Ryan Deasy Ryan McAleer Michael J. Kunk Robert Wintsch Romain Meyer 20250825 spreadsheet Reston, VA U.S. Geological Survey https://doi.org/10.5066/P1KR5E7F This data release contains geochemical data, thin section images, and 40Ar/39Ar isotopic data from bedrock samples in the Orange-Milford Belt of south-central Connecticut. The geochemical data comprise whole-rock major oxide and trace element abundances in 111 samples. Pairs of images in plane-polarized light and cross-polarized light are included for 90 thin sections. Step-heated 40Ar/39Ar analyses of mineral separates/concentrates from 10 different hand samples are also included and comprise 8 analyses of muscovite/sericite, 3 analyses of potassium feldspar, and 2 analyses of actinolite. Bedrock chemistry provides a primary control on the distribution of economic resources including critical mineral deposits. These data were collected in the course of bedrock mapping of the New Haven, Ansonia, and Milford quadrangles to support resource identification, economic development, infrastructure planning, and topical studies such as tectonic reconstructions. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. 20220101 20241101 ground condition Complete None planned -73.1004 -72.9550 41.3765 41.1837 ISO 19115 Topic Category geoscientificInformation None U.S. Geological Survey USGS FBGC 40Ar/39Ar Bascom Argon Dating Laboratory Geochronology Petrogenesis Geochemistry Petrography USGS Metadata Identifier USGS:6875053dd4be025f81987b93 None Connecticut New England 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. Ryan Deasy U.S. Geological Survey, Northeast Region Research Geologist mailing address

