Context, naming, and formal designation of the Cretaceous Hell Creek Formation lectostratotype, Garfield County, Montana

Hartman, Joseph C.; Butler, Raymond; Weiler, Matthew W.; Schumaker, Karew K.

doi:10.1130/2014.2503(02)

Cited by 17 publications

(19 citation statements)

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“…formational boundary is roughly coincident with the KPB. These formations are correlative with other fluvial deposits within the Williston basin including the Hell Creek Formation and Ludlow Member of the Fort Union Formation in North Dakota and South Dakota and the Frenchman and Ravenscrag Formations in Canada [ Hartman , ; Hartman et al ., ]. Rock types included in these deposits include siltstone, mudstone, fine sandstone, and lignite, representative of flood plain deposition, and coarser sandstones, representative of channel deposition.…”

Section: Regional Geologymentioning

confidence: 99%

Importance of titanohematite in detrital remanent magnetizations of strata spanning the Cretaceous‐Paleogene boundary, Hell Creek region, Montana

Sprain

Feinberg

Renne

et al. 2016

Geochem Geophys Geosyst

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Intermediate composition titanohematite, Fe 2-y Ti y O 3 with 0.5 y 0.7, is seldom the focus of paleomagnetic study and is commonly believed to be rare in nature. While largely overlooked in magnetostratigraphic studies, intermediate titanohematite has been identified as the dominant ferrimagnetic mineral in an array of Late Mesozoic and early Cenozoic Laramide clastic deposits throughout the central United States. Intermediate titanohematite is ferrimagnetic and has similar magnetic properties to titanomagnetite, except its unique self-reversing property. Due to these similarities, and with detrital remanent magnetizations masking its self-reversing nature, intermediate titanohematite is often misidentified in sedimentary deposits. Past studies relied upon nonmagnetic techniques including X-ray diffraction and electron microprobe analysis. While these techniques can identify the presence of intermediate titanohematite, they fail to test whether the mineral is the primary recorder. To facilitate the identification of intermediate titanohematite in sedimentary deposits, we characterize this mineral using low-temperature magnetometry and high-temperature susceptibility experiments, and present a new identification technique based on titanohematite's self-reversing property, for sediments that span the Cretaceous-Paleogene boundary (Hell Creek region, Montana). Results from the self-reversal test indicate that the majority of remanence is held by minerals that become magnetized parallel to an applied field, but that intermediate, selfreversing titanohematite (y 5 0.53-0.63) is an important ancillary carrier of remanence. While earlier literature suggests that intermediate titanohematite is rare in nature, reanalysis using specialized rock magnetic techniques may reveal that it is more abundant in the rock record, particularly within depositional basins adjacent to calc-alkaline volcanics, than previously thought.

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Section: Regional Geologymentioning

confidence: 99%

Importance of titanohematite in detrital remanent magnetizations of strata spanning the Cretaceous‐Paleogene boundary, Hell Creek region, Montana

Sprain

Feinberg

Renne

et al. 2016

Geochem Geophys Geosyst

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“…Within the Hell Creek region, the Hell Creek Formation and the Tullock Member of the Fort Union Formation bracket the Cretaceous‐Paleogene boundary (KPB). Correlative units in the eastern and northern portions of the Williston basin include the Hell Creek Formation and Ludlow Member of the Fort Union Formation in North and South Dakota, and the Frenchman and Ravenscrag Formations in Canada [ Hartman , ; Hartman et al ., ]. These units formed as prograding wedges of clastic Laramide sediment that were deposited during the retreat of the Bearpaw Sea [ Fastovsky , ].…”

Section: Geology Of the Williston Basinmentioning

confidence: 99%

“…Due to an increased hydraulic flux and rise in water table around KPB time, there is a prevalence of variegated beds and organic deposits in the Fort Union Formation compared to the Hell Creek. The formational contact is thus defined at the base of the first laterally persistent lignite, above the highest in situ nonavian dinosaur remains [ Calvert et al ., ; Brown , ; Archibald et al ., ; Hartman et al ., ; Moore et al ., ]. Recent work has shown that the formational contact (as defined above) throughout the Williston basin, including the Hell Creek region, is diachronous, ranging over several tens of ka [ Sprain et al ., ].…”

