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(SAFOD) Phase III Whole-Rock Core: Implications for Fault Zone Deformation and Fluid-Rock Interactions

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(SAFOD) Phase III Whole-Rock Core: Implications for Fault Zone Deformation and Fluid-Rock Interactions Utah State University DigitalCommons@USU Geosciences Presentations Geosciences 2010 Composition and Structure of the San Andreas Fault Observatory at Depth (SAFOD) Phase III Whole-Rock Core: Implications for Fault Zone Deformation and Fluid-Rock Interactions Kelly Keighley Bradbury Utah State University James P. Evans Utah State University Follow this and additional works at: https://digitalcommons.usu.edu/geology_pres Part of the Geology Commons Recommended Citation Bradbury, Kelly Keighley and Evans, James P., "Composition and Structure of the San Andreas Fault Observatory at Depth (SAFOD) Phase III Whole-Rock Core: Implications for Fault Zone Deformation and Fluid-Rock Interactions" (2010). Geosciences Presentations. Paper 4. https://digitalcommons.usu.edu/geology_pres/4 This Poster is brought to you for free and open access by the Geosciences at DigitalCommons@USU. It has been accepted for inclusion in Geosciences Presentations by an authorized administrator of DigitalCommons@USU. For more information, please contact [email protected]. Composition and Structure of the San Andreas Fault Observatory at Depth (SAFOD) Phase III Whole-Rock Core: Implications for Fault Zone Deformation and Fluid-Rock Interactions By Kelly Keighley Bradbury ([email protected]) and James P. Evans ([email protected]), Department of Geology, Utah State University, 4505 Old Main Hill, Logan, UT I. Abstract III. San Andreas Fault Rock Composition and Texture: Micro-scale Observations IV. Whole-Rock Geochemistry We examine the composition and texture of whole-rock core from ~ 3 km depth in the San Andreas Fault Observatory at Depth (SAFOD) borehole, which provides a unique Study Area Location Core ID E_1_1 E_1_4 E_1_6A E_2_2 Gap G_1_2 G_1_3 G_1_4 G_1_4 G_2_2 G_2_4 G_2_4 G_2_5 G_2_8 G_2_9 G_3_1 Gap G_4_2 G_4_2 G_4_3 G_4_4 G_4_4 G_4_5 G_4_6 G_5_2 G_5_2 G_5_4 G_5_5 G_5_7 G_6_4 G_6_5 G_6_6 opportunity to characterize in situ rock properties of the near-fault environment, and Core Depth (m) 3142.00 3144.60 3146.3 3150.30 3187.5 3189.2 3189.3 3190.1 3192.70 3193.6 3193.9 3194.8 3197.7 3197.9 3198.7 3295.8 3296.6 3297.4 3298.4 3297.9 3299.1 3299.9 3301.4 3301.7 3303.6 3304.6 3305.1 3310.4 3311.1 3312.1 Black Fault Rock ~ ultrafine cataclasite SO3 0.12 0.14 0.16 0.19 0.11 0.07 0.09 0.08 0.03 4.04 0.07 0.13 0.20 0.15 0.07 0.22 0.26 0.11 0.08 0.09 0.19 0.08 0.10 how these properties vary in an area where deformation is accommodated by aseis- X-ray Diffraction Cl 0.05 0.06 0.06 0.04 0.17 0.13 0.08 0.33 0.30 0.07 0.47 0.32 0.50 0.24 0.18 0.13 0.15 0.15 0.12 0.13 0.15 0.19 0.16 A2. 