{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,12,20]],"date-time":"2025-12-20T21:55:58Z","timestamp":1766267758964,"version":"3.37.3"},"reference-count":29,"publisher":"Geological Institute, Bulgarian Academy of Sciences","issue":"2","funder":[{"DOI":"10.13039\/501100003336","name":"Bulgarian National Science Fund","doi-asserted-by":"publisher","award":["KP-06-N34\/6"],"award-info":[{"award-number":["KP-06-N34\/6"]}],"id":[{"id":"10.13039\/501100003336","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2022,8]]},"abstract":"<jats:p>The main goal of the present study is the characterization of the mineralogical and geochemical features of polymetallic (Mn- and Fe-bearing) nodules, lens- and layer-like bodies from different localities in the central part of the Late Cretaceous Srednogorie metallogenic zone, Bulgaria. The research is based on field studies, sampling and optical microscopy, followed by a combination of analytical techniques: XRD, SEM-EDS, ICP-OES and LA-ICP-MS methods. They define pyrolusite as the main ore mineral of the studied occurrences, while manganite, todorokite, bixbyite, sarkinite, hematite and hauerite are rarer. The most common gangue minerals are quartz, calcite and zeolites. Based on the MnO\/SiO2 ratio, the established minerals are divided into two groups: manganese (i) and silica-manganese (ii) phases, respectively. Their trace element composition is dominated by a high content of V, Zn, Mo, W, Co, Ni, Cu, As, Tl and Sr, whereas some of them belong to the group of the critical raw materials for high-tech products. The measured values for Y and rare earth elements of the studied oxides and hydroxides are low compared to their concentrations in modern polymetallic nodules of the Pacific Ocean. Chondrite-normalized patterns indicated weak LREE enrichment with respect to MREEs and HREEs, which are slightly depleted. Common weak to strong negative Ce anomaly, accompanied by various Sm and Eu anomalies, is also observed. The close proximity of the Late Cretaceous volcanic rocks to the Mn- and Fe-bearing ore mineralization and some structural and textural features of the studied minerals suggest hydrothermal origin of the main Mn-Fe ore occurrences in the Panagyurishte area.<\/jats:p>","DOI":"10.52321\/geolbalc.51.2.3","type":"journal-article","created":{"date-parts":[[2022,7,7]],"date-time":"2022-07-07T17:07:58Z","timestamp":1657213678000},"page":"3-17","source":"Crossref","is-referenced-by-count":4,"title":["New data on the geochemical and mineralogical features of the main manganese- and iron-bearing ore occurrences in the Central Srednogorie Zone, Bulgaria"],"prefix":"10.52321","volume":"51","author":[{"given":"Silvia","family":"Chavdarova","sequence":"first","affiliation":[{"name":"Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Milen","family":"Stavrev","sequence":"additional","affiliation":[{"name":"Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1361-9788","authenticated-orcid":false,"given":"Atanas","family":"Hikov","sequence":"additional","affiliation":[{"name":"Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1130-0861","authenticated-orcid":false,"given":"Irena","family":"Peytcheva","sequence":"additional","affiliation":[{"name":"Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"29796","published-online":{"date-parts":[[2022,7,7]]},"reference":[{"key":"ref0","unstructured":"Bal\u00e1\u017e, P. 2021. Results of the first phase of the deep-sea polymetallic nodules geological survey in the Interoceanmetal Joint Organization license area (2001\u20132016). Mineralia Slovaca 53 (1), 3\u201336."},{"key":"ref1","doi-asserted-by":"publisher","unstructured":"Chavdarova S., Stavrev, M., Hikov, A., Granchovski, G., Georgiev, S., Peytcheva, I. 2021. Geochemical characteristics of the Toplika manganese- and iron-bearing ore occurrence, central part of the Srednogorie Zone, Bulgaria: Preliminary results. Review of the Bulgarian Geology Society 82 (3), 43\u201345, https:\/\/doi.org\/10.52215\/rev.bgs.2021.82.3.43.","DOI":"10.52215\/rev.bgs.2021.82.3.43"},{"key":"ref2","doi-asserted-by":"publisher","unstructured":"Dekov, V., Maynard, B., Kamenov, G., Rouxelb, O., Lalonde, S., Juranov, S. 2020. Origin of the Oligocene manganese deposit at Obrochishte (Bulgaria): Insights from C, O, Fe, Sr, Nd, and Pb isotopes. Ore Geology Reviews 122, 1\u201327, https:\/\/doi.org\/10.1016\/j.oregeorev.2020.103550.","DOI":"10.1016\/j.oregeorev.2020.103550"},{"key":"ref3","unstructured":"Dimitrov, T., Kostov, I. 1954. On the genesis of manganese ore deposits in Srednogorie. Annuaire de l\u2019Universit\u00e9 de Sofia, Facult\u00e9 de biologie, g\u00e9ologie et g\u00e9ographie 48 (2), 24\u201361 (in Bulgarian, with English abstract)."},{"key":"ref4","unstructured":"Dimitrova, D., Milakovska, Z., Peytcheva, I., Stefanova, E., Stoyanova, V., Abramowski, T. 2014. Trace and REE in micronodules from bottom sediments (Interoceanmetal exploration area, NE Pacific Ocean) determined by in situ LA-ICP-MS. National Conference with International Participation \u201cGeosciences 2012\u201d, Abstracts, 15\u201316."