(Figure 2) Foraminifera in lower to middle Albian sediments of DSDP Hole 80-549

The Early Cretaceous series of Site 549 have been analyzed from both an ecological and a chronostratigraphical viewpoint. Lithology and microfaunal assemblages allow the division of these deposits into two parts. The lower part extends from the lower Barremian to the basal upper Barremian and possibly down into the upper Hauterivian. Three foraminiferal associations suggest an orderly evolution from a low-energy, littoral environment, in which continental influences dominated, to progressively more open marine conditions. A dolosparite bed (which has not yet been dated) separates these synrift deposits from lower to basal middle Albian postrift sediments that developed in a pelagic bathyal environment on the middle to nearby lower continental slope.

Cretaceous radiolarians of the southern South Atlantic

Cretaceous radiolarians were recovered from subantarctic Atlantic calcareous submarine deposits from two of the seven sites drilled during ODP Leg 114 in 1987. Fairly well-preserved radiolarian assemblages were found in Hole 698A samples from the Northeast Georgia Rise, whereas assemblages with fair to good preservation were observed from Hole 700B in the East Georgia Basin. The assemblage compositions from both sites are rather low in diversity and are characterized by the dominance of Protoamphipyndax, Dictyomitra, and Stichomitra species, but lack zonal markers recognized from the midlatitude to low-latitude region. Assignment of a Maestrichtian age is based on co-occurring calcareous microfossils. This report constitutes the second such occurrence from the Atlantic sector of the Antarctic Ocean subsequent to the analysis of ODP Leg 113 materials from the Weddell Sea.

Radiolarians of DSDP Site 136-842 and Hole 136-843C

Deep-sea cores recovered at Sites 842 and 843 on Leg 136 of the Ocean Drilling Program have yielded assemblages of Quaternary, Eocene, and Cretaceous radiolarians from the Hawaiian Arch region of the northern equatorial Pacific Ocean. Reddish-brown clays from Hole 842A (0-9.6 mbsf), Hole 842B (0-6.3 mbsf), and Hole 843C (0-4.2 mbsf) contain abundant and diverse assemblages of Quaternary radiolarians consisting of more than 80 species typical of the equatorial Pacific region. Quaternary radiolarians at these sites are assignable to the Quaternary Collosphaera tuberosa Interval Zone and Amphirhopalum ypsilon Interval Zone. The boundary between these zones cannot be determined precisely because of the rarity of zonal markers below surface sediments. Correlations have been made between radiolarian occurrences and magnetostratigraphic events elsewhere in the Pacific Ocean, but similar correlations are difficult at Sites 842 and 843 because of poor subsurface preservation. Chert samples collected from intervals in Cores 842B-10X and 842C-1W have yielded radiolarian ages of lower Cenomanian to Santonian and lower Cenomanian, respectively. Radiolarian assemblages in volcanic sand layers in Sections 6 and 7 of Core 842A-1H (7.5-9.6 mbsf) contain lower and middle Eocene radiolarians admixed with abundant Quaternary faunas. Reworked Eocene radiolarians appear to be restricted to thin layers of volcanic sands within the cores, suggesting deposition by turbidity currents.

Sedimentology and planktonic foraminiferal dissolution during the latest Cretaceous in the South Atlantic

