Petrographic studies of thin sections from the 1979 and 2017 Surtsey drill cores provide new insi... more Petrographic studies of thin sections from the 1979 and 2017 Surtsey drill cores provide new insights into microstructural features in basaltic lapilli tuff sampled from the principal structural and hydrothermal zones of the volcano. These describe narrow rims of fine ash on altered glass pyroclasts in thin sections of the 2017 cores, characteristics of granular and microtubular structures in the original thin sections of the 1979 core, and glass alteration in diverse environments. The narrow ash rims follow the outlines of glass pyroclasts in the subaerial tuff cone and in submarine and sub-seafloor deposits; they suggest complex eruptive and depositional processes. The tubular microstructures resemble endolithic microborings in older oceanic basalt; they suggest possible microbial activity. Tubule lengths indicate rapid growth rates, up to 30 µm in ~15 years. Comparisons of glass alteration in thin sections prepared immediately after drilling in 1979 and 2017 indicate differential...
Programs are presented which calculate angular relations among fault attitude, marker-plane attit... more Programs are presented which calculate angular relations among fault attitude, marker-plane attitude and slip direction, and determine the extension or contraction of the marker by the fault slip. The programs are written both in FORTRAN and in the reverse-Polish language implemented on Hewlett-Packard type hand calculators. Examples of program use are presented.
left-stepping, en echelon ground cracks within the Kaoiki seismic zone, on the southeast flank of... more left-stepping, en echelon ground cracks within the Kaoiki seismic zone, on the southeast flank of Mauna Loa volcano, Hawaii. The general trend of the ruptures, N48ø-55øE, parallels a nodal plane of the main shocks' focal mechanisms. The ruptures themselves consist of short, predominantly extension cracks, which are up to 20 m long and strike roughly E-W, 300-50 ø clockwise from the overall trend of the zones. Some of the cracks are linked by secondary fractures and rubble breccia to form left-stepping crack arrays, which are themselves linked to form longer en echelon systems of ground rupture. Geologic maps and field observations indicate that these features emerge from an underlying strike-slip fault, and they form a "fracture-process zone" above its tip. The maximum displacement measured across cracks in the 1983 rupture zone is 0.5 m. Trilateration data, however, suggests that the overall shear displacement was about 1.5 m at depth. Elastic solutions indicate that a region of significant tensile stress can exist above buried strike-slip faults. We suggest that these stresses generated the extensional ground cracks and that shear displacements were transmitted to the Earth's surface by subsequent growth and linkage of these cracks into the observed arrays. We infer that the crack arrays accommodate increased displacement with depth and they merge downward into the "parent" strike-slip fault at an estimated 1-2 km depth, where strike-slip displacement was probably more or less continuous along the-•7 km length of the rupture. In the Kaoiki region, only three major ground ruptures traverse a series of basaltic lava flows that date back 1500 years. This suggests that the recent-• 10-year periodicity of moderate-magnitude Kaoiki strike-slip events may not have extended far into the past. The tectonic significance of strike-slip faulting on Mauna Loa volcano remains enigmatic.
Colonisation of life on Surtsey has been observed systematically since the formation of the islan... more Colonisation of life on Surtsey has been observed systematically since the formation of the island 50 years ago. Although the first colonisers were prokaryotes, such as bacteria and blue-green algae, most studies have been focusing on settlement of plants and animals but less on microbial succession. To explore microbial colonization in diverse soils and the influence of associate vegetation and birds on numbers of environmental bacteria, we collected 45 samples from different soils types on the surface of the island. Total viable bacterial counts were performed with plate count at 22°, 30° and 37°C for all soils samples and the amount of organic matter and nitrogen (N) was measured. Selected samples were also tested for coliforms, faecal coliforms aerobic and anaerobic bacteria. The deep subsurface biosphere was investigated by collecting liquid subsurface samples from a 182 meters borehole with a special sampler. Correlation was observed between N deficits and the number of microo...
This site lies in the historic core of Beccles, as outlined in the County Historic Environment Re... more This site lies in the historic core of Beccles, as outlined in the County Historic Environment Record (BCC 018). Medieval and later archaeological features were recorded immediately to the north (BCC 025 and Misc.). Urban archaeological deposits have the potential to be relatively complex. No objection in principle but the site will require a planning condition under the NPPF to secure a programme of archaeological investigation. Evaluation at as early a stage as possible is recommended so that costs and timescales for archaeological work can be factored in to project designs. A programme of archaeological work will be required, secured through a planning condition.
Roman hydraulic maritime concretes of the central Italian coast have Flegrean vitric tuff as coar... more Roman hydraulic maritime concretes of the central Italian coast have Flegrean vitric tuff as coarse aggregate and mortar pozzolan. Pozzolanic reaction at high pH produced silica-rich CASH and calcium carbonate cements; tobermorite in the residual cores of lime and vitric tuff clasts; and ettringite and calcium-chloroaluminate in bead-like microstructures and voids. Phillipsite may reflect dissolution of residual alkali-rich volcanic glass at lower pH. The cement systems seem to have remained relatively stable during partial to full immersion in seawater for 2000 years. Further analytical investigations will determine the diverse chemical processes that produced specific cement microstructures.
