Moore, Diane E. McLaughlin, Robert J. Lienkaemper, James J. 20210817 csv files Menlo Park, CA U. S. Geological Survey https://doi.org/10.5066/P9OUFFKS Moore, Diane E. McLaughlin, Robert J. Lienkaemper, James J. 2018 The data consist of three tables of mineral compositions. Tectonics American Geophysical Union (Wiley) https://doi.org/10.1029/2018TC005307 An exposure of a creeping segment of the Bartlett Springs Fault (BSF), part of the San Andreas system in northern California, is a ~1.5 m-wide zone of serpentinite-bearing fault gouge cutting through late Pleistocene fluvial deposits. The fault gouge consists of porphyroclasts of antigorite serpentinite, talc, chlorite, and tremolite-actinolite, along with some Franciscan metamorphic rocks, in a matrix of the same materials. The Mg-mineral assemblage is stable at temperatures above 250°-300°C. The BSF gouge is interpreted to have been tectonically incorporated into the fault from depths near the base of the seismogenic zone, and to have risen buoyantly to the surface where it is now undergoing right-lateral displacement. The ultramafic-rich composition, frictional properties, and inferred mode of emplacement of the BSF serpentinitic gouge correspond to those of the creeping traces of the San Andreas Fault identified in the SAFOD (San Andreas Fault Observatory at Depth) drillhole. This suggests a common origin for creep at both locations. A tectonic model for the source of the ultramafic-rich materials in the BSF is proposed that potentially could explain the distribution of creep throughout the northernmost San Andreas system. Compositions of the minerals that comprise serpentinite-rich fault gouge within the Bartlett Springs Fault near Lake Pillsbury, California were obtained to determine the depth at which the gouge formed. Serpentine-mineral compositions from outcrops of Coast Range ophiolite in the same area were obtained for comparison to compositions of serpentine in the fault gouge. 2011 2018 publication date Complete None planned -122.99468993673 -122.89031981955 39.474365473569 39.36827914787 USGS Thesaurus fault zone serpentinite metasomatic rocks fault creep USGS Metadata Identifier USGS:5bdc8bc2e4b0b3fc5cf02c50 GNIS Lake Pillsbury Lake County California none none Diane Moore U. S. Geological Survey research geologist mailing and physical

345 Middlefield Road, MS/977

Menlo Park CA 94025 United States 6503294825 dmoore@usgs.gov The electron microprobe software applied a ZAF correction to the collected data. Reference standards were used to calibrate the instrument for quantitative analyses. The mineral standard set consists of feldspars (Si, Al, Ca, Na, K), natural olivines (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 runs, to check for drift in sample current. Precision of the microprobe data generally is ±1% for major and minor elements. The values fall within the expected ranges for the minerals that were analyzed. Data points that were not consistent with the the mineral being analyzed were removed from the data set. Data were removed because of low (anhydrous) oxide totals, obvious contamination, or unreasonable calculated structural formulae. Data set is considered complete for the information presented, as described in the abstract. 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 Field work and sample collection were conducted in 2010, 2014, 2015, and 2016. Thin sections were prepared from selected samples. 201608 Petrographic examination of thin sections was conducted at intervals between 2011 and 2016. Spots for microprobe analysis were marked on printouts of thin section scans. 2017 Raw mineral composition data were collected, in conjunction with analyses of similar materials from the San Andreas Fault Observatory at Depth, between 2011 and 2016. Data with very low anhydrous totals or obvious contamination (i.e., presence of elements that do not belong in the crystal structure). Remaining data were consolidated for structural formula calculations. 201604 Structural formula calculations were conducted. The calculations use the anhydrous oxygen content of a given mineral formula, and the total cation charge equals the anion (oxygen) charge (charge balance). Analyses that yielded unreasonable structural formulas were removed from the dataset. 