Abstract
AbstractSubduction of oceanic plateaux are events that have occurred infrequently in Earth's history. Although rare, these events are thought to considerably influence regional tectonics and global plate motions. In the mid‐Cretaceous the oceanic Hikurangi Plateau collided with the formerly active East Gondwana margin: An event which falls into the same of a sudden change from subduction to extensional processes, including graben formation, development rift basin development, and exhumation of metamorphic core complexes in the Zealandia continent as well as a global‐scale plate reorganization event. In this study, we use recently acquired seismic refraction and gravity data along one profile across the submarine Chatham Rise, which represent a former accretionary wedge of the East Gondwana subduction zone. We demonstrate that the southward extent of the subducted Hikurangi Plateau in the lower crust beneath the submarine Chatham Rise along our profile is only ~150. This is ~150 km less than the previously suggested extent. Furthermore, we interpret that a slice of the subducted Phoenix Plate remains attached to the southern edge of the Hikurangi Plateau. We suggest that cessation of subduction in response to the Hikurangi Plateau jamming as well as the rollback and detachment of the Phoenix Plate slab played an important role in the changing tectonic forces across Zealandia in mid‐Cretaceous. Moreover, we suggest that the subduction cessation along the Hikurangi Plateau segment led to the fragmentation of the Gondwana subduction zone and Phoenix Plate, which significantly influenced and potentially prolonged the global mid‐Cretaceous plate reorganization event.
Highlights
IntroductionTwo well‐studied, but contradictory, examples of the influence of oceanic plateaux on regional and global tectonics include (a) the still ongoing collision of the Ontong Java Plateau with the Melanesian arc, which led to partial subduction and crustal accretion (Mann & Taira, 2004; Taira et al, 2004) and (b) the Late Cretaceous lithospheric removal of a subducted oceanic plateau beneath western North America, which led to regional‐scale surface rebound and, thereby, initiated the Laramide Orogeny in North America (Liu et al, 2010)
The formation of oceanic plateaux—extraordinarily thick oceanic crust primarily resulting from primarily basaltic magmatism—is considered to be the most extreme volcanic events on Earth
We suggest that cessation of subduction in response to the Hikurangi Plateau jamming as well as the rollback and detachment of the Phoenix Plate slab played an important role in the changing tectonic forces across Zealandia in mid‐Cretaceous
Summary
Two well‐studied, but contradictory, examples of the influence of oceanic plateaux on regional and global tectonics include (a) the still ongoing collision of the Ontong Java Plateau with the Melanesian arc, which led to partial subduction and crustal accretion (Mann & Taira, 2004; Taira et al, 2004) and (b) the Late Cretaceous lithospheric removal of a subducted oceanic plateau beneath western North America, which led to regional‐scale surface rebound and, thereby, initiated the Laramide Orogeny in North America (Liu et al, 2010). Oceanic plateau collision and subduction are capable of triggering both far‐field and local tectonic effects
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