Age, provenance and tectonic setting of metasedimentary rocks of the Simlipal Complex, Singhbhum Craton, eastern India

Abstract The Simlipal Complex is a circular/elliptical structure at the eastern margin of the Singhbhum Craton in eastern India. The complex comprises metavolcanic and metasedimentary rocks and may represent the remnant of an Archean impact structure. Major and trace element abundances and zircon U–Pb ages from the metasedimentary rocks of the complex, which possibly constituted the target rocks of the impact, are used to constrain the provenance of the sediments and the tectonic environment of their deposition. The metasedimentary rocks include sandstones/quartzites and shales/slates/phyllites. CIA index and the A-CN-K discrimination diagram suggests moderate to extensive weathering of the source areas. The shales/slates/phyllites plot along the weathering trend of granite-granodiorite-tonalite, implying an average granodioritic source. The rare earth element (REE) patterns of shales/slates/phyllites are fractionated (LaN/YbN = 2.86–13.5) with nearly flat heavy-REE (GdN/YbN = 0.92–1.84) similar to Post Archean Australian shale. The Zr/Sc and Th/Sc ratios indicate zircon addition to sandstones/quartzites and mixing of mafic and felsic igneous rocks to shales/slates/phyllites. The shales/slates/phyllites are enriched in Sc, Cr, Ni, Y, Zr, Hf, Th, and U compared to Archean Upper Crust and have positive Cr and Ni anomalies suggesting contribution from mafic/ultramafic source. The major age peaks retrieved from detrital zircons in the metasediments are at 3.63 Ga, 3.46–3.26, 3.17–2.95, 2.87–2.75 Ga, and 2.54 Ga which correlate with ages reported for granitoid suites from different lithodemic units of the Singhbhum Craton. The sediments from the central and NW regions of the complex are dominated by zircons with an age of 3028 ± 15 Ma, while those from the NE regions and areas outside of it (e.g., the Kuliana region) have a preponderance of older zircon ages (ca. 3.25–3.38 Ga). The ages of the oldest metamorphic and the youngest detrital zircon population are suggestive of deposition of the sediments between ca. 2.8 Ga and 2.5 Ga. Crystallization ages and the shape of zircon crystals along with the geochemical signature of the sediments suggest that they were derived locally from the Singhbhum Craton and its surroundings.