A high-resolution (10-20 kyr) record of variations in CaCO3 content and dissolution was established for latest Cretaceous (last 0.7 Myr) deep-sea sediments from the South Atlantic Ocean (DSDP Site 516 from the Rio Grande Rise, and sites 525 and 527 from the Walvis Ridge). The degree of fragmentation of planktonic foraminifera (DFP) was used as a measure of calcite dissolution. High negative correlations between DFP and other independent measures of carbonate dissolution (percentage of sand fraction, absolute abundance of planktonic foraminifera, and planktonic/benthic foraminiferal ratio) validate its use as a sensitive index of calcite dissolution in upper Maastrichtian deep-sea sediments. Very high DFP and a significant negative correlation between DFP and CaCO 3 content suggest that Site 516 was located below the foraminiferal lysocline during the entire interval studied. Such a shallow position of the lysocline (paleodepth of Site 516 was 1.2 km) may be explained by "upwelling" of corrosive deep waters along the southern margin of the Rio Grande Rise. Sites 525 and 527 were located above the foraminiferal lysocline; however, three short periods of enhanced dissolution were recognised at Site 525 (paleodepth 1 km) and one interval of strong dissolution was identified at Site 527 (paleodepth 2.7 km). The lack of correspondence between the dissolution regimes at sites from the Walvis Ridge suggests limited deep-water communication across this physiographic barrier. Two of the dissolution maxima recognised at Site 525 correspond to carbonate maxima at Site 527. Variations in "upwelling" intensity along the Walvis Ridge, resulting in fluctuations in primary productivity in this area, may be the proximal cause of both carbonate cycles at Site 527 and dissolution cycles at Site 525. We suggest that development of the bottom Ekman layer between a hypothetical westward geostrophic current and the topographical height of the Rio Grande Rise-Walvis Ridge system may be a plausible hydrodynamical explanation for the proposed "'upwelling" along the southern margin of this topographical structure.

Stable isotopic composition and carbonate concentrations of sediments of the Cretaceous/Paleogene boundary in the Antarctic

Stable isotopic records across the Cretaceous/Paleogene (K/P) boundary in Maud Rise Holes 689B and 690C indicate that significant climatic changes occurred during the latest Cretaceous, beginning approximately 500 k.y. prior to the mass extinction event and the enrichment of iridium at the K/P boundary (66.4 Ma). An oxygen isotopic decrease of ~0.7 per mil - ~1.0 per mil is recorded in the Late Cretaceous planktonic and benthic foraminifers between 66.9 and 66.6 Ma. The negative isotope excursion was followed by a positive excursion of similar magnitude between 66.6 Ma (latest Cretaceous) and ~66.3 Ma (earliest Paleocene). No other isotopic excursions of this magnitude are recorded in the planktonic and benthic microfossil records 1.0 m.y prior to, and for 2.0 m.y following the mass extinction event at the K/P boundary. The magnitude and duration of these isotopic excursions were similar to those at the Paleocene/Eocene and Eocene/Oligocene boundaries. A major d13C excursion occurred 200 k.y. prior to the boundary, involving a positive shift in planktonic and benthic d13C of ~0.5 per mil - 0.75 per mil. Similar changes observed in other deep-sea sequences indicate that this reflected a global change in d13C of the oceanic total dissolved carbon (TDC) reservoir. The magnitude of this inferred carbon reservoir change and its association with high latitude surface-water temperature changes recorded in the d18O records implies that it was linked to global climate change through feedback loops in the carbon cycle. At the K/P boundary, the surface-to-deep water d13C gradient is reduced by approximately 0.6 per mil - ~0.2 per mil. However, unlike sequences elsewhere, the planktonic-benthic d13C gradient (Delta d13C) was not eliminated in the Antarctic. The surface-to-deep water gradient was re-established gradually during the 400 k.y. following the mass extinction. Full recovery of the Delta d13C occurred by ~60.0 Ma. In addition to the reduced vertical d13C gradient across the K/P boundary, there was a negative excursion in both planktonic and benthic d13C beginning approximately 100 k.y. after the boundary (66.3 Ma). This excursion resulted in benthic d13C values in the early Paleogene that were similar to those in the pre-K/P boundary intervals. This negative shift appears to reflect a change in the d13C of the oceanic TDC reservoir shift that may have resulted from reduced carbon burial and/or increased carbon flux to the oceans. Any model that attempts to explain the demise of the oceanic plankton at the end of the Cretaceous should consider the oceanic environmental changes that were occurring prior to the massive extinction event.

