INVESTIGADORES
CISTERNA Gabriela Adriana
artículos
Título:
Latest Carboniferous-earliest Permian transgressive deposits in the Paganzo Basin of Western Argentina : Lithofacies and sequence stratigraphy of a coastal plain to shallow-marine succession
Autor/es:
DESJARDINS, P., BUATOIS, L.A., LIMARINO, C.O. & CISTERNA, G.A.
Revista:
JOURNAL OF SOUTH AMERICAN EARTH SCIENCES
Editorial:
Elsevier
Referencias:
Año: 2009 vol. 28 p. 40 - 53
ISSN:
0895-9811
Resumen:
The upper Paleozoic rocks of Gondwana record a complex paleoclimatic history related to the migration
of the supercontinent over high latitudes. Changes in climate and relative sea level can be traced through
detailed sedimentologic and sequence-stratigraphic analysis. Our study focuses on transgressive deposits
of Stephanian?Early Permian age in the lower member of the Tupe Formation with the objective of characterizing
lithofacies and sedimentary environments within a sequence-stratigraphic framework in order
to achieve a better understanding of the sedimentary history of the Paganzo Basin and the nature of
transgressive deposits.
Sixteen lithofacies grouped in eight assemblages were defined and arranged in two complete
sequences. A sequence boundary (SB) is identified at the base of the Tupe Formation. Coastal-plain deposits
capped by marine embayment lithofacies are included within sequence 1. A relative sea-level fall (SB)
is recorded by an abrupt change into braided alluvial-plaine deposits (LST). The beginning of the TST is
characterized by the appearance of coal and deltaic lithofacies. Late TST deposits occur above a ravinement
surface and comprise bay-margin to distal-bay deposits forming a retrogradational stacking package.
These lithofacies are replaced upwards by HST deposits. A relative sea-level fall (SB) is recorded by
the presence of fluvial deposits overlying marine lithofacies.
The Tupe Formation illustrates the transition of a coastal-plain to a marine embayment. The detection
of a transgressive surface within the coastal-plain deposits of sequence 1 expanded significantly the volume
of deposits now included as part of the latest Carboniferous?earliest Permian transgression, and
underscores the importance of searching for transgressive signatures in non-marine environments. The
presence of two sequences supports a punctuated shoreline trajectory with an overall retrogradational
stacking pattern. An abrupt relative sea-level fall and increased aridity is recorded at the end of the transgressive
event.