Authors / CoAuthors
Bain, J.H.C. | Mackenzie, D.E. | Ryburn, R.J.
Abstract
The Kubor Anticline began as a basement fold on the northeast margin of the Australian continental block in Palaeozoic time. It is bounded in the north by the New Guinea Mobile Belt (Bain, 1973; Dow et al 1973), a tectonically active zone within younger continental crust which accreted to the northern edge of the continent in Mesozoic time. Uplift of the northern edge of the older continental block resulted in gravity sliding, folding, and thrusting of the overlying Tertiary and uppermost Mesozoic rocks (Papuan Fold Belt), but the basement and the lower part of the cover rocks were only broadly folded and faulted (e.g. Kubor Anticline). Within the Mobile Belt the rocks are strongly deformed and intensely faulted. The oldest rocks exposed are low-grade greenschists formed by regional metamorphism of sedimentary and volcanic rocks of probable Palaeozoic age (Omung Metamorphics). They crop out only in the core of the Kubor Anticline, where they are intruded by acid to basic large plutons and small stocks (Kubor Granodiorite) of probable Late Permian age.In the west and northeast, the Kubor Granodiorite is conformably overlain by small patches of Upper Permian or Triassic limestone and arkose (Kuta Formation). Upper Triassic dacites and basalts (Kana Volcanics) are also unconformable on the metamorphic and plutonic rocks, but are not in contact with the Kuta Formation.The basement, Kuta Formation, and Kana Volcanics are overlain unconformably by the upper part of the Wahgi Group (about 7000 m of Upper Jurassic to Upper Cretaceous clastic and volcanic rocks), and the same sequence forms the limbs of the anticline.The southern and western limbs of the Kubor Anticline are overlain with paraconformity by upper Palaeocene? mudstone and sandstone (Pima Sandstone) and Eocene-Oligocene limestone (Nebilyer Limestone) respectively. At the east end of the northern limb, the Upper Cretaceous rocks are overlain with slight unconformity by about 300 m of Eocene-Oligocene foraminiferal limestone (Chimbu Limestone), which forms the base of the sequence in the Yaveufa Syncline. The Eocene-Oligocene limestones are everywhere overlain by Miocene limestone or elastics. The Nebilyer Limestone at the western closure of the Kubor Anticline is overlain by fine elastics with interbedded limestone, marl, and mudstone (Aure Beds) which grade southwards into massive shelf limestone (Darai Limestone).The northern limb of the Kubor Anticline is cut by the Bismarck Fault Zone along the southern margin of the New Guinea Mobile Belt. The Bismarck Fault Zone is 20 km wide and consists of a disturbed zone of subparallel anastomosing faults, thrusts, and tight overturned folds. There is at least 3000 m of vertical displacement (north side up) spread over the width of the fault zone in the vicinity of Mount Wilhelm. No economic mineral deposits are known in the Kubor area.
Product Type
document
eCat Id
98
Contact for the resource
Custodian
Owner
Custodian
Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
Canberra
ACT
2601
Australia
Keywords
-
- GA PublicationBulletin
- ( Theme )
-
- geology
-
- PG
- Australian and New Zealand Standard Research Classification (ANZSRC)
-
- Earth Sciences
-
- Published_External
Publication Date
1975-01-01T00:00:00
Creation Date
Security Constraints
Legal Constraints
Status
Purpose
Maintenance Information
unknown
Topic Category
geoscientificInformation
Series Information
Bulletin 155
Lineage
Unknown
Parent Information
Extents
[-7.0, -5.0, 144.0, 145.5]
Reference System
Spatial Resolution
Service Information
Associations
Source Information
Source data not available.