Bulletin of Volcanology

, 81:65 | Cite as

Generation of block-and-ash flows at the onset of silicic volcanism in the Paraná Magmatic Province (Brazil): evidence from photoanalysis of Caxias do Sul breccias

  • Letícia Freitas GuimarãesEmail author
  • Adrian Hornby
  • Ulrich Kueppers
  • Adriana Alves
  • Valdecir de Assis Janasi
  • Donald Bruce Dingwell
Research Article


In this work, we perform textural analysis on volcanic breccias related to the silicic magmatism in the region of São Marcos (southern Brazil), Paraná Magmatic Province. The breccias are matrix-supported, coarse-grained, poorly sorted with angular to rounded fragments in a fine-grained matrix. Juvenile fragments are dense to pumiceous, massive to banded dacites; lithic fragments were not recognised. The analyses were performed on field photographs. Grain size distribution (GSD) analysis showed maximum fragment sizes between − 8 and − 9.5 ϕ and smallest recognised sizes between − 3 and 1.5 ϕ. Due to the spatial resolution limit of the photographs and the weathered condition of the matrix, the fine fragments from the matrix were not analysed. The GSD fractality could be quantified by a single power law, with low/moderate D values of 1.9–2.3. Vesicle size distribution (VSD) and shape parameters of both fragments and vesicles were also measured. The fragments are typically low vesicularity, with median vesicle area fractions around 5% for all samples, but pumiceous fragments with up to 43% area are found. VSDs exhibit single exponential, concave upwards curves, with vesicles becoming more deformed/complex with increasing size, suggesting a single continuous process of nucleation and growth under low degrees of shear. Regarding the fragments’ shape parameters, all samples have high values of solidity which, together with the low-vesicularity of the fragments, suggest brittle fragmentation of poorly vesicular material and the operation of secondary fragmentation processes during transport that round and smooth the clasts. However, field evidence for local conduit systems together with the GSD fractality suggest that these may be proximal deposits, without substantial transport history. Based on a comparison of the deposits’ characteristics with several types of volcanic breccias, we propose a block and ash flow source for these breccias that indicate the presence of nearby lava domes, providing evidence for high-viscosity low-flux dacitic volcanism in the Paraná Magmatic Province.


Volcanic breccias Block and ash deposits Paraná Magmatic Province Textural analysis Grain size distribution 



We thank N.S. Marteleto and C. DeCampos for helping during fieldwork, and M.D. Higgins, J. Bernard, J. Paredes-Mariño and E.F. Lima for valuable discussions.The authors are thankful to the editors (Dr. Jacopo Taddeucci and Dr. Andrew Harris) and the two anonymous reviewers, whose comments significantly improved the paper.

Funding information

This work was supported by FAPESP (Grant No. 2012/06082-6). LFG was supported by a CNPq PhD fellowship (No. 142084/2015-8) and CAPES PDSE fellowship (No. 88881.134384/2016-01). AH was supported by EU funding through a Marie Curie Individual Fellowship (AVAST No. 753900).

Supplementary material

445_2019_1332_MOESM1_ESM.pdf (193 kb)
ESM 1 (PDF 193 kb)
445_2019_1332_MOESM2_ESM.pdf (212 kb)
ESM 2 (PDF 211 kb)
445_2019_1332_MOESM3_ESM.pdf (301 kb)
ESM 3 (PDF 301 kb)
445_2019_1332_MOESM4_ESM.pdf (221 kb)
ESM 4 (PDF 221 kb)
445_2019_1332_MOESM5_ESM.pdf (1.5 mb)
ESM 5 (PDF 1571 kb)
445_2019_1332_MOESM6_ESM.pdf (1 mb)
ESM 6 (PDF 1031 kb)
445_2019_1332_MOESM7_ESM.pdf (997 kb)
ESM 7 (PDF 996 kb)
445_2019_1332_MOESM8_ESM.pdf (635 kb)
ESM 8 (PDF 635 kb)


