Diane E. Moore David A. Lockner 20250820 tabular digital data https://doi.org/10.5066/P1LFKQGZ A series of hydrothermal frictional strength experiments was conducted on synthetic gouges prepared from five chlorite-rich samples of varying composition. We present chlorite mineral compositions obtained by electron microprobe techniques, and X-ray diffraction and bulk chemical analyses of the gouges that were prepared by hand-grinding each sample to less than 90-µm grain diameter. Major and minor element gouge analyses were conducted in the Geology, Geophysics, and Geochemistry Science Center laboratory of the U. S. Geological Survey in Lakewood, CO. All of the other data were collected in the earthquake Science Center laboratories, which were located at that time in Menlo Park, CA. Chlorite samples tested: Fe-chlorite. Chlorite-garnet schist of unknown origin. The millimeter-scale euhedral garnets were removed from the sample prior to grinding. Ore14-1. Chlorite blackwall, the inner zone of a metasomatic alteration rind surrounding a high-grade mafic blueschist block in Coos Counry, southwest Oregon. Location: 42.9883°N, 124.3811°W. LP14-3a. Large, chlorite-rich clast exposed in an exhumed shear on the west side of Lake Pillsbury, Mendocino County, California. Location: 39.4072°N, 122.9575°W. CCa-2. Ripidolite chlorite, obtained from the Clay Minerals Society Special Clay Minerals Collection. Flagstaff Hill, El Dorado County, California. Location: 38.7648°N, 121.0839°W. Russian chlorite. Clinochlore cleavage flakes from Achmativ Mine, a famous skarn deposit located near Zlatonst in the Southern Urals, Russia. Location: 55.3042°N, 59.6561°E. The purpose of the study was twofold: first, to test whether or not the composition of chlorite is correlated with its frictional strength and, second, to determine the effect of heating on chlorite frictional properties. Although sample locations are provided, where known, they are of no relevance to this study. 20100405 20170607 Time range of laboratory strength experiments. Complete None planned Sources of samples obtained for use in this study. Where known, specific sample locations arre provided in the Abstract rather than in the data tables. -124.0000 59.7000 55.3000 38.7000 ISO 19115 Topic Category geoscientificInformation USGS chemical analysis faulting (geologic) USGS Thesaurus faulting (geologic) chlorite frictional strength geochemistry USGS Metadata Identifier USGS:68237e96d4be025fcee55c4b No access constraints. Please see 'Distribution Information' for details. These data are marked with a Creative Common CC0 1.0 Universal License. These data are in the public domain and do not have any use constraints. Users are advised to read the dataset's metadata thoroughly to understand appropriate use and data limitations. Diane E Moore USGS - SOUTHWEST REGION Scientist Emerita mailing and physical

