Distribution, stratigraphy and stratigraphic relationships of cretaceous sediments, western Raukumara Peninsula, New Zealand

Abstract

Fossiliferous Cretaceous rocks in western Raukumara Peninsula occur as a narrow band along the southern margin of underlying Torlesse Supergroup greywacke rocks and beneath a cover of Tertiary rocks, or as infaulted or erosional outliers within Torlesse Supergroup. A major regional angular unconformity representing the Rangitata Orogeny and subsequent peneplanation of variable duration, separates complexly folded and faulted, mostly steeply dipping, virtually unfossiliferous, indurated greywacke rocks of Torlesse Supergroup from less indurated, open folded, fossiliferous Cretaceous shelf sediments. Cretaceous sequences commence with basal transgressive sandstone and conglomerate ranging in age from Korangan Stage (Aptian) to Haumurian Stage (Maastrichtian). Other unconforrnities, mostly local, are present in Cretaceous sequences, and a second regional unconformity occurs below a Haumurian, and locally Piripauan, transgressive succession. The geographic and stratigraphic distribution of lithofacies, unconformities and the thickness of units during the Cretaceous suggest complex patterns of deposition and erosion possibly in response to faulting and folding in the Torlesse basement. © 1973 Taylor & Francis Group, LLC.