Toarcian–Aalenian (Early–Middle Jurassic) radiolarian fauna from the Los Molles Formation, Neuquén Basin, Argentina: Taxonomy and paleobiogeographic affinities

Kochhann, Karlos Guilherme Diemer; Baecker-Fauth, Simone; Pujana, Ignacio; Silveira, Ariane Santos da; Fauth, Gerson

doi:10.1016/j.jsames.2011.01.001

Cited by 3 publications

(3 citation statements)

References 26 publications

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“…Naipauer et al ., 2012; Pujols et al ., 2018). This could be the case in slightly younger sandy depocentres such as La Jardinera (latest Toarcian, Paim et al ., 2008; Kochhann et al ., 2011; Steel et al ., 2023) (Fig. 2), where increased sand supply is associated with a major eustatic sea‐level fall along the southern Neuquén Basin margin at the Toarcian–Aalenian boundary (Paim et al ., 2008).…”

Section: Resultsmentioning

confidence: 99%

Evolving fill‐and‐spill patterns across linked early post‐rift depocentres control lobe characteristics: Los Molles Formation, Argentina

Privat,

Peakall,

Hodgson

et al. 2024

Sedimentology

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Inherited rift topography controls the sediment routing, timing of sand supply, and sedimentary linkage of early post‐rift depocentres. Exhumed examples of early post‐rift turbidite systems are rare and previous studies have examined the evolution of individual depocentres; in contrast, the detailed evolution of early post‐rift turbidite systems across multiple depocentres has never been documented. Current fill‐and‐spill models do not detail the stratigraphic architecture and evolution of sedimentological characteristics of multiple intraslope fans developed across topography, including bed type distributions. Here, the evolution of three intraslope fans that developed across two early post‐rift depocentres is documented along an 18 km long transect in the southern Neuquén Basin, Argentina. The relative chronology of sand supply in depocentres is constrained with new U–Pb ages, and sediment source areas with provenance analysis. The early post‐rift intraslope fans record progradation of the system and progressive sedimentary linkage of post‐rift depocentres, transverse to local syn‐rift structures, with sediment routing subparallel to the cratonic basin margin. The large‐scale stratigraphic architecture of intraslope fans indicates an evolution as a fill‐and‐spill system, with initial confinement through flow stripping and overspill to spillover with erosion and bypass across a transverse topographic high separating the depocentres. Changes in early post‐rift intraslope fan characteristics, including thickness, sandstone content, lobe complex stacking patterns, stratal termination patterns and bed type distribution, record changing confinement through time within a depocentre, and spatially across depocentres. The strong spatial and vertical stratigraphic variability of transitional flow deposits and hybrid event beds reflects enhanced erosion, sediment bypass and flow transformation across transverse relief between the two depocentres during the spillover phase. These findings advance current understanding of early post‐rift turbidite systems and refine fill‐and‐spill models, which will help the prediction of spatial and vertical changes in rock quality and connectivity in subsurface hydrocarbon reservoirs and CO2 storage sites.

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Section: Resultsmentioning

confidence: 99%

Evolving fill‐and‐spill patterns across linked early post‐rift depocentres control lobe characteristics: Los Molles Formation, Argentina

Privat,

Peakall,

Hodgson

et al. 2024

Sedimentology

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“…(A) Location map of the Neuquén Basin in South America, indicating the main localities and the studied area of La Jardinera. (B) Stratigraphic chart of southern Neuquén Basin (from Olariu et al ., ; after Vergani et al ., ; Riccardi et al ., 2000; Paim et al ., ; Kochhann et al ., ). (C) West–east seismic cross‐section along southern Neuquén Basin followed by interpretation.…”

Section: Geological Backgroundmentioning

confidence: 97%

“…One studied cross‐section is ca 5 km long, nearly depositional‐strike oriented (see palaeocurrent map, Fig. A) and contains the Don Cordero shelf‐edge delta deposits dated to Aalenian or earliest Bajocian (Kochhann et al ., ). The second cross‐section, adjacent to the first but slightly older, is ca 4 km long, nearly depositional‐dip oriented and contains the conglomeratic Bey Malec shelf‐edge delta deposits that can be seen to form long downslope (clinoformal) coarse‐grained ‘timelines’ that penetrate far down into the deepwater slope of the Los Molles Formation.…”

Section: Studied Outcrops: Arroyo La Jardinera Areamentioning

confidence: 97%

River‐dominated and tide‐influenced shelf‐edge delta systems: Coarse‐grained deltas straddling the Early–Middle Jurassic shelf–slope break and transforming downslope, Lajas–Los Molles formations, Neuquén Basin, Argentina

et al. 2020

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The three‐dimensional facies and architecture variability of shelf‐edge deltaic units cropping out at the transition between the Lower–Middle Jurassic Lajas and Los Molles formations of southern Neuquén Basin, Argentina, is presented here, as well as their stratigraphic relationship to uppermost deep‐water slope channel systems. Deep‐water, slope mudstones with thin turbidite beds merge upward with prodelta mudstones and thin sandstones, which are truncated by delta‐front to mouth‐bar sandstones. The latter sandstones are then downcut by large‐scale, trough cross‐stratified coarse‐grained sandstones and conglomerates of distributary channel systems and along‐strike, amalgamated with cross‐bedded sandy units showing evidence of tidal reworking. Proximal–distal facies and architecture variability within a shelf‐edge deltaic succession demonstrates that distributary channel‐complexes become wider and deeper basinward, forming channelized river‐dominated distributary fairways separated by tidally reworked inter‐distributary sand belts at the shelf edge. Evidence from depositional‐dip oriented outcrops shows a lack of collapsed and slumped strata at the shelf edge, and that the coarse shelf‐edge distributary channel fills continue far down the deepwater slope, and conglomerates transform to become high‐density turbidites to mainly thick‐bedded, sand‐matrix‐supported debrites. The interplay between flood tides and river currents is interpreted to have primarily modulated the focusing of river drainages, and consequently coarse‐grained sediment transport, along preferential routes on the outer‐shelf to shelf‐edge and down onto the slope. This contribution documents a unique example of coarse‐grained (mostly conglomeratic) shelf‐edge delta systems, tying bed‐scale facies and architecture data to a seismic‐scale shelf‐margin morphology, thus providing outcrop analogue data for the characterization of shelf‐edge delta systems in the subsurface.

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Evolutionary patterns and palaeobiogeography of Pliensbachian and Toarcian (Early Jurassic) Radiolaria

Goričan¹,

Carter

Guex

et al. 2013

Palaeogeography, Palaeoclimatology, Palaeoecology

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Toarcian–Aalenian (Early–Middle Jurassic) radiolarian fauna from the Los Molles Formation, Neuquén Basin, Argentina: Taxonomy and paleobiogeographic affinities

Cited by 3 publications

References 26 publications

Evolving fill‐and‐spill patterns across linked early post‐rift depocentres control lobe characteristics: Los Molles Formation, Argentina

Evolving fill‐and‐spill patterns across linked early post‐rift depocentres control lobe characteristics: Los Molles Formation, Argentina

River‐dominated and tide‐influenced shelf‐edge delta systems: Coarse‐grained deltas straddling the Early–Middle Jurassic shelf–slope break and transforming downslope, Lajas–Los Molles formations, Neuquén Basin, Argentina

Evolutionary patterns and palaeobiogeography of Pliensbachian and Toarcian (Early Jurassic) Radiolaria

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