Micrometer‐scale maps of authigenic microstructures in submarine basaltic tuff from a 1979 Surtse... more Micrometer‐scale maps of authigenic microstructures in submarine basaltic tuff from a 1979 Surtsey volcano, Iceland, drill core acquired 15 years after eruptions terminated describe the initial alteration of oceanic basalt in a low‐temperature hydrothermal system. An integrative investigative approach uses synchrotron source X‐ray microdiffraction, microfluoresence, micro‐computed tomography, and scanning transmission electron microscopy coupled with Raman spectroscopy to create finely resolved spatial frameworks that record a continuum of alteration in glass and olivine. Microanalytical maps of vesicular and fractured lapilli in specimens from 157.1‐, 137.9‐, and 102.6‐m depths and borehole temperatures of 83, 93.9, and 141.3 °C measured in 1980, respectively, describe the production of nanocrystalline clay mineral, zeolites, and Al‐tobermorite in diverse microenvironments. Irregular alteration fronts at 157.1‐m depth resemble microchannels associated with biological activity in ol...
Horace could more accurately have compared the celebrated lifespan of his poems to the extremely ... more Horace could more accurately have compared the celebrated lifespan of his poems to the extremely durable concrete monuments that were being constructed in Rome and the harbors of the Mediterranean region by his patron, Octavian, who would become Emperor Augustus (27 BCE– 14 CE) (Figure 1a–c). Bronzes irreversibly and inexorably decay through chloride corrosion in coastal and marine environments, and Egyptian pyramids are now collapsing—having suffered progressive differential movement and detachment of their limestone blocks, probably through anisotropic thermal expansion of calcite during heating by transit of the sun in the desert and subsequent disruption through seismic ground shaking. I have crafted a monument more lasting than bronze, more imposing than the royal structure of the pyramids, one that neither eroding rain nor the furious North Wind can bring to ruin, nor the passage of countless years and the flight of time.
Comparison of investigations of the 1979 and 2017 cored boreholes coupled with continued observat... more Comparison of investigations of the 1979 and 2017 cored boreholes coupled with continued observations of the dynamic surface of Surtsey has modified our concepts of the subsurface structure of the volcano. A geometrical analysis of the 2017 vertical and inclined cores indicates that near-surface layering dips westerly, indicating that the boreholes are located inside the Surtur crater. In subaerial deposits, as well as in deep deposits below sea level and below the pre-Surtsey seafloor, there are zones of porous tuff that contain abundant pyroclasts with narrow rims of fine ash. These features, typical of near-surface deposits, could have been carried down the vent by downslumping during fluctuating explosive activity. They support the hypothesis that a broad diatreme underlies the Surtur vent. No major intrusions were encountered in the 2017 drilling except for coherent basalt in deep sub-seafloor deposits below the center of Surtur crater. The 2017 borehole temperature measurement...
Surtsey is a young volcanic island in the offshore extension of Iceland's southeast rift zone tha... more Surtsey is a young volcanic island in the offshore extension of Iceland's southeast rift zone that grew from the seafloor during explosive and effusive eruptions in 1963-1967. In 1979, a cored borehole (SE-1) was drilled to 181 m depth and in 2017 three cored boreholes (SE-2a, SE-2b and SE-3) were drilled to successively greater depths. The basaltic deposits host a low-temperature (40-141 °C) seawater-dominated geothermal system. Surtsey provides an ideal environment to study water-rock interaction processes in a young seawater geothermal system. Elemental concentrations (SiO2, B, Na, Ca, Mg, F, dissolved inorganic carbon, SO4, Cl) and isotope contents (δD, δ 18 O) in borehole fluids indicate that associated geothermal waters in submarine deposits originated from seawater modified by reactions with the surrounding basalt. These processes produce authigenic minerals in the basaltic lapilli tuff and a corresponding depletion of certain elements in the residual waters. Coupling of measured and modeled concentrations investigates the effect of temperature and associated abundance of authigenic minerals on chemical fluxes from and to the igneous oceanic crust during lowtemperature alteration. The annual chemical fluxes calculated at 50-150 °C range from-0.01 to +0.1×10 12 mol yr-1 for SiO2, +0.2 to +129×10 12 mol yr-1 for Ca,-129 to-0.8×10 12 mol yr-1 for Mg and-21 to +0.4×10 12 mol yr-1 for SO4 where negative values indicate chemical fluxes from the ocean into the oceanic crust and positive values indicate fluxes from the oceanic crust to the oceans. These flux calculations reveal that water-rock interaction at varying water-rock ratios and temperatures produces authigenic minerals that serve as important sinks of seawaterderived SiO2, Mg and SO4. In contrast, water-rock interaction accompanied by dissolution of 2 basaltic glass and primary crystal fragments, provides a significant source of Ca. Such lowtemperature alteration could effectively influence the elemental budget of the oceanic igneous crust and ocean waters. The modelling provides insights into water chemistries and chemical fluxes in low-temperature MOR recharge zones. Surtsey also provides a valuable young analogue for assessing the chemical evolution of fluid discharge over the life cycles of seamounts in ridge flank systems.
