See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/272822199 Diversity and paleoecology of Miocene coral-associated mollusks from East Kalimantan (Indonesia) Article in Palaios · February 2015 DOI: 10.2110/palo.2013.124 CITATIONS READS 14 725 7 authors, including: Sonja Reich Frank Wesselingh GEOMAR Helmholtz Centre for Ocean Research Kiel Naturalis Biodiversity Center 9 PUBLICATIONS 164 CITATIONS 206 PUBLICATIONS 6,838 CITATIONS SEE PROFILE SEE PROFILE Nadia Santodomingo Kenneth G. Johnson Natural History Museum, London Natural History Museum, London 71 PUBLICATIONS 996 CITATIONS 109 PUBLICATIONS 3,685 CITATIONS SEE PROFILE SEE PROFILE Some of the authors of this publication are also working on these related projects: PRIDE: Drivers of Pontocaspian RIse and DEmise View project Fossil shells Dutch coasts View project All content following this page was uploaded by Sonja Reich on 27 February 2015. The user has requested enhancement of the downloaded file. DIVERSITY AND PALEOECOLOGY OF MIOCENE CORAL-ASSOCIATED MOLLUSKS FROM EAST KALIMANTAN (INDONESIA) Source: PALAIOS, 30(1):116-127. Published By: Society for Sedimentary Geology URL: http://www.bioone.org/doi/full/10.2110/palo.2013.124 BioOne (www.bioone.org) is a nonprofit, online aggregation of core research in the biological, ecological, and environmental sciences. BioOne provides a sustainable online platform for over 170 journals and books published by nonprofit societies, associations, museums, institutions, and presses. Your use of this PDF, the BioOne Web site, and all posted and associated content indicates your acceptance of BioOne’s Terms of Use, available at www.bioone.org/page/terms_of_use. Usage of BioOne content is strictly limited to personal, educational, and non-commercial use. Commercial inquiries or rights and permissions requests should be directed to the individual publisher as copyright holder. BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research. PALAIOS, 2015, v. 30, 116–127 Research Article DOI: http://dx.doi.org/10.2110/palo.2013.124 DIVERSITY AND PALEOECOLOGY OF MIOCENE CORAL-ASSOCIATED MOLLUSKS FROM EAST KALIMANTAN (INDONESIA) ARIES KUSWORO,1 SONJA REICH,2 FRANK P. WESSELINGH,2 NADIEZHDA SANTODOMINGO,3 KENNETH G. JOHNSON,3 3 2 JONATHAN A. TODD, AND WILLEM RENEMA 1Pusat Survei Geologi, Jl. Diponegoro 57, Bandung 40122, Indonesia 2Naturalis Biodiversity Center, Department of Geology, P.O. Box 9517, 2300 RA Leiden, The Netherlands 3Department of Earth Sciences, Natural History Museum, Cromwell Road, London SW& BD, UK e-mail: [email protected] ABSTRACT: This study is a preliminary assessment of an extremely diverse Tortonian (late Miocene) mollusk assemblage from a coral carpet environment preserved at Bontang (East Kalimantan, Indonesia). Even though coral-associated aragonitic faunas are rarely well preserved, the composition of the assemblage described here can be used to address the following questions: (1) How do the mollusk assemblages in coral habitats differ from other habitats, and (2) What is the effect of sampling on estimates of taxon richness? The mollusk assemblage is dominated by predatory snails and includes typical modern coral- associated taxa such as the gastropod Coralliophila and the bivalve Tridacna. Our investigation implies that adequate documentation of Cenozoic mollusk diversity in the Indo-Pacific is even more challenging than previously expected as very large samples are required to capture species richness. Further assessments of fossil faunas from coral-dominated habitats will be required to provide insight to development of Indo-Pacific biodiversity through time. INTRODUCTION and (2) What is the effect of sampling on taxon richness estimates? To achieve these goals we reconstruct the paleoenvironment of the locality, The Indo-West Pacific (IWP), extending from the Red Sea and East document the mollusk assemblage in terms of taxon richness and feeding Africa to the Central Pacific, is the largest of four major oceanic guild composition, and compare our results to published faunas from biogeographic regions, and the one holding the highest taxon diversity elsewhere in the IWP. (Ekman 1934; Briggs 1974; Paulay 1997). Within the IWP, the center of maximum marine biodiversity (species richness) is located in the Indo- Malayan region where local species richness peaks in and around coral GEOLOGICAL SETTING AND STUDY LOCALITY habitats (Hoeksema 2007; Renema et al. 2008). A large variety of The Miocene outcrops of Bontang are located on the eastern side of the organisms, including corals, fish, mollusks, crustaceans, and echinoderms Kutai Basin, the southeasternmost extension of