scholarly journals Chemostratigraphy of the Toarcian oceanic anoxic event from the Ionian Zone, Greece

2017 ◽  
Vol 47 (2) ◽  
pp. 825
Author(s):  
N. Kafousia ◽  
V. Karakitsios ◽  
E. Mattioli ◽  
H.C. Jenkyns
Keyword(s):  
Carbon Isotope ◽  
Relative Increase ◽  
Geochemical Data ◽  
Oceanic Anoxic Event ◽  
Carbonate Carbon ◽  
Carbon Burial ◽  
Organic Carbon Burial ◽  
Anoxic Event ◽  
The Difference ◽  
The Impact

A global perturbation in the carbon cycle has been recorded in the Early Toarcian (~ 183 Ma) and is marked by enhanced organic-carbon burial and mass extinction. It is also associated with high palaeotemperatures, both positive and negative excursions in carbon-isotope ratios, and the development of anoxic to euxinic conditions in marine environments: together these phenomena have been designated as constituting an Oceanic Anoxic Event. Here we provide a high-resolution, multiproxy biostratigraphic and chemostratigraphic study from a section that belongs to the central Ionian Zone in Greece. Calcareous nannofossil distribution, as well as the TOC, δ13Ccarb and δ13Corg, have all been determined. The nannofossil zones NJT 5b, NJT 6 and NJT 7 have been recognized in the section. In the NJT 5b zone a small positive excursion in TOC and negative excursion in δ13Ccarb is recorded, tentatively assigned to the Pliensbachian/Toarcian boundary. In the NJT 6 zone, the main negative carbon-isotope excursion characteristic of this interval is developed, associated with a relative increase in TOC. The difference in this section, compared with sections from the Pindos Zone but in common with sections elsewhere, is the record of a positive excursion in the NJT 7 zone in both organic and carbonate carbon isotopes. This study offers new biostratigraphic and geochemical data for the Ionian Zone, and further illustrates the impact of Toarcian Oceanic Anoxic Event in the Tethyan region.

scholarly journals PRELIMINARY DATA FROM THE FIRST RECORD OF THE EARLY TOARCIAN OCEANIC ANOXIC EVENT IN THE SEDIMENTS OF THE PINDOS ZONE (GREECE)

2017 ◽  
Vol 43 (2) ◽  
pp. 627 ◽  
Author(s):  
Kafousia N. Kafousia N. ◽  
V. Karakitsios ◽  
H.C. Jenkyns
Keyword(s):  
Organic Carbon ◽  
Carbon Isotope ◽  
First Record ◽  
Passive Margin ◽  
Oceanic Anoxic Event ◽  
Carbonate Carbon ◽  
Carbon Burial ◽  
Organic Carbon Burial ◽  
Anoxic Event ◽  
Regional Character

The Early Toarcian Oceanic Anoxic Event (ca 183 Ma) coincides with high palaeotemperatures, regional anoxia to euxinia, marine transgression, mass extinction and high rates of organic-carbon burial in a global context. Most of the detailed studies of this event have investigated deposits formed in the epicontinental seas of northern Europe, although coeval organic-rich shales are known locally in the Tethyan region. However, the global or regional character of this event is still under debate. In this study we present, for the first time, a high-resolution geochemical record of the Early Toarcian Oceanic Anoxic event in pelagic sediments (Kastelli Pelites) formed in a long-lived Mesozoic deep-sea basin, corresponding to the western passive margin of the Pindos Ocean of western Greece. Our data record both the positive excursion in total organic carbon (TOC) and the characteristic negative excursion in δ13Ccarb. The δ13Ccarb values are very stable in the bottom of the section (~2‰), whereas higher in the section the values drop down to ~ -5‰. Following this negative excursion, the carbonate carbon-isotope ratios return to background values. The TOC excursion is modest, rising from a background of 0.05% to ~ 2% and then returning to a background of 0.04%. Because both relative enrichment in TOC and the negative carbon-isotope excursion that characterize the Toarcian OAE are recorded in some of the deepest marine sediments of the Tethyan region, the global significance of the event is reinforced.

scholarly journals Enhanced terrestrial runoff during Oceanic Anoxic Event 2 on the North Carolina Coastal Plain, USA

