Abstract
AbstractStratal stacking patterns and termination relationships of Upper Cretaceous and Paleogene strata of Aotea Basin, which is at the southern end of New Caledonia Trough and adjacent to Taranaki Basin, are used to infer vertical movements before, during, and after Tonga‐Kermadec subduction initiation. Regional 2D seismic‐stratigraphic units are tied to petroleum exploration wells, including recently drilled Romney‐1. We identify: (a) an uppermost Cretaceous to Paleocene (70–56 Ma) aggradational shelf sequence, with at least two regressional events linked to eustatic sea‐level falls; (b) a diachronous deepening of the basin from shelfal to bathyal environments, that progressed northwest to southeast during the early to middle Eocene (53–46 Ma); (c) that was contemporaneous with small‐scale volcanism; (d) a brief phase of middle to late Eocene (46–35 Ma) delta development at the western basin margin (Challenger Plateau) that is evidence for local uplift; and (e) an onlapping sequence deposited since the latest Eocene (35–0 Ma) that requires ∼1,300 m of subsidence at the western margin. Paleogeographic maps and a generalized stratigraphic chart summarize our observations. The Eocene phase of tectonic subsidence, uplift, and diffuse volcanism (53–46 Ma) was a precursor to plate motion at the Cenozoic plate boundary through New Zealand and suggests a causal relationship between prearc subsidence, Tonga‐Kermadec subduction initiation, and plate motion change. Delamination of lower crust beneath Aotea Basin during initial subducted slab formation might explain our observations.
Published Version
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