All ICDP Publications with Abstracts
From parent-sysfolder "Publications" + 2 folder-levels deep
2019.
Petrophysical, Geochemical, and Hydrological Evidence for Extensive Fracture-Mediated Fluid and Heat Transport in the Alpine Fault's Hanging-Wall Damage Zone
Geochemistry, Geophysics, Geosystems,
18
(12)
4709 – 4732
2017
ISSN: 15252027
Publisher: Blackwell Publishing Ltd
Keywords:▾
Earthquakes; Fracture; Geophysics; Groundwater; Hydrogeology; Topography; Transport properties, Damage zones; Earthquake rupture process; Fault zone; Petrophysical datum; Petrophysics; Seismogenesis; Spatial and temporal scale; Strain accumulations, Faulting, coseismic process; earthquake rupture; exhumation; fault zone; heat transfer; hydrogeology; petrochemistry; seismogram; topography, Alpine Fault Zone; New Zealand; South Island
Abstract: ▾ Fault rock assemblages reflect interaction between deformation, stress, temperature, fluid, and chemical regimes on distinct spatial and temporal scales at various positions in the crust. Here we interpret measurements made in the hanging-wall of the Alpine Fault during the second stage of the Deep Fault Drilling Project (DFDP-2). We present observational evidence for extensive fracturing and high hanging-wall hydraulic conductivity (∼10−9 to 10−7 m/s, corresponding to permeability of ∼10−16 to 10−14 m2) extending several hundred meters from the fault's principal slip zone. Mud losses, gas chemistry anomalies, and petrophysical data indicate that a subset of fractures intersected by the borehole are capable of transmitting fluid volumes of several cubic meters on time scales of hours. DFDP-2 observations and other data suggest that this hydrogeologically active portion of the fault zone in the hanging-wall is several kilometers wide in the uppermost crust. This finding is consistent with numerical models of earthquake rupture and off-fault damage. We conclude that the mechanically and hydrogeologically active part of the Alpine Fault is a more dynamic and extensive feature than commonly described in models based on exhumed faults. We propose that the hydrogeologically active damage zone of the Alpine Fault and other large active faults in areas of high topographic relief can be subdivided into an inner zone in which damage is controlled principally by earthquake rupture processes and an outer zone in which damage reflects coseismic shaking, strain accumulation and release on interseismic timescales, and inherited fracturing related to exhumation. © 2017. American Geophysical Union. All Rights Reserved.
2018.
Pore fluids in Dead Sea sediment core reveal linear response of lake chemistry to global climate changes
Geology,
45
(4)
315-318
2017
ISSN: 00917613
Publisher: Geological Society of America
DOI:10.1130/G38685.1
Keywords:▾
Atmospheric temperature; Bromine; Carbon dioxide; Climate change; Drilling fluids; Glacial geology; Magnesium; Oceanography; Submarine geophysics; Surface properties; Surface waters, Chemical variations; Continental scientific drillings; Global climate changes; Hydrological changes; Interglacial periods; Last glacial terminations; Marine isotope stages; Sea surface temperature (SST), Lakes, climate variation; Last Glacial; paleoclimate; porewater; precipitation (climatology); sediment core; water budget; water chemistry, Dead Sea
Abstract: ▾ Pore fluids extracted from a 456 m sediment core, recovered within the framework of a multinational and International Continental Scientific Drilling Program (ICDP) co-sponsored effort at the bottom of the terminal Dead Sea, recorded the chemical variations in the deep lake over the past 220 k.y. Mg2+ and Br- were shown to be conservative in the pore fluids, increasing in concentration during interglacial periods, diluting during glacials, and providing excellent proxies for deep lake net water balance changes. Furthermore, the Na/Cl ratio recorded the process of halite precipitation and dissolution induced by these hydrological changes. Mg2+ and Br- records follow a glacialinterglacial pattern, such as observed in atmospheric CO2 concentrations and global sea-surface temperatures, albeit with a phase offset. At the end of the last interglacial (ca. 116 ka), there is a delay in onset of dilution of the deep lake, most likely due to the limnological transition from holomictic to meromictic conditions. The increase in deep lake concentrations at Last Glacial Termination I is delayed as a result of freshwater input into the deep lake during the cooler Younger Dryas period. There is a persistent relationship between precipitation in the watershed and North Atlantic sea-surface temperatures, similar to conditions observed over the past instrumental record. Deviations from the long-term trends occurred during interglacial periods, Marine Isotope Stages MIS 5e and MIS 1, when the deep Dead Sea was significantly diluted, and coincided with Mediterranean sapropel layers S5 and S1. © 2017 The Authors.
