A new flexible titanium foil cell for hydrothermal experiments and fluid sampling

Battery-free temperature logger for deep-sea hydrothermal fluids based on heat pipe heat exchangers and thermoelectric generators

Long-term in situ measurements of the temperature of hydrothermal fluids have great significance in the research of seafloor hydrothermal activities. Herein, we developed a self-powered battery-free temperature logger for measuring and recording the temperature of hydrothermal fluids. A gravity heat pipe made of titanium alloy was employed as the heat-conducting element of the temperature logger to capture heat from a hydrothermal vent and transfer it to the thermoelectric unit. The thermoelectric generator used herein converted the temperature difference into electrical energy to power the circuit of the temperature logger. Numerical analyses and experiments were performed to investigate the performance of the heat pipe and temperature logger. Results show that the temperature logger can realize self-powered starting at a temperature of >76 °C during a tank test. This paper presents a discussion on a new instrument for temperature measurements of deep-sea hydrothermal fluids.

Kinetically driven successive sodic and potassic alteration of feldspar

The dynamic evolutions of fluid-mineral systems driving large-scale geochemical transformations in the Earth's crust remain poorly understood. We observed experimentally that successive sodic and potassic alterations of feldspar can occur via a single self-evolved, originally Na-only, hydrothermal fluid. At 600 °C, 2 kbar, sanidine ((K_,Na)AlSi₃O₈) reacted rapidly with a NaCl fluid to form albite (NaAlSi₃O₈); over time, some of this albite was replaced by K-feldspar (KAlSi₃O₈), in contrast to predictions from equilibrium reaction modelling. Fluorine accelerated the process, resulting in near-complete back-replacement of albite within 1 day. These findings reveal that potassic alteration can be triggered by Na-rich fluids, indicating that pervasive sequential sodic and potassic alterations associated with mineralization in some of the world's largest ore deposits may not necessarily reflect externally-driven changes in fluid alkali contents. Here, we show that these reactions are promoted at the micro-scale by a self-evolving, kinetically-driven process; such positive feedbacks between equilibrium and kinetic factors may be essential in driving pervasive mineral transformations.

Note: An isobaric sample transfer apparatus for deep-sea pressurized fluid sample

This paper presents a novel isobaric sample transfer apparatus developed to facilitate the continuous culture of microorganisms while also providing the capacity for maintaining the sample at in situ pressure during the whole transfer and culture process. This apparatus is fitted to the isobaric fluid sampler which is used for collecting the isobaric fluid sample. This apparatus can not only avoid decompression in traditional sample transfer but also realize the integrated function of sample transfer and culture under isobaric conditions. The subsampling cylinder can automatically work as a flow culture reactor after completing the subsampling of the pressurized sample. Several transfer experiments were carried out to demonstrate this design which can make the period of transfer automatically.