IGEBA   23946
INSTITUTO DE GEOCIENCIAS BASICAS, APLICADAS Y AMBIENTALES DE BUENOS AIRES
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
ASTRONOMICAL AND MAGNETOSTRATIGRAPHIC CALIBRATION OF THE UPPERMOST JURASSIC THROUGH LOWERMOST CRETACEOUS IN THE NEUQUÉN BASIN, ARGENTINA: A CONTRIBUTION FROM THE SOUTHERN HEMISPHERE TO THE GEOLOGIC TIME SCALE
Autor/es:
KIETZMANN, D.A.; KOHAN MARTINEZ, M.; OGG, J.G.; IGLESIA-LLANOS, M.P.
Lugar:
Indianapollis
Reunión:
Congreso; GSA Annual Meeting 2018; 2018
Institución organizadora:
The Geological Society of America
Resumen:
Detailed cyclostratigraphic analyses have been made from five Tithonian?Berriasian sections of the Vaca Muerta Formation, exposed in the Neuquén Basin, Argentina. The Vaca Muerta Formation is characterized by decimeter-scale rhythmic alternations of marlstones and limestones, showing a well-ordered hierarchy of cycles, where elementary cycles, bundles of cycles and superbundles have been recognized. According to biostratigraphic data, elementary cycles have a periodicity of ~21 kyr, which correlates with the precession cycle of Earth?s axis. Spectral analysis based on time series of elementary cycle thickness allows us to identify frequencies of ~400 kyr and ~90-120 kyr, which we interpret as the modulation of the precession cycle by the Earth?s orbital eccentricity.Correlation between studied sections allowed us to estimate a minimum duration for each Andean ammonite zone. Moreover, cyclostratigraphic data allowed us to build the first continuous floating astronomical time scale for the Tithonian ? Berriasian anchored to the magnetic polarity time scale through magnetostratigraphy. We estimated a minimum duration of 5.67 myr for the Tithonian and 5.27 myr for the Berriasian.