Satellite‐ and field‐based facies mapping of isolated carbonate platforms from the Kepulauan Seribu Complex, Indonesia

Dwi Amanda Utami,Lars Reuning,Sri Yudawati Cahyarini

doi:10.1002/dep2.47

Dwi Amanda Utami, Lars Reuning + Show 1 more

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https://doi.org/10.1002/dep2.47

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Abstract

AbstractQuantitative facies models from modern carbonate are essential for the interpretation of their fossil counterparts. The isolated carbonate platforms of the Kepulauan Seribu archipelago has many atoll‐like islands with reef belts exposed to bidirectional monsoon winds. Statistical analysis based on texture and composition reveal that there are four sedimentary facies; coral grainstone, coral packstone/grainstone, coral‐mollusc packstone and mollusc wackestone. The occurrence of mollusc wackestone in the lagoon is controlled by water depth, while the sand apron and reef front do not show significant facies separation with water depth. The co‐occurrence of these different facies in the same depth window is contrary to the common thought that changes in bathymetry should be reflected in facies changes. The studied reef systems therefore show aspects of random and ordered facies distribution with respect to water depth. A satellite derived environmental facies map generated by an image analysis algorithm indicates that environmental facies distribution is mainly controlled by water depth, density of seagrass cover and coral abundance. The sand apron can be subdivided into three environmental facies with no, sparse and dense seagrass cover. The deeper water zone can be separated into shallow and deep subtidal parts of lagoons and platform margins. In the lagoon, satellite derived environmental facies directly correlated with sedimentary facies. No direct correlation of environmental facies to sedimentary facies was possible in the sand apron due to the heterogeneity and complexity of the environment. However, the mean sediment grain size is significantly smaller in areas of the sand apron colonized by dense seagrass. This study aims to contribute towards a better understanding of modern equatorial Southeast Asian carbonate systems, delineate modern carbonate facies based on sediment texture and composition with the aid of multivariate statistical analysis combined with statistic based satellite mapping, and give insights regarding the correlation between depositional facies and water depth.

Highlights

Cenozoic shallow marine tropical carbonates form major hydrocarbon reservoirs in various parts of the world
The small, isolated carbonate platforms forming the islands of the Kepulauan Seribu Complex provide a useful modern analogue for buried carbonate systems in Indonesia (Park et al, 1995; Wilson, 2002) and other similar Cenozoic carbonates from Southeast Asia and northern Australia (Belde, Back, Bourget, & Reuning, 2017; Morgan, George, Harris, Kupecz, & Sarg, 2010; Rosleff‐Soerensen, Reuning, Back, & Kukla, 2012, 2016)
Four sedimentary facies occur in isolated carbonate platforms of Kepulauan Seribu: coral grainstone, coral packstone/grainstone, coral‐mollusc packstone and mollusc wackestone

Summary

Introduction

Cenozoic shallow marine tropical carbonates form major hydrocarbon reservoirs in various parts of the world. Almost half the cumulative production and a sizeable proportion of the remaining oil and gas reserves in Indonesia are found in the Java Sea, offshore southeast Sumatra and northwest Java (Figure 1). These fields are hosted by Miocene carbonates of the Baturaja and Parigi Formation (Bukhari, Kaldi, Yaman, Kakung, & Williams, 1992; Burbury, 1977; Fainstein, 1987; Park, Matter, & Tonkin, 1995). Sediment distribution patterns form the fundamental studies on sediment formation, redeposition, sediment dynamics and early diagenesis in modern reefs and carbonate platforms (Gischler, 2011; Gischler, Isaack, & Hudson, 2017)

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