Journal article
Middle Albian provenance, sediment dispersal and foreland basin dynamics in southwestern Montana, North American Cordillera
Basin research, Vol.34(2), pp.913-937
04/2022
DOI: 10.1111/bre.12645
Abstract
The Lower Cretaceous Blackleaf Formation in southwestern Montana records sedimentation in the Idaho‐Montana retroforeland basin of the North American Cordillera. Regional‐scale sedimentology suggests that during Albian time southwestern Montana was partially flooded by an early marine incursion of the Western Interior Seaway during deposition of the Blackleaf Formation. We use sandstone petrography, large‐n (n = 600) U‐Pb detrital zircon geochronology and mixture modelling to determine the provenance of these strata. Our analysis suggests three distinct provenance groups: Group 1 sandstones occur in the eastern region of the study area, are quartz‐rich and have zircon age‐probability peaks of ca. 110, 160, 420–450, 1050 and 1160 Ma; these sandstones match with a primarily Appalachian provenance. Group 2 sandstones occur in the western region of study area, are lithic‐rich and have peaks of ca. 110, 160, 1780, 1840, 1920, 2080 and 2700 Ma; the primary source for these sandstones was exhumed lower‐middle Palaeozoic strata from the Idaho sector of the Sevier belt. Group 3 sandstones occur in the western region of the study area, are lithic‐rich and have prominent peaks of ca. 115, 170, 430, 600, 1085, 1170, 1670 and 1790 Ma; the primary source for these sandstones was exhumed Triassic‐upper Palaeozoic strata from the Idaho sector of the Sevier belt. Our provenance data record a sharp change that coincides with the western shoreline of the seaway, and we infer that it may indicate the position of an irregular, submarine forebulge depozone influenced by dynamic subsidence during a period of reduced thrusting in the adjacent fold‐thrust belt. Albian‐aged sediments in southwestern Montana were delivered by rivers with headwaters in the Sevier belt as well as transcontinental river systems with headwaters in eastern North America. In southwestern Montana, west‐flowing transcontinental fluvial systems were flooded by the Western Interior Seaway as it encroached from the north.
Detrital zircon geochronology of the Albian lower Blackleaf Formation in southwestern Montana documents a sharp change in provenance along the shoreline of the Western Interior Seaway. The western, nonmarine, lithic sandstone has a Sevier belt provenance; the eastern, marine, quartz sandstone was sourced from the Appalachians of eastern North America.
Details
- Title: Subtitle
- Middle Albian provenance, sediment dispersal and foreland basin dynamics in southwestern Montana, North American Cordillera
- Creators
- Justin A Rosenblume - University of IowaEmily S Finzel - University of IowaDavid M Pearson - Idaho State UniversityCole T Gardner - University of Iowa
- Resource Type
- Journal article
- Publication Details
- Basin research, Vol.34(2), pp.913-937
- DOI
- 10.1111/bre.12645
- ISSN
- 0950-091X
- eISSN
- 1365-2117
- Number of pages
- 25
- Grant note
- Graduate College, University of Iowa Sullivan‐Smith Fund, EES Department, University of Iowa Tobacco Root Geological Society Leisch Fund, EES Department, University of Iowa National Science Foundation (EAR‐1727504; EAR‐1728563; NSF‐EAR 1649254) Furnish‐Glenister Fund, EES Department, University of Iowa
- Language
- English
- Date published
- 04/2022
- Academic Unit
- Earth and Environmental Sciences
- Record Identifier
- 9984229292202771
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