Eocene tectonic compression in northern Zealandia; magneto-biostratigraphic constraints from the sedimentary records of New Caledonia (southwest Pacific Ocean)

Author(s): Dallanave, Edoardo; Agnini, Claudia; Pascher, Kristina M.; Maurizot, Pierre; Bachtadse, Valerian; Hollis, Christopher John; Dickens, Gerald R.; Collot, Julien; Sevin, Brice; Strogen, Dominic; Monesi, Edoardo
Author Affiliation(s): Primary:
Ludwig Maximilians University of Munich, Munich, Germany
University of Padua, Padua, Italy
GNS Science, Lower Hutt, New Zealand
Geological Survey of New Caledonia, New Caledonia
Ludwig Maximilians University, Germany
Rice University, United States
University of Milan, Italy
Volume Title: AGU 2017 fall meeting
Source: American Geophysical Union Fall Meeting, Vol.2017; American Geophysical Union 2017 fall meeting, New Orleans, LA, Dec. 11-15, 2017. Publisher: American Geophysical Union, Washington, DC, United States
Note: In English
Summary: Published seismic profiles acquired from the Tasman Sea and northern Zealandia area (southwest Pacific) point to a widespread Eocene convergent deformation of oceanic and continental crust, with reverse faults and uplift (Tectonic Event of the Cenozoic in the Tasman Area; TECTA). The TECTA is interpreted as the precursor of the Tonga-Kermadec subduction initiation. Grande Terre is the main island of the New Caledonia archipelago and the largest emergent portion of northern Norfolk Ridge (part of northern Zealandia). Eocene sedimentary records exposed in Grande Terre contain a transition from pelagic micrite to terrigenous-rich calciturbidites, marking a shift from passive margin to convergent tectonic regime. This could represent the local expression of the convergence inception observed on a regional scale. We conducted an integrated magneto-biostratigraphic study, based on calcareous nannofossil and radiolaria, of two early-middle Eocene records cropping out near Noumea (southwest Grande Terre) and Koumac (northwest Grande Terre). The natural remanent magnetization of the sediments is complicated by multiple vector components, likely related to the late Eocene obduction, but a characteristic remanent magnetization has been successfully isolated. Overall the record spans from magnetic polarity Chron C23n to C18n, i.e. from ∼51 to 39 Ma. In this robust magnetic polarity-based chronological frame, the pelagic micrite to terrigenous-rich calciturbidites occurred near the top of Chron C21n and is dated 46 Ma. Furthermore, the magnetic mineral assemblage within part of the calciturbidites consists of hematite associated with maghemite. This association indicates emergent land as source of the terrigenous, suggesting a considerable uplift. Because 94% of the Zealandia continent is submerged, ocean drilling is needed to gauge the full extent and timing of Eocene compressive deformation revealed by the seismic profiles acquired in the Tasman area. This is a primary aim of International Ocean Discovery Program (IODP) Expedition 371 (27th July - 26th September 2017).
Year of Publication: 2017
Research Program: IODP2 International Ocean Discovery Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Australasia; Cenozoic; Compression tectonics; Eocene; Expedition 371; International Ocean Discovery Program; New Zealand; Pacific Ocean; Paleogene; South Pacific; Southwest Pacific; Tectonics; Tertiary; West Pacific; Zealandia
Coordinates: S373400 S262900 E1712100 E1601800
Record ID: 2019058559
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