Current Research Projects

The WiscAr Laboratory collaborates with researchers and institutions from around the world. While we work on numerous small research projects, the lab also focuses on large scale innovative studies that use geochronology, geochemistry, and petrology to better understand Earth’s history.

Here are some of the major research projects the WiscAr team are currently working on:

 

Ice forcing in arc magmatic plumbing systems (IF-AMPS)

From left to right: Brad, Pablo, and Brent Alloway (senior volcanologist) conducting fieldwork on Osorno volcano

A question at the frontier of Earth science is: how do changes in the climate system on our planet’s surface interact with magma reservoirs housed within its interior? We will conduct a novel blend of field observations, lab measurements, and numerical model simulations in an integrated study of links between changes in glaciers and topography, and the behavior of several active volcanoes in Chile during the last 50,000 years. These volcanoes were partly covered by the 3,000 foot thick Patagonian ice sheet until it melted rapidly beginning 18,000 years ago. This natural laboratory offers unparalleled means to investigate how the rapid loss of ice impacted the composition and rates of eruptions from these volcanoes. This project will provide career-building experience for several PhD students. A volcano & ice Summer program will engage technical school students from underrepresented groups in the US and Chile in field- and lab-based experiences, including training in drone technology for data collection and geologic mapping. Our collaborations with Chilean scientists and educators aim to: (1) enhance knowledge of the growth rates and eruptive histories of several of the most dangerous volcanoes in South America, thereby improving hazard assessment, (2) generate new climate proxy data critical to calibrating our numerical model of ice sheet retreat, and (3) train students from the communities living near these volcanoes.

Brad conducting fieldwork around Mocho-Choshuenco volcano. Riñihue lake can be seen in the back

Utilizing new and existing geochronologic, geochemical, glacial and erosion/deposition observations within the Andean Southern Volcanic Zone, we aim to couple a suite of numerical models to test and refine three hypotheses: (1) Over short timescales (<100,000 year), the composition, volume, and timing of eruptions are strongly influenced by climate-driven changes in surface loading. These short-term responses modulate the long-term (>100,000 year) average eruptive characteristics, which are governed by mantle melt flux, (2) Crustal stress changes associated with the local onset of rapid deglaciation and erosion at 18,000 years ago promoted eruptions by enhancing volatile exsolution that in turn pressurized stored magma and propelled dike propagation to the surface, and (3) Responses to rapid unloading will vary among volcanoes, reflecting contrasts in the composition, volatile contents, and compressibility of stored magma, as well as the rate at which crustal reservoirs are recharged from depth. This variability can be exploited to reveal fundamental controls on the sensitivity of glaciated arcs to the climate system. To investigate these hypotheses, we will pursue four objectives: (1) Generate high-resolution records of cone growth, eruptive behavior, and geochemical evolution of six volcanoes during the last ~50,000 years spanning 250 km along the subduction zone, (2) Build new records of ice retreat, and landscape evolution owing to the erosion, transport, and deposition of sediment adjacent to the six volcanoes, (3) Use the observed chemical and physical patterns in the volcanic, climatic, and topographic records to constrain crustal loading through time, and explore the effects of this forcing in numerical models, and (4) Integrate findings to contextualize processes in continental settings, and provide a framework for examining the sensitivity of arc volcanism to external forcing elsewhere and across a spectrum of climate states throughout Earth history.

Pablo collecting samples from the 1835 eruption at Osorno volcano. This eruption was glimpsed by Charles Darwin during his second voyage on the Beagle
Columnar basalts at the route around Osorno volcano. These lava flows are around 170±50 ka

 

 

 

 

 

 

 

NSFGEO-NERC: Foundation for the next generation of paleoceanographic and biogeochemical studies: Developing a new Lower Cretaceous time scale

The Cretaceous was a time of global warming during which atmospheric carbon dioxide levels surpassed 800 ppm, similar to that predicted for 2100 by “business-as-usual” emission scenarios. Cretaceous rocks record high sea levels, high biological productivity, massive volcanism, and major perturbations of the carbon cycle during several ocean anoxic events (OAEs). Understanding these phenomena can provide deep-time analogs for future greenhouse scenarios. Marine sediments that record these crises are globally widespread, but weaving these records into a common temporal framework is essential if they are to reveal the drivers.  This project aims to generate a new temporal framework spanning 125 to 93 million years ago during which several major OAEs occurred. This will permit examination of repeated deteriorations of marine ecosystems across the Pacific, Atlantic, and Mediterranean oceans. Novel outreach, international collaboration, and training of future earth science leaders feature prominently. We will bring deep-time science to the public via presence at the Sturgis Motorcycle Rally.

