Submarine Landslide Deposits in Orogenic Belts

Ogata, Kei; Festa, Andrea; Pini, Gian Andrea; Alonso, Juan Luis Alonso

doi:10.1002/9781119500513.ch1

Cited by 16 publications

(31 citation statements)

References 181 publications

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“…7 and 9) it could be better classified as a polygenetic mélange (Festa et al, 2019;. Thus we envisage this thrusting structure as a mixing unit sharing rocks of the LPa and the Autochthon, where the Silurian parts could have been scraped off from the CIZ local uppermost sequence at the orogenic time, a mechanism suggested by Ogata et al (2019), Semeraglia et al (2019 and Hajna et al (2019) for the mélanges formation. This offscraping mechanism is supported in the study area by the Silurian rocks found in the autochthonous unit (CIZ) at the eastern part of the Alcañices Synform (González Clavijo, 2006).…”

Section: Structural and Stratigraphic Meaning Of The Lower Parautochthon Synorogenic Basinsmentioning

confidence: 75%

A tectonic carpet of Variscan flysch at the base of an unrooted accretion prism in NW Iberia: U-Pb zircon age constrains from sediments and volcanic olistoliths

Clavijo

Silva

Catalán

et al. 2020

Preprint

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Abstract. The allochthonous complexes of Galicia – Trás-os-Montes Zone (NW Iberia) are part of the tectonic stack that unrooted the Variscan accretionary prism. They are formed by individual tectonic slices marked by specific tectono-metamorphic evolution, which was piled up in a piggy-back thrust complex onto its relative autochthon, the Central Iberian Zone (CIZ). Consequently, allochthony decreases towards lower, more external and younger thrust sheets. The lowermost unit of this pile of slivers is known as Schistose Domain or Parautochthon and bears low metamorphic grade, contrasting with the higher temperatures and pressures estimated for the upper allochthonous units, but sharing the stratigraphic sequence with the underlying autochthon. The Parautochthon is divided in two structural and stratigraphic sub-units: (i) the Lower (LPa) made of synorogenic flysch-type sediments with varied turbiditic units and olistostrome bodies, showing Upper Devonian-lower Carboniferous age on base of the youngest zircon populations and fossiliferous content; (ii) the Upper (UPa), composed of highly deformed pre-orogenic upper Cambrian-Silurian volcano-sedimentary sequence comparable with both the nearby autochthon and the HP-LT Lower Allochthon, laying structurally above. The UPa thrusted onto the LPa by the the Main-Trás-os-Montes Thrust; and the LPa detached from the CIZ relative autochthon by a regional structure (Basal Lower Parautochthon Detachment) which follows the favourable Silurian carbonaceous beds. A review on the detrital zircon studies of the synorogenic LPa complemented by 17 new samples geochronology is here presented. The results support the extension of the LPa underneath the NW Iberia allochthonous complexes, from Cabo Ortegal, to Bragança and Morais Massifs. Its current exposure follows the lowermost tectonic boundary between the Galicia – Trás-os-Montes (allochthon) and Central Iberian (autochthon) Zones. Youngest zircon age populations point to a maximum sedimentation age for the LPa formations ranging from Famennian to Serpukhovian and endorse the piggy-back evolution inside this unit, mimicking the general structure of the Galicia – Trás-os-Montes Zone. The zircon populations in the LPa allow constraining the sedimentary provenance areas, showing the intervention of nearby sources (mostly the UPa) and/or multiply recycled/long transport sediments with typically N-Central Gondwana age fingerprint, also found in the Lower Allochthon, UPa and Autochthon. Complementary geochronology of volcanic olistoliths trapped in the LPa sediments and of upper Cambrian to Upper Ordovician rhyolites from the UPa is also presented, showing a direct relation between the major block's source area (UPa) and the setting place (LPa). Old zircon age patterns show that the LPa sedimentary rocks were recycled from detrital rocks of the allochthon (advancing wedge) and the nearby autochthon (peripheral bulge).

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Section: Structural and Stratigraphic Meaning Of The Lower Parautochthon Synorogenic Basinsmentioning

confidence: 75%

A tectonic carpet of Variscan flysch at the base of an unrooted accretion prism in NW Iberia: U-Pb zircon age constrains from sediments and volcanic olistoliths

Clavijo

Silva

Catalán

et al. 2020

Preprint

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“…8a, b and 9) it could be considered as a polygenetic mélange (Festa et al, 2019(Festa et al, , 2020. We envisage the SCSSs as a mixing unit sharing rocks of the LPa and the Autochthon, where the Silurian components were scraped off from the CIZ local uppermost sequence during the emplacement, a mechanism suggested by Ogata et al (2019), Smeraglia et al (2019) and Hajna et al (2019) for mélange formation. This offscraping mechanism is supported by the presence of Silurian rocks in the Autochthon (CIZ) at the eastern part of the Alcañices Synform and at the Sil Syncline area (Martínez Catalán et al, 2016).…”

Section: Structural and Stratigraphic Meaning Of The Lower Parautochthon Synorogenic Basinsmentioning

confidence: 83%

A tectonic carpet of Variscan flysch at the base of a rootless accretionary prism in northwestern Iberia: U–Pb zircon age constrains from sediments and volcanic olistoliths

