Produção Nacional
Inferências paleoambientais a partir de análise de palinofácies da Formação Hidden Lake (Coniaciano, Cretáceo), Bacia Larsen, Ilha James Ross, Antártica
2017; Volume: 20; Issue: 1 Linguagem: Inglês
10.4072/rbp.2017.1.08
ISSN2236-1715
AutoresMonika Beatriz Crud, Marcelo de Araújo Carvalho, Renato Rodríguez Cabral Ramos,
Tópico(s)Geological formations and processes
ResumoSub-basin has one of the most complete sedimentary sequences deposited in the Southern Hemisphere.This work aims to characterize the sedimentary organic matter of 32 samples recovered from HL-1 (64 m) and HL-2 (59 m) sections, assigned to Hidden Lake Formation (Coniacian), thus to identify the paleoenvironmental changes.The Amorphous, Phytoclasts and Palynomorphs groups were identified.The sedimentary organic matter was grouped into amorphous material, opaque phytoclasts, non-opaque phytoclasts, continental palynomorphs and marine palynomorphs.The stratigraphic distribution of the groups revealed three intervals (I-III) for HL-1 section and four for HL-2 (A-D).The paleoenvironmental changes were supported based on facies association (AF-1-AF3), continental/marine ratio and principal components analysis.The two sections were correlated as follow: I/A, II/B and III-C-D.The Interval I/A is characterized by high values of woody material.The Interval II/B continues with high values of woody material; however, the highest peak of amorphous organic matter is recorded in HL-1 section, and the lowest abundance of non-opaque in the HL-2.In the III/C-D is recorded a conspicuous increase in marine elements in both sections.A fan-delta paleoenvironment is suggested for both sections.In section HL-1, a large amount of phytoclasts and volcanoclastic detritus suggests more proximal position in the sedimentary body.In the HL-2 section, a large amount of marine elements suggests normal marine removed from active terrigenous inputs.
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