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Nano Texture and Mineralization in Fault Shear Zones
- SUN Yan, LU Xiancai, JU Yiwen
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2018, 24(3):
307.
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Nowadays nanoscience is pervasive, touching almost every professional field from information sciences to geosciences,
consequently, it has become a buzzword in our era. Over the past one decade, studies of nanogeosciences has all obtained rapid
progression on practice, theory and experiment at home and abroad. In this article, applying research methods of the 4F (Fact, Formation,Function and Formulation), the authors carried out specimen observation and synthetic for nanotexture and mineralization under scanning
electron microscope (SEM) and transmitting electron microscope (TEM). The authors firstly described a formation, development and
composition of shear shell (film), which widespreadly contribute on shear slip surfaces, in general, a brittle shear thin shell is thicker (h,
thickness reaching mm-cm grade) than a ductile film (h, cmm-mm grade). The former is caused by a kinetic friction-stick slip sliding, but
the latter is created by a static friction-creep slip sliding, and both of the shell and film all consist of nanominerals and nanotextures.
Then, the authors focused one's exploration to strain deformation and growth evolution on the nanotexture and nanoaction of the shear thin
shall (film) as regarding research principal part, and they are together with not only elastic feature but also viscous one rather than single
mechanic property. According to developing processes of the shear deformation, growth-development-evolution of the nonotexture can be
classified three deformation strain stages, i.e., strengthen (harden)-weaken (soften)-enbrittlement (degeneration), and corresponding with
three kinds nanoactions, i. e., nanocoating-nanoweakening-nanodelaminating.（1）The nanocoating is a mostly basic nanoaction, and so
long as shear slip remains a friction, it must bear the nanocoating in mature fault shearing (zone). Significantly, it can give rise to order
nanotexture and direct fabrication, including individual nanograin (commonly, diameter d=40-80 nm)-aggregate nanograin-multi
aggregate nanograin; nanograin-nanoline-nanolayer, as well as grain granulation-alienation-regeneration, etc.（2）The nanoweakening
results from particle-size reduction, flash heating, foliation development, and weaken mineral, etc., and it may be subdivided three
categories, i. e., slipping nanoweakening, rheological nanoweakening, and dynamic nanoweakening.（3）The nanodelaminating is a strip
which is induced by control from dynamic heating to static cooling, and its fission is commonly along a parting, cleavage and slip plane. In
summary, the three nanoactions with mutual fusion forcefully reflect an internal relation of a symbiosis feedback system between the
shear slip friction and nanoordered texture. Furthermore, we discussed a relation between the nanotexture and mineralization, taking the
Jinshan gold deposit and the Guangfeng talc deposit, Jiangxi Province as examples.（1）In the three stages of the gold-bearing mylonite
develop porcess, including a diagenesis, mineralization and formation foliation respectively caused by the nanocoating, nanoweakening
and nanodelaminating, an important case is that temperature of the ultramylonite can reach melt point 327℃ of the gold material during
the nanoweakening stage, thus, in the rheological process it may produce gold grain groups both a concentrated grain type (d, 15-35 nm)
and discrete grain type (d, 4-8 nm).（2）In the talc deposit, the higher strain strongly reflects the nanotexture and nanoaction much more.
During the nanoweakening stage, the nanosublayering, which results in a very thin thickness (only 10-15 nm) along the (001) slip plane,
local melt rheology and the delaminating even more creates an open stripping and parting. Through the researches mentioned above, the
authors have revealed“Earth materials with at least one dimension in the nano-orange are essentially ubiquitous”from an aspect.
Needless to say, a bigger curtain of the geosciences“nanoscience and technology: the next revolution in the earth sciences”exactly rises,
it moves towards to impel us to recognize some geological phenomena moreover, also urges us to exploit a“novel (or dramatic)”effect of
the“nano-orange”in the Earth materials.
