TY - JOUR T1 - Spatial distribution pattern of crystals and minerals in diorites from SE Birjand TT - آرایش فضایی بلورها و کانی‌ها در سنگ‌های دیوریت - کوارتزدیوریتی جنوب خاوری بیرجند JF - jsci JO - jsci VL - 12 IS - 2 UR - http://jsci.khu.ac.ir/article-1-1429-en.html Y1 - 2012 SP - 355 EP - 374 KW - Spatial distribution pattern (SDP) of crystals KW - crystal clustering KW - Birjand KW - Textural coarsening KW - Diorite N2 - In this research, based on spatial distribution and size of crystals, the role of physical processes affecting formation of the igneous rocks such as kinetics of crystallization (nucleation and growth of crystals), dynamics of magmatic systems (e.g. mixing and convection currents) and equilibrium processes such as textural coarsening are investigated. To this end, the spatial distribution pattern (SDP) of plagioclase, amphibole and quartz crystals were quantified in the microdiorite-quartz diorites and results were combined with petrography to discuss the factors affecting plagioclase packing arrangements and physical processes operated during formation of these rocks. The study area is located in 120 Km southeast of Birjand. The 8 thin sections of rocks were processed and geometrical features e.g. length, width and centre of 3098 crystals were measured. Then, R values (a descriptive value) were measured using nearest neighbor distance method with BigR and ArcGIS software's and the data were plotted against porosity (modal abundance of other phases in igneous rocks.) Results show that crystals have clustered SDP. The degree of plagioclases clustering is different in sections with change of crystal sizes and shapes. The origin of crystal clusters is likely to involve heterogeneous nucleation, textural coarsening and overgrowth of crystals. M3 ER -