New (U-Th)/He titanite data from a complex orogen–passive margin system: A case study from northern Mozambique. (August 2016)

• Record Type: Journal Article
• Authors: Bauer, Friederike U.; Jacobs, Joachim; Emmel, Benjamin U.; van Soest, Matthijs C.
• Is Part Of: Journal of African earth sciences. Volume 120(2016:Aug.)
• Page Start: 56
• Page End: 69
• Publication Date: 2016-08
• Subjects: Titanite (U-Th)/He thermochronology -- Exhumation history Mozambique -- Thermal history modelling -- Orogen-passive margin system -- Gondwana break-up; Earth sciences -- Africa -- Periodicals; Earth sciences -- Middle East -- Periodicals; Geology -- Africa -- Periodicals; Geology -- Middle East -- Periodicals; Sciences de la terre -- Afrique -- Périodiques; Sciences de la terre -- Moyen-Orient -- Périodiques; Géologie -- Afrique -- Périodiques; Géologie -- Moyen-Orient -- Périodiques; Earth sciences; Geology; Africa; Middle East; Periodicals; Electronic journals; 556.05
• DOI: 10.1016/j.jafrearsci.2016.04.012
• Languages: English
• ISSNs: 1464-343X

Abstract

Abstract: New titanite (U-Th)/He (He) data on basement rocks from NE Mozambique are presented. The objective was to test the applicability of titanite He thermochronology in an orogen–passive margin setting and to better constrain the exhumation history across the Lurio Belt, a major structural discontinuity in Mozambique. Therefore, samples from existing geochronological and thermochronological studies were dated using titanite He thermochronology. Resulting titanite He data (from abraded crystals) provide average cooling ages from 178 ± 15 to 383 ± 23 Ma. The data fit well into the age pattern obtained from previous thermochronological studies in NE Mozambique, revealing differential exhumation across the Lurio Belt. The basement to the north experienced earlier cooling than that to the south, while overall youngest titanite He ages are from the Lurio Belt, indicating reactivation linked to the post-collisional extension and break-up of Gondwana. Thermal history modelling revealed two possibilities, able to account for the different cooling histories of NE Mozambique since initial Gondwana break-up in Permian times: One involves a transient sedimentary overburden that buried and (re)heated the southern basement, with subsequent basin inversion at ∼250 Ma in response to rift shoulder uplift. The second model implies delayed cooling of the southern basement, possibly due to delamination of the crustal root shortly after Gondwana formation. The formerly upwelling asthenosphere and the subsequently formed sag basin might have caused a prolonged thermal effect. Titanite He ages and thermal histories point to rift shoulder uplift of the southern part and increased thermal activity within the reactivated Lurio Belt, signifying first rifting activities as precursor of Gondwana break-up. Highlights: Titanite (UTh)/He analyses: a reliable tool for thermal history reconstruction. Tectono-thermal history of a pull-apart setting during initial Gondwana break-up. Fault reactivation and rift shoulder uplift as precursor of Gondwana break-up.