Journal article
Migrating magmatism in the northern US Cordillera: in situ U–Pb geochronology of the Idaho batholith
Contributions to Mineralogy and Petrology, Vol.159(6), pp.863-883
2010
DOI: 10.1007/s00410-009-0459-5
Abstract
New in situ laser ablation-inductively coupled plasma-mass spectrometry and sensitive high-resolution ion microprobe U–Pb geochronology of zircons from the Idaho batholith and spatially overlapping Challis intrusions reveals a series of discrete magmatic belts of different ages and compositions. Following the accretion of the Blue Mountains province to North America along the Salmon River suture zone, two compositionally diverse belts of metaluminous plutons formed both adjacent to the suture and well inboard of it. These were constructed from ~100 to 85 Ma and were followed by a voluminous pulse of peraluminous magmatism, forming the bulk of the Atlanta lobe and largest fraction of the batholith between ~80 and 67 Ma. Around 70 Ma, a later and more spatially restricted suite of metaluminous plutons formed around the Bitterroot lobe of the batholith. This was followed by another pulse of voluminous peraluminous magmatism in the Bitterroot lobe, lasting from ~66 to 54 Ma. The changes from low volume metaluminous to high volume peraluminous magmatism may reflect a combination of changes in the angle and segmentation of the subducting Farallon plate and over thickening of the continental lithosphere. All of these features were then cut by plutons and dikes associated with the Challis volcanic field, lasting from ~51 to 43 Ma. Inherited components are pervasive in zircons from most phases of the batholith. While Precambrian components are very common, zircons also often contain cores or mantles that are 5–20 million years older than their rims. This suggests that the early phases of the batholith were repeatedly cannibalized by subsequent magmas. This also implies that the older suites may have been originally more aerially extensive than their currently exposed forms.
Details
- Title: Subtitle
- Migrating magmatism in the northern US Cordillera: in situ U–Pb geochronology of the Idaho batholith
- Creators
- Richard M. Gaschnig - Washington State UniversityJeffrey D. Vervoort - Washington State UniversityReed S. Lewis - University of IdahoWilliam C. McClelland - University of Iowa
- Resource Type
- Journal article
- Publication Details
- Contributions to Mineralogy and Petrology, Vol.159(6), pp.863-883
- DOI
- 10.1007/s00410-009-0459-5
- ISSN
- 0010-7999
- eISSN
- 1432-0967
- Language
- English
- Date published
- 2010
- Academic Unit
- Earth and Environmental Sciences
- Record Identifier
- 9984230123902771
Metrics
8 Record Views