This file was created by the TYPO3 extension publications --- Timezone: CEST Creation date: 2026-06-03 Creation time: 06:07:20 --- Number of references 13 article Heesakkers20112395 We analyze the structure of the Archaean Pretorius fault in TauTona mine, South Africa, as well as the rupture-zone that recently reactivated it. The analysis is part of the Natural Earthquake Laboratory in South African Mines (NELSAM) project that utilizes the access to 3. 6 km depth provided by the mining operations. The Pretorius fault is a ~10 km long, oblique-strike-slip fault with displacement of up to 200 m that crosscuts fine to very coarse grain quartzitic rocks in TauTona mine. We identify here three structural zones within the fault-zone: (1) an outer damage zone, ~100 m wide, of brittle deformation manifested by multiple, widely spaced fractures and faults with slip up to 3 m; (2) an inner damage zone, 25-30 m wide, with high density of anastomosing conjugate sets of fault segments and fractures, many of which carry cataclasite zones; and (3) a dominant segment, with a cataclasite zone up to 50 cm thick that accommodated most of the Archaean slip of the Pretorius fault, and is regarded as the 'principal slip zone' (PSZ). This fault-zone structure indicates that during its Archaean activity, the Pretorius fault entered the mature fault stage in which many slip events were localized along a single, PSZ. The mining operations continuously induce earthquakes, including the 2004, M2. 2 event that rejuvenated the Pretorius fault in the NELSAM project area. Our analysis of the M2. 2 rupture-zone shows that (1) slip occurred exclusively along four, pre-existing large, quasi-planer segments of the ancient fault-zone; (2) the slipping segments contain brittle cataclasite zones up to 0. 5 m thick; (3) these segments are not parallel to each other; (4) gouge zones, 1-5 mm thick, composed of white 'rock-flour' formed almost exclusively along the cataclasite-host rock contacts of the slipping segments; (5) locally, new, fresh fractures branched from the slipping segments and propagated in mixed shear-tensile mode; (6) the maximum observed shear displacement is 25 mm in oblique-normal slip. The mechanical analysis of this rupture-zone is presented in Part II (Heesakkers et al., Earthquake Rupture at Focal Depth, Part II: Mechanics of the 2004 M2. 2 Earthquake Along the Pretorius Fault, TauTona mine, South Africa 2011, this volume). © 2011 Springer Basel AG. Article 2011 English 00334553 10.1007/s00024-011-0354-7 Pure and Applied Geophysics 168 2395 – 2425 School of Geology and Geophysics, University of Oklahoma, Norman, OK, United States; Chevron ETC, 1500 Louisiana St, Houston, TX 77002, United States; AngloGold Ashanti, Carletonville, Gauteng, South Africa 12 Brittle faulting; Deep mines; earthquake mechanics; earthquake rupture zone; Fault reactivation; Fault rock, Earthquakes; Fracture; Rocks; Tectonics, Fault slips, brittle deformation; cataclasite; displacement; earthquake rupture; fault zone; fracture; quartzite; strike-slip fault, South Africa https://www.scopus.com/inward/record.uri?eid=2-s2.0-84857554632&doi=10.1007%2fs00024-011-0354-7&partnerID=40&md5=71482a0c2996d825a3fefc441c2b7e8e Cited by: 51 V. Heesakkers S. Murphy Z. Reches article Heesakkers20112427 Article 2011 10.1007/s00024-011-0355-6 Pure and Applied Geophysics 168 2427 – 2449 12 https://www.scopus.com/inward/record.uri?eid=2-s2.0-84857560807&doi=10.1007%2fs00024-011-0355-6&partnerID=40&md5=84b8bef564caef6cd55211055f6a4a32 Cited by: 29 V. Heesakkers S. Murphy D.A. Lockner Z. Reches article Lippmann-Pipke20112134 An on-site gas monitoring study has been conducted in the framework of an earthquake laboratory (The International NELSAM-DAFGAS projects) at the TauTona gold mine, South Africa. Five boreholes up to 60m long were drilled at 3.54km depth into the highly fractured Pretorius Fault Zone and instruments for chemical and seismic monitoring installed therein. Over the span of 4years sensitive gas monitoring devices were continuously improved to enable the direct observation of geogas concentration variations in the DAFGAS borehole. The major gas concentrations are constant