Proterozoic Tectonics and Crustal Evolution in Southwestern North America

The Proterozoic record in southwestern North America documents a sequence of magmatic, deformational and metamorphic events that shaped the continent’s cratonic margin. Starting in the Mesoproterozoic, successive accretion of island-arc terranes welded juvenile crust onto the southern edge of Laurentia during the Yavapai and Mazatzal orogenies. These events were characterised by arc-related magmatism, high-pressure metamorphism and crustal thickening, producing basement rocks exposed today in the Mogollon Plateau, Tucson Mountains and Wet Mountains. Subsequent thermal relaxation and rifting at around 1.1 Ga led to widespread emplacement of the A-type Granite-Rhyolite province, triggering extensional structures that presaged later Basin and Range deformation. The Neoproterozoic Grenvillian collision to the east induced far-field stresses, reactivating Proterozoic sutures and influencing the distribution of deep-seated faults. Integration of geochronological, geochemical and geophysical data has revealed multiple cycles of crustal growth and reworking between 1.8 and 1.0 Ga, underscoring the significance of Proterozoic processes in establishing the rigid core of North America and controlling the distribution of mineral and hydrocarbon resources. The persistence of Proterozoic fabric has in turn influenced modern seismicity, groundwater flow and landscape evolution across Arizona, New Mexico and western Texas.

Research from Nature Portfolio

Recent studies have refined the timing and mechanisms of terrane accretion along the Proterozoic margin by integrating high-precision U-Pb geochronology with Lu–Hf isotopic tracing, demonstrating that juvenile and evolved crustal components were added in pulses between 1.75 and 1.60 Ga. Seismic-tomography research has imaged relic suture zones in the lower crust beneath the Mojave and Sonoran sectors, revealing lateral variations in lithospheric thickness inherited from Proterozoic subduction. In addition, detrital zircon Hf-isotope mapping across southern Arizona has elucidated the provenance of Mesoproterozoic sediments and quantified recycled versus juvenile additions, thereby constraining the growth history of Laurentia during supercontinent assembly.

Proterozoic Tectonics and Crustal Evolution in Southwestern North America publication trend

The graph below shows the total number of articles in proterozoic tectonics and crustal evolution in southwestern north america across all publications each year (not limited to Nature Index journals).

Technical terms

Terrane: A fragment of crustal material with a distinct geological history accreted onto a continental margin.

Orogeny: A mountain-building event caused by plate convergence and deformation of the crust.

Craton: A stable, ancient part of the continental lithosphere that has survived cycles of deformation.

U-Pb Geochronology: A dating method using the decay of uranium to lead in minerals such as zircon to determine rock ages.

Detrital Zircon Hf Isotopes: Isotopic ratios measured in zircon grains from sedimentary rocks to trace crustal growth and provenance.

Amphibolite Facies: A set of metamorphic conditions characterised by amphibole and plagioclase formation, indicating mid-crustal pressures and temperatures.

References

1. On the occurrence of amphibolite-facies sapphirine, spinel, phlogopite, anorthite, and corundum in the Wet Mountains, Colorado, USA. Lithos (2023).
2. The genesis of metamorphosed Paleoproterozoic massive sulphide occurrences in central Colorado: geological, mineralogical and sulphur isotope constraints. Geological Magazine (2023).