A new genus of Trichomyiinae (Diptera: Psychodidae) from Upper Cretaceous amber of New Jersey

Xenotrichomyia newjerseyiensis a new genus and species belonging to Trichomyiinae within Psychodidae is characterized, described, illustrated and its taxonomic position is discussed. It shares some similarities with Trichomyiinae of group B, but retains some archaic features, such as normal and non-excentric flagellomeres, and possesses an autapomorphy in wing venation that distinguish it from all remaining Trichomyiinae. This discovery represents the first Trichomyiinae (Psychodidae) from the Upper Cretaceous New Jersey amber, and adds more evidence on the very high palaeodiversity of the psychodids since at least the Lower Cretaceous. An updated check list of fossil Trichomyiinae is given.     

The Cenomanian/Turonian oceanic anoxic event in the Razzak Field, north Western Desert, Egypt: Source rock potential and paleoenvironmental association

The Western Desert of Egypt is one of the world’s most prolific Jurassic and Cretaceous hydrocarbon provinces. It is one of many basins that experienced organic-rich sedimentation during the late Cenomanian/early Turonian referred to as oceanic anoxic event 2 (OAE2). The Razzak #7 oil well in the Razzak Field in the northern part of the Western Desert encountered the Upper Cretaceous Abu Roash Formation. This study analyzed 23 samples from the upper “G”, “F”, and lower “E” members of the Abu Roash Formation for palynomorphs, particulate organic matter, total organic carbon (TOC) and δ¹³C_org in order to identify the OAE2, determine hydrocarbon source rock potential, and interpret the depositional environment. The studied samples are generally poor in palynomorphs, but show a marked biofacies change between the lower “E” member and the rest of the studied samples. Palynofacies analysis (kerogen quality and quantity) indicates the presence of oil- and gas-prone materials (kerogen types I and II/III, respectively), and implies reducing marine paleoenvironmental conditions. Detailed carbon stable isotopic and organic carbon analyses indicate that fluctuations in the δ¹³C_org profile across the Abu Roash upper “G”, “F”, and lower “E” members correspond well with changes in TOC values. A positive δ¹³C_org excursion (∼2.01‰) believed to mark the short-term global OAE2 was identified within the organic-rich shaly limestone in the basal part of the Abu Roash “F” member. This excursion also coincides with the peak TOC measurement (24.61 wt.%) in the samples.     

Sea level changes in the upper Aptian-lower/middle(?) Turonian sequence of Cauvery Basin,India – An ichnological perspective

Cauvery Basin, a pericratonic rift basin along the Eastern Continental Margin of India, evolved during the breakup of the Eastern Gondwanaland. It exposes both syn-rift and later post-rift passive margin deposits ranging from Barremian to Miocene. The Karai Formation, upper Aptian-lower/middle (?) Turonian represents the oldest passive margin in the Cauvery Basin. It is bounded at both contacts by major sequence boundaries viz. the break-up unconformity and the Turonian tilt event. The present communication deals with the ichnology of the Karai Formation and its integration with sedimentary facies and biostratigraphy to interpret the sea level changes during deposition. A traverse between the villages Karai and Kulakkalnattam was studied in detail for this purpose. Based on the lithological position, characters and internal grain size trends, the Karai Formation is sub-divided into four informal lithologic units; the lower three units, constitute a lithostratigraphic unit known in literature as the Gypsiferous Clay Member, while the uppermost, corresponds to the Sandy Clay Member. At the base, clays of the Karai Formation unconformably onlap onto the Precambrian basement or the fluvial syn-rift deposits across the break-up unconformity. Upper Aptian to middle Cenomanian, units I and II showing the distal Cruziana ichnofacies, deepening of the basin and a retrogradational stacking pattern represent a transgressive system tract (TST). This long phase of transgression is attributed to continuous accommodation created by the post-breakup thermal subsidence. The upper part of unit II (middle Cenomanian) shows condensation, with its top representing the maximum flooding surface (MFS). Upper Cenomanian to lower/middle (?) Turonian, units III and IV characterised by a shift from the distal Cruziana to the Skolithos ichnofacies, an initial aggradational and later deltaic, progradational stacking pattern resulting from a fall in the relative sea level and filling up of accommodation space represent the highstand system tract (HST). A further fall in the relative sea level led to the exposure, incision and erosion of the Karai Formation over which the younger transgressive sequence of the Trichinopoly Group was deposited with an angular unconformity.     

