02693nas a2200157 4500008004000000245009300040210006900133260002000202520217200222100002402394700002002418700001702438700001802455700001902473856004302492 0 engd00aMicrobial carbonates in Miocene reefs in the Mahakam Delta in East Kalimantan, Indonesia0 aMicrobial carbonates in Miocene reefs in the Mahakam Delta in Ea aBerlin, Germany3 a
Coral patch reefs in the Miocene Mahakam Delta in East Kalimantan (Borneo, Indonesia) grew in shallow marine turbid waters. These patch reefs developed from delta front to deeper (prodelta) settings in areas with temporary reduced siliciclastic input. Langhian reef deposits are well exposed in limestone quarries in the Samarinda area and locally include microbial carbonates. Two different types of microbial carbonates have been found around Samarinda in two localities 2 km apart. These sections were logged in detail and 208 samples were collected. Meso and macrostructure of microbialites were identified at the outcrops. Thin sections from carbonate samples were examined under optical microscope and microfacies were classified using the Dunham (1962) and Insalaco (1998) terms. The carbonate content was analyzed using Total Inorganic Carbon analysis, with 12% carbon as a standard for carbon calibration. In the northern section, microbialites occur as low-relief domes, up to 2 m wide and 0.5 m high, with internal lamination, developed around large coral fragments at the transition from reef deposits to fine-grained siliciclastics.
The second type of microbialites has been found in the southern locality as decimeter-scale nodules ("megaoncoids") formed around nuclei of large coral fragments. Small nodules were bound together into bigger nodules. Microbial micrite with laminated to digitated fabrics intergrew with coralline algae to form the thick covers of these "megaoncoids", which laterally change into coral boundstones. In both sections microbialites are not components of the reef framework. They grew around large coral fragments on the flanks of the patch reefs. The microbialites that form low relief domes developed on nearly flat, stable seafloor seawards of the patch reef. The "megaoncoids" in the southern section formed as a result of downslope movement of coral fragments coated by microbialite/coralline algal crust. The steep slope at the flank of the patch reef favored falling and overturning of encrusted corals and continued growth of microbial crusts on other sides of nodules.
Microbial carbonates are deposits that form by the activity of bentic microbial communities. Microbialites usually form domical, columnar or conical structures and can have laminated, clotted, dendritic or homogenous macrofabric. They have a broad distribution and can grow in a variety of different environments such as hot springs, freshwater lakes, hypersaline lakes, reefs and other marine environments. This research focuses on microbialites associated to coral reefs. Coral patch reefs in the Miocene Mahakam Delta in East Kalimantan (Borneo, Indonesia) grew in shallow marine turbid waters. These patch reefs developed from delta front to deeper (prodelta) settings in areas with temporary reduced siliciclastic input. Langhian reef deposits are well exposed in limestone quarries in the Samarinda area and locally include microbial carbonates. Two different types of microbial carbonates have been found around Samarinda in two localities 2 km apart. These sections were logged in detail and 208 samples were collected. Meso and macrostructure of microbialites were identified at the outcrops. Thin sections from carbonate samples were examined under optical microscope and microfacies were classified using the Dunham (1962) and Embry and Klovan (1971) terms. The carbonate content was analyzed using Total Inorganic Carbon analysis, with 12% carbon as a standard for carbon calibration. In the northern section, microbialites occur as low-relief domes, up to 2 m wide and 0.5 m high, with internal lamination, developed around large coral fragments at the transition from reef deposits to fine-grained siliciclastics.
The second type of microbialites has been found in the southern locality as decimeter-scale nodules ("megaoncoids") formed around nuclei of large coral fragments. Small nodules were bound together into bigger nodules. Microbial micrite with laminated to digitated fabrics intergrew with coralline algae to form the thick covers of these "megaoncoids", which laterally change into coral boundstones. In both sections microbialites are not components of the reef framework. They grew around large coral fragments on the flanks of the patch reefs. The microbialites that form low relief domes developed on a nearly flat, stable seafloor seawards of the patch reef. The "megaoncoids" in the southern section formed as a result of downslope movement of coral fragments coated by microbialite/coralline algal crust. The steep slope at the flank of the patch reef favoured falling and overturning of encrusted corals and continued growth of microbial crusts on other sides of nodules.
