Cuenca del Noa

XIII Reunión Argentina de Sedimentología, Relatorio | Salta, 2012 | p. 119-132

La cuenca Neoproterozoica-Eocámbrica en el
NOA: sedimentología y ambientes de depósito de
secuencias con icnofósiles, nuevas perspectivas
Vanina López de Azarevich, Florencia G. Aceñolaza,
Guillermo F. Aceñolaza, Ricardo H. Omarini
y Miguel Azarevich

ABSTRACT
In NW Argentina, the Neoproterozoic-Eocambriansequences that include an important ichnofossil record are
filites, shales, quartzites and grauvackesof the Puncoviscana Formations.l., deposited in a shallow marine basin
withtidal flats and foreshore to distal platforms (less than 200 meters-deep). Primary sedimentary structures such as
linguoid, interference and double crested ripples, hummocky cross stratification, flasser and onduliticstratification,
rill marks, exposed surfaces, tidal rhythmites, as well as photic zone related microbial mats and algae activity, confirm
an inter- to sub-tidal deposition influenced by tides, waves and storms. At the moment, no turbidite sequences were
found in the studied localities of Rancagua, Palermo Oeste, Km 13, Bárcena, Purmamarca, Tilcara, Quebrada del
Toro, Muñano, Tastil, San Antonio delos Cobres. They contain Nereites and Oldhamia ichnoassociations that
suggest an Upper Ediacara to Early Cambrian (Terraneuvian - Series 2?) age of deposition. Earliest depositional age
is also confirmed by U/Pb zircon age obtained from magmatic rocks that intrude or interlayered the sedimentary
sequence (563 to 517 Ma).Analyses of astronomic periods obtained from tidal rhythmites allowed toadjust, from
another point of view, the relation between astronomic, sedimentary and biologic processes occurred at global scale
in the temporal range of deposition (Neoproterozoic-Eocambrian). It implies that an important decrement in the
Moon retreat during the Neoproterozoic-Cambrian transition influenced in more stable and lowertides and benign
conditions for the Cambrian Explotion.Geotectonic interpretations of the Puncoviscana basin developed at the
present are based on petrologic, geochemical and geochronological data, but lack of the appropriate sedimentological
context that allow an adjust evaluation the geodynamic configuration from the initial rifting occurred during Rodinia
fragmentation.

INTRODUCCIÓN
La Formación Puncoviscana fue definida por
Turner (1960) en lalocalidad homónima, situada en
el extremo noroeste de la República Argentina. Esta
secuencia constituye el basamento Precámbrico-Cámbrico de la Cordillera Oriental, Argentina, y se extiende desde el límite argentino-boliviano hasta aproximadamente los 27º de latitud sur (Fig. 1). La unidad
litoestratigráfica de referencia está compuesta por sedimentos leptometamórficos, filitas y pizarras,cuarci-

tas y grauvacas de colores verdoso hasta violáceo y
gris, con estructuras sedimentarias primarias y abundantes trazas fósiles.
Salfity et al. (1976) interpretan el basamento del
NOA en el Valle de Lerma, Salta, integrando por 4
unidades que, de base a techo, son:
• Formación Sancha (Ortiz, 1962): turbiditas gris-verdosas, conglomerados y diamictitas.
• Formaciones Las Tienditas, Volcány Tumbaya (Loss
y Giordana, 1952; Ortiz, 1962; Porto et al., 1990):
calizas micríticas y dolomitas negras grisáceas, respec119

López de Azarevich et al.

65°

67°

63°

PAR

B O L I V I A

AG

22°

UA

-

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Cratón Anto
falla

5

24°
?

4

?
2

3

1

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26°
A M E R I C A DEL SUR

?
24°

REFERENCIAS

A

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Granitoides Precámbrico
- CámbricosI

?
O C E A NO

Localidad fosílifera

A T L A N T I CO

A

R

G

E

N

T

P A C I F I CO

26°

Formación Puncoviscana
(sensu Turner, 1960)
Cuenca Punciviscana

N

O C E A NO

Mesoprotero
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(Sa s et a l., 20
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C H I L E...