and air-like with about 78% N2, 21% O2, 1% Ar. The geogas components CO2, CH4, He and H2 show the most interesting trends and variations on the minute-by-minute basis and significantly correlate with seismic data, while the 222Rn activity remains constant. Time series and cross correlation analysis allow the identification of different gas components (geogas and tunnel air) and the identification of two processes influencing the borehole gas composition: (1) pumping-induced tunnel air breakthrough through networks of initially water-saturated fault fractures; and (2) seismicity induced permeability enhancement of fault fractures to above ∼5×10-10m2. The current set-up of the gas monitoring system is sensitive enough to quantify the resulting geogas transport during periods of intense blasting activities (including recorded blasts with seismic moment ≤1×109Nm, located within 1000m of the cubby) and, it is suggested, also during induced earthquakes, a final goal of the project. © 2011 Elsevier Ltd. 2011 English 08832927 10.1016/j.apgeochem.2011.07.011 Applied Geochemistry 26 2134-2146 Institute of Radiochemistry, Helmholtz-Zentrum Dresden-Rossendorf - Research Site Leipzig, Permoserstr. 15, 04318 Leipzig, Germany; Helmholtz-Zentrum Potsdam, Deutsches GeoForschungsZentrum, Telegrafenberg, 14473 Potsdam, Germany; Department of Earth Sciences, University of New Hampshire, 56 College Rd., Durham, NH 03824, United States; Department of Microbial, Biochemical and Food Biotechnology, University of the Free State, Bloemfontein 9300, South Africa; Rock Engineering, TauTona Gold Mine, AngloGold Ashanti, Carletonville, South Africa; Integrated Ocean Drilling Program, Texas AandM University, 1000 Discovery Drive, College Station, TX 77845, United States; School of Geology and Geophysics, Oklahoma University, 100 East Boyd Street Suite 810, Norman, OK 73019, United States 12 Concentration variation; Cross-correlation analysis; Fault zone; Gas component; Gas compositions; Gas concentration; Gas monitoring; Gas monitoring systems; Hard rocks; Permeability enhancement; Seismic datas; Seismic moment; Seismic monitoring; South Africa, Boreholes; Carbon dioxide; Earthquakes; Fracture; Gas detectors; Gold; Gold mines; Time series; Time series analysis, Gases, borehole; correlation; fault zone; fractured medium; gas transport; gold mine; hard rock; induced seismicity; mining industry; radon isotope; seismic data; time series, South Africa https://www.scopus.com/inward/record.uri?eid=2-s2.0-82155173449&doi=10.1016%2fj.apgeochem.2011.07.011&partnerID=40&md5=01d9c37de40a8833bb3dabdb3e2d2666 cited By 24 J. Lippmann-Pipke J. Erzinger M. Zimmer C. Kujawa M. Boettcher E.V. Heerden A. Bester H. Moller N.A. Stroncik Z. Reches article Lippmann-Pipke2011287 The deep gold mines of the Witwatersrand Basin, South Africa have gained recent attention not only because of investigations of the deep fracture water and associated CH4- and H2-rich gases found there, but because of recent reports of deep microbial communities persisting to depths of almost 3km - an exotic outpost of the Earth's deep biosphere. While shallower fluids in the basin (to approximately 1km) were found to contain abundant populations of methanogens and sulphate-reducing bacteria, the deepest, oldest, most saline fracture waters in the basin hosted hitherto unrecognised low biomass and low biodiversity chemoautotrophic ecosystems independent from the photosphere. Shallow and deep fluids also show distinct differences in gas and fluid geochemistry. Paleometeoric waters are dominated by hydrocarbon gases with compositional and isotopic characteristics consistent with production by methanogens utilising the CO2 reduction pathway. In contrast the deepest, most saline fracture waters contain gases that are dominated by high concentrations of H2 gas, and CH4 and higher hydrocarbon gases with isotopic signatures attributed to abiogenic processes of water-rock reaction. The high salinities (up to hundreds of g/L), highly altered δ18O and δ2H signatures, and both 36Cl and measurements of co-occurring nucleogenic noble gases for these fracture waters are consistent with extensive water-rock