@article {2017, title = {Microbial carbonates in Miocene reefs in the Mahakam Delta in East Kalimantan, Indonesia}, journal = {Sedimentary Geology}, address = {Berlin, Germany}, abstract = {

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.

}, author = {Vedrana Pretkovi{\'c} and Juan C. Braga and Vibor Novak and Anja R{\"o}sler and Willem Renema} } @conference {2017, title = {Microbial carbonates in Miocene reefs in the Mahakam Delta in East Kalimantan, Borneo, Indonesia}, booktitle = {SAGE2013 - Southeast Asian Gateway Evolution}, year = {2013}, month = {11/03/2013}, address = {Berlin, Germany}, abstract = {

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.

}, author = {Vedrana Pretkovi{\'c} and Juan C. Braga and Vibor Novak and Anja R{\"o}sler and Willem Renema} } @article {2041, title = {Evolutionary history of the reef building coralline algae (Rhodophyta)}, journal = {Journal of Phycology}, abstract = {

Mastophoroids in the sense of Harvey et al. (2003) are the main components of shallow coral reef environments. Their status as a monophyletic subfamily is lost, but different subsequent proposals about the taxonomic relationships of their genera were declared to be untenable. Here we present a new, more complete phylogeny of Mastophoroideae sensu Harvey et al. (2003) with a temporal dimension reflecting the evolutionary history of this clade which is very important in ecological and structural means in coral reefs. We agree with Kato et al. (2011) to maintain the Lithophylloideae, Corallinoideae and Metagoniolithoideae, to reduce the Mastophoroideae and to establish the new subfamilies Hydrolithoideae, Neogoniolithoideae and Porolithoideae. We propose two new genera Adeylithon gen. nov. with the type species A. conicum and Harveylithon gen. nov. with the type species H. rupestre. The calibration of the molecular clock of the genetic marker SSU supposes a Cenozoic origin of most of the clades of the former mastophoroids sensu Harvey et al. (2003) and a separation from Hapalidiaceae in the boundary between early and late Cretaceous.

}, author = {Anja R{\"o}sler and Francisco Perfectti and Viviana Pe{\~n}a and Juan Carlos Braga} } @article {2040, title = {Coralline Algae from the Miocene Mahakam Delta (East Kalimantan, SE Asia)}, journal = {Palaios}, year = {In Press}, abstract = {

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.

}, author = {Anja R{\"o}sler and Vedrana Pretkovi{\'c} and Vibor Novak and Willem Renema and Juan C. Braga} } @conference {2017, title = {Microbial carbonates in Miocene reefs in the Mahakam Delta in East Kalimantan, Borneo, Indonesia}, booktitle = {SAGE2013 - Southeast Asian Gateway Evolution}, year = {2013}, month = {11/03/2013}, address = {Berlin, Germany}, abstract = {Coral patch reefs grew in shallow marine turbid waters in the Miocene Mahakam Delta in East Kalimantan (Borneo, Indonesia). These patch reefs developed from delta front to deeper (prodelta) settings in areas with temporary reduced siliciclastic input. These coral reef deposits are well exposed in limestone quarries in the Batu Putih area in Samarinda and locally include microbial carbonates. Two different types of microbial carbonates have been found in two localities around Samarinda, 2 km apart from each other. 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. They appear at the transition from bioclastic sediments with coralline algae and corals to fine-grained siliciclastic deposits in a deepening succession. The second type of microbialites can be found in the southern locality as decimetre-scale nodules formed around nuclei of large coral fragments. Microbial micrite with laminated to digitated fabrics intergrew with coralline algae to form the thick covers of these "megaoncoids". The large nodules are the main components of carbonate breccias deposited on the flanks of a patch reef. }, author = {Vedrana Pretkovi{\'c} and Juan C. Braga and Anja R{\"o}sler} } @article {1990, title = {Development of a turbid reef in the Middle Miocene (East Kalimantan, Indonesia)}, journal = {Geological Society of America Abstracts with Programs}, volume = {77}, year = {2012}, pages = {623}, address = {Charlotte, North Carolina, USA}, keywords = {INDONESIA, marginal ecosystems, Miocene, palaeonvironmental reconstruction, patch reefs}, url = {https://gsa.confex.com/gsa/2012AM/webprogram/Paper209284.html}, author = {Nadiezhda Santodomingo and Vibor Novak and Nathan Marshall and Emanuela Di Martino and Nicholas Fraser and Elena LoGiudice and Vedrana Pretkovi{\'c} and Anja R{\"o}sler and Willem Renema and Kenneth G. Johnson} } @conference {1989, title = {Coralline algae from the Miocene Mahakam Delta (East Kalimantan, SE Asia)}, booktitle = {GSA Annual Meeting 2012}, year = {2012}, month = {04/11/12}, address = {Charlotte, USA}, abstract = {Although the Miocene is the epoch of the onset of the biodiversity hotspot in South East Asia, crustose coralline algae (CCA) of this age are poorly known in region. To fill this knowledge gap, crucial to understand the evolutionary history of reef building coralline algae, we studied CCA in Miocene reefs in the Kutai Basin, the largest sedimentary basin in Borneo that was dominated by siliciclastic sediments of the Proto-Mahakam delta. Local carbonate buildups comprising low relief patch reefs occur within the deltaic succession in shallow and turbid water, influenced by high siliciclastic input (Wilson, 2002). CCA in the Kutai basin are mostly found in association with coral reefs, encrusting corals or fragments of them. In beds with very high siliciclastic content no coralline algae were observed in the outcrops, but corals were still present. Two main CCA assemblages have been recognized in the studied Middle Miocene reefs: 1) a shallow-water assemblage, with two species of Neogoniolithon, thick crusts of Spongites, various Hydrolithon and also Sporolithon and Lithoporella. 2) In darker waters preferentilaly grew melobesioid assemblages, dominated by rhodoliths mainly consisting of Lithothamnion or by thin crusts of Mesophyllum and Sporolithon. This last one is the only assemblage found in mesophotic reefs. CCA of East Kalimantan show occurrences of some extant species earlier than expected. These new first-occurrence dates are being used to produce a detailed time tree of the main reef building CCA species with the help of a new molecular phylogeny based on five genetic markers. Wilson Moyra E.J. (2002) Cenozoic carbonates in Southeast Asia: implications for equatorial carbonate development. Sedimentary Geology 147, 295{\textendash} 428}, author = {Anja R{\"o}sler and Juan Carlos Braga} }