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Journal Article

A new cheilostome bryozoan from a dinosaur site in the Upper Cretaceous (Campanian) Judith River Formation of Montana Available to Purchase

Paul D. Taylor, Raymond R. Rogers
Published: 01 September 2021
Journal of Paleontology (2021) 95 (5): 965–973.
DOI: https://doi.org/10.1017/jpa.2021.34
... cheilostome bryozoan, Conopeum flumineum n. sp., based on well-preserved material from the Campanian Judith River Formation of the Upper Missouri River Breaks National Monument in north-central Montana. The new species shows strong morphological similarities with Conopeum seurati , a Recent species...
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View PDF for article title, A new cheilostome bryozoan from a dinosaur site in the <span class="search-highlight">Upper</span> Cretaceous (Campanian) Judith <span class="search-highlight">River</span> Formation of Montana
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Add to Citation Manager for A new cheilostome bryozoan from a dinosaur site in the <span class="search-highlight">Upper</span> Cretaceous (Campanian) Judith <span class="search-highlight">River</span> Formation of Montana
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Map of the study area, showing localities (black dots) where stratigraphic columns and fossil occurrences were recorded in the Judith River Formation, Upper Missouri River Breaks National Monument (gray), Montana, USA (Winifred is a small town near the study area).

Map of the study area, showing localities (black dots) where stratigraphic ... Available to Purchase

Published: 05 September 2022
Figure 1. Map of the study area, showing localities (black dots) where stratigraphic columns and fossil occurrences were recorded in the Judith River Formation, Upper Missouri River Breaks National Monument (gray), Montana, USA (Winifred is a small town near the study area).
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Judith River Formation study area. A, Map of north-central Montana showing boundaries of Upper Missouri River Breaks National Monument (UMRBNM; gray). Dotted box delimits region that includes the Judith River Formation type area. B, Satellite image of Judith River Formation type area along drainage of Missouri River in UMRBNM. Locations of three new reference sections (92-JRT-15, 91-JRT-8, 91-JRT-12) are indicated. Modified from Google Earth.

Judith River Formation study area. A , Map of north-central Montana showin... Available to Purchase

Published: 01 January 2016
Figure 1. Judith River Formation study area. A , Map of north-central Montana showing boundaries of Upper Missouri River Breaks National Monument (UMRBNM; gray). Dotted box delimits region that includes the Judith River Formation type area. B , Satellite image of Judith River Formation type
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Generalized outcrop belt of the Judith River Formation (JRF) in Montana and the Belly River Group (BRG) in the plains of Alberta and Saskatchewan, Canada. Upper portions of the Two Medicine Formation (TMF) represent the updip equivalent of the Judith River Formation in northwestern Montana. Focal areas include the expansive outcrops along the Missouri River in the Upper Missouri River Breaks National Monument (UMRBNM), exposures in the Milk River drainage in northern Montana (KC—Kennedy Coulee) and southeastern Alberta (Of—Onefour area), and exposures in the Red Deer River valley in Dinosaur Provincial Park (DPP). Figure is modified from Eberth and Hamblin (1993).

Generalized outcrop belt of the Judith River Formation (JRF) in Montana and... Available to Purchase

Published: 28 July 2023
Montana. Focal areas include the expansive outcrops along the Missouri River in the Upper Missouri River Breaks National Monument (UMRBNM), exposures in the Milk River drainage in northern Montana (KC—Kennedy Coulee) and southeastern Alberta (Of—Onefour area), and exposures in the Red Deer River valley
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Igloo occurrences in Judith River Formation, Montana, USA. A: General location of sites and legend. B: Age and lithostratigraphy of Judith River Formation in study area (region delimited in C), with positions of dated bentonite beds. Igloos were recovered from the terrestrial Coal Ridge Member. C: Google Earth™ image of portion of Upper Missouri River Breaks National Monument with locations of igloo sites and dated bentonite beds.

Igloo occurrences in Judith River Formation, Montana, USA. A: General locat... Available to Purchase

Published: 01 March 2018
Member. C: Google Earth™ image of portion of Upper Missouri River Breaks National Monument with locations of igloo sites and dated bentonite beds.
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Age probability density plots for single-crystal sanidine 40Ar/39Ar age determinations from bentonite beds ST1-03, PPF1-03, and WHB1-11 (see figs. 3, 10) sampled from the type area of the Judith River Formation in north-central Montana (Upper Missouri River Breaks National Monument). Weighted mean ages of the three populations are indicated, with errors reported at 1σ.

