Title

Seismic characteristics and accretion history of Halimeda bioherms on Kalukalukuang Bank, eastern Java Sea (Indonesia)

Document Type

Article

Publication Date

3-1-1988

Abstract

Extensive areas of Halimeda bioherms similar to those described by Orme et al. (1978), Orme (1985), Davies and Marshall (1985), and Phipps et al. (1985) from Australia's Great Barrier Reef have formed on Kalukalukuang Bank (K-Bank) 50 km east of the Sunda Shelf margin in the easter Java Sea. K-Bank is an isolated limestone platform whose top slopes southward from a water depth of about 20 m at the north to about 100 m at the south (≈30 km). It occurs in a bidirectional monsoonal wind regime and a predominantly southerly flowing current from Makassar Strait. The water column around K-Bank has a well developed shallow thermocline (50 m to 150 m). K-Bank has a relatively flat top with marginal banks of suspected Pleistocene origin as interpreted from seismic relationships. A reconnaissancelevel survey grid of high-resolution seismic profiles indicates that Halimeda bioherms are restricted to the bank margins with the exception of the eastern margin. Bioherms either extend to the steep margin of the platforms or are separated from the platform edge by banks of coral and coralline algae. The morphology of the Halimeda bioherms varies from steep-sided, elongate ridges in the northern bank area, through coalescing symmetrical mounds with partly infilled valleys, to broad undulating areas similar to those described by Orme (1985) from the Great Barrier Reef. High-resolution seismic records indicate erosional episodes in the high-relief areas, an interpretation that seems to be supported by accumulation rates calculated from C dates of cores. Thicknesses of Halimeda accumulation above a prominent reflector considered as Pleitocene, vary from around 20 m in the north to a maximum of over 50 m in the southwest. Accumulation rates obtained from dating of two cores to-ward the north of K-Bank, average 0.294 m/100 yr for core VC4 and a maximum of 0.59 m/100 yr in a part of core PC12. Dating of material from the top 30 cm of a deep bioherm (≈100 m) in the southwest of K-Bank, indicates that the growth rate of these bioherms has slowed markedly, presumably because of increasing water depth (decreasing light) over the Holocene transgression. © 1988 Springer-Verlag. 14

Publication Source (Journal or Book title)

Coral Reefs

First Page

149

Last Page

159

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