A PALEOMAGNETIC ANALYSIS OF VERTICAL AXIS ROTATION ALONG THE TASCOTAL MESA FAULT IN FAR WEST TEXAS

The Tascotal Mesa transfer zone (TMTZ), as described by Dickerson (1995), is an east-west trending zone expressing ~290 million years of tectonic and magmatic activity since the late Paleozoic. The Tascotal Mesa Fault (TMF) lies within the TMTZ as a right lateral strike-slip fault expressing ~1 km of dextral offset and ~735 m of normal dip-slip motion within the last ~30 million years (Dickerson, 1995). The TMF is at the southeastern margin of the Basin and Range extensional province and functions as a transfer zone within the Rio Grande rift in west Texas (Dickerson, 2013 Henry, 1998 Henry et al., 1991). Ideal horizontal extension should cause the crust to undergo only vertical motion or rotation about a horizontal axis, but vertical-axis rotations have been documented in volcanic flows within the TMTZ, by the use of paleomagnetism (Rapp et al., 1983, Ryan, 1988, Sager et al., 1992, Winters, 1967). The goal of this study is to interpret the role of the Tascotal Mesa Fault in accommodating crustal deformation through a quantitative vertical axis rotation paleomagnetic analysis and the preliminary results will be presented.