosymbionts and the foraminifer-microalgal association acts like a holobiont.To verify that light is an important limiting factor controlling the vertical(depth)distribution of living Cycloclypeus holobionts,their physiological responses to light intensity were examined by short-term metabolic measurements and long-term incubations.Net oxygen production(OP)rates measured under different light levels using an oxygen microelectrode indicate that Cycloclypeus holobionts are daily net primary producers adapted to low light levels,with slight photoinhibition(reduced net OP rates relative to a light-saturated rate)over 100μmol photons m^(−2)s^(−1).Long-term growth increments of asexually reproduced juveniles incubated for two months at different light levels ranging from 0 to 100μmol photons m^(−2)s^(−1) show that Cycloclypeus holobionts are adapted to a low light level(∼5μmol photons m^(−2)s^(−1)),but can be acclimatized to a certain low light ranges(<50μmol photons m^(−2)s^(−1)).These experimental results confirm that light is an important environmental gradient affecting the vertical distribution of Cycloclypeus holobionts.展开更多
Benthic foraminiferal analysis of 29 samples in surface sediments from the southern Okinawa Trough is carried out. The results indicate that benthic foraminiferal abundance decreases rapidly with increasing water dept...Benthic foraminiferal analysis of 29 samples in surface sediments from the southern Okinawa Trough is carried out. The results indicate that benthic foraminiferal abundance decreases rapidly with increasing water depth. Percentage frequencies of agglutinated foraminifera further confirm the modern shallow carbonate lysocline in the southern Okinawa Trough. From continental shelf edge to the bottom of Okinawa Trough, benthic foraminiferal fauna in the surface sediments can be divided into 5 assemblages: (1) Continental shelf break assemblage, dominated by Cibicides pseudoungerianus, corresponds to subsurface water mass of the Kuroshio Current; (2) upper continental slope assemblage, dominated by Cassidulina carinata , Globocassidulina subglobosa, corresponds to intermediate water mass of the Kuroshio Current; (3) intermediate continental slope assemblage, dominated by Uvigerina hispi-da, corresponds to the Okinawa Trough deep water mass above the carbonate lysocline; (4) lower continental slope- trough bottom assemblage, dominated by Pullenia bulloides, Epistominella exigua and Cibicidoides hyalinus, corresponds to deep water mass of the Okinawa Trough; and (5) trough bottom agglutinated assemblage, dominated by Rhabdammina spp. , Bathysiphon flavidus, corresponds to strongly dissolved environment of the trough bottom. The benthic foraminiferal fauna in the southern Okinawa Trough are controlled jointly by water masses and food supply. Water temperature, oxygen concentration and carbonate dissolution of the water masses are important controlling factors especially for the continental shelf break and trough bottom assemblages. The food supply also plays an important role in these benthic foraminiferal assemblages along the western slope of the Okinawa Trough. Both the abundance and the 5 assemblages of benthic foraminifera correspond well to the organic matter supply along the continental slope and a lateral transport of TSM (total suspended matter) and POC (particulate organic carbon) from the shelf break to the deep water is also an important food supply for benthic fauna in this region.展开更多
The main purpose of this paper is the sequence stratigraphy and biostratigraphy of lower Tertiary sediments on the base of larger benthic foraminifera in northeast of Iran (Chehel-Kaman Formation). This formation main...The main purpose of this paper is the sequence stratigraphy and biostratigraphy of lower Tertiary sediments on the base of larger benthic foraminifera in northeast of Iran (Chehel-Kaman Formation). This formation mainly consists of Limestone, dolomite and interbeds of sand, shale and evaporate sediments. Petrographical studies indicate that these sediments may have been deposited on a shallow carbonate platform ramp and consist of 4 carbonate lithofacies (15 subfacies). These lithofacies may have been deposited in open marine, shoal, lagoon and tidal flat environmental conditions. Sequence stratigraphy analysis led to identification of 4 third-order depositional sequences, bounded by type 2 (within the top of the underlying Pestehleigh Formation) and type 1 sequence boundaries (paleosol). Interpreted sea level curve in this basin can be relatively correlated with global curves during Paleocene time and a with a sea-level fall occurred in the latest Paleocene, followed by a rise in the earliest Eocene. Biostratigraphy study led to the identification of 32 larger benthic Foraminifera genera. The Paleocene/Eocene boundary has been probably recorded as a thin red paleosol horizon (~10 - 15 cm).展开更多
