Geoscience Society of New Zealand Miscellaneous Publication 131A Cerro Chivo Laguna Azul Abstract Volume of the Laguna Potrok Aike Fourth International Maar Conference 3IMC - ARGENTINA A Multidisciplinary Congress on Monogenetic Volcanism Edited by Kate Arentsen, Károly Németh, Elaine Smid Badacsony Tihany Filakovo 2IMC - HUNGARY - SLOVAKIA -GERMANY Pulvermaar Dauner Maare Auckland, New Zealand 20-24 February 2012 Eichholzmaar 1IMC - GERMANY Fourth International Maar Conference a multidisciplinary congress on monogenetic volcanism Auckland, New Zealand 20 – 24 February 2012 ABSTRACTS VOLUME Edited by Kate Arentsen, Károly Németh, Elaine Smid Geoscience Society of New Zealand Miscellaneous Publication 131A ISBN 978-1-877480-15-7 ISSN Online 2230-4495 ISSN Print 2230-4487 Previous IMCs International Maar Conference Daun, Germany, 2000 Second International Maar Conference Lajosmizse, Hungary, 2004 Third International Maar Conference Malargüe, Argentina, 2009 Conference Supporters International Association of Volcanology and Chemistry of the Earth’s Interior International Association of Sedimentologists Geoscience Society of New Zealand The University of Auckland Massey University Institute of Earth Science and Engineering Earthquake Commission Elsevier Springer Villa Maria Estate Epic Beer Organizing Committee Károly Németh and Ian EM Smith (Co-Chairs) Members: Kate Arentsen, Shane Cronin, Jan Lindsay, Janet Simes, Elaine Smid Scientific Advisory Group Georg Buechel, Kathy Cashman, Shane Cronin, Gonca Gençalioğlu Kuşcu, Guido Giordano, Stephan Kurszlaukis, Jan Lindsay, Volker Lorenz, Joan Marti, Károly Németh, Corina Risso, Hetu Sheth, Claus Siebe, Ian EM Smith, Young Kwan Sohn, Greg Valentine, James White, Bernd Zimanowski, Bernd Zolitschka IAVCEI – CMV/CVS – IAS 4IMC Conference Auckland, New Zealand, 2012 Preface We extend our warmest welcome to delegates of the Fourth International Maar Conference (4IMC) and look forward to hosting you in Auckland, New Zealand. We anticipate an exciting week of scientific exchanges, renewing friendships and making new friends. The original idea of organizing a scientific workshop-type meeting focusing on the great variety of geological processes shown in maar volcanoes arose in the type locality of maar volcanism: the Vulkaneifel Mountains of western Germany. Professors Volker Lorenz and Georg Buechel conceived of a meeting that concentrated on the formation of maar volcanoes in which experts could share their views of the origin of this type of volcanism in their type locality. Daun in western Germany hosted the first International Maar Conference (1IMC) in the year 2000, providing a snapshot of the wealth of knowledge underpinning our understanding of maar volcanoes. 1IMC also highlighted the overarching aspects of volcanism, sedimentation, economic significance and geomorphic problems that maar volcanoes offer anyone who wishes to study them. The location of 1IMC naturally determined that the main focus of the conference was young, intact maar volcanoes, their sedimentary environments, ecological sites and hazard aspects. Four years later the concept of a maar conference was taken to a new level, garnering support from IAVCEI and IAS to produce the second International Maar Conference (2IMC). 2IMC was hosted in Hungary and organized by a tri-nation committee (Hungary – Slovakia – Germany), arranging strongly linked scientific events in each of these three countries. 2IMC was held in the “puszta” (flat lowland) in the small town of Lajosmizse from where field trips went to the western Pannonian Basin and to southern Slovakia to study deeply eroded maar volcanoes. This setting dictated that the main subject of 2IMC had a strong focus on diatremes, the root zones of maar volcanoes. In 2009, for the third International Maar Conference (3IMC), the venue shifted to the Southern Hemisphere. Argentina hosted 3IMC in Malargue, a small desert town in the eastern foothills of the Andes. The location of 3IMC also determined the main focus of the meeting. Malargue is located at the edge of a major monogenetic volcanic field containing over 800 Pliocene to Recent volcanoes. Among this large number of monogenetic volcanoes only a few have been recognized as having a phreatomagmatic eruption history, highlighting the important message that such volcanoes may carry for paleoenvironmental reconstruction as well as for the elevated hazard such eruptions may pose in an otherwise “dry” explosive eruptive centre-dominated field. 