Fracturing of Sedimentary Rock Around Magmatic Dikes Due to Thermal Pressurization of Pore Fluids

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Abstract/Contents

Abstract: Examination of the host rock around magmatic dikes at Ship Rock, NM, reveals two sets of joints in the Mancos shale in the immediate vicinity of the dikes. One set is parallel to the dike contact and is believed to have formed just ahead of the dike as it was propagating (Delaney et al. 1986). The other joint set is sub-perpendicular to the dike contact and is the focus of this paper. A high-resolution aerial map of a segment of the northeastern dike at Ship Rock was made using Structure from Motion (SfM), where a camera attached to a helium balloon collects photographs, which are automatically orthorectified and stitched together in Agisoft LLC. Measurements from this map, combined with other field data, shows that the joint set remains perpendicular to the contact along the length of the dike, even when the orientation of the dike changes. Furthermore there is a significant decrease in the fracture spacing towards the center of the dike. We interpret the joints to have formed as a result of heat flow from the dike, and we investigate the role of thermal pore-pressurization in this process. Understanding the formation of these joints is critical to our understanding of brecciation and erosion of host rock around fissure eruptions to produce sustained eruptions through larger cylindrical volcanic vents.

Type of resource	text
Date created	2014

Author	Townsend, Meredith
Author	Pollard, David D.

Subject	basaltic volcanism
Subject	thermal pore pressurization
Subject	physics-based models
Subject	heat and mass transport
Subject	rock mechanics
Subject	Ship Rock New Mexico
Subject	The Stanford Rock Fracture Project
Genre	Article

Location	https://purl.stanford.edu/gc344vg6165

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License: This work is licensed under a Creative Commons Attribution 3.0 Unported license (CC BY).

Preferred Citation: Townsend, Meredith and Pollard, David D. (2014). Fracturing of Sedimentary Rock Around Magmatic Dikes Due to Thermal Pressurization of Pore Fluids. Stanford Digital Repository. Available at: http://purl.stanford.edu/gc344vg6165

The Stanford Rock Fracture Project

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