the Sunda platform on contribute to the high diversity in the region (Bellwood et al. 2005; the east coast of Kalimantan, Indonesia. The Kutai Basin is confined by Hoeksema 2007; Renema et al. 2008). Documentation of the fossil record the Sangkulirang fault zone in the north, the Adang fault zone in the is required in order to understand the ecological and environmental south, the Kalimantan High in the west, and to the east the Makassar context of the origin of the biodiversity hotspot, as well as its Strait. The formation of the Kutai Basin initiated during the Eocene development through time (Renema et al. 2008). Although the sampling (Moss and Chambers 1999). Subsequently the basin developed in various of ancient coral reef–associated habitats is necessary to document levels phases during the Cenozoic, including major changes of the basin of biodiversity, this is frequently difficult: coral facies often suffer strong architecture and depositional systems. During the late Neogene and diagenesis, compromising the preservation of associated organisms, Quaternary the basin development was regressive, a result of sediment fill, especially those with aragonitic hard-parts, such as mollusks (Wright et inversion, and uplift (Allen and Chambers 1998). In Miocene times the al. 2003). This results in highly biased mollusk assemblages from reefal study area was located in a coastal zone that received considerable input environments that are largely made up of taxa with more diagenetically of terrigenous clastic sediments (Cibaj 2009; Marshall et al. 2015). In spite resistant and largely calcitic shells, such as oysters and pectinids (Wright of relatively turbid water conditions, rich coral communities could et al. 2003, and references therein; Santodomingo et al. 2015). develop in the region (Wilson 2005; Novak et al. 2015; Santodomingo In this study an unusually well preserved association of ramose corals et al. 2015). and mollusks from upper Miocene deposits in Bontang (East Kaliman- The sampling locality TF 102 (0.16821u N, 117.44350u E) is an tan, Indonesia) is presented. The material provides the opportunity to abandoned quarry on the north side of the northern entrance road to investigate a rare Neogene coral-associated mollusk assemblage from the Bontang (Fig. 1). The locality represents the upper part of a marine IWP biodiversity hotspot. The aim of this study is to reconstruct the interval of about 150 cm of fossiliferous, coarsening-upward, silty clay to paleoenvironment and to characterize the mollusk assemblage in terms of fine sandy silt (Fig. 1). Below this interval gray-blue clay with dispersed diversity and ecology. Specific questions that we address include: (1) How fossiliferous lenses occurs. Above the marine interval lies a non- do the mollusk assemblages in coral habitats differ from other habitats, fossiliferous undulating clay bed of approximately 160 cm thickness Published Online: February 2015 Copyright E 2015, SEPM (Society for Sedimentary Geology) 0883-1351/15/030-116/$03.00 PALAIOS MIOCENE INDONESIAN CORAL-ASSOCIATED MOLLUSKS 117 FIG. 1.—Overview over locality TF 102, Bontang, East Kalimantan. A) Location in the Bontang area. B) Situation sketch of coral patches on the floor of abandoned quarry TF 102. C) Lithological column of the TF 102 quarry section: a 5 clay, b 5 silt, c 5 sand, d 5 organic matter, e 5 shells, f 5 corals. The asterisk denotes the sampled interval. Height in meters. followed by approximately three meters of barren fine sandstones. Those sediments represent the basal part of an overlying fluvial unit. Biostratigraphic data (large benthic foraminifera and calcareous nannoplankton) suggest that the TF 102 locality and other fossiliferous localities nearby are assigned a Tortonian age (Renema et al. 2015). Strontium isotope data from scleractinian corals and giant clams (Tridacninae) from six localities in the Bontang area (including TF 102) show ages ranging from 8.24 Ma to 9.75 Ma (61 Ma) with an average of 9.4 6 0.2 Ma, matching a Tortonian biostratigraphic age (Renema et al. 2015). MATERIAL AND METHODS FIG. 2.—Images of the surface of a coral-mollusk patch on the floor of the TF Fossil mollusk and coral assemblages were collected from discrete 102 quarry. A) Coral fragments and mollusks; a larger muricid gastropod is visible patches of fragmented ramose corals, weathering out on the approxi- in the center. B) Melongena in the center; the smaller gastropod shell in front is a mately horizontal surface of a bedding plane of marine silts and clays Coralliophila. C) A comparatively large strombid shell on the left. (Figs. 1, 2). Although these patches