interaction over geologically long time scales in these high rock/water ratio environments. While the ultimate origin of these fluids has been attributed alternately to saline waters that penetrated the crystalline basement, formation water, or hydrothermal fluids in some cases, their δ18O and δ2H isotopic signatures have typically been so profoundly overprinted by the effects of long-term water-rock interaction that, for the most saline end-members, little evidence of their primary composition remains. The key objective of the present study is to further investigate the origin of these fluids by integrating for the first time detailed neon isotope analyses on the dissolved gases. Helium isotopic analysis confirmed that there is no significant mantle-derived component associated with these fluids and gases. Neon isotope results show distinct differences in neon composition that correspond to the different fluid geochemical end-members previously identified. Typical crustal neon signatures (type A) are identified in the paleometeoric waters populated with abundant methanogens. In contrast, the deep more saline fracture waters contain an enriched nucleogenic neon signature unlike any previously reported in crustal fluids. These samples show the highest 21Ne/22Ne ratios (0.160±0.003) ever reported in groundwater. Fluid inclusions in these rocks yield even higher 21Ne/22Ne ratios between 0.219 and 0.515, consistent with an extrapolated 21Ne/22Ne value of 3.3±0.2 at 20Ne/22Ne=0. We show that this enriched nucleogenic neon end-member represents a fluid component that was produced in the fluorine-depleted Archaean formations and trapped in fluid inclusions ≥2Ga ago. The observation of enriched nucleogenic neon signatures in deep fracture water implies the release of this billion year old neon component from the fluid inclusions and its accumulation in exceptionally isolated fracture water systems. The observed association of this Archean neon signature with H2-hydrocarbon-rich geogases of proposed abiogenic origin dissolved in the same deep groundwater suggests that the fracture systems have also allowed for the accumulation of various products of water-rock reactions throughout geologic times. One of these fracture systems contained the deepest characterised microbial ecosystems on earth - chemolithotrophs eking out an existence at maintenance levels independent from sunlight. Consequently, the enriched nucleogenic neon isotope signature may indicate regions in the Archaean crust where investigations of the deep biosphere might be focused. © 2011 Elsevier B.V. 2011 English 00092541 10.1016/j.chemgeo.2011.01.028 Chemical Geology 283 287-296 Helmholtz Zentrum Dresden Rossendorf, Institute of Radiochemistry, Research Site Leipzig, Permoserstr. 15, 04318 Leipzig, Germany; Department of Geology, University of Toronto, 22 Russell Street, Toronto, M5S 3B1, Canada; Helmholtz-Zentrum Potsdam, Deutsches GeoForschungsZentrum, Telegrafenberg, 14473 Potsdam, Germany; Department of Microbial, Biochemical and Food Biotechnology, University of the Free State, P.O. Box 339, Bloemfontein 9300, South Africa; Department of Geosciences, Princeton University, Guyot Hall, Princeton, NJ 08544, United States 3-4 Abiogenic; Abiogenic origin; Archaean; Archean; Chemolithotrophs; Crustal fluid; Crystalline basement; Deep fluids; Deep fractures; Deep gold mines; Deep groundwaters; Dissolved gas; Endmembers; Fluid components; Fluid geochemistry; Fluid inclusion; Formation water; Fracture systems; Fracture water; High concentration; High salinity; Higher hydrocarbons; Hydro-carbon gas; Hydrothermal fluids; Isotopic analysis; Isotopic characteristics; Isotopic signatures; Key objective; Maintenance levels; Metamorphic fluids; Microbial communities; Microbial eco system; Neon isotopes; Noble gas; South Africa; Subsurface microbiology; Sulphate reducing bacteria; Time-scales; Water rock interactions; Water-rock reactions, Analytical geochemistry; Biodiversity; Biospherics; Ecosystems; Fluids; Fluorine; Fracture; Gallium; Gas fuel analysis; Gold mines; Groundwater; Groundwater geochemistry; Helium; Hydrocarbons; Inert gases; Isotopes; Methanogens; Microbiology; Mineralogy; Rock