Skip to Main Content
Book Chapter

Granites of Edward VII Peninsula, Marie Byrd Land: anorogenic magmatism related to Antarctic–New Zealand rifting

By
S. D. Weaver
S. D. Weaver
Search for other works by this author on:
C. J. Adams
C. J. Adams
Search for other works by this author on:
R. J. Pankhurst
R. J. Pankhurst
Search for other works by this author on:
I. L. Gibson
I. L. Gibson
Search for other works by this author on:
Published:
January 01, 1992

Syenogranites and monzogranites of Edward VII Peninsula, Marie Byrd Land, represent magmatism associated with continental rifting and the separation of New Zealand from W Antarctica in the mid-Cretaceous. These coarse-grained, leucocratic, subsolvus biotite granites occur as five small plutons cutting Lower Palaeozoic metasediments. Petrographic features include the predominance of microcline perthite over albite, bipyramidal smoky quartz, red-brown biotite and accessory ilmenite, zircon, apatite, monazite and fluorite. Enclaves are absent and miarolitic cavites are rare.

The granites are a weakly peraluminous, potassic, and highly fractionated suite with high concentrations of Rb, Nb, Y, HREE and F in the most evolved compositions. REE patterns vary from LREE-enriched (CeN/YbN = 8.4), to flat REE patterns (CeN/YbN = 1.1) with large negative Eu anomalies (Eu/Eu* =0.02). Initial 87Sr/86Sr ratios are 0.7116–0.7206 and initial εNd values are −5.5 to −7.7. Generalised fractionation trends for the suite are explicable in terms of the modal mineralogy. Monazite crystallisation exerted a predominant control on LREE concentrations.

The geochemistry of the Edward VII Peninsula granites suggests an infracrustal I-type source, and regionally available Devonian-Carboniferous I-type granodiorites and tonalites satisfy the isotopic constraints. The granites classify as A-type (preferred term A-subtype) and Within-Plate Granites on standard diagrams, but the least fractionated rocks clearly indicate the I-type, Volcanic Arc Granite geochemical signatures of their inferred crustal sources.

You do not currently have access to this article.

Figures & Tables

Contents

GSA Special Papers

The Second Hutton Symposium on the Origin of Granites and Related Rocks

P. E. Brown
P. E. Brown
Search for other works by this author on:
B. W. Chappell
B. W. Chappell
Search for other works by this author on:
Geological Society of America
Volume
272
ISBN print:
9780813722726
Publication date:
January 01, 1992

References

Related

Citing Books via

Related Articles
Close Modal
This Feature Is Available To Subscribers Only

Sign In or Create an Account

Close Modal
Close Modal