Hope L. Ianiri Nancy G. Prouty Amy Gartman 20250218 comma-delimited text data release DOI:10.5066/P13XVXQC Pacific Coastal and Marine Science Center, Santa Cruz, California U.S. Geological Survey https://doi.org/10.5066/P13XVXQC Hope L. Ianiri Nancy G. Prouty Pamela L. Campbell Amy Gartman Katlin B. Adamczyk Jaycee J. Favela 2025 data release DOI:10.5066/P13XVXQC Pacific Coastal and Marine Science Center, Santa Cruz, CA U.S. Geological Survey Suggested Citation: Ianiri, H.L., Prouty, N.G., Campbell, P.L., Gartman, A., Adamczyk, K.B., and Favela, J.J., 2025, Sedimentary organic geochemistry data from Escanaba Trough, off the coast of northern California, collected May-June 2022: U.S. Geological Survey data release, https://doi.org/10.5066/P13XVXQC. https://doi.org/10.5066/P13XVXQC Bulk organic geochemistry data were determined on one to five cm subsamples of sediment push cores collected from the Escanaba Trough during May to June 2022. These data include percent total organic carbon (percent TOC ), total nitrogen (percent TN), carbon to nitrogen ratios (C/N), stable carbon isotope ratios (d13C), stable nitrogen isotope ratios (d15N), radiocarbon values (D14C), and grain size (mean phi). Location information (for example , latitude, longitude, and depth) is also reported. Data were obtained to assess organic carbon storage, reactivity, and cycling within sediments of the Escanaba Trough, a hydrothermal spreading center which contains critical minerals. This work aids our understanding of the geochemistry of marine mineral host sediments and hydrothermal vent processes throughout the global ocean. Additional information about the field activity or activities from which these data were derived is available online at: https:// https://cmgds.marine.usgs.gov/fan_info.php?fan=2022-621-FA Escanaba Trough: Exploring the Seafloor and Oceanic Footprints is an interagency effort involving the National Oceanic and Atmospheric Administration, the U.S. Geological Survey, and the Bureau of Ocean Energy Management. Funding is acknowledged from NOAA Ocean Exploration via its Ocean Exploration Fiscal Year 2019 Funding Opportunity and through the National Oceanographic Partnership Program (NOPP), from the USGS Coastal and Marine Hazards and Resources Enhanced Funding Opportunities, and from the Bureau of Ocean Energy Management through Interagency Agreement M19PG00021 with the United States Geological Survey. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. 20220531 20220611 Ground condition at time data were collected. Complete None planned -127.53618710 -127.44714953 41.08222461 40.69569198 ISO 19115 Topic Category environment oceans geoscientificInformation Data Categories for Marine Planning Nonliving resources Mineral resources Physical/Chemical features Substrate USGS Thesaurus push coring light stable isotope analysis carbon-14 analysis subsampling geochemistry marine geology Marine Realms Information Bank (MRIB) keywords petroleum resources carbon cycle seep and vent ecosystems chemical analysis sediment geochemistry None U.S. Geological Survey USGS Coastal and Marine Hazards and Resources Program CMHRP Pacific Coastal and Marine Science Center PCMSC USGS Metadata Identifier USGS:6696de49d34ecb78f609f77a Geographic Names Information System (GNIS) Pacific Ocean NGA GEOnet Names Server (GNS) Escanaba Trough No access constraints USGS-authored or produced data and information are in the public domain from the U.S. Government and are freely redistributable with proper metadata and source attribution. Please recognize and acknowledge the U.S. Geological Survey as the originator(s) of the dataset and in products derived from these data. U.S. Geological Survey, Pacific Coastal and Marine Science Center PCMSC Science Data Coordinator mailing and physical

