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Petrological and Geophysical Characterization of Exhumed Subcontinental Mantle from the Australian-Antarctic Ocean-Continent Transition Zone

The final lithospheric breakup of the Australian-Antarctic rift system remains controversial due to sparse geological constraints on the nature of the basement along the ocean-continent transition zones. We present new interpretations of multichannel seismic reflection transects, as well as new petrological data of dredged mantle rocks along the East Antarctic margin (Seamount B, offshore Terre Adélie). By combining both datasets, we show that a 50–100 km wide domain of cold (900°C), fertile subcontinental mantle was exhumed along the non-volcanic Antarctic margin. The dredged peridotites preserve characteristics similar to mantle xenoliths found in syn- to post-rift volcanism at the eastern end of the Australian margin (Victoria and Tasmania), indicating the sampling of a common fertile subcontinental mantle during rifting between Australia and Antarctica. Seamount B represents the initial stages of exhumation of cold subcontinental lithosphere along an ocean-continent transition during rifting. This thick mantle domain was likely affected by syn-rift melt impregnation at high-pressure (8 kbar), leading to the formation of plagioclase-pyroxenites. Overall, the combination of continental rifted blocks, a 50-100 km wide domain of volcanic-poor subcontinental mantle and (ultra)-slow spreading implies that ocean-continent transition zones along the Australian-Antarctic margins represent a recent analogue to ocean continent transition zones from the Jurassic Western Tethys. Additionally, evidence of syn-rift melt stagnation at high pressure suggests that magmatism along the Australian-Antarctic rifted margins was sufficient to form magnetic anomalies that can be used as isochrons despite their formation in lithosphere other than mature, steady-state ocean crust.

Simple

Identification info

Alternate title
Supplementary materials to "Revisiting the Australian-Antarctic Ocean-Continent Transition Zone using Petrological and Geophysical Characterization of Exhumed Subcontinental Mantle"
Date (Creation)
2020-02-25
Date (Publication)
2020-02-25

Principal investigator

Institute for Marine and Antarctic Studies (IMAS), University of Tasmania (UTAS) - McCarthy, Anders
IMAS - Hobart
Private Bag 129
Hobart
Tasmania
7001
Australia
ORCID ID >

Principal investigator

Institute for Marine and Antarctic Studies (IMAS), University of Tasmania (UTAS) - Sauermilch, Isabel
IMAS - Hobart
Private Bag 129
Hobart
Tasmania
7001
Australia
ORCID ID >

Credit
A.M. acknowledge the support of SNSF grant P2LAP2_171819. I.S. was supported under Australian Research Council's Special Research Initiative for Antarctic Gateway Partnership (Project ID SR140300001). J.M.W. acknowledges support from Australian Research Council grant DP180102280. We are also grateful to the support from the SCAR community as well as to Dr. M. Yuasa of the Geological Survey of Japan for having carried out the initial studies on Seamount B. The seismic reflection data is freely available through the Seismic Data Library System of SCAR and geochemical analyses of minerals are accessible in the supporting information data set.
Status
Completed

Principal investigator

Institute for Marine and Antarctic Studies (IMAS), University of Tasmania (UTAS) - McCarthy, Anders
IMAS - Hobart
Private Bag 129
Hobart
Tasmania
7001
Australia
ORCID ID >

Point of contact

Institute for Marine and Antarctic Studies (IMAS), University of Tasmania (UTAS) - Sauermilch, Isabel
IMAS - Hobart
Private Bag 129
Hobart
Tasmania
7001
Australia
ORCID ID >

Topic category
  • Geoscientific information

Extent

N
S
E
W


Temporal extent

Time period
2020-02-25 2030-12-31
Maintenance and update frequency
Not planned
Keywords (Theme)
  • Seismic transects along Terre Adélie (East Antarctica) indicate a 50-100 km wide domain of exhumed subcontinental mantle
  • Seamount B likely records MORB-impregnation of subcontinental mantle at high pressures (>8 kbar)
NASA/GCMD Keywords, Version 8.5
  • EARTH SCIENCE | SOLID EARTH | ROCKS/MINERALS/CRYSTALS
  • EARTH SCIENCE | OCEANS | MARINE GEOPHYSICS | MAGNETIC ANOMALIES
  • EARTH SCIENCE | OCEANS | BATHYMETRY/SEAFLOOR TOPOGRAPHY | CONTINENTAL MARGINS
Australian and New Zealand Standard Research Classification (ANZSRC): Fields of Research
  • Marine Geoscience
  • Tectonics

Resource constraints

Classification
Unclassified

Resource constraints

Use limitation
The data described in this record are the intellectual property of the University of Tasmania through the Institute for Marine and Antarctic Studies.

Resource constraints

Linkage
http://i.creativecommons.org/l/by/4.0/88x31.png

License Graphic

Title
Creative Commons Attribution 4.0 International License


>

Website
http://creativecommons.org/licenses/by/4.0/

License Text

Other constraints
The citation in a list of references is: citation author name/s (year metadata published), metadata title. Citation author organisation/s. File identifier and Data accessed at (add http link).
Language
English
Character encoding
UTF8

Distribution Information

Distribution format
OnLine resource
DATA ACCESS - Petrological and Geophysical Characterization of Exhumed Subcontinental Mantle [direct download]

Resource lineage

Statement
This Dataset contains mineral chemistry (major and trace elements) of plagioclase, olivine, spinel, orthopyroxene, clinopyroxene and amphibole from dredged samples from Seamount B (offshore Terre Adélie, Japanese dredging expeditions TH91, TH95).
Hierarchy level
Dataset

Metadata

Metadata identifier
5086b536-6b2a-4244-992e-b4f2ae46822e

Language
English
Character encoding
UTF8

Publisher

Institute for Marine and Antarctic Studies (IMAS), University of Tasmania (UTAS) - IMAS Data Manager

Type of resource

Resource scope
Dataset
Metadata linkage
https://metadata.imas.utas.edu.au/geonetwork/srv/eng/catalog.search#/metadata/5086b536-6b2a-4244-992e-b4f2ae46822e

Point of truth URL of this metadata record

Date info (Creation)
2020-08-14T12:02:00
Date info (Revision)
2020-08-14T12:02:00

Metadata standard

Title
ISO 19115-3:2018
 
 

Overviews

Spatial extent

N
S
E
W


Keywords

Seamount B likely records MORB-impregnation of subcontinental mantle at high pressures (>8 kbar) Seismic transects along Terre Adélie (East Antarctica) indicate a 50-100 km wide domain of exhumed subcontinental mantle
Australian and New Zealand Standard Research Classification (ANZSRC): Fields of Research
Marine Geoscience Tectonics
NASA/GCMD Keywords, Version 8.5
EARTH SCIENCE | OCEANS | BATHYMETRY/SEAFLOOR TOPOGRAPHY | CONTINENTAL MARGINS EARTH SCIENCE | OCEANS | MARINE GEOPHYSICS | MAGNETIC ANOMALIES EARTH SCIENCE | SOLID EARTH | ROCKS/MINERALS/CRYSTALS

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