FRICTIONAL PROPERTIES OF SERPENTINE MINERALS UNDER HYDROTHERMAL CONDITIONS
Serpentine minerals are among the minerals commonly found in the Earth's subduction zones,and their unique physicochemical properties have a significant impact on subducting geodynamics.Friction experimental studies of serpentine minerals are essential to gain a deep understanding of the frictional sliding stability of serpentine-containing faults in subduction zones as well as explaining the complicated misalignment behavior of faults in subduction zone.Previous laboratory research has produced an abundance of results,and this work addresses two main aspects:the stable states of occurrence and interconversion relationships of serpentine minerals,and the parameters affecting the frictional strength and sliding stability of serpentine minerals.First of all,studies on the stable endowment state of serpentine minerals and the interconversion relationship show that different types of serpentines diaplay different stable phases under different conditions.Chrysotile and lizardite are stable at low temperatures,and the stability fields of both chrysotile and lizardite roughly overlap,but chrysotile is in a substable state.Antigorite is stable at high temperature conditions,such as subduction zone mantle wedges containing high pore fluid pressure conditions,and undergoes a transition from lizardite to antigorite with increasing temperature.Secondly,studies on the factors controlling the frictional strength and sliding stability of serpentine minerals have shown that temperature,pore fluid,and the effective normal stress are all critical factors,for example,an increase in temperature can significantly increase the frictional strength of lizardite and chrysotile.In addition,the friction strength of serpentine minerals shows an obvious pressure dependence,and it was found through previous experimental studies that the friction strength of chrysotile exhibits a high-pressure sensitivity,and that the friction strength of antigorite gradually increases with increasing temperature under low fluid pressure conditions,showing an obvious temperature strengthening phenomenon.In contrast,the change in frictional strength of antigorite with temperature under high-pressure fluid pressure conditions is diametrically opposed to the results of low-pore fluid pressure conditions,which shows a clear temperature weakening phenomenon.Previous studies have also found that antigorite-undergoes a dehydration reaction with increasing temperature under lower fluid pressure conditions,and then exhibits unstable velocity weakening phenomenon,while antigorite exhibits velocity weakening phenomenon under low shear deformation rate under high-pressure fluid conditions.By analyzing the variation of friction-slip stability of antigorite with the shear slip rate can help us to better explain the phenomenon of subduction-zone slow-slip.Overall,experimental studies of the friction of serpentine minerals provide a key experimental basis for a deep understanding of subduction zone geologic processes.The results of these studies are scientifically important for predicting earthquakes and explaining the evolution of the Earth's internal tectonics and subduction zones,providing strong support for research and practice in the field of geosciences.
Serpentinefriction coefficientvelocity dependencefrictional stabilityslow slipsubduction zone
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