The GSSP for the base of the Santonian Stage is defined at 94.4 m in the eastern border of the“Cantera de Margas”quarry,Olazagutia(Navarra,N.Spain:42º52'05.3"N,2º11'40"W)and marked by the...The GSSP for the base of the Santonian Stage is defined at 94.4 m in the eastern border of the“Cantera de Margas”quarry,Olazagutia(Navarra,N.Spain:42º52'05.3"N,2º11'40"W)and marked by the first occurrence(FO)of the inoceramid bivalve Platyceramus undulatoplicatus.This first occurrence is located about 9 m below the contact between a lower marly unit and an upper more calcareous unit.The FO of the planktonic foraminifer Sigalia carpatica is the secondary marker of the GSSP and first occurs 7 m below the primary marker,but it becomes consistently present about 4.2 m above the boundary.In addition,six peaks in the carbon stable isotope curve can be recognized between the Kingsdown Event 17.2 m below and the Bedwell Event 12.35 m above the GSSP.The basal Santonian GSSP was approved by the International Subcommission on Cretaceous Stratigraphy in September 2010,by the International Commision of Stratigraphy in April 2012,and ratified by the International Union of Geological Sciences in January 2013.展开更多
The GSSP for the base of the Chattian Stage(Paleogene System,Oligocene Series)is defined at meter level 197 in the Monte Cagnero section,which belongs to the pelagic succession of the Umbria–Marche basin(Urbania,cent...The GSSP for the base of the Chattian Stage(Paleogene System,Oligocene Series)is defined at meter level 197 in the Monte Cagnero section,which belongs to the pelagic succession of the Umbria–Marche basin(Urbania,central Italy:43°38′47.81″N–12°28′03.83″E).This level with an astronomical age of 27.82 Ma coincides with the highest common occurrence of the planktonic foraminifer Chiloguembelina cubensis at the base of planktonic foraminiferal O5 Zone and falls in the upper part of calcareous nannofossil NP24 Zone,in the lower part of dinocyst Dbi Zone,and in the lower Chron C9n.The proposal was approved by the International Subcommission of Paleogene Stratigraphy in July 2015,approved by the International Commission of Stratigraphy in August 2016,and ratified by the International Union of Geological Sciences in September 2016.展开更多
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...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 coexistence of the N. saipanensis and N. malatyaensis points to suitable palaeobiogeographic conditions of Central Iran to host Western and Eastern Tethyan taxa.展开更多
An integrated study of borehole data and outcrop of Mississippian （late Tournaisian to late Visean） rocks in Co. （County） Galway, western Ireland has enabled a more detailed geological map and lithostratigraphy to...An integrated study of borehole data and outcrop of Mississippian （late Tournaisian to late Visean） rocks in Co. （County） Galway, western Ireland has enabled a more detailed geological map and lithostratigraphy to be constructed for the region. Several carbonate formations have been distinguished by microfacies analysis and their precise ages established by micropalaeontological investigations using foraminifers and calcareous algae. In addition, palaeogeographic maps have been constructed for the late Tournaisian, and early to late Visoan intervals in the region. The oldest marine Mississippian （late Tournaisian） deposits are recorded in the south of the study region from the Loughrea/Tynagh area and further south in the Gort Borehole; they belong to the Limerick Province. They comprise the Lower Limestone Shale Group succeeded by the Ballysteen Group, Waulsortian Limestone and Kilbryan Limestone Formations. These rocks were deposited in increasing water depth associated with a transgression that moved northwards across Co. Galway. In the northwest and north of the region, marginal marine and non-marine Tournaisian rocks are developed, with a shoreline located NW of Galway City （Galway High）. The central region of Co. Galway has a standard Visdan marine succession that can be directly correlated with the Carrick-on- Shannon succession in counties Leitrim and Roscommon to the northeast and east as far as the River Shannon. It is dominated by shallow-water limestones （Oakport, Ballymore and Croghan Limestone Formations） that formed the Galway-Roscommon Shelf. This facies is lat- erally equivalent to the Tubber Formation to the south which developed on the Clare-Galway Shelf. In the southeast, basinal facies of the Lucan Formation accumulated in the Athenry Basin throughout much of the Visean. This basin formed during a phase of extensional tectonics in the early Visean and was probably connected to the Tynagh Basin to the east. In the late Visean, shallow-water limestones of the Burren Formation extend across much of the southern part of the region. They are characterized by the presence of rich concentrations of large brachiopod shells and colonial coral horizons which developed in predominantly high-energy conditions. These limestones also exhibit palaeokarstic surfaces and palaeosols which formed during regressive conditions of glacio-eustatically controlled cyclicity. Locally, slightly deeper water, lower energy conditions developed on the shelf with the formation of rare bryozoan-rich mud-mounds. Deep-water basinal facies were maintained in the central and southeastern parts of the region between the two shelves with the persistence of the Lucan Formation. Ac- tive syn-sedimentary faulting influenced deposition in the Visean and interfingering of basinal sediments with slumps and shallow-water shelf carbonates are recognized.展开更多
