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Temporal association of arc–continent collision, progressive magma contamination in arc volcanism and formation of gold-rich massive sulphide deposits on Wetar Island (Banda arc)

Temporal association of arc–continent collision, progressive magma contamination in arc volcanism and formation of gold-rich massive sulphide deposits on Wetar Island (Banda arc)
Temporal association of arc–continent collision, progressive magma contamination in arc volcanism and formation of gold-rich massive sulphide deposits on Wetar Island (Banda arc)
Whole-rock 87Sr/86Sr and ?18O analyses of volcanic rocks and 3He/4He analyses of sulphides and sulphates from mineralized rocks on Wetar, Indonesia indicate a variable contribution of assimilated crustal material or sediment sourced from the subducted Australian craton to the south. These new data support the idea of progressive source contamination with precisely dated events showing that Wetar Island hosts the most extreme examples of crustal assimilation in the region. The increased continental contamination occurs during the Pliocene (Zanclian to Piacenzian) during distinct magmatic events between 5 and 4 Ma, and at 2.4 Ma when 87Sr/86Sr ratios in unaltered lavas, with whole-rock ?18O values between 5.7 and 9.6‰, increase from 0.707484 to extreme radiogenic values of 0.711656.

The earlier of these magmatic events is important in the generation of the hydrothermal systems responsible for the mineralization recorded on Wetar. Samples from this yield radiogenic 3He/4He ratios between 0.5 and 1.4 R/RA, similar to the data from volcanic rocks on nearby Romang. The later magmatic event coincides with the arrival of the Australian Continental Margin at the subduction zone along the Banda arc. Progressive incorporation of continental-sourced components into the source region below the Wetar Island edifice coincides with the formation of gold-rich volcanogenic massive sulphide deposits hosted within the contaminated volcanic pile.
1342-937X
583-593
Herrington, Richard J.
118a02cb-b04d-4110-a96a-a227ae6ccb8f
Scotney, Philip M.
de324b91-8087-48a9-8e47-b926b5bd1bf6
Roberts, Stephen
f095c7ab-a37b-4064-8a41-ae4820832856
Boyce, Adrian J.
e21e60d3-a9ab-4cad-9bd8-f6680f3dbd7f
Harrison, Darrell
d2965c7f-3191-4bb1-a090-8df899d47f1e
Herrington, Richard J.
118a02cb-b04d-4110-a96a-a227ae6ccb8f
Scotney, Philip M.
de324b91-8087-48a9-8e47-b926b5bd1bf6
Roberts, Stephen
f095c7ab-a37b-4064-8a41-ae4820832856
Boyce, Adrian J.
e21e60d3-a9ab-4cad-9bd8-f6680f3dbd7f
Harrison, Darrell
d2965c7f-3191-4bb1-a090-8df899d47f1e

Herrington, Richard J., Scotney, Philip M., Roberts, Stephen, Boyce, Adrian J. and Harrison, Darrell (2011) Temporal association of arc–continent collision, progressive magma contamination in arc volcanism and formation of gold-rich massive sulphide deposits on Wetar Island (Banda arc). Gondwana Research, 19 (3), 583-593. (doi:10.1016/j.gr.2010.10.011).

Record type: Article

Abstract

Whole-rock 87Sr/86Sr and ?18O analyses of volcanic rocks and 3He/4He analyses of sulphides and sulphates from mineralized rocks on Wetar, Indonesia indicate a variable contribution of assimilated crustal material or sediment sourced from the subducted Australian craton to the south. These new data support the idea of progressive source contamination with precisely dated events showing that Wetar Island hosts the most extreme examples of crustal assimilation in the region. The increased continental contamination occurs during the Pliocene (Zanclian to Piacenzian) during distinct magmatic events between 5 and 4 Ma, and at 2.4 Ma when 87Sr/86Sr ratios in unaltered lavas, with whole-rock ?18O values between 5.7 and 9.6‰, increase from 0.707484 to extreme radiogenic values of 0.711656.

The earlier of these magmatic events is important in the generation of the hydrothermal systems responsible for the mineralization recorded on Wetar. Samples from this yield radiogenic 3He/4He ratios between 0.5 and 1.4 R/RA, similar to the data from volcanic rocks on nearby Romang. The later magmatic event coincides with the arrival of the Australian Continental Margin at the subduction zone along the Banda arc. Progressive incorporation of continental-sourced components into the source region below the Wetar Island edifice coincides with the formation of gold-rich volcanogenic massive sulphide deposits hosted within the contaminated volcanic pile.

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Published date: 2011

Identifiers

Local EPrints ID: 183481
URI: http://eprints.soton.ac.uk/id/eprint/183481
ISSN: 1342-937X
PURE UUID: a807cec0-1eb2-442c-b7a1-0961a6fdf517
ORCID for Stephen Roberts: ORCID iD orcid.org/0000-0003-4755-6703

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Date deposited: 28 Apr 2011 15:29
Last modified: 09 Nov 2021 02:39

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Contributors

Author: Richard J. Herrington
Author: Philip M. Scotney
Author: Stephen Roberts ORCID iD
Author: Adrian J. Boyce
Author: Darrell Harrison

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