Oral Presentations
Provenance Analysis of the Golden Spike and Blackleaf Formations through Detrital Zircon and Petrographic Analysis
Presentation Type
Presentation
Faculty Mentor’s Full Name
Marc Hendrix
Faculty Mentor’s Department
Geoscience
Abstract / Artist's Statement
In this study, we aim to investigate the changes in provenance between the Upper Cretaceous Golden Spike Formation and Middle Cretaceous Flood Member of the Blackleaf Formation using detrital zircon, petrographic, and scanning electron analysis. Samples were collected from the Upper Cretaceous Golden Spike Formation at a southward-facing roadcut along the North Frontage Road in Garrison, MT, and from the Middle Cretaceous Flood Member of the Blackleaf Formation at a west-facing roadcut 12 miles east of Garrison along Highway 12. Detrital zircons were separated from both sets of samples and sent to Boise State to determine the maximum depositional ages of the formations and to document variations in detrital zircon age spectra among the three samples. The zircons were separated by crushing and milling the samples, followed by running the milled material through a water table for density separation. This step was succeeded by magnetic separation and heavy liquid separation, which yielded the final detrital zircon concentrates. Thin sections were prepared from each sample of the Golden Spike and Blackleaf Formations and analyzed with a petrographic microscope to characterize the formation's mineralogy. Additionally, the samples were examined under a Scanning Electron Microscope (SEM) to investigate variations in framework grain mineralogy and diagenetic components such as cement. This study will contribute to our knowledge of the evolution of the Cretaceous foreland basin in Montana by offering insights into the types and variability of sediment input into the basin, the age of the sediment reaching the basin, and the general provenance of basin material.
Category
Physical Sciences
Provenance Analysis of the Golden Spike and Blackleaf Formations through Detrital Zircon and Petrographic Analysis
UC 331
In this study, we aim to investigate the changes in provenance between the Upper Cretaceous Golden Spike Formation and Middle Cretaceous Flood Member of the Blackleaf Formation using detrital zircon, petrographic, and scanning electron analysis. Samples were collected from the Upper Cretaceous Golden Spike Formation at a southward-facing roadcut along the North Frontage Road in Garrison, MT, and from the Middle Cretaceous Flood Member of the Blackleaf Formation at a west-facing roadcut 12 miles east of Garrison along Highway 12. Detrital zircons were separated from both sets of samples and sent to Boise State to determine the maximum depositional ages of the formations and to document variations in detrital zircon age spectra among the three samples. The zircons were separated by crushing and milling the samples, followed by running the milled material through a water table for density separation. This step was succeeded by magnetic separation and heavy liquid separation, which yielded the final detrital zircon concentrates. Thin sections were prepared from each sample of the Golden Spike and Blackleaf Formations and analyzed with a petrographic microscope to characterize the formation's mineralogy. Additionally, the samples were examined under a Scanning Electron Microscope (SEM) to investigate variations in framework grain mineralogy and diagenetic components such as cement. This study will contribute to our knowledge of the evolution of the Cretaceous foreland basin in Montana by offering insights into the types and variability of sediment input into the basin, the age of the sediment reaching the basin, and the general provenance of basin material.