Strain localization and fluid-assisted deformation in apatite and its influence on trace elements and U–Pb systematics

From microanalysis to supercontinents: Insights from the Rio Apa Terrane into the Mesoproterozoic SW Amazonian Craton evolution during Rodinia assembly

“…Apatite grains from the Caracol Complex show different chemical signatures compared with those from the Porto Murtinho Complex with the former having lower REE contents and fractionated REE‐chondrite normalized profiles with HREE enrichment. These grains are predominantly classified as low‐ to medium‐grade metamorphic apatite (Figure 12a), in agreement with chemical characteristics of metamorphic/metasomatic apatite (Glorie et al, 2019; Henrichs et al, 2019, 2018; Ribeiro, Lagoeiro, et al, 2020). Apatite from samples FMR147 and FMR42 record c .…”

“…The 44069 monazite yielded an average 206 Pb/ 238 U age of 422 AE 2 Ma (MSWD = 0.3, N = 100), Madagascar apatite yielded an 207 Pb-corrected age (using the in-built Stacey and Kramers, 1975, correction in IsoplotR) of 490 AE 6 Ma (MSWD = 0.6, N = 32), OLT titanite yielded a concordia age of 1,009 AE 7 Ma (MSWD = 2.7, N = 13), and R632 rutile yielded a concordia age of 497 AE 5 Ma (MSWD = 1.1, N = 7). All secondary standards yielded ages in agreement with reference values for each standard and to the long-term reproducibility of the Isotopia Lab results (e.g., Ribeiro, Lagoeiro, et al, 2020;Ribeiro, Mulder, et al, 2020;Zoleikhaei et al, 2021).…”

“…Group 2 apatite from sample FMR104, however, has a much lower REE content and significant LREE depletion and is classified as low-to medium-grade metamorphic apatite. These chemical signatures are similar to those of recrystallized apatite (Ribeiro, Lagoeiro, et al, 2020), possibly indicating chemical re-equilibration during medium-grade deformation and metasomatism (Glorie et al, 2019;Odlum & Stockli, 2020;Ribeiro, Lagoeiro, et al, 2020). Apatite from sample FMR109 still preserves the original igneous chemistry and U-Pb age (1,970 AE 47 Ma) overlapping with zircon U-Pb ages from the Porto Murtinho Complex (Faleiros et al, 2016;, whereas apatite from samples FMR104 and FMR101 are c. 200 Ma younger than the average crystallization age of the Porto Murtinho Complex.…”

“…Group 2 apatite from sample FMR104, however, has a much lower REE content and significant LREE depletion and is classified as low‐ to medium‐grade metamorphic apatite. These chemical signatures are similar to those of recrystallized apatite (Ribeiro, Lagoeiro, et al, 2020), possibly indicating chemical re‐equilibration during medium‐grade deformation and metasomatism (Glorie et al, 2019; Odlum & Stockli, 2020; Ribeiro, Lagoeiro, et al, 2020).…”

Bulk inclusion micro‐zircon U–Pb geochronology: A new tool to date low‐grade metamorphism

“…rutile, hematite, and epidote) suggests crystallization of apatite during metamorphism. Combining the apatite chemistry and U-Pb data, it is apparent that metamorphic apatite is depleted in REE, Y, and U, consistent with that of Ribeiro et al (2020), and it is most likely that the apatite date can be linked to the inherited REE+Y-rich cores. The preservation of inherited apatite dates is not unexpected since the metamorphic temperatures of the sample (490℃) did not exceed the range of closure temperatures for Pb diffusion in apatite (350-550℃; Engi, 2017 and references therein).…”