41 Recent Work in Mesozoic East Coast Rift Basins: Structure, Sedimentology, Paleontology, Mapping, and More! (Posters)

This session will bring together those conducting geological studies of the evolution of North American east coast Mesozoic rift basins and their sedimentary, volcanic, paleontological, and paleoclimatic records.

Tuesday, 24 March 2026
8:00 AM - 12:00 PM
CCC, Ballroom C

Sources say otherwise: A detrital zircon take on Connecticut’s Mesozoic rift basins

Paper number: 41-0
Program: Technical Sessions
Time: 8:00 AM – 8:00 AM

Authors

Abstract

In this study, LA-ICP-MS derived U-Pb ages of detrital zircons from six sandstones, combined with data from seven previously reported samples, provide new insight into the evolution of the synrift sediment fills in the Mesozoic basins of Connecticut. These results improve provenance constraints, allowing refinement of paleogeographic reconstruction and tectonic models for basin development. The Hartford basin contains over 4 km of Upper Triassic to Lower Jurassic fluvial, lacustrine and volcanic strata. The Pomperaug basin, a small outlier basin ~20 km west, is composed of a few hundred meters of similar strata. Both basins developed as half grabens with active eastern border faults tilting strata to the east. Similarity of basin fills has long led to speculation that the basins were once more extensive and connected in a “broad-terrane” basin, with only erosional remnants remaining.

 

Samples contain diverse populations of zircons but predominantly are dominated by five age ranges, reflecting source rocks affected by various orogenies: Alleghanian, Acadian, Taconic, Peri-Gondwanan, (Avalonian), and Grenville. Surrounding basement geology of the areas surrounding the basins is a bewildering complex of N-S linear belts of terranes accreted during Paleozoic orogenies, and penecontemporaneous metamorphic alterations and recycling of zircons makes pinpointing provenance a challenge. Nonetheless, results reveal notable trends. Eastern samples contain distinct zircon populations: on the east side, Taconic and peri-Gondwanan zircons consistent with proximity to the Bronson Hill Arc and Avalon terrane, whereas western samples are dominated by Acadian ages, with few Taconic ages, suggesting a predominant western source.  East Berlin samples contain distributions indicating sediment from both east and west source areas. Pomperaug basin samples also record mixed provenance signatures.

 

Combined, these results indicate that the basins developed, at least initially, as individual entities. Provenance changed during basin evolution, with Jurassic strata containing significantly higher proportions of Grenville ages, consistent with increased western or axial drainage into the basin. Similar stratigraphic trends are recognized in the Pomperaug strata, which contain more Grenville-aged zircons, reflecting closer proximity to that source.  The reorganized drainage into the basin likely represents transition into a later-stage tectono-sedimentary setting.

Geological Society of America Abstracts with Programs. Vol. 58, No. 2

doi: 10.1130/abs/2026NE-411285

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