NEW ARTICLE PUBLISHED!

New Albian to Cenomanian (Cretaceous) dinoflagellate cyst taxa of ovoidinioid affinities from East Greenland, the Barents Sea and England

Henrik Nøhr-Hansen, Lucy I. Costa, Martin A. Pearce and Peter Alsen

Abstract. Palyno-biostratigraphical studies of upper Albian-Lower Cenomanian successions from East Greenland, the south-western Barents Sea and south-eastern England have revealed new dinoflagellate cyst taxa of clear or questioned ovoidinioid affinities. This paper describes the new genus Sindridinium, four new species – Ovoidinium epelidosphaeroides sp. nov., Epelidosphaeridia manifesta sp. nov., Sindridinium borealis gen. et sp. nov. and Sindridinium anaanae gen. et sp. nov. – and proposes a new combination, Sindridinium? torulosa comb. nov. (formerly Canningia torulosa). The genus Epelidosphaeridia is emended based on features seen in E. manifesta sp. nov., which demonstrate peridiniacean affinities and support inclusion in the Ovoidinioideae. Morphological gradations between Epelidosphaeridia spinosa, E. manifesta sp. nov. and Ovoidinium epelidosphaeroides sp. nov., suggest close phylogenetic relationships, also postulated between Sindridinium? torulosa comb. nov., S. borealis gen. et sp. nov. and S. anaanae gen. et sp. nov. The stratigraphic ranges of the taxa described are calibrated to known dinoflagellate markers and mid-Cretaceous ammonites.

PALYNOLOGY, 42, 366-391, 2018
https://doi.org/10.1080/01916122.2017.1351006

 

NEW ARTICLE PUBLISHED!

Additional new organic-walled dinoflagellate cysts from two onshore UK Chalk boreholes

Martin A. Pearce

Abstract. Beautifully preserved dinoflagellate cysts continue to be discovered in UK Cretaceous chalks and provide important new biostratigraphic information. Five new species – Conosphaeridium norfolkense sp. nov., Glaphyrocysta coniacia sp. nov., Impletosphaeridium banterwickense sp. nov., Sentusidinium devonense sp. nov., Sentusidinium spinosum sp. nov. and the new subspecies Spiniferites ramosus subsp. ginakrogiae subsp. nov. – are described from Upper Cretaceous strata of the British Geological Survey (BGS) Banterwick Barn and Trunch boreholes (onshore UK). An emended diagnosis for Odontochitina diducta Pearce is also provided to broaden the morphological variability in the type material.

J. Micropalaeontology, 37, 73–86, 2018
https://doi.org/10.5194/jm-37-73-2018

 

NEW ARTICLE PUBLISHED

Water-mass evolution in the Cretaceous Western Interior Seaway of North America and equatorial Atlantic

James S. Eldrett, Paul Dodsworth, Steven C. Bergman, Milly Wright and Daniel Minisini

Abstract. The Late Cretaceous Epoch was characterized by major  global  perturbations  in  the  carbon  cycle,  the  most prominent  occurring  near  the  Cenomanian–Turonian (CT) transition  marked  by  Oceanic  Anoxic  Event  2  (OAE-2) at  94.9–93.7 Ma.  The  Cretaceous  Western  Interior  Seaway (KWIS) was one of several epicontinental seas in which a complex water-mass evolution was recorded in widespread sedimentary  successions.  This  contribution  integrates  new data on the main components of organic matter, geochemistry, and stable isotopes along a north–south transect from the  KWIS  to  the  equatorial  western  Atlantic  and  Southern Ocean. In particular, cored sedimentary rocks from the Eagle Ford Group of west Texas (∼90–98 Ma) demonstrate subtle  temporal  and  spatial  variations  in  palaeoenvironmental conditions  and  provide  an  important  geographic  constraint for interpreting water-mass evolution. High-latitude (boreal–austral),  equatorial  Atlantic  Tethyan  and  locally  sourced Western Interior Seaway water masses are distinguished by distinct palynological assemblages and geochemical signatures.  The  northward  migration  of  an  equatorial  Atlantic Tethyan  water  mass  into  the  KWIS  occurred  during  the early–middle  Cenomanian  (98–95 Ma)  followed  by  a  major re-organization during the latest Cenomanian–Turonian (95–94 Ma) as a full connection with a northerly boreal water  mass  was  established  during  peak  transgression.  This oceanographic change promoted de-stratification of the water column and improved oxygenation throughout the KWIS and as far south as the Demerara Rise off Suriname. In addition, the recorded decline in redox-sensitive trace metals during the onset of OAE-2 likely reflects a genuine oxygenation event related to open water-mass exchange and may have been complicated by variable contribution of organic matter from different sources (e.g. refractory/terrigenous material), requiring further investigation.

Clim. Past, 13, 855–878, 2017
https://doi.org/10.5194/cp-13-855-2017

 

  • You are here:  
  • Home
  • News