Clavijo

Silva

Catalán³

et al. 2021

Solid Earth

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Abstract. The allochthonous complexes of Galicia–Trás-os-Montes Zone (NW Iberia) are part of a rootless tectonic stack which preserves part of a Variscan accretionary prism. They are formed by individual tectonic slices marked by specific tectonometamorphic evolutions, which were piled up in a piggy-back mode onto its relative autochthon, the Central Iberian Zone (CIZ). Allochthony decreases from the structurally upper thrust sheets towards the lower ones. The lowermost unit of the stack is known as the Parautochthon or Schistose Domain. It is characterized by a low metamorphic grade in contrast with higher temperatures and/or pressures estimated for the overlying allochthonous units and shares the stratigraphic sequence with the underlying autochthon. The Parautochthon is divided in two structural and stratigraphic sub-units: (i) the Lower Parautochthon (LPa) is made of synorogenic flysch-type sediments with varied turbiditic units and olistostrome bodies, showing Upper Devonian–lower Carboniferous age according to the youngest zircon populations and fossiliferous content; (ii) the Upper Parautochthon (UPa) is composed of highly deformed preorogenic upper Cambrian–Silurian volcano-sedimentary sequence comparable with the nearby autochthon and to some extent, also with the high-P and low-T Lower Allochthon laying structurally above. The UPa was emplaced onto the LPa along the Main-Trás-os-Montes Thrust, and the LPa became detached from the CIZ relative autochthon by a regional-scale structure, the Basal Lower Parautochthon Detachment, which follows a weak horizon of Silurian carbonaceous slates. A review on the detrital zircon studies on the synorogenic LPa complemented by zircon dating of 17 new samples is presented here. The results support the extension of the LPa underneath the NW Iberian allochthonous complexes, from Cabo Ortegal, to Bragança and Morais massifs. Its current exposure follows the lowermost tectonic boundary between the Galicia–Trás-os-Montes (allochthon) and Central Iberian (autochthon) zones. The youngest zircon age populations point to a maximum sedimentation age for the LPa formations ranging from Famennian to Serpukhovian and supports the piggy-back mode of emplacement of the Galicia–Trás-os-Montes Zone, of which it represents the latest imbricate. The zircon age populations in the LPa allow the sedimentary provenance areas to be constrained, showing the intervention of nearby sources (mostly the UPa) and/or multiply recycled and long-transport sediments with a typically north-central Gondwana age fingerprint, also found in the Lower Allochthon, UPa and Autochthon. Complementary geochronology of volcanic olistoliths trapped in the LPa sediments and of late Cambrian to Upper Ordovician rhyolites from the UPa is also presented. It shows a direct relationship between the major blocks source area (UPa) and the setting place (LPa). Old zircon age patterns show that the LPa sedimentary rocks were recycled from detrital rocks of the allochthon (advancing wedge) and the nearby autochthon (peripheral bulge).

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“…Some of these situations can be related to the development of structures in different domains of the MTD (extensional, translational, compressional and transcurrent) related to different regions of the flow (at the head, central, frontal or toe and lateral zones, respectively) and radial spreading of the flow (e.g., Alsop and Marco, 2012;Sharman et al, 2015). In addition, MTDs can be laterally confined or unconfined, and frontally confined or emergent (e.g., Frey-Martínez et al, 2006;Ogata et al, 2019). These conditions may result in lateral and vertical strain partitioning within the MTD that can create local variation of flow (Ogata et al, 2019).…”

Section: Do Mtd Structures Show Robustness For Defining Palaeoflows?mentioning

confidence: 99%

“…In addition, fold hinges and axial planes may subsequently rotate toward the transport direction and local backthrusts and folds verging upslope may also exist (e.g., Hansen, 1971;Woodcock, 1979;Farrell and Eaton, 1987;Strachan and Alsop, 2006;Alsop et al, 2017). Further complications may include irregular palaeoslope and seafloor topography, MTD frontal and lateral confinement and transport directions that change through time, together with overprinting relationships between adjacent MTDs, and other factors (e.g., Frey-Martinez et al 2006;Gee et al, 1999;Bull et al, 2009;Alves and Cartwright, 2010;Ogata et al 2019). Disaggregation and mixing of remobilized sediments may obliterate structures generated during earlier stages of the mass flow (Rodrigues et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

Statistical analysis of structures commonly used to determine palaeoslopes from within mass transport deposits

Rodrigues

Trzaskos

Alsop

et al. 2021

Journal of Structural Geology

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Submarine Landslide Deposits in Orogenic Belts

Cited by 16 publications

References 181 publications

A tectonic carpet of Variscan flysch at the base of an unrooted accretion prism in NW Iberia: U-Pb zircon age constrains from sediments and volcanic olistoliths

A tectonic carpet of Variscan flysch at the base of an unrooted accretion prism in NW Iberia: U-Pb zircon age constrains from sediments and volcanic olistoliths

A tectonic carpet of Variscan flysch at the base of a rootless accretionary prism in northwestern Iberia: U–Pb zircon age constrains from sediments and volcanic olistoliths

Statistical analysis of structures commonly used to determine palaeoslopes from within mass transport deposits

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