First record of Oceanic Anoxic Event 2 in the Eastern Carpathians: implications for chemostratigraphic and biostratigraphic correlations
This study aims to investigate a marlstone and claystone succession located at the southern end of the Eastern Carpathians, a region where oceanic anoxic event 2 (OAE2) has not been pointed out so far. Toward the upper half of this succession, a 17-cm-thick black shale was identified. The investigat...
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| Format: | Article |
| Language: | English |
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Frontiers Media S.A.
2023-09-01
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| Series: | Frontiers in Earth Science |
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| Online Access: | https://www.frontiersin.org/articles/10.3389/feart.2023.1155482/full |
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| author | Mihaela Melinte-Dobrinescu Mihaela Melinte-Dobrinescu Gabriel Ion Eliza Anton Vlad Apotrosoaei Vlad Apotrosoaei Andrei Briceag Constantin Lazăr Constantin Lazăr |
| author_facet | Mihaela Melinte-Dobrinescu Mihaela Melinte-Dobrinescu Gabriel Ion Eliza Anton Vlad Apotrosoaei Vlad Apotrosoaei Andrei Briceag Constantin Lazăr Constantin Lazăr |
| author_sort | Mihaela Melinte-Dobrinescu |
| collection | DOAJ |
| description | This study aims to investigate a marlstone and claystone succession located at the southern end of the Eastern Carpathians, a region where oceanic anoxic event 2 (OAE2) has not been pointed out so far. Toward the upper half of this succession, a 17-cm-thick black shale was identified. The investigated depositional interval lies within the late Cenomanian–early Turonian, encompassing the UC3d up to UC7 nannofossil zones. The δ13C values fluctuated between 2.06‰ and 3.89‰, showing a positive isotope excursion that was assigned to OAE2. The δ13C isotope curve displays the following intervals: pre-excursion, first build-up, trough, second build-up, plateau, and post-excursion. Within the second build-up interval of OAE2, a substantial shift in CaCO3 values, accompanied by high concentrations of total organic carbon and a significant decline in the abundance and diversity of calcareous nannofossil assemblages, was observed. The nannofossil turnover related to OAE2 climax revealed predominance of Watznaueria barnesiae and temporary disappearance from the record of surface-water higher fertility taxa, such as Biscutum constans, Zeugrhabdotus erectus, and Discorhabdus ignotus. Above OAE2, peaks of Eprolithus floralis, followed by increased abundance of Eiffellithus turriseiffelii and Nannoconus spp., were identified. In the lower part of the studied succession (i.e., the upper Cenomanian UC3d nannofossil subzone), during the pre-excursion characterized by low δ13C values and less negative δ18O values, a small group of nannofossils more related to mid- and high-paleolatitudes, such as Crucibiscutum salebrosum, Repagulum parvidentatum, and Seribiscutum primitivum, is present, always showing a low abundance. |
| first_indexed | 2024-03-12T02:09:23Z |
| format | Article |
| id | doaj.art-9976d0fe803449db8081ad8a9ed55e58 |
| institution | Directory Open Access Journal |
| issn | 2296-6463 |
| language | English |
| last_indexed | 2024-03-12T02:09:23Z |
| publishDate | 2023-09-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Earth Science |
| spelling | doaj.art-9976d0fe803449db8081ad8a9ed55e582023-09-06T17:43:22ZengFrontiers Media S.A.Frontiers in Earth Science2296-64632023-09-011110.3389/feart.2023.11554821155482First record of Oceanic Anoxic Event 2 in the Eastern Carpathians: implications for chemostratigraphic and biostratigraphic correlationsMihaela Melinte-Dobrinescu0Mihaela Melinte-Dobrinescu1Gabriel Ion2Eliza Anton3Vlad Apotrosoaei4Vlad Apotrosoaei5Andrei Briceag6Constantin Lazăr7Constantin Lazăr8National Institute of Marine Geology and Geo-ecology, Bucharest, RomaniaDoctoral School of Geology, University of Bucharest, Bucharest, RomaniaNational