Miocene crustose coralline algae (CCA) from the South East Asia are poorly known, although the Miocene is the epoch of the onset of the biodiversity hotspot in the region and CCA are crucial to understand the evolutionary history of reef building. To fill this knowledge gap, CCA from Lower and Middle Miocene reefs and related carbonates in the Kutai Basin in East Kalimantan (Borneo, Indonesia) have been studied. The Kutai Basin was dominated by siliciclastic sediments of the Proto-Mahakam delta and only locally carbonate buildups occur laterally to or within the deltaic succession. CCA in the Kutai Basin occur in low-energy shallow-water platform carbonates and in association with coral reefs, encrusting the corals or bioclasts. Two main CCA assemblages have been recognized: 1) A shallow-water assemblage (S-assemblage), dominated by Neogoniolithon spp., thick crusts of Spongites spp., and Hydrolithon spp.; and 2) the D-assemblage, mainly consisting of thin crusts of Lithothamnion spp., Mesophyllum spp., and Sporolithon spp., which grew in darker waters. Light reduction in reefs in the Proto-Mahakam delta was due to increased water depth or higher turbidity by higher siliciclastic input. Assemblages with intermediate composition (I-assemblages) can also be found. Common CCA with large cells fusions and groups of heterocysts, typical features of modern reef CCA, in the S-assemblages in the Middle Miocene of East Kalimantan reflect the initiation of the reef-building CCA flora in the Indo-Pacific region. The occurrence of this kind of CCA confirms the biogeographic differentiation of a tropical reef flora.
1 aRösler, Anja1 aPretković, Vedrana1 aNovak, Vibor1 aRenema, Willem1 aBraga, Juan, C. uhttps://ipaeg.myspecies.info/node/204000700nas a2200205 4500008004600000245009700046210006900143100002800212700001700240700002400257700002100281700001800302700002500320700002100345700001700366700002400383700001900407700002500426856004300451 Submitted eng d 00aA diverse patch reef from turbid habitats in the Middle Miocene (East Kalimantan, Indonesia)0 adiverse patch reef from turbid habitats in the Middle Miocene Ea1 aSantodomingo, Nadiezhda1 aNovak, Vibor1 aPretković, Vedrana1 aMarshall, Nathan1 aRösler, Anja1 aDi Martino, Emanuela1 aLoGiudice, Elena1 aReich, Sonja1 aBraga, Juan, Carlos1 aRenema, Willem1 aJohnson, Kenneth, G. uhttps://ipaeg.myspecies.info/node/203302842nas a2200205 4500008004100000245012500041210006900166300001200235490000800247520207100255100001702326700002802343700001802371700002502389700002402414700002002438700002502458700001902483856013402502 2013 eng d00aEnvironmental reconstruction of a late Burdigalian (Miocene) patch reef in deltaic deposits (East Kalimantan, Indonesia)0 aEnvironmental reconstruction of a late Burdigalian Miocene patch a110-1220 v3743 aMost studies of Cenozoic shallow-water, mixed carbonate-siliciclastic depositional systems have focused on their sedimentology. To date, however, comprehensive analyses of biotas and biofacies of Indo-West Pacific reefs that developed in mixed carbonate-siliciclastic systems are lacking. This study describes the palaeoenvironment and biodiversity of a late Burdigalian patch reef that developed in a mixed carbonate-siliciclastic depositional system. The studied exposure is located at the northeast margin of the Kutai Basin near Bontang (Indonesia), and is approximately 80 m wide and 25 m thick. Multi-taxon analysis of the most abundant fossil groups, including larger benthic foraminifera, corals, coralline algae, and bryozoans, aims to provide a model for environmental interpretation that will allow comparison with similar deposits of Indo-West Pacific region. Based on fossil content and lithology, five different facies types have been distinguished: foraminiferal packstone (FP), bioclastic packstone with foralgal communities (BP), thin-platy coral sheetstone (CS), platy-tabular coral platestone (CP), and shales (S). Among larger benthic foraminifera, smaller and more robust forms dominate in the FP and BP facies, while larger and flatter forms are the most abundant in the CS and CP facies. Thin-platy corals are dominant in the CS facies and gradually change into thicker platy-tabular forms in the CP facies. Assemblages and growth forms of coralline algae show no major differences between the facies types and are dominated by melobesioids and Sporolithon. The majority of bryozoan species are encrusting and were found only in the CS facies. Light-dependent organisms occurring in the reef indicate low light conditions typical for mesophotic reefs. The relatively small size of this reef complex and quite distinct vertical changes in the facies types, combined with the high siliciclastic content in most of the units, points to strong terrigenous input affecting water transparency as the main factor controlling the reef growth.
