The Geology of the Monkey Face area, Marlborough, with special reference to the Mesozoic strata.

Crampton, JS

The Mesozoic stratigraphy of the Monkey Face area, Marlborough, consists of ?Late Jurassic Torlesse Supergroup rocks overlain unconformably by the terrestrial to shallow marine Arowhanan Stage Bluff Sandstone Member of the Gridiron Formation. Lying with inferred disconformity on this is the shallow marine ?Haumurian Conway Siltstone. Another disconformity marks the base (?Waipawan Stage) of the Amuri Limestone Formation. The top of the Amuri Limestone is not present, and a small block of Altonian siltstone (Waikari Formation) is fault-bounded.
The Torlesse Supergroup sandstone is interpreted as having derived largely from recycling of older low-grade Torlesse rocks. Mineralogical and textural maturity of the sediments increases into the Gridiron Formation and Conway Siltstone and indicates continued reworking of this terrane. In addition muscovites in the Conway Siltstone and Waikari Formation document erosion of a schist provenance inferred to be uplifted Torlesse.
Folds and faults (reverse, normal, and strike slip) are a consequence of dextural movement on the Hope Fault just to the north of the Monkey Face area.

v. 61 p. ill. Photos. Map (folded in pocket). 30 cm.

1985Crampton

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