The Patagonian orocline is the 90 ø bend in the southernmost Andes between 50øS and 56øS. Paleomagnetic and structural data indicate that the orocline is, at least in part, the product of tectonic rotation. Recent field work in the Beagle Channel region of southernmost Chile provides evidence for widespread left-lateral strike-slip faulting in the internal zones of the mountain belt. Both arms of the Beagle Channel are interpreted to be left-lateral strike-slip faults based on detailed study of mesoscale strike-slip faults (Riedel shears) observed in coastal outcrops. Although much of the evidence indicates Cenozoic brittle strike-slip faulting, other fabric data, including vertical foliation zones containing horizontal quartz stretching lineations and ductile left-lateral kinematic indicators, suggest that Mesozoic ductile strike-slip or obliqueslip shearing also occurred. The implication is that the mid-Cretaceous Andean orogeny involved the transpressional inversion of the Rocas Verdes marginal basin and that transpression has been the dominant deformational regime in the region for the last 120 Ma. Regional left-lateral strike-slip faults are now recognized in all lithotectonic provinces of the southernmost Andes. A statistical study of regional lineament trends using aerial photographs and satellite imagery suggests that many unstudied lineaments are also strike-slip faults. A new model is proposed that integrates the development of strike-slip faulting and the structural evolution and uplift of the southernmost Andes with the rotational development of the orocline. The Patagonian orocline appears to be the product of broad interplate shearing accommodated by strike-slip faulting, block rotation, and contraction and is probably continuing to evolve today.[ 1991 ] have established that the orocline is, at least in part, a secondary bend due to counterclockwise tectonic rotation. Rotation of the southernmost Andes was first proposed by Wegener [1929] who suggested that the southern tip of South America "lagged behind" as South America drifted westward relative to Africa. More recent theories on the origin of the orocline have similarly proposed that the orocline is a product of regional-scale drag due to broad left-lateral shearing between the South America and Scotia-Antarctic plates [Carey, 1958; Hamilton, 1964; Winslow, 1982]. However, despite the history of common thought on the origin of the orocline, previous studies have not addressed the detailed internal structure of the orocline and the means by which crustal rotation might have occurred.The orocline concept was first proposed by Carey [ 1955] for those sections of mountain belts that have been secondarily bent. Marshak [1988] expanded the orocline concept by distinguishing different types of oroclines and their different kinematic evolutions. Included in Marshak's summary is the concept of a strike-slip orocline, defined as an orocline formed either by drag adjacent to a strike-slip fault, by sigmoidal bending of cover strata above a basement wre...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.