NASA AMES-Moffett Field, Moffett Field - Building 19

350 N. Akron Rd.

Moffett Field CA 94035 US 650-643-7134 dmoore@usgs.gov Accuracy and uncertainties are addressed in the individual process steps, as appropriate. No formal accuracy tests were conducted. Data set is considered complete for the information presented. Users are advised to read the rest of the metadata record carefully for additional details. No formal positional accuracy tests were conducted. No formal positional accuracy tests were conducted. Chlorite compostions (electron microprobe analysis): Chlorite mineral compositions were obtained by electron microprobe analysis of carbon-coated, polished thin sections of the starting materials. Analytical conditions were 15kV accelerating voltage, 10 nA beam current, and 5 µm beam diameter. The mineral standard set consisted of feldspars (Si, Al, Ca, Na, K), natural olivine (Mg, Fe, Ni), chromite (Cr), and the oxides Mn2O3 (Mn) and TiO2 (Ti). A set of mineral standards was also tested at intervals during the data collection, to check for drift in the sample current. Reported compositions are the averages of 20-25 spot analyses. X-ray diffraction analysis: Synthetic gouges were prepared from the starting materials by removing mineral impurities under a stereomicroscope and then hand-grinding the samples to less than 90 µm grain diameter. Packed-powder X-ray diffraction analyses of the prepared gouges were made on a Rigaku Multiflex diffractometer. The samples were analyzed using Cu-K alpha radiation at 40kV operating voltage and 20 mA beam current. Scans were run over the range 2-70 degrees 2-theta at a 1-degree per minute scanning rate and 0.01-degree sampling width. Whole-Rock Geochemistry: Compositions of the synthetic gouge samples were made by Inductively Coupled Plasma (ICP) techniques in the laboratory of the Geology, Geophysics, and Geochemistry Science Center at the Denver Federal Center in Lakewood, Colorado. The sample is fused with lithium metaborate and dissolved using dilute nitric acid in a graphite crucible; the solution is then analyzed by ICP-Optical Emission Spectroscopy. The analysis total Fe contents, that is, combined ferrous and ferric iron. Ferrous oxide (FeO) contents were also determined separately, by titration techniques. The samples were digested in a mixture of sulfuric, hydrochloric, and hydrofluoric acids, then titrated with a solution of potassium dichromate using a sodium diphenylamine sulphonate indicator. Details of the analytical procedures, performance, and reporting limits can be found in Taggart, J. E., 2002, Analytical methods for chemical analysis of geologic and other materials, U. S. Geological Survey Open-File Report 02-223, https://pubs.usgs.gov/of/2002/ofr-02-0223/. Frictional Strength experiments: The five synthetic gouges prepared from the starting materials were tested in a triaxial apparatus fitted with an internal furnace. Each sample consisted of an initially 1-mm thick layer of gouge smeared as a thick paste along a 30° sawcut in a Westerly granite cylinder (19.1 mm diameter). The sawcut surfaces were roughened with 120-grit SiC. The upper granite piece contains a through-going drillhole, to facilitate pore-fluid access to the gouge layer. experiments were run at temperatures of 25, 100, 200, and 300°C, 160 MPa normal stress and 60 MPa pore pressure of deionized water, to yield 100 MPa effective normal stress. The sample cylinders were placed within Pb jackets for the experiments run at 25-200°C, and Cu jackets were used in the 300°C experiments. Argon gas was used as the confining pressure medium. The pore-pressure lined were evacuated for 15-20 minutes, during which time the confining pressure was increased to 70-80 MPa. The 60 MPa fluid pressure was then applied and and confining pressure raised concurrently to 160 MPa at room temperature or ~`30-140 MPa for heated experiments. In the latter case, the starting value of 160 MPa confining pressure was attained as the sample heated. axial stress is provided by a piston that pushes against the bottom of the sample assembly at a fixed rate, causing slip along the inclined sawcut as the sample shortens in the axial direction. As axial load increases during an experiment, both shear and normal stress increase. To maintain constant normal stress, computer-controlled changes to the confining pressure were applied. Axial velocities were varied at intervals in the range 0.001-1.0 µm/s (corresponding sliding velocities along the sawcut are approximately 0.0011501.15 µm/s). The velocity sequence used in the experiments was: 0.1 µm/s (-0.1-1.3 mm displacement), 0.01 (1.3-1.8), 0.001 (1.8-2.0), 0.01 (2.0-2.5), 0.1 (2.5-3.0), 1.0 (3.0-3.5), 0.1 (3.5-4.0). Several experiments did not reach the 4-mm axial displacement limit because of jacket failures. Corrections for seal friction and for changes in contact area along the sliding surface were made during the experiment, and corrections for jacket strength were applied after the experiment. We report values of apparent coefficient of friction, µ, versus displacement, where is defined as the shear stress divided by effective normal stress. The uncertainty in determining absolute coefficient of friction at this normal stress is about +/-0.02 for Pb-jacket experiments and +/-0.03 for those using Cu jackets. 20250710 Diane E. Moore U. S. Geological Survey, Southwest Region, Earthquake Science Center Scientist Emerita mailing and physical

