Lithosphere delamination with foundering of lower crust and mantle caused permanent subsidence of New Caledonia Trough and transient uplift of Lord Howe Rise during Eocene and Oligocene initiation of Tonga-Kermadec subduction, western Pacific
|Author(s)||Sutherland Rupert1, Collot Julien2, 3, Lafoy Yves3, Logan Graham A.4, Hackney Ron4, Stagpoole Vaughan1, Uruski Chris1, Hashimoto Takehiko4, Higgins Karen4, Herzer Richard H.1, Wood Ray1, Mortimer Nick5, Rollet Nadege4|
|Affiliation(s)||1 : GNS Sci, Lower Hutt 5040, New Zealand.
2 : IFREMER, Ctr Brest, Dept Geodynam & Geophys, F-29280 Plouzane, France.
3 : Direct Ind Mines & Energie Nouvelle Caledonie, Serv Geol Nouvelle Caledonie, Noumea 98845, New Caledonia.
4 : Geosci Australia, Canberra, ACT 2601, Australia.
5 : GNS Sci, Dunedin 9016, New Zealand.
|Source||Tectonics (0278-7407) (American Geophysical Union), 2010-03 , Vol. 29 , N. TC2004 , P. 1-16|
|WOS© Times Cited||52|
|Keyword(s)||norfolk ridge system, back arc extension, new zealand region, south fiji basin, sw pacific, northland plateau, tasman sea, seismic stratigraphy, geodynamic ecolution, tectonic evolution|
|Abstract||We use seismic reflection and rock sample data to propose that the first-order physiography of New Caledonia Trough and Norfolk Ridge formed in Eocene and Oligocene time and was associated with the onset of subduction and back-arc spreading at the Australia-Pacific plate boundary. Our tectonic model involves an initial Cretaceous rift that is strongly modified by Cenozoic subduction initiation. Hence, we are able to explain (1) complex sedimentary basins of inferred Mesozoic age; (2) a prominent unconformity and onlap surface of middle Eocene to early Miocene age at the base of flat-lying sediments beneath the axis of New Caledonia Trough; (3) gently dipping, variable thickness, and locally deformed Late Cretaceous strata along the margins of the trough; (4) platform morphology and unconformities on either side of the trough that indicate a phase of late Eocene to early Miocene uplift to near sea level, followed by rapid Oligocene and Miocene subsidence of similar to 1100-1800 m; and (5) seismic reflection facies tied to boreholes that suggest absolute tectonic subsidence at the southern end of New Caledonia Trough by 1800-2200 m since Eocene time. The Cenozoic part of the model involves delamination and subduction initiation followed by rapid foundering and rollback of the slab. This created a deep (>2 km) enclosed oceanic trough, similar to 2000 km long and 200-300 km across, in Eocene and Oligocene time as the lower crust detached, with simultaneous uplift and local land development along basin flanks. Disruption of Late Cretaceous and Paleogene strata was minimal during this Cenozoic phase and involved only subtle tilting and local reverse faulting or folding. Basin formation was possible through the action of at least one detachment fault that allowed the lower crust to either be subducted into the mantle or exhumed eastward into Norfolk Basin. We suggest that delamination of the lithosphere, with possible mixing of the lower crust back into the mantle, is more widespread than previously thought and may be commonly associated with subduction initiation, such as Cenozoic events in the Mediterranean and western Pacific.|