Titre du document / Document title
Syncompressional emplacement of the Boulder and tobacco root batholiths (Montana-USA) by pull-apart along old fault zones
Auteur(s) / Author(s)
SCHMIDT C. J. ;
SMEDES H. W. ;
O'NEILL J. M. ;
Affiliation(s) du ou des auteurs / Author(s) Affiliation(s)
Western Michigan univ., dep. geology, Kalamazoo MI 49008, ETATS-UNIS
Résumé / Abstract
The 15 major plutons comprising the 6000 km
2 Late Cretaceous Boulder batholith were emplaced at mid- to upper-crustal levels (<20 km) during active thrusting in the Montana thrust belt. The Tobacco Root batholith, the largest satellite pluton of the Boulder batholith (∼300 km
2) was emplaced into uplifted Archean basement rocks immediately southeast of the frontal margin of the thrust belt. Emplacement of the Boulder batholith and its satellite plutons was cotnrolled principally by three long-lived and deeply penetrating regional fault sets. Two of these sets (a NE-trending set and an E-trending set) appear to have controlled the emplacement of the main mass of the batholith (Butte pluton). A third (NW-trending) fault set controlled the emplacement of the Tobacco Root batholith and many of the smaller plutons of the Boulder batholith. The intersecting fault sets give the Butte pluton a distinctly rhomboid shape, elongate in a northeasterly direction. Geophysical data suggest that the pluton may have a flat floor at the level of the basal decollement of the thrust belt (∼17 km)
Revue / Journal Title
Geological journal
ISSN
0072-1050
CODEN GELJA8
Source / Source
1990, vol. 25, n
o3-4, pp. 305-318 [14 page(s) (article)] (1 p.1/2)
Langue / Language
Anglais
Editeur / Publisher
Wiley, Chichester, ROYAUME-UNI
(1964)
(Revue)
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Localisation / Location
INIST-CNRS, Cote INIST : 6865
Nº notice refdoc (ud4) : 19743834