2017.
Seismological evidence of fault weakening due to erosion by fluids from observations of intraplate earthquake swarms
Journal of Geophysical Research: Solid Earth,
122
(5)
3701 – 3718
2017
ISSN: 21699313
Publisher: Blackwell Publishing Ltd
Keywords:▾
Bohemia; Czech Republic; earthquake swarm; erosion; fault; fluid pressure; hydrothermal fluid; intraplate process; microearthquake; moment tensor; seismology
Abstract: ▾ The occurrence and specific properties of earthquake swarms in geothermal areas are usually attributed to a highly fractured rock and/or heterogeneous stress within the rock mass being triggered by magmatic or hydrothermal fluid intrusion. The increase of fluid pressure destabilizes fractures and causes their opening and subsequent shear-tensile rupture. The spreading and evolution of the seismic activity are controlled by fluid flow due to diffusion in a permeable rock (fluid-diffusion model) and/or by redistribution of Coulomb stress (intrusion model). These models, however, are not valid universally. We provide evidence that none of these models is consistent with observations of swarm earthquakes in West Bohemia, Czech Republic. Full seismic moment tensors of microearthquakes in the 2008 swarm in West Bohemia indicate that fracturing at the starting phase of the swarm was not associated with fault openings caused by pressurized fluids but rather with fault compactions. This can physically be explained by a fault-weakening model, when the essential role in the swarm triggering is attributed to degradation of fault strength due to long-lasting chemical and hydrothermal fluid-rock interactions in the focal zone. Since the rock is exposed to circulating hydrothermal, CO2-saturated fluids, the walls of fractures are weakened by dissolving and altering various minerals. The porosity of the fault gauge increases, and the fault weakens. If fault strength lowers to a critical value, the seismicity is triggered. The fractures are compacted during failure, the fault strength recovers, and a new cycle begins. ©2017. American Geophysical Union. All Rights Reserved.
2016.
Lake Lisan: The Archive of the Last Glacial Levant's Hydroclimatology
In Enzel, Yehouda and Bar-Yosef, OferEditors,
Editor
Page 107–114
Publisher
Cambridge University Press
2017
107–1142015.
Structural characteristics of the Lake Van Basin, eastern Turkey, from high-resolution seismic reflection profiles and multibeam echosounder data: geologic and tectonic implications
International Journal of Earth Sciences,
106
(1)
239-253
2017
ISSN: 14373254
Publisher: Springer Verlag
Keywords:▾
basin evolution; compression; extensional tectonics; mantle upwelling; seismic data; seismic reflection; spectral resolution; volcanism, Lake Van; Turkey
Abstract: ▾ The structural evolution of Lake Van Basin, eastern Turkey, was reconstructed based on seismic reflection profiles through the sedimentary fill as well as from newly acquired multibeam echosounder data. The major sub-basins (Tatvan Basin and Northern Basin) of Lake Van, bound by NE-trending faults with normal components, formed during the past ~600 ka probably due to extensional tectonics resulting from lithospheric thinning and mantle upwelling related to the westward escape of Anatolia. Rapid extension and subsidence during early lake formation led to the opening of the two sub-basins. Two major, still active volcanoes (Nemrut and Süphan) grew close to the lake basins approximately synchronously, their explosive deposits making up >20 % of the drilled upper 220 m of the ca. 550-m-thick sedimentary fill. During basin development, extension and subsidence alternated with compressional periods, particularly between ~340 and 290 ka and sometime before ~14 ka, when normal fault movements reversed and gentle anticlines formed as a result of inversion. The ~14 ka event was accompanied by widespread uplift and erosion along the northeastern margin of the lake, and substantial erosion took place on the crests of the folds. A series of closely spaced eruptions of Süphan volcano occurred synchronously suggesting a causal relationship. Compression is still prevalent inside and around Lake Van as evidenced by recent faults offsetting the lake floor and by recent devastating earthquakes along their onshore continuations. New, high-resolution bathymetry data from Lake Van reveal the morphology of the Northern Ridge and provide strong evidence for ongoing transpression on a dextral strike-slip fault as documented by the occurrence of several pop-up structures along the ridge. © 2016, Springer-Verlag Berlin Heidelberg.