3193.9 Unnormalized Major Elements (Weight %): SiO2 67.82 58.80 75.16 72.96 70.19 79.06 68.37 72.11 70.71 67.97 65.70 64.82 47.74 49.97 60.59 55.60 42.01 46.57 41.44 63.91 59.40 48.54 36.71 81.34 60.93 58.91 58.21 58.99 30.93 57.77 mic creep and high-rates of microseismicity. Detailed petrography and microstructural TiO2 0.599 1.012 0.145 0.425 0.604 0.318 0.555 0.572 0.540 0.444 0.442 0.483 0.426 0.447 0.168 0.645 0.319 0.363 0.280 0.441 0.483 0.357 0.376 0.347 0.658 0.720 0.660 0.743 0.351 0.701 Al2O3 15.80 18.11 12.21 14.20 12.03 6.68 12.18 11.47 13.81 9.89 10.59 11.31 8.62 9.09 6.06 12.84 6.20 7.20 5.71 11.32 10.84 6.57 8.42 8.72 13.87 16.66 17.27 15.19 8.52 15.08 analyses coupled with X-Ray Diffraction and X-ray Fluorescence techniques are used to 3193.6 3193.9 FeO* 2.63 5.26 0.62 1.04 4.07 2.30 4.46 3.07 2.62 2.80 3.29 3.15 6.60 6.49 0.95 6.93 6.20 6.04 6.21 3.59 3.76 1.71 3.32 0.86 6.84 7.55 6.93 7.74 4.13 7.38 MnO 0.041 0.100 0.027 0.015 0.027 0.032 0.023 0.029 0.021 0.050 0.042 0.047 0.111 0.116 0.074 0.061 0.097 0.093 0.123 0.071 0.069 0.124 0.169 0.012 0.103 0.066 0.059 0.080 1.378 0.113 MgO 1.03 2.15 0.34 0.35 1.46 0.91 2.31 1.47 1.95 1.35 2.05 1.85 18.78 16.64 0.56 9.41 21.73 18.95 22.30 5.54 5.13 1.39 3.02 0.72 2.96 3.39 3.28 3.39 1.78 3.16 describe composition, alteration, and textures. CaO 1.82 2.09 2.24 1.72 0.63 2.61 1.32 0.63 1.03 5.48 3.55 3.10 2.49 2.30 12.88 1.71 3.18 3.03 4.83 3.14 5.88 20.42 22.47 0.92 3.21 1.25 1.09 2.15 25.43 3.33 Na2O 3.01 2.88 3.14 3.51 1.08 0.45 0.67 0.90 0.71 0.55 1.33 2.82 1.13 1.15 1.44 1.17 1.17 1.50 0.97 4.18 1.75 1.40 1.08 1.94 2.58 2.17 1.87 2.36 1.05 2.07 K2O 4.49 4.41 3.27 4.10 2.61 1.29 2.07 2.39 3.10 2.06 1.29 1.16 0.37 0.51 1.97 1.37 0.17 0.45 0.15 0.83 2.23 1.28 1.51 2.91 1.37 2.17 2.62 1.58 1.24 1.89 P2O5 0.149 0.326 0.037 0.060 0.262 0.226 0.212 0.233 0.168 0.186 0.178 0.168 0.091 0.096 0.153 0.205 0.076 0.078 0.069 0.103 0.440 0.218 0.314 0.185 0.068 0.094 0.077 0.075 0.283 0.126 Sum 97.39 95.13 97.20 98.38 92.97 93.88 92.17 92.87 94.66 90.78 88.46 88.92 86.36 86.81 84.85 89.94 81.16 84.27 82.07 93.13 89.97 82.00 77.38 97.96 92.59 92.98 92.07 92.28 75.10 91.63 All samples record multiple generations of cataclastic deformation in a complexly de- 1906 M 7.8 LOI (%) na na na na 6.60 5.34 6.91 6.48 na 7.90 10.33 10.77 13.53 12.97 8.29 na 18.63 15.60 17.55 7.03 9.04 17.58 21.26 na 7.66 7.48 8.10 7.58 24.06 8.62 Si Quartz Normalized Major Elements (Weight %): Si O2 formed and altered sequence of fine-grained sheared rocks. Localized shears bound San Francisco Core Depth (m) 3142.00 3144.60 3146.3 3150.30 3187.5 3189.2 3189.3 3190.1 3192.70 3193.6 3193.9 3194.8 3197.7 3197.9 3198.7 3295.8 3296.6 3297.4 3298.4 3297.9 3299.1 3299.9 3301.4 3301.7 3303.6 3304.6 3305.1 3310.4 3311.1 3312.1 Magnetite SiO2 69.64 61.81 77.33 74.16 75.50 84.21 74.18 77.64 74.70 74.88 74.28 72.90 55.29 57.56 71.41 0.718 51.77 55.26 50.49 68.63 66.02 59.19 47.44 83.03 65.81 63.36 63.22 63.92 41.19 63.05 1989 M 6.9 Fe +2 Fe2 +3 O4 TiO2 0.615 1.064 0.149 0.432 0.650 0.339 0.602 0.616 0.571 0.489 0.500 0.543 0.493 0.515 0.198 14.28 0.394 0.431 0.341 0.474 0.537 0.436 0.485 0.354 0.710 0.775 0.717 0.805 0.468 0.765 multi-layered zones of medium to ultra-fine grained cataclasite. Phacoidal clasts or Albite Al2O3 16.22 19.03 12.57 14.43 12.94 7.12 13.21 12.35 14.59 10.90 11.97 12.73 9.98 10.47 7.14 7.70 7.64 8.55 6.95 12.15 12.04 8.01 10.88 8.90 14.98 17.92 18.76 16.46 11.35 16.46 ( Na , Ca ) Al ( Si , Al )3 O8 NA Plate X-ray Diffraction FeO* 2.70 5.53 0.64 1.05 4.38 2.45 4.84 3.30 2.77 3.08 3.72 3.55 7.64 7.48 1.11 0.068 7.64 7.17 7.56 3.86 4.18 2.09 4.29 0.88 7.39 8.12 7.52 8.38 5.50 8.06 porphyroclasts comprised of serpentinite, quartz, and older cataclasite are embedded A1.
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