Transfer zones provide a mechanism by which displacement is maintained across a fold and thrust belt where a single thrust terminates along strike. Commonly, the transfer is not simply a “lap joint” wherein en echelon thrusts, tied to a common sole fault, shift displacement; rather, these zones are structurally complex with intensified folding, fracturing, and, in some instances, cleavage. An example occurs in the Valley and Ridge of eastern Tennessee, northeast of Knoxville. There, the Beaver Valley thrust terminates into folded Middle Ordovician carbonates. To the southeast, the adjacent Saltville thrust increases in stratigraphic separation, coinciding with the Beaver Valley termination. The Saltville places Lower Cambrian strata on Mississippian units northeast of the fault termination, whereas the Lower Cambrian rests on Cambrian-Ordovician rocks only 20 km to the southwest.

Near its tip, the Beaver Valley thrust shows little displacement, but the loss of slip is accompanied by intensified folding. The folding traces an anticlinorium involving Middle and Upper Ordovician carbonates and shales. These folded rocks are broken by fractures and extensional veins, commonly filled with sparry twinned calcite, and ranging from 0.2 to 2.0 mm wide. One set of veins is generally normal to bedding with a second set oblique; in some cases, three sets cut the rock. Also, Middle Ordovician carbonates carry an axial planar solution cleavage, and catacalcites are locally developed, particularly in dolostones of the Cambrian-Ordovician Knox Group. A set of folds, the axes of which are oblique to transport direction, occurs across the transfer zone; they are often found in the footwall of a thrust.

The complex structural geometries in these thrust sheets suggest contradictory timing relationships. The contradiction is explained if the two faults are envisioned as propagating from initial breaks, then growing toward one another contemporaneously. This example demonstrates the potential complexity of a transfer zone, as well as the possibility of apparent local variation in fault sequence in a generally hinterland to foreland progression of emplacement.

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