The Cenomanian–Turonian Eagle Ford Group of South Texas: Insights on timing and paleoceanographic conditions from geochemistry and micropaleontologic analyses

Denne, Richard A.; Hinote, Russell E.; Breyer, John A.; Kosanke, Tobi; Lees, Jackie A.; Engelhardt-Moore, Nancy; Spaw, Joan M.; Tur, Nataliya A.

doi:10.1016/j.palaeo.2014.05.029

Cited by 110 publications

(45 citation statements)

References 33 publications

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“…Eldrett et al (2015) estimated a 1.65-million-year hiatus, based on a comparison of nannofossil distributions (Donovan et al 2012;Lowery et al 2014) with Iona-1. Ewing (2013) and Denne et al (2014) correlated and interpreted the unconformity in a regional context.…”

Section: Cenomanianàturonian Boundary (Ctb) (3978 M) (Ca 94 Ma)mentioning

confidence: 99%

Palynostratigraphy and palaeoenvironments of the Eagle Ford Group (Upper Cretaceous) at the Lozier Canyon outcrop reference section, west Texas, USA

Dodsworth¹

2015

Palynology

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This study describes the detailed palynology of the Eagle Ford Group at Lozier Canyon, its principal outcrop reference section in west Texas. Prominent marine phytoplankton assemblages are consistent with a proposed depositional setting for Lozier Canyon on a submarine platform within the Cretaceous Western Interior Seaway (KWIS) of the USA. The Lower Eagle Ford Formation (middle to upper Cenomanian) was deposited under restricted marine conditions with oxygen-deficient, probably anoxic bottom waters, as indicated by the black, organic-rich (ca. 1 to > 6% total organic carbon) shale lithology. The formation comprises two fourth-order stratigraphical sequences, each showing sedimentary evidence of increasing water depth during deposition. Palynomorph assemblages from the sequences are dominated by green algal prasinophyte phycomata in the lower parts and peridinioid dinoflagellate cysts in the upper parts. The productivity of these marine phytoplankton groups may have been stimulated by availability of ammonium (prasinophytes) and nitrite (peridinioids) from upwelling, or vertical expansion of the oxygen-minimum zone. The transition from prasinophyte-to peridinioid-dominated assemblages may reflect elevation of the photic zone to a level less regularly encroached by deeper, ammonium-enriched waters of the denitrification zone. The overlying Upper Eagle Ford Formation (upper Cenomanian to upper Turonian or Coniacian) was deposited under deeper, relatively open marine conditions, as indicated by a decrease in organic carbon content and an increase in carbonate content. This is supported by the presence of diversified dinoflagellate cyst assemblages, including inter-regional (high-to mid-latitude) marker events; in the upper Cenomanian, base and acme Cyclonephelium compactum-membraniphorum, top consistent and frequent Litosphaeridium siphoniphorum, and top Adnatosphaeridium tutulosum; in the middle to upper Turonian, range bases of Heterosphaeridium difficile and Senoniasphaera rotundata. The stratigraphical resolution offered by palynology indicates potential application to wellsite 'geosteering' of commercial shale oil and shale gas wells drilled in the Eagle Ford Group.

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Section: Cenomanianàturonian Boundary (Ctb) (3978 M) (Ca 94 Ma)mentioning

confidence: 99%

Palynostratigraphy and palaeoenvironments of the Eagle Ford Group (Upper Cretaceous) at the Lozier Canyon outcrop reference section, west Texas, USA

Dodsworth¹

2015

Palynology

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“…The bulk of the Eagle Ford Gr in the Iona-1 core was deposited below storm wave base (>100-200 m water depths) in a distal, clastic sediment starved, restricted setting (Eldrett et al, 2014). Additional background stratigraphic and sedimentologic information on the Eagle Ford Gr and adjacent sections in the Maverick Basin can be found in Pessagno (1969), Denne et al (2014), Lowery et al (2014), and references therein.…”

Section: Research Core Iona-1mentioning

confidence: 99%

“…However, this is primarily due to the fact that the majority of the limestones are affected by diagenetic cement, preventing effective liberation of foraminifera, radiolaria and other bioclasts from the rock matrix of this lithology using standard wash techniques. It is therefore difficult to ascertain whether the micropaleontological assemblage absolute abundance variations recovered using standard techniques reflect a primary environmental signal or the diagenetic overprint (see Denne et al, 2014).…”

