Grasshoppers and crickets (Insecta : Orthoptera) from the lower cretaceous of southern England

This is a synoptic monograph of fossil Orthoptera from the English Lower Cretaceous (Purbeck and Wealden groups). The previously described taxa of these insects are revised on the basis of type specimens and examination of extensive new material. Eight new genera and 30 new species are proposed: Probaisselcana cretacea sp. nov., Minelcana membranacea gen. et sp. nov., Panorpidium proximum sp. nov., P. bimacillatum sp. nov., ?P. parvum sp. nov. (Elcanidae); ?Cyrtophyllites cretaceus sp. nov. (Haglidae); Aenigmodus minutus gen. et sp. nov., Pseudaboilus wealdensis gen. et sp. nov., P. purbeckensis sp. nov., Tettigoilus sonorus gen. et sp. nov., ?Agrionidium obscurum sp. nov. (Prophalangopsidae); Notocearagryllus britannicus sp. nov., N. grandispeculum sp. nov., N. cordispeculum sp. nov., Anglogryllus lyristes gen. et sp. nov., A. rotundispeculum sp. nov.. Speculogryllus acutispeculum gen. et sp. nov., Sharategia davisi sp. nov., S. batchelorae sp. nov., S. baldocki sp. nov. (Baissogryllidae); ?Araripegryllus orientalis sp. nov. (Gryllidae); Deinovitimia occidentalis sp. nov. (Ensifera: infraorder incertae sedis); Cretoxya rasnitsyni gen. et sp. nov. (Tridactylidae); Locustopsis posterior sp. nov., Zeunerella prior sp. nov., Zessinia borealis sp. nov., Mesolocustopsis anglica sp. nov., M. angusta sp. nov., M. problematica sp. nov., and Britannacrida distincta gen. et sp. nov (Locustopsidae). The subfamily Baisselcaninae is synonymized with Elcaninae, and a new subfamily (Archelcaninae subfam. nov.) is proposed for a segregate of Elcaninae. A preliminary comparison of the Purbeck/Wealden with other Early Cretaceous orthopteran faunas is given. (c) 2006 Published by Elsevier Ltd.

Técnicas de modelagem 3D aplicadas a dados paleobatimétricos das bacias de Santos e Campos e à simulação deformacional de objetos geológicos

Pós-graduação em Geologia Regional - IGCE

Diversity and faunal composition of benthic foraminifera in Hole 44-390A on the Blake Nose Plateau

Benthic foraminiferal assemblages are a widespread tool to understand changes in organic matter flux and bottom-water oxygenation and their relation to paleoceanographic changes in the Upper Cretaceous oceans. In this study, assemblage data (diversity, total number, and number per species and gram) from Deep Sea Drilling Project (DSDP) Site 390 (Blake Nose, western North Atlantic) were processed for the lower Maastrichtian (Globotruncana falsostuarti - Gansserina gansseri Planktic Foraminiferal Zone). These data document significant changes in nutrient flux to the sea floor as well as bottom-water oxygenation during this time interval. Parallel to the observed changes in the benthic foraminiferal assemblages the number of inoceramid shells decreases, reflecting also a significant increase in bottom-water oxygenation. We speculate, that these data could reflect the onset of a shift from warmer low-latitude to cooler high-latitude deep-water sources. This speculation will predate the major reorganization of the oceanic circulation resulting in a circulation mode similar to today at the Early/Late Maastrichtian boundary by ~1 Ma and therefore improves our understanding of Late Cretaceous paleoceanography.

(Appendix) Benthic foraminifera distribution of upper Creatceous and Paleocene at DSDP Hole 72-516F

Benthic foraminifers of the Coniacian-Santonian through the Paleocene were recovered from a continuous pelagic carbonate section from Hole 516F on the Rio Grande Rise. Sixty-five genera and 153 species have been identified, most of which have been reported from other localities. Bathyal depths are reflected in the benthic assemblages dominated by gavelinellids (Gavelinella beccariiformis, G. velascoensis), Nuttallides truempyi, and various gyroidinids and buliminids. Rapid subsidence during the Coniacian-Santonian from nearshore to upper to middle bathyal depths was followed by much reduced subsidence, with the Campanian-Paleocene interval accumulating at middle bathyal to lower bathyal depths. A census study based on detailed sampling reveals major changes in benthic faunal composition at the Cretaceous/Tertiary boundary transition. It was a time of rapid turnover, with the extinctions of numerous species and the introduction of many new species. Overall, species diversity decreases about 20%, and approximately one-third of latest Maestrichtian species do not survive to the end of the Cretaceous. This shift indicates a significant environmental change in the deep sea, the precise nature of which is not apparent from the foraminifers or their enclosing sediments.

