Emilia Tulan
Hydrocarbon source rock potential and paleoenvironment of lower Miocene diatomites in the Eastern Carpathians Bend Zone (Sibiciu de Sus, Romania)
Tulan, Emilia; Reinhard, F. Sachsenhofer; Tari, Gabor; Witkowski, Jakub; Tămaș, Dan Mircea; Horvat, Aleksander; Tămaș, Alexandra
Authors
F. Sachsenhofer Reinhard
Gabor Tari
Jakub Witkowski
Dan Mircea Tămaș
Aleksander Horvat
Alexandra Tămaș
Abstract
Diatomites are prolific hydrocarbon source rocks in many basins worldwide. In the broader Carpathians, diagenetically altered diatomites are called menilites, and menilitic shale successions are regarded as the most prolific hydrocarbon source rocks in the region. The abandoned Sibiciu de Sus quarry, located in the Eastern Carpathian Bend Zone of Romania, provides large exposures of the upper part of the Lower Miocene Upper Menilites, composed of various diatomite lithologies, cherts, menilitic shales and quartz-rich sandstone. The sediments are highly deformed due to soft-sediment deformation and subsequent Miocene to Pliocene contractional tectonics. Twenty-two diatom-bearing samples were examined in order (a) to determine the hydrocarbon source rock potential, (b) to document the diatom assemblages and (c) to interpret the depositional environment. The hydrocarbon potential of the studied rocks is considered good to very good, with an average TOC of 3.77 wt. % (max. 9.57 wt. % TOC) and type II–III kerogen (avg. HI: 384 mg HC/g TOC). Tmax does not exceed 424 °C suggesting that the organic matter is thermally immature. Despite that, the Production Index is high (0.1–0.3), which proves the presence of migrated hydrocarbons. The source potential index (SPI) indicates that the exposed section, if mature, could generate about 1.3 t HC/m2. As the diatom preservation does not enable chemical extraction of individual valves, this study describes only genus-level findings. The diatom assemblages are dominated by Aulacoseira and Actinocyclus, whereas Ellerbeckia, Paralia and Rhaphoneis are rarely observed. The diatom assemblages indicate a nearshore, brackish-water depositional setting.
Citation
Tulan, E., Reinhard, F. S., Tari, G., Witkowski, J., Tămaș, D. M., Horvat, A., & Tămaș, A. (2020). Hydrocarbon source rock potential and paleoenvironment of lower Miocene diatomites in the Eastern Carpathians Bend Zone (Sibiciu de Sus, Romania). Geologica Carpathica, 71(5), 424-443. https://doi.org/10.31577/geolcarp.71.5.4
Journal Article Type | Article |
---|---|
Acceptance Date | Sep 21, 2020 |
Publication Date | 2020-10 |
Deposit Date | Nov 27, 2020 |
Publicly Available Date | Nov 27, 2020 |
Journal | Geologica Carpathica |
Print ISSN | 1335-0552 |
Electronic ISSN | 1336-8052 |
Publisher | Veda, Publishing House of the Slovak Academy of Sciences |
Peer Reviewed | Peer Reviewed |
Volume | 71 |
Issue | 5 |
Pages | 424-443 |
DOI | https://doi.org/10.31577/geolcarp.71.5.4 |
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This article has been published under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.
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