- Tytuł:
- The OAE1a in Cuchía (Early Aptian, Spain): C and O geochemistry and global correlation
- Autorzy:
-
García-Mondéjar, J.
Fernández-Mendiola, P. A.
Owen, H. G. - Powiązania:
- https://bibliotekanauki.pl/articles/139445.pdf
- Data publikacji:
- 2015
- Wydawca:
- Polska Akademia Nauk. Czytelnia Czasopism PAN
- Tematy:
-
Cretaceous
Aptian
Basque-Cantabrian Basin
C-O isotopes
TOC
kreda
apt
izotopy - Opis:
- C-isotopes, TOC and O geochemical data from the lower Aptian Cuchía section in the western Basque-Cantabrian basin (BCB) allow an accurate delimitation of the OAE1a-equivalent and its geochemical Menegatti´s segments, a detailed δ13Ccarb correlation with regional and interregional sections, and a high-resolution construction of TOC and bulk-rock δ18Ocarb curves and their interpretation. The δ13Ccarb values range from -2‰ and +4‰ (VPDB). They agree with previous data from the eastern BCB sections (Aralar) confirming the ammonite age of the OAE1a in the Basque-Cantabrian basin: Deshayesites forbesi, Deshayesites deshayesi, and Deshayesites deshayesi-Dufrenoyia furcata transition Zones. Interregional δ13Ccarb correlation with pelagic (Cismon, Italy, and Mid-Pacific Mountains, DSDP Site 463) and neritic (Roquefort-La Bédoule, France) core sections, reveals a common profile of a wide negative excursion characteristic of the OAE1a. It consists of a double trough separated by a flat relative maximum, with two negative spikes in the upper trough of neritic sections. TOC absolute values range from 0.12% to 1.37%. Segments of the TOC curve with persistent low values closely correspond with descending segments of the δ13Ccarb curve, and are attributed to lesser organic productivity in the BCB. Detailed bulk-rock δ18Ocarb data (-5.71‰ to -1.05 ‰ PDB) and variation curve show two main positive O-isotope shifts and three minor positive inflections, within a general negative trend characteristic of the OAE1a. The two major positive shifts correspond to both shallowing upwards sequences and the lowermost can be related to a eustatic sea level fall. Independent interregional correlation of the O-isotope shifts with C-isotopes supports their interpretation as punctuating colder events within a general warming trend.
- Źródło:
-
Acta Geologica Polonica; 2015, 65, 4; 525-543
0001-5709 - Pojawia się w:
- Acta Geologica Polonica
- Dostawca treści:
- Biblioteka Nauki
Artykuł