Jacob T. Murchek James M. DeGraff Benjamin J. Drenth 20250306 1.0 CSV Reston, VA U.S. Geological Survey Additional information about originators: Jacob T. Murchek, https://orcid.org/0009-0006-1765-5646; James M. DeGraff, https://orcid.org/0009-0004-3800-969X; Benjamin J. Drenth, https://orcid.org/0000-0002-3954-8124; Bibliographic Reference: Murchek, J.T., DeGraff, J.M., and Drenth, B.J., 2024, Gravity data in the Upper Peninsula, Michigan for geophysical profile modeling of the Midcontinent Rift System and associated structures, U.S. Geological Survey data release, DOI: https://doi.org/10.5066/P14BGVCT https://doi.org/10.5066/P14BGVCT Gravity data were collected from 2022 through 2024 to provide more detailed data for geophysical profile modeling of the Midcontinent Rift System and associated structures. This data release provides the complete Bouguer anomaly gravity data for 256 new gravity stations to supplement existing data and replace erroneous existing data. The purpose is to release these data for public use. These data were acquired to aid in geophysical modeling of the Midcontinent Rift System and its associated structures. File contains data available in comma separated value (.csv) format. The user must have software capable of opening and viewing a .csv file. 20221022 20240910 ground condition Complete None planned -89.5000 -87.5000 47.4900 46.1000 ISO 19115 Topic Category geoscientificInformation None - Free Keywords U.S. Geological Survey USGS Mineral Resources Program MRP Geology, Energy & Minerals Science Center GEMSC Lacoste Romberg gravimeter Gravity measurement USGS Thesaurus bouguer anomaly free-air anomaly gravitational field (earth) USGS Metadata Identifier USGS:67055321d34edddc3ed251f5 Geographic Names Information System (GNIS) Michigan Keweenaw County Houghton County Ontonagon County Baraga County Gogebic County None. Please see 'Distribution Info' for details. None. Users are advised to read the dataset's metadata thoroughly to understand appropriate use and data limitations. Jacob T Murchek USGS - Northeast Region Physical Scientist mailing

