Abstract

LOPEZ DE AZAREVICH, Vanina L.; AZAREVICH, Miguel B.  and  OMARINI, Ricardo H.. New methodologies applied to the study of platform sequences in the Ediacaran-Lower Cambrian Basement from NW argentina (Puncoviscana Formation). Ser. correl. geol. [online]. 2010, vol.26, n.2, pp.103-120. ISSN 1666-9479.

New methodologies applied to the study of clastic rhythmic sequences of tidal origin in the Puncoviscana Formation provide a new conception on the paleoenvironments of the basin and constitute a key for the comprehension of paleoastronomic parameters that affected tides at the Ediacaran-Cambrian boundary in NW Argentina. Application of Fast Fourier Transforms to lamina thickness variations in tidal rhythmites was developed in last 25 years in old and modern rocks, and implemented in Argentina since 2008 in the Ediacaran-Early Cambrian Puncoviscana Formation. This methodology allows recognition of lunar cycles (synodic, anomalistic, tropical) from patterns obtained in period versus power spectral density graphics, and how these periodic component infuenced in the tidal record. Also, this method can be used for calculate the Earth-Moon distance for time of deposition. So the estimation of lunar retreat rate has been calculated as 7.31 cm/year for the period 620-523 Ma and 2.70 cm/years for 523-305 Ma.

Keywords : Tidal rhythmites; Fast Fourier Transforms; Earth-Moon distance; Puncoviscana Formation; Northwest Argentina.

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