The formation of the oceanic island Surtsey in the shallow ocean off the south coast of Iceland i... more The formation of the oceanic island Surtsey in the shallow ocean off the south coast of Iceland in 1963-1967 remains one of the best-studied examples of basaltic emergent volcanism to date. The island was built by both explosive, phreatomagmatic phases and by effusive activity forming lava shields covering parts of the explosively formed tuff cones. A detailed gravity survey was carried out on Surtsey in July 2014 with a gravity station spacing of~100 m. We analyse these data in order to refine a 2.5D-structural and density model of the internal structure for this type locality of Surtseyan volcanism. We carry out a complete Bouguer correction of these data using total terrain corrections based on detailed DEMs of the island and the submarine bathymetry. The principal components of the island are the two tuff cones composed principally of lapilli tuff; this was originally phreatomagmatic tephra formed in the explosive phases of the eruption. Lapilli tuff can be subdivided into (1) submarine lapilli tuff and (2) lapilli tuff above sea level. Other units are (3) subaerial lava, and (4) subaqueous lava deltas. Minor components that are volumetrically insignificant are small intrusions, and unconsolidated and unaltered tephra, still found in thin layers flanking the tuff cones. An additional formation, relevant for any analysis of the subsurface structure of Surtsey, is (5) the sedimentary rocks making up the seafloor, being at least 100 m thick but probably much thicker. Using measurements of the density of all the above components, and subdividing the island into different units based on its pattern of growth, we specifically attempt to constrain the width and depth of diatreme structures proposed by Moore (1985) and confirmed in the ICDP SUSTAIN drilling of Surtsey in 2017 (Jackson et al., 2019). Our forward modeling is aided by a detailed subdivision of the island into units (1) to (4) based on repeated mapping of the island during 1964-1967.
Journal of Volcanology and Geothermal Research, 2019
The evolution of hydrothermal alteration in glassy and variably palagonitized tuff, erupted as te... more The evolution of hydrothermal alteration in glassy and variably palagonitized tuff, erupted as tephra in 1963-1964 on Surtsey, an island built in the offshore extension of Iceland's southeast rift zone, is documented through a comparative petrographic study of samples from drill cores recovered in 1979 and 2017. Time-lapse alteration within the low-temperature meteoric to seawater dominated hydrothermal system of the volcano is characterized in terms of secondary mineral contents, alteration rates and alteration style with depth. Between 1979 and 2017 palagonitization and cementation by secondary minerals has progressed into previously poorly altered parts of the system, leading to increased consolidation of the basaltic tephra. Alteration rates range between 1.05 and 42.5 μm•yr -1 for palagonitization of glass and 0.4-8.33 μm•yr -1 for pseudomorphic olivine replacement by clay minerals over a temperature interval of 47-140 °C. Five distinct zones of alteration style, distinguished through alteration mineralogy, development of authigenic phases over time, as well as degree of alteration are described. Alteration of basaltic tephra at Surtsey volcano is defined by an early stage of phillipsite and clay mineral formation, followed by a later stage of analcime and tobermorite formation as well as replacement of phillipsite below the water table in zone 2 between 65.4 and 138.4 m. Only minor advancement of alteration is detected in zone 3 between 138.4 and 150.3 m depth, where the primary tephra remains largely unpalagonitized and unconsolidated. In contrast, from 1979 to 2017 alteration has increased between 150.3 and 177.8 m depth, in zone 4, leading to rapid and extensive glass and olivine alteration. The quantification of these time-lapse hydrothermal alteration processes at Surtsey provides an important reference for studies of the evolution of young oceanic islands hosting hydrothermal systems.
Micrometer-scale maps of authigenic microstructures in submarine basaltic tuff from a 1979 Surtse... more Micrometer-scale maps of authigenic microstructures in submarine basaltic tuff from a 1979 Surtsey volcano, Iceland, drill core acquired 15 years after eruptions terminated describe the initial alteration of oceanic basalt in a low-temperature hydrothermal system. An integrative investigative approach uses synchrotron source X-ray microdiffraction, microfluoresence, micro-computed tomography, and scanning transmission electron microscopy coupled with Raman spectroscopy to create finely resolved spatial frameworks that record a continuum of alteration in glass and olivine. Microanalytical maps of vesicular and fractured lapilli in specimens from 157.1-, 137.9-, and 102.6-m depths and borehole temperatures of 83, 93.9, and 141.3°C measured in 1980, respectively, describe the production of nanocrystalline clay mineral, zeolites, and Al-tobermorite in diverse microenvironments. Irregular alteration fronts at 157.1-m depth resemble microchannels associated with biological activity in older basalts. By contrast, linear microstructures with little resemblance to previously described alteration features have nanocrystalline clay mineral (nontronite) and zeolite (amicite) texture. The crystallographic preferred orientation rotates around an axis parallel to the linear feature. Raman spectra indicating degraded and poorly ordered carbonaceous matter of possible biological origin are associated with nanocrystalline clay mineral in a crystallographically oriented linear microstructure in altered olivine at 102.6 m and with subcircular nanoscale cavities in altered glass at 137.9-m depth. Although evidence for biotic processes is inconclusive, the integrated analyses describe the complex organization of previously unrecognized mineral texture in very young basalt. They provide a foundational mineralogical reference for longitudinal, time-lapse characterizations of palagonitized basalt in oceanic environments. Plain Language Summary The thermal, chemical, and mineralogical evolution of basaltic rocks and the physical properties Earth's oceanic and continental crust are fundamentally linked. To better understand the evolution of basalt alteration over short geologic timescales, we turn to a newly formed volcanic island, Surtsey, in southern Iceland. The analyzed samples are composed of glassy basaltic fragments, created by explosive interactions between magma and seawater. They come from drill core collected in 1979, which was still hot when acquired 15 years after the eruptions ceased. The research focuses on (1) the alteration of the basaltic glass into secondary minerals and (2) tiny linear features formed of concentrically oriented secondary minerals. The partial dissolution of glass and its rapid transformation to clay mineral frees constituents that crystallize as zeolite and Al-tobermorite mineral cements. The linear features are composed of clay minerals (nontronite) and zeolite (amicite). Organic carbon-rich matter is associated with their clay mineral layers. These structures differ, however, from those in microtunnels ascribed to biologic activity in older basaltic rocks. The analyses provide a stepping stone toward understanding the earliest basaltic alteration in oceanic environments. Overall, our study demonstrates that basaltic and thereby crustal evolution is a more fast-paced, dynamic process than previously thought.
