Authors / CoAuthors
Jaques, A.L. | Robinson, G.P.
Abstract
Recent geological mapping in the north coast ranges of Papua New Guinea has recognised a Paleogene island arc. This arc is believed to have faced southward, and formed at the northeastern boundary of the Indo-Australian plate. The arc collided with continental crust of the Indo-Australian plate to the south; collision is thought to have occurred first in the west in the Early Miocene and to have progressed eastwards. Crustal shortening on collision resulted in foreland-type folding and thrusting at the continental margin, emplacement of ophiolite allochthons from the arc-trench gap at the collision zone, and uplift and fracturing of the accreted arc. Post-collision plate adjustments are thought to include extensive trans- current faulting about the former plate boundary, southward thrusting of part of the arc (Finisterre-Huon block), and extensive faulting in a complex linear zone extending from south of Manus Island through New Ireland and the Solomon Islands. Present-day interaction between the Indo-Australian and Pacific plates is spread over a wide zone in which at least two minor plates are involved. Despite previous claims, plots of the most accurately located earthquake foci define a northward-dipping seismic zone beneath the Late Cainozoic volcanoes at the southern margin of the Bismarck Sea. We find no evidence to substantiate a reversal of arc polarity at any time after the Mid-Tertiary collision. Mid to Late Cainozoic magmatism in central Papua New Guinea appears to have been triggered by uplift inducing partial melting of mantle modified by Cretaceous subduction. The present-day northward-dipping seismic zone is believed to be a vestige of the Early Tertiary subduction zone; the hanging slab is now slowly sinking and equilibrating with the mantle. If northern New Guinea can be considered to be the type example of a continent/island-arc collision then reversal of arc polarity may not be a necessary consequence of such collisions.
Product Type
document
eCat Id
80936
Contact for the resource
Custodian
Owner
Custodian
Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
Canberra
ACT
2601
Australia
Keywords
-
- GA PublicationJournal
-
- PNG
- Australian and New Zealand Standard Research Classification (ANZSRC)
-
- Earth Sciences
-
- Published_External
Publication Date
1977-01-01T00:00:00
Creation Date
Security Constraints
Legal Constraints
Status
Purpose
Maintenance Information
unknown
Topic Category
geoscientificInformation
Series Information
BMR Journal of Australian Geology and Geophysics 2:4:289-303
Lineage
Unknown
Parent Information
Extents
[-12.0, 0.0, 141.0, 156.0]
Reference System
Spatial Resolution
Service Information
Associations
Source Information
Source data not available.