Palynofacies evidence of dysoxia and upwelling in the Turonian of the Sergipe Basin,Brazil

This paper presents the integrated results of palynofacies and geochemical analyses in Turonian carbonate strata from the Sergipe Basin, Brazil. Forty-three outcrop samples were analyzed from sections of the Cotinguiba Formation in the Votorantim and Rita Cacete quarries. Our results allow for the characterization of the organic matter and interpretation of the environments of deposition. Together with the existing geochemical data, the results allow for recognition of oxic and dysoxic intervals and inferences pertaining to local oceanographic conditions to explain these environmental changes. The palynofacies groups are dominated by marine palynomorphs and amorphous organic matter (AOM), with minor amounts of terrigenous palynomorphs and phytoclasts. The total organic carbon (TOC) and δ¹³C ratio are directly correlated with the dominant palynofacies elements, particularly AOM. The upper section in Rita Cacete quarry has the most complete data set, and the TOC, δ¹³C and marine-derived AOM in this section tend to decrease upsection and serve to differentiate the oxic and dysoxic intervals. The sections also contain abundant, low-diversity dinoflagellate assemblages composed primarily of Trichodinium boltenhagenii, Cribroperidinium? muderongense, Canningia reticulata and Xenascus plotei. The palynofacies and dinoflagellate assemblages indicate deposition in shallow marine to outer neritic environments. The dysoxic events are recognized by an increase in TOC and δ¹³C, high amounts of AOM, an abundance of the low-diversity dinoflagellate assemblages and the lowest amounts of terrestrial components. The changes in marine productivity seem to be related to periods of low-intensity upwelling, which likely decreased the levels of dissolved oxygen in the basin.     

Vulnerability mapping of the Turonian limestone aquifer in the Phosphates Plateau (Morocco)

Turonian limestones are an important source of water indispensable for industrial, urban and agricultural development in the Phosphates Plateau. This is an elaboration of a vulnerability map of the aquifer, based on a multicriterion approach according to the DRASTIC charter that serves as a tool for assessment, management and protection of the groundwater quality.     

Stable isotope analysis of the Cenomanian–Turonian (Late Cretaceous) oceanic anoxic event in the Crimea

Carbon and oxygen isotope data from Cenomanian–Turonian sediments from the southwest of the Crimea are presented. The sediments consist of limestones, marls and organic-rich claystones, the latter with total organic carbon values up to 2.6 wt. %, representing Oceanic Anoxic Event 2. A shift to more negative δ¹⁸O values through the uppermost Cenomanian into the lowermost Turonian may be the result of warming; however, petrographic analysis shows that the samples have undergone a degree of diagenetic alteration. The carbon isotope data reveal a positive excursion from 2.7‰ to a peak of 4.3‰ at the Cenomanian/Turonian boundary; values then decrease in the early Turonian. This excursion is comparable to those of other Cenomanian–Turonian sections, such as those seen in the Anglo-Paris Basin, and is thought to be due to global changes in the oceanic carbon reservoir. On this curve are a number of negative δ¹³C excursions, just below the Cenomanian/Turonian boundary. It is suggested that these negative excursions are associated with the uptake of light carbon derived from the oxidation and deterioration of organic material during localised exposure of the sediments to oxic or meteoric diagenetic conditions, possibly during sea-level fluctuations.     

