Apatite as a monitor for petrogenetic processes and its implications for the provenance of sanukitoids and other Archean rocks from the Rio Maria Domain, southeastern of the Carajás Province, Brazil

Abstract

The granitogenesis of the Rio Maria domain, located in the southern of the Carajás province, is characterized by the presence of a variety of Archean granitoids formed between 2.98 and 2.86 Ga, along with Paleoproterozoic anorogenic granites dating to 1.88 Ga. The study of the morphology and chemical composition of apatites crystals has been employed to assess the magmatic evolution of igneous rocks. This work presents the results of chemical analyses conducted using an electron microprobe on apatites from sanukitoids in the regions of Rio Maria, Bannach, and Ourilândia do Norte, as well as from the Ba-Sr-rich leucogranodiorite Nova Canadá and the TTG-affinity Mogno trondhjemite, all of which are of Archean origin. Additionally, apatites crystals from the Paleoproterozoic oxidized anorogenic Seringa granite are included for comparison. Apatites crystals from the sanukitoids of Ourilândia do Norte and Rio Maria exhibit lower fluorine (F) content and higher levels of lanthanum (La), cerium (Ce), praseodymium (Pr), samarium (Sm), and europium (Eu) compared to similar sanukitoids found in Bannach. Based on the geochemical signatures of apatites crystals, it is suggested that the magmas of the sanukitoids of the Ourilândia do Norte and Rio Maria may have originated from mantle sources with a higher degree of metasomatism and/or enriched in rare earth elements (REE) and yttrium (Y), while the magmas of the Bannach sanukitoids may have derived from a mantle less intensely metasomatized and comparatively depleted in REE + Y. Apatite crystals from the Mogno trondhjemite and the Ba-Sr-rich Nova Canadá leucogranodiorite are depleted in REE + Y and resemble the apatites of the Bannach sanukitoids, although the apatites in the leucogranodiorite are more enriched in strontium (Sr).The Seringa granite has apatite crystals with higher F and REE + Y content when compared to apatites from the Archean rocks, indicating that apatite compositions can be used to distinguish between Archean and Paleoproterozoic granitoids, thus providing valuable contributions in provenance studies.