Magnetotelluric Survey to Locate the Archean/Proterozoic Suture Zone in North-Central Elko County, Nevada Open file rept

摘要

It is important to know whether major mining districts in the Northern Nevada Gold Province are underlain by rocks of the Archean Wyoming craton, known to contain large orogenic gold deposits (Cameron, 1988), or by accreted rocks of the Paleoproterozoic Mojave province (Whitmeyer and Karlstrom, 2004). It is also important to know the location and orientation of the Archean/Proterozoic suture zone between these provinces and of major basement structures within them because these features may affect subsequent patterns of sedimentation, deformation, magmatism, and hydrothermal activity (Grauch, and others, 2003). In eastern Utah and western Wyoming, the Archean/Proterozoic suture zone is exposed and has an east-west strike (Reed, 1993). In the Great Basin, the strike of the Archean/Proterozoic suture zone is poorly constrained because it is largely concealed below a Neoproterozoic-Paleozoic miogeocline and basin fill. East-west and southwest strikes have been inferred on the basis of strontium (Sr), neodymium (Nd), and lead (Pb) isotopic compositions of granitoid intrusions (Tosdal, and others, 2000). To better constrain the location and strike of the Archean/Proterozoic suture zone below cover, a regional south-north magnetotelluric (MT) sounding profile was acquired in north-central Nevada (fig. 1) to track the suture zone from western Utah (Williams and Rodriguez, 2003) and eastern Nevada (Williams and Rodriguez, 2004). Resistivity modeling of the MT data can be used to investigate buried structures or sutures that may have influenced subsequent regional fluid flow. The purpose of this report is to release the MT sounding data collected in north-central Nevada in September 2004; no interpretation of the data is included.