Paleoflow directions of a subaqueous lahar deposit around the Miocene Keserus Hill lava dome complex (North Hungary) as constrained by photo-statistics and anisotropy of magnetic susceptibility (AMS)

T. Biró, D. Karátson, E. Márton, S. Józsa, B. Bradák

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2 Citations (Scopus)

Abstract

A twofold fabric analysis by using photo-statistics on rock surfaces and low-field anisotropy of magnetic susceptibility (AMS) is presented, making it possible to infer paleoflow directions, which in turn helps to constrain the primary volcanic geomorphology of a deeply eroded mid-Miocene field (Keserus Hill lava dome group, Visegrád Mountains, North Hungary). The analyses were carried out on the Rám Hill Pumiceous Sandstone (RHPS) that, based on its petrographic features, is considered as a subaqueously emplaced laharic deposit.The observed anisotropic frequencies of clast a-axis azimuths, the good agreement of fabric directions obtained for all and most elongated samples (elongation. > 2.5), the good clustering of the declinations of the K1 susceptibilities largely corresponding with the result of image analysis, allow to infer reliable flow directions. The obtained large-scale paleoflow paths show a quasi-radial pattern around the central part of the Visegrád Mountains, which quantitatively confirms the previous hypothesis on the volcanic structure, namely a central edifice-topped syn-eruptive topography.The RHPS is characterized by a clast fabric (revealed by photostatistics on cutted rock surfaces considering the lapilli-sized fraction) as strong as in subaerial PDC deposits, but by a significantly weaker magnetic fabric. The weak magnetic fabric is supposed to be the result of rock heterogeneity, thus the weakening effect of abundant lithic clasts with strong internal magnetic susceptibility anisotropy, different from the shape anisotropy of the clasts and the flow-related magnetic fabric of the fine-grained matrix.

Original languageEnglish
Pages (from-to)141-149
Number of pages9
JournalJournal of Volcanology and Geothermal Research
Volume302
DOIs
Publication statusPublished - Sep 1 2015

Fingerprint

lahar
Hungary
lava dome
magnetic anisotropy
Domes
lava
domes
Magnetic susceptibility
clast
magnetic fabric
Anisotropy
Deposits
deposits
Miocene
Statistics
statistics
magnetic permeability
anisotropy
Rocks
sandstone

Keywords

  • Anisotropy of magnetic susceptibility
  • Carpathian-Pannonian region
  • Fabric analysis
  • Photo-statistics
  • Subaqueous lahar deposit

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics

Cite this

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title = "Paleoflow directions of a subaqueous lahar deposit around the Miocene Keserus Hill lava dome complex (North Hungary) as constrained by photo-statistics and anisotropy of magnetic susceptibility (AMS)",
abstract = "A twofold fabric analysis by using photo-statistics on rock surfaces and low-field anisotropy of magnetic susceptibility (AMS) is presented, making it possible to infer paleoflow directions, which in turn helps to constrain the primary volcanic geomorphology of a deeply eroded mid-Miocene field (Keserus Hill lava dome group, Visegr{\'a}d Mountains, North Hungary). The analyses were carried out on the R{\'a}m Hill Pumiceous Sandstone (RHPS) that, based on its petrographic features, is considered as a subaqueously emplaced laharic deposit.The observed anisotropic frequencies of clast a-axis azimuths, the good agreement of fabric directions obtained for all and most elongated samples (elongation. > 2.5), the good clustering of the declinations of the K1 susceptibilities largely corresponding with the result of image analysis, allow to infer reliable flow directions. The obtained large-scale paleoflow paths show a quasi-radial pattern around the central part of the Visegr{\'a}d Mountains, which quantitatively confirms the previous hypothesis on the volcanic structure, namely a central edifice-topped syn-eruptive topography.The RHPS is characterized by a clast fabric (revealed by photostatistics on cutted rock surfaces considering the lapilli-sized fraction) as strong as in subaerial PDC deposits, but by a significantly weaker magnetic fabric. The weak magnetic fabric is supposed to be the result of rock heterogeneity, thus the weakening effect of abundant lithic clasts with strong internal magnetic susceptibility anisotropy, different from the shape anisotropy of the clasts and the flow-related magnetic fabric of the fine-grained matrix.",
keywords = "Anisotropy of magnetic susceptibility, Carpathian-Pannonian region, Fabric analysis, Photo-statistics, Subaqueous lahar deposit",
author = "T. Bir{\'o} and D. Kar{\'a}tson and E. M{\'a}rton and S. J{\'o}zsa and B. Brad{\'a}k",
year = "2015",
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TY - JOUR

T1 - Paleoflow directions of a subaqueous lahar deposit around the Miocene Keserus Hill lava dome complex (North Hungary) as constrained by photo-statistics and anisotropy of magnetic susceptibility (AMS)

AU - Biró, T.

