Evaluating the effect of marine diagenesis on late Miocene pre-evaporitic sedimentary successions of Eastern Mediterranean Sea
Antonarakou, Assimina (Panepistēmio Athēnōn. Department of Historical Geology and Paleontology)
Kontakiotis, George (Panepistēmio Athēnōn. Department of Historical Geology and Paleontology)
Vasilatos, Charalampos (Panepistēmio Athēnōn. Department of Historical Geology and Paleontology)
Besiou, Eva (Panepistēmio Athēnōn. Department of Historical Geology and Paleontology)
Zarkogiannis, Stergios (Panepistēmio Athēnōn. Department of Historical Geology and Paleontology)
Drinia, Hara (Panepistēmio Athēnōn. Department of Historical Geology and Paleontology)
Mortyn, P. Graham (Universitat Autònoma de Barcelona. Institut de Ciència i Tecnologia Ambientals)
Tsaparas, Nikolaos (Panepistēmio Athēnōn. Department of Historical Geology and Paleontology)
Makri, Panayota (Panepistēmio Athēnōn. Department of Historical Geology and Paleontology)
Karakitsios, Vasileios (Panepistēmio Athēnōn. Department of Historical Geology and Paleontology)
Universitat Autònoma de Barcelona.
Departament de Geografia
Data: |
2019 |
Resum: |
The microstructure and geochemical composition of foraminiferal tests are valuable archives for the reconstruction of paleoclimatic and paleoecological changes. In this context, the late Miocene Globigerinoides obliquus shells from Faneromeni section (Crete Island) were investigated through Scanning Electron Microscopy (SEM) imaging, Energy Dispersive System (EDS) analysis and X-Ray Diffraction (XRD) spectroscopy in order to evaluate their potential as paleoenvironmental archives in the eastern Mediterranean. Investigation of diagenetic features, in late Miocene sediments from the Faneromeni section, shows that carbonate precipitation and cementation occur in various lithologies, particularly in carbonate-rich portions, such as bioclastic or clayey limestones. We identified 3 different diagenetic stages (early, intermediate, advanced), as a function of taphonomy in the study area. The comparison of microstructural and geochemical characteristics reveals a sequence of preservation states with "glassy" to "frosty" to "chalky" shells, indicative of the progressive diagenetic alteration of late Miocene planktic foraminiferal calcite. The early diagenetic stage occurs during the Tortonian, and consists of intermediates between "glassy" and "frosty" individuals. Around the Tortonian/Messinian (T/M) boundary at the second diagenetic stage, planktonic foraminifera have a clear "frosty" appearance, showing a gradual high-Mg calcite (to dolomite) crystal overgrowth development and dissolution of biogenic calcite. During the late Messinian and progressively through the Messinian Salinity Crisis (MSC), planktonic foraminifera present a "chalky" taphonomy. The additional precipitation of authigenic high-Mg inorganic calcite and dolomite crystals in the exterior of the tests characterizes the advanced diagenetic stage. The measured amount of diagenetic Mg-rich (10-14% molar Mg on average) calcite and/or dolomite coatings is compatible with results obtained on modern eastern Mediterranean core-top sediments. The assessment of such a diagenetic alteration contributes to a more precise reconstruction of sea surface temperatures (SSTs) during the Neogene, such that only when the changing proportions of the texture are accounted for, would geochemical measurements and subsequent paleoenvironmental interpretations be more meaningful. However, further investigations should extend this approach to test the robustness of our findings across a range of taphonomies, ages and burial settings. |
Nota: |
Unidad de excelencia María de Maeztu MdM-2015-0552 |
Drets: |
Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original. |
Llengua: |
Anglès |
Document: |
Article ; recerca ; Versió publicada |
Publicat a: |
IOP conference series: Earth and environmental science, Vol. 221, conference 1 (2019) , art. 012051, ISSN 1755-1315 |
DOI: 10.1088/1755-1315/221/1/012051
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Registre creat el 2019-05-20, darrera modificació el 2021-08-07