Iceland 2014 - Overview of field work
In 2014, I was very lucky to be a recipient of the Lewis and Clarke Fund for Exploration and Field Research in Astrobiology. The fund is awarded by the NASA Astrobiology Institute and the American Philosophical Society (more info here). My proposal involved sampling six hydrothermal sites (fancy words for 'hot springs') in Iceland, as well as exploring the Heimaey island in the South for the existence of possible hot springs. This blog describes the adventures at each site! But first I wanted to give a bit of background as to why this work was important and interesting.
Iceland is an island located in the mid-Atlantic where the oceanic spreading ridge can be studied at the surface. Additionally sustained by a mantle plume, Iceland is an ideal natural laboratory to study basaltic rocks (a type of volcanic rock) influenced by hydrothermal circulation. The heat of continental hydrothermal systems drives water circulation through the subsurface, enabling sampling of active processes at depth without drilling.
The geology of Iceland allows sampling of diverse hydrothermal waters hosted within dominantly tholeiitic basalts (reduced magmas with high magnesium and low sodium). Alkali basalts (oxidizes magmas rich in iron and high in alkalis) also exist in Iceland at the Westmann Islands and Snæfellsnes peninsula (which I went to, and will show pictures of in upcoming blog posts!).
With a well-developed road infrastructure (albeit many needing 4x4 and come with the occasional river crossings!), springs in Iceland are easily accessed by vehicle and a short to moderate hike, making Iceland ideally suited for efficient and cost-effective sampling of a broad range of basaltic spring and spring types. Six sites were sampled during this 14 day exploratory field research.
Because of the spreading ridge going right through the country, the geology of Iceland is spectacular!
But why did I want to sample the springs in the first place? The answer is Hydrogen.
The reaction of water with rock produces hydrogen (H2) via several processes that are widespread on Earth. Those processes are expected to occur on rocky planetary bodies where liquid water is present. Such reactions can represent a continuous supply of chemical energy for possible types of life that rely on the results of the chemical reaction between volcanic rocks and water for food.
Hydrogen-fueled microbes are of particular interest because they are both widespread and deeply rooted in the phylogenic tree of life, implying they may have emerged extremely early in the evolution of life on Earth, and possibly even at the origin of life. As a result, H2-fueled microbes are strong candidates for the potential of life beyond Earth.
The goal of this work is to assess the variation in continental H2 abundance in hydrothermal springs across basaltic host rocks, in order to assess their potential habitability. The first step to do so is understand what concentrations of H2 can be expected in such systems. This information can then be fed into the bioenergetic computer models that I have been working on to quantitatively assess H2-utilizing metabolic energy yields.
Basalt is the dominant rock type on Mars, and so this study can provide a “living analog” to ancient Mars when such hydrothermal systems existed, as shown by the relic presence of hydrothermal minerals detected on the martian surface (such as the detection of pure silica deposits).
Furthermore, this study would further complement existing datasets and research projects exploring mafic and ultramafic rocks in submarine hydrothermal vents (e.g. the “Lost City” hydrothermal fields) at one end of the spectrum, to hydrothermal systems in more felsic rocks in continental settings, such as found in Yellowstone National Park and Lassen National Park at the other end.
Iceland is easily accessed from the US! Myself and my fieldie, Katie, flew directly to Reykjavik from Seattle. Stay tuned!
Site 4: Geysir
Site 5: Hveravellir
Site 6: Hveragerdi