A wide range of proxies (organic and inorganic geochemistry, gamma-ray spectrometry, microfacies, framboidal pyrite analysis) were applied in order to decipher changes in depositional conditions during the mid-Tournaisian anoxic event, referred to as the Lower Alum Shale Event (LASE) in the Polish part of the Laurussia basin. The LASE part of the section, unlike older Tournaisian deposits, is characterised by high concentrations of isorenieratane, palaeorenieratane, and their diagenetic derivatives, the occurrence of 2-methyl-3-iso-butyl-maleimides, and high values of the sterane-to-hopane ratio. The predominance of tiny pyrite framboids, inorganic data such as low values of the Th/U and high values of the C_org/P and V/Cr ratios, and generally higher enrichments of redox-sensitive metals such as U, V, Mo, Pb, and Zn and depletion in Mn, all suggest anoxic/euxinic conditions on the sea-bottom. The results of our investigations, especially Co, Mn, Cd, and Mo distribution patterns, demonstrate that enhanced primary productivity in the water column was responsible for a high degree of organic carbon burial rather than preservation in restricted conditions on the seafloor. This elevated productivity may have been generated by the upwelling of nutrient-rich deep water, an increase in volcanic activity and volcanogenic oceanic fertilisation, or both. Volcanically driven mid-Tournaisian climatic changes (warming), as manifested by high Zr concentrations and Hg anomalies, may have been responsible for the deglaciation of Gondwana resulting in the global crenulata transgression.

The global rise in sea level and high level of organic productivity were responsible for the development of anoxic conditions and the halt of carbonate production, as reflected by drastic changes of facies not only in the sections investigated, but in many other parts of the world as well.

为了解释中途缺氧事件（称为下矾土页岩事件（LASE））中沉积条件的变化，应用了广泛的代理（有机和无机地球化学，伽马射线能谱，微相，黄铁矿黄铁矿分析）。 ）在月桂盆地的波兰部分。该部分的LASE部分与较旧的Tournaisian矿床不同，其特点是高浓度的异麦角烷，古麦角烷及其成岩衍生物，2-甲基-3-异丁基-马来酰亚胺的出现，以及-霍比。微小的黄铁矿framboids，如的Th / U的低值以及C的高值无机数据的优势_有机/ P和V / Cr比值，以及通常对U，V，Mo，Pb和Zn等氧化还原敏感金属的富集度较高，以及Mn的耗竭率均表明海底存在缺氧/富余状态。我们的研究结果，尤其是Co，Mn，Cd和Mo的分布模式，表明水柱中初级生产力的提高导致高度的有机碳埋藏，而不是在受限的海底条件下保存。生产力的提高可能是由于营养丰富的深水上升，火山活动增加和火山成因的海洋肥力增加或两者兼而有之。较高的Zr浓度和Hg异常表明，火山驱动的中古突尼斯气候变化（变暖）可能是导致冈瓦纳河冰消作用的原因，海藻侵害。

全球海平面的上升和有机生产力的高高是造成缺氧条件和碳酸盐生产停滞的原因，不仅在所调查的部分，而且在世界许多其他地区，相的急剧变化也反映了这一点。好。