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Abstract <p>Granites forming cross‑cutting veins in the doleritic sills were first studied in the Paleoproterozoic Onega Large Igneous Province (LIP). Age of zircon from granite veins based on U–Th–Pb (LA-ICP-MS) is estimated to be 1956 ± 7 Ma and that of baddeleyite from host dolerites (U–Pb (ID TIMS)) is 1965 ± 4&#xa0;Ma, suggesting they belong to a single episode of igneous activity of age ca. 1.96 Ga. Based on chemical composition and distribution patterns of trace elements, the granites of the veins belong to the A<sub>2</sub> type. Nevertheless, results of partial melting modeling of basement granites and Jatulian terrigenous sedimentary rocks suggest that they could not have served as sources of silica-rich melts. The modeling of fractional crystallization of melts similar in composition to dolerite sills, along with the presence of an inherited ancient component in zircons from granitic veins, indicate that the A-type granite veins in the Onega LIP originated via fractionation of basaltic melts accompanied by assimilation of ancient crustal material.</p>

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A-Type 1.96 Ga Granites in the Onega Large Igneous Province, Karelian Craton

  • 期刊论文

  • 发表日期：

    2026年4月23日

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  • V. V. Ustinova,
  • A. V. Stepanova,
  • M. A. Sukhanova,
  • E. B. Salnikova,
  • K. G. Erofeeva,
  • A. V. Samsonov,
  • K. N. Bessmertnyi,
  • O. A. Maksimov,
  • O. M. Silaeva,
  • A. A. Fedorov

摘要

Abstract

Granites forming cross‑cutting veins in the doleritic sills were first studied in the Paleoproterozoic Onega Large Igneous Province (LIP). Age of zircon from granite veins based on U–Th–Pb (LA-ICP-MS) is estimated to be 1956 ± 7 Ma and that of baddeleyite from host dolerites (U–Pb (ID TIMS)) is 1965 ± 4 Ma, suggesting they belong to a single episode of igneous activity of age ca. 1.96 Ga. Based on chemical composition and distribution patterns of trace elements, the granites of the veins belong to the A2 type. Nevertheless, results of partial melting modeling of basement granites and Jatulian terrigenous sedimentary rocks suggest that they could not have served as sources of silica-rich melts. The modeling of fractional crystallization of melts similar in composition to dolerite sills, along with the presence of an inherited ancient component in zircons from granitic veins, indicate that the A-type granite veins in the Onega LIP originated via fractionation of basaltic melts accompanied by assimilation of ancient crustal material.