Fluid inclusions in halite are widely used in research to determine the conditions of sedimentation in salt basins and reconstruct the chemical composition of seawater during a specific geological period. However, previous preliminary studies of the genetic types of inclusions, considered in the present research project, have not received due attention. Consequently, we decided to take into account the main distinguishing features of fluid inclusions in halite, belonging to various genetic types. The ultramicrochemical analysis (UMCA) method is one of the several methods that are used for the quantitative determination of the chemical composition of the primary fluid inclusions in halite. We have upgraded that technique, and that allowed us to reduce the analytical error rates of each component determination. The error rates were calculated in the study of Ca-rich and SO₄-rich types of natural sedimentary brines.

Achieving accurate chronostratigraphical correlation between late Cambrian sections in North China and sections from elsewhere in the world has been a long‐standing problem, largely owing to a lack of preserved or identified biostratigraphical marker fauna. Here, we examine trilobite occurrences, the sequence of facies and lithological change, and carbon and oxygen isotopes from the carbonate sequence of the Jiulongshan section, Shandong Province. Whereas regionally comparable sections are commonly unconformable coincident with the Kushan–Chaumitien formation boundary, we report the Steptoean Positive Isotopic Carbon Excursion (SPICE) event from an uninterrupted section recording a regressive–transgressive palaeoenvironmental fluctuation. Further, we place the onset and rise of the SPICE event within a high‐resolution, trilobite biostratigraphical framework, reporting, for the first time, Fenghuangella laevis from Shandong Province. Although correlating trilobite biostratigraphical relationships from China to the rest of the world has long been burdened by the endemism of Chinese taxa, the base of the Fenghuangella biozone corresponds with the base of the globally recognized Glyptagnostus reticulatus biozone, thus better demarcating the base of the Paibian Stage in North China.

Information on the associations of clay minerals in Upper Proterozoic and Phanerozoic marine evaporite formations suggests that cyclic changes in the (SO₄-rich and Ca-rich) chemical type of seawater during the Phanerozoic could affect the composition of associations of authigenic clay minerals in marine evaporite deposits. The vast majority of evaporite clay minerals are authigenic. The most common are illite, chlorite, smectite and disordered mixed-layer illite-smectite and chlorite-smectite; all the clay minerals are included regardless of their quantity. Corrensite, sepiolite, palygorskite and talc are very unevenly distributed in the Phanerozoic. Other clay minerals (perhaps with the exception of kaolinite) are very rare. Evaporites precipitated during periods of SO₄-rich seawater type are characterized by both a greater number and a greater variety of clay minerals—smectite and mixed-layer minerals, as well as Mg-corrensite, palygorskite, sepiolite, and talc, are more common in associations. The composition of clay mineral association in marine evaporites clearly depends on the chemical type of seawater and upon the brine concentration in the evaporite basin. Along with increasing salinity, aggradational transformations of clay minerals lead to the ordering of their structure and, ideally, to a decrease in the number of minerals. In fact, evaporite deposits of higher stages of brine concentration often still contain unstable clay minerals. This is due to the intense simultaneous volcanic activity that brought a significant amount of pyroclastic material into the evaporite basin; intermediate products of its transformation (in the form of swelling minerals) often remained in the deposits of the potassium salt precipitation stage.

Currently, fluid inclusions in halite have been frequently studied for the purpose of paleoclimate reconstruction. For example, to determine the air temperature in the Middle Miocene (Badenian), we examine single-phase primary fluid inclusions of the bottom halites (chevron and full-faceted) and near-surface (cumulate) halites collected from the salt-bearing deposits of the Carpathian region. Our analyses showed that the temperatures of near-bottom brines varied in ranges from 19.5 to 22.0 °C and 24.0 to 26.0 °C, while the temperatures of the surface brines ranged from 34.0 to 36.0 °C. Based on these data, such as an earlier study of lithology and sedimentary structures of the Badenian rock salts, the crystallization of bottom halite developed in the basin from concentrated and cooled near-surface brines of about 30 m depth. Our results comply with the data on the temperature distribution in the modern Dead Sea.