Elucidating stratovolcano construction from volcaniclastic mass‐flow deposits: The medial ring‐plain of Taranaki Volcano, New Zealand

Sedimentology ◽  
2021 ◽  
Author(s):  
Aliz Zemeny ◽  
Jonathan Procter ◽  
Karoly Nemeth ◽  
Georg F. Zellmer ◽  
Anke V. Zernack ◽  
...  
Keyword(s):  
New Zealand ◽  
Mass Flow ◽  
Mass Flow Deposits

Pleistocene mass-flow deposits of basaltic hyaloclastite on a shallow submarine shelf, South Iceland

1991 ◽  
Vol 53 (8) ◽  
pp. 597-611 ◽  
Author(s):  
Steffen G Bergh ◽  
Gudmundur E Sigvaldason
Keyword(s):  
Mass Flow ◽  
Mass Flow Deposits

Depositional Environments of Plant Bearing Sediments

1988 ◽  
Vol 3 ◽  
pp. 1-13 ◽  
Author(s):  
Scott L. Wing
Keyword(s):  
Mass Flow ◽  
Depositional Environments ◽  
Fluvial Systems ◽  
Volcanic Origin ◽  
Sedimentary Environments ◽  
Plant Remains ◽  
Mass Flow Deposits ◽  
Fluvial Environments

Plants can become incorporated into the sediments of virtually any environment, from the oozes of abyssal plains to the silts and sands of delta fronts to brecciated mudflows of volcanic origin. However there is a much narrower range of sedimentary environments in which identifiable plant remains are found in abundance. Generally speaking these are the very shallow or subaerial portions of deltas and estuaries, the channels and floodplains of fluvial systems, lakes of all sizes, ash-falls, and mass-flow deposits such as mudflows. For the purposes of this paper peat swamps are considered as unusual subtypes of deltaic and fluvial environments in which clastic input is low relative to organic accumulation.

scholarly journals Middle and Late Jurassic radiolarians from the Neotethys suture in the Eastern Alps

2016 ◽  
Vol 91 (1) ◽  
pp. 25-72 ◽  
Author(s):  
Luis O’Dogherty ◽  
Špela Goričan ◽  
Hans-Jürgen Gawlick
Keyword(s):  
Mass Flow ◽  
Late Jurassic ◽  
Eastern Alps ◽  
Accretionary Wedge ◽  
Taxonomic Study ◽  
New Genera ◽  
Two New Species ◽  
Mass Flow Deposits ◽  
Thermal Overprint ◽  
Radiolarian Assemblages

AbstractCherty limestones, marls and radiolarites are widespread in the Hallstatt Mélange of the Northern Calcareous Alps. The mélange was formed during the Neotethyan orogeny in a series of deep-water basins that progressively developed in front of the advancing nappe front. The low thermal overprint of these rocks favors the good preservation of radiolarians (polycystines) that have been used for dating and reconstructing the Jurassic tectonostratigraphy of the area. This paper describes rich Middle–Late Jurassic radiolarian faunas from four localities in the Hallstatt Mélange near Bad Mitterndorf in Austria. Two different successions, both spanning from the Bathonian to the Oxfordian, are dated. In the first succession, the radiolarites are intercalated between or occur as matrix in mass-flow deposits originating from the accretionary wedge. The second succession is nearly 100 m thick but is devoid of mass-flow deposits and documents a continuous radiolarite deposition in greater distance from the nappe stack. Both successions are ascribed to the Sandlingalm Basin, which evolved on a relatively distal continental margin during early stages of the orogeny.The highly diverse and well-preserved radiolarian assemblages have been used for a detailed taxonomic study. Two new families are described: Minocapsidaen. fam. andXitomitridaen. fam.; six new genera are describedDoliocapsan. gen.,Crococapsan. gen.,Parvimitrellan. gen.,Xitomitran. gen.,Campanomitran. gen., andMizukidellan. gen. In addition, one new replacement name,Takemuraella(proTriversus), is introduced, the diagnoses of 6 genera are emended, and two new species are described:Hemicryptocapsa nonagintan. sp. andMizukidella mokaensisn. sp.