Bldg. 19

350 N. Akron Rd.

Moffett Field CA 94035 USA 650-643-7134 dmoore@usgs.gov Chlorite_mineral_compositions.csv Comma Separated Value (CSV) file containing data. Producer Defined Sample_No. Number assigned to a given chlorite sample. Producer Defined 1 5 integers Sample_Name Name given to each chlorite sample tested. Producer Defined Fe-chlorite Chlorite-garnet schist of unknown origin. Producer defined Ore14-1 Sample number of chlorite collected from the inner zone of a metasomatic alteration rind surrounding a high-grade mafic blueschist block. Producer defined LP14-3a Large, chlorite-rich clast exposed in an exhumed shear zone. Producer defined CCa-2 Ripidolite chlorite sample obtained from Clay Minerals Society Special Clay Minerals Collection. Producer defined Russian chlorite Clinochlore cleavage flakes from a skarn deposit; sample purchased from Mineralogical Research Co. Producer defined SiO2 Silicon concentration, reported as its oxide. Producer Defined 25.84 33.02 weight percent TiO2 Titanium concentration, reported as its oxide. Producer Defined 0.02 0.07 weight percent Al2O3 Aluminum concentration, reported as its oxide. Producer Defined 16.03 23.91 weight percent Cr2O3 Chromium concentration, reported as its oxide. Producer Defined 0.02 0.09 weight percent FeO_total Fe Total iron concentration, reported as ferrous oxide. Producer Defined 1.28 21.56 weight percent NiO Nickel concentration, reported as its oxide. Producer Defined 0.0 0.11 weight percent MnO Manganese concentration, reported as its oxide. Producer Defined 0.02 0.31 weight percent MgO Magnesium concentration, reported as its oxide. Producer Defined 18.33 33.61 weight percent CaO Calcium concentration, reported as its oxide. Producer Defined 0.02 0.06 weight percent Na2O Sodium concentration, reported as its oxide. Producer Defined 0.01 0.03 weight percent K2O Potassium concentration, reported as its oxide. Producer Defined 0.0 0.04 weight percent anhydrous_total Sum of the analyzed elements, reported as an oxide total. Producer Defined 84.7 87.66 weight percent Chlorite-rich_gouge_X-ray_Diffractio_Data.csv Comma Separated Value (CSV) file containing data. Producer Defined 2_theta Angle of X-ray beam as it hits the sample. Producer Defined 2.0 70.0 degrees 1 _Fe_chlorite X-ray intensity for Fe-chlorite sample. Producer Defined 8 16193 counts per second 2 _Ore14-1 X-ray intensity for sample Ore14-1. Producer Defined 7 10333 counts per second 3_LP14-3a X-ray intensity for sample LP14-3a. Producer Defined 20 12518 counts per second 4_CCa-2 Counts per second for sample CCa-2. Producer Defined 24 4546 counts per second 5_Russian_chlorite X-ray intensity for Russian chlorite sample. Producer Defined 48 11088 counts per second Chlorite-rich_gouge_compositions.csv Comma Separated Value (CSV) file containing data. Producer Defined Sample_No. Number assigned to a given chlorite sample. Producer Defined 1 5 integers Sample_Name Name given to each chlorite sample tested. Producer Defined Fe-chlorite Chlorite-garnet schist of unknown origin. Producer defined Ore14-1 Sample number of chlorite collected from the inner zone of a metasomatic alteration rind surrounding a high-grade blueschist block. Producer defined LP14-3a Large, chlorite-rich clast exposed in an exhumed shear zone. Producer defined CCa-2 Ripidolite chlorite sample obtained from Clay Minerals Society Special Clays Collection. Producer defined Russian chlorite Clinochlore cleavage flakes from a skarn deposit; sample purchased from Mineralogical Research Co. Producer defined Si Silicon concentration Producer Defined 11.6 15.1 elemental weight percent Ti Titanium concentration Producer Defined 0.04 0.68 elemental weight percent Al Aluminum concentration Producer Defined 8.32 12.8 elemental weight percent Fe Total iron concentration