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Shallow-marine, mixed temperate, terrigenouscarbonate sediments are accumulating on the shallow to deep Wanganui shelf (c. 20-110 m water depth). From cluster analysis of textural and compositional parameters, five surficial sediment facies and five subfacies have been defined for the shelf. Facies 1 (Bivalve-bearing [gravelly] sand), is a terrigenous-dominated, shallow shelf facies (<50 m), incorporating Subfacies la (Sand)-a modern felsic sand prism-and lb (Bivalve-bearing volcaniclastic gravelly sand)-modern to relict andesitic detritus and shell fragments. Facies 2 (Skeletal-dominated sandy gravel) comprises sediments containing >50% CaCO 3 , and occurs in the shallow to mid shelf region (c. 30-90 m) where levels of terrigenous input are reduced, and substrates and hydraulic conditions are favourable for carbonate production. Facies 2 comprises Subfacies 2a (Bivalve-dominated sandy gravel), 2b (Bryozoan/bivalve-dominated sandy gravel), and 2c (Bryozoan/bivalve-dominated muddy sandy gravel and gravelly muddy sand). Facies 2 sediments are

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