Models of marine transgression —Example from Lower Cretaceous fluvial and paralic deposits, north-central Kansas

Franks, Paul C.

doi:10.1130/0091-7613(1980)8<56:momtef>2.0.co;2

Cited by 12 publications

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“…Transgressive deposits tend to be poorly represented, as least in nearshore settings, so that the stratigraphic record may consist primarily of the aggradational, re gressive phase of sedimentation (see Swift [1968Swift [ , 1976 for Cretaceous and Holocene Coastal Plain examples; Ryer [1977] and Larson and Byers [1978] on the Cretaceous of the West ern Interior; and Goodwin [1977, 1978], Goodwin and Anderson [1980], and Cameron [1978] for Paleozoic examples). Se quences with well-developed transgressive de posits may be limited to tectonically active re gions (e.g., Bourgeois 1979) and, more locally, in areas of particularly favorable pretransgression topography (e.g., Franks 1980). This per vasive asymmetric pattern of preserved sedi ments should affect the biotic patterns presented by the contained fossils, but no attempt has yet been made to consider this factor.…”

Section: Introductionmentioning

confidence: 99%

Apparent versus real biotic effects of transgressions and regressions

Jablonski

1980

Paleobiology

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In evaluating the biotic effects of transgressions and regression, care must be taken to ensure that observed patterns are not simply an artifact of the location of available stratigraphic sections along an ancient onshore-offshore gradient of adaptive types. Analysis of Recent bivalves suggests that very nearshore benthic assemblages are dominated by species that are geographically more widespread, are more eurytopic, and more often have planktotrophic larvae than species in offshore assemblages (Jackson 1974; Jablonski and Valentine 1980); this pattern may serve as a null hypothesis for paleobiogeographic analysis. Late Cretaceous bivalve and gastropod faunas of the Gulf and Atlantic Coastal Plain exhibit decreasing levels of endemism and increasing mean geographic range over the course of regression and return to high levels of endemism and low mean geographic range with the succeeding transgression. In addition, species with longer durations are more frequent at peak regression, while geologically shorter-lived species are more prevalent at peak transgression. As seen in Recent examples, the molluscan assemblages from nearshore facies have a higher proportion of species with broad environmental tolerances and planktotrophic larvae, and thus more extensive geographic and stratigraphic ranges, than do the more offshore shelf assemblages. Because late regressive phases are represented only by very nearshore facies, these directional changes in biogeographic and evolutionary characteristics are most parsimoniously interpreted as a reflection of the nature of the facies available for sampling rather than biotic effects of transgression and regression.

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Section: Introductionmentioning

confidence: 99%

Apparent versus real biotic effects of transgressions and regressions

Jablonski

1980

Paleobiology

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“…To establish internal consistency, the depositional environment of each example was assessed and reclassified as needed ( Table 1). In straightforward examples, the extent of barrier island deposits was measured or recorded directly from the publication (e.g., Bridges, 1976;Franks, 1980). For more ambiguous examples, however, the sedimentology and geologic context was considered in detail (e.g., Berg, 1976;Guscott et al, 2003).…”

Section: Database Developmentmentioning

confidence: 99%

Modern to Ancient Barrier Island Dimensional Comparisons: Implications for Analog Selection and Paleomorphodynamics

2019

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Ancient barrier islands are poorly understood relative to other clastic depositional environments, despite being prominent features along modern coastlines and important for understanding transgressive shoreline deposits. A new dataset of ancient barrier island dimensions (n = 83 examples) addresses this knowledge gap with a quantitative analysis of barrier island sand body dimensions including thickness (vertical), length (shore-parallel direction), and width (shore-perpendicular direction). This dataset of barrier island deposits was compared to planform measurements made for modern islands (n = 274), to investigate possible scaling relationships and other aspects of modern to ancient linkages. These measurements are nuanced and challenging to perform, and first-pass comparisons show that modern barrier islands should not be used as direct analogs for ancient systems. Nevertheless, results emphasize key depositional and preservation processes, and the dimensional differences between deposits formed over geologic vs. modern time scales. Using the methods outlined herein, barrier island deposits appear to be 2-5x longer (p50 modern = 10.7 km; p50 ancient = 20.0 km), and 6-15x wider (p50 modern = 1.2 km; p50 ancient = 7.3 km) than modern barrier islands. We interpret the results to indicate that ancient barrier islands are time-transgressive deposits recording vertical amalgamation, and barrier island growth by lateral accretion, and progradation. When comparing single barrier islands, thickness measurements do not vary systemically between modern and ancient examples, suggesting that local accommodation dictates barrier island thickness as a preservation control. Gross length, width, and thickness measurements are too coarse for robust paleomorphodynamic calculations, therefore more detailed sub-environment analysis (e.g., upper shoreface delineation), with improved facies models, is required before rigorous quantifications can Mulhern et al. Barrier Island Dimensional Comparisons be generated. However, these initial comparisons do show scaling trends between length and width which could be leveraged, with caution, in the interim. As sea levels continue to rise, understanding barrier island motion and preservation will be central to predicting coastal change.

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“…Paleotopographic relief as a control on distribution of fluvial, estuarine, and barrier-island successions is well documented for Holocene sediments in Delaware (Kraft, 1971), for Cretaceous marginalmarine rocks in Kansas (Franks, 1980), and the Texas Gulf Coast (Wilkinson, 1975). Heward (1981) states that barrier islands have the greatest preservation potential above paleotopographic lows, or drowned valleys.…”

Section: Depositional Reconstructionmentioning

confidence: 99%

Short notes on Alaska geology 1997

1998

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Models of marine transgression —Example from Lower Cretaceous fluvial and paralic deposits, north-central Kansas

Cited by 12 publications

References 0 publications

Apparent versus real biotic effects of transgressions and regressions

Apparent versus real biotic effects of transgressions and regressions

Modern to Ancient Barrier Island Dimensional Comparisons: Implications for Analog Selection and Paleomorphodynamics

Short notes on Alaska geology 1997

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