Abstract
Serpentines occur in ultrabasic dykes, ophiolitic complexes, melanges, etc.
The author has classified serpentinization, based on the above occurrences, into 4 types. Type A is the Serpentines that occurs in dykes, type B occurs in complexes, type C occurs in serpentine melanges, and type D occurs in the sedimentary melanges.
Further classification established 3 alteration grades of serpentinization. Alteration grade-I is the forming serpentinite (massive serpentine), alteration grade-II is forming of foliation or shearing by the tectonic movement, and alteration grade-III is the talc-chlorite alteration by the regional metamorphism.
It might be shown that hard constructions in the serpentine areas are owing to the alteration grade-II zone.
Chrysotile and antigorite in serpentinite causes serious unsymmetrical pressures and deformations in rocks, since they have the peculiar characteristics of swelling and viscosity, and that causes land-slides near land cuttings in Serpentine areas. Talc and Mg-chlorite, as clay minerals belong to the same Phyllosilicates, also show similar characteristics to Serpentinite. Mg-chlorite has characteristics of swelling. The axis perpendicular to the foliation plaine of the serpentinized rock is considered to be maximum principal axis of swelling pressure.
