Science in China Ser. D Earth Sciences 2004 Vol.47 No.12 1095 1101 1095 Copyright by Science in China Press 2004 On deposits controlled by tectonic lenses WANG Jincao 1 , XIA Bin 1 & JI Shaocheng 2 1. Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; 2. Department of Civil, Geological and Mining Engineering, Montreal Institute of Technology, P. O. Box6079, Station Centre-ville Montreal, Canada Correspondence should be addressed to Wang Jincao (email: wangjcyqc@163.com) Received April 8, 2002 Abstract By study of the typical tectonic lenses controlling some ore deposits, the tectonic lens boundaries may be classified into fuzzy boundaries, sharp boundaries and complex boundaries, and the metallostructures in tectonic lenses may be classified into vein-type, stock- work-type and breccia-type. After studying their metallostructures, we suggest the conception on tectonic lenses as an ore-forming system, realizing that the compact-function ore-forming system is made up of the lenticular weak-strain domain(Q) and its outside linear strong-strain belt(P). The ore-forming system, which is composed of four subsystems that coupled with each other and exert their system functions to the full, includes the dual-dynamical system made up of tectonic and fluid dynamics, the metallotectonic system controlled by hydrofracturing, the ore-source system made up of multi-substances and the mineral transportation system contacted by tectonic network. Deformational partitioning, hydrofracturing and tectonic pumping operate the consid- erable function while the system function practises. Finally the significance of metallotectonics on the tectonic lenses is discussed in the paper. Keywords: tectonic lenses, boundary type of tectonic lenses, type of metallostructures, tectonic lens as an ore-forming system. DOI: 10.1360/02yd0144 Tectonic lenses (e.g., boudinage structures, pinch-and-swell structures) are common geological structures observed in various scales ranging from several hundreds of kilometers (e.g., lenticular terranes or massifs) in orogenic belts to a few millimeters (e.g., core-mantle structures and porphyroclasts) in petro- graphic thin-sections. The most frequently observed tectonic lenses are those developed in metamorphic rocks where compositional layers with distinct rheological strengths coexist. No matter how the lenses are originated in tectonically compressional, shear or extensional regime, the competent rocks al- most always tend to form weak strain lenses due to the presence of rheological contrast between the compe- tent rocks and their surrounding matrix. The matrix flows around the lenses develop much more pro- nounced foliation and lineation, and are thus more intensively deformed than the lenses. Based on his investigations of Xishan (Western Mountain) in the Beijing area, Ma Xingyuan [1] classified the tectonic lenses into rhombus-shaped, lotus-root-shaped, trape- zoid-shaped and irregular ones according to their shapes that are assumedly controlled by their me- chanical behaviour during deformation. Microscopic tectonic lenses have been interpreted by Bell [2,3] ac- cording to the theory of so-called deformational parti- tioning, which actually takes account for a fact that a large bulk strain tends to be partitioned into progres-