40 Mesozoic Magmatism, Postrift Tectonics, and Passive Margin Development of Northeastern North America (Posters)

The northeastern region experienced protracted Mesozoic (Triassic-Cretaceous) magmatism associated with continental rifting and subsequent passive margin development. We welcome contributions related to the occurrence, tectonics, or driving mechanisms of these syn- and postrift events.

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

New (but still Preliminary) Bedrock Geologic Map of the Hartford Basin Region, Central Connecticut: Geochemical Refinements and Preliminary Aeromagnetic Insights

Paper number: 40-3
Program: Technical Sessions
Time: 8:00 AM – 8:00 AM

Authors

  • Meghan Seremet Presenting Author
    Connecticut Geological and Natural History Survey, Hartford, Connecticut
  • Elias Utterback
    Connecticut Geological and Natural History Survey, Hartford, Connecticut
  • Anjana Shah
    United States Geological Survey, Denver, CO
  • Devin Justman
    Connecticut Geological and Natural History Survey, Hartford, CT
  • Randolph Steinen
    Connecticut Geological and Natural History Survey, Hartford, Connecticut
  • Allison Charney
    Central Connecticut State University, New Britain, CT
  • Robert Wintsch
    Connecticut Geological and Natural History Survey, Haddam, CT

Abstract

We present a preliminary updated map of the central Connecticut portion of the Bedrock Geological Map of Connecticut compiled by John Rodgers in 1985. This map was funded in part by the USGS STATEMAP program. New whole-rock major, trace, and rare earth element data for 71 samples of diabase, basalt, and lamprophyre have refined igneous unit identification and correlation of feeder dikes with associated basalt flows. These flows are from oldest to youngest the Talcott, Holyoke, and Hampden basalts. A previously unrecognized sill has been added to the map. The sill shares a similar chondrite-normalized rare earth element pattern with the Holyoke Basalt; however, lower overall rare earth element concentrations indicate a more primitive magmatic pulse derived from a similar magma source. In addition, a lamprophyre district has been identified, with several newly discovered and previously identified narrow (m-wide) dikes included as an inset map. New airborne magnetic data, collected through the USGS Earth Mapping Resources Initiative (Earth MRI) in 2025, show magnetic anomaly highs over the basalt and sills, likely caused by their significantly higher magnetic susceptibility compared to the surrounding sandstones and shales. The new data will thus allow for more accurate mapping of the bedrock in areas covered by glacial and post-glacial deposits, further refining igneous units in select areas once final processing is complete.

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

doi: 10.1130/abs/2026NE-411374

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