SVRCHNOKŘÍDOVÁ FAUNA (FORAMINIFERA, BIVALVIA) PODSLEZSKÉ JEDNOTKY Z POTOKA KOPYTNÁ V BYSTŘICI NAD OLŠÍ

An Eocene-Oligocene oxygen and carbon isotope history based on planktonic and benthic foraminifers from Deep Sea End_Page 523------------------------------ Drilling Project Leg 71 cores has been constructed for the Maurice Ewing Bank of the eastern Falkland Plateau, southwestern Atlantic Ocean. Specifically, the cores cover portions of the middle Eocene, upper Eocene, and lower Oligocene. Surface water isotopic temperatures postulated for the middle Eocene at Site 512 fluctuated within about four degrees but generally averaged about 9°C (48°F). Bottom isotopic temperatures at Site 512 (water depth = 1,846 m, 6,056 ft) were generally a degree lower than surface water temperatures. Surface water isotopic temperatures at Site 511 initially averaged about 11°C (52°F) during the late Eocene, but dropped to an average of 7°C (44.5°F) in the early Oligocene. Bottom isotopic temperatures at Site 511 (water depth = 2,589 m, 8,494 ft) generally record temperatures between 12.5°C (54.5°F) and 8°C (46.5°F), similar to the range in the surface water temperatures. During the early Oligocene, bottom isotopic temperatures dropped sharply and averaged about 2°C (35.5°F), very close to present-day values. Surface water isotopic temperature values also decreased to an average of about 7°C (44.5°F), leading to a significant divergence between surface and bottom water isotopic temperatures during the early Oligocene. Comp risons among Southern Ocean DSDP Sites 511, 512, and 277, and between these and other DSDP sites from central and northern latitudes (Sites 44, 167, 171, 292, 357, 398, 119, and 401) show that much of the Eocene was characterized by relatively warm temperatures until sometime in either the middle Eocene, late Eocene, or early Oligocene. At each site, conspicuous 18O enrichments occur in both the benthic and planktonic foraminifers over a relatively short period of time. Although a general trend toward a climatic deterioration is evident, the density of data points among the various studies is still too sparse to determine either a synchroneity or a time transgression between the major isotopic events. A close correlation could be made between the Site 511 oxygen isotope temperature curve and paleoclimatic trends derived independently from radiolarian studies. The sharp temperature drop and the divergence between bottom and surface water temperatures during the early Oligocene apparently reflect a major expansion of the Antarctic water mass. The migration of the boundary between the sub-Antarctic and Antarctic water masses over the site at this time would account in part for the sharp temperature changes. Sharp changes of this nature would not necessarily be noted in other geographic areas, particularly those to the north which have different oceanographic regimes. End_of_Article - Last_Page 524------------

