Coralline Algae at the Paleocene/Eocene Thermal Maximum in the Southern Pyrenees (N Spain)
Metadatos
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Frontiers
Materia
Rhodolith beds Thermal maximum Paleocene/Eocene boundary Ocean acidification Pyreneen basin
Fecha
2022-07-04Referencia bibliográfica
Aguirre J, Baceta JI and Braga JC (2022) Coralline Algae at the Paleocene/Eocene Thermal Maximum in the Southern Pyrenees (N Spain). Front. Mar. Sci. 9:899877. doi: [10.3389/fmars.2022.899877]
Patrocinador
Spanish Ministerio de Ciencia e Innovacioon PGC2018-099391-B-100; Junta de Andalucia RNM-190; Basque Government Research Programme PGC2018-099391-B-100 IT930-16Resumen
During the Paleocene/Eocene Thermal Maximum, ~55.6 Ma, the Earth experienced the
warmest event of the last 66Ma due to amassive release of CO2. This event lasted for ~100
thousands of years with the consequent ocean acidification (estimated pH = 7.8-7.6). In this
paper, we analyze the effects of this global environmental shift on coralline algal
assemblages in the Campo and Serraduy sections, in the south-central Pyrenees
(Huesca, N Spain), where the PETM is recorded within coastal-to-shallow marine
carbonate and siliciclastic deposits. In both sections, coralline algae occur mostly as
fragments, although rhodoliths and crusts coating other organisms are also frequent.
Rhodoliths occur either dispersed or locally forming dense concentrations (rhodolith beds).
Distichoplax biserialis and geniculate forms (mostly Jania nummulitica) of the order
Corallinales dominated the algal assemblages followed by Sporolithales and Hapalidiales.
Other representatives of Corallinales, namely Spongites, Lithoporella as well as
Neogoniolithon, Karpathia, and Hydrolithon, are less abundant. Species composition
does not change throughout the Paleocene/Eocene boundary but the relative abundance
of coralline algae as components of the carbonate sediments underwent a reduction. They
were abundant during the late Thanetian but became rare during the early Ypresian. This
abundance decrease is due to a drastic change in the local paleoenvironmental conditions
immediately after the boundary. A hardground at the top of the Thanetian carbonates was
followed by continental sedimentation. After that,marine sedimentation resumed in shallow,
very restricted lagoon and peritidal settings, where muddy carbonates rich in benthic
foraminifera, e.g., milioliids (with abundant Alveolina) and soritids, and eventually
stromatolites were deposited. These initial restricted conditions were unfavorable for
coralline algae. Adverse conditions continued to the end of the study sections although
coralline algae reappeared and were locally frequent in some beds, where they occurred
associated with corals. In Serraduy, the marine reflooding was also accompanied by
significant terrigenous supply, precluding algal development. Therefore, the observed
changes in coralline algal assemblages during the PETM in the Pyrenees were most likely
related to local paleoenvironmental shifts rather than to global oceanic or
atmospheric alterations.