  1. Aguirre-Díaz GJ, Labarthe-Hernández G (2003) Fissure ignimbrites: fissure-source origin for voluminous ignimbrites of the Sierra Madre Occidental and its relationship with Basin and Range faulting. Geology 31:773–776. CrossRefGoogle Scholar
  2. Alidibirov M, Dingwell DB (2000) Three fragmentation mechanisms for highly viscous magma under rapid decompression. J Volcanol Geotherm Res 100:413–421. CrossRefGoogle Scholar
  3. Andrews BJ, Manga M (2011) Effects of topography on pyroclastic density current runout and formation of coignimbrites. Geology 39:1099–1102. CrossRefGoogle Scholar
  4. Angelini PG (2018) Petrological and volcanological insights into acid lavas from the Paraná-Etendeka Magmatic Province on the surroundings of Guarapuava city, Paraná, Southern Brazil: a contribution of detailed textural characterization combined with in situ Sr isotopes in. Universidade de São PauloGoogle Scholar
  5. Baksi AK (2018) Paraná flood basalt volcanism primarily limited to ~ 1 Myr beginning at 135 Ma: new 40Ar/39Ar ages for rocks from Rio Grande do Sul, and critical evaluation of published radiometric data. J Volcanol Geotherm Res 355:66–77. CrossRefGoogle Scholar
  6. Bellieni G, Comin-Chiaramonti P, Marques LS et al (1984) High- and Low-TiO2 flood basalts from the Parana plateau (Brazil): petrology and geochemical aspects bearing on their mantle origin. Neus Jahrb Miner Abh 150:273–306Google Scholar
  7. Bellieni G, Comin-chiaramonti P, Marques LS et al (1986) Petrogenetic aspects of acid and basaltic lavas from the paraná plateau (Brazil): geological, mineralogical and petrochemical relationships. J Petrol 27:915–944. CrossRefGoogle Scholar
  8. Blott SJ, Pye K (2008) Particle shape: a review and new methods of characterization and classification. Sedimentology 55:31–63. CrossRefGoogle Scholar
  9. Bryan SE, Ferrari L (2013) Large igneous provinces and silicic large igneous provinces: progress in our understanding over the last 25 years. Geol Soc Am Bull 125:1053–1078CrossRefGoogle Scholar
  10. Bryan SE, Peate IU, Peate DW et al (2010) The largest volcanic eruptions on Earth. Earth-Science Rev 102:207–229. CrossRefGoogle Scholar
  11. Caballero L, Sarocchi D, Borselli L, Cárdenas AI (2012) Particle interaction inside debris flows: evidence through experimental data and quantitative clast shape analysis. J Volcanol Geotherm Res 231–232:12–23. CrossRefGoogle Scholar
  12. Calder ES, Lavallée Y, Kendrick JE, Bernstein M (2015) Lava dome eruptions. In: Encyclopedia of Volcanoes, 2nd edn, pp 343–362CrossRefGoogle Scholar
  13. Cañón-Tapia E, Raposo MIB (2018) Anisotropy of magnetic susceptibility of silicic rocks from quarries in the vicinity of São Marcos, Rio Grande do Sul, South Brazil: Implications for emplacement mechanisms. J Volcanol Geotherm Res 355:165–180. CrossRefGoogle Scholar
  14. Carrasco-Núñez G (1999) Holocene block-and-ash flows from summit dome activity of Citlaltepetl volcano, Eastern Mexico. J Volcanol Geotherm Res 88:47–66. CrossRefGoogle Scholar
  15. Cashman KV, Scheu B (2015) Magmatic fragmentation, 2nd edn, Elsevier IncGoogle Scholar
  16. Cassidy M, Manga M, Cashman K, Bachmann O (2018) Controls on explosive-effusive volcanic eruption styles. Nat Commun 9:1–16. CrossRefGoogle Scholar
  17. Chang F, Chen C-J, Lu C-J (2004) A linear-time component-labeling algorithm using contour tracing technique. Comput Vis Image Underst 93:206–220. CrossRefGoogle Scholar