The 2017 Surtsey Underwater volcanic System for Thermophiles, Alteration processes and INnovative... more 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 Published by Copernicus Publications on behalf of the IODP and the ICDP. 36 M. D. Jackson et al.: SUSTAIN drilling at Surtsey volcano, Iceland 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.
Surtsey, the youngest of the islands of Vestmannaeyjar, is an oceanic volcano created by explosiv... more Surtsey, the youngest of the islands of Vestmannaeyjar, is an oceanic volcano created by explosive basaltic eruptions during 1963-1967 off the southern coast of Iceland. The subsurface deposits of the volcano were first sampled by a cored borehole in 1979. In summer 2017, three cored boreholes were drilled through the active hydrothermal system of the volcano by the International Continental Scientific Drilling Program (ICDP) SUSTAIN Expedition 5059. These cores are expected to provide the first glimpse of microbial life in very young and native basaltic tuff of the oceanic crust. To reduce the contamination of the subsurface environment, seawater circulating fluid was filtered and passed through two UV-sterilizing treatments. One of the boreholes has been equipped with a subsurface observatory dedicated in situ experiments for monitoring water-rock interactions and microbial processes in sterile, artificial basaltic glass and in olivine granules. With temperatures ranging from 25 to 125 • C, the subsurface observatory provides a precise geothermal window into an active hydrothermal system and thus represents an exceptional natural laboratory for studying fluid-rock-microbe interactions at different temperature regimes and facilitates experimental validation of active submarine microbial processes at the limit of functional life, about 121 • C. Comparisons with the 1979 and 2019 drill cores will provide time-lapse observations of hydrothermal processes over a 50-year timescale. Here, we present the technical design of the observatory and the incubation chamber experiments deployed from September 2017 to summer 2019.
Pozzolanic reaction of volcanic ash with hydrated lime is thought to dominate the cementing fabri... more Pozzolanic reaction of volcanic ash with hydrated lime is thought to dominate the cementing fabric and durability of 2000-year-old Roman harbor concrete. Pliny the Elder, however, in first century CE emphasized rock-like cementitious processes involving volcanic ash (pulvis) "that as soon as it comes into contact with the waves of the sea and is submerged becomes a single stone mass (fierem unum lapidem), impregnable to the waves and every day stronger" (Naturalis Historia 35.166). Pozzolanic crystallization of Al-tobermorite, a rare, hydrothermal, calcium-silicate-hydrate mineral with cation exchange capabilities, has been previously recognized in relict lime clasts of the concrete. Synchrotron-based X-ray microdiffraction maps of cementitious microstructures in Baianus Sinus and Portus Neronis submarine breakwaters and a Portus Cosanus subaerial pier now reveal that Al-tobermorite also occurs in the leached perimeters of feldspar fragments, zeolitized pumice vesicles, and in situ phillipsite fabrics in relict pores. Production of alkaline pore fluids through dissolution-precipitation, cation-exchange and/or carbonation reactions with Campi Flegrei ash components, similar to processes in altered trachytic and basaltic tuffs, created multiple pathways to post-pozzolanic phillipsite and Al-tobermorite crystallization at ambient seawater and surface temperatures. Long-term chemical resilience of the concrete evidently relied on water-rock interactions, as Pliny the Elder inferred. Raman spectroscopic analyses of Baianus Sinus Al-tobermorite in diverse microstructural environments indicate a cross-linked structure with Al 3+ substitution for Si 4+ in Q 3 tetrahedral sites, and suggest coupled [Al 3+ +Na + ] substitution and potential for cation exchange. The mineral fabrics provide a geoarchaeological prototype for developing cementitious processes through low-temperature rock-fluid interactions, subsequent to an initial phase of reaction with lime that defines the activity of natural pozzolans. These processes have relevance to carbonation reactions in storage reservoirs for CO 2 in pyroclastic rocks, production of alkali-activated mineral cements in maritime concretes, and regenerative cementitious resilience in waste encapsulations using natural volcanic pozzolans.
The hydrated lime-volcanic ash mortars of imperial age concrete construction in Rome owe their ex... more The hydrated lime-volcanic ash mortars of imperial age concrete construction in Rome owe their extraordinary durability to a specific alteration facies of scoriaceous ash from the Pozzolane Rosse ignimbrite, erupted at 456±3 ka from Alban Hills volcano. Stratigraphic, petrographic, and chemical investigations demonstrate that during the warm, humid period preceding marine isotope stage 11, hydrolytic pedogenesis produced an argillic horizon in Pozzolane Rosse, with thick illuvial clay that had little reactivity with hydrated lime, as shown by mortars from the Forum of Julius Caesar (46 to 44 BC). In the underlying soil horizon, however, translocated halloysite overlies opal and poorly crystalline clay surface coatings. Imperial age mortars, as from the Forum and Markets of Trajan (AD 96 to 115), show strong reactivity of these components, altered scoria groundmass, and zeolites with hydrated lime. Romans deliberately selected this alkali-rich ash for optimal performance of pozzolanic concretes.
eScholarship provides open access, scholarly publishing services to the University of California ... more eScholarship provides open access, scholarly publishing services to the University of California and delivers a dynamic research platform to scholars worldwide.