2021 ◽  
Vol 17 (3) ◽  
pp. 1227-1242
Author(s):  
Christopher M. Lowery ◽  
Jean M. Self-Trail ◽  
Craig D. Barrie
Keyword(s):  
North Carolina ◽  
Organic Carbon ◽  
Carbon Isotope ◽  
Coastal Plain ◽  
Hydrologic Cycle ◽  
Oceanic Anoxic Event ◽  
Carbon Burial ◽  
Organic Carbon Burial ◽  
Oceanic Anoxic Event 2 ◽  
Anoxic Event

Abstract. A global increase in the strength of the hydrologic cycle drove an increase in the flux of terrigenous sediments into the ocean during the Cenomanian–Turonian Oceanic Anoxic Event 2 (OAE2) and was an important mechanism driving nutrient enrichment and thus organic carbon burial. This global change is primarily known from isotopic records, but global average data do not tell us anything about changes at any particular location. Reconstructions of local terrigenous flux can help us understand the role of regional shifts in precipitation in driving these global trends. The proto-North Atlantic basin was one of the epicenters of enhanced organic carbon burial during OAE2, so constraining terrigenous flux is particularly important in this region; however, few local records exist. Here, we present two new OAE2 records from the Atlantic Coastal Plain of North Carolina, USA, recognized with calcareous nannoplankton biostratigraphy and organic carbon isotopes. We use carbon / nitrogen ratios to constrain the relative contribution of marine and terrestrial organic matter; in both cores we find an elevated contribution from vascular plants beginning just before OAE2 and continuing through the event, indicating a locally strengthened hydrologic cycle. Terrigenous flux decreased during the brief change in carbon isotope values known as the Plenus carbon isotope excursion; it then increased and remained elevated through the latter part of OAE2. Total organic carbon (TOC) values reveal relatively low organic carbon burial in the inner shelf, in contrast to black shales known from the open ocean. Organic carbon content on the shelf appears to increase in the offshore direction, highlighting the need for cores from the middle and outer shelf.

scholarly journals Enhanced productivity led to increased organic carbon burial in the euxinic North Atlantic basin during the late Cenomanian oceanic anoxic event

2002 ◽  
Vol 17 (4) ◽  
pp. 3-1-3-13 ◽  
Author(s):  
Marcel M. M. Kuypers ◽  
Richard D. Pancost ◽  
Ivar A. Nijenhuis ◽  
Jaap S. Sinninghe Damsté
Keyword(s):  
Organic Carbon ◽  
North Atlantic ◽  
Atlantic Basin ◽  
Oceanic Anoxic Event ◽  
North Atlantic Basin ◽  
Carbon Burial ◽  
Organic Carbon Burial ◽  
Anoxic Event

scholarly journals Orbital forcing of organic carbon burial in the proto-North Atlantic during oceanic anoxic event 2

2004 ◽  
Vol 228 (3-4) ◽  
pp. 465-482 ◽  
Author(s):  
Marcel M.M. Kuypers ◽  
Lucas J. Lourens ◽  
W. Irene C. Rijpstra ◽  
Richard D. Pancost ◽  
Ivar A. Nijenhuis ◽  
...  
Keyword(s):  
Organic Carbon ◽  
North Atlantic ◽  
Orbital Forcing ◽  
Oceanic Anoxic Event ◽  
Carbon Burial ◽  
Organic Carbon Burial ◽  
Oceanic Anoxic Event 2 ◽  
Anoxic Event

scholarly journals Equatorward phytoplankton migration during a cold spell within the Late Cretaceous supergreenhouse

2016 ◽  
Author(s):  
Niels A.G.M. van Helmond ◽  
Appy Sluijs ◽  
Nina M. Papadomanolaki ◽  
A.Guy Plint ◽  
Darren R. Gröcke ◽  
...  
Keyword(s):  
Bottom Water ◽  
Cold Spell ◽  
Cold Event ◽  
Climate Shift ◽  
Oceanic Anoxic Event ◽  
Rapid Climate Change ◽  
Carbon Burial ◽  
Organic Carbon Burial ◽  
Oceanic Anoxic Event 2 ◽  
Anoxic Event

Abstract. Oceanic Anoxic Event 2 (OAE2), a ~600 kyr episode close to the Cenomanian-Turonian boundary (ca. 94 Ma), is characterized by 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 dataset from a high-latitude Northern Hemisphere site, Pratts Landing (western Alberta, Canada). We combine this 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.

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