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

Delineation of Structure of Triassic Sediments Near Spring Mountain, Schwenksville, PA to Better Understand local Triassic Diabase Emplacement

Paper number: 41-1
Program: Technical Sessions
Time: 8:00 AM – 8:00 AM

Authors

Abstract

We studied deformation in the Triassic basin in the vicinity of Spring Mountain, Schwenksville, in northern Montgomery County, southeast Pennsylvania to better understand the geometry of local igneous intrusions. The basin here includes Triassic sedimentary units and mafic intrusions, dominantly in sills, in gentle folds in map pattern that deform both the sedimentary units and the sills - i.e. folding postdates intrusion.  The mafic intrusions were deposited during Central Atlantic magmatic province (CAMP) magmatism (~201 Ma) which resulted in low-volume deposits of highly variable thicknesses and orientations. Surface exposures of the mafic material are limited, yet the deposits are considered connected in the subsurface. Geochemical variability of the few exposures has lead to questions over the petrologic evolution of the erupted material which is largely controlled by localized structural constraints.  We collected orientations of bedding in the sedimentary units adjacent to the main sill in the vicinity of Schwenksville and north and west, to better constrain the thickness and orientation of that sill. The sill is approximately 400 meters thick, and locally varies by up to 20 meters.  While there is some local variability, the broad Triassic folding geometry in the vicinity of Schwenksville is a gentle syncline with a fold axis plunging approximately 12 degrees west-northwest. 

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

doi: 10.1130/abs/2026NE-411427

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