Late Cretaceous paleobiogeography of Braarudosphaera bigelowii

Fonseca, Maria de Lurdes; Scotese, Christopher R.; Cachão, Mário

doi:10.1016/j.marmicro.2019.03.010

Cited by 4 publications

(2 citation statements)

References 204 publications

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“…Three nanoplanktonic species analysed by Dean (1988) have near‐shore affinities. B. bigelowii is found in neritic environments that are less than 200 m (de Lurdes Fonseca et al, 2019). Helicopontosphaera (Buky & Percival, 1971) and Spenolithus (Perch‐Nielsen, 1985) more frequently occur in near‐shore than open marine environments.…”

Section: Resultsmentioning

confidence: 99%

Alluvial fan and fan delta facies architecture recording initial marine flooding in the Mio‐Pliocene syn‐rift sequence of the Fish Creek‐Vallecito Basin, southern California

2023

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The timing and character of the initial marine flooding of extensional basins has implications for their tectonic history. Yet, the recognition of such flooding is difficult along rift basin margins due to the dominance of coarse-grained systems and the lack of marine fauna. This study conducts detailed facies and stratigraphic analysis of a Mio-Pliocene alluvial fan and fan-delta succession in the Fish Creek Vallecito Basin in southern California. Our goal is to characterize the marine flooding surface, determine the paleogeographic position of the shoreline and estimate the magnitude of relative base-level rise that occurred during the marine incursion associated with the opening of the Gulf of California. Our results show that the flooding of the Elephant Trees alluvial fans is often marked by an abrupt lithologic and facies change from meter-scale boulder-rich subaerial debrites (proximal alluvial fan facies association) to centimetre-scale granulerich subaqueous debrites, ripple-laminated sandstones and mudstones (prodelta facies association). By delineating the zone of transition between the subaerial and subaqueous facies, we place the initial flooding paleo-shoreline 4 km up the alluvial fan's paleo-depositional slope. Considering alluvial fan slope gradients between 1° and 5°, this 4 km transgression would require an estimated 70-350 m of water depth during the initial marine incursion. Interfingering of fan-delta deposits with subaqueous marine and planktonic-rich evaporites suggests that the basin was below sea-level after, and perhaps even before, the marine flooding.Subaerial subsea-level basins exist in Death Valley and the Salton Trough today within similar extensional and transtentional tectonic regimes. This subaerial subsea-level interpretation might explain the high magnitude and abrupt relative base-level rise recorded by the facies transitions in the Fish Creek Vallecito Basin. These results suggest that the Fish Creek Vallecito Basin underwent significant extension during its early and nonmarine depositional phase, allowing it to reach subsea-level elevations. The tectonic history of the Fish Creek Vallecito Basin maybe similar to other extensional basins where rapid subsidence allows 1620 | EAGE

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Section: Resultsmentioning

confidence: 99%

Alluvial fan and fan delta facies architecture recording initial marine flooding in the Mio‐Pliocene syn‐rift sequence of the Fish Creek‐Vallecito Basin, southern California

2023

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“…(iii) Similar to the modern ocean (Zehr, 2011), diazotrophs could have formed symbioses with other phytoplankton such as dinoflagellates and haptophytes. Haptophytespecific endosymbiotic diazotrophs emerged before 90 Ma (based on molecular clocks; Cornejo-Castillo et al, 2016) and potentially as early as 110 Ma (based on the fossil record of their haptophyte host, Braarudosphaera bigelowii; Fonseca et al, 2019). We speculate that increased burial flux due to emerging algae-diazotroph symbioses could have shaped carbon and nitrogen cycle excursions over the last 100 million years.…”

Section: Implications For Ocean Anoxiamentioning

confidence: 92%

Linking diatom-diazotroph symbioses to nitrogen cycle perturbations and deep-water anoxia: Insights from Mediterranean sapropel events

Elling

Hemingway

Kharbush

et al. 2021

Earth and Planetary Science Letters

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compound-specific δ 13 C diatom-diazotroph symbioses N 2 -fixation Mediterranean sapropels Elevated organic matter (OM) export flux promotes marine anoxia, thus increasing carbon sequestration efficiency and decreasing atmospheric carbon dioxide levels. However, the mechanisms that trigger and sustain anoxic events-particularly those associated with nutrient-poor, oligotrophic surface watersremain poorly constrained. Mediterranean Sea sapropels are well-preserved sediments deposited during episodic anoxic events throughout the Plio-Pleistocene; as such, they may provide unique insight into the biogeochemical and ecological drivers of-and responses to-marine anoxia. Using biomarker distributions, we demonstrate that anaerobic ammonium oxidizing (anammox) bacteria and diazotrophic endosymbionts of mat-and/or raft-forming diatoms were both abundant during sapropel events, particularly in the Ionian and Libyan seas. In these sapropels, the carbon isotope compositions of anammox biomarkers directly capture progressive 13 C-depletion in deep-water dissolved inorganic carbon, indicating sustained carbon sequestration. To explain these observations, we propose a reinforcing feedback whereby initial nutrient and/or circulation perturbations promote fixed nitrogen loss via intensified anammox and heterotrophic denitrification, which in turn favors proliferation of rapidly sinking diatom-diazotroph symbiotic consortia, increases OM burial flux, and sustains anoxia. This mechanism resolves the long-standing conundrum that small and buoyant diazotrophs are apparently associated with high OM export during periods of marine anoxia and oligotrophy.

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The response of calcareous plankton to the Sapropel S1 interval in North Ionian Sea

Cascella

Bonomo

Lirer

et al. 2021

Global and Planetary Change

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Late Cretaceous paleobiogeography of Braarudosphaera bigelowii

Cited by 4 publications

References 204 publications

Alluvial fan and fan delta facies architecture recording initial marine flooding in the Mio‐Pliocene syn‐rift sequence of the Fish Creek‐Vallecito Basin, southern California

Alluvial fan and fan delta facies architecture recording initial marine flooding in the Mio‐Pliocene syn‐rift sequence of the Fish Creek‐Vallecito Basin, southern California

Linking diatom-diazotroph symbioses to nitrogen cycle perturbations and deep-water anoxia: Insights from Mediterranean sapropel events

The response of calcareous plankton to the Sapropel S1 interval in North Ionian Sea

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