Petrographic studies of thin sections from the 1979 and 2017 Surtsey drill cores provide new insi... more Petrographic studies of thin sections from the 1979 and 2017 Surtsey drill cores provide new insights into microstructural features in basaltic lapilli tuff sampled from the principal structural and hydrothermal zones of the volcano. These describe narrow rims of fine ash on altered glass pyroclasts in thin sections of the 2017 cores, characteristics of granular and microtubular structures in the original thin sections of the 1979 core, and glass alteration in diverse environments. The narrow ash rims follow the outlines of glass pyroclasts in the subaerial tuff cone and in submarine and sub-seafloor deposits; they suggest complex eruptive and depositional processes. The tubular microstructures resemble endolithic microborings in older oceanic basalt; they suggest possible microbial activity. Tubule lengths indicate rapid growth rates, up to 30 µm in ~15 years. Comparisons of glass alteration in thin sections prepared immediately after drilling in 1979 and 2017 indicate differential...
Programs are presented which calculate angular relations among fault attitude, marker-plane attit... more Programs are presented which calculate angular relations among fault attitude, marker-plane attitude and slip direction, and determine the extension or contraction of the marker by the fault slip. The programs are written both in FORTRAN and in the reverse-Polish language implemented on Hewlett-Packard type hand calculators. Examples of program use are presented.
left-stepping, en echelon ground cracks within the Kaoiki seismic zone, on the southeast flank of... more left-stepping, en echelon ground cracks within the Kaoiki seismic zone, on the southeast flank of Mauna Loa volcano, Hawaii. The general trend of the ruptures, N48ø-55øE, parallels a nodal plane of the main shocks' focal mechanisms. The ruptures themselves consist of short, predominantly extension cracks, which are up to 20 m long and strike roughly E-W, 300-50 ø clockwise from the overall trend of the zones. Some of the cracks are linked by secondary fractures and rubble breccia to form left-stepping crack arrays, which are themselves linked to form longer en echelon systems of ground rupture. Geologic maps and field observations indicate that these features emerge from an underlying strike-slip fault, and they form a "fracture-process zone" above its tip. The maximum displacement measured across cracks in the 1983 rupture zone is 0.5 m. Trilateration data, however, suggests that the overall shear displacement was about 1.5 m at depth. Elastic solutions indicate that a region of significant tensile stress can exist above buried strike-slip faults. We suggest that these stresses generated the extensional ground cracks and that shear displacements were transmitted to the Earth's surface by subsequent growth and linkage of these cracks into the observed arrays. We infer that the crack arrays accommodate increased displacement with depth and they merge downward into the "parent" strike-slip fault at an estimated 1-2 km depth, where strike-slip displacement was probably more or less continuous along the-•7 km length of the rupture. In the Kaoiki region, only three major ground ruptures traverse a series of basaltic lava flows that date back 1500 years. This suggests that the recent-• 10-year periodicity of moderate-magnitude Kaoiki strike-slip events may not have extended far into the past. The tectonic significance of strike-slip faulting on Mauna Loa volcano remains enigmatic.
Colonisation of life on Surtsey has been observed systematically since the formation of the islan... more Colonisation of life on Surtsey has been observed systematically since the formation of the island 50 years ago. Although the first colonisers were prokaryotes, such as bacteria and blue-green algae, most studies have been focusing on settlement of plants and animals but less on microbial succession. To explore microbial colonization in diverse soils and the influence of associate vegetation and birds on numbers of environmental bacteria, we collected 45 samples from different soils types on the surface of the island. Total viable bacterial counts were performed with plate count at 22°, 30° and 37°C for all soils samples and the amount of organic matter and nitrogen (N) was measured. Selected samples were also tested for coliforms, faecal coliforms aerobic and anaerobic bacteria. The deep subsurface biosphere was investigated by collecting liquid subsurface samples from a 182 meters borehole with a special sampler. Correlation was observed between N deficits and the number of microo...
This site lies in the historic core of Beccles, as outlined in the County Historic Environment Re... more This site lies in the historic core of Beccles, as outlined in the County Historic Environment Record (BCC 018). Medieval and later archaeological features were recorded immediately to the north (BCC 025 and Misc.). Urban archaeological deposits have the potential to be relatively complex. No objection in principle but the site will require a planning condition under the NPPF to secure a programme of archaeological investigation. Evaluation at as early a stage as possible is recommended so that costs and timescales for archaeological work can be factored in to project designs. A programme of archaeological work will be required, secured through a planning condition.
Roman hydraulic maritime concretes of the central Italian coast have Flegrean vitric tuff as coar... more Roman hydraulic maritime concretes of the central Italian coast have Flegrean vitric tuff as coarse aggregate and mortar pozzolan. Pozzolanic reaction at high pH produced silica-rich CASH and calcium carbonate cements; tobermorite in the residual cores of lime and vitric tuff clasts; and ettringite and calcium-chloroaluminate in bead-like microstructures and voids. Phillipsite may reflect dissolution of residual alkali-rich volcanic glass at lower pH. The cement systems seem to have remained relatively stable during partial to full immersion in seawater for 2000 years. Further analytical investigations will determine the diverse chemical processes that produced specific cement microstructures.
