LA-ICP-MS U-Pb dating of the detrital zircons from clastic rocks of Naij Tal Group in East Kunlun and its geological implications

Naij Tal Group consists of a set of ophiolitic mélanges. Therefore, some evidence for restoring the structural pattern of east Kunlun in Early Palaeozoic can be obtained by studying Naij Tal Group’s formation time and provenance. Most previous researchers hold the opinion that Naij Tal Group belongs to Ordovician or Ordovician-Silurian; nevertheless, other viewpoints arguing for Silurian, Permian or Cenozoic are also existent. The authors obtained the youngest age 538±10Ma by LA-ICP-MS U-Pb dating of the detrital zircons from Naij Tal Group’s clastic rocks and thus confined its formation time to 538-427Ma in combination the intrusion age of 427.7Ma. Thus, the formation age of Naij Tal Group was assigned to Ordovician because of its special geological significance. Moreover, there are five age peaks existent in Naij Tal Group’s detrital zircons, i.e., ~2450Ma, ~1100Ma, ~980Ma, ~810Ma, and ~650Ma. The authors thus suppose that Baishahe Group, Xiaomiao Group, Wanbaogou Group and magmatic rocks formed during early Neoproterpzoic were provenances of Naij Tal Group’s clastic rocks because of the similar distributions of their zircon ages. It is also held that the source areas might have experienced early Paleoproterozoic, late Paleoproterozoic, late Mesoproterpzoic and early Neoproterpzoic tectono-magmatic events according to the characteristics of their zircon U-Pb ages.