Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
4724152 | Precambrian Research | 2010 | 13 Pages |
Abstract
The Barberton granitoid-greenstone belt is a classic dome-and-keel province, characterized by kilometer-scale gneiss domes and elongate keels of largely folded supracrustal rocks. Combined U-Pb SHRIMP data and structural mapping demonstrate that the geometry of the Barberton belt reflects events that occurred over â¼30 million year interval, from ca. 3230 and 3203 Ma. Early deformation with NW-SE shortening in the upper crust was accompanied by emplacement of tonalite-trondhjemite-granodiorite TTG magmas at 3234 ± 12 and 3226 ± 9 Ma. Much of the structural grain of the greenstone belt relates to a long episode of post-orogenic extension, with NE-directed extension in the lower crust leading to exhumation of high-grade gneisses in the southern Barberton terrane. Advective heat transfer during emplacement of kilometer-scale (TTG) plutons around the margins of the greenstone belt facilitated the infolding of the relatively denser and colder greenstone sequence. The end of this tectonic cycle is punctuated by the emplacement of the undeformed, 3203 ± 7 Ma Dalmein pluton, which sharply truncates not only anticlines and synclines in the greenstone belt but also the dominant fabric in the high-grade gneisses.
Related Topics
Physical Sciences and Engineering
Earth and Planetary Sciences
Geochemistry and Petrology
Authors
Cristiano Lana, Eric Tohver, Peter Cawood,