Basin yoking: Mechanisms, examples, and significance from the Appalachian area of North America

ABSTRACT Basin yoking is a theoretical concept originally proposed to explain the merging of a foreland basin with a nearby intracratonic basin via interaction of long-wavelength, crustal sinusoids formed in response to flexural deformational loading in a nearby orogen. Although models showed that the process is a likely consequence of flexural mechanisms accompanying major orogenies, the concept of basin yoking has received little attention. Herein, we show and classify five examples of basin yoking related to the Taconian, Acadian, and Neoacadian orogenies in the Appalachian orogen. Original models suggested that yoking is a viscoelastic response to flexural movement in deeper, warmer, less viscous parts of the crust, but examples from the Appalachian region suggest that flexural reactivation of older basement structures may be more important in facilitating and sustaining basin yoking in upper, brittle parts of the crust. The Appalachian region exhibits three types of yoking: multistructure yoking, involving structures of diverse origins and orientations; single-structure yoking, involving down-drop motion along a single graben-like complex of basement structures of similar origin and orientation; and foreland basin–foreland basin yoking, without structural influence. Most yoking occurs during stages of maximum foreland-basin subsidence during which marine black shale is deposited, and such yoking is a significant mechanism in extending the deposition of resource-rich black shales into adjacent basins. However, unlike the structurally related yoking, yoking between two foreland basins seems to produce results that are unique to the timing, location, and phase of flexure for each basin.