An SEM study has been conducted to examine the ultrastructures in the spirotheca of Fusulinella and to reveal the ultra-features of the basic layers consisting of the spirotheca of Fusulinella. The study has demonstra...An SEM study has been conducted to examine the ultrastructures in the spirotheca of Fusulinella and to reveal the ultra-features of the basic layers consisting of the spirotheca of Fusulinella. The study has demonstrated that the diaphanotheca in the spirotheca of Fusulinella could be considered as a secondary structure.展开更多
Encrusting foraminifers locally can play an essential reef-forming role such as in the Carnian fossiliferous Hallstatt Limestones of Austria where a dense succession of hardgrounds occurs with numerous small buildups(...Encrusting foraminifers locally can play an essential reef-forming role such as in the Carnian fossiliferous Hallstatt Limestones of Austria where a dense succession of hardgrounds occurs with numerous small buildups(up to 2 cm high)composed of sessile foraminifers.Similar foraminiferal micro-buildups occur in a 10-cm-thick bed in the basinal facies in the basal Zechstein(Upper Permian)strata in the Radlin 60 borehole,in western Poland.Foraminiferal micro-buildups of presumably columnar habit account for up to a half of the volume.The growth of columns was interrupted by hiatal surfaces,although usually the growth of columns was restored afterwards.In the upper part of the bed with foraminiferal micro-buildups,the foraminiferal encrustations become visibly less abundant,and in most cases,they have a shape of less regular masses.The bed with foraminiferal micro-buildups abounds in closely spaced discontinuity(hiatal)surfaces,occasionally encrusted by foraminifers.Tubular foraminifers in the bed with foraminiferal micro-buildups are accompanied by various encrusting organisms,possibly microbes;they are grouped under the name Palaeonubecularia.In the intercolumnar spaces,common Midiella sp.occur.During deposition,the conditions were mostly suboxic,and various types of ferruginous morphs,common in the lower part of the bed,suggest that dysoxic-anoxic interfaces produced various microaerophilic environments for iron-bacteria.The environmental conditions during the deposition of the upper part of the bed were very similar to those characterizing the starved basin environment in which the bioclastic-peloidal and oncoidal sediments in the Zechstein Limestone have been formed.In turn,the lower part of the bed registers the transition from normal(=not starved)marine conditions,with a clear chemocline,to the starved basin conditions.The deposition of the bed was coeval with the Kupferschiefer deposition based on the correlation ofδ13C curves,which implies that the previous stratigraphical concept of basal Zechstein strata has to be re-evaluated.展开更多
A new early Visean coral assemblage has been recorded from turbidite facies in the southern part of the AzrouKhenifra Basin,northwest of Khenifra,central Morocco.The newly discovered Ba Moussa West(BMW)coral fauna inc...A new early Visean coral assemblage has been recorded from turbidite facies in the southern part of the AzrouKhenifra Basin,northwest of Khenifra,central Morocco.The newly discovered Ba Moussa West(BMW)coral fauna includes Siphonophyllia khenifrense sp.nov.,Sychnoelasma urbanowitschi,Cravenia lamellata,Cravenia tela,Cravenia rhytoides,Turnacipora megastoma and Pleurosiphonella crustosa.The early Visean age of the coral assemblage is supported by foraminiferal and conodont data,with the recognition of the basal Visean MFZ9 Zone.This confirms that the first transgression in the Azrou-Khenifra Basin was during the earliest Visean.The allochthonous coral assemblage was recovered from coarse-grained proximal limestone debris flow and turbidite beds within a faultbounded unit,lying to the west of a thrust syncline containing upper Visean limestones.No evidence exists of the former early Visean shallow-water platform from which the corals were derived.All other in situ platform carbonate rocks around the southern margin of the Azrou-Khenifra Basin are probably of late Visean(Asbian–Brigantian)age.The early Visean Ba Moussa West coral fauna can be compared with that at Tafilalt in eastern Morocco,as well as in other Saharian basins of Algeria.Many of the genera and species in the Ba Moussa West assemblage are identical to those in NW Europe,with which it must have had marine connections.The new rugose species described,Siphonophyllia khenifrense,is probably endemic to North Africa.Its ecological niche in NW Europe was occupied by S.cylindrica or S.aff.garwoodi.展开更多
文摘In this research, the Turonian-early Campanian sedimentary succession of the Abderaz Formation with 510 mthick (comprising: light grey shale and marls) was studied in the type section in eastern Kopeh-Dagh basin. The statistical analysis of the morphotype groups of the identified planktonic foraminifers shows that most of them are shallow water forms (SWF) and deep water forms (DWF). The high planktonic to benthic ratio indicates particular oligotrophic conditions and sedimentation in relatively deeper zones of a marine environment. The salinity of sea water during Coniacian was in the minimum level, whereas it reached maximum in Coniacian-Santonian boundary. Comparing Planktonic assemblages from the study formation with those from the Cretaceous biogeographical provinces reflects a close relationship between the identified species and the planktonic forms of the Tethyan provinces.
基金the German Academic Exchange Service (DAAD) Scholarship, Pilot Project of Knowledge Innovation Program, CAS (Grant No. KZCX2-114) the National Natural Science Foundation of China (Grant Nos. 40252003, 40072004)+1 种基金 the Scientific Research Foundation for the Returned Overseas Chinese Scholars, Ministry of Education (Grant No. 2002247) State Key Laboratory Paleobiology and Stratigraphy, CAS (Grant No. 203111).
文摘The low diversity agglutinated foraminifers are recovered from the Qihulin Formation of the Longzhaogou Group in eastern Heilongjiang, China. The foraminiferal fauna consists of 9 species of 5 genera. The common members are Cribrostomoides nonioninoides (Reuss), Haplophragmoides concavus (Chapman), H. gigas minor Nauss. Although the diagnostic zonal taxa are absent in the agglutinated fauna, according to the global stratigraphic distribution of the above-mentioned species, and the associated Pseudohaploceras ammonite fauna, the foraminiferal fauna may be of a Barremian-Aptian (Early Cretaceous) age.
基金funded by the Spanish Ministerio de Innovación y Ciencia (research project CGL2009-10340BTE)ongoing research development(research project CGL2012-30922BTE)
文摘The northern flank of the Tindouf Syncline in southern Morocco exhibits a continuous, well exposed Carboniferous succession with limestones of Late Asbian to Early Bashkirian age containing rich and diverse foraminiferal and rugose coral assemblages. Analysis of these assemblages provides new data on the relatively poorly known Saharan basins. The palaeobiogeographical relationship of the Tindouf Basin with other Palaeotethyan basins is complex. Although there is a predominance of cosmopolitan taxa for the Palaeotethys, it is recognized that there was an influence of basins from NW Europe, such as the UK and Ireland. Some taxa are recorded in both NW Europe and Tindouf without any characteristic contributions from intermediate basins in northern Morocco. The neighbouring Béchar Basin in Algeria presents distinct assemblages. The bulk of the data analyzed suggest that this sector of the western Palaeotethys can be subdivided into four palaeobiogeographical subprovinces: the Atlantic Subprovince (UK, Ireland, N France and Belgium), the Mediterranean Subprovince (Pyrenees, Montagne Noire, Betic Cordillera, Rif (N Morocco) and Balearic Islands), and the Saharan Subprovince (Béchar, Reggan, Ahnet-Mouydir and Tindouf). In between, mobile belts of mixed faunal assemblage characteristics are observed (e.g., SW Spain and Central Meseta) forming the West peri-Gondwanan Subprovince.Analysis of the Tindouf Basin faunas shows that, as in other Saharan basins, there is a high diversity and abundance of foraminiferal taxa, with a higher proportion of survivors and longer stratigraphic ranges; these features also are mirrored by rugose corals. This emphasizes the longevity of the carbonate platform in a tropical setting, where periodic transgressions introduced new assemblages, and oceanic currents are interpreted as one of the main controlling factors for the distribution of the taxa in these subprovinces. Moreover, not only were water temperatures on the platform higher, but also tectonic stability greater. It is considered that the effects of the first phases of the Gond-wanan glaciation were minimal on the Tindouf faunas.
基金funded by ORS fellowship supplemented by he Department of Earth Scieces,University of Bristol to Ni R. Y.National Natural Science Foundation of China (Grant No.40703014)
文摘Boron isotopic compositions in marine planktonic foraminifers can record changes in seawater pH and hence provide a new tool to reconstruct the changes of paleo-atmospheric PCO2.Here a comparative study was done on boron isotopes and trace element abundances of planktonic foraminifers,Globigerinoides sacculifer and Globigerinoides ruber from three tropical ODP sites,Site 806B,Site 664C and Site 999A.It is demonstrated here that G.ruber is a better species to be used for downcore boron isotope analyses on glacial-interglacial scales,particularly since G.sacculifer is prone to dissolution causing unexpectedly light boron isotopes during glacial times.It has been shown that the trace elements composition of foraminifers (i.e.,Mg/Ca,U/Ca,B/Ca,and Li/Ca) can reflect the variations of seawater temperature and/or [CO3 2-].However,all of these systems are highly species de-pendent and affected by other vital effects,and it is therefore important to perform necessary calibrations when applying them to the downcore analyses.