Some modifications for Biostratigraphic Scheme of Paleocene deposits of the Northern Ukraine as result of examination of foraminifera assemblages of the Dnieper-Donets Depression and Ukrainian Shield are proposed. In the Northern Ukraine section sediments of Psolian regional stage (regiostage) contain the most representative assemblages of planktonic and benthic foraminifera. Two planktonic foraminifers’ zones Subbotina trivialis – Globoconusa daubjergensis – Globanomalina compressa and Praemurica inconstans established earlier by M.V. Jartseva (1972) characterize the Psolian regiostage. Subbotina trivialis – Globoconusa daubjergensis – Globanomalina compressa zone corresponding to Eoglobigerina taurica and Globoconusa daubjergensis zones of the Belokamenskian regiostage of the Southern Ukraine is correlated with Danian zone P1 Eoglobigerina edita of tropical planktonic foraminiferal biochronological zonation. Praemurica inconstans zone of the Northern Ukraine corresponds to south Ukraine zone of the same name and is correlated with zone P2 Praemurica uncinata of Danian too. Benthic foraminifers’ assemblages from Psolian deposits have been distinguished as Cibicides lectus zone corresponding to Anomalina danica s. l. and Pyramidina crassa interregional zones of Danian and Zelandian of the south Russia and adjacent regions. Reviewed in the article biostratigraphical characteristics of local stratigraphic units of Psolian regiostage: the Sumy Suite of the Dnieper-Donets Depression (zones Subbotina trivialis – Globoconusa daubjergensis – Globanomalina compressa, beds with Cibicidoides lectus, beds with Cibicidoides favorabilis of the central part of the Depression; Anomalina danica zone, Ceratolamarckina tuberculata local zone, beds with Parasubbotina pseudobulloides and beds with Globoconusa kozlowskii of the north-eastern part of the Depression), Strata of quartz-glauconitic sands of the Konka-Yalyn Depression (beds with Parasubbotina pseudobulloides, beds with Cibicidoides lectus), the Luzanovka Beds (beds with Parasubbotina pseudobulloides, beds with Globoconusa daubjergensis, beds with Elphidiella prima) and the Polesje Beds (beds with Parasubbotina pseudobulloides, beds with Cibicidoides lectus), the Rajgorod Suite (assemblage with Anomalina danica) of the Ukrainian Shield. Correlation of these Suites, Beds and Strata are given. The Merlian regiostage of the Northern Ukraine contains not numerous foraminifers. Benthic foraminifers’ associations from the Merlian and Irzhavets Suites of the Dnieper-Donets Depression have been distinguished as assemblage with Bolivinopsis spectabilis. Sediment containing this assemblage is of Thanetian age by dinocysts. Findings of sporadic planktonic foraminifers in the Merlian deposits do not contradict this.

Two wells drilled along the margin of Enewetak Atoll penetrated approximately 1000 m of upper Eocene, Oligocene, and lower Miocene carbonates. Strontium isotope stratigraphy indicates relatively continuous deposition of carbonate from 40 Ma to 20 Ma. Depositional environments show a gradual basinward progradation of facies with slope carbonates passing upward into fore-reef, reef, back-reef, and lagoonal carbonates. Slope strata contain wackestones and packstones with submarine-cemented lithoclasts, coral, coralline algae fragments, benthic rotaline forams, planktonic forams, and echinoderm fragments. Fore-reef strata are dominantly packstones and boundstones containing large pieces of coral, abundant benthic forams, coralline algae fragments, stromatoporoids( ), and minor planktonic forams. Reef and near-reef sediments include coralgal boundstones and grainstones with abundant benthic forams. Halimeda and miliolid forams are common in lagoonward parts of the back reef. Sponge borings, geopetal structures, and fractures are common in reef and fore-reef strata. Lagoonal strata are wackestones and packstones with common mollusks, coral, coralline algae, and benthic forams (rotaline and miliolid). Diagenesis has extensively altered strata near the atoll margin. Aragonite dissolution and calcite cements (radiaxial and cloudy prismatic) are abundant in fore-reef, reef, and some back-reef strata. Petrographic and geochemical data indicate aragonite dissolution and calcite cementation in seawater at burialmore » depths of 100 to 300 m. Dolomite occurs in slope and deeply buried reefal carbonates. Most dolomitization occurred at burial depths of more than 1000 m in cool marine waters circulating through the atoll. lagoonal strata are not significantly altered by marine diagenesis and still contain abundant primary aragonite and magnesium calcite.« less

Integrated stratigraphy of the Campanian–Maastrichtian boundary succession of the Middle Vistula River section, central Poland; Part II

