11 Using Volcanic Deposits to Help Us Understand Volcanic and Magmatic Processes
This session invites presentations that leverage volcanic deposits to reconstruct magmatic and eruptive processes. We welcome contributions from field and experimental volcanology, petrology, geochemistry, thermodynamics, and fluid mechanics, ranging from the landform to nanoscale.
Sunday, 19 October 2025
8:00 AM - 12:00 PM
HBGCC, 217A
Field Indicators of Magma Flow Duration in Basaltic Feeder Dikes
Paper number: 11-13
Program: Technical Sessions
Time: 11:15 AM – 11:30 AM
Authors
Abstract
Long-lived feeder dikes show distinct features that are not present in short-lived feeder dikes, and these features are observable in the field. I will use examples from dikes of the Columbia River Basalts and the North Atlantic Igneous Province to highlight these features. Easily quantified properties such as dike width, length, dip, strike, and paleodepth show no correlation with dike longevity. Instead, more subtle internal features within the dike and thermal effects on the surrounding wall-rock are reliable indicators of their magmatic longevity. Partially melted wall-rock is the most robust indicator of a long-lived dike, which forms only when the dike remains active long enough and its magma is hotter than the wall-rock’s solidus. Increased coherence or grain annealing in the wall rock can also suggest prolonged heat exposure from a long-lived segment. Short-lived dikes will have small-diameter columns near the margins. In contrast, long-lived segments feature larger-diameter columns with no quenched margins. These field indicators offer rapid (albeit qualitative) insights into the magmatic longevity of mafic dike systems.
Geological Society of America Abstracts with Programs. Vol. 57, No. 6
doi: 10.1130/abs/2025AM-413298
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