caa a22 4500 445814586 CHVBK 20180317145222.0 cr unu---uuuuu 170323e20110201xx s 000 0 eng 10.1007/s10040-010-0645-6 doi (NATIONALLICENCE)springer-10.1007/s10040-010-0645-6 Helium measurements of pore fluids obtained from the San Andreas Fault Observatory at Depth (SAFOD, USA) drill cores [Elektronische Daten] [S. Ali, M. Stute, T. Torgersen, G. Winckler, B. Kennedy] Mesures de l'hélium des fluides intersticiels contenus dans les carottes du San Andreas Fault Observatory à Depth (SAFOD, USA) 4He accumulated in fluids is a well established geochemical tracer used to study crustal fluid dynamics. Direct fluid samples are not always collectable; therefore, a method to extract rare gases from matrix fluids of whole rocks by diffusion has been adapted. Helium was measured on matrix fluids extracted from sandstones and mudstones recovered during the San Andreas Fault Observatory at Depth (SAFOD) drilling in California, USA. Samples were typically collected as subcores or from drillcore fragments. Helium concentration and isotope ratios were measured 4-6 times on each sample, and indicate a bulk 4He diffusion coefficient of 3.5 ± 1.3×10-8 cm2s-1 at 21°C, compared to previously published diffusion coefficients of 1.2×10-18 cm2s-1 (21°C) to 3.0×10-15 cm2s-1 (150°C) in the sands and clays. Correcting the diffusion coefficient of 4Hewater for matrix porosity (∼3%) and tortuosity (∼6-13) produces effective diffusion coefficients of 1×10-8 cm2s-1 (21°C) and 1×10-7 (120°C), effectively isolating pore fluid 4He from the 4He contained in the rock matrix. Model calculations indicate that <6% of helium initially dissolved in pore fluids was lost during the sampling process. Complete and quantitative extraction of the pore fluids provide minimum in situ porosity values for sandstones 2.8 ± 0.4% (SD, n = 4) and mudstones 3.1 ± 0.8% (SD, n = 4). Springer-Verlag, 2010 Stable isotopes nationallicence Pore fluids nationallicence Porosity nationallicence Tortuosity nationallicence USA nationallicence Ali S. Lamont-Doherty Earth Observatory, 61 Route 9W, 10964, Palisades, NY, USA aut Stute M. Lamont-Doherty Earth Observatory, 61 Route 9W, 10964, Palisades, NY, USA aut Torgersen T. Lamont-Doherty Earth Observatory, 61 Route 9W, 10964, Palisades, NY, USA aut Winckler G. Lamont-Doherty Earth Observatory, 61 Route 9W, 10964, Palisades, NY, USA aut Kennedy B. Lawrence-Berkeley National Laboratory, 1 Cyclotron Road, MS70A-4418, 94720, Berkeley, CA, USA aut Hydrogeology Journal Springer-Verlag 19/1(2011-02-01), 237-247 1431-2174 19:1<237 2011 19 10040 https://doi.org/10.1007/s10040-010-0645-6 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10040-010-0645-6 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Ali S. Lamont-Doherty Earth Observatory, 61 Route 9W, 10964, Palisades, NY, USA aut NATIONALLICENCE 700 1- Stute M. Lamont-Doherty Earth Observatory, 61 Route 9W, 10964, Palisades, NY, USA aut NATIONALLICENCE 700 1- Torgersen T. Lamont-Doherty Earth Observatory, 61 Route 9W, 10964, Palisades, NY, USA aut NATIONALLICENCE 700 1- Winckler G. Lamont-Doherty Earth Observatory, 61 Route 9W, 10964, Palisades, NY, USA aut NATIONALLICENCE 700 1- Kennedy B. Lawrence-Berkeley National Laboratory, 1 Cyclotron Road, MS70A-4418, 94720, Berkeley, CA, USA aut NATIONALLICENCE 773 0- Hydrogeology Journal Springer-Verlag 19/1(2011-02-01), 237-247 1431-2174 19:1<237 2011 19 10040 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer