10/14/2025
By Brianna Bowlby

The Kennedy College of Sciences, Department of Earth, Environmental and Atmospheric Sciences, invites you to attend a Master’s Thesis Defense by Brianna Bowlby titled “Provenance of the Narragansett Basin in New England using detrital zircon analysis.”

Date: Tuesday, October 28, 2025
Time 12:30- 2:30 p.m.
Location: Olney Hall 312

Advisor: Richard Gaschnig, Ph.D., Environmental, Earth and Atmospheric Sciences, UMass Lowell

Committee Members:

  • Kate Swanger, Ph.D., Earth, Environmental, Earth and Atmospheric Sciences, UMass Lowell
  • Daniel Murray, Ph.D., Department of Geosciences, University of Rhode Island

Abstract:
The Narragansett basin is a clastic sedimentary basin that contains some of the only Carboniferous strata from New England, making it a rare sedimentary record of the transition from the Acadian orogeny to the Alleghenian orogeny. Sedimentary rocks within the basin are continentally derived and were deposited on plutonic and metamorphic basement rocks of the Avalon terrane. The lower units of the basin include the Wamsutta Formation, Pondville Conglomerate, Sachuest Arkose, and Purgatory Conglomerate, although their relationships to one another are not entirely clear. These units are overlain by the Rhode Island Formation and Dighton Conglomerate. This study aims to investigate the provenance of these six stratigraphic units and reconstruct the sediment source areas to better understand the basins history and evolution. Detrital zircon U-Pb geochronology and trace element analysis with LA-ICP-MS along Hf isotopic data was utilized to understand age distributions for each formation and to observe how their geochemical history has evolved over time. Detrital zircon ages were dominated by Neoproterozoic grains from 605-635 Ma, except for the Rhode Island Formation which exhibited a dominant age peak during the Silurian ~425 Ma. Obtaining the locations for these source areas can allow for further constraints on the region's paleogeography and how it has evolved over time. Most of the detritus was drawn from proximal plutons and older metasedimentary rocks from areas adjacent to the basin and in distal African sources. Conversely the Rhode Island Formation appears to consist of material derived from plutonic belts to the north, near the MA-NH border.