2014.
[English]
Seismic facies characterization of the overdeepened glacial tannwald basin
Publisher
European Association of Geoscientists and Engineers, EAGE
2017
Liang, SwedenKeywords:▾
Fertilizers; Seismic waves; Seismology; Shear waves, Drill sites; High resolution; Internal features; Multicomponents; P waves; S-waves; Seismic facies; Vibroseis, Infill drilling
ISBN:
9789462822238
2013.
VS of the uppermost crust structure of the Campi Flegrei caldera (southern Italy) from ambient noise Rayleigh wave analysis
Journal of Volcanology and Geothermal Research,
347278 – 295
2017
ISSN: 03770273
Publisher: Elsevier B.V.
Keywords:▾
Campania [Italy]; Campi Flegrei; Italy; Napoli [Campania]; Acoustic noise; Group velocity dispersion; Landforms; Rayleigh waves; Shear waves; Velocity; Cross correlations; Fundamental modes; Group velocity dispersion curve; Neapolitan yellow tuffs; Non linear inversion; Pyroclastic soils; Seismic station; Shear wave velocity; ambient noise; caldera; correlation; crustal structure; drilling; Rayleigh wave; S-wave; seismic velocity; tuff; Shear flow
Abstract: ▾ Shear wave velocities (VS) are defined in the uppermost 1–2 km of the Campi Flegrei caldera through the non-linear inversion of the group velocity dispersion curves of fundamental-mode Rayleigh waves extracted from ambient noise cross-correlations between two receivers. Noise recordings, three months long, at 12 seismic stations are cross-correlated between all couples of stations. The experiment provided successful results along 54 paths (inter-stations distance), of which 27 sampled a depth > 1 km. VS contour lines are drawn from 0.06 km b.s.l. to 1 km depth b.s.l. and show difference between the offshore (gulf of Pozzuoli and coastline) and the onshore areas. At 0.06 km b.s.l., the gulf of Pozzuoli and the coastline are characterized by VS of 0.3–0.5 km/s and of 0.5–0.7 km/s, respectively. Such velocities are typical of Neapolitan pyroclastic soils and fractured or altered tuffs. The inland shows VS in the range 0.7–0.9 km/s, typical of Neapolitan compact tuffs. Velocities increase with depth and, at 1 km depth b.s.l., velocities lower than 1.5 km/s are still present in the gulf and along the coastline while velocities higher than 1.9 km/s characterize the eastern sector (grossly coincident with the Neapolitan Yellow Tuff caldera rim), the S. Vito plain and the area between Solfatara and SW of Astroni. Such features are much more evident along two cross-sections drawn in the offshore and onshore sectors by integrating our VS models with literature data. Our models join previous noise cross-correlation studies at greater scale at depths of 0.7–0.8 km, hence the picture of the Campi Flegrei caldera is shown up to a depth of 15 km. VS of about 1.7 km/s, corresponding to compression velocities (VP) of about 3 km/s (computed by using the VP/VS ratio resulted in the inversion), are found at depths of 1.1 km, in the centre of the gulf of Pozzuoli, and at a depth of about 0.7 km b.s.l. onshore. An increment of VS velocity (~ 1.9–2.0 km/s) is locally observed onshore which might be attributed to a layer of tuffs and tuffites interbedded with thin lava beds, according to the correlation of VS with stratigraphies in the deep drillings of S. Vito. © 2017 Elsevier B.V.
2012.
