Evolution Applied Ltd

Cornwall, United Kingdom

Evolution Applied Ltd

Cornwall, United Kingdom
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Radmacher W.,ING PAN Instytut Nauk Geologicznych | Perez-Rodriguez I.,University of Zaragoza | Arz J.A.,University of Zaragoza | Pearce M.A.,Evolution Applied Ltd
Cretaceous Research | Year: 2014

Dinoflagellate cyst assemblages from a well-exposed uppermost Cretaceous section at Zumaia (northern Spain) provide a basis for comparison with previous biostratigraphic and magnetostratigraphic studies on the problematic location of the Campanian-Maastrichtian boundary in the section. The position of the last occurrence of Corradinisphaeridium horridum and first common occurrence of Alterbidinium acutulum, correspond well with the bioevents defining the Campanian-Maastrichtian boundary in the Global boundary Stratotype Section and Point of Tercis les Bains (130km to the North). Together with other age-diagnostic dinoflagellate cyst bioevents, we suggest that the boundary should be placed between 239.75 and 224.75m below the Cretaceous-Palaeogene boundary, about 46m lower than an interpretation based on the first occurrence of the planktonic foraminifer Pseudoguembelina palpebra and the last occurrence of the nannofossil Broinsonia parca subsp. constricta. A conspicuous acme of the dinoflagellate cyst Thalassiphora cf. delicata is encountered around the lower-upper Maastrichtian boundary (calibrated by foraminiferal, calcareous nannoplankton and magnetic polarity data), which may prove to be a useful correlatable event. © 2014 Elsevier Ltd.

Patterson M.O.,Victoria University of Wellington | McKay R.,Victoria University of Wellington | Naish T.,Victoria University of Wellington | Escutia C.,University of Granada | And 35 more authors.
Nature Geoscience | Year: 2014

The Pliocene and Early Pleistocene, between 5.3 and 0.8 million years ago, span a transition from a global climate state that was 2-3 °C warmer than present with limited ice sheets in the Northern Hemisphere to one that was characterized by continental-scale glaciations at both poles. Growth and decay of these ice sheets was paced by variations in the Earth's orbit around the Sun. However, the nature of the influence of orbital forcing on the ice sheets is unclear, particularly in light of the absence of a strong 20,000-year precession signal in geologic records of global ice volume and sea level. Here we present a record of the rate of accumulation of iceberg-rafted debris oshore from the East Antarctic ice sheet, adjacent to the Wilkes Subglacial Basin, between 4.3 and 2.2 million years ago. We infer that maximum iceberg debris accumulation is associated with the enhanced calving of icebergs during ice-sheet margin retreat. In the warmer part of the record, between 4.3 and 3.5 million years ago, spectral analyses show a dominant periodicity of about 40,000 years. Subsequently, the powers of the 100,000-year and 20,000-year signals strengthen. We suggest that, as the Southern Ocean cooled between 3.5 and 2.5 million years ago, the development of a perennial sea-ice field limited the oceanic forcing of the ice sheet. After this threshold was crossed, substantial retreat of the East Antarctic ice sheet occurred only during austral summer insolation maxima, as controlled by the precession cycle. © 2014 Macmillan Publishers Limited. All rights reserved.

Olde K.,Kingston University | Jarvis I.,Kingston University | Ulicny D.,Academy of Sciences of the Czech Republic | Pearce M.A.,Evolution Applied Ltd | And 7 more authors.
Palaeogeography, Palaeoclimatology, Palaeoecology | Year: 2015

Geochemical and palynological records are presented for an expanded Turonian-Coniacian hemipelagic succession in the central Bohemian Cretaceous Basin. A high-resolution stratigraphic framework is provided by biostratigraphy and organic carbon stable-isotope (δ13Corg) chemostratigraphy. A short-term (100 kyr) sea-level curve has been derived from high-resolution transgressive/regressive maxima / shore-proximity data established from basin-wide sediment geometries. The viability of geochemical and palynological parameters as potential sea-level proxies is tested against this independently derived sea-level record. Elemental chemostratigraphy is demonstrated to offer a reliable means of identifying medium- to long-term (0.4-2.4 Myr) sea-level trends. Manganese maxima are associated with periods of high sea level, and troughs with intervals of low sea level. Falling Mn contents accompany regression and rising values transgression. Major transgressive events associated with medium-term sea-level change are marked by sharp increases in Ti/Al ratios, but short-term (100 kyr) sea-level cycles are not consistently identified. Long-term δ13Corg variation and dinoflagellate cyst species richness are positively correlated and show similarities to the sea-level curve. Baseline trends have a cycle duration close to the 2.4 Myr long-eccentricity cycle. Dinocyst species richness closely follows short-term changes in sea level, with marked increases in dinocyst diversity coincident with most short-term flooding events. Periods of rapid sea-level rise caused an influx of a more diverse 'outer shelf' assemblage into the study area, together with the addition of shallower water species, some of which may have been transported into the central basin by hypopycnal flows. Changes in the proportion and abundance of peridinioid dinoflagellate cysts (principally Palaeohystrichophora infusorioides) were controlled principally by changing nutrient levels. Proximity proxies derived from geochemical and palynological data are not always consistent with the independent sea-level model. This exemplifies the need to understand all factors influencing elemental geochemical and palynological proxies before making simplistic sea level interpretations. © 2014 Elsevier B.V.

