Australian Museum Journal Balmoral Beach Aboriginal shell midden, Port Jackson, Australia: pumice petrology and sources

Shortform:
Sutherland and Barron, 1998, Rec. Aust. Mus. 50(3): 241–262
Author(s):
Sutherland, F. L.; Barron, B. J.
Year published:
1998
Title:
Balmoral Beach Aboriginal shell midden, Port Jackson, Australia: pumice petrology and sources
Serial title:
Records of the Australian Museum
Volume:
50
Issue:
3
Start page:
241
End page:
262
DOI:
10.3853/j.0067-1975.50.1998.1284
Language:
English
Date published:
25 November 1998
Cover date:
25 November 1998
ISSN:
0067-1975
CODEN:
RAUMAJ
Publisher:
The Australian Museum
Place published:
Sydney, Australia
Subjects:
ABORIGINES: AUSTRALIAN; ANTHROPOLOGY; CULTURE: INDIGENOUS
Digitized:
11 March 2009
Available online:
16 July 2009
Reference number:
1284
EndNote package:
EndNote file
Title page:
Title page (109kb PDF)
Complete work:
Complete work (4580kb PDF)

Abstract

Palaeopumice strand deposits (1800 to 4000 years B.P.) occur in the Balmoral Beach Aboriginal Shell Midden excavations. In composition, the pumice clasts are low-potassium dacites and contain up to 5% xenocrysts, phenocrysts and glomerophenocrysts of orthopyroxene, pyroxene, plagioclase and iron oxide minerals. The matrix includes smaller grains of these minerals in an abundant, highly vesicular rhyodacite volcanic glass. The 3300 year old and younger pumices typically contain rare xenocrysts and phenocrysts of magnesian olivine, forming an unusual mineral assemblage. One older pumice clast is a quartz-bearing rhyodacite, with distinctive trace element geochemistry. The typical dacites, resemble those erupted from the Tonga-Kermadec island arc in the Southwest Pacific, due both to the presence of olivine and the variably depleted trace and rare earth element contents. This implies a 4000 km drift caused by the East Australian oceanic current, before the pumice was stranded in Port Jackson.