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Date Permissions Signed


Date of Award

Summer 1990

Document Type

Masters Thesis

Degree Name

Master of Science (MS)



First Advisor

Kelsey, H. M.

Second Advisor

Cashman, Susan M.

Third Advisor

Talbot, James L.


Development of the Ohara Depression and uplift of the Ruahine and Wakarara Ranges followed an increase of the convergence rate between the Pacific and Australian plates. The Ohara Depression is a trough of Plio-Pleistocene sediments that crops out between the Ruahine and Wakarara Ranges. Two episodes of uplift during the late Pliocene and Pleistocene are recorded in the geologic record. Initial uplift occurred in the late Pliocene followed by subsidence through the early Pleistocene. The greatest uplift occurred during the mid-Pleistocene, and is recorded by deposition of a 200-250 m-thick conglomerate unit. Although compressional structures are present within and to the east of the Ohara Depression, there is a partitioning of strain between the eastern front of the Wakarara Range and the Ohara Depression. Coast-perpendicular shortening dominates along the eastern Wakarara Range front and translation accompanied by coast-parallel shortening occurs within the Ohara Depression and along the Ruahine and Mohaka faults. Within the northern Ohara Depression, the Big Hill fault transfers motion from the Ruahine fault to the Mohaka fault. The Mohaka fault serves as a boundary between the two strain domains, shielding the part of the Ohara Depression west of the Wakarara Range from contraction.




Plio-Pleistocene sediments, Ohara Depression, Ruahine Range, Wakarara Range


Western Washington University

OCLC Number


Subject – LCSH

Geology, Stratigraphic--Pliocene; Geology, Stratigraphic--Pleistocene; Sedimentary rocks--New Zealand--North Island; Plate tectonics--New Zealand--North Island; Geology--New Zealand--North Island

Geographic Coverage

North Island (N.Z.)




masters theses




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