The Middle Buntsandstein Subgroup of the Lower Triassic of north-eastern Poland has been investigated in the context of possible marine ingressions into the Central European Basin. To better constrain these, palynofacies analysis and mineralogical analysis of mudstones were undertaken on samples taken from the Lidzbark and Malbork formations penetrated by the Bartoszyce IG 1 borehole, serving as stratotype section of both lithostratigraphic units. Microfacies and geochemical analyses, including C and O isotope analysis, were conducted additionally on oolitic limestones of the basal Lidzbark Formation (the lowermost Middle Buntsandstein), and the boron content was measured on all mudstone samples. Seven palynofacies types are distinguished: types 1 to 3 within the Malbork Formation and types 4 to 7 within the Lidzbark Formation. Types 1 and 2 originated on a floodplain, type 3 probably in a deltaic or barrier setting, and types 4 and 5 in a brackish lagoon or a more open basin, possibly of marine origin. Palynofacies type 6 reflects long transport and reworking, whereas palynofacies type 7 is interpreted as formed due to pedogenic processes. Clay minerals and quartz, accompanied by feldspars, calcite and dolomite are the main components of the mudstones investigated. The clay mineral association consists of illite or a mixture of illite and smectite, and chlorite. The Lidzbark Formation and the lowermost part of the Malbork Formation show less variability in mineralogical composition than the upper part of the Malbork Formation. Smectite admixtures were detected only in the upper part of the Malbork Formation (the uppermost Middle Buntsandstein). The boron content, achieved after aqua regia digestion, ranges from 70 to 121 mg/kg (96 mg/kg at average), oscillating generally around 90 mg/kg. A higher boron content, bound in silicate structure, is associated with the upper part of the Malbork Formation. All major mineralogical and geochemical changes coincide more or less with the transition from the supposed marine to the terrestrial environmental realm, interpreted from lithological and sedimentological observations within the lowermost part of the Malbork Formation. However, diagenetic alteration of the clay minerals, and of the boron content, could not be ruled out. The oolitic limestones, mainly grainstones, contain admixtures of quartz grains and rare bioclasts, the ooids nuclei being peloids or unrecognizable. The carbonates are almost exclusively composed of low-Mg calcite. A high content of Mg and the presence of small amounts of dolomite suggest that the ooids were primarily composed of high-Mg calcite and are comparable with similar Early Triassic deposits in Tethyan settings. The δ¹³C values range from –2 to +1‰ VPDB, fitting well with the known ranges of Lower Triassic marine carbonates. An observed δ¹³C depletion towards the top of the oolite-bearing part of the section may reflect a local shallowing trend that led to overall salinity decrease. A possible connection with the one of the global oceanic geochemical episodes has to be tested further. The results obtained suggest a marine origin of the lower Middle Buntsandstein deposits studied and document a terrestrial origin for the upper Malbork Formation.

在可能的海洋侵入中欧盆地的背景下，对波兰东北部下三叠统的中Buntsandstein子群进行了研究。为了更好地约束这些，对取自Bartoszyce IG 1钻孔的Lidzbark和Malbork地层的样品进行了岩相分析和矿物学分析，这是两个岩性地层学单元的层状剖面。此外，还对基底利兹巴克组（最低的中下桑丹斯坦）的鲕状石灰石进行了微相和地球化学分析，包括碳和氧同位素分析，并测量了所有泥岩样品中的硼含量。区分出七种古孢类型：马尔堡组为1至3型，利兹巴克组为4至7型。1型和2型起源于洪泛区，3型可能起源于三角洲或屏障环境，4型和5型起源于咸水泻湖或较开放的盆地，可能是海洋起源的。6型的孢子虫反映出较长的运输和返工，而7型的孢子虫则被解释为是由成岩作用形成的。粘土矿物和石英以及长石，方解石和白云石是所研究泥岩的主要成分。粘土矿物组合由伊利石或伊利石和蒙脱石以及绿泥石的混合物组成。利兹巴克组和马尔堡组的最下部在矿物学组成上的变异性小于马尔堡组的上部。仅在马尔堡组的上部（最中生布兹坦斯坦）发现了蒙脱石外加剂。硼含量 王水消化后达到的剂量范围为70至121 mg / kg（平均96 mg / kg），通常在90 mg / kg左右振荡。绑定在硅酸盐结构中的较高硼含量与马尔堡组的上部有关。所有主要的矿物学和地球化学变化或多或少都与从假定的海洋向陆地环境领域的转变相吻合，这从马尔堡组最下部的岩性和沉积学观测解释。但是，不能排除粘土矿物和硼含量的成岩作用。鲕粒型石灰石（主要是花岗石）含有石英粒和稀有的生物碎屑的混合物，卵母细胞核是倍性或无法识别的。碳酸盐几乎完全由低镁方解石组成。镁含量高和少量白云石的存在表明，该卵石主要由高镁方解石组成，可与特提斯地区类似的早三叠世沉积物相提并论。δ¹³ C值的范围从–2到+ 1‰VPDB，非常适合下三叠纪海相碳酸盐岩的已知范围。观察到的δ ¹³朝向部分的鲕状岩轴承部的顶部Ç耗尽可能反映了局部变浅的趋势，导致整体盐度降低。与全球海洋地球化学事件之一的可能联系必须进一步测试。所获得的结果表明，研究的中下Buntsandstein沉积物是海洋成因，并记录了上马尔伯克组的陆源。