2016 Table S1. Compositions of spinels in Bartlett Springs Fault Gouge. The table lists compositions of spinels contained in porphyroclasts within Bartlett Springs Fault gouge, obtained by standard electron microprobe (EPMA) techniques. It also contains the structural formula for the crystal that was calculated from the composition. producer defined Clast Type This column lists the dominant mineralogy of the porphyroclast that contains the analyzed spinel crystal. producer defined One or two mineral names, which are the most abundant minerals in the clast containing the spinel. SiO2 (wt%) The concentration of silicon oxide (SiO2) measured with the electron microprobe. Concentration values are reported in weight percent (wt%). producer defined 0.00 0.20 weight percent TiO2 (wt%) The concentration of titanium oxide (TiO2) measured with the electron microprobe. Concentration values are reported in weight percent (wt%). producer defined 0.00 0.35 weight percent Al2O3 (wt%) The concentration of aluminum oxide (Al2O3) measured with the electron microprobe. Concentration values are reported in weight percent (wt%). producere defined 5.50 25.50 weight percent Cr2O3 (wt%) The concentration of chromium oxide (Al2O3) measured with the electron microprobe. Concentration values are reported in weight percent (wt%). producer defined 41.00 58.60 weight percent Fe2O3 The concentration of ferric oxide (Fe2O3); values are reported in weight percent (wt%). The electron microprobe measures total iron concentrations. For spinels, the concentrations of ferric and ferrous iron were calculated from stoichiometry. producer defined 2.00 9.10 weight percent FeO (wt%) The concentration of ferrous oxide (FeO); values are reported in weight percent (wt%). The electron microprobe measures total iron concentrations. For spinels, the concentrations of ferric and ferrous iron were calculated from stoichiometry. producer defined. 15.25 19.80 weight percent NiO (wt%) The concentration of nickel oxide (NiO) measured with the electron microprobe. Concentration values are reported in weight percent (wt%). author produced 0.00 0.15 weight percent MnO (wt%) The concentration of manganese oxide (MnO) measured with the electron microprobe. Concentration values are reported in weight percent (wt%). producer defined 0.25 0.45 weight percent MgO (wt%) The concentration of magnesium oxide (MgO) measured with the electron microprobe. Concentration values are reported in weight percent (wt%). producer defined 7.50 12.50 weight percent CaO (wt%) The concentration of calcium oxide (CaO) measured with the electron microprobe. Concentration values are reported in weight percent (wt%). producer defined 0.00 0.05 weight percent Na2O (wt%) The concentration of sodium oxide (Na2O) measured with the electron microprobe. Concentration values are reported in weight percent (wt%). producer defined 0.00 0.10 weight percent K2O (wt%) The concentration of potassium oxide (K2O) measured with the electron microprobe. Concentration values are reported in weight percent (wt%). producer defined 0.00 0.01 weight percent Total (wt%) The total oxide concentrations measured by the electron microprobe. Concentration values are reported in weight percent (wt%). producer defined 98.00 99.50 weight percent Al The number of aluminum atoms in the calculated structural formula of the spinel crystal, calculated on the basis of 4 oxygen (O) atoms for the structural formula. producer defined 0.20 0.95 atoms Cr The number of chromium atoms in the calculated structural formula of the spinel crystal, calculated on the basis of 4 oxygen (O) atoms for the structural formula. producer defined 1.00 1.65 atoms Fe3+ The number of ferric-iron atoms in the calculated structural formula of the spinel crystal, calculated on the basis of 4 oxygen (O) atoms for the structural formula. The proportions of ferric and ferrous iron in the structural formula were estimated from stoichiometry, such that (Al + Cr + Fe3+) ~ 2.00 and (Fe + Mg + Mn) ~ 1.00. producer defined 0.05 0.22 atoms Fe2+ The number of ferrous-iron atoms in the calculated structural formula of the spinel crystal, calculated on the basis of 4 oxygen (O) atoms for the structural formula. The proportions of ferric and ferrous iron in the structural formula were estimated from stoichiometry, such that (Al + Cr + Fe3+) ~ 2.00 and (Fe + Mg + Mn) ~ 1.00. producer defined 0.40 0.60 atoms Mn The number of manganese atoms in the calculated structural formula of the spinel crystal, calculated on the basis of 4 oxygen (O) atoms for the structural formula. producer defined 0.01 0.01 atoms Mg The number of magnesium atoms in the calculated structural formula of the spinel crystal, calculated on the basis of 4 oxygen (O) atoms for the structural formula. atoms 0.40 0.60 atoms O The number of oxygen atoms in the calculated structural formula of the spinel crystal: (Al,Cr,Fe3+)2(Fe2+,Mn,Mg)O4. producer defined. 