文摘During latest Devonian and early Carboniferous times,calcareous foraminifers were abundant,widely distributed,and showed the most rapid rate of evolution in the shallow?sea deposits.These factors,especially their fast phylogenetic changes,make them an essen?tial element in biostratigraphic schemes of this time interval.However,the distribution patterns of calcareous foraminifers depend on a series of biological and non?biological factors,such as population sizes,dispersion,oceanic currents and temperatures,and substrate types,which are not always well?controlled when interpreting spatial and temporal distribution patterns.For this study,a dataset of calcareous foraminifers was compiled containing the tempo?ral distribution(biozone level)of 420 species belonging to 155 genera currently described from Strunian(latest Devonian)to basal Serpukhovian(Lower Carboniferous)key sections in southern China,and the presence of those species in eleven palaeobiogeographical units.The comparison of the regional Chinese diversity curve,which has a bell?shaped form with a dou?ble peak in the Ivorian,to a global curve shows the influence of local and regional factors.Mini?mum values in the Chinese Strunian,basal Tournaisian and early late Visean can be explained by the small number of studied outcrops,unfavourable facies and depositional gaps in these stratigraphic intervals in South China.This is especially obvious in the late Visean and Serpuk?hovian,which is a peak time of global diversity.The fall observed at that time interval in southern China is easily explained by the fact that this time peried is far less intensively studied and thus fewer data are present in the database.The opposite situation is seen around the TournaisianVisean boundary.Here,a peak is found in both regional and global curves,but that up to 87%of all known species are found in southern China seems to be unlikely,especially when the normal average value are 35%-40%.This anomalously high percentage is a consequence of the work undertaken on the Global Stratotype Section and Point(GSSP),and it shows that a species deficit may exist in the global curve.*Cluster,hierarchical cluster and Nonmetric multidimensienal Scalingel(NMDS)analyses have been calculated to study the palaeobiogeographical affinities of the southern Chinese calcareous foraminifers.The palaeobiogeographical patterns for the complete studied interval or parts of it(substages)are comparable on the genus and species level and stable throughtime.The assemblages found in southern China are well connected to other palaeo(bio)geo?graphical entities supporting the idea of relatively abundant widespread and cosmopolitan taxa in the studied interval.A cluster of South China,Europe and the Russian Platform is found in all analyses.This cluster often attached to the units Far-East Russia and Turkey rep?resents the northern Palaeotethyan Realm.The relatively close affinities between South China and North America cannot be well discussed yet.Chinese data for endemicity,geographical spread and biodiversity in the Tournaisian-Visean boundary interval can be roughly correlated to 3rd-order sea-level fluctuations.Migration patterns into and out of South China can only be suspected,but not yet quantified.
文摘A rich foraminiferal assemblage,consisting of abundant Aulotortus sinuosus and A.tumidus in association with Lamelliconus multispirus,Endoteba ex gr.controversa,E.ex gr.badouxi,Endotebanella kocaeliensis,Endotriada tyrrhenica,Endotriadella wirzi,Malayspirina fontainei,Ammobaculites rhaeticus,Diplotremina astrofimbriata,Agathammina austroalpina,and others,was found in the Doi Long Formation of the Triassic Lampang Group,Northern Thailand.These foraminifers suggest that the formation is referable to the Carnian(early Late Triassic),which is consistent with the age estimated by ammonoids.In microfacies,peloidal grainstone,bioclastic grainstone,sponge-microbial boundstone,and oolitic grainstone were recognized in the Doi Long Formation.Based on microfacies,three depositional facies,the lagoon facies,reef facies,and shoal facies,are recognized in this formation.These lines of evidence are suggestive that the Doi Long Formation was deposited in a reef or bank setting rather than a ramp setting.
文摘A compiled selected literature on some groups of microfossils of the Mesozoic and Cenozoic of the James Ross Basin,eastern Antarctic Peninsula,is presented here,in order to show how the microbiota has been modified over time,triggered by environmental changes.The analyzed microfossils consist of palynomorphs(mostly pollen grains,spores,and dinoflagellate cysts),foraminifers and bryozoans.Dinoflagellate cysts and pollen-spores have been recorded in Jurassic to Pleistocene sedimentary outcrops.Dinoflagellate cysts proved to be good indicators for productivity and/or nutrient availability,surface water temperature and chemistry,the position of ancient shorelines and paleoceanographic trends.Pollen and spores allowed reconstruction of floral community and thus characterization of the climate that prevailed on the continent.Foraminifera,recovered from the Lower Cretaceous to the Pleistocene sedimentary rocks,provided information about the bathymetry,showing different marine settings(e.g.,coastal,inner neritic,outer neritic,upper bathyal)in different localities.The bryozoan record is restricted to the Cenozoic.Their colonial growth-forms reflect several environmental conditions such as shallow waters with a low rate of sedimentation,hard substrate and moderate or strong current action for the analyzed localities.The study of the Antarctic ecosystems based on the fossil microbiota and their response to the climate and the continental configuration changes,allowed understanding of the composition and dynamics of the polar environments,which have an important role in the Earth climate.
文摘Foraminifer is a very useful microorganism to perform biostratigraphical zonation of the Upper Jurassic. Foraminiferal biozones are calibrated by the ammonite standard zones and can be used for intra- and interregional correlations. Furthermore, the fossil record of foraminiferal faunas is well known among basins of the Northern Eurasia and is also used for accurate palaeoenvironmental, palaeobiogeographical, or biofacial reconstructions. It allows identifying a complex set of biotic and abiotic events which may be used to propose a more general palaeoecoloecological and palaeoceanographical reconstruction of the Subboreal, Boreal, and Arctic seas. Then, the late Kimmeridgian Northern Eurasian seas formed a network of well-connected palaeobasins during the sea-level rise and resulted in rather similar palaeoenvironmental conditions.
