Revisiting the age and paleomagnetism of the Modipe Gabbro of South AfricaSubmitted by admin on Thu, 10/31/2013 - 08:17
|Title||Revisiting the age and paleomagnetism of the Modipe Gabbro of South Africa|
|Publication Type||Journal Article|
|Year of Publication||2013|
|Authors||Denyszyn SW, Feinberg JM, Renne PR, Scott GR|
The Modipe Gabbro is a Precambrian intrusive unit hosted by the Kaapvaal craton of South Africa and pro- vides one of the oldest records of geomagnetic field behavior in the late Archean. Earlier paleomagnetic research into the Modipe Gabbro provided valuable insight into its magnetic properties and mineral- ogy, but predate the development of paleomagnetic tools that are important in unraveling potentially complex histories of Precambrian rocks. Further, a lack of information about the precise age of the intrusion prevented this earlier paleomagnetic study from being used to evaluate the tectonic history of the Kaapvaal craton. Here we present a comprehensive paleomagnetic and geochronologic study of the Modipe Gabbro that complements and builds upon the existing work. The emplacement age of the gabbro (2784.0 ± 1.0 Ma), established using the U–Pb ID-TIMS method on baddeleyite, links the intrusion to nearby igneous bodies in the Kaapvaal craton, establishing one of the oldest fully differentiated mag- matic events in the geologic record. The precise age of the Modipe Gabbro and field observations about its strike allow us to perform a tilt correction using the both the attitude and paleomagnetism of the nearby Derdepoort basalts. The tilt-corrected data allow a comparison of Kaapvaal craton’s paleolatitude with that of the Pilbara craton at 2.78 Ga, with implications for the existence of the supercraton Vaalbara.