  18. Fatemi M, Amini A, Baboulaz L, Vetterli M (2016) Shapes from Pixels. IEEE Trans Image Process 25:1193–1206. CrossRefGoogle Scholar
  19. Fink JH, Griffiths RW (1998) Morphology, eruption rates, and rheology of lava domes: Insights from laboratory models. J Geophys Res 103:527. CrossRefGoogle Scholar
  20. Fisher R (1960) Classification of volcanic breccias. Bull Geol Soc Am 71:973–962CrossRefGoogle Scholar
  21. Florisbal LM, Heaman LM, Janasi VA, Bitencourt MF (2014) Tectonic significance of the Florianópolis Dyke Swarm, Paraná-Etendeka Magmatic Province: a reappraisal based on precise U-Pb dating. J Volcanol Geotherm Res 289:140–150. CrossRefGoogle Scholar
  22. Frank HT, Gomes MEB, Formoso MLL (2009) Review of the areal extent and the volume of the Serra Geral Formation, paraná Basin, South America. Pesqui em Geociencias 36:49–57CrossRefGoogle Scholar
  23. Freeman H (1961) On the encoding of arbitrary geometric configurations. IRE Trans Electron Comput EC-10:260–268. CrossRefGoogle Scholar
  24. Freundt A, Schmincke HU (1992) Abrasion in pyroclastic flows. Geol Rundschau 81:383–389. CrossRefGoogle Scholar
  25. Garland F, Hawkesworth CJ, Mantovani MSM (1995) Description and petrogenesis of the Paraná Rhyolites, Southern Brazil. J Petrol 36:1193–1227CrossRefGoogle Scholar
  26. Gonnermann HM (2015) Magma fragmentation. Annu Rev Earth Planet Sci 43:431–458. CrossRefGoogle Scholar
  27. Guimarães LF (2014) Características físicas e químicas e modelo eruptivo para os riolitos tipo Santa Maria ( Província Magmática Paraná ) na região de Gramado Xavier , RS. Universidade de São PauloGoogle Scholar
  28. Guimarães LF, De Campos CP, Janasi VA et al (2018a) Flow and fragmentation patterns in the silicic feeder system and related deposits in the Paraná-Etendeka Magmatic Province, São Marcos, South Brazil. J Volcanol Geotherm Res. CrossRefGoogle Scholar
  29. Guimarães LF, Raposo MIB, Janasi VA et al (2018b) An AMS study of different silicic units from the southern Paraná-Etendeka Magmatic Province in Brazil: implications for the identification of flow directions and local sources. J Volcanol Geotherm Res 355:304–318. CrossRefGoogle Scholar
  30. Korvin G (1992) Fractal models in the earth sciences. Elsevier, Amsterdam, p 408Google Scholar
  31. Heilbronner R, Barrett S (2014) Shape descriptors. In: Image analysis in Earth sciences: microstructures and textures of Earth materials. Springer, Berlin Heidelberg, pp 1–520CrossRefGoogle Scholar
  32. Hentschel ML, Page NW (2003) Selection of descriptors for particle shape characterization. Part Part Syst Charact 20:25–38. CrossRefGoogle Scholar
  33. Higgins MD (2000) Measurement of crystal size distributions. Am Mineral 85:1105–1116. CrossRefGoogle Scholar
  34. Hornby AJ (2018) IPC shape macro (Version 1.0.2.). Zenodo.
  35. Hornby A, Lavallée Y, Kendrick JE et al (2019a) Brittle-ductile deformation and tensile rupture of dome lava during inflation at Santiaguito, Guatemala. J Geophys Res Solid Earth 2018JB017253.
  36. Hornby AJ, Lavallée Y, Kendrick JE, Rollinson G, Butcher AR, Clesham S, Kueppers U, Cimarelli C, Chigna G (2019b) Phase partitioning during fragmentation revealed by QEMSCAN Particle Mineralogical Analysis of volcanic ash. Sci Rep 9:126. CrossRefGoogle Scholar
  37. Ichihara M (2002) Fragmentation of a porous viscoelastic material: implications to magma fragmentation. J Geophys Res 107:1–14. CrossRefGoogle Scholar
