HR: 0800h
AN: T11A-0335    [Abstracts]
TI: The Development of Vein and Pressure Solution Arrays in a Compressive Orogenic Belt, County Clare, Ireland.
AU: * Nenna, F A
EM: fnenna@stanford.edu
AF: Stanford University, Department of Geological & Environmental Sciences 450 Serra Mall Braun Hall, Building 320, Stanford, CA 94305-2115, United States
AU: Aydin, A
EM: aydin@pangea.Stanford.EDU
AF: Stanford University, Department of Geological & Environmental Sciences 450 Serra Mall Braun Hall, Building 320, Stanford, CA 94305-2115, United States
AB: The Carboniferous Ross Sandstone, exposed on the Loop Head Peninsula, County Clare, Ireland is part of the deep-water deposits of the Shannon Basin fill that was subject to compressive stresses at the end of the Carboniferous during the Variscan Orogeny. This deformation produced broad regional east-west trending folds and also tight low-amplitude folds that are concentrated around thrust faults. Near these faults, orthogonal sets of pressure solutions and veins form a pervasive structural assemblage within the sandstone. Abutting relationships of the veins against the pressure solution seams indicate contemporaneous formation of the two structure sets. The east-west orientation of the pressure solution seams are sub-parallel to local thrust fault traces and fold axes, and reflects the regional Variscan structural fabric. A subsequent stress or material rotation during the Variscan Orogeny (or perhaps a major second stage of deformation either in late phase of the orogeny or following the orogeny) has lead to left-lateral shear of the pressure solution seams evidenced by pressure solution splays and pull-aparts between their sheared segments, and right-lateral shear on the veins evidenced by splay crack features. With increased shear, extensive splay cracks and pull-apart networks form damage zones through which strike-slip fault systems develop. Ultimately, this study documents the formation of damage zones through the formation and evolution of veins and pressure solution seams and the role of these fundamental structures in palaeo- and present-day fluid flow.
DE: 8004 Dynamics and mechanics of faulting (8118)
DE: 8005 Folds and folding
DE: 8010 Fractures and faults
DE: 8118 Dynamics and mechanics of faulting (8004)
SC: Tectonophysics [T]
MN: 2007 Fall Meeting