4 4 atoms Table S2. Compositions of minerals in Bartlett Springs fault gouge. The table lists compositions of Mg-rich minerals in porphyroclasts within Bartlett Springs Fault gouge, obtained by standard electron microprobe (EPMA) techniques. It also lists structural formulas, calculated from the composition data, as appropriate for each mineral. producer defined Mineral (composition) The name of the mineral whose composition is presented. Parenthetical phrases that follow some of the mineral names describe the occurrence of the mineral in the porphyroclast. producer defined Mineral names, followed for some entries by descriptions of the mineral occurrence contained in parentheses. SiO2 (wt%) The concentration of silicon oxide (SiO2) measured with the electron microprobe. Concentration values are reported in weight percent (wt%). producer defined 31.00 61.00 weight percent TiO2 (wt%) The concentration of titanium oxide (TiO2) measured with the electron microprobe. Concentration values are reported in weight percent (wt%). producer defined 0.00 0.50 weight percent Al2O3 (wt%) The concentration of aluminum oxide (Al2O3) measured with the electron microprobe. Concentration values are reported in weight percent (wt%). producer defined 0.10 16.70 weight percent Cr2O3 (wt%) The concentration of chromium oxide (Cr2O3) measured with the electron microprobe. Concentration values are reported in weight percent (wt%). producer defined 0.00 1.10 weight percent FeO (wt%) The concentration of iron oxide (FeO) measured with the electron microprobe. Total iron concentration values are reported as ferrous oxide (FeO) in weight percent (wt%). producer defined 2.00 16.50 weight percent NiO (wt%) The concentration of nickel oxide (NiO) measured with the electron microprobe. Concentration values are reported in weight percent (wt%). producer defined 0.02 0.25 weight percent MnO (wt%) The concentration of manganese oxide (MnO) measured with the electron microprobe. Concentration values are reported in weight percent (wt%). producer defined 0.02 0.50 weight percent MgO (wt%) The concentration of magnesium oxide (MgO) measured with the electron microprobe. Concentration values are reported in weight percent (wt%). producer defined 17.00 38.10 weight percent CaO The concentration of calcium oxide (CaO) measured with the electron microprobe. Concentration values are reported in weight percent (wt%). producer defined 0.00 12..20 weight percent Na2O (wt%) The concentration of sodium oxide (Na2O) measured with the electron microprobe. Concentration values are reported in weight percent (wt%). producer defined 0.00 0.50 weight percent K2O (wt%) The concentration of potassium oxide (K2O) measured with the electron microprobe. Concentration values are reported in weight percent (wt%). producer defined 0.00 0.10 weight percent Total (wt%) The total oxide concentrations measured by the electron microprobe; anhydrous totals. Concentration values are reported in weight percent (wt%). producer defined 84.40 98.00 weight percent Si The number of silicon atoms in the calculated structural formula of the crystal, calculated on the basis of the number of anhydrous* oxygen (O) atoms in the structural formula of the mineral (*excluding the oxygen in H2O). producer defined 3.00 8.00 atoms AlIV The number of aluminum atoms in the tetrahedral site of the calculated structural formula of the crystal. Calculations are made on the basis of the number of anhydrous* oxygen (O) atoms in the structural formula of the mineral (*excluding the oxygen in H2O). Aluminum atoms are first assigned to the tetrahedral site (indicated by the superscript IV), to fill the site occupancy. Any remaining aluminum is assigned to the octahedral site (indicated by the superscript VI). producer defined 0.00 0.90 atoms AlVI The number of aluminum atoms in the tetrahedral site of the calculated structural formula of the crystal. Calculations are made on the basis of the number of anhydrous* oxygen (O) atoms in the structural formula of the mineral (*excluding the oxygen in H2O). Aluminum atoms are first assigned to the tetrahedral site (indicated by the superscript IV), to fill the site occupancy. Any remaining aluminum is assigned to the octahedral site (indicated by the superscript VI). producer defined 0.00 1.10 atoms Ti The number of titanium atoms in the calculated structural formula of the crystal, calculated on the basis of the number of anhydrous* oxygen (O) atoms in the structural formula of the mineral (*excluding the oxygen in H2O). producer defined 0.00 0.05 atoms Cr The number of chromium atoms in the calculated structural formula of the crystal, calculated on the basis of the number of anhydrous* oxygen (O) atoms in the structural formula of the mineral (*excluding the oxygen in