Peri-Gondwanan origin and early geodynamic history of NE Sicily: A zircon tale from the basement of the Peloritani Mountains

摘要

The ages of detrital zircon grains from one paragneiss and inherited zircon cores from two augen gneisses from the amphibolite facies basement of the Peloritani Mountains(southern Italy) measured by SHRIMP U-Pb constrain the previously unknown deposition age of the original sediments and help to elaborate a model for their provenance and subsequent evolution. The deposition age is latest Neoproterozoic to Cambrian(~ 545. Ma), bracketed by the combined ages of the youngest detrital/inherited zircon populations and of zircon from virtually coeval granitoids that intrude the metasediments. This is consistent with the subgreenschist facies Palaeozoic volcano-sedimentary sequences exposed in the southern Peloritani Mountains being the original cover rocks of the northern Peloritani late Neoproterozoic to early Cambrian basement. The age spectra of the detrital/inherited zircon grains show that the Neoproterozoic/Cambrian sediments were derived from the erosion of sources dominated by Neoproterozoic rocks with ages in the range of 0.85-0.54. Ga, with other main components aged 1.1-0.9 and ~. 2.7-2.4. Ga, and a minor one aged ~. 1.6. Ga, as typically found in peri-Gondwanan terranes. The presence of a large amount of Grenvillian-aged zircon contradicts previous models that propose a West African affinity for the Calabria-Peloritani Terrane, and the absence of 2.2-1.9. Ga Trans Amazonian/Tapajós-Parima/Eburnean zircon rules out an Amazonian provenance. The age spectra are more consistent with the basement sediments having an East African origin, similar to that of the early Palaeozoic sandstones in southern Israel and Jordan, part of a "provenance regionality" shared with other terranes currently located in the eastern Mediterranean area.