Zircon geochronology and provenance of the late Proterozoic and early Palaeozoic of southwestern Jordan

The Feinan Granite of the Wadi Feinan type area revealed late Cryogenian (Neoproterozoic) to early Terreneuvian (Cambrian) magmatic ages with a maximum (94 %) of ages ranging from 550 Ma to 627 Ma (Ediacaran, Neoproterozoic). The few youngest zircon grains, however, provided a Concordia Age of 535 +/- 12 Ma, interpreted here as the intrusion age of the Feinan Granite. This age spectrum contradicts hitherto assumptions of an absence of ages older than 600 Ma in the Feinan Granite and re-establishes a former model of a unified igneous complex together with the Timna unit of southern Israel of which the Feinan Granite is the eastern continuation (Timna-Feinan Igneous Complex). A Neoproterozoic age (about 600 Ma) was previously indicated for the conglomeratic Saramuj Formation by previous studies, but the present work provides additional detrital zircon ages that also indicate younger Neoproterozoic zircons (566-718 Ma). This indicates deposition over an extended time period and, consequently, a shorter stratigraphical gap between this formation and the overlying Cambrian strata. Age data of detrital zircons from upper lower and lower middle Cambrian siliciclastic formations (Salib Formation, Burj Formation, Umm Ishrin Formation) and from Middle to Upper Ordovician formations (Hiswah Formation, Dubaydib Formation, Tubayliyat Formation) are presented and reveal similar detrital zircon ages. Three of these formations are geochronologically investigated for the first time. There is a general predominance of Neoproterozoic ages (ranging from 552-1000 Ma, locally with sporadic early Cambrian zircons from the Umm Ishrin Formation and Hiswah Formation) and a conspicuous stratigraphic gap in the middle and lower Mesoproterozoic. The youngest of the investigated units (Tubayliyat Formation) documents an obvious depletion in the number of Neoproterozoic zircons and an increase in older zircons which we interpret as being eroded from a lower (earlier) stratigraphical level. The sources of the Neoproterozoic to late Mesoproterozoic detrital zircons are represented by the proximate Arabian-Nubian Shield, and some more distant areas. Sources of older zircons are proposed - probably after multiple resedimentation - with greater distance, as for example the southern regions of the East African Orogen, in the Saharan Metacraton, or others such as European peri-Gondwanan sources, East-Asia or Australia (East African-Arabian Zircon Province). The data presented fill large gaps in the geochronological record of the Neoproterozoic-Ordovician succession of this region and contribute to our knowledge of the geological development and architecture at the northern edge of the Arabian-Nubian Shield. Based on the present study and published data we introduce a revised lithostratigraphic classification for the Ordovician to Silurian rocks in southern Jordan.