Paleomagnetic and ⁴°Ar/³⁹Ar geochronologic data from Late Proterozoic mafic dikes and sills, Montana and Wyoming Harlan, Stephen S. creator author. Geissman, John William author. Snee, Lawrence W. author. Geological Survey (U.S.) issuing body. text bibliography dcu 1997 monographic eng remote 1 online resource (16 pages) : illustrations, maps. by Stephen S. Harlan, John Wm. Geissman, and Lawrence W. Snee. "Paleomagnetic and 40Ar/39Ar results from mafic dikes and sills in northwestern Wyoming and western Montana indicate that they were emplaced during a regional magmatic event at 780 to 770 Ma." Includes bibliographical references (pages 14-16). n-us-mt n-us-wy Geology, Stratigraphic Proterozoic Geochronometry Montana Geochronometry Wyoming Sills (Geology) Montana Dikes (Geology) Wyoming Dikes (Geology) Geochronometry Geology, Stratigraphic Proterozoic Geologic Period Sills (Geology) Montana Wyoming From 570 million to 2 billion years ago fast I 19.16:1580 I 19.16:1580 Paleomagnetic and ⁴⁰Ar/³⁹Ar geochronologic data from Late Proterozoic mafic dikes and sills, Montana and Wyoming Harlan, Stephen S. (DLC) 97017085 (OCoLC)36877396 U.S. Geological Survey professional paper ; 1580 https://purl.fdlp.gov/GPO/LPS21271 COP 141123 20211202194740.0 in00004028911 eng