products; Saline water; Weathering, Neon, concentration (composition); isotopic composition; methanogenesis; microbial community; neon; noble gas; water chemistry; water-rock interaction, South Africa; Witwatersrand https://www.scopus.com/inward/record.uri?eid=2-s2.0-79953281570&doi=10.1016%2fj.chemgeo.2011.01.028&partnerID=40&md5=c058436c02658727d728a7bcda351e8b cited By 63 J. Lippmann-Pipke B. Sherwood Lollar S. Niedermann N.A. Stroncik R. Naumann E. Heerden T.C. Onstott article McGarr20092815 For one week during September 2007, we deployed a temporary network of field recorders and accelerometers at four sites within two deep, seismically active mines. The ground-motion data, recorded at 200 samples/sec, are well suited to determining source and ground-motion parameters for the mining-induced earthquakes within and adjacent to our network. Four earthquakes with magnitudes close to 2 were recorded with high signal/noise at all four sites. Analysis of seismic moments and peak velocities, in conjunction with the results of laboratory stick-slip friction experiments, were used to estimate source processes that are key to understanding source physics and to assessing underground seismic hazard. The maximum displacements on the rupture surfaces can be estimated from the parameter Rv, where v is the peak ground velocity at a given recording site, and R is the hypocentral distance. For each earthquake, the maximum slip and seismic moment can be combined with results from laboratory friction experiments to estimate the maximum slip rate within the rupture zone. Analysis of the four M 2 earthquakes recorded during our deployment and one of special interest recorded by the in-mine seismic network in 2004 revealed maximum slips ranging from 4 to 27 mm and maximum slip rates from 1.1 to 6:3 m=sec. Applying the same analyses to an M 2.1 earthquake within a cluster of repeating earthquakes near the San Andreas Fault Observatory at Depth site, California, yielded similar results for maximum slip and slip rate, 14 mm and 4:0 m=sec. 2009 English 00371106 10.1785/0120080336 Bulletin of the Seismological Society of America 99 2815-2824 U.S. Geological Survey, MS 977 345 Middlefield Rd. Menlo Park, California 94025, United States; Council for Scientific and Industrial Research Natural Resources and Environmental Unit, P.O. Box 91230, Auckland Park 2006, South Africa 5 Broadband records; California; Deep gold mines; Ground motion parameters; Ground-motion; Hypocentral distance; Maximum displacement; Maximum slip; Peak ground velocity; Peak velocities; Repeating earthquake; Rupture surface; Rupture zone; San Andreas Fault; Seismic hazards; Seismic moment; Seismic networks; Slip rates; Source process; Stick-slip friction; Temporary networks, Experiments; Friction; Gold mines; Mines; Mining; Parameter estimation; Risk assessment; Slip forming; Tectonics, Earthquakes, earthquake catalogue; earthquake hypocenter; earthquake magnitude; gold mine; ground motion; mining-induced seismicity; seismic hazard; seismic moment; slip rate, California; North America; United States https://www.scopus.com/inward/record.uri?eid=2-s2.0-70349873690&doi=10.1785%2f0120080336&partnerID=40&md5=eadc13c48dee1062809d2dd7a84c75f7 cited By 16 A. McGarr M. Boettcher J.B. Fletcher R. Sell M.J.S. Johnston R. Durrheim S. Spottiswoode A. Milev article Boettcher2009 [1] With twelve years of seismic data from TauTona Gold Mine, South Africa, we show that mining-induced earthquakes follow the Gutenberg-Richter relation with no scale break down to the completeness level of the catalog, at moment magnitude Mw -1.3. Events recorded during relatively quiet hours in 2006 indicate that catalog detection limitations, not earthquake source physics, controlled the previously reported minimum magnitude in this mine. Within the Natural Earthquake Laboratory in South African Mines (NELSAM) experiment's dense seismic array, earthquakes that exhibit shear failure at magnitudes as small as Mw -3.9 are observed, but we find no evidence that Mw -3.9 represents the minimum magnitude. In contrast to previous work, our results imply small nucleation zones and that earthquake processes in the mine can readily be scaled to those in either laboratory experiments or natural faults. 