Lower Miocene through upper Pleistocene benthic foraminifer assemblage records from Ocean Drilling Program Site 751 on the Southern Kerguelen Plateau (57°44'S, water depth 1634 m) were combined with benthic and planktonic foraminifer oxygen and carbon isotope records and high-resolution CaCO3 data from the same site. Implications for the Neogene productivity and paleoceanography of the southern Indian Ocean are discussed. We used distinctive features of the Miocene δ 18 θ and δ13C curves for stratigraphic correlation. Coinciding with a lower middle Miocene hiatus from 14.2 to 13.4 Ma, there was a rapid increase in benthic δ18θ values by 1.2%c. This distinct increase occurs in middle Miocene benthic foraminifer oxygen isotope curves from all oceans. No major change, however, in benthic foraminifer faunal composition occurred in this period of growth of the Antarctic ice cap and cooling of deep ocean waters (14.9-14.2 Ma). A drastic change in benthic foraminifer faunas coincided with a hiatus from 8.4 to 5.9 Ma. Shortly after this hiatus, in the latest Miocene, the CaCO3 content of the sediments dropped from 75% to 0%. From that time ( 5.8 Ma) through the early Pliocene, Site 751 has been situated beneath a high biogenic siliceous productivity zone. Carbonate contents of upper Pliocene and Pleistocene sediments vary between 20% and 70%. The benthic foraminifer faunas in the uppermost Pliocene and lower Pleistocene reflect strong bottom current conditions, in contrast to those in the upper Pleistocene, which indicate calm sedimentation and high food supply. High δ13C values of planktonic foraminifers compared with low values of benthic foraminifers suggest high primary productivity in the late Pleistocene. The changes in productivity were probably a result of latitudinal migration and meandering of the Polar Frontal Zone.

The integral investigation of the upper Campanian‒Maastrichtian section near the settlement of Nizhnyaya Bannovka (Krasnoarmeiskii district, Saratov oblast) included its detailed lithological description and the study of different organic remains (belemnites, benthic and planktonic foraminifers, radiolarian, calcareous nannofossils, dinocysts) with the analysis of their taxonomic composition and stratigraphic distribution and magnetostratigraphic (magnetic polarity and petromagnetic) properties. The belemnite findings indicate the presence of the upper Campanian Belemnitella langei Zone in the section, which comprises sediments previously attributed to the lower Maastrichtian Belemnitella lanceolata Zone. The analogs of magnetic polarity chrons 33n, 32r, and 31n (probably superposed chrons 31n and 30) are established. It is assumed that radiolarians offer the opportunity to define the middle Campanian substage by analogy with the standard (international) stratigraphic scale. On the basis of benthic foraminifers, calcareous dinocysts, and paleomagnetic data, the late Maastrichtian age of sediments previously dated back to the early Maastrichtian is substantiated. A large hiatus corresponding to the terminal Campanian‒early Maastrichtian is revealed in the section. The succession of sedimentological, biotic, and paleogeographic events is outlined for the late Campanian‒Maastrichtian interval. The obtained data make it possible to disclose paleobiogeographic connections between microfaunal communities of the Campanian and late Maastrichtian seas on the East European and West Siberian plates. It is established that the uppermost Maastrichtian sediments are enriched in extraterrestrial matter.

Samples were washed with sodium metaphosphate (5.5 g/L) in tap water through a 63-μm sieve and air dried. Benthic foraminifers were picked from aliquots of the >150-μm size fraction and mounted on reference slides. We avoid the 63to 150-μm size fraction preferred by some authors (e.g., Schroder et al., 1987) because of problems in identifying small taxa. While we lose information obtainable from the 63to 150-μm size fraction, we gain information on larger taxa (i.e., in an aliquot picked from the >63-μm size fraction, many larger taxa are underemphasized, while small, difficult to identify taxa are emphasized). In general, ~300 specimens were picked per sample. However, samples with as few as 130 specimens were used in the faunal analyses. Thirty-seven samples were examined for this study (Table 1). Our identifications of most of the benthic foraminifers follow the taxonomy of van Morkhoven et al. (1986); additional taxonomic references include Katz and Miller (1993a, 1993b), and references included therein. Not all species present were identified; for example, species of some common (Lenticulina, Oridorsalis, and Gyroidinoides) and some rare (Lagena, Fissurina, and Oolina) genera were not differentiated. We performed Q-mode principal components and varimax factor analyses on the relative abundance (percentage) data using modifications of programs provided by Lohmann (1980). The Q-mode principal components and varimax factor programs utilize a cosine-theta matrix, standardizing each sample to unit length. Each factor represents a unique benthic foraminiferal biofacies. We used factor analysis to help identify trends in the benthic foraminiferal biofacies at Site 1006, using two analyses: (1) the first was run using the entire benthic foraminiferal data set (Fig. 1); and (2) the second analysis was run with the transported, shallow-water taxa deleted and only the in situ faunal components were used (Fig. 2). Dissolution indices (Table 1) were based on counts of planktonic foraminifer fragments, whole planktonic foraminifer tests, and benthic foraminifer tests. Percentages of planktonic foraminifer fragments were calculated relative to fragments plus whole planktonic foraminifer tests. Percentages of planktonic foraminifers were calculated relative to whole planktonic plus benthic foraminifer tests.

