Donald M. Fisher

TL;DR: In this article, a unified methodology for problem-solving in structural geology using linear algebra and computation is presented, with a suite of online MATLAB functions, allowing users to modify the code to solve their own structural problems.

Abstract: Steady state models of overgrowth and vein formation are developed using kinetic data for quartz dissolution and precipitation and estimates of fluid advection, pore-fluid and grain-boundary diffusion. Application of these models to overgrowths and veins in the Kodiak accretionary complex suggests that the Kodiak Formation deformed continuously by a grain-boundary diffusion-limited mechanism, accompanied by episodic pore fluid diffusion of quartz from the matrix to vertical fluid-filled fractures near the base of the accretionary wedge. These processes produced two types of syntectonic crystal textures within the Kodiak Formation: overgrowths containing displacement-controlled fibers, and throughgoing veins composed of face-controlled elongate blocky quartz crystals. Based on textural observations, displacement-controlled quartz growth in overgrowths is rate-limited by either diffusion along a cohesive interface or the rate of matrix strain. The magfiitude of elongation recorded by displacement-controlled crystal growth varies smoothly (elongation of 1 to 3) from the shallowest to the deepest structural levels of the Kodiak Formation, suggesting that the diffusional component of deformation in the accretionary wedge increases with depth. In contrast, face-controlled quartz growth is largely restricted to veins within the deepest level, where the cleavage is subhorizontal and deformation involves a component of simple shear, suggesting proximity to a decollement. The facecontrolled quartz veins represent mode I cracks which seal periodically and contain continuous planar solid inclusion bands, cracks which partially seal periodically and contain discontinuous solid inclusion bands, or cracks that remain open and contain euhedral quartz crystals with no solid inclusions. The initial crack aperture, inferred from spacing of inclusion bands, varies from 8 gm in

TL;DR: In this article, the authors used thermochronometric data to evaluate erosion rates and particle paths within the active Taiwan arc-continent collision and presented 20 new apatite fission-track ages and 6 new zircon fission track ages.

TL;DR: In this paper, the authors identify three successive, transitional stages in the melanges: (I) breakup of sand beds along cataclastic shear zones with dispersal of sand inclusions within a relatively ductile shale matrix, (II) development of ductile shear bands that crosscut the melange fabric at a low angle, and (III) hydrofracturing with the formation of calcite and quartz-filled veins in sandstone inclusions and microfaults in the shales.

TL;DR: In this article, the authors present the results of a workshop sponsored by the U.S. Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division that was held in Leesburg, Virginia in May 2016.