12201 Sunrise Valley Drive

Reston VA 20192 USA 219-308-8758 jmurchek@usgs.gov Michigan Technological University; Houghton, Michigan, 49931 No formal attribute accuracy tests were conducted No formal logical accuracy tests were conducted 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 U.S. Geological Survey 3D Elevation Program 2019 raster digital data U.S. Geological Survey, 2019, 3D Elevation Program 1-Meter Resolution Digital Elevation Model, accessed August 2024 at URL: https://apps.nationalmap.gov/downloader. https://apps.nationalmap.gov/downloader. Digital and/or Hardcopy 2019 observed USGS 3DEP Sampled elevations for KP1 gravity stations from lidar I.M. Longman 19591201 publication Longman, I.M., 1959, Forumlas for Computing the Tidal Accelerations Due to the Moon and the Sun, Journal of Geophysical Research, vol. 64, no. 12, pp. 2351-2355. https://doi.org/10.1029/JZ064i012p02351 Digital and/or Hardcopy 1959 publication date Longman, 1959 Equations for earth's tide corrections Zachary P. Brady John R. Leeman 2018 0.5.0 Python Script Brady, Z.P, and Leeman, J.R., 2018, TideGravity python library, tidegravity - PyPI. https://pypi.org/project/tidegravity Digital and/or Hardcopy 2018 publication date Brady and Leeman, 2018 Source code for computing earth's tide corrections for each gravity station. C. Morelli 1974 publication Paris, France International Association of Geodesy Morelli, C., ed., 1974, The International Gravity Standardization Net (IGSN) 1971: International Association of Geodesy Special Publication no.4, 194 p. Digital and/or Hardcopy 1974 publication date Morelli, 1974 Datum for observed gravity data Richard J. Blakely 1995 Book New York, United States Cambridge University Press Blakely, R.J., 1995, Potential Theory in Gravity and Magnetic Applications, Cambridge University Press, 441 p. Digital and/or Hardcopy 1995 publication date Blakely, 1995 Provides equations for free-air and Bouguer corrections International Association of Geodesy 1971 publication International Association of Geodesy, 1971, Geodetic reference system 1967: International Association of Geodesy Special Publication No. 3, 116 p. Digital and/or Hardcopy 1971 publication date International Association of Geodesy, 1971 Theoretical gravity calculation Donald Plouff 19770718 publication Open-File Report 77-535 Denver, CO USGS Plouff, D., 1977, Preliminary documentation for a FORTRAN program to compute gravity terrain corrections based on topography digitized on a geographic grid: U.S. Geological Survey Open-File Report 77-535,45 p. https://doi.org/10.3133/ofr77535 Digital and/or Hardcopy 1977 publication date Plouff, 1977 Terrain corrections Gravity data in this study were acquired using a Lacoste and Romberg G-model gravimeter. A Trimble Geo-7x GNSS unit was used to measure the horizontal and vertical position of each station in the KP0 and KP2 profiles. Profile KP1 vertical positions were sampled from one-meter digital elevation models (USGS, 2019) using horizontal locations from the Trimble Geo7x. The location information was processed using Trimble Pathfinder software. Absolute gravity base stations in Calumet, Houghton, and Ontonagon, Michigan were used for absolute control. The error levels in these published data are expected to be less than 0.1 mGal. USGS 3DEP 20240910 Factory calibration constants are provided by Lacoste and Romberg for each meter to make the conversion to milligals. Theoretical gravity was calculated for each station at sea-level and is based on the Geodetic Reference System of 1967 (International Association of Geodesy, 1971) for the shape of the spheroid. The gravity data were corrected for variations in earth's tide (Longman, 1959) using python script 'tidegravity' (Brady and Leeman, 2018) and meter drift using a linear drift between successive absolute base station readings. The International Gravity Standardization Net 1971 (IGSN 71) (Morelli, 1974) is the datum for the observed gravity data. The free-air anomaly was calculated by subtracting the theoretical gravity from the observed gravity and adding the free-air correction using standard formulas (Blakely, 1995). The simple Bouguer anomaly was calculated by subtracting the Bouguer correction from the free-air anomaly to account for the mass effect of rocks between the station and sea-level using a rock density of 2.67 g/cm3 (e.g., Blakely, 1995). Longman, 1959 Brady and Leeman, 2018 Morelli, 1974 Blakely, 1995 International Association of Geodesy, 1971 20240910 Software based on Plouff's (1977) gravity correction program was used to calculate standard inner and outer zone terrain corrections. The inner zone correction extends 895 meters from the gravity station and is based on publicly available 10-meter digital elevation models. For the outer zone correction, multiple resolution digital elevation models were used to calculate the correction from 895 meters to 166.7 kilometers. The inner and outer zone terrain corrections were added to the simple Bouguer anomaly to calculate the complete Bouguer anomaly. Plouff, 1977 20240910 0.00001 0.00001 Decimal degrees North American Datum of 1983 (NAD 83) Geodetic Reference System 1980 6378137.000000 298.257222 North American Vertical Datum of 1988 0.5 meters Explicit elevation coordinates included with horizontal coordinates Final_GravityData.csv Comma Separated Value (CSV) file containing data. U.S. Geological Survey Station Gravity Station identifier U.S. Geological Survey Gravity station identification numbers. 'KP' refers to Keweenaw Peninsula. The numbers following 'KP' are the associated profile and station identifier. Lat_NAD83 Latitude in decimal degrees, NAD83 U.S. Geological Survey 46.163646 47.480302 Decimal Degree Lon_NAD83 Longitude in decimal degrees, NAD83 U.S. Geological Survey -89.412257 -87.918092 Decimal Degree Elev_m_NAVD88 Elevation in meters, NAVD88 datum U.S. Geological Survey 183.135 530.004 Meters ObsGrav Observed Gravity in milligals U.S. Geological Survey 980592.246 980802.79 Milligal TheoGrav Theoretical Gravity in milligals U.S. Geological Survey 980725.224 980844.18 Milligal FAC Free-Air Correction in milligals U.S. Geological Survey 56.516 163.559 Milligal FAA Free-Air Anomaly in milligals U.S. Geological Survey -67.91 41.872 Milligal BSC Bouguer-Slab Correction in milligals, assumes density of 2.67 g/cm3 U.S. Geological Survey 20.503 59.336 Milligal SBA Simple-Bouguer Anomaly in milligals, assumes density of 2.67 g/cm3 U.S. Geological Survey -89.156 20.068 Milligal OTC Outer zone Terrain Correction in milligals, assumes density of 2.67 g/cm3 U.S. Geological Survey -0.102 1.679 Milligal ITC Inner zone Terrain Correction in milligals, assumes density of 2.67 g/cm3 U.S. Geological Survey 0.0002 1.8345 Milligal CBA Complete Bouguer Anomaly in milligals, assumes density of 2.67 g/cm3 U.S. Geological Survey -88.591 19.973 Milligal U.S. Geological Survey GS ScienceBase mailing address

Denver Federal Center, Building 810, Mail Stop 302

Denver CO 80225 United States 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. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Digital Data https://doi.org/10.5066/P14BGVCT None 20250306 Jacob T Murchek USGS - Northeast Region Physical Scientist mailing

12201 Sunrise Valley Drive

Reston VA 20192 USA 219-308-8758 jmurchek@usgs.gov FGDC Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998