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Record Search Query:

The geological evolution of the Mawson Coast/Framnes Mountains

Entry ID: ASAC_177

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Summary

Abstract: Metadata record for data from ASAC Project 177
See the link below for public details on this project.

From the abstracts of some of the referenced papers:

The high-grade metamorphic rocks of the Colbeck Archipelago comprise granulite facies metasedimentary gneisses and charnockitic gneisses of three ages. A suite of rocks previously mapped as the Colbeck Gneiss is shown to be composite in age ... and origin, consisting of metasedimentary and orthogneiss that are intruded by granitic gneiss and charnockitic gneiss. An (?) Archaean granulite facies S1 gneissosity is preserved in the metadsedimentary gneisses and early orthogneiss; the development of S1 was followed by isobaric cooling from peak metamorphic conditions of T greater than or equal to 750 degrees C and P equal to 5.1 plus or minus 0.8 kbar. Younger intrusions cut rocks containing S1 structures, but were deformed by an approximate 1200 Ma granulite facies D2 event that resulted in reclined, isoclinal F2 folds oriented parallel to a pervasive east-trending L2 mineral and stretching lineation. Rocks bearing S2 structures are cut by the areally extensive ~ 960 Ma Mawson Charnockite, which was affected by two upright folding events D3 and D4 at ~ 920 Ma. Events D2-4 comprise the Proterozoic Rayner Structural Episode, which is characterised regionally by the retrogression of Archaean assemblages. The two pulses of extensive intermediate to felsic magmatism accompanied or immediately preceded the Proterozoic orogenies evident as D2-4, and it is tempting to infer casual links. However, field relationships are consistent with intrusion having been contemporary with anomalously high conductive heat fluxes, which could be due to advective heating from larger intrusions are not exposed at the present structural level. The formation of extensional, granulite facies D5 ultramylonite plus or minus pseudotachylite zones is the last deformation event in the area.

The high-grade metamorphic rocks exposed along the MacRobertson and east Kemp Land coasts consist of, in the west, Archaean gneisses reworked during a ductile mid-Proterozoic deformation, and in the east, foliated Proterozoic charnockite gneiss containing large remnants of gneiss of probable Archaean age. Evidence for three folding events is recognised in the reworked gneisses. An early recumbent terrain is deformed by two upright events possessing near-vertical axial surfaces. The charnockite gneiss preserves evidence of only the final event. These three events comprise the Rayner Structural Episode, which was a consequence of the ductile thrusting of Archaean gneiss westward toward a stable Archaean block, the Napier Complex. Kinematic indicators are consistent with the formation of the Proterozoic recumbent terrain by dominantly shear deformation. Dissection of both the Rayner and Napier Complexes by retrograde shear zones and mylonite-pseudotachylite zones was a consequence of the northward thrusting of the two complexes during the Cambrian.

Related URL

Link: VIEW PROJECT HOME PAGE

Description: Public information for ASAC project 177

Geographic Coverage

(Click for Interactive Map)

Spatial coordinates

N: -66.0

S: -67.0

E: 62.5

W: 61.5

Temporal Coverage

Start Date: 1990-09-30

Stop Date: 1997-03-31

Paleo Temporal Coverage

Chrono Unit:

PROTEROZOIC

Chrono Unit:

ARCHAEAN

Location Keywords

CONTINENT > ANTARCTICA

GEOGRAPHIC REGION > POLAR

Science Keywords

SOLID EARTH > ROCKS/MINERALS/CRYSTALS > METAMORPHIC ROCKS

SOLID EARTH > ROCKS/MINERALS/CRYSTALS > SEDIMENTARY ROCKS

SOLID EARTH > TECTONICS > PLATE TECTONICS > LITHOSPHERIC PLATE MOTION

ISO Topic Category

GEOSCIENTIFIC INFORMATION

Quality Values provided in temporal and spatial coverage are approximate only.

See the attached papers for more information.

Access Constraints Data for this project have not been able to be recovered.

Copies of some of the referenced publications are available for download at the provided URL to AAD staff only.

Use Constraints This data set conforms to the PICCCBY Attribution License
(http://creativecommons.org/licenses/by/3.0/).

Please follow instructions listed in the citation reference provided at http://data.aad.gov.au/aadc/metadata/citation.cfm?entry_id=ASAC_177 when using these data.

This "The geological evolution of the Mawson Coast/Framnes Mountains" is licensed under a Creative Commons Attribution 3.0 Unported License.

Ancillary Keywords

deformation

magmatism

metamorphic complexes

Data Set Progress

COMPLETE

Data Center

Australian Antarctic Data Centre, Australia

Data Center URL: http://data.aad.gov.au

Data Center Personnel
Name: DATA OFFICER AADC Phone: +61 3 6232 3244 Fax: +61 3 6232 3351 Email: metadata at aad.gov.au Contact Address: Australian Antarctic Division 203 Channel Highway City: Kingston Province or State: Tasmania Postal Code: 7050 Country: Australia

Distribution

Distribution Media: HTTP

Distribution Size: 29 MB

Distribution Format: PDF

Fees: free

Personnel

GEOFFREY L CLARKE

Role: INVESTIGATOR

Role: TECHNICAL CONTACT

Role: DIF AUTHOR

Phone: +61 2 9351 2919

Fax: +61 2 9351 0184

Email: geoffc at mail.usyd.edu.au

Contact Address:

University of Sydney

School of Geosciences F05

City: Sydney

Province or State: New South Wales

Postal Code: 2006

Country: Australia

Publications/References

Clarke G., Norman T. (1993), Generation of pseudotachylite under granulite facies conditions, and preservation during cooling., Journal of Metamorphic Geology, 11, 319

Creation and Review Dates

DIF Creation Date: 2000-10-11

Last DIF Revision Date: 2012-06-08

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