The Role of Heavy Minerals in Understanding the Provenance of Sandstone: An Example from the Upper Cretaceous Tanjero Formation, Surdash Region, Northeastern Iraq

Abstract

The Tanjero Formation is the Upper Cretaceous (Campanian-Maastrichtian) crops out in northeastern Iraq at the High-Folded and Imbricate Zones. To study heavy minerals, twenty sandstone samples were obtained from selected sites of the Tanjero Formation exposed at the southwestern limb of the Surdash anticline in the northeast part of Sulaimanyia city. The analyzed data indicates that the most abundant heavy minerals are opaque, followed by pyroxene, epidote, amphibole, chlorite, rutile, and garnet. The significant abundance of unstable and metastable minerals in the heavy mineral suites shows their direct derivation from the adjacent main basic igneous and metamorphic source rocks, which are situated in the High-Folded and Imbricate Zones in the northern and northeastern parts of Iraq. The estimated zircon-tourmaline-rutile index reveals that the majority of the sandstone samples have less than 75% zircon-tourmaline-rutile index, indicating that the sediments are generally immature. Furthermore, the relationship between an ultra-stable and a meta-stable heavy mineral indicated the immaturity of the Tanjero Formation sandstone and its moderate stability, proving that these minerals cannot be transported over extremely long distances close to the source rocks area. The heavy mineral assemblage demonstrated that the studied area is distinguished by high tectonic activity. In addition, according to the MF- MT-GM ternary diagram, the analyzed sandstone samples lie within the active continental margins field, which is distinguished by a higher percentage of MF minerals than GM minerals generated from mafic magmatic source rocks.