9 Stratigraphy and Sedimentology

Thursday, 18 May 2006
8:00 AM - 9:40 AM

EVIDENCE IN UTAH OF AN EASTWARD MOVING ENERGY WAVE THAT ORIGINATED IN THE PERMIAN/TRIASSIC PANTHALASSA SEA: THE BLACK DRAGON BRECCIA AND HOSKINNINI CONNECTION

Paper number: 9-2
Program: Technical Sessions
Time: 8:20 AM – 8:40 AM

Authors

Abstract

The Black Dragon Breccia lies unconformably upon the Permian Kaibab Limestone and appears to be unconformable with the overlying remainder of the Triassic Black Dragon member of the Moenkopi Formation in the San Rafael Swell of east-central Utah. This breccia grades into the Hoskinnini member of the Moenkopi Fm, approximately 115 miles to the southeast of the San Rafael Swell in the White Canyon area located between Bridges National Monument and Hite, Utah.

Eastward trending off-set depositional patterns observed in the Black Dragon Breccia along with eastward thinning breccias and eastward thrusting recumbent folds present within the Hoskinnini suggest an extremely potent energy regime that originated in the Panthalassa Sea west of Pangaea. Soft-sediment deformation features in the Hoskinnini and deposits of chert breccia derived from the Kaibab (exposed only several miles west of the White Canyon area) are represented in a generally north-south belt measuring approximately five by fifteen miles and are herein considered to be the result of a major tsunami near the Permian/Triassic boundary.