H2O). producer defined 0.00 0.10 atoms Fe The number of ferrous iron atoms in the calculated structural formula of the crystal, calculated on the basis of the number of anhydrous* oxygen (O) atoms in the structural formula of the mineral (*excluding the oxygen in H2O). Total iron concentrations are reported as ferrous iron. producer defined 0.15 1.40 atoms Ni The number of nickel atoms in the calculated structural formula of the crystal, calculated on the basis of the number of anhydrous* oxygen (O) atoms in the structural formula of the mineral (*excluding the oxygen in H2O). producer defined 0.00 0.02 atoms Mn The number of manganese atoms in the calculated structural formula of the crystal, calculated on the basis of the number of anhydrous* oxygen (O) atoms in the structural formula of the mineral (*excluding the oxygen in H2O). producer defined 0.00 0.05 atoms Mg The number of magnesium atoms in the calculated structural formula of the crystal, calculated on the basis of the number of anhydrous* oxygen (O) atoms in the structural formula of the mineral (*excluding the oxygen in H2O). producer defined 2.60 5.50 atoms Ca The number of calcium atoms in the calculated structural formula of the crystal, calculated on the basis of the number of anhydrous* oxygen (O) atoms in the structural formula of the mineral (*excluding the oxygen in H2O). producer defined 0.00 1.90 atoms Na The number of sodium atoms in the calculated structural formula of the crystal, calculated on the basis of the number of anhydrous* oxygen (O) atoms in the structural formula of the mineral (*excluding the oxygen in H2O). producer defined 0.00 0.15 atoms K The number of potassium atoms in the calculated structural formula of the crystal, calculated on the basis of the number of anhydrous* oxygen (O) atoms in the structural formula of the mineral (*excluding the oxygen in H2O). producer defined 0.00 0.01 atoms O The number of anhydrous* oxygen atoms in the calculated structural formula of the crystal (*excluding the oxygen in H2O). producer defined 11 23 atoms Table S3. Coast Range ophiolite serpentine compositions. The table lists compositions of serpentine minerals from the Coast Range ophiolite in the vicinity of the Bartlett Springs fault at Lake Pillsbury, obtained by standard electron microprobe (EPMA) techniques. It also lists the structural formula for each mineral analysis, calculated from the composition data. producer defined Occurrence The texture of the analyzed serpentine mineral in the sample. producer defined a term that describes the occurrence of the mineral (mesh or bastite texture, or a vein mineral). SiO2 (wt%) The concentration of silicon oxide (SiO2) measured with the electron microprobe. Concentration values are reported in weight percent (wt%). producer defined 40.4 42.3 weight percent TiO2 (wt%) The concentration of titanium oxide (TiO2) measured with the electron microprobe. Concentration values are reported in weight percent (wt%). producer defined 0.00 0.01 weight percent Al2O3 (wt%) The concentration of aluminum oxide (Al2O3) measured with the electron microprobe. Concentration values are reported in weight percent (wt%). producer defined 0.60 1.60 weight percent Cr2O3 (wt%) The concentration of chromium oxide (Cr2O3) measured with the electron microprobe. Concentration values are reported in weight percent (wt%). producer defined 0.01 0.03 weight percent FeO (wt%) The concentration of iron oxide (FeO) measured with the electron microprobe. Total iron concentration values are reported as ferrous oxide (FeO) in weight percent (wt%). producer defined 3.30 4.50 weight percent NiO (wt%) The concentration of nickel oxide (NiO) measured with the electron microprobe. Concentration values are reported in weight percent (wt%). producer defined 0.10 0.35 weight percent MnO (wt%) The concentration of manganese oxide (MnO) measured with the electron microprobe. Concentration values are reported in weight percent (wt%). producer defined 0.01 0.15 weight percent MgO (wt%) The concentration of magnesium oxide (MgO) measured with the electron microprobe. Concentration values are reported in weight percent (wt%). producer defined 36.00 37.20 weight percent CaO (wt%) The concentration of calcium oxide (CaO) measured with the electron microprobe. Concentration values are reported in weight percent (wt%). producer defined 0.02 0.05 weight percent Na2O (wt%) The concentration of sodium oxide (Na2O) measured with the electron microprobe. Concentration values are reported in weight percent (wt%). producer defined 0.02 0.05 weight percent K2O (wt%) The concentration of potassium oxide (K2O) measured with the electron