Geochemical and Lu/Hf isotopic (LA-ICP-MS) signature of detrital zircons from sandstones of the basal levels of the Riphean stratotype

• Published in: Doklady earth sciences Vol. 459; no. 1; pp. 1356 - 1360
• Main Authors: Romanyuk, T. V., Kuznetsov, N. B., Maslov, A. V., Belousova, E. A., Krupenin, M. T., Ronkin, Yu. L., Gorozhanin, V. M., Gorozhanina, E. N.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01.11.2014; Springer; Springer Nature B.V
• Subjects: Age; Analysis; Chemical properties; Diorite; Earth and Environmental Science; Earth Sciences; Geochemistry; Geology; Grains; Hafnium; Isotopes; Mineralogy; Porphyry; Rocks; Sandstones; Syenite; Trace elements; Zircon; Zirconium; Source Rock; 206Pb; Orogen; Sandstone; Detrital Zircon
• ISSN: 1028-334X; 1531-8354
• DOI: 10.1134/S1028334X14110257

This paper presents the results of selective study of trace elements (29 analyses) and the Lu/Hf isotopic system (41 analyses) in preliminarily dated (U-Pb) detrital zircons (dZr s ) from sandstones of the Ai Formation of the Burzyan Group of the Bashkirian Anticlinorium, which compose the basal horizons of the typical Riphean section of the Southern Urals. The statistically processed trace-element patterns of dZr s showed that “diorites” were dominant over “syenites” among the source rocks of dZr s . The rock types estimated by trace-element patterns for the cores and rims of two large grains (“diorite” and “syenite”) coincided. The analysis of the Lu/Hf isotopic system of dZr s revealed a wide dispersion of the ɛ Hf value from +7.1 to −20.1 at the T DM C model age of the substrate from 2.25 to 3.95 Ga. Four grains (in one case with the core and rim studied) from the population of the large transparent cherry zircons (TCZ) are characterized by the “syenitic” rock type and extremely ancient T DM C values of 3.22, 3.45, 3.64, 3.66, and 3.75 Ga at ages of zircons of 2486, 2784, 2873, 1977, and 1984 Ma, respectively. Two “dioritic” grains from the TCZ population have significantly distinct parameters: 2.37 and 2.51 Ga at 2049 and 2057 Ma, respectively. It is evident that this specific population of dZr s was formed with a significant contribution of very ancient crustal material, which became active under “syenitic” magmatism and provided the T DM C value of >3.5 Ga. Numerous juvenile dZr s form a compact cluster, which correspond to the rocks of the southern part of the Volga-Sarmatian orogen (age of 2.1–2.0 Ga, T DM C = 2.1–2.4 Ga). The complexes of the entire the Volga-Uralia, the Volga-Sarmatian orogen, and adjacent areas could be the provenance areas for the Ai sandstones in contrast to the northeastern areas of the East-European Platform with dominant “granitic” source rocks and T DM C values lower than 3.5 Ga.