RECONSTRUCTING FAULT HISTORY FROM FAULT ROCKS AND TRAVERTINE DEPOSITS, ROCK CANYON FAULT, UTAH

Central Utah lies along the eastern border of the Basin and Range Province. Within this region the Rock and Dry Canyon’s graben structure is a block dropped down by oblique faults with an anomalous east-west orientation relative to other Basin and Range structures. Travertine is a rock composed of calcium carbonate that is commonly associated with faults, particularly active faults. The geometry and the macro/microstructures of travertine can provide a record of the evolution of the fault through time. The objectives of this study are to document the evidence of fault history contained in travertine formed along the Rock Canyon fault in order to test the hypothesis that this is a young, potentially active structure contributing to Basin and Range Province deformation. Polished rock slabs prepared from travertine samples collected along the mapped Rock Canyon fault show a wide range of textures, including columnar, radial/fibrous, banded, bedded, botryoidal, and brecciated travertine (broken, cemented fault rock) along with fibrous, brecciated, and blocky crystalline calcite. Angular clasts of layered travertine, deposited along the fault at an earlier stage, are contained within breccias documenting a subsequent slip event (or events). Therefore, initial observations on fault rock textures indicate that there were multiple slip episodes on the Rock Canyon fault. More detailed microscopic observations on thin sections prepared from the same samples will constrain the number and type of fracturing, fault slip, and vein precipitation events that occurred.