  38. Janasi VA, Freitas VA, Heaman LH (2011) The onset of flood basalt volcanism, Northern Paraná Basin, Brazil: a precise U-Pb baddeleyite/zircon age for a Chapecó-type dacite. Earth Planet Sci Lett 302:147–153. CrossRefGoogle Scholar
  39. Jaupart C, Allegre CJ (1991) Gas content, eruption rate and instabilities of eruption regime in silicic volcanoes. Earth Planet Sci Lett 102:413–429. CrossRefGoogle Scholar
  40. Jones TJ, Russell JK (2017) Ash production by attrition in volcanic conduits and plumes. Sci Rep 7:5538. CrossRefGoogle Scholar
  41. Jones TJ, McNamara K, Eychenne J et al (2016) Primary and secondary fragmentation of crystal-bearing intermediate magma. J Volcanol Geotherm Res 327:70–83. CrossRefGoogle Scholar
  42. Kaminski E, Jaupart C (1998) The size distribution of pyroclasts and the fragmentation sequence in explosive volcanic eruptions. J Geophys Res 103:29759–29779. CrossRefGoogle Scholar
  43. Kirkpatrick JD, Rowe CD (2013) Disappearing ink: how pseudotachylytes are lost from the rock record. J Struct Geol 52:183–198. CrossRefGoogle Scholar
  44. Kueppers U, Perugini D, Dingwell DB (2006) “Explosive energy” during volcanic eruptions from fractal analysis of pyroclasts. Earth Planet Sci Lett 248:800–807. CrossRefGoogle Scholar
  45. Kueppers U, Putz C, Spieler O, Dingwell DB (2012) Abrasion in pyroclastic density currents: I-insights from tumbling experiments. Phys Chem Earth, Parts A/B/C 45–46:33–39. CrossRefGoogle Scholar
  46. Lima EF, Philipp RP, Rizzon GC, Waichel BL, Rossetti LMM (2012) Sucessões vulcânicas, modelo de alimentação e geração de domos de lava ácidos da Formação Serra Geral na região de São Marcos-Antônio Prado (RS). Geologia USP. Série Científica 12(2):49–64Google Scholar
  47. Lima EF, Waichel BL, Rossetti LMM et al (2018) Feeder systems of acidic lava flows from the Paraná-Etendeka Igneous Province in southern Brazil and their implications for eruption style. J South Am Earth Sci 81:1–9. CrossRefGoogle Scholar
  48. Liu EJ, Cashman KV, Rust AC (2015) Optimising shape analysis to quantify volcanic ash morphology. GeoResJ 8:14–30. CrossRefGoogle Scholar
  49. Liu EJ, Cashman KV, Rust AC, Höskuldsson A (2017) Contrasting mechanisms of magma fragmentation during coeval magmatic and hydromagmatic activity: the Hverfjall Fires fissure eruption, Iceland. Bull Volcanol 79:68–26. CrossRefGoogle Scholar
  50. Llewellin EW, Manga M (2005) Bubble suspension rheology and implications for conduit flow. J Volcanol Geotherm Res 143:205–217. CrossRefGoogle Scholar
  51. Luchetti ACF, Gravley DM, Gualda GAR, Nardy AJR (2018a) Textural evidence for high-grade ignimbrites formed by low-explosivity eruptions, Paraná Magmatic Province, southern Brazil. J Volcanol Geotherm Res 355:87–97. CrossRefGoogle Scholar
  52. Luchetti ACF, Nardy AJR, Madeira J (2018b) Silicic, high- to extremely high-grade ignimbrites and associated deposits from the Paraná Magmatic Province, southern Brazil. J Volcanol Geotherm Res 355:270–286. CrossRefGoogle Scholar
  53. Mandelbrot B (1967) How long is the coast of Britain? Statistical self-similarity and fractional dimension. Science (80- ) 156:636–638. CrossRefGoogle Scholar
  54. Mangan M, Sisson T (2000) Delayed, disequilibrium degassing in rhyolite magma: decompression experiments and implications for explosive volcanism. Earth Planet Sci Lett 183:441–455. CrossRefGoogle Scholar