Cenomanian–Turonian carbonate platform deposits in west central Jordan

We studied upper Albian to Turonian shallow-marine shelf deposits (Ajlun Group) of west central Jordan along a NNE-SSW running transect. The carbonate-dominated succession includes few siliciclastic intercalations, claystones and shales, and can be subdivided into five formations. The Naur, Fuheis and Hummar Formations of upper Albian to upper Cenomanian age represent shallow subtidal to supratidal platform environments. The uppermost Cenomanian to middle Turonian Shueib Formation includes deeper water deposits of the inner/mid-shelf and locally TOC-rich black shales. Shallow-marine platform environments once again dominate the Wadi As Sir Formation (middle-upper Turonian). A new multibiostratigraphic framework is based on ammonites (mainly of the middle Cenomanian rhotomagense Zone to the middle Turonian woollgari Zone) and calcareous nannofossils (biozones CC 9–CC 11), supplemented by benthic and planktonic foraminifers and ostracods. It forms the base of a sequence stratigraphic subdivision, containing eight sedimentary sequences (S1–S8), which are separated by four Cenomanian sequence boundaries (CeJo1–CeJo4) and three Turonian sequence boundaries (TuJo1–TuJo3). This scheme allows the correlation of the platform succession from distal to proximal shelf areas in contrast to previous correlations using lithologic units. Furthermore, comparisons between the platform successions and sequence patterns of west central Jordan and those from neighbouring areas allow to differentiate local, regional, and global controlling factors of platform development within the study area.     

Upper Cretaceous deposits in the northwest of Saratov region, Part 2: Problems of chronostratigraphy and regional geological history

Problems of geochronological correlation are considered for the formations established in the study region with due account for data on the Mezino-Lapshinovka, Lokh and Teplovka sections studied earlier on the northwest of the Saratov region. New paleontological data are used to define more precisely stratigraphic ranges of some stratigraphic subdivisions, to consider correlation between standard and local zones established for different groups of fossils, and to suggest how the Upper Cretaceous regional scale of the East European platform can be improved. Considered in addition are paleogeographic environments in the study region during the Late Cretaceous epoch and principal stages of the regional geological evolution.     

Cretaceous foraminifera from the Turonian succession at Beer, southeastern Devon, England

During Winter 2000/2001 a major cliff fall occurred at the back of the bay in Beer, southeastern Devon. In the subsequent remedial works the cliff was cleared of loose material prior to stabilisation works. This process provided a suite of samples from previously inaccessible parts of the cliff succession. By adding these samples to earlier suites of samples collected over the last 30 years it has been possible to improve our knowledge of the foraminifera of Turonian age in southwestern England.The planktic foraminifera are, perhaps, the most significant component of the assemblages as many of the taxa recorded in Devon are of southern aspect and are relatively rare in others parts of the U.K. The planktic zonation recognised in this section is, therefore, almost identical with that recorded in Tethyan areas and a precise correlation can be generated. There are relatively large numbers of important taxa such as Helvetoglobotruncana helvetica, Dicarinella imbricata, Marginotruncana sigali, M. pseudolinneiana, M. coronata and M. schneegansi. The benthic foraminifera, by comparison, are relatively rare and are represented by a low diversity assemblage. This is typical of northwestern European chalk successions of Turonian age and is coincident with the highest sea levels of the Cretaceous. In the middle to late Turonian there is a dramatic shallowing event that is recorded world-wide at this level. The assemblage changes towards the top of the accessible succession at Beer record this significant, world-wide event.     

Vascoceras (Greenhornoceras) birchbyi Cobban & Scott from the Greenhorn Limestone (Lower Turonian) of Central Kansas

The Early Turonian ammonite, Vascoceras (Greenhornoceras) birchbyi Cobban & Scott, has been recorded at nine additional localities in Kansas, Colorado and New Mexico. Most significant is discovery of a specimen in Russell County, Kansas, that doubles the known longitudinal range of the species in the U.S. Western Interior. The species occurs in a single, thin, time-parallel limestone bed that apparently was deposited during a peak pulse of the Cenomanian-Turonian transgression.