Airborne magnetic and radiometric survey, northwestern Minnesota, 2021

This data release provides digital flight line data for a high-resolution airborne magnetic and radiometric survey over parts of northwestern Minnesota near the town of Mentor. The airborne survey was funded by the Earth Mapping Resources Initiative and was designed to meet complementary needs related to geologic mapping and characterization of mineral resource potential. A total of 40,139-line km of magnetic and radiometric data were acquired over an irregular-shaped area of 9140 km2. Data were collected from a fixed-wing aircraft flown at mean terrain clearance of 120 meters (m) above topography along N-S flight lines spaced at 250 m intervals. Tie lines were flown in an E-W direction every 2500 m. Data were collected by EDCON-PRJ and NV5 Geospatial, Inc. under contract with the USGS using a fixed wing aircraft with a magnetometer mounted in the tail stinger and a fully calibrated gamma-ray spectrometer. The survey operated out of the Crookston, Minnesota airport from May of 2021 to July of 2021. 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.本数据集发布提供了明尼苏达州西北部门托（Mentor）镇周边区域的高分辨率航空磁法与放射性测量飞行线数字数据。本次航空测量由地球测绘资源倡议（Earth Mapping Resources Initiative）资助，旨在满足地质填图与矿产资源潜力评价的互补性需求。本次测量在面积9140平方千米的不规则区域内，共获取了40139直线千米的磁法与放射性测量数据。数据采集采用固定翼飞机，沿地形上方平均离地高度120米的空域飞行，南北向飞行线的布设间距为250米；每2500米布设一条东西向联络测线。数据由EDCON-PRJ与NV5 Geospatial, Inc.受美国地质调查局（USGS）委托采集，所用固定翼飞机的尾杆搭载了磁强计，并配备了经过全面校准的伽马射线能谱仪。本次测量作业于2021年5月至7月间，以明尼苏达州克鲁克斯顿（Crookston）机场为基地开展。本发布内容包含的文件有：磁法测量飞行线数据、放射性测量飞行线数据，以及一份详述测量参数、野外作业、质量控制与数据处理流程的报告。本次发布还提供一个压缩包，内含承包商提交的交付成果，包括磁法与放射性测量的Geosoft数据库及网格数据，以及一份详述测量概况与数据处理过程的报告。