12201 Sunrise Valley Dr

Mail Stop 926A

Reston VA 20192 US 703-648-6897 703-648-6953 rdeasy@usgs.gov These data have been peer reviewed and compared with related ancillary data. Detection limits given for analytes measured by INAA at Bureau Veritas Commodities Canada Ltd. are those reported in the tabulated results. Detection limits given for analytes measured by ICP-ES at Bureau Veritas Commodities Canada Ltd. are those reported in the company's schedule of services. Detection limits given for analytes measured by XRF at Analytical Laboratories, Brigham Young University are those reported by the instrument manufacturer, as available. Detection limits of all other elements, including those measured by ICP-MS at the University of Bergen, are not available (NA). Data were reviewed for consistency and analyses/results were checked for validity and fidelity of relationships. 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. All data as part of this collection were included in this data release for the region and time period specified in this metadata. No formal positional accuracy tests were conducted No formal positional accuracy tests were conducted Ryan J. McAleer 2017 publication Digital and/or Hardcopy 2017 publication date McAleer and others (2017) radiation geometry description E. C. Alexander 1978 publication Digital and/or Hardcopy 1978 publication date Alexander and others (1978) MMHB Ar/Ar dating standard G. B. Dalrymple 1981 publication Digital and/or Hardcopy 1981 publication date Dalrymple and others (1981) interfering isotope values A. O. Nier 1950 publication Digital and/or Hardcopy 1950 publication date Nier (1950) argon isotopic composition of Earth's atmosphere R. H. Steiger 1977 publication Digital and/or Hardcopy 1977 publication date Steiger and Jäger (1977) decay constants Ralph A. Haugerud 1988 publication Digital and/or Hardcopy 1988 publication date Haugerud and Kunk (1988) data reduction program K. R. Ludwig 2012 publication Digital and/or Hardcopy 2012 publication date Ludwig (2012) plotting program T. Staudacher 1978 publication Digital and/or Hardcopy 1978 publication date Staudacher and others (1978) description of furnace characteristics 40Ar/39Ar Sample Preparation and Characterization: Mineral separation and argon analyses were done in the Bascom Argon Dating (BARD) laboratory at the U.S Geological Survey (USGS) in Reston, VA. Rocks were sampled in the field by Ryan Deasy or Robert Wintsch. Sample "ZH1B" is of a quartz-muscovite vein and sample "AmZ peg" is a pegmatitic cobble from conglomerate. These samples were gently ground by hand and the minerals of interest were then hand picked. Sample "AmZ many" is of hand-picked K-feldspar cleavage fragments from conglomerate. No additional processing was required for these samples. The remainder of the samples were crushed using a Sturtevant jaw crusher and ground to a medium to coarse sand size using a Bico direct drive disk mill. The samples were then sieved to a narrow size fraction, typically 100-120 mesh (125-149 micrometers) and the size fraction was rinsed to remove dust and then dried in an oven at ~70C. A Frantz L1 isodynamic separator, organic heavy liquids (mixtures of Methylene Iodide, Bromoform, and Benzyl Benzoate), and ultrasonic cleaning were then used iteratively, and followed by a final stage of hand picking until mineral separates with an optical purity >99.9% for actinolite, and >99% for k-feldspar and muscovite were obtained. Paper shaking was also used to concentrate muscovite. K-feldspar purity was evaluated by immersing the mineral separate in clove oil which has an index of refraction intermediate between K-feldspar and quartz + plagioclase. All separates were rinsed in acetone, ethyl alcohol and then 3 times in deionized water prior to packing for irradiation. 20050501 40Ar/39Ar Sample Irradiation: All mineral separates were then packaged in high purity Cu foil, sealed under vacuum in fused silica vials, and irradiated in the central thimble of the USGS-TRIGA reactor in one of three irradiations. The irradiation geometry was similar to that described in McAleer and others (2017). The sample assembly was rotated during irradiation to minimize the radial gradient in the fast neutron fluence, and no cadmium shielding was used. The samples were irradiated for 40 megawatt-hours (40 hours at 1.0MW/h) in 2005 (KD44), or 30 megawatt-hours (30 hours at 1.0 MW/h) in 2014 (KD61) and 2017 (KD65). All samples were irradiated along with MMHB (Alexander and others, 1978) as the flux monitor and a preferred age of 519.4 ± 2.5 Ma (Alexander and others, 1978). The values of Nier (1950) were used for the argon isotopic composition of air, and the values of Steiger and Jager (1977) were used for decay constants. Interfering isotope ratios were determined on co-irradiated CaF2 and zero age K-glass included with the irradiations KD61 and KD65. The interfering isotope values of Dalrymple and others (1980) were used for KD44. 2005 40Ar/39Ar Sample Analysis: 40Ar/39Ar analysis of the irradiated materials was done at the U.S. Geological Survey Bascom Argon Dating Laboratory (BARD) in Reston, VA. Samples were step-heated in a low blank furnace similar to that of Staudacher and others (1978), but with a molybdenum liner inserted into the tantalum crucible. The liner results in a temperature offset of -100 ±10 °C in the measured versus set point temperature based on melting experiments on aluminum and copper. The set point temperatures are reported in data tables. Following extraction, the evolved gases were cleaned in a fully automated extraction line prior to analysis. Gases released by furnace heating were cleaned in the first stage of a low volume two-stage extraction line with a SAES GP50 ST707 getter operating at room temperature, a hot rhenium filament for cracking hydrocarbons, and glass finger immersed in liquid nitrogen. The gas was then equilibrated with the second stage for three minutes, followed by 10 minutes of cleaning with a SAES GP50 ST101 getter operating at ~400°C, a Ti-getter operated at ~350°C, and a glass finger immersed in a dry ice/acetone mixture. Purified noble gases were then expanded into a VG1200B mass spectrometer and analyzed in static mode on a Balzers SEV217 electron multiplier in six cycles in peak hopping mode. Argon isotope data were collected and reduced using a modified version of ArAuto and ArAr* (Haugerud and Kunk, 1988). Full-system backgrounds (with the same procedures as sample runs, except the furnace is not turned on) were measured prior to the step heating analyses. Background corrections were made using the mean and standard deviation of three blanks immediately preceding analysis. Experiments show that the furnace full system blank is constant up to ~1350°C where the argon 40, 38, and 36 signals increase in atmospheric proportions. Air was used to monitor mass spectrometer discrimination. Aliquots of air were treated in the same manner as samples. The reduced data were plotted and ages and uncertainties were calculated using Isoplot (Ludwig, 2012). Values with '-9999' in reported data tables indicate 'no data' or 'not interpreted'. 20220707 Geochemistry Sample Preparation and Analysis: Whole-rock powders were prepared for geochemical analyses with a shatterbox in a tungsten carbide mill. A subset of samples were analyzed by X-ray fluorescence (XRF) with a Rigaku ZSX Primus II at Analytical Laboratories, Brigham Young University, using fused glass disks for major elements and pressed powder pellets for trace elements. Major element oxides in some samples were acquired by inductively coupled plasma emission spectroscopy (ICP-ES) at Bureau Veritas Commodities Canada Ltd. Trace element abundances in some samples were acquired by instrumental neutron activation analysis (INAA) at Bureau Veritas Commodities Canada Ltd. Rare earth element (REE) and other trace element abundances were acquired in a subset of samples at the University of Bergen, Norway, where, within a clean lab, 100 mg powder aliquots were dissolved in sub-boiled HF/HNO3 in PTFE screw-top beakers and were subsequently analyzed by inductively coupled plasma mass spectrometry (ICP-MS) on a Thermo Scientific Element XR ICP-MS. 2018 Thin Section Image Acquisition: Thin section images were acquired with an Epson Perfection V600 Photo scanner and the Epson Scan software package. Thin sections were scanned in transmitted light. Plane-polarized images were taken with a polarizing filter placed below the thin sections. Cross-polarized images were achieved by placing a second polarizing filter above the thin sections oriented 90 degrees to the lower filter. All images are of standard 26 mm x 46 mm petrographic microscope slides. Scanned images are at 1:1 scale with a calculated error of ±0.7%. Field of view in each image is the full thin section. 2025 0.0001 0.0001 Decimal degrees All entity and attribute information for this data release is contained in a data dictionary file named "OMB_data_dictionary.csv" OMB_data_dictionary.csv GS ScienceBase U.S. Geological Survey 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. Digital Data https://doi.org/10.5066/P1KR5E7F None 20250825 Ryan Deasy U.S. Geological Survey, Northeast Region Research Geologist mailing address

12201 Sunrise Valley Dr

Mail Stop 926A

Reston VA 20192 US 703-648-6897 703-648-6953 rdeasy@usgs.gov FGDC Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998