https://reports.sci.am/index.php/reports <p><em data-start="0" data-end="19">Reports of NAS RA</em> (REPNAS) is a peer‑reviewed, open‑access journal of the National Academy of Sciences of Armenia that publishes high‑quality research across all STEM disciplines.</p> <p>REPNAS welcomes Original Research Articles, Review Articles, Short Research Papers, Letters, and Editorials that deliver solid and sound contributions, robust methodologies, and multidisciplinary insights of relevance to the global scientific community.</p> "GITUTYUN" PUBLISHING HOUSE OF NAS RA en-US Reports of NAS RA 0321-1339 https://reports.sci.am/index.php/reports/article/view/5 <p>Recently obtained biostratigraphic results in terrigenous sequences (shales and sandstones)&nbsp;intercalated between brachiopod-bearing limestones constitute an important breakthrough in&nbsp;our understanding of the chronostratigraphic framework of the Frasnian–Famenniantransitional interval. More precisely, miospores obtained from the Ertych section constrain the&nbsp;entire terrigenous sequence to the late Frasnian, while acritarches, prasinophytes and&nbsp;chitinozoans found in the same samples establish its accumulation in marine environments.&nbsp;Conodonts extracted from the Noravank section establish that the lower part of the terrigenous&nbsp;interval, dominated by shales, was accumulated during the linguiformis conodont zone. Taking&nbsp;into account the combined chronostratigraphic evidence in the two sections, it may be inferred&nbsp;that the terrigenous sequence accumulated in less than 240 thousand years. Our results give for&nbsp;the first time a relatively precise time framework to describe and reconstruct marine and&nbsp;terrestrial paleoecosystems that existed in the northern edge of the megacontinent Gondwana.</p> Taniel Danelian Vahram Serobyan Vachik Hairapetian Meline Tsatryan Sirush Khachatryan Meri Yeghiazaryan Nune Avagyan Tamara Hambardzumyan Gayane Kirakosyan Lusine Harutyunyan Vitalina Lokteva Anna Gasparyan Arayik Grigoryan Copyright (c) 2025 Taniel Danelian, Vahram Serobyan, Vachik Hairapetian, Meline Tsatryan, Sirush Khachatryan, Meri Yeghiazaryan, Nune Avagyan, Tamara Hambardzumyan, Gayane Kirakosyan, Lusine Harutyunyan, Vitalina Lokteva, Anna Gasparyan, Arayik Grigoryan https://creativecommons.org/licenses/by-nc/4.0 2025-09-25 2025-09-25 125 2 190 190