scholarly journals Stratigraphy, facies architecture and emplacement history of the c. 3.6 ka B.P. Ngatoro Formation on the eastern flanks of Egmont Volcano, western North Island, New Zealand

2021 ◽  
Author(s):  
◽  
Benjamin John Dixon
Keyword(s):  
New Zealand ◽  
Debris Flow ◽  
Mass Flow ◽  
Extended Phase ◽  
Facies Architecture ◽  
Eruptive Event ◽  
Central Java ◽  
Flow Deposit ◽  
History Of ◽  
Mass Flows

<p>The Ngatoro Formation is an extensive volcaniclastic deposit distributed on the eastern lower flanks of Egmont Volcano, central North Island, New Zealand. Formally identified by Neall (1979) this deposit was initially attributed to an Egmont sourced water-supported mass flow event c. 3, 600 ¹⁴C years B.P. The Ngatoro Formation was subsequently described by Alloway (1989) as a single debris flow deposit closely associated with the deposition of the underlying Inglewood Tephra (c. 3,600 ¹⁴C yrs B.P) that had laterally transformed into a hyperconcentrated- to- flood flow deposit. Such water-supported mass flows have been well documented on volcanoes both within New Zealand (i.e. Mt Ruapehu) and elsewhere around the world (i.e. Mt Merapi, Central Java and Mt St Helens, Washington). This thesis comprises field mapping, stratigraphic descriptions, field and laboratory grain size and shape analysis, tephrochronology and palaeomagnetic analysis with the aim of refining the stratigraphy, facies architecture and emplacement history of the c. 3,600 ¹⁴C yrs B.P. Ngatoro Formation.  This study has found that the Ngatoro Formation has a highly variable and complex emplacement history as evidenced by the rapid textural changes with increasing distance from the modern day Egmont summit. The Ngatoro Formation comprises two closely spaced mass flow events whose flow and emplacement characteristics have undergone both proximal to distal and axial to marginal transformations. On surfaces adjacent to the Manganui Valley on the deeply incised flanks of Egmont Volcano, the Ngatoro Formation is identified as overbank surge deposits whereas at the boundary of Egmont National Park it occurs as massive, pebble- to boulder-rich debris flow deposits. At intermediate to distal distances (17-23 km from the modern Egmont summit) the Ngatoro Formation occurs as a sequence of multiple coalescing dominantly sandy textured hyperconcentrated flow deposits. The lateral and longitudinal textural variability in the Ngatoro Formation reflects downstream transformation from gas-supported block-and-ash flows to water-supported debris flows, then subsequently to turbulent pebbly-sand dominated hyperconcentrated flows.  Palaeomagnetic temperature estimates for the Ngatoro Formation at two sites (Vickers and Surrey Road Quarries, c. 10 km from the present day Egmont summit) indicate clast incorporation temperatures of c. 300°C and emplacement temperatures of c. 200°C. The elevated emplacement temperatures supported by the Ngatoro Formation’s coarse textured, monolithologic componentry suggest non-cohesive emplacement of block-and-ash flow debris generated by the sequential gravitational collapse of an effusive lava dome after the paroxysmal Inglewood eruptive event (c. 3,600 ¹⁴C yrs B.P.). The occurrence of a prominent intervening paleosol between these two events suggest that they are not part of the same eruptive phase but rather, the latter is a product of a previously unrecognised extended phase of the Inglewood eruptive event. This study recognises the potential for gravitational dome collapse, the generation of block-and-ash flows and their lateral transformation to water-support mass flows (debris, hyperconcentrated and stream flows) occurring in years to decades following from the main eruptive phase. This insight has implications with respect to the evaluation of post-eruptive hazards and risk.</p>

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