Orogenic bridge theory: towards a predictive tool for past and future plate tectonics

<ns3:p>Plate tectonics is a centerpiece of Earth’s geodynamics and key to making our planet habitable, natural resources, geohazards and climate change, and the evolution of life. Understanding plate tectonics is increasingly important due to the ongoing energy transition. At the core of plate tectonics, the supercontinent cycle suggests that landmasses repeatedly accrete into supercontinents and then break up during rifting. Thus far, rifting was thought to gradually unzip continents from one another and to be mostly controlled by geodynamic processes (e.g. subduction, mantle plumes). Orogenic Bridge Theory (OrBiT) suggests another first-order factor controlling supercontinent breakup. It states that preexisting orogens perpendicular to active rifts hinder breakup, forcing rifts to adapt, e.g., by jumping, and localizing major transform faults. Orogens take longer to break due to their thickened crust and obliquity of related structures. Thus, while seafloor spreads on either side of rift-orthogonal orogens, extension continues to stretch the orogenic crust until breakup occurs there later. We call these regions of stretched continental crust flanked by oceanic crust “orogenic bridges”. OrBiT implies that the extent of continental crust in the oceans may be underestimated and, thus, that our understanding of plate tectonics is incomplete. OrBiT may help refine future predictions of plate tectonics, e.g. localization of future rifts and transform faults, which are typical sites of natural resources and geohazards. OrBiT is based on a new global correlation of major transform faults with rift-orthogonal orogens and ongoing work at various potential orogenic bridges and continental margins, which are discussed herein. Further testing of this new theory is encouraged.</ns3:p>