Dear colleagues, It is with great pleasure that we extend an invitation to you for a session titled "Behavior and effects of volatiles in melts and fluids under extreme conditions" at the upcoming Goldschmidt2024 conference, set to take place in Chicago this August. Detailed information and the abstract submission portal can be accessed through [this link <https://conf.goldschmidt.info/goldschmidt/2024/meetingapp.cgi/Session/6172>]. Invited Speaker: Rajdeep Dasgupta (Rice University) We enthusiastically welcome submissions in the form of oral presentations or posters. If your ongoing research aligns with the thematic focus of our session, we would be honored to receive an abstract from you. The deadline for abstract submissions is March 29, and additional details can be found on the conference website. Thank you for considering our session. See you in Chicago! Yunguo Li, Anne Davis, Emma Stoutenburg, Bijaya B Karki, Huaiwei Ni Session 2c: Melts and fluids are crucial for mass and heat transfer in planetary interiors, and are essential for understanding the dynamics and evolution of terrestrial planets. Volatiles can dissolve in melts and fluids in varying amounts depending on pressure, temperature, and fugacity conditions, significantly altering their physical and chemical properties. For example, volatiles like water can significantly lower the melting temperatures of rocks, modify the melting/crystallization sequence, and affect element partitioning and isotope fractionation, which is vital for chemical differentiation in planetary interiors. The solubility, speciation, and migration of volatiles in melts control magma ingassing and degassing. This also influences the density, viscosity and conductivity, which are responsible for the Earth’s liquid core dynamo and the variability of volcanism. Therefore, a comprehensive understanding of the behavior and effects of volatiles in fluids and melts under high pressure and temperature conditions is crucial for various research domains in Earth and planetary sciences. This session will focus on various aspects of volatiles, melts, and fluids in terrestrial planets' interiors, ranging from the crust to the core through ancient times to modern periods. We welcome contributions on volatiles in melts and fluids, including but not limited to: structural and physiochemical properties of melts and fluids with volatiles; element partitioning and fractionation; crystallization and melting; magma degassing; density; elastic properties; diffusivity; viscosity; conductivity; and their effects on planetary processes occurring at depths. Experimental, analytical, and computational studies are welcomed, and interdisciplinary studies are especially encouraged.