Airborne magnetic and radiometric survey, Boulder Batholith region, Montana, 2022

This data release provides digital flight line data for a high-resolution airborne magnetic and radiometric survey over parts of Montana in the vicinity of the Boulder Batholith. The airborne survey was jointly funded by the Earth Mapping Resources Initiative and Kennecott Exploration Company. The survey was designed to meet complementary needs related to geologic mapping and characterization of mineral resource potential. A total of 34,041 line km of magnetic and radiometric data were acquired over an irregular-shaped area of 6178 km. Data were collected from a helicopter flown at a nominal terrain clearance of 100 meters (m) above topography along E-W flight lines spaced at 200 m intervals. Tie lines were flown in an N-S direction every 2000 m. Data were collected by Sander Geophysics Limited (SGL), and Dewberry Engineers, Inc. under contract with the USGS using a helicopter with a magnetometer mounted in a stinger and a fully calibrated gamma-ray spectrometer. The survey operated out of the Butte, Montana, airport from June of 2022 to August of 2022. Files that are available in this publication include flight line data for the magnetic survey, flight line data for the radiometric survey and a report describing the survey parameters, field operations, quality control and data reduction procedures. A zip file is provided that contains the contractor's deliverable products that includes Geosoft databases and grids for the magnetic and radiometric survey and the report describing the survey and data reduction. Version History First release: July, 2023 Version 2: April, 2024 Version 2 This project was jointly funded by the US Geological Survey Earth Mapping Resources Initiative and Kennecott Exploration Company. The original data release (July, 2023) consisted of USGS-funded data only. Data that were added to the data release on April, 2024, which consisted of aeromagnetic and radiometric data, were funded by Kennecott Exploration Company and was withheld from the original release as proprietary data. This revision includes all data acquired as part of the survey. Changes from previous version: 1) Added aeromagnetic and radiometric data funded by Kennecott Exploration Company. 2) Updated metadata to reflect the extent of the full data release. 3) Updated spatial reference .shp files to reflect the extent of the full data release. 4) Updated contractor report and deliverables to reflect the extent of the full data release. 5) Updated geotiffs to reflect the extent of the full data release.本数据集发布提供了蒙大拿州博尔德岩基（Boulder Batholith）周边部分区域的高分辨率航空磁法与放射能测量飞行线数据。本次航空测量项目由地球测绘资源倡议（Earth Mapping Resources Initiative）与肯尼科特勘探公司（Kennecott Exploration Company）联合资助，旨在满足地质填图与矿产资源潜力评价的互补需求。 本次作业共在6178平方千米的不规则区域内，采集了总计34041测线千米的磁法与放射能测量数据。采集时采用直升机沿东西向飞行测线开展作业，测线间距为200米，标称离地地形高度为100米；每隔2000米布设一条南北向联络测线。数据由桑德地球物理有限公司（Sander Geophysics Limited, SGL）与德伯里工程公司（Dewberry Engineers, Inc.）受美国地质调查局（USGS）委托采集，所用直升机搭载了安装于尾杆（stinger）的磁强计与经过全面校准的伽马射线能谱仪。本次作业的运营基地为蒙大拿州比尤特机场，作业时间为2022年6月至8月。 本次发布提供的文件包括磁法测量飞行线数据、放射能测量飞行线数据，以及一份阐述测量参数、野外作业、质量控制与数据处理流程的报告。此外还提供了一个压缩包，内含承包商交付的成果产品，包括磁法与放射能测量的Geosoft数据库与网格数据，以及阐述测量项目与数据处理流程的报告。 版本更新记录： 首次发布：2023年7月 版本2：2024年4月 本项目由美国地质调查局地球测绘资源倡议与肯尼科特勘探公司联合资助。2023年7月的初始发布仅包含美国地质调查局资助的数据。2024年4月新增的航空磁法与放射能测量数据由肯尼科特勘探公司资助，最初因属于专有数据未纳入初始发布版本。本次修订包含本项目全部采集的数据。相较于前一版本的更新内容如下：1）新增由肯尼科特勘探公司资助的航空磁法与放射能测量数据；2）更新元数据以反映完整数据集的覆盖范围；3）更新空间参考.shp文件以匹配完整数据集的覆盖范围；4）更新承包商报告与交付成果以反映完整数据集的覆盖范围；5）更新GeoTIFF文件以匹配完整数据集的覆盖范围。