The ages of several Oligocene to Miocene sedimentary formations from the Eastern Carpathians Bend Zone are poorly constrained due to palaeoenvironmental factors, reworking of fossils, structural complexity and limited exposure. To help overcome these issues, this study integrates calcareous nannoplankton and foraminifera biostratigraphy with isotopic age dating (U-Pb) of volcaniclastic zircons, and sedimentological and structural observations/interpretations. Our study was carried out along an ~6-km-long section made from a series of outcrops along the Bizdidel River which exposes several formations such as the Pucioasa, Fusaru, Vinețișu, Starchiojd and Slon. We show that the Fusaru Formation consists of coarse-grained rocks deposited as confined longitudinal channel successions that migrated laterally. It is bounded by the mud-rich Pucioasa and Vinețișu formations which are lateral equivalents of the Fusaru confined channels deposited as levee/overbank units. These genetically related formations appear to reach younger ages – of the lower to middle Burdigalian based on calcareous nannoplankton and foraminifera biostratigraphy – than previously thought (upper Oligocene to lower Burdigalian). The dominant organic-rich mudstones of the Starchiojd Formation represent pelagites/hemipelagites deposited in anoxic conditions. Their middle Burdigalian age is established by a 17.41 ±0.27 Ma zircon U-Pb age of zircons from the Bătrâni Tuff in the Starchiojd Formation. Based on the similar phenocryst content, zircon U-Pb age and zircon trace element composition, the source of the tuff is suggested to be the 17.3 Ma Eger ignimbrite-forming eruption, which has proximal, near-caldera deposits in the Bükkalja Volcanic Field, Hungary. The mud-rich Slon Formation seems to be related to shelf edge/upslope failure that formed cohesive debrite avalanches resulting from foreland propagation of compression. The Slon Formation extends in this area to at least the upper part of the lower Miocene to middle Miocene. These results highlight the need to revise ages of those parts of the sequence which are poorly constrained or different in other parts of the Carpathian Basin. Such revised ages help to better constrain the understanding of the deformation history of the Carpathians.

由于古环境因素、化石改造、结构复杂性和有限的暴露，东喀尔巴阡山脉弯曲带的几个渐新世到中新世沉积层的年龄很难确定。为了帮助克服这些问题，本研究将钙质超微浮游生物和有孔虫生物地层学与火山碎屑锆石的同位素测年 (U-Pb) 以及沉积学和结构观察/解释相结合。我们的研究是沿着 Bizdidel 河沿岸的一系列露头组成的约 6 公里长的部分进行的，该部分暴露了几个地层，如 Pucioasa、Fusaru、Vineşişu、Starchiojd 和 Slon。我们表明，Fusaru 地层由粗粒岩石组成，这些岩石沉积为横向迁移的受限纵向河道序列。它以富含泥浆的 Pucioasa 和 Vineşişu 地层为界，它们是 Fusaru 封闭河道的横向等效物，沉积为堤坝/河堤单元。这些与遗传相关的地层似乎比以前认为的（渐新世上部到下部 Burdigalian）更年轻——基于钙质超微浮游生物和有孔虫生物地层学的下 Burdigalian 到中部 Burdigalian。Starchiojd 地层的主要富含有机质泥岩代表在缺氧条件下沉积的角质层/半角质层。他们的 Burdigalian 中期年龄由来自 Starchiojd 地层 Bătrâni 凝灰岩的 17.41 ±0.27 Ma 锆石 U-Pb 年龄确定。根据相似的斑晶含量、锆石U-Pb年龄和锆石微量元素组成，推测凝灰岩的来源为17.3 Ma Eger ignimbrite-forming喷发，在匈牙利的 Bükkalja 火山区有近端、近火山口的矿床。富含泥浆的 Slon 地层似乎与陆架边缘/上坡破坏有关，这些破坏形成了由前陆压缩扩展引起的粘性碎屑崩塌。Slon 地层在该区域至少延伸到下中新世的上部至中中新世。这些结果突出表明需要修改层序中那些在喀尔巴阡盆地其他部分约束不力或不同的部分的年龄。这样修正的年龄有助于更好地约束对喀尔巴阡山脉变形历史的理解。富含泥浆的 Slon 地层似乎与陆架边缘/上坡破坏有关，这些破坏形成了由前陆压缩扩展引起的粘性碎屑崩塌。Slon 地层在该区域至少延伸到下中新世的上部至中中新世。这些结果突出表明需要修改层序中那些在喀尔巴阡盆地其他部分约束不力或不同的部分的年龄。这样修正的年龄有助于更好地约束对喀尔巴阡山脉变形历史的理解。富含泥浆的 Slon 地层似乎与陆架边缘/上坡破坏有关，这些破坏形成了由前陆压缩扩展引起的粘性碎屑崩塌。Slon 地层在该区域至少延伸到下中新世的上部至中中新世。这些结果突出表明需要修改层序中那些在喀尔巴阡盆地其他部分约束不力或不同的部分的年龄。这样修正的年龄有助于更好地约束对喀尔巴阡山脉变形历史的理解。