Geodynamic context for the deposition of coarse‐grained deep‐water axial channel systems in the <scp>P</scp>atagonian <scp>A</scp>ndes

Ghiglione, Matías C.; Likerman, Jeremías; Barberón, Vanesa; Giambiagi, Laura; Aguirre–Urreta, Beatriz; Suárez, Fabián

doi:10.1111/bre.12061

Cited by 59 publications

(86 citation statements)

References 71 publications

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“…Combined with the abundance of felsic volcanic clasts associated with the Lago Sofia conglomerate, the influx of Late Jurassic zircon suggests exhumation of the Tobifera and El Quemado rift volcanics during deposition of the Cerro Toro channel system (Romans et al ., ). This interpretation has also been corroborated by structural studies suggesting uplift/thrusting of the basement and internal domains of the thrust belt, which included the Tobífera and El Quemado formations (Fosdick et al ., ; Ghiglione et al ., ).…”

Section: Discussionmentioning

confidence: 98%

Down‐slope facies variability within deep‐water channel systems: Insights from the Upper Cretaceous Cerro Toro Formation, southern Patagonia

et al. 2018

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In southern Patagonia, outcrops of the Upper Cretaceous Cerro Toro Formation preserve a >150 km long deep‐water axial channel belt in the Magallanes–Austral Basin, providing a unique opportunity to investigate longitudinal variations in the depositional characteristics of a deep‐water channel system. This study documents sedimentological, stratigraphical and geochronological data from the Cerro Toro Formation in the Argentine sector of the basin. New results are integrated with previous work from the Chilean basin sector to conduct a basin‐scale comparison of the timing of deposition, provenance and lithofacies proportions. The Cerro Toro channel belt includes a nearly 1000 m thick section characterized by high‐density turbidites and mass‐wasting deposits. Two ash beds from the base of the section yield U–Pb zircon ages of 90·4 ± 2 Ma and 88·0 ± 3 Ma, indicating similar initiation ages as documented in the Chilean sector. The U–Pb detrital zircon age spectra from samples in the study area reveal similar provenance trends to samples from the Chilean basin sector, with peak age populations at 310 to 260 Ma, 160 to 135 Ma and 110 to 82 Ma. The maximum depositional age of the channel belt in the Argentine sector is 87·8 ± 1·5 Ma and all new geochronology data corroborate an 86 to 80 Ma depositional age for the main Cerro Toro channel belt. Statistical analyses of 7370 beds from nearly 8000 m of new and previously published stratigraphic sections along the entire outcrop belt suggest progressive variations in the down‐system proportion of lithofacies. In the up‐slope region, lithofacies representing mass wasting processes (for example, debris‐flow and mass‐transport deposits) account for ca 29% of the stratigraphic thickness, as opposed to 5% in the down‐slope region of the channel belt, where turbidity current deposits are more prevalent. The proportion of beds >1 m thick also decreases systematically down slope, particularly for conglomeratic turbidite deposits. This work highlights that: (i) the proportion of thick beds and distribution of lithofacies are key down‐system changes in the stratigraphic fill of this deep‐water channel belt; (ii) detrital zircon trends suggest a relatively well‐mixed longitudinal depositional system; and (iii) geochronology of the main Cerro Toro outcrop belt supports but does not necessitate the model of a single, roughly age‐equivalent, channel system. This study has implications for understanding the downslope variability in depositional processes, stratigraphic architecture and reservoir quality of submarine channel systems.

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Section: Discussionmentioning

confidence: 98%

Down‐slope facies variability within deep‐water channel systems: Insights from the Upper Cretaceous Cerro Toro Formation, southern Patagonia

et al. 2018

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“…The development of foreland basins on previously attenuated lithosphere introduces numerous geologic attributes that must be considered in flexural models of foreland deflection. These include lateral variation or segmentation in flexural strength [e.g., Stockmal et al ., ; Desegaulx et al ., ; Bayona et al ., ] and unusually dense topographic loads [e.g., Ghiglione et al ., ]. In our EFM‐3 model, which includes effects of both lithospheric thinning and sediment loading, the impact of contrasting Te across the foreland is most pronounced in the distal parts of the basin and on the forebulge geometry (Figure ).…”

Section: Discussionmentioning

confidence: 99%

Influence of attenuated lithosphere and sediment loading on flexure of the deep-water Magallanes retroarc foreland basin, Southern Andes