Institute of Marine Geology and Geo-ecology, Bucharest, RomaniaNational Institute of Marine Geology and Geo-ecology, Bucharest, RomaniaNational Institute of Marine Geology and Geo-ecology, Bucharest, RomaniaDoctoral School of Geology, University of Bucharest, Bucharest, RomaniaNational Institute of Marine Geology and Geo-ecology, Bucharest, RomaniaNational Institute of Marine Geology and Geo-ecology, Bucharest, RomaniaDoctoral School of Geology, University of Bucharest, Bucharest, RomaniaThis study aims to investigate a marlstone and claystone succession located at the southern end of the Eastern Carpathians, a region where oceanic anoxic event 2 (OAE2) has not been pointed out so far. Toward the upper half of this succession, a 17-cm-thick black shale was identified. The investigated depositional interval lies within the late Cenomanian–early Turonian, encompassing the UC3d up to UC7 nannofossil zones. The δ13C values fluctuated between 2.06‰ and 3.89‰, showing a positive isotope excursion that was assigned to OAE2. The δ13C isotope curve displays the following intervals: pre-excursion, first build-up, trough, second build-up, plateau, and post-excursion. Within the second build-up interval of OAE2, a substantial shift in CaCO3 values, accompanied by high concentrations of total organic carbon and a significant decline in the abundance and diversity of calcareous nannofossil assemblages, was observed. The nannofossil turnover related to OAE2 climax revealed predominance of Watznaueria barnesiae and temporary disappearance from the record of surface-water higher fertility taxa, such as Biscutum constans, Zeugrhabdotus erectus, and Discorhabdus ignotus. Above OAE2, peaks of Eprolithus floralis, followed by increased abundance of Eiffellithus turriseiffelii and Nannoconus spp., were identified. In the lower part of the studied succession (i.e., the upper Cenomanian UC3d nannofossil subzone), during the pre-excursion characterized by low δ13C values and less negative δ18O values, a small group of nannofossils more related to mid- and high-paleolatitudes, such as Crucibiscutum salebrosum, Repagulum parvidentatum, and Seribiscutum primitivum, is present, always showing a low abundance.https://www.frontiersin.org/articles/10.3389/feart.2023.1155482/fullCenomanian-Turonian boundarycalcareous nannofossilsδ13C positive excursionpaleoenvironmentpaleobiogeography |
| spellingShingle | Mihaela Melinte-Dobrinescu Mihaela Melinte-Dobrinescu Gabriel Ion Eliza Anton Vlad Apotrosoaei Vlad Apotrosoaei Andrei Briceag Constantin Lazăr Constantin Lazăr First record of Oceanic Anoxic Event 2 in the Eastern Carpathians: implications for chemostratigraphic and biostratigraphic correlations Frontiers in Earth Science Cenomanian-Turonian boundary calcareous nannofossils δ13C positive excursion paleoenvironment paleobiogeography |
| title | First record of Oceanic Anoxic Event 2 in the Eastern Carpathians: implications for chemostratigraphic and biostratigraphic correlations |
| title_full | First record of Oceanic Anoxic Event 2 in the Eastern Carpathians: implications for chemostratigraphic and biostratigraphic correlations |
| title_fullStr | First record of Oceanic Anoxic Event 2 in the Eastern Carpathians: implications for chemostratigraphic and biostratigraphic correlations |
| title_full_unstemmed | First record of Oceanic Anoxic Event 2 in the Eastern Carpathians: implications for chemostratigraphic and biostratigraphic correlations |
| title_short | First record of Oceanic Anoxic Event 2 in the Eastern Carpathians: implications for chemostratigraphic and biostratigraphic correlations |
| title_sort | first record of oceanic anoxic event 2 in the eastern carpathians implications for chemostratigraphic and biostratigraphic correlations |
| topic | Cenomanian-Turonian boundary calcareous nannofossils δ13C positive excursion paleoenvironment paleobiogeography |
| url | https://www.frontiersin.org/articles/10.3389/feart.2023.1155482/full |
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