(2012); ** mean age (U e Pb SHRIMP) of the Candiota, Faxinal and Leão-Butiá coal fi elds obtained in the present study. " height="100" width="auto" style="height:100px;" data-reactid="184"/ABSTRACT: Apresenta-se aqui uma síntese da composição da paleoflora preservada em siltitos argilosos do Membro Siderópolis, Formação Rio Bonito tendo como objetivo estabelecer comparações fitoestratigráficas com outras paleofloras neopensilvanianas e cisuralianas da Bacia do Paraná.
A Formação Rio Bonito, a mais importante das unidades litoestratigráficas portadoras de carvão da Bacia do Paraná, pertence à supersequência Gondwana I (Pensilvaniano-Eotriássico).
Additionally, elements may exist in different isotopes, with each isotope of an element differing only in the number of neutrons in the nucleus.
A particular isotope of a particular element is called a nuclide. That is, at some random point in time, an atom of such a nuclide will be transformed into a different nuclide by the process known as radioactive decay.
All ordinary matter is made up of combinations of chemical elements, each with its own atomic number, indicating the number of protons in the atomic nucleus.
The methods I utilize involve electron microprobe (EMP), secondary ion mass spectrometry (SIMS), nano SIMS, and inductively coupled plasma mass spectrometry (ICP-MS).
One of the exciting and challenging components of my research is finding analytical techniques to answer complicated petrogenetic questions.
The radiometric age of 291 ± 1.2 Ma obtained through single-crystal zircon U-Pb ages (Sensitive High Resolution Ion Micro Probe - SHRIMP II) of tonsteins from the Leão-Butiá Coalfield, southern Paraná Basin (Rio Grande do Sul state), associated with previous SHRIMP II radiometric data obtained from tonsteins from the western (Candiota Coalfield) and eastern (Faxinal and Leão-Butiá coalfields) borders of the basin indicate that the mean age of the main peat-forming interval is 291.0 ± 1.3 Ma.
In a regional context, the mean age represents a consistent geochronological correlation for the uppermost and more important coal seams in southern Brazilian coalfields, but this assumption does not establish an ash fall origin from a single volcanic event.