31 CRITICAL MINERAL DEPOSITS AND ORE SYSTEMS OF THE NORTHEAST (Poster)

This session will showcase new findings pertaining to critical mineral resources and hydrothermal-magmatic ore systems across the northeast. We welcome submissions involving fieldwork, geochemical, petrologic, geochronologic, and other approaches from micro- to macroscopic scales.

Monday, 23 March 2026
1:30 PM - 5:30 PM
CCC, Ballroom C

Statewide Bedrock Geochemical Reconnaissance: A Foundation for Mineral System Evaluation, Modern Mapping, and Societal Applications in Connecticut

Paper number: 31-1
Program: Technical Sessions
Time: 1:30 PM – 1:30 PM

Authors

Abstract

Six Earth Mapping Resources Initiative (Earth MRI) focus areas have been identified in the State of Connecticut: The Salisbury iron mining district supergene deposits, peri-Laurentian arc system copper-zinc sulfide deposits, LCT pegmatites, Hartford-Deerfield Basin MVT Zn-Pb deposits and Ni-Cu-PGE sulfide deposits, Great Hill Ni-Co-Cu sulfide deposits, and Brimfield Schist graphite deposits. These areas need additional geochemical and geophysical information to get a better understanding of their mineral systems, geologic framework, and economic potential. However, a paucity of geochemical analyses associated with 7.5-minute quadrangle bedrock geologic maps published in the 1950s to 1970s leaves little known about mineral deposit or bedrock geochemistry in Connecticut. 

The State-wide Geochemical Reconnaissance Project aims to improve the frequency, extent, and accessibility of bedrock geochemical information. To begin, a baseline geochemical database and map was developed from collated geochemical sampling literature and previous state geothermal and mapping projects. From this baseline, we will develop a robust sampling plan to include bedrock outcrop sampling across the State for a full suite of geochemical analyses, targeting large data gaps in the mineral focus areas and areas of societal importance for State residents. Sampling efforts will utilize state-wide 2023 LiDAR data, 2025 USGS Earth MRI CT Valley magnetic and radiometric airborne survey data, aerial photography, published and unpublished geologic maps, and previous literature. Hand sample locations will be documented in Esri FieldMaps, inventoried, and sent to USGS and subcontractor laboratories to analyze major, trace, and REEs. Sampling will include total sulfur to identify potentially pyrrhotite-rich locations, a societal concern for crumbling concrete with aggregates used in foundations. Measuring uranium and arsenic concentrations will also help identify source lithologies for these groundwater contaminants. Select samples will also be analyzed for PGEs, graphite, and fluoride. Critical mineral compositions, host minerals, and crystallization age relationships will be identified with thin sections and electron microprobe analysis, while U/Pb zircon and 40Ar/39Ar cooling dates will help characterize fluoride-associated pegmatites in western Connecticut.  

The new state-wide geochemical dataset will allow petrologically similar bedrock units to be more easily discriminated, helping set future bedrock mapping priorities, create new modern geologic maps, and provide much needed data to assess societal concerns in the State. The database will also provide ground truth data for the EARTH MRI CT Valley airborne survey. 

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

doi: 10.1130/abs/2026NE-411501

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