The Sedimentary Volcanology sub-theme encompasses research on eruption, transport and deposition dynamics in modern and ancient volcanic successions. Sub-projects include:

CALDERA-FORMING SUBMARINE VOLCANISM

Widespread seafloor waveforms, called sediment waves, surround many modern submarine silicic caldera arc volcanoes. Many of these sediment waves have been attributed to caldera-forming eruptions in a recent study published by Dr Martin Jutzeler. In the Kermadec arc, two volcanoes have sediment waves that form gigantic fanning out, upward-migrating cyclic steps and anti-dune deposits, suggesting extreme fluxes of deposition from supercritical density currents directly linked with caldera-forming volcanism. In 2019 Dr Martin Jutzeler and co-CI Dr Rebecca Carey were successful in obtaining time on the RV Investigator for a 29-day voyage they will lead in October 2020. The aim of this voyage is to link the behaviour of deep submarine eruptions with the morphology of their deposits using seismic reflection and sediment coring at several calderas in the Kermadec arc, north of New Zealand. The high-resolution seismic transects will enable new ore vectoring strategies for exploration in Australia and provide essential data to propose an IODP expedition to drill these calderas.

ANAK KRAKATAU VOLCANO, INDONESIA

In December 2018 Anak Krakatau volcano dramatically collapsed with part of its newly built cone falling into the surrounding shallow ocean basin. The 2018 collapse created a tsunami in the Sunda Strait, killing more than 400 people in Java and Sumatra. In 2019 Dr Martin Jutzeler and Dr Rebecca Carey were successful in obtaining ship-time for a 38-day voyage in October 2021 on board the RV Investigator. Our team will investigate the submarine deposits of the volcanic landslide using bathymetry, seismic reflection, deep-tow cameras and sediment coring to understand the sedimentary mechanisms that produced the tsunami, and reconstruct the eruption and tsunami sequence.

PROVENANCE OF VOLCANIC SEDIMENT OFFSHORE OF ANTARCTICA

Dr Martin Jutzeler was an onshore participant in the two-month ocean drilling IODP 379 expedition in the Amundsen Sea (western Antarctica). The expedition was facilitated by the RV JOIDES Resolution (USA) and led by K. Gohl and J. Wellner. Dr Jutzeler requested samples of sandy to pebbly material from ice-rafted debris, and possible turbidites and tephra fallout. This study will reconstruct the provenance of volcanic sediment by chemical fingerprinting using the LA-ICP-MS and the microprobe.

The Sedimentary Volcanology project encompasses research on eruption, transport and deposition dynamics at modern volcanoes and in ancient successions with the aim of improving the reconstruction of volcanic architecture in ancient analogues. Sub-projects include:

PROVENANCE OF CALDERA-FORMING DEPOSITS IN THE IZU-BONIN ARC

In 2018 Martin Jutzeler and co-Principal Investigator Rebecca Carey obtained a $10,000 grant from the Australia and New Zealand Consortium to the International Ocean Discovery Program (ANZIC) to carry out geochemical analyses on pumice-rich deposits drilled in the Sumisu Rift in the Izu-Bonin arc. These LA-ICP-MS analyses will complement preliminary analyses on the microprobe. This study will provide additional data to narrow down the source of gigantic pumice-rich beds to specific nearby calderas, and thus allowing further study on transport processes associated with caldera-forming submarine silicic eruptions.

VOLCANIC AND CLIMATE-INDUCED SOURCE OF HEMIPELAGIC MUD IN ISLAND ARCS

Martin Jutzeler took an active role during 2018 in a multidisciplinary study led by Professor James Gill at UCSC, addressing the provenance of very thick Miocene to modern successions of very fine-grained hemipelagic mud in the Izu-Bonin rear-arc. This study shows evidence through geochemistry and componentry that the microparticles forming most of the hemipelagic mud are chiefly products from local rear-arc volcanism, and do not originate from organic marine snow. These volcanic particles are chiefly <60 microns, making them particularly difficult to study and identify. Interestingly, the overall local contribution of hemipelagic mud shifts during glacial periods, with most of the sediment chemical composition pointing towards a Chinese loess source. Heightened accumulation of this foreign component during glacial periods points towards a modification of the path of the Kuroshio current due to climate change since the Miocene. This study demonstrates the role of climatic variations and ocean currents as external contributors to the morphology of volcanic arcs, locally modifying sedimentation rate and the composition of fine sediments.

ORIGIN OF GIANT SEDIMENT WAVES ON SUBMARINE CALDERA VOLCANOES

Martin Jutzeler co-led a study, published in Earth and Planetary Science Letters (EPSL) during 2018, that identified the origins of widespread seafloor waveforms surrounding modern submarine silicic caldera arc volcanoes. Using bathymetry and seismic reflection data, the team identified the morphological characteristics of two waveform end-members. The deposits derived from caldera-forming explosive eruptions are made of widespread, fanning out, upward-migrating cyclic steps and anti-dune deposits, suggesting extreme fluxes of deposition from Froude supercritical density currents. In contrast, landslide-derived deposits are funnelled, can be backward rotated, and linked to arcuate headwalls. This study is aligned with ore exploration, through identification of key volcanic facies aimed at improved volcanic architecture reconstruction in marine settings.