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Santa Cruz CA 95060 831-427-4747 pcmsc_data@usgs.gov Colin Carney and Dyke Andreason at the University of California, Santa Cruz Stable Isotope Laboratory measured ratios of stable isotopes of carbon 13/12 and nitrogen 15/14, total organic carbon, and total nitrogen. Roberta Hansman and Kathy Elder at NOSAMS (National Ocean Sciences Accelerator Mass Spectrometry) measured ratios of carbon 14/12. Geochemical data are tabulated in comma separated variable (CSV) format. Hope L. Ianiri Pamela L. Campbell Amy Gartman Nancy G. Prouty 2025 Ianiri, H.L., Campbell, P., Gartman, A., and Prouty, N.G., 2025, Characterizing sedimentary organic carbon in a hydrothermal spreading center, the Escanaba Trough: Chemical Geology, https://doi.org/10.1016/j.chemgeo.2025.122679 https://doi.org/10.1016/j.chemgeo.2025.122679 Minze Stuvier Henry A. Polach 1977 Stuiver, M., Polach, H.A., 1977. Discussion Reporting of 14C Data. Radiocarbon 19, 355-363. https://doi.org/10.1017/S0033822200003672 J. L. Morton Robert A. Zierenberg Carol A. Reiss 1994 Morton, J.L., Zierenberg, R.A., Reiss, C.A., 1994. Geologic, hydrothermal, and biologic studies at Escanaba Trough: an introduction, in: Geologic, Hydrothermal, and Biologic Studies at Escanaba Trough, Gorda Ridge, Offshore Northern California. U.S. Geological Survey. David. A. Clague Robert A. Zierenberg Jennifer B. Paduan David W. Caress Brian L. Cousens Brian M. Dreyer Alice S. Davis James McClain Stephanie L. Ross 2022 Clague, D.A., Zierenberg, R.A., Paduan, J.B., Caress, D.W., Cousens, B.L., Dreyer, B.M., Davis, A.S., McClain, J., Ross, S.L., 2022. Emplacement and impacts of lava flows and intrusions on the sediment-buried Escanaba Segment of the Gorda mid-ocean ridge. Journal of Volcanology and Geothermal Research 432, 107701. https://www.sciencedirect.com/science/article/pii/S0377027322002323 Analytical precision of stable isotope ratios relative to internationally calibrated in-house reference materials (Vienna PeeDee Belemnite for d13C and air for d15N). was less than 0.1 per mil for d13C values and 0.2 per mil for d15N values. Precision of total organic carbon was 2.5 micrograms carbon, which corresponds to less than 0.06 percent based on the amounts analyzed. Precision of total nitrogen was less than 0.5 microgram nitrogen, which corresponds to less than 0.003 percent based on the amounts analyzed. 14C measurements at NOSAMS are checked for accuracy via the primary standard NBS Oxalic Acid I (NIST-SRM-4990). Every group of samples processed includes an appropriate blank, analyzed concurrently. Error in D14C values was less than 1.5 per mil. No formal logical accuracy tests were conducted. Dataset is considered complete for the information presented as described in the abstract. Some samples were not analyzed for radiocarbon or grain size. Users are advised to read the rest of the metadata record carefully for additional details. The horizontal accuracy for each sample was obtained from the ROV's Ultra Short Baseline Positioning System (USBL) navigation after calibration to the CASIUS (Calibration of Attitude Sensors In USBL Systems) calibration system. Accuracy for this depth is approximately 10-20 m. The vertical accuracy was determined using multiple DVLs (Doppler Velocity Loggers) on the ROV, which are accurate to less than 1 m. SEDIMENT COLLECTION. Samples were collected aboard the R/V Thomas Thompson via push coring using the ROV Jason. Once recovered shipboard, pore waters were extracted via rhizon samplers, cores were subsectioned into one to five cm slices, the exterior sediment which was in contact with the core liner was removed, and remaining sediment was stored frozen in pre-combusted glass jars. 20220611 RATIOS OF STABLE ISOTOPES OF CARBON 13/12 (d13C), NITROGEN (d15N), TOTAL ORGANIC CARBON, and TOTAL NITROGEN (C:N): Dried and homogenized sediment was analyzed for TOC, TN, d13C, and d15N values using a CE Instruments NC2500 elemental analyzer (EA) coupled to a Thermo Scientific DELTAplus XP isotope ratio mass spectrometer (IRMS) via a Thermo Scientific Conflo III at the University of California at Santa Cruz Stable Isotope Lab. Inorganic carbonates were removed from the samples analyzed for d13C/percent TOC via direct addition of 400 uL of sulfurous acid. Stable isotope ratios were corrected for size, drift, and source stretching effects. 20240301 Colin Carney Stable Isotope Lab at the University of California at Santa Cruz Associate Specialist Mailing

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Santa Cruz CA 95064 831-459-5751 cpcarney@ucsc.edu RADIOCARBON ANALYSES: Dried and homogenized sediment was analyzed for D14C ratios via accelerator mass spectrometry (AMS) using a custom built continuous flow AMS system at the National Ocean Sciences AMS (NOSAMS). Bulk sediment samples were acidified to remove inorganic carbon prior to analysis via addition of 1.2M HCl. 20221201 Roberta Hansman NOSAMS Research Specialist, Staff Chemist mailing and physical

