Stratigraphy and sedimentology of the Coalgate area, Canterbury, New Zealand

Abstract

Abstract Stratigraphic and sedimentologic studies of the Cretaceo-Tertiary sequence overlying Torlesse rocks in the Coalgate area permit a review of the lithostratigraphy of the region. Much new information has come from borehole logs and cores. Coal measures conformably overlain by shallow marine strata and associated igneous rocks, including View Hill Basalt, are assigned to the Eyre Group (modified name) of upper Cretaceous and possibly Paleocene age. Burnt Hill Group (new name) is erected to accommodate some 200 m of Oligocene-Miocene non-calcareous marine, estuarine, and associated igneous rocks of central and northern Canterbury. Formations include: Homebush Standstone (new name for a massive estuarine deltaic deposit) (oldest unit); Thongcaster Formation of Duntroonian age (new name for a fossiliferous clayey fine sandstone); Wairiri Volcaniclastite (new name for a tuff-breccia deposit); Chalk Quarry Sandstone of Waiauan age (modified name); Chalk Hill Clay; Sandpit Tuff (name now formalised) consi...