Premium
Geodetic Constraints on Cratonic Microplates and Broad Strain During Rifting of Thick Southern African Lithosphere
Author(s) -
Wedmore L. N. J.,
Biggs J.,
Floyd M.,
Fagereng Å.,
Mdala H.,
Chindandali P.,
Williams J. N.,
Mphepo F.
Publication year - 2021
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2021gl093785
Subject(s) - geology , lithosphere , rift , east african rift , craton , geodetic datum , seismology , archean , tectonics , plate tectonics , african plate , gnss applications , paleontology , satellite , geodesy , aerospace engineering , engineering
Southern Africa is typically considered to belong to a single tectonic plate, Nubia, despite active faulting along the southwestern branch of the East African Rift System. We analyze regional Global Navigation Satellite System (GNSS) measurements, and find that the “San” microplate, situated south of the southwestern branch of the East African Rift, is statistically distinct from Nubia, with 0.4–0.7 mm/yr of extension across the boundary. Adding nine new campaign GNSS sites, we show that the extension rate across the southern Malawi Rift is 2.2 ± 0.3 mm/yr, with 75% of the relative velocity occurring over 890 km, despite the surface expression of faulting being <150 km wide. Thus, for the first time, we use geodetic measurements to describe the accommodation of strain in broad zones between Archean cratons in southern Africa's thick continental lithosphere.