1 aNovak, Vibor1 aSantodomingo, Nadiezhda1 aRösler, Anja1 aDi Martino, Emanuela1 aBraga, Juan, Carlos1 aTaylor, Paul, D1 aJohnson, Kenneth, G.1 aRenema, Willem uhttps://ipaeg.myspecies.info/content/environmental-reconstruction-late-burdigalian-miocene-patch-reef-deltaic-deposits-east-kalim00923nas a2200289 4500008004100000245008400041210006900125260003500194300000800229490000700237653001400244653002400258653001200282653003800294653001600332100002800348700001700376700002100393700002500414700002100439700002100460700002400481700001800505700001900523700002500542856006600567 2012 eng d00aDevelopment of a turbid reef in the Middle Miocene (East Kalimantan, Indonesia)0 aDevelopment of a turbid reef in the Middle Miocene East Kalimant aCharlotte, North Carolina, USA a6230 v7710aINDONESIA10amarginal ecosystems10aMiocene10apalaeonvironmental reconstruction10apatch reefs1 aSantodomingo, Nadiezhda1 aNovak, Vibor1 aMarshall, Nathan1 aDi Martino, Emanuela1 aFraser, Nicholas1 aLoGiudice, Elena1 aPretković, Vedrana1 aRösler, Anja1 aRenema, Willem1 aJohnson, Kenneth, G. uhttps://gsa.confex.com/gsa/2012AM/webprogram/Paper209284.html00771nas a2200181 4500008004100000245013200041210006900173260003600242100002500278700002100303700001700324700002800341700001800369700002400387700002500411700001900436856013400455 2012 eng d00aPalaeoenvironmental reconstruction of a Miocene patch reef in East Kalimantan (Indonesia): a close-up on the bryozoan component0 aPalaeoenvironmental reconstruction of a Miocene patch reef in Ea aBrno Czech Republicc31/05/20121 aDi Martino, Emanuela1 aTaylor, Paul, D.1 aNovak, Vibor1 aSantodomingo, Nadiezhda1 aRösler, Anja1 aBraga, Juan, Carlos1 aJohnson, Kenneth, G.1 aRenema, Willem uhttps://ipaeg.myspecies.info/content/palaeoenvironmental-reconstruction-miocene-patch-reef-east-kalimantan-indonesia-close-bryozo00682nas a2200181 4500008004100000245008700041210006900128260001500197100001700212700002800229700001800257700002500275700002000300700002000320700002500340700001900365856011600384 2012 eng d00aEnvironmental reconstruction of a Langhian patch reef (East Kalimantan, Indonesia)0 aEnvironmental reconstruction of a Langhian patch reef East Kalim c29/03/20121 aNovak, Vibor1 aSantodomingo, Nadiezhda1 aRösler, Anja1 aDi Martino, Emanuela1 aBraga, Juan, C.1 aTaylor, Paul, D1 aJohnson, Kenneth, G.1 aRenema, Willem uhttps://ipaeg.myspecies.info/content/environmental-reconstruction-langhian-patch-reef-east-kalimantan-indonesia00669nas a2200181 4500008004100000245007200041210006900113260003100182100002500213700002100238700001700259700002800276700001800304700002400322700002500346700001900371856009700390 2012 eng d00aBryozoans from a Langhian patch reef in East Kalimantan (Indonesia)0 aBryozoans from a Langhian patch reef in East Kalimantan Indonesi aCatania, Italyc24/05/20121 aDi Martino, Emanuela1 aTaylor, Paul, D.1 aNovak, Vibor1 aSantodomingo, Nadiezhda1 aRösler, Anja1 aBraga, Juan, Carlos1 aJohnson, Kenneth, G.1 aRenema, Willem uhttps://ipaeg.myspecies.info/content/bryozoans-langhian-patch-reef-east-kalimantan-indonesia