Micrometer‐scale maps of authigenic microstructures in submarine basaltic tuff from a 1979 Surtse... more Micrometer‐scale maps of authigenic microstructures in submarine basaltic tuff from a 1979 Surtsey volcano, Iceland, drill core acquired 15 years after eruptions terminated describe the initial alteration of oceanic basalt in a low‐temperature hydrothermal system. An integrative investigative approach uses synchrotron source X‐ray microdiffraction, microfluoresence, micro‐computed tomography, and scanning transmission electron microscopy coupled with Raman spectroscopy to create finely resolved spatial frameworks that record a continuum of alteration in glass and olivine. Microanalytical maps of vesicular and fractured lapilli in specimens from 157.1‐, 137.9‐, and 102.6‐m depths and borehole temperatures of 83, 93.9, and 141.3 °C measured in 1980, respectively, describe the production of nanocrystalline clay mineral, zeolites, and Al‐tobermorite in diverse microenvironments. Irregular alteration fronts at 157.1‐m depth resemble microchannels associated with biological activity in ol...
Horace could more accurately have compared the celebrated lifespan of his poems to the extremely ... more Horace could more accurately have compared the celebrated lifespan of his poems to the extremely durable concrete monuments that were being constructed in Rome and the harbors of the Mediterranean region by his patron, Octavian, who would become Emperor Augustus (27 BCE– 14 CE) (Figure 1a–c). Bronzes irreversibly and inexorably decay through chloride corrosion in coastal and marine environments, and Egyptian pyramids are now collapsing—having suffered progressive differential movement and detachment of their limestone blocks, probably through anisotropic thermal expansion of calcite during heating by transit of the sun in the desert and subsequent disruption through seismic ground shaking. I have crafted a monument more lasting than bronze, more imposing than the royal structure of the pyramids, one that neither eroding rain nor the furious North Wind can bring to ruin, nor the passage of countless years and the flight of time.
Comparison of investigations of the 1979 and 2017 cored boreholes coupled with continued observat... more Comparison of investigations of the 1979 and 2017 cored boreholes coupled with continued observations of the dynamic surface of Surtsey has modified our concepts of the subsurface structure of the volcano. A geometrical analysis of the 2017 vertical and inclined cores indicates that near-surface layering dips westerly, indicating that the boreholes are located inside the Surtur crater. In subaerial deposits, as well as in deep deposits below sea level and below the pre-Surtsey seafloor, there are zones of porous tuff that contain abundant pyroclasts with narrow rims of fine ash. These features, typical of near-surface deposits, could have been carried down the vent by downslumping during fluctuating explosive activity. They support the hypothesis that a broad diatreme underlies the Surtur vent. No major intrusions were encountered in the 2017 drilling except for coherent basalt in deep sub-seafloor deposits below the center of Surtur crater. The 2017 borehole temperature measurement...
Surtsey is a young volcanic island in the offshore extension of Iceland's southeast rift zone tha... more Surtsey is a young volcanic island in the offshore extension of Iceland's southeast rift zone that grew from the seafloor during explosive and effusive eruptions in 1963-1967. In 1979, a cored borehole (SE-1) was drilled to 181 m depth and in 2017 three cored boreholes (SE-2a, SE-2b and SE-3) were drilled to successively greater depths. The basaltic deposits host a low-temperature (40-141 °C) seawater-dominated geothermal system. Surtsey provides an ideal environment to study water-rock interaction processes in a young seawater geothermal system. Elemental concentrations (SiO2, B, Na, Ca, Mg, F, dissolved inorganic carbon, SO4, Cl) and isotope contents (δD, δ 18 O) in borehole fluids indicate that associated geothermal waters in submarine deposits originated from seawater modified by reactions with the surrounding basalt. These processes produce authigenic minerals in the basaltic lapilli tuff and a corresponding depletion of certain elements in the residual waters. Coupling of measured and modeled concentrations investigates the effect of temperature and associated abundance of authigenic minerals on chemical fluxes from and to the igneous oceanic crust during lowtemperature alteration. The annual chemical fluxes calculated at 50-150 °C range from-0.01 to +0.1×10 12 mol yr-1 for SiO2, +0.2 to +129×10 12 mol yr-1 for Ca,-129 to-0.8×10 12 mol yr-1 for Mg and-21 to +0.4×10 12 mol yr-1 for SO4 where negative values indicate chemical fluxes from the ocean into the oceanic crust and positive values indicate fluxes from the oceanic crust to the oceans. These flux calculations reveal that water-rock interaction at varying water-rock ratios and temperatures produces authigenic minerals that serve as important sinks of seawaterderived SiO2, Mg and SO4. In contrast, water-rock interaction accompanied by dissolution of 2 basaltic glass and primary crystal fragments, provides a significant source of Ca. Such lowtemperature alteration could effectively influence the elemental budget of the oceanic igneous crust and ocean waters. The modelling provides insights into water chemistries and chemical fluxes in low-temperature MOR recharge zones. Surtsey also provides a valuable young analogue for assessing the chemical evolution of fluid discharge over the life cycles of seamounts in ridge flank systems.
