Abstract

We use seismic-reflection and rock-sample data to propose that the first-order physiography of New Caledonia Trough and Norfolk Ridge formed in Eocene to Miocene time, and was associated with the onset of subduction and back-arc spreading at the Australia-Pacific plate boundary. Our tectonic model involves an initial Cretaceous rift that is strongly modified by Cenozoic subduction initiation and hence we are able to explain: complex sedimentary basins of inferred Mesozoic age; a prominent unconformity and onlap surface of Middle Eocene to Early Miocene age at the base of flat-lying sediments beneath the axis of New Caledonia Trough; gently-dipping, variable thickness, and locally deformed Late Cretaceous strata along the margins of the trough; platform morphology and unconformities on either side of the trough that indicate a phase of Late Eocene to Early Miocene uplift to near sea level, followed by rapid Oligocene and Miocene subsidence of c. 1100-1800 m; and seismic-reflection facies tied to boreholes that suggest absolute tectonic subsidence at the southern end of New Caledonia Trough by 1800-2200 m since Eocene time. The Cenozoic part of the model involves delamination and subduction initiation followed by rapid foundering and rollback of the slab. This created a deep (>2 km) enclosed oceanic trough c. 2000 km long and 200-300 km across in Eocene and Oligocene time as the lower crust detached, with simultaneous uplift and local land development along basin flanks. Disruption of Late Cretaceous and Paleogene strata was minimal during this Cenozoic phase and involved only subtle tilting and local reverse faulting or folding. Basin formation was possible through the action of at least one detachment fault that allowed the lower crust to either be subducted into the mantle or exhumed eastward into Norfolk Basin. We suggest that delamination of the lithosphere, with possible mixing of the lower crust back into the mantle, is more widespread than previously thought.
Google map showing geographic bounding box with values North bound -13.75 East bound 175.0 West bound 156.0 South bound -35.0
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Product Type/Sub Type

dataset - External Publication - Scientific Journal Paper

Constraints

license
Creative Commons Attribution 3.0 Australia Licence

IP Owner

Commonwealth of Australia (Geoscience Australia)

Author(s)

Date (publication)

2010

Product Type

dataset

Topic Category

geoscientificInformation

Keywords

External Publication
Scientific Journal Paper
sedimentary basins
plate tectonics
geophysics
geodynamics
continental margins
Earth Sciences

Resource Language

English

Resource Character Set

utf8

Resource Security Classification

unclassified

Geographic Extent

North bound
-13.75
East bound
175.0
West bound
156.0
South bound
-35.0

Lineage

Unknown

Digital Transfer Options

onLine

Distributor

Role
distributor
Organisation Name
Geoscience Australia
City
Canberra
Administrative Area
ACT
Postal Code
2601
Country
Australia
Email Address

Metadata File Identifier

a05f7892-ecfb-7506-e044-00144fdd4fa6

Metadata Standard Name

ANZLIC Metadata Profile: An Australian/New Zealand Profile of AS/NZS ISO 19115:2005, Geographic information - Metadata

Metadata Standard Version

1.1

Metadata Date Stamp

2009-07-30

METADATA SECURITY CLASSIFICATION

unclassified

Metadata Contact

Role
pointOfContact
Organisation Name
Geoscience Australia
City
Canberra
Administrative Area
ACT
Postal Code
2601
Country
Australia
Email Address
Related Links
For information on acquiring this product,
please contact the Geoscience Australia Sales Centre via:

fax:
+61 2 6249 9960; or
phone:
1800 800 173 (within Australia);
 
+61 2 6249 9966 (outside Australia).

Please note that support hours are 9 am to 5 pm weekdays