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Durham University

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Publication details

Franzel, Maximilian & Back, Stefan (2019). Three-dimensional seismic sedimentology and stratigraphic architecture of prograding clinoforms, central Taranaki Basin, New Zealand. International Journal of Earth Sciences 108(2): 475-496.

Author(s) from Durham

Abstract

Three-dimensional (3D) seismic-reflection analysis of a major Miocene-to-Pleistocene (c. 19–2 Ma) clinoform succession of the central Taranaki Basin offshore New Zealand reveals two distinct intervals of downbuilding progradation (c. 7.5–6 Ma; and c. 4–2 Ma). Downbuilding clinoforms are of kilometre scale and characterized by straight upper foreset gullies that initiate near or at the clinoform breakpoint, in places connected to topset distributary channels. Foreset mass-transport complexes occur mainly in the basal parts of downbuilding clinoform successions. Upbuilding progradational clinoforms formed between c. 6–5.5 Ma and c. 4.5–4 Ma. These clinoforms are generally smaller, with topsets in places comprising beach ridges and tidal channels. The foresets of the upbuilding clinoforms contain large gullies and sinuous deepwater channels, locally connected to topset channels. Retrogradational deposits in the studied succession (c. 5.5–4.5 Ma) lack a distinct clinoform geometry, show a few slope channels and gullies, and are characterized by extensive landward-stepping networks of shallow-marine and fluvial channels. 3D seismic-reflection analysis of the c. 2000 km2 study area allows an exemplary 3D documentation of migrating depositional systems along a highly progradational clastic margin, constrained by a stratigraphic framework tightly defined by the two intervals of major depositional downbuilding. The Late Miocene downbuilding is interpreted as forced by tectonic uplift along the Cape Egmont fault and neighbouring structures in the south of the study area. In contrast, the Plio-Pleistocene downbuilding is interpreted as dominantly controlled by eustasy in a tectonic environment characterized by subsidence. Excellent preservation of the 4–2 Ma clinoform topsets provides unique insights into depositional systems at and above the shelf break imaging palaeo-shoreline and palaeo-backshore environments. The detailed 3D clinoform analyses presented contribute to the understanding of clastic sedimentation processes from shelf to slope, which can be used to predict deepwater depositional facies.