During the year Martin Jutzeler and co-Principal Investigator Rebecca Carey submitted a Marine National Facility proposal for shiptime aboard the RV Investigator in 2020. The aim of this voyage is to link the behaviour of deep submarine eruptions with the morphology of their deposits. The project will investigate the architecture of three modern submarine silicic calderas in the Kermadec arc, north of New Zealand, using seismic reflection and shallow coring. The calderas sit at various water depths, and this study will tackle the interdependency of magma flux to hydrostatic pressure. Outputs from this study include modelling of sediment mass fluxes during such eruptions, and thus the production of the first-ever hazard mapping scheme for submarine volcanoes globally (tsunami and sediment flows). This project will identify the true nature of sediment waves on the flank of these calderas and evaluate the tsunamigenic potential of submarine volcanism. Further, high-resolution seismic transects will enable new ore vectoring strategies for exploration in Australia and provide essential data to propose an International Ocean Discovery Program (IODP) expedition to drill these calderas.

In 2018 Martin Jutzeler received a $9,000 seed grant from UTAS to organise an international workshop to frame a deep-sea drilling pre-proposal to the IODP. The workshop was held in December in Washington DC, USA, just before the AGU Fall Meeting. The aim of the workshop was to identify the major scientific questions relative to modern submarine silicic caldera volcanism. The major specific aims include characterisation of the volcanic architecture, relationship between magmatic and hydrothermal systems, magma evolution, and collection of the entire stratigraphy of the proximal sediment wave deposits. This IODP pre-proposal will be submitted in late 2019.

PUMICE RAFTS

Research on pumice rafts on several fronts is being led by Martin Jutzeler. Pumice rafts are floating accumulations of pumice clasts derived from submarine and coastal volcanism, and are dispersed over thousands of kilometres by surface ocean currents and wind. In collaboration with oceanographers at the National Oceanography Centre Southampton (UK) and the University of Utrecht (Netherlands), the team explored the statistical dispersal of pumice rafts at a global scale, based on surface ocean model hindcast. Martin is also leading another research topic on pumice rafts, using abrasion experiments in wave tanks that recreate pumice-to-pumice attrition in the open sea.  Results show compelling evidence for voluminous production of fine material that would accumulate as fine tephra on the seafloor. Both studies explore the role of pumice rafts on local climate and biochemical cycles, and their consequences for pelagic and benthic communities. These studies are also providing strong links with volcanic architecture and ore exploration, by identifying ultra-distal marine facies derived from high-intensity submarine eruptions, such as that produced by the Havre submarine caldera in 2012.

Sub-projects in the ‘Sedimentary volcanology’ theme are focussed on volcano sediment aprons and volcanic architectures, to better understand ancient analogues.

LACUSTRINE SEDIMENTATION OF MASS FLOWS: OLIGOCENE ANCESTRAL CASCADES VOLCANO ARC

This sub-project aims to characterise the sedimentation mechanisms acting in lakes adjacent to subaerial arc volcanoes. The Oligocene Wildcat Creek beds in Washington State, USA, record volcaniclastic deposition in a lacustrine basin in the Ancestral Cascades arc. The succession is well exposed over 300 km² of remote forested area, and is made up of hundreds of laterally extensive beds interpreted to record below wave-base deposition of explosive subaerial volcanism in a lacustrine setting.

In 2016 and 2017, Martin Jutzeler carried out detailed stratigraphic logging and extensive fieldwork in wilderness areas that allowed the reconstruction of the architecture of the basin. Facies analysis identified deposits from eruption-fed pyroclastic density currents, subaqueous debris flows, airfall onto water, reworking by rivers, and local peperitic intrusions. Preliminary results from 2016 fieldwork were published as a United States Geological Survey field guide in 2017. This project is part of a broader research focus on subaqueous volcaniclastic density currents encompassing marine core data collected by Martin during International Ocean Discover Program expeditions 340 and 350 in island arcs.

ORIGIN OF GIANT SEDIMENT WAVES ON SUBMARINE VOLCANOES

Based on marine geophysical data, this sub-project identifies the origins of widespread seafloor waveforms surrounding submarine silicic caldera arc volcanoes. The eruption-fed waveforms identified at several submarine volcanoes worldwide consist of fanning out, upward-migrating cyclic steps and anti-dune deposits, resulting from voluminous deposition from Froude supercritical density currents. These deposits indicate high-flux sedimentation regimes that were reached at the climactic phase of silicic caldera-forming submarine explosive eruptions.

Further, this project identifies key characteristics that distinguish these bedforms from submarine landslide deposits, and compares them with subaerial analogues. This study has strong links with ore exploration, through reconstruction of volcanic architecture and identification of a new type of proximal volcaniclastic deposits. Martin Jutzeler has co-led the study and is author of a manuscript to be published in Earth and Planetary Science Letters in early 2018.

REGIONAL DISPERSAL OF VOLCANIC PRODUCTS IN THE KERMADEC ARC, NEW ZEALAND

Knowledge about the dispersal of pyroclasts in island arc and backarc settings remains very poor. In 2017, Martin Jutzeler participated as sedimentologist/volcanologist on a six-week voyage aboard the new R/V Sonne, flagship of the German research fleet; the voyage (expedition SO255) was led by Professor Kaj Hoernle (GEOMAR Germany). Through dredging at 179 stations over 200,000 km², Martin collected numerous samples of volcaniclastic sediment and hemipelagic mud rich in volcanic particles. This extensive collection will allow us to chemically characterise the dispersal of pyroclasts in the context of an island arc, and compare it with compositions of known edifices. This will allow reconstruction of sedimentation patterns by ocean and atmospheric dispersal. Further, multiple samples include rafted pumice clasts from the 2012 deep submarine eruption of Havre volcano. Mapping of these deposits will constrain dispersal of pumice clasts by surface oceanic currents and improve existing models of oceanographic current modelling.