[English]
Drilling into seismogenic zones of M2.0 – M5.5 earthquakes from deep South African gold mines (DSeis): establishment of research sites
Volume 2017-October
,
Page 237 – 248
Publisher
International Society for Rock Mechanics
2017
Ritsumeikan University, Kusatsu, Japan; University of the Witwatersrand, Johannesburg, South Africa; Tohoku University, Japan; Institute of Mine Seismology Ltd, South Africa; Council for Geoscience, South Africa; Fukada Geology Institute, Japan; ETH, Switzerland; Seismogen CC, South Africa; Anglogold Ashanti, South Africa; University of New Hampshire, United States; University of Western Australia, Australia; Stanford University, United States; Independent consultant, South Africa; Tel Aviv University, Israel; Princeton University, United StatesISBN:
978-192041099-5
2011.
[English]
Geothermal Play Fairway Analysis of the Snake River plain: Phase 2
Volume 41
,
Page 2328-2345
Publisher
Geothermal Resources Council
2017
Utah State University, Logan, UT, United States; US Geological Survey, Menlo Park, CA, United States; DOSECC Exploration Services, Salt Lake City, UT, United States; Leidos, San Diego, CA, United States; Boise State University, Boise, ID, United States; Lawrence Berkeley National Laboratory, Berkeley, CA, United States; Idaho National Laboratory, Idaho Falls, ID, United States; National Renewable Energy Lab (NREL), Golden, CO, United StatesISBN:
0934412227
2010.
[English]
Passive seismic imaging of structure discontinuities around the active fault using scattered earthquake waveforms
Publisher
European Association of Geoscientists and Engineers, EAGE
2017
University of Science and Technology of China, ChinaKeywords:▾
Petroleum industry; Seismic waves; Shear waves; Strike-slip faults; Structural geology, Earthquake waveforms; Image Structures; Oil/gas industry; San Andreas fault; Scattering imaging; Seismic networks; Seismic tomography; Seismically active faults, Earthquakes
ISBN:
9789462822191
2009.
[English]
Predicting uniaxial compressive strength from empirical relationships between ultrasonic P-wave velocities, porosity, and core measurements in a potential geothermal reservoir, Snake River Plain, Idaho
Volume 2
,
Page 1474-1482
Publisher
American Rock Mechanics Association (ARMA)
2017
Occidental Petroleum Corporation, Houston, TX, United States; University of Alberta, Edmonton, Canada; Utah State University, Logan, UT, United StatesISBN:
9781510857582
2008.
[English]
Preliminary description of rocks and alteration in IDDP-2 drill core samples recovered from the Reykjanes geothermal system, Iceland
Volume 41
,
Page 1599 – 1615
Publisher
Geothermal Resources Council
2017
Department of Earth and Planetary Sciences, University of California, Davis, CA, United States; HS Orka, Orkubraut 3, Svartsengi, Grindavík, 240, Iceland; Department of Earth Sciences, University of California, Riverside, CA, United States; ÍSOR (Iceland GeoSurvey), Grensávegur 9, Reykjavík, 108, IcelandISBN:
0934412227
2007.
[English]
Successful drilling for supercritical geothermal resources at Reykjanes in SW Iceland
Volume 41
,
Page 1095 – 1107
Publisher
Geothermal Resources Council
2017
HS Orka, Orkubraut 3, Svartsengi, Grindavík, 240, Iceland; Dept. of Earth Sciences, University of California, Riverside, CA 92521, United StatesISBN:
0934412227
2006.
Variations of seismic b-value at different stages of the seismic cycle along the North Anatolian Fault Zone in northwestern Turkey
Tectonophysics,
712-713232-248
2017
ISSN: 00401951
Publisher: Elsevier B.V.
