Hostname: page-component-586b7cd67f-t7fkt Total loading time: 0 Render date: 2024-11-24T08:02:34.174Z Has data issue: false hasContentIssue false
  • English
  • Français

Organic block coatings in block-and-ash flow deposits at Merapi Volcano, central Java

Published online by Cambridge University Press:  17 September 2008

E. DONOGHUE ,
V. R. TROLL ,
L. M. SCHWARZKOPF ,
G. CLAYTON  and
R. GOODHUE
E. DONOGHUE*
Affiliation:
Department of Geology, University of Dublin, Trinity College, Dublin 2, Ireland
V. R. TROLL
Affiliation:
Department of Geology, University of Dublin, Trinity College, Dublin 2, Ireland
L. M. SCHWARZKOPF
Affiliation:
GeoDocCon, Unterpferdt 8, 95176, Konradsreuth, Germany
G. CLAYTON
Affiliation:
Department of Geology, University of Dublin, Trinity College, Dublin 2, Ireland
R. GOODHUE
Affiliation:
Department of Geology, University of Dublin, Trinity College, Dublin 2, Ireland
*
†Author for correspondence: [email protected]
Get access Rights & Permissions [Opens in a new window]

Abstract

The 1954, 1994, 1998 and 2006 block-and-ash flow deposits from Merapi volcano, Indonesia, contain andesite blocks that display localized, dark surface coatings. These coated blocks are typically found in clusters, but may also occur isolated within the block-and-ash flow deposits. The coatings form irregular patches (tens of centimetres across) on block surfaces, and are characterized by a silver, metallic appearance. The origin and composition of the coatings have not previously been determined, and no comparable deposits have been described in detail from any other volcanically active region of the world. Carbon isotope analyses of coated and uncoated bulk rock material, and of a range of charred and uncharred wood samples, suggest that the dark block coatings at Merapi volcano are organic in origin. Scanning electron microscopy and reflected light microscopy indicate that such coatings may form due to the migration and subsequent deposition of organic carbon in cavities within the andesite blocks. The most recent field evidence from the 2006 block-and-ash flow deposits at Merapi indicates that in situ charcoalification of plant material after block deposition and/or during the final stages of flow, is the major mechanism that forms localized concentrations of block coatings. Isolated coated blocks may result either from recycling of older deposits, or, more likely, from charcoalification and redistribution of plant material caught between colliding lava blocks during flow.

Keywords

coatingandesitecharcoalblock-and-ash flowMerapi volcano
Type
Original Article
Information
Geological Magazine , Volume 146 , Issue 1 , January 2009 , pp. 113 - 120
Copyright
Copyright © Cambridge University Press 2008

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Footnotes

‡

Present address: Department of Earth Sciences, Uppsala University, Villavägen 16, SE-752 36 Uppsala, Sweden