Section: Geology Of the Williston Basinmentioning

confidence: 99%

“…In this region the KPB is variably defined, but typically characterized by the highest appearance of in situ nonavian dinosaur fossils [ Clemens and Hartman , ; Hartman et al ., ; Moore et al ., ] or the lowest occurrence of unreworked Paleocene pollen [ Bercovici et al ., ], and associated with a −1.5 to −2.8‰ carbon isotope anomaly [ Arens and Jahren , ; Arens et al ., ] and the impact claystone and iridium anomaly, which frequently contains shocked quartz and glass spherules [ Bohor et al ., ; Bohor , ; Smit , ]. The KPB is not always coincident with the Hell Creek/Fort Union contact.…”

Section: Geology Of the Williston Basinmentioning

confidence: 99%

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Chemical and Pb isotope composition of phenocrysts from bentonites constrains the chronostratigraphy around the Cretaceous‐Paleogene boundary in the Hell Creek region, Montana

Ickert

Mulcahy

Sprain

et al. 2015

Geochem Geophys Geosyst

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An excellent record of environmental and paleobiological change around the CretaceousPaleogene boundary is preserved in the Hell Creek and Fort Union Formations in the western Williston Basin of northeastern Montana. These records are present in fluvial deposits whose lateral discontinuity hampers long-distance correlation. Geochronology has been focused on bentonite beds that are often present in lignites. To better identify unique bentonites for correlation across the region, the chemical and Pb isotopic composition of feldspar and titanite has been measured on 46 samples. Many of these samples have been dated by 40 Ar/ 39 Ar. The combination of chemical and isotopic compositions of phenocrysts has enabled the identification of several unique bentonite beds. In particular, three horizons located at and above the Cretaceous-Paleogene boundary can now be traced-based on their unique compositions-across the region, clarifying previously ambiguous stratigraphic relationships. Other bentonites show unusual features, such as Pb isotope variations consistent with magma mixing or assimilation, that will make them easy to recognize in future studies. This technique is limited in some cases by more than one bentonite having compositions that cannot be distinguished, or bentonites with abundant xenocrysts. The Pb isotopes are consistent with a derivation from the Bitterroot Batholith, whose age range overlaps that of the tephra. These data provide an improved stratigraphic framework for the Hell Creek region and provide a basis for more focused tephrostratigraphic work, and more generally demonstrate that the combination of mineral chemistry and Pb isotope compositions is an effective technique for tephra correlation.

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“…This would have the effect of making a unit appear older or younger than it really is. For example, the mudstone immediately beneath the Apex sandstone (basal unit of the upper Hell Creek Formation, Montana; Hartman et al, 2014) is of normal polarity, assigned to C30n, whereas the mudstone immediately above the Apex Sandstone is of reversed polarity (assigned to C29r; LeCain et al, 2014). The C30n-C29r boundary is therefore drawn within the Apex Sandstone, whereas it is more likely that it occurs at the hiatus at the base of the sandstone.…”

Section: Magnetostratigraphymentioning

confidence: 99%

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Supplemental Information 2: Recalibration Sheet

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Interbasinal stratigraphic correlation provides the foundation for all consequent continental-scale geological and paleontological analyses. Correlation requires synthesis of lithostratigraphic, biostratigraphic and geochronologic data, and must be periodically updated to accord with advances in dating techniques, changing standards for radiometric dates, new stratigraphic concepts, hypotheses, fossil specimens, and field data. Outdated or incorrect correlation exposes geological and paleontological analyses to potential error. The current work presents a high-resolution stratigraphic chart for terrestrial Late Cretaceous units of North America, combining published chronostratigraphic, lithostratigraphic, and biostratigraphic data. 40 Ar / 39 Ar radiometric dates are newly recalibrated to both current standard and decay constant pairings. Revisions to the stratigraphic placement of most units are slight, but important changes are made to the proposed correlations of the Aguja and Javelina Formations, Texas, and recalibration corrections in particular affect the relative age positions of the Belly River Group,

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Context, naming, and formal designation of the Cretaceous Hell Creek Formation lectostratotype, Garfield County, Montana

Cited by 17 publications

References 0 publications

Importance of titanohematite in detrital remanent magnetizations of strata spanning the Cretaceous‐Paleogene boundary, Hell Creek region, Montana

Importance of titanohematite in detrital remanent magnetizations of strata spanning the Cretaceous‐Paleogene boundary, Hell Creek region, Montana

Chemical and Pb isotope composition of phenocrysts from bentonites constrains the chronostratigraphy around the Cretaceous‐Paleogene boundary in the Hell Creek region, Montana

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