SUSTAIN drilling at Surtsey volcano, Iceland, tracks hydrothermal and microbiological interactions in basalt 50 years after eruption

Abstract

Abstract. The 2017 Surtsey Underwater volcanic System for Thermophiles, Alteration processes and INnovative concretes (SUSTAIN) drilling project at Surtsey volcano, sponsored in part by the International Continental Scientific Drilling Program (ICDP), provides precise observations of the hydrothermal, geochemical, geomagnetic, and microbiological changes that have occurred in basaltic tephra and minor intrusions since explosive and effusive eruptions produced the oceanic island in 1963–1967. Two vertically cored boreholes, to 152 and 192 m below the surface, were drilled using filtered, UV-sterilized seawater circulating fluid to minimize microbial contamination. These cores parallel a 181 m core drilled in 1979. Introductory investigations indicate changes in material properties and whole-rock compositions over the past 38 years. A Surtsey subsurface observatory installed to 181 m in one vertical borehole holds incubation experiments that monitor in situ mineralogical and microbial alteration processes at 25–124 ∘C. A third cored borehole, inclined 55∘ in a 264∘ azimuthal direction to 354 m measured depth, provides further insights into eruption processes, including the presence of a diatreme that extends at least 100 m into the seafloor beneath the Surtur crater. The SUSTAIN project provides the first time-lapse drilling record into a very young oceanic basaltic volcano over a range of temperatures, 25–141 ∘C from 1979 to 2017, and subaerial and submarine hydrothermal fluid compositions. Rigorous procedures undertaken during the drilling operation protected the sensitive environment of the Surtsey Natural Preserve.

Basalt-Hosted Microbial Communities in the Subsurface of the Young Volcanic Island of Surtsey, Iceland

“…One of the principal objectives of the 2017 Surtsey Underwater volcanic System for Thermophiles, Alteration processes and Innovative concretes (SUSTAIN) drilling project at Surtsey volcano, sponsored in part by the ICDP, was to investigate microbial diversity within the basaltic tephra. All possible precautions were made to avoid microbial contamination ( Jackson et al, 2019b ). Water from the sea was pumped to the drill site and used as drilling fluid since no fresh water is available on the island ( Figure 1 ).…”

“…Seventeen drill core samples were collected for microbial analyses from the vertical SE-02b cored borehole that extends to 192m below surface and terminates in poorly consolidated tephra a few meters above the presumed depth of the pre-eruption seafloor ( Jackson et al, 2019b ). At the drill site, drill core samples were collected from every third 3-m core run for molecular analyses by cutting a 10-cm section at 70cm from the top of the core run.…”

“…In 1979, a 181m core (SE-01) drilled through the eastern sector of the Surtur vent ( Figure 1 ), probed the hydrothermal system in the subaerial and the submarine deposits – above and below coastal sea level, respectively ( Jakobsson and Moore, 1982 , 1986 ; Jackson et al, 2019a ). In 2017, three new cored boreholes (SE-02a, SE-02b and SE-03) were acquired through the International Continental Scientific Drilling Program (ICDP) 5,059 expedition, SUSTAIN drilling operation ( Jackson et al, 2015 , 2019b ; Weisenberger et al, 2019 ). Annual monitoring of temperatures in the 1979 borehole, SE-01, indicates that the hydrothermal system has cooled down over the years.…”

“…Map of the Surtsey volcanic island within the Westman Islands (Vestmannaeyjar) archipelago and location of sampling sites: 1979 borehole SE-01 and 2017 borehole SE-02b (green star), drilling fluid (blue line), and fumaroles (orange stars). Schematic cross section of Surtur crater showing the geological setting of the subsurface deposits and the location of the time-lapse cored boreholes (see Jackson et al, 2019b ) and a zone of seawater inflow.…”

New geophysical memory-logging system for highly unstable and inclined scientific exploration drilling

“…Furthermore, it is easy and flexible to use, comprises the largest range of sonde types, and is readily available through a large number of academic and commercial providers. In the framework of the International Continental Scientific Drilling Program (ICDP), we have conducted more than 37 wireline logging campaigns (Hodell et al, 2006;Koeberl et al, 2007;Gebhardt et al, 2013;Jackson et al, 2019;Jerram et al, 2019;Abbott and Rodbell, 2020) using slimhole tools. For the majority of these missions, most demands could be covered.…”