Abstract - The Moab Fault is a 28 mile (45km) long, salt related, normal fault of about 3,100ft (950m) maximum surface throw. The fault cuts a Pennsylvanian to Cretaceous sedimentary sequence, and extends north-westwards from the Moab-Spanish Valley salt anticline along the south-western flank of a salt withdrawal syncline. The surface trace comprises a simple southern segment joined at branch-points to a series of fault splays in the north. Maximum surface throw occurs in the south where the fault is associated with both a footwall high and a hanging wall anticline. The fault trace is bordered by a damage zone, which includes a swarm of minor structures, that is most extensively developed within regions of structural complexity, for example around branch-points fault bends, overlap zones and fault-related folds. The fault was active from the Triassic until at least the mid-Cretaceous.
Distinctive types of veining, calcite cementation and iron oxide
reduction are best developed adjacent to the fault, especially in Jurassic
Navajo and Entrada sandstones. Calcite, ankerite, barite, and pyrite cemented
veins are restricted to the immediate proximity of the fault except within
regions of structural complexity. Concretionary calcite cements are extensively
developed within regions of structural complexity where they extend for
tens of metres away from the fault. Reduction of iron oxides in red bed
sandstones is more widely distributed than cementation and veining. Within
regions of structural complexity adjacent to the fault the Navajo and Entrada
sandstone sequences are entirely reduced, whilst reduction fronts extend
up to 3 miles(5km) away from the fault in the most permeable horizons.
Field observations indicate that the cementation and iron oxide reduction
are broadly synchronous with the latest stages of fault movement.
In: Geology and Resources of the Paradox Basin, Utah
Geological Association, 265-283, 1996.