2009 English 00948276 10.1029/2009GL038080 Geophysical Research Letters 36 L10307 U.S. Geological Survey, MS 977, 345 Middlefield Road, Menlo Park, CA 94025, United States; Department of Earth Sciences, University of New Hampshire, 24 Nesmith Hall, 131 Main Street, Durham, NH 03824, United States 10 Break down; Earthquake process; Earthquake source; Laboratory experiments; Lower limits; Moment magnitudes; Natural earthquake; Nucleation zone; Seismic arrays; Seismic data; Shear failure; South Africa, Mines; Mining, Earthquakes, earthquake; gold mine; mining-induced seismicity; nucleation; seismic data; spatial distribution, Africa; South Africa; Southern Africa; Sub-Saharan Africa https://www.scopus.com/inward/record.uri?eid=2-s2.0-67651121531&doi=10.1029%2f2009GL038080&partnerID=40&md5=51be8d817659d454d8fa8bffe345ee78 cited By 47 M.S. Boettcher A. McGarr M. Johnston conference Lucier2008 Researchers from The Natural Earthquake Laboratory in South African Mines (NELSAM) project are investigating the physics and mechanics of mining-induced earthquakes using the access to seismogenic depths provided by deep South African gold mines and the large number of seismic events that occur near these mines. To study these events, it is necessary to quantify the far-field stress field around the mine, determine how the presence of the mining excavation perturbs this stress field, and investigate how these mining-induced stress changes affect the pre-existing faults. In this paper, we develop and test a new technique for determining the far-field virgin state of stress near the TauTona gold mine. The technique we used to constrain the far-field stress state follows an iterative forward modeling approach that combines observations of drilling induced borehole failures in borehole images, boundary element modeling of the mining-induced stress perturbations, and forward modeling of borehole failures based on the results of the boundary element modeling. Following this approach, we determined that the state of stress is a normal faulting regime with principal stress orientations that are slightly deviated from vertical and. Modeling of breakout rotations and gaps in breakout occurrence associated with recent fault slip on critically stressed faults further confirmedthis stress state. ©2008, ARMA, American Rock Mechanics Association. Conference paper 2008 English 10.1016/j.ijrmms.2008.09.005 42nd U.S. Rock Mechanics - 2nd U.S.-Canada Rock Mechanics Symposium 46 555 – 567 Shell International Exploration and Production, Inc., Houston, TX, United States; Stanford University, Stanford, CA, United States; University of Oklahoma, Norman, OK, United States 3 African gold mine; Borehole images; Boundary elements; Far-field; Far-field stress; Fault slip; Forward modeling; Induced stress; Insitu stress; Mining excavation; Natural earthquake; Principal stress; Seismic event; State of stress; Stress field; Stress state; Virgin state, Earthquakes; Gold; Gold mines; Mines; Rock mechanics; Rocks; Stresses, Mining https://www.scopus.com/inward/record.uri?eid=2-s2.0-69549103366&partnerID=40&md5=daff1f0e0a34db6a393ad3f05685495b Cited by: 0 A.M. Lucier M.D. Zoback V. Heesakkers Z. Reches article Slater2006453 A comparison between the14C content of the methane and dissolved inorganic carbon (DIC) in deep, terrestrial subsurface systems was used to assess the timing of microbial methanogenesis contributing to gases in fracture water samples from three mines in the Witwatersrand Basin, South Africa. The results demonstrated that the majority of methane was produced over geologic timescales. In four of the samples, the methane contained no significant radiocarbon, indicating that the estimated 90% microbial methane in these samples was produced in the geologic past by indigenous microbial communities. In two samples from different mines, methaneΔ14C levels indicated a primarily ancient origin for the microbial methane with the potential for more recent contributions from ongoing indigenous microbial activities constrained to between 0 and40%, and 0 and 