文摘The Pagoda Formation is a lithologically and biologically distinctive unit among the Upper Ordovician. The strata are characterized by a nodular limestone, which yields fossil assemblages of high diversity. Conodonts of 14 genera 20 species （6 undetermined species） and ostracods of 14 genera 26 species （16 undetermined species） are identified. In addition, spherical radiolarians and minute-walled foraminifers were first reported from this formation in South China. The conodont assemblage is attributed to the Hamarous europaeus Zone, which indicates the Early Katian Age. The conodont HDS biofacies, along with thin-shelled ostracods, spherical radiolarians and foraminifers, suggest relatively deep and quiet water depositional environment. Accordingly, these fossil materials not only enrich the diversity of the Pagoda biota, but also provide evidence for discussions of deposi- tional environments and stratigraphic correlations for the Pagoda Formation.
文摘In the present study, over 3000 m of Upper Cretaceous sediments （Tarbur Formation） in seven stratigraphic, columnar sections were studied. The area is located in the Zagros mountain ranges of southwestern Iran, attributed to the converging continental Arabian Shield, and is interpreted as the result of subduction and collision. Based on foraminiferal studies of the Tarbur Formation in the sections, we have established many new biozones in the stratigraphic sections. However, investigations of the biozones indicate that there is no lithostratigraphic variation between the Upper Cretaceous and Lower Paleocene sediments in some of the studied sections. The concept of widespread formations and lithologic correlations is not applicable in this area, probably as a result of the tectonic unrest at that time. The biostratigraphic boundary between the Cretaceous and the Lower Paleocene is nevertheless well defined by the intraformational boundary in the sections.
基金partly supported by the JSPS KAKENHI(No.JP17740341)。
文摘Cycloclypeus carpenteri is the largest extant benthic foraminifer,dwelling in the deep euphotic zone(a water depth between 60 and 130 m)of the warm oligotrophic Indo-West Pacific.This foraminifer harbors diatom endosymbionts and the foraminifer-microalgal association acts like a holobiont.To verify that light is an important limiting factor controlling the vertical(depth)distribution of living Cycloclypeus holobionts,their physiological responses to light intensity were examined by short-term metabolic measurements and long-term incubations.Net oxygen production(OP)rates measured under different light levels using an oxygen microelectrode indicate that Cycloclypeus holobionts are daily net primary producers adapted to low light levels,with slight photoinhibition(reduced net OP rates relative to a light-saturated rate)over 100μmol photons m^(−2)s^(−1).Long-term growth increments of asexually reproduced juveniles incubated for two months at different light levels ranging from 0 to 100μmol photons m^(−2)s^(−1) show that Cycloclypeus holobionts are adapted to a low light level(∼5μmol photons m^(−2)s^(−1)),but can be acclimatized to a certain low light ranges(<50μmol photons m^(−2)s^(−1)).These experimental results confirm that light is an important environmental gradient affecting the vertical distribution of Cycloclypeus holobionts.
基金This research was jointly supported by the National Natural Science Foundation of China under contract Nos 49736210,40176019 and 40106006,and the Post-doctoral Fund of Ocean University of Qingdao,China.
文摘Benthic foraminiferal analysis of 29 samples in surface sediments from the southern Okinawa Trough is carried out. The results indicate that benthic foraminiferal abundance decreases rapidly with increasing water depth. Percentage frequencies of agglutinated foraminifera further confirm the modern shallow carbonate lysocline in the southern Okinawa Trough. From continental shelf edge to the bottom of Okinawa Trough, benthic foraminiferal fauna in the surface sediments can be divided into 5 assemblages: (1) Continental shelf break assemblage, dominated by Cibicides pseudoungerianus, corresponds to subsurface water mass of the Kuroshio Current; (2) upper continental slope assemblage, dominated by Cassidulina carinata , Globocassidulina subglobosa, corresponds to intermediate water mass of the Kuroshio Current; (3) intermediate continental slope assemblage, dominated by Uvigerina hispi-da, corresponds to the Okinawa Trough deep water mass above the carbonate lysocline; (4) lower continental slope- trough bottom assemblage, dominated by Pullenia bulloides, Epistominella exigua and Cibicidoides hyalinus, corresponds to deep water mass of the Okinawa Trough; and (5) trough bottom agglutinated assemblage, dominated by Rhabdammina spp. , Bathysiphon flavidus, corresponds to strongly dissolved environment of the trough bottom. The benthic foraminiferal fauna in the southern Okinawa Trough are controlled jointly by water masses and food supply. Water temperature, oxygen concentration and carbonate dissolution of the water masses are important controlling factors especially for the continental shelf break and trough bottom assemblages. The food supply also plays an important role in these benthic foraminiferal assemblages along the western slope of the Okinawa Trough. Both the abundance and the 5 assemblages of benthic foraminifera correspond well to the organic matter supply along the continental slope and a lateral transport of TSM (total suspended matter) and POC (particulate organic carbon) from the shelf break to the deep water is also an important food supply for benthic fauna in this region.
