Tectonic influence on the characteristics of contourite systems

Tectonic influence on bottom current processes, particularly in active margin settings, may result in contourite deposits that are morphologically distinct from those developed along passive margins. Despite numerous works on the role of tectonics in the development of contourites deposits and the evolution of water mass circulation, there remains limited consensus on standardised criteria for the identification and characterisation of contourite drifts. The aim of our study is to distinguish the various tectonic controls on contourite deposition through a comprehensive review of existing knowledge, supported by morphologic characterisation, morphometric quantification, and statistical analysis of the dimensional relationship between structural and contourite features. We present three representative analogues from the South China Sea that illustrate depositional, erosional, and mixed features of both its modern and ancient contourite systems, and compare them with the well-known Gulf of Cádiz contourite systems. Tectonically-influenced contourite systems can be classified into three categories based on structural control: confined , fault-controlled , and obstacle-controlled drifts . The associated tectonic structures and movements—such as uplift and subsidence—affect both the external geometry and internal configuration of the drifts. To better capture the complexity of tectonic influence on contourite deposition, several conceptual models are summarised for each type of structural control, and a revised classification framework for contourite drifts is proposed. Regional tectonic evolution also plays a crucial role in contourite development, governing their evolutionary phases— onset , growth , and buried -stages. Their long-term evolution is further influenced by global events associated with reconfiguration of oceanic gateways and changes in circulation patterns, driven by the coupling of astronomical and tectonic processes and modulated by orbital-scale variations in bottom current activity. The role of tectonics in contourite deposition carries significant geological implications—contourite drift architecture, sedimentary facies distribution, sediment supply and accommodation, seafloor stability and geohazards—as well as economic relevance to the energy sector and marine ecosystems.