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dc.contributor.author
Schwarz, Ernesto
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dc.contributor.author
Buaotis, L.
dc.contributor.other
Bádenas, Beatriz
dc.contributor.other
Aurell, Marcos
dc.contributor.other
Alonso Zarza, Ana María
dc.date.available
2024-05-28T11:51:08Z
dc.date.issued
2011
dc.identifier.citation
Variations of substrate-controlled ichnofacies along a marine sequence boundary: an example from the Valanginian of central Neuquén Basin (Argentina); 28th IAS Meeting of Sedimentology; Zaragoza; España; 2011; 381-381
dc.identifier.isbn
978-84-615-1755-8
dc.identifier.uri
http://hdl.handle.net/11336/236228
dc.description.abstract
Erosion and/or non-deposition associated with basin-scale stratigraphic discontinuities such as regressive surfaces of marine erosion (RSME) and sequence boundaries (SB) can result in the formation of different substrates including non-cohesive sands, dewatered muds and/or cemented hardgrounds. Thus, any individual discontinuity across a basin could be demarcated by different substrate-controlled trace fossils, but ancient examples supporting this concept have not been widely reported. This contribution discusses a case study from the Intra-Valanginian Unconformity, a discontinuity that represents a dramatic sea-level fall within the Lower Cretaceous strata of the Neuquén Basin (Argentina). This second-order sequence boundary can be mapped for 10’s of kilometers both along depositional strike and dip. In the proximal region of the lowstand configuration, the subaerial segment of the SB is demarcated by alluvial conglomerates (basal Mulichinco Fm) onto deep-marine black shales (Vaca Muerta Fm). In the marine realm, the time-equivalent RSME separates black shales and marls beneath from shallow-marine carbonate deposits above. The downdip expression of the RSME is well-exposed across a 20-km long, strike-oriented outcrop. Everywhere in this region the discontinuity is demarcated by robust Thalassinoides that penetrate up to 25 cm in the underlying succession. These burrows have well-defined walls and spherical to subspherical cross-sections, suggesting that the substrate was relatively firm during excavation. The burrow system is filled mostly with bioclasts of echinoids and bivalves from overlying sediments, but also with pebble-size mudstone intraclasts that were eroded from the underlying succession. This burrow system is interpreted to represent the Glossifungites Ichnofacies. The updip expression of the RSME was recorded in subsurface from a cored hydrocarbon well located about 20 km from the outcrops. As in the distal region, a first generation of passively filled Thalassinoides excavated into a firm substrate is attributed to the Glossifungites Ichnofacies. However, this suite is in turn cross-cut at the top by mm-long borings representing the Trypanites Ichnofacies. The RSME records a complex erosional history after the onset of the Valanginian sea-level fall. The more proximal regions of the marine realm underwent erosion and exhumation of buried sediments in the first place, allowing for the formation of crustacean-colonized firm substrates. As sea level continued falling, these processes extended (or migrated) to distal areas. Meanwhile, long-lived by-pass and/or early marine cementation favored the development of hard grounds in the proximal region (subaerial exposure, although possible, cannot be unambiguously established), producing the co-occurrence of different substrates at this time. Shallow-marine sediments probably deposited during early transgression and backstepped onto the RSME, producing a composite RSME/Transgressive Surface.
dc.format
application/pdf
dc.language.iso
eng
dc.publisher
International Asociation of Sedimentologists
dc.rights
info:eu-repo/semantics/restrictedAccess
dc.rights.uri
https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
dc.subject
Substrate-controlled ichnofacies
dc.subject
Marine sequence boundary
dc.subject
Mulichinco Fm (Valanginian)
dc.subject
Neuquén Basin (Argentina)
dc.subject.classification
Geociencias multidisciplinaria
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dc.subject.classification
Ciencias de la Tierra y relacionadas con el Medio Ambiente
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dc.subject.classification
CIENCIAS NATURALES Y EXACTAS
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dc.title
Variations of substrate-controlled ichnofacies along a marine sequence boundary: an example from the Valanginian of central Neuquén Basin (Argentina)
dc.type
info:eu-repo/semantics/publishedVersion
dc.type
info:eu-repo/semantics/conferenceObject
dc.type
info:ar-repo/semantics/documento de conferencia
dc.date.updated
2024-05-16T14:45:04Z
dc.journal.pagination
381-381
dc.journal.pais
España
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dc.journal.ciudad
Zaragoza
dc.description.fil
Fil: Schwarz, Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Geológicas. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Investigaciones Geológicas; Argentina
dc.description.fil
Fil: Buaotis, L.. University of Saskatchewan; Canadá
dc.relation.alternativeid
info:eu-repo/semantics/altIdentifier/url/https://www.sedimentologists.org/ims
dc.conicet.rol
Autor
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dc.conicet.rol
Autor
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dc.coverage
Internacional
dc.type.subtype
Reunión
dc.description.nombreEvento
28th IAS Meeting of Sedimentology
dc.date.evento
2011-07-05
dc.description.ciudadEvento
Zaragoza
dc.description.paisEvento
España
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dc.type.publicacion
Book
dc.description.institucionOrganizadora
International Association of Sedimentologists
dc.source.libro
Abstracts, 28th IAS Meeting of Sedimentology
dc.date.eventoHasta
2011-07-08
dc.type
Reunión
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