scholarly journals Supplemental Material: Carbon isotope and sequence stratigraphy of the upper Isachsen Formation on Axel Heiberg Island (Nunavut, Canada): High Arctic expression of oceanic anoxic event 1a in a deltaic environment

2021 ◽  
Author(s):  
W. Dummann ◽  
et al.
Keyword(s):  
Sequence Stratigraphy ◽  
Carbon Isotope ◽  
High Arctic ◽  
Geochemical Data ◽  
Oceanic Anoxic Event ◽  
Anoxic Event ◽  
Axel Heiberg Island

<div>Geochemical data and the age models presented in this study.<br></div><div><br></div><div><br></div><div><br></div><div><br></div>

Carbon isotope and sequence stratigraphy of the upper Isachsen Formation on Axel Heiberg Island (Nunavut, Canada): High Arctic expression of oceanic anoxic event 1a in a deltaic environment

2021 ◽  
Author(s):  
Wolf Dummann ◽  
Claudia Schröder-Adams ◽  
Peter Hofmann ◽  
Janet Rethemeyer ◽  
Jens O. Herrle
Keyword(s):  
Carbon Isotope ◽  
Sedimentary Environment ◽  
High Arctic ◽  
Geochemical Data ◽  
Sea Level Changes ◽  
Sequence Stratigraphic ◽  
Oceanic Anoxic Event ◽  
Stratigraphic Framework ◽  
Anoxic Event ◽  
Sverdrup Basin

&lt;p&gt;Oceanic anoxic event (OAE) 1a documents a major perturbation of the Early Cretaceous global carbon cycle with severe consequences for the ocean-climate-biosphere system. While numerous studies over the past decades have provided a relatively detailed picture of the environmental repercussions of OAE 1a at low and mid-latitudes, studies from high latitudes, in particular the High Arctic, are limited. In this study, we present a high-resolution carbon isotopic and sequence stratigraphic framework for the lower to lower upper Aptian interval of the Isachsen Formation of the High Arctic Sverdrup Basin (Canada). These data enable us to precisely locate the stratigraphic position of OAE 1a in a deltaic sedimentary environment. The carbon isotope record allows, for the first time, identification of the different carbon isotope segments (CISs) of OAE 1a in the Sverdrup Basin and thereby correlation of the High Arctic record with sections from lower latitudes. Based on this improved chemostratigraphy, we revise the age of upper Paterson Island, Rondon, and Walker Island Members, important regional lithostratigraphic marker units. Whole-rock geochemical data record two episodes of marine incursion into the Sverdrup Basin during OAE 1a (CISs Ap3 and Ap6), which are interpreted as regional maximum flooding surfaces. This information is used in conjunction with detailed sedimentological logs and geochemical grain-size proxies to refine the sequence stratigraphic framework for the upper Isachsen Formation. We propose that transgressive-regressive cycles in the Sverdrup Basin were mainly controlled by the combined effects of eustatic sea-level changes and regional tectonic uplift, potentially related to the emplacement of Alpha Ridge, which culminated at ca. 122 Ma during CIS Ap9.&lt;/p&gt;

scholarly journals Carbon isotope and sequence stratigraphy of the upper Isachsen Formation on Axel Heiberg Island (Nunavut, Canada): High Arctic expression of oceanic anoxic event 1a in a deltaic environment

Geosphere ◽  
2020 ◽  
Author(s):  
W. Dummann ◽  
C. Schröder-Adams ◽  
P. Hofmann ◽  
J. Rethemeyer ◽  
J.O. Herrle
Keyword(s):  
Carbon Isotope ◽  
Sedimentary Environment ◽  
High Arctic ◽  
Geochemical Data ◽  
Sea Level Changes ◽  
Sequence Stratigraphic ◽  
Oceanic Anoxic Event ◽  
Stratigraphic Framework ◽  
Anoxic Event ◽  
Sverdrup Basin