Benthic foraminifera in Lower Cretaceous sediments from various DSDP samples

From the DSDP Legs 1, 11, 13, 17, 25, 27, 32, 36, 41, 43, 44, 50, and 62 the Lower Cretaceous foraminifers have been investigated for biostratigraphical, taxonomical, and palaeoecological purposes. An overview of the cored Lower Cretaceous sections of Leg 1-80 is given. In the Northern Atlantic Ocean characteristic foraminiferal faunas are missing from the Upper Tithonian to the Valanginian due to a marked regression which caused hiatuses. In areas without black shale conditions Valanginian to Barremian medium rich to poor microfaunas with Praedorothia ouachensis (Sigal) of the Praedorothia ouachensis Zone (Valanginian-Hauterivian). The Hauterivian-Aptian interval is characterized by zones of Gavelinella barrerniana, Gaudryina dividens, and Conorotalites aptiensis. During the Albian a world-wide fauna consisting of agglutinated and calcareous foraminifers of the Pseudoclavulina gaultina Zone is established in areas lacking the wide-spread black-shale conditions. The Upper Albian and the Cenomanian are represented by the Gavelinella eenomanica Zone. Some ornamented species of the nodosariids (Citharina, Lenticulina), Gavelinella, Conorotatites, Pleurostomella, Vatvulineria, and Osangularia are of some importance for the biostratigraphy of the Berriasian-Albian interval. The Berriasian to Albian zones introduced for the Tethys and the DSDP by Moullade (1984) could only be of some local importance due to the long stratigraphical range of the foraminiferal species used. In the Indian Ocean an exact stratigraphical age cannot be assigned to the few Neocomian foraminiferal faunas of a cooler sea water (Site 261). These faunas mainly contain primitive agglutinated foraminifers, because in most cases the calcareous tests are dissolved or redeposited. In the Pacific Ocean most of the Berriasian to Aptian microfaunas are of minor biostratigraphical and palaeoecological importance for reasons of poor core recoveries, contaminations or original foraminiferal poverty (black shales). Since the Albian there are somewhat higher-diverse faunas of calcareous and agglutinated foraminifers with index species of the Pseudoclavulina gaultina Zone. As a rule, the boundary Albian/Cenomanian is set by means of planktonic foraminifers because no other foraminifer has its first appearance datum during this interval, except Gavelinella cenornanica. During the Albian very uniform, world-wide foraminiferal faunas without a marked provincialism are obvious.

Late Cretaceous benthic foraminiferal assemblages from Demerara Rise, western tropical Atlantic

This paper is based on Santonian-Campanian sediments of Ocean Drilling Program Sites 1257 (2951 mbsl) and 1259 (2353 mbsl) from Demerara Rise (Leg 207, western tropical Atlantic, off Surinam). According to its position, Demerara Rise should have been influenced by the early opening of the Equatorial Atlantic Gateway and the establishment of a bottom-water connection between the central and South Atlantic Oceans during the Late Cretaceous. The investigated benthic foraminiferal faunas demonstrate strong fluctuations in bottom-water oxygenation and organic-matter flux to the sea-floor. The Santonian-earliest Campanian interval is characterised by laminated black shales without benthic foraminifera in the lowermost part, followed by an increasing number of benthic foraminifera. These are indicative of anoxic to dysoxic bottom waters, high organic-matter fluxes and a position within the oxygen minimum zone. At the shallower Site 1259, benthic foraminifera occurred earlier (Santonian) than at the deeper Site 1257 (Early Campanian). This suggests that the shallower site was characterised by fluctuations in the oxygen minimum zone and that a re-oxygenation of the sea-floor started considerably earlier at shallower water-depths. We speculate that this re-oxygenation was related to the ongoing opening of the Equatorial Atlantic Gateway. A condensed glauconitic chalk interval of Early Campanian age (Nannofossil Zone CC18 of Sissingh) overlies the laminated shales at both sites. This interval contains benthic foraminiferal faunas reflecting increasing bottom-water oxygenation and reduced organic-matter flux. This glauconitic chalk is strongly condensed and contains most of the Lower and mid-Campanian. Benthic foraminiferal species indicative of well-oxygenated and more oligotrophic environments characterise the overlying mid- to Upper Campanian nannofossil chalk. During deposition of the nannofossil chalk, a permanent deep-water connection between the central and South Atlantic Oceans is proposed, leading to ventilated and well-oxygenated bottom waters. If this speculation is true, the establishment of a permanent deep-water connection between the central and South Atlantic Oceans terminated Oceanic Anoxic Event 3 "black shale" formation in the central and South Atlantic marginal basins during the Early Campanian (Nannofossil Zone CC18) and led to well-oxygenated bottom waters in the entire Atlantic Ocean during the Late Campanian (at least from Nannofossil Zone CC22 onwards).

