The development of a 70 m~80 m wide mylonite zone at mid-crustal depth in Archean granitoids in Fuxin area, Liaoning Province, have been studied. Syndeformational fluid-rock interaction produced substantial differences in mineral composition and bulk rock chemistry in the shear zone. The changes in whole rock chemistry, trace and rare earth elements indicate increase in mass fraction of K,Na,Ca,Sr,Ni,Co,Zr and REE, and decrease in mass fraction of Si,Ba,Cr with the REE patterns remaining unchanged. The authors recognized that the variation of immobile elements result mainly from volume deficiency, but the variation of mobile elements from fluid infiltration. Based on the volume loss expression C8/C0=1/(1-V), the fractional volume losses are 30% and 40% respectively for blastomylonite and mylonite schist. Based on the equation of fluid and rock N=L(Si)/C(Si)(f)(1-S)(), we obtain the ratio of liquid and rock of 11.8~59.4 and 14.8~73.9.
|Translated title of the contribution||Variation of composition and volume loss during mid -crustal mylonitization of late Archean granitoid, Fuxin area, Liaoning Province|
|Number of pages||6|
|Publication status||Published - 1999|
- Ductile shear zone
- Mid-crustal mylonitization
- Variation of composition
- Volume loss