The sediment composition and predictive mapping of facies on the Propeller Mound—A cold-water coral mound (Porcupine Seabight, NE Atlantic)

Lithostratigraphic analysis of the Turonian–Coniacian Bireno and Douleb carbonate Members in Jebels Berda and Chemsi, Gafsa basin, central-southern Atlas of Tunisia

Foraminifera indicate Neogene evolution of Yongle Atoll from Xisha Islands in the South China Sea

A series of papers is intended to be published in which the results from the analysis of the taxonomic composition and stratigraphic significance of the small foraminiferal assemblages in the Eocene sediments from the Burgas district will be presented. The collection studied includes microfossils from the Mugris Formation and the Ravnec Formation from 19 borehole sections on the territory of Černo More Coal Basin (North of Burgas). Most of the small benthic calcareous foraminifers (50 taxa) - from family Spiroloculiniclae Wiesner to family Cibicididae Cushman are described and illustrated in this study.

Similarity and provenance of underpainting chalk grounds based on their nannofossil assemblages cluster analysis

Rhodolith-forming non-geniculate coralline red algae have been recorded from the Long Formation, exposed in four different outcrops at Little Andaman Island (Hut Bay) in the northeastern Indian Ocean. The non-geniculate corallines are represented by species of Sporolithon Heydrich, 1897, Mesophyllum Lemoine, 1928, Lithothamnion Heydrich, 1897, Phymatolithon Foslie, 1898, Lithoporella (Foslie) Foslie, 1909, Spongites Kützing, 1841, Neogoniolithon Setchell & Mason, 1943 and Lithophyllum Philippi, 1837. The algal assemblages also include geniculate corallines belonging to the genera Amphiroa Lamouroux, 1812 and Corallina Linnaeus, 1758. In addition, larger benthic foraminifers and few planktonic foraminifers also have been identified in thin section analysis. Based on the earlier study carried out on planktonic foraminifers, the Long Formation has been dated as Serravallian (late middle Miocene) and chronostratigraphically, the Long Formation has been included in the Ongeian Regional Stage. In the rhodolith-forming non-geniculate corallines, various growth forms and taphonomic features have been recognized. Diagenesis affected the studied material by micritization, cementation and compaction. The four outcrops are dominated by bioclastic wackestone and packstone composed of coralline red algae, benthic and planktonic foraminifers, echinoid spines and unidentified coral fragments. The rhodolith-forming coralline red algae, the growth forms and taphonomic features in non-geniculate corallines and the characteristic benthic foraminifers are indicative of a moderate energy depositional environment. This study indicates that the carbonate production was considerably high during the Serravallian of the tropical northeastern Indian Ocean.

