New Zealand Journal of Geology and Geophysics abstracts

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Cretaceous and Cenozoic geology east of the Tinui Fault Complex in northeastern Wairarapa, New Zealand

G. NEEF

Department of Applied Geology
University of New South Wales
Sydney, NSW, 2052
Australia

Abstract  The study area, which has Mataikona in the southeast, lies within the east coast ranges, northeast Wairarapa. The deformed strata are chiefly bathyal and Cretaceous in age, whereas Cenozoic strata have a minor distribution. Deposition of the thick stratigraphic succession was almost continuous, although there were short periods of nondeposition chiefly in the Late Cretaceous, Oligocene, and early Miocene. The oldest strata, the indurated Pahaoa Group, are found in the north of the study area. The Springhill Formation of the Makatote Stream Subgroup which follows is indurated at its base. It is overlain unconformably by turbidite of the Wig Subgroup (comprising the Kipihana and Te Mai Formations). Conformable on the Wig Subgroup is the Tinui Group (composed of the silica-rich Whangai and the organic-rich Waipawa Formations). Cenozoic strata are represented by the Mangatu Group (Wanstead, Weber, and Whakatati Formations) and the Owahanga Group (Coast Road, Greenhollows, Takiritini, Tanawa, and Marainanga Road Conglomerate Formations) and sarsen boulders of Late Southland Series limestone.

The mapped area is cut by eight major NNE-trending faults which were active during the Neogene. The Tinui Fault Complex is the most important fault because it separates Miocene strata in the west from Cretaceous strata in the east. The faults vary from vertical to inclined to the WNW. Thrust sheets, west over east, are developed northeast of Te Mai Station (near Pukeamuku Trig) and near Glenwhai Station, and a klippe is present near Wig Trig in the east.

Sinistral faulting probably occurred along the Tinui Fault Complex during the Late Cretaceous when the Pukeamuka pull-apart basin, which contains >800 m of Whangai strata, formed. Dextral faulting along the Tinui Fault Complex occurred intermittently during Miocene (and may have occurred during the late Eocene) but faulting, on the basis of scarce Late Quaternary fault traces, is now less frequent.

Keywords  stratigraphy; structure; tectonics; geological history; NZMS 260, U25 part AC

New Zealand Journal of Geology and Geophysics, 1995, Vol. 38: 375-394

0028-8306/95/3803-0375 $2.50/0 (c) The Royal Society of New Zealand 1995

PDF file of entire paper: medium quality (6723K); (scanned from paper original: notes about this process)

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