INVESTIGADORES
BRESSAN Graciela Susana
artículos
Título:
Análisis tafonómico de las concentraciones fósiles de la Formación La Manga (Oxfordiano), Cuenca Neuquina, Provincia de Mendoza, Argentina
Autor/es:
BRESSAN, GRACIELA S.; PALMA, RICARDO M.
Revista:
JOURNAL OF IBERIAN GEOLOGY
Editorial:
SERVICIO PUBLICACIONES
Referencias:
Lugar: Madrid; Año: 2010 vol. 36 p. 55 - 71
ISSN:
1698-6180
Resumen:
Griphaeid-dominated
fossil concentrations of La Manga Formation are characterized on the
basis of taphonomic, sedimentologic, stratigraphic and palaeoecologic
criteria. These concentrations are present in the basal deposits (Unit
1) of three outcrops in the locality of Bardas Blancas. Their
attributes allow distinguishing seven different fossil accumulations:
A) Channelized fossil concentrations of Gryphaea sp.; B) Shell beds of Gryphaea sp. highly reworked; C) Shell beds of Gryphaea sp. moderately reworked; D) Accumulations of Gryphaea
sp. with biomicrite to biopelmicrite matrix; E) Shell detritus; F)
Accumulations produced by bottom currents; and G) Accumulations found
in clumps. Accumulations A-C were deposited by high energy processes
(storm waves and currents) in the upper middle ramp. Accumulations D
and E were produced by high energy processes (storm waves and currents)
but the final depositions were produced out of suspension in low energy
environments, in lower middle ramp settings. Accumulations F were
generated by weak bottom currents, meanwhile accumulations G correspond
to gryphaeids associations reworked by bioturbators. Both are
interpreted as lower middle or outer ramp. This interpretation suggests
that these deposits that in previous works were interpreted as outer
ramp settings, characterize middle and outer ramp settings. The
vertical distribution of fossil concentrations from upper middle ramp
to lower middle and outer ramp settings evidences a continuously
growing accommodation space and allows to interpret the Unit 1 as part
of a transgressive systems tract.