3IMC clearly demonstrated the development and global progress of research into small scale magmatic systems commonly referred to monogenetic volcanic fields. Maar volcanoes are recognized as the “wet” equivalents of scoria cones and their eruption history, length, and erupted magma volume show great similarity; maars are strongly v IAVCEI – CMV/CVS – IAS 4IMC Conference Auckland, New Zealand, 2012 influenced by external, while scoria cones by internal, controlling parameters. Shortly after 3IMC a small commemorative workshop was held to celebrate the birth of Jorullo scoria cone in Mexico (Jorullo 250) in 2009 and marked a merging of research groups and research efforts to address the broader aspects of monogenetic volcanism. This led to the establishment of the IAVCEI Commissionon Monogenetic Volcanism (https://vhub.org/groups/iavcei_cmv) that supported the Special Issue of Journal of Volcanology and Geothermal Research that published results from the 3IMC and Jorullo 250 conferences [From Maars to Scoria Cones: the Enigma of Monogenetic Volcanic Fields - JVGR 2011 vol. 201(1-4): 1-412.]. The Fourth International Maar Conference (4IMC) is the first in the IMC series in which the main scope of the conference has been specifically expanded to provide a forum to present research results on all aspects of monogenetic (small-volume) volcanism. The study of small volume magmatic systems has received increasing attention in recent times with the realization that, although their surficial expression is as very small volcanoes, they display a remarkable diversity of geochemical and volcanological features that provides a remarkable insight into the processes of magma generation, differentiation, transport and eruption. Naturally maar volcanoes are a central part of this research and 4IMC continues the tradition established by Volker Lorenz and Georg Buechel. 4IMC is hosted by The University of Auckland and supported by Massey University of Palmerston North. Auckland is the largest city of New Zealand with a population of about 1.5 million, living on an active monogenetic volcanic field of at least 54 individual volcanoes that have erupted during the last 250 ka. Each of these volcanoes had at least a brief phreatomagmatic phase in their initial eruptions, while about 34 volcanoes clearly have well developed tuff rings and shallow maars, putting Auckland among regions facing potentially significant volcanic hazard in the future. 4IMC will surely provide a new view of monogenetic volcanic fields to the participants and will help to bring the sometimes life-and- death questions resulting from our research into the real world. Our basic research is the fundamental platform for decision makers and planners responsible for the well-being and safety of a third of New Zealand’s population. 4IMC is a scientific event supported directly by IAVCEI and IAS. The scientific program and quality is assured by the sponsorship and backing of 4IMC by the IAVCEI Commission on Monogenetic Volcanism and Commission on Volcanogenic Sediments. We hope you will find 4IMC a memorable event and the Abstract Volume a useful collection. Welcome to Auckland, a City of Volcanoes. Conference Chairs Ian EM Smith, Auckland, New Zealand Károly Németh, Palmerston North, New Zealand vi IAVCEI – CMV/CVS – IAS 4IMC Conference Auckland, New Zealand, 2012 Contents Abstracts are listed in alphabetical order of first author. The presenting author is underlined in the Contents and bolded in the abstract. * denotes an invited Keynote Lecture. Oral Presentations Agustin-Flores, J., K. Németh, S. Cronin, J. Lindsay, G. Kereszturi: Insights into the controls on the formation of contrasting tuff rings vs. cones in the Auckland Volcanic Field, New Zealand ................................ 1 Andrews, R., J.D.L. White, M. Rosenberg: Making craters: a review and approach to thermodynamic analysis of the 1886 Rotomahana eruption ................................................................................................... 3 Bebbington, M., S. Cronin: Paleomagnetic and geological updates to an event-order model for the Auckland Volcanic Field ............................................................................................................................. 5 Bishop, M.A.: Volcanic Shield Fields, Newer Volcanic Province, Australia ..................................................... *7 Blaikie, T., L. Ailleres, P. Betts, R. Cas: A geophysical comparison of simple and complex maar volcanoes from the Cainozoic Newer Volcanics Province, Southeastern Australia ............................................ 9 Bosshard, S.A., H.B. Mattsson, J.F. Berghuijs: Origin of fluidal pyroclast morphologies in melilititic monogenetic cones: Insights from the recent explosive eruption of Oldoinyo Lengai, Tanzania ....................... 11 Boyce, J., I. Nicholls, R. Keays, P. Hayman: The multiple magma batches of Mt. Rouse, Newer Volcanics Province, Victoria, Australia ......................................................................................................