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New Caledonia Obducted Peridotite Nappe: Offshore Extent and Implications for Obduction and Postobduction Processes
Author(s) -
Patriat Martin,
Collot Julien,
Etienne Samuel,
Poli Sara,
Clerc Camille,
Mortimer Nick,
Pattier France,
Juan Caroline,
Roest Walter R.
Publication year - 2018
Publication title -
tectonics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.465
H-Index - 134
eISSN - 1944-9194
pISSN - 0278-7407
DOI - 10.1002/2017tc004722
Subject(s) - geology , peridotite , nappe , obduction , ophiolite , continental margin , mantle (geology) , paleontology , metamorphic core complex , seismology , tectonics , geochemistry , petrology , geomorphology , subduction , oceanic crust , extensional definition
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 allow 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 preobduction, synobduction, and postobduction sedimentary records. Offshore, the Peridotite Nappe underlies a ~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 ~300 × 25 km dome‐shaped ridge, which we interpret as being the southern extension of the high‐pressure/low‐temperature 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.