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Microbial carbonates in Miocene reefs in the Mahakam Delta in East Kalimantan, Borneo, Indonesia
| Content Provider | Semantic Scholar |
|---|---|
| Author | Pretković, Vedrana Braga, Juan Carlos Rösler, Anja |
| Copyright Year | 2013 |
| Abstract | permitted field trip carried out. Moreover, quarries in the Ruster Hills (e.g., so called Roemersteinbruch St. Margarethen) and in southern Styria (subsurface Roemerbruch Aflenz) were also part of the excursion. Further samples of Leitha Limestone quarries from Nußdorf (Vienna) and Pfaffenberg (Deutsch-Altenburg) were studied for comparison. Carbonate microfacies analysis of 70 thin sections by stereo microscope was applied, quantity estimations are based on comparison charts. From the 30 quarries that were subject to general survey, rock samples were taken for macroscopic identification and some of them chosen for preparation of thin sections. From 12 of these quarries additional cores (35 mm diameter, up to 15 cm long) were drilled. The core samples served for geophysical and geotechnical laboratory tests and for thin sections as well. The field investigations and quarry descriptions contribute to the mineral raw-materials archive and database of the Geological Survey. Based on the available geological maps the Leitha Limestone succession covers a basement relief, which occurs as topographical heights, called Schieferberg, Zeilerberg and Königsberg with Semmeringquarzit and Middle Triassic dolomite and with the latter cropping out as erosional and quarry relics south of Kaisersteinbruch. Although the map differentiates between Badenian 'Leithakalk' and Sarmatian 'detritaerer Leithakalk', this was not obviously recognizable in the field. The thin sections were grouped according to their microfacies characteristics and resulted in: Micro-breccias and conglomerates with reworked dolomite basement rocks, (par-)autochthonous bioclastic corallinacean-bryozoan boundstones as well as bryozoanserpulid boundstones, packand rudstones with mainly corallinacean algae and eventually rhodolithes, well sorted grainand rudstones (detrital calcareous sandstones) with varying amounts of corallinacean algae, bioclasts, foraminifers and lithoclasts. Occasionally important are mixed carbonate-siliciclastic types. Few samples are dominated by molluscs. Some textures, cements and diagenetic features are indicative of special environments. Concerning the coralline algae flora, up to now, mainly Lithothamnium, Lithophyllum and Sporolithon were recognized. A preliminary age differentiation between Badenian and Sarmatian is mainly based on foraminifers and the occurrence of ooids. It can be concluded that the microfossil record in the thin-sections from these isolated samples could be identified to a limited extend. The resulting microfacies types were tested for their regional extent. For further investigation, the significance of these samples should be proven as they should serve for recognition in stone monuments, and for lithostratigraphical contribution. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://opac.geologie.ac.at/wwwopacx/wwwopac.ashx?command=getcontent&server=images&value=BR0099_112_A.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