AU - Karátson, D.

AU - Márton, E.

AU - Józsa, S.

AU - Bradák, B.

PY - 2015/9/1

Y1 - 2015/9/1

N2 - A twofold fabric analysis by using photo-statistics on rock surfaces and low-field anisotropy of magnetic susceptibility (AMS) is presented, making it possible to infer paleoflow directions, which in turn helps to constrain the primary volcanic geomorphology of a deeply eroded mid-Miocene field (Keserus Hill lava dome group, Visegrád Mountains, North Hungary). The analyses were carried out on the Rám Hill Pumiceous Sandstone (RHPS) that, based on its petrographic features, is considered as a subaqueously emplaced laharic deposit.The observed anisotropic frequencies of clast a-axis azimuths, the good agreement of fabric directions obtained for all and most elongated samples (elongation. > 2.5), the good clustering of the declinations of the K1 susceptibilities largely corresponding with the result of image analysis, allow to infer reliable flow directions. The obtained large-scale paleoflow paths show a quasi-radial pattern around the central part of the Visegrád Mountains, which quantitatively confirms the previous hypothesis on the volcanic structure, namely a central edifice-topped syn-eruptive topography.The RHPS is characterized by a clast fabric (revealed by photostatistics on cutted rock surfaces considering the lapilli-sized fraction) as strong as in subaerial PDC deposits, but by a significantly weaker magnetic fabric. The weak magnetic fabric is supposed to be the result of rock heterogeneity, thus the weakening effect of abundant lithic clasts with strong internal magnetic susceptibility anisotropy, different from the shape anisotropy of the clasts and the flow-related magnetic fabric of the fine-grained matrix.

AB - A twofold fabric analysis by using photo-statistics on rock surfaces and low-field anisotropy of magnetic susceptibility (AMS) is presented, making it possible to infer paleoflow directions, which in turn helps to constrain the primary volcanic geomorphology of a deeply eroded mid-Miocene field (Keserus Hill lava dome group, Visegrád Mountains, North Hungary). The analyses were carried out on the Rám Hill Pumiceous Sandstone (RHPS) that, based on its petrographic features, is considered as a subaqueously emplaced laharic deposit.The observed anisotropic frequencies of clast a-axis azimuths, the good agreement of fabric directions obtained for all and most elongated samples (elongation. > 2.5), the good clustering of the declinations of the K1 susceptibilities largely corresponding with the result of image analysis, allow to infer reliable flow directions. The obtained large-scale paleoflow paths show a quasi-radial pattern around the central part of the Visegrád Mountains, which quantitatively confirms the previous hypothesis on the volcanic structure, namely a central edifice-topped syn-eruptive topography.The RHPS is characterized by a clast fabric (revealed by photostatistics on cutted rock surfaces considering the lapilli-sized fraction) as strong as in subaerial PDC deposits, but by a significantly weaker magnetic fabric. The weak magnetic fabric is supposed to be the result of rock heterogeneity, thus the weakening effect of abundant lithic clasts with strong internal magnetic susceptibility anisotropy, different from the shape anisotropy of the clasts and the flow-related magnetic fabric of the fine-grained matrix.

KW - Anisotropy of magnetic susceptibility

KW - Carpathian-Pannonian region

KW - Fabric analysis

KW - Photo-statistics

KW - Subaqueous lahar deposit

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U2 - 10.1016/j.jvolgeores.2015.06.020

DO - 10.1016/j.jvolgeores.2015.06.020

M3 - Article

VL - 302

SP - 141

EP - 149

JO - Journal of Volcanology and Geothermal Research

JF - Journal of Volcanology and Geothermal Research

SN - 0377-0273

ER -