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The Peerless structure, Daniels County, northeastern Montana: A probable late Ordovician impact structure
Author(s) -
Comstock J. M.,
Dietz R. D.,
Morrow J. R.
Publication year - 2004
Publication title -
meteoritics and planetary science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.09
H-Index - 100
eISSN - 1945-5100
pISSN - 1086-9379
DOI - 10.1111/j.1945-5100.2004.tb00111.x
Subject(s) - geology , ordovician , impact structure , paleontology , stratigraphic unit , sedimentary rock , geomorphology , impact crater , geochemistry , physics , astronomy
— The Peerless structure is an ˜6 km‐diameter sub‐surface anomaly located in Daniels County, northeastern Montana. The disruption of sedimentary rock in the structure lies between 2624 to 2818 m below the topographic surface. Seismic mapping shows a typical complex crater composed of a central uplift ˜2 km across, which shows structural uplift of up to 90 m, an annular ring ˜4 km across, and an outer rim ˜6 km in diameter. The youngest disrupted rock unit is the upper Ordovician Red River formation, which indicates that the structure was formed about 430–450 Ma ago.