New Caledonia obducted Peridotite Nappe: offshore extent and implications for obduction and post-obduction processes
|Author(s)||Patriat Martin1, 2, Collot Julien2, Etienne Samuel3, Poli Sara1, 2, Clerc Camille4, Mortimer Nick5, Pattier France1, 2, Juan Caroline3, Roest Walter1|
|Affiliation(s)||1 : IFREMER, Unite Geosci Marines, Plouzane, France.
2 : DIMENC, Serv Geol Nouvelle Caledonie, Noumea, New Caledonia.
3 : ZoNeCo Res Program, ADECAL Technopole, Noumea, New Caledonia.
4 : Univ Nouvelle Caledonie, ISEA, Noumea, New Caledonia.
5 : GNS Sci, Dunedin, New Zealand.
|Source||Tectonics (0278-7407) (Amer Geophysical Union), 2018-04 , Vol. 37 , N. 4 , P. 1077-1096|
One of the largest ophiolitic peridotite masses in the world covers a quarter of the island of Grande Terre, New Caledonia. The Peridotite Nappe was obducted during the Eocene, is weakly deformed and corresponds to the highest of a structurally simple pile of thrust nappes. We present new marine seismic data that allows us to track the offshore continuation of the Peridotite Nappe along‐strike for a distance of more than 500 km south of New Caledonia, and to image its pre‐, syn‐ and post‐obduction sedimentary records.
Offshore, the Peridotite Nappe underlies a c. 150‐km wide and 2 km‐deep basin. Flat‐topped horsts of peridotite are clearly bounded by major normal faults; in contrast faults are obscure onland. To the east, the Peridotite Nappe roots along the eastern margin of the Félicité Ridge (new name), a c. 300 x 25 km dome‐shaped ridge, which we interpret as being the southern extension of the HP/LT metamorphic core complex observed in New Caledonia.
Two alternative tectonic models address the relative timing and relationships between Peridotite Nappe emplacement, uplift of a metamorphic core complex, and extensional tectonics. These models provide new ideas for the understanding the formation of the eastern margin of the Zealandia continent. Our results contribute to an understanding of how oceanic mantle is emplaced onto continental margins.