Integrated paleoenvironmental analysis of the Niobrara Formation: Cretaceous Western Interior Seaway, northern Colorado

Gama, Rui O.B.P. Da; Lutz, Brendan P.; Desjardins, Patricio R.; Thompson, Mike; Prince, Iain; Espejo, Irene

doi:10.1016/j.palaeo.2014.05.005

Cited by 24 publications

(11 citation statements)

References 50 publications

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“…This has also been well-documented on the western margin of the WIS (e.g., Tibert et al, 2003;Leckie, 2004, 2013). Changes in salinity, therefore, would be expected to result in increased %benthics (e.g., Caldwell, et al, 1993;Nielsen et al, 2008;Schröder-Adams et al, 2014;Da Gama et al, 2014), and therefore could not be mistaken for anoxia in our data.…”

Section: Benthic Foraminifera As Seafloor Oxygen Proxymentioning

confidence: 63%

“…Macro and microfossil paleobiogeography from the WIS and adjacent open ocean sites suggest two water masses entered the sea during late transgression ( Figure 3): a warm, normal marine Tethyan water mass from the south and a cool, brackish Boreal water mass from the north. Quasi-estuarine circulation, driven by density differences between these watermasses and freshwater input on the margins of the seaway, caused these waters to form a counterclockwise gyre, with warm Tethyan waters to the east and cool Boreal waters to the west (Kent, 1968;Eicher and Worstell, 1970;Frush and Eicher, 1975;Kauffman, 1984;Pratt and Threlkeld, 1984;Eicher and Diner, 1985;Hay et al, 1993;Slingerland et al, 1996;Leckie et al, 1998;Elderbak et al, 2014;Da Gama et al, 2014;Lockshin et al, 2017). These two water masses likely mixed, through a process called caballing, to form a third, denser watermass that would have sunk and flowed out of the sea as a bottom current (Fisher, 1991;Hay et al, 1993;Elderbak and Leckie, 2016).…”

Section: Climate and Circulationmentioning

confidence: 99%

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The Late Cretaceous Western Interior Seaway as a model for oxygenation change in epicontinental restricted basins

Lowery

Leckie

Bryant

et al. 2018

Earth-Science Reviews

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Deoxygenation is a critical problem facing the ocean as the world warms, and has the potential to effect coastal upwelling zones, shelf areas influenced by high runoff and nutrification, and restricted and semi-restricted basins. The mechanisms that drive deoxygenation in these diverse environments are still not fully understood, in part because the modern record of redox change is short and anoxia is still relatively rare in the modern ocean. Here, we address this problem of scale by studying deoxygenation in the geologic past. We summarize decades of individual studies of benthic foraminifera to generate a record of bottom water oxygen change in the Cretaceous Western Interior Sea (WIS) of North America over ~13 myr (Cenomanian-Campanian), spanning two major sea level cycles. The WIS was prone to major changes in dissolved oxygen content throughout its long history, sometimes directly antiphase to trends in the global ocean. Presented as maps, our data show that bottom water oxygen within the WIS was controlled by a combination of water mass source and mixing moderated by sea level and basin restriction. Areas flooded by cool Boreal (northern-sourced) waters in the northern and western parts of the seaway were better oxygenated than the eastern and southern portions of the seaway, which were flooded by warmer Tethyan (southern-sourced) waters. Beyond east-west differences explained by water mass, the entire seaway was better oxygenated during periods of transgression, and more poorly oxygenated to anoxic during periods of peak transgression/highstand and regression. We suggest that this pattern was due to the formation and downwelling of Western Interior Intermediate Water by the mixing of Tethyan and Boreal waters. During transgressions, an increasing volume of these watermasses entered the 3 seaway, mixed, and downwelled well-oxygenated surface water to the seafloor. During late transgression/highstand, partial stratification and the encroachment of low oxygen waters from the open ocean caused dissolved oxygen levels to drop at the seafloor, but continued downwelling prevented anoxia. During the subsequent regression, a decline in the volume of outside watermasses entering the seaway caused a reduction in mixing and weakened downwelling which led to stratification and seafloor anoxia. As a model for other semi-restricted basins, the trends observed in the WIS show that local changes in relative sea level, mixing, and circulation are critical in controlling oceanic deoxygenation in these environments, in clear contrast to continental margins impinged by oxygen minimum zones, like the contemporaneous Demerara Rise in the southern Caribbean. Although the WIS is larger than most semi-restricted basins, it is characterized by quasi-estuarine circulation driving the interaction of normal marine and brackish watermasses, and thus serves a model for similar shallow epicontinental basins of any size. Understanding how these processes vary in different environments is key to predicting susceptibility of regional water ...