Age probability density plots for single-crystal sanidine 40 Ar/ 39 Ar age... Available to Purchase

Published: 01 January 2016
Figure 17. Age probability density plots for single-crystal sanidine 40 Ar/ 39 Ar age determinations from bentonite beds ST1-03, PPF1-03, and WHB1-11 (see figs. 3 , 10 ) sampled from the type area of the Judith River Formation in north-central Montana (Upper Missouri River Breaks National
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Figure 1. Field areas. A) Map of Upper Cretaceous units in northwestern and north-central Montana showing locations of Two Medicine Formation (Inset B) and Judith River Formation (Inset C) study areas. B) The Landslide Butte field area (Rogers, 1990), a localized pocket of badlands that includes exposures of the uppermost Two Medicine Formation and overlying Bearpaw Formation. C) Part of the Upper Missouri River Breaks National Monument, a vast region of badland exposures that includes the type area of the Judith River Formation. Inset images modified from Google Earth.

Figure 1. Field areas. A) Map of Upper Cretaceous units in northwestern and... Available to Purchase

Published: 01 January 2010
exposures of the uppermost Two Medicine Formation and overlying Bearpaw Formation. C) Part of the Upper Missouri River Breaks National Monument, a vast region of badland exposures that includes the type area of the Judith River Formation. Inset images modified from Google Earth.
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Generalized outcrop belt of the Two Medicine Formation (TMF; green) in northwestern Montana, USA, the Judith River Formation (JRF) in central Montana, and the Belly River Group (BRG) in the plains of Alberta and Saskatchewan, Canada. Middle and upper portions of the Two Medicine Formation correlate with terrestrial and shallow-marine facies of the Judith River Formation and Belly River Group. Figure is modified from Eberth and Hamblin (1993) and Rogers et al. (2023). KC—Kennedy Coulee, north-central Montana; UMRBNM—Upper Missouri River Breaks National Monument, north-central Montana; Of—Onefour area, southeastern Alberta; DPP—Dinosaur Provincial Park, southeastern Alberta.

Generalized outcrop belt of the Two Medicine Formation (TMF; green) in nort... Available to Purchase

Published: 17 July 2024
Formation correlate with terrestrial and shallow-marine facies of the Judith River Formation and Belly River Group. Figure is modified from Eberth and Hamblin (1993) and Rogers et al. (2023) . KC—Kennedy Coulee, north-central Montana; UMRBNM—Upper Missouri River Breaks National Monument, north-central
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Conopeum flumineum n. sp. from the Campanian Judith River Formation of Upper Missouri River Breaks National Monument, Montana, USA. (1–3) Holotype, USNM PAL 771789; (1) general view of the colony fragment with irregularly arranged zooids (scale bar = 500 μm); (2) detail, including intramural bud indicated by an arrow (scale bar = 200 μm); (3) kenozooid (left) and autozooid (right) with cryptocystal groove arrowed (scale bar = 100 μm). (4) Paratype, USNM PAL 771790; broken edge of fragment (probably upside down with distal at the bottom) showing apparent pore chamber (arrow) and small kenozooid (center) (scale bar = 200 μm).

Conopeum flumineum n. sp. from the Campanian Judith River Formation of Upp... Available to Purchase

Published: 01 September 2021
Figure 2. Conopeum flumineum n. sp. from the Campanian Judith River Formation of Upper Missouri River Breaks National Monument, Montana, USA. ( 1–3 ) Holotype, USNM PAL 771789; ( 1 ) general view of the colony fragment with irregularly arranged zooids (scale bar = 500 μm); ( 2 ) detail
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Stratigraphic model of Rogers (1995, 1998) and Rogers et al. (2016), updated with three new ages from Ramezani et al. (2022). In this reconstruction, the mid-Judith discontinuity, which parallels the Eagle/Milk River shoulder, marks the boundary between a low accommodation systems tract (LAST) and a high accommodation systems tract (HAST) in the terrestrial record of the Judith River Formation. The discontinuity, which can be identified in surface exposures and well logs, represents an expansion surface that formed in response to a pulse of added accommodation in the basin. The Parkman Sandstone and McClelland Ferry Members accumulated during the R8 Claggett regressive phase. The Coal Ridge and Woodhawk Members accumulated during the subsequent T9 Bearpaw transgressive phase. KC—Kennedy Coulee, Upper Missouri River Breaks National Monument (UMRBNM).

