PERMIAN TO HOLOCENE NAMAKIERS (SALT GLACIERS) IN THE PARADOX BASIN OF SOUTHWEST COLORADO AND SOUTHEAST UTAH, USA

Namakiers are associated with most salt diapirs in the Deep Fold and Fault Belt (DFFB) of the Paradox Basin and first formed while diapirs were rising during the Early Permian. Only after a diapir was breached was salt (and associated strata) able to flow into the breach and away from the diapir. Namakiers are recognizable on seismic and well logs, sometimes contain stratum and rock fragments with distinct lithologies and Pennsylvanian fossils, and may act as top seals for hydrocarbon accumulations. Paradox Basin namakiers have a seismic signature and size similar to Triassic namakiers in the Permian Salt Basin, Germany, and dimensions similar to those exposed in the Zagros Fold Belt, Iran. The oldest and best preserved namakiers are in southwest Colorado (up to 800ft, 240m thick) and were concurrent with the deposition of the latter part of the massive wedge of Wolfcampian Elephant Canyon Formation and Leonardian Organ Rock Formation sediments in the DFFB. This massive sedimentation overloaded the underlying Pennsylvanian Paradox salt (8000ft, 2400m with interbedded strata) and reshaped low-relief salt anticlines into tall salt walls and diapirs, thus leading to the initial extrusion of salt during the Leonardian. Preservation of the Leonardian Organ Rock namakiers within fluvial redbeds was likely due to a combination of arid climate and rapid burial in adjacent coeval salt-withdrawal mini-basins. Namakiers are also preserved in southeast Utah on three diapirs in and concurrent with massive deposition of Early Triassic Moenkopi redbeds in the DFFB. The youngest namakier is on the Fisher (Onion Creek) diapir in Grand County, Utah where upward flowage of salt, gypsum and associated strata dammed Onion Creek during Late Pliocene through the Pleistocene, trapping sediments in an upsteam “mini-basin” within the breached dome. The Onion Creek namakier is probably still active, but post-Pleistocene incision by Onion Creek has allowed erosion and dissolution to keep pace with or exceed the upward flow of evaporites.