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High‐Resolution C‐Isotope, TOC and Biostratigraphic Records of OAE 1a (Aptian) From an Expanded Hemipelagic Cored Succession, Western Tethys: A New Stratigraphic Reference for Global Correlation and Paleoenvironmental Reconstruction
Author(s) -
Castro José M.,
RuizOrtiz Pedro A.,
de Gea Ginés A.,
Aguado Roque,
Jarvis Ian,
Weissert Helmut,
Molina José M.,
Nieto Luis M.,
Pancost Richard D.,
Quijano María L.,
Reolid Matías,
Skelton Peter W.,
LópezRodríguez Carmina,
MartínezRodríguez Rafael
Publication year - 2021
Publication title -
paleoceanography and paleoclimatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.927
H-Index - 127
eISSN - 2572-4525
pISSN - 2572-4517
DOI - 10.1029/2020pa004004
Subject(s) - aptian , geology , paleontology , stratigraphy , sedimentary rock , chemostratigraphy , paleoclimatology , isotopes of carbon , cretaceous , isotope , climate change , tectonics , oceanography , physics , quantum mechanics
A high‐resolution carbonate C‐isotope stratigraphy for the Aptian is presented for the Cau core (Spain). The biostratigraphically calibrated C‐isotope stratigraphy of the core is used to refine the previously defined C‐isotope segments of the Aptian. Thirteen C‐isotope segments have been identified and correlated, and further subdivisions are presented. Correlation with other sections worldwide demonstrates the robustness of the C‐isotope stratigraphy of the Cau core. The studied succession includes a continuous record of the early Aptian Oceanic Anoxic Event (OAE 1a). Its onset has been studied at an ultrahigh‐resolution scale (0.2–0.5 kyr spacing), revealing a succession of sharp δ 13 C carb negative spikes, interpreted as a record of pulses of volcanism and methane emissions. The largest spike was rapid (<10 kyr) and marks the base of OAE 1a, which occurs within a longer‐term falling δ 13 C carb trend. The C‐isotope profile across OAE 1a perfectly records the negative (C3/Ap3), positive (C4/Ap4), steady (C5/Ap5), and positive (C6/Ap6) segments that were defined from Cismon (Italy) and subsequently identified worldwide. The Ap7 to Ap14 segments record a C‐isotope negative excursion, coupled with high TOC contents, probably related to regional paleogeography. The links with global environmental changes, episodes of widespread deposition of organic matter, and ultimately to major volcanic episodes are discussed. We propose the Cau core as a new reference section for the Aptian, and specifically for OAE 1a, based on its expanded and well‐preserved sedimentary, geochemical and biotic archives, which provide further insights into the environmental and biotic changes that occurred during this time interval.