Early Cretaceous planktonic foraminifera from the Tethys

Early Cretaceous planktonic foraminiferal assemblages include rare planispiral and pseudoplanispiral morphotypes with elongate chambers that BouDagher-Fadel et al. assigned to Schackoina or accommodated in the new genus Claviblowiella. New findings of well-preserved planktonic foraminiferal faunas from the Lesches en Diois (SE France) section, the Cismon core (NE Italy), the Calabianca (NW Sicily) section and the Upper Aptian of Deep Sea Drilling Project (DSDP) Site 545 drilled off Morocco, have allowed a better understanding of the morphological features of these rare, unevenly distributed taxa. Our data demonstrate that each small planispiral species with globular chambers has a corresponding "clavate" morphotype which (as the "normal" forms) exhibits a smooth, finely perforate wall. Consequently, the latter have been assigned here to the genus Globigerinelloides and treated as subspecies of the "non-clavate" taxa. The (clavate) subspecies belonging to the genus Globigerinelloides here retained are G. duboisi sigali Longoria, G. maridalensis elongatus subsp. nov., G. blowi lobatus subsp. nov. and G. paragottisi clavatus subsp. nov., while Globigerinelloides minai Obregòn de la Parra is not retained. In addition, a new genus, Pseudoschackoina, type species Planomalina saundersi Bolli (senior synonym of Hastigerinoides cepedai Obregòn de la Parra, has been formalised for individuals possessing elongate, pointed, laterally compressed chambers, bearing tubulospines arranged on a pseudoplanispiral (dysaxial) coiling mode. Stratigraphically, in the sections studied the first taxon to appear is Pseudoschackoina saundersi, in the uppermost part of the Selli Level (=OAE1a), immediately followed, just above the OAE1a, by all the "clavate" globigerinelloidids. Regarding the last occurrences, Pseudoschackoina saundersi and G. maridalensis elongatus disappear in the lower part of the Globigerinelloides algerianus Zone, Globigerinelloides paragottisi clavatus at the top of the same zone, while Globigerinelloides blowi lobatus and G. duboisi sigali range up to the lower part of the Ticinella bejaouaensis Zone.

Calcareous nannofossils in Pliocene and Quaternary sediments of ODP Leg 117 holes

A total of 21 calcareous nannofossil datums was found in the upper Pliocene and Quaternary sediments recovered from the ocean floor of the North Atlantic during DSDP Leg 94. These datums were correlated to magnetostratigraphy, and ages were estimated by interpolation between magnetic reversals. Calcareous nannofossil assemblages from 549 samples recovered during ODP Leg 117 were studied in order to estimate the age of the sediments of Sites 720, 721, 722, and 731 drilled at the Indus Fan and the Owen Ridge in the Arabian Sea, Indian Ocean. We also showed that the datums above mentioned can be traced into the Indian Ocean. Two new species, namely Helicosphaera omanica and Reticulofenestra ampla, are described.

The Eocene and lower Oligocene coral faunas of the United States with descriptions of a few doubtfully Cretaceous species /

Includes index.

Preliminary delineation and description of the regional aquifers of Tennessee : the Cretaceous aquifer system of west Tennessee /

Shipping list no.: 86-921-P.

Notes on the cretaceous strata of New Jersey and other parts of the United States bordering the Atlantic. Notice of the forminifera.

Mode of access: Internet.

Description of some new species of organic remains of the Cretaceous group of the U.S. with a tabular view of the fossils hitherto discovered in this formation.

Journ. Acad. Nat. Sci. 8. 207-227. 1839-1842.

The Cretaceous flora of southern New York, and New England /

Includes bibliographical references.

Submarine slumps in delta-front sandstones of the Upper Cretaceous Blair Formation, Rock Springs uplift, Wyoming : syndepositional slumps on the western shores of the interior Cretaceous sea /

Mode of access: Internet.

Catalogue of the Mesozoic plants in the British museum (Natural history) The Cretaceous flora.

Half-title: Catalogue of Mesozoic plants in the Department of geology. Pt. v-vi.

Depositional environment of Upper Cretaceous black sandstones of the Western Interior /

Mode of access: Internet.