Santonian dinocyst assemblages of the Santa Marta Formation, Antarctic Peninsula: Inferences for paleoenvironments and paleoecology

To better understand the paleoenvironments of the lower-middle Santonian, dinocyst data were obtained from the Santa Marta Formation, Larsen Basin, James Ross Island, Antarctic Peninsula. This study provides the first available quantitative dinocyst data for the Santa Marta Formation, which should m...

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Bibliographic Details
Published in:Anais da Academia Brasileira de Ciências
Main Authors: SUSAN P. CASTRO, MARCELO A. CARVALHO
Format: Article in Journal/Newspaper
Language:English
Published: Academia Brasileira de Ciências 2015
Subjects:
Dinocistos santonianos
Antártica
Cretáceo
Formação Santa Marta
florações de dinocistos
Science
Q
Antarctic
Antarctic Peninsula
Ross Island
Larsen Basin
Lachman
Lachman Crags
Antarc*
James Ross Island
Online Access:https://doi.org/10.1590/0001-3765201520140651
https://doaj.org/article/6aaa66bcdefa482e8131efc3468a6663
Description
Summary:To better understand the paleoenvironments of the lower-middle Santonian, dinocyst data were obtained from the Santa Marta Formation, Larsen Basin, James Ross Island, Antarctic Peninsula. This study provides the first available quantitative dinocyst data for the Santa Marta Formation, which should more clearly reflect detailed changes in paleoenvironments, as recorded by fluctuations in diversity and abundance. To record the Santonian dinocyst assemblages from the Larsen Basin, 30 samples from an outcrop of the Lachman Crags Member (LC section) were analyzed. These assemblages are dominated by peridiniacean dinocysts typical of the Isabelidinium flora. A lower-middle Santonian age was determined after the recognition of Odontochitina poriferaand Isabelidinium cretaceum zones. Cluster analysis based on quantitative data, yielded five dinocyst assemblages: Manumiella, Heterosphaeridium, Chlamydophorella, Isabelidinium and Odontochitina. Two Santonian blooms, Isabelidinium and Odontochitina,recognized in other regions were also recorded in the studied section. The stratigraphic distribution shows an alternation between the assemblages, distinguishing in the section six intervals. The high abundance of the Manumiella assemblage at the uppermost interval of the section represents the shallower setting, whereas the high abundance of Odontochitina at the middle part of the section represents the deepest setting.

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