MACNBR   00242
MUSEO ARGENTINO DE CIENCIAS NATURALES "BERNARDINO RIVADAVIA"
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Spore diversity during the Middle Devonian, a case study
Autor/es:
NOETINGER, S.
Lugar:
San Francisco
Reunión:
Encuentro; AASP 46th Annual Meeting; 2013
Resumen:
A fairly well preserved palynological association from the Tonono Formation, recovered from the Santa Victoria x-1 well in northwestern Argentina, allowed for the analysis of spore biodiversity between the interval of 2020 - 2881 mbgs. Thirty-seven cutting samples, comprising 74 spore and five cryptospore species along with other components such as acritarchs, prasinophytes and chitinozoans, were studied. Both, marine and continental elements, sustain a marginal depositional setting, with presumably little shoreline shifts. Several taxa with well known stratigraphical distribution were recognized. An early Eifelian age is proposed for the lower part of the studied interval, marked by the last occurrence of Dibolisporites eifeliensis (Lanninger) McGregor in the sample MACN-exCG-Pl 766 (2380 mbgs). The concurrence of species whose last records are in the late Eifelian or early Givetian, such as Ambitisporites avitus Hoffmeister, Cymbosporites senex McGregor and Camfield, Dibolisporites quebecensis McGregor, together with other ones registered since the late Eifelian such as Biharisporites parviornatus Richardson, Chelinospora timanica (Naumova) Loboziak and Streel, Cymbosporites catillus Allen, Geminospora lemurata Balme, Grandispora mammillata Owens, G. stolidotus (Balme) Breuer and Steemans and Leiotriletes balapucensis di Pasquo, suggest an age that span the late Eifelian and early Givetian for the upper part of the borehole. The rarefaction values indicate that species richness is higher in the younger samples than in the older ones, while the biodiversity indices calculated, such as Simpson and Shannon-Wiener, show a slight decline towards the top of the well, presumably as a result of the increment of abundance of a few dominant species.