Linking the Pinware, Baraboo, and Picuris Orogens: Recognition of a Trans-Laurentian ca. 1520–1340 Ma Orogenic Belt

Authors

Christopher G. Daniel
Aphrodite Indares
L. Gordon Medaris Jr.
Ruth Aronoff
David H. Malone, Illinois State UniversityFollow
Joshua Schwartz

Document Type

Chapter

Publication Date

1-23-2023

Publication Title

Laurentia: Turning Points in the Evolution of a Continent

Abstract

It is proposed that the Pinware orogen of eastern Canada, the Baraboo orogen of the midcontinent, and the Picuris orogen of the southwestern United States delineate a previously unrecognized, ~5000-km-long, ca. 1520–1340 Ma trans-Laurentian orogenic belt. All three orogenic provinces are characterized by Mesoproterozoic sedimentation, magmatism, metamorphism, and deformation—the hallmarks of a tectonically active plate margin. Tectonism was diachronous, with the earliest stages beginning ca. 1520 Ma in eastern Canada and ca. 1500 Ma in the southwest United States. Magmatic zircon age distributions are dominated by Mesoproterozoic, unimodal to multimodal age peaks between ca. 1500 and 1340 Ma. The onset of magmatism in the Pinware and Baraboo orogens was ca. 1520 Ma, and onset for the Picuris orogen was ca. 1485 Ma. Detrital zircon age distributions within each orogenic province yield maximum depositional ages between ca. 1570 and 1450 Ma. Minimum depositional ages generally fall between ca. 1500 and 1435 Ma, as constrained by crosscutting intrusions, metatuff layers, or the age of subsequent metamorphism. Metamorphic mineral growth ages from zircon, garnet, and monazite yield peak ages between ca. 1500 and 1350 Ma and tend to be older in the Pinware and Baraboo orogens than in the Picuris orogen. The ⁴⁰Ar/³⁹Ar cooling ages for hornblende, muscovite, and biotite yield significant peak ages between ca. 1500 and 1350 Ma in the Baraboo and Picuris orogens. We propose that the Pinware-Baraboo-Picuris orogen formed in a complex, diachronous, convergent margin setting along the southern edge of Laurentia from ca. 1520 to 1340 Ma.

DOI

https://doi.org/10.1130/2022.1220(11)

Comments

This chapter was originally published in Laurentia: Turning Points in the Evolution of a Continent: Geological Society of America Memoir 220, p. 175-190, 2023; https://doi.org/10.1130/2022.1220(11).

Gold Open Access: This chapter is published under the terms of the CC-BY license and is available open access on www.gsapubs.org.

Recommended Citation

Daniel, C.G., Indares, A., Medaris, L.G., Jr., Aronoff, R., Malone, D., and Schwartz, J., 2023, Linking the Pinware, Baraboo, and Picuris orogens: Recognition of a trans-Laurentian ca. 1520–1340 Ma orogenic belt, in Whitmeyer, S.J., Williams, M.L., Kellett, D.A., and Tikoff, B., eds., Laurentia: Turning Points in the Evolution of a Continent: Geological Society of America Memoir 220, p. 175–190, https://doi.org/10.1130/2022.1220(11).