24%, respectively. Microbiological evidence for methanogenic archaea was observed in both of these samples. One sample had a Δ14C CH4 that was higher than the corresponding DIC, indicating an extreme decoupling between these species and raising concerns over the representative quality of this sample. The variations in the Δ14C of DIC and CH4 between and within mines demonstrate the need for a thorough assessment of each sample to obtain an accurate understanding of the role and timing of microbiological gas production in these complex, heterogeneous, terrestrial subsurface systems. The approach detailed here introduces timing as a new and widely applicable signature for the recognition of a major geochemical marker of indigenous life in the deep subsurface. © Taylor & Francis. 2006 English 01490451 10.1080/01490450600875787 Geomicrobiology Journal 23 453-462 School of Geography and Earth Sciences, McMaster University, Hamilton, ON, Canada; Lamont-Doherty Earth Observatory, Columbia University, New York, NY, United States; Geo ForschungsZentrum Potsdam, Potsdam, Germany; Division of Earth and Ecosystems Sciences (DEES), Desert Research Institute, Las Vegas, NV, United States; Woods Hole Oceanographic Institution, Woods Hole, MA, United States; Department of Geosciences, Princeton University, Princeton, NJ, United States; Department of Geology, University of Toronto, Toronto, ON, Canada 6 carbon isotope; dissolved inorganic carbon; methane; methanogenesis; microbial activity; microbiology, Africa; South Africa; Southern Africa; Sub-Saharan Africa; Witwatersrand, Archaea https://www.scopus.com/inward/record.uri?eid=2-s2.0-85023830705&doi=10.1080%2f01490450600875787&partnerID=40&md5=692d4fc6e51a1b47cf6087f57994d7fd cited By 4 G.F. Slater J. Lippmann-Pipke D.P. Moser C.M. Reddy T.C. Onstott G. Lacrampe-Couloume B. Lollar article Reches200630 2006 English 18168957 10.2204/iodp.sd.3.06.2006 Scientific Drilling 1 30-33 School of Geology and Geophysics, University of Oklahoma, Norman, OK 73019, United States 3 https://www.scopus.com/inward/record.uri?eid=2-s2.0-78650148014&doi=10.2204%2fiodp.sd.3.06.2006&partnerID=40&md5=daa50a530d929846f7ef3d598d109dcb cited By 12 Z. Reches article Lin2006479 Geochemical, microbiological, and molecular analyses of alkaline saline groundwater at 2.8 kilometers depth in Archaean metabasalt revealed a microbial biome dominated by. a single phylotype affiliated with thermophilic sulfate reducers belonging to Firmicutes. These sulfate reducers were sustained by geologically produced sulfate and hydrogen at concentrations sufficient to maintain activities for millions of years with no apparent reliance on photosynthetically derived substrates. 2006 English 00368075 10.1126/science.1127376 Science 314 479-482 Department of Geosciences, Princeton University, Princeton, NJ, United States; Department of Geosciences, National Taiwan University, Taipei, Taiwan; Institute of Oceanography, National Taiwan University, Taipei, Taiwan; Geophysical Laboratory, Carnegie Institution of Washington, Washington, DC, United States; GeoForschungsZentrum Potsdam, Telegrafenberg, Potsdam, Germany; Department of Geological Sciences, Indiana University, Bloomington, IN, United States; Department of Geology, University of Toronto, Toronto, Ont., Canada; Ecology Department, Lawrence Berkeley National Laboratory, Berkeley, CA, United States; Division of Earth and Ecosystems Sciences, Desert Research Institute, Las Vegas, NV, United States; Mponeng Mine, Anglo Gold, Johannesburg, South Africa 5798 Basalt; Geochemistry; Groundwater; Photosynthesis; Reduction; Salts, Metabasalt; Microbial biomes, Microbiology, ground water; hydrogen; sulfate, Archean; biome; groundwater; high energy environment; hydrogen; metabasalt; molecular analysis; salinity; sulfate; sulfate-reducing bacterium, Archean; article; biome; environmental sustainability; Firmicutes; geochemical analysis; microbiology; photosynthesis; priority journal, Bacteria; Biodiversity; DNA, Ribosomal; Ecosystem; Gold; Hydrogen; Mining; Oligonucleotide Array Sequence Analysis; Oxidation-Reduction; Phylogeny; RNA, Ribosomal, 16S; South Africa; Sulfates; Temperature; Thermodynamics; Time; Water Microbiology, Firmicutes https://www.scopus.com/inward/record.uri?eid=2-s2.0-33750332574&doi=10.1126%2fscience.1127376&partnerID=40&md5=9720d92d3f344f7da8d40873c90885ea cited By 287 L.