Aquavortex: A Model for the Formation of Certain Pipe Structures Near the Permo Triassic Boundary in Southern Utah

Joe Fandrich

The sandstone/siltstone facies of the Hoskinnini Member of the Triassic Moenkopi Formation in southern Utah and northeastern Arizona contains a variety of exotic breccias, graded beds, soft-sediment deformation and clastic pipe structures interspersed within redbed sabkha deposits. Certain clastic megapipes in-filled from above and exhibiting evidence of rotation are described in this presentation. These pipes, associated breccias and soft-sediment deformation structures suggest an extreme and complex high energy event bed situated between undisputed Triassic and Permian beds where the boundary disconformity represents a hiatus of several million years. The western edge of the sabkha facies of the Hoskinnini Member appears to represent a mudflat situated along the western shoreline of Pangaea. It is proposed here that the unusual, vertically injected clastic megapipes were excavated and in-filled by massive water-charged vortices generated by eastward-onset tsunami originating in the late to end-Permian Panthalassa Sea.

AAPG Search and Discovery Article #90156©2012 AAPG Rocky Mountain Section Meeting, Grand Junction, Colorado, 9-12 September 2012