Stratigraphic model of Rogers (1995 , 1998 ) and Rogers et al. (2016) , ... Available to Purchase

Published: 28 July 2023
. The Parkman Sandstone and McClelland Ferry Members accumulated during the R8 Claggett regressive phase. The Coal Ridge and Woodhawk Members accumulated during the subsequent T9 Bearpaw transgressive phase. KC—Kennedy Coulee, Upper Missouri River Breaks National Monument (UMRBNM).
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Judith River Formation exposures in the type area in the Upper Missouri River Breaks National Monument. (A) View of mid-Judith discontinuity (thick dashed line) marking contact between McClelland Ferry Member (MFM) and Coal Ridge Member (CRM) at Judith River Formation reference section in vicinity of Stafford–McClelland Ferry (Rogers et al., 2016). Here, an entire section of the Judith River Formation is exposed. Thin dashed lines mark approximate contacts between McClelland Ferry Member, Parkman Sandstone Member (PSM), and Claggett Formation (CF). (B) View of mid-Judith discontinuity (thick dashed line) embedded between McClelland Ferry Member and Coal Ridge Member ~30 km downstream from locality in A. Here, the Coal Ridge Member is capped by shallow-marine sandstones of the Woodhawk Member (WM), which in turn is capped by marine shales of the Bearpaw Formation (BF). Unit contacts are marked by thin dashed lines.

Judith River Formation exposures in the type area in the Upper Missouri Riv... Available to Purchase

Published: 28 July 2023
Figure 6. Judith River Formation exposures in the type area in the Upper Missouri River Breaks National Monument. (A) View of mid-Judith discontinuity (thick dashed line) marking contact between McClelland Ferry Member (MFM) and Coal Ridge Member (CRM) at Judith River Formation reference section
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Location and stratigraphy of the locality (site UC-8315) containing Conopeum flumineum n. sp. in the Campanian Judith River Formation, Montana, USA. (1) Regional setting in relation to Campanian shoreline of Western Interior Seaway (WIS). Gray-shaded area represents approximate distribution of terrestrial landscapes in the Western Interior of North America during the Campanian, west of the WIS (based on Blakey, 2013 and Slattery et al., 2015, modified from Rogers et al., 2020). (2) Location of site UC-8315 in Upper Missouri River Breaks National Monument. (3) Stratigraphy of site UC-8315 in Coal Ridge Member of Judith River Formation, in close proximity to transgressing shoreline of marine Woodhawk Member. (4) Field view of site UC-8315. Dashed line marks base of the bed containing Conopeum flumineum n. sp. Arrow points to 65 cm hoe pick resting on fossil-bearing stratum.

Location and stratigraphy of the locality (site UC-8315) containing Conope... Available to Purchase

Published: 01 September 2021
distribution of terrestrial landscapes in the Western Interior of North America during the Campanian, west of the WIS (based on Blakey, 2013 and Slattery et al., 2015 , modified from Rogers et al., 2020 ). ( 2 ) Location of site UC-8315 in Upper Missouri River Breaks National Monument. ( 3 ) Stratigraphy
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Conopeum flumineum n. sp. from the Campanian Judith River Formation of Upper Missouri River Breaks National Monument, Montana, USA. (1) Paratype, USNM PAL 771791, colony fragment with autozooids ranging from ovoidal to rounded rectangular in outline shape (scale bar = 500 μm). (2) Paratype, USNM PAL 771792, colony fragment consisting of rounded rectangular zooids (scale bar = 500 μm). (3, 4) Paratype, USNM PAL 771793; (3) general view (scale bar = 500 μm); (4) detail showing almost rectangular zooids with a narrow peripheral gymnocyst and a broad cryptocyst (scale bar = 200 μm). (5) Paratype, USNM PAL 771794, damaged intramural bud (scale bar = 200 μm). (6) Paratype, USNM PAL 771795, part of a larger fragment showing multilamellar colony with areas of autozooids aligned in rows and others where their arrangement is more chaotic (scale bar = 1 mm).