Olde K.,Kingston University | Jarvis I.,Kingston University | Pearce M.,Academy of Sciences of the Czech Republic | Ulicny D.,Evolution Applied Ltd | And 4 more authors.
Review of Palaeobotany and Palynology | Year: 2015

Organic walled dinoflagellate cyst (dinocyst) assemblage data are presented for a new Turonian regional reference core (Bch-1) drilled at Běchary in the Bohemian Cretaceous Basin, east-central Czech Republic. The detailed stratigraphic framework for the section is summarised based on calcareous nannofossil and macrofossil biostratigraphy, regional e-log correlation, sequence stratigraphy and carbon isotope chemostratigraphy. Dinocyst results obtained for 196 samples from the 405. m long core offer the highest resolution (22. kyr) stratigraphically well-constrained data set available to date for the Turonian Stage, 93.9-89.8. Ma. A dinocyst biostratigraphic framework is presented based on the evolutionary first and last occurrence, first common occurrence, and acmes of key species. Published dinocyst data from English Turonian Chalk successions in East Sussex, Berkshire, Kent and Norfolk are reviewed within a stratigraphic framework provided by macrofossil records and carbon isotope event (CIE) chemostratigraphy. Critical analysis of existing published Turonian dinocyst zonation schemes shows them to be untenable. Correlation of the English Chalk data to Bch-1 provides a basis for defining a regional dinocyst event stratigraphy with 22 datum levels, and a revised dinocyst zonation scheme constrained within a chemostratigraphic framework of 10 major CIEs. The new zones consist of a Cenomanian Litosphaeridium siphoniphorum Zone, followed by the Cauveridinium membraniphorum Zone spanning the uppermost Cenomanian to Lower Coniacian. This is subdivided into: Senoniasphaera turonica (Lower-mid-Middle Turonian); and Raetiaedinium truncigerum (mid-Middle Turonian-mid-Lower Coniacian) subzones. The Oligosphaeridium pulcherrimum Zone (. Senonisphaera rotundata Subzone) characterises the Lower Coniacian. The new stratigraphy offers a basis for improved correlation and dating of Upper Cretaceous successions. © 2014 Elsevier B.V.

Van Helmond N.A.G.M.,University Utrecht | Sluijs A.,University Utrecht | Papadomanolaki N.M.,University Utrecht | Plint A.G.,University of Western Ontario | And 9 more authors.
Biogeosciences | Year: 2016

Oceanic Anoxic Event 2 (OAE2), a ĝ1/4 600kyr episode close to the Cenomanian-Turonian boundary (ca. 94Ma), is characterized by relatively widespread marine anoxia and ranks amongst the warmest intervals of the Phanerozoic. The early stages of OAE2 are, however, marked by an episode of widespread transient cooling and bottom water oxygenation: the Plenus Cold Event. This cold spell has been linked to a decline in atmospheric pCO2, resulting from enhanced global organic carbon burial. To investigate the response of phytoplankton to this marked and rapid climate shift we examined the biogeographical response of dinoflagellates to the Plenus Cold Event. Our study is based on a newly generated geochemical and palynological data set from a high-latitude Northern Hemisphere site, Pratts Landing (western Alberta, Canada). We combine these data with a semi-quantitative global compilation of the stratigraphic distribution of dinoflagellate cyst taxa. The data show that dinoflagellate cysts grouped in the Cyclonephelium compactum-membraniphorum morphological plexus migrated from high to mid-latitudes during the Plenus Cold Event, making it the sole widely found (micro)fossil to mark this cold spell. In addition to earlier reports from regional metazoan migrations during the Plenus Cold Event, our findings illustrate the effect of rapid climate change on the global biogeographical dispersion of phytoplankton. © Author(s) 2016.