The Early Cretaceous oceanic anoxic event (OAE) 1a documents a major perturbation of the global carbon cycle with severe consequences for the ocean-climate-biosphere system. While numerous studies over the past decades have provided a relatively detailed picture of the environmental repercussions of OAE 1a at low and mid-latitudes, studies from high latitudes, in particular the High Arctic, are limited. In this study, we present a high-resolution carbon isotopic and sequence stratigraphic framework for the lower to lower upper Aptian interval of the Isachsen Formation of the High Arctic Sverdrup Basin (Canada). These data enable us to precisely locate the stratigraphic position of OAE 1a in a deltaic sedimentary environment. The carbon isotope record allows, for the first time, identification of the different carbon isotope segments (CISs) of OAE 1a in the Sverdrup Basin and thereby correlation of the High Arctic record with sections from lower latitudes. Based on this improved chemostratigraphy, we revise the age of upper Paterson Island, Rondon, and Walker Island Members, important regional lithostratigraphic marker units. Whole-rock geochemical data record two episodes of marine incursion into the Sverdrup Basin during OAE 1a (CISs Ap3 and Ap6), which are interpreted as regional maximum flooding surfaces. This information is used in conjunction with detailed sedimentological logs and geochemical grain-size proxies to refine the sequence stratigraphic framework for the upper Isachsen Formation. We propose that transgressive-regressive cycles in the Sverdrup Basin were controlled mainly by the combined effects of eustatic sea-level changes and regional tectonic uplift, potentially related to the emplacement of Alpha Ridge, which culminated at ca. 122 Ma during CIS Ap9.

Astronomical pacing of relative sea level during Oceanic Anoxic Event 2: Preliminary studies of the expanded SH#1 Core, Utah, USA

2019 ◽  
Vol 131 (9-10) ◽  
pp. 1702-1722 ◽  
Author(s):  
Matthew M. Jones ◽  
Bradley B. Sageman ◽  
Rosie L. Oakes ◽  
Amanda L. Parker ◽  
R. Mark Leckie ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Sea Level ◽  
Carbon Isotope ◽  
Geochemical Data ◽  
Relative Sea Level ◽  
Data Set ◽  
Sequence Stratigraphic ◽  
Oceanic Anoxic Event ◽  
Oceanic Anoxic Event 2 ◽  
Anoxic Event

AbstractProximal marine strata of the North American Western Interior Basin (WIB) preserve a rich record of biotic turnover during Oceanic Anoxic Event 2 (OAE2; ca. 94 Ma), a pronounced Late Cretaceous carbon cycle perturbation interpreted to reflect global warming, widespread hypoxia, and possible ocean acidification. To develop a more robust synthesis of paleobiologic and geochemical data sets spanning this Earth-life transition, we drilled the 131 m Smoky Hollow #1 Core (SH#1), on the Kaiparowits Plateau of southern Utah, USA, recovering the Cenomanian–Turonian Boundary (CTB) interval in the Tropic Shale Formation. A 17.5 m positive excursion in high-resolution bulk carbon isotope chemostratigraphy (δ13Corg) of SH#1 characterizes the most expanded OAE2 record recovered from the mid-latitudes of the WIB.Depleted values in a paired carbonate carbon isotope (δ13Ccarb) chemostratigraphy cyclically punctuate the OAE2 excursion. These depletions correspond to intervals in the core with a higher degree of carbonate diagenesis and correlate well to an existing sequence stratigraphic framework of flooding surfaces in the shoreface facies of the Markagunt Plateau (∼100 km west). We detect statistically significant evidence for astronomical cycles in the δ13Ccarb data set, imparted by diagenesis at flooding surfaces, and develop a floating astronomical time scale (ATS) for the study interval. Stable eccentricity cycles (405 k.y.) align with stratigraphic sequences and associated trends in sedimentation rate, and short eccentricity cycles (∼100 k.y.) pace nested parasequences. These results confirm an astronomical signal and, therefore, climatic forcing of relative sea level during OAE2 in the WIB. Furthermore, cross-basin correlation of the ATS and expanded δ13C chemostratigraphy of SH#1 suggests that these transgressive-regressive parasequences modulated siliciclastic sediment delivery in the seaway and contributed to deposition of prominent rhythmically bedded CTB units across the WIB, including the Bridge Creek Limestone. The presented approach to analysis of these proximal offshore siliciclastic facies links early diagenetic influences on chemostratigraphy to astronomically modulated sequence stratigraphic horizons, and helps to resolve rates of paleobiologic and paleoenvironmental change during a significant Mesozoic carbon cycle perturbation.

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.

