Rasmussen, Birger, Zi, Jian-Wei, Muhling, Janet R. (2019) U-Pb evidence for a 2.15 Ga orogenic event in the Archean Kaapvaal (South Africa) and Pilbara (Western Australia) cratons. Geology, 47 (12) 1131-1135 doi:10.1130/g46366.1
| Reference Type | Journal (article/letter/editorial) | ||
|---|---|---|---|
| Title | U-Pb evidence for a 2.15 Ga orogenic event in the Archean Kaapvaal (South Africa) and Pilbara (Western Australia) cratons | ||
| Journal | Geology | ||
| Authors | Rasmussen, Birger | Author | |
| Zi, Jian-Wei | Author | ||
| Muhling, Janet R. | Author | ||
| Year | 2019 (December 1) | Volume | 47 |
| Issue | 12 | ||
| Publisher | Geological Society of America | ||
| DOI | doi:10.1130/g46366.1Search in ResearchGate | ||
| Generate Citation Formats | |||
| Mindat Ref. ID | 143818 | Long-form Identifier | mindat:1:5:143818:9 |
| GUID | 0 | ||
| Full Reference | Rasmussen, Birger, Zi, Jian-Wei, Muhling, Janet R. (2019) U-Pb evidence for a 2.15 Ga orogenic event in the Archean Kaapvaal (South Africa) and Pilbara (Western Australia) cratons. Geology, 47 (12) 1131-1135 doi:10.1130/g46366.1 | ||
| Plain Text | Rasmussen, Birger, Zi, Jian-Wei, Muhling, Janet R. (2019) U-Pb evidence for a 2.15 Ga orogenic event in the Archean Kaapvaal (South Africa) and Pilbara (Western Australia) cratons. Geology, 47 (12) 1131-1135 doi:10.1130/g46366.1 | ||
| In | (2019, December) Geology Vol. 47 (12) Geological Society of America | ||
| Abstract/Notes | Abstract There is geological evidence for widespread deformation in the Kaapvaal craton, South Africa, between 2.2 and 2.0 Ga. In Griqualand West, post-Ongeluk Formation (ca. 2.42 Ga) and pre-Mapedi Formation (>1.91 Ga) folding, faulting, and uplift have been linked to the development of a regional-scale unconformity, weathering horizons, and extensive Fe-oxide mineralization. However, the lack of deformational fabrics and the low metamorphic temperatures (<300 °C) have hampered efforts to date this event. Here we show that metamorphic monazite in Neoarchean shales from four stratigraphic intervals from the Griqualand West region grew at ca. 2.15 Ga, >400 m.y. after deposition. Combined with previous studies, our results show that sedimentary successions across the Kaapvaal craton deposited before ca. 2.26 Ga record evidence for crustal fluid flow at ca. 2.15 Ga, which is locally associated with thrust faulting, folding, and cleavage development. The style of the deformation is similar to that of the Ophthalmian orogeny in the Pilbara craton, Australia, which is interpreted to reflect the northeast-directed movement of a fold-thrust belt between 2.22 and 2.15 Ga. Our results suggest that the Kaapvaal and Pilbara cratons, which some paleogeographic reconstructions place together as the continent Vaalbara, experienced an episode of synchronous folding and thrusting at ca. 2.15 Ga. Deformation was followed by uplift and the development of unconformities that are associated with some of Earth’s oldest oxidative weathering and with the onset of Fe-oxide mineralization. | ||
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