Provenance of late Palaeozoic metasediments of the SW South American Gondwana margin: a combined U–Pb and Hf-isotope study of single detrital zircons

Abstract

Combined U-Pb and Lu-Hf isotope measurements of single detrital zircon grains in Carboniferous metasediments from Patagonia delineate the source areas of the sediments. The detritus, represented by four metasandstone samples, was deposited prior to onset of subduction in Late Carboniferous time along the south Patagonian proto-Pacific Gondwana margin. A broad series of detrital zircon age peaks (0.35-0.7 Ga, 0.9-1.5 Ga) and a large spread (0.3-3.5 Ga) in the age spectra require numerous sources. A fifth metasediment was deposited after the onset of subduction. This syncollisional sample shows two distinct U-Pb age peaks at c. 290 Ma and 305 Ma. This points to a few sources only (Patagonia, West Antarctica). Initial Hf-isotope compositions of selected U-Pb dated zircons from the Carboniferous metasediments reveal zircon protoliths originating from both recycled crust and juvenile sources (åHf (T¼0:4-3:5Ga)

Permo-Carboniferous conglomerates in the Trinity Peninsula Group at View Point, Antarctic Peninsula: sedimentology, geochronology and isotope evidence for provenance and tectonic setting in Gondwana

“…They also differ from other southern Chilean metasediments in having very few older Palaeozoic zircons and lack the strong Carboniferous, Devonian and Cambrian peaks seen in the Eastern Andes Metamorphic Complex at similar latitude (Hervé, Fanning & Pankhurst, 2003). On the whole, the age spectra in the Trinity Peninsula Group do not resemble those of the contemporaneous accretionary complex of Patagonia but seem closer to the portions of the Eastern Andes Metamorphic Complex (Augustsson et al 2006;Hervé, Calderon & Faundez, 2008). Some parts of this complex may be as old as Devonian (Faundez, Herve & Lacassie, 2002) but other parts have detrital zircon peaks of Carboniferous and Permian ages (Hervé, Fanning & Pankhurst, 2003) and probably overlap with Trinity Peninsula Group and Duque de York Complex deposition.…”

“…It is, however, also close to the ages of granites at Target Hill (Millar, Pankhurst & Fanning, 2002), about 350 km SSW of View Point. These few grains are the only representatives of post-Cambrian populations that are well represented in other South American basins (Augustsson et al 2006;Bahlburg et al 2009). This raises some doubts about the provenance of the matrix sediment and a need to consider possible alternative sources.…”

U-Pb zircon constraints on the age of the Cretaceous Mata Amarilla Formation, Southern Patagonia, Argentina: its relationship with the evolution of the Austral Basin

“…In Argentina, it is known as the Bahía de la Lancha Formation and the Río Lácteo Formation; whereas in Chile it is represented in the metamorphic complexes of Aysén and Magallanes. These two were dated at the same latitude as the study area by Hervé et al (2003Hervé et al ( , 2007b and Augustsson et al (2006).…”

Provenance of Pleistocene Rhine River Middle Terrace sands between the Swiss–German border and Cologne based on U–Pb detrital zircon ages

“…Relatively short lag times on the order of a few million years to a few tens of millions of years seem to be typical also of strike-slip, collisional and subduction-related ancient, and modern settings where detritus may be transferred rapidly from source to sink (e.g., Augustsson et al 2006;Bahlburg et al 2011;Link et al 2005;Rino et al 2008;Jacobson et al 2011).…”

“…The increased availability and reliability of LA-ICP-MS U-Pb ages of detrital zircons (e.g., Kosler and Sylvester 2003;Chang et al 2006) offers the possibility to analyze the geochronological evolution of source terranes and the relationship between sources and sinks of sediment. Detrital zircon ages have been successful in discriminating between different source regions and sediment delivery pathways (e.g., Sircombe 1999; Augustsson et al 2006;Bahlburg et al 2010). The presence of a given zircon age population and similarities in age distributions is taken as evidence of a common provenance (e.g., Cawood et al 2003Cawood et al , 2007Bahlburg et al 2010;Linnemann et al 2007).…”