MODELING DUPLEX KINEMATICS USING NEW FIELD MAPPING IN THE MOUNTAIN CITY WINDOW, EASTERN TENNESSEE

The Limestone Cove region of the Mountain City Window in eastern Tennessee contains a classic example of a foreland-dipping duplex geometry. This type example is key to our understanding of structural kinematics in duplex settings with high fault slip relative to fault spacing. Existing maps in the area are of varied scale and detail, with significant discrepancies in fault location, branching, and termination patterns. New field mapping in the Chestoa, Erwin, Unicoi, and Huntdale Quadrangles resolves discrepancies of fault location and provides significantly improved detail of bedding strike/dip data. Mapping focuses on a southeast-northwest transect including the Nolichucky River and nearby trails, roads, and streams between the Tennessee – North Carolina border and Bumpass Cove. Map data reveal the pattern of thrust repetition of the Ocoee Series, Chilhowee Group, Shady Dolomite, and Rome Formation. Unit dips range from approximately 50 to 80° to the northwest (the foreland) in the southeastern portion of the transect and are repeated by three foreland-dipping thrusts. In the northwest, units transition through a map-scale syncline and dip 20 to 50° to the southeast, repeated by two hinterland-dipping thrusts. These structural data provide new constraints on duplex kinematics in settings where previous models required estimation due to nonlayer-parallel slip and unit thickness change. Structural modeling conducted in both Adobe Illustrator and Move reveals the pattern of imbrication and rotation of duplexes toward the foreland. This modeling based on new field data provides improved constraint on predicting highly imbricated duplex geometries in a wide variety of settings. Additional planned field mapping in the Unicoi and Iron Mountain Gap Quadrangles will further resolve existing map discrepancies of fault geometry and the implied kinematics by examining fault termination and branching patterns along strike within this same duplex.