Unraveling the tectonic signatures of thin and thick oroclines through a global catalogue

Oroclines are orogenic belts that have been subjected to bending and are a common feature of mountain ranges worldwide. Despite their widespread occurrence, there is ongoing debate surrounding the geodynamic processes responsible for their development. Specifically, there is uncertainty as to whether these orogens involve upper-crustal (i.e, thin-skinned) or large-scale lithospheric (i.e., thick-skinned) deformation, as well as whether their curvature evolves contemporaneously with mountain growth (i.e., progressive orocline) or post-orogenesis (secondary orocline). Such spatial and temporal deformation means that unraveling the tectonic signature of oroclines may significantly enhance our understanding of orocline formation and provide broader insight into the evolution of mountain systems and convergent plate boundaries worldwide. 

Given the widespread occurrence of oroclines, identifying their tectonic signatures requires analyzing their attributes and geodynamic framework within a global context. However, oroclines have primarily been studied individually - which presents a challenge for their comparison. To address this, we present a global catalogue of oroclines and their tectonic signatures based on map-view characteristics, structural deformation style (e.g., thin- or thick-skinned), and kinematic classification (e.g., primary arc, progressive or secondary orocline).  

Our catalogue is generated by analyzing published literature and newly derived data on orocline attributes, collating 30+ oroclines from around the world. Within our dataset, we observe a wide range of tectonic characteristics, including curve lengths, width-to-length ratios, and interlimb angles. However, we also find a specific signature for oroclines that are classified as thin-skinned or thick-skinned – allowing for a clear identification of such geodynamic processes within our catalogue. In our study, we provide an orocline classification system based on the tectonic signatures highlighted in our dataset. This classification system and identified signatures may have several implications for our understanding of lesser-studied oroclines and the evolution of mountain systems worldwide.