Campanian-Maestrichtian benthic foraminifera of DSDP Hole 78-543A

Foraminiferal assemblages in sediments from Hole 543A suggest that toward the end of the Cretaceous there was an oscillating carbonate compensation depth (CCD) in the western Central Atlantic. Changing assemblages of siliceous agglutinated and calcareous foraminifers reflect the changing depositional environment, from a ridge crest environment during Campanian time to a deep abyssal environment during Maestrichtian time.

Uppermost Jurassic to lower Cretaceous benthic foraminifera from ODP Hole 123-765C

Benthic foraminifers were studied in 99 samples collected from the lower 200 m of Hole 765C. The studied section ranges from the Tithonian to Aptian, and benthic foraminifers can be subdivided into five assemblages on the basis of faunal diversity and stratigraphic ranges of distinctive species. Compared with deep-water assemblages from Atlantic DSDP sites and Poland, assemblages from the Argo Abyssal Plain display a higher diversity of agglutinated forms, which comprise the autochthonous assemblages. Assemblages at the base of Hole 765C are wholly composed of agglutinated forms, reflecting deposition beneath the carbonate compensation depth (CCD). Most calcareous benthic species are found in turbidite layers, and the presence of an upper Valanginian Praedorothia praehauteriviana Assemblage may indicate deposition at or just below the CCD. The P. praehauteriviana Assemblage from Hole 765C is the temporal equivalent of similar assemblages from DSDP Holes 534A, 416A, 370, 105, and 101 in the Atlantic Ocean and Hole 306 in the Pacific Ocean. Stratigraphic ranges of cosmopolitan agglutinated species at Site 765 generally overlap with their reported ranges in the Atlantic and in the bathyal flysch sequences of the Carpathians; however, several species from Hole 765C have not been previously reported from Uppermost Jurassic to Lower Cretaceous abyssal sediments.

(Table 5) Distribution of benthic foraminifers in the late Cretaceous of DSDP Hole 71-511

The book is devoted to stratigraphy of Cretaceous deposits from high latitudes of the southern hemisphere (subantarctic part of the ocean), as well as to geological and climatic Cretaceous history of the area. Correlation with Cretaceous sediments from warm water regions is carried out. Description and photos of characteristic species of planktonic and benthic foraminifera and calcispherulides are given.

Live benthic foraminifera in surface sediments of the Indo-Pakistan continental margin

The Indo-Pakistan Continental Margin represents an extreme habitat for benthic foraminifera since (1) high fluxes of organic matter offer a high food supply, (2) an intensified oxygen minimum Zone (OMZ) develops from the base of the euphotic Zone to water depths over 1000 m and (3) the monsoon causes seasonal oscillations within the biogeochemical cycle. At three stations from the uppermost (233 m), the central (658 m) and the deeper part (902 m) of the OMZ, living benthic foraminiferal assemblages were analyzed within the uppermost 10 cm of the sediment column. The ecologic structure of foraminiferal faunas is characterized by high abundances at the sediment surface and a rapid decrease within the uppermost 2 cm of the sediment column. Despite dysoxic to suboxic bottom-water conditions, stained benthic foraminifera occurred in all cores down to the base of the sampled interval. High surface abundances, a high dominance by few endobenthic calcareous taxa and a low diversity, which may result from specific physiological adaptations to almost anoxic conditions and the absence of predators, are recognized in the central part of the OMZ. The upper and lower margins of the OMZ are characterized by higher diversities and lower abundances. The shallowest part of the OMZ is dominated by calcareous foraminifera, whereas agglutinated species are the most common taxa in the deeper part. Comparisons with previous studies show that benthic foraminiferal assemblages, that are influenced by seasonal oscillations controlling food supply and/or the availability of oxygen, show variations in faunal density and species composition. Since there is strong evidence that oxygen is not a limiting factor for some taxa, it seems more likely that the distribution pattern of benthic foraminifera is preferentially controlled by trophic conditions.