文摘The main purpose of this paper is the sequence stratigraphy and biostratigraphy of lower Tertiary sediments on the base of larger benthic foraminifera in northeast of Iran (Chehel-Kaman Formation). This formation mainly consists of Limestone, dolomite and interbeds of sand, shale and evaporate sediments. Petrographical studies indicate that these sediments may have been deposited on a shallow carbonate platform ramp and consist of 4 carbonate lithofacies (15 subfacies). These lithofacies may have been deposited in open marine, shoal, lagoon and tidal flat environmental conditions. Sequence stratigraphy analysis led to identification of 4 third-order depositional sequences, bounded by type 2 (within the top of the underlying Pestehleigh Formation) and type 1 sequence boundaries (paleosol). Interpreted sea level curve in this basin can be relatively correlated with global curves during Paleocene time and a with a sea-level fall occurred in the latest Paleocene, followed by a rise in the earliest Eocene. Biostratigraphy study led to the identification of 32 larger benthic Foraminifera genera. The Paleocene/Eocene boundary has been probably recorded as a thin red paleosol horizon (~10 - 15 cm).
文摘The GSSP for the base of the Santonian Stage is defined at 94.4 m in the eastern border of the“Cantera de Margas”quarry,Olazagutia(Navarra,N.Spain:42º52'05.3"N,2º11'40"W)and marked by the first occurrence(FO)of the inoceramid bivalve Platyceramus undulatoplicatus.This first occurrence is located about 9 m below the contact between a lower marly unit and an upper more calcareous unit.The FO of the planktonic foraminifer Sigalia carpatica is the secondary marker of the GSSP and first occurs 7 m below the primary marker,but it becomes consistently present about 4.2 m above the boundary.In addition,six peaks in the carbon stable isotope curve can be recognized between the Kingsdown Event 17.2 m below and the Bedwell Event 12.35 m above the GSSP.The basal Santonian GSSP was approved by the International Subcommission on Cretaceous Stratigraphy in September 2010,by the International Commision of Stratigraphy in April 2012,and ratified by the International Union of Geological Sciences in January 2013.
文摘The GSSP for the base of the Chattian Stage(Paleogene System,Oligocene Series)is defined at meter level 197 in the Monte Cagnero section,which belongs to the pelagic succession of the Umbria–Marche basin(Urbania,central Italy:43°38′47.81″N–12°28′03.83″E).This level with an astronomical age of 27.82 Ma coincides with the highest common occurrence of the planktonic foraminifer Chiloguembelina cubensis at the base of planktonic foraminiferal O5 Zone and falls in the upper part of calcareous nannofossil NP24 Zone,in the lower part of dinocyst Dbi Zone,and in the lower Chron C9n.The proposal was approved by the International Subcommission of Paleogene Stratigraphy in July 2015,approved by the International Commission of Stratigraphy in August 2016,and ratified by the International Union of Geological Sciences in September 2016.
基金funded by Damghan University (Grant No. 653/19)。
文摘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 coexistence of the N. saipanensis and N. malatyaensis points to suitable palaeobiogeographic conditions of Central Iran to host Western and Eastern Tethyan taxa.
文摘An integrated study of borehole data and outcrop of Mississippian （late Tournaisian to late Visean） rocks in Co. （County） Galway, western Ireland has enabled a more detailed geological map and lithostratigraphy to be constructed for the region. Several carbonate formations have been distinguished by microfacies analysis and their precise ages established by micropalaeontological investigations using foraminifers and calcareous algae. In addition, palaeogeographic maps have been constructed for the late Tournaisian, and early to late Visoan intervals in the region. The oldest marine Mississippian （late Tournaisian） deposits are recorded in the south of the study region from the Loughrea/Tynagh area and further south in the Gort Borehole; they belong to the Limerick Province. They comprise the Lower Limestone Shale Group succeeded by the Ballysteen Group, Waulsortian Limestone and Kilbryan Limestone Formations. These rocks were deposited in increasing water depth associated with a transgression that moved northwards across Co. Galway. In the northwest and north of the region, marginal marine and non-marine Tournaisian rocks are developed, with a shoreline located NW of Galway City （Galway High）. The central region of Co. Galway has a standard Visdan marine succession that can be directly correlated with the Carrick-on- Shannon succession in counties Leitrim and Roscommon to the northeast and east as far as the River Shannon. It is dominated by shallow-water limestones （Oakport, Ballymore and Croghan Limestone Formations） that formed the Galway-Roscommon Shelf. This facies is lat- erally equivalent to the Tubber Formation to the south which developed on the Clare-Galway Shelf. In the southeast, basinal facies of the Lucan Formation accumulated in the Athenry Basin throughout much of the Visean. This basin formed during a phase of extensional tectonics in the early Visean and was probably connected to the Tynagh Basin to the east. In the late Visean, shallow-water limestones of the Burren Formation extend across much of the southern part of the region. They are characterized by the presence of rich concentrations of large brachiopod shells and colonial coral horizons which developed in predominantly high-energy conditions. These limestones also exhibit palaeokarstic surfaces and palaeosols which formed during regressive conditions of glacio-eustatically controlled cyclicity. Locally, slightly deeper water, lower energy conditions developed on the shelf with the formation of rare bryozoan-rich mud-mounds. Deep-water basinal facies were maintained in the central and southeastern parts of the region between the two shelves with the persistence of the Lucan Formation. Ac- tive syn-sedimentary faulting influenced deposition in the Visean and interfingering of basinal sediments with slumps and shallow-water shelf carbonates are recognized.