Section: Micropalaeontological Assemblagementioning

confidence: 99%

“…In particular, high radiolaria abundances are hypothesized as being indicative of highly dynamic/upwelled and productive shallow waters (Erbacher et al, 1996). Their abundant occurrence primarily in limestone beds may be a preservation artifact, but the presence of well-preserved radiolaria, albeit in low abundances in some marl samples within the OAE-2 interval in Iona-1 suggest that this is not the case (see also Denne et al, 2014). Furthermore, the co-occurrence of abundant radiolaria and Pithonellid calcareous dinocysts in the replaced limestones point towards high productivity in unstable shallow carbonate seas (Jarvis et al, 1988;Wendler et al, 2002Wendler et al, , 2013Omaña et al, 2014;Denne et al, 2014).…”

Section: Environmental Signalsmentioning

confidence: 99%

“…Their abundant occurrence primarily in limestone beds may be a preservation artifact, but the presence of well-preserved radiolaria, albeit in low abundances in some marl samples within the OAE-2 interval in Iona-1 suggest that this is not the case (see also Denne et al, 2014). Furthermore, the co-occurrence of abundant radiolaria and Pithonellid calcareous dinocysts in the replaced limestones point towards high productivity in unstable shallow carbonate seas (Jarvis et al, 1988;Wendler et al, 2002Wendler et al, , 2013Omaña et al, 2014;Denne et al, 2014). This interpretation is consistent with abundant occurrence of Pithonellids (see Hattin, 1975;Pratt, 1981) and clay-size quartz in limestone beds of the Bridge Creek limestone at the GSSP at Pueblo, where the latter was interpreted by Diner (1989, 1991) as representing recrystallized radiolaria, and both being indicative of episodes of high productivity (productivity cycles).…”

Section: Environmental Signalsmentioning

confidence: 99%

See 2 more Smart Citations

Origin of limestone–marlstone cycles: Astronomic forcing of organic-rich sedimentary rocks from the Cenomanian to early Coniacian of the Cretaceous Western Interior Seaway, USA

Eldrett

Bergman

et al. 2015

Earth and Planetary Science Letters

117

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Sedimentary Mercury Enrichments as a Marker for Submarine Large Igneous Province Volcanism? Evidence From the Mid‐Cenomanian Event and Oceanic Anoxic Event 2 (Late Cretaceous)

Scaife

Ruhl

Dickson

et al. 2017

Geochem Geophys Geosyst

104

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Oceanic Anoxic Event 2 (OAE 2), during the Cenomanian‐Turonian transition (∼94 Ma), was the largest perturbation of the global carbon cycle in the mid‐Cretaceous and can be recognized by a positive carbon‐isotope excursion in sedimentary strata. Although OAE 2 has been linked to large‐scale volcanism, several large igneous provinces (LIPs) were active at this time (e.g., Caribbean, High Arctic, Madagascan, Ontong‐Java) and little clear evidence links OAE 2 to a specific LIP. The Mid‐Cenomanian Event (MCE, ∼96 Ma), identified by a small, 1‰ positive carbon‐isotope excursion, is often referred to as a prelude to OAE 2. However, no underlying cause has yet been demonstrated and its relationship to OAE 2 is poorly constrained. Here we report sedimentary mercury (Hg) concentration data from four sites, three from the southern margin of the Western Interior Seaway and one from Demerara Rise, in the equatorial proto‐North Atlantic Ocean. We find that, in both areas, increases in mercury concentrations and Hg/TOC ratios coincide with the MCE and the OAE 2. However, the increases found in these sites are of a lower magnitude than those found in records of many other Mesozoic events, possibly characteristic of a marine rather than atmospheric dispersal of mercury for both events. Combined, the new mercury data presented here are consistent with an initial magmatic pulse at the time of the MCE, with a second, greater pulse at the onset of OAE 2, possibly related to the emplacement of LIPs in the Pacific Ocean and/or the High Arctic.

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The Cenomanian–Turonian Eagle Ford Group of South Texas: Insights on timing and paleoceanographic conditions from geochemistry and micropaleontologic analyses

Cited by 110 publications

References 33 publications

Palynostratigraphy and palaeoenvironments of the Eagle Ford Group (Upper Cretaceous) at the Lozier Canyon outcrop reference section, west Texas, USA

Palynostratigraphy and palaeoenvironments of the Eagle Ford Group (Upper Cretaceous) at the Lozier Canyon outcrop reference section, west Texas, USA

Origin of limestone–marlstone cycles: Astronomic forcing of organic-rich sedimentary rocks from the Cenomanian to early Coniacian of the Cretaceous Western Interior Seaway, USA

Sedimentary Mercury Enrichments as a Marker for Submarine Large Igneous Province Volcanism? Evidence From the Mid‐Cenomanian Event and Oceanic Anoxic Event 2 (Late Cretaceous)

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