Proterozoic tectonic evolution of the Tarim Craton: New insights from detrital zircon U-Pb and Lu-Hf isotopes of metasediments in the Kuruktag area

The Proterozoic is the longest Eon in geological history and witnessed the assemblies and breakups of the Columbia and Rodinia supercontinents. The Tarim Craton has been proposed to be a building block of these supercontinents. However, its tectonic evolution during late Paleoproterozoic to earliest Neoproterozoic (ca. 1.8-0.8 Ga) has been poorly understood, due to the paucity of geological record. In this paper, we present U-Pb and Lu-Hf isotopic data for detrital zircons from the metasediments of the early Neoproterozoic Paergangtag Group and the Paleoproterozoic Xinditag Group in the Kuruktag area, northern Tarim Craton. Although formed approximately 1 billion years later, the Paergangtag Group contains detrital zircons almost identical to those in the Xinditag Group. LA-ICP-MS U-Pb dating yields a ca. 2.0 Ga age peak, as well as a group of older zircons of ca. 2.5 Ga in six samples from these two groups. Lu-Hf data show that the ca. 2.0 Ga zircons have variable epsilon Hf(t) values (- 28.1 to 0.1), indicating the detritus were mostly derived from reworked continental crusts. The older zircons around 2.5 Ga have both negative and positive epsilon Hf(t) values (- 28.5 to 9.5), indicating a prolonged and complicated crustal growth and reworking process in the source area. It is inferred that the zircons in these samples were likely derived from southeastern Tarim Craton, where a ca. 2.0 Ga orogenic event has been documented. The fact that the Neoproterozoic Paergangtag Group contains only Paleoproterozoic and older zircons suggests that the Tarim Craton was not involved in the Grenville Orogeny, which developed between the colliding continents in the interior of the Rodinia Supercontinent. In contrast, the Tarim Craton was probably on the periphery of the Rodinia Supercontinent and was involved in the peripheral subduction zone of the supercontinent shortly after the deposition of the Paergangtag Group. Our new data imply that the Tarim Craton might have been a tectonically stable continent for nearly 1 billion years from ca. 1.8 to 0.9 Ga.