Late Miocene to Pliocene palaeogeography of Viti Levu, Fiji Islands
Abstract The island of Viti Levu is located on the Fiji Platform in an area that has been tectonically active since at least the Late Eocene. The geological history of Viti Levu during this time is one of the competing influence of tectonics, volcanism and eustatic sea-level change in shaping the preserved stratigraphic, and therefore palaeogeographic record. The focus of this paper is the palaeogeographic evolution of Viti Levu from the period following the deformation of the Tuva Group and all older rock units of the Vityaz arc (around 7.5 Ma) to the present. Initial sedimentation during following the deformational event was influenced by the sinistral oblique-slip deformation associated with anticlockwise rotation of the platform. This tectonically dominated period of island evolution saw the establishment of a number of sedimentary basins, many of which continued to receive sediments through until at least the earliest Pliocene. From 6.5 Ma onward, volcanic activity became the main influence on the stratigraphic record, although evidence for major eustatic events (Miocene–Pliocene boundary) are recorded in some sequences. Toward the end of the Early Pliocene, tectonic uplift of Viti Levu resulted in a poor geological record for this time. The Quaternary stratigraphic record reflects relatively minor, mostly eustatic events in coastal areas around major river systems.