INVESTIGADORES
OLIVERO Eduardo Bernardo
artículos
Título:
Eocene graphoglyptids from shallow marine, high-energy, organic-rich, and bioturbated turbidites, Fuegian Andes, Argentina
Autor/es:
OLIVERO, E.B.,; LÓPEZ C., MARÍA I.; MALUMIÁN, N.; PABLO TORRES CARBONELL
Revista:
ACTA GEOLOGICA POLONICA
Editorial:
WYDAWNICTWO NAUKOWE INVIT
Referencias:
Año: 2010 vol. 60 p. 77 - 91
ISSN:
0001-5709
Resumen:
Graphoglyptids are diagnostic ichnofossils of the Paleodictyon ichnosubfacies (Nereites ichnofacies), which is well
represented in deep-marineMesozoicCenozoic thin-bedded turbidites. However, unusual shallow-water records of
MesozoicCenozoic Paleodictyon and particular preservational restrictions of graphoglyptid burrows introduce the
question of whether graphoglyptids are reliable bathymetric indicators.We document and discuss another unusual
graphoglyptid association preserved in shallow-marine, high-energy, organic-rich, and bioturbated turbidites of leveed
channels in the upper middle Eocene CCa member, Cerro Colorado Formation, Fuegian Andes. The member
includes the facies associations: 1) mudstones, 2) interbedded mudstones and thin-bedded Tbc turbidites, and 3)
thick-bedded sandstones andmudstones. Facies association 3), interpreted as channel deposits, records at least three
horizonswithDesmograpton,Glockerichnus,Helicolithus,Helminthorhaphe,Megagrapton, Paleodictyon andUrohelminthoida.
Associated beds are lenticular, channeled sandstone turbidites withmarked basal erosion surfaces and
variable proportions of interbeddedmudstone-sandstone with high content of plant debris. Trace fossils in the channeled
sandstones are dominated by Ophiomorpha rudis and O. annulata; mudstones within the thick-bedded mudstone-
sandstone beds bear Nereites, Phycosiphon, Zoophycos and Paradictyodora, with subordinate Schaubcylindrichnus,
Tasselia and Scolicia. The unusual preservation of limited graphoglyptid-bearing bedswithin a highly
energetic and bioturbated interval seems to support the concept that preservational restrictions on graphoglyptid
burrows could be locally more important than bathymetric constraints.Paleodictyon ichnosubfacies (Nereites ichnofacies), which is well
represented in deep-marineMesozoicCenozoic thin-bedded turbidites. However, unusual shallow-water records of
MesozoicCenozoic Paleodictyon and particular preservational restrictions of graphoglyptid burrows introduce the
question of whether graphoglyptids are reliable bathymetric indicators.We document and discuss another unusual
graphoglyptid association preserved in shallow-marine, high-energy, organic-rich, and bioturbated turbidites of leveed
channels in the upper middle Eocene CCa member, Cerro Colorado Formation, Fuegian Andes. The member
includes the facies associations: 1) mudstones, 2) interbedded mudstones and thin-bedded Tbc turbidites, and 3)
thick-bedded sandstones andmudstones. Facies association 3), interpreted as channel deposits, records at least three
horizonswithDesmograpton,Glockerichnus,Helicolithus,Helminthorhaphe,Megagrapton, Paleodictyon andUrohelminthoida.
Associated beds are lenticular, channeled sandstone turbidites withmarked basal erosion surfaces and
variable proportions of interbeddedmudstone-sandstone with high content of plant debris. Trace fossils in the channeled
sandstones are dominated by Ophiomorpha rudis and O. annulata; mudstones within the thick-bedded mudstone-
sandstone beds bear Nereites, Phycosiphon, Zoophycos and Paradictyodora, with subordinate Schaubcylindrichnus,
Tasselia and Scolicia. The unusual preservation of limited graphoglyptid-bearing bedswithin a highly
energetic and bioturbated interval seems to support the concept that preservational restrictions on graphoglyptid
burrows could be locally more important than bathymetric constraints.Paleodictyon and particular preservational restrictions of graphoglyptid burrows introduce the
question of whether graphoglyptids are reliable bathymetric indicators.We document and discuss another unusual
graphoglyptid association preserved in shallow-marine, high-energy, organic-rich, and bioturbated turbidites of leveed
channels in the upper middle Eocene CCa member, Cerro Colorado Formation, Fuegian Andes. The member
includes the facies associations: 1) mudstones, 2) interbedded mudstones and thin-bedded Tbc turbidites, and 3)
thick-bedded sandstones andmudstones. Facies association 3), interpreted as channel deposits, records at least three
horizonswithDesmograpton,Glockerichnus,Helicolithus,Helminthorhaphe,Megagrapton, Paleodictyon andUrohelminthoida.
Associated beds are lenticular, channeled sandstone turbidites withmarked basal erosion surfaces and
variable proportions of interbeddedmudstone-sandstone with high content of plant debris. Trace fossils in the channeled
sandstones are dominated by Ophiomorpha rudis and O. annulata; mudstones within the thick-bedded mudstone-
sandstone beds bear Nereites, Phycosiphon, Zoophycos and Paradictyodora, with subordinate Schaubcylindrichnus,
Tasselia and Scolicia. The unusual preservation of limited graphoglyptid-bearing bedswithin a highly
energetic and bioturbated interval seems to support the concept that preservational restrictions on graphoglyptid
burrows could be locally more important than bathymetric constraints.Desmograpton,Glockerichnus,Helicolithus,Helminthorhaphe,Megagrapton, Paleodictyon andUrohelminthoida.
Associated beds are lenticular, channeled sandstone turbidites withmarked basal erosion surfaces and
variable proportions of interbeddedmudstone-sandstone with high content of plant debris. Trace fossils in the channeled
sandstones are dominated by Ophiomorpha rudis and O. annulata; mudstones within the thick-bedded mudstone-
sandstone beds bear Nereites, Phycosiphon, Zoophycos and Paradictyodora, with subordinate Schaubcylindrichnus,
Tasselia and Scolicia. The unusual preservation of limited graphoglyptid-bearing bedswithin a highly
energetic and bioturbated interval seems to support the concept that preservational restrictions on graphoglyptid
burrows could be locally more important than bathymetric constraints.Ophiomorpha rudis and O. annulata; mudstones within the thick-bedded mudstone-
sandstone beds bear Nereites, Phycosiphon, Zoophycos and Paradictyodora, with subordinate Schaubcylindrichnus,
Tasselia and Scolicia. The unusual preservation of limited graphoglyptid-bearing bedswithin a highly
energetic and bioturbated interval seems to support the concept that preservational restrictions on graphoglyptid
burrows could be locally more important than bathymetric constraints.Nereites, Phycosiphon, Zoophycos and Paradictyodora, with subordinate Schaubcylindrichnus,
Tasselia and Scolicia. The unusual preservation of limited graphoglyptid-bearing bedswithin a highly
energetic and bioturbated interval seems to support the concept that preservational restrictions on graphoglyptid
burrows could be locally more important than bathymetric constraints.and Scolicia. The unusual preservation of limited graphoglyptid-bearing bedswithin a highly
energetic and bioturbated interval seems to support the concept that preservational restrictions on graphoglyptid
burrows could be locally more important than bathymetric constraints.