FN Archimer Export Format PT J TI The Norfolk Ridge: A Proximal Record of the Tonga‐Kermadec Subduction Initiation BT AF Collot, J Sutherland, R. Etienne, S. Patriat, Martin Roest, Walter Marcaillou, B. Clerc, C. Stratford, W. Mortimer, N. Juan, C. Bordenave, A. Schnurle, Philippe Barker, D. Williams, S. Wolf, S. Crundwell, M. AS 1:1;2:2;3:1;4:3;5:3;6:4;7:5;8:6;9:6;10:1;11:1;12:3;13:6;14:7;15:8;16:6; FF 1:;2:;3:;4:PDG-REM-GEOOCEAN-ALMA;5:PDG-REM-GEOOCEAN-ALMA;6:;7:;8:;9:;10:;11:;12:PDG-REM-GEOOCEAN-GIPS;13:;14:;15:;16:; C1 Service Géologique de Nouvelle‐Calédonie (New Caledonia Geological Survey) DIMENC, Nouméa,New Caledonia Victoria University of Wellington, Wellington, New Zealand Université de Brest CNRS Ifremer Geo‐Ocean, Plouzané,France Université Côte d'Azur IRD CNRS Observatoire de la Côte d'Azur Valbonne, France Avignon université UMR 1114 EMMAH, Avignon,France GNS Science, Lower Hutt,New Zealand State Key Laboratory of Continental Dynamics Department of Geology Northwest University, Xían,China Sorbonne Université CNRS‐INSU Institut des Sciences de la Terre Paris ISTeP UMR 7193, Paris ,France C2 DIMENC SERV GEOL NOUVELLE CALEDONIE, FRANCE UNIV WELLINGTON VICTORIA, NEW ZEALAND IFREMER, FRANCE UNIV COTE D'AZUR, FRANCE UNIV AVIGNON, FRANCE GNS SCIENCE, NEW ZEALAND UNIV NORTH WEST, CHINA UNIV SORBONNE, FRANCE SI BREST SE PDG-REM-GEOOCEAN-ALMA PDG-REM-GEOOCEAN-GIPS UM GEO-OCEAN IN WOS Ifremer UMR DOAJ copubli-france copubli-univ-france copubli-int-hors-europe copubli-sud IF 3.5 TC 1 UR https://archimer.ifremer.fr/doc/00825/93662/100440.pdf LA English DT Article CR TECTA VESPA BO L'Atalante AB Norfolk Ridge bounds the northeastern edge of the continent of Zealandia and is proximal to where Cenozoic Tonga-Kermadec subduction initiation occurred. We present and analyze new seismic reflection, bathymetric and rock data from Norfolk Ridge that show it is composed of a thick sedimentary succession and that it was formed and acquired its present-day ridge physiography and architecture during Eocene to Oligocene uplift, emergence and erosion. Contemporaneous subsidence of the adjacent New Caledonia Trough shaped the western slope of Norfolk Ridge and was accompanied by volcanism. Neogene extension along the eastern slope of Norfolk Ridge led to the opening of the Norfolk Basin. Our observations reveal little or no contractional deformation, in contrast to observations elsewhere in Zealandia, and are hence significant for understanding the mechanics of subduction initiation. We suggest that subduction nucleated north of Norfolk Ridge and propagated rapidly along the ridge during the period 40-35 Ma, giving it a linear and narrow shape. Slab roll-back following subduction initiation may have preserved the ridge and created its eastern flank. Our observations suggest that pre-existing structures, which were likely inherited from Cretaceous Gondwana subduction, were well-oriented to propagate rupture and create self-sustaining subduction. Key Points We present new marine geophysical and geological data of Norfolk Ridge located along the northeastern edge of the Zealandia continent We show that the ridge is not inherited from Cretaceous rifting that led to isolation of Zealandia but from the TECTA Cenozoic tectonic event Analysis of the structure and evolution of Norfolk Ridge underpins our understanding of tectonic processes of subduction initiation Plain Language Summary Plate tectonic theory established and proved that the surface of Earth is composed of rigid moving plates, but it remains unclear how and why these plates sometimes re-configure their boundaries and motions. Subduction zones are places where two plates converge and one plunges deep into the Earth beneath the other one. As the plate sinks, it drags the rest of the plate with it and acts as an engine that “pulls” the plate and drives horizontal motion. This is what drives the dynamics of plate tectonics. How are subduction zones created? This remains an open question, but we know from geological observations that new subduction zones do get created: more than half of all active subduction zones were created after the dinosaurs died out 65 million years ago. We present new observations from northern Zealandia (a submerged continent between New Zealand and New Caledonia) that document how one of the largest subduction zones on Earth, the Tonga-Kermadec system, started. PY 2023 PD MAR SO Geochemistry Geophysics Geosystems SN 1525-2027 PU American Geophysical Union (AGU) VL 24 IS 3 UT 000949090200001 DI 10.1029/2022GC010721 ID 93662 ER EF