Conopeum flumineum n. sp. from the Campanian Judith River Formation of Upp... Available to Purchase

Published: 01 September 2021
Figure 3. Conopeum flumineum n. sp. from the Campanian Judith River Formation of Upper Missouri River Breaks National Monument, Montana, USA. ( 1 ) Paratype, USNM PAL 771791, colony fragment with autozooids ranging from ovoidal to rounded rectangular in outline shape (scale bar = 500 μm). ( 2
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Figure 1

Judith River Formation (JRF) study area and regional stratigraphy. A, The s... Available to Purchase

Published: 21 February 2017
Figure 1 Judith River Formation (JRF) study area and regional stratigraphy. A, The six vertebrate microfossil bonebeds (VMBs) under investigation are located in the Upper Missouri River Breaks National Monument (UMRBNM; shaded gray) in north-central
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Outcrop belt of Woodhawk Member. A, Satellite image of eastern portion of Judith River Formation type area in Upper Missouri River Breaks National Monument. The Woodhawk Member can be traced on outcrop throughout this eastern portion of the type area, from the vicinity of Sturgeon Island to a few kilometers downstream of Fred Robinson Bridge. Numbered localities refer to sections in figure 10. WMS = Woodhawk Member stratotype. Modified from Google Earth. B, Downstream from Grand Island, the basal sequence (above D1; see fig. 10) of the Woodhawk Member crops out at river level, where it assumes steep exposures of gray sandstone. White line marks the contact with superjacent silty shales of the Bearpaw Formation. Arrow points to mountain sheep for scale. C, Top of the same basal sequence (above D1) of the Woodhawk Member along Montana Highway 191 immediately south of Fred Robinson Bridge, with two beds of carbonaceous mudstone (arrows) visible immediately below the contact with Bearpaw Formation.

Outcrop belt of Woodhawk Member. A , Satellite image of eastern portion of... Available to Purchase

Published: 01 January 2016
Figure 7. Outcrop belt of Woodhawk Member. A , Satellite image of eastern portion of Judith River Formation type area in Upper Missouri River Breaks National Monument. The Woodhawk Member can be traced on outcrop throughout this eastern portion of the type area, from the vicinity of Sturgeon
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Schematic cross section detailing chronostratigraphic relations among Upper Cretaceous (Campanian) units in Montana, USA (modified from Gill and Cobban, 1973; Rogers et al., 2016), calibrated with U-Pb bentonite ages reported in this article and in Ramezani et al. (2022). Significant surfaces and intervals within the Two Medicine Formation include the subaerial unconformity (SU) at the top of the Rock City Member, which correlates basinward with the Eagle shoulder, and the condensed lacustrine interval at the base of the Flag Butte Member. The approximate top of the lacustrine interval correlates downdip with the Judith River–Belly River discontinuity (JRBRD) in the Judith River Formation. Regional regressive (R7, R8) and transgressive (T8, T9) phases of deposition are from Kauffman (1977). Ages of stage boundaries are based on Cohen et al. (2013); Sant.—Santonian; Maas.—Maastrichtian. SMRF—Saint Mary River Formation; HF—Horsethief Formation; BF—Bearpaw Formation; JRF—Judith River Formation; FBM—Flag Butte Member; HCM—Hagans Crossing Member; SCM—Shields Crossing Member; RCM—Rock City Member; CRM—Coal Ridge Member; MFM—McClelland Ferry Member; JRBRD—Judith River–Belly River discontinuity; KC—Kennedy Coulee, north-central Montana; SU—subaerial unconformity; UMRBNM—Upper Missouri River Breaks National Monument; LAST—low accommodation systems tract; HAST—high accommodation systems tract.

Schematic cross section detailing chronostratigraphic relations among Upper... Available to Purchase