-H. Lin P.-L. Wang D. Rumble J. Lippmann-Pipke E. Boice L.M. Pratt B.S. Lollar E.L. Brodie T.C. Hazen G.L. Andersen T.Z. DeSantis D.P. Moser D. Kershaw T.C. Onstott article Onstott2006369 Water residing within crustal fractures encountered during mining at depths greater than 500 meters in the Witwatersrand basin of South Africa represents a mixture of paleo-meteoric water and 2.0–2.3 Ga hydrothermal fluid. The hydrothermal fluid is highly saline, contains abiogenic CH4 and hydrocarbon, occasionally N2, originally formed at ∼250–300◦C and during cooling isotopically exchangedO and Hwith minerals and accrued H2,4He and other radiogenic gases. The paleo-meteoric water ranges in age from ∼10 Ka to >1.5 Ma, is of low salinity, falls along the global meteoric water line (GMWL) and is CO2 and atmospheric noble gas-rich. The hydrothermal fluid, which should be completely sterile, has probably been mixing with paleo-meteoric water for at least the past∼100 Myr, a process which inoculates previously sterile environments at depths >2.0 to 2.5 km. Free energy flux calculations suggest that sulfate reduction is the dominant electron acceptor microbial process for the high salinity fracture water and that it is 107 times that normally required for cell maintenance in lab cultures. Flux calculations also indicate that the potential bioavailable chemical energy increases with salinity, but because the fluence of bioavailable C, N and P also increase with salinity, the environment remains energy-limited. The4He concentrations and theoretical calculations indicate that the H2 that is sustaining the subsurface microbial communities (e.g. H2-utilizing SRB and methanogens) is produced by water radiolysis at a rate of ∼1nMyr−1. Microbial CH4 mixes with abiogenicCH4 to produce the observed isotopic signatures and indicates that the rate of methanogenesis diminishes with depth from∼100 at<1 kmbls, to<0.01nMyr−1 at>3 kmbls. Microbial Fe(III) reduction is limited due to the elevated pH. The δ13C of dissolved inorganic carbon is consistent with heterotrophy rather than autotrophy dominating the deeper, more saline environments. One potential source of the organic carbon may be microfilms present on the mineral surfaces. © Taylor & Francis. 2006 English 01490451 10.1080/01490450600875688 Geomicrobiology Journal 23 369-414 Department of Geosciences, Princeton University, Princeton, NJ, United States; Department of Geology, University of Toronto, Toronto, ON, Canada; Geoforschungszentrum Potsdam, Potsdam, Germany; Department of Geological Sciences, Biogeochemical Laboratorie, Indiana University, Bloomington, IN, United States; Analysis University of Tennessee, Knoxville, TN, United States; Environmental Microbiology Group, Pacific Northwest National Laboratory, Richland, WA, United States; New Mexico Institute of Mining and Technology, Department of Biology, Socorro, NM, United States; Oak Ridge National Laboratory, Oak Ridge, TN, United States; Department of Microbial, Biochemical and Food Biotechnology, Faculty of Science, University of the Free State, Bloemfontein, Free State, South Africa; Geosyntec, Princeton, NJ, United States; Shaw Environmental, Lawrenceville, NJ, United States; Department of Earth Sciences, The University of Western Ontario, London, ON, N6A 5B7, Canada 6 biogeochemistry; dissolved inorganic carbon; groundwater; methanogenesis; microbial community; sulfate-reducing bacterium, Africa; South Africa; Southern Africa; Sub-Saharan Africa; Witwatersrand, Methanobacteriales https://www.scopus.com/inward/record.uri?eid=2-s2.0-67349125827&doi=10.1080%2f01490450600875688&partnerID=40&md5=ad063d82a6eac2a8cc0237985bb395ea cited By 33 T.C. Onstott L.