An integrated analysis of controlled and passive source seismic data across an archean-proterozoic suture zone in the Rocky Mountains

Abstract

We conducted a new integrated analysis of the controlled and passive source seismic data from the Continental Dynamics of the Rocky Mountains (CD-ROM) experiment in the western United States. A specific goal of our study was to establish a stronger tie between the CD-ROM and Deep Probe experiments that together form a transect that extends almost 3000 km from northern New Mexico to the southern Northwest Territories of Canada. We created a new P wave velocity and interface model from the controlled source seismic (CSS) data on the basis of an advanced picking strategy that produced substantially more arrivals whose traveltimes could be picked. In addition, we were able to identify a substantial set of S wave arrivals and to establish an independent S wave model, which allowed us to estimate the Vp/Vs and Poisson's ratios in the crust. An integrated analysis of the CSS data with recently generated receiver function results and gravity data allowed us to construct a well-constrained multiparameter structural model. This model resolves the structural framework of the crust and uppermost mantle of the transition from the Wyoming craton to the north, across the Cheyenne belt suture zone, and into the Proterozoic terranes to the south. Our tectonic interpretation that crustal-scale crocodile structures are present provides an explanation for the south dip of the Cheyenne belt in the upper crust and the north dipping slab in the mantle revealed by earlier tomographic results. The very distinct crustal structures north and south of the suture zone are clearly shown in our model and document that the blocks that collided at ∼1.8 Ga to form the Cheyenne belt suture zone have retained their basic crustal and uppermost mantle structure since then. Copyright 2009 by the American Geophysical Union.