图书馆知识库

This paper presents the first ever detrital zircon U-Pb-Hf isotopic study for the Late Neoproterozoic-Early Palaeozoic stratigraphic succession exposed in the Hazara Basin, Western Himalaya, North Pakistan. This time span represents the break-up of the supercontinent Rodinia and final assembly of Gondwana. The detrital record of the Late Neoproterozoic succession indicates well-mixed detritus shed from within the Indian Craton, especially the Central Indian provenance (including the Delhi Fold Belt, Aravalli Orogen, and Bundlekhand Craton). The epsilon Hf(t) values are mostly negative, and Hf TDMC ages are clustered at 2.0-2.4Ga, which indicates the derivation from an ancient reworked crustal source. In addition, the presence of a few positive epsilon Hf(t) values in the Late Neoproterozoic sequence indicates addition of the juvenile crust that corresponds to the period of the Rodinia break-up. However, dissimilarities with detrital signatures from the Australian continent may indicate break-up of the Rodinia supercontinent and detachment of Australia from India prior to similar to 754Ma, which is the depositional age of the Hazara Formation. In addition, the angular unconformity at the base of the Abbottabad Formation represents the compressional tectonics that might be associated with the Pan-African (Indo-Antarctic Craton collision with the East African Orogen during 800-700Ma) orogeny. The presence of the metamorphism and deformation in the rocks below the unconformity supports such an event prior to deposition of the Early Palaeozoic Abbottabad Formation. Similarly, the appearance of the Pan-African detritus in the Early Palaeozoic Abbottabad Formation could be due to closure of the ocean basin between Eastern and Western Gondwana along the Mozambique Suture. This provenance change may indicate the final assembly of supercontinent Gondwana.