Synthesis of Results from the CD-ROM Experiment: 4-D Image of the Lithosphere Beneath the Rocky Mountains and Implications for Understanding the Evolution of Continental Lithosphere

CD-ROM Working Group

Research output: Chapter in Book/Report/Conference proceedingChapter

20 Scopus citations

Abstract

The CD-ROM experiment has produced a new 4-D understanding of the structure and evolution of the lithosphere of the southern Rocky Mountain region. We identify relicts of at least four subduction zones that were formed during assembly of dominantly oceanic terranes in the Paleoproterozoic. Crustal provinces with different geologic histories correspond to distinct mantle velocity domains, with profound mantle velocity contrasts associated with the ancient sutures. Typically, the transitions between the velocity domains are tabular, dipping, extend from the base of the crust to depths of 15&200 km, and some contain dipping mantle anisotropy. The present day heterogeneous mantle structure, although strongly influenced by ancient compositional variations, has undergone different degrees of partial melting due to Cenozoic heating andlor hydration caused by transient plumes or asthenospheric convection within the wide western U.S. active plate margin. A high-velocity mafic lower crust is present throughout the Rocky Mountains, and there is ~10-km-scale Moho topography. Both are interpreted to record progressive and ongoing differentiation of lithosphere, and a Moho that has changed position due to flux of basalt from the mantle to the crust. The mafic lower crust evolved diachronously via concentration of mafic restite during arc formation (pre-1.70 Ga), collision-related differentiation and granite genesis (1.7s1.62 Ga), and several episodes of basaltic underplating (1.45-1.35 Ga, ~1.1 Ga, and Cenozoic). Epeirogenic uplift of the western U.S. and Rocky Mountain regions, driven by mantle magmatism, continues to cause reactivation of the heterogeneous lithosphere in the Cenozoic, resulting in differential uplift of the Rocky Mountains.

Original languageEnglish (US)
Title of host publicationThe Rocky Mountain Region
Subtitle of host publicationAn Evolving Lithosphere: Tectonics, Geochemistry, and Geophysics
PublisherAmerican Geophysical Union
Pages421-441
Number of pages21
ISBN (Electronic)9781118666326
ISBN (Print)0875904181, 9780875904191
DOIs
StatePublished - Mar 19 2013

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Keywords

  • Core-mantle boundary
  • Geology, Structural-Rocky Mountains
  • Geophysics-Rocky Mountains
  • Orogeny-Rocky Mountains

ASJC Scopus subject areas

  • Physics and Astronomy(all)

Cite this

CD-ROM Working Group (2013). Synthesis of Results from the CD-ROM Experiment: 4-D Image of the Lithosphere Beneath the Rocky Mountains and Implications for Understanding the Evolution of Continental Lithosphere. In The Rocky Mountain Region: An Evolving Lithosphere: Tectonics, Geochemistry, and Geophysics (pp. 421-441). American Geophysical Union. https://doi.org/10.1029/154GM31