Keywords:▾
Geophysics; Physics, B value; B-value analysis; Damage distribution; Data discretization; North Anatolian Fault Zone; Northwestern Turkey; Sea of Marmara; Turkey, Seismology, earthquake catalogue; earthquake hypocenter; earthquake magnitude; earthquake rupture; fault zone; seismicity; spatiotemporal analysis, Anatolia; Sea of Marmara; Turkey
Abstract: ▾ We studied spatiotemporal b-value variations along the North Anatolian Fault Zone (NAFZ) in northwestern Turkey with a focus on the combined 1999 Izmit and Düzce rupture and the eastern Sea of Marmara. We used a local seismicity catalog of the Izmit-Düzce region covering a time span from 2.5 years prior to the Izmit until 14 months after the Düzce mainshock and a four-year hypocenter catalog in the eastern Sea of Marmara. We consistently calculated moment magnitudes to ensure a homogeneous dataset and applied strict quality criteria. This allows studying variations of b-values throughout the region and at different stages of the seismic cycle. With a standard gridding technique b-value maps, depth sections and time series were calculated which reveal a very heterogeneous b-value distribution in the study area. The variety of b-value observations cannot be interpreted unambiguously, given that the b-value most likely depends on a combination of fault-zone characteristics like local stress conditions, heterogeneity of the crust and damage distribution. By presenting a comprehensive set of possible interpretations we point out that a biased discussion of the results towards stress or another individual parameter may lead to erroneous conclusions. Furthermore, the applied data discretization scheme influences the appearance of the final b-value distribution leading to potential misinterpretations. © 2017 Elsevier B.V.
2005.
The drilling of RN-15/IDDP-2 research well at Reykjanes In sw Iceland
Volume 41
,
Page 512 – 522
2017
2004.
Chronologies of Late Quaternary Coral Reefs and Lake Sediments from the Red Sea and Dead Sea Rift Valley
In Enzel, Yehouda and Bar-Yosef, OferEditors,
Editor
Page 75–82
Publisher
Cambridge University Press
2017
75–822003.
Dead Sea Lake Level Changes and Levant Palaeoclimate
In Enzel, Yehouda and Bar-Yosef, OferEditors,
Editor
Page 115–126
Publisher
Cambridge University Press
2017
115–1262002.
Sedimentology of the Lacustrine Formations in the Dead Sea Basin
In Enzel, Yehouda and Bar-Yosef, OferEditors,
Editor
Page 83–90
Publisher
Cambridge University Press
2017
83–902001.
The Amora Formation, Dead Sea Basin
In Enzel, Yehouda and Bar-Yosef, OferEditors,
Editor
Page 91–98
Publisher
Cambridge University Press
2017
91–982000.
The Stratigraphy and Chronology of the Samra Formation
In Enzel, Yehouda and Bar-Yosef, OferEditors,
Editor
Page 99–106
Publisher
Cambridge University Press
2017
99–1061999.
Volcanic-sedimentary succession description of the Lower Cretaceous Yingcheng Formation based on the ICDP scientific drilling borehole in the Songliao Basin (SK-2)
Earth Science Frontiers,
24
(1)
265-275
2017
ISSN: 10052321
Publisher: Science Frontiers editorial department
Keywords:▾
Boring; Explosives; Rock drilling; Rocks; Sandstone; Sedimentology; Volcanic rocks; Volcanoes, Aptian to Albian; Sedimentary facies; Songliao basin; Volcanic facies; Volcanic-sedimentary succession and cycle; Yingcheng Formation, Sedimentary rocks
Abstract: ▾ China Cretaceous Continental Scientific Drilling in the Songliao Basin, called SK2 project, has collected 365.32 m of the lower Cretaceous Yingcheng Formation whose age is estimated as Aptian-Albian. The borehole got a highly continuous core section with recovery of 98.47%, which is the most complete and precise geological records up to now for the stratum of continental non-marine Cretaceous in the world. The diameter of core is 214 mm which is among the largest diameter concerning coring engineering. We first described the volcanic-sedimentary succession in centimeter scale and studied the volcanic and sedimentary facies. Considering the sedimentary and volcanic rocks as a whole sequence, we recognized seventeen rock types from drilling core of the Yingcheng Formation. There are nine types of sedimentary rocks, including conglomerate, coarse sandstone, medium sandstone, fine sandstone, siltstone, silty mudstone, mudstone, breccia tuffaceous sandstone, and breccia-bearing tuffaceous sandstone. There are eight types of volcanic rocks including rhyolite, rhyolitic tuff/pyroclastics/agglomerate, rhyolitic welded tuff, crypto-explosive breccia, andesitic tuff, and tuffite. Sedimentary facies is fan delta dominant which includes five sedimentary microfacies of distributary channels, back swamp between delta, subaqueous distributary channels, subaqueous mouth bar and mudstone of still water. Volcanic facies are explosive facies and effusive facies dominant, which include four volcanic subfacies of air-fall, pyroclastic flow deposits, middle and upper flow subfacies of the effusive one. According to detailed description of the Yingcheng sequence, we first recognized three periodic sedimentary and volcanic cycles in the Yingcheng Formation, which have been numbered sedimentary I-volcanic I, sedimentary II-volcanic II, and sedimentary III-volcanic III in ascending order. This is a new discovery concerning the vertical features of of the Yingcheng Formation. The centimeter scale description on the core sections from the SK2 may provide some other useful information for related researches in the future. © 2017, Editorial Office of Earth Science Frontiers. All right reserved.
