Supplemental material: Plate margin deformation and active tectonics along the northern edge of the Yakutat Terrane in the Saint Elias Orogen, Alaska, and Yukon, Canada
journal contributionposted on 16.11.2012, 00:00 by Ronald L. Bruhn, Jeanne Sauber, Michelle M. Cotton, Terry L. Pavlis, Evan Burgess, Natalia Ruppert, Richard R. Forster
Geosphere, December 2012, v. 8, p. 1384-1407, doi:10.1130/GES00807.1, Supplemental Figure 4 - PDF file of supplement for Figure 9. Relationships between geologic structure, rock sliding, and the origin and shaping of cirque basins along the southern flank of the eastern Bagley Ice Valley. (A) Oblique view of part of the southern flank with prominent structural surfaces or “rock mass discontinuities” labeled on the figure. (B) Lower hemisphere stereographic projection showing poles to bedding on fold limbs (point clusters P1 and P2) and joints (cluster P3) within the rock mass. S1, S2, and S3 are the corresponding great circles to the average poles to bedding and joints. There is also a foliation that is axial planar to the folded bedding, and that dips to the north. Foliation and bedding strike subparallel to the trend of the ice valley, and axial surfaces of folds dip steeply towards the north. Joint set S3 intersects the foliation and bedding surfaces and cuts across the axial surfaces of the folds. Mass wasting by rock sliding is caused by failure along the north dipping foliation and bedding surfaces with joint set S3 providing the discontinuities that limit the lateral extent of slide masses. Topography and structural surfaces were extracted from the STAR3i digital elevation model (DEM) with the strike and dip of prominent structural surfaces determined by three-point solutions and field reconnaissance. The area encompassed by the figure is marked by a yellow dashed rectangle in Figure 9.