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

Fluid Inclusions in the Cuttingsville Pluton Complex: Understanding the Thermal History of the Youngest New England-Quebec Igneous Province Pluton

Paper number: 40-0
Program: Technical Sessions
Time: 8:00 AM – 8:00 AM

Authors

Abstract

The Cuttingsville plutonic complex in Vermont is located within the Taconic lobe of the New England–Quebec (NEQ) igneous province. The Early Cretaceous Cuttingsville complex represents the youngest pluton in the New England region. The pluton was emplaced in a passive margin setting and represents the last stage of  NEQ postrift magmatism. The ~103 Ma complex is inconsistent with the Great Meteor hotspot track and requires an alternative mechanism to explain its occurrence (Cooper et al., 2021). Shallow mantle processes such as edge-driven convection have been proposed to explain the magmatism. The crosscutting structures of the complex provide a better understanding of the passive margin after 103 Ma. 

Field work at the Cuttingsville complex focused on the structures exposed along the Mill River. The quartz syenite is crosscut by brittle fractures, igneous dikes, mineralized veins, and mesoscale faults.  Fluid inclusion work was conducted to better understand the thermal history of the crosscutting structures and their timing relative to the pluton emplacement.

Fluid inclusions were found in the quartz syenite and in the crosscutting mineralized veins. Observed fluid inclusions in quartz were both primary and  secondary in origin, reflecting their formation at different stages of the plutonic complex’s history. The fluid inclusions vastly ranged in size from less than a micron to more than 20 microns. The small ( ~1 micron or less) fluid inclusions were distributed along planes interpreted as healed microfractures. Homogenization temperatures for fluid inclusions within the mineralized veins were relatively low for a magmatic system. This suggests that the hydrothermal system associated with the mineralized veins likely resulted from a meteoric fluid component that circulated through a shallow, brittle pluton during late-stage or post-magmatic cooling. 

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

doi: 10.1130/abs/2026NE-411116

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