Carbon-isotope and microfaunal stratigraphy bounding the Lower Aptian Oceanic Anoxic Event 1a in northeastern Tunisia

2013 ◽  
Vol 39 ◽  
pp. 133-148 ◽  
Author(s):  
Abdallah Elkhazri ◽  
Hassen Abdallah ◽  
Saloua Razgallah ◽  
Michel Moullade ◽  
Wolfgang Kuhnt
Keyword(s):  
Carbon Isotope ◽  
Oceanic Anoxic Event ◽  
Lower Aptian ◽  
Anoxic Event ◽  
Northeastern Tunisia

The chemostratigraphy and environmental significance of the Marlstone and Junction Bed (Beacon Limestone, Toarcian, Lower Jurassic, Dorset, UK)

2021 ◽  
pp. 1-15
Author(s):  
Hugh C. Jenkyns ◽  
Sophie Macfarlane
Keyword(s):  
Carbon Isotope ◽  
Oxygen Isotopes ◽  
Lower Jurassic ◽  
Carbon And Oxygen Isotopes ◽  
Oceanic Anoxic Event ◽  
Nodular Limestone ◽  
Anoxic Event ◽  
Reference Curves ◽  
High Degree ◽  
Organic Rich Sediment

Abstract Two fallen blocks of the Marlstone and stratigraphically overlying Junction Bed sampled on the beach below Doghouse Cliff in Dorset, UK (Wessex Basin) have been examined for carbon and oxygen isotopes of bulk carbonate as well as for strontium, carbon and oxygen isotopes and Mg:Ca ratios in the contained belemnites. The sequence, which contains most of the Toarcian zones and subzones within a metre or less of grey to yellow to pink, red and brown fossil-rich nodular limestone, is extremely condensed and lithologically similar to pelagic red limestones of the Tethyan Jurassic that are locally mineralized with Fe-Mn oxyhydroxides (e.g., Rosso Ammonitico). Strontium-isotope ratios of the contained belemnites are compatible with existing reference curves and both blocks show a rise to more radiogenic values post-dating the Pliensbachian–Toarcian boundary. The high degree of correlation between the relatively negative carbon and oxygen isotopes of the bulk carbonate is compatible with significant diagenetic overprint, and contrasts with higher carbon-isotope values in coeval condensed coccolith-rich limestones elsewhere. Evidence for the characteristic signature of the Toarcian Oceanic Anoxic Event, as represented by organic-rich sediment, is absent, possibly owing to a stratigraphic gap. Both blocks exhibit abrupt carbon-isotope shifts to lower values, one of which could represent the limbs of an incompletely recorded negative excursion associated with the Toarcian Oceanic Anoxic Event. That the Toarcian Oceanic Anoxic Event was also a significant hyperthermal is illustrated in both blocks by a drop in oxygen-isotope values and rise in Mg:Ca ratios of belemnites close to the base of the Junction Bed in the lowest part of the serpentinum zone.

A new record of the Toarcian oceanic anoxic event from Scotland (UK) and environmental responses

2021 ◽  
Author(s):  
Wenhan Chen ◽  
David Bryan Kemp ◽  
Tianchen He ◽  
Chunju Huang
Keyword(s):  
Chemical Weathering ◽  
Coarse Grained ◽  
Global Ocean ◽  
Geochemical Data ◽  
Oceanic Anoxic Event ◽  
Organic Carbon Isotope ◽  
Anoxic Event ◽  
Geographic Differences ◽  
Environmental Responses ◽  
Global Carbon

&lt;p&gt;The early Toarcian oceanic anoxic event (T-OAE, ~183 Ma) was characterized by a prominent environmental perturbation, likely associated with a large amount of &lt;sup&gt;12&lt;/sup&gt;C-enriched carbon released into the global ocean-atmosphere system. This effusion caused a marked disruption to the global carbon cycle and propagated a series of remarkable changes in ocean chemistry and climate. Although the T-OAE has been recognized worldwide, clear geographic differences in the character of the event and its environmental effects have been recognized. Here, we present new geochemical data from a lower Toarcian succession on the Isle of Raasay, NE Scotland (Hebrides Basin, Northwest European Shelf). Organic carbon isotope data through the Raasay section reveal a pronounced negative excursion, similar to that recognised globally. The excursion interval is enriched in organic matter, and redox sensitive element data suggest that suboxic bottom water conditions contemporaneously occurred, likely interspersed with anoxic episodes. Our findings contrast with evidence of more pervasive anoxia/euxinia in nearby basins, and emphasize how deoxygenation was spatially variable within the T-OAE. Inorganic geochemical data and sedimentological observations suggest a significant enhancement in chemical weathering and coarse-grained detrital flux during the T-OAE on Raasay. These findings support evidence from other localities for a strengthening of hydrological cycling in response to global warming during the T-OAE.&lt;/p&gt;

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