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Theory on Water Phase Transitions Controlling Hydrothermal Mineralization
Author(s) -
HU Baoqun,
Guxian LÜ,
WANG Fangzhang,
SUN Zhanxue,
GUO Tao
Publication year - 2014
Publication title -
acta geologica sinica ‐ english edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.444
H-Index - 61
eISSN - 1755-6724
pISSN - 1000-9515
DOI - 10.1111/1755-6724.12385_12
Subject(s) - chinese academy of sciences , beijing , china , library science , geomechanics , earth science , geology , engineering , geography , archaeology , computer science , geotechnical engineering
Taking the isobaric heat capacity (Cp) as the example, the study has calculated the physico-chemical properties changes of water on the phase transition curve, the critical point and the geothermal curves (Wagner et al., 2000). The method is from NIST WEBBOOK. (1) There are some sudden changes of water’s physicochemical properties on the phase transition curve (between 100°C and 374°C ), critical point and pseudo phase transition curve (between 374°C and 450°C). On the curve of gas-liquid phase transition (including the critical point) and pseudo phase transition in supercritical area, water physico-chemical properties will suddenly change, which are distinct from gradual change with small amplitude in no phase transition area. These physico-chemical properties changes between phase transition and no phase transition, make it to be possible bring mineralization matter in or out the water-bearing system. As shown in Fig.1. (2) It is necessary descending pressure caused by fracture in hydrothermal mineralization. There are no sudden changes (or mutations) of physico-chemical properties under the closed water-bearing system with the normal geothermal gradient. Fig.2 shows that according to the normal geothermal gradients, from shallow to deep in the lithosphere, the isobaric heat capacities are gradient change with the small amplitude by less than 10%, and no sudden changes appear. On the lines of geothermal curves 5 °C / km, 10 °C / km, 20 °C / km and 50 °C / km, the curves of isobaric heat capacities are similar. In the lithosphere, the condition with the mutation of water physico-chemical properties is that the temperature and pressure of water-bearing system are simultaneously on the phase transition curve and the critical point. Only some special geological environment can satisfy these conditions. The typical condition with pressure descending is fracture broken zone, and the typical condition with temperature increasing is magmatic activity. If the fracture and magmatic activity simultaneously occur in some areas HU Baoqun, LÜ Guxian, WANG Fangzhang, SUN Zhanxue and GUO Tao, 2014. Theory on Water Phase Transitions Controlling Hydrothermal Mineralization. Acta Geologica Sinica (English Edition), 88(supp. 2): 1616-1617.