Ediacaran‐Ordovician Magmatism and REE Mineralization in the Wet Mountains, Colorado, USA: Implications for Failed Continental Rifting

Structures associated with Ediacaran‐Ordovician alkaline magmatism and the timing of rare earth element (REE) mineralization in the Wet Mountains, CO, were analyzed using field, geophysical, and U‐Th‐Pb isotope methods to interpret their tectonic setting in the context of previously proposed rift mo...

Full description

Saved in:
Bibliographic Details
Published in:Tectonics (Washington, D.C.) D.C.), 2023-04, Vol.42 (4), p.n/a
Main Authors: Magnin, Benjamin P., Kuiper, Yvette D., Anderson, Eric D.
Format: Article
Language:English
Subjects:
Ablation
airborne geophysics
Cambrian
Coastal inlets
Dikes
Direction
Earth
Earth crust
Embankments
Fault lines
Faults
faults and fractures
Fractures
geochronology
Geophysical data
Green energy
Isotopes
Lava
Magma
Magnetic data
Mass spectrometry
Mass spectroscopy
Mineral deposits
Mineralization
Minerals
Monazite
Mountains
Ordovician
Rare earth elements
Renewable energy
Rifting
Southern Oklahoma Aulacogen
Thorium
Uranium
Veins (geology)
Wet Mountains
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Structures associated with Ediacaran‐Ordovician alkaline magmatism and the timing of rare earth element (REE) mineralization in the Wet Mountains, CO, were analyzed using field, geophysical, and U‐Th‐Pb isotope methods to interpret their tectonic setting in the context of previously proposed rift models. The Wet Mountains are known for thorium and REE mineralization associated with failed rift‐related, Ediacaran‐Ordovician alkaline intrusions and veins. Structural field data indicate that alkaline dikes and mineralized veins are controlled by a system of northwest‐striking, high‐angle faults and tension fractures formed in a 040°‐directed extensional regime. Magnetic and surface expressions of Democrat Creek and McClure Mountain complexes show tectonic elongation toward ∼045°, consistent with NE‐directed extension. Magnetic data also suggest the existence of a fourth, previously unrecognized mafic‐ultramafic complex of inferred Cambrian age with a similar elongated orientation. Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA‐ICP‐MS) 208Pb/232Th analysis of low‐uranium zircon from carbonatite dikes and in situ 206Pb/238U LA‐ICP‐MS analysis of monazite in mineralized dikes yielded 465 ± 18 Ma and 489 ± 33 Ma ages, respectively. These ages are consistent with the expected age based on slightly older, cross‐cut syenite dikes and the hypothesized Ordovician end to failed rift‐related magmatism. The Ediacaran‐Ordovician age of alkaline magmatic rocks and the associated northeast‐directed extension direction are similar to those of the along‐strike, Ediacaran‐Cambrian Southern Oklahoma Aulacogen. Therefore, the failed rift system in the Wet Mountains is interpreted to be a northwestern continuation of the Southern Oklahoma Aulacogen with carbonatite magmatism and thorium/REE mineralization representing late intrusive phases. Plain Language Summary The Wet Mountains of south‐central Colorado contain elements and minerals important to modern electronics and green energy technology. These minerals formed along an ancient tectonic system where the Earth's crust pulled apart, which was associated with uprise of magma from greater depths. The orientation of the system was previously unknown. This study used field and geophysical data to analyze the faults and fractures that controlled the migration of magma and emplacement of associated mineralization in order to understand the direction in which the Earth's crust pulled apart. Results of this study rev
ISSN:0278-7407
1944-9194
DOI:10.1029/2022TC007674