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A close correlation between lithofacies and organofacies in meter-scale high-order cycles composed of lacustrine sediments enables comparison and refinement of lithofacies-defined cyclostratigraphy. Four lithofacies and four organofacies have been identified in fluctuating profundal high-order cycles in the lower-Permian Lucaogou Formation, southern Bogda Mountains, NW China. The four lithofacies include interbedded and interlaminated coarse siltstone and very fine sandstone, black shale, wackestone and dolostone, and calcareous and dolomitic shales. Four distinctive organofacies have been identified, on the basis of geochemical composition of organic matter and specific biomarker proxies related to organic matter types, rather than to depositional conditions and thermal maturity. The four organofacies are associated with the four lithofacies in the meter-scale high-order cycles, suggesting litho- and organo-facies may be genetically linked and may have been controlled by lake contraction and extension. The study shows that the lithofacies-derived and environment-defined high-order cycles can be delineated and substantiated by geochemical proxies-defined organofacies. This study also demonstrates that a holistic approach combining litho- and organic geochemical data is useful in reconstruction of meter-scale lacustrine cycles in a half-graben. 

Summary Adaptation of lipid membrane composition is an important component of archaeal homeostatic response. Historically, the number of cyclopentyl and cyclohexyl rings in the glycerol dibiphytanyl glycerol tetraether (GDGT) Archaeal lipids has been linked to variation in environmental temperature. However, recent work with GDGT‐making archaea highlight the roles of other factors, such as pH or energy availability, in influencing the degree of GDGT cyclization. To better understand the role of multiple variables in a consistent experimental framework and organism, we cultivated the model CrenarchaeonSulfolobus acidocaldariusDSM639 at different combinations of temperature, pH, oxygen flux, or agitation speed. We quantified responses in growth rate, biomass yield, and core lipid compositions, specifically the degree of core GDGT cyclization. The degree of GDGT cyclization correlated with growth rate under most conditions. The results suggest the degree of cyclization in archaeal lipids records a universal response to energy availability at the cellular level, both in thermoacidophiles, and in other recent findings in the mesoneutrophilic Thaumarchaea. Although we isolated the effects of key individual parameters, there remains a need for multi‐factor experiments (e.g., pH + temperature + redox) in order to more robustly establish a framework to better understand homeostatic membrane responses.