The Miocene genus Rzehakia, an endemic brackish bivalve that lived in the Paratethys Sea, recorded in late Ottnangian sediments deposited during the regression of the Central Paratethys Sea in the semi-enclosed Alpine-Carpathian foreland basin, is closely related to the Rzehakia found hundreds of kilometres away in the early Badenian transgressive sequence situated in the Western Carpathians hinterland. The finding of the “Rzehakia beds” from the Malý Krtíš site in the Novohrad-Nógrád Basin provides insight into the palaeobiogeography of the Central Paratethys. The present study documents Rzehakia-bearing deposits of an alternating wave-dominated, river-influenced environment and of a fluvial-dominated, tide-influenced, wave-affected environment, probably located on the prodelta slope of a compound deltaic clinoform. Corresponding calcareous nannofossil assemblages, marked by the absence of Sphenolithus belemnos and the co-occurrence of Helicosphaera ampliaperta with Sphenolithus heteromorphus without Helicosphaera waltrans, indicate the NN4 Zone. Furthermore, the presence of the regional benthic foraminiferal marker Uvigerina graciliformis indicates a Karpatian age and the planktic Globorotalia transsylvanica restricts the profile stratigraphic range to the upper Burdigalian-Langhian part of the NN4 Zone (i.e., upper Karpatian-lower Badenian). In accordance with updated palaeogeographic data, these results led us to the conclusion that the “Rzehakia beds” in the Novohrad-Nógrád Basin are synchronous with or younger than those from the Alpine-Carpathian Foredeep and are possibly related with their middle Miocene (late Kotzakhurian–early Tarkhanian) occurrences in the Eastern Paratethys.

中文翻译：

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潘诺尼亚盆地北部陆架上的“Rzehakia 层”：生物地层学和古环境意义

中新世 Rzehakia 属是一种生活在 Paratethys 海的地方性微咸双壳类动物，记录在半封闭的高山喀尔巴阡前陆盆地中央 Paratethys 海海退期间沉积的晚期 Ottnangian 沉积物中，与 Rzehakia 密切相关，发现了数百种位于西喀尔巴阡山脉腹地的早期巴登阶海侵序列中。在 Novohrad-Nógrád 盆地的 Malý Krtíš 遗址发现的“Rzehakia 层”提供了对 Central Paratethys 的古生物地理的深入了解。本研究记录了交替的波浪主导、河流影响环境和河流主导、潮汐影响、波浪影响环境的含 Rzehakia 的沉积物，可能位于复合三角洲斜面的前三角洲斜坡上。相应的钙质纳米化石组合，以不存在 Sphenolithus belemnos 和 Helicosphaera ampliaperta 与 Sphenolithus heteromorphus 的共同出现为标志，而没有 Helicosphaera waltrans，表明 NN4 区域。此外，区域底栖有孔虫标记 Uvigerina graciliformis 的存在表明了 Karpatian 时代，并且浮游的 Globorotalia transsylvanica 将剖面地层范围限制在 NN4 区的上布尔迪加尔 - 朗吉亚部分（即上卡帕蒂安 - 下巴登）。根据更新的古地理资料，