microprobe. Concentration values are reported in weight percent (wt%). producer defined 0.00 0.01 weight percent Total (wt%) The total oxide concentrations measured by the electron microprobe; anhydrous totals. Concentration values are reported in weight percent (wt%). producer defined 83.40 84.40 weight percent Si The number of silicon atoms in the calculated structural formula of the serpentine crystal, calculated on the basis of the number of anhydrous* oxygen (O) atoms in the structural formula of the mineral (*excluding the oxygen in H2O). producer defined 3.95 4.10 atoms AlIV The number of aluminum atoms in the tetrahedral site of the calculated structural formula of the crystal. Calculations are made on the basis of the number of anhydrous* oxygen (O) atoms in the structural formula of the mineral (*excluding the oxygen in H2O). Aluminum atoms are first assigned to the tetrahedral site (indicated by the superscript IV), to fill the site occupancy. Any remaining aluminum is assigned to the octahedral site (indicated by the superscript VI). producer defined 0.00 0.05 atoms ALVI The number of aluminum atoms in the tetrahedral site of the calculated structural formula of the serpentine crystal. Calculations are made on the basis of the number of anhydrous* oxygen (O) atoms in the structural formula (*excluding the oxygen in H2O). Aluminum atoms are first assigned to the tetrahedral site (indicated by the superscript IV), to fill the site occupancy. Any remaining aluminum is assigned to the octahedral site (indicated by the superscript VI). producer defined 0.10 0.15 atoms Cr The number of chromium atoms in the calculated structural formula of the serpentine crystal, calculated on the basis of the number of anhydrous* oxygen (O) atoms in the structural formula of the mineral (*excluding the oxygen in H2O). producer defined 0.00 0.10 atoms Fe The number of ferrous iron atoms in the calculated structural formula of the crystal, calculated on the basis of the number of anhydrous* oxygen (O) atoms in the structural formula of the mineral (*excluding the oxygen in H2O). Total iron concentrations are reported as ferrous iron. Total iron concentrations are reported as ferrous iron. producer defined 0.25 0.40 atoms Ni The number of nickel atoms in the calculated structural formula of the serpentine crystal, calculated on the basis of the number of anhydrous* oxygen (O) atoms in the structural formula (*excluding the oxygen in H2O). producer defined 0.01 0.02 atoms Mn The number of manganese atoms in the calculated structural formula of the serpentine crystal, calculated on the basis of the number of anhydrous* oxygen (O) atoms in the structural formula (*excluding the oxygen in H2O). producer defined 0.00 0.01 atoms Mg The number of magnesium atoms in the calculated structural formula of the serpentine crystal, calculated on the basis of the number of anhydrous* oxygen (O) atoms in the structural formula (*excluding the oxygen in H2O). producer defined 5.25 5.45 atoms Ca The number of calcium atoms in the calculated structural formula of the serpentine crystal, calculated on the basis of the number of anhydrous* oxygen (O) atoms in the structural formula (*excluding the oxygen in H2O). producer defined 0.00 0.01 atoms Na The number of sodium atoms in the calculated structural formula of the serpentine crystal, calculated on the basis of the number of anhydrous* oxygen (O) atoms in the structural formula (*excluding the oxygen in H2O). producer defined 0.00 0.01 atoms O The number of anhydrous* oxygen atoms in the calculated structural formula of the crystal (*excluding the oxygen in H2O). O = 14 for the serpentine-mineral structural-formula calculations. producer defined 14 14 atoms U.S. Geological Survey - ScienceBase mailing and physical

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Denver CO 80225 USA 1-888-275-8747 sciencebase@usgs.gov The spinel compositions in Table S1 are presented in Figure 5 of Moore et al. (2018). The mineral compositions in Table S2 (serpentine, talc, chlorite, and tremolite-actinolite) are used top define the compositional ranges for those minerals in Figures 8 and 10 of Moore et al. (2018). The serpentine mineral compositions are described, and some oxides listed, in the section on Coast Range ophiolite rocks (section 4) of Moore et al. (2018). These tables are also included as supplementary materials associated with the published paper. All data are contained in .csv files. 20210817 Moore USGS research geologist mailing and physical

345 Middlefield Road Mail Stop 977

Menlo Park CA 94025 United States 6503294825 dmoore@usgs.gov Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998