The formation of the oceanic island Surtsey in the shallow ocean off the south coast of Iceland i... more The formation of the oceanic island Surtsey in the shallow ocean off the south coast of Iceland in 1963-1967 remains one of the best-studied examples of basaltic emergent volcanism to date. The island was built by both explosive, phreatomagmatic phases and by effusive activity forming lava shields covering parts of the explosively formed tuff cones. A detailed gravity survey was carried out on Surtsey in July 2014 with a gravity station spacing of~100 m. We analyse these data in order to refine a 2.5D-structural and density model of the internal structure for this type locality of Surtseyan volcanism. We carry out a complete Bouguer correction of these data using total terrain corrections based on detailed DEMs of the island and the submarine bathymetry. The principal components of the island are the two tuff cones composed principally of lapilli tuff; this was originally phreatomagmatic tephra formed in the explosive phases of the eruption. Lapilli tuff can be subdivided into (1) submarine lapilli tuff and (2) lapilli tuff above sea level. Other units are (3) subaerial lava, and (4) subaqueous lava deltas. Minor components that are volumetrically insignificant are small intrusions, and unconsolidated and unaltered tephra, still found in thin layers flanking the tuff cones. An additional formation, relevant for any analysis of the subsurface structure of Surtsey, is (5) the sedimentary rocks making up the seafloor, being at least 100 m thick but probably much thicker. Using measurements of the density of all the above components, and subdividing the island into different units based on its pattern of growth, we specifically attempt to constrain the width and depth of diatreme structures proposed by Moore (1985) and confirmed in the ICDP SUSTAIN drilling of Surtsey in 2017 (Jackson et al., 2019). Our forward modeling is aided by a detailed subdivision of the island into units (1) to (4) based on repeated mapping of the island during 1964-1967.
Journal of Volcanology and Geothermal Research, 2019
The evolution of hydrothermal alteration in glassy and variably palagonitized tuff, erupted as te... more The evolution of hydrothermal alteration in glassy and variably palagonitized tuff, erupted as tephra in 1963-1964 on Surtsey, an island built in the offshore extension of Iceland's southeast rift zone, is documented through a comparative petrographic study of samples from drill cores recovered in 1979 and 2017. Time-lapse alteration within the low-temperature meteoric to seawater dominated hydrothermal system of the volcano is characterized in terms of secondary mineral contents, alteration rates and alteration style with depth. Between 1979 and 2017 palagonitization and cementation by secondary minerals has progressed into previously poorly altered parts of the system, leading to increased consolidation of the basaltic tephra. Alteration rates range between 1.05 and 42.5 μm•yr -1 for palagonitization of glass and 0.4-8.33 μm•yr -1 for pseudomorphic olivine replacement by clay minerals over a temperature interval of 47-140 °C. Five distinct zones of alteration style, distinguished through alteration mineralogy, development of authigenic phases over time, as well as degree of alteration are described. Alteration of basaltic tephra at Surtsey volcano is defined by an early stage of phillipsite and clay mineral formation, followed by a later stage of analcime and tobermorite formation as well as replacement of phillipsite below the water table in zone 2 between 65.4 and 138.4 m. Only minor advancement of alteration is detected in zone 3 between 138.4 and 150.3 m depth, where the primary tephra remains largely unpalagonitized and unconsolidated. In contrast, from 1979 to 2017 alteration has increased between 150.3 and 177.8 m depth, in zone 4, leading to rapid and extensive glass and olivine alteration. The quantification of these time-lapse hydrothermal alteration processes at Surtsey provides an important reference for studies of the evolution of young oceanic islands hosting hydrothermal systems.
Micrometer-scale maps of authigenic microstructures in submarine basaltic tuff from a 1979 Surtse... more Micrometer-scale maps of authigenic microstructures in submarine basaltic tuff from a 1979 Surtsey volcano, Iceland, drill core acquired 15 years after eruptions terminated describe the initial alteration of oceanic basalt in a low-temperature hydrothermal system. An integrative investigative approach uses synchrotron source X-ray microdiffraction, microfluoresence, micro-computed tomography, and scanning transmission electron microscopy coupled with Raman spectroscopy to create finely resolved spatial frameworks that record a continuum of alteration in glass and olivine. Microanalytical maps of vesicular and fractured lapilli in specimens from 157.1-, 137.9-, and 102.6-m depths and borehole temperatures of 83, 93.9, and 141.3°C measured in 1980, respectively, describe the production of nanocrystalline clay mineral, zeolites, and Al-tobermorite in diverse microenvironments. Irregular alteration fronts at 157.1-m depth resemble microchannels associated with biological activity in older basalts. By contrast, linear microstructures with little resemblance to previously described alteration features have nanocrystalline clay mineral (nontronite) and zeolite (amicite) texture. The crystallographic preferred orientation rotates around an axis parallel to the linear feature. Raman spectra indicating degraded and poorly ordered carbonaceous matter of possible biological origin are associated with nanocrystalline clay mineral in a crystallographically oriented linear microstructure in altered olivine at 102.6 m and with subcircular nanoscale cavities in altered glass at 137.9-m depth. Although evidence for biotic processes is inconclusive, the integrated analyses describe the complex organization of previously unrecognized mineral texture in very young basalt. They provide a foundational mineralogical reference for longitudinal, time-lapse characterizations of palagonitized basalt in oceanic environments. Plain Language Summary The thermal, chemical, and mineralogical evolution of basaltic rocks and the physical properties Earth's oceanic and continental crust are fundamentally linked. To better understand the evolution of basalt alteration over short geologic timescales, we turn to a newly formed volcanic island, Surtsey, in southern Iceland. The analyzed samples are composed of glassy basaltic fragments, created by explosive interactions between magma and seawater. They come from drill core collected in 1979, which was still hot when acquired 15 years after the eruptions ceased. The research focuses on (1) the alteration of the basaltic glass into secondary minerals and (2) tiny linear features formed of concentrically oriented secondary minerals. The partial dissolution of glass and its rapid transformation to clay mineral frees constituents that crystallize as zeolite and Al-tobermorite mineral cements. The linear features are composed of clay minerals (nontronite) and zeolite (amicite). Organic carbon-rich matter is associated with their clay mineral layers. These structures differ, however, from those in microtunnels ascribed to biologic activity in older basaltic rocks. The analyses provide a stepping stone toward understanding the earliest basaltic alteration in oceanic environments. Overall, our study demonstrates that basaltic and thereby crustal evolution is a more fast-paced, dynamic process than previously thought.