Published: 17 July 2024
discontinuity; KC—Kennedy Coulee, north-central Montana; SU—subaerial unconformity; UMRBNM—Upper Missouri River Breaks National Monument; LAST—low accommodation systems tract; HAST—high accommodation systems tract.
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Formal and informal lithostratigraphic units in Judith River–Belly River wedge. The ~280-m-thick Belly River section in the vicinity of Dinosaur Provincial Park (DPP), Alberta, is a composite log based on surface and subsurface data sets (modified from Eberth and Hamblin, 1993), and here the Judith River–Belly River discontinuity, dated to ca. 76.354 ± 0.057 Ma, separates the Oldman and Dinosaur Park Formations. The ~180-m-thick Judith River section in the Upper Missouri River Breaks National Monument (UMRBNM) in Montana is a surface section that includes lower and upper contacts with the Claggett and Bearpaw Formations, respectively (modified from Rogers et al., 2016). Here, the Judith River–Belly River discontinuity, dated to ca. 76.329 ± 0.035 Ma, separates the McClelland Ferry and Coal Ridge Members of the Judith River Formation. A bentonite dated to 75.219 ± 0.031 Ma rests ~90 m above the discontinuity, near the base of the Bearpaw Formation. Another bentonite dated to 78.594 ± 0.024 Ma occurs near the base of the Judith River Formation in the “marker A coal” bed identified by Goodwin and Deino (1989) in the Kennedy Coulee field area. The discontinuity can be tracked from north-central Montana into Alberta and Saskatchewan at the same general stratigraphic position above the Eagle/Milk River shoulder (see text for discussion). The basal contact of the Dinosaur Park Formation diverges from the Judith River–Belly River discontinuity in southernmost Alberta and Saskatchewan and climbs stratigraphically to the south toward the international boundary, as previously described in Eberth and Hamblin (1993) and Eberth (2005).

Formal and informal lithostratigraphic units in Judith River–Belly River we... Available to Purchase

Published: 28 July 2023
), and here the Judith River–Belly River discontinuity, dated to ca. 76.354 ± 0.057 Ma, separates the Oldman and Dinosaur Park Formations. The ~180-m-thick Judith River section in the Upper Missouri River Breaks National Monument (UMRBNM) in Montana is a surface section that includes lower and upper contacts
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Subsurface expression of the Oldman–Dinosaur Park discontinuity (ODPD) and mid-Judith discontinuity (MJD) from the vicinity of Dinosaur Provincial Park (DPP) in southeastern Alberta to the Upper Missouri River Breaks National Monument (UMRBNM) in north-central Montana (path of subsurface section A–A′ indicated on map, wells 1–25). See text for descriptions of subsurface signatures that identify each discontinuity across the region. The red line in each log indicates the inferred position of each discontinuity (solid for Oldman–Dinosaur Park discontinuity, dashed for mid-Judith discontinuity). Both discontinuities maintain a relatively consistent stratigraphic position in relation to the Eagle/Milk River shoulder (EMRS), a widely recognized marker horizon (e.g., Glombick and Mumpy, 2014). Picks of Foremost-Oldman, Oldman–Dinosaur Park, and Dinosaur Park–Bearpaw contacts are informed by Glombick (2010a, 2010b, 2011a, 2011b, 2013). Picks of the Oldman–Dinosaur Park discontinuity that coincide with picks made by Glombick (2011b) in the same logs are indicated by black asterisks. Black dashed line on map indicates where Oldman–Dinosaur Park discontinuity to the north shifts to mid-Judith discontinuity to the south. Yellow—Oldman Formation; light green—Dinosaur Park Formation; light brown—Coal Ridge Member of Judith River Formation; darker brown—McClelland Ferry and Parkman Sandstone Members of Judith River Formation; dark gray—Bearpaw Formation. Judith River reference section 91-JRT-8 is from Rogers et al. (2016). KC—Kennedy Coulee field area; Of—Onefour field area; CF—Claggett Formation; BF—Bearpaw Formation; G—gamma-ray log; D—density log; R—resistivity log; S—sonic log; SP—spontaneous potential log.

Subsurface expression of the Oldman–Dinosaur Park discontinuity (ODPD) and ... Available to Purchase