Alongside the central and southern Ionian Calabria, a Pliocene (Zanclean – Piacenzian) sedimentary succession crops out more or less continuously. This succession, assimilated to the Sicilian Trubi Formation, is constituted by a rhythmic alternation of marls and limestones, these last very rich in planktonic and benthic foraminifers and in coccoliths.Near the village of Palizzi Marina (RC) one of the fairly well known Calabrian outcrops of this formation occurs. This paper describes the fi rst observations on the trace fossils recognized in the middle part of this sedimentary succession.The ichnoassemblage belongs to the Zoophycos ichnofacies, confirming previous studies which proposed an open marine slope-basin depositional paleoenvironment, at a depth of 800-1000 m, inferred on the basis of planktonic and benthic foraminifers.

Late Maestrichtian to late Eocene bathyal benthic foraminiferal faunas at Sites 752,753, and 754 on Broken Ridge in the eastern Indian Ocean were analyzed as to their stratigraphic distribution of species to clarify the relation between faunal turnovers and paleoceanographic changes.Based on Q-mode factor analysis, eight varimax assemblages were distinguished: the Stensioina beccariiformis assemblage in the upper Maestrichtian to upper Paleocene; the Cibicidoides hyphalus assemblage in the upper Maestrichtian; the Cibicidoides cf. pseudoperlucidus assemblage in the upper Paleocene; the Anomalinoides capitatusldanicus assemblage in the uppermost Paleocene to lower Eocene; the Cibicidoides subspiratus assemblage in the lower Eocene; the Nuttallides truempyi assemblage in the lower and middle Eocene; the Osangularia sp. 1 - Hanzawaia ammophila assemblage in the upper Eocene; and the Lenticulina spp. assemblage in the uppermost Eocene, Oligocene, and lower Miocene. The presence of the Osangularia sp. 1 - Hanzawaia ammophila assemblage is related to the shallowing episode on Broken Ridge (upper bathyal), as a result of the rifting event that occurred in the middle Eocene.The most distinct faunal change (the disappearance of about 37% of the species) occurred between the S. beccariiformis assemblage and the A. capitatusldanicus assemblage, at the end of the upper Paleocene. A. capitatusldanicus, Lenticulina spp., and varied forms of Cibicidoides replaced the Velasco-type fauna at this time. The timing of this event is well correlated with the known age at South Atlantic sites (Thomas, 1990 doi:10.2973/odp.proc.sr.113.123.1990; Kennett and Stott, 1990 doi:10.2973/odp.proc.sr.113.188.1990; Katz and Miller, 1990 doi:10.2973/odp.proc.sr.114.147.1991). The primary cause of the extinction of the Stensioina beccariiformis assemblage is elusive, but may have resulted from the cessation of deep-water formation in the Antarctic (Katz and Miller, 1990), and subsequent arrival of warm saline deep water (Thomas, 1990; Kennett and Stott, 1990). Another possibility may be a weakened influence of high-salinity water formed at the low latitudes such as the Tethys Sea. The extinction event corresponds to the change from higher delta13C values in benthic foraminifers to lower ones. An interpretation of delta13C values is that the eastern Indian deep water, characterized by young and nutrient-depleted water, became old water which was devoid of a supply of new water during the latest Paleocene to early Eocene. Prior to this benthic event, signals of related faunal change were detected in the following short periods: early and late Paleocene, near the boundary of nannofossil Zone CP4, and Zone CP5 of the late Paleocene at Site 752.Among common taxa in the upper Maestrichtian, only seven species disappeared or became extinct at the Cretaceous/ Tertiary boundary at Site 752. The benthic foraminiferal population did not change for up to 2 m above the boundary, in contrast to the rapid decrease of the plankt onic foraminiferal population at the boundary. A decrease in the number of benthic foraminifers occurs after that level, corresponding to an interval of decreased numbers of planktonic foraminifers and higher abundance of volcanic ash. Reduced species diversity (H') suggests a secondary effect attributable to the dissolution of foraminiferal tests. The different responses of planktonic and benthic foraminifers to the event just above the boundary suggest that the Cretaceous/Tertiary event was a surface event as also suggested by Thomas (1990). In addition, a positive shift of delta13C in benthic foraminifers after the event indicates nutrient-depleted bottom water at Site 752.