基金Project supported by a grant from the Chinese National Natural Science Foundation for Young Scientists
文摘An SEM study has been conducted to examine the ultrastructures in the spirotheca of Fusulinella and to reveal the ultra-features of the basic layers consisting of the spirotheca of Fusulinella. The study has demonstrated that the diaphanotheca in the spirotheca of Fusulinella could be considered as a secondary structure.
基金the Grant No.62.9012.2039.00.0 from Polish Geological InstituteNational Research Institute statutory funds to TMP。
文摘Encrusting foraminifers locally can play an essential reef-forming role such as in the Carnian fossiliferous Hallstatt Limestones of Austria where a dense succession of hardgrounds occurs with numerous small buildups(up to 2 cm high)composed of sessile foraminifers.Similar foraminiferal micro-buildups occur in a 10-cm-thick bed in the basinal facies in the basal Zechstein(Upper Permian)strata in the Radlin 60 borehole,in western Poland.Foraminiferal micro-buildups of presumably columnar habit account for up to a half of the volume.The growth of columns was interrupted by hiatal surfaces,although usually the growth of columns was restored afterwards.In the upper part of the bed with foraminiferal micro-buildups,the foraminiferal encrustations become visibly less abundant,and in most cases,they have a shape of less regular masses.The bed with foraminiferal micro-buildups abounds in closely spaced discontinuity(hiatal)surfaces,occasionally encrusted by foraminifers.Tubular foraminifers in the bed with foraminiferal micro-buildups are accompanied by various encrusting organisms,possibly microbes;they are grouped under the name Palaeonubecularia.In the intercolumnar spaces,common Midiella sp.occur.During deposition,the conditions were mostly suboxic,and various types of ferruginous morphs,common in the lower part of the bed,suggest that dysoxic-anoxic interfaces produced various microaerophilic environments for iron-bacteria.The environmental conditions during the deposition of the upper part of the bed were very similar to those characterizing the starved basin environment in which the bioclastic-peloidal and oncoidal sediments in the Zechstein Limestone have been formed.In turn,the lower part of the bed registers the transition from normal(=not starved)marine conditions,with a clear chemocline,to the starved basin conditions.The deposition of the bed was coeval with the Kupferschiefer deposition based on the correlation ofδ13C curves,which implies that the previous stratigraphical concept of basal Zechstein strata has to be re-evaluated.
基金funded by projects CGL2012–30922 and CGL2016–78738-P of the Spanish Government.
文摘A new early Visean coral assemblage has been recorded from turbidite facies in the southern part of the AzrouKhenifra Basin,northwest of Khenifra,central Morocco.The newly discovered Ba Moussa West(BMW)coral fauna includes Siphonophyllia khenifrense sp.nov.,Sychnoelasma urbanowitschi,Cravenia lamellata,Cravenia tela,Cravenia rhytoides,Turnacipora megastoma and Pleurosiphonella crustosa.The early Visean age of the coral assemblage is supported by foraminiferal and conodont data,with the recognition of the basal Visean MFZ9 Zone.This confirms that the first transgression in the Azrou-Khenifra Basin was during the earliest Visean.The allochthonous coral assemblage was recovered from coarse-grained proximal limestone debris flow and turbidite beds within a faultbounded unit,lying to the west of a thrust syncline containing upper Visean limestones.No evidence exists of the former early Visean shallow-water platform from which the corals were derived.All other in situ platform carbonate rocks around the southern margin of the Azrou-Khenifra Basin are probably of late Visean(Asbian–Brigantian)age.The early Visean Ba Moussa West coral fauna can be compared with that at Tafilalt in eastern Morocco,as well as in other Saharian basins of Algeria.Many of the genera and species in the Ba Moussa West assemblage are identical to those in NW Europe,with which it must have had marine connections.The new rugose species described,Siphonophyllia khenifrense,is probably endemic to North Africa.Its ecological niche in NW Europe was occupied by S.cylindrica or S.aff.garwoodi.