Published: 28 July 2023
Figure 7. Subsurface expression of the Oldman–Dinosaur Park discontinuity (ODPD) and mid-Judith discontinuity (MJD) from the vicinity of Dinosaur Provincial Park (DPP) in southeastern Alberta to the Upper Missouri River Breaks National Monument (UMRBNM) in north-central Montana (path
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Subsurface expression of the Oldman–Dinosaur Park discontinuity (ODPD) and mid-Judith discontinuity (MJD) from the vicinity of Dinosaur Provincial Park (DPP) in southeastern Alberta to the Upper Missouri River Breaks National Monument (UMRBNM) in north-central Montana (path of subsurface section A–A′ indicated on map, wells 1–25). See text for descriptions of subsurface signatures that identify each discontinuity across the region. The red line in each log indicates the inferred position of each discontinuity (solid for Oldman–Dinosaur Park discontinuity, dashed for mid-Judith discontinuity). Both discontinuities maintain a relatively consistent stratigraphic position in relation to the Eagle/Milk River shoulder (EMRS), a widely recognized marker horizon (e.g., Glombick and Mumpy, 2014). Picks of Foremost-Oldman, Oldman–Dinosaur Park, and Dinosaur Park–Bearpaw contacts are informed by Glombick (2010a, 2010b, 2011a, 2011b, 2013). Picks of the Oldman–Dinosaur Park discontinuity that coincide with picks made by Glombick (2011b) in the same logs are indicated by black asterisks. Black dashed line on map indicates where Oldman–Dinosaur Park discontinuity to the north shifts to mid-Judith discontinuity to the south. Yellow—Oldman Formation; light green—Dinosaur Park Formation; light brown—Coal Ridge Member of Judith River Formation; darker brown—McClelland Ferry and Parkman Sandstone Members of Judith River Formation; dark gray—Bearpaw Formation. Judith River reference section 91-JRT-8 is from Rogers et al. (2016). KC—Kennedy Coulee field area; Of—Onefour field area; CF—Claggett Formation; BF—Bearpaw Formation; G—gamma-ray log; D—density log; R—resistivity log; S—sonic log; SP—spontaneous potential log.

Subsurface expression of the Oldman–Dinosaur Park discontinuity (ODPD) and ... Available to Purchase

Published: 28 July 2023
Figure 7. Subsurface expression of the Oldman–Dinosaur Park discontinuity (ODPD) and mid-Judith discontinuity (MJD) from the vicinity of Dinosaur Provincial Park (DPP) in southeastern Alberta to the Upper Missouri River Breaks National Monument (UMRBNM) in north-central Montana (path
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Schematic cross section of Upper Cretaceous strata in Montana (modified from Gill and Cobban 1973). The Judith River Formation correlates to the west with terrestrial deposits of the middle and upper Two Medicine Formation and is bounded above and below by marine shales of the Bearpaw and Claggett Formations. Regional regressive (R7, R8, R9) and transgressive (T8, T9) phases of deposition are from Kauffman (1977). The type area of the Judith River Formation is located in the Upper Missouri River Breaks National Monument (UMRBNM). The new Woodhawk Member crops out in the eastern sector of the type area and consists of three backstepping fourth-order sequences that accumulated during the Bearpaw transgression. The mid-Judith discontinuity (MJD) correlates with the base of the Woodhawk Member and separates the new McClelland Ferry Member below from the new Coal Ridge Member above. The erosional base of the Parkman Sandstone Member of the Judith River Formation in the UMRBNM reflects an episode of forced regression (FR), capping the normal regressive (NR) deposits of the upper Claggett Formation. The downward trajectory of the Parkman Sandstone Member at the eastern edge of the diagram is based on the original facies reconstruction of Gill and Cobban (1973) but is here interpreted as tracking a basal surface of forced regression (BSFR). The sandstone-rich alluvial McClelland Ferry Member was deposited during normal regression under conditions of low positive accommodation, and the mid-Judith discontinuity is a maximum regressive surface (MRS), marking a change to the mud-rich alluvial and paralic Coal Ridge Member, a shift to significantly higher rates of sediment accumulation, and marine transgression (T) by shoreface sands of the Woodhawk Member. New 40Ar/39Ar ages presented in this report are shown in italics. One legacy 40Ar/39Ar age of 77.52 ± 0.19 Ma (sanidine) from a bentonite ∼265 m above the base of the Two Medicine Formation (Foreman et al. 2008) was recalculated to 78.02 ± 0.19 Ma. Rogers (1998) provisionally correlated the mid-Judith discontinuity with a widespread lacustrine carbonate interval (LCI) that overlies the aforementioned bentonite, ∼330 m above the base of the Two Medicine Formation. Positions of Santonian-Campanian and Campanian-Maastrichtian boundaries (Ogg and Hinnov 2012) are approximated. SGA = Sweetgrass arch, across which Campanian/Maastrichtian strata have been eroded.

Schematic cross section of Upper Cretaceous strata in Montana (modified fro... Available to Purchase

Published: 01 January 2016
of the Bearpaw and Claggett Formations. Regional regressive (R7, R8, R9) and transgressive (T8, T9) phases of deposition are from Kauffman ( 1977 ). The type area of the Judith River Formation is located in the Upper Missouri River Breaks National Monument (UMRBNM). The new Woodhawk Member crops out