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Woods Hole MA 02543 508-289-2332 nosams@whoi.edu point point 69 0.00000001 0.0000001 Decimal degrees D_WGS_1984 WGS84 6378137.0000 298.2572 EscanabaTrough_organicgeochem_bulk.csv Table containing bulk organic geochemistry data. producer defined Cruise_ID Lists the alphanumeric cruise identifier for the expedition during which the sample was collected. producer defined TN403 Cruise identification affiliated with Field Activity 2022-621-FA producer defined Sample_ID Name of sample producer defined The sample names include a dive number (J2, denoting Jason2, followed by a number), push core number (PC, denoting push core, followed by a number) and the sediment depth horizon (X-Y). Latitude Latitude of the sample in decimal degrees producer defined 40.69569198 41.08222461 decimal degrees 0.00000001 Longitude Longitude of sample in decimal degrees producer defined -127.5361871 -127.4471495 decimal degrees 0.0000001 Water_depth_m Water depth in meters at which the sample was collected. producer defined 3222 3285 meters 1 Location Location where the sample was collected producer defined Central Hill Text descriptor of sampling site as defined in the literature Morton and others (1994), Clague and others (2022) Edifice Rex West Text descriptor of sampling site as defined in the literature Morton and others (1994), Clague and others (2022) Edifice Rex East Text descriptor of sampling site as defined in the literature Morton and others (1994), Clague and others (2022) SESCA S3A Text descriptor of sampling site as defined in the literature Morton and others (1994), Clague and others (2022) SESCA Waypoint 2 S2A Text descriptor of sampling site as defined in the literature Morton and others (1994), Clague and others (2022) MESCA Text descriptor of sampling site as defined in the literature Morton and others (1994), Clague and others (2022) sediment_depth_top_cm top depth of core subsample. Ex: a sediment core slice from 0-1 cm would have a top depth of 0 centimeters and a bottom depth of 1 centimeter. producer defined 0 20 centimeters 1 sediment_depth_bottom_cm bottom depth of core subsample. Ex: a sediment core slice from 0-1 cm would have a top depth of 0 centimeters and a bottom depth of 1 centimeter. producer defined 1 22 centimeters 1 TOC_percent percent total organic carbon: weight percent of total sediment which is organic carbon. producer defined 0.26 1.75 percent 0.01 TN_percent percent total organic nitrogen: weight percent of total sediment which is organic nitrogen. producer defined 0.02 0.22 percent 0.01 CN atomic ratio of total organic carbon to total nitrogen. Calculated as C/N atomic = C:N (wt:wt) * 14.0067 micrograms N / 12.0107 micrograms C. producer defined 7.9 16.8 unitless 0.1 d13C ratio of stable carbon 13/12 isotopes of sedimentary organic carbon after removal of inorganic carbon. producer defined -25.6 -21.4 standard per mil notation 0.1 d15N ratio of stable nitrogen 15/14 isotopes of sedimentary nitrogen. producer defined 0.85 9.48 standard per mil notation 0.01 D14C ratio of stable carbon 14/12 isotopes of sedimentary organic carbon. D14C is defined as in Stuiver and Pollach (1977) as the relative difference between the absolute international standard (base year 1950) and sample activity corrected for age and d13C. The value is age corrected to account for decay that took place between collection (or death) of the sample and the time of sample measurement so that measurements of the same sample made years apart will produce the same calculated D14C result. -9999 indicates sample was not analyzed for radiocarbon. producer defined -741.9 -303.7 standard per mil notation 0.1 D14C_err error associated with D14C values. An internal statistical error is calculated using the total number of 14C counts (n) measured for each target and an external error is calculated from the reproducibility of multiple exposures for a given target. The ratio of carbon 14/12 isotopes of a sample was measured 10 separate times over the course of a run. The final reported error is the larger of the internal or external error, propagated with errors from the normalizing standards and blank subtraction. -9999 indicates sample was not analyzed for radiocarbon. producer defined 1.2 2.2 standard per mil notation 0.1 OS-number NOSAMS accession number NOSAMS Identification number assigned by NOSAMS to each radiocarbon measurement made. The first line of the csv file is a header line. U.S. Geological Survey U.S. Geological Survey - ScienceBase mailing and physical

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Denver CO 80225 1-888-275-8747 sciencebase@usgs.gov These data are available in a single csv file (EscanabaTrough_organicgeochemistry_bulk.csv). 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 on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. comma-delimited text Microsoft Excel Version 2308 Build 16731.20716 Click-to-Run csv file No compression applied 0.0364 https://www.sciencebase.gov/catalog/file/get/668f0246d34e4f2ebb745682 https://www.sciencebase.gov/catalog/item/668f0246d34e4f2ebb745682 https://doi.org/10.5066/P13XVXQC Data and metadata can be downloaded using the Network_Resource_Name links. The first link is a direct link to download a zipped file of data and metadata. The second link points to a landing page with metadata and data. The third link points to the landing page for the entire data release. None. These data can be viewed with Microsoft Excel or any text reading software. 20250218 U.S. Geological Survey, Pacific Coastal and Marine Science Center PCMSC Science Data Coordinator mailing and physical

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Santa Cruz CA 95060 831-427-4747 pcmsc_data@usgs.gov Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998