},{"key":"ref5","unstructured":"Dimitrova, E., Nachev, I., Slavov, S. 1984. Upper Cretaceous stratigraphy of the Panagyurishte area. Bulletin of the Geological Institute, Series Paleontology, Stratigraphy and Lithology 19, 65\u201384 (in Bulgarian, with English abstract)."},{"key":"ref6","doi-asserted-by":"publisher","unstructured":"Dubinin, A. 2004. Geochemistry of Rare Earth Elements in the ocean. Lithology and Mineral Resources 39, 289\u2013307, https:\/\/doi.org\/10.1023\/B:LIMI.0000033816.14825.a2.","DOI":"10.1023\/b:limi.0000033816.14825.a2"},{"key":"ref7","doi-asserted-by":"publisher","unstructured":"Gallhofer, D., von Quadt, A., Peytcheva, I., Schmid, S., Heinrich, C. 2015. Tectonic, magmatic, and metallogenic evolution of the Late Cretaceous arc in the CarpathianBalkan orogen. Tectonics 34 (9), 1813\u20131836, https:\/\/doi.org\/10.1002\/2015TC003834.","DOI":"10.1002\/2015tc003834"},{"key":"ref8","doi-asserted-by":"publisher","unstructured":"Hein, J., Mitzell, K., Koschinsky, A., Conrad, T. 2013. Deepocean mineral deposits as a source of critical metals for highand green-technology applications: Comparison with landbased resources. Ore Geology Reviews 51, 1\u201314, https:\/\/doi.org\/10.1016\/j.oregeorev.2012.12.001.","DOI":"10.1016\/j.oregeorev.2012.12.001"},{"key":"ref9","doi-asserted-by":"publisher","unstructured":"Hikov, A. 2013. Geochemistry of hydrothermally altered rocks from the Assarel porphyry copper deposit, Central Srednogorie. Geologica Balcanica 42 (1\u20133), 3\u201328, https:\/\/doi.org\/10.52321\/GeolBalc.42.1-3.3.","DOI":"10.52321\/geolbalc.42.1-3.3"},{"key":"ref10","doi-asserted-by":"crossref","unstructured":"Hikov, A., Milakovska, Z., Stoyanova, V., Stefanova, E., Abramowski, T., Chavdarova, S., Stavrev, M. (2022). REE and trace elements distribution in the deep-sea sediments from the Interoceanmetal (IOM) polymetallic nodule exploration area in the Clarion-Clipperton fractures zone, NE Pacific. Comptes rendus de l\u2019Acad\u00e9mie bulgare des Sciences 75 (in press).","DOI":"10.7546\/CRABS.2022.07.10"},{"key":"ref11","unstructured":"Iliev, K., Katskov, N. 1990. Geological map of Bulgaria in scale 1:100 000, Panagyurishte map sheet. Company for Geophysical Surveys and Geological Mapping, Sofia."},{"key":"ref12","unstructured":"Ivanov, \u017d. 2017. Tectonics of Bulgaria. Sofia University Press, Sofia, 331 pp. (in Bulgarian, with English abstract)."},{"key":"ref13","unstructured":"Karagjuleva, J., Kostadinov, V., Tsankov, T., Gochev, P. 1974. Structure of the Panagyurishte strip east of the Topolnitsa River. Bulletin of the Geological Institute, Series Geotectonics 23, 231\u2013301 (in Bulgarian, with English and Russian abstracts)."},{"key":"ref14","unstructured":"Katskov, N., Iliev, K. 1993. Explanatory note for the geological map of Bulgaria in scale 1:100 000, Panagyurishte map sheet. Company for Geophysical Surveys and Geological Mapping, Sofia, 54 pp. (in Bulgarian, with English abstract)."},{"key":"ref15","unstructured":"Kostov, I., 1945. Classification of the manganese ore deposits and their provincial relationship. Annuaire de l\u2019Universit\u00e9 de Sofia, Facult\u00e9 physico-math\u00e9matique (Sciences naturelles) 3, 133\u2013174 (in Bulgarian, with English abstract)."},{"key":"ref16","doi-asserted-by":"publisher","unstructured":"Kouzmanov, K., Moritz, R., von Quadt, A., Chiaradia, M., Peytcheva, I., Fontignie, D., Ramboz, C., Bogdanov, K. 2009. Late Cretaceous porphyry Cu and epithermal Cu\u2013Au association in the Southern Panagyurishte District, Bulgaria: The paired Vlaykov Vruh and Elshitsa deposits. Mineralium Deposita 44 (6), 611\u2013646, https:\/\/doi.org\/10.1007\/s00126-009-0239-1.","DOI":"10.1007\/s00126-009-0239-1"},{"key":"ref17","doi-asserted-by":"publisher","unstructured":"Melfos, V., Voudouris, P. 2012. Geological, mineralogical and geochemical aspects for critical and rare metals in Greece. 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Annuaire de la Direction G\u00e9n\u00e9rale des Recherches G\u00e9ologiques 11, 117\u2013132 (in Bulgarian, with German and Russian abstracts)"}],"container-title":["Geologica Balcanica"],"original-title":[],"language":"en","deposited":{"date-parts":[[2023,2,11]],"date-time":"2023-02-11T03:09:08Z","timestamp":1676084948000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.geologica-balcanica.eu\/journal\/51\/2\/pp.-3-17"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2022,7,7]]},"references-count":29,"journal-issue":{"issue":"2","published-online":{"date-parts":[[2022,8]]},"published-print":{"date-parts":[[2022,8]]}},"URL":"https:\/\/doi.org\/10.52321\/geolbalc.51.2.3","relation":{},"ISSN":["2535-1060","0324-0894"],"issn-type":[{"type":"electronic","value":"2535-1060"},{"type":"print","value":"0324-0894"}],"subject":[],"published":{"date-parts":[[2022,7,7]]}}}