Mid-Cretaceous oceanic anoxic events in the Pacific Ocean revealed by carbon-isotope stratigraphy of the Calera Limestone, California, USA

Robinson, Stuart A.; Clarke, Leon J.; Nederbragt, Alexandra J.; Wood, I. G.

doi:10.1130/b26350.1

Cited by 41 publications

(32 citation statements)

References 39 publications

(58 reference statements)

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“…Therefore, we cannot rule out option B presented by Robinson et al . []. However, the difference in the detailed chemostratigraphy has little impact on our interpretations that the section spans the pre‐OAE1a interval and most of the positive CIE (i.e., segments C1–C7 of Menegatti et al []) (Figure ).…”

Section: Resultsmentioning

confidence: 91%

“…The other places the negative δ 13 C excursion ~0.6 m below the organic‐rich chert layer [i.e., option B in Robinson et al . , ]. We have elected to display Figure a because our δ 13 C data do not show a negative δ 13 C excursion below the chert layer that was attributed to segment C3 in Figure b.…”

Section: Resultsmentioning

confidence: 99%

“…In Figure a, C1–C3, C7, and C8 refer to portions of the profile that we correlate with the δ 13 C carb segments of Menegatti et al [], which corresponds to the “option A” correlation of Robinson et al . []. The alternative correlation (option B) [ Robinson et al .…”

Section: Resultsmentioning

confidence: 99%

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Biogeochemical sulfur cycling during Cretaceous oceanic anoxic events: A comparison of OAE1a and OAE2

2016

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Biogeochemical sulfur cycling has varied widely over geologic time, mainly in response to changes in primary productivity and organic carbon burial, volcanism, weathering, and evaporite deposition. Several of these processes are explicitly linked to discreet (<1.2 Ma) intervals of widespread organic carbon burial, termed oceanic anoxic events (OAEs). During the Cretaceous, there is a highly distinctive ~4‰ negative excursion in the sulfur isotope composition of seawater sulfate (δ34SSO4) that is bracketed by the two most prominent OAEs (OAE1a and OAE2). This excursion lasted for ~25 Ma and has been variously attributed to enhanced volcanism, changes in weathering, evaporite burial, and/or changes in modes of organic carbon remineralization. We present new high‐resolution carbon and sulfur isotope records from carbonate‐associated sulfate and pyrite for OAE1a and OAE2. OAE1a is characterized by a monotonic decrease in δ34SSO4 values. Both negative and positive δ34SSO4 excursions are associated with OAE2. To refine hypotheses for the observed changes in biogeochemical sulfur cycling associated with these events, we use a simple sulfur isotope box model. Both empirical and modeling results indicate that δ34SSO4 variability was dominated by input fluxes during OAE1a, whereas enhanced volcanism, weathering, and pyrite burial controlled δ34SSO4 records during OAE2. Our analysis supports the conclusion that Cretaceous marine sulfate concentrations were much lower than modern concentrations and indicates that increases in marine sulfate occurred at the onset of both events. We conclude that increases in marine sulfate from low background concentrations, in conjunction with other environmental characteristics, contributed to the development of OAEs.

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Section: Resultsmentioning

confidence: 91%

Section: Resultsmentioning

confidence: 99%

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Biogeochemical sulfur cycling during Cretaceous oceanic anoxic events: A comparison of OAE1a and OAE2

2016

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“…The early Aptian event (Selli event, OAE 1a) has its type locality in Italy, named "Livello Selli" (Coccioni et al 1989;Baudin et al 1998;Li et al 2008;Blättler et al 2011), and the event of early Albian (Paquier event, OAE 1b) was first recognized in the Vocontian basin in southeastern France (Bréhéret 1985(Bréhéret , 1994Herrle et al 2003). Both events are well represented by organic rich black shales in the Alpine-Mediterranean region and anthers regions of the world (Sliter 1989;Bralower et al 1993;Herrle et al 2003;Tsikos et al 2004;Robinson et al 2008;Hofmann et al 2008;Blättler et al 2011;Nuñez-Useche et al 2014).…”