Producer Defined 1.24 16.8 elemental weight percent Mg Magnesium concentration Producer Defined 10.4 21.6 elemental weight percent Ca Calcium concentration Producer Defined 0.05 0.79 elemental weight percent Na Sodium concentration Producer Defined 0.04 0.13 elemental weight percent K Potassium concentration Producer Defined <0.01 Less than 0.01 weight percent of the element is present in the sample. Producer defined 0.06 elemental weight percent Producer defined P Potassium concentration Producer Defined <0.01 Less than 0/.01 weight percent of the element is present. Producer defined 0.08 elemental weight percent Producer defined Ba Barium concentration Producer Defined <10 elemental weight percent (less than 10) Producer defined Cr Chromium concentration Producer Defined 405 concentration in parts per million Producer defined 2062 concentration, in parts per million Producer defined 363 concentration, in parts per million Producer defined <100 concentration, in parts per million (less than 100) Producer defined 133 concentration, in parts per million Producer defined Mn Manganese concentration Producer Defined 766 concentration, in parts per million Producer defined 2007 concentration, in parts per million Producer defined 1939 concentration, in parts per million Producer defined <100 concentration, in parts per million (less than 100) Producer defined 120 concentration, in parts per million Producer defined Nb Niobium concentration Producer Defined <10 parts per million (less than 10) Producer defined Sr Strontium concentration Producer Defined 13 parts per million Producer defined <10 parts per million (less than 10) Producer defined 14 parts per million Producer defined Y Yttrium concentration Producer Defined 31 parts per million Producer defined <10 parts per million (less than 10) Producer defined 36 parts per million Producer defined Zr Zirconium concentration Producer Defined 49 parts per million Producer defined 26 parts per million Producer defined 130 parts per million Producer defined 145 parts per million Producer defined <10 parts per million (less than 10) Producer defined FeO_titrated Concentration of divalent iron, reported as oxide (FeO) weight percent. Producer Defined 1.63 21.2 weight percent 1_Fe_chlorite_friction.csv Comma Separated Value (CSV) file containing data. Producer Defined dZ_25_mm axial displacement for test at 25°C Producer Defined -0.09635 4.00094 millimeters (mm) mu _ Coefficient of friction at 25°C Producer Defined -0.0157 0.3225 dZ_100_mm Axial displacement for test at 100°C. Producer Defined -0.09896 4.02454 millimeters mu_100 coefficient of friction at 100°C. Producer Defined -0.0149 0.32 dZ_200_mm Axial displacement for test at 200°C. Producer Defined -0.08858 4.03456 mu_200 Coefficient of friction at 200°C Producer Defined << empty cell >> No Data Producer defined -0.007 0.3671 dZ_300_mm Axial displacement for test at 300°C Producer Defined -0.10191 3.18397 millimeters mu_300 Coefficient of friction at 300C. Producer Defined << empty cell >> No Data Producer defined -0.0465 0.3281 2_Ore_14-1_chlorite_friction.csv Comma Separated Value (CSV) file containing data. Producer Defined dZ_25_mm Axial displacement for test at 25°C Producer Defined -0.09419 4.00295 mu_25 Coefficient of friction at 25°C Producer Defined -0.0131 0.2639 dZ_100_mm Axial displacement for test at 100°C Producer Defined << empty cell >> No Data Producer defined -0.10511 4.01842 millimeters mu_100 Coefficient of friction at 100°C Producer Defined << empty cell >> No Data Producer defined -0.0129 0.2902 dZ_200_mm Axial displacement for test at 200°C Producer Defined << empty cell >> No Data Producer defined -0.10702 3.52751 millimeters mu_200 Coefficient of friction at 200°C Producer Defined << empty cell >> No Data Producer defined -0.002 0.3282 dZ_300_mm