The favored hypothesis for OAEs involves volcanic initiation leading to a cascade of processes amplifying global marine production; key factors are the nature of volcanism and the source of increased nutrients. Yet geographic differences in proxy records (C and Os isotopes) indicate additional complexities, such as sea level and ocean circulation. Our goals are to establish: (1) A new time scale for global geochemical and paleobiologic datasets; (2) Chemostratigraphic correlation of the new time scale to European sections using C and Os isotope stratigraphy, and (3) A new global time scale for improved understanding of major biogeochemical perturbations. We will: (i) Determine radioisotopic ages of rhyolitic tuffs in sediments of Japan, (ii) Integrate these new ages with new Os-, and C-isotope chemostratigraphy in Europe, (iii) Compile global geochemical proxy data for OAE1a within a common temporal and stratigraphic framework, and analyze trends and patterns from the Pacific to Europe, (iv) Evaluate the volcanic versus climatic/orbital hypotheses for OAE initiation, and (v) Explore the significance of geography in the timing and magnitude of geochemical signals.

 

Early Evolution of the Hawaiian Plume from the Geochemistry and Geochronology of Basalts Spanning the Entire Emperor Seamount Chain

The Hawaiian-Emperor Chain is one of the longest (>6,000 km), largest (>6 million km3), and most persistently active (>100 volcanoes over ~80 million years) “hotspot” provinces on Earth. The extensive volcanism of the Hawaiian-Emperor Chain is caused by the Hawaiian mantle plume, which likely rises buoyantly from the core-mantle boundary and produces some of the hottest and most primitive basalt lavas of the the last 100 million years. Studies of the Hawaiian-Emperor Chain have led to major discoveries and concepts of critical importance to the Earth Sciences, including plate tectonics and the nature of compositional heterogeneity in the deep mantle. The Emperor Seamounts are the least studied, and most enigmatic portion of the Hawaiian-Emperor Chain.

This project will examine the temporal-compositional evolution of the oldest (~80-50 Ma) volcanoes of the Hawaiian-Emperor Chain using the geochemistry (major and trace elements, and Pb-Sr-Nd-Hf isotope ratios) and geochronology (40Ar/39Ar incremental heating) of the Emperor Seamounts. The major goals are (1) to delineate the transition of the Hawaiian mantle plume from a near-ridge environment to the recent style of upwelling that is far from plate boundaries and (2) improve understanding of Pacific mantle dynamics. This is a collaborative project with scientists from the University of Hawaii at Manoa.

 

 

The Tatun Volcanic Group: From hazards to risk

Throughout the centuries of historical record, the volcanoes of the Tatun Volcanic Group (TVG) north of Taipei have steamed away benignly, without dangerous eruptions.  The hazards posed by the TVG remain nebulous. A large team of international scientists led by Kerry Sieh (formerly of Cal Tech and Earth Observatory of Singapore) will characterize the hazards posed by the Tatun Volcanic Group far more thoroughly and accurately than has yet been done and to use these data to calculate levels of exposure and risk.  First, we will use existing very high-resolution LiDAR imagery of the TVG to map its myriad of volcanic edifices, lava flows, pyroclastic flows, lahars and other collapses in unprecedented detail.  Based upon the relationships thus revealed, we will select a suite of edifices, flows and other volcanic features for further petrologic and geochronologic study.  We will use state-of-the-art 40Ar/39Ar and radiocarbon geochronology to determine the ages and age relationships of several young edifices and their various components.  For a subset of young eruptions, we will use diffusion chronometry to determine the behavior of magmas in the decades to weeks prior to their past eruptions. Together these activities will provide the data needed to make the first quantitative estimates of the hazards posed by the TVG.

Once the hazards have been quantified, we will turn to estimating from demographic and infrastructural data the exposure and risks posed to Taiwan’s citizenry, select industries, and governance.  In this we will assist the National Center for Disaster Reduction (NCDR) in their missions to enhance disaster risk reduction and emergency preparedness and to engage with at-risk communities.  Another major outcome of this project will also be the training of a new generation of Taiwanese earth scientists in hazard-, exposure-, and risk-oriented earth science and technology.

Sulfur crystals growing from an active hydrothermal vent in the TVG.
Steam coming from an active vent in the central TVG.