The dyke swarms of Tandil and Azul are groups of dykes of Proterozoic age located in Buenos Aires Province, Argentina. The dyke swarms consists of two groups: 2000 million year old dykes of calc-alkaline type and 1600 million year old dykes of tholeiitic type.[1]

Description

The tholeiitic dykes are made up of diabase and titanium-rich basalt, in contrast the calc-alkaline dykes are made up of andesite and rhyolite.[2] The dyke swarms intrude the southern part of the Río de la Plata Craton, much the same way the Uruguayan dyke swarms intrude the northeastern part of the craton.[1]

The calc-alkaline dykes intruded in a period of transtensional tectonics during the Transamazonian orogeny, while the tholeiitic dykes intruded during the period of extensional tectonics that succeeded the orogeny.[1]

References

  1. 1 2 3 Iacumin, M.; Piccirillo, E.M.; Girardi, V.A.V.; Teixeira, W.; Bellieni, G.; Echeveste, H.; Fernández, R.; Pinese, J.P.P.; Ribot, A. (2001). "Early proterozoic calc-alkaline and middle proterozoic tholeiitic Dyke Swarms from Central–Eastern Argentina: petrology, geochemistry, Sr–Nd isotopes and tectonic implications". Journal of Petrology. 42 (11): 2109–2143.
  2. ↑ Lajoinie, M.F.; Etcheverry, R.O; Lanfranchini, M.E.; Cábana, C. (2014). "Geología, geoquímica y génesis de diques proterozoicos del área de San Miguel, sierras septentrionales de la provincia de Buenos Aires". Revista de la Asociación Geológica Argentina (in Spanish). 71 (3): 404–415.
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