Axial displacement for test at 300°C Producer Defined << empty cell >> No Data Producer defined -0.10368 3.06256 millimeters mu_300 Coefficient of friction at 300°C Producer Defined << empty cell >> No Data Producer defined -0.0518 0.2954 3_LP14-3a_chlorite_friction.csv Comma Separated Value (CSV) file containing data. Producer Defined dZ_25_mm Axial Displacement for test at 25°C. Producer Defined << empty cell >> No Data Producer defined -0.10217 3.24704 millimeters mu_25 Coefficient of friction at 25°C Producer Defined << empty cell >> No Data Producer defined -0.0156 0.2957 dZ_100_mm Axial displacement for test at 100°C Producer Defined -0.11509 4.00785 millimeters mu_100 Coefficient of friction at 100°C Producer Defined -0.0127 0.3434 dZ_200_mm Axial displacement for test at 200°C Producer Defined << empty cell >> No Data Producer defined -0.10696 3.50599 millimeters mu_200 Coefficient of friction at 200°C Producer Defined << empty cell >> No Data Producer defined -0.002 0.3453 dZ_300_mm Axial displacement for test at 300°C Producer Defined << empty cell >> No Data Producer defined -0.10711 2.32665 millimeters mu_300 Coefficient of friction at 300°C Producer Defined << empty cell >> No Data Producer defined -0.0442 0.3024 4_CCa-2_chlorite_friction.csv Comma Separated Value (CSV) file containing data. Producer Defined dz_25_mm Axial displacement for test at 25°C Producer Defined -0.18454 4.03768 millimeters mu_25 Coefficient of friction at 25°C Producer Defined -0.027 0.2396 dZ_100_mm Axial displacement for test at 100°C Producer Defined << empty cell >> No Data Producer defined -0.09915 3.95332 millimeters mu_100 Coefficient of friction at 100°C Producer Defined << empty cell >> No Data Producer defined -0.0117 0.265 dZ_200_mm Axial displacement for test at 200*C Producer Defined << empty cell >> No Data Producer defined -0.10432 4.01874 millimeters mu_200 Coefficient of friction at 200°C Producer Defined << empty cell >> No Data Producer defined -0.008 0.2607 dZ_300_mm Axial displacement for test at 300°C Producer Defined << empty cell >> No Data Producer defined -0.11088 2.37331 millimeters mu_300 Coefficient of friction at 300°C Producer Defined << empty cell >> No Data Producer defined -0.0451 0.2791 5_Russian_chlorite_friction.csv Comma Separated Value (CSV) file containing data. Producer Defined dZ_25_mm Axial displacement for test at 25°C Producer Defined << empty cell >> No Data Producer defined -0.11623 4.00601 millimeters mu_25 Coefficient of friction at 25°C Producer Defined << empty cell >> No Data Producer defined -0.0148 0.2123 dZ_100_mm Axial displacement for test at 100°C Producer Defined -0.10463 4.01865 millimeters mu_100 Coefficient of friction at 100°C Producer Defined -0.0133 0.2221 dZ_200_mm Axial displacement for test at 200°C Producer Defined << empty cell >> No Data Producer defined -0.10313 4.01975 millimeters mu_200 Coefficient of friction at 200°C Producer Defined << empty cell >> No Data Producer defined -0.007 0.2383 dZ_300_mm Axial displacement for test at 300°C Producer Defined << empty cell >> No Data Producer defined -0.10156 1.80618 millimeters mu_300 Coefficient of friction at 300°C Producer Defined << empty cell >> No Data Producer defined -0.0476 0.2359 U.S. Geological Survey - ScienceBase Diane E. Moore mailing address

Denver Federal Center

Building 810

Mail Stop 302

Denver CO 80225 1-888-275-8747 sciencebase@usgs.gov Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty. Digital Data https://doi.org/10.5066/P1LFJKQGZ None 20250820 Diane E Moore USGS - SOUTHWEST REGION Scientist Emerita mailing and physical

NASA AMES-Moffett Field, Moffett Field - Building 19

Moffett Field CA 94035 USA 6506437134 dmoore@usgs.gov FGDC Biological Data Profile of the Content Standard for Digital Geospatial Metadata FGDC-STD-001.1-1999