Role of the Down-Bending Plate as a Detrital Source in Convergent Systems Revealed by U–Pb Dating of Zircon Grains: Insights from the Southern Andes and Western Italian Alps

Abstract

In convergent zones, several parts of the geodynamic system (e.g., continental margins, back-arc regions) can be deformed, uplifted, and eroded through time, each of them potentially delivering clastic sediments to neighboring basins. Tectonically driven events are mostly recorded in syntectonic clastic systems accumulated into different kinds of basins: trench, fore-arc, and back-arc basins in subduction zones and foredeep, thrust-top, and episutural basins in collisional settings. The most widely used tools for provenance analysis of synorogenic sediments and for unraveling the tectonic evolution of convergent zones are sandstone petrography and U–Pb dating of detrital zircon. In this paper, we present a comparison of previously published data discussing how these techniques are used to constrain provenance reconstructions and contribute to a better understanding of the tectonic evolution of (i) the Cretaceous transition from extensional to compressional regimes in the back-arc region of the southern Andean system; and (ii) the involvement of the passive European continental margin in the Western Alps subduction system during impending Alpine collision. In both cases, sediments delivered from the down-bending continental block are significantly involved. Our findings highlight its role as a detrital source, which is generally underestimated or even ignored in current tectonic models.

Multi-Proxy Provenance Analyses of the Kingriali and Datta Formations (Triassic–Jurassic Transition): Evidence for Westward Extension of the Neo-Tethys Passive Margin from the Salt Range (Pakistan)

“…The comparative low relief did not allow sediment derivation from diverse source rocks. The meandering fluvial system reworked and transported mostly the older Triassic and Permian siliciclastics (Figure 17a) [146]. This is confirmed by the eastward disappearance of the Triassic and Permian strata in the present-day eastern Salt Range (Figure 2).…”

The role of mantle upwelling on the thermal history of theTertiary‐PiedmontBasin at theAlps‐Apenninestectonic boundary

“…The TPB is bounded by: (i) metamorphic rocks of the Ligurian Alps to the south and southwest (Briançonnais units and Voltri massif; Figure 1), which experienced a complex, multi‐stage deformation and metamorphic evolution (e.g. Bonini et al, 2010; Capponi & Crispini, 2002; Di Giulio et al, 2020; Federico et al, 2009; Maino et al, 2012, 2019; Maino & Seno, 2016; Mueller et al, 2020; Vignaroli et al, 2010); and (ii) Cretaceous low‐grade metamorphic units, exposed to the east, which are part of the accretionary wedge of the Northern Apennines (Capponi et al, 2016; Marroni, Meneghini, & Pandolfi, 2010; Marroni, Ottria, & Pandolfi, 2010).…”