Olde K.,Kingston University | Jarvis I.,Kingston University | Pearce M.,Kingston University | Pearce M.,Evolution Applied Ltd | And 2 more authors.
Cretaceous Research | Year: 2016

A river section at Słupia Nadbrzez˙na, central Poland, has been proposed as a candidate Turonian - Coniacian (Cretaceous) GSSP, in combination with the Salzgitter-Salder quarry section of Lower Saxony, Germany. Results of a high-resolution (25 cm) palynological study of the boundary interval in the Słupia Nadbrzez˙na section are presented. Terrestrial palynomorphs are rare; marine organic-walled dinoflagellate cysts dominate the palynological assemblage. The dinoflagellate cyst assemblage has a low species richness (5-11 per sample; total of 18 species recorded) and diversity (Shannon index H = 0.8-1.4), dominated by four taxa: Circulodinium distinctum subsp. distinctum; Oligosphaeridium complex; Spiniferites ramosus subsp. ramosus; Surculosphaeridium longifurcatum. Declining proportions of O. complex and S. ramosus subsp. ramosus characterise the uppermost Turonian, with an increased dominance of S. longifurcatum in the lower Coniacian. The Turonian - Coniacian boundary interval includes an acme of C. distinctum subsp. distinctum in the upper Mytiloides scupini Zone, a dinoflagellate cyst abundance maximum in the Cremnoceramus walterdorfensis walterdorfensis Zone, and the highest occurrence of Senoniasphaera turonica in the basal Coniacian lower Cremnoceramus deformis erectus Zone. Most previously reported Turonian - Coniacian boundary dinoflagellate cyst marker species are absent; a shallow-water oligotrophic epicontinental depositional setting, remote from terrestrial influence, likely limited species diversity and excluded many taxa of biostratigraphic value. © 2016 Elsevier Ltd.

Radmacher W.,Polish Academy of Sciences | Tyszka J.,Polish Academy of Sciences | Mangerud G.,University of Bergen | Pearce M.A.,Evolution Applied Ltd
Marine and Petroleum Geology | Year: 2014

The present study of five wells from Upper Albian to Lower Maastrichtian succession in the southwestern Barents Sea yields the first dinoflagellate cyst-based palynological event biostratigraphy for the area. The research focuses on the Upper Cretaceous Kveite and Kviting formations due to the lack of formal palynological documentation, and enables the formation of a biozonation of greater resolution than currently achievable by micropalaeontology. Four new interval zones and one abundance subzone are described, from base upward: Palaeohystrichophora infusorioides and Palaeohystrichophora palaeoinfusa Interval Zone (intra Early Cenomanian-intra Late Cenomanian), Dinopterygium alatum Interval Zone (?intra Early Coniacian-Late Santonian), Palaeoglenodinium cretaceum Interval Zone (Early Campanian), and the Chatangiella bondarenkoi Interval Zone (Late Campanian) encompassing the Heterosphaeridium bellii Abundance Subzone (intra-Late Campanian). The zones are well correlated to existing palynological zonations from the Norwegian-Greenland Sea, where the previously described Subtilisphaera kalaalliti Interval Zone (intra Late Albian-?intra Early Cenomanian), Heterosphaeridium difficile Interval Zone (Middle Turonian to ?intra Early Coniacian) and Cerodinium diebelii Interval Zone (Early Maastrichtian) are recognised. These data also reveal the presence of three significant unconformities of Late Cenomanian-Early Turonian, Middle Campanian and Late Maastrichtian-Paleocene age. © 2014 Elsevier Ltd.

Barron J.A.,U.S. Geological Survey | Stickley C.E.,Evolution Applied Ltd. | Bukry D.,U.S. Geological Survey
Palaeogeography, Palaeoclimatology, Palaeoecology | Year: 2015

Eocene diatom and silicoflagellate biostratigraphy are summarized and correlated with the most recent geologic time scale as well as with the global oxygen isotope and eustatic sea level curves. The global distribution of Eocene diatom/silicoflagellate-bearing sediments varies considerably, reflecting changing oceanic gateways and paleoceanography with changing patterns that are punctuated by four major depositional events.Event 1 (~. 49 million years ago, Ma), at the end of the Early Eocene Climatic Optimum (EECO), saw the cessation of diatom/silicoflagellate deposition in epicontinental regions of the North Sea region and in the northern Russia and the onset of biosilica deposition in the Arctic. Event 2 (~. 46. Ma), which coincided with intensification of the Middle Eocene cooling trend, marked the widespread expansion of diatom/silicoflagellate deposition in both the North and South Atlantic. A shift of diatom/silicoflagellate deposition from the Atlantic to the Pacific began at Event 3, at the end of the Middle Eocene Climatic Optimum (MECO) (~. 40. Ma), that was likely tied to the initial opening of the Drake Passage between Antarctica and South America. Event 4 (~. 39. Ma) coincided with a major sea level fall and a widespread deep-sea hiatus in the latest Middle Eocene. Late Eocene diatom/silicoflagellate deposition became more concentrated in middle-to-high latitude regions and coastal upwelling regions, particularly in the Pacific Ocean.Tabulation of the first and last occurrences of 132 biostratigraphically-important diatoms suggests increased species turnover during the latest Paleocene to earliest Eocene that may be in part due to a monographic effect. An increasing rate of evolution of new diatom species between ~. 46 and 43. Ma and after ~. 40. Ma coincides respectively with the widespread expansion of diatom deposition in the Atlantic and with an increased pole-to-equator thermal gradient that witnessed the expansion of diatoms in high latitude oceans and coastal upwelling settings. © 2015.

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