  55. Mann S, Picard RW (1995) Being “undigital” with digital cameras: extending dynamic range by combining differently exposed pictures. Proc IS&T Annu Conf:442–448Google Scholar
  56. Mantovani MSM, Marques LS, De Sousa MA et al (1985) Trace element and strontium isotope constraints on the origin and evolution of Paraná Continental Flood Basalts of Santa Catarina State (Southern Brazil). J Petrol 26:187–209. CrossRefGoogle Scholar
  57. Maria A, Carey S (2007) Quantitative discrimination of magma fragmentation and pyroclastic transport processes using the fractal spectrum technique. J Volcanol Geotherm Res 161:234–246. CrossRefGoogle Scholar
  58. Marsh JS, Ewart A, Milner SC et al (2001) The Etendeka Igneous Province: magma types and their stratigraphic distribution with implications for the evolution of the Paraná-Etendeka flood basalt province. Bull Volcanol 62:464–486. CrossRefGoogle Scholar
  59. Melnik O, Sparks RSJ, Costa A, Barmin AA (2011) Volcanic eruptions: cyclicity during lava dome growth. In: Meyers RA (ed) Extreme environmental events. Springer New York, New York, pp 1035–1081CrossRefGoogle Scholar
  60. Milner SC, Ewart A (1989) The geology of the Goboboseb Mountain volcanics and their relationship to the Messum Complex , Namibia. Commun Geol Surv Namib 5:33–42Google Scholar
  61. Milner SC, Duncan AR, Ewart A (1992) Quartz latite rheoignimbrite flows of the Etendeka Formation, north-western Namibia. Bull Volcanol 54:200–219. CrossRefGoogle Scholar
  62. Milner SC, Duncan AR, Whittingham AM, Ewart A (1995) Trans-Atlantic correlation of eruptive sequences and individual silicic volcanic units within the Paraná-Etendeka igneous province. J Volcanol Geotherm Res 69:137–157. CrossRefGoogle Scholar
  63. Mueller S, Scheu B, Spieler O, Dingwell DB (2008) Permeability control on magma fragmentation. Geology 36:399–402. CrossRefGoogle Scholar
  64. Nardy AJR, Machado FB, Oliveira MAF (2008) As rochas vulcânicas mesozóicas ácidas da Bacia do Paraná: litoestratigrafia e considerações geoquímico-estratigráficas. Brazilian J Geol 38:178–195Google Scholar
  65. Nardy AJR, Rosa MC, Luchetti ACF et al (2011) Parâmetros físicos pré-eruptivos do magmatismo ácido da província magmática do Paraná: Resultados preliminares. Geociencias 30:575–588Google Scholar
  66. Nurfiani D, Bouvet de Maisonneuve C, Nur D, De Maisonneuve CB (2018) Furthering the investigation of eruption styles through quantitative shape analyses of volcanic ash particles. J Volcanol Geotherm Res 354:102–114. CrossRefGoogle Scholar
  67. Paredes-Mariño J, Morgavi D, Di Vito M et al (2017) Syneruptive sequential fragmentation of pyroclasts from fractal modeling of grain size distributions of fall deposits: the Cretaio Tephra eruption (Ischia Island, Italy). J Volcanol Geotherm Res 345:161–171. CrossRefGoogle Scholar
  68. Parsons WH (1969) Criteria for the recognition of volcanic breccias: review. Geol Soc Am Mem 115:263–304. CrossRefGoogle Scholar
  69. Peate DW (1997) The Paraná-Etendeka Province. In: Mahoney JJ, Coffin (eds) Large igneous provinces: continental, oceanic and planetary flood volcanism vol. 100. Geophysical Monography Series, pp, 217–245CrossRefGoogle Scholar
  70. Peate DW, Hawkesworth CJ, Mantovani MSM, Shukowsky W (1990) Mantle plumes and flood-basalt stratigraphy in the Paraná, South America. Geology 18:1223–1226.<1223:MPAFBS>2.3.CO;2 CrossRefGoogle Scholar