1998.
Variability in landscape and lake system responses to glacial and interglacial climates during the Middle Pleistocene based on palynological and geochemical data from Lake El'gygytgyn, Eastern Arctic
Review of Palaeobotany and Palynology,
2461 – 13
2017
1997.
Terrestrial biota and climate during Cretaceous greenhouse in NE China
Earth Science Frontiers,
24
(1)
18 – 31
2017
ISSN: 10052321
Publisher: Science Frontiers editorial department
Keywords:▾
Carbon; Coal deposits; Lakes; Lead; Organic carbon; Petroleum deposits; Silicate minerals; Stratigraphy; Volcanic rocks; Cretaceous; Elemental compositions; NE China; Oceanic Anoxic Event; Organic carbon burial; Paleoclimates; Planktic foraminifera; Terrestrial biota; Climate change
Abstract: ▾ Northeast China offers a unique opportunity to perceive Cretaceous stratigraphy and climate of terrestrial settings. The sediments contain variegated clastic and volcanic rocks, diverse terrestrial fossils, and important coal and oil resources. Four Cretaceous biotas of Jehol, Fuxin, Songhuajiang and Jiayin occurred in ascending order. For scientific purpose, a coring program (SK1) provides significant material for Cretaceous research. The SK1 presents a continuous section of Upper Cretaceous non-marine fossils, magnetochron successions and chronostratigraphic events. These events are integrated with marine events by an X/Y graphic plot between the core data and a global database of GSSP and key reference sections. More precisely, age interpolation based on CA-ID-TIMS U-Pb zircon dates and the calibrated cyclostratigraphy places the end of the Cretaceous Normal Superchon at 83.07±0.15 Ma. This date also serves as an estimate for the Santonian-Campanian stage boundary. It also places the K/Pg boundary within the upper part of the Mingshui Formation. The terrestrial and marine life and the analysis of elemental composition, δ13Corg, biomarkers show that lake water salinity changed along with a Coniacian-Santonian marine incursion. High lake-level coincides with the sea transgression during the time. High salinity resulted in the development of periodic anoxic environments of the basin. One of these times of deposition of organic-rich mud correlates with the magnetochron of C34n/C33r and Coniacian-Santonian planktic foraminifera. This marine flooding correlates with OAE 3 and it is possible that the global oceanic anoxic event may have influenced organic carbon burial in the Songliao Basin for this brief period. The evolution of 4 biotas corresponds to the Cretaceous climate change. We tentatively interpret the terrestrial record to reflect the changes in both global climate and regional basin evolution. © 2017, Editorial Office of Earth Science Frontiers. All right reserved.
1996.
