Palynodiversity patterns and paleoclimatic changes in the late paleozoic in Brazil and Uruguay

La diversidad palinológica y los cambios climáticos en el Paleozoico Superior en Brasil y Uruguay

Beri Castagnin, Lourdes de los Ángeles - Martínez Blanco, Ximena - Tejera, Leticia - Piñeyro, Andrea - Souza, P. A.

Resumen:

We have analysed the diversity of the late Paleozoic palynoflora of the Paraná (Brazil and Uruguay), Parnaíba and Amazon (Brazil) basins using already published data. In order to do this the total diversity and diversity with range-through approach curves were built up, as well as Foote’s appearance and disappearance rates at the generic level. These parameters were also obtained separately for each group of sporomorphs. An important increase in diversity in the Asselian and Sakmarian and a posterior decrease until the Lopingian were observed. The values of the appearance rates were higher than those of disappearance and they peaked in the Asselian, while the highest disappearances took place in the Capitanian and, to a lesser extent, in the Sakmarian. On the other hand, spores and pollen grains show some differences in the general diversity trend. However, there are differences in the patterns of appearance and disappearance. Despite possible biases, mainly related to the collecting effort, the diversity curves and appearance and disappearance rates obtained are congruent with the climatic phases proposed for this region in these periods. The increase in the number of palynomorph genera is associated to the early Permian climatic amelioration whilst a decrease in diversity is related to the beginning of an arid phase.


Se analizó la diversidad de la palinoflora correspondiente a estratos del Paleozoico superior de las cuencas de Paraná (Brasil y Uruguay), Parnaíba y Amazonas (Brasil), utilizando datos previamente publicados. Se elaboraron curvas de diversidad total y diversidad calculadas mediante el método range-through y se calcularon los índices de aparición y desaparición de los diferentes géneros utilizando como herramienta el índice de Foote. También se analizaron esos parámetros en diferentes grupos de esporomorfos por separado. Se observó un aumento importante de la diversidad en el Asseliano y Sakmariano y una posterior disminución gradual hasta el Lopingiano. Los valores de los índices de aparición fueron más importantes que los de desaparición y se dieron en el Asseliano, mientras que las mayores desapariciones se observaron en el Capitaniano y en menor medida en el Sakmariano. Por otra parte, las esporas y los granos de polen presentan algunas diferencias en la tendencia general de diversidad. Sin embargo, se aprecian diferencias en los patrones de aparición y desaparición. A pesar de los posibles sesgos, fundamentalmente relacionados con el esfuerzo de colecta, existe cierta coherencia entre la diversidad, los índices de apariciones y desapariciones y las fases climáticas propuestas para esa edad en la región. El cambio hacia un clima más templado ocurrido en el Pérmico inferior estaría asociado a un aumento en el número de géneros de palinomorfos mientras que el comienzo de una fase más árida estaría relacionado a una disminución en la diversidad.


Detalles Bibliográficos
2018
Diversity
Paleozoic
Palynology
Inglés
Universidad de la República
COLIBRI
https://hdl.handle.net/20.500.12008/26333
Acceso abierto
Licencia Creative Commons Atribución - No Comercial - Sin Derivadas (CC - By-NC-ND 4.0)
Resumen:
Sumario:We have analysed the diversity of the late Paleozoic palynoflora of the Paraná (Brazil and Uruguay), Parnaíba and Amazon (Brazil) basins using already published data. In order to do this the total diversity and diversity with range-through approach curves were built up, as well as Foote’s appearance and disappearance rates at the generic level. These parameters were also obtained separately for each group of sporomorphs. An important increase in diversity in the Asselian and Sakmarian and a posterior decrease until the Lopingian were observed. The values of the appearance rates were higher than those of disappearance and they peaked in the Asselian, while the highest disappearances took place in the Capitanian and, to a lesser extent, in the Sakmarian. On the other hand, spores and pollen grains show some differences in the general diversity trend. However, there are differences in the patterns of appearance and disappearance. Despite possible biases, mainly related to the collecting effort, the diversity curves and appearance and disappearance rates obtained are congruent with the climatic phases proposed for this region in these periods. The increase in the number of palynomorph genera is associated to the early Permian climatic amelioration whilst a decrease in diversity is related to the beginning of an arid phase.