-H. Lin M. Davidson B. Mislowack M. Borcsik J. Hall G. Slater J. Ward B. Sherwoodlollar J. Lippmann-Pipke E. Boice L.M. Pratt S. Pfiffner D. Moser T. Gihring T.L. Kieft T.J. Phelps E. Vanheerden D. Litthaur M. DeFlaun R. Rothmel G. Wanger G. Southam article Wilson2005749 Grain size reduction and gouge formation are found to be ubiquitous in brittle faults at all scales, and most slip along mature faults is observed to have been localized within gouge zones. This fine-grain gouge is thought to control earthquake instability, and thus understanding its properties is central to an understanding of the earthquake process. Here we show that gouge from the San Andreas fault, California, with ∼160 km slip, and the rupture zone of a recent earthquake in a South African mine with only ∼0.4 m slip, display similar characteristics, in that ultrafine grains approach the nanometre scale, gouge surface areas approach 80 m2g-1, and grain size distribution is nonfractal. These observations challenge the common perception that gouge texture is fractal and that gouge surface energy is a negligible contributor to the earthquake energy budget. We propose that the observed fine-grain gouge is not related to quasi-static cumulative slip, but is instead formed by dynamic rock pulverization during the propagation of a single earthquake. 2005 English 00280836 10.1038/nature03433 Nature 434 749-752 School of Geology and Geophysics, University of Oklahoma, Norman, OK 73019, United States; Department of Geological Sciences, University of Nevada, Reno, NV 89557, United States 7034 Comminution; Earthquakes; Fractals; Grain size and shape; Rocks, Earthquake instability; Energetics; Fine-grain gouge; Gouge formation, Particle size analysis, earthquake; particle size, article; earthquake; energy consumption; energy transfer; mining; particle size; priority journal; rock; surface property https://www.scopus.com/inward/record.uri?eid=2-s2.0-17644372729&doi=10.1038%2fnature03433&partnerID=40&md5=c40ab10403bf9473b969399d26366d2c cited By 239 B. Wilson T. Dewers Z. Reches J. Brune article Lin2005 H2 is probably the most important substrate for terrestrial subsurface lithoautotrophic microbial communities. Abiotic H2 generation is an essential component of subsurface ecosystems truly independent of surface photosynthesis. Here we report that H2 concentrations in fracture water collected from deep siliclastic and volcanic rock units in the Witwatersrand Basin, South Africa, ranged up to two molar, a value far greater than observed in shallow aquifers or marine sediments. The high H2 concentrations are consistent with that predicted by radiolytic dissociation of H2O during radioactive decay of U, Th, and K in the host rock and the observed He concentrations. None of the other known H2-generating mechanisms can account for such high H2 abundance either because of the positive free energy imposed by the high H2 concentration or pH or because of the absence of required mineral phases. The radiolytic H 2 is consumed by methanogens and abiotic hydrocarbon synthesis. Our calculations indicate that radiolytic H2 production is a ubiquitous and virtually limitless source of energy for deep crustal chemolithoautotrophic ecosystems. Copyright 2005 by the American Geophysical Union. 2005 English 15252027 10.1029/2004GC000907 Geochemistry, Geophysics, Geosystems 6 Department of Geosciences, Princeton University, Princeton, NJ 08540, United States; Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Road, N.W., Washington, DC 20015, United States; Lamont-Doherty Earth Observatory, Columbia University, 61 Route 9W, Palisades, NY 10964, United States; Geo Forschungs Zentrum Potsdam, Telegraphenberg, Haus B, 320, D-14473 Potsdam, Germany; Stable Isotope Laboratory, Department of Geology and Geophysics, University of Toronto, Toronto, 22 Russel Street, Toronto, ON M5S 3D1, Canada; GeoSyntec Consultants, 1 Airport Place, Princeton, NJ 08540, United States; Shaw Group, 4100 Quakerbridge Road, Lawrenceville, NJ 08648, United States; Pacific Northwest National Laboratory, Mailstop P7-50, 902 Battelle Boulevard, Richland, WA 99352, United States; Department of Geosciences, Princeton, NJ 08540, United States 7 https://www.scopus.com/inward/record.uri?eid=2-s2.0-24644521340&doi=10.1029%2f2004GC000907&partnerID=40&md5=48ff3410b2d580a26231893026ab9fc3 cited By 161 L.-H. Lin J. Hall J. Lippmann-Pipke J.A. Ward B.S. Lollar M. DeFlaun R. Rothmel D. Moser T.M. Gihring B. Mislowack T.C. Onstott