Idioma:

Hyperpycnal (over density) flows and deposits

Zavala, Carlos

Journal of palaeogeography, 2020-06, Vol.9 (1), p.1-21, Article 17 [Periódico revisado por pares]

Singapore: Springer Singapore

Texto completo disponível

Citações Citado por

Enviar para

Título:
Hyperpycnal (over density) flows and deposits
Autor: Zavala, Carlos
Assuntos: Alluvial deposits ; Alluvial fans ; Aquatic reptiles ; Basins ; Clay ; Coastal zone ; Density ; Deposits ; Duration ; Earth and Environmental Science ; Earth Sciences ; Flow duration ; Fluid dynamics ; Fluvial deposits ; Freshwater ; Geochemistry ; Grain size ; Gravitation ; Gravitational collapse ; Gravity ; Gravity flow ; Historical Geography ; Hyperpycnal flows ; Hyperpycnites ; Inland water environment ; Landslides ; Lithofacies palaeogeogrphy and sedimentology ; Lofting ; Mineral Resources ; Organic matter ; Original Article ; Paleontology ; Rheological properties ; Rheology ; Rivers ; Sediment ; Sediment gravity flows ; Sedimentary structures ; Sedimentology ; Sediments ; Subcritical flow ; Supercritical flow ; Travel ; Turbidites ; Turbidity ; Underflow ; Volcanic eruptions ; Water discharge ; Water reservoirs
É parte de: Journal of palaeogeography, 2020-06, Vol.9 (1), p.1-21, Article 17
Descrição: A hyperpycnal flow forms when a relatively dense land-derived gravity flow enters into a marine or lacustrine water reservoir. As a consequence of its excess of density, the incoming flow plunges in coastal areas, generating a highly dynamic and often long-lived dense underflow. Depending on the characteristics of the parent flow (flow duration and flow rheology) and basin salinity, the resulting deposits (hyperpycnites) can be very variable. According to flow duration, land-derived gravity flows can be classified into short-lived or long-lived flows. Short-lived gravity flows last for minutes or hours, and are mostly related to small mountainous river discharges, alluvial fans, collapse of natural dams, landslides, volcanic eruptions, jökulhlaups, etc. Long-lived gravity flows last for days, weeks or even months, and are mostly associated with medium- to large-size river discharges. Concerning the rheology of the incoming flow, hyperpycnal flows can be initiated by non-Newtonian (cohesive debris flows), Newtonian supercritical (lahars, hyperconcentrated flows, and concentrated flows) or Newtonian subcritical flows (pebbly, sandy or muddy sediment-laden turbulent flows). Once plunged, non-Newtonian and Newtonian supercritical flows require steep slopes to accelerate, allow the incorporation of ambient water and develop flow transformations in order to evolve into a turbidity current and travel further basinward. Their resulting deposits are difficult to differentiate from those related to intrabasinal turbidites. On the contrary, long-lived Newtonian subcritical flows are capable of transferring huge volumes of sediment, freshwater and organic matter far from the coast even along gentle or flat slopes. In marine settings, the buoyant effect of interstitial freshwater in pebbly and sandy hyperpycnal flows can result in lofting due to flow density reversal. Since the excess of density in muddy hyperpycnal flows is provided by silt-clay sediments in turbulent suspension, lofting is not possible even in marine/saline basins. Muddy hyperpycnal flows can also erode the basin bottom during their travel basinward, allowing the incorporation and transfer of intrabasinal sediments and organic matter. Long-lived hyperpycnal flow deposits exhibit typical characteristics that allow a clear differentiation respect to those related to intrabasinal turbidites. Main features include (1) composite beds with gradual and recurrent changes in sediment grain-size and sedimentary structures, (2) mixture of extrabasinal and intrabasinal components, (3) internal and discontinuous erosional surfaces, and (4) lofting rhythmites in marine/saline basins.
Editor: Singapore: Springer Singapore
Idioma: Inglês

Voltar para lista de resultados

Realização: Logos de Redes Sociais:

Hyperpycnal (over density) flows and deposits

Zavala, Carlos

Singapore: Springer Singapore

Buscando em bases de dados remotas. Favor aguardar.