The Iceland Deep Drilling Project 4.5 km deep well, IDDP-2, in the seawater-recharged Reykjanes geothermal field in SW Iceland has successfully reached its supercritical target
Scientific Drilling,
231-12
2017
ISSN: 18168957
Publisher: Copernicus GmbH
Keywords:▾
Drilling fluids; Economics; Geothermal energy; Geothermal fields; Geothermal wells; Seawater; Thermodynamic properties, Bottom hole temperatures; Formation temperature; Geothermal resources; Hydrothermal system; Iceland deep drilling projects; Supercritical condition; Supercritical hydrothermal; Total circulation loss, Rhenium compounds
Abstract: ▾ The Iceland Deep Drilling Project research well RN-15/IDDP-2 at Reykjanes, Iceland, reached its target of supercritical conditions at a depth of 4.5 km in January 2017. After only 6 days of heating, the measured bottom hole temperature was 426 °C, and the fluid pressure was 34MPa. The southern tip of the Reykjanes peninsula is the landward extension of the Mid-Atlantic Ridge in Iceland. Reykjanes is unique among Icelandic geothermal systems in that it is recharged by seawater, which has a critical point of 406 °C at 29.8MPa. The geologic setting and fluid characteristics at Reykjanes provide a geochemical analog that allows us to investigate the roots of a mid-ocean ridge submarine black smoker hydrothermal system. Drilling began with deepening an existing 2.5 km deep vertical production well (RN-15) to 3 km depth, followed by inclined drilling directed towards the main upflow zone of the system, for a total slant depth of 4659m (~4.5 km vertical depth). Total circulation losses of drilling fluid were encountered below 2.5 km, which could not be cured using lost circulation blocking materials or multiple cement jobs. Accordingly, drilling continued to the total depth without return of drill cuttings. Thirteen spot coring attempts were made below 3 km depth. Rocks in the cores are basalts and dolerites with alteration ranging from upper greenschist facies to amphibolite facies, suggesting that formation temperatures at depth exceed 450 °C. High-permeability circulation-fluid loss zones (feed points or feed zones) were detected at multiple depth levels below 3 km depth to bottom. The largest circulation losses (most permeable zones) occurred between the bottom of the casing and 3.4 km depth. Permeable zones encountered below 3.4 km accepted less than 5% of the injected water. Currently, the project is attempting soft stimulation to increase deep permeability. While it is too early to speculate on the energy potential of this well and its economics, the IDDP-2 is a milestone in the development of geothermal resources and the study of hydrothermal systems. It is the first well that successfully encountered supercritical hydrothermal conditions, with potential high-power output, and in which on-going hydrothermal metamorphism at amphibolite facies conditions can be observed. The next step will be to carry out flow testing and fluid sampling to determine the chemical and thermodynamic properties of the formation fluids. © Author(s) 2017.
1995.
THE CAMPI FLEGREI DEEP DRILLING PROJECT (CFDDP): CALDERA STRUCTURE AND HAZARD
International Journal of Safety and Security Engineering,
7
(3)
443 – 448
2017
ISSN: 20419031
Publisher: WITPress
Keywords:▾
Campania [Italy]; Campi Flegrei; Italy; Napoli [Campania]; Deposits; Geochronology; Hazards; Stratigraphy; Tectonics; Volcanoes; Caldera-forming eruption; Campi Flegrei; Collapse mechanism; Neapolitan yellow tuffs; Scientific drilling; Tectonic evolution; Tectonic structure; Volcanic hazards; caldera; collapse; dating method; geochronology; hazard; metropolitan area; project assessment; reconstruction; tectonic evolution; tectonic structure; volcanic eruption; Infill drilling
Abstract: ▾ The recent investigation carried out on the west bound of the Naples metropolitan area and inside the Campi Flegrei caldera as part of the Campi Flegrei Deep Drilling Project provided new insight in order to reconstruct the volcano-tectonic evolution of this extremely populated area. Campi Flegrei represents the highest risk volcanic areas in the world, although its volcano-tectonic structure, eruptive history and eruptive style of the largest eruptions are intensely debatedby scientists since several decades. We present here a summary of stratigraphic and geochronological dating (40Ar/39Ar) allowing to define the age of intra-caldera deposits belonging to the two highest magnitude caldera-forming eruptions (i.e. Campania Ignimbrite, 39÷40 ka, and Neapolitan Yellow Tuff, 14.9 ka) and to evaluate the amount of collapse of the eastern sector of the caldera. These results point out: (i) a reduction of the area affected by caldera collapse, which appears to not include the city of Naples; (ii) a small volume of the infilling caldera deposits, particularly for the CI; and (iii) the need for reassessment of the collapse amounts and mechanisms related to larger eruptions. Our results also imply a revaluation of volcanic risk for the eastern caldera area, including the city of Naples. The results of this study point out that large calderas are characterised by complex collapse mechanisms and dynamics, whose understanding needs more robust constraints, which can be obtained from scientific drilling. © 2017 WIT Press,