  71. Peate DW, Hawkesworth CJ, Mantovani MSM (1992) Chemical stratigraphy of the Paraná lavas (South America): classification of magma types and their spatial distribution. Bull Volcanol 55:119–139CrossRefGoogle Scholar
  72. Pepe S, Solaro G, Ricciardi GP, Tizzani P (2008) On the fractal dimension of the fallout deposits: a case study of the 79 A.D. Plinian eruption at Mt. Vesuvius. J Volcanol Geotherm Res 177:288–299. CrossRefGoogle Scholar
  73. Perugini D, Kueppers U (2012) Fractal analysis of experimentally generated pyroclasts: a tool for volcanic hazard assessment. Acta Geophys 60:682–698. CrossRefGoogle Scholar
  74. Perugini D, Speziali A, Caricchi L, Kueppers U (2011) Application of fractal fragmentation theory to natural pyroclastic deposits: insights into volcanic explosivity of the Valentano scoria cone (Italy). J Volcanol Geotherm Res 202:200–210. CrossRefGoogle Scholar
  75. Pinto VM, Hartmann LA, Santos JOS et al (2011) Zircon U-Pb geochronology from the Paraná bimodal volcanic province support a brief eruptive cycle at ~135Ma. Chem Geol 281:93–102. CrossRefGoogle Scholar
  76. Polacci M, Pioli L, Rosi M (2003) The Plinian phase of the Campanian Ignimbrite eruption (phlegrean fields, Italy): evidence from density measurements and textural characterization of pumice. Bull Volcanol 65:418–432. CrossRefGoogle Scholar
  77. Polo LA, Janasi VA (2014) Volcanic stratigraphy of intermediate to acidic rocks in the southern Paraná Magmatic Province, Brazil. Geol USP - Ser Cient 14:83–100. CrossRefGoogle Scholar
  78. Polo LA, Giordano D, Janasi VA, Guimarães LF (2018a) Effusive silicic volcanism in the Paraná Magmatic Province, South Brazil: physico-chemical conditions of storage and eruption and considerations on the rheological behavior during emplacement. J Volcanol Geotherm Res 355:115–135. CrossRefGoogle Scholar
  79. Polo LA, Janasi VA, Giordano D et al (2018b) Effusive silicic volcanism in the Paraná Magmatic Province, South Brazil: evidence for locally-fed lava flows and domes from detailed field work. J Volcanol Geotherm Res 355:204–218. CrossRefGoogle Scholar
  80. Proffitt D, Rosen D (1979) Metrication errors and coding efficiency of chain-encoding schemes for the representation of lines and edges. Comput Graph Image Process 10:318–332. CrossRefGoogle Scholar
  81. Rhodes E, Kennedy BM, Lavallée Y et al (2018) Textural insights into the evolving lava dome cycles at Santiaguito Lava Dome, Guatemala. Front Earth Sci 6:30. CrossRefGoogle Scholar
  82. Rocha-Júnior ERV, Puchtel IS, Marques LS et al (2012) Re–Os isotope and highly siderophile element systematics of the Paraná continental flood basalts (Brazil). Earth Planet Sci Lett 337–338:164–173. CrossRefGoogle Scholar
  83. Rocha-Júnior ERV, Marques LS, Babinski M et al (2013) Sr–Nd–Pb isotopic constraints on the nature of the mantle sources involved in the genesis of the high-Ti tholeiites from northern Paraná Continental Flood Basalts (Brazil). J South Am Earth Sci 46:9–25. CrossRefGoogle Scholar
  84. Rossetti LMM, Lima EF, Waichel BL et al (2018) Lithostratigraphy and volcanology of the Serra Geral Group, Paraná-Etendeka Igneous Province in Southern Brazil: towards a formal stratigraphical framework. J Volcanol Geotherm Res 355:98–114. CrossRefGoogle Scholar
