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)

Herrington, R.J., Scotney, P.M., Roberts, S., Boyce, A.J. and Harrison, D. (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), pp. 583-593. (doi: 10.1016/j.gr.2010.10.011)

Abstract

Whole-rock ⁸⁷Sr/⁸⁶Sr and δ¹⁸O 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 δ¹⁸O 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/R_A, 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.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Boyce, Professor Adrian
• Authors: Herrington, R.J., Scotney, P.M., Roberts, S., Boyce, A.J., and Harrison, D.
• College/School: College of Science and Engineering > Scottish Universities Environmental Research Centre
• Journal Name: Gondwana Research
• Publisher: Elsevier B.V.
• ISSN: 1342-937X
• ISSN (Online): 1342-937X
• Published Online: 19 November 2010