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Section: Benthic Foraminifera As Seafloor Oxygen Proxymentioning

confidence: 63%

Section: Climate and Circulationmentioning

confidence: 99%

The Late Cretaceous Western Interior Seaway as a model for oxygenation change in epicontinental restricted basins

Lowery

Leckie

Bryant

et al. 2018

Earth-Science Reviews

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“…A significant freshwater contribution to water masses is supported by fossil‐ and biophosphate‐derived oxygen isotope evidence from throughout the WIS, as well as low diversity of surface dwelling organisms [ Tourtelot and Rye , ; Hattin , ; Wright , ; Fisher and Arthur , ; Coulson et al , ]. Continental paleoprecipitation estimates suggest that the increased freshwater influence may be derived from elevated runoff from the Sevier Highlands [ Retallack , ], while shifts to more Boreal faunal communities support dominance of fresher, northern sourced surface water [ Da Gama et al , ]. Although the freshwater influence would aid in development of stratification, previous studies from the WIS suggest that ventilation events occurred even within TOC‐rich units [ Sageman , ; Sageman and Bina , ], which is consistent with variability in TOC and redox indicators in the Niobrara, specifically from 45 to 51 m in the Portland core.…”

Section: Discussionmentioning

confidence: 99%

“…Continental paleoprecipitation estimates suggest that the increased freshwater influence may be derived from elevated runoff from the Sevier Highlands [Retallack, 2009], while shifts to more Boreal faunal communities support dominance of fresher, northern sourced surface water [Da Gama et al, 2014].…”

Section: Stratificationmentioning

confidence: 99%

Redox‐controlled preservation of organic matter during “OAE 3” within the Western Interior Seaway

et al. 2015

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During the Cretaceous, widespread black shale deposition occurred during a series of Oceanic Anoxic Events (OAEs). Multiple processes are known to control the deposition of marine black shales, including changes in primary productivity, organic matter preservation, and dilution. OAEs offer an opportunity to evaluate the relative roles of these forcing factors. The youngest of these events-the Coniacian to Santonian OAE 3-resulted in a prolonged organic carbon burial event in shallow and restricted marine environments including the Western Interior Seaway. New high-resolution isotope, organic, and trace metal records from the latest Turonian to early Santonian Niobrara Formation are used to characterize the amount and composition of organic matter preserved, as well as the geochemical conditions under which it accumulated. Redox sensitive metals (Mo, Mn, and Re) indicate a gradual drawdown of oxygen leading into the abrupt onset of organic carbon-rich (up to 8%) deposition. High Hydrogen Indices (HI) and organic carbon to total nitrogen ratios (C:N) demonstrate that the elemental composition of preserved marine organic matter is distinct under different redox conditions. Local changes in δ 13 C indicate that redox-controlled early diagenesis can also significantly alter δ 13 C org records. These results demonstrate that the development of anoxia is of primary importance in triggering the prolonged carbon burial in the Niobrara Formation. Sea level reconstructions, δ 18 O results, and Mo/total organic carbon ratios suggest that stratification and enhanced bottom water restriction caused the drawdown of bottom water oxygen. Increased nutrients from benthic regeneration and/or continental runoff may have sustained primary productivity.

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“…These conditions did not affect calcareous microfossils as they have been recovered from the same stratigraphic interval in the whole Western Interior Basin (e.g. McNeil and Caldwell, 1981;Nielsen et al, 2003;Diaz and Velez, in press;Da Gama et al, 2014;Lowery et al, 2016). The distribution of foraminiferal assemblages throughout the basin is closely linked to the surface circulation of the seaway during the Late Cretaceous (Caldwell et al, 1978).…”

Section: Discussionmentioning

confidence: 77%

Late Cretaceous radiolarians from a bentonite-rich interval at the base of the Niobrara Formation, southwestern Saskatchewan, Canada: biostratigraphic and paleoenvironmental implications

Diaz

Vélez

2018

Can. J. Earth Sci.

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A radiolarian assemblage containing 11 species of both nasellarians and spumellarians was recovered from the Upper Cretaceous Niobrara Formation in southwestern Saskatchewan, Canada. This assemblage represents the first report of Coniacian radiolarians in the entire Western Interior Basin and one of the few reports for the Upper Cretaceous in North America. The presence of radiolarians and the partial disappearance of foraminifera in the only bentonitic interval in this formation suggest that high silica concentrations supplied by volcanic events favored ecological conditions for radiolarians to thrive and or enhanced their preservation before and after deposition. Correlation of this assemblage with other Upper Cretaceous radiolarian assemblages in North America shows a close affinity with the microfauna recovered in the Sverdrup Basin (Canadian Arctic).

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Integrated paleoenvironmental analysis of the Niobrara Formation: Cretaceous Western Interior Seaway, northern Colorado

Cited by 24 publications

References 50 publications

The Late Cretaceous Western Interior Seaway as a model for oxygenation change in epicontinental restricted basins

The Late Cretaceous Western Interior Seaway as a model for oxygenation change in epicontinental restricted basins

Redox‐controlled preservation of organic matter during “OAE 3” within the Western Interior Seaway

Late Cretaceous radiolarians from a bentonite-rich interval at the base of the Niobrara Formation, southwestern Saskatchewan, Canada: biostratigraphic and paleoenvironmental implications

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