Geochemistry of seafloor surface sediment and submarine hydrothermal signature of Tomini Bay, Indonesia

Abstract

During the Indonesia–Australia Submarine Survey of Hydrothermal Activity (IASSHA) 2001 cruise, several seafloor surface sediment samples were collected from Tomini Bay. The samples were geochemically examined for major and trace-element geochemistry to study the hydrothermal signature fingerprint. The Tomini Bay seafloor surface sediment sampled by gravity coring is relatively enriched in Na, P, S, Ca, Ni, Sr, and Ba mainly from a terrigenous source. The elevated concentrations of Mg, S, Cr, Co and Ni at one site suggest a contribution from a mafic terrigenous source. A manganese-rich sediment layer was detected on the sediment surface with Mn up to 9474.43 ppm. A hydrothermal signature was successfully distinguished from the manganese-rich sediment layer. Despite the lack of hydrothermal precipitates, the geochemistry of the Tomini Bay seafloor surface sediments provides evidence for submarine hydrothermal activity.

KEY POINTS

1. Seafloor surface sediment is an alternative proxy for investigating submarine hydrothermal activity.

2. Hydrothermal signature is well recorded in the Fe/Mn-rich sediment layer and can be distinguished from measured concentrations and elemental ratios of Fe, Mn, HFSE (Zr), trace elements (Cu, Ni, Zn, Co, Zr) and REY (Y, Ce).

3. The Mn-rich sediment layer in Tomini Bay seafloor surface sediment preserved hydrothermal fingerprint and confirmed the evidence of an active hydrothermal system in the studied area.

Keywords:

• Tomini Bay
• geochemistry
• seafloor surface sediment
• hydrothermal activity
• hydrothermal signature
• manganese-rich sediments

Acknowledgements

We express our gratitude to Dr Hery Harjono, Director of the Research Center for Geotechnology—LIPI 2001–2006, Dr Safri Burhanuddin, Chief Coordinator of IASSHA 2001, and other scientists who participated in Leg A of the IASSHA 2001 marine expedition program. Thanks to R. A. Binns, T. McConachy, J. Parr, C. Yeats and CSIRO staff, who trained Indonesian scientists in technical operation marine expedition. Special thank you to the captain and crew of R/V Baruna Jaya VIII LIPI for their tireless effort and excellent handling, especially during the dredging operation in Tomini Bay.

Authorship contribution statement

AY was the main contributor to this article and was responsible for writing the original draft. HP kindly provided the data from the IASSHA 2001 cruise project. Together with IS, HN and SPS supported the process by initiating discussion and conceptualisation, providing constructive advice and reviewing the manuscript for submission.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The authors declare that the data supporting the findings of this study are available within the paper and its supplemental data.

Additional information

Funding

The joint research cooperation on Submarine Metallogenic Resources and its management has been funded by the Indonesian Institute of Sciences (LIPI) and Marine and Fishery Department (DKP) in Indonesia, and through a Government Sector Linkages Program, 2001–2002 from CSIRO and AusAID from Australia. LIPI’s post-cruise work is supported by a grant from RUTI (Riset Unggulan Terpadu Internasional, International Competitive Research Program), launched by the Ministry of Research and Technology of the Republic of Indonesia in 2002, and ran through 2004.