A mechanistic approach for interpreting hydroclimate from halite-bearing sediments

Establishing accurate palaeo-hydroclimatic reconstructions from lacustrine and marine archives is a long-standing challenge in palaeoenvironment studies. Closed-basin evaporites, and especially halite, record episodes of extremely arid conditions during rapid climate change. However, the complex limnological behaviour of deep hypersaline water bodies and the stochastic nature of the hydroclimatic regime and its variations limit detailed palaeo-hydroclimatic interpretations from such records. Therefore, a mass-balance model was developed to explore hydrology-limnology-sedimentology relationships in hypersaline environments under both deterministic and stochastic approaches that generates synthetic halite-mud sequences. Applying the model to the Holocene Dead Sea halites yields novel insights into palaeoenvironmental conditions in the Levant. The deterministic framework indicates that: (i) under a series of similar hydroclimatic cycles, the thickness of each subsequent halite interval decreases, due to the depletion of dissolved-ions storage in the brine; (ii) halite deposition requires lake levels to drop below the minimal lake level of the preceding cycle; (iii) the time interval between halite deposition and the hydrological minimum is increasingly longer in subsequent cycles. Thus, counter-intuitively, halite deposition mostly takes place as water discharge increases, providing that the water balance is still negative. The stochastic approach produced random sequences comparable to the observed Dead Sea sedimentary record. It demonstrates that some hydrological minima are not represented by halite deposition at all. Furthermore, the thickness and number of halite beds at each hydrological cycle vary substantially, depending on the specific hydrological conditions realized. Finally, these results imply that the major Dead Sea level drop at the pre-Holocene deglaciation (ca 14 ka bp), previously assumed to be a record minimum, could not have been as pronounced as suggested, and must have been milder than the subsequent drop at the early Holocene (ca 11-10 ka bp).ISSN:0037-0746ISSN:1365-309

Large-scale cross-societal examination of real- and minimal-group biases

Biases in favor of culturally prevalent social ingroups are ubiquitous, but random assignment to arbitrary experimentally created social groups is also sufficient to create ingroup biases (i.e., the minimal group effect; MGE). The extent to which ingroup bias arises from specific social contexts versus more general psychological tendencies remains unclear. This registered report focuses on three questions. First, how culturally prevalent is the MGE? Second, how do critical cultural and individual factors moderate its strength? Third, does the MGE meaningfully relate to culturally salient real-world ingroup biases? We compare the MGE to bias in favor of a family member (first cousin) and a national ingroup member. We propose to recruit a sample of > 200 participants in each of > 50 nations to examine these questions and advance our understanding of the psychological foundations and cultural prevalence of ingroup bias