2014

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Flexural subsidence in foreland basins is controlled by applied loads-such as topography, water/sediment, and subcrustal forces-and the mechanical properties of the lithosphere. We investigate the controls on subsidence observed within the Upper Cretaceous Magallanes retroarc foreland basin of southern South America to evaluate the impact of lateral variations in flexural rigidity due to Late Jurassic extension. Conventional elastic models cannot explain the observed basin deflection and thick accumulation of deep-water Cenomanian-Turonian basin strata. However, models in which the lithosphere has been previously thinned and deflects under topographic and sedimentary loads successfully reproduce regional subsidence patterns. Results satisfy paleobathymetric observations in the Magallanes Basin and suggest that lithospheric thinning is necessary to produce both long-wavelength and deep subsidence during Late Cretaceous basin evolution. Results indicate that elastic thickness decreases westward from~45-25 km in the distal foreland to~37-15 km beneath the foredeep. These findings are consistent with a westward reduction in crustal thickness associated with the Jurassic extensional history of the Patagonian lithosphere. Our results also show that sediment loading exerts an important control on regional deflection patterns and promotes a wider region of subsidence and reduced forebulge uplift. We propose that lateral variations in mechanical properties and large sediment loads restrict depocenter migration and may cause the foredeep to remain fixed for prolonged periods of time. These findings confirm that loading of thinned lithosphere imposes different mechanical controls on the flexural profile and have potential implications for other retroarc foreland basins characterized by earlier extensional histories.

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“…After 70 Ma, Cordillera Darwin experienced rapid exhumation, peaking between 60 and 40 Ma [ Barbeau et al , ; Gombosi et al , ; Klepeis et al , ; Maloney et al , ]. This period coincides with the advance of the thrust and fold belt into the Magallanes foreland [ Klepeis et al , ], which ended in Tierra del Fuego during Oligo‐Miocene times [ Alvarez‐Marrón et al , ; Ghiglione et al, ; Torres‐Carbonell et al , , ].…”

Section: Discussionmentioning

confidence: 99%

The curved Magallanes fold and thrust belt: Tectonic insights from a paleomagnetic and anisotropy of magnetic susceptibility study

et al. 2014

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The Magallanes fold and thrust belt (FTB) presents a large-scale curvature from N-S oriented structures north of 52°S to nearly E-W in Tierra del Fuego Island. We present a paleomagnetic and anisotropy of magnetic susceptibility (AMS) study from 85 sites sampled in Cretaceous to Miocene marine sediments. Magnetic susceptibility is lower than 0.0005 SI for 76 sites and mainly controlled by paramagnetic minerals. AMS results indicate that the sedimentary fabric is preserved in the undeformed areas of Tierra del Fuego and the more external thrust sheets units, where an incipient lineation due to layer parallel shortening is recorded. Prolate AMS ellipsoids, indicating a significant tectonic imprint in the AMS fabric, are observed in the internal units of the belt. AMS results show a good correlation between the orientation of the magnetic lineation and the fold axes. However, in Península Brunswick, the AMS lineations are at~20°counterclockwise to the strike of the fold axes. Pretectonic stable characteristic remanent magnetizations (ChRM) were determined in seven sites. A counterclockwise rotation (21.2°± 9.2°) is documented by ChRM data from four sites near the hinge of the belt in Península Brunswick and near Canal Whiteside while there is no evidence of rotation near the nearly E-W oriented Vicuña thrust within Tierra del Fuego. The curved shape of the Cenozoic Magallanes FTB is not related to vertical axis rotation, and thus, the Magallanes FTB can be considered as a primary arc.

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Geodynamic context for the deposition of coarse‐grained deep‐water axial channel systems in the Patagonian Andes

Cited by 59 publications

References 71 publications

Down‐slope facies variability within deep‐water channel systems: Insights from the Upper Cretaceous Cerro Toro Formation, southern Patagonia

Down‐slope facies variability within deep‐water channel systems: Insights from the Upper Cretaceous Cerro Toro Formation, southern Patagonia

Influence of attenuated lithosphere and sediment loading on flexure of the deep-water Magallanes retroarc foreland basin, Southern Andes

The curved Magallanes fold and thrust belt: Tectonic insights from a paleomagnetic and anisotropy of magnetic susceptibility study

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