Changes of thermocline depth at the Sumba Island offshore based on planktonic foraminiferal assemblages and its implication to eutrophication since the Last Deglaciation (~18 ka BP): a preliminary study

Authors

  • Ryan Dwi Wahyu Ardi 1Geological Engineering Study Program, Faculty of Earth Science and Technology, Institut Teknologi Bandung, Jl. Ganesha No. 10 Bandung 40132; 2Agrotechnology Study Program, Faculty of Science and Technology, Universitas Nahdlatul Ulama Purwokerto, Jl. Sultan Agung No. 42 Purwokerto 53144 https://orcid.org/0000-0002-2037-9287
  • Aswan 1Geological Engineering Study Program, Faculty of Earth Science and Technology, Institut Teknologi Bandung, Jl. Ganesha No. 10 Bandung 40132 https://orcid.org/0000-0001-6074-8772
  • Khoiril Anwar Maryunani 1Geological Engineering Study Program, Faculty of Earth Science and Technology, Institut Teknologi Bandung, Jl. Ganesha No. 10 Bandung 40132
  • Eko Yulianto Research Center for Geotechnology, Indonesian Institute of Sciences, Jl. Sangkuriang Kompleks LIPI Bandung 40135 https://orcid.org/0000-0002-9685-6510
  • Purna Sulastya Putra Geological Engineering Study Program, Faculty of Earth Science and Technology, Institut Teknologi Bandung, Jl. Ganesha No. 10 Bandung 40132; Research Center for Geotechnology, Indonesian Institute of Sciences, Jl. Sangkuriang Kompleks LIPI Bandung 40135 https://orcid.org/0000-0002-4417-5852
  • Septriono Hari Nugroho Geological Engineering Study Program, Faculty of Earth Science and Technology, Institut Teknologi Bandung, Jl. Ganesha No. 10 Bandung 40132; Research Center for Geotechnology, Indonesian Institute of Sciences, Jl. Sangkuriang Kompleks LIPI Bandung 40135

DOI:

https://doi.org/10.17794/rgn.2021.3.3

Keywords:

Australian–Indonesian monsoon, applied micropaleontology, Indonesian Throughflow, Lesser Sunda Islands, paleoceanography

Abstract

Changes of the thermocline depth (DOT) at the Sumba Island offshore are not well-known compared to the DOT changes in the Timor Sea, the main exit passage of the Indonesian Through-flow (ITF). Planktonic foraminiferal assemblages in cores collected from the southwest Sumba offshore (ST08) and Sumba Strait (ST12, ST13, and ST14) were used as a tool to infer the DOT and paleoproductivity changes at the Sumba Island offshore. The DOT changes were indicated from the thermocline and mixed layer dwellers’ relative abundance while the paleoproductivity changes were indicated from the relative abundance of Neogloboquadrina dutertrei. This study suggests a contrast between the DOT pattern at the Sumba Island offshore and the DOT pattern in the Timor Sea during the Last Deglaciation–Holocene. The contrast DOT pattern indicated that the multi-millennial changes of the Australian-Indonesian monsoon (AIM) during the Last Deglaciation–Holocene were the main factors behind the DOT changes in this region while the effects of El Nino Southern Oscillation (ENSO) –like, Indian Ocean Dipole (IOD) –like, and ITF to DOT changes were minimal. Paleoproductivity enhancement at the Sumba Island offshore was not solely related to the monsoon-driven coastal upwelling intensification, which resulted in the DOT shoaling and eutrophic condition. The increase of nutrient availability in surface water due to river runoff increase and changes in the lifted water mass nature were also able to enhance productivity in this region.

Author Biographies

Ryan Dwi Wahyu Ardi, 1Geological Engineering Study Program, Faculty of Earth Science and Technology, Institut Teknologi Bandung, Jl. Ganesha No. 10 Bandung 40132; 2Agrotechnology Study Program, Faculty of Science and Technology, Universitas Nahdlatul Ulama Purwokerto, Jl. Sultan Agung No. 42 Purwokerto 53144

Doctoral Candidate in Geological Engineering Study Program, Faculty of Earth Sciences and Technology, Institut Teknologi Bandung

Junior Lecturer in Agrotechnology Study Program, Faculty of Science and Technology, Universitas Nahdlatul Ulama Purwokerto

Aswan, 1Geological Engineering Study Program, Faculty of Earth Science and Technology, Institut Teknologi Bandung, Jl. Ganesha No. 10 Bandung 40132

Senior Lecturer and member of the Paleontology and Quartenary Geology Research Group in Geological Engineering Study Program, Faculty of Earth Science and Technology, Institut Teknologi Bandung

 

Khoiril Anwar Maryunani, 1Geological Engineering Study Program, Faculty of Earth Science and Technology, Institut Teknologi Bandung, Jl. Ganesha No. 10 Bandung 40132

Lecturer and member of the Paleontology and Quartenary Geology Research Group in Geological Engineering Study Program, Faculty of Earth Science and Technology, Institut Teknologi Bandung

 

Eko Yulianto, Research Center for Geotechnology, Indonesian Institute of Sciences, Jl. Sangkuriang Kompleks LIPI Bandung 40135

Chief Researcher and Chief of Research Center for Geotechnology, Indonesian Institute of Sciences

Purna Sulastya Putra, Geological Engineering Study Program, Faculty of Earth Science and Technology, Institut Teknologi Bandung, Jl. Ganesha No. 10 Bandung 40132; Research Center for Geotechnology, Indonesian Institute of Sciences, Jl. Sangkuriang Kompleks LIPI Bandung 40135

Senior Researcher and Head of Sedimentary Laboratory in Research Center for Geotechnology, Indonesian Institute of Sciences

Doctoral Candidate in Geological Engineering Study Program, Faculty of Earth Sciences and Technology, Institut Teknologi Bandung

Septriono Hari Nugroho, Geological Engineering Study Program, Faculty of Earth Science and Technology, Institut Teknologi Bandung, Jl. Ganesha No. 10 Bandung 40132; Research Center for Geotechnology, Indonesian Institute of Sciences, Jl. Sangkuriang Kompleks LIPI Bandung 40135

Junior Researcher and member of Sedimentary Laboratory in Research Center for Geotechnology, Indonesian Institute of Sciences

Doctoral Candidate in Geological Engineering Study Program, Faculty of Earth Sciences and Technology, Institut Teknologi Bandung

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Published

2021-06-23

How to Cite

Ardi, R. D. W., Aswan, Maryunani, K. A., Yulianto, E. ., Putra, P. S., & Nugroho, S. H. (2021). Changes of thermocline depth at the Sumba Island offshore based on planktonic foraminiferal assemblages and its implication to eutrophication since the Last Deglaciation (~18 ka BP): a preliminary study. Rudarsko-geološko-Naftni Zbornik, 36(3). https://doi.org/10.17794/rgn.2021.3.3

Issue

Vol. 36 No. 3 (2021): No. 54

Section

Geology

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