Work

Magnetostratigraphy and Source Characterisation Across the Early Miocene Unconformity, Northern Rocky Mountains, USA

Year: 2025

Type: article

Abstract: ABSTRACT The early Miocene unconformity (EMU) formed during a transition in the tectonic regime of western North America that coincided with faunal diversification. The Railroad Canyon section in the northern Rocky Mountains provides a complete geologic record around this event. Our new magnetostratigraphic study in combination with published U‐Pb ages from intercalated ash places the end of the EMU at ~20.1 Ma with a duration of up to 1.5 Myr. The EMU is marked by an abrupt change in rock colour, an increase in magnetite concentration, and a decrease in calcite abundance. Average sedimentation rates are similar above and below the EMU, as are climate proxies; therefore, the changes in mineralogy likely reflect a reorganisation in sediment source. Drainage network reorganisation seemingly contributed to this, possibly related to a change in tectonic regime, such as the onset of Basin and Range extension and/or arrival of the Yellowstone plume.

Source: Terra Nova

DOI: 10.1111/ter.12779

Authors: Dieke Gerritsen, Stuart A. Gilder, Alina L. Ludat, Michael R. Wack

Institution: Ludwig-Maximilians-Universität München

Language: English

Topic: Geomagnetism and Paleomagnetism Studies

Subfield: Molecular Biology

Field: Biochemistry, Genetics and Molecular Biology

Domain: Life Sciences

Open Access status: hybrid

Estimated APC paid: $3,720

Funder: Deutsche Forschungsgemeinschaft