  85. Rust ACC, Manga M (2002) Bubble shapes and orientations in low Re simple shear flow. J Colloid Interface Sci 249:476–480. CrossRefGoogle Scholar
  86. Rust AC, Manga M, Cashman KV (2003) Determining flow type, shear rate and shear stress in magmas from bubble shapes and orientations. J Volcanol Geotherm Res 122:111–132. CrossRefGoogle Scholar
  87. Sarocchi D, Sulpizio R, Macías JL, Saucedo R (2011) The 17 July 1999 block-and-ash flow (BAF) at Colima Volcano: new insights on volcanic granular flows from textural analysis. J Volcanol Geotherm Res 204:40–56. CrossRefGoogle Scholar
  88. Sheridan MF, Wohletz KH, Dehn J (1987) Discrimination of grain-size subpopulations in pyroclastic deposits. Geology 15:367CrossRefGoogle Scholar
  89. Simões MS, Lima EF, Sommer CA, Rossetti LMM (2018) Structures and lithofacies of inferred silicic conduits in the Paraná-Etendeka LIP, southernmost Brazil. J Volcanol Geotherm Res. CrossRefGoogle Scholar
  90. Sparks RSJ, Walker GP (1977) Significance of vitric-enriched air-fall ashes associated with crystal-enriched ignimbrites. J Volcanol Geotherm Res 2:329–341. CrossRefGoogle Scholar
  91. Spieler O, Alidibirov M, Dingwell DB (2003) Grain-size characteristics of experimental pyroclasts of 1980 Mount St. Helens cryptodome dacite: effects of pressure drop and temperature. Bull Volcanol 65:90–104. CrossRefGoogle Scholar
  92. Spieler O, Kennedy B, Kueppers U et al (2004) The fragmentation threshold of pyroclastic rocks. Earth Planet Sci Lett 226:139–148. CrossRefGoogle Scholar
  93. Suzuki-Kamata K, Kusano T, Yamasaki K (2009) Fractal analysis of the fracture strength of lava dome material based on the grain size distribution of block-and-ash flow deposits at Unzen Volcano, Japan. Sediment Geol 220:162–168. CrossRefGoogle Scholar
  94. Thiede DS, Vasconcelos PM (2010) Paraná flood basalts: rapid extrusion hypothesis confirmed by new 40Ar/39Ar results. Geology 38:747–750. CrossRefGoogle Scholar
  95. Turcotte DL (1986) Fractals and fragmentation. J Geophys Res 91:1921–1926CrossRefGoogle Scholar
  96. Turcotte DL (1992) Fractals and chaos in geology and geophysics. Cambridge University Press, Cambridge, p 221Google Scholar
  97. Ui T, Matsuwo N, Sumita M, Fujinawa A (1999) Generation of block and ash flows during the 1990-1995 eruption of Unzen Volcano, Japan. J Volcanol Geotherm Res 89:123–137. CrossRefGoogle Scholar
  98. Wadsworth FB, Witcher T, Vossen CEJ, Hess KU, Unwin HE, Scheu B, Castro JM, Dingwell DB (2018) Combined effusive-explosive silicic volcanism straddles the multiphase viscous-to-brittle transition. Nat Commun 9:4696. CrossRefGoogle Scholar
  99. Wagner T, Lipinski H (2013) IJBlob: an ImageJ Library for connected component analysis and shape analysis. J Open Res Softw 1:6–8. doi:
  100. Walker GPL (1985) Origin of coarse lithic breccias near ignimbrite source vents. J Volcanol Geoth Res 25(1–2):157–171CrossRefGoogle Scholar

Copyright information

© International Association of Volcanology & Chemistry of the Earth's Interior 2019

Authors and Affiliations

  • Letícia Freitas Guimarães
    • 1
    Email author
  • Adrian Hornby
    • 2
  • Ulrich Kueppers
    • 2
  • Adriana Alves
    • 1
  • Valdecir de Assis Janasi
    • 1
  • Donald Bruce Dingwell
    • 2
  1. 1.Instituto de GeociênciasUniversidade de São PauloSão PauloBrazil
  2. 2.Dept. für Geo- und UmweltwissenschaftenLudwig-Maximilians Universität MünchenMunichGermany

Personalised recommendations