Decoding the Ediacaran Enigma: Gondwana paleogeography revisited through a provenance study of the Salt Range Formation (Salt Range, western Himalayas, Pakistan)

Abstract

The relative positioning of the different fragments of Gondwana prior to its amalgamation remains controversial, and geological research from the Ediacaran Salt Range Formation (SRF) in the Pakistan Himalayas, which may help to solve this issue has been limited. An integrated approach including petrography, U-Pb zircon geochronology, and Hf isotopic analyses was needed to provide information about the depositional age, provenance, tectonic setting, regional correlation, and paleogeographic position of the SRF within the Gondwana supercontinent. SRF sandstones range from feldspatho-litho-quartzose to quartz-rich litho-quartzose. Detrital zircon U-Pb results reveal an Ediacaran (<551) maximum depositional age of the SRF, with major age clusters at 2550–2450 Ma, 1970–1800 Ma, 1050–900 Ma, 900–700 Ma, 695–542 and both positive (52 %) and negative (48 %) εHf(t) values, indicating juvenile and recycle of both eastern (Indian Shield) and western (Arabian Nubian Shield) Gondwana terranes. Zircon-age peaks at 900–700 Ma, and 695–542 Ma, suggesting provenance from the Malani igneous suite, Oman, Madagascar, Seychelles and from the Pan-African belt include Arabian-Nubian shield and Iran, respectively. The SRF displays lithological, biogeographic, geochronological, and provenance similarities with coeval formations in Oman, India, and the Yangtze Block of South China, indicating that the SRF was deposited onto a carbonate-evaporite platform during the collision of eastern (Indian Shield) and western (Arabian Nubian Shield Gondwana. We suggest that the western Himalayas were positioned on the northern margin of Indian Shield during the Ediacaran and provide a revised paleogeographic framework for the tectonic evolution during the amalgamation of the Gondwana supercontinent.