Geometry of Shelf Sandstone Bodies in the Shannon Sandstone of Southeastern Montana

Shurr, George W.

doi:10.2110/pec.84.34.0063

Cited by 19 publications

(6 citation statements)

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“…Examples in the Cretaceous Western Interior, U.S.A., include the Fox Hills Sandstone (Waage, 1968;Land, 1972), Ferron Sandstone (Cotter, 1975), Mosby Sandstone Member of the Belle Fourche Shale (Rice, 1984), Semilla Sandstone Member of the Mancos Shale (La Fon, 1981) and the Shannon Sandstone (Shurr, 1984). This association is identical to that reported here from the Bearpaw Formation.…”

Section: Discussionsupporting

confidence: 77%

Origin of Concretion-Hosted Shell Clusters in the Late Cretaceous Bearpaw Formation, Southern Alberta, Canada

Tsujita¹

1995

PALAIOS

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JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. SEPM Society for Sedimentary Geology is collaborating with JSTOR to digitize, preserve and extend access to PALAIOS.The widespread phenomenon of faunal clustering in concretions is examined in examples from the Late Cretaceous Bearpaw Formation of southern Alberta. Concretion-hosted shell clusters have traditionally been interpreted as biologically formed features. In contrast, sedimentologic, taphonomic and faunal evidence in the Bearpaw Formation suggests that shell clustering is inherently related to a common physical control.The clustered nature of the Bearpaw assemblages reflects the accumulation of shells in isolated storm scours. Differences in faunal composition resulted from variations in (1) the mode of scour initiation, (2) the faunal content of sea-floor sediments, and (3) the degree of shell transport experienced during storms. The formation of the isolated scours is attributed to locally augmented erosion in the vicinity of bed defects and objects exposed on the sea floor. The common restriction of fossils to concretions reflects preferred concretion growth around the shell-rich scour fills. Previously described examples of concretion-hosted shell clusters are re-interpreted in light of the scour-fill hypothesis.

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Section: Discussionsupporting

confidence: 77%

Origin of Concretion-Hosted Shell Clusters in the Late Cretaceous Bearpaw Formation, Southern Alberta, Canada

Tsujita¹

1995

PALAIOS

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“…Examples include major fluvial channel-belt deposits, such as the "third-order" cycles of the Siwalik Group in Pakistan (as demonstrated by detailed studies of the magnetostratigraphy by Johnson et al 1985). Other examples include such major depositional elements as delta complexes and alluvial fans, shelf sand-ridge fields (group III "regional lentils" of Shurr 1984), and major lobes of submarine fans (third-order "turbidite stages" of Mutti and Normark 1987). Other examples include such major depositional elements as delta complexes and alluvial fans, shelf sand-ridge fields (group III "regional lentils" of Shurr 1984), and major lobes of submarine fans (third-order "turbidite stages" of Mutti and Normark 1987).…”

Section: The Grouping Of Architectural Units In Clastic Rocks Accordimentioning

confidence: 99%

The Geology of Fluvial Deposits

Miall¹

2006

786

1,053

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“…Alternations of fine clayey/marly sediments and coarser sandy deposits in fossil shelf settings from greenhouse periods are classically ascribed to sea‐level fluctuations. In cases where sea‐level fluctuations are not the obvious cause of parasequence evolution, complex, nonlinear autocyclic forcing or variations in energy level (tides, storms) have been suggested (Shurr, 1984; Swift et al. , 1991; Bergman & Snedden, 1999; Tillman, 1999).…”

Section: Variations In the Tide On Milankovitch Time Scalesmentioning

confidence: 99%

Orbitally forced sedimentary rhythms in the stratigraphic record: is there room for tidal forcing?

Boer¹,

Trabucho‐Alexandre

2011

Sedimentology

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The imprint of orbital cycles, which result from the varying eccentricity of the Earth's orbit and changes in the orientation of its axis, have been recognised throughout the Phanerozoic rock record. Variations in insolation and their effect on climate are generally considered to be the sole transfer mechanism between the orbital variables and cyclic sedimentary successions. Common oceanographic principles, however, show that the ocean tide also responds to variations in the orbital parameters. The ocean tide has not yet been considered to be a valid, additional transfer mechanism for the orbital variations. In geological studies of Milankovitch cycles in sedimentary successions the insolation paradigm offers satisfying explanations, and the role of long-term variations of the ocean tide has not yet been appreciated. Variations in the ocean tide, related to changing eccentricity (at present 0AE0165, theoretical maximum 0AE0728), affect a variety of oceanographic and sedimentary processes. In addition to the widely accepted paradigm of orbitally forced insolation changes, the tidal transfer of orbital signals may explain certain less well-understood aspects of orbitally induced cycles in the stratigraphic record related to ocean mixing, organic productivity, and tidal processes in shallow seas and deep water. Variations of the ocean tide in relation to the 18AE6 year lunar nodal cycle, which has no insolation counterpart by which they may be obscured, indeed show that these relatively small variations can produce significant effects in sedimentary environments that are sensitive to variations in the strength of the ocean tide. In analogy with the 18AE6 year lunar nodal cycle, orbital variations of the tide on Milankovitch time scales are likely to have affected sedimentary systems in the past.

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Geometry of Shelf Sandstone Bodies in the Shannon Sandstone of Southeastern Montana

Cited by 19 publications

References 0 publications

Origin of Concretion-Hosted Shell Clusters in the Late Cretaceous Bearpaw Formation, Southern Alberta, Canada

Origin of Concretion-Hosted Shell Clusters in the Late Cretaceous Bearpaw Formation, Southern Alberta, Canada

The Geology of Fluvial Deposits

Orbitally forced sedimentary rhythms in the stratigraphic record: is there room for tidal forcing?

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