Section: Oceanic Anoxic Event 1a and Oceanic Anoxic Event 1b -Black Smentioning

confidence: 99%

“…These high total organic carbon (TOC) levels are the expression in the Maracaibo Basin sedimentary record of two oceanic anoxic events (OAEs): OAE 1a of the early Aptian (~ 120 Ma), represented by the Machiques Member, and the OAE 1b of the late Aptian (~ 113 Ma), represented by the Piché Member, both of them belong to the Apón Formation (Méndez et al 2008). These two bituminous intervals, whose correlative sections have been studied in many sedimentary basins in Europe, the Mediterranean sea, Florida (USA), Gulf of Mexico, the Pacific and the Atlantic oceans (Sliter 1989;Bralower et al 1993Bralower et al , 1994Jenkyns & Wilson 1999;Leckie et al 2002;Dumitrescu et al 2006;Hofmann et al 2008;Robinson et al 2008), represent two effective source rock levels. This implies a new configuration of the Cogollo Group and Río Negro Formation petroleum system.…”

Section: Introductionmentioning

confidence: 99%

The Cogollo Group and the oceanic anoxic events 1a and 1b, Maracaibo basin, Venezuela

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et al. 2015

Braz. J. Geol.

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ABSTRACT:Carbonates of Cogollo Group (Apón, Lisure and Maraca formations) constitute the broader calcareous platform system originated during Aptian and Albian of Cretaceous in north-western South America, Maracaibo Basin, Venezuela. On the shallow shelf, a variety of calcareous sedimentary facies were deposited during marine transgressive and regressive cycles. Some of them developed porosity and constitute important hydrocarbon reservoirs. Due to some major marine transgressions, from early Aptian, the anoxic environment and characteristic facies of a pelagic environment moved from the outer slope and basin to the shallow shelf, during specific time intervals, favouring the sedimentation of organic matter-rich facies, which correspond to the oceanic anoxic events (OAEs) 1a and 1b. The source rock of Machiques Member (Apón Formation) was deposited during early Aptian OAE 1a (~ 120 Ma). The source rock of Piché Member, located at the top of the Apón Formation, was deposited during late Aptian OAE 1b (~ 113 Ma). Finally, La Luna Formation, from Cenomanian, that covers the OAE 2 (~ 93 Ma), represents the most important source rock in the Maracaibo Basin. In this way and based on sedimentological and organic geochemistry results from the determinations performed on 247 samples belonging to six cores in the Maracaibo Basin, we propose these two organic-rich levels, deposited on the shallow shelf of the Cogollo Group, as "effective source rocks", additional to La Luna Formation, with oil migration in relatively small distances to the porosity facies. KEYWORDS:

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Onset and demise of Cretaceous oceanic anoxic events: The coupling of surface and bottom oceanic processes in two pelagic basins of the western Tethys

et al. 2016

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The upper Albian-lower Turonian pelagic successions of the Tethys record processes acting during the onset, core, and recovery from perturbed conditions across oceanic anoxic event (OAE) 1d, OAE 2, and the mid-Cenomanian event I (MCE I) relative to intervening intervals. Five sections from Umbria-Marche and Belluno Basins (Italy) were analyzed at high resolution to assess processes in surface and deep waters. Recurrent facies stacking patterns (SP) and their associations record periods of bottom current activity coupled with surface changes in trophic level. Climate changes appear to have been influential on deep circulation dynamics. Under greenhouse conditions, vigorous bottom currents were arguably induced by warm and dense saline deep waters originated on tropical shelves in the Tethys and/or proto-Atlantic Ocean. Tractive facies postdating intermittent anoxia during OAE 1d and in the interval bracketed by MCE I and OAE 2 are indicative of feeble bottom currents, though capable of disrupting stratification and replenish deep water with oxygen. The major warming at the onset of OAE 2 might have enhanced the formation of warm salty waters, possibly producing local hiatuses at the base of the Bonarelli Level and winnowing at the seafloor. Hiatuses detected at the top of the Bonarelli Level possibly resulted from most effective bottom currents during the early Turonian thermal maximum. Times of minimal sediment displacement correlate with cooler climatic conditions and testify a different mechanism of deep water formation, as further suggested by a color change to reddish lithologies of the post-OAE 1d and post-OAE 2 intervals.

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Mid-Cretaceous oceanic anoxic events in the Pacific Ocean revealed by carbon-isotope stratigraphy of the Calera Limestone, California, USA

Cited by 41 publications

References 39 publications

Biogeochemical sulfur cycling during Cretaceous oceanic anoxic events: A comparison of OAE1a and OAE2

Biogeochemical sulfur cycling during Cretaceous oceanic anoxic events: A comparison of OAE1a and OAE2

The Cogollo Group and the oceanic anoxic events 1a and 1b, Maracaibo basin, Venezuela

Onset and demise of Cretaceous oceanic anoxic events: The coupling of surface and bottom oceanic processes in two pelagic basins of the western Tethys

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