References

Allard, P. 1983. The origin of hydrogen, carbon, sulphur, nitrogen and rare gases in volcanic exhalations, evidence from isotope geochemistry. In Forcasting Volcanic Events (eds Tazieff, H. & Sabroux, J.), pp. 337–86. New York: Elsevier.Google Scholar
Camus, G., Gourgaud, A., Mossand-Berthommier, P. C. & Vincent, P. M. 2000. Merapi (Central Java, Indonesia): An outline of the structural and magmatological evolution, with a special emphasis to the major pyroclastic events. Journal of Volcanology and Geothermal Research 100, 139–63.CrossRefGoogle Scholar
Cas, R. A. F. & Wright, J. V. 1987. Volcanic successions, modern and ancient. London: Allen and Unwin, 111 pp.CrossRefGoogle Scholar
Freundt, A., Wilson, C. J. N. & Carey, S. N. 2000. Ignimbrites and block-and-ash flow deposits. In Encyclopedia of Volcanoes (eds Sigurdsson, H. et al. .), pp. 817–34. California: Academic Press.Google Scholar
Gertisser, R. & Keller, J. 2003 a. Temporal variations in magma composition at Merapi Volcano (Central Java, Indonesia): magmatic cycles during the past 2000 years of explosive activity. Journal of Volcanology and Geothermal Research 123, 1–23.CrossRefGoogle Scholar
Gertisser, R. & Keller, J. 2003 b. Trace element and Sr, Nd, Pb and O isotope variations in medium-K and high-K volcanic rocks from Merapi volcano, Central Java, Indonesia: Evidence for the involvement of subducted sediments in Sunda arc magma genesis. Journal of Petrology 44, 457–89.CrossRefGoogle Scholar
Grunewald, U., Sparks, R. S. J., Kearns, S. & Komorowski, J. C. 2000. Friction marks on blocks from pyroclastic flows at the Soufriere Hills volcano, Montserrat: Implications for flow mechanisms. Geology 28, 827–30.2.0.CO;2>CrossRefGoogle Scholar
Holloway, J. R. & Blank, J. G. 1994. Application of experimental results to C–O–H species in natural melts. In Volatiles in Magmas (eds Carroll, M. R. & Halloway, J. R.), pp. 187–230. Reviews in Mineralogy no. 30.Google Scholar
Hoefs, J. 2004. Stable Isotope Geochemistry (5th ed.). Berlin: Springer-Verlag, pp. 44–9.CrossRefGoogle Scholar
Newhall, C. G., Bronto, S., Alloway, B., Banks, N. G., Bahar, I., del Marmol, M. A., Hadisantono, R. D., Holcomb, R. T., McGeehin, J., Miksic, J. N., Rubin, M., Sayudi, S. D., Sukhyar, R., Andreastuti, S., Tilling, R. I., Torley, R., Trimble, D. & Wirakusumah, A. D. 2000. 10,000 Years of explosive eruptions of Merapi Volcano, Central Java: archaeological and modern implications. Journal of Volcanology and Geothermal Research 100, 9–50.CrossRefGoogle Scholar
Rollinson, H. 1993. Using Geochemical Data: evaluation, presentation, interpretation. Singapore: Longman.Google Scholar
Schmincke, H.-U. 2005. Volcanism. Berlin: Springer-Verlag, 323 pp.Google Scholar
Schwarzkopf, L. M., Schmincke, H.-U. & Troll, V. R. 2001. Pseudotachylite on impact marks of block surfaces in block-and-ash flows at Merapi volcano, Central Java, Indonesia. International Journal of Earth Sciences 90, 769–75.Google Scholar
Schwarzkopf, L. M., Schmincke, H.-U. & Troll, V. R. 2002. Friction marks on blocks from pyroclastic flows at the Soufrière Hills volcano, Montserrat: Implications for flow mechanisms: Comment. Geology 30, 190.2.0.CO;2>CrossRefGoogle Scholar
Schwarzkopf, L. M., Schmincke, H.-U. & Cronin, S. J. 2005. A conceptual model for block-and-ash flow basal avalanche transport and deposition, based on deposit architecture of 1998 and 1994 Merapi flows. Journal of Volcanology and Geothermal Research 139, 117–34.CrossRefGoogle Scholar
Scott, A. C. & Glasspool, I. J. 2007. Observations and experiments on the origin and formation of inertinite group macerals. International Journal of Coal Geology 70, 53–66.CrossRefGoogle Scholar
Scott, A. C. & Glasspool, I. J. 2005. Charcoal reflectance as a proxy for the emplacement temperatures of pyroclastic flow deposits. Geology 33, 589–92.CrossRefGoogle Scholar
Scott, A. C., Cripps, J. A., Collinson, M. E. & Nichols, G. J. 2000. The taphonomy of charcoal following a recent heathland fire and some implications for the interpretation of fossil charcoal deposits. Palaeogeography Palaeoclimatology Palaeoecology 164, 1–31.CrossRefGoogle Scholar
Scott, A. C. & Jones, T. P. 1991. Fossil Charcoal: a plant-fossil record preserved by fire. Geology Today 7, 214–16.CrossRefGoogle Scholar
Scott, A. C. 1989. Observations on the nature and origin of fusain. International Journal of Coal Geology 12, 443–75.CrossRefGoogle Scholar
Sparks, R. S. J., Barclay, J., Calder, E. S., Herd, R. A., Komorowski, J.-C., Luckett, R., Norton, G. E., Ritchie, L. J., Voight, B. & Woods, A. W. 2001. Generation of a debris avalanche and violent pyroclastic density current on 26 December (Boxing Day) 1997 at Soufrière Hills Volcano, Montserrat. In The Eruption of the Soufrière Hills Volcano, Montserrat, from 1995 to 1999 (eds Druitt, T. H. & Kokelaar, B. P.), pp. 409–34. Geological Society of London, Memoir no. 21.Google Scholar
Taylor, G. H., Teichmuller, M., Davis, A., Diessel, C. F. K., Littke, R. & Robert, P. 1998. Organic Petrology. Berlin-Stuttgart: Gebruder Bornträger.Google Scholar
van Bemmelen, R. W. 1949. The Geology of Indonesia. Vol. 1A: General Geology. The Hague: Government Printing Office, 732 pp.Google Scholar
Voight, B., Constantine, E. K., Siswowidjoyo, S. & Torley, R. 2000. Historical eruptions of Merapi Volcano, Central Java, Indonesia, 1768–1998. Journal of Volcanology and Geothermal Research 100, 69–138.CrossRefGoogle Scholar
Supplementary material: Image

Donoghue Supplementary Material

Colour Fig2.jpg

Download Donoghue Supplementary Material(Image)
Image 1.1 MB
Supplementary material: Image

Donoghue Supplementary Material

Colour Fig3.jpg

Download Donoghue Supplementary Material(Image)
Image 1.4 MB