Explanation Of Marine Lake Formation At Misool Raja Ampat West Papua, Indonesia

Lukas Rumenta,Leontine E. Becking,Eko Haryono,Gandi Y.S. Purba,Purwanto Purwanto

doi:10.7186/bgsm72202112

Abstract

Marine lake in a karst landscape is one of the macro karst forms known as doline and is only found in some locations in the world. Moreover, the theory of marine doline formation is always associated with global sea-level rise which differs from one place to another due to several factors. This research was conducted to understand the formation process of marine lakes in Misool and how the water fills the basins formed especially at Holocene time. This was achieved by obtaining information on the longest underwater terrace which is also the longest standing water position recorded on the sea wall. The marine terraces were measured by sounding profiles to the sea bordering the seven marine lakes including Lenmakana, Balbullol, Lenkafal, Keramat, Karawapop, Keramat-2, and Keramat-3 as well as Harapan Jaya Sea. A total of 24 profiles were measured and stable isotopes δ18O and δD of water samples were used to determine the origin of water in the lakes. The results showed the longest terrace was at the depth of ˗33 and ˗3 m while the references from the area closest to Misool showed the same water level positions at 10,500 BP and 6,985 BP. Furthermore, the composition of δ18O and δD from lake water indicated the water samples were a mixture of groundwater and seawater with the seawater having the more dominant concentration and this allows it to fill the lake first through a previously formed cavity system.

Highlights

Marine lake is a body of water surrounded by land with variations in form, size, and distance to the sea, and some are found at karst areas such as Palau, Halong Bay Vietnam, Croatia, and Raja Ampat Indonesia
The information produced from these articles and others on the marine environment including the marine lake in Palau has been documented by Colin (2009) while some others are on Vietnam and the whole of Indonesia
(1994) provided a comprehensive report on Kakaban Lake in East Kalimantan, Becking et al (2011; 2009) on marine lakes in Raja Ampat, and the discovery of jellyfish lakes in Misool by Becking et al (2014) and Purba et al (2018b). These findings showed 40 out of the 55 marine lakes in Raja Ampat are in Misool Island (Becking et al, 2009; 2011)

Summary

Introduction

Marine lake is a body of water surrounded by land with variations in form, size, and distance to the sea, and some are found at karst areas such as Palau, Halong Bay Vietnam, Croatia, and Raja Ampat Indonesia. Tomascik & Mah (1994) provided a comprehensive report on Kakaban Lake in East Kalimantan, Becking et al (2011; 2009) on marine lakes in Raja Ampat, and the discovery of jellyfish lakes in Misool by Becking et al (2014) and Purba et al (2018b). These findings showed 40 out of the 55 marine lakes in Raja Ampat are in Misool Island (Becking et al, 2009; 2011)

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Discussion

Conclusion