Facies analysis of a higly cyclic sedimentary unit: the Late Hauterivian to Early Barremian Agua de la Mula Member of the Agrio Formation, Neuquén Basin, Argentina
Archuby FM, Fürsich F (2010)
Publication Language: English
Publication Type: Journal article
Publication year: 2010
Journal
Book Volume: 41
Pages Range: 77-127
Abstract
is article contains the facies analysis of the highly cyclic Upper Hauterivian to Lower Barremian Agua de
la Mula Member of the Agrio Formation (Neuquén Basin, Argentina). e study was developed to test the hypothesis
that the occurrence of particular facies can be predicted every time the sequence stratigraphic model can be applied.
e multi-facetted approach based on detailed bed-by-bed collection of sedimentological, stratigraphic, ichnological,
taphonomic, and palaeoecological data led a precise palaeoenvironmental interpretation within a controlled bio- and
sequence-stratigraphic framework.
e facies and facies associations are based mainly on lithological aspects. ree main groups of facies and facies as-
sociations are distinguished: (a) siliciclastic, (b) mixed, and (c) carbonate. e rst group comprises facies and facies
associations linked to regressive phases of short sequences (so-called dilution hemi-sequences) and is characterised by
deposition of terrigenous siliciclastic material, while the second and third group include rocks varying widely in terms
of composition that share a condensed nature (so-called starvation hemi-sequences). Together they form starvation/
dilution sequences. Siliciclastic facies dominate over mixed ones. Carbonate facies are the least represented.
e distinct heterogeneity of facies types and successions correlates with both, the observed cyclic patterns and the
upward reduction in siliciclastic input. e starvation/dilution sequences, which shape the cycle pattern, are present
throughout the sections. ey consist of alternations of terrigenous-starved and terrigenous-diluted beds. Features of
starvation/dilution sequences change according to their position within the sections, but there is always a contrast
between the lower starved and the upper diluted hemisequence.
Facies of starvation/dilution sequences are ner- or coarser-grained, following the deepening and shallowing trend,
respectively of major sedimentary sequences. Predictions of facies occurrence can be improved, if the position within
the sedimentary sequence (transgressive systems tract or regressive systems tract) is also considered. In this way, facies
of starvation/dilution sequences corresponding to the early/late transgression and regression as well as to the maxi-
mum ooding zone can be predicted. Superimposed cyclicities of dierent hierarchies alter the resulting patterns.
Most of the Agua de la Mula Member of the study area can be interpreted to represent a siliciclastic open ramp.
Carbonate-rich beds formed as concentrations of invertebrate hard-parts produced during terrigenous starvation in a
siliciclastic system during transgressions rather than by increased carbonate production. e reduced terrigenous input
observed in the last 150 m of the two investigated sections resulted in facies that can be better explained by carbonate
models. However, even in this setting siliciclastic facies are well represented during major regressions.
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How to cite
APA:
Archuby, F.M., & Fürsich, F. (2010). Facies analysis of a higly cyclic sedimentary unit: the Late Hauterivian to Early Barremian Agua de la Mula Member of the Agrio Formation, Neuquén Basin, Argentina. Beringeria, 41, 77-127.
MLA:
Archuby, Fernando Miguel, and Franz Fürsich. "Facies analysis of a higly cyclic sedimentary unit: the Late Hauterivian to Early Barremian Agua de la Mula Member of the Agrio Formation, Neuquén Basin, Argentina." Beringeria 41 (2010): 77-127.
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