• The Astingbulake IF was deposited at ∼1.92–1.89 Ga, consistent with the timing of global post-GOE IFs. • The host rocks of the IF are derived from mildly to moderately weathered felsic sources of stable continental crust. • The Astingbulake IF was deposited along a passive continental margin, it is suggested that intense submarine volcanism is not a prerequisite for post-GOE IF formation. The abundance of Precambrian iron formations (IFs) decreased significantly following the Great Oxidation Event (GOE). Although it is widely accepted that this decrease was a result of the GOE, reactivation of massive IF deposition occurred during specific time periods after the GOE, particularly at ca. 1.9 Ga (herein termed “post-GOE IFs”). The occurrence of these IFs indicates pulsed changes in marine redox states or physicochemical conditions during the late Paleoproterozoic. The post-GOE IFs that have been discovered are largely distributed in North America and Western Australia. Due to their limited distribution, the mechanisms by which they formed and their geological significance remain poorly constrained. This contribution presents geochronological together with geochemical data for the metasedimentary rocks hosting the Astingbulake IF and geochemical data of spatially associated intrusive rocks in northeastern Tarim Craton, in order to constrain the depositional as well as tectonic setting of the Astingbulake IF and thereby provide new constraints on the deposition of post-GOE IFs. Combining the weighted mean age of the youngest detrital zircons (1920 ± 6 Ma, n = 28, MSWD = 0.63) from the underlying metasedimentary rocks with zircon U–Pb ages of from the intrusive rocks (ca. 1890 Ma) that crosscut the IF, the depositional age of the Astingbulake IF is restricted to ca. 1.92–1.89 Ga. Mineral assemblages, and major- and trace-element characteristics of the metasedimentary rocks suggest that their protoliths were largely mudstones and sandstones, with detrital inputs derived predominantly from stable continental crust. Combined petrological and geochemical characteristics suggest that these rocks formed within a passive continental margin, implying that the Astingbulake IF was deposited in a shelf environment. This contribution identifies a large-scale IF unit of ca. 1.9 Ga in the Tarim Craton, which corresponds to the main depositional period of post-GOE IFs globally. This discovery suggests that deposition of IFs in the late Paleoproterozoic was extensive and holds global geological significance. Combined with previous research, this contribution provides new geological evidence and insights into the pulsed deposition of post-GOE IFs and suggests that intense submarine volcanic activity is not a prerequisite for controlling the formation of post-GOE IFs.
Li et al. (Wed,) studied this question.