The 2017 Surtsey Underwater volcanic System for Thermophiles, Alteration processes and INnovative... more 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 Published by Copernicus Publications on behalf of the IODP and the ICDP. 36 M. D. Jackson et al.: SUSTAIN drilling at Surtsey volcano, Iceland 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.
Surtsey, the youngest of the islands of Vestmannaeyjar, is an oceanic volcano created by explosiv... more Surtsey, the youngest of the islands of Vestmannaeyjar, is an oceanic volcano created by explosive basaltic eruptions during 1963-1967 off the southern coast of Iceland. The subsurface deposits of the volcano were first sampled by a cored borehole in 1979. In summer 2017, three cored boreholes were drilled through the active hydrothermal system of the volcano by the International Continental Scientific Drilling Program (ICDP) SUSTAIN Expedition 5059. These cores are expected to provide the first glimpse of microbial life in very young and native basaltic tuff of the oceanic crust. To reduce the contamination of the subsurface environment, seawater circulating fluid was filtered and passed through two UV-sterilizing treatments. One of the boreholes has been equipped with a subsurface observatory dedicated in situ experiments for monitoring water-rock interactions and microbial processes in sterile, artificial basaltic glass and in olivine granules. With temperatures ranging from 25 to 125 • C, the subsurface observatory provides a precise geothermal window into an active hydrothermal system and thus represents an exceptional natural laboratory for studying fluid-rock-microbe interactions at different temperature regimes and facilitates experimental validation of active submarine microbial processes at the limit of functional life, about 121 • C. Comparisons with the 1979 and 2019 drill cores will provide time-lapse observations of hydrothermal processes over a 50-year timescale. Here, we present the technical design of the observatory and the incubation chamber experiments deployed from September 2017 to summer 2019.
Pozzolanic reaction of volcanic ash with hydrated lime is thought to dominate the cementing fabri... more Pozzolanic reaction of volcanic ash with hydrated lime is thought to dominate the cementing fabric and durability of 2000-year-old Roman harbor concrete. Pliny the Elder, however, in first century CE emphasized rock-like cementitious processes involving volcanic ash (pulvis) "that as soon as it comes into contact with the waves of the sea and is submerged becomes a single stone mass (fierem unum lapidem), impregnable to the waves and every day stronger" (Naturalis Historia 35.166). Pozzolanic crystallization of Al-tobermorite, a rare, hydrothermal, calcium-silicate-hydrate mineral with cation exchange capabilities, has been previously recognized in relict lime clasts of the concrete. Synchrotron-based X-ray microdiffraction maps of cementitious microstructures in Baianus Sinus and Portus Neronis submarine breakwaters and a Portus Cosanus subaerial pier now reveal that Al-tobermorite also occurs in the leached perimeters of feldspar fragments, zeolitized pumice vesicles, and in situ phillipsite fabrics in relict pores. Production of alkaline pore fluids through dissolution-precipitation, cation-exchange and/or carbonation reactions with Campi Flegrei ash components, similar to processes in altered trachytic and basaltic tuffs, created multiple pathways to post-pozzolanic phillipsite and Al-tobermorite crystallization at ambient seawater and surface temperatures. Long-term chemical resilience of the concrete evidently relied on water-rock interactions, as Pliny the Elder inferred. Raman spectroscopic analyses of Baianus Sinus Al-tobermorite in diverse microstructural environments indicate a cross-linked structure with Al 3+ substitution for Si 4+ in Q 3 tetrahedral sites, and suggest coupled [Al 3+ +Na + ] substitution and potential for cation exchange. The mineral fabrics provide a geoarchaeological prototype for developing cementitious processes through low-temperature rock-fluid interactions, subsequent to an initial phase of reaction with lime that defines the activity of natural pozzolans. These processes have relevance to carbonation reactions in storage reservoirs for CO 2 in pyroclastic rocks, production of alkali-activated mineral cements in maritime concretes, and regenerative cementitious resilience in waste encapsulations using natural volcanic pozzolans.
The hydrated lime-volcanic ash mortars of imperial age concrete construction in Rome owe their ex... more The hydrated lime-volcanic ash mortars of imperial age concrete construction in Rome owe their extraordinary durability to a specific alteration facies of scoriaceous ash from the Pozzolane Rosse ignimbrite, erupted at 456±3 ka from Alban Hills volcano. Stratigraphic, petrographic, and chemical investigations demonstrate that during the warm, humid period preceding marine isotope stage 11, hydrolytic pedogenesis produced an argillic horizon in Pozzolane Rosse, with thick illuvial clay that had little reactivity with hydrated lime, as shown by mortars from the Forum of Julius Caesar (46 to 44 BC). In the underlying soil horizon, however, translocated halloysite overlies opal and poorly crystalline clay surface coatings. Imperial age mortars, as from the Forum and Markets of Trajan (AD 96 to 115), show strong reactivity of these components, altered scoria groundmass, and zeolites with hydrated lime. Romans deliberately selected this alkali-rich ash for optimal performance of pozzolanic concretes.
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